A Regional Interbasin Groundwater System in the White River Area, Southeastern Nevada

VOL. 2, NO. 2 WATER RESOURCES RESEARCH SECOND QUARTER 1966

A RegionalInterbasin Groundwater System in the WhiteRiver Area, SoutheasternNevada

THOMAS E. EAKIN

Water ResourcesDivision, U.S. GeologicalSurvey, Carson City, Nevada

Abstract. A regional interbasin groundwater system including thirteen valleys in southeastern Nevada is generally identified on the basis of preliminary appraisalsof the distribution and quantities of the estimated groundwater recharge and discharge within the region, the uniformity of dischargeof the principal springs,the compatibility of the potential hydraulic gradient with regional groundwater movement, the relative hydrologic properties of the major rock groups in the region, and, to a limited extent, the chemical character of water issuing from the principal springs. The principal findings are: (1) Paleozoic carbonate rocks are the principal means of transmitting groundwater in the interbasin regional system--the regional transmissibility provisionally is estimated to be about 200,000 gal/day/ft; (2) estimates of recharge and discharge show wide discrepanciesin individual valleys, but hydrologic balance with recharge and discharge estimates of about 100,000 acre-ft/yr obtains within the thirteen-valley region; and (3) the dischargeof the Muddy River Springs, the lowest of the three principal spring groups, is shown to be highly uniform, which is consistentwith their being supplied from a large regional groundwater system. The relation between this regional system and others in eastern and southern Nevada is now under study by the Geological Survey. (Key words: I-Iydrologie systems;hydrology (limestone); springs; groundwater)

INTRODUCTION a regional groundwater system in a part of the Basin and Range province in southeastern Reconnaissanceappraisals of the groundwater Nevada. Although the scope of the report is resourcesof various valleys in Nevada have been limited by the reconnaissancenature of the in- made for severalyears. One of the assumptions vestigationson which it is based, virtually all on which thesestudies originally were predicated componentsof the hydrologic system are eval- was the generally accepted concept that most uated. hydrologic systemswere more or less co-exten- Locationand extent o)e the reqion. The re- sive with the topographicallyclosed basins in gion discussedincludes the area within the drain- the Basin and Range province. As studies for age divides of six valleys drained by the White various areaswere completed,it becameevident River in Pleistocenetime and seven adjacent that groundwatersystems in certain valleys of but topographicallyseparated valleys. It is in eastern and southern Nevada extended beyond southeastern Nevada and lies within lat 36ø40 ' the limits of the particular valley. Somevalleys and 41ø10'N and long. 114030' and 115ø45'W. have a much larger spring dischargethan could It includesparts of Clark, Elko, Lincoln, Nye, be sustainedby local recharge,and other valleys and White Pine counties (Figure 1). From its have deep water levels that preclude an an- north end in southernElko County, the region nual groundwater dischargeby evapotranspira- extendssouthward to includethe upper Moapa tion comparable with probable local recharge. Valley, a distance of about 240 miles. Its maxi- If these observations are correct, a multivalley mum width is about 70 miles near lat 38øN. regional groundwater system is required to The regionincludes an area of about 7700 square satisfy the general hydrologic equation that inmiles. flow equals outflow. Topographic settinq. Figure 2 shows the This report describesthe general features of locationsof the principal valleys and rangesin the region.Of the thirteen valleys,Long, Jakes, • Publication authorized by the Director, U.S. Cave, Dry Lake, and Delamar valleys are Geological Survey. topographicallyclosed. Garden Valley surfici-

251 252 TI-IONIAS E. EAKIN

116ø00' • 115ø00' 114000' •. •::• / ELKOCOUNTY I

I ..:;:;:::;-:.::;-:.:.:; •

EXPLANATION r x ,

i 1. SHEEP RANGE 0 5 15 25 2. BRISTOL RANGE 3. HIGHLAND RANGE 4. EGAN RANGE Scale in Miles 5. HORSE RANGE i'P'illton 6. GRANT RANGE 7. SCHELL CREEK RANGE 8.PAHRANAGAT RANGE 9.ANTELOPE MOUNTAINS i 10.ARROW CANYON RANGE 11 .QUINN CANYON RANGE i I- 12.WHITE PINE MOUNTAINS COUNTY 13. GOLDEN GATE RANGE LINCOLN i 14.15.DELAMARPAHROC RANGERANGE (•) 16.BUTTE MOUNTAINS COUNTYi 17.MAVERICK SPRINGS RANGE 18. MEADOW VALLEY MOUNTAINS 19.WORTHINGTON MOUNTAINS 20. SEAMAN RANGE

•lamar (site)

37 • -----4

Altitude zones ,in feet above sea level; CLARKCOUNTY interval, 2000 feet

LasVeg

7O00 -- 9000

,5000 -- 7000

3000 --5000 , UPPER MOAPA '-VALLEY (3000 115•' 4,,)IScale inMiles

Fig. 1. Location of regional interbasinground- Fig. 2. General topography of the area of this water systemdescribed in this report. report. Interbasin GroundwaterSystem 253 ally may drain into Coal Valley but together on Figures4 and 6. Theseelements are discussed they form a topographically closedunit. The in the following sections. remaining six valleys were drained by the Geologic setting. The rocks provide the PleistoceneWhite River, then a tributary to the framework in which groundwater occurs and Colorado River system. The six valleys are moves. Groundwater may occur in interstitial White River, Pahroc,Pahranagat, Kane Spring, openings,in fractures,or in solutionopenings in Coyote Spring,and upper Moapa. the rocks. The openingsmay have been formed This regionof mountainsand valleys generally at the time the rocks were deposited or at a has a southward gradient (Figure 2). Along the subsequenttime by œracturing,weathering, or White River Wash the altitude decreases from solution. The distribution and nature of these about 5500 feet in the latitude of Lund to about openingsmay relate generally to other physi- 1800 feet in the vicinity of the Muddy River cal and chemical characteristics of formations Springsin a channeldistance of about 175 miles. or groupsof rocks.Thus, the generalnature and The averagegradient alongthe Wash is about 21 distribution of the rocks in the region permit feet per mile. The White River Wash forms an some inferences regardirg the occurrence and axial topographiclow between Garden and Coal movement of groundwater. valleys on the west and Cave, Dry Lake, and A number of geologicstudies in parts of the Delamar valleys on the east. area df this report have been made. For present The mountains generally are 2000 to 4000 purposes,the reconnaissancegeologic map of feet higher than the floorsof the adjacent valley Lincoln County [Tscha.nzand Pampeyan, 1961], (Figure 2). The crests of the ranges commonly the reconnaissancegeologic map of Clark County exceed 8000 feet above sea level and locally [Bowyet et al. 1958], the general geologicmap exceed10,000 feet in the north part of the area. accompanyingthe guidebookto the geology of In the south part of the area the crests of the east-central Nevada [Boettcher and Sloan, ranges exceed 8000 feet above sea level only 1960] for White Pine and parts of northeastern locally and commonly are less than 7000 feet Nye counties, and unpublished information in altitude. from F. J. Kleinhampl for segments of the region in northeastern Nye County have been TI-IE REGIOl•AL GROUI•DWATER SYSTEN[ most useful with referencelo the areal geology of the region. For the White Pine County part The regional groundwater system includes of the region many of the papers in the guide- both the rocks and the groundwater of the book to the geology of east-central Nevada fined area. It includesthe areas of rechargeand [Boettcher and Sloa.n,1960] are of much value. discharge,storage and transmissionof water, Although not known to crop out within the and geologicunits that control the occurrence area of this report, Precambrian rocks are and movement of water. Semiperchedground- posedin the northern Egan Range east of Long water in the mountains and in the valley fill of Valley, in the Schell Creek Range [Young, at least some valleys contributesto the regional 1960], along the east side of Cave Valley and systembut is not emphasizedherein. northward, and in the Mormon Mountains The identification of this regional ground- [Tschanz and Pampeyan, 1961] east of Coyote water system is based upon (1) the relative hy- Spring Valley and may be inferred to underlie drologicproperties of the major rock groups in all the region of this report. the area of consideration;(2) the regionalmove- A thick section of Paleozoic rocks was de- ment of groundwateras inferred from potential posited throughout and beyond the area. Lo- hydraulic gradients; (3) the relative distribution cally, the stratigraphicthickness of the Paleozoic and quantitiesof the estimatedrecharge and dis- rocksexceeds 30,000 feet [Kellog, 1963, p. 685]. charge; (4) the relative uniformity and long- Clastic rocks occur principally in the upper term fluctuationof the dischargeof the principal and lower parts of the section. Carbonate springs; and (5) the chemical quality of the rocks, which comprise more than half of the water dischargedfrom the principal springs. section,are generally found in the central part Much of the available data pertinent to the of the Paleozoic section. analysisis includedin Tables 1, 4, 5, and 6 and Lower Triassic marine depositsare noted by EXPLANATION

Valley fill principallyclay, silt, sand, and gravel; locally may include fresh- water limestone or evaporite;consolidated to unconsolidated. Deposited under subaerial, stream or lacustrine environments. Lower Tertiary deposits involved in deformation; upper Tertiary and Quaternarydeposits moderately deformed, locally.Sand and gravel deposited in stream channels and alluvial fans transmit water freely;fine-grained deposits, where saturated, transmit water slowly but contain a large volume of Scale in Miles water in storage

Volcanic rocks Principally volcanic tuff and welded tuff or ignimbrite, but include other volcanic rock types and Iocall• sedimentary deposits.Generallytransmits water slowly, but locally highly fractured weided tuff may yield water readily. In mountains differential transmissibility, bedding planes, or fracture systems result in semiperched ground water which supplies many small springs. Where saturated transmits water slowly but contain a large volume of water in storage

Paleozoic rocks undivided Principallylimestone anddolomite. Secondary fracture or solution openings result in transmission of substantial quantitiesofwater, atleast locally. Ingross where saturated, storeIncludealargesome volumeshale, ofsandstone, water. Principaland quartzite regional whichaquifer. generally act as a barrierto ground-watermovement. Locally,however, fracturedorweathered zones transmit some water

Fig. 3. Generalizedgeology of the region.Adapted from Bowyer et al. [1959]for Clark County;Tschanz and Pampeyan [1961] for LincolnCounty; F. Kleinhampl(private communication,1963) for partsof NyeCounty; and Boettcher and Sloan [1960] for remaining area. Interbasin Grou•.dwater System 255

EXPLANATION

Area of evapotranspiration of ground water

Playa and approximate altitude, in feet, above sea level eLundSpring (5595) '"i Data point, name, and approximate altitude of water level above sea level :? .,,es

Data point and serial number. Points described below include name or well number followed by depth to water and by altitude of water level. For oil tests, only total depth (T.D.) of well given J AlphaSShaft(6108) •. Preston:Springs(5680) 1.--Well 21N/59-18d2; 88; 6000 un•.•pring(5595) 2.--Well 21N/58-33b1; 68; 6000 3.--Well 20N/58-14a1; 117; 6000 4.--Oil test, Summit Springs Unit no. 1; T.D. 11453 5.--Illipah Creek 6.--Oil test, Hayden Creek Unit no. 1; T.D. 5117 7.--Well 14N/61-10cl; 280; 5780 8.--Ellison Creek ' 15 9.--White River 10.--Oil test, County Line Unit no. 1; T.D. 4850 11.--Emigrant Springs; 5415 HotCreek Springs (5175)• 12.--Morman Spring; 5300 13.--Butterfield and Flag Springs; 5275 14.--Well 5N/60-25a1; 25; 5100 •" • • •/ o• BristolMine 15.--Well 8N/64-30cl; 331; 5800 J ..• "." • ß .• (5•75) 16.--Well 5N/64-14a1; 214 (dry); <5385 17.--Well 3N/64-20b1; 317; 4820 18.--Well 2N/64-3b1; 684; 4350 19.--Well 1N/64-24a1; 398; 4300 20.--Well 4N/61-36cl; 90; 4970 21 .--Well 3N/62-8cl; 217; 4835 22.--Well 3N/62-35b1; 252; 4770 23.--Well 2N/63-31b1; 800 (dry); <4125 24.--Well 2S/61-23dl; 302 (dry); <3900 25.--Well 2N/59-22b1; 250 (dry); < 4775 26.--Well 4N/59-6d1; 9; 5340 : s2 27.--Well 3N/58-15b1; 235; 5040 28.--Well 3N/57-16cl; 33; 6150 29.--Well 1S/57-3al; 570; 5020 30.--Well 6S/63-12al; 900 (dry); <3700 PahranagatSp' g •Alam? a /"x 31.--Well 4S/61-1561; 670; 3700 32.--Well 5S/60-6cl; 380; 4025 33.--Well 3S/60-24dl; 187; 3815 34.--Well 4S/60-2al; 105; 3870 35.--Hiko Spring, altitude 3890 36.--Crystal Springs, altitude 3805 37.--Ash Springs, altitude 3610 38.--Upper Pahranagat Lake

39.--Maynard Lake , . , 40.--Well 10S/62-14al; 416; 2175 41.--Coyote Spring, altitude 2575 42.--Well 13SI63-25al; 330; 1875

Fig. 4. Location points of selecteddata in the area of this report.

Stokes [1960, Figure 2] near Currie, Nevada, nonmarine Newark Canyon Formation of Early and near Wah Wah, Utah, about 70 milesnorth Cretaceousage, which occursin the vicinity of and 90 miles southeast of Ely, respectively. Eureka, Nevada, 70 miles west of Ely. To the Nolan et al. [1956, pp. 68-70] describedthe southeast in northwest Arizona and adjacent areas,substantial sections of Mesozoicrocks oc- by McJanneti and Clartc [1960a, p. 245], who cur. Stokes [1960, p. 121] indicatesthat south- infer that part of this valley fill is of Pliocene eastern Nevada was generally above sea level (?) age. Obviously,as the depositswere laid for most of Mesozoic time. At least in late down in basinsor valleys, the thicknessshould Mesozoic time, parts of the area were being be variable, ranging from a feather edgeat the eroded and had exterior drainage. margins to a substantial thicknessin the central Nonmarine sedimentary rocks of Eocene age parts of the valleys. in and adjacent to the White River Valley have Quaternary depositsinclude gravel, sand,silt, been describedby Win/rey [1960], who named and clay laid down in stream-channel,alluvial- them the SheepPass Formation. Their aggregate fan, and playa environments.White River, when thickness is 3220 feet. As tentatively outlined it was a through-flowingstream in late Pleisto- [Win/rey, 1960, Figure 3], the basin in which cenetime, probably removedmore material than they were deposited extended from about T5N it depositedin the lower parts of the valleys in to T11N in the southern White River Valley which it flowed. The depth and extent of dissec- and from Cave Valley on the east to beyondthe tion are greatest in the southern or downstream White Pine Mountains on the west. Contem- valleys. poraneous deposits have not been described Most of the mining districts have areas of elsewhere in the region, although the Horse exposedintrusive rocks, and Bauer et al. [1960, Spring Formation of Eocene (?) age in the p. 223] discuss some of the intrusive rocks in Muddy Mountains, south of Coyote Spring the Robinson Mining District west of Ely. Valley, may be equivalent in age [Wi•/rey, Adair and Stringham [1960, Figure 1] showthe 1960, p. 133]. location of five intrusive igneousbodies or dike During middle Tertiary time an extensiveand groups adjacent to the White River Valley. Two thick section of volcanic rocks was laid down in areas are in the White Pine Mountains, and easternNevada. Cook [1960, Figure 1] indicates three areas are in the Egan Range. that an extensiveignimbrite province included The rocks.have been faulted, fractured, and much of the area of this report. To someextent displacedin a complexway and in varying de- nonmarine sediments, such as the lacustrine grees within the region during several periods limestoneand cobbleconglomerate in the Pahroe of structural activity. Range reported by Tschanz [1960, p. 204], are Occurrenceof groundwater. For the pur- interbedded locally with the volcanic rocks. The poses of this report the several stratigraphic thickness of the volcanic rocks varies sub- units discussedbriefly in the previous section stantially from placeto place,but Dolgo# [1963, can be groupedbroadly on the basisof apparent p. 878] estimatesa thicknessof over 3000 feet grosshydraulic properties. for the volcanic sequencein the Pahranagat Three groups are shown on Figure 3. The area. relative hydraulic properties are noted in the Continental depositsoverlie the Tertiary vol- explanationL Not shown are Precambrian and canic rocks in the present valleys. Commonly intrusive rocks that have negligible fracture these are fine grained lacustrine or playa de- permeability.These rocks probably provide a posits that grade laterally to coarser fractions lower limit to groundwater circulation, not toward the source areas in the mountains. The otherwiselimited, at depth. Where these rocks Muddy Creek Formation of Plioeene (?) age are exposedand are continuouswith depth, [Longwell, 1928, pp. 90-96] is partly exhumed they also should form a barrier to the lateral in Moapa Valley. Longwell [1928, p. 94] sug- movement of groundwater. gested that a thickness of 1700 feet for the Fracture and solution openingsin the Pale- Muddy Creek Formation was not excessivein ozoie carbonaterocks locally store and transmit the central part of the basin. Somewhat similar substantialquantities of groundwater.The great fine graineddeposits are exposedalong parts of thickness of Paleozoic carbonate rocks in this the White River Channel. Their maximum region tends to favor a regionalhydraulic con- thicknessis not known. In White River Valley tinuity, even though the Paleozoic rocks have the County Line oil test (point 10, Figure 4) been subjectedto several periodsof substantial penetrated 1475 feet of 'valley fill' as reported faulting. Interbasin GroundwaterSystem 257 The occurrenceof groundwater in carbonate The Tertiary volcanic rocks generally have rocks is demonstratedby the widespreaddistri- low permeability. These rocks ordinarily are bution of many large springs associatedwith rather fine grained,and the extent to whichthey Paleozoic carbonate rocks throughout eastern may transmit groundwateris possiblycontrolled Nevada. For example, most of the flow of by the degreeto which closelyspaced fractures Crystal Springs in Pahranagat Valley (Figure occur in them. Where these rocks are welded or 4) issuesin the bottom of poolsand adjacent more or lessglassy, fractures may be somewhat seeps from valley fill. However, part of the open and locally transmit groundwaterfreely. flow of Crystal Springs issues directly from A well north of Lathrop Wells in southern carbonate rocks, which are exposedand also vada is known to be capable of producing underlie the adjacent valley fill. The other several hundred gallons of water per minute principal springs,such as Ash and Hiko springs from the welded tuff (Winegrad, private com- in PahranagatValley, the large springsin upper munication, 1963). Commonly,however, semi- Moapa Valley, and Hot Creek, Mormon, and perchedgroundwater in fracture systemsin the Lund springsin White River Valley, issuefrom Tertiary volcanicrocks suppliesthe water for pointsat or near contactswith carbonaterocks numeroussmall springsin the mountains,such and valley fill. as those in the southernButte Mountains, in Groundwater occurs in carbonate rocks at the Quinn Canyon Range alongthe west side of depth, as in the Deep Ruth, Kelinske, and GardenValley, and in the Delamar Range along Starpointer shafts in the RobinsonMining Dis- the northwest side of Kane Spring Valley. trict (L. Green and M. Dale, oral coremunica- Where these rocks are beneath the valleys and tion, 1964). These shafts are about 1 mile east are saturated, substantial quantities of ground- of Liberty pit, shown on Figure 4. Ground- water may be stored in them. The extent to water also occurs in carbonate rocks in the which they may transmit groundwateris raiher Bristol Mine in the Bristol Range (Paul Gem- a function of the cross-sectionalarea. through mill, private communication,1964). Fresh water which the water may move and the hydraulic was reported [McJannett and Clark, 1960b, p. gradient than of the unit permeability, which 249] in 'cavernouszones' of the JoanaLimestone generallyis very low. (Lower Mississippian) at depths of 4058 to The partly consolidatedor cemented fine- 4097 feet below land surface in the Hayden grainedvalley fill of Pliocene(?)and Pleistocene Creek oil test (data point 6, Figure 4). This age generally yields water slowly. However, interval is roughly 3000 feet lower than the Coyote Spring in Coyote Spring Valley yields floor of Jakes Valley, which is about 5 miles a modesl•supply of water, at one time nearly northeastof the test well. half a cubic foot per second,from a combined The elastic rocks included in the Paleozoic developmentof a tunnel and several wells in group in Figure 3 tend to act as barriers to fine-grainedvalley-fill deposits.Brownie Spring groundwater movement compared with car- in PahranagatValley yields about 1 cubic foot bonate rocks. However, fractured clastic rocks per secondfrom a tunnel in consolidatedcon- do store and transmit some groundwater at glomerate.Where saturated,the fine-grainvai- least locally, as in the Piochedistrict. ley fill is capableof storir large quantitiesof The older Tertiary sedimentaryrocks, such water. The unconsolidatedsand and gravel de- as the SheepPass Formation of Winfrey [1960], positsof the youngervalley fill and in'alluvial are generally consolidatedand are believed to fans are capable of transmitting water freely. have little primary permeability. Locally they The sand and gravel depositsof the younger are faulted, which may provide secondaryfrae- valley fill commonly have the highest unit tures throughwhich somewater may be trans- permeability of any unconsolidateddeposits in mitred to springs,such as in TllN, R62E in the region. The large-capacity irrigation wells the Egan Range where that formation is ex- in the White River, Pahranagat, and upper posed.Where suchr•Jcks underlie the valley Moapavalleys are developedin thesedel)osits. floor and are saturated,they may containa con- Groundwater movement. The hydraulic siderablevolume of groundwaterin storage, gradientsbetween springsand se!eetedwells, even thoughthe averagepermeability is small. and, more generally,the regionaltopographic 258

MuddyR,ver Datapoint numbers, as onfigure 4 HotCreek Preston Sirings42 40 39 3736 35 29 23 222120 14SI3rlngs 5OOO , Springs 7 3 2 •> / J J dAKES VALLEY LONG VALLEY ( 7• COYOTESPRINGS PAHRANAGAT PAHROC WHITERIVER VALLEY • 5•0• J VALLEYJ J VALLEYI J J JVALLEY I I II I I • • • I I ,...___•• ...... Fo 0 8 16 24 32 40 Scale in Miles

Fig. 5. Diagrammatic profile showing relation of water level to land surface along longitudinal axis of the area.

gradient, indicatethe generaldirection of poten- 19, 30, 29, and 25 on Figure 4). The altitudesof tial lateral groundwater movement in the re- these water levels are higher than known or in- gional system. Actual movement is dependent ferred altitudes of water levels along White upon the hydraulic conductivity of the rocks. River Wash at or south of the equivalent lati- The principal springs, which are the major tudes. Most of these water levels are considered points of dischargefrom the regionalsystem, are to representsemiperched groundwater in valley in or adjacent to the White River Wash, and fill. As such, it is inferred that water levels in the altitudes of their orifices decrease south- the carbonaterocks underlying the severalwells ward. Thus, in White River Valley, PrestonBig would be at somewhatlower altitudes.Even so, Spring issuesat an altitude of 5680 feet above the potential gradient and movement from the sea level and Hot Creek Springs, about 40 adjacent valleys apparently is toward the miles south, issuesat an altitude of 5175 feet trough occupiedby the White River Wash. above sea level (Figure 4). In Pahranagat Val- For Jakes and Long valleys, lying north of ley from north to south, Hiko, Crystal, and Ash White River Valley, the valley floors are at springs issue at altitudes of about 3890, 3805, altitudes of 6295 and 6050 feet, respectively,and and 3610 feet, respectively. In upper Moapa are higher than White River Valley. The lowest Valley, the closelygrouped Muddy River Springs known water-level altitude beneath the playa of issue between altitudes of 1800 and 1780 ft. Long Valley is about 6000 feet, and in Jakes Compared with tile low parts of adjacent Valley the water level is unknown but is esti- topographically closed valleys of the regional mated to be as much as 400 feet below the playa groundwatersystem, the White River Wash is surface. A potential though low southward generally considerablylower at equivalent lati- gradient through the carbonate rocks toward tudes (Figure 4). The playa of Cave Valley is White River Valley apparently exists, as the about 5975 feet above sea level. Due west in altitude of the water level in a well (point 7, Fig- White River Valley the Wash altitude is lessthan ure 5) in northern White River Valley is about 5200 feet. In Coal Valley the playa is at an 5780 feet and at PrestonSprings, about 12 miles altitude of about 4950 feet, whereasdue east the farther south,is about 5650 feet. White River Wash altitude is about 4800 feet. Outcrops of Paleozoic carbonate rocks at or In Dry Lake Valley the playa altitude is slightly adjacent to most of the springs are at altitudes less than 4600 feet. At the latitude of the central lower than other Paleozoic carbonate rocks at part of that playa, the White River Wash is or north of the latitude of the respective out- about 440 feet. The Delamar Valley playa is crops within this region. For example, in White about 4400 feet above sea level, and upper River Valley the carbonate-rock outcrops ad- Pahranagat Lake due west is about 1000 feet jacent to Lund Spring (Figures 3 and 4) are at lower. a lower altitude than other carbonate-rock out- In all the above valleys plus Garden Valley, crops at or north of that latitude in White which surficially drains to Coal Valley, water River, Jakes, or Long valleys. The carbonate- levels are several hundred feet' or more below rock outcropsfrom which I-Iot Creek Springsis- the respective playas. Representativeknown, sue are also at lower altitudes than any others at reported, or inferred low water-level altitudes or northof that latitude'•in WhiteRiver, Jakes, for Cave, I)ry Lake, I)elamar, Garden, and Long, and Cave valleys. Coal valleys, respectively,are 5500, 4300, 3700 Similarly, the Paleozoic carbonate rocks (?), 5020, and less than 4775 feet (points 15, from which Crystal Springsissues in Pahranagat Interbasin Groundwater System 259 Valley are at a lower altitude than other out- mile, between the middle pair of wells (points crops of carbonate rocks north of that latitude. 21 and 22) is nearly 22 feet per mile, and be- This same relation applies to the Paleozoiccar- tween the downstream pair of wells (points 22 bonate rocks exposed adjacent to the Muddy and 23) is over 100 feet per mile. Several miles River Springs. This repetitive association of northwest of the upstream well (point 20) the large springs with areas of topographically low water-level gradient is parallel to and within outcrops of Paleozoic carbonate rocks demon- about 10 feet of land surface. The steepeningof strates their closeassociation and supports the the water-level gradient in the valley fill in this inference of the regional movement of ground- section of the White River Wash is inferred to water. reflect a relatively abrupt changeof head in the The regional potential groundwater surface groundwater in the underlying carbonate rocks. is not everywhere defined by a smooth surface. This change or difference in head may be as- On the contrary, 'limited data suggestthat the sociated with faulting in the carbonate rocks, water surfaceshave local hydraulic discontinui- which results in a barrier effect to the movment ties resulting from barrier effects or from other of groundwater across the fault, or with an causes. increase in the relative capacity to transmit The profile in Figure 5 showsthe land-surface water in the Paleozoic carbonate rocks down- and water-level altitudes along the approximate stream from this section. longitudinal axis of the region. It follows the A somewhat similar discordance in altitude of general alignment of the White River wash water levels occursin the valley fill southward southwardfrom the latitude of Preston Springs. from Maynard Lake (point 39, Figure 4). The The upper line of the profile showsland surfac• reported depth to water in the well (point 40) with the vertical and horizontal scalesthe same, in northern Coyote Spring Valley was 416 feet, to illustrate the small proportion of relief in the or at an altitude of 2175 feet. The well is about region as a whole. The lower profile showsthe 8 miles south of Maynard Lake. The indicated land surface and water levels at a vertical ex- water-level gradient between Maynard Lake aggeration 10 times the horizontal scale for the and the well is about 117 feet per mile. This purposeof more readily showingthe local diver- gradient too is consideredto reflect a relatively gence of water level from land surface. As can steep apparent water-level gradient of the be seen from the lower profile, the water-level groundwater in the underlying Paleozoic car- gradient is near and parallel to the land-surface bonate rocks in the vicinity of Maynard Lake gradient in the White River, Pahranagat, and gap. The most likely causehere is a barrier effect upper Moapa valleys, the areas of principal resulting from faulting in the vicinity of the spring discharge.Elsewhere, the gradient locally Maynard Lake gap. Tschanz and Pampeyan may be steeperthan the land surface,as is in- [1961] show a prominent fault complex cross- dicated in the north end of Pahroc and Coyote ing White River Wash just south of Maynard Springs valleys, and in other sections the Lake, which could provide the necessarylocal gradient is lessthan that of the land surface,as barrier effect to southward groundwater move- in the central and southern parts of Pahroc and ment. Coyote Spring valleys. In central Pahroc Valley, the well (point 23) At the north end of Pahroc Valley and the was dry at a depth of 800 feet, or at about an south end of White River Valley the depth to altitude of 4125 feet, as noted above; the alti- water in the valley fill along White River Wash tude of Hiko Spring, 31 miles southwestalong in 4 wells (points 20, 21, 22, and 23, Figure 4) the Wash, is about 3890 feet. The indicated increasesprogressively from about 90, to 217, to gradient is lessthan 8 feet per mile. However, 252, and to more than 800 feet below land sur- the water-level altitude in the carbonate rocks face. The land-surfacegradient in this segment is probably somewhat lower than in the over- of the wash is about 14 feet per mile, and the lying valley fill in the vicinity of the well. Thus, distancesbetween the wells are 3, 4.5, and 6 the inferred water-level gradient in the car- miles, respectively.Thus, the indicated water- bonate rocks betweenthese two points may be level gradient between the upstream pair of even less than the above indicated gradient of wells (points 20 and 21) is about 56 feet per 8 feet per mile. 260 T•0•AS E. EAKIN

In Coyote Spring Valley, the indicated hy- ever, average precipitation is greatest in the draulic gradient between the two wells (points mountainous areas at altitudes of 7000 feet and 40 and 42) is about 13.5 feet per mile. This higher. Much of the precipitation in the moun- lower gradient is in contrast with the steep tains occursas snow,which accumulatesdurirg gradient near the north end of the valley, as the winter and melts in the spring. This process was also the ease in Pahroe Valley. Between is favorable for accomplishingrecharge. In gen- the southernwell (point 42) and Muddy River eral, then, most of the rechargefrom precipita- Springs the difference in altitude of water level tion is probably centeredin and adjacent to the is about 75 feet in a distance of about 10 miles. severalprincipal mountain ranges. The apparent gradient is about 7.5 feet per The general relations of increasedprecipita- mile. Again the inference is that the water-level tion with altitude and the seasonal distribution gradient in the underlyirg carbonate rocks is of precipitation are shown by the average probably somewhatless than that in the valley monthly and annual precipitationfor Kimberly, fill for most of the length of the valley. The Adaven,Alamo, and Overton (Table 3). Station above information suggests that a general locationsare shownon Figure 1. gradient in the carbonate rocks in this region Winter precipitation usually results from may be lessthan 8 feet per mile. Thus, the rela- general storms that originate in the north tive altitudes of the principal springs,wells in Pacific. Summer precipitation occurs as high- key locations,and regional topography support intensity showersresulting mainly from south- the inference of regional groundwater gradient east storms and local convectional storms. This to the south. relationship results in a pattern in which most Recharge o/ groundwater. Table 1 sum- of the precipitation occurs during the winter marizes the estimatesof recharge to and of dis- half of the year but with a secondarysummer charge from the groundwater system. These maximum in July and August. The summer estimates were derived mainly in the reports maximum tends to be more pronouncedin the referred to in the table. southernpart of the region. Precipitation providesthe principal sourceof The distribution of water runoff from the water for rechargeto the regional groundwater mountains also permits some inferences of the system. The direct measurement of recharge is distribution and manner of recharge to the not feasible,nor perhaps even possible,over an groundwater system. For mountain areas of area of any great size.However, the generalrela- otherwisesimilar characteristics,proportionally tionshipsthat potential rechargeincreases with large runoff suggestslittle rechargeby deep in- increased precipitation and that precipitation filtration in bedrockin the mountains,and small generally increaseswith altitude have been used runoff suggestsproportionally large rechargeby to make estimatesof long-term average annual deepinfiltration in the bedrock.Also, substantial recharge. The average annual recharge to runoff from the mountains suggeststhat re- groundwater from precipitation in a valley has charge by infiltration from streamflow on the been estimated empirically for the reconnais- valley fill may be significant. sance investigationsby a technique that seem- Records are not available to demonstrate the ingly produces reasonable estimates for most magnitude and distribution of streamflow areas of Nevada. Briefly, precipitation zones throughoutthis region,but a generaldescrip- indicatedby Hardman a•d Mason [1949, p. 10] tion of the streamflowconditions provides illus- are taken to be approximately represented by trative support. altitude zones on the l:250,000-scale topo- The present-day White Riyer is a headwater graphicmaps. The successivelyhigher zoneshave remnant of the ancestralWhite River (Figures higher average annual precipitation and ac- I and 4). The White River formerly was a cordingly are consideredto have a higher per- throughfiowirg stream that surficially drained centage of the precipitation recharging the the White River, Pahroc, Pahranagat,Coyote groundwaterreservoir. The values generally as- Spring, Kane Spring, and upper Moapa valleys sumed are shown in Table 2. to the Colorado River. It was a prominent Obviously, recharge is not uniformly dis- streamas late as late Pleistocenetime. Probably, tributed either over the area or in time. How- too, in extremely rare and most favorable con- InterbasinGroundwater System 261 262 THOMAS E. EAKIN

TABLE 2. Assumed Values for Precipitation and Per Cent Recharge for Several Altitude Zones in Area of This Report

Assumed Assumed Average Average Annual Recharge Precipitation Altitude Annual to Groundwater, Zone, Zone, Precipitation, % of average in. ft ft precipitation

Less than 8 below 6000 variable negligible 8 to 12 6000 to 7000 0.83 3 12 to 15 7000 to 8000 1.12 7 15 to 20 8000 to 9000 1.46 15 More than 20 more than 9000 1.75 25 ditions, through streamflowmay have occurred sustainedby flow from the severalsprings along since Pleistocenetime. The position of the an- the floor of the valley. However, during much of cestrai White River is marked by a wash or the year streamflowfrom the mountainsis small trench along the topographical axis of the and is dissipated by diversion for irrigation White River, Pahroc, Pahranagat, Coyote and evapotranspiration before it reaches the Spring, and upper Moapa valleys. The wash is Nye County line. At times of minimum stream- incised from a few to several hundred feet below flow the channel may be dry only a short dis- the adjacent valley surfaces. Perennial flow tance downstream from where the stream leaves presently occurs only from the White Pine the mountains. The streamflow reportedly Mountains and downstreamfrom the principal [Maxey and Eakin, 1949, p. 15] has been as springs in the White River, Pahranagat, and much as 75 cfs (cubic feet per second) during Moapa valleys. The principal present-day flow the spring freshet, although commonly the occursin the downstreampart of the ancestral streamflow is about 2 cfs during the summer river. Here Muddy River flows from Muddy seasonin the vicinity of Preston. Maxey and River Springs near the head of Moapa Valley Eakin [1949, Table 1] list a number of meas- through Moapa Valley to Lake Mead (Figure urementson the White River, made during the 1). Otherwise,flow occursalong limited sections period 1908-1943. of the wash only after high-intensity storms or Most of the streams having sufficient flow to very favorable snowmelt conditions. be utilized for irrigation head in the ranges The present-day White River and its princi- borderingthe west side of Jakes, White River, pal tributary, Ellison Creek, drain a part of the and Garden valleys. The streamflow is derived east side of the White Pine Mountains. The largely from the seasonalsnow accumulation. White River flows from these mountains at a Peak flow occurs with the spring runoff, and point about 5 miles northwest of Preston low flow is partly suppliedfrom small mountain Springs. During periods of high flow or when springs. evapotranspirationis at a minimum, the stream- Throughout the area streamflow may occur flow may extendto the southend of White River for short periods after high-intensity storms, Valley, a distance of about 50 miles, in part most of which probably occur during the sum-

TABLE 3. Average Monthly and Annual Precipitation for Adaven, Alamo, Kimberly, and Overton, Nevada, for Period of Record

Period of Alti- Station Record tude Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Annual

Adaven 1919-1962 6250 1.32 1.48 1.46 1.04 0.81 0.43 0.86 1.20 0.50 1.02 0.84 1.20 12.19 Alamo 1922-1960 3610 0.62 0.66 0.70 0.58 0.47 0.16 0.67 0.72 0.26 0.56 0.43 0.51 6.34 Kimbedy 1931-1958 7230 1.55 1.50 1.55 1.32 1.32 0.66 0.90 0.83 0.68 0.89 0.84 1.51 13.30 Overton 1940-1962 1220 0.54 0.48 0.41 0.24 0.15 0.05 0.20 0.38 0.29 0.47 0.41 0.60 4.22 Interbasin Groundwater Syste•n 263 mer months. On the whole all streamflow is in the other valleys,which is not associatedwith dissipated within the area by evaporation, the principal springs,is estimatedto be nearly transpiration, and recharge,except for minor 5000 acre-feet a year and largely occurs in amounts generated by high-intensity storms Long, Garden, and Cave valleys. either in CoyoteSpring or Kane Spring valleys, The springsof the three groups generally are which occasionallyresults in runoff throughAr- known to have relatively uniform flow. Some row Canyon into the Muddy River in upper variation of flow undoubtedly occurs,but the Moapa Valley. occasionalmeasurements of discharge made at The nature of the bedrock in the mountains most of the springsare not adequateto define apparently affects the runoff in the area. Lo- minor variations. In White River Valley, the cally,the Paleozoiecarbonate rocks, which trans- Preston Springs-principally Big, Arnoldson, mit water readily, seeminglyreceive recharge Cold, and Nicholas-havebeen measuredat reg- from precipitation that otherwise would be- ular weekly intervals suflScientlyto demonstrate come runoff in the mountain canyons. Thus, a relatively constantflow characteristic.Preston Illipah Creek (point 5, Figure 4) seemsto be Big Spring (dischargeabout 8.5 efs) has been smallerthan one might expect from the altitude measured at about weekly intervals during the and area of its drainage basin. Perhaps a more periods March to August 1936, Septemberto surprisingexample is the near lack of perennial November 1948, April to November during runoff into the valley for the well-wateredEgan 1949, 1950, and 1951, and from May to Sep- Range. tember 1952. Arnoldson Springs (discharge The distribution of present-dayperennial and about 3.5 efs) and Nicholas Springs (discharge seasonalrunoff is closelyassociated with the dis- about 3.0 cfs) have been measured at about tribution of the higher mountain ranges and weekly intervals from September 1948 to Sep- generally supports the concept that the greater tember 1952. These records indicate that the average precipitation is associated with the minimum dischargeis only about 10% lessthan higher mountain ranges. the maximum. Average annual runoff from the mountains Arnoldson, Nicholas, and Cold springs also of the region is estimated to be about 80,000 were measuredat about weekly intervals from acre-feet, as computed by the altitude-runoff March to August 1936. These measurements method describedby Riggs and Moore [1965]. also indicated nearly constant flow. During this Of this amount, about 70% is estimatedto be period the flows of Arnoldson (3.8 cfs) and generated in the northern half of the region. Nicholas (2.7 cfs) springs were somewhat dif- Thus, the distribution of runoff indicates that ferent than the flows during the later period of the northern part of the area is relatively well measurement,apparently the result of changing watered.This indicationin turn suggeststhat the the outlet level of one of,the springs.However, potential for recharge from streamflow also is the combined flow of the two springs for both relatively favorable in the northern part of the periods was almost identical. These data sug- region. gest a highly uniform flow of the springs.The Discharge of groundwater. The principal na- best record to indicate the long-term spring- tural dischargeof groundwateris from the three flow characteristics,however, is the gaging rec- groupsof springsin the White River, Pahrana- ord of the Muddy River near Moapa. The gag- gat, and upper Moapa valleys. The discharge ing station is within 2 miles of the Muddy River of the springsin the White River and Pahrana- springs,which supply most of the flow of the gat valleys subsequently is lost from those Muddy River. With appropriate adjustments, valleys,largely by evapotranspiration,including that record can be used to represent the dis- the water utilized for irrigation. In upper Moapa ch_argeof the springs.

Valley most of the spring dischargeleaves the ß The streamflow of the Muddy River, near valley as streamflow in the Muddy River. The Moapa, has been recordedfor the periodsJuly combined average discharge of these three 1913 to September1915, May 1916 to Septem- groups of springs is estimated to be about ber 1918, June 1928 to October 1931, April to 98,000 acre-feet a year (Table 1). Additionally, July 1932, and from October 1944 to the pre- dischargeof groundwaterby evapotranspiration sent. The streamflow record at this station 264 THO•tAS •. •A• representsthe actual discharge of the springs, to occur, with considerabletime lag, in response except as follows: (1)streamflow at the station to variations in precipitation and consequent may be higher than spring dischargeduring recharge.Both the high degree of uniformity periods of local runoff, particularly from high- of dischargeand the small variationsin annual intensity rains within the immediate drainage mean discharge are compatible with the ex- area; and (2) streamflowat the station is lower peered character of dischargefrom a regional than spring dischargewhen water is diverted groundwater system. above the gaging station for irrigation, and Relation o• estimated grouadwater recharge when evapotranspirationbetween the station to discharge. The estimatesof rechargeto and and the springsdepletes the flow at the gaging dischargefrom the regional system shown in station site. Table i agree closelyfor the region as a whole: A partial adjustment for the effect of over- the estimated recharge is 104,000 acre-feet a land runoff, during the period 1944-1962, was year, and the estimated dischargeis 103,000 made by Eakin [1964, p. 23]. This adjustment acre-feet a year. The estimatesare considered resulted in a residual flow that, in effect, was reasonable and represent the magnitude of entirely derived from spring discharge. The water naturally entering and leaving the re- mean, median,and adjustedmean monthly and gional system.The closeagreement in the nu- annualdischarges for 25 completewater yearsof merical values is consideredto be coincidental record through 1962 are given in Table 4. rather than to indicatea high order of accuracy Recently Eakin aad Moore [1964] further in the estimatingtechniques. a]nalyzedthe record of dischargeof the Muddy Althoughthe regional estimates agree closely, River to evaluate the characteristicsof the flow there is wide divergence in the estimates for of the springssupplying the river. Corrections particular valleys. For example, in the White for evapotranspirationlosses between the springs River and upper Moapa valleysthe estimatesof and gagingstation virtually eliminated the sea- spring dischargeare 37,000 and 36,000 acre-feet, sonal variation shown by the month-to-month respectively.The estimate of recharge (38,000 variations of mean streamflow at the gaging acre-feet) from precipitation within the sur- station. January characteristicallyis the month ficial drainage area of White River Valley ap- having the minimum average temperature and proximares the estimate for spring discharge, rate of evapotranspiration.Accordingly, the but the estimated rechargefrom precipitation mean annual dischargeof the springssupplying in the local drainage area of- upper Moapa Muddy River is thus closely represented by Valley is negligible. the mean January discharge (49.8 els) re- Figure 6 showsthe distribution of the esti- cordedat the gagirg station. mated rechargeto and dischargefrom the re- The analysis indicated a high degree of uni- gional groundwater system and a generalized formiry of spring discharge. The minimum representation of the regional flow system. annual mean dischargewas about 90% of the From the figure it is seen that about 78% of maximum year. However, the small range in the recharge is estimated to occur in the 4 annual mean dischargeapparently is significant northern valleys, and about 62% of the dis- in that the variations appear to be orderly and charge is estimated to be from the springs in

TABLE 4. Monthly Discharge of Muddy River, near Moapa, for 25-year Period Ending September 30, 1962

Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Sept. Year

25-year mean 46.1 48.7 49.5 49.8 49.7 48.1 46.8 45.0 43.2 43.4 44.2 44.4 46.5 25-year median 46.5 48.0 49.3 49.3 49.2 47.6 46.5 45.4 43.4 43.9 43.3 44.4 46.7 Mean adjusted for effect of local surface-water runoff 46.0 48.2 49.5 49.8 49.4 48.0 46.8 44.9 43.2 43.0 53.5 44.4 46.4 Interbasin GroundwaterSystem 265

Estimated average annual recharge to and discharge (--) from the regional ground-water systems, in thousands of acre-feet per year.

LONG VALLEY 8 '•ß •i A.. 05 15 25 L .•" '•Scalein Miles PJAXES(' JAKES VALLEY 17 • VALLEYo

CAVE VALLEY • : •'

• t • • CAVE•

--37 -- Spring discharge White River Valley .. . t _ --•- • VALLEY [

• .. VALLEY.: COA' : I t •., ,,...•v 2 D,• L,• V,LL•• /l • • • ) •*•

' " " : VALLEY

• .....• • N- V,LLEr D•L,•,, WLL•r .• • { DELAMAR, •as•.,oun•ar• • 2 • ] % w'•? •. • • - • = • • VALLEYI •

su•-• •ounaar• • ...... i •>• • • • •pr•ng•scnarge •anranaga• va•ey • '•' VALLEY•'

groundGeneralwater directionmovement of COYOTESPRINGI AND • COYOTEI j ' KANESPRING2 VALLEYS •J SPRINGS'• • .OA.AUPPER I • I 37 / VALLEY• •ALLEY Approximat;;;ctionusedto --36 --Spring discharge UpperMoapaValley • ' [ ',• computeregional transmissibility + I -- Netdifference inestimates Fig. 6. Generalizedflow pattern and estimatedaverage annual rechargeto and discharge from the regional groundwater system. 266 •x•o•xs

the Pahranagat and upper Moapa valleys in The estimated transmissibilities for the three the southern part of the region. sectionswere computed by using equation 1 Thus, the generalbalance between the over- and the values are listed in Table 5. These all estimatesof recharge and dischargesuggests values suggestthat a first approximationof the a regional system within the 13-valley area. regional transmissibility of the Paleozoic car- Further, the grossdistribution of rechargeand bonate rocks is on the order of 200,000 gal/day/ discharge infers a generally southward move- ft. The value is not large consideringthe sub- ment compatible with the regional movement stantial thickness of the Paleozoic carbonate indicated by the potential hydraulic gradient rocks. However, as the actual transmissionof discussedin the previoussection. groundwater in the carbonate rocks is localized Regiona.1transmissibility o• the Paleozoiccar- largely in fracture or solutionzones, local trans- bonate•rocks. Transmissibility,one of the missibilityvalues undoubtedly are much higher, hydraulic properties of an aquifer, is usually perhaps l0 times or more, than the indicated determinedby pumping tests under controlled averageregional value. On the other hand, large conditions. Values so obtained are then used to areas of carbonate rocks that have little or no compute the quantity of groundwater flow fracturing and solutionopenings transmit very through a specified segment of aquifer. Wells small amounts of water. are not available in this region to obtain trans- Chemical quality of water in the regional missibility data of the carbonate rocks. system. The chemical character of ground- However, the generalizedflow pattern and water in part reflects an interaction between natural recharge-dischargerelations shown on the water and the rocksthrough which it passes. Figure 6, togetherwith the hydraulicgradients Chemical analysesof water from several of the discussedin the previous sectionon movement principal springs in the region are listed in and generallyshown in the profile on Figure 5, Table 6. As these springsrepresent most of the can be used to estimate the regional transmissi- dischargefor the regionalsystem, chemical con- bility of the Paleozoic carbonate rocks. The stituents are a compositeof the variations and formula used is concentrationsthat ordinarily may be found in the system.Locally, higher or lower concentra- T -- Q/0.00112 IW (1) tions of individual constituents and total dis- where T is the transmissibility in gal/day/ft; solved constituentsundoubtedly occur. Q is the underflowin acre-feet per year; I is the The water from the springs in the White hydraulic gradient in feet per mile; W is the River and Pahranagat valleys characteristically effectivewidth of the aquifer in miles, through is a calcium-magnesiumbicarbonate type, and which southward flow occurs; and the constant the dissolved-solidsconcentration ranges from 0.00112 is a factor to convert gallonsper day to 246 to 343 ppm (parts per million). Water from acre-feet per year. the Muddy River Springs in upper Moapa Three general sectionswere selectedto esti- Valley has about twice the dissolved-solidscon- mate transmissibility' (1) a section near the centration (614 and 620 ppm) and is of a north end of White River Valley through which mixed type. most of the underflow occurs from Long and In a complexhydrologic system with many Jakes valleys; (2) a sectionnear the south end of White River Valley through which most of the underflow occurs from White River and TABLE 5. Three Estimatesof Transmissibility in the Regional Groundwater System Cave valleys; and (3) a section in central Coyote Spring Valley through which most of Underflow Estimated Estimated the underflow occurs from Pahranagat and (Q) from Effective Computed Transmis- Delamar valleys. Gradients used are the indi- Sec- Figure 2, Width (W), Gradient, sibility, cated regional minimums, as discussedin the tion acre-ft/yr mi ft/mi gpd/ft section on groundwater movement. Locally, actual gradients may be only a foot or two (a) 25,000 15 6.4 230,000 per mile or as much as several hundred feet (b) 40,000 25 S lS0,000 (c) 35,000 15 8 260,000 per mile where controlledby barriers. Interbasin Gro,undwaterSystem 267

......

000 '• • 000 • • • 268 T•O•rAS •. •A•r•r interrelated subsystems,the causesof many of than a few hundred feet, may transmit ground- the chemical variations of the groundwater water, but the lateral movementof water closely naturally would be obscure.However, the anal- conformsto the general slope of the land sur- yses of water from springsin the White River face. Valley show a reasonableuniformity of com- 2. The major structural trend commonly is position for water that probably has been de- about parallel to the principal topographicaxis rived from nearby areas and has moved largely of the range. Ordinarily, faults and structural through carbonate rocks, but which includes alignments tend to act as barriers to ground- some water that has moved partly in volcanic water movement across or at right angles to and sedimentaryrocks. If the hypothesisof the them. regional system is approximately correct, most 3. The mountains characteristically receive of the water supplying the springs in Pahrana- much greater average precipitation than do the gat Valley should be derived from a consider- adjacent valleys; greater precipitation provides able distance beyond the immediate surface a greater potential for recharge.If greater re- drainage area; that is, several tens of miles at charge occursper unit area, other things being least. The concentration of water from these equal, a hydraulic high (or divide) will be springsmight remain relatively low if the water maintained between the areas of lesser or no moved almost entirely in carbonate rocks. The recharge. analysesof water from Hiko, Crystal, and Ash 4. Surface water divides are coincident with springsshown in Table 6 are indeed low, rang- the topographicdivides, which suggeststhat the irg from 286 to 313 ppm of dissolvedsolids. groundwater divide is also aligned with the The dissolved-solids concentration of the topographic divide. water from two of the springsin upper Moapa Valley is about 2 times that of the other two The position of the hydraulic boundary of the groups of springs. Much of the increaseis due regional groundwater system is indicated at to an increasein sodium, sulfate, and chloride only a few locations.For example, in the Egan ions. Calcium is moderately higher, but mag- Range, the water-level altitude in the well nesium is nearly constant in the water from all (point 7, Figure 4) 12 miles north of Preston the springs. This general increasein concentra- Springs in White River Valley is about 5780 tion is more or less to be expected for water feet. Northeastward about 11 miles, the water- issuing from a position in the regional system level altitude in the Alpha Shaft is reported to relatively removed from most areas of dis- be 6108 feet [Maxey a•d Eakin, 1949, p. 41]. charge. The moderate degree of concentration Eastward about half a mile, the water-level suggeststhat circulation in the regional system altitude in the Liberty Pit is maintained by is comparatively active. pumping at an altitude of about 6475 feet. Bou•da.ries of the regional groundwater sys- Drill holes on the east side of Liberty Pit are tem. In the preceding discussionthe general reported to have water-level altitudes ranging boundary of the White River regional system from about 6860 to 6960 feet. Groundwater in has been represented as being approximately carbonate rocks was encounteredin the nearby coincidentwith the outer topographic divides of Deep Ruth and Kelinske shafts. About 2 miles the appropriate valleys. In basin and range east the water-level altitude in the Kimberly hydrology,mountains usually are assumedto be Pit is somewhat below 6600 feet, and adjacent hydraulic barriers. Ordinarily few data are altitudes in drill holes range from about 6618 available to demonstrate this assumption as a to 6822 feet. The above-water-level information fact, but one or more of several factors pro- for the Robinson mining district area was re- vide the basis for this generally correct assump- ported by L. Green and M. Dale of the Kenne- tion. These factors include the following: cott Copper Company (private communication, 1964). About 3« miles southeastof the Kim- 1. The consolidated bedrock forming the berly Pit, Murry Springs, which provide the mountains is virtually impermeable. Secondary municipal water supply for the City of Ely, openingsdue to surficial fracturing or weather- issue at an altitude of about 6600 feet. Finally, ing, which rarely extend to depths of more severalmiles east in the floor of SteptoeValley, Interbasin Groundwater System 269 the water level is within a few feet of land through the older valley fill toward the White surface, which is at an altitude of about 6375 River Wash. As the rechargearea is necessarily feet. This mountain area is geologicallyand at a higher altitude than the spring area, it may structurally complex, and water levels have be assumedto be at an altitude high enough to been affectedsomewhat by mining operations. provide a hydraulic barrier in the carbonate However, the generalizedinformation indicates rocks in the Sheep Range. that a hydraulic divide is several hundred feet The I)elamar Range and Meadow Valley higher than the water level in either White Mountains form the east sides of I)elamar and River or Steptoevalleys and is within perhaps Kane Springs valleys. Some groundwater is a mile of the topographicdivide. perched in the Tertiary volcanic rocks and Limited water-level information also indi- supplies several small springs in the Kane cated the position of the hydraulic divide at the Spring Valley side of the I)elamar Range. Near north end of the Bristol Range. The water-level the townsite of I)elamar (Figure 4), somewater altitude at a well (point 17, Figure 4) in Dry initially was developedat several small seepages Lake Valley is about 4820 feet; about 8 miles from limestone and granite [Carpenter, 1915, east the water-level altitude in the Bristol Mine, p. 67] and was insu•cient for the requirements. as reported (oral communication,1964) by Paul That these springs were derived from perched Gemmill (formerly of Combined Metals Re- groundwateris suggestedstrongly by the fact duction Company), is about 5675 feet. Still that, accordingto Carpenter,the mine at I)ela- farther east in the next valley, about 4 miles mar was totally dry to a depth of 1400 feet. northeast of Bristol Mine, the water-level alti- The altitude of the bottom of the mine is not tude in a well is about 5610 [Rush, 1964,Table known but apparently was of the order of 5300 15]. Groundwater in the Bristol Mine occurs in feet. West of I)elamar, in the lower part of Paleozoic carbonate rocks, and, according to Delamar Valley, the apparent water-level alti- Gemmill, the level apparently fluctuatesto some tude may be below 3700 feet, based on reports extent with variations in recharge.The ground- that a well (point 30, Figure 4) was dry at a water encounteredin the wells is in valley fill depth of 900 feet. East of Delamar, water levels and may be under a higher head than in the in the floor of Meadow Valley Wash are at an underlying carbonate rocks. Nevertheless,the altitude of about 3800 feet. The meager re- water-level altitude in the Bristol Mine indi- charge in the Delamar Range and the presence catesa hydraulicdivide closeto the topographic of relatively impermeable Paleozoic elastic and divide in the Bristol Range. Tertiary volcanic rocks are probably sufficient The Pahranagat and Sheep ranges form the to maintain a hydraulic divide between Meadow west side of Pahranagat and Coyote Spring Valley Wash and Delamar Valley, even though valleys, respectively.Recharge from precipita- the divide may be much below the level of tion in thesemountains, although limited, prob- Delamar mine in that area. ably maintains a hydraulic divide along the More generally, on the basis of substantial mountain alignment. Data on water levels in recharge potential, it may be inferred that the the Paleozoic carbonate rocks in these moun- Butte Mountains and Egan, Schell Creek, tains are not available.However, the altitude of Bristol, and Highland ranges,which form the the water level in a well (point 32, Figure4) in easternboundaries of Long, Jakes,White River, the valley fill is about 4025 feet, or about 220 Cave, and Dry Lake valleys, respectively, are feet higher than Crystal Springs, about 3• probably aligned with the east side hydraulic miles to the east in Pahranagat Valley. This boundaries of those valleys. Similarly, the altitude suggeststhat the gradient of ground- Maverick Springs, Ruby, and the White Pine water in the underlying carbonate rocks may mountainsand Grant and Quinn Canyon ranges also be generally from the Pahranagat Range are probably aligned with the west side hy- toward the White River Wash to the east. Some- draulic boundariesof Long, Jakes,White River, what similarly, the semiperchedgroundwater and Garden valleys. supplying Coyote Springs in Coyote Spring Some sections of these east- and west-side Valley is consideredto be derived from recharge groups of mountains, such as the Antelope in the Sheep Range to the west and moves Mountains and Horse Range, are relatively low, 270 T•O•S and precipitation and resultant groundwater nature of the regional system is consideredto rechargealone may be insufficientto maintain a be valid. hydraulic divide in thesesections. The effective- Other regional or multivalley groundwater ness of these divides cannot be determined at systemspotentially may occurelsewhere in the this time. However, the prominent structural Basin and Range province,especially within the trends parallel to these rangesprobably act as principal area of carbonatedeposition in Paleo- barriers or partial barriers to groundwater zoic time, which is the area sometimesreferred movement acrossthose alignments. Provision- to as the Paleozoic miogeosynclinalarea in ally, then, it is assumedthat the principal eastern and southern Nevada, parts of western structural trends are sufficient to maintain hy- Utah, and possiblyin southernIdaho. draulic divides in these mountains. West of the srea of this report, intensive Very little rechargeoccurs in the low Meadow studiesare being completedon interbasinmove- Valley Mountains. The degree of influenceof ment in Paleozoic carbonate rocks in and ad- these mountains on groundwatermovement in jacent to the Nevada Test Site by the Geologi- the carbonate rocks in this area is not known cal Survey. Further, additional data are being but might very well be almost negligible. obtained relating to the location and extent of Groundwater in the carbonate rocks occurs at regional groundwater systems,in conjunction higher altitudes, both in the region of this re- with the regular investigationsunder the co- port and northeastwardin the Meadow Valley operativeprogram of the GeologicalSurvey in area. However,in the Meadow Valley area the Nevada. estimates of recharge from precipitation and dischargeby evapotranspirationare in relative Acknowledgments. Critical reviews and com- agreement[Rush, 1964, pp. 20-24]. This agree- ments by my colleagues G. F. Worts, Jr., J. L. ment suggeststhat if the Meadow Valley area Poole, S. E. Rantz, and S. F. Kaputska and others contributesgroundwater that u!timately dis- have materially contributed to the development chargesfrom the Muddy River Springs, then of this paper. This paper is a product of the reconnaissance the quantity is only a small proportion of the project conducted as a part of the general pro- total discharge of the springs. gram of water-resourcesinvestigations in Nevada In contrast,the combinedestimated recharge by the U.S. Geological Survey, in cooperation from precipitationin the area consideredto be with the Nevada Department of Conservation and Natural Resources. supplyingthis regional groundwatersystem is in reasonableagreement with estimatesof dischargefrom the springsonly if the Muddy River REFERENCES Springsare includedwith those in Pahranagat Adair, D. H., B. Stringham, Intrusive igneous and White River valleys. For the present,then, rocks of east-central Nevada, in Guideboole to information favors the theory that most of the the Geology o/ East-Central Nevada, pp. 229- water supplying Muddy River Springs is de- 231, Intermountain Association of Petroleum Geologists, 1960. rived from within the boundaries of the re- Bauer, H. L., Jr., J. J. Cooper, and R. A. Brett- gional groundwatersystem as describedin this rick, Porphyry copper deposits in the Robinson report. Mining District, White Pine County, Nevada, in Guidebook to the Geology o/ East-Central CLOSING STATENlENT Nevada, pp. 220-228, Intermountain Association of Petroleum Geologists, 1960. The regional interbasin groundwatersystem Boettcher, J. W., and W. W. Sloan, Jr., editors, here describedreasonably explains several other- Guidebook to the Geology o/ East-Central wise anomalous occurrencesof large natural Nevada, 278 pp., Intermountain Association of Petroleum Geologists, 1960. springdischarge in 'dry' areasand of very deep Bowyer, G., E. H. Pampeyan, and C. R. Long- water levels in valleys where at least limited well, Geologic map of Clark County, Nevada, natural discharge of groundwater by evapo- U.S. Geol. Surv. Mineral Inv. Field Studies transpirationordinarily would be expected.The Map MF-138, 1958. identification of this regional system is provi- Carpenter, Everett, Groundwater in southeastern Nevada, U.S. Geol. Surv. Water-Supply Paper sional in that it is based largely on indirect 365, 86 pp., 1915. methods and limited data. However, the gross Cook, E. 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