The Oldest Stratigraphic Units in The

The oldest stratigraphic units in the study area the Devonian- and Mississippian-age Englewood For- are the Precambrian igneous and metamorphic rocks mation because of the absence of the Ordovician (fig. 9), which underlie the Paleozoic, Mesozoic, and sequence. The Englewood Formation is overlain by the Cenozoic rocks and sediments. These Precambrian Madison Limestone. rocks range in age from 1.7 to about 2.5 billion years The Mississippian-age Madison Limestone is a and were eroded to a gentle undulating plain at the massive, gray to buff limestone that is locally dolomitic beginning of the Paleozoic Era (Gries, 1996). The Pre- (Strobel and others, 1999). The Madison Limestone, cambrian rocks are highly variable in composition and which was deposited as a marine carbonate, was are composed mostly of metasediments, such as schists exposed at land surface for approximately 50 million and graywackes. The Paleozoic and Mesozoic rocks years. During this period, significant erosion, soil were deposited on the Precambrian rocks as nearly hor- development, and karstification occurred (Gries, 1996). izontal beds. Subsequent uplift during the Laramide There are numerous caves and fractures within the orogeny and related erosion exposed the Precambrian upper part of the formation (Peter, 1985). The thickness rocks in the central core of the Black Hills, with many of the Madison Limestone increases from south to of the Paleozoic and Mesozoic sedimentary rocks north in the study area and ranges from almost zero in exposed in roughly concentric rings around the core. the southeast corner of the study area (Rahn, 1985) to The exposed Precambrian rocks commonly are referred 1,000 ft east of Belle Fourche (Carter and Redden, to as the crystalline core. 1999d). Because the Madison Limestone was exposed The layered series of sedimentary rocks sur- to erosion and karstification for millions of years, its rounding the crystalline core includes outcrops of the contact with the overlying Minnelusa Formation is Madison Limestone (also locally known as the unconformable. Pahasapa Limestone) and the Minnelusa Formation. The Pennsylvanian- and Permian-age Minnelusa The bedrock sedimentary formations typically dip away from the uplifted Black Hills (fig. 15) at angles Formation consists mostly of yellow to red cross- that can approach or exceed 15 to 20 degrees near the stratified sandstone, limestone, dolomite, and shale outcrops, and decrease with distance from the uplift to (Strobel and others, 1999). In addition to sandstone and less than 1 degree (Carter and Redden, 1999a, 1999b, dolomite, the middle part of the formation consists of 1999c, 1999d, 1999e). Following are descriptions for shale and anhydrite (DeWitt and others, 1986). The the bedrock formations that contain major aquifers in upper part of the Minnelusa Formation also may con- the Black Hills area. tain anhydrite, which generally has been removed by The oldest sedimentary unit in the study area is dissolution in or near the outcrop areas, occasionally the Cambrian- and Ordovician-age Deadwood Forma- forming collapse features filled with breccia (Brad- tion, which is composed primarily of brown to light- dock, 1963). The Minnelusa Formation was deposited gray glauconitic sandstone, shale, limestone, and local in a coastal environment, and dune structures at the top basal conglomerate (Strobel and others, 1999). These of the formation may represent beach sediments (Gries, sediments were deposited on top of a generally hori- 1996). The thickness of the Minnelusa Formation zontal plain of Precambrian rocks in a coastal- to near- increases from north to south and ranges from 375 ft shore environment (Gries, 1975). The thickness of the near Belle Fourche to 1,175 ft near Edgemont in the Deadwood Formation increases from south to north in study area (Carter and Redden, 1999c). In the north- the study area and ranges from 0 to 500 ft (Carter and eastern part of the central Black Hills, little anhydrite Redden, 1999e). In the northern and central Black occurs in the subsurface due to a change in the deposi- Hills, the Deadwood Formation is disconformably tional environment. On the south and southwest side of overlain by Ordovician rocks, which include the the study area, the thickness of clastic units increases Whitewood and Winnipeg Formations. The Winnipeg and a thick section of anhydrite occurs. In the southern Formation is absent in the southern Black Hills, and the Black Hills, the upper part of the Minnelusa Formation Whitewood Formation has eroded to the south and is thins due to leaching of anhydrite. The Minnelusa not present south of the approximate latitude of Nemo Formation is disconformably overlain by the Permian- (DeWitt and others, 1986). In the southern Black Hills, age Opeche Shale, which is overlain by the Minnekahta the Deadwood Formation is unconformably overlain by Limestone.

18 Hydrology of the Black Hills Area, South Dakota

SEA 7,000 6,000 5,000 4,000 3,000 2,000 1,000 FEET LEVEL

A' QTac Kps R T Ps

QTac

Rapid Creek Rapid Rapid City Rapid Kik 14. Abbreviations for stratigraphic intervals stratigraphic for Abbreviations 14.

Ju Pmk

Po Rapid Creek Rapid PPm

MDme

Rapid Creek Rapid OCd

Rapid Creek Rapid Rapid Creek Rapid KILOMETERS 4 Location of section is Locationshownsection in figure of pCu 46 2 6 8 10 MILES 2810 0 0

(modified from Strobel and others, 1999). ′ South Fork Castle Creek Castle Fork South

OCd South Fork Castle Creek Castle Fork South pCu 9.

PPm

MDme

Geologic cross section A-A Geologic LIMESTONE PLATEAU LIMESTONE

SOUTH DAKOTA SOUTH

VERTICAL EXAGGERATION X5 EXAGGERATION VERTICAL WYOMING A SEA 7,000 6,000 5,000 4,000 3,000 2,000 1,000 FEET LEVEL Figure 15 Figure are explained in figure

Geologic Framework 19 The Permian-age Minnekahta Limestone is a Paleozoic aquifers occurs in high-altitude outcrop areas fine-grained, purple to gray laminated limestone around the major uplifts such as the Black Hills uplift (Strobel and others, 1999), which ranges in thickness (fig. 17). from 25 to 65 ft in the study area. The Minnekahta The Cambrian-Ordovician (or Deadwood) Limestone is overlain by the Triassic- and Permian-age aquifer is contained within the sandstones of Cambrian Spearfish Formation. age (Deadwood Formation and equivalents) and lime- The Cretaceous-age Inyan Kara Group consists stones of Ordovician age (Red River Formation and of the Lakota Formation and overlying Fall River equivalents) (fig. 12). Generally, flow in the Cambrian- Formation. The Lakota Formation consists of the Ordovician aquifer is from the high-altitude recharge Chilson, Minnewaste Limestone, and Fuson Shale areas to the northeast. Discharge (fig. 17) from the members. The Lakota Formation consists of yellow, Cambrian-Ordovician aquifer is to adjacent aquifers, brown, and reddish-brown massive to thinly bedded lakes and springs in eastern North Dakota, and springs sandstone, pebble conglomerate, siltstone, and clay- and seeps where the aquifer crops out in Canada stone of fluvial origin (Gott and others, 1974); locally (Downey, 1984). Within the Great Plains region, the there are lenses of limestone and coal. The Fall River Cambrian-Ordovician aquifer contains fresh water Formation is a brown to reddish-brown, fine-grained (dissolved solids concentrations less than 1,000 mg/L sandstone, thin bedded at the top and massive at the (milligrams per liter)) only in an area surrounding the bottom (Strobel and others, 1999). The thickness of the Black Hills and in a small area in north-central Wyo- Inyan Kara Group ranges from 135 to 900 ft in the study area (Carter and Redden, 1999a). ming (Whitehead, 1996). The aquifer is a brine (dissolved solids concentration greater than 35,000 mg/L) in eastern Montana and western and central North Ground-Water Framework Dakota (Whitehead, 1996). The Mississippian (or Madison) aquifer is con- The hydrogeologic setting of the Black Hills area tained within the limestones, siltstones, sandstones, is schematically illustrated in figure 16, and the areal and dolomite of the Madison Limestone or Group. distribution of the hydrogeologic units is shown in Generally, water in the Mississippian aquifer is con- figure 14. Four of the major aquifers in the Black Hills fined except in outcrop areas. Flow in the Mississippian area (Deadwood, Madison, Minnelusa, and Inyan Kara aquifer generally is from the recharge areas to the aquifers) are regionally extensive and are discussed in northeast. Discharge (fig. 17) from the Mississippian the following sections in the context of regional and aquifer occurs by upward leakage to the lower Creta- local hydrologic settings. A fifth major aquifer ceous aquifer in central South Dakota and eastern flow (Minnekahta aquifer) generally is used only locally, as to the Cambrian-Ordovician aquifer in eastern North are aquifers in the igneous and metamorphic rocks Dakota (Downey, 1984). Water in the Mississippian within the crystalline core area and in alluvium. In aquifer is fresh only in small areas near recharge areas some local areas, wells are completed in strata that and becomes saline to slightly saline as it moves down- generally are considered to be semiconfining and gradient. The water is a brine with dissolved solids con- confining units. centrations greater than 300,000 mg/L in the deep parts of the Williston Basin (Whitehead, 1996). Regional Aquifers The Pennsylvanian (or Minnelusa) aquifer is The major aquifers underlie parts of Montana, contained within the sandstones and limestones of the North Dakota, South Dakota, Wyoming, and Canada. Minnelusa Formation, Tensleep Sandstone, Amsden The parts of the regional aquifers in Canada are not Formation, and equivalents of Pennsylvanian age described or shown in this report. (fig. 12). Water in the Pennsylvanian aquifer moves The Paleozoic aquifers include the Cambrian- from recharge areas to the northeast to discharge areas Ordovician aquifer (Deadwood aquifer in the Black in eastern South Dakota (Downey and Dinwiddie, Hills), Mississippian aquifer (Madison aquifer in 1988). Some water discharges by upward leakage to the the Black Hills), and the Pennsylvanian aquifer lower Cretaceous aquifer (Swenson, 1968, Gott and (Minnelusa aquifer in the Black Hills). Recharge to the others, 1974).

20 Hydrology of the Black Hills Area, South Dakota Alluvial aquifer Potentiometric surface of Madison aquifer Lateral outflow Leakage from/ leakage to ground-water sectionin shown outflowcomponents

Group m i Inyan Kara L

a o t i t h

MAJOR AQUIFER CONFINING UNIT SPRING a a k m e r n o

EXPLANATION n i F Limestone

Flowing well M Artesian springflow

a inflow s Lateral n lu o

e ground-water n is n d i a M M Spring conduit Cave

Formation Hills area. Schematic generally corresponds with geologiccross table Water

Deadwood Recharge et of the Madisonet aquiferare also shown components with inflow shownand in green

Headwater springflow PLATEAU n e o

n i Precambrian igneous and metamorphic rocks

t LIMESTONE o

t a

s m

F L

Schematic showing simplified hydrogeologicBlackthe setting of d

a 15. Components considered for hydrologic budg

Madison D Dip of sedimentary rocks exaggerated Relative thickness NOT TO SCALE Minnelusa Formation figure shownblue. in Figure 16 Figure

Ground-Water Framework 21

●

Falls Sioux ● iddie, 1988;

●

Fargo

Grand Forks Grand o EXPLANATION

★

100 Pierre ★

RECHARGE AREA DISCHARGE AREA FOR MADISON AND MINNELUSA (via adjacent aquifers) AQUIFERS DISCHARGE AREA FOR DEADWOOD AQUIFER springs, and seeps) (via adjacent aquifers, WITH DISSOLVED WATER EXTENT OF GROUND THAN GREATER SOLIDS CONCENTRATION 100,000 MILLIGRAMS PER LITER AQUIFER--Dashed EASTERN LIMIT OF DEADWOOD located where approximately FLOW DIRECTION OF GROUND-WATER

Bismarck

S O U T H D A K O T A T O K A D H T U O S

N O R T H D A K O T A T O K A D H T R O N Rapid City Rapid ● Basin

Williston

of ry

o a nd ou ★

B 105 te a m xi ro pp A Cheyenne em within Paleozoicem withinaquifer units (modifiedandfrom Downey Dinw ●

Casper ●

Billings

W Y O M I N G

110

M O N T A N A ●

Great Falls

o Base modified from U.S. Geological Survey digital data, 1:2,000,000, 1972

43 ★

Butte MILES ●

Helena 100 100 KILOMETERS 50

o 50 General directionground-water of inflow regional aquifer syst

115

0 0 .

48 Figure 17 Figure Whitehead, 1996).

22 Hydrology of the Black Hills Area, South Dakota Several sandstone units (fig. 13) compose the domestic and municipal users near its outcrop area, lower Cretaceous aquifer, which is known as the Inyan receives recharge primarily from precipitation on the Kara aquifer in South Dakota. Generally, water in the outcrop. There may be some hydraulic connection lower Cretaceous aquifer is confined by several thick between the Deadwood aquifer and the underlying shale layers except in aquifer outcrop areas around weathered Precambrian rocks, but regionally the structural uplifts, such as the Black Hills. Water in the Precambrian rocks act as a lower confining unit to the lower Cretaceous aquifer generally moves northeast- Deadwood aquifer. The Whitewood and Winnipeg For- erly from high-altitude recharge areas to discharge mations, where present, act as overlying semiconfining areas in eastern North Dakota and South Dakota units to the Deadwood aquifer (Strobel and others, (Whitehead, 1996). Although the aquifer is wide- 1999). The Whitewood and Winnipeg Formations spread, it contains little fresh water. Water is fresh only locally may transmit water and exchange water with in small areas in central and south-central Montana and the Deadwood aquifer, but regionally are not consid- north and east of the Black Hills uplift (Whitehead, ered aquifers. Where the Whitewood and Winnipeg 1996). More than one-half of the water in the lower Formations are absent, the Deadwood aquifer is in con- Cretaceous aquifer is moderately saline, and the water tact with the overlying Englewood Formation, which is very saline or a brine in the deep parts of the Will- was included as part of the Madison aquifer for this iston and Powder River Basins (Whitehead, 1996). study. Much of the saline water is believed to be from upward The Madison aquifer generally occurs within the leakage of mineralized water from the Paleozoic karstic upper part of the Madison Limestone, where aquifers. numerous fractures and solution openings have created extensive secondary porosity and permeability. Strobel and others (1999) included the entire Madison Lime- Local Aquifers stone and the Englewood Formation in their delineation Many of the sedimentary units contain aquifers, of the Madison aquifer. Thus, in this report, outcrops of both within and beyond the study area. Within the the Madison Limestone and Englewood Formation Paleozoic rock interval, aquifers in the Deadwood (fig. 14) are referred to as the outcrop of the Madison Formation, Madison Limestone, Minnelusa Formation, Limestone for simplicity. The Madison aquifer receives and Minnekahta Limestone are used extensively. These significant recharge from streamflow losses and precip- aquifers are collectively confined by the underlying itation on the outcrop. Low-permeability layers in the Precambrian rocks and the overlying Spearfish Forma- lower part of the Minnelusa Formation generally act as tion. Individually, these aquifers are separated by minor an upper confining unit to the Minnelusa aquifer. How- confining layers or by low-permeability layers within ever, karst features in the upper part of the Madison the individual units. In general, ground-water flow in Limestone may have reduced the effectiveness of the these aquifers is radially outward from the central core overlying confining unit in some locations. of the Black Hills. Although the lateral component of The Minnelusa aquifer occurs within layers of flow generally predominates, the vertical component of sandstone, dolomite, and anhydrite in the lower portion flow, and thus leakage between these aquifers, can be of the Minnelusa Formation and sandstone and anhy- extremely variable (Peter, 1985; Greene, 1993). drite in the upper portion. The Minnelusa aquifer has Although the Precambrian basement rocks primary porosity in the sandstone units and secondary generally have low permeability and form the lower porosity from collapse breccia associated with dissolu- confining unit for the series of sedimentary aquifers tion of interbedded evaporites and fracturing. The (fig. 16), localized aquifers occur in many locations in Minnelusa aquifer receives significant recharge from the crystalline core of the Black Hills, where enhanced streamflow losses and precipitation on the outcrop. secondary permeability has resulted from weathering Streamflow recharge to the Minnelusa aquifer gener- and fracturing. Where the Precambrian rocks are satu- ally is less than to the Madison aquifer (Carter, rated, unconfined (water-table) conditions generally Driscoll, and Hamade, 2001), which is preferentially occur and topography can strongly control ground- recharged because of its upslope location. The Min- water flow directions. nelusa aquifer is confined by the overlying Opeche The Deadwood Formation contains the Dead- Shale. wood aquifer, which overlies the Precambrian rocks. Both the Madison and Minnelusa aquifers are The Deadwood aquifer, which is used mainly by potential sources for numerous large artesian springs in

Ground-Water Framework 23 the Black Hills area, and hydraulic connections within the outcrop of the Minnelusa Formation between the two aquifers are possible in other locations (Hortness and Driscoll, 1998). Large artesian springs, (Naus and others, 2001). Ground-water flowpaths and originating primarily from the Madison and Minnelusa velocities in both aquifers are influenced by anisotropic aquifers, occur in many locations downgradient from and heterogeneous hydraulic properties caused by these loss zones, most commonly within or near the secondary porosity. outcrop of the Spearfish Formation. These springs pro- The Minnekahta aquifer, which overlies the vide an important source of base flow in many streams Opeche Shale, typically is very permeable, but well beyond the periphery of the Black Hills (Rahn and yields can be limited by the small aquifer thickness. Gries, 1973; Miller and Driscoll, 1998). The Minnekahta aquifer receives significant recharge from precipitation on the outcrop and some additional recharge from streamflow losses. The overlying Characteristics and Properties of Major Aquifers Spearfish Formation acts as a confining unit to the Aquifer characteristics and properties for the aquifer and to other underlying Paleozoic aquifers. major aquifers in the study area (Deadwood, Madison, Hence, most of the artesian springs occur near the Minnelusa, Minnekahta, and Inyan Kara aquifers) are outcrop of the Spearfish Formation. presented in this section. Aquifer characteristics, Within the Mesozoic rock interval, the Inyan including areal extent, thickness, and storage volume, Kara Group comprises an aquifer that is used exten- are presented in table 1. Aquifer characteristics for the sively. Aquifers in various other units of the Mesozoic Precambrian aquifer also are presented because rock interval are used locally to lesser degrees. The numerous wells are completed in this aquifer in the Inyan Kara aquifer receives recharge primarily from crystalline core of the Black Hills. The areal extent of precipitation on the outcrop. The Inyan Kara aquifer the aquifers was determined using a geographic infor- also may receive recharge from leakage from the mation system (GIS) coverage by Williamson and underlying Paleozoic aquifers (Swenson, 1968; Gott and others, 1974). As much as 4,000 ft of Cretaceous others (2000) of the hydrogeologic unit map by Strobel shales act as the upper confining unit to aquifers in the and others (1999) for the study area. Mesozoic rock interval. Localized aquifers occur in the Precambrian Confined (artesian) conditions generally exist igneous and metamorphic rocks that make up the crys- within the sedimentary aquifers where an upper con- talline core of the Black Hills and are referred to collec- fining layer is present. Under confined conditions, tively as the Precambrian aquifer. The Precambrian water in a well will rise above the top of the aquifer in aquifer is not continuous, and ground-water flow is which it is completed. Flowing wells will result when mainly controlled by secondary permeability caused by drilled in areas where the water level, or potentiometric fracturing and weathering. The Precambrian aquifer is surface, is above the land surface. Flowing wells and considered to be contained in the area where the Pre- artesian springs that originate from confined aquifers cambrian rocks are exposed in the central core, which are common around the periphery of the Black Hills. has an area of approximately 825 mi2 in the study area. Numerous headwater springs originating from The thickness of the aquifer has been estimated by the Paleozoic units at high altitudes on the western side Rahn (1985) to be generally less than 500 ft, which was of the study area provide base flow for many streams. considered the average thickness (table 1). Wells in the These streams flow across the crystalline core of the Custer area have been completed at depths greater than Black Hills, and most streams generally lose all or part 1,000 ft, indicating that the Precambrian aquifer is of their flow as they cross the outcrops of the Madison Limestone (Rahn and Gries, 1973; Hortness and thicker in some locations. The Precambrian aquifer is Driscoll, 1998). Karst features of the Madison Lime- mostly unconfined, but may have locally confined con- stone, including sinkholes, collapse features, solution ditions. The area of the sedimentary aquifers is smaller cavities, and caves, are responsible for the Madison than the area of the Precambrian rocks because erosion aquifer’s capacity to accept recharge from streamflow. has removed the sedimentary rocks in the central core Large streamflow losses also occur in many locations of the Black Hills.

24 Hydrology of the Black Hills Area, South Dakota Table 1. Summary of the characteristics of major and Precambrian aquifers in the study area [mi2, square miles; ft, feet; acre-ft, acre-feet]

Estimated Maximum Average Area amount of formation saturated Effective Aquifer extent recoverable thickness thickness porosity1 (mi2) water in storage2 (ft) (ft) (million acre-ft)

Precambrian 35,041 -- 1500 0.01 2.6

Deadwood 4,216 500 226 .05 30.5

Madison 4,113 1,000 4521 .05 562.7

Minnelusa 3,623 1,175 6736 .05 570.9

Minnekahta 3,082 65 50 .05 4.9

Inyan Kara 2,512 900 310 .17 84.7

Combined storage for major and Precambrian aquifers 256.3

1From Rahn (1985). 2Storage estimated by multiplying area times average thicknesses times effective porosity. 3The area used in storage calculation was the area of the exposed Precambrian rocks, which is 825 mi2. 4Average saturated thickness of the confined area of the Madison aquifer. The unconfined area had an average saturated thickness of 300 ft. 5Storage values are the summation of storage in the confined and unconfined areas. 6Average saturated thickness of the confined area of the Minnelusa aquifer. The unconfined area had an average saturated thickness of 142 ft.

Large amounts of water are stored within the acre-ft. The largest storage volume is for the Inyan major aquifers, but not all of it is recoverable because Kara aquifer because of the large effective porosity some of the water is contained in unconnected pore (0.17). Storage in the Minnelusa aquifer is larger than spaces. Thus, effective porosity, which is the porosity in the Madison aquifer, primarily because of larger of a rock that consists of interconnected voids, was average saturated thickness. used in estimating the amount of recoverable water in Well yields (fig. 18) for the major aquifers were storage (table 1). Where aquifer units are not fully obtained from the USGS Ground Water Site Inventory saturated (generally in and near outcrop areas), the (GWSI) database. The mean well yields for the aqui- saturated thickness is less than the formation thickness fers generally are much higher than the median well and the aquifer is unconfined. For the Madison and yields because some well yields are very high. Well Minnelusa aquifers, it was possible to delineate the saturated thickness of the unconfined portions of these yields generally are lower for wells completed in the aquifers, as discussed later in this section. Average Precambrian rocks than the major aquifers because the saturated thicknesses of the unconfined and confined Precambrian aquifer is not continuous and most of the portions of the Madison and Minnelusa aquifers were available water is stored in fractures. The Madison used in storage estimates for these aquifers. For the aquifer has the potential for high well yields, and the other major aquifers, full saturation was assumed mean and median well yields are higher in the Madison because more detailed information was not available. aquifer than the other major aquifers. The Minnelusa The total volume of recoverable water stored in aquifer also has the potential for high well yields. Low the major aquifers (including the Precambrian aquifer) well yields are possible in some locations for all the within the study area is estimated as 256 million major aquifers.

Ground-Water Framework 25 561 137 166 433 64 246 10,000 5,000

2,000 1,000 EXPLANATION 500 561 Number of wells with yield data 200 Maximum 100 * 90th percentile 50 * * * 75th percentile 20 * Mean 10 * * Median 5 25th percentile 2 10th percentile 1 Minimum 0.5

0.2

WELL YIELD, IN GALLONS PER MINUTE YIELD, WELL 0.1 0.05

0.02 0.01 Precambrian Deadwood Madison Minnelusa Minnekahta Inyan Kara AQUIFER

Figure 18. Boxplots showing distribution of well yields from selected aquifers (data obtained from U.S. Geological Survey Ground Water Site Inventory database).

Aquifer properties, including hydraulic conduc- water flowpaths and velocities also are heavily influ- tivity, transmissivity, storage coefficient, and porosity, enced by anisotropic and heterogeneous hydraulic are presented in table 2 for the major aquifers and the properties of the Madison aquifer. Flowpaths are not Precambrian aquifer. The estimates presented for the necessarily orthogonal to equipotential lines because of various aquifer properties are based on previous highly variable directional transmissivities and may be studies. In general, the Madison aquifer has the highest further influenced by vertical flow components hydraulic conductivity and transmissivity estimates of between the Madison and Minnelusa aquifers. Long the major aquifers. Transmissivity and hydraulic con- (2000) described anisotropy in the Madison aquifer in ductivity also may be high in the Minnelusa aquifer. the Rapid City area that causes ground-water flow to be The Inyan Kara aquifer generally has the highest effec- nearly parallel to mapped equipotential lines in some tive porosity of the major aquifers. cases. Regional ground-water flow from the west may The potentiometric surfaces of the Madison and influence the potentiometric surface in both aquifers in Minnelusa aquifers are shown in figures 19 and 20, the northern and southwestern parts of the study area. respectively. In many locations, ground-water flow in Locations of artesian springs that probably originate these aquifers follows the bedding dip, which generally from ground-water discharge from the Madison or is radially away from the central part of the uplift. Minnelusa aquifers and have potential to influence Structural features, such as folds and faults, may have potentiometric surfaces also are shown in figures 19 local influence on ground-water flowpaths. Ground- and 20.

26 Hydrology of the Black Hills Area, South Dakota Table 2. Estimates of hydraulic conductivity, transmissivity, storage coefficient, and porosity from previous investigations [ft/d, feet per day; ft2/d, feet squared per day; --, no data; <, less than]

Total Hydraulic Transmissivity Storage porosity/ Source conductivity Area represented (ft2/d) coefficient effective (ft/d) porosity

Precambrian aquifer

Rahn, 1985 ------0.03/0.01 Western South Dakota

Galloway and Strobel, 2000 450 - 1,435 0.10/-- Black Hills area

Deadwood aquifer

Downey, 1984 -- 250 - 1,000 -- -- Montana, North Dakota, South Dakota, Wyoming

Rahn, 1985 ------0.10/0.05 Western South Dakota

Madison aquifer

Konikow, 1976 -- 860 - 2,200 -- -- Montana, North Dakota, South Dakota, Wyoming

Miller, 1976 -- 0.01 - 5,400 -- -- Southeastern Montana

Blankennagel and others, 1977 2.4x10-5 - 1.9 ------Crook County, Wyoming

Woodward-Clyde Consultants, -- 3,000 2x10-4 - 3x10-4 -- Eastern Wyoming, western South 1980 Dakota

Blankennagel and others, 1981 -- 5,090 2x10-5 -- Yellowstone County, Montana

Downey, 1984 -- 250 - 3,500 -- -- Montana, North Dakota, South Dakota, Wyoming

Plummer and others, 1990 -- -- 1.12x10-6 - 3x10-5 -- Montana, South Dakota, Wyo- ming

Rahn, 1985 ------0.10/0.05 Western South Dakota

Cooley and others, 1986 1.04 ------Montana, North Dakota, South Dakota, Wyoming, Nebr.

Kyllonen and Peter, 1987 -- 4.3 - 8,600 -- -- Northern Black Hills

Imam, 1991 9.0x10-6 ------Black Hills area

Greene, 1993 -- 1,300 - 56,000 0.002 0.35/-- Rapid City area

Tan, 1994 5 - 1,300 -- -- 0.05 Rapid City area

Greene and others, 1999 -- 2,900 - 41,700 3x10-4 - 1x10-3 -- Spearfish area

Carter, Driscoll, Hamade, and -- 100 - 7,400 -- -- Black Hills area Jarrell, 2001

Minnelusa aquifer

Blankennagel and others, 1977 <2.4x10-5 - 1.4 ------Crook County, Wyoming

Pakkong, 1979 -- 880 -- -- Boulder Park area, South Dakota

Woodward-Clyde Consultants, -- 30 - 300 6.6x10-5 - 2.0x10-4 -- Eastern Wyoming, western South 1980 Dakota

Ground-Water Framework 27 Table 2. Estimates of hydraulic conductivity, transmissivity, storage coefficient, and porosity from previous investigations–Continued [ft/d, feet per day; ft2/d, feet squared per day; --, no data; <, less than]

Total Hydraulic Transmissivity Storage porosity/ Source conductivity Area represented (ft2/d) coefficient effective (ft/d) porosity

Minnelusa aquifer—Continued

Rahn, 1985 ------0.10/0.05 Western South Dakota

Kyllonen and Peter, 1987 -- 0.86 - 8,600 -- -- Northern Black Hills

Greene, 1993 -- 12,000 0.003 0.1/-- Rapid City area

Tan, 1994 32 ------Rapid City area

Greene and others, 1999 -- 267 - 9,600 5.0x10-9 - 7.4x10-5 -- Spearfish area

Carter, Driscoll, Hamade, and -- 100 - 7,400 -- -- Black Hills area Jarrell, 2001

Minnekahta aquifer

Rahn, 1985 ------0.08/0.05 Western South Dakota

Inyan Kara aquifer

Niven, 1967 0 - 100 ------Eastern Wyoming, western South Dakota

Miller and Rahn, 1974 0.944 178 -- -- Black Hills area

Gries and others, 1976 1.26 250 - 580 2.1x10-5 - 2.5x10-5 -- Wall area, South Dakota

Boggs and Jenkins, 1980 -- 50 - 190 1.4x10-5 - 1.0x10-4 -- Northwestern Fall River County

Bredehoeft and others, 1983 8.3 -- 1.0x10-5 -- South Dakota

Rahn, 1985 ------0.26/0.17 Western South Dakota

Kyllonen and Peter, 1987 -- 0.86 - 6,000 -- -- Northern Black Hills

28 Hydrology of the Black Hills Area, South Dakota o 104o 45' 103 30' Indian Horse o Belle Fourche EXPLANATION 44 45' Reservoir Cr Owl Newell OUTCROP OF MADISON LIME- BELLE Creek Creek STONE (from Strobel and Nisland F others, 1999) BELLE FOURCHE O UR CHE RIVER Hay Creek 3,400 MADISON LIMESTONE PRESENT, R 3,500 E BUTTE CO Vale BUT OVERLAIN BY SURFICIAL 3,700 3,600 R I V TER LAWRENCE CO MEADE CO Mirror REDWA DEPOSITS (from Carter and Lake Cox Old Spearfish and Lake Hatchery Saint Creek Redden, 1999d) McNenny Crow Higgins Gulch Onge Rearing Creek Spring reek MADISON LIMESTONE ABSENT Pond Gulch Spearfish C 3,200 30' (from Carter and Redden, 1999d) Whitewood Gulch 3,800

4,200 Bottom 3,000 4,000 Creek e 3,000 ls POTENTIOMETRIC CONTOUR-- Bear a Creek 4,400 4,600 F 4,800 Whitewood Butte Shows altitude at which water 5,000Higgins Cr Creek 5,200 Squ STURGIS Spearfish a Central Tinton w would have stood in tightly cased, Cr City li Iron Cr ka o ood DEADWOOD l Cr w A 15' 103 nonpumping wells (modified from ad Beaver Cr e D Cr Lead Bear h5,400 nnie Cr Strobel and others, 2000a). 5,600 s A erry 4,800 i trawb f S r Cr Creek Tilford 5,800 a Contour interval 100, 200, or e Whitetail 4,600 p Elk Elk Creek 2,800 S 2,600 4,400 Springs 500 feet, where appropriate. 6,000 Little Creek Roubaix ek Creek N Elk re Elk Dashed where inferred. Datum

Little . C 15' h F Boxelder fis o is sea level r r Piedmont

a k 4,200 6,200 e R Ellsworth p 4,400 a 3,400 S 3,600 Air Force S. Fork Rapid Cr p FAULT--Dashed where approxi- i 4,000 d Nemo Base 6,400 3,800

C Creek r Blackhawk mated. Bar and ball on down- Cold S 6,600 pri C ng ree s k Box Elder thrown side k For Rochford

6,400s d 4,200 a N. City o For Rapid ANTICLINE--Showing trace of axial h k Ca Springs R stle RAPID CITY Castle Cr plane and direction of plunge. Beav e Cleghorn/ Rapid r k Pactola Creek C C ree r C Jackson Dashed where approximated e re Reservoir e e 3,600 Creek k k Springs Castle V Deerfield ic Creek SYNCLINE--Showing trace of axial 6,600 toria S. Fork Reservoir Spring o r 4,000

44 C plane and direction of plunge. 6,400 l e 6,200 Cast 3,000

6,400 Rockerville Sheridan Creek Dashed where approximated 6,000 Creek Lake Hill City 6,600 Mt. Rushmore MONOCLINE--Showing trace of National 5,500 Keystone 5,000 Memorial axial plane. Dashed where yon an Spring Harney Hayward LIMESTONE PLATEAU C Peak n approximated 4,500 o x

y PENNINGTON CO n n Battle

o Spo Hermosa y k C an DOME--Symbol size approximately n CUSTER CO e a Creek Creek s C Battle le proportional to size of dome. o Grace Bear Creek B French Gulch Creek Spring Dome asymmetry indicated by CUSTER Grace Redbird e Gillette idg arrow length Creek Cool Coolidge 45' Jewel Cave CUSTER Creek National Spring ARTESIAN SPRING Monument Beaver STATE French Fairburn

4,000 PARK

Canyon 3,600 Creek 3,800 ighl 3,400 3,700 H an Lame Canyon d Creek 3,900 3,900 Pringle Wind Cave National Park Creek

3,200 WYOMING 3,800 Wind Johnny Cave Beaver SOUTH DAKOTA SOUTH Creek Dewey Beaver Red Spring Creek Buffalo Gap RIVER 30' Hell Creek Hot Brook Spring FALL RIVER CO H on 3,700 ot roo y Evans Plunge Spring B k Can HOT SPRINGS Minnekahta Fall Oral R 3,600 CHEYENNE 3,500 Cascade Cool Spring Springs 3,400 Cascade Springs Edgemont Horsehead Angostura o Creek Reservoir Creek 43 15' d oo w n o tt o Igloo Creek C Provo

Hat 01020MILES Base modified from U.S. Geological Survey digital data, 1:100,000, 1977, 1979, 1981, 1983, 1985 Rapid City, Office of City Engineer map, 1:18,000, 1996 01020KILOMETERS Universal Transverse Mercator projection, zone 13

Figure 19. Potentiometric surface of the Madison aquifer and locations of major artesian springs.

Ground-Water Framework 29 o 104o 45' 103 30'

Horse Indian 2,800 o Belle Fourche EXPLANATION 44 45' Reservoir Cr OUTCROP OF MINNELUSA Owl Newell BELLE Creek Creek FORMATION (modified from Nisland F Strobel and others, 1999) BELLE FOURCHE O UR CHE RIVER Hay Creek MINNELUSA FORMATION R Vale E BUTTE CO PRESENT, BUT OVERLAIN BY R I V Mirror TER LAWRENCE CO MEADE CO Lake REDWA SURFICIAL DEPOSITS (from Old Spearfish 3,200 and Cox 3,600 3,000 Carter and Redden, 1999c) Hatchery Saint Creek McNenny Lake Crow Higgins Gulch Onge Rearing 3,400 Creek Spring MINNELUSA FORMATION Pond reek Gulch Spearfish C 30'4,200 3,600 ABSENT (from Carter and 4,000 4,200 Whitewood Gulch 3,800 Redden, 1999c) Bottom Creek e 4,000 ls Bear 5,000 4,400 a Creek 3,000 4,600 F POTENTIOMETRIC CONTOUR-- 4,800 Whitewood Butte Higgins Cr Creek Squ STURGIS Shows altitude at which water a Central Tinton Cr w i Iron CityCr 4,000 al d DEADWOOD lk o would have stood in tightly oo 3,800 Cr w A 15' 103 ad Beaver Cr e cased, nonpumping wells D Cr Lead Bear 3,600 h nnie Cr s A erry i trawb f S (modified from Strobel and r Cr Creek Tilford 2,800 6,000 a e Whitetail p Elk Elk Creek others, 2000b). Contour S 6,200 Springs 3,200 Littl interval 200 feet. Dashed where 6,400 Roubaix e Creek Spearfish Elk ek 6,400 N re Little C Elk . 3,000 inferred. Datum is sea level 15' F Boxelder o r k Piedmont R 3,400 FAULT--Dashed where approxi- a 6,600S. Fork Rapid Cr p Ellsworth i d Nemo Air Force mated. Bar and ball on down- C Base 3,800 Creek r Blackhawk Cold S 6,200 pri thrown side C ng ree s k Box Elder k For Rochford s adN ANTICLINE--Showing trace of axial o . For Rapid City h k Ca R stle Springs RAPID CITY plane and direction of plunge. Castle Cr Beav e Cleghorn/ Rapid r k Pactola Creek Dashed where approximated C C ree r C Jackson e re Reservoir e e Creek k k Springs Castle V SYNCLINE--Showing trace of axial 6,800 Deerfield ictoria Creek 6,400 Reservoir Spring o S. Fork r 3,800 plane and direction of plunge. 44 C e Creek 6,600 Castl Dashed where approximated Sheridan Creek Lake Rockerville Hill City MONOCLINE--Showing trace of 6,000 6,200 Mt. Rushmore National Keystone axial plane. Dashed where 6,200 Memorial 6,000 yon an Spring Harney Hayward

LIMESTONE PLATEAU approximated C n Peak 5,800o x

y PENNINGTON CO n n Battle

o Spo Hermosa DOME--Symbol size approximately y k C an 5,600n CUSTER CO e a Creek Creek proportional to size of dome. s Battle e C l 5,400 o Grace Bear Creek B 5,800 Dome asymmetry indicated by 6,000 French Gulch Creek Spring CUSTER Grace arrow length Redbird ge Gillette Coolid Coolidge 45' Jewel Cave CUSTER Creek ARTESIAN SPRING 4,200 National 5,400 Spring

Monument Beaver 4,800 STATE Fairburn

5,200 Creek

4,4004,600 PARK 3,800

Canyon

3,800 5,000 4,000 gh 3,400 Hi la Lame Canyon n Creek d 3,200 Pringle Wind Cave National Park 3,000

Creek WYOMING 2,800

4,800 Wind Johnny

Cave Beaver SOUTH DAKOTA SOUTH 4,600 Creek Dewey Beaver 2,600 Red 3,600 Spring 4,200

k Creek 4,400 o RIVER Hell o Buffalo Gap r 30' 3,600 B d Creek l

o FALL RIVER CO HotC Brook Spring H on Evans Plunge Spring ot roo y B k Can HOT SPRINGS Minnekahta Fall Oral R

CHEYENNE Cool SpringCascade Springs Cascade Springs

Edgemont Horsehead Angostura o Creek Reservoir Creek 43 15' d oo w n o tt 3,400 o Igloo Creek C Provo

Figure 20. Potentiometric surface of the Minnelusa aquifer and locations of major artesian springs.

30 Hydrology of the Black Hills Area, South Dakota Maps showing the saturated thickness of the aquifers exist in some formations such as the Sundance unconfined areas of the Madison and Minnelusa aqui- and Morrison Formations. These aquifers are referred fers are shown in figures 21 and 22, respectively. Both to as the Sundance and Morrison aquifers in this report. the Madison and Minnelusa aquifers are unconfined The Cretaceous-sequence confining unit mainly near their outcrops and confined (fully saturated) at includes shales of low permeability, such as the Pierre some distance downdip from their outcrops. In general, Shale; local aquifers in the Pierre Shale are referred to the saturated thickness is less than 200 ft for most of the as the Pierre aquifer in this report. Within the Graneros outcrop areas. These areas are especially susceptible to Group, the Newcastle Sandstone contains an important drought conditions, and the formations may even be minor aquifer referred to as the Newcastle aquifer. dry in these areas regardless of precipitation condi- Because water-quality characteristics (discussed in a tions. In most areas, the aquifers are fully saturated subsequent section of this report) are very different within a short distance downdip of the outcrops. How- between the Newcastle aquifer and the other units in ever, in the southwest part of the study area, neither the Graneros Group, data are presented for the New- aquifer is fully saturated for a distance of about 6 mi castle aquifer separately from the other units in the downdip of the respective outcrops. Graneros Group, known as the Graneros aquifer in this Although the Limestone Plateau area is a large report. recharge area for the Madison and Minnelusa aquifers, Tertiary intrusive units are present only in the saturated thicknesses generally are small within these northern Black Hills, and generally are relatively aquifers in this area. Very few wells have been success- impermeable, although “perched” ground water often fully completed in this area, especially within the is associated with intrusive sills. The White River Madison Limestone, where saturated conditions gener- aquifer consists of various discontinuous units of sand- ally occur only near the bottom of the formation. Satu- stone and channel sands along the eastern flank of the rated thicknesses are limited by the discharge of Black Hills and is considered a minor aquifer where springs along the eastern edge of the Plateau and by saturated. Unconsolidated deposits of Tertiary or ground-water flow to the west. Fluctuations in ground- Quaternary age, including alluvium, colluvium, and water levels in this area generally are smaller than other wind-blown deposits, all have the potential to be local areas. aquifers where they are saturated.

Overview of Other Aquifers In addition to the major aquifers, many other Surface-Water Framework aquifers are used throughout the study area. The New- castle Sandstone, White River Group, and the uncon- Streamflow within the study area is highly influ- solidated units are considered aquifers where saturated enced by climatic and geologic conditions. The base (Strobel and others, 1999). In addition, many of the flow of most streams in the Black Hills originates in the semiconfining and confining units shown in figure 14 higher altitudes, where relatively large precipitation may contain local aquifers. This section provides a and small evapotranspiration result in more water being brief overview from Strobel and others (1999) of other available for springflow and streamflow. Many streams aquifers in the study area that are contained in various have headwater springs originating from the Paleozoic units from oldest to youngest. carbonate rocks on the western side of the study area. The Whitewood Formation, where present, may Most of these streams flow in a generally eastward contain a local aquifer, but seldom is used because of direction across the Precambrian rocks of the crystal- more reliable sources in the adjacent Madison or line core and subsequently lose all or part of their flow Deadwood aquifers. Local aquifers may exist in the where Paleozoic outcrops are crossed farther down- Spearfish confining unit where gypsum and anhydrite stream (Rahn and Gries, 1973). Large artesian springs have been dissolved, increasing porosity and perme- occur in many locations downgradient from loss zones, ability; these aquifers are referred to as the Spearfish most commonly within or near the outcrop of the aquifer in this report. The Jurassic-sequence semicon- Spearfish Formation. These springs provide an impor- fining unit consists of shales and sandstones. Overall, tant source of base flow in many streams beyond the this unit is semiconfining because of the low perme- periphery of the Black Hills (Rahn and Gries, 1973; ability of the interbedded shales; however, local Miller and Driscoll, 1998).

Surface-Water Framework 31 o 104o 45' 103 30' Indian Horse o Belle Fourche EXPLANATION 44 45' Reservoir Cr Owl Newell OUTCROP OF MADISON LIME- BELLE Creek Creek STONE (from Strobel and others, Nisland F 1999) BELLE FOURCHE O UR CHE RIVER

Hay Creek MADISON LIMESTONE ABSENT R E BUTTE CO Vale (from Carter and Redden, 1999d) I V ER R MEADE CO WAT LAWRENCE CO RED SATURATED THICKNESS OF Cox Saint Creek Lake Crow Onge MADISON LIMESTONE, IN Creek FEET (from Clawges, 2000a) reek Gulch Spearfish C 30' Less than 200 Whitewood Gulch

Bottom Creek e 200 to 400 ls Bear a Creek F Whitewood Butte Higgins 400 to 600 Cr Creek Squ STURGIS Spearfish a Central Tinton w Cr City li Iron Cr ka o ood DEADWOOD l 600 to 800 Cr w A 15' 103 ad Beaver Cr e D Cr Lead Bear h nnie Cr s A berry Fully saturated i traw f S r Cr Creek Tilford a e Whitetail p Elk S

Little Creek Roubaix ek Creek N Elk re Elk

Little . C 15' h F Boxelder fis o r r Piedmont a k e R Ellsworth p a S Air Force S. Fork Rapid Cr p i d Nemo Base

C Creek r Blackhawk Cold S pri ng Cre s ek k Box Elder For Rochford s adN o . For Rapid h k Ca R stle RAPID CITY Castle Cr Beav e Rapid r k Creek C e Pactola r C C re e r Reservoir e ee Creek k k Castle V Deerfield ictoria Creek Reservoir Spring o S. Fork r 44 C l e Cast Rockerville Sheridan Creek Creek Lake Hill City Mt. Rushmore National Keystone Memorial o ny n Spring Harney LIMESTONE PLATEAU a Hayward C n Peak

o x

y n PENNINGTON CO n Battle

a o po Hermosa y S k C a n CUSTER CO ne a Creek Creek s C le o Grace Bear B French Creek CUSTER Gulch Redbird e Gillette idg Creek Cool 45' Jewel Cave CUSTER National

Monument Beaver STATE French Fairburn

PARK

Canyon Creek gh Hi la Lame Canyon n Creek d Pringle Wind Cave National Park

Creek WYOMING

Wind Johnny

Cave SOUTH DAKOTA SOUTH Dewey Beaver Red Creek Buffalo Gap RIVER 30' Hell Creek

FALL RIVER CO H on ot roo y B k Can HOT SPRINGS Minnekahta Fall Oral R

CHEYENNE Cascade Springs

Edgemont Horsehead Angostura o Creek Reservoir Creek 43 15' d oo w n o tt o Igloo Creek C Provo

Figure 21. Saturated thickness of the Madison aquifer.

32 Hydrology of the Black Hills Area, South Dakota o 104o 45' 103 30' Indian Horse o Belle Fourche EXPLANATION 44 45' Reservoir Cr Owl Newell OUTCROP OF MINNELUSA FORMATION BELLE Creek Creek (from Strobel and others, 1999) Nisland F BELLE FOURCHE O UR MINNELUSA FORMATION ABSENT CHE RIVER

Hay Creek (from Carter and Redden, 1999c) R

E BUTTE CO Vale I V ER R MEADE CO SATURATED THICKNESS OF REDWAT LAWRENCE CO Cox MINNELUSA FORMATION, IN FEET Saint Creek Lake Crow Onge (from Clawges, 2000b)

Creek reek Less than 200 30' Gulch Spearfish C Whitewood Gulch 200 to 400

Bottom Creek e ls Bear a Creek 400 to 600 F Whitewood Butte Higgins Cr Creek Squ STURGIS Spearfish a Central 600 to 800 Tinton Cr w i Iron CityCr al od DEADWOOD lk o Cr o A dw 15' 103 a 800 to 1,000 Beaver Cr e D Cr Lead Bear h nnie Cr s A erry i trawb f S r Cr Creek Tilford 1,000 to 1,200 a e Whitetail p Elk S Fully saturated Little Creek Roubaix ek Creek N Elk re Elk

Little . C 15' h F Boxelder No data fis o r r Piedmont a k e R Ellsworth p a S Air Force S. Fork Rapid Cr p i d Nemo Base

C Creek r Blackhawk Cold S pri Cr ng ee s k Box Elder k For Rochford s adN o . For Rapid h k Ca R stle RAPID CITY Castle Cr Beav e Rapid r k Creek C C ee Pactola r C r e re Reservoir e e Creek k k Castle V Deerfield ictoria Creek Reservoir Spring o S. Fork r 44 C l e Cast Rockerville Sheridan Creek Creek Lake Hill City Mt. Rushmore National Keystone Memorial yon n Spring Harney Hayward

LIMESTONE PLATEAU a C n Peak

o x

y n PENNINGTON CO n Battle

a o Spo Hermosa

y k C a n CUSTER CO ne a Creek Creek s C le o Grace Bear B French Creek CUSTER Gulch Redbird e Gillette idg Creek Cool 45' Jewel Cave CUSTER National

Monument Beaver STATE French Fairburn

PARK

Canyon Creek gh Hi la Lame Canyon n Creek d Pringle Wind Cave National Park

Creek WYOMING

Wind Johnny

Cave SOUTH DAKOTA SOUTH Dewey Beaver Red

k Creek

o RIVER Hell o Buffalo Gap r 30' B d Creek l

C FALL RIVER CO H on ot roo y B k Can HOT SPRINGS Minnekahta Fall Oral R

CHEYENNE Cascade Springs

Edgemont Horsehead Angostura o Creek Reservoir Creek 43 15' d oo w n o tt o Igloo Creek C Provo

Figure 22. Saturated thickness of the Minnelusa aquifer.

Surface-Water Framework 33 Five hydrogeologic settings have been identified numerous Tertiary intrusives in the northern Black for the Black Hills area that influence both stream- Hills (fig. 14). Unconsolidated Quaternary and Tertiary flow (Driscoll and Carter, 2001) and water-quality deposits also occur in various locations. Within this set- (Williamson and Carter, 2001) characteristics. These ting, ground-water discharge contributes to base flow settings are described in the following section, which is of many streams; however, base flow can diminish followed by sections describing streamflow losses and rather quickly during periods of minimal precipitation. streamflow regulation, both of which have large influence on many area streams. The loss-zone setting consists of areas that are heavily influenced by streamflow losses that occur as streams cross outcrops of the Madison Limestone and Hydrogeologic Settings Minnelusa Formation. The outer extent of this area is The five hydrogeologic settings identified for the represented by the outer extent of the outcrop of the Black Hills area include the limestone headwater, crys- Inyan Kara Group (fig. 23). This same area is used to talline core, loss zone, artesian spring, and exterior set- represent the artesian spring setting because many arte- tings, which are represented by four areas (fig. 23). The sian springs are located along stream channels that also loss zone and artesian spring settings have distinctly are influenced by streamflow losses. Most artesian different streamflow characteristics but share a springs are located downgradient from the outcrop of common area because many artesian springs are the Minnelusa Formation (fig. 23). Complex interac- located along stream channels that also are influenced tions between bedrock aquifers, alluvial aquifers, and by streamflow losses. Locations of representative surface water can occur within this setting. streamflow-gaging stations for the five hydrogeologic No artesian springs are known to be located settings, which are used in subsequent descriptions of beyond the outcrop of the Inyan Kara Group; the area streamflow and water-quality characteristics, also are beyond this outcrop is referred to as the exterior setting. shown in figure 23. Within this setting, the influence of ground water on The limestone headwater setting is considered to streamflow generally is relatively minor or negligible, be within or near the Limestone Plateau area (fig. 23), with the exception of upstream influences from stream- where large outcrops of the Madison Limestone and Minnelusa Formation occur in a high-altitude area of flow losses or artesian springs. Many streams also are generally low relief, along the South Dakota-Wyoming influenced by irrigation withdrawals or other forms of border. Most of the limestone headwater springs occur regulation, as described in a subsequent section. near the eastern edge of the Limestone Plateau in areas where the contact between the Madison Limestone and Streamflow Losses underlying geologic units (fig. 9) is exposed (fig. 14). Streamflow losses influence the flow of most Various low-permeability layers in the underlying units streams that cross Paleozoic outcrops, especially the can act as confining layers, which result in lateral Madison Limestone and Minnelusa Formation. Most movement of ground water prior to discharge as spring- streams lose all of their flow up to some loss threshold. flow. Most recharge for these headwater springs is from infiltration of precipitation on outcrops of the Madison When streamflow exceeds this threshold, flow is main- Limestone and Minnelusa Formation. Ground-water tained through the loss zones. Loss thresholds for most discharge from the Deadwood aquifer also can con- large streams were quantified by Hortness and Driscoll tribute to springflow. Sustained streamflow within the (1998) and are summarized in table 3. Individual loss Madison and Minnelusa outcrops is very uncommon thresholds range from negligible (no loss) to as much as 3 (Driscoll and Carter, 2001) and generally occurs only 50 ft /s. Streamflow losses can occur along Iron Creek in limited areas where low permeability “perching” and Higgins Gulch; however, loss thresholds are noted layers occur. Small perched springs are common espe- as zero because these streams receive net ground-water cially within outcrops of the Minnelusa Formation discharge from the Madison and Minnelusa aquifers. along the Limestone Plateau. Newton and Jenny (1880) observed losses in White- The crystalline core setting consists primarily of wood Creek; however, loss zones apparently were igneous and metamorphic Precambrian rocks within sealed by fine-grained mine tailings that have been dis- the central part of the Black Hills, but also includes charged to the stream (Hortness and Driscoll, 1998).

34 Hydrology of the Black Hills Area, South Dakota 06436700 o EXPLANATION 104o 45' 103 30' CONNECTED OUTCROP OF Indian Horse o Belle Fourche MADISON LIMESTONE-- 44 45' Reservoir Cr Owl Newell Excludes erosional remnants BELLE Creek Creek (modified from Strobel and 06433500 Nisland F 06436760 BELLE FOURCHE O others, 1999) UR CHE RIVER

Hay Creek CONNECTED OUTCROP OF R

E BUTTE CO Vale Mirror06430532 R I V MINNELUSA FORMATION-- TER LAWRENCE CO MEADE CO Lake RED06430540WA Excludes erosional remnants and Cox Old Spearfish McNenny Lake Hatchery Saint Creek (modified from Strobel and Rearing Crow Higgins Gulch Onge Pond 06429905Creek Spring others, 1999) reek Gulch Spearfish C 06437500 30'

Sand HYDROGEOLOGIC SETTINGS Whitewood Gulch

Bottom Limestone headwater Cr Creek e ls Bear a Creek F Whitewood Butte Crystalline core Higgins Cr 06430898 Creek Squ STURGIS Spearfish a Central Tinton w Cr City li Iron Cr ka o Loss zone and artesian 06436156ood DEADWOOD l Cr w A 15' 103 ad 06430850Beaver Cr e spring--Bounded by outer Cold D Cr Lead Bear h nnie Cr 06437020 s A wberry i Stra extent of Inyan Kara Group, f 06430800r Cr Creek Tilford a e Whitetail p 06424000Elk which approximates outer 06430770S Elk Creek Little extent of the Black Hills area Creek Roubaix Creek Springs ek N Elk re Springs Elk

Little . C 15' h F Boxelder fis o Exterior r r Piedmont a k e R Ellsworth p a S Air Force S. Fork Rapid Cr p i d Nemo Base

C ARTESIAN SPRING Creek 06429500 r Blackhawk Creek 06422500 r06408700k 06423010 Box Elder Fo Rochford STREAMFLOW-GAGING ds a N. o For Rapid City Springs 06392900 h k Ca STATION USED FOR R stle RAPID CITY Castle Cr ANALYSIS OF STREAM- Cleghorn/ Rapid ek Pactola06412810Creek C C re r Reservoir Jackson FLOW CHARACTERISTICS-- 06409000ee Creek Creek k Springs Castle V Number is station Deerfield ictoria Creek Reservoir o S. Fork r 06407500 Sprin identification number 44 C g e Castl 06406920 Sheridan Rockerville 06408500 Limestone headwater Creek Lake Hill City 06408700 Mt. Rushmore Creek National Keystone Crystalline core Memorial Battle o ny n Spring Harney Creek 06403300 Beaver a Hayward LIMESTONE PLATEAU C Peak n Spring

o x 06404000 Loss zones

y n PENNINGTON CO n Battle

a o Spo Hermosa

y k 06408500 C a n CUSTER CO ne 06392950 a Creek Creek Artesian spring s C 06404800 le 06405800 o Grace Bear B 06402470 French06402995 Gulch Creek CUSTER Grace Exterior Redbird e ek Gillette 06404998 idg re Creek Cool Coolidge C 06400875 45' Jewel Cave CUSTER Creek

p National Spring

u 06403300 p Monument Beaver STATE

o French Fairburn STREAMFLOW-GAGING o

W PARK STATION USED FOR

Canyon Creek gh ANALYSIS OF WATER- Hi la Lame Stockade Canyon n Creek d QUALITY CHARACTER- Pringle Wind Cave National Park Creek ISTICS--Number is station WYOMING 06402430 identification number Wind

Beaver Cave 06402470 Johnny SOUTH DAKOTA SOUTH Dewey Beaver Limestone headwater Creek Red Creek 06408700 Creek Spring Buffalo RIVER 30' Hell Gap Crystalline core Hot Brook Spring 06402995 FALL RIVER CO H on ot roo ny Evans Plunge Spring Artesian spring B k Ca HOT SPRINGS 06412810 Minnekahta Fall 06402000 Oral R Exterior

CHEYENNE 06395000 Cool Spring Cascade Springs 06400497 Cascade 06395000 Springs Edgemont Horsehead Angostura o Creek Reservoir Creek 43 15' d oo w 06400000 n o tt o Igloo Creek C 06400875 Provo

Hat 01020MILES Base modified from U.S. Geological Survey digital data, 1:100,000, 1977, 1979, 1981, 1983, 1985 01020KILOMETERS Rapid City, Office of City Engineer map, 1:18,000, 1996 Universal Transverse Mercator projection, zone 13 Figure 23. Hydrogeologic settings for the Black Hills area. Locations of streamflow-gaging stations representative of the settings also are shown (from Driscoll and Carter, 2001). Surface-Water Framework 35 Table 3. Summary of loss thresholds from Black Hills Although most losses occur within outcrops of streams to bedrock aquifers the Madison Limestone and Minnelusa Formation, [From Hortness and Driscoll (1998). ft3/s, cubic feet per second] small losses may occur to other bedrock units. Losses to the Deadwood Formation are minimal. Losses to the Approximate loss Stream name threshold Minnekahta Limestone generally are small, relative to (ft3/s) losses to the Madison and Minnelusa Formations; how- Beaver Creek1 5 ever, they are difficult to quantify because of potential losses to extensive alluvial deposits that commonly are Highland Creek 10 located near Minnekahta Limestone outcrops. South Fork Lame Johnny Creek 1.4 Loss thresholds generally are relatively constant, without measurable effects from flow rate or duration North Fork Lame Johnny Creek 2.3 of flow through loss zones. Changes in loss thresholds French Creek 15 resulting from changes in channel conditions have been documented for Whitewood Creek (previously dis- Battle Creek 12 cussed), Grace Coolidge Creek, and Spring Creek Grace Coolidge Creek 21 (Hortness and Driscoll, 1998). The loss threshold for Grace Coolidge Creek probably was reduced by Bear Gulch1 .4 deposition of large quantities of fine-grained sediment Spokane Creek 2.2 mobilized after the Galena Fire, which occurred during Spring Creek 28 July 1988. Streamflow losses along Spring Creek apparently were temporarily reduced as a result of Rapid Creek 10 efforts to seal the channel with bentonite and rocks Victoria Creek 1.0 during 1937-40 (Brown, 1944).

Boxelder Creek 50 Streamflow Regulation Elk Creek 19 Many streams in the study area are affected by Little Elk Creek 3.3 withdrawals, diversions, or reservoir regulation. The Bear Gulch2 4 largest consumptive use of surface water within the study area is withdrawals for irrigation supplies 2 Beaver Creek 9 (Amundson, 1998). The largest withdrawals are associ- Iron Creek 0 ated with irrigation projects along Rapid Creek and the Cheyenne and Belle Fourche Rivers, where Bureau of Spearfish Creek 23 Reclamation storage reservoirs provide reliable water Higgins Gulch 0 supplies. Angostura Reservoir (fig. 1) supplies the Angostura Unit; Deerfield and Pactola Reservoirs False Bottom Creek 15 supply the Rapid Valley Project; and Keyhole (located Whitewood Creek 0 in northeastern Wyoming) and Belle Fourche Reser- voirs supply the Belle Fourche Project (Bureau of Bear Butte Creek 12 Reclamation, 1999). Details about these reservoirs, 1Located in southern Black Hills. along with storage records through 1993, were reported 2 Located in northern Black Hills. by Miller and Driscoll (1998). Large irrigation withdrawals also are made from Beaver Creek near Buffalo Gap and from Spearfish Creek and the Redwater River in the northern Black Hills, where streamflow is sufficiently reliable to provide consistent supplies. Smaller irrigation withdrawals are made from many other area streams.

36 Hydrology of the Black Hills Area, South Dakota Streamflow in many area streams is influenced water-quality characteristics. A brief discussion of by a variety of other generally non-consumptive diver- hydrologic processes relevant to the Black Hills area is sions and regulation mechanisms (such as smaller res- first presented. ervoirs). Diversions from Rapid, Elk, and Spearfish Creeks have historically provided water for mining operations (Homestake Mining Company) and munic- Hydrologic Processes ipal supplies (Central City, Deadwood, and Lead) in the A schematic diagram illustrating hydrologic pro- Whitewood Creek Basin (Miller and Driscoll, 1998). cesses is presented in figure 24. Precipitation falling on Homestake Mining Company also diverts water from the earth’s surface generally infiltrates into the soil Spearfish Creek for two hydroelectric power plants; horizon, unless the soil is saturated or the infiltration these flows are returned to Spearfish Creek below the capacity is exceeded, in which case overland flow or loss zone. Substantial withdrawals for municipal direct runoff will occur. Some water may be returned supplies also are made from Rapid Creek. from the soil horizon to the land surface through interflow, contributing to relatively short-term increases in streamflow. In the Black Hills area, where potential HYDROLOGIC PROCESSES AND evaporation generally exceeds precipitation, most CHARACTERISTICS water is eventually returned to the atmosphere through evapotranspiration (ET). Water infiltrating beyond the This section describes the characteristics of the root zone may eventually recharge ground-water sys- ground-water and surface-water resources in the study tems; however, ground-water discharge (in the form of area, including the response of ground water and springflow or seepage) also may contribute to stream- streamflow to variations in hydrologic conditions and flow.

Evapotranspiration Precipitation

Overland flow Evaporation Transpiration Interflow Infiltration Depression storage

Perched Interflow Soil horizon and Unsaturated water table colluvial deposits zone Springflow

Ground- Water table Stream channel water Saturated zone Bedrock Infiltration inflow aquifer Ground-water discharge to Ground- streams water Alluvial outflow Confining unit deposits

Total runoff

Figure 24. Schematic diagram illustrating hydrologic processes (modified from Driscoll and Carter, 2001).

Hydrologic Processes 37 In this report, the term runoff is used to include Most of these wells are in locations that may be all means by which precipitation eventually contributes affected by withdrawals from production wells. The to streamflow. Direct runoff includes overland flow Hermosa South Inyan Kara well (fig. 26G), with a and that portion of interflow that arrives in stream steady decline in water level of about 4 ft from 1983 to channels relatively quickly. Base flow generally 1998, is the only observation well in the Black Hills includes all ground water discharging to streams and area that shows a steadily declining trend throughout its also includes some interflow. Springflow is generally period of record. The Hermosa West Inyan Kara well considered to be ground-water discharge that occurs in (fig. 26F), which is located several miles farther north somewhat discrete and identifiable locations, as (fig. 25), does not show a similar decline. opposed to more general ground-water seepage. The water level at the Redwater Minnelusa well Streamflow is inclusive of runoff and also may include water from other sources such as diversions or well (fig. 26A) shows a seasonal response to withdrawals discharges. for irrigation, but generally recovers each year. The Within this report, streamflow is most commonly water level at the Boulder Canyon Minnelusa well expressed in units of cubic feet per second, but fre- (fig. 26B) declined steadily during the 1980’s and early quently is expressed in acre-feet per year (1.0 ft3/s 1990’s, but recovered during subsequent years. = 724.46 acre-ft for a year consisting of 365.25 days). The Sioux Park Madison well (fig. 26E) shows Units of acre-feet (1.0 ft over an acre, which is equiva- response to increased production by the city of Rapid lent to 43,560 ft2) are especially convenient for calcu- City from the Madison aquifer beginning in the late lating annual yield (annual runoff per unit of area), 1980’s. Recovery occurs during winter months when which generally is expressed in inches. production is reduced. An adjacent Minnelusa well shows no influence from production from the Madison aquifer; however, a decline during the 1990’s in the Ground-Water Characteristics Cement Plant Minnelusa well (fig. 26C) may be related to the increased production from the Madison aquifer. Water-level trends and comparisons for the major aquifers in the study area are described in this The Countryside Deadwood well (fig. 26D) is section. In addition, water-quality characteristics for located southwest of Rapid City in an area where sub- the major aquifers are described, and a brief summary stantial production from the Deadwood aquifer occurs. for other aquifers is provided. Increasing demand in this area occasionally has caused water-supply shortages during recent periods of peak Water-Level Trends and Comparisons demand; however, long-term water-level declines are not apparent. Well hydrographs provide information regarding temporal water-level trends, comparisons between Comparisons Between Madison and Minnelusa Aquifers aquifers, and water-level response to climatic conditions. Hydrographs (by calendar year) for 49 wells are In many locations, two or more observation presented in this section; the location of these wells is wells are colocated. The most common colocated wells shown in figure 25. On these hydrographs, solid lines are paired Madison and Minnelusa wells, which can indicate continuous records and dashed lines indicate provide information regarding interactions between periods with discontinuous records, which may be these aquifers. A variety of factors have potential to based only on periodic manual measurements in some contribute to reduced competency of confining layers cases. Hydrographs for 22 additional wells were pre- between the Madison and Minnelusa aquifers, which sented by Driscoll, Bradford, and Moran (2000). can result in hydraulic connection. Interactions between the Madison and Minnelusa aquifers were Temporal Trends investigated by Naus and others (2001) and are dis- Temporal trends in water levels are examined for cussed in more detail in a subsequent section of this eight wells with relatively long-term records (fig. 26). report.

38 Hydrology of the Black Hills Area, South Dakota o 104o 45' 103 30' Indian Horse o Belle Fourche EXPLANATION 44 45' Reservoir Cr Owl Newell OUTCROP OF MADISON LIME- BELLE Creek Creek STONE (from Strobel and Nisland F BELLE FOURCHE O others, 1999) UR CHE RIVER Hay Creek

R OUTCROP OF MINNELUSA

E BUTTE CO Vale 1 R I V FORMATION (from Strobel TER LAWRENCE CO MEADE CO REDWA and others, 1999) Cox Saint Creek Lake Crow 11,12 Onge OBSERVATION WELL--Symbol Creek reek 30' Spearfish C indicates aquifer designation. 2,3,4 7,8 5,6 Whitewood Number indicates map number Gulch Gulch 9,10 Bottom e 16 ls 14,15 Deadwood Bear a Creek F Whitewood Butte 2 Higgins 13 Cr Creek Creek Squ STURGIS Madison a Central Tinton w Cr City li Iron Cr ka o ood DEADWOOD l 3 Cr w A 15' 103 Minnelusa ad Beaver Cr e D Cr Lead Bear h nnie Cr 4 s A erry i trawb f S Minnekahta r 16,17 Cr Creek Tilford a e Whitetail p Elk 18,19,20 S 35 Inyan Kara Roubaix Little Elk ek Creek N re 21,22 Elk Little . C 15' h F Boxelder fis o r r Piedmont a k e R Ellsworth p a S Air Force S. Fork Rapid Cr p i d Nemo Base

C Creek r Blackhawk Cold S pri 26,27 ng Cre s ek k Box Elder For Rochford s adN o . For Rapid h k Ca 24,25 23 R stle RAPID CITY Castle Cr Beav 29,30 e Rapid r k Creek 31,32 C e Pactola r C C re e r Reservoir e ee Creek k k Castle V Deerfield ictoria Creek28 S. Fork Reservoir 33,34 o r

44 C l e Cast Rockerville Sheridan Creek Spring Lake Hill City Mt. Rushmore National Keystone Memorial nyon Harney

LIMESTONE PLATEAU a Hayward C n Peak

o x

y n PENNINGTON CO n Battle

a o po Hermosa y S k C a n CUSTER CO ne a Creek Creek s C 35 le o Grace Bear B French Creek CUSTER Gulch 38 Redbird e Gillette lidg 36,37 Creek Coo 45' Jewel Cave CUSTER 39,40 National

Monument Beaver STATE French Fairburn

PARK

Canyon Creek gh Hi la Lame Canyon n Creek d Pringle Wind Cave National Park

41,42 Creek WYOMING

Wind Johnny

Cave SOUTH DAKOTA SOUTH Dewey Beaver Red Creek 43,44,45 Buffalo Gap RIVER 30' Hell Creek

FALL RIVER CO H on 48,49 ot roo ny 46,47 B k Ca HOT SPRINGS Minnekahta Fall Oral R

CHEYENNE Cascade Springs

Edgemont Horsehead Angostura o Creek Reservoir Creek 43 15' d oo w n o tt o Igloo Creek C Provo

Figure 25. Location of observation wells for which hydrographs are presented.

Ground-Water Characteristics 39 3,540

A Redwater Minnelusa (site 1) 3,520

3,500

3,480

3,460

3,700

B Boulder Canyon Minnelusa (site 13)

3,680

3,660

3,640

3,460

C Cement Plant Minnelusa (site 23) 3,440

3,420

3,400

3,380

3,500

WATER LEVEL, IN FEET ABOVE SEA LEVEL D Countryside Deadwood (site 28) 3,480

3,460

3,440

3,420

3,460

3,440 E

3,420

3,400

3,380 Sioux Park Madison (site 31) 3,360 Sioux Park Minnelusa (site 32) 3,340 1960 1965 1970 1975 1980 1985 1990 1995 1999 CALENDAR YEAR

Figure 26. Hydrographs illustrating temporal trends in ground-water levels.

40 Hydrology of the Black Hills Area, South Dakota 3,380

F Hermosa West Inyan Kara (site 35)

3,360

3,340

3,320

3,360

G Hermosa South Inyan Kara (site 38)

3,340

3,320 WATER LEVEL, IN FEET ABOVE SEA LEVEL

3,300 1960 1965 1970 1975 1980 1985 1990 1995 1999 CALENDAR YEAR

Figure 26. Hydrographs illustrating temporal trends in ground-water levels.—Continued

Hydrographs illustrating general similarities in hydraulic connection in the vicinity of these wells. water levels for some colocated Madison and Min- Hydrographs for the Custer State Park (CSP) wells nelusa wells are presented in figure 27. All of the wells (fig. 27F) are nearly identical, and other pairs shown are located where confined conditions exist in both have general similarities. At most pairs of wells, aquifers. Hydraulic connection between the aquifers hydraulic connection cannot be confirmed or refuted has been confirmed through aquifer testing (Greene, because aquifer testing has not been performed. 1993) for the City Quarry wells (fig. 27D), which have Distinct hydraulic separation between the hydrographs that are nearly identical. Hydraulic con- Madison and Minnelusa aquifers is apparent for two nection in this area also has been confirmed by dye well pairs (fig. 28) where water-level altitudes differ by testing (Greene, 1997), which identified a Madison about 500 to 600 ft in locations where unconfined aquifer source for nearby City Springs (fig. 23) that (water-table) conditions occur. In both locations, the discharges through the Minnelusa Formation. water table in the Minnelusa aquifer is much higher Similarities in hydrographs do not necessarily than that in the Madison aquifer, which also is not fully indicate hydraulic connection between the aquifers. saturated. Both well pairs are located within or near the Hydrographs for the Spearfish Golf Course wells Minnelusa Formation outcrops (fig. 25) and measured (fig. 27A) are very similar during 1995-98, but have water-level altitudes in the Minnelusa aquifer are little similarity prior to that period. Aquifer testing higher than for most other observation wells in uncon- (Greene and others, 1999) provided no indication of fined areas.

Ground-Water Characteristics 41 3,700 3,500

A Spearfish Golf Course Madison (site 9) D City Quarry Madison (site 24) 3,680 Spearfish Golf Course Minnelusa (site 10) City Quarry Minnelusa (site 25) 3,480

3,660 3,460 3,640

3,440 3,620

3,600 3,420

3,480 3,600

B Whitewood Madison (site 14) E Reptile Gardens Madison (site 33) 3,460 Whitewood Minnelusa (site 15) Reptile Gardens Minnelusa (site 34) 3,550 3,440

3,420 3,500 3,400

3,380 3,450

3,700 3,720

WATER LEVEL, IN FEET ABOVE SEA LEVEL C Tilford Madison (site 18) F CSP Airport Madison (site 39) Tilford Minnelusa (site 19) CSP Airport Minnelusa (site 40) Tilford Minnekahta (site 20) 3,650 3,700

3,600 3,680

3,550 3,660 1984 1986 1988 1990 1992 1994 1996 1998 1984 1986 1988 1990 1992 1994 1996 1998 CALENDAR YEAR CALENDAR YEAR

Figure 27. Hydrographs illustrating general similarities in water levels for some colocated Madison/Minnelusa wells with confined conditions.

4,400 A B 4,200

Tinton Road Madison (site 7) Boles Canyon Madison (site 36) 4,000 Tinton Road Minnelusa (site 8) Boles Canyon Minnelusa (site 37)

WATER LEVEL, 3,800

IN FEET ABOVE SEA LEVEL 3,600 1984 1986 1988 1990 1992 1994 1996 1998 1984 1986 1988 1990 1992 1994 1996 1998 CALENDAR YEAR CALENDAR YEAR

Figure 28. Hydrographs illustrating distinct hydraulic separation for two Madison/Minnelusa well pairs with unconfined conditions.

42 Hydrology of the Black Hills Area, South Dakota Figure 29 shows hydrographs for other colocated the Tilford wells (fig. 27C), State Line wells (fig. 29A), Madison and Minnelusa wells, most of which are in and 7-11 Ranch wells (fig. 29F). Many artesian springs locations with confined conditions (figs. 21 and 22). emerge through the Minnekahta Limestone; thus, Most of these well pairs show distinct hydraulic sepa- hydraulic connections with the underlying Madison ration between the aquifers, with hydraulic heads sepa- and Minnelusa aquifers are possible. Hydrographs for rated by as much as 100 to 150 ft. Hydraulic separation the Minnekahta and Madison wells are very similar for is consistently less than about 30 ft for three well pairs, the State Line wells, which are located about 3 mi however—the Frawley Ranch, Hell Canyon, and south of a group of large artesian springs (fig. 23). Minnekahta Junction wells (figs. 29B, 29E, and 29G, Hydraulic heads in the Minnelusa and Minnekahta respectively). Periods of record for these wells may be wells are quite similar in the 7-11 Ranch wells, which insufficient to indicate similarity or dissimilarity of are located 3 mi west of Beaver Creek Springs. hydrograph shapes. Hydrographs for colocated Deadwood and Hydraulic connection between aquifers does not Madison wells (fig. 30) are available for two locations. necessarily mean hydrographs will be similar. The For the Cheyenne Crossing wells (fig. 30B), the water Madison and Minnelusa aquifers probably are con- table in the Madison aquifer is about 250 ft higher than nected hydraulically at Cleghorn and Jackson Springs the water table in the Deadwood aquifer. For the Doty (fig. 23), which are located within the outcrop of the wells (fig. 30C), the Deadwood aquifer is confined, and Minnelusa Formation, but probably originate primarily hydraulic head is about 200 ft higher than in the Mad- from the Madison aquifer (Naus and others, 2001). ison aquifer. Hydrographs for the Canyon Lake wells, which are located about one-quarter mile from the spring com- Responses to Climatic Conditions plex, show no indication of hydraulic connection, however (fig. 29D). Hydraulic head in the Minnelusa Ground-water levels are directly affected by aquifer is about 50 to 60 ft lower than in the Madison recharge rates that are influenced by annual precipita- aquifer in this area, indicating probable recharge from tion amounts; however, numerous other factors can the Madison aquifer (Driscoll and Carter, 2001). The affect ground-water response. The timing and intensity Minnelusa aquifer apparently is connected hydrauli- of precipitation, along with evaporative factors such as cally to Rapid Creek at this location, as evidenced by a temperature, humidity, wind speed, and solar radiation, sharp water-level decline during a period when Canyon can have a large effect on annual recharge. Streamflow Lake was drained near the end of 1995. losses (especially for the Madison and Minnelusa aqui- Another observation that can be made from com- fers) also contribute to recharge. Ground-water levels parisons of hydrographs for paired wells is that the also can be affected by well withdrawals, spring dis- hydraulic head in the Madison aquifer equals or charges, and various hydraulic properties of aquifers. exceeds the hydraulic head in the Minnelusa aquifer in Hydrographs for many wells in figures 26-30 show a most locations where confined conditions occur. The distinct response to annual precipitation patterns Madison aquifer has the potential for higher hydraulic (fig. 8); thus, other influences probably are relatively head than the Minnelusa aquifer because of generally minor for many wells. Many of these wells with suffi- higher altitude of recharge area for the Madison cient periods of record show short-term declines during aquifer. An exception to this generality occurs along the late 1980’s, with generally increasing water levels the northeastern flank of the Black Hills. The hydraulic during the wetter conditions of the middle to late head in the Minnelusa aquifer generally equals or 1990’s. exceeds that in the Madison aquifer for the Spearfish Water-level records are not available for the Golf Course wells (fig. 27A), the Whitewood wells Black Hills area for the prolonged drought conditions (fig. 27B), and the Frawley Ranch wells (fig. 29B). that occurred during the 1930’s and late 1950’s. Cumu- lative precipitation deficits during these periods were more severe than for the short-term drought conditions Comparisons for Other Aquifers that occurred during the late 1980’s (fig. 8). Recharge Hydrograph comparisons for colocated wells estimates for 1931-98 for the Madison and Minnelusa completed in other aquifers are presented in figure 30. aquifers (Carter, Driscoll, and Hamade, 2001) indicate Hydrographs for the Spearfish West Minnelusa and that recharge also was minimal during the 1930’s and Minnekahta wells are shown in figure 30A. Hydro- late 1950’s; thus, water-level declines exceeding those graphs for the Minnekahta aquifer also are available for of the late 1980’s probably occurred.

Ground-Water Characteristics 43 3,800 3,740

AEHell Canyon Madison (site 41) Hell Canyon Minnelusa (site 42) 3,750 3,730

State Line Madison (site 2) 3,700 State Line Minnelusa (site 3) 3,720 State Line Minnekahta (site 4)

3,650 3,710

3,600 3,700

3,560 3,700

B Frawley Ranch Madison (site 5) F 3,550 Frawley Ranch Minnelusa (site 6) 3,600 3,540 7-11 Ranch Madison (site 43) 7-11 Ranch Minnelusa (site 44) 7-11 Ranch Minnekahta (site 45) 3,530 3,500

3,520

3,510 3,400

3,650 3,655

CGPiedmont Madison (site 21) Minnekahta Junction Madison (site 46) Minnekahta Junction Minnelusa (site 47) 3,600 Piedmont Minnelusa (site 22) 3,650

3,550 3,645 WATER LEVEL, IN FEET ABOVE SEA LEVEL 3,500 3,640

3,450 3,635

3,440 3,700 D H 3,420 3,650

3,400 3,600 Canyon Lake Madison (site 29) Vets Home Madison (site 48) Canyon Lake Minnelusa (site 30) Vets Home Minnelusa (site 49) 3,380 3,550

3,360 3,500

3,340 3,450 1984 1986 1988 1990 1992 1994 1996 1998 1984 1986 1988 1990 1992 1994 1996 1998 CALENDAR YEAR CALENDAR YEAR

Figure 29. Hydrographs illustrating generally separated water levels for some colocated Madison/Minnelusa wells.

44 Hydrology of the Black Hills Area, South Dakota 3,620 Driscoll and Carter (2001) noted that for the A Spearfish West Minnelusa (site 11) Madison and Minnelusa aquifers, the smallest water- Spearfish West Minnekahta (site 12) 3,600 level fluctuations occur in the extreme southern Black

3,580 Hills. Smaller recharge than in other areas probably is a contributing factor. Another factor may be large 3,560 storage capacity in unconfined parts of the aquifers, which are especially extensive in the southern Black 3,540 Hills (figs. 21 and 22). Caves, which are especially

3,520 prevalent in the Madison aquifer, probably are more

5,900 common in the southern Black Hills than in other areas and can provide large storage capacity . B 5,800 Water Quality Cheyenne Crossing Deadwood (site 16) 5,700 Cheyenne Crossing Madison (site 17) This section includes a summary of water- quality characteristics for the major aquifers and 5,600 selected minor aquifers in the Black Hills area. More detailed descriptions of ground-water quality are pre- 5,500 sented by Williamson and Carter (2001), who consid- 4,100 ered water-quality data collected for the Black Hills C Hydrology Study and other studies from October 1, WATER LEVEL, IN FEET ABOVE SEA LEVEL 1930, to September 30, 1998. A brief discussion of the 4,000 susceptibility of aquifers to contamination also is pre- Doty Deadwood (site 26) Doty Madison (site 27) sented, as well as a summary of water quality relative to water use. Table 4 describes the significance of 3,900 selected properties and constituents and any related U.S. Environmental Protection Agency (USEPA) water-quality standards for drinking water. 3,800 1984 1986 1988 1990 1992 1994 1996 1998 Maximum Contaminant Levels (MCL’s) are CALENDAR YEAR established for contaminants that, if present in drinking water, may cause adverse human health effects; MCL’s Figure 30. Hydrographs for colocated Minnelusa/Minnekahta are enforceable health-based standards (U.S. Environ- and Deadwood/Madison wells. mental Protection Agency, 1994a). Secondary Max- imum Contaminant Levels (SMCL’s) are established for contaminants that can adversely affect the taste, odor, or appearance of water and may result in discon- tinuation of use of the water; SMCL’s are nonenforce- Hydrographs for the Inyan Kara wells (figs. 26F able, generally non-health-based standards that are and G) show minimal response to climatic conditions. related to the aesthetics of water use (U.S. Environ- Hydrographs for other Inyan Kara wells that are not mental Protection Agency, 1994a). Action levels, which are concentrations that determine whether shown also show minimal response to climatic condi- treatment requirements may be necessary (U.S. tions (Driscoll, Bradford, and Moran, 2000). Environmental Protection Agency, 1997), have been All of the other aquifers show a wide range of established for copper and lead. water-level responses to climatic conditions, ranging Concentrations of constituents were compared from minimal response to several tens of feet. The by Williamson and Carter (2001) to drinking-water largest overall water-level change is for the Reptile standards set by the USEPA. Although USEPA stan- Gardens Madison well (fig. 27E), which increased by dards apply only to public-water supplies, individuals about 110 ft during 1990-98. Increases of about 80 ft using water from private wells should be aware of the have been recorded for the Tilford Madison and potential health risks associated with drinking water Minnelusa wells (fig. 27C). that exceeds drinking-water standards.

Ground-Water Characteristics 45