Prepared in cooperation with the South Dakota Department of Environment and Natural Resources and the West Dakota Water Development District The Black Hills Hydrology Study —By Janet M. Carter, Daniel G. Driscoll, and Joyce E. Williamson o Introduction 104o 45' 103 30' Indian Horse o Belle Fourche EXPLANATION 44 45' Reservoir Cr The Black Hills area is an impor- Owl Newell Outcrop of Madison Limestone BELLE Creek Creek tant resource center that provides an Nisland Outcrop of Minnelusa Formation F BELLE FOURCHE OU economic base for western South RCHE RIVER Approximate extent of the Black Hay Creek R E BUTTE CO Vale Hills area, represented by Dakota through tourism, agriculture, I V ER R MEADE CO REDWAT LAWRENCE CO generalized outer extent of the timber, and mineral resources. Water Cox the outcrop of Inyan Kara Saint Creek Lake Crow Onge Group originating from the area is used for Creek reek municipal, industrial, agricultural, and 30' Gulch Spearfish C Whitewood Bear x Gulch Butte Bottom Creek e recreational purposes throughout ls Bear a Creek F Whitewood Butte Higgins much of western South Dakota. The Cr Creek Squ STURGIS Spearfish a Central Tinton Cr w li Iron CityCr ka ood DEADWOOD l o Black Hills area also is an important Cr w A 103 ad 15' Beaver Cr e D Cr Lead Bear h nnie Cr s A berry recharge area for aquifers in the north- i traw f S r Cr Creek Tilford a hitetail e W p Cheyenne Elk S ern Great Plains. Crossing Little Creek Roubaix ek Creek N Elk re Elk Little C Population growth, resource devel- . 15' h F Boxelder fis o r r Piedmont a k e Ellsworth R p opment, and periodic droughts have a S Air Force S. Fork Rapid Cr p i Base d Nemo C Creek r Blackhawk the potential to affect the quantity, Cold S pri Cre ng ek s k Box Elder For Rochford quality, and availability of water s adN o . For Rapid h k Ca R stle RAPID CITY within the Black Hills area. Because Castle Cr Beav e Rapid r k Creek C C ee Pactola r C r of this concern, the Black Hills e re Reservoir e e Creek k k Castle V Deerfield ictoria Creek Hydrology Study was initiated in Reservoir Spring o S. Fork r 44 C l e Cast Rockerville 1990 to assess the quantity, quality, Sheridan Creek Creek Lake and distribution of surface water and Hill City Mt. Rushmore National Keystone Memorial yon an Spring Harney Hayward ground water in the Black Hills area LIMESTONE PLATEAU Iron C Peak n Mountain o x y x n PENNINGTON CO n Battle o a Cr of South Dakota. This long-term y Sylvan Spok Hermosa C n CUSTER CO Lake an a Iron e C Creek Creek s le study was a cooperative effort Calamity Grace Bear o B French Peak Creek CUSTER x Gulch Redbird e between the U.S. Geological Survey Gillette idg Creek Cool 45' Jewel Cave CUSTER National (USGS), the South Dakota Depart- Monument Beaver STATE French Fairburn ment of Environment and Natural PARK Canyon Creek gh Resources, and the West Dakota Water Hi la Lame n Canyon d C Creek o tt Wind Cave o Pringle n Development District, which repre- National Park w Creek o o WYOMING d sented various local and county coop- Wind Johnny Cave SOUTH DAKOTA SOUTH Dewey Onyx Beaver Creek Cave erators. This fact sheet describes the Red k Creek o RIVER Hell o Buffalo Gap r Black Hills Hydrology Study and the 30' B d Creek l o C FALL RIVER CO H on ot roo ny major findings of the study. More B k Ca HOT SPRINGS Minnekahta Fall detailed summaries are provided in Oral R CHEYENNE a lay-reader summary (Carter and Cascade SOUTH DAKOTA Springs others, 2002) and in a technical sum- Black Oahe Hills Reservoir Horsehead M mary (Driscoll and others, 2002). Edgemont iss ou Angostura r i o Creek Reservoir Creek 43 15' d Area oo w River n shown o tt o Igloo Creek Overview of Study C Provo The Black Hills Hydrology Study was Hat Base modified from U.S. Geological Survey digital data, 01020MILES initiated in 1990 as a partnership among 1:100,000, 1977, 1979, 1981, 1983, 1985 Rapid City, Office of City Engineer map, 1:18,000, 1996 several local, State, and Federal agencies. Universal Transverse Mercator projection, zone 13 01020KILOMETERS The study area for the Black Hills Hydrology Study includes portions of Figure 1. Area of investigation for the Black Hills Hydrology Study. U.S. Geological Survey USGS Fact Sheet FS-046–02 U.S. Department of the Interior June 2002 six counties in the Black Hills area of about 71 observation wells, 94 precipita- Long-term trends in precipitation for South Dakota (fig. 1). Outcrops of the tion gages, and 60 streamflow-gaging water years 1931-98 for the study area Madison Limestone and Minnelusa stations was used during the data- are illustrated in figure 2; a water year is Formation in South Dakota, which are collection phase. Critical components the 12-month period, October 1 through areas where these geologic formations of this network (primarily observation September 30, and is designated by the occur at the land surface, are shown in wells and selected streamflow-gaging calendar year in which it ends. Annual figure 1. The generalized outer extent of stations) are being maintained for long- precipitation for the study area averages the outcrop of the Inyan Kara Group, term purposes through a cooperative 18.61 inches and has ranged from which approximates the outer extent of program between the USGS and local 10.22 inches in water year 1936 to the Black Hills area, also is shown in and State cooperators. 27.39 inches in water year 1995. The figure 1. A series of 21 reports and 11 maps middle to late 1990’s stand out as the The purpose of the Black Hills have been published as part of the study. wettest period since 1931, which has Hydrology Study was to assess the quan- Hydrologic data collected during the caused potential for bias towards wet tity, quality, and distribution of surface study have been published in various conditions in the data collected in the water and ground water in the Black data reports. Maps (1:100,000 scale) Black Hills during this period. This Hills area of South Dakota. The study have included a hydrogeologic unit map potential bias has been addressed in the was designed as a regional assessment of for the study area, structure-contour analysis of hydrologic data throughout the water resources and was not designed maps for five geologic formations that the course of the study, and has been to address site-specific issues. Because contain major aquifers, and potentiomet- balanced to some extent by relatively dry the Black Hills area is an important ric maps for these major aquifers. Inter- conditions during the late 1980’s and recharge area for several regional bed- pretive reports have addressed water early 1990’s. rock aquifers and various local aquifers, quality and hydrologic conditions for the study concentrated on describing the surface water and ground water. Many Hydrogeologic Setting hydrologic significance of selected bed- of the interpretive reports have dealt rock aquifers. The major aquifers in the specifically with the Madison and Throughout geologic time, the Black Black Hills area are the Deadwood, Minnelusa aquifers, which were a pri- Hills area has experienced frequent Madison, Minnelusa, Minnekahta, and mary focus of the study. Additional periods of inundation by seas, extended Inyan Kara aquifers. The highest prior- information concerning the study and erosion, mountain building, and intrusion ity was placed on the Madison and Minnelusa aquifers, which are widely study products is available at http:// by igneous rocks; thus, the hydrogeology used and interact extensively with the sd.water.usgs.gov/projects/bhhs/ of the study area is very complex. The surface-water resources of the area. BHHS.html. Black Hills uplift formed as an elongated The study consisted of two primary dome about 60 to 65 million years ago. phases—data collection and interpreta- Description of Study Area The oldest geologic units in the study tion. An extensive network consisting of area are the Precambrian crystalline The study area for the Black Hills (igneous and metamorphic) rocks (not Hydrology Study (fig. 1) consists of the shown in fig. 1), which are exposed in topographically defined Black Hills and the central core of the Black Hills, Photograph by Darwin L. Rahder adjacent areas located in western South extending from near Lead to south of Dakota. The Black Hills are situated Custer. The Precambrian rocks generally between the Cheyenne and Belle have low permeability; however, local- Fourche Rivers. The Belle Fourche ized aquifers occur in many locations in River is the largest tributary to the the crystalline core of the Black Hills Cheyenne River. The study area includes most of the larger communities in west- ern South Dakota and contains about one-fifth of the State’s population. 30 Climate 20 The overall climate of the Black Hills area is continental, which is character- ized generally by low precipitation 10 Annual precipitation amounts, hot summers, cold winters, and Long-term average extreme variations in both precipitation (18.61 inches) 0 and temperatures. Local climatic condi- 19301940 1950 1960 1970 1980 1990 2000 ANNUAL PRECIPITATION, IN INCHES PRECIPITATION, ANNUAL tions are affected by topography, with WATER YEAR generally lower temperatures and higher Figure 2. Long-term trends in precipitation for The precipitation gage Mt.