OVERVIEW AND RESULTS OF THE BLACK HILLS HYDROLOGY STUDY

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1 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) 149 OVERVIEW AND RESULTS OF THE BLACK HILLS HYDROLOGY STUDY Daniel G. Driscoll and Janet M. Carter U.S. Geological Survey Rapid City, SD ABSTRACT The Black Hills Hydrology Study was a long-term study that was initiated in 1990 and was completed in 2002, following completion of a series of 21 reports and 11 published maps. The study was a regional assessment of water resources that had a purpose of assessing the quantity, quality, and distribution of surface water and ground water in the Black Hills area of South Dakota, which has complex hydrogeology. A major focus of the study was on describing the hydrologic significance of the major bedrock aquifers in the area, which are the Inyan Kara, Minnekahta, Minnelusa, Madison, and Deadwood aquifers. An overview of the study and a summary of major results are provided herein. Keywords Black Hills, hydrology, ground water, surface water, water quality, Madison aquifer, Minnelusa aquifer, precipitation, recharge INTRODUCTION The Black Hills area is an important resource center that provides an economic base for western South Dakota through tourism, agriculture, timber, and mineral resources. Water originating from the area is used for municipal, industrial, agricultural, and recreational purposes throughout much of western South Dakota. Population growth, resource development, and periodic droughts have the potential to affect the quantity, quality, and availability of water within the Black Hills area. The hydrogeology of the Black Hills area is extremely complex. A vertical sequence of bedrock aquifers is contained within a series of geologic units that have been uplifted and exposed in the Black Hills area. Several important regional aquifers in the northern Great Plains receive substantial recharge in the area. Ground-water and surface-water hydrology are highly influenced by geologic conditions, which can be extremely heterogeneous and have large spatial variability throughout the area. Ground water and surface water interact extensively in the area, and both aquifer recharge and streamflow are influenced by climatic conditions, which have large spatial and temporal variability. The Black Hills Hydrology Study was initiated in 1990 to assess the quantity, quality, and distribution of surface water and ground water in the Black

2 150 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) Hills area of South Dakota. This long-term study was a cooperative effort among the U.S. Geological Survey (USGS), the South Dakota Department of Environment and Natural Resources, and the West Dakota Water Development District, which represented various local and county cooperators. This paper provides an overview of the Black Hills Hydrology Study and summarizes major results. OVERVIEW OF STUDY The Black Hills Hydrology Study was initiated in 1990 and was completed in The Black Hills Hydrology Study was designed as a regional assessment of the water resources and was not designed to address site-specific issues. The study focused on describing the hydrologic significance of the major bedrock aquifers in the Black Hills area, which are the Inyan Kara, Minnekahta, Minnelusa, Madison, and Deadwood aquifers. The highest priority was placed on the Madison and Minnelusa aquifers, which are widely used and interact extensively with the surface-water resources of the area. The study consisted of two primary phases data collection and interpretation. An extensive network consisting of 71 observation wells, 94 precipitation gages, and 60 streamflow-gaging stations was used during the data collection phase, which ended in Critical components of this network (primarily observation wells and selected streamflow-gaging stations) are being maintained for long-term purposes through cooperative programs between the USGS and various local, State, and Federal cooperators. The interpretive phase of the study was completed in 2002, and resulted in the publication of a series of 21 reports and 11 maps. DESCRIPTION OF STUDY AREA The study area for the Black Hills Hydrology Study includes the topographically defined Black Hills and portions of six counties in western South Dakota. The generalized outer extent of the outcrop of the Cretaceous-age Inyan Kara Group approximates the outer extent of the Black Hills area (Figure 1). The Black Hills are situated between the Cheyenne River and the Belle Fourche River, which is the largest tributary to the Cheyenne River. The study area includes most of the larger communities in western South Dakota and contains about one-fifth of the State s population. Land-surface altitudes range from about 7,242 feet (2,207 meters (m)) above National Geodetic Vertical Datum of 1929 (NGVD 29) at Harney Peak to about 3,000 feet (914 m) above NGVD 29 in the adjacent plains. The overall climate of the Black Hills area is continental, which is characterized by low precipitation amounts, hot summers, cold winters, and extreme variations in both precipitation and temperatures. Local climatic conditions are affected by topography, with generally decreasing temperatures and increasing precipitation with increasing altitude. Average annual precipitation for water years (WY) ranged from 16 inches (41 centimeters (cm)) in the south-

3 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) 151 Figure 1. Study area. ern and northern parts of the study area to greater than 28 inches (71 cm) near Lead and Deadwood (Driscoll and Carter 2001). Long-term trends in precipitation for WY for the study area are illustrated in Figure 2A. Annual precipitation for the study area averaged inches (47 cm) and ranged from inches (26 cm) in WY 1936 to inches (70 cm) in WY The cumulative trends (Figure 2B) show that sustained periods of generally deficit precipitation occurred during and The middle to late 1990s was the wettest period since 1931, which caused potential for bias towards wet conditions for hydrologic data collected during this period. This potential bias was addressed in various analyses performed as part of the study, and has been balanced to some extent by relatively dry conditions during the late 1980s and early 1990s.

4 152 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) Figure 2. Long term trends in precipitation for Black Hills area, water years (from Driscoll, Hamade, and Kenner 2000). Throughout geologic time, the Black Hills area has experienced frequent periods of inundation by seas, extended erosion, mountain building, and intrusion by igneous rocks; thus, the hydrogeology of the study area is very complex. The Black Hills uplift formed as an elongated dome about 60 to 65 million years ago during the Laramide orogeny (Darton and Paige 1925). The oldest geologic units in the study area are the Precambrian crystalline (igneous and metamorphic) rocks, which are exposed in the central core of the Black Hills, extending from near Lead to south of Custer. The Precambrian rocks generally have low permeability; however, localized aquifers occur in many locations in the crystalline core of the Black Hills where secondary porosity and permeability have resulted from fracturing and weathering of the rocks. Surrounding the Precambrian crystalline core is a layered series of sedimentary rocks including limestones, sandstones, and shales that are exposed in roughly concentric rings around the uplifted flanks of the Black Hills, as shown by the outcrops of the Madison Limestone and Minnelusa Formation (Figure 1). The more permeable of these sedimentary rocks the Cambrian- and Ordovician-age Deadwood Formation, Mississippian-age Madison Limestone, Pennsylvanian- and Permian-age Minnelusa Formation, Permian-age Minnekahta Limestone, and Cretaceous-age Inyan Kara Group contain major aquifers that

5 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) 153 are able to store and transmit large quantities of water and are used extensively for water supplies within and beyond the study area. Minor bedrock aquifers occur in other units, including confining units, due to fracturing and interbedded permeable layers. Various unconsolidated units, including alluvium and colluvium, are considered aquifers, where saturated. The hydrologic setting of the Black Hills is schematically illustrated in Figure 3. Individually, the major aquifers generally are separated by confining layers, which are composed of less permeable rocks, or by relatively impermeable layers within the individual units. The aquifers and confining units generally dip away from the flanks of the Black Hills (Figure 3). In general, ground-water flow in these aquifers is radially away from the central core of the Black Hills. The aquifers primarily receive recharge from infiltration of precipitation on outcrops, and several aquifers also receive recharge from streamflow losses. Confined (artesian) conditions generally exist within the major aquifers, in locations where an upper confining layer is present. Flowing wells and artesian springs that originate from confined aquifers are common around the periphery of the Black Hills. Figure 3. Schematic showing simplified hydrologic setting of the Black Hills area. Surface water in the Black Hills area is highly influenced by geologic conditions, and five hydrogeologic settings have been identified that have distinctive influences on streamflow and surface-water quality. The five settings, which are shown in Figure 4, are represented by four areas because two of the settings loss zone and artesian spring are considered to share a common area. Numerous headwater (water-table) springs, originating primarily from the Madison and Minnelusa aquifers, occur in the limestone headwater setting, which is a high-altitude area of generally low relief in the western part of the

6 154 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) Figure 4. Hydrogeologic settings for the Black Hills area. study area known as the Limestone Plateau (Figure 4). Most of the headwater springs occur near the eastern edge of the Limestone Plateau and provide base flow for many Black Hills streams. These streams flow across the Precambrian igneous and metamorphic rocks in the crystalline core setting. The loss zone setting (Figure 4) consists of areas that are heavily influenced by streamflow losses. Most streams generally lose all or part of their flow as they cross the outcrop of the Madison Limestone (Rahn and Gries 1973; Hortness and Driscoll 1998). Karst features of the Madison Limestone, including collapse features, sinkholes, and solution features such as caves, are responsible for the Madison aquifer s large capacity to accept recharge from streamflow. Large streamflow losses also occur in many locations within the outcrop of the Minnelusa Formation, and limited losses probably also occur within the outcrop of the Minnekahta Limestone (Hortness and Driscoll 1998).

7 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) 155 Large artesian springs originating primarily from the Madison and Minnelusa aquifers occur in many locations downgradient from these loss zones. Thus, the loss zone and artesian spring settings are represented by the same area (Figure 4). These artesian springs provide an important source of base flow in many streams beyond the periphery of the Black Hills. No artesian springs are known to be located beyond the outcrop of the Inyan Kara Group; thus, the area beyond this outcrop is considered to be the exterior setting (Figure 4). RESULTS OF STUDY Detailed results of the Black Hills Hydrology Study have been reported in a variety of publications, including data reports, map reports, topical reports, and summary reports. Water-level data through WY 1998 for the entire network of observation wells were summarized in a project data report (Driscoll, Bradford, Moran 2000) that also included water-quality data for a variety of surface-and ground-water sampling sites. Previous project data reports (Driscoll and Bradford 1994; Driscoll et al. 1996) provided similar data. Streamflow and precipitation data were published annually in Water Resources Data for South Dakota (U.S. Geological Survey ). A summary of precipitation data available for the study area was provided by Driscoll, Hamade, and Kenner (2000). The report summarized monthly data for precipitation gages operated within the study area during and examined long-term trends for precipitation. The report also provided an isohyetal map showing the spatial distribution of precipitation for WY A number of topical reports addressing a variety of subject matter were published throughout the course of the study. One of the earliest topical reports was a compilation of streamflow loss thresholds (maximum sustainable loss rates) to bedrock aquifers for major streams within the study area (Hortness and Driscoll 1998). Unique loss thresholds were quantified for 24 streams in the study area and ranged from negligible (no loss) for several streams to as much as 50 cubic feet per second (ft 3 /s) (1.4 cubic meters per second (m 3 /s)) for Boxelder Creek. Quantification of losses to individual aquifers was possible for only about onethird of the streams. Loss thresholds for individual streams were concluded to be relatively constant, and without measurable effect from streamflow rates or duration of flow through the loss zones. A summary of data for all continuous-record gaging stations within the study area was assembled by Miller and Driscoll (1998). This report included detailed statistical summaries for gaging stations with 10 or more years of streamflow data and also provided a preliminary characterization of geologic influences on streamflow. A more detailed analysis of the distinctive influences of the five different hydrogeologic settings (Figure 4) on streamflow characteristics was provided by Driscoll and Carter (2001). Relations between annual streamflow and annual precipitation were quantified for representative gaging stations for selected hydrogeologic settings. Relative strong correlations between annual streamflow and precipitation were demonstrated for the crystalline core and exterior settings. Similar correlations were extremely weak for the limestone

8 156 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) headwater setting because of the influence of long-term ground-water storage; however, correlations for this setting were substantially improved by using moving-average precipitation as an explanatory variable. A series of 1:100,000-scale maps showing ground-water resources were produced, and included maps showing the distribution of hydrogeologic units (Strobel et al. 1999), potentiometric surfaces of the major bedrock aquifers (Strobel et al. 2000), and altitudes of the tops of the geologic formations that contain the major aquifers (Carter and Redden 1999). Accompanying data reports documenting selected data for specific wells and springs were published for the potentiometric maps (Galloway 2000) and structure-contour maps (Carter 1999). Water-level records from 71 observation wells indicated that there is no long-term decline in water levels in any of the bedrock aquifers in the Black Hills area. Water levels in a large percentage of the observation wells completed in the Madison and Minnelusa aquifers respond especially quickly to climatic conditions. The total volume of recoverable water stored in the major aquifers (including aquifers in the Precambrian rocks) within the study area was estimated as 256 million acre-feet (316.1 billion cubic meters) (Carter et al. 2002). Most of the recoverable water is stored in the Inyan Kara, Minnelusa, and Madison aquifers (Table 1). Table 1. Estimated volumes of recoverable water in storage for major aquifers in study area (modified from Carter et al. 2002). Aquifer Estimated Amount Of Recoverable Water In Storage Million acre-feet Billion cubic meters Inyan Kara Minnekahta Minnelusa Madison Deadwood Precambrian COMBINED STORAGE FOR MAJOR AQUIFERS Hydraulic connection between the Madison and Minnelusa aquifers at some locations in the Rapid City area has been confirmed through aquifer testing and dye tracing (Greene 1993, 1997). In the Spearfish area, aquifer testing provided no indication of hydraulic connection in the vicinity of tested wells (Greene et al. 1999). Potential for hydraulic connection is indicated in several locations by similarities in hydrographs for paired observation wells completed in the Madison and Minnelusa aquifers; however, hydraulic connection generally cannot be confirmed or refuted because aquifer testing has not been performed at most locations (Driscoll et. al. 2002). Hydraulic connection probably occurs at

9 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) 157 many artesian spring locations, and artesian springflow probably accounts for the largest percentage of leakage that occurs between the Madison and Minnelusa aquifers Carter, Driscoll, and Hamade (2001) used a variety of methods in estimating recharge to the Madison and Minnelusa aquifers. Recharge estimates for the aquifers were combined because recharge from streamflow losses could not be quantified separately for most streams. Estimated relations between annual recharge and precipitation were used in deriving estimates of recharge from infiltration of precipitation. Large outcrops of the Madison Limestone and Minnelusa Formation occur in the Black Hills of Wyoming and were considered in estimating recharge to the Madison and Minnelusa aquifers. Recharge to these aquifers for WY in South Dakota and Wyoming averaged about 344 ft 3 /s (9.7 m 3 /s). Annual recharge rates were highly variable (Figure 5) and ranged from about 62 ft 3 /s (1.8 m 3 /s) in 1936 to about 847 ft 3 /s (24.0 m 3 /s) in About three-quarters of the total recharge to the Madison and Minnelusa aquifers is from infiltration of precipitation on outcrops, and about one-quarter is from streamflow losses. The largest amount of precipitation recharge occurs in the Limestone Plateau area of the Black Hills. Figure 5. Annual recharge to the Madison and Minnelusa aquifers, in the Black Hills of South Dakota and Wyoming, water years (from Carter, Driscoll, and Hamade, 2001). The recharge estimates developed by Carter, Driscoll, and Hamade (2001) were used extensively in development of detailed hydrologic budgets for the Madison and Minnelusa aquifers (Carter, Driscoll, Hamade, and Jarrell 2001).

10 158 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) The budgets for these aquifers were combined because several of the budget components, including recharge and springflow, could not be quantified individually. Estimates of average combined budget components for WY were: 395 ft 3 /s (11.2 m 3 /s) for recharge, 78 ft 3 /s (2.2 m 3 /s) for headwater springflow, 189 ft 3 /s (5.4 m 3 /s) for artesian springflow, 28 ft 3 /s (0.8 m 3 /s) for well withdrawals, and 100 ft 3 /s (2.8 m 3 /s) for net ground-water outflow from the study area. The recharge estimates for WY are substantially higher than for WY because of substantially wetter climatic conditions. Artesian springflow is the single largest discharge component for the Madison and Minnelusa aquifers. Various hydrologic budgets (WY ) for the study area (excluding Wyoming) were developed by Driscoll and Carter (2001), including groundwater budgets for all of the major bedrock aquifers, surface-water budgets, and combined ground- and surface-water budgets. Ground-water budgets for the study area are dominated by the Madison and Minnelusa aquifers, with recharge to these aquifers comprising about 84 percent of total recharge to all bedrock aquifers, which averaged about 348 ft 3 /s (9.9 m 3 /s). Springflow was estimated as 219 ft 3 /s (6.2 m 3 /s), of which 94 percent originates from the Madison and Minnelusa aquifers. Well withdrawals were estimated as 40 ft 3 /s (1.1 m 3 /s), of which 70 percent was withdrawn from the Madison and Minnelusa aquifers. Ground-water outflow from the study area was estimated as 89 ft 3 /s (2.5 m 3 /s), of which 65 percent occurs in the Madison and Minnelusa aquifers. Surface-water inflows to the study area have averaged about 252 ft 3 /s (7.1 m 3 /s) and outflows have averaged about 552 ft 3 /s (15.6 m 3 /s). Total consumptive usage from both ground-water and surface-water sources was estimated as 218 ft 3 /s (6.2 m 3 /s), which includes well withdrawals of 40 ft 3 /s (1.1 m 3 /s), reservoir evaporation of 38 ft 3 /s (1.1 m 3 /s), and consumptive streamflow withdrawals of 140 ft 3 /s (4.0 m 3 /s). Of the average annual precipitation in the study area, about 91.6 percent is returned to the atmosphere through evapotranspiration, about 3.5 percent recharges aquifers in the study area, and about 4.9 percent becomes runoff from the land surface. Water-quality characteristics for ground water and surface water were summarized by Williamson and Carter (2001). Water quality of the major aquifers generally is very good in and near outcrop areas but deteriorates progressively with distance from the outcrops. In the Minnelusa aquifer, concentrations of dissolved sulfate vary markedly over short distances, especially near a zone where active anhydrite dissolution occurs. Most limitations for the use of ground water are related to aesthetic qualities associated with hardness and high concentrations of chloride, sulfate, sodium, manganese, and iron. Very few health-related limitations exist for ground water; most limitations are for substances associated with radioactive decay, such as radon and uranium. In addition, high concentrations of arsenic have been detected in a few samples from the Madison and Minnelusa aquifers. Surface-water quality is distinctly influenced by the hydrogeologic settings (Figure 4). For most streams, concentrations of dissolved solids increase as streamflow decreases. However, for streams in the limestone headwater and artesian spring settings, which are dominated by ground-water discharge, concentrations of dissolved solids have little variability. Most streams generally meet

11 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) 159 water-quality standards established for designated beneficial uses. The primary exceptions are streams in the exterior setting, which frequently fail to meet standards for suspended sediment (South Dakota Department of Environment and Natural Resources 1998) and occasionally fail to meet standards for temperature and dissolved oxygen during low-flow conditions. Water-quality characteristics for selected streams in Lawrence County, which includes many mineralized areas, were described by Williamson and Hayes (2000). Separating influences of mining activities from natural water quality generally is difficult because historical data are sparse. Degradation of water quality from large-scale mining activities has been documented, however, in Annie, Bear Butte, Squaw, and Whitewood Creeks. A major focus of the Black Hills Hydrology Study was to obtain a better understanding of flow systems within the Madison and Minnelusa aquifers, which are extremely complex due to heterogeneity and anisotropy related to karst features and fractures and to interactions between the aquifers and surface-water resources. Geochemical analyses by Naus et al. (2001) showed that regional flowpaths in the Madison and Minnelusa aquifers are largely deflected around the Black Hills. The dominant proportion of water in these aquifers within the study area is recharged within the Black Hills area. Age-dating analyses indicated that ground-water flow velocities in the Madison and Minnelusa aquifers are extremely variable. A technical summary (Driscoll et al. 2002) and a layreader summary (Carter et al. 2002) of the results of the Black Hills Hydrology study were published. Most reports published as part of the study are available online at URL sd.water.usgs.gov/projects/bhhs/table1.html. More information about the Black Hills Hydrology Study, including digital data, is available online at URL sd.water.usgs.gov/projects/bhhs/intro.html. The Black Hills Hydrology Study has provided an abundance of information regarding the water resources of the Black Hills area, which is widely used by a variety of resource managers. This information base also will serve as a foundation for addressing future needs for additional hydrologic information. Ongoing research by various organizations continues to address developing needs. REFERENCES CITED Carter, J.M Selected data for wells and test holes used in structure-contour maps of the Inyan Kara Group, Minnekahta Limestone, Minnelusa Formation, Madison Limestone, and Deadwood Formation in the Black Hills area, South Dakota. USGS OFR pp. Carter, J.M., Driscoll, D.G., and G.R. Hamade Estimated recharge to the Madison and Minnelusa aquifers in the Black Hills area, South Dakota. USGS WRIR pp. Carter, J.M., Driscoll, D.G., Hamade, G.R., and G.J. Jarrell Hydrologic budgets for the Madison and Minnelusa aquifers in the Black Hills of South Dakota and Wyoming, water years USGS WRIR pp.

12 160 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) Carter, J.M., Driscoll, D.G., Williamson, J.E., and V.A. Lindquist Atlas of water resources in the Black Hills area, South Dakota. USGS HA-747, 120 pp. Carter, J.M., and J.A. Redden Altitude of the top of the Inyan Kara Group, Minnekahta Limestone, Minnelusa Formation, Madison Limestone, and Deadwood Formation in the Black Hills area, South Dakota. USGS HA-744-A to HA-744-E. Scale 1:100,000. Darton, N.H., and Sidney Paige Central Black Hills [quadrangle], South Dakota. USGS Atlas of the United States. Folio pp. Driscoll, D.G., and W.L. Bradford Compilation of selected hydrologic data, through water years 1992, Black Hills Hydrology Study, western South Dakota. USGS OFR pp. Driscoll, D.G., Bradford, W.L., and M.J. Moran Selected hydrologic data, through water year 1998, Black Hills Hydrology Study, South Dakota. USGS OFR pp. Driscoll, D.G., Bradford, W.L., and K.M. Neitzert Selected hydrologic data through water year 1994, Black Hills Hydrology Study, South Dakota. USGS OFR pp. Driscoll, D.G., and J.M. Carter Hydrologic conditions and budgets in the Black Hills area of South Dakota, through water year USGS WRIR pp. Driscoll, D.G., Carter, J.M., Williamson, J.E., and L.D. Putnam Hydrology of the Black Hills area, South Dakota: USGS WRIR pp. Driscoll, D.G., Hamade, G.R., and S.J. Kenner Summary of precipitation data compiled for the Black Hills area of South Dakota, water years USGS OFR pp. Galloway, J.M Selected hydrologic data for the Inyan Kara, Minnekahta, Minnelusa, Madison, and Deadwood aquifers in the Black Hills area, South Dakota. USGS OFR pp. Greene, E.A Hydraulic properties of the Madison aquifer system in the western Rapid City area, South Dakota. USGS WRIR pp. Greene, E.A Tracing recharge from sinking streams over spatial dimensions of kilometers in a karst aquifer. Ground Water. 35: Greene, E.A., Shapiro, A.M., and J.M. Carter Hydrogeologic characterization of the Minnelusa and Madison aquifers near Spearfish, South Dakota. USGS WRIR pp. Hortness, J.E., and D.G. Driscoll Streamflow losses in the Black Hills of western South Dakota. USGS WRIR pp. Miller, L.D., and D.G. Driscoll Streamflow characteristics for the Black Hills of South Dakota, through water year USGS WRIR pp. Naus, C.A., Driscoll, D.G., and J.M. Carter Geochemistry of the Madison and Minnelusa aquifers in the Black Hills area, South Dakota. USGS WRIR pp.

13 Proceedings of the South Dakota Academy of Science, Vol. 83 (2004) 161 Rahn, P.H., and J.P. Gries Large springs in the Black Hills, South Dakota and Wyoming: S.D. Geological Survey Report of Investigations pp. South Dakota Department of Environment and Natural Resources The 1998 South Dakota 303(d) waterbody list. South Dakota Department of Environment and Natural Resources, Pierre, S.D. Various pagination. Strobel, M.L., Galloway, J.M., and G.R. Hamade Potentiometric surface of the Inyan Kara, Minnekahta, Minnelusa, Madison, and Deadwood aquifers in the Black Hills area, South Dakota. USGS HA-745-A to HA-745-E. Scale 1:100,000. Strobel, M.L., Jarrell, G.J., Sawyer, J.F., J.R. Schleicher, and M.D. Fahrenbach Distribution of hydrogeologic units in the Black Hills area, South Dakota. USGS HA-743. Scale 1:100,000. U.S. Geological Survey Water resources data for South Dakota, water years USGS Water Data Reports SD-90-1 to SD-98-1 (published annually). Williamson, J.E., and J.M. Carter Water-quality characteristics for the Black Hills area, South Dakota. USGS WRIR pp. Williamson, J.E., and T.S. Hayes Water-quality characteristics for selected streams in Lawrence County, South Dakota, USGS WRIR pp.