dle. ; ‘ Z7 DA Ve VA I 3 choo (44 $ Summary Appraisals of the Nation's , Ground-Water Resources- Souris-Red-Rainy Region SURVEYKEPBQFESSIONAL PAPER 813-K Ps , TA «<-- on ea LLL as al N ”g“ “66-5 UNITED STATES vy & A e \\ X NORTH DAKOTA MINNESOTA ~\J""~ (“x ~ a/ 1 £, (z gey 0 Q‘Cv [ Sy JUN 2 9 1978 y], SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES- SOURIS-RED-RAINY REGION 12124 soreqs portup ay} 4q asouy} are umoys satiepunog jtup ap ut suofSay seoinosayf-1972 A( 10] saoinosay- 'g*n 'saag ay} 01 xopUI oryde18030 ay; fo sipsiniddy Xivumung 'g1g 13deq Kanmg *sore1g po 'saoinosay 4210» A W e sl D yal | uymvyh 0 ‘l C IA NVaIq@@INMVD IVMAVH 4 dojdoyo $401197 P &n i e1g 10dea s ) '§'D'S N \ ut srojdeyo se 'ssord ut 10 1ddISSISSIWN W wamot va d ATAD-DLLNVTILY HLAOS N _ suo1s2y saomosoy 1918 yo a Esuvt m ‘ NOLLVNYVTIX4 QmM-mHE3.m Washington, D.C. 20402 Stock Number 024-001 CONTENTS Page equivilents ...... [...... alel. o een, VI aap oo oe iman ine e nan ind K1 ne er.}. I Purpose and scope of this report..:...... I i Nel a o sooner nts s Pion aia aden, 2 | fegign'| Water SUPDIY -.. n 22. ine inl ciclo onan 2 round resalifees". =... n. .. pall alll 6 . ...s... sll od .ll... 7 Paleozoic aquifer ... 8 aquifer. 0.00. .l 9 Pierre aquifer....... 9 Fox Hills-Hell Creek l oan atin o ( 9 Foil Union aquifer... ___.. _ _tg lec .at 9 (add ese o n ae aie. moana ote... 10 uality offer ound vated to ...) im lae o uel oioi enn een n animie, 11 Role of ground water in water-resources management ...................... 12 Freshwaternee 0. 00. -~ 14 Irrigation: = =...... anl ce one toata e .. 14 Municipal} e cre n ae on ares aaa 16 Page Role of ground water in water-resources management - Continued ) Freshwater use - Continued | Domesticiand a naman cal. .l. .... K17 j (no osifigh s sura rate a. .._ 17 wise ... a t a al aat aet 17 ' Artificial recharge - .. colt na amana coin. ane o.. 18 | Replenishing freshwater AQUHETS :s. 3 rie Prien ni ell. 18 | Freshwater storage in saline AQUOS EAT s: ie. rier near ciec. 19 Liquid-waste disposal in saline aquifers .... 19 Ground-water @evelopment'...... af.! .._ C 20 Problems of OEVvelOPMENL :.]: nei reciever: reno 20 | C in .u 20 | Depletion of-streatuflaw l l...... ... 20 Deterioration of water nyse s nee e serene ds 20 Ground-water conservation ao. 2". al... .._ . 21 EBects:onithe ony ronment a..... cn ll ui. conn all...... 21 Information and ground-water management needs............................. 22 onn lo tn caisse o t.. 23 igen aed an anl. a n. l Dr 2T 24 ILLUSTRATIONS Page FroNTISPIECE _ Index map to chapters in Professional Paper 813. Figure 1.Location map of Souris-Red-Rainy iffaioupshowinggubbseing ..... MBK .L. . Cac. . _ _. K2 2.Location of former glacial lakes in the Souris-Red-Rainy Region: .m oo anc. a rein erica. as 3 3-7. Maps showing: 3. Average annual precipitation ...... 4 4. Average annual snowfall ..... 4 5. Average annual runoff ......... J 6. Average annual lake evaporation.... 5 2 nore esi . (ogy temel one taa n c c tee - 6 8. Diagrammatic section of North Dakota and Minnesota showing location of AGUIETS Aire rie eee rire ir anni ng 7 9-1 1.Maps showing: 9. Areal extent of bedrock ag uiter im. el teh nn porin ier fe cin re Avan aay. 8 10. Expected yields of individual Wells completed in drift....... :"} 10 11. Dissolved solids in ground water 13 12. Map showing areas with irrigation potential........................ 15 13-14.Diagrams of: 13. Direct methods of ae to t aoa aaa tat L 18 14. Indirect methods of as s coma ata esate eae e aa tink mon 19 v VI TABLE te w o t A . Projected irrigation in the Souris, Red, and Rainy Rivet DASIMS e err rre . Ultimate irrigation in each State in the Souris-Red-Rainy . Municipal water supplies in the Souris-Red-Rainy enn . Municipal, domestic, livestock, and industrial water supply in the Souris-Red-RAiny CONTENTS TABLES Page . Aquifers and well yields in the Sourie-Red-Rany Reflonss.:... .. ;... cats rare nnn at OTe 0 K8 . Description of aquifers, water quality, and water-supply potential in the Souris-Red-Rainy eens 12 . Advantages and disadvantages of ground water and surface water as sources of water supply in the e ount RedcBRainy Region.... pm glare. aman oor t L aa 00 14 Annee ies ENGLISH-METRIC EQUIVALENTS [Most measurements in this report are given in English units. Chemical concentrations are given only in metric units-milligrams per liter (mg/L). For concentrations less than 7.000 mg/ L., the numerical value is practically the same as for concentrations in parts per million] English unit Metricequivalent Inch (in) = 25.4 millimeters (mm) Foot (ft) = .3048 meter (m) Mile (mi) = 1.609 kilometers (km) Acre = 004047 _ square kilometer (km?) Square mile (mi?) = 2.590 square kilometers (km?) Gallon (gal) = 003785 - cubic meter (m') Cubic foot (ft) = .02832 cubic meter (m?) Acre-foot (acre-ft) = 1233 cubic meters (m?) Gallon per minute (gal/min) = .06309 liter per second (L/s) Cubic foot per second (ft/s) = 28.32 liters per second (L/s) Million gallons per day (Mgal/d) = .04381 cubic meter per second (m'/s) SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES - SOURIS-RED-RAINY REGION By HaroLtp O. REEpER ABSTRACT A broad-perspective analysis of the ground-water resources and present and possible future water development and management in the Souris-Red-Rainy Region is presented. The region includes the basins of the Souris River within Montana and North Dakota; the Red River of the North in South Dakota, North Dakota, and Minnesota; and the Rainy River within Minnesota. The region includes 59,645 square miles, mostly in North Dakota and Minnesota. The terrain is relatively flat, but ranges in altitude from 2,541 to 750 feet. Annual average precipitation ranges from 14 inches in the west to 28 inches in the east and about 75 percent of it is rain. The mean annual snowfall ranges from 32 inches in the west to 64 inches in the east. Temperatures range from -55° to 118° F (-48.3° to 47.8° C). Irrigation is needed at least part of the time to assure crop production, particularly in the western part of the region. Sand and gravel deposits in the drift form the most important freshwater aquifers. Other aquifers are found in at least parts of the region in the Precambrian, Paleozoic, Cretaceous, and Tertiary rocks. The poten- tiometric surface in the bedrock aquifers generally decreases in altitude toward the Red River of the North, indicating that the general direction of «ground-water movement is toward the river. Ground water with less than 3,000 milligrams per liter dissolved solids is available throughout the region. Ground water with less than 1,000 milligrams per liter occurs in most of the region east of the Red River of the North and in most of the shallow aquifers west of the river. The total volume of water available from storage having less than 3,000 milligrams per liter dissolved solids is estimated to be 5x 108 acre-feet. In addition to the fresh and slightly saline water, the region has abundant highly mineralized water that can be considered as a resource. Yields of wells in individual bedrock aquifers are generally less than 100 gallons per minute but locally yields may be as much as 500 gallons per minute and more. Yields in drift aquifers are frequently less than 100 gallons per minute but range from 5 to 1,000 gallons per minute. In a few places outwash yields more than 1,000 gallons per minute. Ground water is the sole or a primary source of water supply in much of the region, including supplies for irrigation, domestic and livestock, municipal, and industrial needs. Reportedly, the potential irrigation development is 1,550,000 acres, as compared with 50,200 acres in 1975. Both ground- and surface-water supplies would be required to meet these demands. Rural domestic and livestock water supplies are derived almost entirely from ground-water sources. Smaller communities and towns generally rely on ground water, and the cities and industries use ground water, surface water, or both. The municipalities using surface water generally depend upon reservoir storage. Water quality rather than quantity is the greater water-supply problem for many communities in the region. Increased demands on both ground-water and surface-water supplies likely will be made in the future. Storage of surface water in the ground-water reservoirs during times of surplus for withdrawal during times of scarcity would aid in meeting these demands. The surplus (flood) water is of better chemical quality than underlying ground water in parts of the western half of the region. Freshwater could be stored in saline- or freshwater aquifers, and pumped out later, as needed. Thus, the ground-water reservoirs have a definite present and potential role in water management. To understand the hydrologic system for management purposes there is a need to determine more adequately the geologic and hydrologic characteristics of existing aquifers and the location of new aquifers. Also, as pumping and other stresses on any part of the hydrologic system affect other parts of the system, monitoring programs ideally should be started and maintained to detect changes and determine effects of the stresses. Many alternatives are available for managing water in the region. Some of these are operational and others are undergoing research. Adequate hydrologic information is needed to aid in solving problems of water supply, use, and pollution. INTRODUCTION PURPOSE AND SCOPE OF THIS REPORT The purpose of this report is to present a broad-perspec- tive analysis - of ground-water resources in - the Souris-Red-Rainy Region. The region's ground water is a large and manageable resource that could have a more significant role in regional water development. This report is one of a U.S. Geological Survey series that summarizes information on the Nation's ground water for the guidance of planners. New data were not collected for this appraisal, but information from many sources has been utilized. In addition to summarizing the knowledge of ground-water resources of the region, the report points out deficiencies in knowledge. The primary objective of evaluating information deficiencies is to direct attention to types of studies and information that will lead to fuller understanding and description of ground-water reservoirs for better evaluation, planning, and management of the region's water resources. With proper knowledge, utiliza- tion, and conjunctive management of all water resources, ground water can assume greater significance in the region's development. K1 to (3 (4 K2 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES PHYSICAL SETTING The region is located along the northern boundary of the United States in North Dakota and Minnesota and extends short distances into Montana and South Dakota (fig. 1). The region discussed in this report includes that part of the three river basins within the United States. The region, which includes 59,645 square miles in the United States, drains northward into Hudson Bay. The Red River of the North, hereafter referred to as the Red River, drains 39,199 square miles in the central part of the region and flows into Lake Winnipeg and Nelson River to Hudson Bay (all in Canada and not shown on map). The Souris River drains 9,142 square miles in the western part of the region, joins the Assiniboine River in Manitoba, Canada, and flows into the Red River. The Rainy River drains 11,304 square miles in the eastern part of the region, flows through Lake of the Woods to the Winnipeg River in Canada, and eventually joins the Nelson River in Canada. The three river basins in the United States are in the Western Lake section of the Central Lowland physiographic province (Fenneman, 1931). The terrain is relatively flat. One of the most prominent features is the plain along the Red River from 30 to 50 miles wide and 315 miles long. During the glacial epoch the Red River was occupied by glacial Lake Agassiz (fig. 2). Its outlet 104° 100° was southward into Big Stone Lake (outside the region) and through the present valley of the Minnesota River. Altitude ranges from 2,541 feet in north central North Dakota to 750 feet where the Red River crosses the Canadian boundary. Figure 2 Also shows the location of other former glacial lakes in the region. REGIONAL WATER SUPPLY Precipitation is the ultimate source of water supply. Average annual precipitation in the region ranges from about 14 inches in the west to 28 inches in the east (fig. 3). About 75 percent of the annual precipitation is rain. The mean annual snowfall ranges from about 32 inches in the west to 64 inches in the east (fig. 4). Precipitation is adequate for crop production during normal years, although the western half of the region has occasional droughts. The average annual natural runoff originating within the region ranges from less than 0.2 inch in the western part of the Souris River basin to about 15 inches in the eastern part of the Rainy River basin (fig. 5) owing to less precipitation and a higher evapotranspiration rate in the west than in the east. Generally, minimum flows occur during the winter under ice cover 2 to 4 feet thick. Maximum flows generally occur during the spring breakup, and about 50 percent of the annual flow occurs during April and May. 96° 92° | 49° 47° Base from Souris-Red-Rainy River Basins Commission, 1972 | I Souris River basin W Red River basin won min i _- -- Rainy River basin I | LOCATION MAP 0 100 MILES 0 100 KILOMETERS Figure 1.-Souris-Red-Rainy Region, showing subbasins. 49° SOURIS-RED-RAINY REGION K3 104° A I 3 "\ Z 47° Base from Souris-Red-Rainy River Basins Commission, 1972 | i ( wisconsin \ MINNESOTA \ l A LOCATION MAP 0 100 MILES 0 100 KILOMETERS FIGURE 2.-Location of former glacial lakes in the Souris-Red-Rainy Region. The quantity and quality of water resources differ greatly from place to place, season to season, and year to year. In the Souris River basin, streamflow is normally inadequate to satisfy water needs, and the quality is marginally acceptable for most present uses. During normal years, streamflow in most of the Red River basin is adequate, and the quality is generally satisfactory for the predominantly agricultural demands of the basin. However, water quality in the main stem of the Red River is poor due to heavy sediment loads; periodic low flows with attendant increases in dissolved solids; and increasing municipal, industrial, and agricultural polution. Water is abundant for the extent of present development in the Rainy River basin, and, except below International Falls and Shagawa Lake at Ely, its quality is excellent for most uses (U.S. Water Resources Council, 1968, p. 6-8-3). The glacial aquifers and much of the bedrock are recharged by water from precipitation within the region. Some ground-water recharge is from surface-water bodies and from bedrock aquifers of adjacent regions. Recharge to the ground-water reservoirs from precipitation can occur only after the soil moisture deficiency is satisfied. Water requirements of plants and the intensity and duration of a rain, and certain additional factors such as soil type, also affect the amount of recharge. Consequently, recharge is not necessarily proportional to rates of precipitation, although when the precipitation rate is large, recharge is generally greater than during relatively dry periods. Recorded temperature extremes range from -55° to 118° F (-48.3° to 47.8° C); however, mean monthly temperatures range from a monthly minimum of about -10° F (-23.3° C) in January to a monthly maximum of about 85° F (29.4° C) in July (U.S. Geological Sutvey. 1970. p. 104-107). The occasional droughts, hot winds, and prolonged high temperatures that occur, particularly in the western half of the region, cause crop failure and create the need for irrigation at least part of the time. Large quantities of ground water evaporate through the swamps, marshes, lakes, and streams. The average annual lake evaporation rate ranges from 36 inches in the west to less than 24 inches in the east (fig. 6). Discharge from aquifers occurs naturally and by pump- ing. Natural discharge occurs by flow into adjacent rocks having lower hydraulic head, by seepage into streams, as springs, and by evapotranspiration. Trends in water levels reflect the balance or imbalance of ground-water recharge and discharge. Current pumping is not large enough to cause a significant general impact. Significant water-level declines are noted, however, in several areas (Kenmare, Minot, Fargo-West Fargo-Moorhead, and Hatton areas). Ground water constitutes a major element of the region's water supply, as discussed in detail in the following section. SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES 92° 100° I & MANITOBA Pembin® *s, s Ner 49° Fey Lf cananA © as < "*, UNITED STATES River l es orac Rive" Devils Lake _ Bier ~A 6* 20k, i e Grand 097 vow w. Shey aim“ % Hardh_ &,) Sandhill_ gy. NORTH 47° |- EXPLANATION 20 Line of equal average annual precipitation, in inches. Interval 4 inches From U.S. Department of Commerce, Environmental Science Services & / LOCATION MAP Administration, 1968 0 100 MILES Base from Souris-Red-Rainy River Basins Commission, 1972 8 100 KILOMETERS 1 | [ \ FIGURE 3.-Average annual precipitation. 104° 96° 92° 49° * < 1g 3 E 1§ 3 | 47° |- EXPLANATION 32 + NORTH Line of equal average annual snowfall, DAKOTA in inches. Interval 32 inches soUTH 3%, From U.S. Geological Survey, 1970 DAKOTA LOCATION MAP 0 100 MILES 0 100 KILOMETERS Base from Souris-Red-Rainy River Basins Commission, 1972 I 1 FigurE 4. -Average annual snowfall. 47° SOURIS-RED-RAINY REGION K5 a 2 I * A _ NORTH *) WiQ yer ( WISCONSIN Line of equal average annual runoff, . _ DAKOTA c ® F C amnesors ! 5 a z =% INNESOTA \, in inches. Interval variable soum *, %] Amrt | 1 & From Busby, 1966 DAKOTA g ‘0 S + $ % X LOCATION MAP 0 100 MILES : a: 0 100 KILOMETERS Base from Souris-Red-Rainy River Basins Commission, 1972 EXPLANATION f S | Figure 5.-Average annual runnoff. 104° 100° | "B w 93 MANITOBA r % @ ___ Canapa) j : * +, UNITED STATES NY \ & 53s i x River \ Lores “W“ ~ % wigs Sandhill #. < a TA I 47° |- ¢ Fargo EXPLANATION $0 antee NORTH DAKOTA (‘ Line of equal average evaporation, SOUTH DAKOTA \ unnesors ! wisconsin in inches. Interval 2 inches \ \ From Kohler, Nordenson, and Baker, 1959 tp. y % LOCATION MAP 0 100 MILES Base from Souris-Red-Rainy River Basins Commission, 1972 0 100 KiLOMETERS | | lt] FiGure 6.-Average annual lake evaporation. M K6 SUMMARY APPRAISALS GROUND-WATER RESOURCES Ground water in the Souris-Red-Rainy Region is ob- tained mainly from aquifers in Pleistocene drift such as drainage-channel deposits, lake deltas, beach deposits, outwash deposits, and small bodies of sand and gravel interbedded with till. In addition, the Souris and Red River basins in North Dakota have aquifers of Precambrian and Paleozoic age; the Dakota, Pierre, and Fox Hills-Hell Creek aquifers of Cretaceous age; and the Fort Union aquifer of Tertiary age (Crosby and others, 1973, p. 176). In the Red and Rainy River basins in Minnesota, aquifers are of Precambrian, Paleozoic, and Cretaceous age. The total volume of water having less than 3,000 mg/L of dissolved solids available from storage in the region is estimated to be 5x108 acre-feet. The estimate is based on areas, estimated and known saturated thicknesses, and estimated and known values of specific yields of the various aquifer materials. by a series of bedrock units that and in hydrologic characteristics om Precambrian to Quaternary. urface The region is underlain differ greatly in thickness and that range in age fr Precambrian crystalline rocks are at or near the land s 104° (about 1,300 feet a OF THE NATIONS GROUND-WATER RESOURCES bove mean sea level) locally in the eastern part of the region and about 15,000 feet below the surface (about 12,000 feet below mean sea level) in the center of the Williston Basin (figs. 7 and 8). The central and deepest part of this basin is in the westernmost part of North Dakota, southwest of and beyond the limits of the Souris River basin (fig. 7). Most of North Dakota, including the Souris and the western. part of the Red River basins, is in the Williston Basin, which extends northward into Canada, southward into South Dakota, and westward into Montana. Sedimen- tary rocks of Paleozoic, Cretaceous, and Tertiary age occupy the Williston Basin. These strata gradually thin toward the east and are missing in the southern and eastern parts of the Red River basin and in the Rainy River basin, where Precambrian rocks directly underlie the glacial deposits (fig. 8). The oldest Paleozoic beds dip westward at an average slope of nearly 50 feet per mile across the eastern three-fourths of North Dakota, but the Tertiary beds dip westward at only a few feet per mile (Crosby and others, 1973, p. 176). Sedimentary rocks of Ordovician age overlie the crystalline rocks in most of the Red River and Souris 100° 49° 47° 100 MILES 100 KILOMETERS Base from Souris-Red-Rainy River Basins Commission, 1972 River Forest “w” & Grands VOW Forks Hatton\_ /; Sendhil V‘Wfi C A \ MINNESOTA \\ 1 \ LOCATION MAP I Figure 7.-Location of the Williston Basin. SOURIS-RED-RAINY REGION K7 I MINNESOTA ’ NORTH DAKOTA AQUIFERS I l Quaternary E Tertiary Sea level datum Modified from Carlson Dakota and Anderson, 1973 Jurassic EXPLANATION Triassic T] Aquifers (Paleozoic aquifers delineated as a unit) D Non-water-yielding strata Paleozoic FEET - METERS 0-4-0 < Vt» 1000 N z -s oC 500 Pre- § |- norm \" £ ,~ g 2000 cambrian DAKOTA _ || 3a 2 4" 6 ¢ {3 O 3000 1000 3 t = muses st onf . ; g Wes ! south pakora Y @ _ | # 4000 I | ins VERTICAL SCALE FIGURE 8. -Diagrammatic section of North Dakota and Minnesota showing location of aquifers. River basins, sloping and thickening westward. Rocks of Jurassic and Cretaceous age, which thicken westward from the west border of Minnesota overlie the Paleozoic rocks. Tertiary rocks occur on the west edge of the Red River basin and in much of the Souris River basin (Glover and others, 1973). The entire region has been glaciated, and most of it is covered with drift that ranges in thickness from less than a foot to several hundred feet. The drift is largely till, a heterogeneous mixture of clay, silt, sand, and gravel, but it also contains buried lenses of stratified sand, gravel, silt, and clay, which were deposited along the margin of the glacier or near it. The buried sand units, which range in thickness from a few inches to many feet, cover areas of many square miles. Lake Agassiz sediments significantly affect the hydrologic system in the Red River basin because they are extremely fine grained, thick, and widespread. The thickness of these sediments in the Minnesota part of the lake deposits ranges from less than 1 foot to more than 140 feet (Maclay and others, 1972, p. 29), Small well yields are obtained from bedrock aquifers underlying the drift in the Souris and Red River basins. In parts of the Rainy River basin, where productive glacial deposits are thin or absent, small yields of water are obtained locally from fractures in the crystalline bedrock (Glover and others, 1972, p. B-27, B-52, B-77). Yields of wells in individual bedrock aquifers are generally less than about 100 gal/min but may be as much as 500 gal/min locally, and more than 500 gal/min in a few places. Yields in drift aquifers average less than 100 gal/min but range from 5 to 1,000 gal/min. A few wells in outwash yield more than 1,000 gal/min. Table 1 is a list of aquifers and range of yields to wells. The potentiometric surface in the bedrock formations generally decreases in altitude toward the Red River, indicating that the regional direction of water movement is toward the river. In the Rainy River basin, some ground water probably migrates westward into the Red River basin; but most ground water moves northwestward and is discharged from the area through the Rainy River and Lake of the Woods (Glover and others, 1972, p. B-53, B-77). These regional patterns of movements of the ground water indicate that recharge from precipitation on upland areas, from surface water, and from ground water entering from adjacent regions moves regionally to discharge areas along the Red River Valley. The general ground-water flow system is much more complex because of the many local flow patterns within the regional system. Much of the ground-water discharge occurs near recharge areas within the region (Maclay and others, 1972, p. 104-113). PRECAMBRIAN AQUIFER Precambrian crystalline rocks, which underlie all of the region, generally are poor aquifers, but locally are sources of small supplies. Along the southeastern edge of North Dakota, and in the eastern part of the Red River basin in Minnesota and in most of the Rainy River basin (fig. 9), small supplies of water can be obtained from the fractures or M K8 from weathered zones in the upper part of the crystalline rocks. Generally, wells in the Precambrian aquifer will not yield more than a few gallons per minute (Crosby and others, 1973, p. 176). The Precambrian rock surface also generally defines the base of the water-yielding zone of the hydrologic system. The general slope of the crystalline rock surface is from east to west (Maclay and others, 1972, p. 23). (See figure 8.) PALEOZOIC AQUIFER Water occurs in the Paleozoic rocks in the Souris River basin and in most of the Red River basin (fig. 9), but in places it is highly saline. Although there are several water-bearing units within the Paleozoic rocks, data are insufficient to determine the areal extent, thickness (except locally), and degree of interconnection of the individual units; therefore, all water-bearing Paleozoic rocks are treated here as a single aquifer. The top of the aquifer occurs at depths of about 150 feet in eastern North Dakota and deepens westward to more than 13,500 feet at the bottom of the aquifer in western North Dakota, beyond the limits of the region (figs. 7 and 8). It is composed of fine-grained sandstone which yields small dependable supplies of water; and porous, cavernous limestone, which yields large supplies of water. The salinity of the water, however, severely limits its usefulness. Produc- 104° 100° E | SASKATCHEWAN 49° NORTH DAKOTA EXPLANATION 47° |- Fort Union aquifer Dakota aquifer Cretaceous undifferentiated in Minnesota Paleozoic aquifer rax" rar ~" Fox Hills-Hell Creek aquifer Pierre aquifer Precambrian aquifer Base from Souris-Red-Rainy River Basins Commission, 1972 SUMMARY APPRAISALS OF THE NATH V\,_ 7 A./ r—soum DAKOTA (“500mm Leq \ MINNESOTA \ | I LOCATION MAP Mcédifiid froan: T rosby and others, 1973 Glover and others, 1972 0 100 MILES Maclay and others, 1972 k—r—l—r—qi—v—Lr—J—J 0 100 KILOMETERS ONS GROUND-WATER RESOURCES TABLE 1.-Aquifers and well yields in the Souris- Red- Rainy Region [Bedrock aquifers adapted from Crosby and others (1973, p. 176-185) and Glover and others (1972, tables B-10, B-16, B-24). Glacial drift aquifers adapted from Glover and others (1972, tables B-11, B-12. B-17, B-18, B-19, B-24) and Q. F. Paulson (written commun., 1976)] Well yields (gal/min) Aquifer Common General Largest rate pumped range known DFIHE .... 3s ere ares afa sna anne <100 5-1,000 > 1,000 FOIt UNION ...... 2-4 < 1-50 100 Fox Hills-Hell Creek ......» <5 <1-30 150 PIGETTE viven reer arate <5 <1-6 100 2-3 < 1-350 500 Paleozoi¢ ..> <5 <1-60 700 PrEC@MbDTIN ...... <5 <1-10 tion of water in eastern North Dakota is limited to one industrial well that flows, when not closed, at a rate of about 700 gal/min, and a few domestic wells that are used for sanitation. Water from the Paleozoic aquifer also is produc- ed with oil in the western part of the region (Crosby and others, 1973, p. 177). Because of the highly saline water, the Paleozoic aquifers in Minnesota have never been used. Test holes into the Paleozoic rocks have flowed as much as 60 gal/min (Maclay and others, 1972, p. 60). 92° te» Figure 9.-Areal extent of bedrock aquifers in the Souris-Red-Rainy Region. ana- SOURIS-RED-RAINY REGION DAKOTA AQUIFER The Dakota aquifer, which is composed of basal Cretaceous sandstone and shale, underlies all of the Souris River basin and the western half of the Red River basin (fig. 9). Aquifers in Cretaceous rocks, which probably are equivalent to the Dakota aquifer, underly the northwestern Red River basin in Minnesota. The depth to the top of the aquifer gradually increases from 100 feet along the eastern limit of the aquifer in the Red River basin to more than 5,600 feet in the deepest part of the Williston Basin southwest of the Souris River basin (fig. 8). The aquifer materials differ from place to place, but generally consist of interbedded quartzose sand and shale. Sand predominates in the eastern part of North Dakota and shale predominates in the western | part. In the eastern part of North Dakota, the individual sand beds generally are less than 30 feet thick, but locally are as much as 100 feet thick. They generally are composed of fine, medium, or coarse sand that has very little interstitial silt or clay. Interstitial silt and clay decreases permeability of the aquifer and, thus, decreases well yields and the rate of flow of water through the aquifer. In the western part, individual beds generally are composed of fine sand and minor amounts of medium sand, and interstitial silt and clay are more common (Crosby and others, 1973, p. 178). Numerous wells tap the Dakota aquifer in the eastern part of North Dakota. Most of these wells are for domestic and stock use but a few are for municipal and industrial purposes. Flowing wells in the Dakota have discharges that range from less than 1 to 100 gal/min and average 2 to 3 gal/min in most of the Souris-Red-Rainy Region. Pumping rates in excess of 500 gal/min are obtained from some wells (Crosby and others, 1973, p. 179). In the Souris basin part of the region potential well yields range from 50 to 350 gal/min. This water is used mostly by the oil industry for maintaining pressure in oil reseservoirs (Glover and others, 1972; p. B-31). PIERRE AQUIFER The Pierre aquifer is in the upper part of the Pierre Shale of Cretaceous age in the castern part of the Souris River basin and the western part of the Red River basin (fig. 9). The aquifer may extend westward for a short distance beneath the Fox Hills-Hell Creek aquifer, but no data are available to determine the western limit accurately. The Pierre is composed of light-gray to black siliceous shale, marlstone, and claystone, and is locally fractured in the upper part. Unfractured shale, marlstone, and claystone are nearly impermeable and will not yield a significant amount of water to wells; therefore, the fractured zones are the only sources of water. The fractures, where present, may extend several hundred feet below the land surface, but they generally are too small to yield significant quantities of water below depths of about 100 feet (Crosby and others, 1973, p. 180). K9 Although the Pierre is not a major aquifer, it is the only source of water for many farms and a few municipal supplies. Most farm wells yield less than 6 gal/min. Locally, where the fracture zone is exceptionally thick or the fractures are unusually large, pumping rates range from 50 to 100 gal/min (Crosby and others, 1973, p. 180). FOX HILLS-HELL CREEK AQUIFER The Fox Hills-Hell Creek aquifer of Cretaceous age underlies most of the Souris River basin (fig. 9). The depth to the top of the aquifer gradually increases from a few feet in topographically low areas near the eastern boundary of the aquifer to more than 1,400 feet in topographically high areas near the center of the Williston Basin southwest of the Souris River basin (figs. 7 and 8). The aquifer is composed of interbedded sand, clay, silt, and lignite, but the lithology differs considerably from place to place. Many of the individual sandy layers in the aquifer are thin and lenticular and do not extend for more than a few miles. However, at least one, and commonly more than one, sandy layer more than 20 feet thick is present. Generally, the individual sandy layers are composed of fine to medium sand with inter- bedded silt and clay lenses, but locally the sandy layers may be either very fine sand or include considerable amounts of interstitial silt (Crosby and others, 1973, p. 180). Wells in the Fox Hills-Hell Creek aquifer generally yield less than 30 gal/ min; but locally, where the sandy layers are unusually thick or contain very little interstitial or inter- bedded silt or clay, yields may be as much as 150 gal/min. Most of the water is used for rural domestic and stock purposes (Crosby and others, 1973, p. 181 FORT UNION AQUIFER Sand and lignite beds in the Fort Union Formation of Tertiary age form the Fort Union aquifer in the western two-thirds of the Souris River basin (fig. 9). The Fort Union, which may be as thick as 1,100 feet near the center of the Williston Basin, is composed of beds of silty clay, clay, sand, and lignite. Individual beds in the formation generally cannot be traced as much as a mile; however, a few exceptionally thick and extensive beds extend many miles. Most sand beds are less than 10 feet thick, but some are as much as 150 feet thick. Lignite beds generally are 2 to 5 feet thick, but thicknesses of as much as 40 feet have been reported. The sand is generally fine, with medium sand reported locally. The sand also may contain considerable amounts of interstitial clay (Crosby and others, 1973, p. 181-182). The nonmarine Tongue River Member of the Fort Union Formation, stratigraphically in the upper part of the formation, is the principal bedrock aquifer in the Souris River basin. The underlying marine Cannonball Member yields water that is used for watering livestock but that is generally too salty for human consumption, according to Glover and others (1972, p. B-27). Although there may be E K10 SUMMARY APPRAISALS OF THE NATI several aquifers in the Fort Union Formation, data generally are insufficient to determine the areal extent, thickness, or degree of interconnection of the units; therefore, all water-bearing units in the Fort Union are considered here as a single aquifer. The quantity of water the Fort Union aquifer will yield to wells depends on (1) the thickness, sorting, and grain size of the sand beds, and (2) the quantity of interstitial or interbedded clay near each well. Properly constructed wells finished in sand beds as thick as 100 feet will yield as much as 50 gal/ min with 20 feet of draw-down. A few wells will yield as much as 100 gal/min, but drawdowns are greater than 20 | feet. Most wells that tap the Fort Union aquifer are used for rural domestic and stock supplies. Some wells, however, are used for municipal and industrial supplies. Most farm wells are completed in the uppermost saturated sand lens. The wells commonly are equipped with cylinder pumps generally having capacities of only 2 to 4 gal/min (Crosby and others, 1973, p. 182). DRIFT AQUIFERS age, which are the most water in the region, are f the Souris and Red River er basin. Although most of d of several tens to several Drift aquifers of Quaternary important sources of ground distributed throughout most 0 basins and part of the Rainy Riv the drift in the region is compose 104° 100° ON'S GROUND-WATER RESOU RCES hundred feet of till, which yields little or no water to wells, some of the drift consists of stratified sand and gravel which form important sources of water supply (Crosby and others, 1973, p. 183). In the Rainy River basin, however, glacial erosion rather than deposition was the primary process shaping the surface of the land, and the deposits are thin or absent, except in the south and west parts of the basin where the glacial deposits thicken to nearly 250 feet (Glover and others, 1972, p. B-77). Figure 10 shows the areal distribution of known major drift aquifers and the expected yields to wells of water having less than 3,000 mg/L of dissolved solids. Ranges in yields to wells in the various aquifers delineated in figure 10 have been simplified from those tabulated by Glover and others (1972). Most of the aquifers are either valley fill or outwash deposits. Melt water flowing from and along the ice front deposited outwash and ice-contact deposits in a network of channels. During subsequent periods of glacial advance and retreat, old channels were blocked and new ones formed. Each successive advance of glacial ice smoothed the terrain by filling the valleys and eroding the hills. Parts of these channels were subsequently filled with sand, gravel, and till, such as in the New Rockford aquifer in east-central North Dakota. Some of these glacial channels are now occupied by modern streams, as illustrated by the Sheyenne River valley in southeastern North Dakota. Deposits in these channels 92" l g SASKATCHEWAN 49° [ ~~~. W- UnNiED STATES EXPLANATION Expected yields, in gallons per minute 0-50 50-500 More than 500 Modified from Glover and others, 1972 47° south \, DAKOTA Base from Souris-Red-Rainy River Basins Commission, 1972 MANITOBA I Rose, International +_ ___ Fal go Rany: » papid )/ «z River 3 { ( wIscONsIN \ minnEsOTA \ LOCATION MAP 100 MILES 100 KILOMETERS FigGurE 10.-Expected yields of individual wells. SOURIS-RED-RAINY REGION form numerous aquifers scattered throughout the Red and Souris River basins and the western part of the Rainy River basin as shown by the long narrow patterns in figure 10. Many of the earlier channels were buried by subsequent glacial deposits, and most of the glacial channels exposed at the surface were formed during the most recent advance of glacial ice. Outwash deposits in these youngest channels are generally thin, and only locally form significant aquifers. The deposits in glacial Lake Agassiz, in the center of the Red River basin, occupy almost one-third of the area of the ! basin (fig. 2). These deposits are generally too fine grained to be important as a source of ground water. However, some | lakeshore deposits, such as deltas and beach ridges, are coarse grained and form important aquifers (Glover and others. 1972. p. B-29, B-53). The Sheyenne delta aquifer in the southeast corner of North Dakota is a notable example (Glover and others, 1972, p. B-62). Fine-grained sediments also were deposited in glacial Lakes Cando and Dakota, and glacial Devils Lake in the western part of the Red River basin and in glacial Lake Souris in the Red and Souris River basins (fig. 2). Alluvium deposited after the glacial periods consists of silt, sand, and gravel in the valleys of some of the larger streams. These deposits generally are finer grained and less permeable than the outwash deposits, but locally they are sources of water. The ability of the deposits to yield water to wells depends on the grain size and thickness of the materials, but in broad view and ultimately the quantity of water that an aquifer will yield depends on the amount of water in storage and on the amount of recharge. If a sand or gravel deposit is small and enclosed in till or other fine-grained material, it receives little recharge; consequently, such deposits will not yield large quantities of water for sustained periods. Large deposits of saturated sand and gravel, however, contain large quantities of water in storage and may be capable of receiving sustained quantities of recharge over the large area of contact with the clay layers even if they are enclosed within fine-grained deposits; consequently, such deposits form major aquifers that will yield substantial quantities of water for sustained periods (Crosby and others, 1973, p. 183). QUALITY OF GROUND WATER The chemical quality of water can be classified according to its dissolved-solids concentration. The classification of Winslow and Kister (1956, p. 5) used by the U.S. Geological Survey is as follows: Class Dissolved solids (mg/L) errr nisi siren nie. less than 1,000 Slightly Salines..::.5.:: 9.0 30. 1,000- 3,000 Moderately salinge...........al....;.... ... 3,000-10,000 Very saline ..:... ..:... ... anglo lal, 10,000-35,000 if ars . oal more than 35,000 | | | | | K11 Figure 11 shows areas in the Souris-Red-Rainy Region where ground water occurs with less than 1,000 mg/L and with 1,000 to 3,000 mg/L dissolved solids. Ground water with less than 3,000 mg/L dissolved solids is available throughout the region; however, yields may be small. In addition to the fresh and slightly saline water, the region has abundant highly mineralized water. Robinove and others (1958, p. 9) stated that many of the formations in North Dakota are capable of yielding only very small supplies of water. The Pierre Shale, for example, yields only minor amounts of saline water to many wells in the eastern part of North Dakota. Table 2 lists and describes water-yielding formations and their water-quality and water-supply potential. The quality of ground water in the Souris-Red-Rainy Region differs from place to place, even within an aquifer. Generally, water with the best quality is in or near recharge areas or areas with flow sufficient to flush out saline water. Water in surficial outwash in or near recharge areas almost everywhere contains less than 1,000 mg/L dissolved solids and in many places less than 500 mg/L. Highly mineralized water is found in older, deeper rocks in much of the region and in shallow aquifers where water has migrated from mineralized aquifers. For example, in the north-central part of the Red River basin, highly mineralized water migrates upward into the drift from the underlying Paleozoic and Dakota aquifers. Water in the drift in these areas generally is a sodium chloride type, with many of the characteristics of the water in the underlying bedrock (Crosby and others, 1973."p. 195). In the Pierre aquifer, water is a sodium chloride or sodium sulfate type or a combination of the two. The ° dissolved-solids concentration ranges from 700 to 12,500 mg/L, and the shallow fractured zone generally yields water with 2,000 to 4,000 mg/L dissolved solids. Most of the water in the Pierre aquifer contains greater quantities of chloride or sulfate, or both, than the limits for drinking water recommended by the U.S. Public Health Service (1962). The Pierre is not a highly productive aquifer, but it is the only source of water for many farms and a few municipalities (Crosby and others, 1973, p. 194). Water in the Fox Hills-Hell Creek aquifer generally is a sodium bicarbonate type, but locally the water is a sodium sulfate type. Although water from the Fox Hills-Hell Creek aquifer ranges from about 300 to 3,700 mg/L dissolved solids, water containing less than 1,000 mg/L dissolved solids occurs near outcrop areas, where little drift overlies the aquifer. Most of the water that contains more than 2,500 mg/L of dissolved solids occurs where significant thicknesses of drift cover the Fox Hills-Hell Creek aquifer. The drift probably contributes much of the dissolved-solids concentration to recharge water that reaches the Fox Hills-Hell Creek aquifer (Crosby and others, 1973, p. 194). Water in the Fort Union aquifer is a sodium bicarbonate or sodium sulfate type in different places. However, some of K12 vi SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES TABLE 2.-Description of aquifers, water quality, and water-supply potential in the Souris-Red-Rainy Region [Compiled from Crosby and other s, 1973; Glover and others, 1972; and Robinove and others, 1958. Small yields are 5 to 150 gal/ min, moderate yields 150 to 350 gal/min, and large yields more than 350 gal/min] Aquifer Character of rocks Water quality Water-supply potential and aquifer occurrence Drift and alluvium . Drift: till, outwash, and _ lacustrine deposits. Alluvium: . gravel, sand, silt, and clay. Upper part of Fort Sandstone, shale and s Union (includes lignite. ot i ' Tongue - River f Member). E Cannonball Marine _ sandstone £ Member of Fort _ and sandy shale. Union. Fox Hills-Hell Creek Sandstone; sandstone - and shale. Pleffe ilahi Shale, brittle, fissile; upper part frac- tured. DAKOUA Sandstone and shale. PaleoZO¢ ..............- Shale, sandstone, limestone, - and dolomite. Precambrian ... Crystalline rocks, up- per part fractured and weathered. Extremely variable from place to place Dissolved solids generally 250 to 1,000 mg/L, but may be as high as 3,000 to 10,000 mg/L in a few places. Sodium bicarbonate type and locally high sulfate. Dissolved solids 200 to 7,000 mg/ L. Sodium chloride type. Dissolved solids less than 3,000 mg/L, most water ranges from 1,000 to 2,500 mg/ L. Sodium bicarbonate type generally, sodium sulfate type locally. Dissolved solids 300 to 3,700 mg/ L, but most water contains 1,000 to 2,000 mg/ L. Extremely variable from place to place. Sodium chloride, sodium sulfate type, Of combination. Dissolved solids 700 to 12,500 mg/L but most is less than 3,000 mg/L. Souris basin: sodium chloride type, dissolved solids 4,000 to 15,000 mg/ L. Red basin: sodium sulfate type, dissolved solids 2,000 to 8,000 mg/L in North Dakota, less than 2,000 mg/L in Minnesota. Highly saline. Dissolved solids 14,000 to 54,000 mg/ L in central part of Red basin, and as high as 330.000 mg/L in western North Dakota. Sodium bicarbonate sulfate type, depending largely on type in the adjacent aquifer. Dissolved solids about 1,000 mg/ L or more in Red basin, less than 500 mg/L in Rainy basin. Extremely varible from place to place. Large poten- tial for large supplies in sand and gravel aquifers. Large potential for small supplies almost everywhere in region. Small to moderate supplies. Occurs in western two-thirds of Souris basin. Small to moderate supplies. Occurs in most of Souris basin and extreme western parts of Red basin. Widely used for domestic and stock supplies. Occurs in eastern part of Souris basin and western two-thirds of Red basin. Moderate to large supplies. Occurs in western two-thirds of region. Potential for development of small to large supplies. Occurs in North Dakots and northwestern corner of Minnesota. Small supplies, low yields. Occurs in Minnesota and eastern North Dakota. the water from the deeper parts of the aquifer in the northern Dakota is a sodium chloride type, with chloride concentrations as high as 3,830 mg/L. Elsewhere, the water in the Fort Union aquifer generally contains less than the U.S. Public Health Service recommended limit for part of North chloride of 250 mg/L. The quality of water differs greatly among shallower (300 are less than 300 mg/L. The dissolved solids in drift aquifers in the Red and Souris River basins in North Dakota are generally greater than 600 mg/ L. Dissolved solids in the drift in North Dakota are as high as 26,200 mg/ L, although most water in areas where flow is upward from bedrock aquifers contains less than 10,000 mg/L (Crosby and others, 1973, p. 195). feet or less) wells in the Fort Union aquifer. Dissolved-solids concentrations range from about 200 to 6,700 mg/L in Fort Union aquifer that North Dakota. Most water in the contains more than 3,000 mg/L dissolved solids is in areas covered with drift. The dissolved-solids concentrations in most of the deeper part of the aquifer is in the 1,000- to 2,500-mg/L range. The high sodium and dissolved-solids the water from the Fort | p. concentrations generally make Union aquifer unsuitable for irrigation (Crosby and others, 1973, p. 194). In most of the Red River basi dissolved-solids concentrations in the 1972, p. 62, 63). In the Rainy River basin and in the northeastern part of the Red River basin, the dissolved-solids concentrations in the drift and 600 mg/L (Maclay and others, ROLE OF GROUND WATER WATER-RESOURCES MANAGEMENT Increased dem IN ands on ground-water and surface-water supplies of the Souris-Red-Rainy Region will be made in the future (Souris-Red-Rainy River Basins Commission, 1972, 15; and Ferris population is expected to increase 20 percent between 1960 and others, 1972, p. G-3, G-5). The and 2020 but the municipal and rural domestic water uses are n in Minnesota the drift are between 300 expected to increase 90 percent. industrial uses will cause even greater demands on the water supply. Municipal and industrial growth in an area generally depend directly upon the availability of adequate supplies of water of suitable quality. Increased irrigation and Anticipated increased use may SOURIS-RED-RAINY REGION 100° K13 92° T I f EXPLANATION 47° Dissolved solids, in milligrams per liter _] 0-1,000 SoUTH DAKOTA 1,000-3,000 Base from Souris-Red-Rainy River Basins Commission, 1972 | Modified from Glover and others, 1972 0 \ MINNESOTA ! I ~ ® LOCATION MAP 100 MILES 0 100 KILOMETERS FIGURE 11.-Dissolved solids in ground water. result in ground-water shortages. Little difficulty is expected in meeting this need in the eastern part of the Souris-Red-Rainy Region, but in the western part, par- ticularly in the Souris basin, good quality water from known sources is in short supply. Most of the anticipated additional needs for water in the western half of the region probably -can be met from the Garrison Diversion Unit and through greater use of ground- and surface-water supplies. The Garrison Diversion Unit is a large-scale water redistribution project. It is planned to divert initially 2,000 ft'/s and eventually 8,850 from the Missouri River at Garrison Reservoir to the Red and Souris River drainages and the James River (tributary to the | Missouri) drainage for irrigation and municipal-industrial uses. Also included as part of the Garrison Diversion Unit plan are measures for flood control, drainage of nonirrigable lands, pollution abatement, and recreation. Maclay and others (1972: p.. 47-84) discussed water-resource management in the Red River basin, cluding ground water. A summary of their discussion of ground water in the Red River basin applies as well to the Souris-Red-Rainy Region. Water management before 1967 included major flood-control projects, local flood-protection projects, watershed-protection projects... fish . and - wildlife developments, land drainage, and irrigation. Many man- in- | | | I | made reservoirs have been constructed, particularly in North Dakota. The largest of these is Lake Ashtabula on the Sheyenne River, which has about 69,000 acre-feet of usable storage. Primary considerations in the management of water supply are: (1) location and amount of the supply, (2) accessibility, (3) dependability, and (4) quality. Table 3 shows the advantages and disadvantages of ground water and surface water in regard to these four considerations. Ground water is important to the region's future develop- ment because of its large total quantity and general availability in most of the region; however, careful planning will be required in developing ground-water supplies because of its different quality from place to place and with depth, and the limited geographic extent of many of the Quaternary aquifers. Adapting McGuinness' (1963, p. 119) discussion of the role of ground water in the Nation's water situation to the Souris-Red-Rainy Region: 1. Ground-water reservoirs are important and indispensable in securing the region's future water supply. 2. Existing knowledge is grossly inadequate to form a basis for effective development and management of the ground-water reservoirs. 3. The region must overcome informational inadequacies in ground-water hydrology as well as in techniques of planning and water management. K14 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES TABLE 3.-Advantages and disadvantages of ground water and surface water as sources of water supply in the Souris-Red-Rainy Region [After Maclay, Winter, and Bidwell, 1972] Surface water Ground water Location and amount Surface water is easily located. Amount of surface water available is not large in some areas, even with storage. Ground water can be easily located where surficial deposits are water bearing. In most places exploration by test drilling or other methods is generally necessary to locate sources capable of supplying high-yield wells. Locally, even obtaining a small supply is difficult. Accessibility Surface water is readily accessible to riparian land owners in Minnesota. Surface water is not accessible to riparian land owners in North Dakota. Users must obtain State permits in North Dakota and Minnesota. For the large number of people not living along streams and lakes, surface water is generally not available. The cost of physically storing and transporting water is an important economic factor. Ground water is generally accessible.by drilling wells. Locally, an aquifer capable of supplying high-yield wells may not be in the immediate vicinity and a municipality may, have to go several miles to obtain a supply. A State permit is required for supplies larger than for domestic purposes. Dependability Because streamflow can be observed and measured it is possible to calculate and project the amount of water that will probably be available in the future. Data are already available for some locations on many of the streams. Stream flow is highly variable in most streams in the region. Dependable water supplies require storage reservoirs as a rule. Ground-water sources are ususally very dependable. If discharge does not exceed recharge, ground water can normally be used virtually indefinite- ly, including periods of extended droughts. Determining the yield of an aquifer is difficult. Data are not available for many areas and they are costly to obtain. Shallow surficial aquifers are generally not dependable during drought years. Quality Surface water is generally low in dissolved solids and the concentration is fairly uniform east of the Red River but variable west of the Red River. Treatment is generally necessary to remove suspended sediment and organic matter. Quality, temperature, and color vary widely over the year at any location. Ground-water quality differs over the region but generally does not vary with time at any location. Temperature is constant throughout the year. Certain chemical characteristics, such as hardness and iron content, are high in many places. FRESHWATER USE Ground water is the sole or a primary source of supply in much of the Souris-Red-Rainy Region. In areas distant from streams and in uplands, where surface water is not available physically, legally, or in the quality required for a particular use, ground water is the sole source of supply. Ground water and surface water are used conjunctively in part of the region, but conjunctive use is not fully exploited to meet quantity and quality requirements of water supplies. For example, water of good quality from one source could be mixed with mineralized water from another source in some areas to get a greater quantity within specified quality requirements. Also during times of low or no streamflow, ground water could supplement or replace surface water. Distribution systems could be used for surface water or ground water. Estimates of water use in the United States according to categories of use were listed by State and region by MacKichan and Kammerer (1961), Murray (1968), and Murray and Reeves (1972). Water-use projections to 2020 were given for the Souris-Red-Rainy Region by Ferris and others (1972) and Weber and others (1972) in the Souris-Red-Rainy River Basins Comprehensive Study. The U.S. Bureau of - Reclamation (1973) summarized water-resources development in North Dakota, with emphasis on surface-water supplies, and included a brief description of the Garrison Diversion Unit which was mentioned earlier. IRRIGATION About 15,700 acres of land was irrigated in the region in 1967 and 1968, including about 12,000 acres in the Souris River basin, about 3,500 acres in the Red River basin, and about 200 acres in the Rainy River basin. Irrigated land in the Red River basin increased to about 38,000 acres in 1975 but remained about the same in the Souris and Rainy River basins. The total land irrigated in 1975 was 50,200 acres. The largest potential use of water in the Souris-Red-Rainy Region is for irrigation. Forecasts of irrigation development were described by Weber and others (1972) in the Souris-Red-Rainy River Basins Comprehensive Study for optimum utilization of land and water resources. Potentially irrigable lands were considered to be suitable for develop- SOURIS-RED-RAINY REGION ment by either private (small-scale) or project (large-scale) methods, depending on availability of water. Private methods considered were farm-size systems irrigated primarily with ground water. Project methods considered would use surface-water storage and distribution works, which probably could be constructed only with public funds. Sources of water in quantity for irrigation include ground water in the Souris and Red River basins and water from the Missouri River (Garrison Diversion Unit) and the Rainy River. The Souris and Red River basins have large areas of potentially irrigable land (fig. 12), but water is not available from the Souris River for irrigation and the Red River can supply only small parts of the potentially irrigable area in the basin, such as the irrigated area east of Moorhead where several irrigators tap tributaries to the Red River. Surface water for potential irrigation development in the Souris and Red basins must be supplied from other sources, such as the Missouri and Rainy Rivers. In the Rainy River basin the abundance of surface water of good quality and apparent absence of large aquifers preclude the consideration of ground water for major irrigation. The ultimate potential irrigation development in the region totals 1,550,000 acres, table 4. It is predicted that the amount of irrigated lands will reach 530,000 acres by the year 2000 and 1,404, 000 acres by 2020. Ground-water develop- ment is projected to decrease between 2000 and 2020, and 104° ina & W 4 | | 49° i fi > o or rane meine =--___ NORTH DAKOTA y A 474— EXPLANATION Irrigable area using ground water v NORTH * DAKOTA SoUTH DAKOTA Irrigable area using surface water Modified from Weber and others, 1972 Base from Souris-Red-Rainy River Basins Commission, 1972 MANITOBA =_ UNITED sTATES ' . 2 K15 TABLE 4.-Projected irrigation in Souris, Red, and Rainy River basins [From Souris-Red-Rainy River Basins Comprehensive Study by Weber and others, 1972, tables F-17, F-20] Acreage (thousand acres) River basin Water source Year Year Ultimate 2000 2020 Ground water ...... 20 16 16 .... Surface water ......... 134 369 369 .... Ground water ...... 200 180 180 ... Surface water ...... 169 824 970 Surface water ......... 7 15 15 Total ground water ................... 220 196 196 Total surface water ...................... 310 1,208 1,354 Grand total irrigated .................... 530 1,404 1,550 Note.-Does not include 190,700 acres as initial stage of Garrison Diversion Unit. surface-water (or project) development is projected to increase nearly 400 percent in the same period. The source of water and the irrigable area for the ultimate irrigation development within each State in the region is shown in table 5. It is estimated that 579,000 acres could be irrigated from the Missouri River (Garrison Diversion Unit), 775,000 acres could be irrigated from the Rainy River, and 196,000 acres from ground-water supplies. The estimate of potential irrigation development is 1,203,500 acres in North Dakota, 343,000 acres in Minnesota, and 3,500 acres in South Dakota. 921° I |__vorns parora P 1 _ SOUTH DAKOTA (W'SCONSIN Saa \ minnesota \ | © 5 * LOCATION MAP 0 100 Mies 0 100 kiometers FIGURE 12.-Areas with irrigation potential. K16 TABLE 5.-Ultimate irrigation in each State in the Souris-Red-Rainy Region [From Souris-Red-Rainy River Basins Comprehensive Study by Weber and others, 1972, p. F-51 to F-60] Potential irrigation development (thousand acres) Development plan North Minnesota South Total Dakota Dakota Souris River basin: From ground water' ...... 16 16 From Missouri River ..... 369 369 Red River basin: From ground water' ...... 122 58 180 From Missouri River ..... 206.5 3.5 210 From Rainy River ...... 490 270 760 Rainy River basin: From Rainy River! ...... 15 15 TOlal ~A Mires 1,203.5 343 35 1,550 'Private development Project development The projections in the Souris-Red-Rainy River Basins Comprehensive Study (Weber and others, 1972) show that most of the near-future irrigation will be with ground water. By 2000, 41 percent of the acreage will be irrigated from ground water, but by 2020 surface-water development will account for 86 percent of the irrigated area. These projec- tions are based on present knowledge of the availability of ground water and do not allow for methods of water management such as artificial recharge, salvage of water for beneficial use, and use of saline aquifers. Also, with continued ground-water investigations, additional aquifers probably will be found. When water-management possibilities are fully utilized, ground water may become increasingly important to irrigation. MUNICIPAL The region is primarily rural, with few population centers of more than a few thousand persons. Only 11 cities are projected to have a population of greater than 10,000 by 2020 (Ferris and others, 1972, p. G-7). Ten are in the Red River basin and one in the Souris basin. Of the 208 cities or towns in the region, 178 have ground-water supplies, 21 have surface-water supplies, and 9 have combined supplies. Table 6 lists the number of cities and towns and population served in each of the river basins. The smaller communities and towns of the region generally rely on ground water, and the larger cities and industries rely on surface water, ground water, or both. The municipalities using surface water generally depend on reservoir storage. Municipalities with water-distribution systems have a per capita use of about 100 gallons of water per day.The per capita use is 108 gallons per day in the Souris basin, 98 gallons in the Red basin, and 79 gallons per day in the Rainy basin. Projections indicate a pet capita use of about 140 gallons per day by 2020 for the Souris-Red-Rainy Region. Projection for the Souris, Red, and Rainy basins are 152, 138, and 119 gallons per day per person, respectively, in 2020. Table 7 lists the 1960 population and water | [From Souris-Red-Rainy River Basins Comprehensive Study by SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES TABLE 6.-Municipal water supplies in the Souris-Red-Rainy Region [From Souris-Red-Rainy River Basins Comprehensive Study by Ferris and others, 1972, p. G-19, G-36, G-75. Populations are from 1960 census] Source of water Ground Surface _ Combined Souris River basin: Number of cities or tOWNS ........... 31 0 2 Population §EIVEU -... 23,019 0 35,800 Red River basin: Number of cities or towns: North and South Dakota ........ 69 8 5 MiNNESOtA ...... enn} 69 8 1 Population served: North and South Dakota ...... 62,620 104,317 13,903 MINNESOTA eee een 50,355 42,590 22,935 Rainy River basin: Number of cities or toOWns$ ........... 9 5 1 Population S@IVEd . .. 9,915 14,705 465 Total: Number of cities or towns 178 21 9 Population SEFVEd .... ;:::... 145,909 161,612 73,103 withdrawal, and projections of population and withdrawal to 2020 for each of the basins. According to Ferris and others (1972, p. G-2) in the Souris-Red-Rainy River Basins Comprehensive Study, for a few communities the threat of water shortages persists or may develop as requirements increase. These communities include Minot, in the Souris River basin, and several other cities (such as Neche, Pembina, Grafton, and Mayville, N. Dak., and Crookston, Minn.) that depend on tributaries of the Red River. The largest municipal water-supply demands of the region are along the main stem of the Red River. The TABLE 7.-Municipal, domestic, livestock, and industrial water supply in the Souris-Red-Rainy Region Ferris and others, 1972, tables G-12, G-15, G-36, G-39, G-49, G-52] Population served Withdrawal 1960 2020 1960 2020 Mgal/d Mgal/d Municipalities: Souris ...... 58,819 121,899 6,36 18.50 Red 296,720 507,709 29.11 69.87 Rainy /...... 25,085 36,511 1.98 4.36 Total ...... 380,624 666,119 37.45 92.73 Domestic: Souris ...... 44,852 20,701 2.11 1.15 Red :.... .on. 244,393 135,791 13.12 7.385 Ramy ..:..;; 15,323 8,152 .65 .36 Total ...... 304,568 164,644 15.88 8.176 Livestock: SOUTIS ~...... .cc 4.50 8.18 Red ...... 52.63 100.06 RAINY 2:38 4.25 TOUAL inns c as tererr ena nals 59.48 112.49 inne Industrial: SOUTIS vre 2.33 4.15 Red ...... 151.38 92.78 RAIRY ...lol. cv ener 54.23 157.62 TOA] ......» races 207.94 255.15 SOURIS-RED-RAINY REGION Red River and its tributary storage can meet the present municipal and industrial requirements. Shortages in some areas, however, have occurred during prolonged drought. Communities that depend on ground water have solved such problems by deepening wells or constructing additional wells. As water use along the main stem of the Red River increases, additional storage for water supply may be required, or ground water may be needed as a supplement. Water supplies in the Rainy River basin exceed present and foreseeable requirements. DOMESTIC AND LIVESTOCK Domestic and livestock water supplies are almost entirely from ground-water sources. Withdrawals are small and well distributed and shortages are not expected. About two-thirds of the 305,000 rural population are served by pressurized water systems, and per capita use is 60 gallons per day. By 2020, the rural population is expected to be about half the present number and to have the same per capita use, according to Ferris and others (1972) in the Souris-Red-Rainy River Basins Comprehensive Study. The 2020 water-use projections (table 7) are intended to indicate the trend of water requirements based on population projections and the general water-use criteria developed for the basinwide projections. These projections do not reflect the individual circumstances for a given community. In the Souris River basin, about half the domestic and livestock wells tap bedrock aquifers. Drift aquifers supply the other half. Surface water, where available, is used for livestock. Some water, which is too mineralized for human consumption, can be tolerated by livestock. In the Red River basin drift aquifers, where available, are generally tapped by domestic and livestock wells. Well yields and water quality from the bedrock aquifers are generally poorer than from the drift. Bedrock aquifers can be tapped nearly anywhere on the Dakota side of the Red River basin, but are not present in parts of northwestern Minnesota. As a result, local water shortages exist where drift aquifers are also absent. Livestock production has been inhibited due to lack of adequate water resources in parts of northwestern Minnesota. Rural domestic water in the Rainy River basin is supplied by wells. Livestock supplies are mostly from surface-water sources. In the last several years, water districts have been formed in North Dakota to supply water to rural and small-city residents for domestic and stock uses. In general, the rural water districts are formed as a consequence of county-wide ground-water studies which delineated aquifers and iden- tified ground-water resources available for development. Water supplies of about 100 gal/min are developed from glacial outwash, buried sand and gravel channels, and delta aquifers such as are found along the east edge of North Dakota in the Red River valley. The water districts are formed to utilize good-quality water from these aquifers and to supply nearby rural areas where water quality and quantity are inadequate. K17 INDUSTRIAL The economy of the Souris and Red River basins is based primarily on agriculture and related food-processing in- dustries. The food-processing industries, which include sugar-beet refining, potato processing, meat packing, and creameries, account for a large part of the industrial water demands. Most soils in the Rainy River basin and in the northern Minnesota part of the Red River basin, however, are unsuitable for cultivation but valuable for forestry. In these areas forestry resources and recreation are the economic foundation, and the pulp and paper industry is the primary water user. Manufacturing is increasing in the Souris basin. The large decrease in water requirements indicated in the Red River basin from 1960 to 2020 (table 7) - is due to a shift in the power industry from flow-through to cooling-tower operation. Table 7 reflects only water use by self-supplied industry. Some industries obtain water from municipal supplies. A rough guideline is that municipal water use in excess of 80 to 90 gallons per day per person is attributable to commercial and industrial use. Ferris and others ( 1972) in the Souris-Red-Rainy River Basins Comprehensive Study assumed that future industrial food processing in the region would increase at about the same rate as agricultural production. Figures in table 7 reflect the expected increase in the Souris and Rainy River basins. A similar increase in the Red River basin is overshadowed by the expected decrease in water re- quirements of the power industry. That is, future water use was derived by applying the projected production of power to current water use. Where appropriate, adjustments were made to reflect changing trends, such as the anticipated increase of water recycling or reuse. SALINE-WATER USE Highly mineralized ground water is plentiful in the western part of the region. Feth and others (1965) showed the availability of water containing more than 1,000 mg/L dissolved solids at depths less than 500 feet throughout the western half. In the northeastern and northwestern corners of North Dakota, water containing 10,000 to 35,000 mg/L dissolved solids lies at depths of less than 500 feet. At greater depths the water is generally more mineralized. Such water can be considered a resource or asset rather than a liability. The water can be used for a number of purposes, including cooling and oil-field repressuring. Possibly this highly mineralized water could be utilized by the chemical industry as a source of minerals and chemicals. Mineralized water from the Dakota aquifer is being used for washing sugar beets and potatoes. In the western part of the region highly mineralized water is being used to some extent to repressure oil fields to increase production. Saltwater produced with the oil must be disposed of so that it does not damage the environment and contaminate surface water and fresh ground water. About 94 percent of the oil-field brine produced in North K18 SUMMARY Dakota is returned to saline ground-water reservoirs. Most of the brine is returned to the reservoirs from which it was withdrawn (Folsom, 1973, p. 102). Where oil-field brines are insufficient for repressuring oil fields, highly mineralized water available from other ground-water sources ideally should be used to conserve freshwater supplies. A large part of the available water supply of the western part of the region is saline. Robinove and others (1958) stated that a large proportion of the available water supply of North Dakota is saline. Water-resources investigations in the region have been principally oriented to municipal, industrial, domestic, and irrigation - uses requiring freshwater. However, saline water can be treated to increase its usability for these purposes. Congress, in 1952, passed the Saline Water Act that provided for research into and development of practicable and economic means to produce freshwater from saline water to conserve and increase the water resources of the Nation. Considerable progress has been made in developing desalinization processes. The former Office of Saline Water (now Office of Water Research and Technology), Department of the Interior, once operated an electrodialysis desalting plant at Webster, S. Dak.. Although only a small number of desalinization plants are in operation throughout the Nation, they may be used more extensively in the future. In some areas of the region water of acceptable quality for a particular purpose may be inadequate in quantity. Where saline water is available, it could be diluted with the freshwater to create an adequate supply of usable water. Feth (1965) prepared a map of the United States showing distribution of saline ground water. His report includes a large number of references. Several reports for North Dakota and Minnesota are listed and the reader is referred to these reports for a more detailed discussion of saline ground water in the region. ARTIFICIAL RECHARGE Artificial recharge is the process of increasing the storage of water in an aquifer system by artificial means. Storage in the ground has several advantages over surface storage: (1) the sand and gravel would filter the water; (2) the water would be kept at a relatively constant temperature; and (3) there would be no evaporation. Care is necessary, however, to avoid pollution or physical impairment of the un- derground system. For example, recharge waters must be chemically compatible with the native ground water to prevent formation of precipitates that would reduce hydraulic conductivity. Suspended solids must be removed before injection, and pollution by bacteria must be prevented. Storage of surface water in aquifers during times of surplus for withdrawal during times of scarcity would aid in meeting increased demands. Floodwater is chemically better in most respects than underlying ground water in parts of the western half of the region. Freshwater could be stored M APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES in saline-water aquifers, as well as freshwater aquifers, and pumped out as needed. Artificial recharge may be accomplished by direct and indirect methods. Direct methods of recharge include water spreading by means of ponds, check dams, pits, furrows, or ditches to increase the amount of water infiltrating from the surface into the ground-water reservoir, and injection of water directly into the ground-water body by means of wells or shafts (fig. 13). Indirect methods of recharge include inducing movement of water from streams or lakes into underground formations (fig. 14A), and preventing the natural flow of ground water to the land surface by lowering ground-water levels (fig. 14B). Further information is available in the published literature on methods, case studies, and other aspects of artificial recharge. See Todd (1959), Signor, Growitz, and Kam (1970), and Knapp (1973) for listings of literature to 1973. REPLENISHING FRESHWATER AQUIFERS Surplus water is available during winter and spring from surface-water sources, principally the larger rivers and tributaries, which could be used to recharge ground water. Furrows or Recharge well Land surface ditches Water table No impermeable layer or zone between ground surface and aquifer Recharge well Land surface Relatively impermeable Water table Water table aquifer Impermeable layer or zone between ground surface and water-table aquifer Recharge well Land surface surface Potentiometric Zone of aeration Relatively impermeabl Artesian aquifer Impermeable layer or zone between ground surface and artesian aquifer Figure 13.-Diagrams of direct methods of recharge. SOURIS-RED-RAINY REGION Land surface Increased gradient and flow from river Part of water pumped is inter- cepted before reaching river, thereby decreasing natural B river flow downstream FIGURE 14.-Diagrams of indirect methods of recharge. Utilization of floodwater to replenish ground-water supplies also would diminish flooding to some extent. Additionally, water injected into the ground in winter or early spring would be cold and well suited for air conditioning and as a process coolant. This technique probably could be used near Moorhead where high flows from the Buffalo River could be injected into the aquifer and pumped out later in the year. Artificial recharge is not new to the region, as shown by the following two examples. Artificial recharge has been in operation at Minot, N. Dak. since 1965. The Souris River has been a source of part of Minot's municipal water supply for many years. In 1961, Minot constructed eight wells to supplement the stream supply. Excessive water-level declines in the following years indicated that a ground-water shortage was developing. Although the Souris River is not a reliable source of direct supply, relatively large peak flows in the spring indicated that the river was a potential source of water for recharge to K19 the aquifer. A ground-water recharge facility was designed and constructed in 1965 to use both direct and indirect recharge methods, (Ferris and others, 1972, p. G-22). Kelly (1967, p. 20) reported that Valley City, N. Dak., had an average daily water use of 750,000 gallons in 1966, which was obtained from wells tapping partly confined gravel deposits in the Sheyenne River valley. These deposits at Valley City have a maximum thickness of more than 50 feet and an areal extent of about 1 square mile. The aquifer has been artificially recharged successfully since 1932 by diver- sion of water from the Sheyenne River to an abandoned gravel pit. During this time the potentiometric surface in the aquifer has risen more than 22 feet. Before 1958, the recharge system was operated annually from J anuary until June; however, when the potentiometric surface rose to within 8 feet of the surface, the recharge operation was discontinued. Between J une and January the potentiometric surface declined as ground water was withdrawn. During the recharge-discharge cycle, the average annual fluctuation of the potentiometric surface was 10 feet, amounting to a change in storage of about 1,000 acre-feet of water. Since 1958, the recharge system has been operated throughout the year. The quality of water in the aquifer has gradually improved since the installation of the recharge system. FRESHWATER STORAGE IN SALINE AQUIFERS Saline aquifers can be used to store freshwater during times of abundant surface supply and pumped out as needed. Tests and experiments by the U.S. Geological Survey at Norfolk, Va., recovered about 85 percent of the injected freshwater (Brown and Silvey, 1973). The freshwater dis- places the saline water and forms a fresh-water body, most of which can be recovered. The success of such projects would depend on knowledge of the hydrologic system in the vicinity of the projects, favorable site conditions, and on the operation of adequate monitoring systems. This possibility might be investigated in the Minot area, N. Dak., the Fargo-Moorhead area, N. Dak. and Minn., the Hallock area, Minn., and other population centers or areas of central rural supplies where spring floodwater might be retained temporarily in upland reservoirs until it can be treated and stored underground. In the Red River basin, the Dakota Sandstone or the Pierre Shale might be used in North Dakota for this purpose; in Minnesota aquifers in Cretaceous or Ordovician rocks might be so used. In the Souris River basin, the Fox Hills-Hell Creek aquifer or the Fort Union aquifer might be so used. The Dakota Sandstone in the Souris basin probably is too deep to be used economically for this purpose. To use these aquifers for storage of surplus surface water, suitable site conditions would have to be located. LIQUID-WASTE DISPOSAL IN SALINE AQUIFERS Saline aquifers can be used for liquid waste disposal. Much has been written concerning underground waste K20 disposal (Rima and others, 1971). A knowledge of the geology, ground-water hydraulics, and geochemistry would aid in determining whether or not injected wastes could be contained and isolated, or recovered later if it is warranted. (Injection of waste underground can present serious hazards to water supplies and the local environment.) GROUND-WATER DEVELOPMENT Water use has had a rapid upward trend in the Souris-Red-Rainy Region. As the gross water supply is constant and water demands are rising, the answer to problems of supply is the development of untapped sources of water and the possible reuse of water. PROBLEMS OF DEVELOPMENT The problems of development differ widely with the intended use of the water. Problems inherent in development of most small wells are chiefly the availability, quantity, and quality of the water. Water quality is a serious problem in parts of the Souris and Red River basins where supplies of potable water are scarce. The development of large supplies has additional problems related to proper planning and administration of the development pattern. Initial development generally involves haphazard drilling for water that is readily available. In some areas where the ground and surface waters are closely related, the develop- ment of ground-water supplies has depleted surface flow (Theis, 1941). Also, unplanned development may result in aquifer overdraft in one area and surpluses at another. Ideally, the development of an aquifer would be designed to achieve the optimum economic recovery of the water. To achieve this, detailed information would be needed on the depth, quality, quantity, and annual recharge and discharge of the water in the various aquifers. Thus it is seen that water problems during initial development in much of the region are related to hydrologic and geologic conditions. In general, investigations that would provide information about the geologic and hydrologic conditions of the aquifer are not undertaken until the degree of development has created problems that threaten the continued use of the aquifer. In this region, these problems are: changes in ground-water levels, depletion of streamflow, and deteriora- tion of water quality. Also there are management problems relating to ground-water replenishment, ground-water con- servation, and effects of the development on the environ- ment. CHANGES IN WATER LEVELS Pumping necessarily causes water levels to decline near the pumped well, creating a gradient and flow toward the well. Water-level declines, although not yet alarming in most of the region, are increasing the cost of pumping. Declines of ground-water levels near West Fargo, due to municipal and industrial pumpage, indicate possible future supply problems from this aquifer. Large water-level declines in the Minot well field in the early 1960's indicated that a critical SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES water shortage was developing rapidly. The problem was alleviated by artificial recharge of the aquifer. (See the section "Replenishing Freshwater Aquifers.") If the extraction of water continues until withdrawal exceeds recharge, significant depletion of water storage may occur in the area of overdraft. With time, the continued or increased water use may cause water-level declines in the entire aquifér. In the late 19th century and early 20th century near the Red River, wells flowed that tapped the glacial drift below the lake deposits. Since then water levels in the western part of the lake plain have declined and wells have ceased to flow. Serious water-level declines have occurred near West Fargo because of municipal and industrial pumpage of about 500 million gallons annually. Water levels have declined as much as 150 feet at Moorhead where buried sand and gravel aquifers have been tapped for a municipal water supply. Because of the declines in water levels in this area, the ground-water gradient has been reversed locally and the underlying drift aquifers are being recharged rather than discharging upward toward the land surface (Maclay and others, 1972, p. 113). Water-level rises can be caused by irrigation of land, leakage from canals, flooding, and construction of surface reservoirs. Percolation of irrigation water to the water table in time may cause the water table to rise. Infiltration of irrigation water additionally could cause deterioration of ground-water quality. Excessive water-level rises may cause other problems such as flooding of basements, damage to structures, and detrimental changes to vegetation. An example of potential rising water levels is near the planned Kindred Dam and lake on the Sheyenne River in southeastern North Dakota. Downey and Paulson (1974) have predicted that the maximum rise in water levels will occur about 50 years after filling of the lake. DEPLETION OF STREAMFLOW The withdrawal of ground water can decrease streamflow by decreasing ground-water discharge to the stream or by inducing infiltration of water from the stream to the aquifer. The pumping effect on a stream depends on the pumping rate, distance of well from the stream, and the aquifer characteristics. The amount of ground-water pumpage derived from a nearby stream Of drain can be computed by methods developed by Theis (1941). Decreased streamflow caused by pumping of ground water is generally considered an adverse effect. However, benefits may outweigh the disadvantages, as in the Minot area, where a dam on the Souris River augments the surface supply to the city and increases infiltration of ground water to the city's well field (Ferris and others, 1972, p. G-22)._ DETERIORATION OF WATER QUALITY Deterioration in chemical quality of the ground water may result when the natural equilibrium of the aquifer is disturbed by development. Intensive development can cause SOURIS-RED-RAINY REGION large-scale deterioration of quality by recirculation of water, interformational leakage, and pulling poor water from distant areas. Where good quality water is being pumped from glacial aquifers, upward migration of deeper mineralized water may be caused by the lowered head due to pumping. The Paleozoic and Cretaceous rocks in the northwestern part of the Red River basin contain highly saline water that is discharging where these rocks pinch out against crystalline rocks in Minnesota. Upward migration of saline water has resulted in contamination of ground water in the overlying drift in northwestern Minnesota and northeastern North Dakota (Maclay and others, 1972. p. 113; Crosby and others, 1973, p. 195). To the west of the area, wells tapping the better water in the overlying drift aquifers could induce upward migration of the saline water if the heads are lowered sufficiently by the pumping. Water may leak vertically between aquifers if the seal between them is broken by improperly constructed wells. If the quality of water is poorer in the aquifer having the higher head, the quality of water in the receiving aquifer will deteriorate. Municipalities and industry have to dispose of a variety of wastes. The important types of waste in the region are chemicals from food and industrial processing, sewage, concentrated chemicals in cooling water, oil-field brines, mine discharge, and return flow of irrigation water. Any of these wastes may cause deterioration of ground-water quality if they enter the aquifer. Other types of waste, such as the effluent from saline-water conversion plants may be added in the future. The use and reuse of water for irrigation results in the increase of dissolved mineral concentrations in the water. Each time water is applied to the land, some returns to the surface stream or to the ground-water reservoir. This return flow is wastewater, and its utility has been decreased because of the increase in dissolved-solids concentration. GROUND-WATER CONSERVATION When intensive development reaches advanced stages, the conservation of water becomes important as a solution to several types of problems. Farm conservation could include reduction of irrigation losses between well and field; more efficient irrigation, planting crops with a smaller water requirement, and eradication of phreatophytes. Leaky artesian wells could be repaired and artesian flow controlled by valves at the wellhead. Municipalities could repair leaky distribution systems, and limit lawn watering. Commercial users could return cooling water to the aquifer. Industry could process and return used water underground through injection wells or filter beds. All of these conservation measures could be used to various degrees in the Souris-Red-Rainy Region. Elimination of phreatophytes would reduce consumptive use of the ground water. Phreatophytes, where found, are in K21 areas where ground water is less than about 30 feet deep. Phreatophytes may intercept and waste ground water moving toward streams or lakes. They also may use enough water to induce recharge from surface-water bodies into shallow aquifers. Phreatophytes in some parts of the Nation are undesirable. However, in this region phreatophytes are desirable as wind breaks and ground cover to prevent erosion. Water may be salvaged by use of evaporation sup- pressants on surface reservoirs in the western half of the region where evaporation rates are high. Experiments with evaporation suppressants (Magin and Randall, 1960) in- dicate suppression may not be practical or feasible on large reservoirs, but is promising for use on small ponds. Evaporation losses could be eliminated by storing water underground and pumping it out as needed. The un- derground storage could use known aquifers or permeable, unsaturated materials. Another method of water conservation that could be used advantageously in the region is the salvage and recycling of water. Such recycling includes air conditioning or industrial water where the water can be treated to restore its usefulness. The possibility of reuse should be considered for as many different situations as possible. Under some circumstances ground water used for air conditioning could be returned to the reservoir without detrimental effects, thereby main- taining the ground-water supply. EFFECTS ON THE ENVIRONMENT A Souris-Red-Rainy River Basins Commission report (1972, p. 215) states: Although this Region is relatively small in comparison to other water resource planning regions in the Nation, its natural environment is characterized by a wide variety of physiographic and vegetative features. Over the years, public concern for maintaining and/or enhancing the quality of this natural environment has been increasing rapidly. Proper use and management of the water and land resources, which make up the Region's natural environment, will preserve and maintain a high quality environment. Development of water supplies may have a detrimental effect on the environment. However, adequate monitoring programs can detect adverse effects in most situations. Declining water levels caused by pumping can cause migration of highly mineralized water, depletion of streamflow, or a change in natural vegetation in the case of near-surface ground-water levels. Irrigation can cause deterioration of water quality as natural minerals and fertilizers are dissolved in recycled irrigation water. Long distance transportation of water may cause en- vironmental changes. Such changes depend on (1) quality of the transported water in relation to the native water, (2) depth to the.ground water along the path of transportation and in the area of use, and (3) effects of removing water from one area for use in another. Along much of the Red River in North Dakota and Minnesota, natural upward migration of highly mineralized K22 water has reduced soil productivity. Pumping could lower heads of the mineralized water and improve the quality of the soils, but provision would have to be made to dispose of the mineralized water. Lowering the artesian heads is a drainage project that could be detrimental to wildlife and natural vegetation. A broad-scale analysis of land resources and watershed management as related to economic development and certain aspects of the environment is presented for the region in the Souris-Red-Rainy River Basins Comprehensive Study (McClure and others, 1972). Currently more than 2 million acres of pasture and range land is suitable for crop production. Conversely, one-half million acres of land currently used for crop production could be converted to more economical uses such as forest, pasture or range land. The projected land development depends largely on availability of water, and particularly on availability of ground water. INFORMATION AND GROUND-WATER MANAGEMENT NEEDS Few aquifers are so continuous and uniform that high-production wells may be assured without preliminary test drilling. In some places the aquifers are defined by data from scattered test holes; future work may modify inter- pretations. For example, very little is known about the Paleozoic rocks in the Souris-Red-Rainy Region owing to a lack of drill-hole data and information on depth to the rocks. Exploration, testing, and study may help to find water at depth in quantity and quality suitable for a particular purpose. Study and planning also are needed to determine the best use of the water and land resources. A properly designed and operated monitoring program can alert managers to approaching problems of diminishing supply or other detrimental effects. Monitoring programs ideally should be started before development, and continued to detect changes and determine effects of the development. For example, pumping ground water causes water-level declines near the pumped wells. As pumping continues or is increased, these declines generally spread. Return irrigation water, a new canal or reservoir, or excess precipitation can cause water-level rises. Monitoring water levels near pumped areas could give useful information on possible migration of inferior water toward the well field. A ground-water quality monitoring program would detect changes in water quality such as migration of highly mineralized water or other pollution within or into the aquifer. Data from such a program could be used to suggest corrective action such as altering the pumping rates Of patterns. Reconnaissance and qualitative studies have been made for most of the region. Quantitative studies, including the use of models, have been made for small parts of the region to define the hydrologic and geochemical aspects of the SUMMARY APPRAISALS OF THE NATI ON'S GROUND-WATER RESOURCES system. Where sufficient data are available to develop digital models, these would benefit the planned development of the ground- and surface-water supplies. All of the water in storage, both surface water and ground water, is not usable, and the amount of each fluctuates with changing conditions. Regulation of surface- and ground-water storage can increase the usable supply. Adequate surface storage possibly could eliminate the loss of floodwaters and reduce surface discharge to that amount required for downstream water users. Some surface water is lost during floods when streams overflow onto adjacent lands and the water is lost to evapotranspiration. Additional surface storage could reduce these losses. These surplus waters could be conserved by artificial recharge through wells and infiltration beds. Data are needed to determine the amount of surface water that could be salvaged by artificial recharge. Also, data are needed in all areas to locate suitable recharge sites. Some water in storage is not usable because of high mineral content. Information is needed to determine where desalinization could be effective to increase the usable water supply. Information and inventories are needed to identify existing and potential sites of pollution and means of waste disposal. In a water-short area such as the western half of the region, the reduction of waste through intensive use and conservation would reduce problems of waste disposal. The increased concentration of chemical constituents that results from intensive reuse of water, however, may aggravate problems in other areas, such as restrictions on, or lack of, suitable disposal sites or methods. Wise and efficient use of water requires that waste problems be solved at the stage of prevention, rather than when the problem becomes one of correction. Further research may lead to better means of reducing agricultural processing wastes. Also, research may determine the efficiency and suitability of various types of soils for the land disposal of sewage sludges and effluent. Information gained by continued monitoring could be effective in preventing pollution from oil-field waste. Water produced with oil in the western part of the Souris River basin is an important quality problem in North Dakota. The water is highly mineralized and is produced in relatively large volume. Pollution from petroleum production, however, does not appear to be a serious problem at this time. Surveillance of these activities is conducted by the State of North Dakota and prevention of pollution rather than - curative measures - are emphasized - in the Souris-Red-Rainy River Basins Comprehensive Study (Young and others, 1972, p. H-16). Most of this water is disposed of by injection into deep wells, either for disposal, or for repressuring oil producing formations. Data are required on water-level fluctuations in connec- tion with the inventory of water supplies, and to minimize the possibility of waterlogging of the land, and the invasion -_SOURIS-RED-RAINY REGION of inferior water. Data also are needed on the quantity of return flow from existing irrigation areas and on the relation among crop type, water application practices, fertilizer use, and other factors causing increase in dissolved solids in the return flow. Maclay, Winter, and Bidwell (1972, p. 71-73) discussed water-resource management alternatives and related infor- mation needs. Their discussion is summarized here with respect to ground water in the Souris-Red-Rainy Region. Many alternatives for managing water are available to planners, some of which could be applied to water problems in the region. Some of these are operational and others are currently undergoing research. Many of them require adaptation to each local situation. Improved methods to locate ground-water supplies are greatly needed. This would assure that the best and nearest possible source is being used. Better methods of well drilling and construction could lead to better development of water supplies. More efficient well development is needed, par- ticularly in small aquifers. Pumping water from the lower yielding aquifers by using several low-yield wells rather than one high-yield well might be desirable. This is particularly applicable to beach-ridge aquifers associated with deposits of former glacial lakes. Also, special types of well construc- tion such as infiltration galleries may be useful for develop- ing thin but widespread aquifers, for example, those composed of beach deposits. Special uses of saline or other poor quality water could be beneficial in part of the region where this type of water is abundant. Desalinization might be considered for these areas when it becomes economical. Joint use of ground water and surface water also offers many management possibilities, particularly in the lake plain. Mixing of good quality water with poor quality water may provide an intermediate type that is acceptable for a particular use. This might be considered where poor quality water is abundant. The storage capacity of aquifers would determine the possibility of storing surface water in them. Ground-water pumpage could greatly exceed natural recharge if stream water could be injected into ground-water reservoirs during periods of high flow. This technique probably could be used near Moorhead, where high flows from the Buffalo River could be injected into the aquifer and pumped out later. More efficient and less costly methods are needed for transporting water from source to central distribution system, and then to individual users. Better metering and more realistic water billing in some of the communities could reduce water demands. Many alternatives in the management of water supplies are possible. The selection of methods would depend upon their economic and hydrologic feasibility. In selecting any one or a set of these alternatives, the development of a water resource should be considered in the context of the total hydrologic system, with the realization that hydrologic f I o K23 changes in one part of a system will cause changes at other places. McGuinness (1969; p.. 1) stated. "... management of aquifers requires vast amounts of data plus a much better understanding of aquifer-system behavior than now exists. Implicit in this deficiency of knowledge is a need for much new research, lest aquifers be managed according to ineffective rule-of-thumb standards, or even abandoned as unmanageable." SUMMARY The Souris-Red-Rainy Region is underlain by a series of bedrock units that differ greatly in thickness and hydraulic characteristics and that range in age from Precambrian to Quaternary. Precambrian rocks are at or near the surface locally in the eastern part of the region and more than 15,000 feet below the surface in the center of the Williston Basin in western North Dakota. The Paleozoic, Cretaceous, and Tertiary sedimentary rocks of the Williston Basin gradually thin eastward and are missing in the Rainy River basin and in the southern and eastern parts of the Red River basin. The entire region has been glaciated, and most of the region is covered with glacial deposits that range in thickness from less than a foot to several hundred feet. Sand and gravel deposits in the drift form the most important freshwater aquifers. Other aquifers in the region are in Precambrian Paleozoic, Cretaceous, and Tertiary rocks. The poten- tiometric surface in the bedrock aquifers generally decreases in altitude toward the Red River, indicating that the general direction of ground-water movement is toward the Red River. Ground water with less than 3,000 mg/L dissolved solids is available throughout the Souris-Red-Rainy Region; however, yields are small in places because some aquifers contain highly mineralized water. Ground-water quality in the Rainy River basin generally is better than in the Souris or Red River basins. Ground water with less than 1,000 mg/L of dissolved solids occurs in most of the region east of the Red River and in most of the shallow aquifers west of the Red River. The dissolved-solids concentration generally is less than 500 mg/L in water from the fractured crystalline rock and outwash-delta aquifers and less than 1,000 mg/L in other aquifers in the glacial deposits. The total volume of water available from storage having less than 3,000 mg/L of dissolved solids is estimated to be 5x10® acre-feet. In addition to the fresh and slightly saline water, the region has an abundance of highly mineralized water that also can be considered as a resource. Yields of wells in individual bedrock aquifers are generally less than 100 gal/min but locally yields may be as much as 500 gal/min and more. Yields in drift aquifers are commonly less than 100 gal/min but range from 5 to 1,000 gal/min. In a few places the outwash yields more than 1,000 gal/min. -Water quality rather than quantity is the most important problem for many communities in the region. Excessive K24 natural concentrations of dissolved solids, sulfate, and chloride are common in the western parts. Iron and manganese concentrations also are excessive in many supplies throughout the region. However, at the natural concentration levels none of these constituents are hazar- dous to health. Ground water is the sole or a primary source of water supply in much of the Souris-Red-Rainy Region. In areas distant from streams, and in upland areas where surface water is not available physically, legally, or in the quality required for a particular use, ground water is the sole source of supply. Reportedly, the potential irrigation development is 1,550,- 000 acres as compared with 50,200 acres irrigated in 1978. Both ground- and surface-water supplies will be required to meet these potential demands. Rural domestic and livestock water supplies are derived almost entirely from ground-water sources. Small com- munities and towns generally rely on ground water, and the cities and industries use ground water, surface water, or both. The municipalities using surface water generally depend upon reservoir storage. The quantity of water available to most municipalities has been adequate. Shortages in some areas, however, have occurred during prolonged drought. Communities depend- ing upon ground water have solved such problems by deepening wells or constructing additional ones. For a few communities, potential water shortages persist or may develop in the future as requirements increase. Included are Minot in the Souris River basin, and several cities (such as Neche, Pembina, Grafton, and Mayville, N. Dak., and Crookston, Minn.) that depend on tributaries of the Red River. The largest municipal and industrial water-supply demands are in areas along the main stem of the Red River. As water use increases, however, additional reservoir storage or ground water may be required. Careful analysis and management of this complex water-supply system is warranted. Water supplies in the Rainy River basin are abundant in terms of present and foreseeable requirements. Increased demands on both ground-water and sur- face-water supplies will be made in the future. Storage of water in the ground-water reservoir during times of surplus for withdrawal during times of scarcity would aid in meeting these demands. Similarly the surplus (flood) water is of better chemical quality than underlying ground water in parts of the western half of the region. Freshwater could be stored in saline-water aquifers as well as in freshwater aquifers, and pumped out as needed. The ground-water reservoir has a definite potential in water management. This reservoir volume is larger than all of the surface reservoirs in the region and should be more fully used. Supplies of water adequate for recharging the ground-water reservoir are available in the region during the spring from several rivers and tributaries. The management of floodwater for replenishing ground-water supplies also | M SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES could diminish flooding to some extent. Examples of artificial recharge projects that are operational in the region are at Minot and Valley City, N. Dak. To understand the hydrologic system for management purposes there is a need to determine more adequately the hydrologic and geologic characteristics of existing aquifers, to determine the feasibility of providing treatment for improvement of the quality of water contained in those aquifers, and to locate new, undeveloped aquifers. As pumping and other stresses on one part of the hydrologic system affect other parts, monitoring programs ideally should be started before development and continued to detect changes and determine effects of the stresses. Monitoring - water-level changes, - withdrawals, and ground-water quality can alert managers to approaching problems of diminishing supply, waterlogging of land, or other detrimental effects. A water-quality monitoring program could detect migration of highly mineralized water or of other pollutants in the aquifer and aid in determining corrective action. Information is needed to locate and identify pollution sources. Further research may lead to better means of reducing wastes derived from product processing. Many alternatives are available to planners for managing water. Some of these are operational and others are undergoing research. Many of them require adaptation to specific local situations. Adequate hydrologic information is needed by the water manager Of planner to aid in solving problems of water supply, use, and pollution. REFERENCES CITED Brown, D. L., and Silvey, W. D., 1973, Underground storage and retrieval of fresh water from a brackish-water aquifer in Underground waste management. and artificial recharge: Second Internat. Sym. on Underground Waste Management and Artificial Recharge, New Orleans, p. 379-406. Busby, M. W., 1966, Annual runoff in the conterminous United States: U.S. Geol. Survey Hydrol. Inv. Atlas HA-212. Carlson, C. G., and Anderson, S. B., 1973, Stratigraphy in Mineral and water resources of North Dakota: North Dakota Geol. Survey Bull. 63, p. 30-41. Crosby, O. A., Armstrong, C. A., and Paulson, Q. F., 1973, Water resources of North Dakota in Mineral and water resources of North Dakota: North Dakota Geol. Survey Bull. 63, p. 161-198. Downey, J. S., and Paulson, Q. F., 1974, Predictive modeling of effects of the planned Kindred Lake on ground-water levels and discharge, southeastern North Dakota: U.S. Geol. Survey Water-Resources Inv. 30-74, 22 p. Fenneman, N. M., 1931, Physiography of the Western United States: New York, McGraw-Hill Book Co., 534 p. Ferris, Ted, (chm.), and others, 1972, Water supply and health aspects, Appendix G of Souris-Red-Rainy River basins comprehensive study: Souris-Red-Rainy River Basins Commission, v. 4, 110 p. Feth, J. H., 1965, Selected references on saline ground-water resources of the United States: U.S. Geol. Survey Circ. 499, 30 p. Feth, J. H., and others, 1965, Preliminary map of the conterminous United States showing depth to and quality of shallowest ground water containing more than 1,000 parts per million dissolved solids: U.S. Geol. Survey Hydrol. Inv. Atlas HA-199. SOURIS-RED-RAINY REGION Folsom, C. B., Jr., 1973 Petroleum and natural gas in Mineral and water resources of North Dakota: North Dakota Geol. Survey Bull. 63, p. 99-119. Glover, D. H. (chm.), and others, 1972, Water resources, Appendix B of Souris-Red-Rainy River basins comprehensive study: Souris-Red-Rainy River Basins Commission, v. 2, 80 p. Kelly, T. E., 1967, Artificial recharge at Valley City, North Dakota, 1932 to 1965: Jour. of Ground Water, v. 5, no. 2, April, p. 20-25. Knapp, G. L., 1973, Artificial recharge of ground water - A bibliography: Water Resources Scientific Information Center 73-202, 309 p. Kohler, M. A., Nordenson, T. J., and Baker, D. R., 1959, Evaporation maps of the United States: U.S. Dept. of Commerce Tech. Paper 37, 13 p. McClure, N. A. (chm), and others, 1972, Land resources and watershed management, Appendix C of Souris-Red-Rainy River basins com- prehensive study: Souris-Red-Rainy River Basins Commission, v. 2, 122 p. McGuinness, C. L., 1963, The role of ground water in the National water situation: U.S. Geol. Survey Water-Supply Paper 1800, 1,121 p. McGuinness, C. L., 1969, Scientific or rule-of-thumb techniques of ground-water management-Which will prevail?: U.S. Geol. Survey Circ. 608, 8 p. MacKichan, K. A., and Kammerer, J. C., 1961, Estimated use of water in the United States, 1960, U.S. Geol. Survey Circ. 456, 26 p. Maclay, R. W., Winter, T. C., and Bidwell, L. E., 1972, Water resources of the Red River of the North drainage basin in Minnesota: U.S. Geol. . Survey Water-Resources Inv. 1-72, 129 p. Magin, G. B., Jr., and Randall, L. E., 1960, Review of literature on evaporation suppression: U.S. Geol. Survey Prof. Paper 272-C, p. 53-69. Murray, C. R., 1968, Estimated use of water in the United States, 1965: U.S. Geol. Survey Circ. 556. 53 p. Murray, C. R., and Reeves, E. B., 1972, Estimated use of water in the United States in 1970: U.S. Geol. Survey Circ. 676, 37 p. Government Printing Office: 1978-777-102/26 K25 Rima, D. R., Chase, E. B., and Meyers, B. M., 1971, Subsurface waste disposal by means of wells - A selective annotated bibliography: U.S. Geol. Survey Water-Supply Paper 2020, 305 p. Robinove, C. J., Langford, R. H., and Brookhart, J. W., 1958, Saline water resources of North Dakota: U.S. Geol. Survey Water-Supply Paper 1428, 72 p. Signor, D. C., Growitz, D. J., and Kam, William, 1970, Annotated bibliography on artificial recharge of ground water, 1955-67: U.S. Geol. Survey Water-Supply Paper 1990, 141 p. Souris-Red-Rainy River Basins Commission, 1972, Souris-Red-Rainy River basins comprehensive study: Souris-Red-Rainy River Basins Commission, v. 1, Type I Framework study, 216 p. and Type II study of selected basins, 128 p. Theis, C. V., 1941, The effect of a well on the flow of a nearby stream: Am. Geophys. Union Trans., v. 22, pt. 3, p. 734-738. Todd, D. K., 1959, Annotated bibliography on artificial recharge of ground water through 1954; U.S. Geol. Survey Water-Supply Paper 1477, 115 p. U.S. Bureau of Reclamation, 1973, Water resources development in North Dakota in Mineral and water resources of North Dakota: North Dakota Geol. Survey Bull. 63, p. 199-252. U.S. Department of Commerce, Environmental Science Services Ad- ministration, 1968, Climatic atlas of the United States: 80 p. U.S. Geological Survey, 1970, The National atlas of the U nited States of America: U.S. Geol. Survey, Washington, D. C., 417 p. U.S. Public Health Service, 1962, Drinking water standards - 1962; U.S. Public Health Service Pub. No. 956, 61 p. U.S. Water Resources Council, 1968, The Nation's water resources: Washington, U.S. Govt. Printing Office. Weber, W. R. (chm.), and others, 1972, Irrigation, Appendix F of Souris-Red-Rainy River basins comprehensive study: Souris-Red-Rainy River Basins Commission, v. 4, 69 p. Winslow, A. G., and Kister, L. R., 1956, Saline-water resources of Texas: U.S. Geol. Survey Water-Supply Paper 1365, 105 p. Young, L. A. (chm.), and others, 1972, Water quality and pollution control, Appendix H of Souris-Red-Rainy River basins comprehensive study: Souris-Red-Rainy River Basins Commission, v. 4, 86 p. rar., | \ 7 DAYS seirnges _ 1_ LIBRARY B if Summary Appraisals of the (: Nation's Ground-Water \in 5 Resources-Tennessee Region _ GEOLOGIC A L SURVEYSPR~OFESSIONAL PAPER 813 - ‘I" \\7 |'/\ KENTUCKY 4 xv ;)r\‘f\ f, “$131; # ¥ ————— mony ts in maw ay as Humes no to mcse on on comes V wets n ss mene o ~ = ~*~=1- s s IF 4 A p a j \\ TENNESSEE I ’_/' \-~_l «"* NORTH/CAROLINA "uy ue 1 A \ \ s o U T H & @ ~ k y % CAROLINA SIPP I I. A L A B A M A 1 GEO R GIA % 1 % UN - 81070 'sae}§ pojtup af} UI wfiowwoflm 4 10] pouno;] saoinosay-12}2 4 Sa7e}§ pojtup a kb poystfqe}sa asoup are umoys satrepunog $20in0§23 40;ny4-punoun suoupy ay; fo sipsiniddy Ainumng 'gig 10deq reuotssajorg AaaAing feot8of0a9 'g"n 'satlog au 01 xaput ofdeidoan wen a 2 * ”at * D é} D A xa) | uymyH 04] IVMVH satos \ E€1g 1odeq jeuotssajoig D & a 's'o's'n ut ssard ut 10 poystqnd are s1a1dey;y I I suoypusisap 4o1dpyo s401127 IddISSISSIW iX YIMOT va a suot8ay dTNOOILNVTLY HLAOS ‘ 1212M \D T GJ Seil s & NOLLVNYVTIIX4 I N 4GNY¥D H iI %"" _ f Odv¥o1T00 YIMOT A ) \ N~z¢ m fl I ;, VINHOAITVO 4 \ lin a ivan P _ LLMYTLY-dIn o| &" GPX \\\\\' Nisva Lvaxo [ v4 549V A Fete \\ ssa» / anvTON3 5L ( ANIVU-UIU-SITUNOS Summary Appraisals of the Nation's Ground-Water Resources-Tennessee Region by Ann Zurawski omen man CEOLGGICAL SURVEY PEOFEESSIONAL PAPER 813-L Ground-water development and management opportunities in the region UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1978 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, Secretary GEOLOGICAL SURVEY H. William Menard, Director Library of Congress Cataloging in Publication Data Zurawski, Ann Summary appraisals of the nation's ground-water resources-Tennessee region. (Geological Survey Professional Paper 813-L) Bibliography: p. L34-L35. 1. Water, Underground-Tennessee River watershed. I. Title. II. Series: United States. Geological Survey. Professional Paper 813-L. GBI027.T46Z87 553°'.79°09768 78-606195 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock No. 024-001-03074-8 CONTENTS Page Page ADsIPACt:_.z__. L L1 | Development of the ground-water resource ________------------ L23 Introduction es c 2 Ground-water US@ 23 The ground-water resOUPCe 5 Potential for development = _______----------------------- 283 Ground water and streamflow __ 5 Availability 25 Major aquifers 6 Dependability 25 Unconsolidated aquifers _________-------------------- 7. Treatment needs 25 Carbonate aquifers 7. Cost of development _____________________------_<--- 25 Fractured noncarbonate aquifers ___-__-_-------------- 7 Temperature stability _______-_---------------------- 205 Aquifer productivity 9 Efficiency for small-scale development _______--------- 26 Occurrence of ground Water 10 Supplemental and conjunctive Use-____-_--------------- 26 Blue Ridge 11 Underground storage _________-_-_____----------------- 27 Valley and Ridge 12 Locating a ground-water supply ___-___-_------------------ 28 Cumberland Plateau __________--_----_---------------- 15 Data needs 30 Highland Rim 15 Water-resources management _________-_______------------- 32 Central Bagin' 16") ConclUusIONs ".-.. 32 Coastal Plain 190 | 34 Quality of ground water 20 FiguUrE TABLE bo 18. 19; 20. 21. 22. 23. to ILLUSTRATIONS Page . Map showing Water Resources Council regions of the United States' 12 . Map showing physiographic subdivisions of the Tennessee 3 . Map and graphs showing mean annual and monthly precipitation and mean monthly temperatures for the Tennessee Region ...::: s:. ou pr dr er.: nc tev cs de can. an tur 4 . Diagram showing hydrologic cycle with water budget for a typical stream - 6 . Diagram showing the effect of ground-water levels on streamflow __... L_:L 7 . Hydrograph showing base flow of Buffalo River near Lobelville during 1968 water year 8 . Graph of ground-water recharge in six drainage basing o> 9 . Streamflow-duration curves for six gaging stations -__-. ee Mil. iy al- see- a 11 . Diagram showing kinds of water-bearing openings in the three major types of aquifers in the Tennessee Region -__- 12 . Map showing distribution of major aguifer types 2-1. co 13 . Map showing ranges and median values of specific capacities of selected wells 14 . Sketches showing idealized geologic and hydrologic conditions in each of the physiographic subdivisions of the Tennessee Region. 19" Blue:hidge .... ._.... SLgif o. all init coas coa aon 16 13. valeyand Ridge ~~ .-.."... L.. el cece cta o_ oto ne care tno oo o" 17 14 Cumberland PIALGAU cern icin eae 18 15 Highland Rim. i.... s... leta . o thereat ren cn ~- 19 16. Central Basin "._.. ...... scl.e: _ .._ 20 17. Coastal Plain ull. 21 Map showing results of chemical analyses of ground water from each physiographic subdivision of the Tennessee Region -__- 22 Graphs showing ranges and medians of six chemical constituents in untreated ground water of the Tennesee Region and in the treated, finished water of the 100 largest cities in the United States. dks neon 24 Hydrograph of water level in test well M-1, Manchester, Tenn., showing seasonal trends and response to rainfall -__- 26 Graphs of pumping rate and water levels in well M-157, Colbert County, Ala. during pumping test _________-_------ 27 Illustration showing some of the kinds of data used to derive criteria for locating test well sites ___________--------- 29 Map showing locations of wells in the U.S. Geological Survey observation well 31 TABLES Page . Comparison of water budget of a typical stream in the Tennessee Region with water budgets for Pomperaug and Beaverdam Creek basing ts L10 s g-dgy 20-year low flows at six gaging stations' 12 . Probable yields from the major aquifer types of the Tennessee RegiOn cel 15 . \Water use in the Tennessee Region in 24 II IV English acre-ft (acre-foot) ft (feet) (ft?/s)/mi? (cubic feet per second per square mile) ft*/d (foot squared per day) gal/min (gallons per minute) (gal/min)/ft (gallons per minute per foot) in. (inches) in./yr (inches per year) Mgal/d (million gallons per day) mi (miles) mi (square miles) CONTENTS METRIC UNITS Multiply by 1233 3.048 x 10- 1.093 - 10-2 9.20 x 10 ~* 6.309 x 10 2.0170 x 10! 2.540 x 10+ 2.540 x 10+ 3.785 x 108 1.609 2.590 Metric m* (cubic meter) m (meters) (m*/s)/km? (cubic meter per second per square kilometer) m*/d (meter square per day) L/s (liters per second) (L/s)/m (liters per second per meter) mm (millimeters) mm/yr (millimeters per year) m*/d (cubic meters per day) km (kilometers) km (square kilometers) SUMMARY APPRAISALS OF THE NATIONS CGROUND-W ATER RESOURCES- TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES By Ann ZURAWSKI ABSTRACT Ground water is an abundant and little-used resource in the Ten- nessee Region, a 41,000 square mile area dominated by the Tennes- see River system and including parts of Alabama, Georgia, Ken- tucky, Mississippi, North Carolina, Tennessee, and Virginia. One- fifth to one-fourth of the precipitation that falls on the region enters the ground-water reservoirs. During the year approximately the same amount of water leaves the ground-water system, sustaining the dry-weather flow of streams. Recharge for the region is about 22,000 million gallons per day or 0.5 million gallons per day per square mile. The major types of aquifers in the region are unconsolidated mate- rial (including sand and regolith), carbonate rocks, and fractured noncarbonate rocks. One or more of these aquifer types occurs in each of the six physiographic subdivisions of the region. The produc- tivity of these aquifers depends on their hydraulic properties and on the distribution of these properties. The unconsolidated sand aqui- fers are the most homogeneous in composition and most predictable in occurrence. These aquifers commonly yield 200 to 600 gallons per minute per well depending on the thickness of sand penetrated. The most difficult aquifers to predict in regard to depth and yield are the carbonate rocks. In these aquifers it is possible to drill dry holes within a few hundred feet of wells capable of producing several thousand gallons per minute. However, with an adequate reconnais- sance study to determine the occurrence of ground water and a planned test drilling program, yields of up to 300 gallons per minute per well can be expected in the carbonate aquifers. Potential yields from the fractured noncarbonate aquifers are lower than in the car- bonate rocks. 'The chemical and physical properties of ground water in the Ten- nessee Region are usually within the limits recommended by the Environmental Protection Agency for drinking water, and the ground water in all but some very shallow aquifers tends to be free of pathogenic microorganisms. Saline water is not known to occur in significant quantities in the region. In 1970, 173 million gallons per day of ground water were used in the Tennessee Region. This was less than 8 percent of the total quan- tity of water used in the region and only 0.8 percent of the estimated ground-water recharge. Ground water is used chiefly as a source of water supply for rural areas and small towns. A lesser amount is used by industries and commercial establishments located beyond the limits of municipal water-supply systems. However, there is po- tential for significantly increased use in order to augment surface- water supplies and to utilize the total water resource more effi- ciently. Hydrologic studies and adequate test drilling would greatly in- crease the chances of locating large amounts of ground water, espe- cially in the nine-tenths of the Tennessee Region that is underlain by either carbonate rocks or fractured noncarbonate rocks which have highly variable water-bearing properties. Collectively, such studies are useful in developing a concept of the hydrologic system which would permit the development of criteria for selecting well sites in other areas with a similar geological and hydrological setting. Hy- drologic studies that include test drilling have been conducted in all parts of the region except the Cumberland Plateau. Some of the basic data necessary for hydrologic studies, such as geologic maps, well records, and streamflow records are available throughout the region. However, detailed information on ground- water levels, ground-water quality, and aquifer characteristics are not equally available throughout the region. This type of information cannot be obtained quickly when it is needed; it must be the product of a continuing program of studies designed to evaluate the Tennes- see Region's ground-water resource. Because of the interdependence of ground water and surface water, water management efforts can be fully effective only if they involve the whole water resource. In the Tennessee Region, surface water is highly controlled, but there is at present no regionwide water- resources management plan that includes ground water. INTRODUCTION The significance of ground water as a resource is often not fully recognized in areas where surface water is abundant. Ground water is hidden from view, and requires special techniques to define its occurrence and availability. Planners and water managers who make decisions affecting development of water resources do not always have adequate information with which to evaluate ground water as an alternate or supplemental source of water. In order to demonstrate that the Nation's ground water is a large and important resource, the U.S. Geological Survey has undertaken a broad-perspective appraisal of the ground-water resources in each of the 21 regions into which the United States has been di- vided by the Water Resources Council (fig. 1). The pur- pose of these regional appraisals is to show that in many parts of the Nation, ground water can play a significant role in regional water supply and that it warrants further study and consideration in regional developmental planning. L1 L2 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES -- ~-. 1 ARKkansas-wHite- kep 400MILES a* g TpKouai OanuCb -_ Molokai 2 Aleutian O TOMaui Puerto ..: me Island: < Rico Virgin 0 HAWaAHi Islands Howaii T c 0 400 MILES 0 I5OMILES 0 80 MILES CARIBBEAN FIGURE 1.-Water Resources Council regions of the United States. The Tennessee Region coincides with the Tennessee River basin, an area of 41,000 mi? which lies mainly in Tennessee, Alabama, and North Carolina but includes small parts of Virginia, Georgia, Kentucky, and Mississippi. This diverse area includes parts of six physiographic provinces each having distinctive topog- raphy and geology (fig. 2). The Tennessee River system has played a major role in the region's development. Historically, severe flood- ing along the Tennessee River hindered industrializa- tion of the region. The Tennessee Valley Authority, created by Congress in 1933 as a regional resource de- velopment agency, very early began to construct dams along the Tennessee to control flooding, promote navi- gation and produce electric power. The harnessing of the river was followed by industrialization, population growth, and a higher standard of living. The flow of the Tennessee River and its tributaries, however, is only a small part of the region's water re- sources. In July of 1973, a record 10.3 million acre-ft of useable water was stored in the Tennessee River's res- ervoir system (Tennessee Valley Authority, 1973). This is 450 billion ft? of water. M. I. Kaufman (written commun. 1975) estimated that 25,800 billion ft? of ground water was available from storage in the Ten- nessee Region. While that approximated figure is dif- ficult to verify, it is indicative of the magnitude of difference between ground-water and surface-water storage even for a fully regulated river system. In many areas where surface water is not available, large quantities of ground water are available for develop- ment. Ground water has been a neglected resource in the Tennessee Region, but because of increasing pres- sure to utilize all resources in the most efficient and L3 TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES '(gz61 pus ag104eT pu® '€E61 'symg 'gzge1 'saoygo pue surepy 'p161 '"ollW 'A96t '3uny wou poytpou) uot8ay aossouuay, oy} JO suotstaAtpqns 4H40D14 Prac] ob8 / ) | po 0 cc | _ | mes. 7 | I T T nNolivis ouwmwuwox “fig“, awwamuflm w \ - fA scn .. oP 10. 9.40! 098 AYaNnno! : . . } /.f fl lllll D i aAwannose nNisvae--~*~> IS »I *! S § I W J . - # *A N‘ , fl/xm A* % f a.» 9€ <4 | N +. IV Eia aanvs 919 iv ; , N “Kw \\% AjOW3 TTS 9 T N NY IL b & C +4 AR". #4 o mn e oe .~ A ~ \& g=~~ A M ov8 +98 88 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES L4 uotdoy aoss s3TImw Os or og oz or 0371 6§-S261 aolM34 HY3A S vos A NOLLVLIdIOJMd TVNNNV NV3W NISVS H3JAIY 33SSINN3L viva A8 dVW WoW: 0314100w % 70H1N09 #3LW¥M 10 NOISIAIG AITIIWA 33SS3NN3L ay 9 g yoon w y w an U U I T T T t - us 3 OL61-i¥6!1 'Noig3x 3JSSINN3L 3H1L NI 1 fl * 0 ouuaf, oy} 10J sommjeoduuoy 4ryjuow ueaw pure uorgeqidroord pue renuue ueep-*¢ AHVONNOG8 Nisve «- S3N17 3LV1G - - _._ saHonl ni 17v4niva \. os- NOILVNYVT14X3 3UNLYVHMI3IWN3L AIHLNON NY3W 09 SE 29€ I 6S61-0681 'Noig93y 33SSSNN3L 3H1L NI NOILYLIdID3Md AIHLNOW NY3W - NoSv3S oNImo#9 "G e ado w TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES productive manner, ground water is now being recog- nized as an integral part of the region's water re- sources. This report synthesizes the results of previous studies in the Tennessee Region and appraises the role of ground water in the hydrologic systems of the Ten- nessee Region. It provides an overview of the occur- rence of ground water, its present and potential use, and the need for management of ground water as an integral part of the water resources of the region. THE ATER RESOURCE GROUND WATER AND STREAMFLOW The source of both surface and ground water is pre- cipitation. In an average year, precipitation in the Tennessee Region ranges from 40 in. in the northern Valley and Ridge province to 85 in. in the mountainous eastern part (fig. 3). The average for the region is 52 in. (Tennessee Valley Authority, 1975). In a normal year, most precipitation occurs in the winter and spring months, least in the summer and fall months. About 60 percent of the yearly precipitation returns to the atmosphere by evaporation and the transpiration of plants. Rates of evapotranspiration are highest during the hot, dry months when plants are growing. Of the remaining 40 percent of the precipitation, a part flows overland into streams and a part percolates into the ground to replenish, or recharge, the ground-water res- ervoirs (fig. 4). Water entering the ground-water reservoirs is stored in the pore spaces in unconsolidated deposits and weathered rock, or in fractures and solution openings in the bedrock. Characteristically, all ground water in storage moves toward areas of discharge such as springs, streams, and wells. Water levels are related to the amount of water available to the base flow of streams and the volume of water that can be stored in the ground-water reservoir. The effect that water-level fluctuation has on streamflow in areas underlain by a limestone aquifer with a thin soil cover is shown in figure 5. Ground water in these areas is discharged rapidly during periods of little or no rainfall, causing a decline in ground-water levels in the aquifer which results in the depletion of streamflow. Streams that cut deeply into thick, unconsolidated aquifers have sustained streamflow even through long periods of dry weather because of the slow release of ground water from these aquifers. In most aquifers, the replenishment of ground water at times exceeds the outflow or vice versa, but over a long period the recharge and discharge are about equal, so that ground-water discharge in a nor- mal year can be approximately equated with the aver- age annual base flow of streams. L5 The amount of ground-water recharge in the Ten- nessee Region was estimated using hydrographs of streamflow at six gaging stations during the 1968 water year, a year of nearly average streamflow across the region. Hydrograph separations were made to ob- tain maximum and minimum estimates of base flow (fig. 6). The values obtained ranged from 5 to 16 in./yr or 13 to 33 percent of the year's precipitation (fig. 7). The average rate of recharge for the region as a whole is estimated to be between 10 to 13 in./yr or 19 to 25 percent of the precipitation. This is about 0.5 (Mgal/ d)/mi? or 22,000 Mgal/d for the entire region. The water budget shown in figure 4 is typical for the region. The numbers agree with previous water budget studies in the Pomperaug River basin in Connecticut, a basin underlain by fractured crystalline rocks and thin gla- cial drift (Meinzer and Stearns, 1929) and Beaverdam Creek basin in Maryland, underlain by coastal plain deposits (Rasmussen and Andreasen, 1957; table 1). Since the hydrologic properties of the aquifers in the Tennessee Region are intermediate between those of the other two basins, it is reasonable that the water budget figures for the Tennessee Region as a whole fall between those of the other two studies. Average re- charge figures can serve only as a rough guide to the amounts of ground water available for withdrawal be- cause they describe only the annual amount of water passing through the system, only part of which can be captured by wells. Flow-duration curves of streams are, in part, indi- cators of the water-storing properties of aquifers. A flow-duration curve is constructed by plotting specified streamflows against the percentage of time they are equalled or exceeded at a gaging station. The streamflow at any time depends on the climate, drain- age area, topography, overburden, and geology of the basin. Variations in these factors from one basin to another result in a variety of shapes of flow-duration curves (Burchett and Moore, 1971). The shape of the low-flow portions of duration curves is controlled chiefly by the geology of the basin (Searcy, 1959) and is indicative of the interaction of ground water and sur- face water in the basin. Flow-duration curves of six long-term gaging sta- tions on unregulated streams in the Tennessee Region are shown in figure 8. Each curve is representative of the flow characteristics of streams in a particular physiographic province. The effects of the difference in size of drainage areas have been minimized by plotting the streamflow in cubic feet per second per square mile. The decreasing slope of four of the duration curves shows that those streams have well-sustained base flow indicating the ability of unconsolidated aquifer material to store and release water slowly. Big Sandy River at Bruceton, Tenn., traverses unconsolidated L6 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES | TRA ION I at z RAINFALL g a s TRANSPIRATION w a" (\ 2 a As 3 Coyvh EVAPORATIO f 33339) A I overiando A A / Ck w... FLOW ECS @ ) L_ _- WINTER WATER Tasie __) [} _ Noy Pry, } P5 T" __. __ --SUMMER Wareg Ati c Yow "s te :4 ( E \y. STREAM ” lNFIlTRATIOthE Q ~ {-. /L v came | ween t "sed DISCHARGE-LOw lis TYPICAL WATER BUDGET Average rainfall over drainage area --- Stream discharge---------._._.__ Inches 50.2 21.5 Low flow- e Overland Evaporation and transpiration-------- 11.5 10.0 28.7. Froure 4.-Hydrologic cycle and water budget for a typical stream in the Tennessee Region based on average of values for six drainage basins. (Hydrologic cycle from Burchett, 1977.) sand. Buffalo River near Lobelville, Tenn., Clinch River above Tazewell, Tenn., and Little River near Maryville, Tenn., are in areas covered by thick regolith. The curves for Wartrace Creek at Bell Buckle, Tenn., and Emory River at Oakdale, Tenn., are markedly dif- ferent from the other curves, indicating the low water- storing properties of the rock underlying the basins and the very poorly sustained low flows. The curve for Emory River at Oakdale shows the low storage ca- pacity of the fractured rocks capping the Cumberland Plateau. The curve for Wartrace Creek shows the low storage and rapid release of ground water in flat-lying limestone aquifers of the Central Basin. Intercon- nected solution openings in the limestone rapidly dis- charge the water that is temporarily stored above stream level. Low-flow frequency analyses for these gaging stations also show that base flow of Emory River and Wartrace Creek is much more poorly sus- tained than that of the other four streams (table 2). MAJOR AQUIFERS Three types of aquifers occur in the Tennessee Re- gion: unconsolidated material with intergranular TENNESSEE REGION, GROUND-WATER LEVEL IS FLOWING STREAM IS DRY INCLUDING PART OF TENNESSEE AND ADJACENT STATES DURING WET WEATHER- OUND-WATER LEVEL AFTER A LONG PERIOD OF DRY WEATHER- L7 (yA ? ( 'A /J V a C/ Ficur® 5.-Ground-water levels in an unconfined aquifer affect streamflow. In this limestone aquifer, typical of the Central Basin, recharge is stored temporarily above stream level. When there is a gradient toward the stream, ground water is discharged to the stream, sustaining its flow. As solution openings are drained, the water table becomes almost flat at or below the stream level, and streamflow ceases. porosity, carbonate rocks with solution openings, and noncarbonate rocks with fractures (fig. 9). One or more of these aquifers is characteristic of each physiographic province (fig. 10). UNCONSOLIDATED AQUIFERS Uconsolidated materials are significant aquifers in about half of the Tennessee Region (fig. 10). In. the Coastal Plain, an area of 4,000 mi? on the western edge of the region, the important aquifers are sand forma- tions which dip to the west. These formations are the most uniformly productive aquifers of the region, commonly yielding 200 to 600 gal/min to single wells. Parts of another 18,000 mi? are covered by unconsoli- dated materials, referred to as regolith, which is a mantle of disintegrated rock that has accumulated over the bedrock. Grain size ranges from clay to coarse gravel and is a major factor in determining the reg- olith's water-bearing properties. The regolith is hy- drologically significant in areas where it is thick and permeable, especially in the Highland Rim and parts of the Blue Ridge and Valley and Ridge. In these areas it acts as a sponge in absorbing and storing large amounts of ground water. Where saturated, the reg- olith yields dependable domestic supplies, but larger supplies can be obtained where fractures or solution openings in the underlying bedrock are hydraulically connected with the regolith. CARBONATE AQUIFERS Carbonate aquifers underlie about half of the Ten- nessee Region (fig. 10). The rocks in the Valley and Ridge section of the region are steeply tilted and west of the Valley and Ridge are essentially flat lying. Water occurs in openings along fractures, faults, and bedding planes which have become enlarged by cir- culating ground water. Solution openings occupy a small volume in the rock and generally occur within about 300 ft of land surface. Individual openings range from a fraction of an inch to several feet in height and can be laterally extensive. Wells that penetrate large openings may be able to produce several thousand gal- lons per minute, but such openings occupy a small pro- portion of the rock. As a result, well yields vary widely in carbonate terrane. For example, at Franklin, Tenn., in the Central Basin just north of the Tennessee Re- gion, two test wells 100 ft apart produced 18 and about 180 gal/min respectively. Variability of solution open- ings makes well placement critical in efforts to develop large amounts of ground water from carbonate rocks. FRACTURED NONCARBONATE AQUIFERS Slightly more than a third of the Tennessee Region is underlain by noncarbonate rocks which, unlike the Coastal Plain deposits, have very little porosity aside from fractures. These rocks range from sedimentary rocks such as shale and sandstone underlying the Cumberland Plateau to rocks that have been subjected to metamorphism and deformation in the Blue Ridge. Weathering along fractures and faults has created av- enues for water movement. These fracture openings probably comprise less than 1 percent of the rock vol- ume, and water-bearing fractures are uncommon at SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES L8 (69617) weysurg pue 'pmauyouing 'or00py pue (¢961) nomusuny pue 4qsng 4q paqt1asap 121 go uoreaytpow e st poyjou stg, 'yeod je; skep 9 qurod ay; 03 out 14Stenqs e 4q poutof 'xead Sutmof[o; ay} Jo Aep ay; 03 popua3xa sem aano uotssada1 yoea 'wunwtrurnu 04} 104 'ast1 03 uedaq ureans ay; acoum qutod ay; 03 yead 04} wor; umeip uoyy sem out uy "yead ayy jo Lep ayy 03 yoeq pogoaford azom yead yorea 19ye skep 9 wou; saamo 043 'mopino 19gem-puno18 umuwtxew 043 40g 'rea4 copem gogt 10; poutuug;op sem mogurea ns 03 wuinwrurtu pue nwIxeJq ay; wor st moy pue 'utseq a sey goun. puejiaAo skep 9 noge 19yy 'mogureans Jo xeak e 'Teak gogt ay; Butinp af[1A4faqo7 eau T0ATY Ofeygng Jo moy aseg-9 sunor1 moO ISVq QI1¥WILS3 wWhWINIW mOlH ISY¥q whnwixvyw OL S 000'L 000'OL aN0OD3S 1434 1331 I9NJ NI TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES HIGHLAND RIM BUFFALO RIVER NEAR LOBELVILLE, TENN. CENTRAL BASIN WARTRACE CREEK AT BELL BUCKLE, TENN. COASTAL PLAIN BIG SANDY RIVER AT BRUCETON, TENN. 20 RECHARGE Ind |f Il W 10 RECHARGE, IN INCHES 17-20 23-33 20-31 d L9 BLUE RIDGE LITTLE RIVER NEAR MARYVILLE, TENN. VALLEY AND RIDGE CLINCH RIVER ABOVE TAZEWELL, TENN. CUMBERLAND PLATEAU EMORY RIVER AT OAKDALE, TENN. FOR REGION 1.5 INCHES cae cum cum 10-31 13-23 22-29 RECHARGE AS PERCENT OF 1968 RAINFALL IN EACH DRAINAGE BASIN Ficur® 7.-Ground-water recharge (not including ground-water evapotranspiration) in 1968 in six drainage basins in the Tennessee region, average of the maximum and minimum values for the six depths over 300 ft (McMaster and Hubbard, 1970). The fractures at greater depths are likely to be unweath- ered and closed. Fractures are commonly more abun- dant near faults. Well production is determined by the depth, size, and degree of interconnection of fractures penetrated and by the thickness of overburden hydrau- lically connected to the fractures. Fractured rocks are generally considered to be poor aquifers, but they have generally not been adequately tested to determine their water-yielding potential. Newcome and Smith (1958) report that wells producing 50 gal/min or more are rare on the Cumberland Plateau. However, the town of Wartburg, Tenn., has three wells which, at the time they were drilled, were and recharge for the region. This value is the basins. reported to produce more than 100 gal/min each. Test drilling in the Great Smoky Mountains National Park (McMaster and Hubbard, 1970) showed that where fractured rock is hydraulically connected to thick reg- olith, properly located wells can produce 100 gal/min or more. AQUIFER PRODUCTIVITY Aquifer productivity as used in this report refers to the rate at which ground water can be withdrawn from an aquifer at a particular locality on a continuing basis by means of a well or group of wells. Well yields are determined by the hydraulic properties of the aquifer. In the Tennessee Region, however, the areal variabil- ity in properties of the aquifers, combined with lack of L10 TABLE 1.-Comparison of water budget of a typical stream in the Tennessee Region with water budgets for Pomperaug River and Beaverdam Creek basins. [Values are given as percent of precipitation .} Tennessee Pomperaug Beaverdam Basin Creek Basin Region Evapotranspiration ______ 52.2 60.7 57.2 Total runoff (streamflow) __________ 46.4 36.1 42.8 Ground-water runoff (base 2 19.6 25.9 22.9 Change in storage ______ 1.4 2.1 Not calculated data for many areas make the definition of aquifer pro- ductivity difficult. Several approaches can be sed to quantify aquifer productivity. The basic hydraulic properties of an aquifer are transmissivity (the rate at which water can be transmitted through the aquifer) and storage (related to the amount of water that is released by draining part of a water-table aquifer or lowering the pressure in an artesian aquifer). The more nearly an aquifer approaches uniformity in its water-bearing properties, the more applicable are these measures of hydraulic characteristics. In the Tennessee Region, the unconsolidated aqui- fers of the Coastal Plain section, on the western margin of the region, are the lest variable in their hydraulic properties. Two aquifer tests indicate transmissivity of 3,300 and 4,300 ft*/d and storage coefficients of 0.0008 and 0.0001 for the McNairy Sand, a confined uncon- solidated aquifer (Boswell and others, 1965). However, nine-tenths of the region is underlain by carbonate or fractured noncarbonate aquifers which are far from uniform in their hydraulic properties. Five aquifer tests in Madison County, Ala., indicate transmissivity ranging from 650 to 130,000 ft*/d and storage coeffi- cients of 0.04 to 0.0004 for the Fort Payne Chert (Malmberg and Downing, 1957). A similar large varia- bility in aquifer hydraulic properties is evident from the results of aquifer tests made elsewhere in the Ten- nessee Region and is typical of carbonate aquifers. Another indicator of aquifer productivity is the specific capacity of wells, the rate of yield per unit of drawdown. Although specific capacity is influenced in part by conditions in and around the well, properly qualified specific capacity data can indicate the prop- erties of the aquifer. The ranges of specific capacities shown in figure 11 illustrate the high degree of varia- bility in the hydraulic properties of aquifers of the Tennessee Region, although some of the low values may be the result of poor well design rather than aquifer properties. This variability is of critical im- portance in developing a ground-water supply because the more variable the aquifer productivity, the greater SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES the risk of failure to obtain the desired amount of ground water at a particular site. In the Tennessee Region, the least variability of yields is from wells that tap unconsolidated aquifers. The greatest variability is in carbonate-rock aquifers covered by thin or patchy mantles of regolith. In economic terms, greater varia- bility in yields means that more preliminary study, more test wells, and more flexibility in well location will probably be needed to obtain a desired amount of ground water. Another approach to quantifying aquifer produc- tivity is to estimate probable yields that could be ob- tained from wells located on the basis of geologic and hydrologic information. Table 3 shows yields that might be expected from different types of aquifers in the Tennessee Region. These yields are for single wells constructed to obtain maximum yield having at least 50 ft of available drawdown. The numbers are based on figures given by Cederstrom (1973) for areas with geol- ogy similar to that of the Tennessee Region and on inferences drawn from records of well production in the region. Ground-water withdrawals are ultimately lim- ited by the rate of recharge to the aquifer. In the Ten- nessee region, maximum withdrawals on a continuing basis are about 0.5 Mgal/d per square mile of area con- tributing recharge to the system. Efficient and economical development of the ground-water resources of the Tennessee Region are strongly influenced by the variability of aquifer pro- ductivity. Predictability of well yields and the avail- ability of ground-water supplies at particular sites is greatest in the Coastal Plain sand aquifers and the regolith-mantled carbonate rocks. Hence, it is probable that ground-water development will proceed most effi- ciently in these areas. The predictability of obtaining a ground-water supply is poorest in the noncarbonate rocks and in the carbonate rocks that have no regolith cover. In these areas, development will be less efficient until methods are developed to locate permeable zones and predict well yields with greater accuracy. OCCURRENCE OF GROUND WATER The distribution of ground water in the Tennessee Region is influenced by the difference in topography, geology, and hydrology among the six physiographic provinces (fig. 2). Though large amounts of ground water exist in each physiographic area, less prelimi- nary study and exploratory drilling are usually needed to obtain a specified supply in areas where the ground water occurs in the intergranular pore spaces of uncon- solidated aquifers, than in areas where water occurs in discrete fractures or openings in consolidated rocks. The following sections describe for each physiographic area the topographic, geologic, and hydrologic controls on the distribution of ground water. TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES Al F-T-T TTH | mamas PROVINCE BLUE RIDGE GAGING STATION A LITTLE RIVER NEAR MARYVILLE, TENN - DRAINAGE AREA - 269 MI* -I VALLEY AND RIDGE-CLINCH RIVER ABOVE TAZEWELL, TENN. DRAINAGE AREA - 1474 MI* ; CUMBERLAND PLATEAU - EMORY RIVER AT OAKDALE, TENN- DRAINAGE AREA - 764 MI" HIGHLAND Rim -- BUFFALO RIVER NEAR LOBELVILLE, TENN. DRAINAGE AREA - 707 Mi* CENTRAL BASIN -WARTRACE CREEK AT BELL BUCKLE, TENN. DRAINAGE AREA - 16.3 M* BIG SANDY RIVER AT BRUCETON, TENN. COASTAL PLAIN DRAINAGE AREA - 205 Mi* Ld I N Lor d \ | L._._..l lllIIll\Illll| .5 1 2 100 C § °F - A L pst a~ "[> p -a e» 3 ° to § C Q4._ ~ F Z..— O - aL. 4] jcal 2 aE m m: .L Aa E [sal E 1x4 n ® C - E m— ). ~f. O.— 2, a a_ B‘— (a») h E a < mA Co . & +! m— .01 PERCE 5 10 20 30 40 50 60 70 80 90 95 98 99.5 99.9 99.99 99 99.8 NT OF TIME INDICATED STREAMFLOW WAS EQUALLED OR EXCEEDED FicurE 8. -Streamflow-duration curves for six gaging stations in the Tennessee Region. BLUE RIDGE The part of the Tennessee Region that lies within the Blue Ridge province is composed of remnants of an an- cient mountain chain. The topography is rugged and relief is greater than in other parts of the region. In most places, the dense, massive bedrock contains little water except where faulted or fractured. Overlying the bedrock is a mantle of regolith that ranges in thickness from a few feet on the steeper slopes to more than 100 ft on the lower slopes of the mountains. The regolith is composed of sand, clay, and rock fragments (McMaster and Hubbard, 1970). It stores large amounts of water, releasing it slowly to the underlying fractures and to springs and streams. The fractures store only limited L12 TABLE 2.-3-day 20-year low flows at six gaging stations in the Tennessee Region 3-day 20-year low flow Province Station in cubic feet per second per square mile Blue Ridge Little River at 0.17 Maryville, Tenn. Clinch River above .08 Tazewell, Tenn. Emory River at 0005 Oakdale, Tenn. Buffalo River near .22 Lobelville, Tenn. Wartrace Creek at Bell Buckle, Tenn. Big Sandy River at 16 Bruceton, Tenn. Valley and Ridge ______ Cumberland Plateau __ Highland Rim ________ Central Basin ________ Coastal Plain amounts of water, but they act as collectors which transmit water from the overlying regolith to points of discharge (fig. 12). Most of the bedrock in the Blue Ridge is noncarbonate, but a few areas are underlain by intensely weathered carbonate rocks that contain large amounts of ground water in solution openings and in porous zones. In the Blue Ridge province, McMaster and Hubbard (1970) and LeGrand (1967) determined that the chances of drilling high-producing wells are increased at sites having a thick cover of regolith in relatively low topographic positions within a few hundred feet of a fault zone. The broad valleys underlain by carbonate rocks, such as Cades Cove in the Great Smoky Moun- tains National Park, may be favorable sites for locat- ing ground-water supplies. However, these occur only in a few small areas of the Blue Ridge. VALLEY AND RIDGE The Valley and Ridge province is characterized by northeast-trending ridges underlain by resistant rock separated by valleys underlain by less resistant rock. UNCONSOLIDATED AQUIFER CARBONATE ROCK AQUIFER SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES The rock formations crop out in long, narrow belts par- allel to the trend of ridges and valleys; some belts are bounded by faults. The linear ridges and valleys chan- nel surface drainage into a "trellis" pattern of long streams flowing along valley floors fed by short lateral streams. All three major aquifer types occur in the Valley and Ridge province. Because of the great differences in hy- draulic characteristics among these aquifers, geologic maps are essential tools for well-site selection in this province. The shale and sandstone formations (frac- tured noncarbonate rocks) are the poorest aquifers. Limestone and dolomite of varying solubility occur with a cover of regolith ranging in thickness from a few feet to over 100 ft with extreme areal variability (DeBuchananne and Richardson, 1956). The largest ground-water supplies are in the soluble carbonate rocks, especially where they are associated with thick regolith (fig. 13). Water moves through enlarged frac- tures and solution openings in these carbonate rocks, emerging in places as large springs. Some of these flow at an average rate of 4,500 gal/min or more (Sun and others, 1963). The Knox Dolomite, which underlies about 60 percent of the province, is the most significant water-bearing formation. The most productive wells are located in areas of ground-water discharge such as stream valleys or else they penetrate fracture zones. These fracture zones are sometimes indicated by straight stream segments and aligned tributaries. Most of the larger water-bearing openings in the Knox occur at a depth of less than 300 ft. Swingle (1959) states that surface faults indicate areas with deep and numerous fractures which allow deep solution activity. Wells tapping water-filled solution openings in low areas are more dependable as a source of water supply than wells on ridges because the seasonal fluctuations of water level are small in the low areas. NONCARBONATE ROCK AQUIFER FicurE 9.-The three major types of aquifers in the Tennessee Region, distinguished by the kind of water-bearing openings they contain (after Meinzer, 1923). L13 'uorgay sossauuay, oy, ut sad44 19jimbe sofew jo uor;nqlLysi(-*'0 1@v 10 SY14V I TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES (§ INYIIHINOIS A11¥319010 40AH QMOOQ Ag NIVTHIGNN VIdVY fesse HL11093% LNYOIHMINOIS MI1YVII9OO108§0AH HLLIM sy34Indv Ad NIYV1430NN Y334V H:: sy311noyv Ssy31INnO¥ 11IYNOGHYINON Ag NIV13430NN sy31INnD¥ IJ1YNOGHYD Ad NIY1430NN sy11inbov soOfVW 14V sNOILYW 304 anwvs q@1lvalmnosno>nn HDIHM Ni Y34V * s14AL ¥31IN0Y #OTVW _ "/ _ | 4 -a vay " sawoo Or og. 0 01 02 RSS C : 0059 A/S avos " A t=n | /\ X. : tp QUO‘Q * “V. I pay vo £ 32 Cs §MOM3MGQ s mg“. ® een e Ca on se 0 C ] L l -L «C2 | 1 T L_ of Carroll County, Tenn. The amount of water that can be withdrawn from these formations depends, in part, on the thickness of saturated sand layers and the con- struction of the wells that penetrate them. In northern Mississippi, test wells in a shattered Paleozoic chert aquifer produced up to 550 gal/min with a specific capacity of 5 (gal/min)/ft (Newcome and Callahan, 1964). The Camden Chert and Fort Payne Chert comprise this fractured chert aquifer in Tennes- see (Wells, 1933). QUALITY OF GROUND WATER The natural quality of ground water in the Tennes- see Region depends on many factors, but mainly upon the chemical composition of the rock in which the water occurs. When water from precipitation enters the aquifer as recharge, it is generally low in dissolved solids, soft, and slightly acidic. As the water moves through the aquifer it acquires a greater concentration of dissolved constituents which change its chemical and physical properties. The least change occurs in the aquifers composed of regolith. The ground water in the regolith remains slightly acidic and low in dissolved About 1500 feet Drawing not to scale FIGURE 16.-Sketch howing idealized geologic and hydrologic conditions in the Central Basin (Nashville Basin section of the Interior Low Plateaus province). L+ solids. This type of ground water is common in the regolith of the Blue Ridge and Highland Rim. Water in the outcrop belt (recharge area) of the unconsolidated aquifers of the Coastal Plain is also fairly close to rainwater in composition, but becomes harder and higher in dissolved solids as it moves deeper below land surface. Ground water that comes in contact with sandstone and shale containing pyrite remains soft but may be- come more acidic and high in concentrations of iron and hydrogen sulfide. This type of water occurs in some noncarbonate formations of the Valley and Ridge, in the Pennsylvanian shale and sandstone of the Cumber- land Plateau, and immediately below the Chattanooga Shale of the Highland Rim. A third kind of change occurs in water that contacts carbonate rocks. Because rainwater that has passed through the soil is somewhat acidic, it can dissolve limestone and dolomite, becoming enriched in bicarbo- nate, calcium, and magnesium. As the dissolved solids content increases, the water becomes harder and slightly alkaline. This type of chemical change occurs in carbonate aquifers such as those in the Valley and TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES N L21 Mississippi River - Tennessee River drainage divide Recharge Recharge O7 Z&A PPF /QCJ Owl Creek | About 50 miles Predominant lithology [ZZZ] Sand 300 y £3 Limestone 'the Drawing not to scale FIGURE 17.-Sketch showing idealized geologic and hydrologic conditions in the Coastal Plain province. The cross section extends east and west approximately at a latitude of 35°N. Ridge, the Highland Rim, the Central Basin, Sequatchie Valley of the Cumberland Plateau, and in limestones underlying coves of the Blue Ridge. The analyses shown in figure 18 are representative of the chemical quality of the ground water from the six physiographic areas of Tennessee. Dissolved con- stituents, consisting mainly of calcium and bicarbo- nate ions, are highest in the ground water of the Cen- tral Basin, with somewhat lower concentrations in the Highland Rim and Valley and Ridge. Unlike aquifers of the Central Basin, aquifers in the latter two areas do not consist entirely of carbonate rocks, and the influ- ence of the regolith and other noncarbonate rocks is seen in the lower amounts of dissolved constituents, including calcium and bicarbonate. The analyses for the Blue Ridge, Cumberland Plateau, and Coastal Plain, all areas with mainly non- carbonate aquifers, indicate considerably lower dis- solved solids in the ground water of these areas than in carbonate terranes. In the Blue Ridge, where most of the ground water occurs in the highly weathered reg- olith, dissolved solids are lowest. L232 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES Values are medians, in milligrams per liter a 2; Physiographic g 5 § FR R $ P Province 8 g 8 g a f r I: I: g { i 1 g a a a w o o Pyi 2° } -$ f fee? jag g 4 $ u H o g ua Ba m ua o Fa Z 1 Blue Ridge 16 0.05 4.6 0.5 3.3 0.8 29 1.6 0.9 0.1 0.1 2 Valley and 10 0.09 _ 38 12 4.5 178 5 3.5 0.0 3.9 Ridge 3 Cumberland 6.4 - 1.0 16 3.5 3.9 1.2 60 10 2.8 0.1 0.8 Plateau 4 Highland Rim 11.5 0.00 39 3.8 3.4 146 4.2 4.0 0.1 1.9 5 Central Basin 73 ::0.08, 79 9.7 4.4 1.5 256 26 5.0 0.3 0.53 6 Coastal Plain 14 0.5 16 4.6 22 3.4 0.7 Q Z < «-I I O "C 100 Source of analyses: 1, McMaster and Hubbard, 1970, 23 samples; 2, DeBuchananne and Richardson, 1950, 235 samples; 3, Newcome and Smith, 1958, 13 samples; 4, Geol. Survey of Alabama bulletins, 125 sam- ples; 5, U.S.G.S. test wells at Columbia, Normandy, and Franklin, Tenn., 22 samples; 6, Boswell, Moore, MacCary, and others, 1965, median for Ripley Fm. (McNairy Sand), number of samples unknown. FIGURE 18.-Results of chemical analyses of ground-water samples from each physiographic subdivision of the Tennessee Region. Ground-water quality is reflected in the chemical character of stream water during periods of base flow. To some extent, streams can be used to obtain an inte- grated sample of discharge from the aquifers underly- ing the watershed. Betson and McMaster (1975) have developed, for the Tennessee River basin, a model to simulate mineral constituent concentrations in streamflow for watersheds underlain by different types of rock. Concentration values generated using their re- gression coefficients and a streamflow of 1 (ft?/s)/mi? agree fairly closely with the analyses in figure 18 when the coefficients used are those for rock types most commonly found in each physiographic province. The rate of water circulation within the aquifer has an important effect on ground-water quality. Where circulation has been rapid, aquifers may have been flushed of readily dissolved substances. Where the reg- olith is hydraulically connected to well-developed openings in the underlying bedrock, for example, water from the regolith, low in dissolved solids, can circulate rapidly through the openings without great increases in hardness. As a result of situations like these, water from wells that tap very permeable formations or highly developed solution or fracture systems tends to be lower in dissolved solids than water from poorly interconnected openings. The quality of ground water from a particular aquifer at any one place tends to be relatively constant with time. This property is most evident where the regolith filters the water that replenishes the aquifer. In aquifers having direct connections with land surface (via sinkholes, for example), marked changes in qual- ity may occur as storm runoff enters the system. Well-developed openings and highly porous mate- TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES rial, when less than about 100 ft below land surface are very susceptible to pollution, and strong protective measures are needed to ensure that the ground-water quality will remain unimpaired. A study sponsored by the U.S. Public Health Service identified a high incidence of contamination of rural domestic water supplies in three counties in Tennes- see, as shown by the presence of coliform and fecal coliform bacteria in water samples (Bureau of Water Hygiene, 1971). Fifty-nine percent of the water supplies examined failed to meet bacteriological standards. However, according to the report, nearly every one of the rural, individual systems examined had one or more facility deficiencies. Very few of these systems were constructed to prevent entrance of con- tamination. It is entirely probable that they represent contamination at the well site and not of the aquifers that furnish water to the wells. Water obtained from relatively deep aquifers penetrated by test wells has usually contained very few, if any, coliform bacteria, and it is not unusual for the water to be entirely free of any indications of contamination. Most of the ground water in the Tennessee Region is of suitable chemical character for public drinking- water supplies. Figure 19 shows the medians and ranges of some of the chemical constituents for which maximum concentrations have been recommended by the Environmental Protection Agency (National Academy of Science-National Academy of Engineer- ing,; 1972; Environmental Protection Agency, 1975). In two areas the median values for iron exceed the rec- ommended maximum concentration, but most of the samples are well within the recommendations. The Tennessee Region has no known significant bodies of saline ground water. Of about 1,000 analyses (mostly published) of water from wells and springs throughout the region, only 40 indicate water with over 1,000 mg/L total dissolved solids. The high dis- solved solids content is usually associated with stag- nant ground water in poorly developed solution open- ings in flat-lying carbonate rocks. Most of the wells and springs with high dissolved solids are in the Central Basin or Highland Rim, and 17 of the wells tap the Knox Dolomite of central Tennessee. In almost every case they reportedly produce less than 20 gal/min (0.03 Mgal/d). DEVELOPMENT OF THE GROUND-WATER RESOURCES GROUNDWATER USE In 1970, the use of ground water in the Tennessee Region totaled 173 Mgal/d (Murray and Reeves, 1972). This is less than 1 percent of the estimated 22,000 Mgal/d of ground water that is discharged annually to the streams of the Tennessee Region, which is an in- L23 dication of the large amounts available for develop- ment. The ground water that is used amounts to slightly less than 8 percent of the total water use in the Region excluding that used for electric power genera- tion (table 4). However, the percent of the population served by ground water is much larger than the total- use figures would indicate. According to the 1970 census, the population of the Tennessee Region was about 3,300,000. One-third of the people were living in towns or cities with popula- tions of 2,500 or more. The rest lived in small towns or rural areas (Delury, 1973). At present, most of the large towns and cities in the Tennessee Region use surface water. A notable excep- tion is Huntsville, Ala., a city of 138,000, which ob- tained all its water from Big Spring until 1950. Now it draws half its supply from five wells and one spring and the other half from the Tennessee River (Geol. Survey of Alabama, 1975). In that part of the State of Tennessee within the Tennessee River basin, the largest towns supplied entirely with ground water are Tullahoma, population 15,000 and Elizabethton, popu- lation 12,000. Both draw their water from springs (Tennessee Div. Water Resources, written commun., 1976). Many of the smaller towns in the Tennessee Region use ground water. Seventy-nine percent of the small water-distribution systems (serving fewer than 2,500 people) use ground water for at least half their supply. As these towns and others that withdraw water from small streams grow, the present surface source may become inadequate, and ground water could play a major role in supplementing these supplies. The rural population of the Tennessee Region ob- tains most of its water supply from wells and springs. Approximately 50 Mgal/d was used for rural domestic purposes in 1970. In contrast, only a third of water used for livestock and irrigation was ground water (Murray and Reeves, 1972). Industries in the Tennessee Region that have their own source of water used 45 Mgal/d of ground water in 1970. This was only 3 percent of the water used by self-supplied industries other than power-generating plants. In addition to industrial use, ground water supplies many businesses in isolated areas such as service sta- tions and motels. Springs are used for raising fish be- cause of the constant temperature and low turbidity of the ground water. POTENTIAL FOR DEVELOPMENT Ground water is generally overlooked as a water supply in the Tennessee Region because of the abun- dance of surface water. Only a small part of the availa- ble ground-water supply, about 0.8 percent of the aver- age annual recharge, is being used. The advantages in 1L24 EXPLANATION RECOMMENDED MAXIMUM CONCENTRATION 0.3 MG/L SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES IRON pH RECOMMENDED RANGE f T T T T T T T T T I t u T A 100 LARGEST CITIES IN U. S. _. A sip 1.3 I A M105 B _ COASTALPLAIN -- -~ -- -- 8 ===» 28 & | C - CENTRAL BASIN .-. _. _". c slp 1.9 c : : D HIGHLAND RIM -- -- - - D m¥ 2.0 D 1 rommmmmunc@mmem | E CUMBERLAND PLATEAU .. _. _ E -=@ 11 E NOT INCLUDED IN ANALyses A F VALLEY AND RIDGE - -- __ _ Foo mealy 12 F 1 o" muUFRIbGE _ _. _. a p 1.9 s |_ : R 4 j ; 4 3 4 % 4 ) t t u t + + t t t a T T T T T MEDIAN 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 4 5 6 7 8 9 "10 MILLIGRAMS PER LITER units RANGE FLUORIDE SULFATE RECOMMENDED MAXIMUM CONCENTRATION 250 MG/L © m m uo N & 20 60 so loo 120 140 MILLIGRAMS PER LITER 40 160 180 200 CHLORIDE RECOMMENDED MAXIMUM CONCENTRATION 250 mo/L 10 20 - 30 40 _ so - 60 70 MILIGRAMS PER LITER 80 90 100 RECOMMENDED MAXIMUM CONCENTRATION (TENNESSEE REGION) 2.0 mo/l 0.0 1.0 2.0 3.0 4.0 5.0 MILLIGRAMS PER LITER NITRATE RECOMMENDED MAXIMUM CONCENTRATION 10 mo/L 0 m m o Nn & 4 10 12 MILLIGRAMS PER LITER NOTE: NITRATE CONCENTRATION IS INFLUENCED By WELL DEPTH AND CONSTRUCTION, AND MAY NOT BE REPRESENTATIVE OF GROUND WATER TO se EXPECTED 14 16 18 20 rons From Environmental Protect ron Asency, 1975, anp Envrronmentat Stupres Boarp, Nat. Acap. Sct., Nat. Acap. Ene. , 1973. Vacues ror 100 Larcest citiEs From DurFor anp Becker, 1965. Analyses usen are the same AS THOSE IN Froure 18. Figure 19.-Medians and ranges of six chemical constituents in untreated ground water of the Tennessee Region and in the treated, finished water of the 100 largest cities in the United States. Also given are the recommended maximum or minimum values for these constituents in drinking water. TABLE 4.-Water use in the Tennessee Region in 1970 [From Murray and Reeves (1972)] Water withdrawn (in Mgal/d) Use of water Ground water Surface water Public supplies ______________________ 64 240 Rural domestic use .__._._____.__°___° 51 .9 Livestock and irrigation ____________ __ 13 25 Self-supplied industrial use (excluding power generation) ______ 45 1,300 Power generation (thermoelectric) ____ 0 6,100 Power generation (hydroelectric) ______ 0 12,000 cy. 173 19,700 using ground water as a water supply are as follows: (1) its widespread availability, (2) its general dependa- bility, particularly at depth, (3) the minimal amount of treatment required, (4) the relatively low cost of devel- oping a ground-water supply, and (5) its uniform tem- perature and chemical character. Ground water can be used very efficiently for small-scale developments such as water supplies for rural communities, industries, and small towns. In addition, ground water has poten- tial for supplemental and conjunctive use with surface-water supplies. There is growing interest in the feasibility and ad- visability of injecting fresh water into aquifers for storage. The use of underground space for storage of liquids has been practiced on only a limited scale in the region. TENNESSEE REGION, AVAILABILITY In many parts of the Tennessee Region, ground water is available in amounts comparable to those that might be obtained from surface-water impoundments. In contrast to surface-water impoundments, however, the ground-water reservoir stores water with minimal evaporation, insulated to some degree from pollutants and available at diverse points. In addition, ground- water supplies can be developed more quickly and at lower cost compared to the time and cost of creating surface-water storage. DEPENDABILITY It is a common belief that ground-water levels are continually declining in all parts of the country. How- ever, this is true only in places where pumpage of ground water greatly exceeds natural recharge. In the Tennessee Region, ground-water levels show only normal seasonal trends. Water levels usually decline during the growing season (April-November) and rise during the remainder of the year when most ground- water systems are being recharged from precipitation (fig. 20). Shallow dug wells are not dependable sources of supply during periods of prolonged drought as they are generally not dug deep enough to allow for any extreme decline in water level. However, production from drilled wells that penetrate deeper solution cav- ities or water-bearing formations is generally not seri- ously reduced by drought. In areas where ground water is developed, local low- ering of water levels can occur as a result of pumping. However, if pumpage is within the capacity of the aquifer to supply water, the rate of water-level decline will gradually diminish and the water level will stabilize. The response of the water level to various rates of pumping is shown in figure 21. Nowhere in the region has ground-water development caused sig- nificant depression of water levels, although there are instances where inadequate spacing between wells has caused excessive water-level drawdown in a localized area. TREATMENT NEEDS Ground water in the Tennessee Region usually needs less treatment than surface water to make it accept- able for most uses. It can often be used untreated for cooling and process water in industrial plants. Chlori- nation is the basic treatment needed for drinking- water supplies. In some cases aeration is needed to dis- sipate dissolved gases such as hydrogen sulfide or to precipitate dissolved iron. Buffering may be needed, especially for water systems in which low-pH ground water is to be mixed with slightly alkaline surface wa- ter. Ground water usually has low turbidity and does INCLUDING PART OF TENNESSEE AND ADJACENT STATES L25 not generally require filtration to meet turbidity standards for drinking water. Ground water has the additional advantage of being uniform in chemical quality, and would therefore require less monitoring than a surface-water supply. For example, the turbid- ity of surface water is increased by storm runoff, but ground-water turbidity is usually constant, except in shallow carbonate aquifers that have direct connec- tions with land surface, such as sinkholes. As a result of the minimal treatment needed for most ground-water supplies, low-cost treatment facilities can be installed at the well field. This makes it possible to have multiple self-contained units located at points of use of the water rather than a single treatment plant with an extensive distribution system. CosT OF DEVELOPMENT Another potential benefit of ground-water develop- ment is its relatively low cost. Cederstrom (1973) esti- mated that in the North Atlantic States the cost of large supplies of ground water at the wellhead, taking into account the costs of locating and developing a well or well field, ranged from 1.5 to 5 cents per thousand gallons in 1970 depending on the aquifer material. Many of the aquifer materials in this study area are similar to those of the Tennessee Region, ranging from Coastal Plain sediments from which ground water can be obtained most cheaply to carbonate rocks in which ground-water development is most costly. The invest- ment required to construct and operate a ground-water distribution facility is further reduced at places where the water requires little treatment. A study of the alternatives for water supply may reveal an economic incentive to use ground water. An example is a small utilities district in central Hamilton County, Tenn. Owing to the proximity of the surface- water intake for this system to the site of a nuclear powerplant on the Tennessee River, a study of alterna- tive sources of water was made. The results of the in- vestigation indicated that the use of ground water from the Knox Dolomite would lower the cost of providing finished water to the consumers by as much as 50 per- cent, and the utility district is now using wells. TEMPERATURE STABILITY A relatively constant annual temperature, about the same as the average annual air temperature of the area where it occurs, is characteristic of ground water. This characteristic makes it extremely useful for cool- ing and for industrial processes where constant tem- perature is required. In the Tennessee Region ground-water temperatures normally range from 50 to 65°F. A growing use of ground water is as a heat exchange medium for heat pumps. Heating and cooling of build- L26 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES sak CLA A VLL A -L \ M “1 24, 1973 WATER year *~ i 1 IN FEET BELOW SURFACE 1 DEPTH TO WATER 24 28 32 WATER YEAR 36 1974 WATER YEAR FIGURE 20.-Water-level fluctuations in test well M-1, Manchester, Tenn. showing seasonal trends (from Burchett, 1977). ings is much more efficient with a ground-water-to-air rather than air-to-air interface, because of its constant temperature and the high specific heat of water. EFFICIENCY FOR SMALL-SCALE DEVELOPMENT Owing to the scale of ground-water developments, ground water in the Tennessee Region has great poten- tial as a sole water source for small communities and industries that are remote from large reservoirs. In sparsely populated areas and small rural com- munities a multifamily well may be a more efficient water supply than a connecting pipeline to a large cen- tralized water distribution system (Lehr, 1976). Ceder- strom (1973) concluded in his cost analysis of ground- water supplies in North Atlantic States (1973) that "where large water requirements consist of many small to moderate demands at distinctly separate points ground-water supplies may serve admirably from a cost point of view." This approach is being taken in Lincoln County, Tenn. where the U.S. Geological Survey has undertaken a cooperative study with the Lincoln County Public Utilities Commission to inves- tigate the occurrence and availability of ground water as an aid in developing ground-water supplies for small communities throughout the county. For industrial use, the cost of installing a well or developing a well field may compare favorably with the cost of a long pipeline connecting to a municipal sys- tem. Also, the initial cost would be defrayed by the low operation and maintenance cost of the ground-water facility. Where sufficient ground water cannot be ob- tained on site, water can be piped from wells at more favorable sites, as is being contemplated in Chat- tanooga, Tenn. (D. R. Rima, U.S. Geological Survey, oral commun., 1976). SUPPLEMENTAL AND CONJUCTIVE USE In areas where ground water alone is inadequate to supply a needed amount of water, it can play a supple- mental role. There are several situations in which use of ground water would be an attractive alternative source of supply. For example, when a town grows gradually to the point where demand for water occa- sionally exceeds the supply available from ground- water sources, a surface-water impoundment might be needed. However, until the need was severe enough to TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES L27 a d 30 WATER LEVEL 4 0 IN FEET BELOW LAND SURFACE 45 so 1,8 00 1,20 0 so 0 DISCHARGE IN GALLONS PER MINUTE 400 0 MARCH 4 MARCH 5 MARCH 6 MARCH 7 FicuUrE 21.-Pumping rate and water levels in well M-157, Colbert County, Ala. during pumping test (from Harris and others, justify major construction of this nature, ground water, even in relatively small amounts, could supply the peak water demand. In areas where surface water is not available, municipalities are faced with the alter- natives of building a pipeline to connect to another water system or of developing ground-water supplies. In this situation, a thorough investigation of available ground-water resources is warranted because of the high cost of constructing a pipeline. Ground water can also play a role in urban development as the water supply for outlying areas of growth. Conjuctive use of ground water and surface water has received little attention in the Tennessee Region. The following examples illustrate how knowledge of ground water and surface water interaction could in- crease the efficiency with which both are used. In Chat- tanooga, Tenn., there is a plan to modify a water sys- tem that normally uses water from a stream which is subjected to occasional chemical pollution. The stream will be monitored and, when pollution occurs, the sys- tem will draw water from nearby wells until the sur- face water is again usable. Ground water could also be used to augment the low flows of streams, both to sup- ply water systems and to maintain sufficient flow to assimilate waste. When a large surface-water impoundment is made, it could benefit ground-water users by reducing the ground-water level fluctuations in the vicinity of the L L MARCH 8 MARCH 9 MARCH 10 MARCH 11 960 1963). lake. Surface water can be stored without the use of an impoundment where a suitable aquifer is available. Such an aquifer can be recharged with surface water during times of high flow for withdrawal during dry periods. Well fields can also be used to capture subsur- face flow in stream beds by inducing flow from the stream toward the wells. In an alluvial aquifer, of which there are few in the Tennessee Region that are not covered by reservoirs, there is a fluctuation of temperature in the aquifer caused by infiltration of river water. The ground-water temperature lags about 6 months behind the river temperature. It is warmest in winter and coolest in summer. This property could be useful for heating and cooling purposes. UNDERGROUND STORAGE Deep wells are being used in the Tennessee Region for disposal of liquid waste. Two industries, in New Johnsonville, Tenn., and Mt. Pleasant, Tenn., use wells for disposal of chemical waste. At Oak Ridge, Tenn., medium-level liquid radioactive wastes are injected into a shale formation in cement grout so that once they solidify they cannot move from the point of injec- tion (de Laguna, 1968). No aquifer in the Tennessee Region is capable of completely isolating injected liquid substances. There- fore, the possibility exists that injected liquids would L28 displace poor-quality water and migrate upward into aquifers used for sources of water supplies. The use of aquifers for storage of fresh water has not been strongly considered in the region. The inadequacy of information on local ground-water movement currently makes it difficult to evaluate the feasibility and environmental impact of injecting fresh water into a deep aquifer for later withdrawal. LOCATING A GROUND-WATER SUPPLY Ground water is not necessarily available in adequate quantities precisely where it is needed, espe- cially in carbonate rocks. The chances of finding adequate supplies of ground water are greatly in- creased if drilling of production wells is preceded by a hydrologic study of the area to determine the most fa- vorable areas for high-producing wells and by test drilling to verify these areas. In many areas the drill- ing and test pumping of more than one test well might be required before a satisfactory supply can be ob- tained. In his cost analyis of ground-water supplies in the North Atlantic Region, Cederstrom (1973) states that the "average yield" of wells in any one area, as com- monly given in the literature, is no guide to what might be obtained because most wells were constructed to supply water for domestic use and the potential yield of the aquifer was not determined. The "average yield," therefore, represents something a little greater than the average need and is not a measure of the full poten- tial of wells in the rock type being studied. In the Tennessee Region the generally low produc- tion from wells reported by drilling contractors has tended to discourage exploration for large ground- water supplies in almost all areas except the Coastal Plain. For example, in the part of the upper Duck River basin of Tennessee that is on the Highland Rim, 86 percent of wells reported to the Tennessee Division of Water Resources produced 20 gal/min or less. How- ever, of 19 test holes drilled in the same area, only 16 percent produced 20 gal/min or less and 74 percent produced 100 gal/min or more (Burchett, 1977). The reason for this success in test drilling was the use of site-selection criteria based on hydrologic concepts of the occurrence and availability of water in the Fort Payne regolith and bedrock. Site-selection criteria are the practical application of an understanding of the hydrologic system in an area. In some parts of the Tennessee Region the controls on ground-water occurrence are well defined. Two such areas are the Coastal Plain and northern Alabama. Test drilling in the Great Smoky Mountains National Park (McMaster and Hubbard, 1970) has helped to SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES identify criteria for the Blue Ridge. However, in other parts of the region, criteria are either nonexistent or incomplete. The Cumberland Plateau is the only area where very little test drilling for water has been done. Considering the unreliability of the flow of surface streams on the Plateau and the reported difficulty in obtaining even domestic ground-water supplies in some areas, an intensive study of the Plateau's water resources would contribute information needed to fill the biggest gap in knowledge of Tennessee Region's ground-water hydrology. In the Central Basin, Highland Rim, and Valley and Ridge Provinces, ongoing studies by the U.S. Geologi- | cal Survey, including test drilling, are leading to de- velopment of site selection criteria which can greatly improve chances of obtaining large ground-water supplies in carbonate-rock terranes. These criteria are continually being tested and refined. Some of the hydrologic controls in each province of the Tennessee Region have been discussed in the sec- tion on "Occurrence of Ground Water." Site selection criteria vary from one area to another depending on which factors have the greatest influence on ground- water distribution. Use of the criteria does not guaran- tee that large ground-water supplies will be located; it merely increases the chances of drilling successful wells, especially when a site is chosen on the basis of several different criteria. For example, test drilling, test pumping, definition of surface geology and subsur- face structure, mapping of soil thickness, and correla- tion of the withdrawal of ground water with piezo- metric maps prepared during periods of high and low water levels were the basis for locating and developing a well field in a limestone terrane near Huntsville, Ala., capable of producing 14,000,000 gal/d at a frac- tion of the cost of a proposed surface-water supply (Lamoreaux and Powell, 1963). Figure 22 illustrates the kinds of information used in selecting drilling sites in central Tennessee. It should also be noted that in areas of great variability in ground-water occurrence, especially where carbonate rocks are the aquifers, a single test hole is not adequate to determine the maximum amount of ground water available at a par- ticular site. Once a ground-water supply has been located, the characteristics of the hydrologic system should be taken into account in designing the pumping facility. The optimum design is a balance of well yield and operating efficiency against undesirable impacts on the hydrologic system (for example, diminution of stream or spring flow, interference with nearby wells, and de- terioration of water quality as a result of induced re- charge). One of the most frequently neglected princi- TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES 26 7. T Tou? / pr! f U wa NZ D AZ ems. x" L/ AA Is Sevier er. y 57 \<,(, \\ ~// fs I= als Jat (pe Pres" -~ W T M. _ Ao. rh el yig WM uf U f. //'\k/} A a t> A# (A "*= 9 )te <1 $ Tas (”fl \‘\ I“ fe] ar utkorosic 106 camma_ ray 10g ] //}) "I ag tand Surface om * I/ r/ ( i> Overburden Fort Payne Chattanooga Shale LINEAR FEATURES Total Depth ; - -| WELL AND SPRING "Fra RECORDS GICAL DATA SURFACE _ WATER @ Pert rosy SITE SELECTION AND TEST DRILLING FicurE 22.-Types of data used to derive criteria for locating test well sites. L29 L30 ples of well-field design is adequate spacing of wells to avoid interference. For example, in 1960 the town of Waverly, Tenn., was provided with water from two wells less than 500 ft apart, each reportedly producing 300 gal/min. Pumpage from these wells had created a 25 ft deep cone of depression around the wells (Marcher and others, 1964). In 1960 a third well was drilled in the same city-owned lot as the other two municipal wells, but it could not supply sufficient water to be used as a production well. In effect the three wells were functioning as a single well, and withdrawals had ex- ceeded the capacity of the aquifer to supply water to that small area. It is likely that had the well been placed sufficiently far away so as not to be influenced by pumping from the other two, it would have produced an adequate amount of water. The necessary spacing between wells could have been calculated from aquifer test data. Land use can also be affected by ground-water devel- opment. For example, sinkhole development is a possi- ble consequence of ground-water utilization in the parts of the Tennessee Region underlain by carbonate rocks. Where considerable lowering of ground-water levels is predicted, the likelihood of accelerated sink- hole formation should be investigated (Newton and others, 1973). Wells withdraw water that would naturally dis- charge to streams or springs. Pumping wells will inevitably reduce the ground-water supply to these discharge points and may eventually alter the ground-water gradient enough to cause surface water to enter the aquifer. While these effects may not be serious or may even be beneficial, plans for ground- water use would ideally include an evaluation of their impact on both ground water and surface water. This is particularly important when ground water and surface water are to be used conjunctively because ground- water withdrawals affect streamflow at times of low flow when the need for sustained surface-water flow is greatest. DATA NEEDS Accurate assessment of an area's potential for ground-water development is only possible where adequate data exist or can be acquired to define the ground-water system. Much of the basic data required, even for a small-area study, cannot be obtained in a short period, but must be collected on a continuing basis. Geologic data, well records, water-level and water-quality data, and information on aquifer charac- teristics are typical of information required as a foun- dation for hydrogeologic studies. Large-scale general purpose geologic mapping is available nearly everywhere in the Tennessee Region. In addition, mineral exploration has provided subsur- SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES face stratigraphic data in many areas. A large quantity of unpublished well records are available as a result of state laws requiring drillers to submit information for wells they drill. This information soon will exceed 50 wells per county in each state. Some of this information has been computer-listed by state water resources agencies. Federal and State water-resource agencies also keep well records and logs. The greatest deficit in ground-water basic data is in records of water-levels, water-quality, and aquifer tests. Northern Alabama is unusual in the complete- ness of its basic records. For example, as shown by figure 23, the number of network observation wells op- erated by the U.S. Geological Survey in the northern Alabama part of the Tennessee Region is equal to the number in the remainder of the region even though only 17 percent of the region is in Alabama. Outside of Alabama, observation wells are sparse, and they do not give representative information for all the physio- graphic provinces in the region. Strengthening the observation well network before large-scale ground- water development takes place would provide neces- sary information on water levels, on "base line" ground-water quality, and on aquifer behavior under natural stresses such as drought. Records of natural ground-water level fluctuations are particularly important, alone or in conjunction with stream seepage investigations, for identifying re- charge and discharge areas. Identification of sources of contamination is most critical in recharge areas in order to manage ground-water quality. Large ground-water supplies that are subject to minimal water-level variation can often be located in or near ground-water discharge areas. Hence, the identifica- tion of these areas aids in exploration for ground water. Aquifer characteristics, as determined by pumping tests, are not known in most of the Region. Many of the pumping tests that have been made served chiefly to test well performance rather than aquifer characteris- tics. Governmental regulation of public water supplies is increasing and more quantitative information from pumping tests will be required to satisfy the needs an- ticipated under these regulations. The results of these pumping tests would be useful in defining aquifer characteristics on a regional basis. According to an assessment of the availability of ground-water data in the Tennessee Valley (W. M. McMaster, Tennessee Valley Authority, written com- mun., July 1975) the density, utility, and age of pub- lished reports of ground-water information are highly variable. Large-area reconnaissance reports, published between 1932 and 1962, exist for most of the Region. These reports are generally based on rather cursory well inventories and cover large areas. Only the parts L31 TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES 'x1omou [Jom Aaaimg 'g' 94} ut s[[om Jo suo1e90¢T-'¢7 «¥8 s s T= U gems -- saum OS Or 0€ 0¢ ot 0 . 308 NOI934 3J3SSINNFL YYOMILIN 113M AjAin$s 1v51901030 °S ~A wonvae vivo annvadas T Mat XZ [" (Z SNINNY14 1O¥INO3 H3LVM 10 NOISIAIG a V W V T V I Y AUNOHLNY AITIVA 3SS3NN3L ¥ I 9 Y°0 71:9 ¥ V. J e Tag a y" ' f? 7 "Tapo a i meo ution! os i E * Aa Ex 34 A =| at dleuis4en0 pes L32 of the Tennessee Region in northern Alabama, Ken- tucky, and North Carolina are adequately covered by reports on smaller areas that are useful for defining well-site selection criteria. Detailed geohydrologic studies involving test drill- ing and aquifer testing are necessary for an under- standing of ground-water hydrology that would allow the development of criteria for locating feasible areas in which to develop high-producing wells. The results of these studies should be considered in regional, met- ropolitan, and industrial water planning and man- agement programs. The study of hydrologic systems in the Tennessee Region requires considerable time. However, if present sources of supply are placed under a severe stress re- sulting from a major drought or population expansion, the degree to which water management can deal with problems will depend, in part, on how much informa- tion is available and on how well the hydrologic sys- tems of critical areas are understood. Information re- quired to deal with these problems might include such things as where untapped ground-water supplies can be located, which parts of the region have the least ground-water storage, how ground water and surface water can be used conjunctively, and what the effects of utilizing one will be on the other. WATER-RESOURCES MANAGEMENT Effective management of water resources cannot deal with water problems in isolation but as they relate to the hydrologic system as a whole. Stress imposed on one part of a hydrologic system is certain to have re- percussions in other parts of the system. This is true whether the stress is applied to ground water or sur- face water. For example, ground-water withdrawals can reduce the low flow of streams by intercepting ground-water that is naturally discharged to the stream. Impoundment of surface water can increase the quantity of ground water in storage by altering head relationships in an aquifer. Although the surface-water resources in the Tennessee Region are heavily developed, there are no regionwide plans for managment of ground water or of the combined ground- and surface-water resources of the region. The response of a hydrologic system to stress may be experienced at points distant from the place where the stress is applied. For this reason, study and manage- ment of water resources can be accomplished most ef- fectively within hydrologic boundaries rather than political boundaries. Yet many of the organizations, including most government agencies, whose function is to study or manage water resources have programs which operate within political boundaries such as states or counties. To deal with the broad implications of hy- drologic problems, either of two approaches could be SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES considered: close coordination among the organiza- tions, or the involvement of an organization whose jurisdiction includes the entire hydrologic system. In the past, conflicts as to matters such as funding and the means of implementing management policies have arisen in the course of some attempts to coordinate the efforts of several organizations concerned with water. Notable success at managing water resources of a basin-wide scale has been achieved by agencies such as the Delaware River Basin Commission and the Ten- nessee Valley Authority. However, because the Ten- nessee Valley Authority was established primarily to control the Tennessee River, it has not been called upon to direct a major effort toward developing the region's ground-water resources, though it has sup- ported ground-water studies in some parts of the re- gion. The need for a regionwide ground-water manage- ment plan is not yet pressing in the present infancy of ground-water development in the Tennessee Region. In the absence of crisis, a regional ground-water man- agement plan could serve several purposes: (1) to coor- dinate data collection and interpretive studies, (2) to indicate the most efficient and economical use of ground-water resources in the region, (3) to recom- mend measures to maintain the quality of present and potential ground-water supplies, and (4) to provide support for predicting the environmental impact of ground-water diversions by means of digital models which would simulate the conjunctive functioning of both ground-water and surface-water systems. Regard- less of how a ground-water management plan would be administered, its formulation and implementation in conjunction with surface-water management plans should recognize the interdependence of ground water and surface water and provide for utilization of both aspects of the region's water resources to their fullest potential. CONCLUSIONS Ground water is an abundant resource in the Ten- nessee Region. As much as one-fifth to one-fourth of the precipitation that falls in the region enters the ground-water reservoirs each year. A significant part of the 22,000 Mgal/d contributed annually to the ground-water reservoir from precipitation is available for development. In 1970, less than 1 percent of the estimated ground-water recharge, amounting to 173 Mgal/d, was used in the Tennessee Region. This was less than 8 percent of the total quantity of water used in the re- gion. There is, therefore, a large potential for increased development of ground-water supplies. At present, ground water is used chiefly in rural areas and small communities and by industries and TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND ADJACENT STATES commercial establishments beyond the limits of munic- ipal water-supply systems. This use of ground water for small-scale developments is practical and economical because in many parts of the region, ground water can be obtained at or near the points of use, eliminating the need for water impoundments and extensive distribu- tion systems. The cost is further reduced by the need for only minimal treatment facilities for most ground-water developments. Ground water can also be used in larger com- munities to augment existing supplies. Use of ground water to provide for peak demand and as a standby or emergency water source is not uncommon in the Ten- nessee Region, but many more opportunities exist in which ground water could be used along with surface- water supplies to obtain maximum benefit from the water resources. Conjunctive use of ground water and surface water, such as the use of wells to obtain water to maintain a minimum streamflow, has not been given much consideration in the Tennessee Region. This kind of development as well as the use of aquifers for storage of surface water during periods of excess flow require a degree of knowledge of ground-water occurrence and movement which is at present unavail- able in most of the region. The amount of ground water available in the Ten- nessee Region, if all the recharge to an area were re- coverable, would be about 0.5 (Mgal/d)/mi?. The degree to which this quantity is recoverable depends on the hydraulic properties of the aquifers and their areal variability. A narrow strip along the western edge of the region, in the Coastal Plain province, is underlain by unconsolidated sand aquifers from which a large part of the ground-water recharge could be recovered with proper development. Aquifer yields at a given site are more predictable in the Coastal Plain than any- where else in the region, and wells producing 500 to 1,000 gal/min are possible. However, only one-tenth of the Tennessee Region lies in the Coastal Plain. The remainder is underlain by carbonate rocks or fracture noncarbonate rocks. The water-bearing properties of these rocks are variable resulting in high exploration costs in developing ground water. Carbonate rocks with little or no reg- olith, as they occur in the Central Basin and parts of the Valley and Ridge, are the most variable with well yields ranging from less than 1 gal/min to as much as several thousand gal/min within a short distance. An important factor in aquifer productivity in the region is the occurrence of the regolith. A thick reg- olith stores ground water and releases it slowly to openings in the underlying rock. Carbonate aquifers with a thick regolith occur in the Highland Rim and parts of the Valley and Ridge. Because of their great L338 areal extent and relatively uniform distribution of ground water, these areas have the greatest potential for ground water development. Chemical constituents and physical properties of ground water in the Tennessee Region are usually within the limits recommended by the Environmental Protection Agency for drinking water. Water in uncon- solidated aquifers and regolith tends to be soft, low in dissolved solids, and slightly acidic. In carbonate rocks the water is usually hard and somewhat alkaline. Water in noncarbonate rocks is generally soft and in some parts of the region, may contain certain undesir- able amounts of iron and sulfate. Saline water is not known to occur in significant quantities in the region. Because nine-tenths of the Tennessee Region is underlain by rocks that have highly variable water- bearing properties, one of the major problems with de- veloping the ground-water resource is locating open- ings that would supply the quantity of water required. A hydrologic study that includes adequate test drilling and pumping tests would greatly increase the chances of obtaining the quantity of ground water needed. In- formation from such a study would be useful in devel- oping a concept of the hydrologic systems in which ground water occurs, thus permitting the formulation of criteria for selecting well sites in geologically and hydrologically similar areas. Hydrologic studies, in- cluding test drilling, have been undertaken in each section of the region except the Cumberland Plateau. These studies can only be regarded as a beginning but they have already indicated that the ground-water re- source in much of the region is significantly larger than had been anticipated. Coverage by detailed re- ports is lacking in most of the region and the basic data required to make adequate appraisals of the water re- sources are not always available. Some of the data for hydrologic studies, such as geologic maps, well records, and streamflow records are available throughout the region. However, adequate information on ground- water levels, ground-water quality, and aquifer char- acteristics is not available in all parts of the region. Both basic data and interpretation derived from in- tensive studies are essential tools for managing the ground-water resources and predicting the results of developmental activities. The information needed for management cannot be obtained immediately when it is needed; it must be the product of a continuing pro- gram to understand and evaluate the Tennessee Re- gion's water resources. Because ground-water devel- opment has been largely neglected in the region, there is opportunity to establish the data base and manage- ment capability before stress on the region's water re- sources increases to the point that management prob- lems become difficult to solve. L34 At present the management of the region's water resources is unbalanced. Due to the establishment of the Tennessee Valley Authority, surface water is con- trolled to a high degree regionwide; however, there has been no comparable attempt to manage the ground water systematically. Any plans for fully developing the water resources should be based on hydrologic principles which recognize the interdependence of ground water and surface water and should provide for utilization of both aspects of the regions' water re- sources to their fullest potential. REFERENCES Adams, George I., Butts, Charles, Stephenson, L. W., and Cooke, Wythe, 1926, Geology of Alabama: Alabama Geol. Survey Spe- cial Rept. no. 14, 312 p. Betson, Roger P., and McMaster, William M., 1975, Nonpoint source mineral water quality model: Water Pollution Control Federa- tion Jour., v. 47, no. 10, p. 2461-2473. Boswell, E. H., Moore, G. K., MacCary, L. M., and others, 1965, Cretaceous aquifers in the Mississippi embayment, U.S. Geol. Survey Prof. Paper 448-C, 37 p. Burchett, Charles R., 1977, Water resources of the upper Duck River basin, central Tennessee: Tennessee Div. of Water Resources, Water Resources Series no. 12, 103 p. Burchett, Charles R., and Hollyday, E. F., 1974, Tennessee's newest aquifer: Geol. Soc. America Abs. with Programs, v. 6, no. 4, p. 338. Burchett, Charles R., and Moore, Gerald K., 1971, Water resources in the upper Stones River basin: Tennessee Div. of Water Re- sources, Water Resources Series no. 8, 62 p. Bureau of Water Hygiene, 1971, Evaluation of the Tennessee water supply program summary: U.S. Environmental Protection Agency, 23 p. Busby, M. W., and Armentrout, G. W., 1965, Kansas streamflow characteristics, part 6A, base flow data: Kansas Water Re- sources Board, Tech. Rept. no. 6A, 207 p. Butts, Charles, 1933, Geologic map of the Appalachian Valley of Virginia with explanatory text: Virginia Geol. Survey Bull. 42, 56 p. Cederstrom, D. J., 1973, Cost analysis of ground-water supplies in the North Atlantic Region, 1970; U.S. Geol. Survey Water- Supply Paper 2034, 48 p. Cressler, Charles W., 1964, Geology and ground-water resources of Walker County, Georgia: Georgia Geol. Survey Inf. Circ. 29, 15 p. Cushing, E. M., Boswell, E. H., Speer, P. R., Hosman, R. L., and others, 1970, Availability of water in the Mississippi embay- ment: U.S. Geol. Survey Prof. Paper 448-A, 13 p. Davis, R. W., Lambert, T. Wm., and Hansen, Arnold J., Ir., 1973, Subsurface geology and ground-water resources of the Jackson Purchase region, Kentucky: U.S. Geol. Survey Water-Supply Paper 1987, 66 p. [1974]. DeBuchananne, G. D., and Richardson, R. M., 1956, Ground-water resources of East Tennessee: Tennessee Div. Geology Bull. 58, 393 p. de Laguna, Wallace, 1968, Radioactive waste disposal by hydraulic fracturing [abs.]: Ground Water, v. 6, no. 6, p. 47. Delury, George E., editor, 1973, The world almanac: New York, Newspaper Enterprise Assoc., 1040 p. Dodson, Chester L., and Harris, Wiley F., 1963, Geology and SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES Geol. Survey Bull. 76, 90 p. Dufor, Charles N., and Becker, Edith, 1964, Public water supplies of the 100 largest cities in the United States, 1962: U.S. Geol. Sur- vey Water-Supply Paper 1812, 364 p. Environmental Protection Agency, 1975, Interim primary drinking water standards: Federal Register, v. 40, no. 51, Part II, March 14, 1975. Feth, J. H., 1965, Preliminary map of the conterminous United States showing depth to and quality of shallowest ground water containing more than 1,000 parts per million dissolved solids: U.S. Geol. Survey Hydrol. Inv. Atlas HA-199. Geological Survey of Alabama, 1975, Environmental geology and hydrology Huntsville and Madison County, Alabama: Alabama Geol. Survey Atlas Ser. 8, 118 p. Grantham, Rodney G., and Stokes, William R., 1976, Ground-water quality data for Georgia: U.S. Geol. Survey open-file report, 216 p. Harris, H. B., Moore, G. K., and West, L. R., 1963, Geology and ground-water resources of Colbert Co., Alabama: Alabama Geol. Survey County Rept. 10, 71 p. Harris, Wiley F., Jr., and McMaster, W. M., 1965, Geology and ground-water resources of Lawrence County, Alabama: Ala- bama Geol. Survey Bull. 78, 70 p. Hunt, Charles B., 1967, Physiography of the United States: San Francisco and London, W. H. Freeman and Company, 480 p. Joiner, Thomas J., and Scarbrough, Leon W., 1969, Hydrology of limestone terranes, geophysical investigations: Alabama Geol. Survey Bull. 94, Part D, 43 p. LeForge, Lawrence, Cooke, Wythe, Keith, Arthur, and Campbell, Marius R., 1925, Physical geography of Georgia: Georgia Geol. Survey Bull. 42, 189 p. Lamoreaux, P. E., and Powell, W. J., 1963, Stratigraphic and struc- tural guides to the development of water wells and well fields in a limestone terrane: Alabama Geol. Survey Rept. Ser. 6, 13 p. LeGrand, H. E., 1967, Ground water of the Piedmont and Blue Ridge provinces in the Southeastern States: U.S. Geol. Survey Cire. 538, 11 p. Lehr, Jay H., 1976, Let's promote individual and cluster wells in rural water systems: Water Well Jour., March 1976. McMaster, W. M., 1963, Geology and ground-water resources of the Athens area, Alabama: Alabama Geol. Survey Bull. 71, 45 p. McMaster, W. M., and Harris, W. F., Jr., 1963, General geology and ground-water resources of Limestone County, Alabama, a re- connaissance: Alabama Geol. Survey County Rept. 11, 43 p. McMaster, W. M., and Hubbard, E. F., 1970, Water Resources of the Great Smoky Mountains National Park, Tennessee and North Carolina: U.S. Geol. Survey Hydrol. Inv. Atlas HA-420. Malmberg, G. T., and Downing, H. T., 1957, Geology and ground- water resources of Madison County, Alabama: Alabama Geol. Survey County Rept. 3, 225 p. Marcher, M. V., Bingham, R. H., and Lounsbury, R. E., 1964, Ground-water geology of the Dickson, Lawrenceburg, and Waverly areas in the western Highland Rim, Tennessee: U.S. Geol. Survey Water-Supply Paper 1764, 50 p. Meinzer, O. E., 1923, Occurrence of ground water in the United States, with a discussion of principles: U.S. Geol. Survey Water-Supply Paper 489, 321 p. Meinzer, O. E., and Stearns, N. D., 1929, A study of ground water in the Pomperaug Basin, Connecticut, with special reference to in- take and discharge: U.S. Geol. Survey Water-Supply Paper 597-B, p. 73-146. Miller, Robert A., 1974, The geologic history of Tennessee: Tennessee Div. Geol. Bull. 74, 63 p. Moore, G. K., 1973, Hydraulics of sheetlike solution cavities: Ground ground-water resources of Morgan County, Alabama: Alabama Water, v. 11, no. 4, July-August 1973. TENNESSEE REGION, INCLUDING PART OF TENNESSEE AND Aoore, Gerald K., Burchett, Charles R., and Bingham, Roy H., 1969, Limestone hydrology in the upper Stones River basin, central Tennessee: Tennessee Div. Water Resources, 58 p. Moore, Gerald K., and Wilson, John M., 1972, Water resources of the Center Hill Lake region, Tennessee: Tennessee Div. Water Re- sources, Water Resources Series no. 9, 77 p. Murray, C. Richard, and Reeves, E. Bodette, 1972, Estimated use of water in the United States in 1970: U.S. Geol. Survey Circ. 676. National Academy of Science-National Academy of Engineering, 1973, Water quality criteria 1972: U.S. Environmental Protec- tion Agency Ecol. Research Ser., EPA-R3-033, 594 p. Newcome, Roy, Jr., and Callahan, J. A., 1964, Water for industry in the Corinth area, Mississippi: Mississippi Board of Water Com- missioners Bull. 64-2, 24 p. Newcome, Roy, Jr., and Smith, Ollie, Jr., 1958, Ground-water re- sources of the Cumberland Plateau in Tennessee: Tennessee Div. Water Resources, 72 p. 1962, Geology and ground-water resources of the Knox Dolo- mite in middle Tennessee: Tennessee Div. Water Resources, Water Resources Series no. 4, 43 p. Newton, J. G., Copeland, C. W., and Scarbrough, L. W., 1973, Sink- hole problem along proposed route of interstate highway 459 near Greenwood, Alabama: Alabama Geol. Survey Circ. 83, 63 p. Peace, Richard R., Jr., 1964, Geology and ground-water resources of the Russelville area, Alabama: Alabama Geol. Survey Bull. 77, 83 p. Peace, Richard R., Jr., and Link, Donald R., 1971, Geology and ground-water resources of northwestern North Carolina: North Carolina Dept. of Water and Air Resources, Div. of Ground Wa- ter, Ground-Water Bull. 19, 135 p. Rasmussen, W. C., and Andreasen, G. E., 1957, A hydrologic budget ADJACENT STATES L835 of the Beaverdam Creek basin, Maryland: U.S. Geol. Survey open-file report, 211 p. Rima, D. R., Moran, Mary S., and Woods, Jean E., 1978, Ground- water supplies in the Murfreesboro area, Tennessee: U.S. Geol. Survey Water Resources Inv. 77-86, 73 p. Sanford, T. H., Jr., 1964, Ground-water conditions in the Huntsville area, Alabama, Jan. 1960 thru June 1961; Alabama Geol. Sur- vey Circ. 24, 46 p. 1966, Ground water in Marshall County, Alabama, a recon- naissance: Alabama Geol. Survey Bull. 85, 66 p. Searcy, James K., 1959, Flow-duration curves: U.S. Geol. Survey Water-Supply Paper 1542-A, 33 p. Sun, P-C. P., Criner, J. H., and Poole, J. L., 1963, Large springs of East Tennessee: U.S. Geol. Survey Water-Supply Paper 1755, 52 p. Swingle, George D., 1959, Geology, mineral resources, and ground water of the Cleveland area, Tennessee: Tennessee Div. Geol. Bull. 61, 125 p. Tennessee Dept. of Public Health, Division of Water Quality Control, 1975, Water quality management plan for the Lower Tennessee River basin, 220 p. Tennessee Valley Authority, 1973, Division of Water Control Plan- ning, annual report for fiscal year 1973, 49 p. 1975, Precipitation in Tennessee River basin, annual 1975: Tennessee Valley Auth., Div. of Water Management, Data Serv- ices Branch, Rept. no. O-243-A75. Wells, Francis G., 1933, Ground-water resources of western Tennes- see: U.S. Geol. Survey Water-Supply Paper 656, 319 p. Wilson, John M., 1965, Ground-water resources and geology of Cum- berland County, Tennessee: Tennessee Div. Water Resources, 56 p. if; Pe v.-.&!1 343 -"} 7 DAYS Summary Appraisals of the Nation's Ground-Water Resources- Hawaii Region C, t L) GEOLOGICAL SURV EY PyFESSIONAL P A PER 8 1 3-M / 159° 160° 22 w a_ 2 NHHAU Quay/M :\ : «Honolul MO ulu Ziggxlxl 21° Kaunakakai . 21° € amily LANAI D MAUIk aKAHOOLAWE 20° N 20° (J m\L HAW AII > Kilauea ** 19° < 19° 160° 159° 158° 157° 156° 156° U.S. pEepostt~n=_y BPR L9 4/8 'So1eig portup atp Uf suofSay saomnosay-191e 4 107 founo3 saomosay-1oje A portup ay} 4q aso are umoys satrepunog '$20in082y do;» suonnpyy ay; fo sipsipiddy 10deq feuorssgjorg AsaAing 'g' 'sattog ou 01 xaput oryde1s0an es W lpg, T of saoinosay 1912M yo B asin NOLLVNYVTIX4 e" «¢ * ¢ IA ¥4) | HyYMVH NVIGIIIVD IVMAVH suoypugisap N o a Eig sodeq | feuotssajord I ( ut stopdeyo se 'ssard ut 10 IddISSISSIWN W YImOT va a storSay ATNAQ-OLLNVTLY HLAOS ' 10NYHD Old A VINYOAITVD \ gN n SANXYT LVIYD (“mo—EC ~J dNVTONI MAN dmz. LA $2422 ANIVH-UI¥-SIUNOS Summary Appraisals of the Nation's Ground-Water Resources- Hawaii Region By K. J. TAKASAKI EEOLOCGCICAEL SURVEY PROEESSION AL PAPER 8 I 3-M Problems and opportunities related to the development and management of the ground-water resources in the region UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1978 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, Secretary GEOLOGICAL SURVEY W.A. Radlinski, Acting Director Library of Congress catalog-card No. 78-600035 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock Number 024-001-03061-6 CONTENTS Page Page ADELPACt .... ln dito M1 | Water use-Continued Introducti0n 1 Future water-use patterns-Continued Noteworthy ground-water development events _____----- 1 industrial. .....___..-_.«-._. ede. M13 Regional setWNg c 2 Surface water versus ground water _____________________ 18 Geologic framework _______________________________-_---- 2 | Ground-water 13 Hydrographic areas ___________________________--------- 5 | Optimizing ground-water development ____________-_--_-_------- 28 Rainfall uence 5 Basal ground water ___--- E LALA 28 Evapotrangpiration 5 Dike-impounded water __--- a pecs - oona anche os 23 Surface runoff and infiltration ________-_-_-_--------------- 5 Surface activities to maximize recharge of ground water __ 24 Distribution of rainfall | 9 | Ground-water problems 24 WAtET USC 9 Problems arising from inadequate information _-_-_------ 24 Water use in 1975 9 Technologital prObIeMms _______________---_------------~- 25 Future water-use patterns _________________------------- 9 Institutional problems ___________________________------- 26 Municipal 9 | 26 Agricultural 9 | Selected references 27 ILLUSTRATIONS Page FicurE 1. Map of Hawaiian otal thee lone lt nn eca tent sant M3 2. Diagrammatic cross section showing geologic structure of an idealized Hawaiian volcanic dome ______________------ 4 3. Map of Hawaiian Islands showing hydrographic areas representing major drainage basing __________.__.______-..- 6 4. Map of the Hawaiian Islands showing lines of equal annual average rainfall in inches ____-__-_-_-__------------------ 7 &. Sketches showing orographic effects on 8. 6. Map of Hawaiian Islands showing distribution of rainfall 10 7. Graph showing distribution of rainfall into components of evapotranspiration, direct runoff, and deep infiltration in leeward Koolau coleen roel coupe tase see coe tos cee saan cose krn ea oen" 11 8. Diagrammatic cross section showing occurrence and development of ground water in an idealized Hawaiian volcanic Nome. [r. ... :o tA. pic testo oe lolol aie ease renee s n r rance ne 14 9-15. Maps of islands showing ground-water recharge, 1975 draft, and approximate outlines of ground-water reservoirs. 0. Island Of HAWAII anas- ~~ 15 10. Island of Maui N. ls:. if.....iurig.to ..o. deel -- t one ~ 16 11. Islands of Molokai and Langi os 17 12. Teland Of Oghu ondes s eee. See oanade - ass 18 13. Island Of KAudi dae -to -Q 14. Bland Of KahOOIAWB 20 15. Iland of Nilhau 21 TABLES Page TABLE 1. Distribution of rainfall to evapotranspiration, runoff, and ground-water Fecharge M12 2 Mater use In Hawaii Region- A. c 13 8. Drincipal pround-water reservolrg _. 22 HI IV CONTENTS FACTORS FOR CONVERTING ENGLISH UNITS TO INTERNATIONAL SYSTEM (SD UNITS The following factors may be used to convert the English units given herein to the International System of Units (SD) Multiply English units By & To obtain SI units ACTE bae. 4047 ire square meter (m*) square foot (112) _c nn LIE (O:. I2Y enne. een cor square meter (m*) square inch (in€} c_. 0 _ 0006452 square meter (m?) square mile (mit) .._ el l 2-500 - cc.... .l. cereaws. square kilometer (km?) fOOF (Pb) 3. 02 nne en aloes toe f C_ it meter (m) 2; 03000 Sete Loli n gian. Abd Leer ne tena. millimeter (mm) mile (mi) _ OGG _; (2000. 10609 -_ . 0 kilometer (km) yard (yd) cum. {La ol P144 - cei call cadet.. meter (m) ncre-foof (acre-ft) coc. OHG Lw l. 1298 tlc cubic meter (m?) cubic foot _L ___ ALi cc DD nf - 02882 -_. cubic meter (m?) gallon ___. ___: if fo mel TBD __.. eac tones. liter (L) million gallons (108 gal or Mgal) ......__:.__.___________G__.__ cubic meters (m*) cubic foot per second-day I(ft¥syd] ._____._____________________ 2447 _._. Asl lille... cubic meter (m?) ____________________________ 002447 _________________ cubic hectometer (hm?) cubic foot per second 02832 0. cubic meter per second (m*/s) ____________________________________ . liter per second (L/s) gallon per minute (gal/min) 06809. __.-_-._.__.leclle. liter per second (L/s) million gallons per day (10®gal/d) or (Mgal/d) __________________ cubic meter per second (m*/s) foot per mile (fi/imi) ssc meter per kilometer (m/km) cubic foot per second per square mile [(ft9/s)/mi2]________________ 01093; cubic meter per second per square kilometer [(m*/s)/km?] foot per day (fUd) .l 0 ___ c_ __ 0.3048 - _- lll lec meter per day (m/d) gallon per minute per foot [(gal/min)/ft] ________________________ r OT, ner eo liter per second per meter [(L/s)/m] foot squared per day (ft*/d) ________ 0920... ..... luce meter squared per day (m*/d) SUMMARY APPRAISALS OF THE NATIONS GROUND-WATER RESOURCES- HAWAII REGION By K. J. TakasaAKI ABSTRACT The water resources of the Hawaii Region, taken as a whole, are far greater than foreseeable future demands on them, but this is not so for the individual islands. Each and every island is independent with respect to water supply, and the occurrence and availability of water vary widely from island to island. The ground-water resources offer better prospects for supplying additional water needs in the future than the surface-water re- sources. Most of the surface supplies that are easy to develop have been fully utilized where needed, and conduits and reservoirs neces- sary to develop new or additional supplies would generally require large and perhaps prohibitive outlays of capital. In 1975, ground water supplied 46 percent, and surface water 54 percent of the water needs but, in the years ahead, these percentages will likely be re- versed as more ground-water development takes place. Total water use, in 1975, averaged about 1,775 million gallons per day, of which about 810 million gallons per day was ground water. The total water use is divided into public supply, 11 percent; self-supplied industrial use, 23 percent; and agricultural, 66 percent. Rainfall is the principal source of ground-water recharge. Local mean annual rainfall ranges from less than 20 inches to more than 300 inches, with the annual average rainfall on the large islands exposed to the trade winds being slightly more than 73 inches and that on the small islands situated in the rain shadow of the larger islands being less than 26 inches. Ground-water recharge has been estimated at about 2,400 billion gallons per year (6.5 billion gallons per day) or roughly 30 percent of the rainfall. Most fresh ground water in the region is stored below sea level in porous lava flows, much of it as basal-water lenses floating on saline ground water, as distinguished from dike-impounded water in the interior of the islands. The basal-water lens is maintained by re- charge, which, if reduced, leads to thinning of the lens and sub- sequent encroachment of seawater. Seawater is the biggest pollutant of freshwater, and many of the ground-water problems are, in some way, associated with the encroachment of saline water induced by development. The major problem areas include the entire island of Oahu, south Kohala-Kona coast on the island of Hawaii, Lahaina District in Maui, and the Koloa and Kekaha-Mana areas in Kauai. INTRODUCTION The purpose of this report is to provide pertinent ground-water information and to relate this informa- tion to the potential role of ground water in meeting future water needs in the Hawaii Region. The report also focuses on some problems related to the hydrology of ground water in overall water supply and manage- ment, and on some of the deficiencies in information and understanding that hinder the optimum develop- ment of the ground-water resources. Ground water in the Hawaii Region is a large and valuable resource. Despite the large overall supply, ground water is not available in some areas, and much of it, especially that which is of suitable quality for domestic use, has to be imported by pipeline from dis- tant areas. In 1975, only about 20 percent of the ap- proximately 810 million gallons per day (Mgal/d) of ground water developed was used for public supplies. As a result of development, the quality of the ground water has deteriorated at some places, but water of less than potable quality can be tolerated in uses such as irrigation of sugarcane and cooling. Most recharge to ground water occurs in the wet interior mountains, generally upgradient from lower- lying developed areas where wastes and subsequent waste disposals are more likely to occur. This favorable situation is gradually changing for the worse as land developments encroach into the principal recharge areas. Some deterioration of the ground water is to be expected, the degree of which will depend greatly on how much deterioration is allowed by policies and deci- sions related to land use, land development, and waste-disposal practices. In most cases, the prevention of pollution by eliminating the pollutant at the source would be a more effective course to follow than at- tempting detection and surveillance of the pollutant after it reaches the ground-water reservoir. NOTEWORTHY GROUND-WATER DEVELOPMENT EVENTS In the early years of development in the Hawaiian Islands, water supply was generally not a major prob- lem, except in the Honolulu area. Land and surface water were abundant at places within each of the larger islands, and development was concentrated in these areas. The early Hawaiians settled near peren- nial streams and springs and diverted water for their highly developed agriculture. Later, sugarcane was grown in areas where rainfall was sufficient or where M1 M2 water could be easily diverted from perennial streams. In the water-scarce areas, the land remained largely undeveloped and unsettled. Domestic water needed for these early developments was not, as a rule, developed separately but was taken from the available irrigation supply. The water, thus obtained, was generally of good quality or was consid- ered so because most of it came from sources in the wet interior areas and was usually diverted from ditches and streams upgradient from the developed areas. Some ground water, other than from springs, was developed by the early Hawaiians from shallow wells dug at or near the beach. Most of the water thus devel- oped was brackish. By the middle 1850's, the population of Honolulu had grown to nearly 12,000. Whaling in the Pacific had reached its peak in activity, and Honolulu had become a principal port of supply. Thus, the city of Honolulu, unlike the rest of the Region, was even then experienc- ing a water-supply problem. Water was piped from dis- tant surface-water sources but the supply could barely meet the demands of the population and of the ships. The availability of freshwater had, in fact, become a severely limiting factor to the growth of Honolulu (Honolulu Board of Water Supply, 1963). In 1879, a well tapping a basal ground-water aquifer under sufficient artesian head to flow freely was drilled in the arid land west of Pearl Harbor in Oahu. Many wells followed, first in Oahu and a little later in the other islands. The presence of a cheap and dependable ground-water supply in many of the dry leeward areas had immediate impact on the Region's development. By 1890, water from artesian wells provided a large share of the water needs for Honolulu, thereby remov- ing the city's principal constraint to growth. By 1920, the cultivation of sugarcane had shifted from the gen- erally wet windward areas to the drier leeward areas, and lands heretofore deemed useless became very much in demand. Sugarcane cultivation had become the principal economic base for the Region. By 1975, more than 1,000 wells had been drilled or dug, most of them to develop water for the irrigation of sugarcane. Rapid and indiscriminate drilling of wells followed the first successful well and continued virtually un- abated for nearly 50 years, especially in southern Oahu. During this time, water from wells near the coast in southern Oahu, once of domestic quality, be- came brackish. Artesian head, once as much as 43 feet above sea level, steadily declined to about 25 feet above sea level. Concern over this decline led to legislation and the establishment of an authority to curb waste and to manage the seemingly deteriorating artesian water supply in Honolulu. Competition for the ground-water supply in Oahu SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES did not become a serious problem until the Second World War, when the first significant transfer of sugarcane lands to other uses occurred. During the Second World War, large areas in the western part of Honolulu, abutting the Pearl Harbor area, were turned over to the military for their use. The military use necessitated the drilling of new wells to provide the domestic-quality water required. After the war urbani- zation increasingly replaced sugarcane lands, and the ensuing competition for water by the various users led to unplanned development in many areas. Problems related to water quality, rights, and management be- came apparent at this time and still persist. The advent of statehood for Hawaii, in 1959, led to increased tourism and hastened the growth of the population of southern Oahu. More agricultural land was urbanized. Meanwhile, considerations of possible impact on the environment of further water and land development added to the complexity of problems. Except for the intensive growth in sugarcane culti- vation, the development and population growth in the other islands did not parallel that in Oahu in the years following the end of the Second World War. Sugarcane cultivation increased somewhat during this period, but owing to many technological advances, fewer workers were needed and the population on all the other islands declined. It was not until sometime after the coming of statehood and the growth of tourism in Oahu that re- sort areas and resort-residential complexes began to expand in the other islands. Tourism now is the fastest growing segment of the economy in all the islands. The ever-increasing demand for water, especially for domestic-quality ground water, in the heretofore un- developed dry leeward areas that are favored for resort development, is a problem that needs to be solved if the tourist industry is to continue to grow. REGIONAL SETTING GEOLOGIC FRAMEWORK The Hawaiian Archipelago, which makes up the Hawaii Region, is a group of shoals, reefs, and islands trending northwest to southeast more than 1,500 miles across the Pacific Ocean (fig. 1). The Hawaiian Islands, which lie at the southeastern end of the archipelago, constitute more than 99 percent of the region's total land area. Only these islands are considered in the ap- praisal of the region's ground-water resources. The Hawaiian Islands are the tops of shield vol- canoes rising from the ocean floor, the oldest is Kauai in the northwest part, and the youngest, the island of Hawaii in the southeast part. Each of the islands con- sists of one to five volcanic domes, the bulk of which is composed of thousands of basaltic lava flows. The lavas issued in repeated outpourings from narrow zones of M3 HAWAII REGION 'wesap ayloed oy} ut spue|st oy} Jo uor;ea0| ay} smoys gosut [jews ayy 'o8efedtyory uerremep ay 008 o AM 42 co _.|r_|llr1[l_.|nrl s311w OOr oor 0 IIVMVH $ <3 % if! b ° ae (cfd , omejooyey L.... ~ Sii A o cdi R *(Afuo uo1l3jejuasaud _m_gopowa oj) uoljisod uadoud ut uou afeas 03 umeup jou jo dey :arop |Legurea 40 abeqjuapuad si aunfl4 = OP Rep aad jo suol[[iw ut = ¥ abuey33au aajem-punoug Jj0 abejuapsuad sit aunfl4 Jj ouny uoljeuaridsueujodea3 NOI LWYNYTdX3 SS0°t1=M OEt*Z=¥ IV X0710MW D028" 2=4 £08 ° L=¥ nVHHN DISTRIBUTION OF RAINFALL IN INCHES 240 220 200 180 160 140 120 100 80 60 40 20 -60 -100 HAWAII REGION 5 £ I | | | | | | | 20 40 /’ 60 80 100 120 140 160 180 200 - 220 240 4,7 ANNUAL RAINFALL IN INCHES V Z A&A << q/Evapotranspirofion exceeds rainfall where water & , how: A& levels are shallow or where heavily irrigated. &/ / Ficur® 7.-Distribution of rainfall as related to rainfall range in leeward Koolau Range. M11 M12 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES TaBLE 1.-Distribution of rainfall, in million gallons per day, to evapotranspiration, runoff, and ground-water recharge 1975 ground-water quantities gggm-c Distribution of rainfall (approximate) area rep- resenting major Total Evapo- Percent- Percent- Ground- Percent- Withdrawn drainage rain- trans- age of age of water age of from Island basin fall piration rainfall Runoff rainfall recharge rainfall _ Exported Imported wells Large islands exposed to trade winds Hawait.-___-__ I 1,430 695 49 430 30 305 21 5 1 5 II 7,335 1,730 24 2,510 34 3,095 42 0 0 18 III 2,340 - '1,705 18 235 10 400 17 0 0 8 IV 1,790 ~+1,2665 71 180 10 345 19 0 0 3 V 1,160 1745 64 180 16 285 20 + 5 1 Totals (rounded) 14,100 6,200 44 3,500 25 4,300 31 6 6 35 Maui -_-._._:.. I 340 125 37 145 41 70 21 0 0 60 II 370 130 35 175 47 65 18 20 0 26 III 685 215 31 325 47 145 21 0 180 170 IV 925 145 16 310 34 470 51 160 0 7 V 500 145 29 270 54 85 17 0 0 1 Totals 2,820 760 27 1,225 43 835 30 180 180 264 Molokai ______ I 230 30 13 150 65 50 22 5 0 <1 II 175 125 71 15 9 35 20 1 1 <1 *III, IV 160 150 94 5 3 5 3 0 5 €] Totals 565 305 54 170 30 90 16 6 6 1 Oahu-'........ I 270 90 33 85 31 95 35 3 1 8 II 255 115 45 100 39 40 16 25 3 42 III 235 120 51 30 13 85 36 0 22 56 IV 425 105 25 70 16 250 59 24 25 260 V 98 77 79 15 15 6 6 0 2 6 VI 520 210 40 130 25 180 35 1 0 48 Totals (rounded) 1,800 715 40 430 24 655 36 53 53 420 Kauat: .-_____- I 910 160 18 $705 77 445 5 18 0 2 II 710 219 31 $455 64 136 5 11 18 2 III 280 75 27 195 70 1410 4 25 11 12 IV 414 89 21 3300 72 426 6 55 25 2 V 116 50 43 58 50 8 7 0 55 32 Totals (rounded) 2,430 595 24 1,715 70 120 5 109 109 50 Kauai: ._.__._. Adjusted totals 2,430 595 24 51,455 60 380 16 109 109 Large islands __ Totals (rounded) 21,700 8,520 39 6,820 ad 6,340 30 354 354 770 Small islands in rain-shadow of large islands Kahoolawe ____ Total 40 28 70 8 20 4 10 0 0 0 Lanal ...... Total 187 124 66 40 22 23 12 0 0 2 NWithau ..__:____ Total 88 63 72 20 23 5 5 0 0 0 Small islands __ Totals (rounded) 315 215 68 70 22 30 10 0 0 2 Region ......_. Grand totals (rounded) 22,000 8,730 40 6,800 31 6,460 29 357 357 772 Probably too high owing to infrequency of storms which provide much of rainfall total. *Hydrographic areas combined owing to low rainfall density in each area. *Includes large quantity of ground-water inflow, see footnote 5. *Too low; ground water included with runoff. "Reduced by 15 percent and added to ground water. HAWAII REGION TABLE 2.-Water use in Hawaii Region, in million gallons per day [From water-supply study-element report, Hawaii Water Resources Regional Study (1975)] Water use Source Self- Public _ supplied _ A; gri- Surface Ground supplies industrial cultural Total Island water _ water 15 117 31 163 134 29 13 85 467 565 305 260 0 2 2.4 2 1 161 130 321 612 152 460 72 352 431 371 60 0.3 0 2.2 2.5 0 2 0 0 0 0 0 0 0 0 0 0 0 0 197 404 1,175 1,776 964 812 of the soil, climatic parameters (rainfall, etc.), the length of fallow period, and the availability and quality of water. Available information is generally not adequate for planning future irrigation needs owing to large-scale shifts from furrow to drip irrigation. INDUSTRIAL At present most self-supplied industrial water is used as cooling water for air-conditioning and for electric power generation. Potential industries that may require large quantities of water include the mining of manganese or other ores from the sea floor, the extraction of minerals from seawater, or the utilization of geothermal energy resources. SURFACE WATER VERSUS GROUND WATER The major source of usable surface water is the fair-weather or base flow of streams. Much of this water is transported from wet to dry areas in extensive ditch systems which were constructed early in this cen- tury. More such water could be developed but only at high cost because new ditches or enlargements of the present ditches would be needed. Other constraints that could restrict future development and transfer of water include existing water rights, environmental considerations, and State and Federal statutory regu- lations. Generally, there are few constraints other than cost in the onsite development of ground water, except where land development is extensive such as in Oahu and possibly in the Lahaina area in Maui. Areas of high water demand in coastal areas generally coincide with areas underlain by poor-quality basal ground wa- ter. In many areas, availability of good-quality ground water would necessitate development 3 to 4 miles farther inland to an altitude of 1,000 feet or higher. A well at these altitudes would have to be drilled to below M13 sea level and the water pumped up from near sea level to the land surface. In areas where ground-water and surface-water sources are closely integrated and where the with- drawal of ground water is quickly reflected in reduced surface-water flow, the need to maintain streamflow may restrict ground-water development. Knowledge of the hydraulic characteristics of the aquifers and the nature of the stream-aquifer interconnection are needed in order to estimate safe limits for development in these areas. Compliance with the Federal Safe Drinking Water Act (PL 93-529, 1974) will have pronounced effect on managerial and planning decisions, especially in areas where both ground-water and surface-water sources are being considered as municipal supplies. The high costs of treating surface-water supplies must be weighed against the cost of developing new ground- water supplies. GROUND-WATER RESERVOIRS Most fresh ground water is stored near and below sea level to depths ranging to 1,000 feet or more below sea level. The principal fresh ground-water reservoirs con- sist of thin-bedded basaltic lava flows. These reservoirs contain interconnected water bodies that are im- pounded by dikes in the interior of the islands or are in dynamic equilibrium with the underlying saline ground water in the outer rims of the islands. Ground water in these settings is referred to, respectively, as dike-impounded water and basal water. Other water bodies, small in comparison, are perched above and iso- lated from these interconnected water bodies and are called perched water. The term high-level water is often used to describe both dike-impounded and perched water, or a combination of them when they occur at high altitudes. A diagrammatic cross section showing occurrence and development of ground water in an idealized Hawaiian volcanic dome is shown in figure 8. The prin- cipal ground-water reservoirs in each of the Hawaiian Islands are outlined in figures 9 to 15. Estimates of ground-water recharge and ground-water draft in each of the hydrographic areas are also shown in figures 9 to 15 and table 1. A brief description of the principal re- servoirs and their potential for additional development is given by hydrographic areas in table 3. Ground-water development is generally most favor- able in areas directly downslope from mountain areas of high rainfall and becomes less favorable with in- creasing distance away from these downslope areas. SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES M14 (F961 'xo; woj;) awurop otueajoa uettemep pozt[eapt ue ut puno13 Jo pue aoualimna0-'g p1ap|o» ssiw 0; umpup uolj9ag ainis papouy Jang) DaG y301009 ui 1aj0m bu1dojaaap 41g [lam wnianj|o uo payoiad smo}; ui 1a;0M buiads mfo|\: a C ayig sayip 4q papunodun 12a40m ass e payosad 1a40M aj0is pap o.1aun ea .... p SWAMVVWV‘”... f m_ 1080] buiads josog =. lam ad4}-inom yso uo pag usy s tare. s Jauuny 1a4o0m-payd1ag ('€161 pue staeq wou; poytpopy) 'sutseq ageurep 1ofew Sunuas M15 OZ Ot 0 s37IW OZ OL 0 wajem punou6b Jajem punoub uo Bburijreol; punoub [feseq 5.23 wajrem punoub eseq buiXfaaro yse ao uo payauad uajgem punouy sayip Aq papunodut aajgem punouy WII HAWAI REGION ulseq /». abeureap buijuasaudau eaur w__~ wajinbe jo {ji iLqeauuad y6iy pue abury3au J0 asneoaag qse09 Jrau YS1IY]9RIq wajem punouy *[[eJjulrea quosqe 0j avp;juns pur| jo Aji3edeo y6iy 03 buimo area abueyoou ybLH slam ALfddns fedroutlad Kep wad 'q3jeap aajem-punouy Kep «aad suo|{eb 'abueyaau aajzem-punday NOI L WNY 1d X3 . 00.894 < e C -ardo1 seare 4q stfom 4fddns jedtouud pue 'geip 'o8reyoo1 107em-puno18 Jo aut[ino agewutxoudde Sutmoys tremep Jo JO depy-'6 sunoly 0 061 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES M16 (CZF6T 'preuoprep; pue sureagg wou paytpopyt) 'sutseq ageurep 1ofew Sut -quosqidai seare 4q stom redtour1d pue (yep $161 'oBreyoo1 'stoa1oso1 Jo aut[ino agewitxoudde Sutmoys mnepy ;o puejst yo depy-'q1 suno14 urseq abeureup burqjuasaudau eaur UT£QMLm0LanAmc Kep aad 'uanjau Jajzem-uolje6 lui; °C Slam Lddns fedioutag e Kep aad suo1l Leb Jajem punoub feseq uo! [LW '3jeap aajrem-punouy { Kep aad suo [eb [Lw 'abueyoau aajem-punoug 4 NOILVNVT1dX3 Jajem punoub aut Les uo burjrol; uaazem punoub [eseg f 3 suakel yse s J0 [10s uo payauad uazem punoug 02 VN 3 XM V W : II soyip {q papunodut punougy NOI LWNYTd X3 sH#313WO1IM OL sg 9 p z o you- pon S371IW 8 9 b C 0 ,00,991 ,0L ,0¢ , O£ ,0v,991 M17 warem punou6b Jajem punoub aur fes uo burjeol;, punoub [eseg _ yse uo Los uo payauad punouy II wajem punou6b wo; algegins saunjond;s Aq uiefaapun rauy HAWAII REGION ('€161 ut 'erep poyustfqndun '4'g wos :reue7 '; p61 'pjeuopoepy pue sureagg wor; poytpout 'texojopy) 'sutseq ageure1p 1o0[ -ew Surjuasarda1 seare oryde1Soip4y Aq s[Jom Addns redtourrd puse 'qggeip g)61 'of 's1toaA1oso1 1oyem-puno13 Sutmoys reue7 pue texofopy jo jo depy-'11 urseq abeureap uofeu .., burqjuasaudau raur uwcamgmoanIAm_~ mo[jweauys se oj pajunoooe si punoub qsowu asnepag ages abueypau moj e stam Afddns fedioul4q e Kep aad uo! LLW '3je1p { Kep aad [eb uolL|LLW $& __OS NOLLWNYT4X3 sO. sH3J1IWOTIM OL 8 9 tf C O llrlflrlLllll Ss31IW 8 9 v C 0 100 Jayjo Jo sayLp Aq papunodur punouy S NOI LWYNYT1d X3 .\‘. "" wmvivH 05,99 L Va Va nV TVX - olC \TV XV XV N NV X 101 olC LSL ,O1L,4St SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES M18 -quasouda1 seaxe 4q strom pue 'yep ¢)§@I 'sitoaraso1 197em-punod8 Jo outf;no agewtxoudde Sutmoys nyeqp Jo puetst ;o depyy-7 THO su3iawm0oilX s 9 p z o plm sa1im9 _ p _ : = 0 Jazem punoub6 I aulfes uo Burjeol} N Jazjem punoub [esegq [] suafel yse uo LLos uo payouad punouy II uo sayip «q papunodwut uaazem punoug 5 wofeu burjuasaudau raur uwzamgmogvxzufl 'sutseq 1ofew Sut ulseq abpeureup Ist sara mopfeys wou; uorjeguld ybiy 03 buimo area aburysau moj P Rpoq aazem plargouoas {q eaur aoqur} [Lugaqd 01 pojdaAip S1 abueyoau jo qued queaijiubls Rep aad suo[[e6 'uanjou aajzem-uolje6biuut se uoj pajunoooe S1 punoub qsowu area abueyoau moj Siloam Lfddns fedroutag Rep aad suo[feb aajgem-punoug Rep aad suo1[e5b 'abaeypooau aazem-punouy NOI LYNVT1dX3 I) A o «®

au MO] stfam ALfddns fedroulag Kep aad suo1 feb uo! | LW '3jeup Jajem-punouy Kep aad suo1 eb uol[ Lw 'abueyoau uajem-punouy NOLLWNY14X3 # 1371VNVY ® . cee non nen een aan 10. cer nein nei c 0+: er Poor ______ Mauna Loa lavas serena 22. POOP ______ do :-. Mauna Kea lavas iran nr Oon cee eden cre enous . (POOP to Taif MautI........_. Dike impounded West Maui lavas Excellent domestic quality. Fair Pasal . =_ - __ 40: -t eer ls Poor quality near coast. Poor MautIL._______ Dike impounded ___ ______ do... .1...... AeA az.. Excellent domestic quality. Fair Pasal. | _ & - ~ _ _____ " renin - als aAa Excellent quality water. Fair to good Maut HI ______ do Haleakala lavas Large recharge from return irrigation Fair water, quality improves to the east. Maui IV _-__..._ Perched Posterosional Haleakala lavas _ Excellent quality water. Good basal . " a". - do- .. Fagrdto good quality in thin basal-water Fair to good odies. MautV ...-..... _-_... do .--....c.l.l.s... Haleakala lavas Good quality in east part and poor in Poor to fair west part. - Molokai I ______ Dike impounded East Molokai Volcanic Series Excellent quality water. Good Molokai II ______ basal '. ~ a ~ y. _ _s _ 0 ws o er nace Quality and flow improve toward east. Fair Molokai III, IV __ ______ do...... East and West Molokai Volcanic Series . " ... spall all n lo _ _ (0+ aren = rec eae nearer been bene e b ecewan Poor to fair Oahu I.......:... Dike impounded Koolau Volcanic Series Development will reduce streamflow. Fair basal -!. _-_. %:: -__ do aE. less Separated into two parts by dike zone. Fair to good. Oahull ._...._. Dike impounded ___ ______ doss.:s cn Development will reduce streamflow. Fair Oahu III _...._-_ basal" . _. 'm= do. --- yen... .c. Heavily tapped in coastal plain areas. Poor Oahu IV ._.... High level - _ . . -___._ . Schofield water body; development at Good expense of reduced flow to Pearl Harbor and Waialua areas. basal .' ., .' ._ __ ___.. 0}: X cise Thick lens, heavily tapped. Poor ______ do ______________ Waianae Volcanic Series Heavily pumped for irrigation, poor Poor general quality. ______ Coralline Heavily pumped for irrigation and recharged Poor to fair by return irrigation water. Oahu y .._..__: Dike impounded Waianae Volcanic Series Excellent quality in limited supply. Poor to fair basal: _ .... .s. . a O-: ass. noc n ences. Brackish near coast. Poor Oahu VI_..__... High level Koolau Volcanic Series Schofield water body, development at Fair to good expense of reduced flow to Pearl Harbor and Waialua areas. Basal .. 'f' ° ___A , do.. Deep valleys restrict lateral flow. Fair ______ do ______________ Waianae Volcanic Series Thick lens. Fair Kauatl _.._.__: ______ do Napali Formation Largei little-tapped source, excellent Good quality. Perched Koloa Volcanic Series Largtlal, untapped source, yield poorly to Poor to fair wells. Kauai I ._._____ Basal Napali Formation Thick basal reservoirs, excellent quality. Fair ______ do ______________ Koloa Volcanic Series Large, little-tapped source, yield Poor to fair generally low to wells. Perched - . ' . . __.___ 0: esac Mostly in small reservoirs, excellent Fair quality. Kauai II ..____ Basal Napali Formation High water levels owing to impoundment Fair to good by Koloa Volcanic Series. Poor to fair ______ do ______________ Koloa Volcanic Series Brackish near coast. Perched : . ___? .. O-. seee easels Little-tapped source in eastern part. Fair Kauai IV ._..__ Basal Makaweli Formation High water levels. Fair do ._: _o. Napali Formation Significant recharge by return irrigation Poor water. Kahoolawe ______ ______ do Mostly brackish. Poor Lanat .._... Dike or fault impounded Lanai Volcanic Series Large storage, can be utilized for peaking. Fair Nithau.......... Basal Mostly brackish. Poor area in Maui are such areas. In the high volcanic dome of Haleakala on Maui, for instance, more than two- thirds of the rain falls on the windward side. About 160 Mgal/d of water developed in this area is conveyed by ditches to irrigate sugarcane in the lower eastern slopes, but much more goes unused to the sea owing to the lack of adequate conduits. Water for domestic use in east Maui is currently HAWAII REGION transported from limited ground-water sources in west Maui and plans are to increase the amount of water transported for this purpose. From the standpoint of long-term optimum use of the ground-water resource in west Maui, development of the large but unused water resources available in the windward slopes of east Maui should be considered for use in east Maui. OPTIMIZING GROUND-WATER DEVELOPMENT The ground-water resources of the region, taken as a whole, are far greater than foreseeable future demands of the region, but this is not true for single basins and single islands. Each island is a separate entity and stands alone with respect to utilization of its ground- water resources. Within each island, ground water may be obtained from the three types of reservoirs de- scribed in the preceding section. Optimal development will occur, however, only by taking into account the relationships of discharge and recharge that may exist locally among the various ground-water bodies. BASAL GROUND WATER It is commonly not recognized that basal ground water is a highly fugitive, as well as renewable, re- source, and that the ocean, to which it escapes, repre- sents a sink of no recovery and no return. Many exist- ing well fields utilize ground water inefficiently by con- centrating the wells in small areas, thus causing large local drawdowns while permitting large amounts of ground water to escape unused to the sea in the inter- vening areas. The wells are concentrated spatially, partly for efficiency of distribution, but in part this has been done because of mistaken belief that they tap an underground river. Pumping may also be unnecessar- ily intermittent rather than steady in the belief that the longer the hiatus in pumping, the greater the buildup in storage. Ideally, optimum development of basal ground water would occur by constantly pumping a line of wells normal to the flow paths, which are generally perpen- dicular to the coastline. Assuming that reliable esti- mates of ground-water recharge and hydraulic conduc- tivity were obtained, the well spacing and pumping rates could be optimized. An optimum development plan is generally a compromise based on a theoretical scheme for maximum development, aquifer-test re- - sults, and economics. Land ownership and availability, however, may be the most important considerations in areas of high land cost and development. j Problems in implementing an optimum plan are few if the existing ground-water draft is small. The prob- lems, however, increase manyfold where the draft is large and the existing development is inefficient as the result of poorly constructed wells, improperly spaced M23 wells, and sustained localized overdraft. The remedy for existing problem areas may involve high costs in the abandonment of old wells and the drilling of new wells, in land acquisition for new well sites, and in the curtailment of ground-water withdrawals at some places. These costs must be weighed against the long- term benefits of optimum development. At places where basal water is confined by sedimen- tary caprock and is under artesian pressure, optimum development may require reduction of the artesian heads and pumping at constant rates in order to minimize leakage through the caprock. This operating plan will result in permanent reduction of storage in the basal freshwater lens and possible intrusion of saline water into some existing wells. The costs of these consequences must be carefully considered. In order that reliable estimates of the consequences can be made and the alternatives properly considered, there is a need for development of hydrologic models of the aquifers. These models can be used to predict re- sults of implementation or nonimplementation of cer- tain operation plans. The degree of success derived from the use of such models would depend entirely, however, on the amount and reliability of the hydro- logic data used in constructing the models. DIKE-IMPOUNDED WATER A dike-impounded reservoir accumulates rainfall, stores it temporarily, and steadily leaks it to abutting basal reservoirs or to streams cutting into the reser- voir. Development of dike-impounded reservoirs is at- tractive because hydraulic heads are high and the re- servoirs are isolated from saline water. One major con- sequence, not fully understood or acknowledged, is that withdrawal of water from such a reservoir reduces its leakage to abutting basal reservoirs by the quantity developed. The most perplexing consequence, however, is the loss of hydraulic head in the reservoir and the tremendous waste of water from storage during con- struction of water-development tunnels below the top of the reservoir. During the tunneling period, which lasts for many months, all of the storage above the invert of the tunnel is depleted and flow from the tun- nel is reduced to some steady rate. The reduction of storage caused by construction of eight tunnels in Oahu has been estimated at 25,800 Mgal (Takasaki and others, 1969), equivalent to the total ground-water withdrawal in Oahu for about 60 days. The combined steady-state flow of these eight tunnels is about 28 Mgal/d, which implies that it would require at least 920 days for natural recharge to restore the depleted storage. The Honolulu Board of Water Supply recently drilled an inclined well to tap dike-impounded water in Oahu. M24 This technique permitted the development of dike- impounded water without the large initial and uncon- trollable waste of stored water common to development by tunneling. A significant part of the reduction in storage by tun- neling could be restored by constructing bulkheads at the controlling dikes. Bulkheads have been installed in several tunnels, but only the one in a tunnel in Waihee Valley is effective in restoring water to its pretunnel level. Bulkheads in other tunnels in Oahu were not constructed at dikes that originally stored the most water; hence, they are only partly effective in the res- toration of storage. The locations of dikes that control the most water can best be determined at the time of tunneling. If tunneling information is not available and storage is depleted, gain in flow between dikes, determined by measurements, should indicate the best sites for bulkheads. Bulkheads are most effective where single dikes control large quantities of water and where the contrast in permeability between lava flows and dikes is great. In a dike complex, the per- meability contrast is too small or the dikes are too numerous for bulkheads to be very effective. The storage above the tunnel in Waihee Valley has been estimated at 2,200 Mgal and capability of manip- ulating this amount of storage is of tremendous value in water-supply management. The remaining tunnels are operating at steady-state flow and storage is virtually nil. The restoration of significant amounts of storage above these tunnels would be invaluable. Op- timum use of these tunnels would be to store water during the wet winter months for use during the dry summer months at rates much larger than the peren- nial steady-state flow of 28 Mgal/d. This scheme would eliminate excessive pumping of basal-water wells dur- ing the high-demand summer months, thus allowing pumping to be held at some constant rate throughout the year. The reverse is the current practice, involving near-constant withdrawal from dike-impounded reser- voirs and manipulated light-winter to heavy-summer withdrawal from basal reservoirs. SURFACE ACTIVITIES TO MAXIMIZE RECHARGE OF GROUND WATER Owing to the general lack of surface-reservoir sites, surface activities designed to induce the recharge of ground water must be such that large surface storage is not essential. Possibilities are: 1. Construction of multipurpose flood control struc- tures designed to maximize or to induce recharge. 2. Lowering near-surface ground-water levels by de- velopment to reduce evapotranspiration and in- duce recharge. 3. Agricultural and forest-management practices con- SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES ducive to recharge and the enhancement of water quality. 4. Fog-drip inducement by artificial means for the purposes of recharge. 5. Artificial recharge of excess surface and irrigation water or sewage effluent by ponding and deep in- jection. 6. Land development conducive to preservation of water quality and increased recharge. 7. Maximum use and storage of water at high al- titudes instead of dropping the water quickly to lower altitudes as is commonly practiced where abutting property owners discharge water indi- vidually. 8. Use of inexpensive or excess power generated by burning bagasse at sugar mills for pumping un- used irrigation water for storage in reservoirs or for subsurface injection at high levels. GROUND-WATER PROBLEMS Water-supply and other water-assessment problems are rarely regional problems, but are, for the most part, single-island problems. Problems related to technol- ogy, water rights, use, pollution, and management of ground water, however, are generally regional in scope. The ground-water problems common to the Region can be considered in three interrelated groups: (1) problems of inadequate information, (2) technological problems, and (3) institutional problems. PROBLEMS ARISING FROM INADEQUATE INFORMATION Inadequate information of the geologic framework, meterology, and streamflow often presents serious problems in interpretation of ground-water regimes. Inadequate geologic information leads to difficulty in describing the ground-water reservoirs, the flow within them, and the outflow from them. Inadequate meteorological and streamflow information leads to problems in determining quantitatively the recharge to and the discharge from the ground-water reservoirs. Major ground-water problems arise from lack of in- formation on the following aspects of the geologic framework: 1. The water-bearing properties of lava flows below sea level. Most of the Region's basal ground water, and the saline ground water that underlies it, occur in these rocks. Lava flows extruded below sea level are generally of low permeability; how- ever, the aquifers that now occur below sea level in the Region are often highly permeable subaerial flows which were subsequently submerged. The extent of the submergence is not known nor is the thickness of the permeable lava flows below sea HAWAI level. This leads to difficulty in evaluating amounts of storage and the deep circulation pat- tern of the fresh and saline ground water. 2. The extent of water-bearing properties of near- shore sedimentary and volcanic rocks. The ensu- ing problems are those related to the discharge of polluted ground water at or near the shore result- ing from the injection of wastes into these rocks. 3. The structure, extent, and density of occurrence of dikes in the dike-intruded zones. The occurrence and movement of dike-impounded waters could be better described if this information were available, and related problems pertaining to water rights and priorities and to environmental impacts that would result from development could be handled more intelligently. 4. The geology and hydrology of rift-zone areas of ac- tive or recently active volcanoes. Rift zones occur on the flanks of volcanoes in places where magma is extruded from long fissures. The rift zones be- come areas of dike intrusion as the magmas cool in the fissures. Hot waters of possible interest for geo- thermal development occur in these areas. A major concern is the determination of the sustained water yield and the potential energy yield as a basis for evaluating the economic potential of the geothermal waters. Problems in evaluating ground-water recharge and discharge arise from inadequacies in the following meteorological and streamflow information: 1. The rainfall distribution in the wet interior areas where most recharge occurs. 2. The relation between actual and potential evapo- transpiration in the moderately dry to moderately wet areas, especially where the potential evapo- transpiration has been estimated as being equal to pan evaporation. 3. The contribution of fog drip to ground-water re- charge. Preliminary studies in the region suggest that the contribution of fog drip to recharge may be significant either as direct infiltration or as a replacement for water lost by evaporation and transpiration. 4. The relation between basin rainfall and basin runoff in the wet interior areas where drainage basins are small and where the ground-water di- vide often differs significantly from the topo- graphic divide. TECHNOLOGICAL PROBLEMS The major technical problems related to ground- water hydrology in the Region are those pertaining to basal ground water. Some of the more important are as follows: REGION M25 1. The relation of basal ground-water levels and their natural and induced fluctuations to the storage, recharge, discharge, and development of the basal lens. More importantly, how to evaluate antici- pated changes in rates of natural recharge and dis- charge at places where water levels are declining. 2. The general inadequacy of equations available for analyzing pumping-test data from partially pene- trating wells, and also the application of the con- cept of transmissivity, which includes aquifer thickness, for determining hydraulic conductivity. The inadequacy is compounded for aquifers con- sisting of thin lenses, where pumping, even at moderate rates, causes rapid upconing of the salt- water interface. * 3. The determination of the relation between horizon- tal and vertical hydraulic conductivities in basal- tic lava-flow aquifers. This relation often deter- mines the yield and, consequently, the optimum mode of development, especially from thin basal lenses where upconing of the underlying saline ground water is always a threat. 4. The evaluation, in space and time, of recharge to and discharge from storage in the part of the basal lens below sea level with change in water level above sea level. 5. The evaluation of tidal responses in basal lenses, especially in thin lenses, and the application of this information to the understanding of the me- chanics of flow and the mixing process in the lenses, and in determining hydraulic conductivity. This may be the only applicable hydrologic analyt- ical method in many areas in the Region where the major stress on the basal aquifer is not caused by pumping but by tidal fluctuations. 6. The analysis, in water-budget studies, of the large intermittent amounts of recharge to thin basal lenses as potentially recoverable increments of stored ground water. Intermittent recharge due to intense storm precipitation usually disperses quickly in thin basal lenses, particularly where these lenses occur in highly permeable recent lava flows. 7. Many of the problems mentioned earlier are related to the potential for degradation of water quality which, although not restricted to basal ground- water bodies, is most evident in these water bodies because of their widespread occurrence. Water quality is a critical factor which often limits the use and development of ground water. Over- development results in saltwater upconing or en- croachment, and man's activities may produce other contaminants which may degrade present M26 supplies. There is a need to identify areas where overdevelopment has occurred, where the ac- tivities of man may endanger present and future supplies, and where geologic and hydrologic condi- tions might permit the surface or subsurface dis- posal of wastes without undesirable environmen- tal consequences. INSTITUTIONAL PROBLEMS Owing to recent interest in the quality of the envi- ronment and the need to comply with government reg- ulations on water quality and waste disposal, the roles of government, business, and the public in ground- water management have been significantly altered. Government's managerial role includes research, con- trol, conservation, development, monitoring, and plan- ning. The relations of these public functions at various levels of the Federal, State, and County governments warrant review because of these recent changes. The jurisdictional lines between different levels of govern- ment and between agencies at the same level remain extremely complex. Problems in water management related to priority and exchange or transfer of water may require gov- ernment intervention and assistance for resolution so that water development can be better integrated and coordinated with land-use plans and comprehensive planning in general. The allocation and management of water has been left largely to private agreements through user associ- ations, which generally include land estates, agricul- tural interests, municipal suppliers, and the military. Problems are beginning to arise as water supplies lo- cally become more scarce and as land developments affect recharge rates and quality of the water. To cope with these problems, the State, through the Ground Water Use Statutes (Chapter 177, Hawaii Revised Statutes, as amended, was reenacted by Act 122, of the 1961 Session Laws of Hawaii), is authorized to desig- nate ground-water areas for regulation, protection, and control if conditions are found to exist that will en- danger the quality or quantity of ground water in such areas. Technical problems will likely arise, however, in trying to establish that such conditions do exist. Management problems are likely to arise because of changes in the hydrology caused by: 1. Intensive development of ground water, which would significantly reduce perennial flow in nearby streams. 2. Massive shifts to drip irrigation from furrow irri- gation. 3. Extensive changes in land use and irrigation prac- tice that would occur in the "Hanapepe" State Su- preme Court decision (1973, McBryde Sugar Co., SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES Ltd. v. Almer F. Robinson, et al.) is upheld and the transfer of surface water from one watershed to another is curtailed. The Hanapepe decision estab- lishes that all surface-water rights belong to the State; appurtenant rights, as use rights, remain in existence; all other rights to the use of water are based on the riparian doctrine; and water rights are not transferable from one watershed to another. Clarification is still needed as to whether or not the state can transfer water from one watershed to another. 4. The 1973 State Supreme Court decision which de- clared the State owner of surplus water in Hawaii's rivers and streams (Hanapepe decision) was overturned as unconstitutional on October 26, 1977 by the Federal District Court in Honolulu (1977, Selwyn A. Robinson, et al. v. George K. Ariyoshi, et al.). The State may appeal the recent Federal Court ruling to the U.S. Supreme Court. The State did not seek title to the water rights in the initial suit. The State government has developed a carrying- capacity concept for use as a growth management tool and framework for decisionmaking (1976). The carry- ing capacity of a region can be defined as the capacity of the region's environmental and resource systems to support a given or planned level of economic activity. The methodology has been formalized and integrated for a prototype study of the water supply of Oahu. Safe yields representing reasonable developable supplies, assuming present technology and economics, need to be translated into carrying capacities which can be ex- trapolated into the future. A major problem in the ef- fective implementation of such a concept lies in the general lack of information needed to adequately eval- uate the water resources. CONCLUSIONS The ground-water resources of the Hawaii Region offer the best prospects for meeting future water needs. In comparison to the surface-water resources, they ap- pear to be less costly to develop and more dependable when developed. Development of ground water may also be more compatible with environmental quality considerations, existing water rights, and statutory regulations. About 810 Mgal/d is currently withdrawn from the ground-water resources. This quantity represents about 4 percent of the estimated rainfall. In spite of this small percentage, many problems in the quantity and quality of the ground-water supply exist. Under natural conditions, these problems exist owing to the extremely uneven distribution of rainfall, size and shape of the islands, and the varying ability of the HAWAI REGION rocks to absorb and transport the water. The heavy local development needed to meet increasing demands and the deterioration of the ground-water supply owing to withdrawal, land development, and waste disposal contribute most to the existing problems. Owing to the large spatial variation in the predomi- nant trade-wind rainfall and the subsequent marked inverse relation in water availability between the areas of supply and areas of demand, most water- supply problems have been solved by the transport of water. With a significant increase in the number of conduits for water transport, many of the future supply problems can probably be best resolved in this way. The import of water from the wet to the dry areas, especially for irrigation, is a most desirable solution because it has the effect of widening the rainfall re- charge area. In many water-deficient areas, where water is un- available for import or is too costly, supply problems would have to be resolved by measures that would re- duce demand or enable the use of treated sewage ef- fluent or brackish water for some purposes. For exam- ple, in coastal areas where additional development of good-quality ground water is not feasible, brackish ground water might be substituted in irrigation and industrial uses for the domestic-quality water now being used for these purposes. Water-supply problems that now exist in areas where sugarcane is heavily irrigated, such as in the Lahaina District in Maui and the Kekaha-Mana and Koloa areas in Kauai, could be relieved somewhat by similar types of water-exchange practices. For the island of Oahu, where the demand for domestic-quality water has a high priority and where most easily obtainable water has already been devel- oped, actions needed to resolve supply problems are more restrictive and specific. There has been a tendency for large users of water to ignore the development of small sources of water, the primary reason being the difficulty or infeasibility of assimilating small scattered supplies in the existing distribution systems. However, in view of the pressing need, many excellent small sources available in wind- ward Oahu, the Waianae area, and the southeastern end of the island should be seriously considered for development. There is a general lack of manmade storage to meet summer peaking needs, and the prospects of sig- nificantly increasing the storage are nil. Lacking adequate storage, summer peaking needs are now met by increased pumping. This method is undesirable in that extreme pumping stresses are imposed in the basal-water bodies which are the principal sources of supply. Some of the summer peaking needs could be M27 met by restoring dike-impounded storage in the Koolau Mountains which was lost by development. This additional storage and the use of water currently stored at high levels in the Schofield water body could be utilized principally for high-demand summer periods. This scheme would make it possible to reduce some of the extremely heavy summer pumping from the basal aquifers. Some increase in the domestic water supply could be accomplished on Oahu by the exchange of poor quality water, such as brackish water or treated sewage ef- fluent for domestic-quality water now used for irriga- tion. Large amounts of nonpotable water are avail- able from treated sewage or from water in coastal sediments. SELECTED REFERENCES Adams, W. M., Peterson, F. L., Surendra, P. M., Lepley, L. 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Survey open-file report, WRI 1-74, 5 sheets. 1976, Elements needed in design of a ground-water-quality monitoring network in the Hawaiian Islands: U.S. Geol. Survey Water-Supply Paper 2041, 23 p. Takasaki, K. J., Hirashima, G. T., and Lubke, E. R., 1969, Water resources of windward Oahu, Hawaii: U.S. Geol. Survey Water- Supply Paper 1894, 119 p. Takasaki, K. J., and Valenciano, Santos, 1969, Water in the Kahuku area, Oahu, Hawaii: U.S. Geol. Survey Water-Supply Paper 1874, 59 p. Takasaki, K. J., and Yamanaga, George, 1970, Preliminary report on the water resources of northeast Maui: Hawaii Div. Water and Land Devel. Cire. C60, 41 p. Taliaferro, W. J., 1959, Rainfall of the Hawaiian Islands: Hawaii Water Authority, Hawaii Div. Water and Land Devel. Rept. R12, 394 p. Tenorio, P. A., Young, R. H. F., Burbank, N. C., and Lau, L. S., 1970, Identification of irrigation return water in the sub-surface, Phase III, Kahuku, Oahu, and Kahului and Lahaina, Maui: Water Resources Research Center, Univ. Hawaii, Honolulu, Tech. Rept. No. 44, 55 p. R. M. Towill Corp., 1971, Sewerage master plan for the County of Maui, State of Hawaii: 254 p. University of Hawaii, 1974, Water for Hawaii, Summary proceedings-Environmental conferences on the public under- standing of science for Hawaii: Honolulu, Hawaii, 110 p. Visher, F. N., and Mink, J. F., 1964, Ground-water resources in southern Oahu, Hawaii: U.S. Geol. Survey Water-Supply Paper 1778, 133 p. Watson, L. J., 1963, The valuation of water in Hawaii: Appraisal and valuation manual of the American Society of Appraisers, 1962- 1963. 1964, Development of ground water in Hawaii: Am. Soc. Civil Engineers Proc., Jour. Hydraulics Div., Paper 4144, 17 p. Wentworth, C. K., 1951, Geology and ground-water resources of the Honolulu-Pearl Harbor area, Oahu, Hawaii: Board of Water Supply, City and County of Honolulu, 111 p. Williams, J. A., and Soroos, R. L., 1973, Evaluation of methods of pumping test analyses for application to Hawaiian aquifers: Water Resources Research Center, Univ. Hawaii, Honolulu, Tech. Rept. No. 70, 159 p. Yamanaga, George, and Huxel, C. J., 1969, Preliminary report on the water resources of the Lahaina District, Maui: Hawaii Div. Water and Land Devel. Cire. C51, 47 p. 1970, Preliminary report on the water resources of the Wailuku area, Maui: Hawaii Div. Water and Land Devel. Circ. C61, 43 p. ® U.S. GOVERNMENT PRINTING OFFICE: 1978 - 789-107/79 9-II SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES, LOWER MISSISSIPPI REGION 'soreig pojtup af UJ suofSay 10; flouno3 saoinosay-1912M portup ay Aq asou} aie umouys satrepunog S$5011082} 12; suoupy ay} fo sipnsiniddy dinuwung 13deq reuotssajorg Aaaing feat8of0a9 'g' 'satiog a} 03 oryde180an «o » W s asl 42 0 A ¥4 E53,“ IVMVH | E€1g 10deq peuotssajoig # 6 i 's'o's'n ut ssard ut 10 are . N U suonvusisap dojdoyo aipoiput s401127 IddISSISSIW 0 * N xamot va a suor8ay dTNADOILNVTLY HLAOS ' I0NYVXHD saoinosay 19]2M vo B U Odv¥0103 NOLLYVNVTIX4 UIU-ALIHM-SYSNYVNXHUY 4 VINYOAITVD I i A Nom \\ SaXYT L¥aud anvToNa 3ng {wom fi k,“ 92 a“ * \ U wk / ¥ uR SB gNIV W \ ANIVU-UIU-SIUNOS Summary Appraisals of the Nation's Ground-Water Resources- Lower Mississippl Region By J. E. TERRY, R. L. HOSMAN, and C. T. BRYANT EFEOLOGICAL SURVEY PROFESSION AL P A PE R 813-N An emphasis on the region's large available supply of ground water and on the water-resource management practices directed toward deriving the maximum benefit from this large water supply o cha 4AUZENT TINT AEEICE WASHINGTON: 1970 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, Secretary GEOLOGICAL SURVEY H. William Menard, Director Terry, J. E. Summary appraisals of the nation's ground-water resources, lower Mississippi region. (Geological Survey Professional Paper 81 3-N) Bibliography: p.39-41. 1. Water, Underground-Gulf coast (United States) 2. Water, Underground-Mississippi Valley. I. Hosman, R. L., joint author. II. Bryant, C. T., joint author. III. Title. IV. Series: United States. Geological Survey. Professional Paper 813-N GB1I017.T47 553'.79°0976 - 78-31887 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock Number 024-001-03146-9 CONTENTS Page Page ___ deca anes N1 | How can we obtain maximum benefit from ground water? __ N29 Introduction.. 1 Expand information base, and use it __________--------- 29 Location and size of area _.__..__......_._L.__--.___-«s 1 Use modern technology 31 'The new land i Aquifer modeling 31. Purpose and SCOpe 3 Artificial recharge: 32 The water-resources scene | 3 Blending Of WAbeF 82 Hydrologic boundaries 7 Control and use of saltwater _____________________- 33 Surface Water ...... .._. ck ~ 7 RecyCling" ...- PLL_ ile 34 Ground water :... al. 7 Geothermal GNETREY | 34 Why is ground water of importance in the Lower Mississippi Plan properly 34 Region?... -- 11 | What are the possible consequences of increased ground-water Widespread accessibility ..______..__.________.__.__._____._ 11 USCT .- ._ _IL... news 35 Large amount available | ..._.________.__J...__.__LG--..- 16 Hydraulic changes 36 Acceptable for many uses .....__._._.__._.____L________-- 19 Water-quality changes ________________________.________ 36 Why are we not getting maximum benefit from ground water? _ 26 Aquifier-framework changes _______________________--- 36 Inadequate consideration ._..._:_.....__.__._:i_L.___<.___- 26 | In summary-Is the-outlook optimistic? - _____________------ 38 Improper development ....._..________________.___._.___ 26 | Selected references - 39 Fractional use of available supply ________________------ 29 ILLUSTRATIONS Page FRONTSPIECE. Geographic index to the series, U.S. Geological Survey Professional Paper 813. FicurE_. 1. Location map, Lower Mississippi RegIQN | N2 2. Map showing normal annual precipitation and temperature | 4 3. Map showing average annual potential evapotranspiration 5 4" Map showing. mean anfliual Tunoff- on sens usa ns 6 5 GEOIORIC MAD ___.... :... _. _. 2.02. on nl 2 on oo no eae +n mn mb a a ane il nle te m in Nei in atms cung n man mn in mn in he o ie ie i i a oe mn gn on oe n one ara e n ul e aoe mon fie 8 6. Generalized geologit .... __ _.. ._.. . 22 o. 2 oo uno ooo eee enne o on c nl Loool mee mine m a an ioe mn o o Toce n me m in oren be oe m in o e m o te s oe a t m ine 9 7. Map showing base of freshwater in Coastal Plain AGUifers 10 8. Map showing freshwater aquifers underlying the Lower Mississippi Region 12 9. Map showing the availability of fresh ground water 13 10. Map showing the ranges in well yields throughout the region | 14 11. Diagrams showing ground water-surface water | 17 12. Map showing the locations of stream-gaging stations where the 7-day, 10-year low flow has been defined ________---- 18 13. Diagrams showing how a well located near a stream can utilize induced recharge from the stream - ___________----- 20 14. Diagrams showing relationship of recharge to aquifer Utiliz@ti0OM 21 15. Map showing dissolved-solids concentration of available ground water 22 16. Map showing prevalent chemical types of water in streams at low flOw = 23 17. Map showing prevalent dissolved-solids concentration of water in streams at low flow = __________________________---- 24 18. Map showing areas covered in ground-water-related reports = 26 19. Diagrams showing well construction without adequate research of available information = _____________-__-___------- 27 20. Diagrams depicting contamination of freshwater aquifers by abandoned, deep test holes ______________________------ 27 21. Sketch showing how to locate a new well in the vicinity of existing wells = 28 22. Map showing areas of severe water-level declines 30 23. Graph showing estimated ground-water use 31 24. Sketch depicting a discharge-recharge barrier-well system for the control of saltwater encroachment _____________--- 33 25. Hydrographs showing water-level declines in the Memphis Sand and the Sparta Sand _________________________------ 37 26. Sketch of the Baton Rouge, La., area, where a fault at least partially controls the advance of a saltwater front _____- BH TABLE Page TABLE 1. The 7-day, 10-year low flow at stream-gaging stations plotted in figure 12 | N19 v SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES-LOWER MISSISSIPPI REGION By J. E. TErry, R. L. Hosman, and C. T. BRYANT ABSTRACT The Lower Mississippi Region comprises an area of 102,400 square miles (265,200 square kilometers). Almost all this area is in the physiographic province known as the Gulf Coastal Plain. Three small areas on the northwest boundary of the region are in the Interior Highlands. The Lower Mississippi Region has an abundance of ground water. The geologic structure in that part of the region within the Coastal Plain is an elongated trough which has been filled with permeable materials, resulting in vast subsurface reservoirs. Except in local areas where continued large withdrawals have caused significant water-level declines, these reservoirs are full. Recharge to the region's aquifers is primarily from rainfall. An- nual rainfall in most of the region is well distributed throughout the year and is sufficient to satisfy evapotranspiration requirements and still provide recharge to the aquifers. An estimated 844 billion cubic feet (24 billion cubic meters) of fresh ground water is available for withdrawal annually in the re- gion. Only about one-third of this quantity is being utilized. There- fore, on this basis alone, the region still has much potential for ground-water development. The Coastal Plain aquifers within the Lower Mississippi Region contain large reserves of saltwater in the downdip limits of the aquifers. The quantity of saltwater in the region is several times that of freshwater. As desalinization techniques are developed and as more uses are found for saltwater, this reserve could become an important source of water for the region. At present (1976); the most productive and potentially productive aquifers or aquifer systems in the region are the Mississippi River valley alluvial aquifer of Quaternary age and the Sparta Sand and the Memphis aquifer (Memphis Sand in Tennessee) of Tertiary age. The Sparta Sand and the Memphis aquifer are heavily utilized and have shown significant water-level declines. However, selected well hydrographs indicate that water levels may be stabilizing under present pumping conditions. The Mississippi River valley alluvial aquifer is the most extensive high-yielding aquifer in the region; yields of several thousand gallons per minute may be obtained at depths of less than 200 feet (61 meters). To obtain maximum benefit from the vast quantities of ground water in the region, adequate attention must be given to the effects of proposed development upon the ground-water regime. Knowledge of the geologic structure and hydraulic properties of the aquifer sys- tems is essential to an evaluation of the effects of such development. Some studies have been made in sufficient detail to provide this knowledge, but additional studies are needed. Activities that could cause significant changes in the ground- water regime should be undertaken only after all available infor- mation has been considered. Failure to seek out and use such information may result in inefficient development of the ground- water resource and, in some instances, degradation of the quality of the resource. Some changes always result from ground-water development. The possible changes can be grouped into three categories: hydraulic, water quality, and those affecting the physical framework of the aquifers. Generally, they are small in magnitude and areal extent. Because these changes occur below the ground surface, they are unknown to the ground-water user unless they noticeably affect the quantity or quality of water produced or cause obvious physical ef- fects, such as land subsidence. Great advances have been made in hydrologic technology in re- cent years. Predictive models have been developed that make it pos- sible for the hydrologist to simulate aquifer responses to proposed development or other stresses. These models would be invaluable tools in progressive water-resources planning and management. INTRODUCTION LOCATION AND SIZE OF AREA The Lower Mississippi Region, as defined by the Water Resources Council, 1970, includes all the drainage basin of the Mississippi River downstream from its confluence with the Ohio River, except those parts of drainage basins of the Arkansas, Red, and White Rivers upstream from the backwater limits of the Mississippi River. It also includes the flood- protected areas at Cairo, Ill., and the Louisiana coastal area. The region comprises parts of Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee, and encompasses about 102,400 mi* (265,200 km*?). Drainage from almost half of the con- terminous United States culminates in the Lower Mississippi Region (fig. 1). The Mississippi River ter- minates at the lower end of the region, completing a river course totaling 2,348 mi (3,778 km) (U.S. Geological Survey, 1970). THE NEW LAND Explorers, traders, and hunters who sought adven- ture and fortune were the first to travel the valley of the Mississippi River. Following the trails they blazed, immigrants came to farm the river soil and to settle the wilderness. These early settlers in the Lower Mississippi Region found the Mississippi River to be both friend and foe. The river provided a mode of transportation and fertile soil for farming, yet it be- N1 N2 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES FigurE 1.-The Lower Mississippi Region. came a destructive force during floods. Since the time when the first plots of land were cleared for farming, agriculture has played a major role in both the economic and the cultural development of the region, and because the most productive land for farming lies along the Mississippi and its major tributaries, flood control has been the object of much concern and effort. In more recent years, industry has greatly increased in the region. From Cairo, Ill., to the Gulf of Mexico, and between New Orleans and Lake Charles, La., are found petroleum refineries and related facilities, in- dustrial and agricultural chemical plants, grain elevators, processing plants for food and kindred products, shipyards, textile mills, manufacturers of paper and related products, powerplants, cement plants, and aluminum-producing complexes. The re- liance of many of these industries upon the river for movement of raw materials and finished products con- tinues to focus regional attention upon the surface- water resource. LOWER MISSISSIPPI REGION PURPOSE AND SCOPE In contrast to the recognition given to surface wa- ter, only minor attention has been given to ground water in the Lower Mississippi Region since the early 1900's. The purpose of this report is to direct attention to the region's large ground-water resource so that it will not be overlooked when plans for water-resource- related changes within the region are devised and im- plemented. The pertinent questions about ground water that should be considered in developing and implementing water-management plans are: 1. Where is the ground water? 2. How much ground water is available? 3. What is the quality of the ground water? 4. What effects will development and use of ground water have on the total water resources and envi- ronment in the region? And, inasmuch as ground water is such an important part of the total water resources of the region and should be considered in planning- 5. What kinds of data are needed, and where are data insufficient, to permit full consideration of ground water in water-resource planning? This report supplies answers to these questions by presenting a regional assessment of the ground-water resource with emphasis on its significance. The scope is intended to be sufficient to permit evaluation of broad concepts of water planning for the region and to determine whether ground water has been adequately considered. This report is also intended to provide sufficient detail to serve as a basis for planning and program development. All unreferenced quantitative values in this report were taken from either the "Lower Mississippi Region Comprehensive Study," by the Lower Mississippi Re- gion Comprehensive Study Coordinating Committee (1974), or the "1975 National Water Assessment: Ground Water in the Lower Mississippi Region," by Boswell (1979). Most numbers in this report are given in inch- pound units followed by metric units in parentheses. The conversions to metric units were made as follows: Multiply By To obtain Inch-pound Inch-pound Conversion Metric Metric unit abbreviation factor unit abbrevi- ation ACC irc. Aiki ccie acre 0.4047 Hectare ha Acre-fool " ..._._....:. acre-ft 0012335 Cubic hectometer ___. hm Cublc fool. ....._...... ft? .02832 Cubic meter _...._._ m* Cubic foot per .02832 Cubic meter per second ft?/s Second-. m*/s Fobl ine ft 3048 Meler.. m Gallon gal 3.17854 Liter .-.....- f Gallon = -......-z...-- gal .0037854 Cubic meter Gallon per minute __ gal/min .06309 Liter per second _ ____ L/s NOR es in. 25.4 Millimeter _ ________-- mm Nile. mi 1.6093 Kilometer .-..... ._... Square mile _________- mi* 2.59 Square kilometer - ____ km Chemical concentrations are given only in metric units-milligrams per liter (mg/L). For concentrations N3 less than 7,000 mg/L, the numerical value is about the same as for concentrations in the inch-pound unit, parts per million. Throughout this report references to small, moder- ate, and large quantities of water in relation to aquifer yields have the following meaning: small, 0-50 gal/min (0-30 L/s); moderate, 50-500 gal/min (3-30 L/s); large, greater than 500 gal/min (30 L/s). THE WATER-RESOURCES SCENE The Lower Mississippi Region is indeed water rich. Precipitation throughout the region is generally abundant and well distributed areally. The normal annual precipitation ranges from 44 in. (1,100 mm) in the northern part of the region to 64 in. (1,600 mm) in the southeastern part (fig. 2). Seasonally, precipita- tion maximums occur in the winter in the northern part and in the summer in the southern part. A part of this precipitation is returned to the atmosphere by evapotranspiration, part infiltrates to the aquifers, and part becomes runoff. Potential evaportranspiration is the combination of evaporation from the ground surface and transpira- tion from plants that would occur if there were com- plete vegetation coverage and adequate soil moisture. In the Lower Mississippi Region, average annual po- tential evapotranspiration ranges from 30 in. (760 mm) in the north to 44 in. (1,100 mm) in the south (fig. 3). Because periods of limited soil-moisture availability occur from time to time and vegetation coverage is not complete in many areas, actual evapotranspiration throughout a long period averages only about 70 to 90 percent of the potential value. Runoff, including base runoff and direct runoff, combines with surface inflow to the region to make up streamflow and maintain water levels in surface- water impoundments. Runoff ranges from 18 in. (460 mm) in the north to 26 in. (660 mm) in the south (fig. 4). Recharge to the confined aquifers occurs primarily in the outcrop areas. In the alluvial unconfined aqui- fers, recharge occurs in areas where the vertical hy- draulic conductivity of the overlying material is suffi- cient to allow downward movement of water. When evapotranspiration requirements are met and soil- moisture storage maximums are exceeded, water in- filtrates to the aquifers. An estimate of available re- charge can be expressed by: Recharge = precip - (ET + direct runoff), where precip = precipitation, ET = evapotranspiration, and direct runoff = direct surface runoff. N4 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES "eu, gsNYoNg‘ g ollfsponsse ‘Nfllfljwnn r Stet mwsmu 1 ‘flm j "3 Oxterd l yue } umcoun [. "392 Y Nap. lame Ta sr ' 54’ & ge 4 a ( _Ne#4 fi‘hzrvznsow c a ofAv {,- cans | i” Jerry )Cvo Iey | ig *%. figfffi Ais (URC; muamson | |a mp 1 ¢ 6 \f No tig 6 2 4 " 62 An PII panes | ¢ % 1% esplle -~ WA: e re. 885% olpriesipr Ie. & 2 MC EXPLANATION fn 82 mam Line of equal average annual precipitation. Interval 4 inches (102 mm) # Line of equal average annual temperature. womm / (5 ° C mmm Interval as shown, in degrees Celsius Regional boundary o woodvitd \ Liberty Base from U.S. Geological Survey, 1965 United States base map, 1965 © | s 91° 89 (i) 5|0 190 1 $0 2(|JO 2?O KILOMETERS L4 14 $ 3 I T_ o 50 100 150 MILES FiGurE 2.-Normal annual precipitation and temperature (modified from Lower Mississippi Region Comprehensive Study, 1974, v. 1, app. C). LOWER MISSISSIPPI REGION 2, '=] fa: (v e ts br \ -o ? g f "_ (x ays Sz‘.“ kit; a ed «emf-nu. “t (~Paverte | ~~ \ Roljsponss A?"""fif\fl"”"‘,§ 6° hy Shang F Wl < M unsung! ® ‘Rnplgyk s Pre hau al o \ 22 - [AST gim | S. priors |_. | SAZ | uemerre | \n EXPLANATION INCHES +s0° \ Base from U.S. Geological Survey, 1965 94° f ° | United States base map, 1965 (s | | | | | | | | | 29° BGB + i 0 94° 93° 92° g1° 90° go (|) 510 1OIO 1 ?O 2?O 2?0 KILOMETERS £9. _E 3 3 I I I 0 50 100 150 MILES FIGURE 3.-Average annual potential evapotranspiration (from Thornthwaite, 1948). N5 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES EXPLANATION Line of equal average annual sms 7 (§ rusts runoff. Interval 2 inches (51 mm) ==» _ Regional boundary 89° 30° 2 Base from U.S. Geological Survey, 1965 °, * | United States base map, 1965 | \~* 0 50 100 150 200 250 KILOMETERS I tpl f- 4 | f | | ; | | 0 50 100 150 MILES FIGURE 4.-Mean annual runoff, in inches. LOWER MISSISSIPPI REGION HYDROLOGIC BOUNDARIES The Lower Mississippi Region does not constitute a single or discrete hydrologic system. Although the re- gional boundaries are located primarily on drainage- basin divides, three major streams in addition to the Mississippi River bring substantial quantities of water across the regional boundary. In addition, and of even more significance in this region, underlying aquifers extend into adjacent areas and ground water moves into and out of the region. Because the re- gional boundaries are not completely hydrologically restrictive, the water resources of the region are af- fected by hydrologic events outside the region. SURFACE WATER The Lower Mississippi Region's surface-water sup- ply is derived from precipitation and runoff within the region, streamflow including ground-water discharge entering the region from adjacent areas, and ground-water discharge to streams within the region. The total mean annual inflow in major streams en- tering the region is nearly 550,000 ft/s (15,600 m*/s). The mean annual stream discharge generated within the region is about 120,000 ft?/s (3,400 m/s). Each of the 29 controlled surface-water reservoirs within the region has a capacity of 5,000 acre-ft (6 hm») or more. The reservoirs have a combined storage of about 10 million acre-ft (12,300 Mean-annual stream outflow from the region is about 670,000 ft®/s (19,000 m*®/s). Theroretically, this is the ultimate quantity of surface water available for use. However, because of the small number of avail- able storage sites and the increased evaporative losses of surface water that occur with development, this quantity is not realistically obtainable. The depend- able surface-water yield must therefore be defined on the basis of the percentage of time a given flow is available. For the Lower Mississippi Region, the 95- percent-duration flow (the flow that will be equaled or exceeded 95 percent of the time) is 216,400 ft®/s (6,100 m?/s), or 160 million acre-ft (197,000 hm?) per year. In 1970, regional surface-water withdrawals aver- aged 22,000 ft?s (620 m/s) or 16 million acre-ft (20,000 hm?) per year. The total water returned to streams, including ground water withdrawn and not consumed, was 18,000 ft?/s (510 m*®/s). The result was a net streamflow loss of 4,000 ft?/s (113 m*/s). GROUND WATER Ground water occurs in large quantities in the Lower Mississippi Region and is readily accessible be- cause of the regional geological framework. Almost all the region is within the Gulf Coastal Plain physio- NT graphic province; three small areas along the north- west boundary are in the Interior Highlands (fig. 5). The Lower Mississippi Region includes most of the Mississippi embayment, a northeast-trending struc- tural trough underlying part of the Coastal Plain. The Coastal Plain and the embayment received sediment during the Cretaceous, Tertiary, and Quaternary Periods. The older deposits generally consist of alter- nating layers of sand and clay; the Quaternary beds contain considerable gravel. The more permeable sand and gravel deposits now form the extensive and pro- ductive aquifers that underlie the Lower Mississippi Region. The Cretaceous and older Tertiary units in the northern or embayment part of the area dip toward the axis of the Mississippi embayment, which coin- cides approximately with the present course of the Mississippi River. In the southern part of the area, the younger Tertiary deposits dip gulfward. Quaternary alluvium blankets most of the area and forms a gulfward-thickening wedge in the southern part (fig. 6). Except in areas of outcrop and where local dewater- ing has taken place, water in the Cretaceous and Ter- tiary aquifers is confined under pressure; that is, water levels in wells tapping these aquifers rise above the top of the aquifer. Most of the Quaternary aquifers are also confined. In some areas, hydrostatic pressures are sufficient to produce natural flows from wells; in some areas, wells that once flowed no longer flow due to pressure declines. Although most of the declines have been caused by heavy pumping, a contributing and in places critical factor has been the practice of allowing uncapped wells to flow unregulated. Recharge to the aquifers is primarily from rainfall. The movement of water in the confined aquifers gen- erally is downdip unless affected by large withdraw- als. In the alluvial aquifers, movement is toward points of discharge. The base of freshwater in the Coastal Plain aquifers is shown in figure 7. All aqui- fers locally contain some saltwater: Quaternary aqui- fers in coastal areas and the older aquifers in their downdip areas. The vast reserves of saltwater in the Coastal Plain aquifers may prove to be an asset to the area as de- salinization technology advances. The quantity of saltwater available is several times that of freshwa- ter. Some saltwater is now used for purposes such as industrial cooling. Similar uses that can tolerate | water of this quality will further enhance the value of the resource. Aquifers in the parts of the Lower Mississippi Re- gion that lie in the Interior Highlands do not repre- N8 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES COASTAL PLAIN * qminiistdd 56K n anifiscéx. y ( -/- ' 91° 90° 50 100 150 290 2?O KILOMETERS 150 MILES EXPLANATION Quaternary loess Quaternary terrace and alluvial deposits Pliocene and Miocene. Series undifferentiated Vicksburg Group, Forest Hill Sand, and Jackson Group Claiborne Group Wilcox Group Midway Group Cretaceous rocks, undifferentiated Paleozoic and Precambrian rocks, undifferentiated Boundaries are dashed where inferred or approximate Base from U.S. Geological Survey, 1965 United States base map, 1965 FigurE 5.-Geologic map (modified from Lower Mississippi River Comprehensive Study, 1974, v. 1, app. C). TERTIARY LOWER MISSISSIPPI REGION 0 & ~ kel T _ C > wou a & F > gC | 5 4 s § olz E - g Kip: 4" < At 3 tow 90. 1 w [; MEAN SEA u 2 LEvEL 2 u -s 2000 (610) o z $ 29.708 a - £8 $ &. 12 u w 2m § & & » E a #23 B ad s Q 27 mean sea | 0 & | Quaternar fu - LEvEL & 2 ARKANSAS LZL < 2000 (610) LOUISIANA = Ad he 3 ( z 4000 (1219) > G m a F m C - w d < J bg S i MEAN SEA { w _ LEVEL E w g * I 2000 (610) € u w 2 o 30.60 KiLOMETERS o 3 4000 (1219) ; a 0 20 (40 MILES l: g Geologic sections in part from Cushing, 1963 i 1 5 La.] Miss. _ , a , & s D o i D £ J E o E 2 & MEaNatA u U mEAN SEA uaternary, m IJ>J LEVEL 5B LEVEL eela n_ ALC | z. J € 3 - - - - { 2000 (610) F - $ ©2000 (610) |- - 3.11 i z fl ® - Tertiary - u Z hig u Z < 4000 (1219) r z 4 4000 (1219) |- - E w o - LW - a g 2 x ig < A z 6000 (1829) 4 G z 6000 (1829) |- - 3 0 3 0 l - 3 E J 5g 8000 (2438) 51g 8000 (2438) Fe | § = Mt Af ds slg! Sl,l sl > La.[Miss. BB 5861 "If C A | | gus 19 SHL 4 w q. MEAN SEA R oa _- e E E LEVEL TEEaterna—r y- fs TGT T. Cam A 2 J R § 1 g 2000 (610) Teftiary " o flj % 93th 200° i u Z 4000 (1219) |- ~TS¥ i z - At - - w Z e000 (1829) |- 4 o & 2 9 - C u 8000 (2438) 5 m $ - 50. : 100 200 300 400 KILOMETERS < I &- | ; 1 1 ; 0 50 100 200 MILES FicuUrE 6.-Generalized geologic sections in the Lower Mississippi Region (modified from Lower Missis- sippi River Comprehensive Study, 1974, v. 1, app. C). NQ N10 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES al / / F4, acc Ne: "5: iii—3 et" "tJ S o .% p’ four |y - sorte | "l cable | J (® ~- “lbw 89° nev frren 36008 lodkenita (- e 8g \p.n ".C ns "Rum?! 0 330.27; a—fi‘tfi _ ay & D « " em p “2“ "16% SFrovidgrlce) a e \ A Area where intermediate beds may contain saltwater e Ca & NFS (th "ay. . %§z & Ci/: a ~ | h een) if? Area where fresh ground water is not available in significant quantities gm? FE" 01536wa Interior Highlands - Paleozoic and e Precambrian rocks, undifferentiated --500- _ Contour on the base of freshwater. Contour interval 500 feet (152 m). Datum is mean sea level 89° 1s0° | Base from U.S. Geological Survey, 1965 United States base map, 1965 220° 50 100 15-110 290 2?) KILOMETERS I T. 50 100 150 MILES FicurE 7.-Base of freshwater in Coastal Plain aquifers (modified from Lower Mississippi River Comprehensive Study, 1974, v. 1, app. C). LOWER MISSISSIPPI REGION sent a significant resource to the region. Rocks in these areas are of Paleozoic age, mostly hard sandstone and shale, and the ground water they con- tain occurs in openings along fractures and bedding planes. The interstitial porosity and permeability that make the unconsolidated aquifers of the Coastal Plain so productive do not exist in the Interior Highlands. An estimated 347,000 billion ft? (9,800 billion m*) or 7,900 million acre-ft (10 million hm*) of freshwater underlies the Lower Mississippi Region. Of this total, about 844 billion ft? (24 billion m*) or 19 million acre- ft (23,900 hm) is available annually for development, using conventional methods. In 1970, regional ground- water withdrawals averaged about 8,300 ft*s (240 m?/s) or 6 million acre-ft (7,400 hm) per year. About 65 percent of the ground water withdrawn in the region is used for irrigation, about 15 percent by industry, and about 8 percent for municipal supply. The remaining 12 percent is used for domestic supply, livestock watering, and other uses. WHY IS GROUND WATER OF IMPORTANCE IN THE LOWER MISSISSIPPI REGION? WIDESPREAD ACCESSIBILITY Ground water is available beneath the entire Lower Mississippi Region. Except for small areas in the N11 Interior Highlands and the coastal area of Louisiana, one or more major aquifers (fig. 8) make moderate to large quantitites of freshwater available throughout the region (fig. 9, 10). The three areas in the region that are in the Inte- rior Highlands are the Arkansas Valley and the Ouachita Mountains in west-central Arkansas and the Ozark Plateaus in southeast Missouri. In these areas, small quantities of ground water are available from Paleozoic rocks (figs. 9, 10). Aquifers of Cretaceous age underlie the northern part of the region. Except for relatively small areas in Arkansas, Tennessee, Mississippi, and Missouri, the Cretaceous material is overlain by Tertiary and (or) Quaternary aquifers (fig. 6) that can yield moderate to large quantitites of water to individual wells. For this reason, the deeper Cretaceous aquifers are not utilized extensively. The major Cretaceous aquifer is the McNairy Sand Member of the Ripley Formation in Mississippi (equiv- alent to the McNairy Sand in Tennessee, Missouri, Illinois, and Kentucky, and the Nacatoch Sand in Ar- kansas). These aquifers are present throughout the northern one-fifth of the region within the Coastal Plain and in a small area in southwest Arkansas, a total area of nearly 20,000 (52,000 km). With- drawals have been restricted to areas where the 1: Quaternary (_" 33 (. "> Vertical distribution of major aquifers Mio-Pliocene aquifer Cockfield Formation Sparta Sand Carrizo Sand Lower Wilcox aquifer Ripley Formation Memphis aquifer N12 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES ARCA < ‘ t vkagelohs Po ° EXPLANATION Number of major freshwater aquifers 37° (or aquifer systems) available CJ 0 § 1 2 or 3 Base from U.S. Geological Survey, 1965 United States base map, 1965 50 1C])O T?O 2(|)0 27.30 KILOMETERS I 50 100 150 MILES FiGurE 8. -Multiple freshwater aquifers underlie 90 percent of the Lower Mississippi Region. LOWER MISSISSIPPI REGION 93° EXPLANATION Availability, in 1,000 gallons per day per square mile 0° (1.46 cubic meters per day per square kilometer) No fresh ground water Less than 1 1-5 5-25 25-125 125-250 250 or more Base from U.S. Geological Survey, 1965 \ United States base map, 1965 50 100 150 2530 251)O KILOMETERS I I I i 50 100 150 MILES FicurE 9.-Availability of fresh ground water. N14 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES dern \ y elens % ups ge uni; se w cs?" 5-5:qu thew yneout 1, B C p sec y Gr“? =I lE c 4: 31 290° - EXPLANATION “use" ya " son |, Arids j ”mm 33 (s fames Yield of wells ~ 1; a } (in gallons per minute) 0-50 50-500 (_] More than 500 Only saltwater available 42 41m AwKL Base from U.S. Geological Survey, 1965 United States base map, 1965 50 190 15:0 2C|JO 2?0 KILOMETERS I I 50 100 150 MILES FiGurE 10.-Ranges in well yields throughout the region; only in small areas do wells yield less than 500 gallons per minute (modified from Boswell, 1975). LOWER MISSISSIPPI REGION aquifers are present at moderate depths and water levels have been practically unaffected by pumping. Other Cretaceous aquifers are important in some areas where they are the best or only sources of ground water available. In north-central Mississippi and parts of west Tennessee, the Coffee Sand is utilized. It is the best or only source of ground water in many places in this area where the underlying Eutaw Formation is too thin or yields highly miner- alized water, or where Paleozoic rocks do not contain aquifers. The Gordo Formation underlies the Eutaw Formation in north-central Mississippi, primarily south of the downdip limit of the Coffee Sand. Water in the Gordo Formation generally is good quality and is the best available in this area. Tertiary aquifers underlie virtually the entire Lower Mississippi Region, except for three small areas on the western border, two in Arkansas and one in Missouri, and a small strip on the eastern border in Tennessee and Mississippi. The Tertiary aquifers north of a line approximately through Vicksburg, Miss., to Colfax, La., are of Eocene age. South of this line, Miocene aquifers overlie the Eocene deposits. These beds dip southward and are, in turn, overlain by Pliocene deposits south of the 31st parallel. The significant Eocene aquifers, in ascending order of their occurrence, are: the lower Wilcox aquifer, the Carrizo Sand (and its stratigraphic equivalent, the Meridian Sand Member of the Tallahatta Formation), the Sparta Sand, and the Cockfield Formation. The lower Wilcox aquifer, the basal unit of the Wil- cox Group, occurs throughout the northern one-third of the Lower Mississippi Region and in a strip across central Arkansas. It crops out in a narrow belt in north Mississippi and west Tennessee (Fort Pillow Sand in the subsurface of west Tennessee) and occurs as a subcrop beneath the Quaternary alluvium in Ar- kansas and Missouri. The lower Wilcox aquifer is a source of water for several cities in northeast Arkan- sas and northwest Mississippi. Except for the lower Wilcox aquifer, the Tertiary aquifers mentioned previously are in the Claiborne Group. The basal unit of the Claiborne is the Carrizo Sand in Arkansas and Louisiana and its equivalent in Mississippi, the Meridian Sand Member of the Tallahatta Formation. This unit crops out in a narrow band in central Mississippi and southwest Arkansas and is a relatively minor aquifer in central Arkansas and in west Mississippi north of the latitude of Vicks- burg. Separating the Carrizo from the overlying Sparta Sand is the Cane River Formation and its equivalents, composed mostly of clay and a few thin beds of fine, almost impermeable sand. The Cane River and its equivalents contain only very minor N15 aquifers in south-central and southwest Arkansas and in west-central Mississippi. In northwest Mississippi, the Winona Sand (equivalent to the Cane River For- mation) becomes more significant and merges into the Memphis aquifer. The Sparta Sand underlies the en- tire central part of the region. It crops out on the east- ern side in a wide belt, from southwest Kentucky through Tennessee and Mississippi, and on the west side in northeast and south-central Arkansas. The Sparta occurs as subcrops beneath the Quaternary al- luvium in some areas in Arkansas and Mississippi. The Sparta is a very productive aquifer throughout the northern three-fourths of the region. The Cook Mountain Formation, which is not an aquifer, overlies the Sparta Sand and separates it from the uppermost unit of the Claiborne Group, the Cockfield Formation. The Cockfield Formation directly underlies the Quaternary alluvium in most of the central part of the region. It includes productive aquifers in Arkansas, Louisiana, and Mississippi. The Cockfield crops out in small areas in southeast Arkansas, along the Arkansas- Louisiana State boundary, in northwest Louisiana, and in central Mississippi. North of approximately the 35th parallel, the Mem- phis aquifer (Memphis Sand in Tennessee) comprises all Claiborne units from the base of the Carrizo Sand to the top of the Sparta Sand. This part of the Claiborne section is a massive sand several hundred feet thick which constitutes a vast ground-water res- ervoir. As such, the Memphis aquifer is second only to the Mississippi River valley alluvial aquifer as a potential source of large quantities of ground water. Aquifers of Oligocene age in the Forest Hill Sand and the overlying Vicksburg Group occur in a small area in the southern half of the Lower Mississippi Re- gion. These aquifers, although they are not extensive, are the only sources of fresh ground water in the 500 ft (150 m) or more of sediments between the top of the Claiborne Group and the base of the Miocene Series. Aquifers of Miocene age occur south of a line ap- proximately through Vicksburg, Miss., to Colfax, La. South of approximately the 31st parallel, the Miocene deposits are overlain by the Pliocene Series. These two series are lithologically similar and are referred to in Louisiana, where they occur together, as the Mio-Pliocene aquifer. In Mississippi, the Miocene de- posits are divided into the undifferentiated upper Miocene aquifer and the Catahoula Sandstone. Both the Miccene and Pliocene Series are overlain by Quaternary deposits and, except for Miocene outcrops in west-central and southwest Louisiana, are not ex- posed at the surface. Both of these series are good present and potential sources of moderate to large quantities of fresh ground water. Near the Louisiana N16 coast, water in both series becomes salty gulfward. Deposits of Quaternary age cover most of the Lower Mississippi Region. Sediments of Pleistocene and Holocene age compose the Mississippi River valley alluvial aquifer, the most extensive source of ground water in the region. The Pleistocene deposits contain gravel at the base, grading upward to finer sand, and are the most productive parts of the aquifer. The over- lying Holocene material is composed of very fine sand, silt, and clay. In many areas it forms a confining layer although it is permeable to varying degrees. Large quantities of water are available from the Mississippi River valley alluvial aquifer throughout most of the region. The aquifer's value is enhanced in that, generally, only shallow well depths are required, pumping lifts are small, and recharge conditions are favorable. Throughout most of the Lower Mississippi Region, recharge to the alluvial aquifer is by precipi- tation. In some areas, where overlying fine-grained materials are nearly impermeable, the aquifers are recharged by underflow. Along the coast in Louisiana, especially in the southeastern part of the State, the alluvial aquifer contains saltwater. Ground water can be obtained with relative ease almost everywhere in the Lower Mississippi Region. For this reason, most public, industrial, and agricul- tural supplies are from wells. In most areas within the region, obtaining adequate quantities of water from surface-water supplies would be economically unfeas- ible. Of the total 102,400 mi? (265,200 km?) within the Lower Mississippi Region, about 5 percent is covered by surface water. In contrast, 90 percent of the region is underlain by two or more aquifers that can yield 100 gal/min (6L/s) or more to individual wells. In contrast to surface reservoirs that inundate many acres of land, large quantities of water are stored in subsurface reservoirs without loss of surface area. Some disadvantages of surface reservoirs are high construction costs, cost of land purchase, loss of land use, and maintenance. Another consideration is that some terrain is not suited for large reservoir con- struction. Much of the area within the southern half of the Lower Mississippi Region could be classified as unsuitable because of the absence of deep, broad stream valleys that could be dammed. For these rea- sons, much dependence is placed on the region's sub- surface reservoirs. LARGE AMOUNT AVAILABLE Approximately 347,000 billion ft? (9,800 billion m?) of water, containing less than 3,000 mg/L dissolved solids, is stored in the subsurface of the Lower Missis- sippi Region. This quantity of water is more than 16 times the average annual surface-water outflow from SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES the region, and if contained in a reservoir it would cover an area the size of the entire region to a depth of 120 ft (37 m). Of this total, about 844 billion ft? (24 billion m*) is available annually for development, based on withdrawals consistent with economically and environmentally acceptable water-level declines. The primary containers of ground water in the lower Mississippi Region are the extensive uncon- solidated sand-and-gravel aquifers of Tertiary and Quaternary age. The ability of these aquifers to store and transmit water varies due to differences in thick- ness and hydraulic conductivity. However, single aquifers that can yield 500 gal/min (32 L/s) or more to individual wells underlie about 90 percent of the re- gion (fig. 10). The highest yields, often several thou- sand gallons per minute, are from wells screened in sand and gravel of the Quaternary alluvial-terrace deposits. The alluvial and terrace deposits account for two-thirds of the potential ground-water supply in the region. Within most of the Lower Mississippi Region, water-table aquifers commonly discharge water to streams that are connected with them (fig. 11A). Also, some streams that have sufficient hydraulic connec- tion with a confined aquifer may receive contributions from the aquifer. Such a condition occurs when the altitude of the water surface in the stream is less than the head (potentiometric surface) in the aquifer (fig. 11B). Under dry, low-flow conditions, perennial streams are sustained completely by discharged ground water. The lowest flow that occurs in a stream for 7 consecutive days once every 10 years is com- monly accepted to be composed of discharged ground water. U.S. Geological Survey stream-gaging stations, within the region, where the 7-day, 10-year low-flow has been defined, are shown in figure 12. Table 1 con- tains the 7-day, 10-year low-flows for the stations plotted in figure 12. Where there is good connection between a major stream and an aquifer, advantage can be taken of the relationship by locating wells near the stream. When a well is pumped, one of two things will occur. If movement has been from the aquifer to the stream, gradients will flatten and may reverse in the vicinity of the well, utilizing water normally discharged to the stream and even taking water from the stream if the gradient reverses. If movement has been from the stream to the aquifer, the gradient will become steeper as the head in the aquifer near the well is re- duced by pumping. In either instance, some water is diverted from the stream, thereby reducing the stress on the aquifer (fig. 13). Most aquifers in the Lower Mississippi Region are full; consequently much potential recharge is rejected LOWER MISSISSIPPI REGION SuffacE J Unoff . Water table ___ Water-table aquifer Stream in hydraulic connection with a water-table aquifer. Under normal conditions the stream receives some water from the aquifer. Water table __ Water-table aquifer 1. The same stream during low-flow conditions. The only flow in the stream is ground-water discharge. Su rfaCe rU” o Lf Potentiometric Artesian aquifer . Stream in hydraulic connection with an artesian aquifer. Under normal conditions the stream is receiv- ing some water from the aquifer. __ __ Potentiometric tesian aquifer |__ The same stream during low-flow conditions. The only flow in the stream is ground-water discharge. FIGURE 11.-Ground water-surface water relations during normal and dry conditions. N17 and evapotranspired or discharged to streams. When ing head relations can cause the aquifer to become re- an aquifer is tapped and water is withdrawn, chang- ceptive to recharge (fig. 14). Under the most favorable N18 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES 9134571, #T W'fiét; f agian ,£¢'\’ Jonesboro 9 c sagan / | \ [Span Meuepan : _ tea. ”ii HAL nse .J 1 | k || Prace. \ fren >= / Parken £ Aasoem| \ 04 621 jamouey, Rooly ! e 1 I SN im | \, E1 Oorado I ”muff" A ir & I a fl» att ¥ Lreess o oan {gt CP FB ())) ) Kn f "#9 _,, _L \ |f Jl F ls Ng Sf / /-» 33 havea ~. Aase Graw ‘_‘ rara) res cg ("I% (C ‘.;’.. Y uncontr: L: 5-7 z 1d ;‘ a £"G Jammy \_ _" #} 36 roMR ART msso uis *I '~\~- 290° a C EXPLANATION A *°°° - Continuous-record gaging station. Numeral beside 7 symbol is abbreviated station number 'er 5x e iwll - f ‘ «Y, ; ‘i I, \ 31° 1 "MT a uo t ja.. " por fi' ,,,,,, tee, Base from U.S. Geological Survey, 1965 United States base map, 1965 29° o (I) 510 KEG 1?0 2(|)0 25r0 KILOMETERS LLA + (3 | 0 50 100 ap 150 MILES FIGURE 12. -Selected 7-day, 10-year low-flow sites. LOWER MISSISSIPPI REGION N19 TABLE 1.-The 7-day, 10-year low flow at selected stream-gaging stations plotted in figure 12 Station 7-day, 10-yr Station 7-day, 10-yr low flow s - low flow Number Name (ft/s) Number Name (ft?/s) 07022500 Perry Creek near Mayfield, Ky 0.0 07290650 Bayou Pierre near Willows, Miss _ ______________________._--- 19 07022600 Mayfield Creek at Mayfield, Ky 0 07291000 Homochitto River at Eddiceton, Miss _ ________________------ 31 07023000 Mayfield Creek at Lovelaceville, K 77 07292500 Homochitto River at Rosetta, Miss _________________-___----- 140 07023500 Obion Creek at Pryorsburg, Ky -- & 0 07295000 Buffalo River (Bayou) near Woodville, Miss _ ____________---- 20 07023700 Obion Creek near Arlington, Ky a 3.3 07356000 Ouachita River near Mount Ida, Ark _ __________________---- 6.0 07024000 Bayou du (de) Chien near Clinton, Ky ______________---- & 6.3 07356500 South Fork Ouachita River at Mount Ida, Ark ____________-- 0 07024500 South Fork Obion River near Como, Tenn ____________-- 2 79 07357000 Ouachita River near Mountain Pine, Ark _ __ 19 07025500 North Fork Obion River near Union City, Tenn _ ______- # 90 07359500 Ouachita River near Malvern, Ark _ ____ 73 07026000 Obion River at Obion, Tenn * 260 07359800 Caddo River near Alpine, Ark ________ 13 07027500 South Fork Forked Deer River at Jackson, Tenn ______- 2 80 07360000 Ouachita River at Arkadelphia, Ark _____- 110 07028100 South Fork Forked Deer River near Halls, Tenn _________--- 145 07360800 Muddy Fork Creek near Murfreesboro, Ark _ _- 0 07029100 _ North Fork Forked Deer River at Dyersburg, Tenn ________-- 93 07361000 _ Little Missouri River near Murfreesboro, Ark 3.6 07029500 Hatchie River at Bolivar, Tenn - ___...__....._____.._.._._.. 122 07361200 Ozan Creek near McCaskill, Ark _ __________ 0 07030050 Hatchie River at Rialto. Tenn 284 07361500 Antoine River at Antoine, Ark _ _________- 0 07030280 Loosahatchie River at Brunswick, Tenn = __________________-- 58 07361600 Little Missouri River near Boughton, Ark 27 07030500 Wolf River at Rossville, Tenn 124 07362000 Ouachita River at Camden, Ark _________- 175 07031700 Wolf River at Raleigh, Tenn 158 07362100 Smackover Creek near Smackover, Ark ___ A 07032000 Mississippi River at Memphis, Tenn __________________------ 99,000 07362500 Moro Creek near Fordyce, Ark _ __________ 0 07037500 St. Francis River near Patterson, Tenn _ _______________----- 14.7 07363000 Saline River at Benton, Ark _ __________-- 1.1 07040100 St. Francis River at St. Francis, Ark - __________________---- 76 07363300 Hurricane Creek near Sheridan, Ark _ ____ 4 07040450 St. Francis River at Lake City, Ark _ ____ 2 97 07363500 Saline River near Rye, Ark ________________ 11 07041000 Little River Ditch 81 near Kennett, Mo 2 15 07364100 Ouachita River near Arkansas-Louisiana State 780 07042000 Little River Ditch 1 near Kennett, Mo ___- 2 17 07364150 Bayou Bartholomew near McGee, Ark Poses 4.5 07042500 Little River Ditch 251 near Lilbourn, Mo s 30 07364200 Bayou Bartholomew near Jones, La - _. 39 07044000 Little River Ditch 251 near Kennett, Mo _________ F 69 07364300 Chemin-a-Haut Bayou near Beekman, L <.1 07046600 Right Hand Chute of Little River at Rivervale, Ar 146 07364700 Bayou de Loutre near Laran, La _ ____ 2.4 07047000 St. Francis River floodway near Marked Tree, Ark 0 07365000 Bayou D'Arbonne near Dubach, La ________._--- 1 07047500 St. Francis River at Marked Tree, Ark 97 07365500 Middle Fork Bayou D'Arbonne near Bernice, La - __ A 07047600 Tyronza River near Tyronza, Ark _ ____ 27 07365800 Cornie Bayou near Three Creeks, Ark ____________ Wateratahle aquifer | If a pumping well is located near a gaining stream, the direction of movement of water in the vicinity of the well may change and water normally discharged to the stream will be utilized by the well. FicurE 13. of streamflow by nearby wells. LOWER MISSISSIPPI REGION Precipitation. on the outcrop provides recharge to the aquifer Artesian . __ aquifer . Pressure in the aquifer is great enough to maintain a head above the water-surface altitude in streams connected with the aquifer; therefore most potential recharge is discharged to the streams before it can move downdip. HI 141 § "98x b \ Artesian aquifer } \\ When water is withdrawn from the aquifer, pressure (and, thus, head) is reduced, allowing previously rejected potential recharge to move downdip. FIGURE 14. -Full aquifers reject recharge; movement of water downdip increases with utilization of the aquifer. N21 N22 TT ; te Ge |EAt m;- * o ,\ua~vqoncn‘gm C # & é . xes CB Ext friggflph a SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES n-Fn ERN my“. ucxv\ fare rr Likes >= Wand s", W- nngém lw | “Am/w v sf d § lm— "% Hi $ eries | "1 / A hA f .r¥ Icy“ 90 mph \ [ ¢ rld & | | £5 . flax. bg Ig (pourcmnflu m Greater than 3,000 evhncl ine j T I ite m C 157 1| cavs | {qwfif Is rd | ~- Cobh o EH A ra s Ree" 1 Base from U.S. Geological Survey, 1965 's \ United States base map, 1965 ache af " \ Spa® \~' s | 120" '8g° 50 Rio 1 ?0 KEG 2?0 KILOMETERS of. 50 100 150 MILES Figure 15. -Dissolved-solids concentration of available ground water (from Boswell, 1975). LOWER MISSISSIPPI REGION N23 - tsk ‘W f (kw. P a ® Gregpuie 3 ~ /*Nameo -| "Ample ~S~ j Brownsvil o |e Ask ‘fif E mowiges-, , e | | montoomery C MUA *for son \\‘ is 42 34° omen al re ** CP mele ta, Passy far ¥ 33" Revigyse / ® arco Giv oaugy HALE AS * °,307 } iv m ,,y_‘.mu— pe: mm: l rag? % “A???“ pg " son |, * "r?" EXPLANATION f 1L & I! f I]: ; A 37 ~ # & x1“ a 1°; 37° 1:1 Caitfnuntl) magnesium carbonate «g f cl.. aP icarbonate type 23 Calcium magnesium sulfate . chloride type J k Sodium potassium carbonate a f io € 31° bicarbonate type § X a- f Sodium potassium sulfate mnzitfifi‘ N{- g0 chloride type feng jr p --- Boundary line a 89° 30% mul s e T aU $ - ® f" ‘ Base from U.S. Geological Survey, 1965 94°. Es | United States base map, 1965 I C ~~* | | . | | | | yas els.. __ "%n" > ife A -+ 20 299+4 g 90° 29° 0 50 100 150 200 250 KILOMETERS lI N | | [ | ; ] 0 50 100 150 MILES FIGURE 16. -Prevalent chemical types of water in streams at low flow (modified from Rainwater, 1962). N24 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES EXPLANATION = E 100 300 500 700 900 Milligrams per liter 30° Base from U.S. Geological Survey, 1965 United States base map, 1965 o--G wa o 0 ms o O 2?0 KILOMETERS am 50 150 MILES FIGURE 17. -Prevalent dissolved-solids concentration of water in streams at low flow (modified from Rainwater, 1962). LOWER MISSISSIPPI REGION agement it is quite likely to remain so; if the ground water being withdrawn requires treatment, it is not likely that, with proper management, treatment facilities will have to be changed significantly due to changes in the ground-water quality. Ground water is believed to be generally free of bac- teria and chemical pollution. This belief is generally valid because ground water moves through natural soil and rock filtering media which can reduce natural bacterial pollution to almost zero. No widespread oc- currence of bacterial pollution of ground water in the Lower Mississippi Region has been observed. How- ever, locally, individual wells may yield bacterially contaminated water due to faulty well construction or location. By definition, ground water is considered to be naturally "polluted" when natural mineral concen- trations exceed established criteria for various uses; so, whether water from a particular aquifer is consid- ered to be polluted depends upon the intended use. If a use problem arises, it can generally be solved by treatment of the water or, in some places, by tapping another available aquifer containing water that is more suitable. WHY ARE WE NOT GETTING MAXIMUM BENEFIT FROM GROUND WATER? INADEQUATE CONSIDERATION Although ground water is being widely utilized, re- gionally much of its potential is not fully realized. Because of flooding problems and the need for navi- gation, high priority has generally been given to de- tailed studies of the region's surface-water systems. As a result, steps have been taken to alleviate most of the severe flooding problems, and good water- transportation systems have been developed. The characteristics of most of the major streams in the re- gion are well defined, and consequently the behavior of these streams during periods of flood and drought is reasonably predictable. Knowledge of the behavior of the region's subsur- face water systems (aquifers) under natural or im- posed stresses is also important in water resources management. The ability to predict with some preci- sion the effects of additional ground-water develop- ment is needed. Data such as aquifer characteristics, interaquifer relations, and stream-aquifer relations must be available in order to make such predictions. At least as much effort should be made to define and control our subsurface waters as has been made to control our surface waters. Detailed ground-water studies, whose end results are predictive models, cover N25 only small parts of the Lower Mississippi Region (fig. 18). There is a general lack of public awareness of the overall significance of ground water and the possible widespread effects of ground-water development. Many times the proper information is not sought or is not properly analyzed before a ground-water-related development is started. There is also a lack of public awareness concerning specific problems, such as the possible impact upon the local ground-water regime of certain seemingly unrelated activities, such as land clearing, excavations, and the proximity of sewage facilities to shallow wells. IMPROPER DEVELOPMENT Improper ground-water development may entail one or any combination of the following: 1. Drilling below the base of freshwater. 2. Finishing a well above the most suitable aquifer. 3. Locating a well too near other pumping wells. 4. Locating a well too near a source of contamination. 5. Overdevelopment. Some of these development problems may be due to an information deficit, as mentioned in the preceding sec- tion, but often available information is adequate but it is not given due consideration. Sometimes when a new well is drilled, available in- formation is not considered to determine the depth of the water best suited to the need. Drilling below the base of freshwater, for example, is generally a waste of time and money (fig. 19A) and will increase the chances of well contamination, as head is reduced by pumping (fig. 19B). Of course, the reverse is also true; when a driller does not have adequate knowledge of the section he is drilling, he may stop short of the best water-bearing zone. Deep test holes, such as those drilled by oil com- panies, commonly pass through both freshwater aquifers and aquifers containing undesirable water (fig. 20A). If these holes are not properly plugged, they may become conduits through which undesirable water may leak into the freshwater zones that have lower hydrostatic heads (fig. 20B). Such leakage has caused saltwater pollution in local areas in the Lower Mississippi Region. The Mississippi River valley allu- vial aquifer in northeast Louisiana has experienced some saltwater pollution due to leaky abandoned wells (Whitfield, 1975). Interference between wells occurs when they are lo- cated too near each other and are screened in the same aquifer. The cones of depression, sometimes termed "zones of influence," created by continued withdrawal from the wells, may coalesce. This condi- N26 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES EXPLANATION Detailed coverage by intensive studies such as analog or digital modeling Relatively detailed coverage by inventory or appraisal studies [Z] Generalized coverage by reconnaissance studies Base data only |_ Base from U.S. Geological Survey, 1965 soy ‘ United States base map, 1965 (I) 50 100 1?O 2(|)0 2?0 KILOMETERS | I 0 C 50 100 150 MILES FiGurE 18. -Delineation of areas covered in ground-water-related reports. LOWER MISSISSIPPI REGION N27 surface . surface FicurE 19.-Disregard of available information can be expensive economically and ecologically. surface Test hole | Land 4} "___ surface Potentiometric surface aoe pment " mew hans oen cohen . mel - FicuUrE 20.-Abandoned, deep test holes cause contamination by interaquifer water exchange if not properly plugged. N28 tion will significantly reduce the amount of water the aquifer will yield to these wells. Observe wells A, B, and C shown in figure 21. Well A depicts a very poor location for a new well; well B depicts a fair location, if pumping is not increased significantly from either the new or the existing well; well C depicts the best location of the three for the conditions indicated. The development of a new water-supply well for a city within the region provides an example of both poor well spacing and disregard of information about the depth of the best water-bearing zone available. The city's existing water supply is from two wells screened at depth intervals of 365 ft (111 m) to 405 ft (123 m) and 370 ft (113 m) to 410 ft (125 m), in the upper part of the Claiborne Group. These wells each produce about 600 gal/min (38 L/s). About 300 ft (91 m) from one of these existing wells, the new supply well has been drilled to a depth of 575 ft (175 m). This well is screened in the 364-ft (111-m) to 398-ft (121-m) interval, the same water-bearing zone as the existing wells. It is intended that the well produce 1,000 gal/ min (63 L/s), which is the capacity of a new water- treatment plant that the city is now building. Before the well was screened, a gamma-ray log, run by the Factory Existing well New well a * x10 x95 o'fiec amo 53 3" e" Fair by 035° " location SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES Geological Survey on the pilot hole, indicated the presence of a possible aquifer 120 ft (37 m) thick below the lower confining layer of the thin (85 ft to 45 ft or 11 m to 14 m) aquifer now being used. Based on the piezometric surface in other wells tapping this aquifer, the pressure in this lower aquifer would have been sufficient to cause flow at ground surface. Fur- ther testing could have determined the potential of this lower sand. Some wells are located too near freshwater- saltwater interfaces. When withdrawals are made from such wells, head(pressure) in the vicinity of the well is reduced, allowing saltwater to move toward the well. This problem can be avoided or possibly solved if adequate information about the aquifer is available. Although saltwater is the most common pollutant associated with ground water in the Lower Mississippi Region, the proximity of proposed well sites to other sources of contamination should be care- fully considered before locating a well. "Overdevelopment" of an aquifer is a relative term. In local areas where water levels have been lowered enough to significantly increase pumping lifts and costs, the term "overdevelopment" is often applied (fig. A o 30 X®" et (566° 6x40 & (0°“ ewe“ ® _o" Poor Good location O New school FicurE 21.-A simplified sketch of how a well location should be selected. LOWER MISSISSIPPI REGION 22). If water levels around such pumping centers con- tinue to decline, the zone of influence will spread, re- sulting in increased pumping costs for users in the area even though they do not significantly contribute to the cause of the decline. Another cause of some loss in artesian pressure in aquifers within the region is the practice of allowing some naturally flowing wells to flow to waste. In southwest Arkansas, many wells that tap Cretaceous aquifers originally flowed at and above the land sur- face. Very few of these wells were capped and today, due at least in part to this waste, heads in these wells have dropped considerably and many of them have ceased to flow. FRACTIONAL USE OF AVAILABLE SUPPLY The availability of fresh ground water varies throughout the Lower Mississippi Region (fig. 9). Be- cause annual ground-water withdrawal in the region is about one-third of the annual amount available (fig. 23), rejected potential recharge constitutes a loss of water that would have entered the subsurface (fig. 14) if storage space were available. A maximum continu- ous withdrawal that could be sustained from an aquifer would be that quantity of water necessary to reduce the hydrostatic pressure and maintain it at such a level that the controlling factor on recharge to the aquifer becomes either the amount of recharge available or the ability of the aquifer to transmit water. As desalinization technology advances and as more uses are found for saltwater, the amount of usable ground water that is available in the region will in- crease several times. Utilization of saltwater will have a twofold effect-a reduction in demands placed upon freshwater aquifers, making more freshwater available for uses requiring better quality water, and a reduction of pressure in saltwater zones, thus allow- ing more freshwater to be withdrawn near saltwater interfaces without inducing coning or encroachment problems. HOW CAN WE OBTAIN MAXIMUM BENEFIT FROM GROUND WATER? Merely increasing the usage of ground water does not assure that the most benefit will be obtained from the available supply; in fact, unwise development could result in the opposite effect. The determination to protect, as well as utilize, ground water can prevent the waste that has resulted from misuse and misman- agement of some of our other natural resources. EXPAND INFORMATION BASE, AND USE IT Ground-water management in the future should N29 consider not only the local aspects of a planned de- velopment but also the regional framework into which the development must fit. To do this there should be an adequate information base containing at least the following kinds of data: physical and hydraulic condi- tions within the aquifers, the quality of water in the aquifers, and interaquifer hydraulic relations. Comprehensive planning or the development of proper planning tools cannot be done without know- ing the size and properties of the ground-water con- tainer involved. The vital statistics of an aquifer that must be determined are its thickness, areal extent, configuration, and texture. Also, the quality of water, and any areal or vertical changes in quality within an aquifer, should be known. In addition to the physical features, the hydraulic conditions within the aquifer must be understood, that is, the movement of water as influenced by recharge and discharge. The hydraulic characteristics of an aquifer are those properties that determine its ability to store and transmit water. Aquifer characteristics, such as hy- draulic conductivity and transmissivity, control the well yields, the amount of drawdown incurred to pro- duce a specified yield, and the magnitude of water- level declines produced by pumping. With this infor- mation, the probable effects of a planned development can be predetermined, and well fields can be designed to minimize well interference. In addition, these aquifer characteristics can be used to estimate the gross yield available from an aquifer throughout a large area under a prescribed set of conditions. Interaquifer relations-the way aquifers interact hydraulically with one another-must also be deter- mined regionally and locally. Some aquifers receive recharge through or from other aquifers. Confining beds may be sufficiently permeable to permit ex- change of water between aquifers. The movement of water into an aquifer that is being pumped can sig- nificantly affect water levels and water quality. In fact, in some areas where such conditions exist, the quality of water in an aquifer may be manipulated by carefully planned pumping patterns and schedules. The extent of hydraulic connection between aquifers must be known for other reasons, too. For example, if poor-quality water or waste were to be injected into an aquifer for storage, a hydraulic connection with another aquifer could induce contamination of the second aquifer. Because of interaquifer hydraulic con- nections, aquifers considered to be separate entities locally may actually be part of a large system when considered regionally. Much of the information base needed for planning can be provided by regional aquifer studies. Such studies have been made in most of the Lower Missis- N30 Emaar | motiraomeny | p \§ £ axel 'k\d"°n'\'o§" char PNA foam! -' Benton: A (scam 37 aao | v i 94° 3 ¥ t | | % i | | I | | 292% -_---_____L. 94° 93° o-- 3 A45J'I’)E* #s] t] \ J evinc vim” J y- imen "fr Monticello) e II "e } o'r e - g- | Hamburg N [/. fo erigyse (Uke Bestigh JN (yy sr + I 50 +20 ---- O a* Qfflx ‘y LAK Lifia ‘O 2?0 KILOMETERS 150 MILES SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES EXPLANATION POTENTIOMETRIC CONTOUR - Dashed where approximately located. Contour interval 40 feet (12 m). Datum is mean sea level. NT | Base from U.S. Geological Survey, 1965 s\ '_® | United States base map, 1965 FrGurE 22. -Areas where extensive lowering of water levels has occurred in the Sparta Sand in Arkansas and Louisiana (contours based on 1974-75 data) and in the Memphis Sand in the area of Memphis, Tenn. (contours based on 1973 data). LOWER MISSISSIPPI REGION T T T T T T 1200 | 50 percent of a conservative estimate - 1100 8000 |- of the dependable daily yield of - aquifers in the region - 1000 7000 |- 4 |- 900 6000 |- i- 800 5000 |- 4000 |- METERS PER DAY 3000 2000 GROUND-WATER USE, IN MILLION CUBIC 1000 GROUND-WATER USE, IN MILLION GALLONS PER DAY pn. 1111.4 v’.‘:‘1: -:.Z.::f--fit. 0 0 1900 1910 1920 1930 1940 1950 1960 1970 YEARS FIGURE 23.-Estimated ground-water use. sippi Region. Most of the area north of the 32d paral- lel is included in studies of the water resources of the Mississippi embayment (Cushing and others, 1963, 1964; Boswell and others, 1965, 1968; Hosman and others, 1968). The reports describe the Cretaceous, Tertiary, and Quaternary aquifer systems. Further studies by Payne (1968, 1970, 1972, 1975) describe the hydrologic significance of lithofacies of aquifers of the Claiborne Group in Arkansas, Louisiana, Mississippi, and Texas. Much of the information necessary for the development of predictive aquifer models is provided by these studies. The only major aquifer systems in the Lower Mississippi Region that have not been studied regionally are the vast coastal aquifers of Miocene, Pliocene, and Pleistocene age. A large amount of water-quality information is available in the Lower Mississippi Region, and re- gionally the water quality in the different aquifers is well known. Consideration of this information by water managers would help them in choosing a suit- able source of water. However, the quality of the water in some aquifers varies in short distances, and substantial additional testing may be necessary at these localities. Water-quality testing is also advisable in the proximity of saltwater interfaces. Monitoring networks can be used to detect anticipated water- quality changes, such as an advancing saltwater front, before the change affects the pumping center. Information on water quality will become increasingly important as concerned management organizations seek measures to conserve and protect the resource. N31 In addition to the regional aquifer studies men- tioned previously, local ground-water studies have been, and are being, made throughout the region. The areas investigated range in size from a few square miles to one or more counties (or parishes) or a river basin. Most of these studies are conducted by the Geological Survey in cooperation with State agencies. Reports based on these studies, plus abundant data in Geological Survey and State agency files, represent a sizable background of ground-water information for the region. Additional investigations should be under- taken in areas within the region where information is insufficient, especially where only reconnaissance studies or basic data are available (fig. 18). These in- vestigations should provide information concerning aquifer properties sufficient for the development of predictive aquifer models. USE MODERN TECHNOLOGY In the past, ground-water technology was almost entirely oriented toward locating and developing supplies of potable water. Little attention was given to the possible consequences of such developments. As the science evolved, techniques were developed (and are still being developed) that meant to our ground- water resource and its users what reforestation technology meant to our timberlands and the lumber industry. With proper use and coordination of these techniques and the continued development of new techniques, benefits from use of ground water will ap- proach a maximum, and our ground-water resource will be protected for future users. AQUIFER MODELING Aquifer models are the best-available predictive tool for ground-water planners and managers. Among the early models was the analog type: using a network of resistors and capacitors to simulate hydraulic prop- erties, it simulated electrically the effects of pumping stresses on an aquifer. The early analog model was the predecessor of the digital model. Construction of the digital model has been made possible by the sophistication of the digital computer and the de- velopment of numerical methods for the solution of the equations of ground-water flow. Use of the digital model requires adequate knowledge of the physical and hydraulic properties of the aquifers, pumping in- formation, and a history of water-level fluctuation for calibration of the model. After the model has been cal- ibrated to reproduce verifiable results, the planner and manager can use it to predict the effect of pro- posed development upon the ground-water system. Models can also be used to predict the movement of a saltwater front or fluids injected into the aquifer. N32 Aquifer modeling is still in a relatively early stage of development, and the degree of sophistication of the technology is steadily increasing. Within the Lower Mississippi Region, four ground-- water studies that utilized either analog or digital modeling techniques have been completed. Two addi- tional studies are currently underway. Each of these studies was, or is being, conducted by the Geological Survey in cooperation with another Federal, or a State, agency. Two of the completed studies used only analog models. One of these completed studies pre- dicted the effects that the imposition of navigation structures on the Arkansas River would have on the ground-water regime (Bedinger, 1970), and the other simulated water-level declines in the Sparta Sand in the Mississippi embayment (Reed, 1972). Two of the completed studies used only digital models. In the Ruston, La., area a digital model was used to predict the effects of projected pumping upon water levels in the Sparta Sand (Sanford, 1973). Digital models were used to predict the effects that the construction of locks and dams on the Red River in Louisiana would have upon ground-water levels in the Red River allu- vial aquifer (A. H. Ludwig, oral comm., 1976). One of the ongoing studies will model the hydrology of the Bayou Bartholomew alluvial aquifer-stream system in Arkansas. Originally, an analog model was con- structed (Broom and Reed, 1973); however, adequate controlling parameters could not be incorporated into the analysis by analog methods. Today, development of a more versatile digital model is underway. The other ongoing study will determine, with the aid of a digital model, the effects of pumping stress upon ground-water levels in the Memphis Sand in the area of Memphis, Tenn. ARTIFICIAL RECHARGE Artificial recharge may be used to augment natural recharge. It has been used to salvage excess streamflow and has also been applied to problems as- sociated with ground-water development, such as overdevelopment and subsidence. Artificial recharge is done by two basic methods: (1) impounding surface water where it can infiltrate a permeable part of the aquifer that is exposed at land surface and (2) inject- ing water into the aquifer through a well. A method that combines injection with surface- water impoundment has been tried in some areas out- side the Lower Mississippi Region, primarily in the West, with only limited success. In such experiments, playa lakes with relatively impermeable beds were used as catch basins. Wells drilled through the lake bottom and into the aquifer were intended to allow SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES evaporation to drain by gravity into the aquifer. Prob- lems with well plugging, both at the intake and in the screened interval, reduced the efficiency of this - method to an unacceptable level. Whether or not this hybrid technique could be made feasible in the Lower Mississippi Region might be worth investigating. Extensive experiments in which treated surface water was injected into the Quaternary aquifer in the Grand Prairie region of Arkansas were conducted by Sniegocki and others (1963). Heavy pumping for rice irrigation had depleted the ground-water supply in the shallow aquifer, and natural recharge to the aquifer was impeded by an extensive overlying clay layer. The conclusions of the experimental study were that the costs of the extensive treatment necessary to render raw surface water suitable for injection, with- out plugging the well screen or the aquifer, are economically prohibitive with present technology. However, well injection may become feasible in the Lower Mississippi Region, either through some technological advance or by locating a compatible combination of aquifer conditions and a surface-water recharge source of such quality that the cost of treat- ment to prevent well-screen and aquifer plugging would be acceptable. At present, water spreading seems to offer the best hope for artificial recharge at places where water levels have been drawn down in the recharge area and where excess surface water is readily available. Aside from possible technical problems, a major consider- ation may be the high cost or unavailability of adequate land for water spreading. However, recharge by water spreading should be given consideration as a management option, wherever additional replenish- ment to the aquifer would be beneficial. BLENDING OF WATER The blending of waters from more than one source can enable the use of water that would require treat- ment if used by itself. The waters to be blended could come from different aquifers or from ground and sur- face sources if the waters are chemically compatible. The resulting concentration of chemical constituents in the blend will be in direct proportion to the quan- tity of each of the contributed waters. For example, a blend containing equal amounts of two types of water would have an average chemical composition of the two. Considering the types of ground water in the Lower Mississippi Region, water blending could prove to be an extremely beneficial practice. The hard, high-iron, low-chloride water in the Quaternary aquifers is plen- tiful in most of the region; however, the water gener- the accumulated water that otherwise would be lost to ally requires treatment for iron removal and soften- LOWER MISSISSIPPI REGION ing. A soft, high-chloride, low-iron water occurs at depth in most aquifers; this water generally remains unused because of the difficulty in lowering the chloride concentration to acceptable levels. A blending of these two waters would dilute the iron concentra- tion of one, the chloride concentration of the other, and produce an intermediate hardness. Blends could be designed that would require little or no treatment for most uses. Excesses in iron, chloride, and hardness represent the most common chemical-quality prob- lems with ground water in the Lower Mississippi Re- gion. Before considering a water blend, competent pro- fessional advice should be sought to determine the chemical compatibility of the different waters. CONTROL AND USE OF SALTWATER The potential for saltwater encroachment exists where withdrawals are large in the proximity of salt- water interfaces. However, if it is necessary to plan a large development of wells near an interface, tech- niques are available for maintaining a dependable supply of freshwater at the pumping center. Barrier wells, either discharge or recharge, have been the most successful means of arresting saltwater encroachment. In a discharge-well system, a line of pumping wells between the saltwater front and the pumping center intercepts the migrating saltwater and forms a low-pressure trough in the potentiometric surface beyond which the saltwater cannot pass. The water discharged by the barrier wells will become in- creasingly salty. If the saltwater cannot be used, it must be disposed of, possibly by injection into a deeper, saltwater-bearing aquifer. Recharge barrier Discharge Recharge North well well South 'e -==" ""y Land _ surface ~ Bs ~- . ~a smae -~ -~ ao mg at os R * en r os,, | a "" Original potentiometric ~ ad surface \\ / * (lexington "v? 200 MILES & \\’ ‘f‘\\46\et‘>* A 32 ~a {_ ({ Indianapoh$ Kat .S?ringfie1d |40 LJ $56 1 8 C EXPLANATION 52- - \.. Line of equal 3 A o _q € 5 W4; precipitation, -42~ * L interval 4 inches -- {q __,... OL 11:0 25m 300 4?!) MILES z as . | | | | I 1— 0 100 200 300 400 500 ° 600 KILOMETERS | 4 XLB p ils % - Et t] C_ 28° 40° FIGURE 2-Average annual precipitation in the South Atlantic-Gulf Region. SOUTH ATLANTIC-GULF REGION O5 akfert >, * lexington EXPLANATION - 1000 -«--~-- Basement rock contour Shows altitude of basement rock surface. Dashed where approx- imately located. Contour inter- val 500 and 1000 feet. Datum is mean sea level \\ az Faults 100 200 MILES | ; "J 0 100 200 KILOMETERS 90° 85° 80° FicuUrE 3.-Major structural features and depth below sea level of basement in the Coastal Plain province. 06 SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES I I 0 200 MILES {g ] 0 100 200 KILOMETERS A 85° FIGURE 4-Geologic map of the South Atlantic-Gulf Region. soUTH ATLANTIC-GULF REGION The Coastal Plain province is underlain by unconsoli- dated clay, sand, and gravel and consolidated or semi- consolidated limestone. The deposits, which range in age from Cretaceous to Holocene, form a hugh are extending from southern Virginia through the Carolinas, Georgia, Alabama, and into eastern Mississippi (fig. 4). From a thin edge at the Fall line, most of the deposits thicken seaward; a southward projection forms the peninsula of Florida. In most places, the Coastal Plain beds have a gentle dip seaward. Each formation was generally overlapped by the next younger formation and their eroded edges are now exposed in a succession of older (inland) to younger (seaward) arcuate belts. The surface exposures of some formations are irregular. For instance, in north- ern North Carolina the inner edges of older strata were beveled by the advancing seas, and younger formations extend to the Fall Line. The Coastal Plain formations are rarely uniform lat- erally (along the strike) or downdip. Nearshore sandy EXPLANATION SEDIMENTARY ROCKS QUATERNARY HOLOCENE AND PLEISTOCENE UPPER TERTIARY PLIOCENE AND MIOCENE LOWER TERTIARY OLIGOCENE, EOCENE, AND PALEOCENE CRETACEOUS JURASSIC AND TRIASSIC INTRUSIVE ROCKS PALEOZOIC - Chiefly granitic - rocks UPPER PALEOZOIC PERMIAN, PENNSYLVANIAN, AND MISSISSIPPIAN LOWER PALEOZOIC ORDOVICIAN AND CAMBRIAN i YOUNGER PRECAMBRIAN In southeastern United States includes metamorphosed Paleozoic OLDER PRECAMBRIAN Metamorphic and igneous rocks FIGURE 4.-Continued. 07 deltaic continental sediments thicken downdip and grade into deeper water silty or limy marine deposits. Lat- erally, sediments may also change in proportions of sand and clay, or may become limy. Sandy terrace deposits were superimposed upon the older formations throughout the Atlantic and Gulf Coastal regions during the Pleistocene Epoch. Table 1 shows the stratigraphic units and aquifers of Cretaceous to Quaternary age that underlie the Coastal Plain province. The Blue Ridge province is underlain by igneous and metamorphic rocks of older age which have been sub- jected to repeated stress. The provinces outside the Coastal Plain are underlain by consolidated sedimentary rocks. In the Valley and Ridge province, these rocks have been greatly folded and faulted. In the adjacent Cumberland Plateau section the rocks have been subjected to less folding and faulting. GROUND-WATER SUPPLIES Most of the South Atlantic-Gulf Region is underlain by aquifers that are generally capable of yielding to wells 50 gal/min or more of water containing less than 1,000 milligrams per liter (mg/L) of dissolved solids (fig. 5 and table 1). Lower yields are characteristic of aquifers in the consolidated rocks that underlie the Blue Ridge, Val- ley and Ridge, and Piedmont provinces. In the Pied- mont, Blue Ridge, Valley and Ridge provinces, and the Cumberland Plateau section, wells may intersect open- ings that result from structural deformation and solu- tion, and yields range from substantial to meager. The most prolific sources of ground water in the South Atlantic-Gulf Region are the highly permeable clastic and limestone aquifers in the Coastal Plain province. In small areas in western Alabama, eastern Mississippi, southeastern North Carolina, and northeastern South Carolina, these aquifers contain only saline water. The aquifers occurring within each physiographic province in the South Atlantic-Gulf Region generally are not separate units operating independently; rather, each is a part of a complex system. Because of this interre- lation, it is generally irrelevant to estimate quantities of water that are available from the individual aquifers. It is more meaningful to estimate the quantity available from the entire system. Because the base flow of streams is supported almost entirely by ground-water outflow, the quantity of ground water available can be estimated by separating the total amount of streamflow from a region into its component parts-overland flow and base flow. The base-flow com- ponent is the approximate yield of the ground-water res- ervoirs under the existing hydrologic conditions. 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M90 s m aussooreg shay 1epag g m B ausso3 1om07 o 4 5. €. Ea & M m ausso3 o is 3 uonewnog ureuno 4009 B § s vonewsog youesg &&] uonewog youesg sApooy | 5, & susso3 ¢ & ¢ & 8 8 Aeq oozej | § § ooze» § $ w Aueniay Kery pay < < o a o s 92 5 & auoisowr7 $s ¢ ¢ § & § vonewmiog © b. aussobiq wasgy weag voneunoy (ued saddn) y peg sed009 oud ppr rire ri wos al 149 Aeymeseyoryg sony uonewsog sony qui mesiy pueg yoowwe sauAeg pueg yoowwep seukeg kep woumey vonews0g woumey siosusiiig aussony one 4 asieoo 204 weuu ] Lew uring Hew uorpeyg auadoiig uijdng Auewsreny pue auea0jo ajpueyueg warseayinog warsem eurpoieq yin0g ebro 1d disstsstyy seuag wasg eptol4 eweqeny pun sun arydvabyouys uing »3s»07 fo uoyn121402 parynasuady-1 I, soUTH ATLANTIC-GULF REGION 09 100 200 300 MILES | I Al 0 l 1- I I 0 300 KILOMETERS | I ‘00 200 EXPLANATION Patterned areas are underlain by aquifers_} 30° generally capable of yielding to iridi- vidual wells 50 gpm or more of water containing less than 1000 mg/L of dissolved solids (includes areas where more highly mineralized water is actually used) Unconsolidated and semi- W consolidated aquifers m Consolidated-rock aquifers Both unconsolidated and x I consolidated-rock aquifers 2 EEE E Not known to be underlain ; by aquifers that will generally yield as much as 50 gpm to . wells ho 5° FicurE 5.-Types of aquifers in the South Atlantic-Gulf Region. Many investigators of the water resources in areas within the Mid-Atlantic Region have estimated the per- centage of streamflow that is base flow, or ground-water discharge. In the Coastal Plain, base flow ranges from about 40 to 95 percent of the total streamflow; a con- servative average would be about 55 percent. In that part of the region underlain by consolidated rocks, base flow ranges from about 25 to 90 percent of the stream- flow, a conservative average being about 40 percent. Wilson and Iseri (1967) show that the total annual streamflow from the South Atlantic-Gulf Region aver- ages about 303,000 ft3/s or 196,000 Mgal/d, 60 percent of which flows into the Gulf of Mexico. However, the proportion of this streamflow that originates in the Coastal Plain as opposed to the remainder of the region was not determined. Using only 40 percent (the conser- vation average percent of streamflow that is baseflow in the consolidated rocks part of the region) and applying this figure to the entire streamflow from the region, the average total yield of ground water from the South At- lantic-Gulf Region under present hydrologic conditions is at least 78,000 Mgal/d or about 286,000 (gal/d)/mi* -the equivalent of about 6 inches of annual recharge. It is impractical and, in fact, environmentally undesirable to intercept all of this water before it is discharged into streams; however, the amount indicates the order of magnitude of ground water available as a potential resource. O10 There is also in storage in the ground-water reservoirs of the region about 600,000 billion cubic feet of water having a dissolved-solids concentration of less than 3,000 mg/L (M. I. Kaufman, oral commun., 1977). This volume of water is sufficient to cover the entire region to a depth of about 80 feet; however, much of this water cannot be withdrawn economically using present tech- niques. Moreover, the environmental effects of removing excessive amounts of ground water from storage may not be acceptable. The hydrologic properties of an aquifer provide a means of measuring or predicting the aquifer's water- supply potential. In this regional appraisal of ground- water resources, data are not available covering the re- gional variation in physical properties and hydrologic characteristics, and instead ranges or averages for hy- draulic properties are used. Terms used to describe hy- draulic characteristics in this study include the following: Transmissivity.-The rate at which water is trans- mitted through a unit width of an aquifer under a unit hydraulic gradient. Depends on the hy- draulic conductivity and thickness of the aquifer. Expressed in units of square feet per day (ft*/d). Hydraulic conductivity.-The volume of water that will move in unit time under a unit hydraulic gra- dient through a unit area measured at right an- gles to the direction of flow. Expressed in units of feet per day (ft/d). Storage coefficient.-The volume of water that an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head-dimensionless. The values of transmissivity and hydraulic conductiv- ity as defined above expressed in square feet per day and feet per day may be converted to units of transmissibility (gallons per day per foot) and permeability (gallons per day per square foot) by multiplying by 7.48. Explana- tions of the derivation and application of values for hy- drologic properties are given by Lohman (1972). PRESENT AND PROJECTED GROUND-WATER USE The withdrawal of fresh and saline water for all uses from all sources in the South Atlantic-Gulf Region in 1975 was reported to be 43,000 Mgal/d. Surface water accounted for 38,000 Mgal/d or about 88 percent of the total, and ground water accounted for 12 percent. Con- sumptive use was 3,700 Mgal/d (Murray and Reeves, 1977, table 17). Ground-water withdrawals in the region for all pur- poses in 1975 totaled about 5,500 Mgal/d (Murray and SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES Reeves, 1977). The largest withdrawal, 1,953 Mgal/d, was for self-supplied industrial use. Public water sup- plies accounted for 1,500 Mgal/d, and rural and live- stock, 660 Mgal/d. About 53 Mgal/d or 1 percent of the total was saline ground water used by self-supplied in- dustries. Included in the total is 1,500,000 acre-ft of water withdrawn for irrigation (about 1,340 Mgal/d on an annual basis). Ground water supplies about 48 percent of all water used for public supplies and 42 percent of all irrigation water in the region. The total of ground-water with- drawal is only about 7 percent of the estimated 78,000 Mgal/d available from the region. . Projections for future water needs made by the Water Resources Council (1968, table 1-2) are shown in the fol- lowing table: Projected water requirements, South Atlantic-Gulf Region [Million gallons daily. From U.S. Water Resources Council, 1968] Withdrawals, surface and ground water Consumptive use 1980 3,395 2000 5,655 2020 8,265 1980 53,180 2000 87,440 2020 130,190 Assuming that ground water continues to supply 14 percent of all water withdrawn in the region, projected ground-water use would be as shown in the following table: Projected ground-water requirements based on the 1970 rate [Million gallons daily] Projected withdrawals Projected consumptive use 1980 7,445 2000 12,242 2020 18,227 1980 475 2000 792 2020 1,157 If one-fourth, or about 19,000 Mgal/d, of the esti- mated available ground-water supply can be withdrawn without serious environmental effects, the projected re- gional ground-water needs through 2020 can be met. Large-capacity wells can be constructed in perhaps 40 percent of the region (fig. 5); hence, most of the ground- water development in the region will probably be in the most favorable area. GROUND-WATER QUALITY In the South Atlantic-Gulf Region good-quality ground water is generally taken for granted. In most of the re- gion enough water of good quality is available for current requirements; however, simple treatment for excessive iron, corrosiveness, and hardness is common. In this report the following classification is used for water hardness in terms of the amount of calcium car- bonate (or its equivalent) that it contains: sOUTH ATLANTIC-GULF REGION [Values in milligrams per liter] 0-60 Soft. came Moderately hard. 121-180 Hard. More than zoo ==-- Very hard. In the sandy coastal plain formations there is normally a progressive increase in the mineral content of ground water downdip. Along the outcrop of the aquifers the water is low in mineral content but may be somewhat corrosive, and water from many wells is high in iron. The high chloride concentrations in water in some Up- per Cretaceous aquifers appear to be related to the permeability of the sediments. In places, saltwater has been replaced by freshwater that has moved farther downdip in high permeable sediments than in the shal- lower but less permeable sediments. The movement of water is slower in less permeable sediments. Freshwater contains less than 1,000 mg/L of dis- solved solids; however, some water supplies use water that has a dissolved-solids concentration higher than 1,000 mg/L, and some water containing up to 2,000 mg/ L is suitable for irrigating some crops. In this report sa- line water is classified as follows according to the dis- solved-solids concentration: Dissolved solids mg/L) Less than 1,000. 1,000 to 8,000. Moderately Saline----------------------------- 3,000 to 10,000. Very Salifie ----------------------------------1 10,090 to 35,000. BING eccen- More than 35,000. Description Fresh Slightly saline------ The younger Tertiary aquifers contain freshwater that extends to or even beyond the coast in most areas (Hath- away and others, 1976). In much of the coastal area the Tertiary limestone aquifer is protected from seawater intrusion by a cover of Miocene clays and marls of low permeability. However, deep saline water has migrated into the freshwater zone in a few places in response to sharp lowering of pressure. The Pleistocene and Holocene unconsolidated sedi- ments commonly yield slightly acidic water that is low in dissolved solids. Colored ground water occurs in a few places in Florida where turbid stream waters can move into the aquifers. In Mississippi, some Eocene aquifers yield colored water in their downdip extensions. Outside the Coastal Plain, water is generally limited in quantity but of good quality. As the depth of ground- water occurrence commonly does not exceed a few hundred feet and the aquifers have long been free of sea- water, the high salinity that is common in the deep zones of the Coastal Plain aquifers is not a problem. The aqui- fer materials with the exception of the carbonate rocks are relatively insoluble, and therefore the dissolved-sol- ids concentration in the ground water is low. Q11 In moving downdip, the slightly acidic water becomes neutralized, iron content decreases, and the hardness of water increases. Because of ion exchange at greater depth, the water becomes a soft sodium bicarbonate type (Cederstrom, 1957, p. 36). Still farther downdip the water becomes saline owing to the presence of seawater with which the formations were once saturated. A similar progression is seen in water in some lime- stone aquifers. In those aquifers water may be initially harder than that in sandy formations, but hardness does not everywhere become excessive downdip owing to base-exchange action. Stringfield (1966) notes that al- though raw water for public supplies in Florida ranges up to 1,000 mg/L of hardness, only 9 percent of those supplies has a hardness greater than above 250 mg/L. Bicarbonate, however, may increase above 300 mg/L. Low bicarbonate concentrations may be related to rapid recharge through sinkholes and solution openings by water having a low carbon dioxide concentration, whereas high bicarbonate concentrations may be ex- pected where recharge water is high in carbon dioxide as a result of percolation through soil that is rich in or- ganic matter (Trainer and Heath, 1976). Although the quality of ground water in the Coastal Plain is generally good, contamination problems exist or may develop in certain areas. In most places ground water does not receive the amount of contamination that streams do. Surface contaminants tend to be degraded, diluted, and filtered before reaching the aquifer. Water moving miles downdip through sandy aquifers is almost everywhere free of organic contamination. Ground water can be degraded, however. Heavy ap- plication of fertilizers, a concentration of septic tanks, sanitary landfills, or feed lots are sources of organic con- taminants that may pollute both ground water and streams. In some industrial areas, heavy metals or nondegrad- able contaminants may be present in waste water enter- ing the ground-water reservoir. These are not filtered out by movement through sandy beds. Limestone terranes that are not protected by a thick sandy or silty soil cover are particularly susceptible to contamination from the surface. Although such water may be diluted, no filtering action occurs, and contami- nants may persist for miles. GROUND WATER IN THE COASTAL PLAIN PROVINCE Except in the Florida Peninsula, the Coastal Plain strata are generally present as a series of overlapping beds that dip gently seaward. The exposed inland out- crop areas absorb rainfall that moves downgradient, or- dinarily seaward. Water accumulates in interfluve areas 012 and moves slowly to the streams in response to gravity. In such areas, water occurs under unconfined (water-ta- ble) conditions. Downdip the water is confined within the aquifer by permeable overlying material, such as clay, and is under pressure from the water filling the aquifer back to the outcrop area. Water will rise in wells drilled in such an aquifer, and the water occurs under confined (artesian) conditions. This simple explanation suits the confined systems as a whole and is applicable without notable qualifications throughout the Coastal Plain. In much of the Florida Peninsula and in some smaller areas, recharge is local rather than at "inland" exposures of the formations. A part of the potential recharge water in the outcrop area of the formations is rejected and becomes part of the sreamflows. Part of the water entering these strata, however, moves downdip into the confined parts of the aquifers. Some of the recharge that is not discharged as base flow to streams in the outcrop area leaks upward through confining beds downgradient from the outcrop area (Siple, 19676). Numerous aquifers are present in the Coastal Plain province of the South Atlantic-Gulf Region. They vary in areal distribution and extent, and some differ in name from one State to another even though they are lateral equivalents (table 1). Perhaps the most prolific aquifer is the Tertiary limestone aquifer which crops out or is near the surface in Florida, southern Alabama, central Georgia, and southeastern South Carolina and is made up of Paleocene to Miocene limy formations that function as one aquifer. The sand aquifers in the Tuscaloosa Group and correlative units of Cretaceous age crop out generally along the Fall Line and extend seaward be- neath the younger formations from North Carolina to Mississippi. In the Western part of the region the thick permeable sand beds of the Miocene Series form an ex- tensive aquifer system. CRETACEOUS AQUIFERS The Cretaceous deposits of the region have an outcrop area of about 40,000 mi from Mississippi to Virginia (fig. 4) and extend seaward under a cover of younger sed- iments. Although the downdip limit of freshwater (water containing less than 1,000 mg/L dissolved solids) in the Cretaceous aquifers is not known in parts of the region, the areal extent of freshwater in these aquifers probably exceeds 70,000 square miles. Except in North Carolina and Virginia, the Lower Cretaceous sedimentary rocks (including the aquifers) are overlapped in the subsurface and do not crop out. These rocks contain salty water in the region except in North Carolina and Virginia and in a limited area in Mis- SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES sissippi (where the quality of water is inferred from geo- physical logs). At Franklin, Isle of Wright County, Va., industrial and municipal pumpage from Lower Creta- ceous deposits has caused water-level declines over a 1,300 square-mile area that extends into North Carolina (Brown and Cosner, 1974). Yields of individual wells are as high as 2,500 gal/min in Virginia, and the aquifer is a source of large ground-water supplies in North Carolina. Upper Cretaceous formations crop out along the inner edge of the Coastal Plain from Mississippi to North Car- olina. The Tuscaloosa aquifers, which extend over 500 miles from Mississippi to North Carolina, form one of the more extensive ground-water reservoirs in the region (fig. 6). In Mississippi and southwestern Alabama the Tuscaloosa Group consists of the Coker and Gordo For- mations. In Georgia, units within the Tuscaloosa are not differentiated. The correlative units of the Tuscaloosa in North and South Carolina are the Cape Fear Formation and, in the updip areas, the overlying Mid- dendorf Formation. Yields of 1,000 gal/min from the Tuscaloosa aquifers are common, and, where the full thickness is developed, yields of 3,000 gal/min may be possible. In Mississippi and northwestern Alabama, the McShan and Eutaw Formations overlie the Tuscaloosa Group. Sand beds in these formations are fair aquifers in some areas. Above the Eutaw Formation, except in east-central Mississippi, are sand beds in the Selma Group. In north- ern Mississippi, these beds are in the Coffee Sand and the Ripley Formation. In eastern Alabama and western Georgia, the Selma includes in ascending order the Bluff- town Formation, Ripley Formation, including the Cus- seta Sand Member, and Providence Sand. These units are only fair aquifers near their outcrop, but downdip in Alabama high yields are available from combinations of these strata. In eastern Georgia, South Carolina, and North Carolina, the aquifers correlative with Selma se- quences are the Black Creek and Peedee Formations. The yields from wells in the Cretaceous aquifers will vary from place to place in each aquifer and from aquifer to aquifer. Table 2 shows the maximum reported yield from each aquifer in several counties in each State. These values do not imply that such yields can be ob- tained everywhere in the aquifer or that such yields are the maximum possible yields. The highest average transmissivities for Cretaceous aquifers are those for the Tuscaloosa Group (Formation). The Coker Formation is an extremely productive aquifer in eastern Mississippi where the highest transmissivity, 80,200 ft*/d, was reported for a well 1,857 feet deep in Noxubee County, Miss. (Newcome, 1971, p. 36). Results soOUTH ATLANTIC-GULF REGION EXPLANATION - 1000 ----- Structure contour Shows altitude of top of Tuscaloosa Group (Formation) and correlative rocks. Dashed where approximately located. Contour interval 500 and 1000 feet. Datum is mean sea level 28" 100 200 MILES | | z J 1 I I 0 100 200 KILOMETERS \ 90° 85° 80° FIGURE 6.-Outcrop area, depth below sea level to the top, and downdip limit of freshwater in the Tuscaloosa Group (Formation) and correlative rocks. O14 TABLE 2. -Maximum reported yields of wells in Upper Cretaceous aquifers, Mississippi to North Carolina -o ind i ronnie int nee l s nge 06,00 tin anglo Yield Drawdown (gal/min) Aquifer State and county rere erie t enn talin o inn in i en are nm, 0. 00; mt on tiie cane n o Alabama: Autatiqn --.-......:-...... 500 -- Coker. Barbour- 350 - Blufftown-Providence Sand. Bulloc 515 212 Gordo. Dale--- 1,400 - Ripley. Green 11,000 =. Coker. 11,000 - Gordo. 460 32 McShan. Houston -------------..... 700 - Providence Sand. Montgomery----------... 1,000 - Coker. 200 - Gordo. Pickens ------............. 640 55 Gordo. 600 38 McShan. Tuscaloosa ----..-......... 500 - Coker, Georgia: i 500 40 Blufftown-Providence Sand. 1,850 - Do. 1,230 70 Do. 656 28 Do. 870 flow Providence Sand-Clayton. 800 - Blufftown-Providence Sand. 1,000 - Providence Sand-Clayton. Mississippi: Chickasaw ----- 600 - Eutaw-McShan. 900 T5 ordo. 770 43 Eutaw-McShan. 600 - rdo. 2,300 flow Coker. 1,600 - Gordo. 1,200 57 Coker. 1,000 42 Gordo. North Carolina: Bertie -- 550 - Tuscaloosa (?). Bladen - 650 - Black Creek. 700 - Peedee. Colombus-- 500 - Do. Craven ----- -- 2,000 57 Tuscaloosa(?)-Black Creek. Duplin-----................ 700 71 Black Creek-Peedee. 750 90 Black Creek. Greene - 550 122 Tuscaloosa(?). Hertford 1,000 67 Do. Hoke---- 900 - Do. Johnston--- 300 - Do. Lenoip-................... 1,300 __ Black Creek. : 1,000 52(?) Tuscaloosa(?)-Black Creek. Martin--- 700 - Black Creek-Peedee. Onslow - 500 80 Black Creek-Peedee(?). Pender 600 40 Black Creek. Pitt--- 380 - Peedee. 1,100 - Tuscaloosa(?). Black Creek(?). 800 - Lower Cretaceous. Tuscaloosa(?)-Black Creek. -.-c-..........c - Tuscaloosa(?). 800-1,000 Do. Sampson- - Black Creek. WaYR6 720 Do. South AIK@TE:c-rcceet cel 3,300 122 Upper Cretaceous (E‘uscaloosa?) Beaufort- 100 flow Lower Black Creek-Tuscaloosa. Colleton-- 1,200 flow Black Creek(?)-Tuscaloosa. Hampton 500 flow Upper Cretaceous- Peedee-Black Creek(?). 1,200 120 Black Creek. 1,690 ms Upper Cretaceous (Tuscaloosa?) Williamsburg ------------ 1,100 - Peedee-Black Creek. 'Estimated. of about 30 tests in Cretaceous aquifers in Mississippi indicate an average transmissivity of 1,200 ft*/d for the Eutaw and McShan Formations and 6,500 ft*/d for the Gordo Formation (Newcome, 1971). Similar conditions can be expected in adjoining parts of Alabama. Siple (1960, p. 165) reported a transmissivity of 26,700 ft*/d for a well developed in his "Tuscaloosa Formation" (Cape Fear Formation) in South Carolina, a value accepted by Callahan (1964, p. 10) for use in evaluating the Tusca- loosa aquifer in Georgia and adjoining states. SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES In northeastern North Carolina transmissivities in Cretaceous aquifers range from 190 to 27,000 ft*/d (Lindskov, 1972, table 4). A reasonable value for the av- erage transmissivity is 10,000 ft*/d. In the opinion of R. C. Heath (written commun., 1977), most of the water withdrawn from the Cretaceous aquifers in North Car- olina is derived from compression of the aquifer, expan- sion of the water, and drainage of the confining beds. In northeastern South Carolina, the hydraulic conductivity averages about 30 ft/d (A. L. Zack, oral commun., 1977). Water in and near the outcrops and in the updip parts of the Cretaceous aquifers is generally low in dissolved solids, high in iron, and slightly acid (corrosive). Al- though much higher concentrations of iron have been re- ported in places in Mississippi and Alabama, 2 or 3 mg/ L is common in most areas. Downdip the water becomes neutral or slightly alkaline, and the iron content de- creases sharply. Water from some wells in North Carolina is hard, pre- sumably because recharge is by seepage down through overlying limy Miocene sediments. Samples high in bi- carbonate and low in hardness from deeper wells in the same area have presumably traveled for some distance downdip from their point of origin. In South Carolina, water from the Black Creek aquifer is characterized by low iron and high fluoride. At varying distances downdip and at depth, water in the Cretaceous aquifers is highly mineralized owing to the fact that the sediments were once saturated with sa- line waters. LOWER TERTIARY AQUIFERS TERTIARY LIMESTONE AQUIFER The Tertiary limestone aquifer, the most extensive and widely used aquifer in the South Atlantic-Gulf Re- gion, underlies an area of about 90,000 square miles which includes Florida (where it is referred to as the Floridan aquifer), southern and coastal Georgia, and ad- jacent parts of Alabama and South Carolina (fig. 7). Lo- cal names for this aquifer are given in table 1. The aqui- fer is the source of some of the largest ground-water supplies in the United States (Stringfield, 1966, p. 1). It has been commonly referred to as the "principal artesian aquifer," although in many areas it is an unconfined aqui- fer. The aquifer includes parts of several geologic units (table 1) that are principally Tertiary limestone but con- tain intercalated beds and lenses of dolomite, sand, silt, marl, and clay in which porosity and permeability differ greatly from place to place. The aquifer thickness in- creases in a seaward direction from about 50 feet in its O15 soOUTH ATLANTIC-GULF REGION 33° f Ag acl. j" z 0% ; 30°} | Q02,00 Pinoama} City % | TY | % + | L E I o 29° i + | 28° 3] EXPLANATION «- z "3 Aake $ ___ _ _< ~, % _L... % ." Sinkpoles breaching Hawthorn For- mation or younger Miocene deposits 600 4 Okeechobee Aquifer at or near the land surface $09 | Structure contours Drawn on top of aquifer; dashed ‘ where approximate. Ticks indicate | | depression. Contour interval 100 feet; datum is mean sea level Ext -L. 50 100 MILES Lo 3 spr G a "d 1 2_J | | | FicurE 7-Distribution and structure contour map of the top of the Tertiary limestone aquifer. (From Stringfield, 1966, fig. 23). 016 updip areas in Georgia to more than 2,500 feet in parts of Florida (Klein, 1971). Most of the massive limestone of Tertiary age has been removed by erosion from the Cap Fear Arch. Neverthe- less, the Tertiary limestone of North Carolina is consid- ered a hydrologic equivalent of this aquifer. The several limestone units constituting the aquifer (table 1) are principally of marine origin and generally grade into or interfinger with clastic deposits toward the continental landmass to the north from which the clasties were derived. These peripheral clastic facies are not con- sidered part of the aquifer. The aquifer is near the sur- face and in hydraulic continuity with the unconfined shal- low aquifers over an extensive area where overlying rocks of lesser permeability are perforated by innumer- able sinkholes, particularly around the Ocala Uplift (fig. 3). Elsewhere the impermeable clays of the Hawthorn Formation overlie the aquifer; however, this formation is breached in a few places, as near Parris Island and Brickyard Point, Beaufort County, South Carolina. Ground-water development is extensive, including withdrawal of hundreds of millions of gallons per day to meet the water-supply needs of numerous major cities, such as Savannah, Jacksonville, and St. Petersburg; the phosphate, pulp, paper, and allied chemical and other in- dustries; and for citrus and other crop irrigation. Throughout the area, the aquifer yields water to tens of thousands of domestic, industrial, and irrigation wells, but most of the large industrial supplies are developed in coastal areas. The wide range in hydraulic characteristics in the Ter- tiary limestone aquifer reported by Stringfield (1966, p. 101-109) is representative of an aquifer composed of sediments that range from interbedded sand and clay to cavernous limestone. The reported transmissivities range from 3,700 to 134,000 ft/d, hydraulic conductiv- ities from 35 to 334 ft/d, and storage coefficients from 0.00019 to 0.021. These values do not indicate the true potential; for example, Callahan (1964, table 4) estimated transmissivity values in Georgia as high as 268,000 ft*/d for his determinations of ground-water flow through the aquifer. Large springs having yields ranging up to hundreds of millions of gallons per day from the Tertiary limestone aquifer are numerous in Florida and Georgia. Silver Springs and Rainbow Springs in central Florida are the largest, their combined flow averaging about 1,000 Mgal/d (Rosenau and Faulkner, 1974). Well yields of 2,000 gal/min are common. Locally, yields up to 11,000 gal/min are known, and a natural flow of 20,000 gal/min is reported for a well in central Florida (Pascale, 1975). The base flow of streams is well sustained as a result of ground-water discharge through springs. SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES Under natural conditions, the aquifer contains potable water as defined by Klein (1971) to depths of more than 2,000 feet in parts of the area (fig. 8). The extent and thickness of the freshwater body is dependent upon the rainfall and the geologic and hydrologic properties of the rocks. Since the last emergence of the land from the sea, the aquifer has been flushed of seawater in most areas. In southern Florida and in places along the eastern sea- board where the potentiometric head is low, the aquifer has not been completely flushed, and the water is saline. Increases in salinity with depth are commonly abrupt im- mediately below an impermeable stratum underlying a freshwater zone. In the Georgia and South Carolina coastal plains, water at depth inland is fresh through the full thickness of the aquifer. At Savannah, Ga., the section is about 600 feet thick, but 70 percent of the water produced in that area comes from two upper zones that have a com- bined thickness of about 100 feet (McCollum and Counts, 1964). Saline water occurs in the lower part of the aquifer at Hilton Head Island, S. C., and the entire aquifer is saline in most of Beaufort County, S. C. (L. R. Hayes, oral commun., 1977). At Brunswick, Ga., the 500- to 1,000-foot zone is fresh; saline water is present from 1,000 to 1,400 feet and low chloride water occurs from 1,400 to 1,700 feet (R. L. Wait, 1965, p. 67). The freshwater in the aquifer is generally hard. In the recharge area, the water may contain less than 20 mg/ L hardness as calcium and magnesium bicarbonate, but almost everywhere downdip the hardness is generally in excess of 100 mg/L. At centers of heavy pumping, lowered head tends to induce upward flow of deeper, possibly saline, water. Many wells have been drilled through several zones of the aquifer, thereby providing direct flow paths for deeper more highly mineralized water to migrate up- ward (or laterally) and contaminate the freshwater res- ervoir. Upward movement may occur in a short time and is, therefore, the greater hazard. In southwestern Florida, the mineral content of ground water along the Peace River is high. Kaufman and Dion (1967) suggested that here deep ground water rises "along a linear zone (fault?) of greater vertical permeability." In eastern Florida, "upward leakage of highly mineralized water from deep artesian zones" is in part "along fault zones" (Klein, 1971). Saline water is moving laterally from points of vertical leakage into well fields at Brunswick, Ga. (Wait and Gregg, 1967). At Jacksonville, Fla., saline water has migrated into the lowermost zone of the Tertiary lime- stone aquifer, thus eliminating it as a source of potable water. soOUTH ATLANTIC-GULF REGION O17 LOWER TERTIARY AQUIFERS OTHER THAN THE Contamination by seawater is possible in coastal TERTIARY LIMESTONE AQUIFER areas where the overlying confining bed is breached. Seawater is presently migrating toward the Savannah The Paleocene, Eocene, and Oligocene sediments that wells from the Hilton Head Island, S.C., area (Counts | make up the lower Tertiary aquifers (exclusive of the and Donsky, 1963, p. 72); however, under existing hy- | Tertiary limestone aquifer) in the region have an outcrop draulic conditions, salt water will require many years to | area of 45,000 square miles from Mississippi to Virginia reach the center of heaving pumping. (fig. 4). They dip seaward under a cover of younger sed- I I I I I I I I EXPLANATION 1000 --- =-- =- Contour showing depth to base of potable water in the Tertiary limestone aquifer. Contour interval 250 feet. Dashed where inferred. Datum is land surface | Area where water in the Tertiary limestone aquifer contains more than 250 mg/L of chloride or more than 500 mg/L of dissolved solids 0 50 MILES 7% 0 50 KILOMETERS 5 z & I | | | | | 85° 80° FIGURE 8$-Depth to the base of potable water in the Tertiary limestone aquifer (Floridan aquifer) in Florida. O18 iments. Although the individual lower Tertiary aquifers are not as extensive areally as the Cretaceous aquifers, they are major sources of ground water where they occur in the region (table 1). The lower Tertiary aquifers include limestone beds that grade laterally into the Tertiary limestone aquifer (table 1). These strata have poor hydraulic connection with one another, and development of maximum supplies in any one place would require either several wells end- ing in different aquifers or a well screened at various levels. Without exception, water in the lower Tertiary aqui- fers is fresh in the area of outcrop and for a few tens of miles downdip, beyond which the water is saline. Maxi- mum development at present is ordinarily confined to whatever productive stratum lies nearest the surface. Additional supplies are available at greater depths in many places, but in other places the deeper beds yield only saline water. The lower Tertiary aquifers in Mississippi, Alabama, and western Georgia (table 1) are highly productive. Yields ranging up to 2,000 gal/min to individual wells are common. A well field in Tertiary limestone yielded as much as 15 Mgal/d at Ft. Gaines, Ga. (Callahan, 1964, p. 19). Well yields of 2,000 gal/min or more could be reasonably expected from efficiently constructed wells at many places in the Pascagoula River basin in Mississippi (Newcome, 1967b, p. 1). Deeper parts of some of the Tertiary aquifers in Mississippi, in areas where fresh- water extends to depths of 3,000 feet (fig. 9), remain virtually untapped and are potential sources of future water supplies. The Castle Hayne Limestone, separated from the Ter- tiary limestone aquifer by erosion across the Cape Fear Arch, is the principal source of water supplies in the coastal plain area of North Carolina. Withdrawals of water from the Castle Hayne in Beaufort County, N. C., for mining exceeded 60 Mgal/d in 1974 (North Carolina Department of Natural Resources, 1974). The lower Tertiary aquifers exhibit a very wide range in hydraulic properties. The estimated average trans- missivity for the Castle Hayne Limestone in North Car- olina is about 25,000 ft*/d (R. C. Heath, written com- mun., 1977), and the range for the lower Tertiary aquifers in South Carolina is from 350 to 13,400 ft*/d (C. A. Spiers, oral commun., 1977). Callahan (1964, p. 19) reported that transmissivities ranged from 940 to 20,000 ft*/d in Georgia. A compilation of about 110 aquifer tests made in lower Tertiary aquifers in Mississippi (Newcome, 1971) shows a range in hydraulic conductivity from near 1 to about 240 ft/d. Corresponding values for transmissivity in an aquifer 100 feet thick would be as much as 24,000 ft2/ SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES d. The average transmissivity for a 100-foot aquifer would be about 6,400 ft*/d. Values for lower Tertiary aquifers in Alabama are estimated to be about the same. UPPER TERTIARY AQUIFERS Miocene and Pliocene sediments make up the upper Tertiary aquifers in the South Atlantic-Gulf Region. These sediments crop out over an area of about 70,000 square miles from Mississippi to Virginia (fig. 4). Miocene beds are widely distributed in the region and extend from Mississippi to Virginia, although absent over the Cape Fear Arch. From Georgia to central South Carolina, Miocene limestones are significant parts of the upper Tertiary limestone aquifer. In the Florida panhandle, Alabama, and Mississippi, the Miocene beds dip toward the south and southwest and thicken rapidly. The total Miocene section is as much as 5,000 feet thick in southwestern Mississippi, but only the higher beds contain freshwater. The depth to base of freshwater in the area (fig. 9) ranges from 500 feet near the northern limit of those formations to as much as 3,000 feet near the coast and near the mouth of Pearl River in Mississippi. Units of Pliocene age overlie the Miocene deposits and are part of the freshwater hydrologic system of the Gulf Coastal area. The Citronelle Formation of Pliocene age is the source of water for many domestic and public-sup- ply wells, but most large yield wells have been drilled into the underlying Miocene aquifers where water is un- der higher artesian pressure. Practially all domestic and municipal water supplies and most industrial supplies along the Gulf Coast in western Florida, Alabama, and Mississippi are obtained from Miocene to Pliocene aquifers. Well yields commonly exceed 1,000 gal/min. At Pensacola, in western Florida, municipal wells yield 1,500 to 2,000 gal/min, and pum- page exceeded 17 Mgal/d in 1970. In the Pascagoula River basin in Mississippi, with careful programs of ex- ploration and development, individual well yields of 2,000 gal/min could become commonplace, and yields of 5,000 gal/min are not unreasonable to expect in some places (Newcome, 19676, p. 35). The upper Tertiary aquifers are characterized by high hydraulic conductivity and transmissivity values. Lind- skov (1972, table 4) reported transmissivity values rang- ing from 44 to 2,710 ft2/d for aquifers in the Yorktown Formation in North Carolina. Callahan (1964, p. 47) re- fers to transmissivities ranging from 4,540 to 66,800 ft/ d in northwestern Florida and southern Alabama and in- dicates that conditions are similar in the Atlantic Coastal area of Georgia in the Pliocene to Holocene aquifers (Callahan, 1964, p. 50). In southern Mississippi the up- per Tertiary aquifers, mostly of Miocene age, are among SOUTH ATLANTIC-GULF REGION O19 the most productive in the State. Newcome (1971) sum- | transmissivity would be 9,400 ft2/d. The largest trans- marized about 130 aquifer tests that indicated hydraulic missivity value for the Miocene aquifer system in Mis- conductivities ranging from 5 to 334 ft/d. The average | sissippi was 84,000 ft2/d at a site in Harrison County hydraulic conductivity for all tests was 94 ft/d. Assuming | (Newcome, 1971, p. 25). that the average aquifer is y. maRsHALL] /*" i*" / H 0 Walthall A r‘\s ( \ Yazoo City yA z 0 0 & Raymond ' 4 | caria sas 3 Brookhaven Lin€oLN yeu ] / @ 3%, tac} Ah!‘ 1T 5" s 5 Libe'hlr,‘ Wégnotia [7 | ao° 89° -1000------ Contour showing altitude of base of freshwater. Contour interval 500 feet. Datum is mean sea level. Dashed where approximate 100 feet thick, the average There appears to be little contamination of deep aqui- as* {+ f % voles \ sxs ar f/ \ (nwnsfufi | faa Muse 3. ne) | geottsborg, uh Fiplef u nj 0 NJ Jasper, 1 {. lcueronte? ARTOW | fl, a i & o g ord Decatur wey _. wa § / 13 1 . g *t. raye‘Emeae‘ o ~ f] d Newndn - N3 HENRY my- 1 ) 2 ey n-as ey cowBta s I; HnyBd / X f \ sencome xf m Sain ( 1 Golo raha bead x --**%, 2" :> CHILTON Talbtton % C rbore, > Springs (s, wi/ro x* 5. (Cuthbert 03415 N *" 4 &C; “LkE RANthPn\ / Meekoors FN ~ otis a 5 fr Albpay zorgqnu; : (mu—mug wo NX the -b | oBtakeiy Tia“ EARLY | Nepton | [- Goounl } | [Z | | | meer st° --- J' \x Orantordville 1‘ wa K U as . : a se" s l $" 0 100 200 300 MILES | 71 4 I I C I 0 100 200 300 KILOMETERS EXPLANATION aon won jane om ape fame 7// E W Line of abrupt change Area where saline water Area where freshwater occurs in base of freshwater occurs above freshwater only in surficial deposits FIGURE 9.-Altitude of the base of freshwater in Alabama and Mississippi. ¥ 020 fers by seawater, but contamination of the shallower aquifers that are hydraulically connected to estuarine streams probably occurs in a few places (Newcome, 1967b, p. 29). QUATERNARY AQUIFERS Pleistocene and Holocene sediments make up the Qua- ternary aquifers in the South Atlantic-Gulf Region. The sediments crop out over an area of about 40,000 square miles, primarily in the coastal area from Mississippi to Virginia (fig. 4). In the western Florida panhandle, the upper Tertiary and Quaternary units (Miocene to Holocene) constitute a large unconfined (water table) aquifer. The sand and gravel deposits are thickest to the south and west and thin to the north and east. Wells 200 to 400 feet deep, capable of producing 1,000 to 2,000 gal/min, are com- mon. The quality of the water is excellent except for the erratic occurrence of excessive iron. The aquifer is sus- ceptible to saltwater encroachment near estuaries. During the drought of 1954 to 1956, the minimum dis- charge or ground-water outflow at 10 of 15 gaging sta- tions in the Florida panhandle was 0.308 (Mgal/d)/mi?2 (Pride and Crooks, 1962, table 2, p. 34-35), equal to about 6.5 inches of precipitation. Thus, in the 6,500 square mile panhandle area, a minimum of about 2,000 Mgal/d would be available for development if the envi- ronmental effects of the withdrawals were acceptable. Deposits of Miocene to Holocene age also make up an important freshwater aquifer in southwestern Florida. The aquifer is about 130 ft thick in western Collier County, but thins eastward and wedges out toward Dade and Broward Counties. Most of the wells near the Gulf are generally less than 100 feet deep, and the municipal water-supply wells are properly spaced and discharged at low rates to prevent saltwater encroachment (MeCoy, 1962). Wells inland yield up to 1,300 gal/min. The quality of the water is good except for a high iron content. The highly productive Biscayne aquifer, predomi- nantly highly permeable limestone of Quaternary age, is the most important source of freshwater for populous southeastern Florida, including the Miami area (Parker and others, 1955). The aquifer underlies about 3,000 square miles of Dade, Broward, and parts of Palm Beach Counties. It is as much as 400 feet thick along the shore- line, but is more commonly less than 200 feet thick and thins to a featheredge 40 miles to the west. It is esti- mated that about two-thirds of the 60 inches annual rain- fall infiltrates the zone of saturation in Dade County (Parker and others, 1955, p. 221). Well yields commonly exceed 2,000 gal/min (Pascale, 1975). An estimated 120 billion gallons of water was pumped from a 600 mi? area in the coastal ridge in 1965, of which 22 billion gallons was consumptive use. Al- SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES though copious supplies are available, one of the factors limiting withdrawals is the susceptibility of the aquifer to saltwater encroachment from the ocean and from tidal canals. Prior to the 1930's, little attention was paid to the det- rimental effects of the tidal canals; however, water man- agement practices initiated in 1945 have effectively sta- bilized the saltwater instrusion. These are (1) the importation of freshwater through canals to maintain higher water levels, (2) the construction of salinity-bar- rier dams in tidal canals to prevent the intrusion of salty water and furnish additional water to infiltrate into the aquifer, and (3) the shifting of pumping to new well fields to the west. North of Palm Beach County, a shallow sand aquifer extends along most of the coastal area. In Duval County, more than 40,000 wells produce 10 to 25 Mgal/d (Fair- child, 1972) from a shallow aquifer system consisting of Miocene to Holocene deposits. The coastal aquifers in the Quaternary deposits (fig. 4) generally yield only small supplies to wells. They are relatively low in permeability, and the storage capacity at any one place usually is small; however, these aquifers absorb rainfall readily, and in many areas they are a per- ennial source of small water supplies and recharge to streams and underlying aquifers. Where Quaternary aquifers are extensive in humid areas, both storage and recharge potential are favorable. At Elizabeth City, N. C., for instance, 14 shallow wells yield a total of 450 gal/min-more than half the city sup- ply (R. C. Heath, oral commun. Nov. 30, 1972). The greater cost in such developments may be the cost of land and pipelines rather than that of the wells. Along some of the larger rivers in the region, alluvium as much as 75 feet thick may yield up to 1,000 gal/min. Sustained yields of this magnitude should not be expected except where wells are properly spaced and recharge conditions are favorable. Data on hydraulic characteristics of the Quaternary deposits are limited because few aquifer tests have been made. Large wells in Quaternary aquifers are not com- mon because of limited available drawdown, and in many localities, the water requires treatment for most uses. A noteworthy exception is the Biscayne aquifer, the ma- jor source of water supplies in southeastern Florida. Par- ker and others (1955, p. 2) reported that the Biscayne is among the most permeable aquifers investigated by the Geological Survey. Transmissivities for the aquifer range from 400,000 to 2,670,000 ft*/d, and the aver- age is 670,000 ft*/d. The average storage coefficient is 0.20. A reasonable value for transmissivity of Quater- nary deposits in North Carolina is about 750 ft2/d (R. C. Heath, written commun., 1977). Transmissivity values for Quaternary aquifers in South Carolina range from soOUTH ATLANTIC-GULF REGION 850 to 2,000 ft*/d (C. A. Spiers, oral commun., 1977), and Callahan (1964, p. 50) estimated that values could be as large as 66,800 ft*/d in the Pliocene to Holocene section in Georgia. The chief value of the Quaternary deposits in the hy- drologic system is their function of absorbing and storing large volumes of precipitation for gradual release to un- derlying aquifers and to streams. GROUND WATER IN THE PIEDMONT PROVINCE In describing the occurrence of ground water in the Piedmont and Blue Ridge provinces, LeGrand (1967, p. 8) states The water table, representing the top of the reservoir, generally lies in the clay, or disintegrated rock materials. In the lower part of the reservoir, water occurs in interconnecting fractures in bedrock; the fractures diminish in number and size with increasing depth. Water enters the fractures by seeping through the overlying clay, and drilled wells draw water from these fractures. The source of this water is pre- cipitation in the general area of a well and not in some remote place. Minor valleys generally mark zones of fracture and, in places, fault zones, and yields are significantly higher there than elsewhere (Baker, 1957). The majority of wells in the Piedmont, however, are located for conven- ience on high ground, commonly under the community water tank. These wells nearly always are low yielding; consequently, the Piedmont is considered an area where well yields are low (fig. 5). LeGrand (1967, p. 9) stated that 90 percent of all ground water in the area occurs in the first 100 feet be- low the water table and that generally two wells 200 feet deep each will yield more water than one well 400 feet deep. Yields of up to 500 gal/min have been reported from wells in crystalline rocks (Johnson and others, 1968), but many deep wells yield less than 75 gal/min. The source of recharge in the Piedmont is the precip- itation that saturates the saprolite (weathered rock) that overlies unweathered rock. Where the saprolite cover is thick or sandy, wells will have the better yields. A well in crystalline rocks ordinarily draws water from a limited area in the general vicinity of the well, and fissure zones supplying water to the well are commonly limited in ex- tent. Wells must be widely spaced in order to avoid mu- tual interference, and successive wells located along the same rock lineament will create more mutual interfer- ence than if successive wells are located at right angles to the "grain" of a rock mass. Wells near a stream may have significantly higher yields than wells distant from such a source of recharge. The 7-day, 2-year low flow in Pickens County, S.C.. ranges from 0.3 to 0.7 (Mgal/d)/mi* (Johnson and others, 1968). This measurement of ground-water discharge to the stream, at the time of low hydraulic gradients, in- 021 dicates that the average annual recharge is at least 6.3 to 17.5 inches. An example of ground-water development in the Pied- mont province is at Tega Cay, S. C., where 22 wells av- eraging 580 feet in depth were drilled to provide water for a resort (McCall, 1972). The well sites were located on the basis of a careful evaluation of geology and hy- drology. Yields ranged from less than 10 gal/min to 370 gal/min and averaged 109 gal/min. From this group, 14 wells yielding an average of 160 gal/min were selected as supply wells. Most of the water is obtained from below a depth of 450 feet. This well field is on a peninsula jut- ting into Lake Wylie, a possible source of recharge that may have been a factor in the high yields obtained even though the path to the wells was circuitous and the source of recharge somewhat distant. Tests for coliform bacteria in the well waters were negative, suggesting that if the lake is a source of much of the recharge, slow filtration through the fine-grained saprolite has been highly effective in removing the bacteria. However, in areas where the saprolite cover is thin, filtration of sur- face-water seepage would not be very effective. GROUND WATER IN THE VALLEY AND RIDGE PROVINCE AND CUMBERLAND PLATEAU SECTION A small part of the study area lies within the folded Appalachians, largely that area in Alabama and Georgia drained by the headwaters of the Coosa River. The un- derlying rocks are Paleozoic limestone, dolomite, sand- stone, and shale, mostly overlain by a mantle of residual material. In the Valley and Ridge province (fig. 1), the rocks are not only crumpled by compressive stresses but are broken into several huge segments, some of which have slid over the more stable masses. Lesser displace- ments occur along high-angle faults. The Paleozoic rocks of the Cumberland Plateau section, adjacent to the Val- ley and Ridge province on the northwest, are gently warped. Synclines (downwarps of rock strata) may be thought of as favorable locations for ground-water development in the sense that water funnels into troughs, but cireu- lation is poor due to the compression of fractures in deep synelinal troughs and the water may be of inferior qual- ity. Anticlines (upwarps), on the other hand, tend to crack the rock into open fractures along their crests dur- ing folding and are favorable recharge areas. In this area of large-scale deformation, the more brit, tle rocks were shattered and sheared; subsequently, dis- solution by percolating water enlarged the fractures in limestone and dolomite (the carbonate rocks). Fractures in sandstone, unless calcareous, are not enlarged by later solution. True (noncaleareous) shales, initially poor aqui- 022 fers, scarcely improve in water-bearing character as a result of deformation and later dissolution. The hydrology of shattered consolidated rocks is greatly different from that of the unconsolidated sandy formations. In shattered limestone, water can move nearly as fast as through a pipe, and in both fractured limestone and sandstone filtering action is lacking. The cone of depression around a well in a highly fractured rock mass enlarges quickly, and water may move rapidly to a well from long distances. Stored water in the car- bonate rocks may be that filling an open cavern, an in- terconnected series of smaller openings, or in the uncon- solidated materials overlying the limestone that is hydraulically connected to water in the caverns. Al- though the rate of recharge in a carbonate rock terrane overlain by a clay mantle may be low, water can flow rapidly to a well from a large surrounding area and high yields with small drawdowns are possible. In Talladega County, Ala., the Cambrian dolomites are highly productive (Causey, 1965). One well yields 1,100 gal/min with 27 feet of drawdown and has been pumped at 1,600 gal/min. A well in Precambrian(?) mar- ble yields 900 gal/min with 72 feet of drawdown. Cressler (1970) notes that in northwestern Georgia, 1,000 gal/min should be available in many places from properly located wells. Near Huntsville, Ala., just north of this report area in the Cumberland Plateau section, a recently completed well 160 feet deep yielded 2,900 gal/min with 20 feet of drawdown (W. J. Powell, oral commun., March 1, 1972). In Calhoun County, Ala., a 95-foot well in Cambrian dolomite yielded 257 gal/min with only 1.6 ft of draw- down; whereas, a 550-foot well yielded about as much with 15 feet of drawdown (Warman and Causey, 1962). It is entirely possible that drilling to 400 or 500 feet in strongly deformed areas may intersect a low-or high-an- gle fault from which large quantities of water may be obtained; therefore, it seems likely that deep drilling is desirable where maximum production is sought. Drilling in the most convenient locations relative to points of use can easily result in failure; whereas, sites a mile or a few miles distant that are selected on the basis of structural control may provide ample water at very low cost. It is probable that the ground-water potential of the Valley and Ridge province is generally underrated, al- though many examples are known of failures to develop productive wells. GROUND WATER IN THE BLUE RIDGE PROVINCE In the rugged Blue Ridge province weathered rock cover (residuum) is commonly thin or absent except in valleys. Ground water generally occurs in residuum or alluvium and in fractures in the underlying igneous and SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES metamorphic rocks. Small water supplies are available from the springs that drain the fracture systems and re- siduum. Well yields depend on the number and degree of interconnection of fractures penetrated by the well but commonly are only a few gallons per minute. Where all the available water is stored in fractures, the yield di- minishes as stored water is pumped and the water level declines. LeGrand (1967) determined that wells are more productive and have a more stable yield where there is a thick mantle of residuum and that most interconnected fractures occur no deeper than 150 feet below the sur- face. Few wells produce significant quantities of water from depths greater than 300 feet. Ground water in the province is generally of good qual- ity. The dissolved-solids concentration is very low, and the principal quality problems are excessive iron and ac- idity (low pH). Aquifers in rock fractures are subject to contamination, however, in areas where the residuum is too thin to be an effective filter. SALINE-WATER RESOURCES Vast quantities of saline water are available in the South Atlantic-Gulf Region. This saline-water resource is mostly in aquifers in the unconsolidated rocks that un- derlie the Coastal Plain above the Paloezoic "basement" rocks to depths that approach 20,000 feet in southern Florida and southwestern Mississippi. All permeable de- posits below the deepest freshwater (fig. 9) are saturated with saline water, some of which has a much higher dissolved-solids concentration than seawater. Some of the dissolved minerals are of economic value; however, the most likely reason for immediate devel- opment will be utilization of slightly saline and moder- ately saline water. Some water containing up to about 2,000 mg/L of dissolved solids can be used for irrigation. Slightly saline water can be blended with freshwater to augment ground-water supplies for public and industrial uses. Desalting operations for public water supplies and other uses are more economical where the raw water has a low concentration of dissolved solids. Saline aquifers offer reservoir space for injection and temporary storage of freshwater. The N orfolk, Va., in- jection project demonstrated that only 15 percent of the injected water was not potable upon recovery (Brown and Silvey, 1977, p. 51). Injection and storage could be used to provide a supplemental source of water to meet peak demands or as an emergency source. DEVELOPMENT AND MANAGEMENT OF GROUND-WATER RESOURCES OBJECTIVES The manager has the responsibility of examining the alternatives for developing sources of supply; that is, a soOUTH ATLANTIC-GULF REGION ground-water supply based on conventional development and management procedures as against supplies based on unconventional technologies. The planner is necessar- ily responsive to public expression regarding acceptable types of development and to the economic and social aims and interests of the particular States concerned. One of the major considerations confronting both manager and planner is the effect of ground-water development on the environment, particularly if a drastic lowering of water levels or large reduction in streamflow is involved. Where these constraints take precedence, dollar costs will be of minor significance in reaching final decisions. In dealing with total available supply, ground water is not an entity separate from surface water. Much of the ground water that is not lost by evapotranspiration be- comes the base flow of streams. Capture by wells of ground water moving toward a stream or induced infil- tration of streamflow is highly desirable in many places but does not increase the total water supply. The in- crease in the ground-water supply is balanced by de- crease in streamflow. Where there is salvage of evapotranspiration loss, that salvage is an addition to the total water supply available for man's use; however, the effects on the environment must be considered. Reuse of water, the use of treated sewage effluent, or the use of poor-quality water for cool- ing or other purposes will conserve the total available supply. Use of ground water that would otherwise dis- charge into saline estuaries is an addition to the total supply in most situations. The above mentioned management techniques are in- tended to show that the total available supply can be in- creased by utilizing aquifer storage during the low streamflow months and making up the resultant under- ground reservoir deficiency by capture of streamflow during the high-flow period. Although the value of conventional approaches to many problems is granted (wider spacing of wells, for instance), emphasis here is placed on procedures that are not generally in use in the region but which have been demonstrated to be effective in other areas. Objections to any of the suggested management procedures may be based on costs; however, alternate sources would also be expensive. NATURAL RECHARGE The overland and ground-water runoff in the south- eastern Coastal Plain is about one-third the total rainfall, roughly 15 inches, and the remainder is assigned to eva- potranspiration loss and ground-water recharge (Pierce, 1966). Estimates of ground-water recharge have ranged from 1 to 11 inches (Callahan, 1964). Recharge of 6 inches would amount to about 0.29 (Mgal/d)/mi*. Some extreme exceptions to this generalization are 023 highly permeable localities in areas underlain by the sandy Cretaceous formations. Callahan (1964, p. 12) states that in places the Cretaceous sand aquifers may discharge to streams the equivalent of 40 inches per year. Thomson and others (1956) showed that in one place the 7-day, 2-year flow (1937-55) of streams fed by Cretaceous aquifers was about 1.04 (Mgal/d)/mi*- equivalent to about 22 inches of recharge. DEVELOPMENT OF UNCONFINED SANDY AQUIFERS Unconfined aquifers are similar to surface reservoirs in that water pumped from storage can be replenished by natural or artifical recharge. Recharge may be sea- sonal precipitation or it may be from another natural source (streams, lakes, or leakage from deeper aquifers). Overdraft, within limits, during dry periods leaves stor- age space for the surplus water available for recharge during wet periods-a condition that can be planned. During the period of high recharge, the intercepted ground-water outflow to the stream, although much greater in volume, is insignificant in relation to the total flow of moderate sized or large streams. The amount of intercepted ground-water flow to streams during low- flow periods is small because the normal ground-water contribution to the stream at that time is small. Planning the development of unconfined aquifers can involve many combinations of numbers and locations of wells and well fields relative to streams or other sources of recharge. Additional flexibility is provided by various methods of artifical recharge. In widely separated well fields the recharge that falls upon a well field in an unconfined aquifer is not the only water available to those wells. Water flows to the pump- ing wells from all directions; thus the wells draw in water replenished by recharge over many square miles. Removing water from storage in unconfined aquifers lowers the water level, thereby reducing the losses to evapotranspiration. DEVELOPMENT OF CONFINED SANDY AQUIFERS Only part of the recharge water in the outcrop area is removed by evapotranspiration, discharged as stream- flow, or intercepted by withdrawals. Some moves down- dip into the confined part of the aquifer. Applying Darcy's Law and assuming a transmissivity of 27,000 ft?/d and an average hydraulic gradient of 2.5 ft/mi, 0.5 Mgal/d will move downdip in a typical aquifer across each mile of the section. Increasing the hydraulic gradient in the confined aquifer (by establishing a cone of depression or by raising the head in the recharge area) would increase the downdip flow proportionately. Fur- ther application of Darcy's Law indicates that a 5-mile width of aquifer would transmit 10 Mgal/d if the hy- draulic gradient were increased to 10 ft/mi. 024 The transmissivity of the aquifer establishes the first constraint on ground-water development. Acceptable pumping lifts in deepening cones of depression estab- lishes the second constraint. Larger volumes of water would be made available by increasing the drawdown and the eventual extent of the cone of depression. Leak- age from aquifers above and below might occur, provid- ing additional water to that which moves laterally and diminishing the supply in the other aquifers. A tempo- rary bonus is water released from storage as a result of lowering the pressure during the water-level decline. Artificial recharge in either the unconfined or confined zones of the aquifer will increase the available water sup- ply. Where enough data are available, and through the use of analog and digital modeling, the optimum combi- nation of recharge, hydraulic gradient, and pumping lift can be planned and problems can be minimized. Certain effects on the environment, such as the poten- tial for land subsidence, should be considered when large withdrawals from confined aquifers are planned. DEVELOPMENT OF THE TERTIARY LIMESTONE AQUIFER Callahan (1964, p. 26) points out that in the Valdosta, | Ga., area the base flow of streams was relatively low in the fall of 1954, 0.014 to 0.054 ft®/s/mi? or 0.009 to 0.035 (Mgal/d)/mi?, but that much of the infiltrating rain- fall of 1.25 ft®/s/mi? (0.81 (Mgal/d)/mi?) may have moved downdip in the principal artesian aquifer rather than emerging as base flows of streams. According to H. B. Counts (oral commun., Feb. 18, 1977), in November 1972 the total flow of the Withlacoochee River, an estimated 12 Mgal/d, drained into two sinkholes and much more could have been accepted. Estimates of rates of recharge to the Tertiary lime- stone aquifer have been made by determining outflow through the aquifer (table 3) according to various pub- lished values or estimates of transmissivity and hy- draulic gradients. These are given below for the several large areas. In the Alachua-Bradford-Clay-Union County, Fla., area the recharge computation of 0.08 (Mgal/d)/mi? (ta- ble 3) is based on a transmissivity value derived from development of the upper 200 feet of the aquifer (Clark and others, 1964) in an area where the aquifer is about 1,000 feet thick. In the Green Swamp (Florida) recharge area the out- flow is limited by the cross-sectional area through which water must flow (Pride and others, 1966). Hence, al- though the transmissivity is higher in the western basin, the cross-sectional area through which discharge takes place is smaller, and the apparent recharge is smaller. It was estimated that in Hillsborough County, Fla., in the late 1950's about 100 Mgal/d entered the county SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES TABLE 3.-Recharge rates to the Tertiary limestone aquifer based on estimates of flow through the aquifer Recharge rate Equivalent Aquifer per square mile precipi- Area flow tation (mi?) (Mga¥/d) (ft/s) (Mgal/d) (in/yr) Florida: Alachua-Bradford Clay- _ 525 45 0.132 0.085 1.8 Union Counties above the 75-ft contour. Orange County ------------ _ 950 210 34 .22 4.62 Polk County: Alfia and Peace 640 163 .395 .255 5.36 Rivers-----.--....... Kissimmee River --- _ 415 151 .536 .364 7.65 Green Swamp area------ _ 870 114.8 .204 132 2.7 min 121.8 217 .140 2.9 avg. 166.2 .28 . 191 4.0 max. Western basin ------- 160 22.1 .214 138 2.9 Eastern basin-------- 208 67.4 501 324 6.8 Hillsborough County: Local -----------...-... 1,040 450 .67 482 9.1 Inflow ---------------.-- 566 100 .274 A77 8.72 from the north and east through the aquifer, but there was additional local recharge of about 0.43 (Mgal/d/mi2, equivalent to 9.1 inches of precipitation per year (Menke and others, 1961, p. 15). Results of other determinations are given in the table. Although only 0.2 to 0.5 Mgal/d of water per square mile of recharge area moves downdip at present, poten- tial production from the artesian beds in the aquifer is much greater. When gradients are increased, the flow is increased proportionally, and additional ground water that is now discharged to streams or springs would be captured. For instance, there are large springs north- west of where the Miocene deposits overlap older strata (fig. 10). These springs may represent potential re- charge to the Tertiary limestone aquifer that cannot pass southeastward under the Miocene cover and through fault zones under existing hydraulic gradients. Some or much recharge through the top of the aquifer will also be available if gradients are increased, and in some areas water from deeper sources may rise along faults. In some instances additional water would be avail- able through capture of evapotranspiration loss and from inflow from streams originating outside the area. Florida's two largest springs, Silver Springs and Rain- bow Springs, each have a ground-water drainage area of about 625 square miles underlain by a thin or broken clay cover. The average combined flow for the two springs was almost 1,000 Mgal/d in 1968 (Faulkner, 1970). Dis- charge ranged from 0.5 to 1.3 (Mgal/d)/mi? (table 4). An annual recharge rate of 10.6 to 28 inches of rainfall is thus indicated. Additional water was probably lost by evapotranspiration from the water table. Freshwater is discharged through springs from the Tertiary limestone aquifer in more than one-half (30,000 square miles) of the Florida land area. Esti- mated flow of springs cataloged by Callahan (1964) and 350 [- 33° 29° |- SOUTH ATLANTIC-GULF REGION T T 141 DXPLANATION nie Bt \ Jas y Tertiary limestone Approximate area of Miocene overlap ...... D Inferred fault [~ U,upthrown side; D, downthrown side Probable fault & | C [ - e W" (3 “h ‘ s. NS ATT 20 0 I20 40 60 MILES ] ‘ i y h “5k -~" a FIGURE 10.-Location of large springs in Georgia and northern Florida. (Modified from Callahan, 1964, figs. 5 and 7.) Z 4 as > Stringfield (1966) probably represents less than half the total discharge of all springs. With all cataloged springs considered at maximum flow, recharge is estimated to be about 0.32 (Mgal/d)/mi? or about 7 inches of rainfall. The minimum flow of cataloged springs (half the total) is equal to 82 percent of the 3,000 Mgal/d of ground water pumped in all of Florida during 1970 (Murray and Reeves, 1977). Spring discharge, like base-flow measurements, does not take into account water "lost" by underground flow downdip or by evapotranspiration. Hence, the value of 0.32 (Mgal/d)/mi? noted above is only an indication of the volumes available. Recharge to the Tertiary limestone aquifer may occur through the Miocene cover at a very low rate. The rate is dependent on the thickness, the hydraulic conductivity of the overlying stratum, and the gradients involved. For instance, a highly conservative estimate of recharge through the thick Miocene cover in the Okefenokee Swamp area is about 0.035 (Mgal/d)/mi? under maximum development (Callahan, 1964, p. 27). An extremely large volume of water is in storage in the Tertiary limestone aquifer in Florida and Georgia. Seventy thousand square miles of Florida and Georgia are underlain by water- bearing strata with thicknesses ranging from several hundred feet to a maximum of about 2,000 feet (fig. 8). In northwestern Florida a part of the aquifer thickness shown includes aquifers below the Tertiary limestone 025 TABLE 4.-Recharge rates to the Tertiary limestone aquifer based on spring discharge Flow Total per square mile Precipi- Area flow tation (mi?) (Mga¥Vd) (ft?/s) (Mga¥V/d) (in./yr) Florida Springs area----------- 30,000 2,456 0.127 0.082 1.72 min. 9,824 .5 .328 6.88 max. Silver Springs ---------------- 625 348 .862 .557 11.7 min. 581 1.314 .849 17.8 avg. 833 2.06 1.333 28 - max. Rainbow Springs--------------- 625 315 .T80 .504 10.6 min. 468 1.16 148 15.7 avg. 684 1.67 1.094 22.9 max. Northwestern Peninsular Florida above the 30-40-ft contours ------------------ 1,950 95 .0754 .0487 1.0 North Central-Peninsular Florida above the 50-60-ft CONtOURS --------------- _ 8,770 181 .0743 .048 1.0 South Central Lake District above the 70-ft contour --- _ 6,000 544 .139 .09 1.9 aquifer. In the other States the volume of water stored in the Tertiary limestone aquifer is much less but is sig- nificant. Withdrawing much of this water in storage can- not be considered today in view of undesirable environ- mental effects that would occur. Recharge to the Tertiary limestone aquifer would in- crease if water levels were lowered. About 70 percent of the 48 to more than 55 inches of rainfall in the area is lost by evapotranspiration. Where the area is riddled with sinkholes (fig. 7), it must be assumed that a high percentage of the rainfall will enter the ground and that much of it will be available to wells, either in the area of recharge or downdip in the confined part of the aquifer. The volume of water that would move downdip through the upper 500 feet of a mile-wide section of the aquifer assuming a transmissivity of 60,000 ft?/d and a hydraulic gradient of 2 ft/mi is estimated to be 0.9 Mgal/ d. If gradients were increased to 4 ft/mi and if 1,000 feet of the aquifer were penetrated, 3.6 Mgal/d would flow through each linear mile of the aquifer (taken along the strike). In any one well field of limited areal extent, how- ever, water will be drawn into that center of discharge laterally and from downdip, and "leakage" will take place through the roof and the floor. On the basis of calcula- tions of maximum recharge as derived from the flow of springs (table 4), maintaining a discharge of 3.6 Mgal/d might require as little as 3 square miles of recharge area. With lowering of the water table and capture of some evapotranspiration loss, the recharge area required would be even smaller. Maximum production of water supplies from wells will | necessarily take into account the tendency to induce a lateral flow of saline water into the well field from the sea. Also, in certain areas there is a tendency for sink- holes to occur as a result of lowering water levels. In any 026 event, monitor wells and mathematical models of the aquifer would be beneficial in understanding the behav- ior of the hydrologic system where maximum stress is approached. The Tertiary limestone aquifer is exceedingly complex and differs greatly in its physical makeup from place to place. The generalizations given here can only bring out several of the pertinent factors that must be considered. DEVELOPMENT OF AQUIFERS IN THE APPALACHIAN MOUNTAINS AND THE PIEDMONT Success in developing ground-water supplies in the part of the region outside the Coastal Plain can be en- hanced by applying scientific principles and modern tech- niques. Although many unsuccessful or low-yielding water wells are known, the ground-water potential of the upland area has probably been underrated. Numerous reports of high-yielding wells in this part of the region indicate that well-site selection based on various geologic and hydrologic criteria and exploratory techniques can result in very productive wells. It is now know that remote-sensing techniques can identify the lines of structural deformation with which many highly productive wells are associated. Remote sensing may be useful in identifying soil or vegetation types that may be useful in locating ground water. Geo- - physical techniques may help in identifying and deline- ating solution openings in carbonate rocks. Ground reconnaissance by trained personnel will im- prove the chances for locating satisfactory well sites. In a study of the occurrence of ground water in the Pied- mont and Blue Ridge provinces, LeGrand (1967) found that topography and soil thickness are good indices for siting high-yielding wells. The most favorable locations are in valleys or draws that have a thick cover of allu- vium, residuum, or weathered rock. Except in cavernous carbonate-rock aquifers, the vol- ume of ground water that is available is directly related to (1) the number, size, and depth of fracture openings and (2) the thickness and permeability of the soil cover. The soil cover, where present, is the source of recharge to the underlying fractures and also serves as a storage reservoir when saturated. Experience has shown that in many areas most interconnecting fractures occur within 150 feet of the land surface, and drilling deeper than about 300 feet is generally not justified (LeGrand, 1967, p- 0). OTHER MANAGEMENT PROCEDURES Management procedures other than those already dis- cussed may be employed where the supply of potable ground water appears to be limited. Briefly they fall un- SUMMARY APPRAISALS OF THE NATION'S GROUND-WATER RESOURCES der these major headings: (1) use of multiple sources of water, (2) use of saline water for special purposes, (3) artificial recharge, and (4) conjunctive use of ground water and surface water. MULTIPLE SOURCES OF FRESH GROUND WATER Where fairly thick sand terraces border large losing streams, an inexpensive source of ground water can be developed (Paulson and others, 1962). Assuming that the river terrace is rather wide, maximum advantage might be taken of such a shallow aquifer by pumping naturally filtered river water from wells near the river during pe- riods of high flow and by pumping from wells as far back from the river as practicable in the low-flow period. In a situation where a supply from a confined aquifer is declining, wells in the terrace deposits might be relied upon to a maximum extent in the higher rainfall months during which time the deep aquifer would be drawn upon less. In the following rather brief low-flow river period, the confined aquifer might then supply much or all of the water needed. Where wells in confined aquifers yield a reliable supply of highly mineralized water, river terrace water might be used for blending, and furthermore at times of max- imum availability, excess freshwater from the shallow aquifer might be used to recharge the confined aquifer. In most places where higher or inland terrace deposits are present, it is questionable whether those deposits would yield supplies large enough to function economi- cally in a combination system; however, there is a pos- sibility that higher inland terrace deposits may be as thick as 150 feet in some areas. The use of shallow well water as a source of municipal supply at Elizabeth City, N. C., has been noted above. In Norfolk, Va., as much as 60 gal/min has been developed from wells in terrace sands (Cederstrom, 1945). USE AND MANAGEMENT OF SALINE WATER In most places freshwater occurs in near-surface for- mations, whereas at greater depths the water is saline. Use of saline water after desalinization may relieve the draft on a freshwater aquifer. In most aquifers, particularly those that are confined, pressure head increases with depth; therefore, where the shallow freshwater stratum is drawn upon heavily, the poor-quality water at greater depth may migrate upward. Where the beds underlying the freshwater aqui- fer are silts, lenticular clays, or massive rocks riddled with solution channels or broken by faults, contamination may become a real concern. Utilization of the deeper water for special purposes, therefore, would tend to re- duce the head in the lower aquifer and minimize that con- cern as well as add to the total supply. soOUTH ATLANTIC-GULF REGION One problem of using deep poor-quality water is that hydraulic connection may be established in the borehole between the deep and shallow aquifers. Saline-water wells should, therefore, be grouted through the fresh- water strata. In special cases where contamination of the upper stra- tum has taken place, pressure-relief wells may be drilled to diminish head in the deeper stratum. This technique was attempted in Brunswick, Ga., to minimize the up- ward movement of saline water in the Tertiary limestone aquifer. However, sufficient reduction of pressure head to completely halt the upward flow of saltwater could not be effected owing to the high transmissivity of the salt- water aquifer (Harlan Counts, oral commun., Nov. 30, 1972). In many downdip localities in Alabama, Mississippi, and the Carolinas, the deeper Cretaceous aquifers yield water that is fresh, whereas the overlying formations are saline. In such places the water developer-farmer, mu- nicipality, or industrialist-must bear the cost of a well 1,000 feet or more in depth or use shallower water of inferior quality. Additionally, an obvious disadvantage is the danger of contamination of freshwater aquifer by movement of saline water from above as heavy pumping from the deeper aquifer continues. To guard against deg- radation of water in the deeper aquifer, water users should be encouraged to use the more cheaply developed inferior shallow water to the fullest extent possible in order to maintain a low-pressure head in the formation. In some areas where relatively shallow water is of in- ferior quality and freshwater is available only at consid- erable depth, nearly all users initially will develop the shallower source of inferior water. In these areas, taking advantage of normal pressure differentials (where deeper aquifers have higher heads), connector wells which would allow freshwater to move upward to dilute the saline water aquifer might be desirable. In an ideal situation a connector well would be cen- trally located with reference to several heavily pumped shallower wells or to a local supply consisting of many private wells. With maintenance of lower head in the upper formation through heavy withdrawals for air con- ditioning or other purposes not requiring the highest quality water, normal upward flow of freshwater through the connector well would be accelerated, and in time all wells in the general area might benefit from an improvement in the quality of water. Owing to normal head differences, even during periods of no pumping, flow would continue upward and outward into the shal- lower stratum, although the flow would be less than when pumps are operating. Where the deep aquifers contain saline water and there is surplus water under higher pressure in shallow aquifers, the system could be reversed, thereby storing 027 freshwater in a saline-water reservoir. In most confined aquifers there is a downdip transition from freshwater to saline water. Planners may consider measures to forestall lateral or updip movement of saline water into centers of freshwater withdrawal. An exam- ple is the situation at Montgomery, Ala., where water from both the Eutaw and Gordo Formations is of good quality (Knowles and others, 1963). West of Montgo- mery, the chloride content of water in the Eutaw For- mation increases rapidly. Flowing wells tapping the Eu- taw Formation west of Montgomery along the Alabama River lower the head of water in the Eutaw Formation and bleed off highly saline water, thereby affording a measure of long-term protection to the Montgomery sup- ply. The flowing wells discharge highly saline water (1,150, 1,330, and 1,600 mg/L chloride). Where a well field is threatened by lateral intrusion of poor-quality water, including the intrusion of seawater, artificial recharge by injection wells, connector wells, or a combination of water spreading and connector wells, might be employed to create freshwater barriers be- tween the well field and the source of contamination. ARTIFICIAL RECHARGE OF GROUND WATER Ground-water discharge accounts for a large part of streamflow; hence, development of ground-water sup- plies may not add greatly to the total available supply of water. Additional water can be made available to the system, however, by reducing losses due to evapotran- spiration, by recycling of water, and by interception of high-flow components of streamflow. Interception of high streamflow in the past has been almost entirely accom- plished by the construction of surface reservoirs. How- ever, in recent years in California the recharging of un- derground reservoirs with water pumped from distant streams is widely practiced. The practice is less common in the mid-western States and unusual in the eastern States. Methods range from collecting storm runoff in pits to constructing canals and pipelines that bring water to the recharge basins or injection wells. Difficulties attend these efforts in places, depending on type of water used, hydraulic characteristics, climatological conditions, and the methodology employed. Nevertheless, the practical- ity of artificial recharge is well established, and we may expect that, generally, technology will provide satisfac- tory answers to most problems. In the arid West, ground-water levels generally occur well below the level of ephemeral streams, and there is storage space for whatever recharge water can be made available. In the humid Southeast, however, ground- water levels generally are fairly close to the surface. Addition of water to the unconfined aquifers will be lim-