U.S. Department of the Interior

U.S. Geological Survey

Water-Quality Characteristics

in the Black Hills Area,

South Dakota

Prepared in cooperation with the

South Dakota Department of Environment and Natural Resources

and the West Dakota Water Development District

Water-Resources Investigations Report 01-4194

By Joyce E. Williamson and Janet M. Carter
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

The use of firm, trade, and brand names in this report is for identification purposes only and 

does not constitute endorsement by the U.S. Geological Survey.

Rapid City, South Dakota: 2001

For additional information write to:

District Chief

U.S. Geological Survey

1608 Mt. View Road

Rapid City, SD 57702

Copies of this report can be purchased from:

U.S. Geological Survey

Information Services

Building 810

Box 25286, Federal Center

Denver, CO 80225-0286
Contents III

CONTENTS

Abstract.................................................................................................................................................................................. 1

Introduction ........................................................................................................................................................................... 2

Purpose and Scope....................................................................................................................................................... 3

Description of Study Area ........................................................................................................................................... 3

Physiography and Climate................................................................................................................................. 3

Geologic Setting ................................................................................................................................................ 5

Hydrologic Setting............................................................................................................................................. 9

Major Aquifers ........................................................................................................................................ 9

Minor Aquifers ........................................................................................................................................ 11

Previous Investigations................................................................................................................................................ 12

Acknowledgments ....................................................................................................................................................... 13

Water-Quality Characteristics................................................................................................................................................ 13

Sampling Sites and Methods ....................................................................................................................................... 13

Water-Quality Criteria ................................................................................................................................................. 17

Water-Quality Characteristics of Selected Aquifers.................................................................................................... 25

Physical Properties ............................................................................................................................................ 25

Common Ions .................................................................................................................................................... 42

Precambrian Aquifers.............................................................................................................................. 42

Deadwood Aquifer .................................................................................................................................. 42

Madison Aquifer...................................................................................................................................... 65

Minnelusa Aquifer................................................................................................................................... 65

Minnekahta Aquifer................................................................................................................................. 67

Inyan Kara Aquifer.................................................................................................................................. 67

Minor Aquifers ........................................................................................................................................ 68

Nutrients ............................................................................................................................................................ 69

Trace Elements .................................................................................................................................................. 75

Precambrian Aquifers.............................................................................................................................. 75

Deadwood Aquifer .................................................................................................................................. 90

Madison Aquifer...................................................................................................................................... 90

Minnelusa Aquifer................................................................................................................................... 90

Minnekahta Aquifer................................................................................................................................. 90

Inyan Kara Aquifer.................................................................................................................................. 90

Minor Aquifers ........................................................................................................................................ 92

Radionuclides .................................................................................................................................................... 92

Deadwood Aquifer .................................................................................................................................. 102

Madison Aquifer...................................................................................................................................... 102

Minnelusa Aquifer................................................................................................................................... 106

Inyan Kara Aquifer.................................................................................................................................. 106

Minor Aquifers ........................................................................................................................................ 106

Summary for Aquifers in Relation to Water Use............................................................................................... 106

Water-Quality Characteristics of Selected Surface-Water Sites .................................................................................. 107

Physical Properties ............................................................................................................................................ 108

Group Comparisons................................................................................................................................. 108

Additional Comparisons.......................................................................................................................... 118

Common Ions .................................................................................................................................................... 121

Group Comparisons................................................................................................................................. 121

Additional Comparisons.......................................................................................................................... 132
IV Contents

CONTENTS—Continued

Water-Quality Characteristics—Continued

Water-Quality Characteristics of Selected Surface-Water Sites—Continued

Nutrients............................................................................................................................................................ 137

Group Comparisons ................................................................................................................................ 137

Additional Comparisons ......................................................................................................................... 142

Trace Elements.................................................................................................................................................. 144

Group Comparisons ................................................................................................................................ 144

Additional Comparisons ......................................................................................................................... 154

Radionuclides.................................................................................................................................................... 154

Summary for Surface-Water Groups in Relation to Water Use ........................................................................ 164

Summary ............................................................................................................................................................................... 165

References............................................................................................................................................................................. 168

Supplemental Information..................................................................................................................................................... 173

FIGURES

1. Map showing area of investigation for the Black Hills Hydrology Study.............................................................. 4

2. Stratigraphic section for the Black Hills................................................................................................................. 6

3. Map showing distribution of hydrogeologic units in the Black Hills area ............................................................. 7

4. Geologic cross section A-A′ ................................................................................................................................... 8

5. Schematic showing simplified hydrogeologic setting of the Black Hills area ....................................................... 10

6. Map showing location of ground-water sampling sites .......................................................................................... 14

7. Map showing location of selected surface-water sampling sites by group............................................................. 15

7a. Map showing location of selected surface-water sampling sites in the Rapid Creek Basin................................... 16

8. Graphs showing relations between water hardness and freshwater aquatic-life

standards for acute and chronic toxicity of selected trace elements ....................................................................... 24

9. Boxplots of physical properties for selected aquifers ............................................................................................. 29

10. Graphs showing selected relations between physical properties and well depth for selected aquifers .................. 32

11-15. Map showing distribution of:

11. Water temperature in the Madison aquifer..................................................................................................... 36

12. Specific conductance in the Madison aquifer ................................................................................................ 38

13. Specific conductance in the Minnelusa aquifer.............................................................................................. 39

14. Specific conductance in the Inyan Kara aquifer............................................................................................. 40

15. Hardness in the Inyan Kara aquifer................................................................................................................ 41

16. Boxplots of concentrations of selected common ions for selected aquifers ........................................................... 48

17. Trilinear diagrams showing proportional concentrations of major ions in selected aquifers ................................. 54

18. South Dakota irrigation-water classification diagram ............................................................................................ 57

19. Graphs showing relations between sulfate and specific conductance in the Madison,

Minnelusa, and Inyan Kara aquifers ....................................................................................................................... 58

20. Graphs showing selected relations between common ions and well depth for selected aquifers........................... 59

21. Map showing distribution of sulfate concentrations in the Minnelusa aquifer....................................................... 66

22. Boxplots of concentrations of selected nutrients for selected aquifers................................................................... 73

23. Boxplots of concentrations of selected trace elements for selected aquifers.......................................................... 83

24. Graphs showing selected relations between trace elements and well depth for selected aquifers.......................... 91

25. Boxplots of concentrations of selected radionuclides for selected aquifers ........................................................... 98

26. Graphs showing selected relations between radionuclides and well depth for selected aquifers ........................... 103

27. Map showing distribution of radon concentrations in the Deadwood aquifer........................................................ 105

28. Boxplots of concentrations of selected properties by surface-water group ............................................................ 109

29. Duration hydrographs of daily mean flow for selected headwater, crystalline,

artesian, and exterior surface-water group sites...................................................................................................... 112

30. Graphs showing relations between discharge and specific conductance for selected

sampling sites by surface-water group.................................................................................................................... 116

31. Graph showing relations between temperature and dissolved oxygen for selected surface-water groups ............. 117
Contents V

FIGURES—Continued

32. Boxplots of specific conductance and hardness for selected surface-water sites in Rapid Creek Basin................ 119

33. Graph showing downstream progression of pH for selected streams influenced by acid mine drainage............... 120

34. Boxplots of concentrations of selected ions by surface-water group...................................................................... 124

35. Graph showing relation between specific conductance and dissolved solids by surface-water group................... 128

36. Trilinear diagrams showing proportional concentrations of major ions by surface-water group ........................... 129

37. Stiff diagrams for surface-water groups and selected sites..................................................................................... 130

38. Map showing spatial distribution of median calcium concentrations in surface water .......................................... 133

39. Map showing spatial distribution of median sulfate concentrations in surface water ............................................ 134

40. Graph showing relation between specific conductance and calcium, sodium, and

sulfate concentrations in surface water ................................................................................................................... 135

41. Boxplots of selected ions for selected surface-water sites in Rapid Creek Basin................................................... 136

42. Graph showing changes in selected ions at Bear Butte Creek near Deadwood, 1988-97 ...................................... 137

43. Boxplots of concentrations of selected nutrients by surface-water group .............................................................. 138

44. Graph showing nitrite plus nitrate concentrations in Annie Creek near Lead, 1988-97......................................... 141

45. Graph showing nitrite plus nitrate concentrations at Horse Creek near Vale and Horse Creek above Vale........... 142

46. Boxplots of selected nutrients for selected surface-water sites in Rapid Creek Basin ........................................... 143

47. Boxplots of concentrations of selected trace elements by surface-water group ..................................................... 148

48. Map showing spatial distribution of maximum arsenic concentrations in surface water ....................................... 155

49. Map showing spatial distribution of median manganese concentrations in surface water ..................................... 156

50. Map showing spatial distribution of maximum selenium concentrations in surface water.................................... 157

51. Graph showing comparison of dissolved copper concentrations to hardness-dependent

chronic and acute aquatic-life criteria for Bear Butte Creek near Deadwood ........................................................ 158

52. Boxplots of concentrations of selected radionuclides by surface-water group....................................................... 160

53. Map showing spatial distribution of median gross beta as cesium-137 concentrations in surface water............... 162

54. Map showing spatial distribution of median uranium concentrations in surface water.......................................... 163

TABLES

1. Water-quality criteria, standards, or recommended limits and general significance for

selected properties or constituents.......................................................................................................................... 18

2. Surface-water-quality standards for selected physical properties and constituents................................................ 22

3. Summary of physical properties in ground water................................................................................................... 26

4. Summary of concentrations of common ions in ground water............................................................................... 43

5. Relation between specific conductance and dissolved solids for selected aquifers ............................................... 56

6. Summary of concentrations of nutrients in ground water ...................................................................................... 70

7. Summary of concentrations of trace elements in ground water ............................................................................. 76

8. Summary of concentrations of radionuclides in ground water............................................................................... 93

9. Summary of physical properties in surface water by group ................................................................................... 114

10. Summary of concentrations of common ions in surface water by group ............................................................... 122

11. Relation between specific conductance and dissolved solids for selected surface-water groups........................... 132

12. Summary of concentrations of nutrients in surface water by group....................................................................... 140

13. Summary of concentrations of trace elements in surface water by group.............................................................. 145

14. Summary of concentrations for radionuclides in surface water by group .............................................................. 159

15. Ground-water sampling sites summarized in this report ........................................................................................ 175

16. Surface-water sampling sites summarized in this report ........................................................................................ 193
VI Contents

CONVERSION FACTORS AND VERTICAL DATUM

Temperature can be converted to degrees Fahrenheit (°F) or degrees Celsius (°C) by the following

equations:

°F = 9/5 (°C) + 32

°C = 5/9 (°F-32)

Chemical concentrations: Chemical concentrations of substances in water are given in metric units

of milligrams per liter (mg/L) and micrograms per liter (μg/L). Milligrams per liter is a unit expressing the concentration of chemical constituents in solution as mass (milligrams) of solute per unit volume (liter) of water. Micrograms per liter is a unit expressing the concentration of chemical

constituents in solution as mass (micrograms) of solute per unit volume (liter) of water. Micrograms

per liter are equivalent to milligrams per liter divided by 1,000.

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD

of 1929)—a geodetic datum derived from a general adjustment of the first-order level nets of both

the United States and Canada, formerly called Sea Level Datum of 1929.

Water year: Water year is the 12-month period, October 1 through September 30, and is designated

by the calendar year in which it ends. Thus, the water year ending September 30, 1992, is called the

“1992 water year.”

OTHER ABBREVIATIONS, SYMBOLS, AND ACRONYMS USED:

Multiply By To obtain

cubic foot per second 0.02832 cubic meter per second 

foot 0.3048 meter

inch 2.54 centimeter

inch 25.4 millimeter

mile 1.609 kilometer

mg/L

μg/L

μS/cm

pCi/L

TU

<

milligrams per liter

micrograms per liter

microsiemens per centimeter at 25 degrees Celsius

picocuries per liter

tritium units

less than

DENR

MCL

NURE

NWIS

NWQL

SMCL

USEPA

USGS

South Dakota Department of Environment and 

Natural Resources

Maximum Contaminant Level

National Uranium Resource Evaluation

U.S. Geological Survey National Water 

Information System

U.S. Geological Survey National Water Quality 

Laboratory

Secondary Maximum Contaminant Level

U.S. Environmental Protection Agency

U.S. Geological Survey
Abstract 1

Water-Quality Characteristics in the

Black Hills Area, South Dakota

By Joyce E. Williamson and Janet M. Carter

ABSTRACT

This report summarizes the water-quality 

characteristics of ground water and surface water 

in the Black Hills area. Differences in groundwater quality by aquifer and differences in surfacewater quality by water source are presented. 

Ground-water characteristics are discussed individually for each of the major aquifers in the Black 

Hills area, referred to herein as the Precambrian, 

Deadwood, Madison, Minnelusa, Minnekahta, 

and Inyan Kara aquifers. Characteristics for minor 

aquifers also are discussed briefly. Surface-water 

characteristics are discussed for hydrogeologic 

settings including headwater springs, crystalline 

core sites, artesian springs, and exterior sites.

To characterize the water quality of aquifers 

and streams in the Black Hills area, data from the 

U.S. Geological Survey National Water Information System water-quality database were examined. This included samples collected as part of 

the Black Hills Hydrology Study as well as for 

other studies within the time frame of October 1, 

1930, to September 30, 1998. Tables of individual 

results are not presented in this report, only summaries. Constituents summarized and discussed 

include physical properties, common ions, nutrients, trace elements, and radionuclides. Comparisons of concentration levels are made to drinkingwater standards as well as beneficial-use and 

aquatic-life criteria.

Ground water within the Black Hills and 

surrounding area generally is fresh and hard to 

very hard. Concentrations exceeding various 

Secondary and Maximum Contaminant Levels 

may affect the use of the water in some areas for 

many aquifers within the study area. Concentrations that exceed Secondary Maximum Contaminant Levels (SMCL’s) generally affect the water 

only aesthetically. Radionuclide concentrations 

may be especially high in some of the major 

aquifers used within the study area and preclude 

the use of water in some areas. The sodiumadsorption ratio and specific conductance may 

affect irrigation use for some wells.

High concentrations of iron and manganese 

are the only concentrations that may hamper the 

use of water from Precambrian aquifers. The 

principal deterrents to use of water from the 

Deadwood aquifer are the high concentrations of 

radionuclides as well as iron and manganese. Iron, 

manganese, and hardness may deter use of water 

from the Madison aquifer as well as dissolved solids and sulfate in downgradient wells (generally 

deeper than 2,000 feet). Iron, manganese, and 

hardness may also deter use of the Minnelusa aquifer. Water from the Minnekahta aquifer generally 

is suitable for all water uses although it is hard to 

very hard. High concentrations of dissolved 

solids, iron, sulfate, and manganese may hamper 

the use of water from the Inyan Kara aquifer. In 

the southern Black Hills, radium-226 and uranium 

concentrations also may preclude use of water 

from the Inyan Kara aquifer. Suitability for irrigation may be affected by high specific conductance 

and sodium-adsorption ratio for the Inyan Kara.
2 Water-Quality Characteristics in the Black Hills Area, South Dakota

Surface-water quality within the Black Hills 

and surrounding area generally is very good but 

the water is hard to very hard. Concentrations of 

some constituents in the study area tend to be 

higher exterior to the Black Hills, primarily due to 

influences from the Cretaceous-age marine shales, 

including dissolved solids, sodium, sulfate, selenium, and uranium. Headwater springs have relatively constant discharge, specific conductance, 

dissolved solids, and concentrations of most other 

constituents.

Concentrations at crystalline core sites are 

very similar to those found in samples from Precambrian aquifers. Some high nitrate concentrations greater than the Maximum Contaminant 

Level (MCL) of 10 mg/L (milligrams per liter) 

have occurred at Annie Creek near Lead, which 

have been attributed to mining impacts. Trace 

elements generally are low with the exception of 

arsenic, for which 60 percent of samples exceed 

the proposed MCL of 10 μg/L (micrograms per 

liter) and one sample exceeds the current MCL of 

50 μg/L. The SMCL’s for iron and manganese 

also have been exceeded in some samples. Artesian springs have very constant discharge and 

specific conductance at each site but show some 

variability between sites. Dissolved solids concentrations exceeding the SMCL of 500 mg/L and 

sulfate concentrations exceeding the SMCL of 

250 mg/L are common for these sites. 

Low dissolved oxygen concentrations in 

surface waters only occur at sites exterior to the 

Black Hills where high temperature and low flow 

occasionally are problematic. About 66 percent of 

the samples from sites exterior to the Black Hills 

exceed 1,000 mg/L sulfate. Concentrations 

exceeding the arsenic MCL, the selenium aquaticlife criterion, and the iron and manganese SMCL’s 

occasionally occur at these sites. Radionuclide 

data are limited, but higher uranium concentrations are found for the areas exterior to the Inyan 

Kara Group outcrop.

Occasionally very low pH levels are 

recorded immediately downstream from abandoned mine sites but generally are within acceptable ranges once they mix with additional stream 

water. Changes in specific conductance, sodium, 

and sulfate in Bear Butte Creek occurred after 

additional mining activities in a tributary basin. 

Bear Butte Creek also had exceedances of the 

acute and chronic copper aquatic-life criteria for 

several samples between 1992-94. Within-basin 

changes for Rapid Creek follow the general trend 

of increasing concentrations for most constituents. 

Nutrient levels are low but do show an increase, 

indicating that land-use practices, both urban and 

agricultural, may be affecting the stream. 

INTRODUCTION

The Black Hills area is an important resource 

center for the State of South Dakota. The Black Hills 

provide an economic base for western South Dakota 

through tourism, agriculture, the timber industry, and 

mineral resources. In addition to these resources, one 

of the most important natural resources in the Black 

Hills is water. Water originating from the area is used 

for municipal, industrial, agricultural, and recreational 

purposes throughout much of western South Dakota 

and is important recharge for aquifers in the northern 

Great Plains. 

Population growth and resource development 

have the potential to affect the quantity, quality, and 

availability of water within the Black Hills area. 

Because of this concern, 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 Hills area of South Dakota (Driscoll, 

1992). This long-term study is a cooperative effort 

between the U.S. Geological Survey (USGS), the 

South Dakota Department of Environment and Natural 

Resources (DENR), and the West Dakota Water 

Development District, which represents various local 

and county cooperators. 

Ground-water quality in the area is heavily 

influenced by the mineralogy of the specific geologic 

unit containing the aquifer. Surface-water quality is 

heavily influenced by underlying geology and streamflow. Both ground-water and surface-water quality 

may be influenced by human effects related to land use. 

An assessment of the quality of ground and surface 

water is important for managing the water resources in 

the Black Hills area and providing a baseline for 

comparison of future water-quality data.
Introduction 3

Purpose and Scope

The purpose of this report is to summarize the 

water-quality characteristics of ground water and 

surface water in the Black Hills. Comparisons of water 

quality by aquifer and comparisons of surface-water 

quality by water source are presented. Ground-waterquality characteristics are discussed individually for 

each of the major aquifers in the Black Hills area, 

referred to in this report as the Precambrian, Deadwood, Madison, Minnelusa, Minnekahta, and Inyan 

Kara aquifers. Characteristics for minor aquifers, 

referred to in this report as the Spearfish, Sundance, 

Morrison, Pierre, Graneros, Newcastle, and alluvial 

aquifers, are discussed briefly. Surface-water-quality 

characteristics are discussed for various hydrogeologic 

settings including headwater springs, crystalline core 

basins, artesian springs, and exterior basins (downgradient of the outcrop of the Inyan Kara Group). For 

some comparisons or descriptions, surface-water 

characteristics are discussed for selected basins, groups 

of sites, or selected sites. Comparisons are made for 

physical properties, major-ion chemistry, nutrients, 

trace elements, and radionuclide concentrations. 

Where sufficient data are available, spatial variations 

are presented.

Description of Study Area

The study area consists of the topographically 

defined Black Hills and adjacent areas located in 

western South Dakota (fig. 1). The generalized outer 

extent of the Inyan Kara Group, which approximates 

the outer extent of the Black Hills area, also is shown 

in figure 1. About 32 percent of the study area is within 

the boundaries of the Black Hills National Forest, 

which was created in 1897. The Black Hills are situated between the Cheyenne and Belle Fourche Rivers. 

The Belle Fourche River 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.

Physiography and Climate

The Black Hills uplift formed as an elongated 

dome about 60 to 65 million years ago (DeWitt and 

others, 1986). The dome trends north-northwest and is 

about 120 miles long and 60 miles wide. Elevations 

range from 7,242 feet above sea level at Harney Peak 

to about 3,000 feet in the adjacent plains. Most of the 

higher elevations are heavily forested with ponderosa 

pine, which is the primary product of an active timber 

industry. White spruce, quaking aspen, paper birch, 

and other native trees and shrubs are found in cooler, 

wetter areas (Orr, 1959). The lower elevation areas 

surrounding the Black Hills primarily are urban, suburban, and agricultural. Numerous deciduous species 

such as cottonwood, ash, elm, oak, and willow are 

common along stream bottoms in the lower elevations. 

Rangeland, hayland, and winter wheat farming are the 

principal agricultural uses for dryland areas. Alfalfa, 

corn, and vegetables are produced in bottom lands and 

in irrigated areas. Various other crops, primarily for 

cattle fodder, are produced in both dryland areas and in 

bottom lands.

Beginning in the 1870’s, the Black Hills have 

been explored and mined for many commodities 

including gold, silver, tin, tungsten, mica, feldspar, 

bentonite, beryl, lead, zinc, uranium, lithium, sand, 

gravel, and oil (U.S. Department of Interior, 1967). 

Mines within the study area have utilized placer 

mining, small surface pits, underground mines, and 

open-pit mines. 

The overall climate of the study area is continental, with generally low precipitation, hot summers, 

cold winters, and extreme variations in both precipitation and temperatures (Johnson, 1933). Local climatic 

conditions are affected by topography, with generally 

lower temperatures and higher precipitation at the 

higher elevations. The average annual precipitation for 

the study area (1931-98) is 18.61 inches, and has 

ranged from 10.22 inches for water year 1936 to 

27.39 inches for water year 1995 (Driscoll, Hamade, 

and Kenner, 2000). The largest precipitation amounts 

typically occur in the northern Black Hills near Lead, 

where average annual precipitation (1950-98) exceeds 

29 inches. Annual averages (1931-98) for counties 

within the study area range from 16.35 inches for Fall 

River County to 23.11 inches for Lawrence County. 

The average annual temperature is 43.9°F (U.S. 

Department of Commerce, 1999) and ranges from 

48.7°F at Hot Springs to approximately 37°F near 

Deerfield Reservoir. Average evaporation generally 

exceeds average annual precipitation throughout the 

study area. Average pan evaporation for April through 

October is about 30 inches at Pactola Reservoir and 

about 50 inches at Oral.
4 Water-Quality Characteristics in the Black Hills Area, South Dakota

EXPLANATION

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Figure 1. Area of investigation for the Black Hills Hydrology Study.

0 10 20

0 10 20 MILES

KILOMETERS

SOUTH DAKOTA

Study

Area

Black

Hills

APPROXIMATE EXTENT OF

 THE BLACK HILLS AREA,

 REPRESENTED BY

 GENERALIZED OUTER

 EXTENT OF INYAN KARA 

 GROUP (modified from

 Strobel and others, 1999)

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
Introduction 5

Geologic Setting

The geologic units that contain aquifers for 

which water-quality characteristics are presented are 

described in this section from oldest to youngest. The 

oldest geologic units in the study area are the Precambrian crystalline (metamorphic and igneous) rocks 

(fig. 2), which form a basement under the Paleozoic, 

Mesozoic, and Cenozoic rocks and sediments. The 

Precambrian rocks are exposed in the central core of 

the Black Hills. These Precambrian rocks range in age 

from 1.7 to about 2.5 billion years, and were eroded to 

a gentle undulating plain by the beginning of the Paleozoic Era (Gries, 1996). The Precambrian rocks are 

highly variable, but are composed mostly of metasediments, such as schists and graywackes. The Paleozoic 

and Mesozoic rocks were deposited as nearly horizontal beds. Subsequent uplift during the Laramide 

orogeny and related erosion exposed the Precambrian 

rocks in the central core of the Black Hills with the 

Paleozoic and Mesozoic sedimentary rocks exposed in 

roughly concentric rings around the core. Deformation 

during the Laramide orogeny contributed to the 

numerous fractures, folds, and other structural features 

present throughout the Black Hills. Tertiary intrusive 

activity also contributed to rock fracturing in the 

northern Black Hills where numerous intrusions exist.

Surrounding the crystalline core is a layered 

series of sedimentary rocks including limestones, sandstones, and shales. The distribution of hydrogeologic 

units in the Black Hills area is shown in figure 3. The 

bedrock sedimentary units typically dip away from the 

uplifted Black Hills at angles that can approach or 

exceed 15 to 20 degrees near the outcrops, and 

decrease with distance from the uplift to less than 

1 degree (Carter and Redden, 1999a, 1999b, 1999c, 

1999d, 1999e) (fig. 4). 

The oldest sedimentary unit in the study area is 

the Cambrian- and Ordovician-age Deadwood Formation, which is composed primarily of brown to lightgray glauconitic sandstone, shale, limestone, and local 

basal conglomerate (Strobel and others, 1999). These 

sediments were deposited on the generally horizontal 

plain of Precambrian rocks in a coastal- to near-shore 

environment (Gries, 1975). The thickness of the 

Deadwood Formation increases from south to north in 

the study area and ranges from 0 to 500 feet (Carter and 

Redden, 1999e). In the northern and central Black 

Hills, the Deadwood Formation is disconformably 

overlain by Ordovician-age rocks that include the 

Whitewood and Winnipeg Formations. The Winnipeg 

Formation is absent in the southern Black Hills, and the 

Whitewood Formation has eroded to the south and is 

not present south of the approximate latitude of Nemo 

(DeWitt and others, 1986). In the southern Black Hills, 

the Deadwood Formation is unconformably overlain 

by the Devonian- and Mississippian-age Englewood 

Formation because of the absence of the Ordovicianage sequence. The Englewood Formation is overlain 

by the Madison Limestone.

The Mississippian-age Madison Limestone, 

deposited as a marine carbonate, is a massive, gray to 

buff limestone that is locally dolomitic (Strobel and 

others, 1999). The thickness of the Madison Limestone 

increases from south to north in the study area and 

ranges from almost zero in the southeast corner of the 

study area (Rahn, 1985) to 1,000 feet east of Belle 

Fourche (Carter and Redden, 1999d). The Madison 

Limestone was exposed above land surface for approximately 50 million years. During this period, significant erosion, soil development, and karstification 

occurred (Gries, 1996). Numerous caves and fractures 

occur within the upper part of the formation (Peter, 

1985). Because the Madison Limestone was exposed 

to erosion and karstification for millions of years, the 

formation is unconformably overlain by the Minnelusa 

Formation.

The Pennsylvanian- and Permian-age Minnelusa 

Formation consists mostly of yellow to red crossstratified sandstone, limestone, dolomite, and shale 

(Strobel and others, 1999). In addition to sandstone 

and dolomite, the lower part of the formation consists 

of shale and anhydrite (DeWitt and others, 1986). The 

upper part of the Minnelusa Formation also may 

contain anhydrite, which generally has been removed 

by dissolution at or near the outcrop areas, forming 

collapse features filled with breccia (Bowles and 

Braddock, 1963). The thickness of the Minnelusa 

Formation increases from north to south and ranges 

from 375 feet near Belle Fourche to 1,175 feet near 

Edgemont in the study area (Carter and Redden, 

1999c). On the southwest side of the study area, there 

is a considerable increase in thickness of clastic units as 

well as a thick section of anhydrite. In the southern 

Black Hills, the upper part of the Minnelusa Formation 

thins due to leaching of anhydrite. The Minnelusa 

Formation is disconformably overlain by the Permianage Opeche Shale, which is overlain by the Minnekahta 

Limestone.

The Permian-age Minnekahta Limestone is a 

fine-grained, purple to gray laminated limestone with 

thicknesses ranging from 25 to 65 feet in the study area 

(Strobel and others, 1999). The Minnekahta Limestone 

is overlain by the Triassic- and Permian-age Spearfish 

Formation. 
6 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 2. Stratigraphic section for the Black Hills.

STRATIGRAPHIC UNIT DESCRIPTION THICKNESS IN FEET

ABBREVIATION

FOR

STRATIGRAPHIC

INTERVAL

SYSTEM ERATHEM

QUATERNARY

& TERTIARY (?)

UNDIFFERENTIATED SANDS AND GRAVELS 0-50 Sand, gravel, and boulders

1,200-2,700

Light colored clays with sandstone channel fillings and local limestone lenses. WHITE RIVER GROUP Tw

TERTIARY

QTu

Principal horizon of limestone lenses giving teepee buttes. Dark-gray shale containing scattered concretions. Widely scattered limestone masses, giving small teepee buttes. Black fissile shale with concretions. 

PIERRE SHALENIOBRARA FORMATION 180-300 Impure chalk and calcareous shale.

CARLILE SHALE Turner Sandy Member

Wall Creek Member

1350-750 Light-gray shale with numerous large concretions and sandy layers.

Dark-gray shale

GRANEROS GROUP

GREENHORN FORMATION

Kps

225-380 Impure slabby limestone. Weathers buff.

Dark-gray calcareous shale, with thin Orman Lake limestone at base.

BELLE FOURCHE SHALE

MOWRY SHALE

MUDDY

SANDSTONE

NEWCASTLESANDSTONE

SKULL CREEK SHALE

150-850

Gray shale with scattered limestone concretions.Clay spur bentonite at base.

125-230

0-150

Light-gray siliceous shale. Fish scales and thin layers of bentonite.Brown to light yellow and white sandstone.

150-270 Dark gray to black siliceous shale.

CRETACEOUS

FALL RIVER FORMATION

LAKOTA

FM

INYAN KARA

GROUPFuson Shale Minnewaste Limestone Chilson Member

10-200 Massive to slabby sandstone.

Coarse gray to buff cross-bedded conglomeratic sandstone, interbedded with buff, red, and gray clay, especially toward top. Local fine-grained limestone.

10-190

0-25

25-485

0-2200-225

Light-gray claystone and shale. Thin sandstone.Massive fine-grained sandstone.

250-450

0-45

Greenish-gray shale, thin limestone lenses.Glauconltic sandstone; red sandstone near middle.Red siltstone, gypsum, and limestone.

MORRISON FORMATION

UNKPAPA SS Redwater Member

Lak MemberHulett MemberStockade Beaver Mem.Canyon Spr Member

SUNDANCEFORMATIONGYPSUM SPRING FORMATION

Kik

Ju JURASSIC

Goose Egg Equivalent

SPEARFISH FORMATION RT Ps TRIASSIC

MINNEKAHTA LIMESTONEOPECHE SHALE Po

Pmk

375-800

125-65

Red sandy shale, soft red sandstone and siltstone with gypsum and thin limestone layers.Gypsum locally near the base.Thin to medium-bedded finely-crystalline, purplish gray laminated limestone.Red shale and sandstone. 125-150

1375-1,1751250-1,000

30-60

10-23510-15010-500

Yellow to red cross-bedded sandstone, limestone, and anhydrite locally at top.Red shale with interbedded limestone and sandstone at base.Massive light-colored limestone. Dolomite in part. Cavernous in upper part.Pink to buff limestone. Shale locally at base.Buff dolomite and limestone.Green shale with siltstone.Massive to thin-bedded brown to light-gray sandstone. Greenish glauconitic shale flaggy dolomite and flat-pebble limestone conglomerate. Sandstone, with conglomeratelocally at the base.Schist, slate, quartzite, and arkosic grit. Intruded by diorite, metamorphosed to amphibolite, and by granite and pegmatite.

PERMIAN

PENNSYLVANIAN

MISSISSIPPIAN

P Pm MINNELUSA FORMATION

MADISON (PAHASAPA) LIMESTONEENGLEWOOD FORMATION

MDme

Ou

DEVONIAN

WHITEWOOD (RED RIVER) FORMATIONWINNIPEG FORMATIONDEADWOOD FORMATIONUNDIFFERENTIATED METAMORPHICAND IGNEOUS ROCKS

OCd

pCu

ORDOVICIAN

CAMBRIAN

PRECAMBRIAN

CENOZOIC

MESOZOIC

PALEOZOIC

Modified from information furnished by the Department of Geology and Geological Engineering,

South Dakota School of Mines and Technology (written commun., January 1994)

0-300

Includes rhyolite, latite, trachyte, and phonolite. INTRUSIVE IGNEOUS ROCKS Tui --

1 Modified based on drill-hole data

Interbedded sandstone, limestone, dolomite, shale, and anhydrite.
Introduction 7

Cascade

Springs

Rochford

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Pringle

Wild

Inlet

Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

QTac

Tw

Tui

Kps

Ju

TRPs

MDme

Kik

Pmk

Po

Ou

PPm

OCd

pCu

A

A'

Figure 3. Distribution of hydrogeologic units in the Black Hills area (modified from Strobel and others, 1999).

0 10 20

0 10 20 MILES

KILOMETERS

EXPLANATION

Alluvium and colluvium,

 undifferentiaed

Unconsolidated

units

White River aquifer

Minnekahta aquifer

Minnelusa aquifer

Madison aquifer

Deadwood aquifer

Inyan Kara aquifer

Tertiary intrusive

units

Spearfish confining

unit

Opeche confining unit

Cretaceoussequence

confining unit

Jurassic-sequence

semiconfining unit

Ordovician-sequence

semiconfining unit

Precambrian igneous

and

metamorphic units

White River Group

Undifferentiated intrusive

 igneous rocks

Pierre Shale to Skull Creek Shale,

 undifferentiated

Inyan Kara Group

Morrison Formation to Gypsum

 Spring Formation, undifferentiated

Spearfish Formation

Minnekahta Limestone

Opeche Shale

Minnelusa Formation

Madison (Pahasapa) Limestone

 and Englewood Formation

Whitewood Formation and

 Winnipeg Formation

Deadwood Formation

Undifferentiated metamorphic

 and igneous rocks

Stratigraphic

Units Map Units HydrogeologicUnits

A A' LINE OF GEOLOGIC SECTION

FAULT--Dashed where approximated.

 Bar and ball on downthrown side.

ANTICLINE--Showing trace of axial

 plane and direction of plunge.

 Dashed where approximated.

SYNCLINE--Showing trace of axial plane

 and direction of plunge. Dashed

 where approximated.

MONOCLINE--Showing trace of axial

 plane. Dashed where approximated.

DOME--Symbol size approximately pro-

 portional to size of dome. Dome

 asymmetry indicated by arrow length.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
8 Water-Quality Characteristics in the Black Hills Area, South Dakota

SEA

6,0005,0004,0003,0002,0001,000

LEVEL

SEA

LEVEL

FEET

7,0006,0005,0004,0003,0002,0001,000

A A'

FEET

7,000

MDme

MDme

Kps

Ju

Kik

PPm

PPm

OCd

OCd Pmk

Po QTac QTac

Rapid Creek Rapid Creek

South Fork Castle Creek

Highway 385

Rapid Creek

Highway 44

Rapid Creek

Rapid City

Rapid Creek

210

210 4 2

2 4 6 8 10 MILES

8 6 10 KILOMETERS

VERTICAL EXAGGERATION X5

T Ps R

Figure 4. Geologic cross section A-A' (Location of section is shown in figure 3. Abbreviations for stratigraphic intervals are explained in figure 2.).

Modified from Strobel and others, 1999

SOUTH DAKOTA

WYOMING

pCu pCu
Introduction 9

The Permian- and Triassic-age Spearfish Formation consists of red, silty shale interbedded with friable, 

red sandstone and siltstone, and sparse limestone layers 

(Strobel and others, 1999). The lower portion of the 

Spearfish Formation contains massive gypsum 

(Robinson and others, 1964). The thickness of the 

Spearfish Formation ranges from 375 to 800 feet (Gries 

and Martin, 1985).

Jurassic-age units consisting of shale and sandstone with some limestone and gypsum overlie the 

Spearfish Formation and include the Sundance and 

Morrison Formations. The Sundance Formation consists of reddish-gray to light-gray siltstone, sandstone, 

limestone, and glauconitic sandstone and shale (DeWitt 

and others, 1989) and is 250 to 450 feet thick in the 

study area (Strobel and others, 1999). The Morrison 

Formation is a light-gray siliceous claystone and shale 

(DeWitt and others, 1989) with a thickness that ranges 

from 0 to 220 feet (Strobel and others, 1999).

The Cretaceous-age Inyan Kara Group consists 

of the Lakota Formation and overlying Fall River 

Formation. The Lakota Formation consists of the 

Chilson, Minnewaste Limestone, and Fuson Shale 

members. The Lakota Formation consists of yellow, 

brown, and reddish-brown massive to thin-bedded 

sandstone, pebble conglomerate, siltstone, and claystone of fluvial origin (Gott and others, 1974); lenses of 

limestone and coal are present locally. The Fall River 

Formation is a brown to reddish-brown, fine-grained 

sandstone, thin bedded at the top and massive at the 

bottom (Strobel and others, 1999). The thickness of the 

Inyan Kara Group ranges from 135 to 900 feet in the 

study area (Carter and Redden, 1999a).

The Cretaceous-age Graneros Group includes 

the Skull Creek Shale, Newcastle Sandstone, Mowry 

Shale, and Belle Fourche Shale. The Skull Creek Shale 

is a dark gray to black siliceous shale and is 150 to 

270 feet thick (DeWitt and others, 1989). The 

Newcastle Sandstone is 0 to 100 feet thick and is a gray 

to light-brown sandstone and siltstone that contains 

beds of bentonite and lignite (DeWitt and others, 

1989). The Mowry Shale consists of light-gray siliceous shale with thin bentonite layers and is 125 to 

230 feet thick (DeWitt and others, 1989). The Belle 

Fourche Shale is a dark-gray bentonitic shale that contains minor limestone lenses and large concretions and 

is 150 to 850 feet thick (DeWitt and others, 1989).

The Cretaceous-age Pierre Shale is a dark-gray 

to black shale containing minor limestone lenses and 

concretions. The thickness of the Pierre Shale ranges 

from 1,200 to 2,700 feet (Strobel and others, 1999).

For purposes of this report, alluvial deposits refer 

to Quaternary-age alluvium, gravel deposits, and 

windblown deposits and Tertiary-age gravel deposits. 

Generally, the thickness of these deposits ranges from 

0 to 50 feet. 

Hydrologic Setting

The hydrologic setting of the Black Hills area is 

schematically illustrated in figure 5. The major 

aquifers in the Black Hills area are the Deadwood, 

Madison, Minnelusa, Minnekahta, and Inyan Kara 

aquifers. Aquifers in the Precambrian rocks also were 

considered as a major aquifer in this report because 

numerous wells are completed in this unit. In some 

local areas, wells are completed in strata that generally 

are considered semiconfining or confining units. These 

local water-bearing strata are referred to as minor 

aquifers in this report. This section describes the 

hydrologic setting for the major and minor aquifers 

considered in this report.

Major Aquifers

The Precambrian basement rocks generally have 

low permeability and form the lower confining unit for 

the series of sedimentary aquifers in the Black Hills 

area. Localized aquifers occur in Precambrian rocks at 

many locations in the central core of the Black Hills, 

where enhanced secondary permeability results from 

weathering and fracturing. These localized aquifers are 

referred to as the Precambrian aquifers in this report. In 

the Precambrian aquifers, water-table (unconfined) 

conditions generally prevail and land-surface topography can strongly control ground-water flow directions. Many wells completed in the Precambrian 

aquifers are located along stream channels.

Many of the sedimentary units contain aquifers, 

both within and beyond the study area. Within the 

Paleozoic rock interval, aquifers in the Deadwood 

Formation, Madison Limestone, Minnelusa Formation, 

and Minnekahta Limestone are used extensively. 

These aquifers are collectively confined by the underlying Precambrian rocks and the overlying Spearfish 

Formation. Individually, these aquifers are separated 

by minor confining layers or by relatively impermeable 

layers within the individual units. In general, groundwater flow in these aquifers is radially outward from 

the central core of the Black Hills. Although the lateral 

component of flow predominates, extremely variable 

leakage (vertical component of flow) can occur 

between these aquifers (Peter, 1985; Greene, 1993).
1

0Water-QualityCharacteristicsintheBlackHillsArea,SouthDakota

Deadwood

Madison

Inyan Kara Group Formation

Limestone

Precambrian metamorphicand igneous rocks

L mi estone

Minnekahta Minnelusa

Madison

Limestone

Formation

Fo mr ation

Deadwood

MinnelusaFormation

Alluvialaquifer

Potentiometricsurface ofMadisonaquifer

Springconduit

Water

table

Cave

Figure 5. Schematic showing simplified hydrogeologic setting of the Black Hills area.

MAJOR AQUIFERSCONFINING UNIT

Flowing well

EXPLANATION

LIMESTONE PLATEAU

Headwater

springs

Artesian

springs

Dip of sedimentary rocks exaggeratedRelative thickness NOT TO SCALE
Introduction 11

The Deadwood Formation contains the Deadwood aquifer, which overlies the Precambrian rocks. 

In general, the Deadwood aquifer serves as a source of 

water mainly for domestic and municipal users near its 

outcrop area. There may be some hydraulic connection 

between the Deadwood and the underlying weathered 

Precambrian rocks, but regionally the Precambrian 

rocks act as a lower confining unit to the Deadwood 

aquifer. Where present, the Whitewood and Winnipeg 

Formations act as a semiconfining unit overlying the 

Deadwood aquifer (Strobel and others, 1999). These 

units locally may transmit and exchange water with the 

Deadwood aquifer, but regionally are not considered 

aquifers. Where the Whitewood and Winnipeg Formations are absent, the Deadwood aquifer is in contact 

with the overlying Englewood Formation, which 

Strobel and others (1999) included as part of the 

Madison aquifer.

The Madison aquifer generally occurs within the 

karstic upper part of the Madison Limestone; however, 

Strobel and others (1999) included the entire Madison 

Limestone and underlying Englewood Formation in 

their delineation of the aquifer. Numerous fractures 

and solution openings in the Madison Limestone 

provide extensive secondary porosity in the aquifer. 

The Madison aquifer generally is confined by low 

permeability layers in the overlying Minnelusa 

Formation.

The Minnelusa aquifer occurs within layers of 

sandstone, dolomite, and anhydrite in the lower portion 

of the Minnelusa Formation and sandstone and anhydrite in the upper portion. The Minnelusa aquifer has 

primary porosity in the sandstone units and secondary 

porosity from collapse breccia associated with solution 

of interbedded evaporites and fracturing. The 

Minnelusa aquifer is confined by the overlying Opeche 

Shale and by low-permeability layers within the 

Minnelusa Formation.

The Minnekahta aquifer, which overlies the 

Opeche Shale, typically is very permeable, but well 

yields are limited by the aquifer thickness. The overlying Spearfish Formation acts as a confining unit to 

the aquifer. 

Within the Mesozoic rock interval, the Inyan 

Kara Group contains an aquifer that is used extensively. As much as 4,000 feet of Cretaceous shales act 

as the upper confining layer to the Inyan Kara aquifer.

Artesian (confined) conditions generally exist 

within the aforementioned aquifers where an upper 

confining layer is present. Under artesian conditions, 

water in a well will rise above the top of the aquifer in 

which it is completed. Flowing wells will result when 

drilled in areas where the potentiometric surface is 

above the land surface. Flowing wells and artesian 

springs that originate from confined aquifers are 

common around the periphery of the Black Hills.

Numerous headwater springs originating from 

the Paleozoic units at high elevations on the western 

side of the study area provide base flow for many 

streams. These streams flow across the central core of 

the Black Hills, and most streams generally lose all or 

part of their flow as they cross the outcrops of the 

Madison Limestone (Rahn and Gries, 1973; Hortness 

and Driscoll, 1998). Karst features of the Madison 

Limestone, including sinkholes, collapse features, 

solution cavities, and caves, are responsible for the 

Madison aquifer’s capacity to accept recharge from 

streamflow. Large streamflow losses also occur in 

many locations within the outcrop of the Minnelusa 

Formation (Hortness and Driscoll, 1998). Large artesian springs occur in many locations downgradient 

from these loss zones, most commonly within or near 

the outcrop of the Spearfish Formation. These springs 

provide an important source of base flow in many 

streams beyond the periphery of the Black Hills (Rahn 

and Gries, 1973; Miller and Driscoll, 1998).

Minor Aquifers

In addition to the major aquifers, many other 

aquifers, such as the Newcastle and alluvial aquifers, 

are used throughout the study area. In addition, many 

of the semiconfining and confining units shown in 

figure 3 may contain local aquifers. These other and 

local aquifers are considered minor aquifers in this 

report. This section provides a brief overview from 

Strobel and others (1999) of the minor aquifers for 

which water-quality data are available. 

Local aquifers may exist in the Spearfish confining unit where gypsum and anhydrite have been dissolved, increasing porosity and permeability; these 

aquifers are referred to as the Spearfish aquifer in this 

report. The Jurassic-sequence semiconfining unit consists of shales and sandstones. Overall, this unit is 

semiconfining because of the low permeability of the 

interbedded shales; however, local aquifers do exist in 

some formations such as the Sundance and Morrison 

Formation. These aquifers are referred to as the 

Sundance and Morrison aquifers in this report.
12 Water-Quality Characteristics in the Black Hills Area, South Dakota

The Cretaceous-sequence confining unit mainly 

includes shales of low permeability, such as the Pierre 

Shale; local aquifers within the Pierre Shale are 

referred to as the Pierre aquifer in this report. Within 

the Graneros Group, the Newcastle Sandstone contains 

an important minor aquifer. Because water-quality 

characteristics are very different between the Newcastle aquifer and the other units within the Graneros 

Group, water-quality data are presented for the 

Newcastle aquifer separately from the other units 

within the Graneros Group, known as the Graneros 

aquifer in this report. 

Gravel deposits of Tertiary age and unconsolidated units of Quaternary age, including alluvium, 

colluvium, gravel deposits, and wind-blown deposits, 

all have the potential to provide water where these units 

are saturated. In this report, these units are collectively 

referred to as alluvial aquifers.

Previous Investigations

Numerous reports from previous investigations 

contain information on the water quality of ground and 

surface water in the Black Hills area. The investigations described in this section are not exhaustive, but 

rather are those that either provide regional waterquality information or were done as part of the Black 

Hills Hydrology Study.

Various investigations have addressed the 

quality of ground water in the Black Hills area. Waterquality data collected from the Inyan Kara aquifer in 

the southern Black Hills were presented by Gott and 

others (1974). Radium concentrations collected from 

wells completed in the Madison aquifer in western 

South Dakota were presented by Carda (1975). 

Numerous water-quality data were collected in western 

South Dakota during the National Uranium Resource 

Evaluation (NURE) Program established by the U.S. 

Department of Energy. Some of the NURE data collected in the Black Hills area were presented by Union 

Carbide Corporation (1979, 1980). Water-quality data 

collected from the Madison aquifer in Montana, South 

Dakota, and Wyoming were presented in Busby and 

others (1983). The quality of ground water in western 

South Dakota was summarized for 17 aquifers by 

Meyer (1984), and ground-water pollution problems 

were summarized in Meyer (1986). Summaries of 

water-quality samples collected from the Inyan Kara, 

Minnelusa, and Madison aquifers were presented by 

Peter (1985) for the Rapid City area and by Kyllonen 

and Peter (1987) for the northern Black Hills of South 

Dakota and Wyoming. Water-quality data with 

emphasis on selenium in the Inyan Kara aquifer in the 

Black Hills were presented by Behal (1988). Waterquality data with emphasis on radionuclides for the 

Deadwood aquifer in the Black Hills were presented by 

Rounds (1991). Major ion and isotope data for the 

Madison aquifer in Montana, South Dakota, and 

Wyoming were presented by Busby and others (1991).

Many investigations on the quality of surface 

water have been conducted. The general water quality 

of streams within South Dakota has been reported 

every 2 years in 305(b) assessment reports prepared by 

the South Dakota Department of Environment and 

Natural Resources (1975-99). Water-quality data and 

results from the Rapid City National Urban Runoff 

Program were presented by Harms (1983), Harms and 

others (1983), and Goddard and others (1989). The 

water-quality effects of contaminated sediments on 

Whitewood Creek and the Belle Fourche and Cheyenne Rivers were addressed by Cherry and others 

(1986a, 1986b, 1986c), Goddard (1988, 1989a, 1989b, 

1990), and Fuller and others (1988, 1989). Waterquality data, including major ions, properties, trace 

elements, and pesticides, that were collected during 

1988 as part of irrigation drainage programs were presented by Greene and others (1990) for the Angostura 

Reclamation Unit and by Roddy and others (1991) for 

the Belle Fourche Reclamation Project. The water 

quality of streams in Custer State Park following the 

Galena Forest Fire was presented by Gundarlahalli 

(1990). Freeman and Komor (1991) presented a compilation of water-quality data along Rapid Creek for the 

period 1946-90, and Williamson and others (1996) presented data on selected trace elements in Rapid Creek. 

Additional summaries of sources of water-quality data 

in the Rapid Creek Basin were presented by Zogorski 

and others (1990). Information about arsenic loads and 

concentrations in Spearfish Creek were presented by 

Driscoll and Hayes (1995). Water-quality impacts on 

surface water from mining were presented by Rahn and 

others (1996).

Several reports contain water-quality data that 

were specifically collected as part of the Black Hills 

Hydrology Study. Water-quality data for selected 

wells, streams, and springs have been published by 

Driscoll and Bradford (1994), Driscoll and others 

(1996), and Driscoll, Bradford, and Moran (2000). 

Water-quality data for selected streams in Lawrence 
Sampling Sites and Methods 13

County were presented by Torve (1991), Williamson 

(1999), and Williamson and Hayes (2000). Nutrient, 

chloride, and bacteria data collected during 1988-90 for 

the Spearfish Creek Basin in Lawrence County were 

presented by Johnson (1992). Water-quality data from 

large-discharge springs and selected wells completed 

in the Madison and Minnelusa aquifers in the southern 

Black Hills were presented by Whalen (1994) and in 

northwestern Lawrence County by Klemp (1995). 

Water-quality data with emphasis on field properties of 

selected headwater springs in the Black Hills were 

presented by Wenker (1997). 

Acknowledgments

The authors acknowledge the efforts of the West 

Dakota Water Development District for helping to 

develop and support the Black Hills Hydrology Study. 

West Dakota’s coordination of various local and county 

cooperators has been a key element in making this 

study possible. The authors also recognize the 

numerous local and county cooperators represented by 

West Dakota, as well as the numerous private citizens 

who have helped provide guidance and support for the 

Black Hills Hydrology Study. The South Dakota 

Department of Environment and Natural Resources has 

provided support and extensive technical assistance to 

the study. In addition, the authors acknowledge the 

input and technical assistance from many faculty and 

students at the South Dakota School of Mines and 

Technology.

WATER-QUALITY CHARACTERISTICS

Data from the USGS National Water Information 

System (NWIS) water-quality database, QWDATA, 

were examined to characterize the water quality of 

aquifers, streams, and springs in the Black Hills area. 

QWDATA stores data primarily collected and analyzed 

by USGS. The data also are transferred to the U.S. 

Environmental Protection Agency (USEPA) waterquality database, STORET.

Data summarized in this report include samples 

collected from October 1, 1930, to September 30, 

1998. A selection criterion for including a sample as 

part of this analysis was to have a cation/anion balance 

within 10 percent. Tables of individual results are not 

presented in this report, only summaries. Site specific 

data can be requested from the USGS or USEPA. For 

some of the constituents summarized in this report, 

multiple laboratory reporting limits were used, 

resulting in censored values at various levels. If the 

majority of detectable levels were less than some of the 

censored values, those censored values were removed 

because they do not provide additional information for 

describing the data set. For the censored data, boxplots 

and summary statistics were estimated using a logprobability regression procedure (Helsel and Gilliom, 

1985). 

Sampling Sites and Methods

Ground-water and surface-water samples collected as part of studies along Whitewood Creek have 

been summarized in previous reports (Goddard, 1988, 

1989a; Fuller and Davis, 1989; Fuller and others, 1988, 

1989; Goddard and others, 1989) and are not included 

in this summary. In addition, samples from wastewater 

treatment plant effluents, some miscellaneous measurement sites, and samples from sites obviously 

affected by abandoned mines are not included. Sampling locations for ground water and surface water are 

presented in figures 6 and 7, respectively. The location 

of selected surface-water sites in the Rapid Creek Basin 

is presented in figure 7a. Lists of the ground-water and 

surface-water sampling sites are presented in tables 15 

and 16 in the Supplemental Information section at the 

end of the report.

For the majority of the samples collected prior to 

the Black Hills Hydrology Study and for all samples 

collected during the study, all water-sampling equipment was presoaked in a Liquinox solution, thoroughly 

scrubbed, rinsed with tap water, and then rinsed with 

deionized water prior to sampling. Samples were 

collected using acceptable methods at the time; most 

methods are described by Hem (1985) and Ward and 

Harr (1990). Field measurements of streamflow, air 

and water temperature, pH, dissolved oxygen, and 

specific conductance usually were collected. When 

more than one site was sampled on a given day, equipment cleaning between sites consisted of a deionized 

water rinse and thoroughly rinsing with well or stream 

water. After samples were collected, filtered and preserved, if applicable, they were shipped to the USGS 

National Water Quality Laboratory (NWQL) for 

analysis.
14 Water-Quality Characteristics in the Black Hills Area, South Dakota

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Inyan Kara

Minnekahta

Minnelusa

Madison

Deadwood

Precambrian

Alluvial

Graneros

Newcastle 

Pierre 

Morrison

Sundance

Spearfish

EXPLANATION

Figure 6. Location of ground-water sampling sites.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'

MAJOR AQUIFERS

MINOR AQUIFERS
Sampling Sites and Methods 15

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Headwater spring

Crystalline core

Artesian spring

Exterior

Other

Figure 7. Location of selected surface-water sampling sites by group.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

HYDROGEOLOGIC SETTINGS

SURFACE-WATER SAMPLING

 SITES BY GROUP

Limestone headwaters

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

Crystalline core

Loss zones and artesian

 springs--Outer extent

 approximates the outer

 extent of the Black Hills

 area

Exterior plains

104o 45' 103 EXPLANATION o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
16 Water-Quality Characteristics in the Black Hills Area, South Dakota T. 2N. T. 1NT. 1S. T. 2S. PENNINGTON COUNTY CUSTER COUNTY

LAWRENCE COUNTY

WYOMING

MEADE COUNTY

SOUTH DAKOTA

R. 2 E. R. 1 E. R. 3 E. R. 4 E. R. 5 E. R. 6 E. R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

104o

R. 12 E.

Ellsworth

Air Force Base

RAPID

CITY

Creston

Big Bend

Silver City

Rochford

Deerfield

Crooks

Tower

44o

15'

44o

103o30'

T.

3

N.

Caputa

Farmingdale

Rapid Creek

Deerfield Dam

and Reservoir

Pactola Dam

and Reservoir saC

lt e

Creek

Rhoads Fk

South

Fork

Vic ot ria C r

CHEYENNE

EVI R R

North

Fork

Rapid

Creek

Canyon Lake

06409000

06409000

06411500 06412500

06414000

06418900

06421500

06409000

06411500 06412500

06410500 06414000

06418900

06421500

0 10 200 10 20 KILOMETERS

MILES

EXPLANATION

RAPID CREEK BASIN BOUNDARYSURFACE-WATER SAMPLING SITE-- Number indicates site identificaiton

Figure 7a. Location of selected surface-water sampling sites in the Rapid Creek Basin.

Base modified from U.S. Geological Survey1:500,000 Hydrologic Unit Map, 1978

SOUTH DAKOTA

BlackHills

RapidCreekBasin

103o
Water-Quality Criteria 17

Water-Quality Criteria

Under the authority of the Safe Drinking Water 

Act in 1974, the USEPA established a public drinkingwater system program. The State of South Dakota 

received USEPA approval to administer their own 

drinking-water program in 1984. Under the Safe 

Drinking Water Act and the 1986 Amendments, both 

USEPA and the State of South Dakota set limits for 

contaminant levels in drinking water to ensure the 

safety of public drinking water. 

Maximum Contaminant Levels (MCL’s) are 

established for contaminants that, if present in drinking 

water, may cause adverse human health effects; MCL’s 

are enforceable health-based standards (U.S. Environmental Protection Agency, 1994a). Secondary Maximum Contaminant Levels (SMCL’s) are established 

for contaminants that can adversely affect the taste, 

odor, or appearance of water and may result in 

discontinuation of use of the water; SMCL’s are nonenforceable, generally non-health-based standards that 

are related to the aesthetics of water use (U.S. Environmental Protection Agency, 1994a). Action levels are 

concentrations that determine whether treatment 

requirements may be necessary (U.S. Environmental 

Protection Agency, 1997). Water-quality criteria, 

standards, or recommended limits and the general significance for the physical properties and constituents 

discussed in this report are presented in table 1.

Concentrations of constituents are compared to 

drinking-water standards set by the USEPA. Although 

USEPA standards apply only to public-water supplies, 

local residents using water from private wells for 

domestic purposes may want to be aware of the potential health risks associated with drinking water that 

exceeds drinking-water standards. Drinking-water 

standards established by the USEPA are based on total 

constituent concentrations, which refer to the combined concentrations of both dissolved and suspended 

phases of the water sample. Results reported by the 

USGS as dissolved constituent concentrations may be 

less than those obtained for similar samples analyzed 

for total constituent concentrations.

In an effort to control water pollution, Congress 

passed the Federal Water Pollution Control Act (Public 

Law 92-500) in 1972. Congress amended the law in 

1977, changing the name to the Clean Water Act, which 

requires States to classify surface waters with regard to 

beneficial use and to establish water-quality criteria to 

meet those uses (South Dakota Department of Water 

and Natural Resources, 1987). The Clean Water Act 

also require States to review and revise these standards 

every 3 years. The current beneficial-use and aquaticlife criteria are presented in table 2.

The beneficial-use criteria are designed to protect and ensure that a stream can support the specified 

beneficial uses. All streams in South Dakota are classified for irrigation and wildlife propagation and stock 

watering. Additional beneficial uses are assigned to 

stream segments as applicable. Some of the more 

common beneficial uses for the Black Hills area 

include domestic water supply, fish life propagation 

waters, and immersion recreation waters. Specific 

stream segment beneficial uses can be found in 

“Surface Water Quality,” Administrative Rules of 

South Dakota 74:51 (1998). Aquatic-life criteria are 

estimates of the highest concentrations in surface water 

that aquatic life can be exposed to without a resulting 

unacceptable or harmful effect. The chronic criteria is 

based on a concentration that the aquatic life can be 

exposed to for an indefinite period without an 

unacceptable or harmful effect. The acute criteria is 

based on a concentration that the aquatic life can be 

exposed to for very short periods without an unacceptable or harmful effect. The aquatic criteria for several 

trace elements vary with stream hardness (fig. 8). 

Generally, as stream hardness increases, the toxicity of 

the trace element decreases.
18 Water-Quality Characteristics in the Black Hills Area, South Dakota

Table 1. Water-quality criteria, standards, or recommended limits and general significance for selected properties

or constituents

[Modified from Hamilton and Howells, 1996. All standards are from U.S. Environmental Protection Agency (1994a) unless noted. MCL, Maximum 

Contaminant Level; SMCL, Secondary Maximum Contaminant Level; USEPA, U.S. Environmental Protection Agency; mL, milliliters; mg/L, milligrams 

per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micrograms per liter; pCi/L, picocuries per liter; --, no limit established]

Constituent

or property Limit Significance

Specific conductance -- A measure of the ability of water to conduct an electrical current; varies with temperature. 

Magnitude depends on concentration, kind, and degree of ionization of dissolved 

constituents; can be used to determine the approximate concentration of dissolved solids. 

Values are reported in microsiemens per centimeter at 25°Celsius.

pH 6.5-8.5 units

SMCL

A measure of the hydrogen ion concentration; pH of 7.0 indicates a neutral solution, pH 

values smaller than 7.0 indicate acidity, pH values larger than 7.0 indicate alkalinity. 

Water generally becomes more corrosive with decreasing pH; however, excessively 

alkaline water also may be corrosive.

Temperature -- Affects the usefulness of water for many purposes. Generally, users prefer water of 

uniformly low temperature. Temperature of ground water tends to increase with 

increasing depth to the aquifer.

Dissolved oxygen -- Required by higher forms of aquatic life for survival. Measurements of dissolved oxygen 

are used widely in evaluations of the biochemistry of streams and lakes. Oxygen is 

supplied to ground water through recharge and by movement of air through unsaturated 

material above the water table (Hem, 1989).

Carbon dioxide -- Important in reactions that control the pH of natural waters. 

Hardness and 

noncarbonate 

hardness (as mg/L 

CaCO3)

-- Related to the soap-consuming characteristics of water; results in formation of scum when 

soap is added. May cause deposition of scale in boilers, water heaters, and pipes. 

Hardness contributed by calcium and magnesium, bicarbonate and carbonate mineral 

species in water is called carbonate hardness; hardness in excess of this concentration is 

called noncarbonate hardness. Water that has a hardness less than 61 mg/L is considered 

soft; 61-120 mg/L, moderately hard; 121-180 mg/L, hard; and more than 180 mg/L, very 

hard (Heath, 1983).

Alkalinity -- A measure of the capacity of unfiltered water to neutralize acid. In almost all natural waters 

alkalinity is produced by the dissolved carbon dioxide species, bicarbonate and 

carbonate. Typically expressed as mg/L CaCO3.

Dissolved solids 500 mg/L

SMCL

The total of all dissolved mineral constituents, usually expressed in milligrams per liter. 

The concentration of dissolved solids may affect the taste of water. Water that contains 

more than 1,000 mg/L is unsuitable for many industrial uses. Some dissolved mineral 

matter is desirable, otherwise the water would have no taste. The dissolved solids 

concentration commonly is called the water’s salinity and is classified as follows: fresh, 

0-1,000 mg/L; slightly saline, 1,000-3,000 mg/L; moderately saline, 3,000-10,000 mg/L; 

very saline, 10,000-35,000 mg/L; and briny, more than 35,000 mg/L (Heath, 1983).

Calcium plus 

magnesium

-- Cause most of the hardness and scale-forming properties of water (see hardness).

Sodium plus potassium -- Large concentrations may limit use of water for irrigation and industrial use and, in 

combination with chloride, give water a salty taste. Abnormally large concentrations 

may indicate natural brines, industrial brines, or sewage.

Sodium-adsorption ratio 

(SAR)

A ratio used to express the relative activity of sodium ions in exchange reactions with soil. 

Important in irrigation water; the greater the SAR, the less suitable the water for 

irrigation.

Bicarbonate -- In combination with calcium and magnesium forms carbonate hardness.

Sulfate 250 mg/L

SMCL

Sulfates of calcium and magnesium form hard scale. Large concentrations of sulfate have a 

laxative effect on some people and, in combination with other ions, give water a bitter 

taste.

Chloride 250 mg/L

SMCL

Large concentrations increase the corrosiveness of water and, in combination with sodium, 

give water a salty taste.
Water-Quality Criteria 19

Fluoride 4.0 mg/L

MCL

2.0 mg/L

SMCL

Reduces incidence of tooth decay when optimum fluoride concentrations present in water 

consumed by children during the period of tooth calcification. Potential health effects of 

long-term exposure to elevated fluoride concentrations include dental and skeletal 

fluorosis (U.S. Environmental Protection Agency, 1994b).

Bromide -- Not known to be essential in human or animal diet. Not known to have any ecologic 

significance when it occurs in small concentrations typically found in fresh waters of the 

United States.

Iodide -- Essential and beneficial element in metabolism; deficiency can cause goiter.

Silica (as SiO2) -- Forms hard scale in pipes and boilers and may form deposits on blades of steam turbines. 

Inhibits deterioration of zeolite-type water softeners.

Nitrite (mg/L as N) 1.0 mg/L

MCL

Commonly formed as an intermediate product in bacterially mediated nitrification and 

denitrification of ammonia and other organic nitrogen compounds. An acute health 

concern at certain levels of exposure. Nitrite typically occurs in water from fertilizers 

and is found in sewage and wastes from humans and farm animals. Concentrations 

greater than 1.0 mg/L, as nitrogen, may be injurious when used in feeding infants.

Nitrite plus nitrate 

(mg/L as N)

10 mg/L

MCL

Concentrations greater than local background levels may indicate pollution by feedlot 

runoff, sewage, or fertilizers. Concentrations greater than 10 mg/L, as nitrogen, may be 

injurious when used in feeding infants.

Ammonia -- Plant nutrient that can cause unwanted algal blooms and excessive plant growth when 

present at elevated levels in water bodies. Sources include decomposition of animal and 

plant proteins, agricultural and urban runoff, and effluent from waste-water treatment 

plants.

Ammonia plus organic -- Organic species are unstable in aerated water and generally are considered to be indicators 

of pollution through disposal of sewage or organic waste (Hem, 1989). Nitrogen in 

reduced (ammonia) or organic forms is converted by soil bacteria into nitrite and nitrate 

(nitrification). See also ammonia.

Phosphorus, 

orthophosphate

-- Dense agal blooms or rapid plant growth can occur in waters rich in phosphorus. A limiting 

nutrient for eutrophication since it is typically in shortest supply. Sources are human and 

animal wastes and fertilizers.

Aluminum 50-200 μg/L

SMCL

No known necessary role in human or animal diet. Nontoxic in the concentrations normally 

found in natural water supplies. Elevated dissolved aluminum concentrations in some low 

pH waters can be toxic to some types of fish (Hem, 1989).

Arsenic 1

50 μg/L

MCL

No known necessary role in human or animal diet, but is toxic. A cumulative poison that is 

slowly excreted. Can cause nasal ulcers; damage to the kidneys, liver, and intestinal 

walls; and death. Recently suspected to be a carcinogen (Garold Carlson, U.S. 

Environmental Protection Agency, written commun., 1998).

Barium 2,000 μg/L

MCL

Toxic; used in rat poison. In moderate to large concentrations can cause death; smaller 

concentrations cause damage to the heart, blood vessels, and nerves.

Boron -- Essential to plant growth, but may be toxic to crops when present in excessive 

concentrations in irrigation water. Sensitive plants show damage when irrigation water 

contains more than 670 μg/L and even tolerant plants may be damaged when boron 

exceeds 2,000 μg/L. The recommended limit is 750 μg/L for long-term irrigation on 

sensitive crops (U.S. Environmental Protection Agency, 1986).

Cadmium 5 μg/L

MCL

A cumulative poison; very toxic. Not known to be either biologically essential or 

beneficial. Believed to promote renal arterial hypertension. Elevated concentrations may 

cause liver and kidney damage, or even anemia, retarded growth, and death.

Chromium 100 μg/L

MCL

No known necessary role in human or animal diet. In the hexavalent form is toxic, leading 

to intestinal damage and to nephritis.

Table 1. Water-quality criteria, standards, or recommended limits and general significance for selected properties

or constituents—Continued

[Modified from Hamilton and Howells, 1996. All standards are from U.S. Environmental Protection Agency (1994a) unless noted. MCL, Maximum 

Contaminant Level; SMCL, Secondary Maximum Contaminant Level; USEPA, U.S. Environmental Protection Agency; mL, milliliters; mg/L, milligrams 

per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micrograms per liter; pCi/L, picocuries per liter; --, no limit established]

Constituent

or property Limit Significance
20 Water-Quality Characteristics in the Black Hills Area, South Dakota

Cobalt -- Importance to human nutrition is not known but the element is essential in plant and animal 

nutrition. Concentrations of cobalt in the Earth’s crust are generally very low. 

Uncontaminated natural water should generally contain no more than a few micrograms 

per liter of cobalt (Hem, 1989, p. 139).

Copper 1,300 μg/L

(action level)

Essential to metabolism; copper deficiency in infants and young animals results in 

nutritional anemia. Large concentrations of copper are toxic and may cause liver 

damage. Moderate levels of copper (near the action level) can cause gastro-intestinal 

distress. If more than 10% of samples at the tap of a public water system exceed 

1,300 μg/L, the USEPA requires treatment to control corrosion of plumbing materials in 

the system.

Iron 300 μg/L

SMCL

Forms rust-colored sediment; stains laundry, utensils, and fixtures reddish brown. 

Objectionable for food and beverage processing. Can promote growth of certain kinds of 

bacteria that clog pipes and well openings.

Lead 15 μg/L

(action level)

A cumulative poison, toxic in small concentrations. Can cause lethargy, loss of appetite, 

constipation, anemia, abdominal pain, gradual paralysis in the muscles, and death. If 1 in 

10 samples of a public supply exceed 15 μg/L, the USEPA recommends treatment to 

remove lead and monitoring of the water supply for lead content (U.S. Environmental 

Protection Agency, 1991).

Lithium -- Reported as probably beneficial in small concentrations (250-1,250 μg/L). Reportedly may 

help strengthen the cell wall and improve resistance to genetic damage and to disease. 

Lithium salts are used to treat certain types of psychosis.

Manganese 50 μg/L

SMCL

Causes gray or black stains on porcelain, enamel, and fabrics. Can promote growth of 

certain kinds of bacteria that clog pipes and wells.

Mercury

(inorganic)

2 μg/L

MCL

No known essential or beneficial role in human or animal nutrition. Liquid metallic 

mercury and elemental mercury dissolved in water are comparatively nontoxic, but some 

mercury compounds, such as mercuric chloride and alkyl mercury, are very toxic. 

Elemental mercury is readily alkylated, particularly to methyl mercury, and concentrated 

by biological activity. Potential health effects of exposure to some mercury compounds 

in water include severe kidney and nervous system disorders (U.S. Environmental 

Protection Agency, 1994b).

Molybdenum -- In minute concentrations, appears to be an essential nutrient for both plants and animals, but 

in large concentrations may be toxic.

Nickel -- Very toxic to some plants and animals. Toxicity for humans is believed to be very minimal.

Selenium 50 μg/L

MCL

Essential to human and animal nutrition in minute concentrations, but even a moderate 

excess may be harmful or potentially toxic if ingested for a long time (Callahan and 

others, 1979). Potential human health effects of exposure to elevated selenium 

concentrations include liver damage (U.S. Environmental Protection Agency, 1994b).

Silver 100 μg/L

SMCL

Causes permanent bluish darkening of the eyes and skin (argyria). Where found in water is 

almost always from pollution or by intentional addition. Silver salts are used in some 

countries to sterilize water supplies. Toxic in large concentrations.

Strontium -- Importance in human and animal nutrition is not known, but believed to be essential. 

Toxicity believed very minimal—no more than that of calcium.

Vanadium -- Not known to be essential to human or animal nutrition, but believed to be beneficial in 

trace concentrations. May be an essential trace element for all green plants. Large 

concentrations may be toxic.

Zinc 5,000 μg/L

SMCL

Essential and beneficial in metabolism; its deficiency in young children or animals will 

retard growth and may decrease general body resistance to disease. Seems to have no ill 

effects even in fairly large concentrations (20,000-40,000 mg/L), but can impart a 

metallic taste or milky appearance to water. Zinc in drinking water commonly is derived 

from galvanized coatings of piping.

Table 1. Water-quality criteria, standards, or recommended limits and general significance for selected properties

or constituents—Continued

[Modified from Hamilton and Howells, 1996. All standards are from U.S. Environmental Protection Agency (1994a) unless noted. MCL, Maximum 

Contaminant Level; SMCL, Secondary Maximum Contaminant Level; USEPA, U.S. Environmental Protection Agency; mL, milliliters; mg/L, milligrams 

per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micrograms per liter; pCi/L, picocuries per liter; --, no limit established]

Constituent

or property Limit Significance
Water-Quality Criteria 21

Gross alpha-particle 

activity

15 pCi/L

MCL

The measure of alpha-particle radiation present in a sample. A limit is placed on gross 

alpha-particle activity because it is impractical at the present time to identify all alphaparticle emitting radionuclides due to analytical costs. Gross alpha-particle activity is a 

radiological hazard. The 15 pCi/L standard also includes radium-226, a known 

carcinogen, but excludes any uranium or radon that may be present in the sample. 

Thorium-230 radiation contributes to gross alpha-particle activity.

Beta-particle and photon 

activity

(formerly manmade 

radionuclides)

4 millirem/yr

MCL

(under review)

The measure of beta-particle radiation present in a sample. Gross beta-particle activity is a 

radiological hazard. See strontium-90 and tritium.

Radium-226 & 228 

combined

5 pCi/L

MCL

Radium locates primarily in bone, however, inhalation or ingestion may result in lung 

cancer. Radium-226 is a highly radioactive alkaline-earth metal that omits alpha-particle 

radiation. It is the longest lived of the four naturally occurring isotopes of radium and is 

a disintegration product of uranium-238. Concentrations of radium in most natural 

waters are usually less than 1.0 pCi/L (Hem, 1989).

Radon2 300 or 4,000 

pCi/L

proposed MCL

Inhaled radon is known to cause lung cancer (MCL for radon in indoor air is 4 pCi/L). 

Injested radon also is believed to cause cancer. A radon concentration of 1,000 pCi/L in 

water is approximately equal to 1 pCi/L in air. The ultimate source of radon is the 

radioactive decay of uranium. Radon-222 has a half life of 3.8 days and is the only radon 

isotope of importance in the environment (Hem, 1989).

Strontium-90

(contributes to betaparticle and photon 

activity)

Gross betaparticle activity

(4 millirem/yr)

MCL

Strontium-90 is one of 12 unstable isotopes of strontium known to exist. It is a product of 

nuclear fallout and is known to cause adverse human health affects. Strontium-90 is a 

bone seeker and a relatively long-lived beta emitter with a half-life of 28 years. The 

USEPA has calculated that an average annual concentration of 8 pCi/L will produce a 

total body or organ dose of 4 millirem/yr (U.S. Environmental Protection Agency, 1997).

Thorium-230

(contributes to gross 

alpha-particle 

activity)

15 pCi/L

MCL

Thorium-230 is a product of natural radioactive decay when uranium-234 emits alphaparticle radiation. Thorium-230 also is a radiological hazard because it is part of the 

uranium-238 decay series and emits alpha-particle radiation through its own natural 

decay to become radium-226. The half-life of thorium-230 is about 80,000 years.

Tritium (3

H)

(contributes to betaparticle and photon 

activity)

Gross betaparticle activity

(4 millirem/yr)

MCL

Tritium occurs naturally in small amounts in the atmosphere, but largely is the product of 

nuclear weapons testing. Tritium can be incorporated into water molecules that reach the 

Earth’s surface as precipitation. Tritium emits low energy beta particles and is relatively 

short-lived with a half-life of about 12.3 years. The USEPA has calculated that a 

concentration of 20,000 pCi/L will produce a total body or organ dose of 4 millirem/yr 

(CFR 40 Subpart B 141.16, revised July 1997, p. 296).

Uranium3 30 μg/L

MCL

(under review)

Uranium is a chemical and a radiological hazard and carcinogen. It omits alpha-particle 

radiation through natural decay. It is a hard, heavy, malleable metal that can be present in 

several oxidation states. Generally, the more oxidized states are more soluble. Uranium238 and uranium-235, which occur naturally, account for most of the radioactivity in 

water. Uranium concentrations range between 0.1 and 10 μg/L in most natural waters.

1Whereas the drinking water MCL currently remains at 50 μg/L, USEPA is currently reviewing a proposed standard of 10 μg/L (U.S. Environmental 

Protection Agency, 2000a). 2

USEPA currently is working to set an MCL for radon in water. The proposed standards are 4,000 pCi/L for States that have an active indoor air 

program and 300 pCi/L for States that do not have an active indoor air program (Garold Carlson, U.S. Environmental Protection Agency, oral commun., 

1999). At this time, it is not known whether South Dakota will participate in an active indoor air program (Darron Busch, South Dakota Department of 

Environment and Natural Resources, oral commun., 1999). 3Although USEPA has finalized the MCL of 30 μg/L for uranium, this regulation does not take effect until December 8, 2003 (U.S. Environmental 

Protection Agency, 2000b).

Table 1. Water-quality criteria, standards, or recommended limits and general significance for selected properties

or constituents—Continued

[Modified from Hamilton and Howells, 1996. All standards are from U.S. Environmental Protection Agency (1994a) unless noted. MCL, Maximum 

Contaminant Level; SMCL, Secondary Maximum Contaminant Level; USEPA, U.S. Environmental Protection Agency; mL, milliliters; mg/L, milligrams 

per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micrograms per liter; pCi/L, picocuries per liter; --, no limit established]

Constituent

or property Limit Significance
22 Water-Quality Characteristics in the Black Hills Area, South Dakota Table 2. Surface-water-quality standards for selected physical properties and constituents [All constituents in milligrams per liter unless otherwise noted. μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micrograms per liter; mL, milliliters; oF, degrees Fahrenheit; oC, degrees Celsius; >, greater than or equal to; --, no data available] Property or constituent Beneficial-use criteria1 Aquatic-life criteria for fisheries1 (acute/ chronic)

(μg/L)

Domestic 

water supply

(mean/daily 

maximum)

Coldwater

permanent

fisheries

Coldwater

marginal

fisheries

Warmwater

permanent

fisheries

Warmwater

semipermanent

fisheries

Warmwater

marginal 

fisheries

Immersion

waters

Limitedcontact

waters

Wildlife

propagation

and stockwatering

waters

Irrigation

waters

Specific conductance 

(μS/cm)

-- -- -- -- -- -- -- -- 4,000/27,000 2,500/24,375 --

pH (standard units) 6.5-9.0 6.6-8.6 6.5-8.8 6.5-9 6.5-9 6.5-9 -- -- 6.0-9.5 -- --Temperature (oF)

(maximum)

-- 65 (18.3oC) 75 (24oC) 80 (27oC) 90 (32oC) 90 (32oC) -- -- -- -- --

Dissolved oxygen -- >6.0

>7 during 

spawning

>5.0 >5.0 >5.0 >4.0 >5.0 >5.0 -- -- --

Total alkalinity as 

(CaCO3)

-- -- -- -- -- -- -- -- 750/21,313 -- --

Total dissolved solids 1,000/21,750 -- -- -- -- -- -- -- 2,500/24,375 -- --

Total suspended solids -- 30/253 90/2158 90/2158 90/2158 150/2263 -- -- -- -- --

Sodium-adsorption ratio -- -- -- -- -- -- -- -- -- 10 --Chloride 250/2438 100/2175 -- -- -- -- -- -- -- -- --

Fluoride 4.0 -- -- -- -- -- -- -- -- -- --Sulfate 500/2875 -- -- -- -- -- -- -- -- -- --

Nitrate (as N) 10 -- -- -- -- -- -- -- 50/288 -- --

Un-ionized ammonia

(as N)

-- 0.02 0.02 0.04 0.04 0.04 -- -- -- -- --

Cyanide (free) -- -- -- -- -- -- -- -- -- -- 22/5.2Dissolved antimony 30.014 44.3 44.3 44.3 44.3 44.3 -- -- -- -- --

Dissolved arsenic 30.000018 40.00014 40.00014 40.00014 40.00014 40.00014 -- -- -- -- 360/190 

(340/5150)
Water-Quality Criteria 23

Dissolved barium 1.0 -- -- -- -- -- -- -- -- -- --Dissolved cadmium -- -- -- -- -- -- -- -- -- -- 63.7/61.0

(4.3/52.2)

Dissolved copper 31.3 -- -- -- -- -- -- -- -- -- 617/611

(13/59)

Dissolved lead -- -- -- -- -- -- -- -- -- -- 665/62.5

Dissolved mercury 30.00014 40.00015 40.00015 40.00015 40.00015 40.00015 -- -- -- -- 2.1/70.012

(1.4/50.77)

Dissolved selenium -- -- -- -- -- -- -- -- -- -- 20/5

(--/55)

Dissolved silver -- -- -- -- -- -- -- -- -- -- 63.4/--

Dissolved zinc 30.0017 -- -- -- -- -- --- -- -- -- 6110/6100

(120/5120)

1South Dakota Department of Environment and Natural Resources, 1998a, unless indicated otherwise.230-day average/daily maximum.3Based on two routes of exposure—ingestion of contaminated aquatic organisms and drinking water.4Based on one route of exposure—ingestion of contaminated aquatic organisms only.5U.S. Environmental Protection Agency, 1998.6Hardness-dependent criteria; value given is an example based on hardness of 100 milligrams per liter as CaCO3.7Chronic criteria based on total recoverable concentration.

Table 2. Surface-water-quality standards for selected physical properties and constituents—Continued[All constituents in milligrams per liter unless otherwise noted. μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micrograms per liter; mL, milliliters; oF, degrees Fahrenheit; oC, degrees 

Celsius; >, greater than or equal to; --, no data available]

Property or constituent

Beneficial-use criteria1 Aquatic-life

 criteria for

 fisheries1

 (acute/

chronic)

(μg/L)

Domestic 

water supply

(mean/daily 

maximum)

Coldwater

permanent

fisheries

Coldwater

marginal

fisheries

Warmwater

permanent

fisheries

Warmwater

semipermanent

fisheries

Warmwater

marginal 

fisheries

Immersion

waters

Limitedcontact

waters

Wildlife

propagation

and stockwatering

waters

Irrigation

waters
24 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 8. Relations between water hardness and freshwater aquatic-life standards for acute and chronic toxicity

of selected trace elements (South Dakota Department of Environment and Natural Resources, 1998a).

1

10,000

2

3

4

5

7

10

20

30

40

50

70

100

200

300

400

500

700

1,000

2,000

3,000

4,000

5,000

7,000

DISSOLVED TRACE-ELEMENT CONCENTRATION, IN MICROGRAMS PER LITER

100 200 300 400 500 600 700 800 900 1,000 1,100 1,200

HARDNESS, IN MILLIGRAMS PER LITER

1

10,000

2

3

4

5

7

10

20

30

40

50

70

100

200

300

400

500

700

1,000

2,000

3,000

4,000

5,000

7,000

EXPLANATION

CADMIUM

COPPER

LEAD

SILVER

NICKEL

ZINC

Acute criterion

Chronic criterion
Water-Quality Characteristics of Selected Aquifers 25

Water-Quality Characteristics of Selected 

Aquifers

Water-quality characteristics are described for 

selected aquifers within the study area. Summaries are 

provided for various physical properties and constituents, which are grouped by common ions, nutrients, 

trace elements, and radionuclides. The effect that 

water-quality characteristics have on water use for 

selected aquifers in the study area is summarized at the 

end of this section.

The major aquifers are those that regionally are 

used for water supply and include the Precambrian, 

Deadwood, Madison, Minnelusa, Minnekahta, and 

Inyan Kara aquifers. Minor aquifers include formations that typically are not considered aquifers, but may 

be used locally to supply water; these include the 

Spearfish, Sundance, Morrison, Pierre Shale, 

Graneros, and Newcastle aquifers. Numerous wells are 

completed in alluvial deposits in the Black Hills area, 

but these aquifers are considered minor because they 

are not regionally extensive. Water-quality characteristics are presented for aquifers for which at least eight 

samples were available in the USGS NWIS waterquality database. Multiple samples were collected 

from some ground-water sites; all sites and the number 

of valid samples considered are presented in table 15 in 

the Supplemental Information section.

Comparisons were made for selected aquifers 

between well depth and variations of selected properties and constituents to provide a general description of 

how properties and constituents vary with increasing 

distance from the outcrop. Linear and logarithmic 

regressions were performed on all properties and constituents with at least eight valid measurements. If the 

associated R2

 value, which is the fraction of variability 

in the dependent variable that is explained by the 

regression equation, was greater than 0.1 and the 

associated p-value, which is based on the ratio of the 

explained variance to the unexplained variance, was 

less than 0.1, the regression was considered statistically 

significant. Plots of the properties or constituents 

versus well depth are presented for all significant 

regressions. Sometimes higher R2 values were 

obtained by using the logarithmic value for a particular 

property or constituent. In these cases, the plot presented contains the logarithmic values of the property 

or constituent versus well depth. 

Because the bedrock formations dip away

from the core of the Black Hills, the depth to these 

formations increases with increasing distance from the 

outcrop. Therefore, well depth can be used as an indication of distance from the outcrop for four of the 

aquifers (Deadwood, Madison, Minnelusa, and Inyan 

Kara aquifers). Well depth is easily quantifiable (as 

compared to distance from the outcrop) and is available 

for almost every well sampled. The well depths for 

samples collected from these aquifers vary from less 

than 50 feet to greater than 1,500 feet. For the Precambrian, Minnekahta, and all minor aquifers considered, 

wells generally are located either on or very near the 

outcrop and, therefore, well depth is relatively 

constant; water-quality variations with well depth for 

these aquifers were not determined.

Water quality in individual aquifers may be 

affected by leakage from other aquifers and by surface 

contamination in poorly constructed wells. Also, some 

samples may be incorrectly included with summaries 

of a specific aquifer due to difficulties in identifying the 

source aquifer for some wells in areas of complex 

hydrogeologic conditions.

Physical Properties

The physical properties measured for samples 

include specific conductance, pH, temperature, dissolved oxygen, carbon dioxide, hardness, noncarbonate hardness, and alkalinity. Summary statistics are 

presented in table 3, and boxplots are presented in 

figure 9 for each of these properties.

Relations between various properties and well 

depth are shown in figure 10. Water temperature 

generally increases with increasing well depth due to 

increases in ground temperature with depth, as shown 

for the Madison, Minnelusa, and Inyan Kara aquifers 

(fig. 10). Minimum water temperatures for all the 

aquifers are similar (fig. 9). Water from the Precambrian aquifers has the lowest mean and median temperature of the major aquifers, which is expected due to 

generally shallow well depths in the Precambrian 

aquifers. The highest water temperatures are from 

samples from the Madison and Minnelusa aquifers, 

which have the deepest wells in the study area (fig. 10). 

In the Madison aquifer, the water temperature of 

samples collected from wells located on or near the 

outcrop is less than 20°C (fig. 11), with some samples 

less than 10°C; the warmest water sampled (greater 

than 50°C) was from wells located near Edgemont. 
26 Water-Quality Characteristics in the Black Hills Area, South Dakota

Table 3. Summary of physical properties in ground water

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter is approximately equal to one part per million; μS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees 

Celsius; --, not analyzed or not determined]

Property or dissolved constituent Number of

samples Mean Median Minimum Maximum

Precambrian aquifers

Specific conductance (μS/cm) 92 387 350 73 1,130

pH (standard units) 110 6.8 7.1 5.4 8.3

Temperature (°C) 64 11 10 5.0 23

Dissolved oxygen 51 5.5 5.7 1.0 14

Carbon dioxide 110 39 18 1.0 571

Hardness, as CaCO3 112 172 175 22 480

Noncarbonate hardness 13 65 9.0 0 342

Alkalinity 87 144 144 20 349

Deadwood aquifer

Specific conductance (μS/cm) 37 460 453 83 831

pH (standard units) 36 7.5 7.7 6.8 8.4

Temperature (°C) 32 13 12 7.5 31

Dissolved oxygen 25 4.2 3.5 0.2 11

Carbon dioxide 35 12 8.4 1.2 45

Hardness, as CaCO3 37 210 210 37 460

Noncarbonate hardness 3 6.7 0 0 20

Alkalinity 34 225 207 129 409

Madison aquifer

Specific conductance (μS/cm) 110 632 460 290 3,360

pH (standard units) 126 7.4 7.6 6.1 8.5

Temperature (°C) 74 19 15 7.0 63

Dissolved oxygen 39 5.9 7.0 0 11

Carbon dioxide 124 17 9.9 1.1 558

Hardness, as CaCO3 127 284 250 22 1,600

Noncarbonate hardness 18 114 95 0 460

Alkalinity 82 203 181 136 363

Minnelusa aquifer

Specific conductance (μS/cm) 196 783 490 208 3,300

pH (standard units) 237 7.4 7.6 6.1 8.6

Temperature (°C) 106 16 14 7.7 53

Dissolved oxygen 53 5.3 5.7 0 15

Carbon dioxide 234 16 10 1.1 341

Hardness, as CaCO3 249 453 270 8.0 2,200

Noncarbonate hardness 44 497 287 0 1,810

Alkalinity 138 206 205 108 400

Minnekahta aquifer

Specific conductance (μS/cm) 26 640 550 270 2,330

pH (standard units) 27 7.4 7.5 6.9 8.3

Temperature (°C) 8 13 12 8.2 31

Dissolved oxygen 3 4.7 4.2 2.6 7.2
Water-Quality Characteristics of Selected Aquifers 27

Minnekahta aquifer—Continued

Carbon dioxide 27 18 17 3.2 62

Hardness, as CaCO3 28 398 310 190 1,500

Noncarbonate hardness 3 554 297 265 1,100

Alkalinity 20 253 250 180 338

Inyan Kara aquifer

Specific conductance (μS/cm) 150 1,242 1,060 297 4,350

pH (standard units) 175 7.3 7.5 6.2 9.5

Temperature (°C) 107 15 14 1.4 33

Dissolved oxygen 68 4.0 3.2 0 10

Carbon dioxide 174 20 12 0.1 253

Hardness, as CaCO3 176 377 280 6.0 2,000

Noncarbonate hardness 34 185 105 0 990

Alkalinity 117 213 204 30 551

Spearfish aquifer

Specific conductance (μS/cm) 13 1,384 610 260 5,725

pH (standard units) 12 7.1 7.4 6.3 8.0

Temperature (°C) 10 11 12 4.4 18

Dissolved oxygen 9 6.9 5.0 2.4 17

Carbon dioxide 12 30 17 1.4 195

Hardness, as CaCO3 13 727 360 130 2,100

Noncarbonate hardness 0 -- -- -- --

Alkalinity 12 199 199 78 282

Sundance aquifer

Specific conductance (μS/cm) 12 1,857 2,045 700 3,160

pH (standard units) 14 7.0 7.2 6.5 8.1

Temperature (°C) 12 14 13 9.0 20

Dissolved oxygen 4 2.9 1.1 0 9.5

Carbon dioxide 14 43 29 3.6 153

Hardness, as CaCO3 14 737 740 190 1,800

Noncarbonate hardness 8 424 450 20 773

Alkalinity 12 229 215 150 341

Morrison aquifer

Specific conductance (μS/cm) 13 1,345 821 432 4,910

pH (standard units) 15 7.2 7.7 6.3 8.0

Temperature (°C) 10 20 17 10 33

Dissolved oxygen 6 7.7 7.8 2.0 12

Carbon dioxide 15 25 6.8 3.3 233

Hardness, as CaCO3 15 576 270 11 2,200

Noncarbonate hardness 5 114 170 0 202

Alkalinity 10 192 189 130 268

Table 3. Summary of physical properties in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter is approximately equal to one part per million; μS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees 

Celsius; --, not analyzed or not determined]

Property or dissolved constituent Number of

samples Mean Median Minimum Maximum
28 Water-Quality Characteristics in the Black Hills Area, South Dakota

Pierre aquifer

Specific conductance (μS/cm) 28 2,082 1,840 300 6,090

pH (standard units) 28 7.3 7.4 6.6 7.9

Temperature (°C) 28 11 11 7.9 18

Dissolved oxygen 28 5.2 4.0 1.3 12

Carbon dioxide 28 32 22 6.9 142

Hardness, as CaCO3 28 772 560 160 2,800

Noncarbonate hardness 0 -- -- -- --

Alkalinity 28 292 291 170 740

Graneros aquifer

Specific conductance (μS/cm) 10 1,358 1,060 495 2,650

pH (standard units) 10 7.1 7.0 6.7 7.8

Temperature (°C) 10 13 12 9.7 19

Dissolved oxygen 10 4.4 3.6 1.3 8.2

Carbon dioxide 10 43 37 6.7 91

Hardness, as CaCO3 10 642 540 120 1,500

Noncarbonate hardness 0 -- -- -- --

Alkalinity 10 258 261 142 368

Newcastle aquifer

Specific conductance (μS/cm) 8 679 595 480 1,290

pH (standard units) 8 7.2 7.7 6.5 7.8

Temperature (°C) 5 14 11 10 23

Dissolved oxygen 0 -- -- -- --

Carbon dioxide 8 34 9.1 5.0 185

Hardness, as CaCO3 8 274 265 33 560

Noncarbonate hardness 4 28 6.5 0 98

Alkalinity 5 257 234 180 359

Alluvial aquifers

Specific conductance (μS/cm) 95 1,128 650 280 6,500

pH (standard units) 112 7.3 7.5 6.3 8.9

Temperature (°C) 49 14 13 7.7 30

Dissolved oxygen 29 6.4 6.0 2.0 12

Carbon dioxide 101 21 13 0.5 158

Hardness, as CaCO3 116 464 280 57 2,000

Noncarbonate hardness 9 367 220 16 760

Alkalinity 75 222 220 23 539

Table 3. Summary of physical properties in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter is approximately equal to one part per million; μS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees 

Celsius; --, not analyzed or not determined]

Property or dissolved constituent Number of

samples Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Aquifers 29

Figure 9. Boxplots of physical properties for selected aquifers.

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

8,000

0

2,000

4,000

6,000

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

92 37 110 196 26 150 13 12 13 28 10 8 95

10

5

6

7

8

9

pH, IN STANDARD UNITS

110 36 126 237 27 175 12 14 15 28 10 8 112

70

0

20

40

60

TEMPERATURE, IN DEGREES CELSIUS

64 32 74 106 8 107 10 12 10 28 10 5 49

Major aquifers Minor aquifers
30 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 9. Boxplots of physical properties for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

3,000

500

1,000

1,500

2,000

2,500

HARDNESS, IN MILLIGRAMS PER LITER

112 37 127 249 28 176 13 14 15 28 10 8 116

0

600

100

200

300

400

500

DISSOLVED CARBON DIOXIDE,

IN MILLIGRAMS PER LITER

110 35 124 234 27 174 12 14 15 28 10 8 101

0

20

5

10

15

DISSOLVED OXYGEN,

IN MILLIGRAMS PER LITER

51 25 39 53 3 68 9 4 6 28 10 0 29

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 31

Figure 9. Boxplots of physical properties for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

2,000

500

1,000

1,500

NONCARBONATE HARDNESS,

IN MILLIGRAMS PER LITER

13 3 18 44 3 34 0 8 5 0 0 4 9

0

800

200

400

600

ALKALINITY, IN MILLIGRAMS PER LITER

87 34 82 138 20 117 12 12 10 28 10 5 75

25th percentile

Single sample

Secondary Maximum Contaminant Level (recommended)

(U.S. Environmental Protection Agency, 1994a)

Median

75th percentile

Data value less than or equal to 1.5 times the interquartile

range outside the quartile

Outlier data value less than or equal to 3 and more than 1.5

times the interquartile range outside the quartile

Outlier data value more than 3 times the interquartile range

outside the quartile

EXPLANATION

12 Number of samples

Major aquifers Minor aquifers
32 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 10. Selected relations between physical properties and well depth for selected aquifers.

WELL DEPTH, IN FEET

DEADWOOD AQUIFER

6.6

8.6

6.8

7.0

7.2

7.4

7.6

7.8

8.0

8.2

8.4

pH, IN STANDARD UNITS

R2 = 0.1602

0

12

1

2

3

4

5

6

7

8

9

10

11

DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

R2 = 0.2327

0 200 400 600 800 1,000 1,200 1,400 1,600

WELL DEPTH, IN FEET

0 200 400 600 800 1,000 1,200 1,400 1,600 0

50

5

10

15

20

25

30

35

40

45

CARBON DIOXIDE, IN MILLIGRAMS PER LITER

R2 = 0.1329
Water-Quality Characteristics of Selected Aquifers 33

Figure 10. Selected relations between physical properties and well depth for selected aquifers.--Continued

WELL DEPTH, IN FEET

MADISON AQUIFER

WELL DEPTH, IN FEET

0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 100

10,000

150

200

250

300

400

500

600

700

800

900 1,000

1,500

2,000

2,500

3,000

4,000

5,000

6,000

7,000

8,000

9,000

SPECIFIC CONDUCTANCE, 

IN MICROSIEMENS PER CENTIMETER

R2 = 0.1851 R2 = 0.4607

5

65

10

15

20

25

30

35

40

45

50

55

60

TEMPERATURE, IN DEGREES CELSIUS

R2 = 0.6040

0

1,700

100

200

300

400

500

600

700

800

900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

HARDNESS, IN MILLIGRAMS PER LITER

R2 = 0.1918

0

480

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

320

340

360

380

400

420

440

460

NONCARBONATE HARDNESS,

IN MILLIGRAMS PER LITER
34 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 10. Selected relations between physical properties and well depth for selected aquifers.--Continued

WELL DEPTH, IN FEET

MINNELUSA AQUIFER

WELL DEPTH, IN FEET

TEMPERATURE, IN DEGREES CELSIUS HARDNESS, IN MILLIGRAMS PER LITER

NONCARBONATE HARDNESS,

IN MILLIGRAMS PER LITER

0 4,500 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

0 4,500 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 0

3,400

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

2,800

3,000

3,200

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

R2 = 0.2521

6

54

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

42

44

46

48

50

52 R2 = 0.5699

0

2,400

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200 R2 = 0.3066

0

2,000

200

400

600

800

1,000

1,200

1,400

1,600

1,800 R2 = 0.3792
Water-Quality Characteristics of Selected Aquifers 35

Figure 10. Selected relations between physical properties and well depth for selected aquifers.--Continued

WELL DEPTH, IN FEET

INYAN KARA AQUIFER

TEMPERATURE, IN DEGREES CELSIUS DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

CARBON DIOXIDE, IN MILLIGRAMS PER LITER HARDNESS, IN MILLIGRAMS PER LITER

0 2,800 0 200 400 600 800 1,0001,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

WELL DEPTH, IN FEET

0 2,800 0 200 400 600 800 1,0001,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

6.0

9.8

6.2

6.4

6.6

6.8

7.0

7.2

7.4

7.6

7.8

8.0

8.2

8.4

8.6

8.8

9.0

9.2

9.4

9.6

9.8

pH, IN STANDARD UNITS

R2 = 0.1634

0

34

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

R2 = 0.1668

0

11

1

2

3

4

5

6

7

8

9

10 R2 = 0.1291

0.01

1,000

0.02

0.03

0.04 0.05

0.07

0.1

0.2

0.3

0.4 0.5

0.7

1

2

3

4

5

7

10

20

30

4050

70

100

200

300

400 500

700

R2 = 0.1442

0

2,200

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000 R2 = 0.1421
36 Water-Quality Characteristics in the Black Hills Area, South Dakota

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

EXPLANATION

Less than 20

WATER TEMPERATURE, IN

 DEGREES CELSIUS

20 - 30

30 - 40

40 - 50

Higher than 50

Figure 11. Distribution of water temperature in the Madison aquifer.

WELL COMPLETED IN MADISON

 AQUIFER FOR WHICH THERE

 IS A WATER TEMPERATURE

 MEASUREMENT

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

MADISON LIMESTONE ABSENT

 (from Carter and Redden,

 1999d)

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
Water-Quality Characteristics of Selected Aquifers 37

Most pH values for the aquifers are within the 

range specified by the SMCL (6.5 to 8.5 standard 

units). In the Precambrian aquifers, 14 of 110 samples 

are below the lower limit specified by the SMCL, 

which indicates acidity. The lowest mean and median 

pH values are from samples from the Precambrian 

aquifers, which is indicative of a formation with few 

carbonate rocks. Samples from the Inyan Kara aquifer 

have the greatest variability in pH (fig. 9). The pH 

increases with increasing depth for both the Deadwood 

and Inyan Kara aquifers. In addition to samples from 

the Precambrian aquifers, a few samples from other 

aquifers also are outside the SMCL range for pH: 2 of 

126 samples from the Madison aquifer, 3 of 237 samples from the Minnelusa aquifer, 11 of 175 samples 

from the Inyan Kara aquifer, 1 of 12 samples from the 

Spearfish aquifer, 1 of 15 samples from the Morrison 

aquifer, and 2 of 112 samples from alluvial aquifers.

Specific conductance is related to dissolved 

solids concentrations as discussed in the following section. Specific conductance generally is low for the 

Precambrian, Deadwood, and Minnekahta aquifers. 

Dissolved constituents tend to increase with residence 

time as indicated by the increase in specific conductance with well depth in the Madison and Minnelusa 

aquifers (fig. 10). Ranges in specific conductance in 

the Madison and Minnelusa aquifers are similar, and 

the highest values generally are from wells located at 

distance from the outcrops as shown in figures 12 

and 13, respectively. Samples from the Inyan Kara 

aquifer have the highest mean and median specific conductance of the major aquifers. The distribution of 

specific conductance in the Inyan Kara aquifer is 

shown in figure 14. Generally, water from the Inyan 

Kara aquifer and from the minor aquifers (with the 

exception of the Newcastle aquifer) is higher in 

specific conductance than the other major aquifers due 

to larger amounts of shale within the formations. Water 

obtained from shales may contain rather high concentrations of dissolved solids (Hem, 1985) and, hence, 

high specific conductance. Generally, the specific conductance of alluvial aquifers increases with increasing 

distance from the core of the Black Hills as streams 

flow across formations with increasing amounts of 

shale.

Hardness contributed by calcium, magnesium, 

and bicarbonate and carbonate species is called 

carbonate hardness. Additional hardness in excess of 

this concentration, such as associated with sulfate, is 

called noncarbonate hardness. The definitions of 

varying degrees of hardness are listed in table 1. Like 

carbonate hardness, alkalinity results from dissolved 

bicarbonate and carbonate species. Thus, formations 

that contain few carbonate rocks generally contain 

water with lower carbonate hardness and alkalinity 

than formations that are composed primarily of carbonate rocks. Samples from the Precambrian aquifers 

have the lowest mean and median hardness and alkalinity of the aquifers, which again is indicative of a 

formation containing few carbonate rocks. 

Water from the Deadwood, Madison, Minnelusa, 

and Minnekahta aquifers generally is hard to very hard 

and is higher in alkalinity than the Precambrian 

aquifers. The source of carbonate hardness and alkalinity in these aquifers is the dissolution of limestone 

and dolomite. The dissolution of anhydrite in the 

Minnelusa Formation, and possibly in the Madison 

Limestone, contributes calcium sulfate and increases 

the noncarbonate hardness in these aquifers (Kyllonen 

and Peter, 1987). Samples from the Minnelusa aquifer 

have the highest mean hardness of the major aquifers; 

the softest water in the Minnelusa aquifer is from wells 

located on the inside of the sulfate transition zone, 

which is described in the following section. In the 

Madison and Minnelusa aquifers, hardness and noncarbonate hardness increase with increasing well depth 

(fig. 10). Samples from the Minnekahta aquifer have 

the highest median hardness and the highest mean and 

median concentrations of noncarbonate hardness and 

alkalinity of the major aquifers.

The hardness of water from the Inyan Kara 

aquifer ranges from soft to very hard. Hardness in the 

Inyan Kara aquifer decreases with increasing well 

depth, or distance from the outcrop (figs. 10 and 15). 

The softening of water downgradient is due to the 

precipitation of calcium and magnesium as water 

moves downgradient, which is described in the 

following section. Water from the minor aquifers 

generally is very hard.

Variability in dissolved oxygen and carbon 

dioxide concentrations generally is similar among the 

aquifers; however, in the Sundance aquifer, dissolved 

oxygen concentrations are notably lower and dissolved 

carbon dioxide concentrations notably higher than the 

other aquifers (fig. 9). Dissolved oxygen and carbon 

dioxide concentrations in samples from the Deadwood 

and Inyan Kara aquifers decrease with increasing well 

depth. Samples from alluvial aquifers indicate that 

dissolved oxygen concentrations generally decrease 

with increasing distance from the core of the Black 

Hills, which is due to low dissolved oxygen concentrations in streams in the exterior plains, as discussed in 

the surface-water section.
38 Water-Quality Characteristics in the Black Hills Area, South Dakota

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

EXPLANATION

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

MADISON LIMESTONE ABSENT

 (from Carter and Redden,

 1999d)

Figure 12. Distribution of specific conductance in the Madison aquifer.

Less than 500

500 - 1,000

1,000 - 1,500

Greater than 1,500

SPECIFIC CONDUCTANCE OF

 SAMPLES IN MICROSIEMENS

 PER CENTIMETER AT 25

 DEGREES CELSIUS--Circle

 size increases with increasing

 concentrations

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
Water-Quality Characteristics of Selected Aquifers 39

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Figure 13. Distribution of specific conductance in the Minnelusa aquifer.

EXPLANATION

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

MINNELUSA FORMATION

 ABSENT (from Carter and

 Redden, 1999c)

Less than 500

500 - 1,000

1,000 - 1,500

Greater than 1,500

SPECIFIC CONDUCTANCE OF

 SAMPLES IN MICROSIEMENS

 PER CENTIMETER AT 25

 DEGREES CELSIUS--Circle

 size increases with increasing

 concentrations

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
40 Water-Quality Characteristics in the Black Hills Area, South Dakota

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Figure 14. Distribution of specific conductance in the Inyan Kara aquifer.

EXPLANATION

OUTCROP OF INYAN KARA

 GROUP (from Strobel and

 others, 1999)

INYAN KARA GROUP ABSENT

 (from Carter and Redden,

 1999a)

Less than 500

500 - 1,000

1,000 - 1,500

Greater than 1,500

SPECIFIC CONDUCTANCE OF

 SAMPLES IN MICROSIEMENS

 PER CENTIMETER AT 25

 DEGREES CELSIUS--Circle

 size increases with increasing

 concentrations

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
Water-Quality Characteristics of Selected Aquifers 41

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

EXPLANATION

Very hard (greater that 180)

WATER HARDNESS, IN

 MILLIGRAMS PER LITER

Hard (121 - 180)

Moderately hard (61 - 121)

Soft (less than 61)

Figure 15. Distribution of hardness in the Inyan Kara aquifer.

WELL COMPLETED IN INYAN

 KARA AQUIFER FOR WHICH

 THERE IS A HARDNESS

 ANALYSIS

OUTCROP OF INYAN KARA

 GROUP (from Strobel and

 others, 1999)

INYAN KARA GROUP ABSENT

 (from Carter and Redden,

 1999a)

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
42 Water-Quality Characteristics in the Black Hills Area, South Dakota

Common Ions

Summary statistics for selected common ions, 

including dissolved solids, calcium, magnesium, 

sodium, percent sodium, sodium-adsorption ratio 

(SAR), potassium, bicarbonate, carbonate, sulfate, 

chloride, fluoride, bromide, iodide, and silica, are 

presented in table 4. The significance of the various 

common ions is described in table 1. Boxplots are presented in figure 16 for each of the common ions, except 

for carbonate. The water type for the various aquifers 

also is discussed in this section. Trilinear diagrams 

(fig. 17) are presented for each of the aquifers. 

Changes in water type as ground water flows downgradient are discussed for the Madison, Minnelusa, and 

Inyan Kara aquifers.

Specific conductance can be used to estimate the 

concentration of dissolved solids using the equations 

presented in table 5. Linear regression was performed 

using specific conductance and concentrations of dissolved solids (sum of constituents or residue) for each 

aquifer having sufficient measurements of both to 

indicate the strength of the relation between specific 

conductance and dissolved solids concentration.

The general suitability of water for irrigation 

from the aquifers in the study area can be determined 

by using the South Dakota irrigation-water diagram 

(fig. 18). The diagram is based on South Dakota 

irrigation-water standards (revised January 7, 1982) 

and shows the State’s water-quality and soil-texture 

requirements for the issuance of an irrigation permit. 

For each aquifer, the adjusted SAR, which is used to 

classify South Dakota irrigation waters, was calculated 

according to Koch (1983) from the mean concentrations of calcium, magnesium, sodium, and bicarbonate 

(or alkalinity from table 3) presented in table 4 for each 

aquifer. Based on mean concentrations, water from all 

aquifers, with the exceptions of the Pierre and 

Sundance aquifers, generally is suitable for irrigation, 

but may not be in specific instances if either the 

specific conductance or the SAR is high.

A strong relation exists between specific conductance and dissolved sulfate concentrations for 

samples from the Madison, Minnelusa, and Inyan Kara 

aquifers (fig. 19). Linear regression was performed 

using specific conductance and sulfate concentrations 

for each of these aquifers. Sulfate concentrations for 

these aquifers can be estimated using the equations 

presented in figure 19.

Precambrian Aquifers

Generally, water from the Precambrian aquifers 

is fresh (less than 1,000 mg/L dissolved solids concentration). Calcium and bicarbonate generally are 

dominant among the common ions. Water from the 

Precambrian aquifers has the highest median chloride 

concentration, lowest mean and median concentrations 

of calcium, magnesium, and bicarbonate, and the 

lowest median sulfate (equal to the Deadwood aquifer) 

of the major aquifers. 

The water type of the Precambrian aquifers 

generally is a calcium bicarbonate or a calcium magnesium bicarbonate type but also can be a mixed type 

(fig. 17). The original rock mineralogy, degree of 

metamorphism, and degree of weathering all can 

contribute to the variations in water type.

Two of 56 samples from Precambrian aquifers 

exceed the SMCL of 500 mg/L for dissolved solids. 

Two of 112 samples exceed the SMCL of 250 mg/L for 

sulfate; both were collected from the same well. Three 

of 55 samples exceed the SMCL of 2.0 mg/L for 

fluoride; all three samples were collected from the 

same well. None of the samples exceeded the MCL of 

4.0 mg/L for fluoride.

Deadwood Aquifer

Water from the Deadwood aquifer generally is 

fresh. Generally, calcium and bicarbonate are dominant among the common ions. Of samples collected 

from the major aquifers, the Deadwood aquifer has the 

lowest mean and median sulfate concentration (equal 

to the Precambrian aquifers). Variability in sulfate 

concentrations in the Deadwood aquifer is low.

The Deadwood aquifer generally has a calcium 

magnesium bicarbonate water type (fig. 17) in wells 

located on or near the outcrop. This water type results 

from the dissolution of calcite and dolomite. The 

downgradient water type is not known because no 

samples were collected from wells located more than 

5 miles from the outcrop of the Deadwood Formation. 

Samples collected from three wells located about 

3 miles from the outcrop have either a sodium bicarbonate or calcium sodium bicarbonate water type. 

Sodium may become the dominant cation in the 

Deadwood aquifer as the water flows downgradient.

Relations between various common ions and 

well depth are shown in figure 20. Fluoride and 

sodium concentrations, percent sodium, and SAR 

generally increase with increasing well depth. Two of 

33 samples equal or exceed the MCL for fluoride; both 

of these samples were collected from a well with a 

depth of 1,105 feet. 
Water-Quality Characteristics of Selected Aquifers 43

Table 4. Summary of concentrations of common ions in ground water

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter (mg/L) is approximately equal to one part per million; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum

Precambrian aquifers

Solids, residue at 180°C 58 0 293 249 60 1,970

Solids, sum of constituents 56 0 230 221 54 642

Calcium 112 0 44 44 6.0 108

Magnesium 112 0 15 14 1.7 52

Sodium 108 0 10 8.1 1.5 70

Sodium, percent 57 0 13 10 6.0 41

Sodium-adsorption ratio 108 0 0.3 0.3 0 2.0

Potassium 58 0 4.0 3.8 1.0 16

Bicarbonate 22 0 165 168 21 268

Carbonate 0 0 -- -- -- --

Sulfate 112 9 35 21 <5.0 345

Chloride 109 41 11 5.6 0.5 161

Fluoride 55 3 0.5 0.3 0.1 2.5

Bromide 0 0 -- -- -- --

Iodide 0 0 -- -- -- --

Silica 64 0 10 8.6 3.5 27

Deadwood aquifer

Solids, residue at 180°C 31 0 254 248 65 528

Solids, sum of constituents 32 0 262 248 48 469

Calcium 37 0 46 50 8.6 70

Magnesium 37 0 23 20 2.5 78

Sodium 37 0 17 5.9 1.2 160

Sodium, percent 32 0 14 7.0 1.0 85

Sodium-adsorption ratio 37 0 0.7 0.2 0 9.0

Potassium 32 0 2.8 2.2 0.1 10

Bicarbonate 3 0 249 260 220 268

Carbonate 2 0 0 0 0 0

Sulfate 37 2 27 21 3.4 88

Chloride 37 4 5.2 2.0 0.5 40

Fluoride 33 1 0.7 0.3 <0.1 5.4

Bromide 1 0 -- -- 0.3 0.3

Iodide 0 0 -- -- -- --

Silica 33 0 11 10 3.3 18

Madison aquifer

Solids, residue at 180°C 80 0 490 260 162 2,300

Solids, sum of constituents 99 0 428 260 161 1,820

Calcium 127 0 70 54 5.6 430

Magnesium 127 0 26 25 2.0 120

Sodium 122 0 39 5.4 0.8 260

Sodium, percent 103 0 14 6.0 1.0 57

Sodium-adsorption ratio 122 0 1.0 0.2 0 18

Potassium 103 0 6.0 2.8 0.7 55

Bicarbonate 41 0 250 222 166 454

Carbonate 24 0 0.3 0 0 6.0
44 Water-Quality Characteristics in the Black Hills Area, South Dakota

Madison aquifer—Continued

Sulfate 127 10 96 23 <1.0 453

Chloride 124 15 55 3.5 0.2 1,000

Fluoride 89 0 0.7 0.4 0.1 18

Bromide 4 0 0.18 0.10 0.1 0.4

Iodide 2 0 0.03 0.03 0.01 0.04

Silica 62 0 11 11 3.4 34

Minnelusa aquifer

Solids, residue at 180°C 190 0 619 296 128 5,055

Solids, sum of constituents 176 0 512 271 120 2,700

Calcium 250 0 127 68 2.2 695

Magnesium 248 0 32 23 0.6 194

Sodium 245 0 18 3.8 0.05 731

Sodium, percent 196 0 4.4 2.0 0 37

Sodium-adsorption ratio 243 0 0.3 0.1 0 21

Potassium 197 0 3.0 2.0 0.7 19

Bicarbonate 86 0 252 249 149 370

Carbonate 15 0 -- 0 0 10

Sulfate 249 15 257 32 <2.0 3,438

Chloride 236 38 12 2.0 <0.1 230

Fluoride 185 8 0.5 0.3 0.01 2.8

Bromide 5 0 0.3 0.1 0.1 0.8

Iodide 3 0 0.01 0.01 0.01 0.01

Silica 104 0 9.8 11 2.2 33

Minnekahta aquifer

Solids, residue at 180°C 24 0 509 346 228 2,255

Solids, sum of constituents 24 0 410 330 233 1,920

Calcium 28 0 109 80 45 425

Magnesium 28 0 30 26 12 105

Sodium 26 0 7.9 4.0 1.1 100

Sodium, percent 25 0 3.2 2.0 1.0 15

Sodium-adsorption ratio 26 0 0.1 0.1 0 1.0

Potassium 25 0 2.4 1.9 1.1 12

Bicarbonate 21 0 321 316 230 412

Carbonate 2 0 0 0 0 0

Sulfate 28 1 139 32 <1.0 1,385

Chloride 28 2 7.5 3.0 0.5 119

Fluoride 25 4 0.3 0.2 <0.1 1.0

Bromide 0 0 -- -- -- --

Iodide 0 0 -- -- -- --

Silica 7 0 12 12 4.8 24

Inyan Kara aquifer

Solids, residue at 180°C 111 0 760 682 174 3,170

Solids, sum of constituents 102 0 742 673 170 3,300

Calcium 177 0 95 71 1.6 505

Table 4. Summary of concentrations of common ions in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter (mg/L) is approximately equal to one part per million; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Aquifers 45

Inyan Kara aquifer—Continued

Magnesium 174 1 34 24 <1.0 279

Sodium 171 0 145 127 1.0 1,000

Sodium, percent 103 0 45 37 1.0 99

Sodium-adsorption ratio 169 0 8.9 2.0 0 79

Potassium 105 0 6.4 6.2 0.1 19

Bicarbonate 31 0 254 258 167 438

Carbonate 0 0 -- -- -- --

Sulfate 177 0 462 330 5.0 2,030

Chloride 176 42 11 5.0 0.1 140

Fluoride 105 1 0.6 0.5 0.1 4.0

Bromide 9 0 0.2 0.1 0.1 0.7

Iodide 10 0 0.04 0.01 0.01 0.26

Silica 112 1 6.1 4.6 <0.1 17

Spearfish aquifer

Solids, residue at 180°C 3 0 294 286 274 322

Solids, sum of constituents 3 0 257 259 247 266

Calcium 13 0 223 116 36 661

Magnesium 13 0 42 23 10 109

Sodium 13 0 63 5.0 2.0 608

Sodium, percent 4 0 3.3 2.0 2.0 7.0

Sodium-adsorption ratio 13 0 0.9 0.2 0.1 8.0

Potassium 4 0 3.9 2.1 1.5 10

Bicarbonate 2 0 224 224 221 227

Carbonate 0 0 -- -- -- --

Sulfate 13 0 635 98 10 2,338

Chloride 13 7 11 4.4 1.5 50

Fluoride 4 0 0.6 0.3 0.2 1.6

Bromide 0 0 -- -- -- --

Iodide 0 0 -- -- -- --

Silica 9 0 5.5 4.8 3.5 9.4

Sundance aquifer

Solids, residue at 180°C 12 0 1,264 1,440 414 1,930

Solids, sum of constituents 12 0 1,202 1,365 399 1,820

Calcium 14 0 155 150 56 352

Magnesium 14 0 86 89 10 220

Sodium 14 0 144 118 6.7 512

Sodium, percent 12 0 29 24 3.0 84

Sodium-adsorption ratio 14 0 3.3 2.0 0.2 16

Potassium 12 0 8.2 6.9 3.9 14

Bicarbonate 2 0 305 305 283 326

Carbonate 0 0 -- -- -- --

Sulfate 14 0 780 1,000 99 1,724

Chloride 14 0 13 8.2 1.1 65

Fluoride 12 0 2.5 0.5 0.1 25

Table 4. Summary of concentrations of common ions in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter (mg/L) is approximately equal to one part per million; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
46 Water-Quality Characteristics in the Black Hills Area, South Dakota

Sundance aquifer—Continued

Bromide 2 0 0.15 0.15 0.1 0.2

Iodide 2 0 0.03 0.03 0.01 0.05

Silica 13 0 10 9.7 2.2 26

Morrison aquifer

Solids, residue at 180°C 8 0 460 383 256 751

Solids, sum of constituents 7 0 443 340 234 793

Calcium 15 0 146 74 2.5 519

Magnesium 15 0 52 23 1.1 268

Sodium 13 0 77 30 2.7 357

Sodium, percent 8 0 22 15 5.0 81

Sodium-adsorption ratio 13 0 2.8 0.8 0 19

Potassium 8 0 6.4 6.7 2.9 9.0

Bicarbonate 1 0 -- -- 208 208

Carbonate 0 0 -- -- -- --

Sulfate 15 0 489 208 46 2,056

Chloride 15 5 7.8 3.0 0.4 56

Fluoride 9 0 0.5 0.5 0.2 0.9

Bromide 0 0 -- -- -- --

Iodide 0 0 -- -- -- --

Silica 11 0 8.9 5.3 3.8 17

Pierre aquifer

Solids, residue at 180°C 0 0 -- -- -- --

Solids, sum of constituents 0 0 -- -- -- --

Calcium 28 0 164 144 41 365

Magnesium 28 0 88 49 10 508

Sodium 28 0 227 176 8.7 757

Sodium, percent 0 0 -- -- -- --

Sodium-adsorption ratio 28 0 3.6 3.0 0.3 11

Potassium 0 0 -- -- -- --

Bicarbonate 0 0 -- -- -- --

Carbonate 0 0 -- -- -- --

Sulfate 28 0 964 659 15 4,126

Chloride 28 7 52 26 <10 222

Fluoride 0 0 -- -- -- --

Bromide 0 0 -- -- -- --

Iodide 0 0 -- -- -- --

Silica 28 0 6.9 6.3 2.0 13

Graneros aquifer

Solids, residue at 180°C 0 0 --- -- -- --

Solids, sum of constituents 0 0 -- -- -- --

Calcium 10 0 168 133 25 459

Magnesium 10 0 54 51 12 122

Sodium 10 0 91 66 3.6 289

Sodium, percent 0 0 -- -- -- --

Table 4. Summary of concentrations of common ions in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter (mg/L) is approximately equal to one part per million; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Aquifers 47

Graneros aquifer—Continued

Sodium-adsorption ratio 10 0 1.6 1.5 0 4.0

Potassium 0 0 -- -- -- --

Bicarbonate 0 0 -- -- -- --

Carbonate 0 0 -- -- -- --

Sulfate 10 0 539 286 87 1,598

Chloride 10 7 41 39 <10 57

Fluoride 0 0

Bromide 0 0 -- -- -- --

Iodide 0 0 -- -- -- --

Silica 10 0 4.7 4.7 3.7 6.4

Newcastle aquifer

Solids, residue at 180°C 8 0 460 400 279 1,010

Solids, sum of constituents 8 0 415 355 277 862

Calcium 8 0 80 76 10 170

Magnesium 8 0 18 18 1.9 32

Sodium 8 0 35 13 8.0 164

Sodium, percent 8 0 20 11 6.0 90

Sodium-adsorption ratio 8 0 1.9 0.4 0.2 12

Potassium 8 0 8.0 7.1 4.1 17

Bicarbonate 0 0 -- -- -- --

Carbonate 0 0 -- -- -- --

Sulfate 8 0 128 103 23 410

Chloride 8 0 3.4 2.6 1.1 8.7

Fluoride 8 0 0.6 0.6 0.3 1.4

Bromide 0 0 -- -- -- --

Iodide 0 0 -- -- -- --

Silica 5 0 8.4 8.6 6.9 10

Alluvial aquifers

Solids, residue at 180°C 78 0 559 329 127 2,380

Solids, sum of constituents 81 0 503 323 100 2,280

Calcium 116 0 121 77 13 536

Magnesium 116 0 39 25 3.2 274

Sodium 115 0 62 10 2.0 778

Sodium, percent 85 0 13 6.0 1.0 87

Sodium-adsorption ratio 115 0 1.1 0.3 0 12

Potassium 85 0 5.0 4.0 0.9 42

Bicarbonate 21 0 266 244 158 458

Carbonate 3 0 0 0 0 0

Sulfate 116 0 360 99 2.9 3,000

Chloride 114 15 19 6.1 1.0 194

Fluoride 73 1 0.4 0.3 0.1 1.5

Bromide 3 0 0.09 0.08 0.06 0.13

Iodide 0 0 -- -- -- --

Silica 51 0 7.7 7.1 0.7 25

Table 4. Summary of concentrations of common ions in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter (mg/L) is approximately equal to one part per million; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
48 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 16. Boxplots of concentrations of selected common ions for selected aquifers.

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

800

200

400

600

DISSOLVED CALCIUM,

IN MILLIGRAMS PER LITER

112/0 37/0 127/0 250/0 28/0 177/0 13/0 14/0 15/0 28/0 10/0 8/0 116/0

0

3,600

1,000

2,000

3,000

DISSOLVED SOLIDS, SUM OF CONSTITUENTS,

IN MILLIGRAMS PER LITER

56/0 32/0 99/0 176/0 24/0 102/0 3/0 12/0 7/0 0/0 0/0 8/0 81/0

0

2,000

1,000

4,000

3,000

5,000

6,000

DISSOLVED SOLIDS, RESIDUE AT 180 DEGREES

CELSIUS, IN MILLIGRAMS PER LITER

58/0 31/0 80/0 190/0 24/0 111/0 3/0 8/0 12/0 0/0 0/0 8/0 78/0

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 49

Figure 16. Boxplots of concentrations of selected common ions for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

120

20

40

60

80

100

PERCENT SODIUM

57/0 32/0 103/0 196/0 25/0 103/0 4/0 12/0 8/0 0/0 0/0 8/0 85/0

0

600

100

200

300

400

500

DISSOLVED MAGNESIUM,

IN MILLIGRAMS PER LITER

112/0 37/0 127/0 248/0 28/0 174/1 13/0 14/0 15/0 28/0 10/0 8/0 116/0

0

1,200

200

400

600

800

1,000

DISSOLVED SODIUM,

IN MILLIGRAMS PER LITER

108/0 37/0 122/0 245/0 26/0 171/0 13/0 14/0 13/0 28/0 10/0 8/0 115/0

Major aquifers Minor aquifers
50 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 16. Boxplots of concentrations of selected common ions for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

500

100

200

300

400

DISSOLVED BICARBONATE,

IN MILLIGRAMS PER LITER

22/0 3/0 41/0 86/0 21/0 31/0 2/0 2/0 1/0 0/0 0/0 0/0 21/0

0

100

20

40

60

80

SODIUM-ADSORPTION RATIO

108/0 37/0 122/0 243/0 26/0 169/0 13/0 14/0 13/0 28/0 10/0 8/0 115/0

0

60

10

20

30

40

50

DISSOLVED POTASSIUM,

IN MILLIGRAMS PER LITER

58/0 32/0 103/0 197/0 25/0 105/0 4/0 12/0 8/0 0/0 0/0 8/0 85/0

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 51

Figure 16. Boxplots of concentrations of selected common ions for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

30

5

10

15

20

25

DISSOLVED FLUORIDE,

IN MILLIGRAMS PER LITER

55/3 33/1 89/0 185/8 25/4 105/1 4/0 12/0 9/0 0/0 0/0 8/0 73/1

0

5,000

1,000

2,000

3,000

4,000

DISSOLVED SULFATE,

IN MILLIGRAMS PER LITER

112/0 37/2 127/10 249/15 28/1 177/0 13/0 14/0 15/0 28/0 10/0 8/0 116/0

0

400

100

200

300

DISSOLVED CHLORIDE,

IN MILLIGRAMS PER LITER

109/41 37/4 124/15 236/38 28/2 176/42 13/7 14/0 15/5 28/7 10/7 8/0 114/15

1,100

1,000

Major aquifers Minor aquifers
52 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 16. Boxplots of concentrations of selected common ions for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

40

10

20

30

DISSOLVED SILICA,

IN MILLIGRAMS PER LITER

64/0 33/0 62/0 104/0 7/0 112/1 9/0 13/0 11/0 28/0 10/0 5/0 51/0

0

1.0

0.2

0.4

0.6

0.8

DISSOLVED BROMIDE,

IN MILLIGRAMS PER LITER

0/0 1/0 4/0 5/0 0/0 9/0 0/0 2/0 0/0 0/0 0/0 3/0 0/0

0

0.4

0.1

0.2

0.3

DISSOLVED IODIDE,

IN MILLIGRAMS PER LITER

0/0 0/0 2/0 3/0 0/0 10/0 0/0 2/0 0/0 0/0 0/0 0/0 0/0

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 53

Figure 16. Boxplots of concentrations of selected common ions for selected aquifers.--Continued

EXPLANATION

Single sample

Number of samples/Number of samples

 with concentrations below the laboratory

 reporting limit

114/15

Secondary Maximum Contaminant Level

 (recommended) (U.S. Environmental

 Protection Agency, 1994a)

Highest detection limit

Maximum Contaminant Level (mandatory

 (U.S. Environmental Protection Agency,

 1994a)

25th percentile

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile
54 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 17. Trilinear diagrams showing proportional concentrations of major ions in selected aquifers.

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

PERCENT OF REACTING VALUES PERCENT OF REACTING VALUES

PERCENT OF REACTING VALUES PERCENT OF REACTING VALUES

PERCENT OF REACTING VALUES PERCENT OF REACTING VALUES

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

8060

40

20

40

60

80

80

60

40

20

PRECAMBRIAN AQUIFERS

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

8060

40

20

40

60

80

80

60

40

20

DEADWOOD AQUIFER

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

60

40

20

40

60

80

80

60

40

20

MINNELUSA AQUIFER

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

60

40

20

40

60

80

80

60

40

20

MINNEKAHTA AQUIFER

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

60

40

20

40

60

80

80

60

40

20

INYAN KARA AQUIFER

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

8060

40

20

40

60

80

80

60

40

20

MADISON AQUIFER

Number of samples = 109 Number of samples = 243

Number of samples = 37 Number of samples = 26

Number of samples = 122 Number of samples = 171
Water-Quality Characteristics of Selected Aquifers 55

 

Figure 17. Trilinear diagrams showing proportional concentrations of major ions in selected aquifers.--Continued

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

8060

40

20

40

60

80

80

60

40

20

SPEARFISH AQUIFER

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

8060

40

20

40

60

80

80

60

40

20

SUNDANCE AQUIFER

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

60

40

20

40

60

80

80

60

40

20

PIERRE AQUIFER

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

60

40

20

40

60

80

80

60

40

20

GRANEROS AQUIFER

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

60

40

20

40

60

80

80

60

40

20

NEWCASTLE AQUIFER

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

8060

40

20

40

60

80

80

60

40

20

MORRISON AQUIFER

Number of samples = 13 Number of samples = 28

Number of samples = 14 Number of samples = 10

Number of samples = 13 Number of samples = 8

PERCENT OF REACTING VALUES PERCENT OF REACTING VALUES

PERCENT OF REACTING VALUES PERCENT OF REACTING VALUES

PERCENT OF REACTING VALUES PERCENT OF REACTING VALUES
56 Water-Quality Characteristics in the Black Hills Area, South Dakota

Table 5. Relation between specific conductance and dissolved solids

for selected aquifers

[S = dissolved solids, in milligrams per liter; K = specific conductance, in microsiemens

per centimeter]

Aquifer Equation of line R2 Number of

samples

Precambrian S = 0.6151K - 14.42 0.9108 39

Deadwood S = 0.5792K - 1.93 .9687 33

Madison S = 0.6091K - 3.73 .9793 91

Minnelusa S = 1.0070K - 215.09 .9777 159

Minnekahta S = 0.8860K - 177.62 .9912 25

Inyan Kara S - 0.7842K - 98.49 .9479 85

Sundance S = 0.7986K - 129.34 .9750 10

Morrison S = 0.7601K - 66.71 .9781 7

Newcastle S = 0.7105K - 67.20 .9817 8

Alluvial S = 0.8302K - 105.62 .9601 64

Figure 17. Trilinear diagrams showing proportional

concentrations of major ions in selected aquifers.--Continued

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

6080

40

60

80

60

40

20

20

80

60

4020

40

60

80

80

60

40

20

ALLUVIAL AQUIFERS

Number of samples = 115

PERCENT OF REACTING VALUES
Water-Quality Characteristics of Selected Aquifers 57

 

A1 A2 A1 A2 A1 A2

B1

C1

B2 B1

C1 B2

D2 E1

D3 E2 E1 B3

C2

D1

B3

B1

B2

C2 C1

C3 D1

D2

E3 E2 C2

C3

D3

E3 C3

B3

0 3 6 7 8 9 10 11 12

3,100

3,000

2,900

2,800

2,700

2,600

2,500

2,400

2,300

2,200

2,100

2,000

1,900

1,800

1,700

1,600

1,500

1,400

1,300

1,200

1,100

1,000

ADJUSTED SODIUM-ADSORPTION RATIO (SAR)

MULTIPLIED BY 0.7

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER AT 25o CELSIUS 

(ECx10 AT 25o C) ADJUSTED FOR CALCIUM, SULFATE, AND RAINFALL 6

EXPLANATION

SOIL TEXTURE

 Sand

 Loamy sands, sandy loams

 Loams, silts, silt loams

 Sandy clay loams, silty clay

 loams, clay loams

 Silty clays, sandy clays, clays

DEPTH BELOW LAND SURFACE

 TO A MORE-PERMEABLE OR

 LESS-PERMEABLE MATERIAL

 40 inches or less to a more-

 permeable material

 40 to 72 inches to a more-

 permeable material

 20 to 60 inches to a less-

 permeable material

SPECIFIC CONDUCTANCE

 Maximum values are based on

 12 inches or less average

 rainfall during the frost-free

 season. For each additonal 

 inch of rainfall, the maximum

 values of conductivity may be 

 increased by 100. Average

 growing season rainfall for

 the Black Hills area is 14 inches,

 so the conductivity of each

 plotted value has been

 reduced by 200 microsiemens.

 For water having more than

 200 milligrams per liter of

 calcium and more than 960

 milligrams per liter of sulfate,

 the maximum conductance

 value may be increased by 400

 microsiemens.

A

B

C

E

1

2

3

AVERAGE CHEMICAL QUALITY OF

 MAJOR AQUIFERS

AVERAGE CHEMICAL QUALITY OF

 MINOR AQUIFERS

Figure 18. South Dakota irrigation-water classification diagram. This diagram is based on South Dakota standards

(revised Jan. 7, 1982) for maximum allowable specific conductance and adjusted sodium-adsorption-ratio values for

which an irrigation permit can be issued for applying water under various soil-texture conditions. Water can be applied

under all conditions at or above the plotted point, but not below it, provided other conditions as defined by the State

Conservation Commission are met (from Koch, 1983).

D

Inyan Kara

Minnekahta

Minnelusa

Madison

Deadwood

Precambrian

Alluvial

Graneros

Newcastle

Pierre

Morrison

Sundance

Spearfish

900

800

700

600

500

400

300

200

100

x

x

*

x

*

#

#

x

*

*

#

#
58 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 19. Relations between sulfate and specific conductance in the Madison, Minnelusa, and Inyan Kara aquifers.

MADISON AQUIFER

INYAN KARA AQUIFER

MINNELUSA AQUIFER

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

500

0

50

100

150

200

250

300

350

400

450

DISSOLVED SULFATE, IN MILLIGRAMS PER LITER

Sulfate=0.2649K-71.88

 where K=specific conductance

 in microsiemens per centimeter

R2=0.7582

n=99

0

2,200

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

DISSOLVED SULFATE, IN MILLIGRAMS PER LITER

Sulfate=0.7143K-306.49

 where K=specific conductance

 in microsiemens per centimeter

R2=0.9551

n=180

0

2,400

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

DISSOLVED SULFATE, IN MILLIGRAMS PER LITER

Sulfate=0.5439K-193.37

 where K=specific conductance

 in microsiemens per centimeter

R2=0.8223

n=150
Water-Quality Characteristics of Selected Aquifers 59

Figure 20. Selected relations between common ions and well depth for selected aquifers.

DEADWOOD AQUIFER

WELL DEPTH, IN FEET

0 200 400 600 800 1,000 1,200 1,400 1,600

WELL DEPTH, IN FEET

0 200 400 600 800 1,000 1,200 1,400 1,600

0

170

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

DISSOLVED SODIUM, IN MILLIGRAMS PER LITER

R2 = 0.1457

0

90

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

PERCENT SODIUM

R2 = 0.1430

0

10

1

2

3

4

5

6

7

8

9

SODIUM-ADSORPTION RATIO

R2 = 0.1098

0

6.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

DISSOLVED FLUORIDE, N MILLIGRAMS PER LITER

R2 = 0.1672
60 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 20. Selected relations between common ions and well depth for selected aquifers.--Continued

WELL DEPTH, IN FEET

MADISON AQUIFER

WELL DEPTH, IN FEET

0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

440

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

320

340

360

380

400

420

DISSOLVED CALCIUM, IN MILLIGRAMS PER LITER

R2 = 0.2398

0

280

20

40

60

80

100

120

140

160

180

200

220

240

260

DISSOLVED SODIUM, IN MILLIGRAMS PER LITER

R2 = 0.2418

0

60

5

10

15

20

25

30

35

40

45

50

55

PERCENT SODIUM

R2 = 0.2032

0

60

5

10

15

20

25

30

35

40

45

50

55

DISSOLVED POTASSIUM, IN MILLIGRAMS PER LITER

R2 = 0.2688

100

10,000

150

200

250

300

400

500

600

700

800

900 1,000

1,500

2,000

2,500

3,000

4,000

5,000

6,000

7,000

8,000

9,000

DISSOLVED SOLIDS, RESIDUE ON EVAPORATION AT

180 DEGREES CELSIUS, IN MILLIGRAMS PER LITER

R2 = 0.4651

100

10,000

150

200

250

300

400

500

600

700

800

900 1,000

1,500

2,000

2,500

3,000

4,000

5,000

6,000

7,000

8,000

9,000

DISSOLVED SOLIDS, SUM OF CONSTITUENTS,

IN MILLIGRAMS PER LITER

R2 = 0.4812
Water-Quality Characteristics of Selected Aquifers 61

Figure 20. Selected relations between common ions and well depth for selected aquifers.--Continued

WELL DEPTH, IN FEET

MADISON AQUIFER

WELL DEPTH, IN FEET

0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

0

500

50

100

150

200

250

300

350

400

450

DISSOLVED SULFATE, IN MILLIGRAMS PER LITER

R2 = 0.3801

0

1,100

100

200

300

400

500

600

700

800

900

1,000

DISSOLVED CHLORIDE, IN MILLIGRAMS PER LITER

R2 = 0.1505

2

36

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

DISSOLVED SILICA, IN MILLIGRAMS PER LITER

R2 = 0.4805
62 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 20. Selected relations between common ions and well depth for selected aquifers.--Continued

WELL DEPTH

MINNELUSA AQUIFER

WELL DEPTH

0 4,500 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 0 4,500 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

0

750

50

100

150

200

250

300

350

400

450

500

550

600

650

700

DISSOLVED CALCIUM, IN MILLIGRAMS PER LITER

R2 = 0.2766

0

200

20

40

60

80

100

120

140

160

180

DISSOLVED MAGNESIUM, IN MILLIGRAMS PER LITER

R2 = 0.3367

0

2,000

200

400

600

800

1,000

1,200

1,400

1,600

1,800

DISSOLVED SULFATE, IN MILLIGRAMS PER LITER

R2 = 0.2888

0

3.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

DISSOLVED FLUORIDE, IN MILLIGRAMS PER LITER

R2 = 0.2496

DISSOLVED SOLIDS, RESIDUE ON EVAPORATION AT

180 DEGREES CELSIUS, IN MILLIGRAMS PER LITER

DISSOLVED SOLIDS, SUM OF CONSTITUENTS,

IN MILLIGRAMS PER LITER

5,500

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000 R2 = 0.3993

3,000

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

2,800 R2 = 0.3084
Water-Quality Characteristics of Selected Aquifers 63

Figure 20. Selected relations between common ions and well depth for selected aquifers.--Continued

WELL DEPTH, IN FEET

MINNELUSA AQUIFER

0 4,500 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

0

34

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

DISSOLVED SILICA, IN MILLIGRAMS PER LITER

R2 = 0.3915
64 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 20. Selected relations between common ions and well depth for selected aquifers.--Continued

WELL DEPTH, IN FEET

INYAN KARA AQUIFER

0 2,800 0 200 400 600 800 1,0001,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

WELL DEPTH, IN FEET

0 2,800 0 200 400 600 800 1,0001,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

0

100

10

20

30

40

50

60

70

80

90

PERCENT SODIUM

R2 = 0.2987

0

18

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

DISSOLVED SILICA, IN MILLIGRAMS PER LITER

R2 = 0.1262

0

550

50

100

150

200

250

300

350

400

450

500

DISSOLVED CALCIUM, IN MILLIGRAMS PER LITER

R2 = 0.1393

0

300

20

40

60

80

100

120

140

160

180

200

220

240

260

280

DISSOLVED MAGNESIUM, IN MILLIGRAMS PER LITER

R2 = 0.1238

0

85

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

SODIUM-ADSORPTION RATIO

R2 = 0.1065
Water-Quality Characteristics of Selected Aquifers 65

Madison Aquifer

Water from the Madison aquifer generally is 

fresh, but can be slightly saline (dissolved solids 

concentration of 1,000 to 3,000 mg/L) near Edgemont, 

Rapid City, and northwest of Spearfish. Samples from 

the Madison aquifer have the highest mean chloride 

concentration of the major aquifers. 

The two main water types in the Madison aquifer 

are calcium magnesium bicarbonate type and calcium 

sodium chloride sulfate type (fig. 17). Calcium, 

magnesium, and bicarbonate are dominant among the 

common ions throughout most of the study area due to 

the dissolution of calcite and dolomite. The latter water 

type exists only in the southwestern part of the study 

area (Naus and others, in press). The high concentrations of chloride, sulfate, and sodium in the southwestern part of the study area relative to the rest of the 

study area probably reflect the presence of more 

evolved ground water and regional flow from the west, 

and/or the presence of evaporite minerals available for 

dissolution (Naus and others, in press).

In the Madison aquifer, calcium, sodium, potassium, sulfate, chloride, and silica concentrations and 

percent sodium generally increase with increasing well 

depth (fig. 20). Although there were not enough values 

of bicarbonate concentrations with a corresponding 

well depth for a statistical correlation, a visual check of 

the well locations in relation to the outcrop showed that 

bicarbonate concentrations decrease with increasing 

distance from the outcrop and, hence, probably 

decrease with increasing well depth. Generally, 

chloride concentrations, sodium concentrations, and 

percent sodium are higher in Fall River County than in 

other counties in the study area. 

About 25 percent of the samples (25 of 99) 

exceed the SMCL for dissolved solids (sum of constituents); all but one of these samples were collected from 

wells located downgradient from the outcrop with 

depths greater than 2,000 feet. About 16 percent of the 

samples (21 of 127 samples) equal or exceed the 

SMCL for sulfate, and about 12 percent of the samples 

(15 of 124 samples) equal or exceed the SMCL of 

250 mg/L for chloride. All of the samples that exceed 

these SMCL’s were collected from wells located downgradient of the outcrop and most of the wells were in 

Fall River County. The higher sulfate concentrations in 

the Madison aquifer may be caused by the dissolution 

of anhydrite or leakage of water from the Minnelusa 

aquifer (Kyllonen and Peter, 1987). One of 89 samples 

exceeds the MCL for fluoride.

Minnelusa Aquifer

Water from the Minnelusa aquifer typically is 

fresh, but can be slightly saline at some locations 

greater than about 5 miles from the outcrop. Generally, 

calcium, bicarbonate, and sulfate are dominant among 

the common ions in the Minnelusa aquifer. Of all the 

major aquifers, the Minnelusa aquifer had the highest 

mean calcium concentration and the lowest median 

sodium concentration, percent sodium (equal to 

samples from the Minnekahta aquifer), and SAR (equal 

to samples from the Minnekahta aquifer). 

The three main water types in the Minnelusa 

Formation are calcium magnesium bicarbonate type, 

calcium magnesium sulfate type, and calcium magnesium bicarbonate sulfate chloride type. Water in the 

Minnelusa aquifer generally evolves downgradient 

from a calcium magnesium bicarbonate type to a calcium magnesium sulfate type due to dissolution of 

anhydrite. In the southern part of the study area, 

ground water is characterized by higher concentrations 

of sodium and chloride. The higher chloride concentrations in this area could reflect hydraulic connection 

between the Madison and Minnelusa aquifers (Naus 

and others, in press). The dissolution of evaporite minerals and the presence of more evolved ground water 

also may contribute toward the occurrence of this water 

type in the Minnelusa aquifer (Naus and others, in 

press).

In the Minnelusa aquifer, calcium, magnesium, 

sulfate, fluoride, and silica concentrations generally 

increase with increasing well depth (fig. 20). The 

increasing concentrations reflect the dissolution of 

many minerals as the water flows downgradient from 

the outcrop of the Minnelusa Formation. Concentrations of chloride and sodium vary with geographic 

location and do not show a relation to well depth (or 

distance from outcrop). The chloride and sodium 

concentrations are higher in the southern Black Hills 

than in other areas.

The concentration of sulfate in the aquifer is 

dependent on the amount of anhydrite present in the 

Minnelusa Formation. Near the outcrop, anhydrite has 

been dissolved and removed; hence, sulfate concentrations near the outcrop are low (less than 250 mg/L). 

Surrounding the core of the Black Hills and downgradient from the Minnelusa Formation outcrop is a 

sulfate transition zone (Kyllonen and Peter, 1987), 

within which the sulfate concentrations range from 250 

to 1,000 mg/L. The transition zone is approximately 2 

to 10 miles wide (fig. 21) and marks an area of active 
66 Water-Quality Characteristics in the Black Hills Area, South Dakota

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Nemo

Central

City

BELLE FOURCHE

Newell

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Pringle

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Grace Cooli d ge

Angostura

Reservoir

Iron

Castl e Cr

N Fork Castle Cr

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

BELLE

Creek

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Boxelder

Rapid

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Little

Creek

Gulch

H gi gins

Creek

Creek

Cr

Bottom False

Creek

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Less than 250

SULFATE CONCENTRATIONS,

 IN MILLIGRAMS PER LITER

250 - 1,000

Greater than 1,000

Figure 21. Distribution of sulfate concentrations in the Minnelusa aquifer (from Naus and others, in press).

WELL COMPLETED IN THE

 MINNELUSA AQUIFER FOR

 WHICH THERE IS A SULFATE

 ANALYSIS

EXPLANATION

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

MINNELUSA FORMATION

 ABSENT (from Carter and

 Redden, 1999c)

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
Water-Quality Characteristics of Selected Aquifers 67

removal of anhydrite by dissolution. The transition 

zone probably is shifting downgradient over geologic 

time as the anhydrite in the formation is dissolved 

(Kyllonen and Peter, 1987). Downgradient from the 

transition zone, sulfate concentrations are greater than 

1,000 mg/L, which represents a zone in which thick 

anhydrite beds remain in the formation.

More than 20 percent of the samples (38 of 176) 

exceed the SMCL for dissolved solids (sum of constituents); most of these samples were collected from 

wells located downgradient from the outcrop with 

depths greater than 1,000 feet. About 20 percent of the 

samples (51 of 249) collected exceed the SMCL for 

sulfate; generally most of these samples are from wells 

located downgradient from the outcrop. Seven of 185 

samples equal or exceed the SMCL for fluoride; all 7 of 

these samples were located downgradient from the 

outcrop. None of the samples exceed the MCL for 

fluoride.

Minnekahta Aquifer

Water from the Minnekahta aquifer generally is 

fresh. Generally, calcium and bicarbonate are dominant among the common ions, although a few samples 

also had high sulfate concentrations. Of the major 

aquifers, the Minnekahta aquifer had the highest 

median calcium and magnesium concentrations and the 

highest mean and median bicarbonate and silica concentrations (table 4). The Minnekahta aquifer also had 

the lowest mean sodium concentration and the lowest 

mean and median potassium concentration, percent 

sodium (equal to the median of the Minnelusa aquifer), 

and SAR (equal to the median of the Minnelusa 

aquifer). 

The Minnekahta aquifer generally yields a calcium bicarbonate water (fig. 17) due to the dissolution 

of calcite. In samples from four wells completed in the 

Minnekahta aquifer, the water type is calcium sulfate. 

The four wells with a substantial sulfate component 

generally are farther from the outcrop than the wells 

dominated by bicarbonate. A possible source for the 

sulfate is leakage from or through the underlying 

Minnelusa aquifer.

Four of 24 samples exceed the SMCL for dissolved solids (sum of constituents). Four of 28 samples 

exceed the SMCL for sulfate; all of these samples were 

collected from wells that are farther from the outcrop 

than the other wells that were sampled.

Inyan Kara Aquifer

Water from the Inyan Kara aquifer is fresh to 

slightly saline, with the highest salinity occurring in the 

southern Black Hills. Generally, sodium and sulfate 

are dominant among the common ions, although 

calcium and bicarbonate concentrations also can be 

high depending on well depth and geographic location. 

Of the major aquifers, the Inyan Kara aquifer had the 

highest mean and median sodium concentration, percent sodium, SAR, and sulfate concentration and the 

highest mean magnesium concentration (table 4). The 

Inyan Kara aquifer also had the lowest mean and 

median silica concentration. 

The Inyan Kara aquifer may yield a sodium 

sulfate, calcium sulfate, calcium bicarbonate, or 

sodium bicarbonate water type (fig. 17) depending on 

geographical location and distance from the outcrop. 

The initial water types are similar to those of the 

Minnelusa aquifer—calcium sulfate or calcium bicarbonate—possibly because the Inyan Kara aquifer 

receives recharge from the underlying aquifers. Wells 

located on and near the outcrop of the Inyan Kara 

Group in the southern Black Hills generally yield a 

calcium sulfate water type, whereas wells in the eastern 

and northern Black Hills generally yield a calcium 

bicarbonate water type. In the southern Black Hills, the 

water evolves as it moves downgradient to a sodium 

sulfate water type or, locally, to a sodium bicarbonate 

water type (Gott and others, 1974). In the eastern and 

northern Black Hills, the water evolves to a sodium 

sulfate water type as it moves downgradient.

Percent sodium, SAR, and silica concentrations 

generally increase with increasing well depth, whereas 

calcium and magnesium concentrations decrease with 

increasing well depth. The change in concentrations 

indicates that sodium and silica are dissolving and calcium and magnesium are precipitating as the water 

flows downgradient from the outcrop of the Inyan Kara 

Group. The source of high sulfate concentrations on or 

near the outcrop may be from upward leakage of water 

from the Minnelusa aquifer or gypsiferous formations 

(Gypsum Spring or Spearfish Formations) or from the 

oxidation of sulfide minerals in the Inyan Kara aquifer 

(Kyllonen and Peter, 1987). 

Chloride concentrations vary with geographic 

location as opposed to distance from outcrop. In the 

southern Black Hills, chloride concentrations generally 

are higher than those in other areas. Sulfate concentrations generally are higher in the southern Black Hills 

than those in other areas, whereas silica concentrations 

generally are lower in the southern Black Hills.
68 Water-Quality Characteristics in the Black Hills Area, South Dakota

More than 60 percent of the samples (65 of 102 

samples) analyzed for dissolved solids (sum of constituents) exceed the SMCL for dissolved solids; most of 

these samples were collected from wells in the southern 

Black Hills or from wells located downgradient from 

the outcrop with depths greater than 500 feet. More 

than 60 percent of the samples (110 of 177 samples) 

collected exceed the SMCL for sulfate; almost every 

sample collected in the southern Black Hills exceeds 

the SMCL for sulfate. Two of 105 samples equal or 

exceed the SMCL for fluoride, and one of these 

samples equals the MCL for fluoride.

Minor Aquifers

Only three samples were analyzed for dissolved 

solids from the Spearfish aquifer. However, at least 

25 percent of the total number of samples probably 

would exceed the SMCL for dissolved solids, based on 

sulfate concentrations that are greater than 500 mg/L. 

Calcium, sulfate, and bicarbonate are dominant among 

the common ions in the Spearfish aquifer. About 

45 percent of the samples (6 of 13 samples) exceed the 

SMCL for sulfate. Water from the Spearfish aquifer 

generally is a calcium bicarbonate or calcium sulfate 

type (fig. 17). The dominance of sulfate increases with 

the amount of gypsum present in the formation.

Most samples (10 of 12 samples) from wells 

completed in the Sundance aquifer and some samples 

(3 of 7 samples) from wells completed in the Morrison 

aquifer exceed the SMCL for dissolved solids. In the 

Sundance aquifer, calcium, sodium, sulfate, and bicarbonate are dominant among the common ions. Almost 

all of the samples from the Sundance aquifer (12 of 14 

samples) exceed the SMCL for sulfate, and 1 of 12 

samples exceeds the MCL for fluoride. Most samples 

from the Sundance aquifer are slightly saline. Calcium, 

sulfate, and bicarbonate are dominant among the 

common ions in the Morrison aquifer. About 

45 percent of the samples (7 of 15 samples) exceed the 

SMCL for sulfate in water from the Morrison aquifer.

No samples from the Pierre aquifer were 

analyzed for dissolved solids; however, it is likely that 

most would exceed the SMCL for dissolved solids, 

based on sulfate concentrations. Sodium, calcium, 

sulfate, and bicarbonate (based on alkalinity) are dominant among the common ions in the Pierre aquifer. 

The mean bicarbonate concentration is about 360 mg/L 

and was determined by dividing the mean alkalinity 

(table 3) by 0.8202 (Hem, 1985). Almost all of the 

samples (24 of 28 samples) exceed the SMCL for 

sulfate.

Water from the Sundance, Morrison, and Pierre 

aquifers generally is a mixed type that includes dominant cations of sodium, calcium, and magnesium, and 

the dominant anions of sulfate and bicarbonate 

(fig. 17). The dominance of sodium and sulfate 

increases with increasing amounts of shale present in 

the formations due to the large cation-exchange capacities of clay minerals (generally sodium concentrations 

increase) and due to the reduced circulation of water 

through the shale (Hem, 1985). The dominance of 

calcium, magnesium, and bicarbonate increases with 

increasing amounts of sandstone (where calcium 

carbonate commonly is the cementing material) and 

carbonate rocks present in the formations.

No samples from aquifers in the Graneros Group 

(excluding the Newcastle aquifer) were analyzed for 

dissolved solids; however, at least 25 percent of the 

samples probably would exceed the SMCL for dissolved solids, based on sulfate concentrations. Wells 

completed in the Newcastle aquifer generally yield 

water that is low in specific conductance and dissolved 

solids, although one of eight samples from the Newcastle aquifer did exceed the SMCL for dissolved 

solids. Calcium, bicarbonate (based on alkalinity), and 

sulfate are the dominant common ions in the Graneros 

aquifer. Calcium and bicarbonate (based on alkalinity) 

are the dominant common ions in the Newcastle 

aquifer. None of the samples for either the Graneros or 

Newcastle aquifers were analyzed for bicarbonate. The 

mean bicarbonate concentration of the samples for both 

aquifers is about 300 mg/L based on the mean alkalinity (table 3). Fifty percent of the samples (5 of 10 

samples) collected from the Graneros aquifer exceed 

the SMCL for sulfate, and one of eight samples collected from the Newcastle aquifer exceeds the SMCL 

for sulfate. Of the minor aquifers, the Newcastle 

aquifer generally has the lowest sulfate concentrations 

and has the lowest dissolved solids concentrations.

The water type yielded from the Graneros 

aquifer varies from a calcium bicarbonate sulfate type 

to a mixed type (fig. 17), depending on the formation in 

which the well is completed. Most wells completed 

within the Graneros Group are completed in the 

Newcastle aquifer, which generally yields a calcium 

bicarbonate or calcium bicarbonate sulfate water type. 

Generally, calcium, sulfate, and bicarbonate are 

dominant among the common ions in the alluvial 

aquifers. The concentrations of all of the common ions 
Water-Quality Characteristics of Selected Aquifers 69

increase with distance from the central core of the 

Black Hills, which is largely due to the increasing 

dissolved ions in the streams and in the geologic 

formations that underlie the alluvial deposits. About 

25 percent of the samples (20 of 81 samples) exceed 

the SMCL for dissolved solids (sum of constituents); 

almost all those samples are from wells completed in 

alluvial deposits that overlie the Cretaceous-age shales. 

More than 30 percent of the samples (38 of 116 

samples) from alluvial aquifers exceed the SMCL for 

sulfate, and most of these are from wells completed in 

alluvial deposits that overlie the Cretaceous-age shales. 

The water type yielded from wells completed in 

alluvial aquifers varies greatly (fig. 17) and largely is 

dependent on the geologic formation that underlies the 

alluvial deposit. Generally, wells completed in alluvial 

deposits that do not overlie Cretaceous-age shales yield 

fresh water with a calcium bicarbonate or calcium magnesium bicarbonate water type. Wells that are completed in alluvial deposits that overlie the Cretaceousage shales generally yield slightly saline water with a 

mixed water type or a water type in which sodium is the 

dominant cation and/or sulfate is the dominant anion. 

Nutrients

Nitrogen and phosphorus are essential nutrients 

for plant growth. The major form of nitrogen in ground 

water is nitrate, although it also can occur in other 

forms including ammonium, ammonia, nitrite, and as 

part of organic solutes. Nitrate is very mobile in 

ground water, and it moves with little or no retardation 

(Freeze and Cherry, 1979). Elevated nitrate concentrations in ground water can originate from natural processes or as contamination from nitrogen sources, such 

as fertilizers and sewage. Nitrate concentrations above 

10 mg/L (U.S. Environmental Protection Agency, 

1994a) can cause methemoglobinemia (blue-baby 

syndrome) in small children.

In ground water, phosphorus generally occurs as 

phosphate. Orthophosphate generally is the most 

stable phosphate species that occurs. Phosphorus has a 

low solubility and, therefore, dissolved concentrations 

in ground water generally are no more than a few tenths 

of a milligram per liter (Hem, 1985). Concentrations 

above this level may indicate contamination by 

fertilizer or sewage. Concentrations of orthophosphate 

that were reported as phosphate were converted to 

concentrations as phosphorus for this report.

Summary statistics for selected nutrients, 

including nitrite, nitrite plus nitrate, ammonia, 

ammonia plus organic, phosphorus, and orthophosphate, are presented in table 6, and the significance of 

the various nutrients is described in table 1. Boxplots 

are presented in figure 22 for each of the nutrients.

Generally, concentrations of nitrogen and phosphorus are low in water from the major aquifers. Two 

of 40 samples collected from wells completed in 

Precambrian aquifers exceed the MCL of 10 mg/L for 

nitrite plus nitrate. No samples from the Deadwood, 

Madison, or Minnekahta aquifers exceed the MCL for 

any regulated nutrient constituent. A sample from the 

Madison aquifer has the highest concentration of 

ammonia plus organic (5.0 mg/L) of all the samples 

from all of the aquifers considered in this study. In the 

Minnelusa aquifer, 2 of 157 samples exceed the MCL 

for nitrite plus nitrate. A sample from the Minnelusa 

aquifer has the highest phosphorus concentration 

(2.1 mg/L) of all the samples from all aquifers 

considered in this study. 

Nitrogen and phosphorus concentrations generally are low in water from the Inyan Kara aquifer. Of 

the samples collected from wells completed in the 

Inyan Kara aquifer, 1 of 41 samples equalled the MCL 

of 1.0 mg/L for nitrite, and 1 of 81 samples exceeds the 

MCL for nitrite plus nitrate. Three individual samples 

from the Inyan Kara aquifer have the highest concentration of nitrite (1.0 mg/L), nitrite plus nitrate 

(60 mg/L), and ammonia (2.2 mg/L) of all the samples 

from all aquifers considered in this study (fig. 22). The 

extreme values for nitrite and nitrite plus nitrate are 

unusually high and may reflect poor well construction 

and surface contamination as opposed to aquifer 

conditions.

With the exception of alluvial aquifers, few 

samples from the minor aquifers were analyzed for 

nitrogen or phosphorus. Of the samples analyzed, 

nitrogen and phosphorus concentrations are low and 

none exceed the MCL for nitrite or for nitrite plus 

nitrate.
70 Water-Quality Characteristics in the Black Hills Area, South Dakota

Table 6. Summary of concentrations of nutrients in ground water

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter. One 

milligram per liter is approximately equal to one part per million; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum

Precambrian aquifers

Nitrite, as N 18 17 -- -- <0.01 0.01

Nitrite plus nitrate, as N 40 8 1.6 0.7 <0.1 12

Ammonia, as N 0 -- -- -- -- --

Ammonia plus organic, as N 0 -- -- -- -- --

Phosphorus, as P 51 44 1

-- 1-- <0.04 0.12

Orthophosphate, as P 0 -- -- -- -- --

Deadwood aquifer

Nitrite, as N 5 5 -- -- <0.01 <0.01

Nitrite plus nitrate, as N 8 4 0.2 <0.1 <0.1 0.5

Ammonia, as N 2 0 0.025 0.025 0.02 0.03

Ammonia plus organic, as N 3 1 -- -- <0.2 0.6

Phosphorus, as P 7 5 -- -- <0.01 0.25

Orthophosphate, as P 1 1 -- -- <0.001 <0.001

Madison aquifer

Nitrite, as N 56 50 1-- 1-- <0.01 0.03

Nitrite plus nitrate, as N 74 14 0.4 0.2 <0.05 2.6

Ammonia, as N 31 12 0.2 0.01 <0.01 1.9

Ammonia plus organic, as N 36 23 0.4 0.1 0.05 5.0

Phosphorus, as P 59 42 0.01 <0.01 <0.01 0.22

Orthophosphate, as P 28 14 <0.01 <0.01 <0.01 0.02

Minnelusa aquifer

Nitrite, as N 61 49 1-- 1-- <0.01 0.05

Nitrite plus nitrate, as N 157 29 0.6 0.3 0.01 16

Ammonia, as N 22 6 0.04 0.02 <0.01 0.3

Ammonia plus organic, as N 28 16 0.2 0.2 <0.1 0.8

Phosphorus, as P 68 54 0.04 <0.01 <0.01 2.1

Orthophosphate, as P 19 11 <0.01 <0.01 <0.01 0.03

Minnekahta aquifer

Nitrite, as N 10 9 -- -- <0.01 0.01

Nitrite plus nitrate, as N 23 4 1.5 0.7 <0.1 9.5

Ammonia, as N 3 1 -- -- <0.02 0.07

Ammonia plus organic, as N 3 1 -- -- <0.2 0.2

Phosphorus, as P 4 3 -- -- <0.01 <0.04

Orthophosphate, as P 3 1 -- -- <0.01 0.03
Water-Quality Characteristics of Selected Aquifers 71

Inyan Kara aquifer

Nitrite, as N 41 31 0.06 <0.01 <0.01 1.0

Nitrite plus nitrate, as N 81 29 1.1 0.1 0.01 60

Ammonia, as N 17 2 0.5 0.25 <0.01 2.2

Ammonia plus organic, as N 18 1 0.8 0.5 <0.1 2.7

Phosphorus, as P 81 74 -- -- <0.01 0.03

Orthophosphate, as P 0 0 -- -- -- --

Spearfish aquifer

Nitrite, as N 3 3 -- -- <0.01 <0.01

Nitrite plus nitrate, as N 4 0 1.8 0.8 0.5 5.0

Ammonia, as N 0 -- -- -- -- --

Ammonia plus organic, as N 0 -- -- -- -- --

Phosphorus, as P 9 9 -- -- <0.04 <0.04

Orthophosphate, as P 0 -- -- -- -- --

Sundance aquifer

Nitrite, as N 3 0 0.02 0.02 0.02 0.02

Nitrite plus nitrate, as N 9 0 0.4 0.1 0.02 2.1

Ammonia, as N 3 0 0.2 0.03 0.02 0.5

Ammonia plus organic, as N 3 0 0.5 0.5 0.3 0.6

Phosphorus, as P 5 4 -- -- <0.01 <0.04

Orthophosphate, as P 0 -- -- -- -- --

Morrison aquifer

Nitrite, as N 2 2 -- -- <0.01 <0.01

Nitrite plus nitrate, as N 7 0 0.5 0.5 0.2 0.7

Ammonia, as N 0 -- -- -- -- --

Ammonia plus organic, as N 0 -- -- -- -- --

Phosphorus, as P 6 6 -- -- <0.04 <0.04

Orthophosphate, as P 0 -- -- -- -- --

Pierre aquifer

Nitrite, as N 0 -- -- -- -- --

Nitrite plus nitrate, as N 0 -- -- -- -- --

Ammonia, as N 0 -- -- -- -- --

Ammonia plus organic, as N 0 -- -- -- -- --

Phosphorus, as P 28 26 -- -- <0.04 0.10

Orthophosphate, as P 0 -- -- -- -- --

Table 6. Summary of concentrations of nutrients in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter. One 

milligram per liter is approximately equal to one part per million; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
72 Water-Quality Characteristics in the Black Hills Area, South Dakota

Graneros aquifer

Nitrite, as N 0 -- -- -- -- --

Nitrite plus nitrate, as N 0 -- -- -- -- --

Ammonia, as N 0 -- -- -- -- --

Ammonia plus organic, as N 0 -- -- -- -- --

Phosphorus, as P 10 10 -- -- <0.04 <0.04

Orthophosphate, as P 0 -- -- -- -- --

Newcastle aquifer

Nitrite, as N 4 4 -- -- <0.01 <0.01

Nitrite plus nitrate, as N 6 4 -- -- <0.1 <0.1

Ammonia, as N 1 0 -- -- 0.01 0.01

Ammonia plus organic, as N 1 1 -- -- <0.1 <0.1

Phosphorus, as P 1 0 -- -- 0.01 0.01

Orthophosphate, as P 0 -- -- -- -- --

Alluvial aquifers

Nitrite, as N 18 17 -- -- <0.01 0.01

Nitrite plus nitrate, as N 70 9 0.7 0.4 0.01 3.1

Ammonia, as N 14 5 0.01 <0.01 <0.01 0.02

Ammonia plus organic, as N 4 3 -- -- <0.2 0.2

Phosphorus, as P 33 29 1-- 1

-- <0.01 0.77

Orthophosphate, as P 23 13 <0.01 <0.01 <0.001 0.02

1

Boxplot for constituent is shown in figure 22, although percent of censored values is greater than 80 percent. Mean and median are not reported 

because they are unreliable.

Table 6. Summary of concentrations of nutrients in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter. One 

milligram per liter is approximately equal to one part per million; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Aquifers 73

Figure 22. Boxplots of concentrations of selected nutrients for selected aquifers.

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

1.4

0.2

0.4

0.6

0.8

1.0

1.2

1.4

DISSOLVED NITRITE, IN MILLIGRAMS PER LITER

18/17 5/5 56/50 61/49 10/9 41/31 3/3 3/0 2/2 0/0 0/0 4/4 18/17

0

20

5

10

15

DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

40/8 8/4 74/14 157/29 23/4 81/29 4/0 9/0 7/0 0/0 0/0 6/4 70/9

65

60

0

2.5

0.5

1.0

1.5

2.0

DISSOLVED AMMONIA,

IN MILLIGRAMS PER LITER

0/0 2/0 31/12 22/6 3/1 17/2 0/0 3/0 0/0 0/0 1/0 14/5 0/0

Major aquifers Minor aquifers
74 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 22. Boxplots of concentrations of selected nutrients for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

6

1

2

3

4

5

DISSOLVED AMMONIA PLUS ORGANIC,

IN MILLIGRAMS PER LITER 

0/0 3/1 36/23 28/16 3/1 18/1 0/0 3/0 0/0 0/0 0/0 1/1 4/3

0

0.2

0.4

0.6

0.8

DISSOLVED PHOSPHORUS, 

N MILLIGRAMS PER LITER

51/44 7/5 59/42 68/54 4/3 81/74 9/9 5/4 6/6 28/26 10/10 1/0 33/29

2.0

2.2

0

0.04

0.01

0.02

0.03

DISSOLVED ORTHOPHOSPHATE,

IN MILLIGRAMS PER LITER 

0/0 1/1 28/14 19/11 3/1 0/0 0/0 0/0 0/0 0/0 0/0 0/0 23/13

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 75

Figure 22. Boxplots of concentrations of selected nutrients for selected aquifers.--Continued

EXPLANATION

Highest detection limit

Maximum Contaminant Level (mandatory) (U.S. Environmental

 Protection Agency, 1994a)

Number of samples/Number of samples

 with concentrations below the laboratory

 reporting limit

114/15

25th percentile

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

Single sample

Trace Elements

Summary statistics for selected trace elements, 

including aluminum, arsenic, barium, boron, cadmium, 

chromium, cobalt, copper, iron, lead, lithium, manganese, mercury, molybdenum, nickel, selenium, silver, 

strontium, vanadium, and zinc, are presented in table 7. 

The significance of the various trace elements is 

described in table 1. Boxplots are presented in 

figure 23 for each of the trace elements. Some of the 

trace elements, such as aluminum, cadmium, chromium, copper, iron, lead, mercury, nickel, and zinc, are 

particularly susceptible to sampling/processing contamination. Because ultra-clean techniques were not 

used in sample collection, some of the results presented 

may reflect sample contamination.

In all aquifers considered in this report, strontium generally is higher in concentration than the other 

trace elements. Barium, boron, iron, manganese, 

lithium, and zinc concentrations also may be high in 

comparison to other trace elements. Concentrations 

and variability of many trace elements are small in the 

aquifers. Boron concentrations generally are much 

higher and have larger variability in the minor aquifers 

than in the major aquifers, with generally higher concentrations in the Inyan Kara aquifer than the other 

major aquifers. The Inyan Kara and Precambrian 

aquifers generally have lower barium concentrations 

and generally higher manganese concentrations than 

the other major aquifers. Lithium concentrations 

generally are much lower and have smaller variability 

in the Precambrian, Deadwood, Madison, Minnelusa, 

and Minnekahta aquifers than in the other aquifers. 

The Sundance aquifer generally has the highest selenium concentrations of all aquifers considered in this 

report. In general, strontium concentrations are lower 

and have smaller variability in the Precambrian, 

Deadwood, Madison, and Minnekahta aquifers than in 

the other aquifers. 

Precambrian Aquifers

Concentrations of several trace elements in 

samples collected from the Precambrian aquifers 

exceed various drinking water standards. One of 51 

samples exceeds the lower value of the SMCL range of 

50 to 200 μg/L for aluminum. Of the 52 samples 

analyzed for arsenic concentrations, one sample 

exceeds the current MCL of 50 μg/L for arsenic, and 

four samples exceed the proposed MCL of 10 μg/L for 

arsenic. About 15 percent of the samples (14 of 91 

samples) exceed the SMCL of 300 μg/L for iron, and 

35 percent of the samples (33 of 93 samples) exceed 

the SMCL of 50 μg/L for manganese.

Of all samples collected from the major aquifers, 

samples from the Precambrian aquifers have the 

highest mean manganese concentration and the highest 

median zinc concentration. Samples from the Precambrian aquifers also have the lowest mean and median 

concentrations of boron (equal to the median concentration of the Madison aquifer) and strontium and the 

lowest median iron concentration.
76 Water-Quality Characteristics in the Black Hills Area, South Dakota

Table 7. Summary of concentrations of trace elements in ground water

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum

Precambrian aquifers

Aluminum 51 39 6.5 3.7 <10 54

Arsenic 52 24 4.2 1.2 <0.5 103

Barium 52 1 33 27 <2.0 120

Boron 60 0 29 20 6.0 227

Cadmium 1 0 -- -- 3.5 3.5

Chromium 52 45 1-- 1

-- <4.0 13

Cobalt 51 37 1.5 1.0 <2.0 7.0

Copper 58 37 30 0.5 <2.0 517

Iron 91 33 267 11 <10 11,000

Lead 1 0 -- -- 10 10

Lithium 51 0 17 9.0 3.0 113

Manganese 93 31 136 10 <2.0 1,100

Mercury 0 -- -- -- -- --

Molybdenum 51 31 5.0 3.5 <4.0 22

Nickel 51 42 1-- 1

-- <4.0 17

Selenium 52 18 0.3 0.3 <0.2 0.7

Silver 52 37 1.4 1.1 <2.0 6.0

Strontium 51 0 170 140 11 619

Vanadium 51 37 4.1 2.0 <4.0 37

Zinc 58 0 168 67 4.0 3,236

Deadwood aquifer

Aluminum 6 4 -- -- <10 40

Arsenic 11 2 2.9 1.3 <1.0 11

Barium 17 0 234 100 14 1,500

Boron 9 0 67 25 11 290

Cadmium 4 3 -- -- <1.0 1.0

Chromium 6 4 -- -- 1.0 6.0

Cobalt 5 3 -- -- <2.0 7.8

Copper 10 6 20 1.7 <1.0 184

Iron 34 1 371 80 9.0 2,500

Lead 4 2 -- -- <1.0 2.0

Lithium 7 1 31 9.0 <2.0 140

Manganese 34 10 31 7.0 <1.0 340

Mercury 6 6 -- -- <0.1 <0.1

Molybdenum 7 4 6.1 3.1 <1.0 16.0

Nickel 4 3 -- -- <4.0 6.0

Selenium 10 5 0.4 0.2 <0.2 1.0

Silver 5 3 -- -- <1.0 3.0

Strontium 7 0 442 449 54 1,161

Vanadium 5 3 -- -- <4.0 27

Zinc 11 3 279 40 <3.0 2,430
Water-Quality Characteristics of Selected Aquifers 77

Madison aquifer

Aluminum 26 16 15 4.9 <10 100

Arsenic 60 7 3.6 3.0 <0.5 27

Barium 37 0 85 51 11 300

Boron 63 5 59 20 9.0 588

Cadmium 38 35 -- -- <0.1 10

Chromium 33 32 -- -- <1.0 6.0

Cobalt 32 22 1.8 1.3 <2.0 7.0

Copper 65 46 4.5 0.6 <1.0 134

Iron 101 29 195 20 <3.0 7,400

Lead 34 24 2.2 0.9 <1.0 29

Lithium 41 9 25 7.0 2.0 236

Manganese 99 47 31 2.7 0.6 710

Mercury 35 30 1-- 1

-- <0.1 0.3

Molybdenum 39 21 5.7 2.5 <1.0 34

Nickel 19 17 -- -- <4.0 10

Selenium 55 14 1.9 0.7 <0.2 18

Silver 48 42 1-- 1

-- <0.2 4.0

Strontium 45 0 501 225 60 3,300

Vanadium 37 26 2.7 2.0 0.7 12

Zinc 72 15 100 13 2.0 1,407

Minnelusa aquifer

Aluminum 41 31 23 0.7 <10 400

Arsenic 67 11 4.9 2.3 <0.5 30

Barium 57 0 103 68 2.0 400

Boron 101 3 51 30 6.0 340

Cadmium 28 26 -- -- <1.0 3.0

Chromium 48 37 2.5 1.3 <1.0 10

Cobalt 46 28 2.0 1.5 <2.0 8.0

Copper 85 56 15 1.1 <1.0 670

Iron 197 59 199 20 <0.1 3,700

Lead 21 17 1-- 1

-- <1.0 30

Lithium 57 1 21 10 4.0 160

Manganese 166 83 70 5.1 <1.0 7,200

Mercury 25 24 -- -- <0.1 0.2

Molybdenum 55 31 8.2 3.0 <1.0 102

Nickel 37 24 3.4 2.8 <2.0 10

Selenium 67 9 1.4 0.5 <0.2 12

Silver 51 36 1.5 1.3 <1.0 5.0

Strontium 57 0 1,547 409 62 11,000

Vanadium 53 18 6.9 5.0 0.7 30

Zinc 96 11 272 33 <3.0 10,000

Table 7. Summary of concentrations of trace elements in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
78 Water-Quality Characteristics in the Black Hills Area, South Dakota

Minnekahta aquifer

Aluminum 1 1 -- -- <10 <10

Arsenic 4 1 2.4 2.1 <1.0 5.0

Barium 4 0 148 125 42 300

Boron 7 0 118 40 19 620

Cadmium 3 3 -- -- <1.0 <1.0

Chromium 4 3 -- -- 1.0 <5.0

Cobalt 3 3 -- -- <2.0 <3.0

Copper 10 3 16 15 <2.0 30

Iron 21 9 57 12 0.1 320

Lead 3 1 -- -- 1.0 10

Lithium 3 0 8.8 10 5.0 11

Manganese 18 13 13 4.3 <0.02 120

Mercury 3 3 -- -- <0.1 <0.1

Molybdenum 3 1 -- -- 6.0 13

Nickel 1 1 -- -- <4.0 <4.0

Selenium 4 0 1.5 1.5 0.3 2.6

Silver 3 2 -- -- <1.0 2.0

Strontium 3 0 626 510 268 1,100

Vanadium 3 2 -- -- <6.0 43

Zinc 10 1 96 61 3.1 360

Inyan Kara aquifer

Aluminum 65 45 12 5.1 <10 140

Arsenic 90 28 1.1 0.8 <0.5 17

Barium 75 2 12 5.0 <2.0 126

Boron 92 0 125 80 30 670

Cadmium 13 12 -- -- <2.0 <2.0

Chromium 62 56 -- -- <4.0 5.0

Cobalt 62 38 2.0 1.2 <2.0 19

Copper 84 66 4.7 0.2 <2.0 210

Iron 145 20 460 33 1.2 3,600

Lead 1 0 -- -- 15 15

Lithium 78 0 103 79 19 455

Manganese 131 21 92 43 <2.0 1,424

Mercury 27 23 1-- 1

-- <0.1 1.9

Molybdenum 78 47 5.2 4.0 <1.0 21

Nickel 62 52 1

-- 1-- <4.0 9.0

Selenium 89 16 1.6 0.6 <0.2 23

Silver 62 53 1-- 1

-- <2.0 4.0

Strontium 79 0 2,133 1,500 31 8,460

Vanadium 79 56 2.2 1.3 <1.0 19

Zinc 90 16 78 20 <3.0 1,803

Table 7. Summary of concentrations of trace elements in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Aquifers 79

Spearfish aquifer

Aluminum 9 5 17 8.4 <10 62

Arsenic 9 5 0.7 0.4 <0.5 2.4

Barium 9 0 35 15 3.0 132

Boron 9 0 170 114 13 517

Cadmium 0 -- -- -- -- --

Chromium 9 7 -- -- <4.0 4.0

Cobalt 9 5 1.8 1.1 <2.0 5.0

Copper 10 7 9.8 0.02 <2.0 90

Iron 13 5 21 13 <10 80

Lead 0 -- -- -- -- --

Lithium 9 0 55 24 5.0 267

Manganese 12 3 17 7.0 <2.0 91

Mercury 0 -- -- -- -- --

Molybdenum 9 2 8.5 7.0 <4.0 15

Nickel 9 6 3.1 2.4 <4.0 7.0

Selenium 9 2 0.5 0.3 <0.2 1.8

Silver 9 6 1.7 1.5 <2.0 3.0

Strontium 9 0 3,313 2,280 78 9,802

Vanadium 9 5 6.9 0.9 <4.0 45

Zinc 10 0 716 271 6.0 3,096

Sundance aquifer

Aluminum 3 1 -- -- <10 30

Arsenic 8 4 1.8 1.5 <0.5 5.0

Barium 3 0 7.7 8.0 5.0 10

Boron 7 0 347 378 60 674

Cadmium 1 1 -- -- <2.0 <2.0

Chromium 2 1 -- -- <4.0 10

Cobalt 2 1 -- -- <2.0 4.0

Copper 4 1 2.5 2.5 <2.0 4.0

Iron 7 0 1,101 56 20 6,600

Lead 0 -- -- -- -- --

Lithium 5 0 189 180 70 313

Manganese 7 2 29 18 <1.0 80

Mercury 6 5 -- -- <0.1 0.8

Molybdenum 5 2 3.9 3.4 2.0 7.0

Nickel 2 2 -- -- <4.0 <4.0

Selenium 8 1 55 1.5 0.5 360

Silver 2 1 -- -- <2.0 6.0

Strontium 5 0 5,473 5,900 2,200 7,518

Vanadium 4 2 -- -- <1.0 11

Zinc 5 0 41 40 10 90

Table 7. Summary of concentrations of trace elements in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
80 Water-Quality Characteristics in the Black Hills Area, South Dakota

Morrison aquifer

Aluminum 6 2 22 13 <10 61

Arsenic 6 3 0.9 0.4 <0.5 2.7

Barium 6 0 13 6.0 4.0 48

Boron 6 0 189 126 22 550

Cadmium 0 -- -- -- -- --

Chromium 6 5 -- -- <4.0 4.0

Cobalt 6 4 -- -- <2.0 6.0

Copper 6 3 3.5 3.4 <2.0 6.0

Iron 11 1 191 42 <10 1,700

Lead 0 -- -- -- -- --

Lithium 6 0 123 58 10 454

Manganese 9 2 7.3 5.0 2.0 30

Mercury 0 -- -- -- -- --

Molybdenum 6 3 7.1 4.0 <4.0 24

Nickel 6 5 -- -- <4.0 7.0

Selenium 6 1 0.3 0.4 <0.2 0.5

Silver 6 4 -- -- <2.0 3.0

Strontium 6 0 4,113 3,534 58 9,598

Vanadium 6 3 9.7 2.9 <4.0 44

Zinc 6 0 76 48 4.0 211

Pierre aquifer

Aluminum 28 16 22 11 <10 75

Arsenic 28 23 1-- 1-- <0.5 1.3

Barium 28 0 22 15 3.0 86

Boron 28 0 425 301 26 1,833

Cadmium 0 -- -- -- -- --

Chromium 28 24 1-- 1

-- <4.0 9.0

Cobalt 28 18 1.8 1.1 <2.0 7.0

Copper 28 17 4.5 0.7 <2.0 74

Iron 28 7 21 19 <10 44

Lead 0 -- -- -- -- --

Lithium 28 0 156 97 10 596

Manganese 28 5 250 6.5 <2.0 2,699

Mercury 0 -- -- -- -- --

Molybdenum 28 15 5.5 3.6 <4.0 16

Nickel 28 25 1

-- 1-- <4.0 10

Selenium 28 3 0.7 0.6 <0.2 3.0

Silver 28 17 1.9 1.5 <2.0 5.0

Strontium 28 0 2,579 2,227 2,78 8,768

Vanadium 28 22 2.7 1.8 <4.0 13

Zinc 28 3 117 34 <4.0 999

Table 7. Summary of concentrations of trace elements in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Aquifers 81

Graneros aquifer

Aluminum 10 7 11 8.6 <10 25

Arsenic 10 7 0.4 0.4 <0.5 0.6

Barium 10 1 19 11 <2.0 80

Boron 10 0 304 159 69 927

Cadmium 0 -- -- -- -- --

Chromium 10 9 -- -- <4.0 7.0

Cobalt 10 4 2.6 2.0 <2.0 7.0

Copper 10 6 2.2 1.4 <2.0 6.0

Iron 10 4 15 11 <10 37

Lead 0 -- -- -- -- --

Lithium 10 0 86 82 16 154

Manganese 10 1 32 5.0 <2.0 149

Mercury 0 -- -- -- -- --

Molybdenum 10 3 5.4 5.0 <4.0 12

Nickel 10 5 3.6 3.6 <4.0 6.0

Selenium 10 1 0.4 0.4 <0.2 0.7

Silver 10 6 1.9 1.2 <2.0 6.0

Strontium 10 0 2,250 2,007 167 4,776

Vanadium 10 6 5.4 2.9 <4.0 16

Zinc 10 0 104 70 12 354

Newcastle aquifer

Aluminum 0 -- -- -- -- --

Arsenic 2 2 -- -- <1.0 <1.0

Barium 1 0 -- -- 9.0 9.0

Boron 4 0 205 75 0.1 670

Cadmium 1 1 -- -- <2.0 <2.0

Chromium 0 -- -- -- -- --

Cobalt 0 -- -- -- -- --

Copper 0 -- -- -- -- --

Iron 4 0 1,985 1,095 50 5,700

Lead 0 -- -- -- -- --

Lithium 1 0 -- -- 50 50

Manganese 5 1 58 50 <30 120

Mercury 2 1 -- -- <0.1 0.4

Molybdenum 1 1 -- -- <10 <10

Nickel 0 -- -- -- -- --

Selenium 2 0 1.5 1.5 1.0 2.0

Silver 0 -- -- -- -- --

Strontium 1 0 -- -- 1,900 1,900

Vanadium 1 0 -- -- 3.0 3.0

Zinc 1 0 -- -- 770 770

Table 7. Summary of concentrations of trace elements in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
82 Water-Quality Characteristics in the Black Hills Area, South Dakota

Alluvial aquifers

Aluminum 29 19 11 5.0 <10 61

Arsenic 33 17 1.4 0.5 <0.5 7.8

Barium 30 0 36 11 4.0 397

Boron 39 0 243 130 0.3 1,476

Cadmium 1 1 -- -- <1.0 <1.0

Chromium 30 26 1-- 1

-- <4.0 9.0

Cobalt 30 18 1.7 1.5 <2.0 4.0

Copper 36 19 7.4 1.1 <2.0 63

Iron 97 22 156 20 <3.0 4,800

Lead 1 1 -- -- <10 <10

Lithium 30 0 112 75 9.0 491

Manganese 82 32 81 5.1 <1.0 2,100

Mercury 0 -- -- -- -- --

Molybdenum 30 11 7.0 5.0 <4.0 37

Nickel 29 22 2.9 1.9 <4.0 11

Selenium 33 7 0.6 0.5 <0.2 2.0

Silver 30 24 1-- 1

-- <1.0 5.0

Strontium 30 0 2,390 1,505 91 8,864

Vanadium 30 20 3.8 2.2 <4.0 15

Zinc 36 1 73 19 <4.0 480

1

Boxplot for constituent is shown in figure 23, although percent of censored values is greater than 80 percent. Mean and median are not reported 

because they are unreliable.

Table 7. Summary of concentrations of trace elements in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Aquifers 83

Figure 23. Boxplots of concentrations of selected trace elements for selected aquifers.

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

500

100

200

300

400

DISSOLVED ALUMINUM,

IN MICROGRAMS PER LITER

51/39 6/4 26/16 41/31 1/1 65/45 9/5 3/1 6/2 28/16 10/7 0/0 29/19

0

120

20

40

60

80

100

DISSOLVED ARSENIC,

IN MICROGRAMS PER LITER

52/24 11/2 60/7 67/11 4/1 90/28 9/5 8/4 6/3 28/23 10/7 2/2 33/17

0

200

400

DISSOLVED BARIUM,

IN MICROGRAMS PER LITER

52/1 17/0 37/0 57/0 4/0 75/2 9/0 3/0 6/0 28/0 10/1 1/0 30/0

1,200

1,600

1,400

Major aquifers Minor aquifers
84 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 23. Boxplots of concentrations of selected trace elements for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

2,000

500

1,000

1,500

DISSOLVED BORON,

IN MICROGRAMS PER LITER

60/0 9/0 63/5 101/3 7/0 92/0 9/0 7/0 6/0 10/0 4/0 39/0 28/0

0

12

2

4

6

8

10

DISSOLVED CADMIUM,

IN MICROGRAMS PER LITER

1/0 4/3 38/35 28/26 3/3 13/12 0/0 1/1 0/0 0/0 0/0 1/1 1/1

0

14

2

4

6

8

10

12

DISSOLVED CHROMIUM,

IN MICROGRAMS PER LITER

52/45 6/4 33/32 48/37 4/3 62/56 9/7 2/1 6/5 28/24 10/9 0/0 30/26

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 85

Figure 23. Boxplots of concentrations of selected trace elements for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

20

5

10

15

DISSOLVED COBALT,

IN MICROGRAMS PER LITER

51/37 5/3 32/22 46/28 3/3 62/38 9/5 2/1 6/4 28/18 10/4 0/0 30/18

0

800

200

400

600

DISSOLVED COPPER,

IN MICROGRAMS PER LITER

58/37 10/6 85/56 10/3 84/66 10/7 4/1 6/3 28/17 10/6 0/0 36/19 65/46

0

12,000

2,000

4,000

6,000

8,000

10,000

DISSOLVED IRON,

IN MICROGRAMS PER LITER

91/33 34/1 101/29 197/59 21/9 145/20 13/5 7/0 11/1 28/7 10/4 4/0 97/22

Major aquifers Minor aquifers
86 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 23. Boxplots of concentrations of selected trace elements for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

40

10

20

30

DISSOLVED LEAD,

IN MICROGRAMS PER LITER

1/0 4/2 34/24 21/17 3/1 1/0 0/0 0/0 0/0 0/0 0/0 1/1 0/0

0

800

200

400

600

DISSOLVED LITHIUM,

IN MICROGRAMS PER LITER

51/0 7/1 41/9 57/1 3/0 78/0 9/0 5/0 6/0 28/0 10/0 1/0 30/0

0

3,000

1,000

2,000

DISSOLVED MANGANESE,

IN MICROGRAMS PER LITER

93/31 34/10 99/47 166/83 18/13 131/21 12/3 7/2 9/2 28/5 10/1 5/1 82/32 8,000

7,000

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 87

Figure 23. Boxplots of concentrations of selected trace elements for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

2.2

0.5

1.0

1.5

2.0

DISSOLVED MERCURY,

IN MICROGRAMS PER LITER

0/0 6/6 35/30 25/24 3/3 27/23 0/0 6/5 0/0 2/1 0/0 0/0 0/0

0

120

20

40

60

80

100

DISSOLVED MOLYBDENUM,

IN MICROGRAMS PER LITER

51/31 7/4 39/21 55/31 3/1 78/47 9/2 5/2 6/3 28/15 10/3 1/1 30/11

0

20

5

10

15

DISSOLVED NICKEL,

IN MICROGRAMS PER LITER

51/42 4/3 19/17 37/24 1/1 62/52 9/6 2/2 6/5 28/25 10/5 0/0 29/22

Major aquifers Minor aquifers
88 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 23. Boxplots of concentrations of selected trace elements for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

60

20

40

DISSOLVED SELENIUM,

IN MICROGRAMS PER LITER

52/18 10/5 55/14 67/9 4/0 89/16 9/2 8/1 6/1 28/3 10/1 2/0 33/7 380

360

0

8

2

4

6

DISSOLVED SILVER,

IN MICROGRAMS PER LITER

52/37 5/3 48/42 51/36 3/2 62/53 9/6 2/1 6/4 28/17 10/6 0/0 30/24

0

12,000

2,000

4,000

6,000

8,000

10,000

DISSOLVED STRONTIUM,

IN MICROGRAMS PER LITER

51/0 7/0 45/0 57/0 3/0 79/0 9/0 5/0 6/0 28/0 10/0 1/0 30/0

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 89

Figure 23. Boxplots of concentrations of selected trace elements for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

EXPLANATION

Secondary Maximum Contaminant Level

 (recommended) (U.S. Environmental

 Protection Agency, 1996)

Highest detection limit

Maximum Contaminant Level (mandatory)

 (U.S. Environmental Protection Agency, 1996)

Proposed Maximum Contaminant Level

 (U.S. Environmental Protection Agency, 2000a)

Action level (U.S. Environmental

 Protection Agency, 1991)

0

50

10

20

30

40

DISSOLVED VANADIUM,

IN MICROGRAMS PER LITER

51/37 5/3 37/26 53/18 3/2 79/56 9/5 4/2 6/3 28/22 10/6 1/0 30/20

0

5,000

1,000

2,000

3,000

4,000

DISSOLVED ZINC,

IN MICROGRAMS PER LITER

11,000

10,000

58/0 11/3 72/15 96/11 10/1 90/16 10/0 5/0 6/0 28/3 10/0 1/0 36/1

Number of samples/Number of samples

 with concentrations below the laboratory

 reporting limit

114/15

25th percentile

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

Major aquifers Minor aquifers

Single sample
90 Water-Quality Characteristics in the Black Hills Area, South Dakota

Deadwood Aquifer

Samples collected from the Deadwood aquifer 

have the highest mean barium and zinc concentrations 

and the highest median iron concentration of samples 

collected from all the major aquifers. None of the trace 

element concentrations were found to vary with depth 

or geographic location.

No samples exceed the current MCL for arsenic; 

however, 1 of 11 samples exceeds the proposed MCL 

for arsenic. About 32 percent of the samples (11 of 34 

samples) exceed the SMCL for iron and about 

18 percent (6 of 34 samples) exceed the SMCL for 

manganese. 

Madison Aquifer

Of all the samples collected from the major aquifers, samples from the Madison aquifer have the lowest 

median concentrations of boron (equal to samples from 

the Precambrian aquifers), lithium, manganese, and 

zinc. Concentrations of aluminum, arsenic, manganese, and selenium generally increase with increasing 

well depth (fig. 24). The highest lithium concentrations generally occur in the southern Black Hills.

Concentrations of several trace elements in samples collected from the Madison aquifer exceed various 

drinking-water standards. Two of 26 samples exceed 

the lower value of the SMCL range for aluminum. No 

samples exceed the current MCL for arsenic; however, 

3 of 60 samples exceed the proposed MCL for arsenic. 

Two of 38 samples exceed the MCL for cadmium. 

About 10 percent of the samples exceed the SMCL’s 

for iron (11 of 101 samples) and manganese (10 of 99 

samples); almost all of the high iron concentrations are 

from wells in the southern Black Hills. One of 34 

samples exceeds the action level of 15 μg/L for lead.

Minnelusa Aquifer

In the Minnelusa aquifer, concentrations of selenium and strontium generally increase with increasing 

well depth associated with increasing distance from the 

outcrop (fig. 24). Concentrations of several other trace 

elements vary with geographic location. Generally, the 

highest aluminum concentrations occur in the northern 

and eastern Black Hills, the highest arsenic concentrations occur in the southern and eastern Black Hills, and 

the highest lithium concentrations occur in the southern 

Black Hills.

Concentrations of several trace elements in 

samples collected from the Minnelusa aquifer exceed 

various drinking-water standards. About 7 percent of 

the samples (3 of 41 samples) exceed the lower value 

of the SMCL range for aluminum; all are from wells 

located in the northern or eastern Black Hills. No 

samples exceed the current MCL for arsenic; however, 

9 of 67 samples exceed the proposed MCL for arsenic. 

About 12 percent of the samples (24 of 197 samples) 

equal or exceed the SMCL for iron. One of 21 samples 

exceeds the action level for lead. Over 10 percent of 

the samples (21 of 166 samples) exceed the SMCL for 

manganese; all are from wells located in the northern or 

eastern Black Hills. One of 96 samples exceeds the 

SMCL of 5,000 μg/L for zinc.

Minnekahta Aquifer

Samples collected from the Minnekahta aquifer 

have the highest median barium concentration of 

samples collected from the major aquifers. Samples 

from the Minnekahta aquifer have the lowest mean 

iron, lithium, and manganese concentrations of the 

major aquifers.

Few samples from the Minnekahta aquifer 

exceed any of the drinking water standards. One of 21 

samples exceeds the SMCL for iron, and 1 of 18 

samples exceeds the SMCL for manganese.

Inyan Kara Aquifer

Samples from the Inyan Kara aquifer have the 

highest mean and median boron, lithium, and strontium 

concentrations, the highest mean iron concentration, 

and the highest median manganese concentration of 

samples from all the major aquifers. Samples from the 

Inyan Kara aquifer have the lowest mean and median 

barium concentration and the lowest mean zinc 

concentration of samples from all the major aquifers.

Relations between various trace element concentrations and well depth in the Inyan Kara aquifer are not 

apparent; however, a few trace elements vary with geographic location. Generally, the highest lithium, strontium, and zinc concentrations are from wells located in 

the southern Black Hills, and the highest iron concentrations are from wells in the northern Black Hills.

Of samples collected from the Inyan Kara 

aquifer, 4 of 65 samples exceed the lower value of the 

SMCL range for aluminum. About 32 percent of the 

samples (47 of 145 samples) equal or exceed the 

SMCL for iron; almost all of these samples are from the 

northern Black Hills. The source of the undesirable 

iron concentrations probably is the oxidation and dissolution of iron minerals in the rock (Kyllonen and Peter, 

1987). The only sample analyzed for lead has a concentration equal to the action level for lead. About 
Water-Quality Characteristics of Selected Aquifers 91

Figure 24. Selected relations between trace elements and well depth for selected aquifers.

WELL DEPTH, IN FEET

MADISON AQUIFER

WELL DEPTH, IN FEET

0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

0

90

80

70

60

50

40

30

20

10

100

110

120

DISSOLVED ALUMINUM,

IN MICROGRAMS PER LITER

R2 = 0.7908

0

28

2

4

6

8

10

12

14

16

20

18

22

24

26

DISSOLVED ARSENIC,

IN MICROGRAMS PER LITER

R2 = 0.1207

0

50

100

150

200

250

300

350

400

450

500

550

600

650

700

750

DISSOLVED MANGANESE,

IN MICROGRAMS PER LITER

R2 = 0.3416

0

2

14

12

10

8

6

4

16

18

20

DISSOLVED SELENIUM,

IN MICROGRAMS PER LITER

R2 = 0.1031

MINNELUSA AQUIFER

WELL DEPTH, IN FEET

DISSOLVED SELENIUM,

IN MICROGRAMS PER LITER

DISSOLVED STONTIUM,

IN THOUSAND MICROGRAMS PER LITER

0 4,500 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

WELL DEPTH, IN FEET

0 4,500 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

0

12

1

2

3

4

5

6

7

8

10

9

11 R2 = 0.2660

12

0

1

2

3

4

5

6

7

8

9

10

11 R2 = 0.1919
92 Water-Quality Characteristics in the Black Hills Area, South Dakota

50 percent of the samples (63 of 131 samples) exceed 

the SMCL for manganese. No samples exceed the 

current MCL for arsenic; however, 1 of 90 samples 

exceeds the proposed MCL for arsenic.

Minor Aquifers

Although few samples from the minor aquifers, 

with the exception of alluvial aquifers, were analyzed 

for trace elements, concentrations in samples from each 

minor aquifer exceed various SMCL’s and MCL’s. In 

the Spearfish aquifer, 1 of 9 samples exceeds the lower 

value of the SMCL range for aluminum, and 1 of 12 

samples exceeds the SMCL for manganese. In the 

Sundance aquifer, 2 of 7 samples exceed the SMCL’s 

for iron and manganese, and 2 of 8 samples exceed the 

MCL of 50 μg/L for selenium. In the Morrison aquifer, 

1 of 6 samples exceeds the lower value of the SMCL 

range for aluminum, and 1 of 11 samples exceeds the 

SMCL for iron. In the Pierre aquifer, 4 of 28 samples 

exceed the lower value of the SMCL range for aluminum, and almost 30 percent of the samples (8 of 28 

samples) exceed the SMCL for manganese. Thirty 

percent of the samples (3 of 10 samples) from the 

Graneros aquifer exceed the SMCL for manganese. In 

the Newcastle aquifer, 2 of 4 samples exceed the 

SMCL for iron, and 3 of 5 samples exceed the SMCL 

for manganese.

In alluvial aquifers, 2 of 29 samples exceed the 

lower value of the SMCL range for aluminum. About 

10 percent of the samples (8 of 97 samples) exceed the 

SMCL for iron, and about 15 percent (12 of 82 

samples) exceed the SMCL for manganese. Almost all 

of the samples from alluvial aquifers that exceed 

drinking-water standards are located downgradient 

from the central core of the Black Hills.

Radionuclides

Radionuclides are unstable isotopes and have a 

certain probability of decay (Clark and Fritz, 1997). 

Radionuclides exist throughout the environment. Most 

occur naturally like uranium, thorium, radium, and 

radon, while others are mostly or entirely manufactured 

like technetium, plutonium, neptunium, and americium 

(Langmuir, 1997). More than 1,700 radionuclides have 

been identified (Clark and Fritz, 1997).

Radioactive decay series consist of a succession 

of radionuclides each with different decay rates. In 

each decay series, the original elements and each 

successive “daughter” product disintegrate, forming 

radionuclides until a stable lead isotope is formed. The 

decay rate usually is expressed as a half-life, which is 

the length of time required for one-half the quantity 

present to disintegrate. Uranium (238U and 235U) and 

thorium are the original elements in the three natural 

decay series (Wanty and Nordstrom, 1993) and give 

rise to most of the naturally occurring radioactivity in 

water (Hem, 1985). 

Uranium concentrations between 0.1 and 

10 μg/L are common in most natural waters and concentrations greater than 1,000 μg/L can occur in water 

associated with uranium-ore deposits (Hem, 1985). 

Concentrations of radium in natural water generally are 

less than 1 pCi/L. Thorium probably is more abundant 

than uranium in most rocks, but is less soluble, so 

thorium generally has lower concentrations in water.

Radioactivity is the release of energy and energetic particles by changes occurring within atomic or 

nuclear structures (Hem, 1985). Alpha, beta, and 

gamma radiation are types of radiation that commonly 

are measured in ground water. Radionuclide analyses 

can be expressed in terms of disintegrations per unit 

time (typically in units of picocuries per liter) or in 

mass units (typically in units of micrograms per liter).

Summary statistics for selected radionuclides, 

including alpha radioactivity as thorium-230, gross 

alpha as uranium, gross beta as cesium-138 and as 

strontium/yttrium-90, radium-226, radium-228, radon222, thorium, tritium, and uranium are presented in 

table 8. The significance of the various radionuclides 

is described in table 1. Boxplots are presented in 

figure 25 for each of the radionuclides. 

The drinking-water standard for gross alphaparticle activity given in table 1 cannot be compared 

directly to any of the gross alpha concentrations used in 

this study. The analyses for alpha radioactivity 

reported by the USGS excludes radon, but not uranium, 

as required by the drinking-water standard. Therefore, 

samples with an alpha radioactivity greater than 

15 pCi/L (picocuries per liter) may exceed the 

drinking-water standard, but this cannot be known 

without knowing the contribution of uranium to gross 

alpha. According to Garold Carlson (U.S. Environmental Protection Agency, written commun., 1999), 

the uranium contribution can be estimated by multiplying the uranium concentration in micrograms per 

liter by 0.7. This value then can be subtracted from the 

alpha radioactivity determined by the USGS and the 

resulting concentration compared to the drinking-water 

standard. This conversion was not performed for the 

statistics presented in table 8, but was performed 

before comparing gross alpha concentrations to the 

drinking-water standard.
Water-Quality Characteristics of Selected Aquifers 93

 Table 8. Summary of concentrations of radionuclides in ground water

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in picocuries per liter except as 

indicated. One microgram per liter (μg/L) is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum

Precambrian aquifers

Alpha radioactivity as thorium-230 0 -- -- -- -- --

Gross alpha as uranium-natural 0 -- -- -- -- --

Gross alpha as uranium-natural (μg/L) 0 -- -- -- -- --

Gross beta as cesium-137 0 -- -- -- -- --

Gross beta as strontium/yttrium-90 0 -- -- -- -- --

Radium-226 0 -- -- -- -- --

Radium-228 0 -- -- -- -- --

Radon-222 0 -- -- -- -- --

Thorium (μg/L) 51 31 5.9 4.1 <5.0 23

Tritium 0 -- -- -- -- --

Uranium (μg/L) 51 7 2.3 1.1 <0.2 10

Deadwood aquifer

Alpha radioactivity as thorium-230 1 0 -- -- 3.7 3.7

Gross alpha as uranium-natural 2 0 56 56 16 95

Gross alpha as uranium-natural (μg/L) 27 4 26 5.8 <0.4 180

Gross beta as cesium-137 28 2 8.7 6.2 2.6 34

Gross beta as strontium/yttrium-90 27 2 7.0 4.5 2.0 33

Radium-226 26 1 6.0 0.7 <0.1 66

Radium-228 23 17 0.9 0.9 <1.0 1.8

Radon-222 16 1 1,971 1,200 <80 6,600

Thorium (μg/L) 4 3 -- -- <5 10

Tritium 1 0 -- -- 139 139

Uranium (μg/L) 29 12 2.0 1.3 0.7 9.7

Madison aquifer

Alpha radioactivity as thorium-230 16 3 4.6 4.1 1.1 16

Gross alpha as uranium-natural 8 1 7.6 7.4 2.2 14

Gross alpha as uranium-natural (μg/L) 30 1 7.7 6.2 1.7 21

Gross beta as cesium-137 36 3 5.3 4.4 2.5 19

Gross beta as strontium/yttrium-90 29 0 4.0 3.3 2.0 13

Radium-226 12 1 1.2 1.0 <0.1 3.0

Radium-228 8 8 -- -- <1.0 <1.0

Radon-222 12 2 186 190 <80 300

Thorium (μg/L) 18 13 7.4 5.5 <5.0 22

Tritium 27 10 29 6.0 <1.0 105

Uranium (μg/L) 45 0 3.8 2.3 0.1 39
94 Water-Quality Characteristics in the Black Hills Area, South Dakota

Minnelusa aquifer

Alpha radioactivity as thorium-230 11 2 19 7.1 <3.0 100

Gross alpha as uranium-natural 10 3 7.0 4.8 <3.3 19

Gross alpha as uranium-natural (μg/L) 29 4 16 7.8 4.2 140

Gross beta as cesium-137 31 5 6.1 4.4 2.0 21

Gross beta as strontium/yttrium-90 27 4 4.9 3.8 1.9 16

Radium-226 17 0 3.1 0.4 0.1 45

Radium-228 5 5 -- -- <1.0 <1.0

Radon-222 5 1 162 170 <80 280

Thorium (μg/L) 35 17 8.8 5.1 <5.0 33

Tritium 18 8 15 1.5 <1.0 100

Uranium (μg/L) 56 0 4.2 3.4 0.2 13

Minnekahta aquifer

Alpha radioactivity as thorium-230 2 0 4.4 4.4 2.1 6.7

Gross alpha as uranium-natural 0 -- -- -- -- --

Gross alpha as uranium-natural (μg/L) 2 0 5.1 5.1 3.0 7.2

Gross beta as cesium-137 3 1 -- -- <0.6 5.8

Gross beta as strontium/yttrium-90 2 1 -- -- <0.6 4.3

Radium-226 2 0 0.3 0.3 0.1 0.4

Radium-228 0 -- -- -- -- --

Radon-222 0 -- -- -- -- --

Thorium (μg/L) 1 1 -- -- <5.0 <5.0

Tritium 2 0 52 52 24 79

Uranium (μg/L) 4 0 3.5 2.9 1.3 7.1

Inyan Kara aquifer

Alpha radioactivity as thorium-230 0 0 -- -- -- --

Gross alpha as uranium-natural 17 5 25 9.5 5.6 150

Gross alpha as uranium-natural (μg/L) 32 10 42 17 8.3 270

Gross beta as cesium-137 28 5 14 11 4.3 43

Gross beta as strontium/yttrium-90 28 5 13 11 3.9 39

Radium-226 34 0 4.1 1.4 0.2 43

Radium-228 3 3 -- -- <2.0 <3.0

Radon-222 0 -- -- -- -- --

Thorium (μg/L) 65 37 6.3 4.5 <5.0 36

Tritium 2 2 -- -- <3.0 <3.0

Uranium (μg/L) 77 9 7.7 2.1 0.1 109

Table 8. Summary of concentrations of radionuclides in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in picocuries per liter except as 

indicated. One microgram per liter (μg/L) is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Aquifers 95

Spearfish aquifer

Alpha radioactivity as thorium-230 0 -- -- -- -- --

Gross alpha as uranium-natural 0 -- -- -- -- --

Gross alpha as uranium-natural (μg/L) 0 -- -- -- -- --

Gross beta as cesium-137 0 -- -- -- -- --

Gross beta as strontium/yttrium-90 0 -- -- -- -- --

Radium-226 0 -- -- -- -- --

Radium-228 0 -- -- -- -- --

Radon-222 0 -- -- -- -- --

Thorium (μg/L) 9 3 9.9 10 <5.0 17

Tritium 0 -- -- -- -- --

Uranium (μg/L) 9 0 8.2 4.4 0.6 46

Sundance aquifer

Alpha radioactivity as thorium-230 0 -- -- -- -- --

Gross alpha as uranium-natural 2 1 -- -- <20 75

Gross alpha as uranium-natural (μg/L) 5 3 -- -- <15 110

Gross beta as cesium-137 5 2 13 12 8.6 21

Gross beta as strontium/yttrium-90 5 2 12 11 7.5 19

Radium-226 6 0 0.9 0.4 0.1 3.4

Radium-228 0 -- -- -- -- --

Radon-222 0 -- -- -- -- --

Thorium (μg/L) 2 0 22 22 6.0 37

Tritium 0 -- -- -- -- --

Uranium (μg/L) 6 1 9.8 9.8 <0.1 19

Morrison aquifer

Alpha radioactivity as thorium-230 0 -- -- -- -- --

Gross alpha as uranium-natural 0 -- -- -- -- --

Gross alpha as uranium-natural (μg/L) 0 -- -- -- -- --

Gross beta as cesium-137 0 -- -- -- -- --

Gross beta as strontium/yttrium-90 0 -- -- -- -- --

Radium-226 0 -- -- -- -- --

Radium-228 0 -- -- -- -- --

Radon-222 0 -- -- -- -- --

Thorium (μg/L) 6 5 -- -- <5.0 9.0

Tritium 0 -- -- -- -- --

Uranium (μg/L) 6 1 19 11 <0.2 51

Table 8. Summary of concentrations of radionuclides in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in picocuries per liter except as 

indicated. One microgram per liter (μg/L) is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
96 Water-Quality Characteristics in the Black Hills Area, South Dakota

Pierre aquifer

Alpha radioactivity as thorium-230 0 -- -- -- -- --

Gross alpha as uranium-natural 0 -- -- -- -- --

Gross alpha as uranium-natural (μg/L) 0 -- -- -- -- --

Gross beta as cesium-137 0 -- -- -- -- --

Gross beta as strontium/yttrium-90 0 -- -- -- -- --

Radium-226 0 -- -- -- -- --

Radium-228 0 -- -- -- -- --

Radon-222 0 -- -- -- -- --

Thorium (μg/L) 27 13 8.6 5.6 <5.0 24

Tritium 0 -- -- -- -- --

Uranium (μg/L) 28 1 15 13 <0.2 54

Graneros aquifer

Alpha radioactivity as thorium-230 0 -- -- -- -- --

Gross alpha as uranium-natural 0 -- -- -- -- --

Gross alpha as uranium-natural (μg/L) 0 -- -- -- -- --

Gross beta as cesium-137 0 -- -- -- -- --

Gross beta as strontium/yttrium-90 0 -- -- -- -- --

Radium-226 0 -- -- -- -- --

Radium-228 0 -- -- -- -- --

Radon-222 0 -- -- -- -- --

Thorium (μg/L) 10 4 11 9.5 <5.0 32

Tritium 0 -- -- -- -- --

Uranium (μg/L) 10 1 12 8.3 <0.2 40

Newcastle aquifer

Alpha radioactivity as thorium-230 0 -- -- -- -- --

Gross alpha as uranium-natural 1 1 -- -- <4.4 <4.4

Gross alpha as uranium-natural (μg/L) 2 2 -- -- <6.5 <27

Gross beta as cesium-137 2 0 12 12 9.6 15

Gross beta as strontium/yttrium-90 2 0 12 12 9.0 14

Radium-226 2 0 0.6 0.6 0.3 1.0

Radium-228 1 1 -- -- <3.0 <3.0

Radon-222 0 -- -- -- -- --

Thorium (μg/L) 0 -- -- -- -- --

Tritium 0 -- -- -- -- --

Uranium (μg/L) 1 0 -- -- 2.1 2.1

Table 8. Summary of concentrations of radionuclides in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in picocuries per liter except as 

indicated. One microgram per liter (μg/L) is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Aquifers 97

Alluvial aquifers

Alpha radioactivity as thorium-230 0 -- -- -- -- --

Gross alpha as uranium-natural 0 -- -- -- -- --

Gross alpha as uranium-natural (μg/L) 1 0 -- -- 2.0 2.0

Gross beta as cesium-137 1 0 -- -- 3.8 3.8

Gross beta as strontium/yttrium-90 1 0 -- -- 3.0 3.0

Radium-226 4 0 0.2 0.2 0.1 0.3

Radium-228 3 1 -- -- <1.0 4.0

Radon-222 4 1 477 280 <80 1,300

Thorium (μg/L) 29 13 7.5 5.0 <5.0 29

Tritium 0 -- -- -- -- --

Uranium (μg/L) 29 1 15 10 <0.2 62

Table 8. Summary of concentrations of radionuclides in ground water—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in picocuries per liter except as 

indicated. One microgram per liter (μg/L) is approximately equal to one part per billion; --, not analyzed or not determined; <, less than indicated detection 

limit]

Dissolved constituent Number of

samples

Number of

censored

samples

Mean Median Minimum Maximum
98 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 25. Boxplots of concentrations of selected radionuclides for selected aquifers.

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

120

20

40

60

80

100

ALPHA RADIOACTIVITY AS THORIUM-230,

IN PICOCURIES PER LITER

0/0 1/0 16/3 11/2 2/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0

0

300

50

100

150

200

250

GROSS ALPHA AS URANIUM-NATURAL,

IN MICROGRAMS PER LITER

0/0 27/4 30/1 29/4 2/0 32/10 0/0 5/3 0/0 0/0 0/0 2/2 1/0

160

0

20

40

60

80

100

120

140

GROSS ALPHA AS URANIUM-NATURAL,

IN PICOCURIES PER LITER

0/0 2/0 17/5 0/0 2/1 0/0 0/0 0/0 1/1 0/0 8/1 10/3 0/0

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 99

Figure 25. Boxplots of concentrations of selected radionuclides for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

46

10

20

30

40

GROSS BETA AS CESIUM-137,

IN PICOCURIES PER LITER

0/0 28/2 36/3 31/5 3/1 28/5 0/0 5/2 0/0 2/0 1/0 0/0 0/0

0

42

10

20

30

40

GROSS BETA AS STRONTIUM/YTTRIUM-90,

IN PICOCURIES PER LITER

0/0 27/2 29/0 27/4 2/1 28/5 0/0 0/0 5/2 1/0 0/0 0/0 2/0

0

80

20

40

60

RADIUM-226, IN PICOCURIES PER LITER

0/0 26/1 12/1 17/0 2/0 34/0 0/0 6/0 2/0 4/0 0/0 0/0 0/0

Major aquifers Minor aquifers
100 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 25. Boxplots of concentrations of selected radionuclides for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

0

5

1

2

3

4

RADIUM-228, IN PICOCURIES PER LITER

0/0 23/17 8/8 5/5 0/0 3/3 1/1 3/1 0/0 0/0 0/0 0/0 0/0

0

8,000

2,000

4,000

6,000

RADON-222, IN PICOCURIES PER LITER

0/0 16/1 12/2 5/1 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 4/0

0

40

10

20

30

THORIUM, IN MICROGRAMS PER LITER

51/31 4/3 18/13 35/17 1/1 65/37 9/3 2/0 6/5 27/13 10/4 0/0 29/13

Major aquifers Minor aquifers
Water-Quality Characteristics of Selected Aquifers 101

Figure 25. Boxplots of concentrations of selected radionuclides for selected aquifers.--Continued

AQUIFER

Precambrian

Deadwood

Madison

Minnelusa

Minnekahta

Inyan Kara

Spearfish

Sundance

Morrison

Pierre

Graneros Alluvial

Newcastle

EXPLANATION

Highest detection limit

Maximum Contaminant Level (mandatory) for

 uranium and for combined radium-226 and

 radium-228 (U.S. Environmental Protection

 Agency, 2000b)

Proposed Maximum Contaminant Level for

 States with an active indoor air program

Proposed Maximum Contaminant Level for

 States without an active indoor air program

0

160

20

40

60

80

100

120

140

TRITIUM, IN PICOCURIES PER LITER

0/0 1/0 27/10 18/8 2/0 2/2 0/0 0/0 0/0 0/0 0/0 0/0 0/0

0

120

20

40

60

80

100

URANIUM, IN MICROGRAMS PER LITER

51/7 29/12 45/0 56/0 4/0 77/9 9/0 6/1 6/1 28/1 10/1 1/0 29/1

Number of samples/Number of samples

 with concentrations below the laboratory

 reporting limit

77/9

25th percentile

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

Single sample

Major aquifers Minor aquifers
102 Water-Quality Characteristics in the Black Hills Area, South Dakota

Also, the drinking-water standard for radium is a 

combined standard for radium-226 and radium-228. 

Often, only the radium-226 concentration was determined for most analyses reported by the USGS. 

Samples with radium-226 concentrations greater than 

5 pCi/L exceed the MCL, but samples with concentrations less than 5 pCi/L also may exceed the standard 

depending on the radium-228 concentrations, which 

usually are not known for the data used in this study. 

When possible, concentrations of radium-226 and 

radium-228 were added. However, in the following 

sections the number of samples that exceed drinkingwater standards for radium should be considered a minimum value because other additional samples also may 

exceed.

Concentrations that exceed the drinking-water 

standard for gross beta as strontium/yttrium-90 

reported by the USGS cannot be determined by comparison to the standard for strontium-90 because the 

USGS data include yttrium. It should be noted that

any samples that exceed 8 pCi/L for gross beta as 

strontium/yttrium-90 may exceed the standard for 

strontium-90.

Because few or no samples were collected from 

several major aquifers for many radionuclides, comparisons between mean and median concentrations will 

not be made in this section. General comparisons 

among the aquifers will be made in this section, and 

additional discussions on radionuclides for selected 

aquifers will be presented.

In general, gross alpha, gross beta, and radium226 is higher in the Inyan Kara and Deadwood aquifers 

than in the Madison, Minnelusa, and Minnekahta 

aquifers (fig. 25). Radon-222 concentrations are much 

higher, and thorium and uranium concentrations are 

lower in the Deadwood aquifer than in the Madison and 

Minnelusa aquifers. Radon-222 concentrations also 

can be high in alluvial aquifers. Uranium concentrations may be high in the Inyan Kara aquifer and have 

considerable variability in the Sundance, Morrison, 

Pierre, Graneros, and alluvial aquifers.

Deadwood Aquifer

Concentrations of some radionuclides, especially radon and radium, are known to be high in the 

Deadwood Formation (Rounds, 1991). Therefore, it is 

not surprising that water samples from the Deadwood 

aquifer have elevated concentrations of radon and 

radium-226. Samples from the Deadwood aquifer have 

lower uranium concentrations relative to other aquifers, which may be due to the reducing conditions of 

the Deadwood aquifer (Rounds, 1991).

Concentrations of gross alpha as uraniumnatural (micrograms per liter) generally increase with 

increasing well depth (fig. 26) and are highest in the 

eastern Black Hills. The highest gross beta concentrations (as both cesium-137 and strontium/yttrium-90) 

and highest uranium concentrations also occur in the 

eastern Black Hills.

More than 30 percent of the samples (8 of 26) 

analyzed for radium-226 or radium-226 and radium228 exceed the MCL of 5 pCi/L for the combined 

radium-226 and radium-228 standard. Almost 

88 percent of the samples (14 of 16) exceed the proposed MCL of 300 pCi/L for radon in States without an 

active indoor air program; three of these samples also 

exceed the proposed MCL of 4,000 pCi/L for radon in 

States with an active indoor air program (fig. 27).

Madison Aquifer

Water from the Madison aquifer generally is low 

in radionuclide concentrations. Carda (1975) reported 

that samples collected in the Black Hills area from the 

Madison aquifer contained no detectable concentrations of radionuclides; however, three Madison wells 

outside the study area had high concentrations of 

radium-226 ranging from 190 pCi/L at Midland (about 

90 miles east of the study area) to 511 pCi/L at Phillip 

(about 50 miles east of the study area).

Gross alpha concentrations (measured as alpha 

radioactivity as thorium-230 and as uranium-natural in 

both picocuries per liter and micrograms per liter) and 

radium-226 concentrations generally increase with 

increasing well depth (fig. 26). Concentrations of other 

radionuclides vary with geographic location. The 

highest gross beta concentrations, as both cesium-137 

and strontium/yttrium-90, occur in the southern Black 

Hills. The highest thorium concentrations occur in the 

eastern and southern Black Hills, and the highest tritium concentrations occur in the eastern and northern 

Black Hills. Because the only radon concentrations 

were available from wells in the eastern Black Hills, it 

is not known if radon concentrations vary with geographic location.

One of 45 samples exceeds the MCL of 30 μg/L 

for uranium. This sample was collected from a well 

located in the southern Black Hills. One of 12 samples 

exceeds the proposed MCL for radon in States without 

an active indoor air program, but this sample does not 

exceed the proposed MCL for radon in States with an 

active indoor air program. This sample was collected 

from a well in the eastern Black Hills.
Water-Quality Characteristics of Selected Aquifers 103

Figure 26. Selected relations between radionuclides and well depth for selected aquifers.

DEADWOOD AQUIFER

WELL DEPTH, IN FEET

R2 = 0.2311

0 200 400 600 800 1,000 1,200 1,400 1,600 0

200

20

40

60

80

100

120

140

160

180

 GROSS ALPHA AS URANIUM-NATURAL,

IN MICROGRAMS PER LITER

WELL DEPTH, IN FEET

MADISON AQUIFER

WELL DEPTH, IN FEET

0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 0 5,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

R2 = 0.4737 R2 = 0.2855

R2 R2 = 0.5412 = 0.2906

0

22

2

4

6

8

10

12

14

16

18

20

GROSS ALPHA AS URANIUM-NATURAL,

IN PICOCURIES PER LITER

0

17

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

ALPHA RADIOACTIVITY AS THORIUM-230,

IN PICOCURIES PER LITER

0

22

2

4

6

8

10

12

14

16

18

20

GROSS ALPHA AS URANIUM-NATURAL,

IN MICROGRAMS PER LITER 0.2

3.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

RADIUM-226, IN PICOCURIES PER LITER
104 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 26. Selected relations between radionuclides and well depth for selected aquifers.--Continued

WELL DEPTH, IN FEET

INYAN KARA AQUIFER

0 2,800 0 200 400 600 800 1,0001,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

WELL DEPTH, IN FEET

0 2,800 0 200 400 600 800 1,0001,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

R2 = 0.4590

R2 = 0.1261

R2 = 0.2465

0

160

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

GROSS ALPHA AS URANIUM-NATURAL,

IN PICOCURIES PER LITER

2

44

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

42

GROSS BETA AS CESIUM-137,

IN PICOCURIES PER LITER

0

50

5

10

15

20

25

30

35

40

45

RADIUM-226, IN PICOCURIES PER LITER
Water-Quality Characteristics of Selected Aquifers 105

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA LIMESTONE

PLATEAU

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

5,800

6,600

5,300

2,700

1,400 1,100

1,500

900

560

800

920

1,600

220

80

1,300

690

5,800

6,600

5,300

2,700

1,400 1,100

1,500

900

560

800

920

1,600

220

80

1,300

690

0 10 20

0 10 20 MILES

KILOMETERS

OUTCROP OF DEADWOOD

 FORMATION (from Strobel

 and others, 1999)

DEADWOOD FORMATION

 ABSENT (from Carter and

 Redden, 1999e)

RADON CONCENTRATION--

 Number is radon concentration

 in picocuries per liter. Circle

 size increases with increasing

 concentrations 

Less than 300

300 - 3,000

Greater than 3,000

Figure 27. Distribution of radon concentrations in the Deadwood aquifer.

EXPLANATION

80

500

5,300

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
106 Water-Quality Characteristics in the Black Hills Area, South Dakota

Minnelusa Aquifer

Water from the Minnelusa aquifer generally is 

low in radionuclide concentrations, but may be high in 

some areas. In the Minnelusa aquifer, uranium concentrations are highest in the southern and eastern Black 

Hills. The highest gross beta concentrations (as 

cesium-137 and strontium/yttrium-90) are in the 

southern Black Hills. The highest thorium concentrations are in the eastern and southern Black Hills, 

whereas the highest tritium concentrations are in the 

eastern and northern Black Hills.

Of the 11 samples analyzed for alpha radioactivity as thorium-230, three samples exceed the MCL 

of 15 pCi/L for gross alpha; all of the samples that 

exceed the MCL were from the southern Black Hills. 

One of 17 samples exceeds the MCL for the combined 

radium-226 and radium-228; this sample was from a 

well located in the eastern Black Hills.

Inyan Kara Aquifer

Uranium was discovered in the Black Hills area 

in Fall River County in 1951 in the basal 100 to 

150 feet of the Lakota Formation of the Inyan Kara 

Group (Page and Redden, 1952). Following the first 

discovery, numerous other uranium deposits were discovered in the southern Black Hills. Uranium may be 

introduced into the Inyan Kara Group through the 

artesian recharge of water from the Minnelusa aquifer 

(Gott and others, 1974). As water in the Inyan Kara 

aquifer flows downgradient, geochemical conditions 

favor the precipitation of uranium (Gott and others, 

1974). Therefore, it is not surprising that some water 

from the Inyan Kara aquifer, especially in the southern 

Black Hills, contains relatively high concentrations of 

radionuclides. 

Concentrations of several radionuclides vary 

with well depth (fig. 26). Gross alpha as U-natural in 

picocuries per liter, gross beta as cesium-137, and 

radium-226 generally increase with increasing well 

depth associated with increasing distance from the outcrop. Other concentrations vary with geographic location. The highest uranium and thorium concentrations 

are from wells located in the southern Black Hills.

Almost 18 percent of the samples (6 of 34 samples) collected from the Inyan Kara aquifer exceed the 

MCL for combined radium-226 and radium-228; all 

but one of these samples are from wells in the southern 

Black Hills. About 4 percent of the samples (3 of 77 

samples) exceed the MCL for uranium; all these samples are from wells located in the southern Black Hills.

Minor Aquifers

Excluding analyses from alluvial aquifers, the 

MCL of 30 μg/L for uranium is the only drinking-water 

standard that is exceeded by samples from other 

aquifers in the study area. However, few analyses exist 

for gross alpha, radium, and radon for the minor 

aquifers in the study area. In addition to the uranium 

concentrations in the alluvial aquifers, 1 of 9 samples 

from the Spearfish aquifer, 2 of 6 samples from the 

Morrison aquifer, 5 of 28 samples from the Pierre 

aquifer, and 1 of 10 samples from the Graneros aquifer 

exceed the MCL for uranium.

Samples from alluvial aquifers may be high in 

uranium concentrations, especially in the southern 

Black Hills. About 17 percent of the samples (5 of 29 

samples) exceed the MCL for uranium, and all were 

collected from wells located in the southern Black 

Hills. In addition to uranium, thorium concentrations 

were highest in the southern Black Hills. One of four 

samples from alluvial aquifers exceeds the proposed 

MCL for radon in States without an active indoor air 

program, but this sample does not exceed the proposed 

MCL for radon in States with an active indoor air 

program.

Summary for Aquifers in Relation to Water Use

Concentrations exceeding the SMCL’s or MCL’s 

may affect the use of water in some areas for many 

aquifers within the study area. Most concentrations 

exceeding standards are for various SMCL’s and 

generally only affect the aesthetic quality of the water. 

Radionuclide concentrations may be especially high in 

some of the major aquifers within the study area and 

preclude the use of water in some areas. Hard water 

may require special treatment for certain uses. Other 

factors, such as the SAR and specific conductance, may 

affect irrigation use. 

High concentrations of iron and manganese 

occasionally may hamper the use of water from 

Precambrian aquifers. None of the samples from the 

Precambrian aquifers exceeded drinking-water standards for radionuclides, although few samples with 

radionuclide analyses were available. 

The principal deterrents to use of water from the 

Deadwood aquifer are the high concentrations of radionuclides, including radium-226 and radon. In addition, concentrations of iron and manganese can be high.

Water from the Madison aquifer can contain high 

concentrations of iron and manganese that may deter its 

use. Water from the Madison aquifer is hard to very 
Water-Quality Characteristics of Selected Surface-Water Sites 107

hard and may require special treatment for certain uses. 

In downgradient wells (generally deeper than 

2,000 feet), concentrations of dissolved solids and 

sulfate also may deter use of water from this aquifer. In 

deep wells and in the Hot Springs area, hot water may 

not be desirable for some uses. Radionuclide concentrations in the Madison aquifer generally are acceptable.

The principal properties or constituents in the 

Minnelusa aquifer that may hamper the use of water 

from this aquifer include hardness and high concentrations of iron and manganese. Generally, downgradient 

wells (generally deeper than 1,000 feet) also have high 

concentrations of dissolved solids and sulfate. In deep 

wells, hot water may be undesirable for some uses. 

Arsenic may be a problem for some wells if the MCL 

is lowered to 10 μg/L. Only a few samples exceed the 

MCL’s for various radionuclides.

Water from the Minnekahta aquifer generally is 

suitable for all water uses because few samples exceed 

SMCL’s or MCL’s and no samples available for this 

study from the Minnekahta aquifer exceed drinkingwater standards for any radionuclides; however, 

samples are available only from shallow wells near the 

outcrop. Water from the Minnekahta aquifer is harder 

than that from any of the other major aquifers in the 

study area, and may require special treatment for 

certain uses.

The use of water from the Inyan Kara aquifer 

may be hampered by high concentrations of dissolved 

solids, iron, sulfate, and manganese. In the southern 

Black Hills, radium-226 and uranium concentrations 

also may preclude its use. Hard water from wells 

located on or near the outcrop of the Inyan Kara Group 

may require special treatment. Suitability for irrigation 

may be affected by high specific conductance and the 

adjusted SAR.

The use of water from minor aquifers may be 

hampered by hardness and concentrations of dissolved 

solids and sulfate. Concentrations of radionuclides, 

with the exception of uranium, generally are acceptable 

in samples from these minor aquifers. Selenium concentrations may be an additional deterrent to the use of 

water from the Sundance aquifer. Water from the 

Pierre and Sundance aquifers generally is not suitable 

for irrigation. Water from the other minor aquifers generally is suitable, but may not be in specific instances if 

either the specific conductance or the SAR is high.

Water from alluvial aquifers generally is very 

hard and may require special treatment for certain uses. 

In alluvial deposits that overlie the Cretaceous-age 

shales, the high concentrations of dissolved solids, 

sulfate, iron, and manganese may limit the use of water 

from these aquifers. In the southern Black Hills, 

uranium concentrations can be high in alluvial aquifers 

in many locations.

Water-Quality Characteristics of Selected 

Surface-Water Sites

The water-quality characteristics for selected 

surface-water sites (fig. 7; table 16 in the Supplemental 

Information section), including streams and springs 

within the study area, are presented in this section. 

Surface-water quality depends largely on the geology 

of the area. Selected sites are used within this section 

to characterize the geologic influences based on the 

hydrogeologic settings presented in figure 7. These 

sites include headwater springs, crystalline core sites, 

artesian springs, and exterior sites. Headwater springs 

originate from the Paleozoic units (fig. 2) on the 

western side of the study area, and each spring tends to 

have relatively constant water-quality characteristics. 

Other streams originate in the Precambrian rocks of the 

crystalline core and tend to have more variability than 

the headwater springs. Artesian springs occur downgradient from the loss zones and contribute much of the 

base flow to exterior streams beyond the Black Hills. 

Additional exterior streams originate around the 

periphery of the Black Hills and represent sites having 

greater fluctuations in water-quality characteristics 

than the representative sites for other settings. The 

selected representative sites for the hydrogeologic settings generally have longer periods of record and more 

closely represent sites with characteristics that depend 

largely on the geologic influences. These sites have 

been used as representative sites in other reports 

produced as part of the Black Hills Hydrology Study. 

Many other surface-water sites from throughout the 

Black Hills are included in an “other” category to 

provide indications of the wider ranges that can occur 

and represent the combination of influences on waterquality characteristics within the study area. 

Mineralized areas in the northern Black Hills as 

well as the generally drier climate of the southern 

Black Hills influence water-quality characteristics. 

Changes that occur within a basin as streams flow 

downslope from headwater areas to the exterior plains 

also will be examined (fig 7a).
108 Water-Quality Characteristics in the Black Hills Area, South Dakota

Boxplots and summary statistics are presented 

for physical properties, common ions, nutrients, trace 

elements, and radionuclides. Figures illustrating 

spatial variations as well as trilinear and Stiff diagrams 

(Stiff, 1951), which indicate water type, also are 

presented. 

Concentrations are compared to drinking-water 

standards as well as beneficial-use and aquatic-life 

criteria. Drinking-water standards are directly relevant 

to a limited number of stream segments with the beneficial use of domestic water supply, but concentrations 

that exceed these standards may be of interest to local 

users as a precautionary measure. Many of the aquatic 

criteria are dependent on hardness. If a concentration 

exceeds the aquatic criteria that is based upon a hardness of 100 mg/L, the appropriate hardness-calculated 

criterion is presented. Drinking-water standards are for 

total concentrations, and results reported by the USGS 

as dissolved concentrations may be less than those 

obtained for similar samples analyzed for total concentrations. A summary of how water-quality characteristics may affect the water use for selected sites within 

the study area is presented at the end of this section.

Physical Properties

The physical properties of the surface-water 

samples include measurements for discharge, specific 

conductance, pH, water temperature, dissolved 

oxygen, carbon dioxide, hardness, and alkalinity. 

Statistical comparisons identified similarities and 

differences between the groups of sites—headwater 

springs, crystalline core sites, artesian springs, exterior 

sites, and other sites. Summary statistics are presented 

in table 9, and the significance of the properties is 

described in table 1. Boxplots are presented in 

figure 28 for each of the properties by group.

Streamflow and the physical properties of the 

water can vary with the hydrogeologic settings. 

Seasonal variability and range in discharge for a representative site from each hydrogeologic setting (fig. 29) 

illustrate discharge variability by group. Relations 

commonly exist between discharge and specific conductance (fig. 30) and between temperature and 

dissolved oxygen (fig. 31).

Group Comparisons

Discharge at headwater springs displays little 

variability (fig. 28) compared to most other groups, 

with only artesian springs having similar flow characteristics. Discharge from the artesian springs is relatively constant at each individual site with more 

variability between sites. Artesian springs generally do 

not display large seasonal or historic variability in discharge (fig. 29). Discharge for crystalline core sites 

displays wider ranges in variability and generally 

varies with season with increasing flows during the 

spring and summer when snowmelt and precipitation 

result in greater runoff. The greatest variability in discharge is measured at exterior sites, which have much 

larger drainage basins than the other groups. 

Most of the other physical properties (including 

specific conductance, hardness, and alkalinity) at headwater springs also display limited variability (fig. 28). 

The stable nature of both discharge and specific conductance at headwater springs is apparent in figure 30. 

Specific conductance at crystalline core sites generally 

decreases as flow increases (fig. 30) due to dilution. 

Specific conductance varies considerably from one 

artesian spring to another; however, specific conductance is relatively constant at each site. At exterior 

sites, specific conductance generally is much higher 

than that for other hydrogeologic settings with a mean 

of 3,400 μS/cm and a maximum of 9,250 μS/cm. 

Compared to sites in the other hydrogeologic settings, 

much stronger relations exist between discharge and 

specific conductance at the exterior sites, with more 

pronounced decreases in specific conductance with 

increasing discharge (fig. 30).

Twenty-one percent of the samples (56 of 263 

samples) from headwater springs exceed the SMCL 

upper limit of 8.5 for pH, with concentrations 

exceeding standards for three of the four headwater 

springs included in this summary. Most values 

exceeding the SMCL for pH occurred at Castle Creek 

above Deerfield Reservoir (06409000); samples from 

this site composed more than 90 percent of the headwater spring samples. There also were 28 samples 

exceeding the coldwater permanent fisheries criteria 

(upper limit of 8.6) and 6 samples exceeding the coldwater marginal fisheries criteria (upper limit of 8.8), 

accounting for 11 and 2 percent of samples, respectively. Fifteen percent of the samples from crystalline 

core sites exceed the SMCL for pH, and 7 percent and 

2 percent exceed the coldwater permanent and marginal criteria, respectively. The pH values for artesian 

springs are much lower than at headwater springs and 

crystalline core sites, and generally are less than 8.5. 

One percent of the pH values at exterior sites exceed 

the SMCL upper limit of 8.5, and no samples exceed 

the fisheries beneficial-use pH criteria (table 2).
Water-Quality Characteristics of Selected Surface-Water Sites 109

Figure 28. Boxplots of concentrations of selected properties by surface-water group.

650 1,763 544 811 7,640

0.001

100,000

0.01

0.1

1

10

100

1,000

10,000

DISCHARGE, IN CUBIC FEET PER SECOND

263 155 11 250 2,123

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP

6

10

7

8

9

pH, IN STANDARD UNITS

663 1,679 518 882 6,174

10

10,000

20

30

40

50

70

100

200

300

400

500

700

1,000

2,000

3,000

4,000

5,000

7,000

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER 
110 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 28. Boxplots of concentrations of selected properties by surface-water group.--Continued

699 1,771 563 774 7,114

-10

40

0

10

20

30

TEMPERATURE,

IN DEGREES CELSIUS

257 138 9 75 1,842 4,000

0

1,000

2,000

3,000

HARDNESS, 

IN MILLIGRAMS PER LITER

177 148 7 36 779

0

20

15

10

5

DISSOLVED OXYGEN, 

IN MILLIGRAMS PER LITER 

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
Water-Quality Characteristics of Selected Surface-Water Sites 111

Figure 28. Boxplots of concentrations of selected properties by surface-water group.--Continued

247 145 8 179 1,781

0

1,200

400

200

600

800

1,000

ALKALINITY,

IN MILLIGRAMS PER LITER

25th percentile

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

EXPLANATION

145 Number of samples

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
112 Water-Quality Characteristics in the Black Hills Area, South Dakota

0.1

10,000

0.2

0.5

1

2

5

10

20

50

100

200

500

1,000

2,000

5,000

0.1

10,000

0.2

0.5

1

2

5

10

20

50

100

200

500

1,000

2,000

5,000

DISCHARGE, IN CUBIC FEET PER SECOND

O N D J F M A M J J A S

Crystalline core site - Battle Creek near Keystone, 06404000, water years 1961-98

Headwater spring - Castle Creek above Deerfield, 06409000, water years 1948-98

Figure 29. Duration hydrographs of daily mean flow for selected headwater, crystalline, artesian, and exterior

surface-water group sites.
Water-Quality Characteristics of Selected Surface-Water Sites 113

0.1

10,000

0.2

0.5

1

2

5

10

20

50

100

200

500

1,000

2,000

5,000

EXPLANATION

MAXIMUM

75TH PERCENTILE

MEDIAN

25TH PERCENTILE

MINIMUM

DISCHARGE, IN CUBIC FEET PER SECOND

O N D J F M A M J J A S

Exterior site - Cheyenne River at Edgemont, 06395000, water years 1946-98

Artesian spring - Fall River at Hot Springs, 06402000, water years 1937-98

0.1

100,000

0.2

0.5

1

2

5

10

20

50

100

200

500

1,000

2,000

5,000

10,000

20,000

50,000

Figure 29. Duration hydrographs of daily mean flow for selected headwater, crystalline, artesian, and exterior

surface-water group sites.--Continued
114 Water-Quality Characteristics in the Black Hills Area, South Dakota

Table 9. Summary of physical properties in surface water by group

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter is approximately equal to one part per billion. ft3

/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 

degrees Celsius; °C, degrees Celsius]

Property or dissolved constituent Number of

samples Mean Median Minimum Maximum

Headwater springs

Discharge (ft3/s) 650 14.1 12.0 2.1 147

Specific conductance (μS/cm) 663 460 460 304 715

pH (standard units) 263 8.3 8.3 7.2 9.6

Temperature (°C) 699 6.8 6.5 0.0 29.0

Dissolved oxygen 177 10.4 10.3 6.9 16.3

Hardness 257 258 260 190 300

Alkalinity 247 249 253 182 290

Crystalline core sites

Discharge (ft3/s) 1,763 19.4 3.8 0.0 1,460

Specific conductance (μS/cm) 1,679 297 290 48 2,620

pH (standard units) 155 8.2 8.3 6.5 9.3

Temperature (°C) 1,771 8.9 8.5 -1.0 27.0

Dissolved oxygen 148 10.1 9.7 6.7 15.6

Hardness 138 158 170 29 310

Alkalinity 145 130 134 28 298

Artesian springs

Discharge (ft3/s) 544 20.5 20.0 3.8 158

Specific conductance (μS/cm) 518 1,692 1,340 114 3,300

pH (standard units) 11 7.7 7.8 7.2 8.0

Temperature (°C) 563 18.9 20.0 3.5 29.0

Dissolved oxygen 7 9.5 8.5 8.0 12.5

Hardness 9 769 710 530 1,500

Alkalinity 8 181 187 155 202

Exterior sites

Discharge (ft3/s) 811 177.6 7.8 0.0 26,300

Specific conductance (μS/cm) 882 3,400 3,110 130 9,250

pH (standard units) 250 7.9 8.0 6.8 8.7

Temperature (°C) 774 10.7 10.0 0.0 33.5

Dissolved oxygen 36 9.9 10.3 6.8 13.1

Hardness 75 1,296 1,100 150 3,100

Alkalinity 179 215 198 67 621
Water-Quality Characteristics of Selected Surface-Water Sites 115

Other sites

Discharge (ft3/s) 7,640 110.6 24.0 0.0 27,700

Specific conductance (μS/cm) 6,174 1,035 640 48 9,450

pH (standard units) 2,123 7.9 8.0 6.6 9.6

Temperature (°C) 7,114 10.5 10.0 -2.5 32.5

Dissolved oxygen 779 9.2 9.1 1.3 15.4

Hardness 1,842 769 750 28 3,400

Alkalinity 1,781 170 160 4.0 1,080

Table 9. Summary of physical properties in surface water by group—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter is approximately equal to one part per billion. ft3/s, cubic feet per second; μS/cm, microsiemens per centimeter at 25 

degrees Celsius; °C, degrees Celsius]

Property or dissolved constituent Number of

samples Mean Median Minimum Maximum
116 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 30. Relations between discharge and specific conductance for selected sampling sites by surface-water group.

0.001 10,000 0.01 0.1 1 10 100 1,000

10

10,000

7050403020

700500400300200100

7,0005,0004,0003,0002,0001,000

HEADWATER SPRINGS

06408700

060490000643077006430850

0.001 10,000 0.01 0.1 1 10 100 1,000

10

10,000

7050403020

700500400300200100

7,0005,0004,0003,0002,0001,000

ARTESIAN SPRINGS

06400497

0640200006402470064128100643053206430540

0.001 10,000 0.01 0.1 1 10 100 1,000

10

10,000

7050403020

700500400300200100

7,0005,0004,0003,0002,0001,000

CRYSTALLINE CORE SITES (subset of 14 sites)

06404000

06404998064075000642250006430898

0.001 10,000 0.01 0.1 1 10 100 1,000

DISCHARGE, IN CUBIC FEET PER SECOND

10

10,000

7050403020

700500400300200100

7,0005,0004,0003,0002,0001,000

EXTERIOR SITES

06395000

064000000643350006436760

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER
Water-Quality Characteristics of Selected Surface-Water Sites 117

Figure 31. Relations between temperature and dissolved oxygen for selected surface-water groups.

-5 0 5 10 15 20 25 30 35

TEMPERATURE, IN DEGREES CELSIUS

0

18

2

4

6

8

10

12

14

16

DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

EXPLANATION

OTHER SITE

HEADWATER SPRING

CRYSTALLINE CORE SITE

ARTESIAN SPRING

EXTERIOR SITE
118 Water-Quality Characteristics in the Black Hills Area, South Dakota

Variations in water temperature occur primarily 

as seasonal fluctuations. Dissolved oxygen concentrations generally vary with temperature, with lower dissolved oxygen concentrations occurring during periods 

of higher temperature (fig. 31). For headwater springs, 

seven samples (1 percent of the samples) exceed the 

coldwater permanent fisheries criteria for temperature 

(18.3°C), and two samples exceed the coldwater marginal fisheries temperature criteria (24°C), indicating 

that temperature may stress fish during unusually warm 

summer periods with lower flows. Dissolved oxygen 

concentrations rarely are less than 7 mg/L, the minimum criteria during spawning periods. Almost 

12 percent of the water temperature measurements for 

crystalline core sites exceed the coldwater permanent 

fisheries criteria of 18.3oC (210 of 1,771 samples), and 

less than 1 percent exceed the coldwater marginal 

fisheries criteria of 24oC. The artesian springs 

generally have higher temperatures (fig. 28) than other 

groups because of the ground-water contribution to the 

springs. Water-temperature statistics for the artesian 

springs are strongly influenced by Fall River at Hot 

Springs (06402000), which is a warm-water spring in 

the southern Black Hills. Fall River displays little variability with season, and freezing temperatures have not 

been recorded at this site. Temperature and dissolved 

oxygen concentration ranges at exterior sites are 

similar to the other groups. Dissolved oxygen concentrations in water from the exterior sites generally 

remain greater than 6 mg/L even at higher temperatures, and ranges of 6 to 12 mg/L are not uncommon 

for temperature ranges of 10 to 30oC (fig. 31). 

Dissolved oxygen concentrations of 2.1, 2.2, and 

3.6 mg/L have been measured at an urban runoff site 

within the Rapid Creek Basin (06416300, Meade Street 

Drain). Two additional sites with low dissolved 

oxygen concentrations are Cottonwood Creek near 

Buffalo Gap and Cheyenne River near Buffalo Gap. In 

addition, low dissolved oxygen concentrations have 

been reported at exterior sites (including the Cheyenne 

River and tributaries) when temperatures are high and 

flows are very low (Hoof, 1998). 

Water from headwater springs generally is very 

hard with concentrations greater than 190 mg/L 

(table 9). The median alkalinity for the headwater 

springs of 253 mg/L (table 9) is the highest of the 

surface-water groups. Water at the crystalline core 

sites ranges from soft to very hard, with the soft water 

occurring primarily because of minimal exposure to 

limestone and sandstone units, which are a source of 

calcium and magnesium. Alkalinity at the crystalline 

core sites ranges from 28 to 298 mg/L. Water from the 

artesian springs is very hard with alkalinity ranging 

from 155 to 202 mg/L (table 9). Hardness and alkalinity at exterior sites are higher than or similar to upslope sites with the water being hard to very hard. The 

maximum alkalinity concentration of 1,080 mg/L 

occurred at Horse Creek near Vale (06436800, other 

site group) and approached the wildlife propagation 

and stock-watering criteria daily maximum of 

1,313 mg/L.

Additional Comparisons

Urbanization is one factor that influences natural 

conditions of streams. Increased runoff during storms, 

permitted discharges, and factors such as channelization and increased public use, can affect stream quality. 

Limited urbanization exists in the Black Hills currently, 

but population in the area continues to grow rapidly. 

Both Rapid City and Spearfish have experienced recent 

growth that challenges city and county managers with 

protection of water and natural conditions while 

providing for economic growth. 

Within a basin, changes in discharge include 

losses of water as streams cross loss zones and then 

gains downstream (Hortness and Driscoll, 1998). 

Additional streamflow losses and gains can occur due 

to effects from urbanization and agriculture including 

irrigation. Other physical properties, such as specific 

conductance and hardness, generally increase downstream with additional exposure to and dissolution of 

calcium, magnesium, sodium, and sulfate as shown by 

increasing concentrations in the Rapid Creek Basin 

from its headwaters to near its confluence with the 

Cheyenne River (fig. 32, fig. 7a). 

Water-quality changes have been identified in 

streams in the northern Black Hills where sulfide ores 

have been exposed by mining (Williamson and Hayes, 

2000). In areas of acid-mine drainage or naturally 

occurring iron-bog areas, pH values can be very low, 

often less than 6. A downstream progression of pH 

values for two streams (False Bottom and Deadwood 

Creeks) affected by mining activities is presented in 

figure 33. Upstream from mining activities, pH levels 

in the stream are normal for the area. The stream pH 

then decreases to low levels immediately downstream 

of mining activities. Farther downstream from mining 

activities, pH values generally increase to near normal 

levels again after exposure to the calcium-rich 

sediments common to the area (Torve, 1991). 
Water-Quality Characteristics of Selected Surface-Water Sites 119

 

Figure 32. Boxplots of specific conductance and hardness for selected surface-water sites in Rapid Creek Basin.

354 205 302 247 248 178 261

1,600

200

0

400

600

800

1,000

1,200

1,400

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

STATION NUMBER IN DOWNSTREAM ORDER (FIGURE 7A)

239 0 171 11 4 265 2

0

800

600

400

200

HARDNESS, IN MILLIGRAMS PER LITER 

06409000 06410500 06411500 06412500 06414000 06418900 06421500

25th percentile

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

EXPLANATION

145 Number of samples

Single sample
120 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 33. Downstream progression of pH for selected streams influenced by acid mine drainage.

Upstream from mining Downstream from mining Immediately downstream

from mining

3.5

8.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

pH, IN STANDARD UNITS

EXPLANATION

FALSE BOTTOM CREEK

DEADWOOD CREEK

Southeast False Bottom

Creek near Lead

442250103485700

False Bottom Creek above

Columbia Mine near Lead

442251103493800 

False Bottom Creek 

near Central City

06432172

South Deadwood Creek above

Hidden Treasure Mine near Lead

442125103483000

Deadwood Creek below Hidden

Treasure Mine near Lead

442131103482000 

Deadwood Creek below Broken

Boot Mine at Deadwood

442213103443900
Water-Quality Characteristics of Selected Surface-Water Sites 121

Common Ions

Summary statistics for selected common ions are 

presented in table 10, and the significance of the 

various common ions is described in table 1. Boxplots 

are presented in figure 34 for each of the common ions, 

except dissolved solids (residue at 180°C), percent 

sodium, and SAR.

Group Comparisons

Specific conductance can be used to estimate the 

concentration of dissolved solids. Linear regression 

was performed using specific conductance (field and 

laboratory), and concentrations of dissolved solids 

(sum of constituents or residue) for each group, and 

results are presented in table 11 and figure 35. The 

regression of specific conductance and dissolved solids 

for headwater springs yields a weak relation due to the 

small variability in both specific conductance and dissolved solids. For headwater springs, specific conductance ranged from 304 to 705 μS/cm, and dissolved 

solid concentrations (sum of constituents) ranged from 

186 to 294 mg/L. The relation between specific conductance and dissolved solids is much stronger for 

crystalline core sites, artesian springs, and exterior sites 

where greater variability of specific conductance and 

dissolved solids occurs. Dissolved solids concentrations (sum of constituents) ranges from 44 to 362 mg/L 

at crystalline core sites, from 834 to 2,240 mg/L at artesian springs, and from 346 to 6,460 mg/L at exterior 

sites (table 10).

The variation in water type for the surface-water 

groups is shown by trilinear diagrams (fig. 36) and Stiff 

diagrams (fig. 37). Calcium and magnesium are the 

dominant cations (40 to 60 percent of total cations), 

and bicarbonate the dominate anion (80 to 99 percent 

of total anions) for headwater springs (figs. 36 and 37) 

similar to samples from the Madison aquifer (fig. 17) 

from wells located on or near the Madison Limestone 

outcrop. Generally, only crystalline core sites have 

lower concentrations of common ions than headwater 

springs (fig. 37). Crystalline core sites generally are a 

calcium bicarbonate type water or calcium bicarbonate 

sulfate type water (fig. 36) and are similar to samples 

from the Precambrian aquifers (fig. 17) with slightly 

higher sulfate and chloride.

Water from the artesian springs is a calcium 

sulfate type (fig. 37). Increased sulfate at artesian 

springs is the most notable difference from headwater 

springs and crystalline core sites. Sources of sulfate 

include rock/water interactions in the Minnelusa 

Formation from upwelling Madison aquifer and/or 

Minnelusa aquifer water (primary source water for 

these springs) or exposure to shale units such as the 

Spearfish Formation at or near land surface. The range 

of sulfate concentrations, based on the limited data set 

(eight samples), is similar to ranges found in groundwater samples from the Spearfish aquifer and from the 

Minnelusa aquifer within the sulfate transition zone 

(fig. 21). Sulfate concentrations from the artesian 

springs are all greater than the SMCL of 250 mg/L 

(table 10). 

Exterior sites generally have sodium calcium 

magnesium sulfate type waters (fig. 36). Increased 

sodium and sulfate concentrations are the most notable 

differences for the exterior sites (fig. 37). Sixty-six 

percent of the samples from the exterior sites have 

sulfate concentrations greater than 1,000 mg/L. Three 

of the 73 samples have sulfate concentrations less than 

the SMCL of 250 mg/L. The SAR does not exceed 10, 

so the sodium generally does not limit the use of this 

water for irrigation. Chloride also generally is much 

higher at these sites than at the headwater springs, crystalline core sites, and artesian springs. Of the 73 samples analyzed for chloride, 26 percent of the samples 

exceed the SMCL of 250 mg/L, and 10 percent of the 

samples exceed 500 mg/L. All of the concentrations 

that exceeded the SMCL are from Cheyenne River at 

Edgemont. 

Concentrations of common ions for the othersites group are very similar to those of the hydrogeologic settings groups, with maximum concentrations 

similar to exterior sites and minimum concentrations 

similar to headwater springs and crystalline core sites 

(table 10). Two bicarbonate concentrations greater 

than 800 mg/L and eight chloride concentrations 

greater than 400 mg/L have been determined for water 

from Horse Creek near Vale. The minimum bicarbonate concentration of 28 mg/L is for water from 

False Bottom Creek. All but one sulfate concentrations 

greater than 1,000 mg/L have occurred in water from 

exterior sites along the Cheyenne River, Belle Fourche 

River, or prairie tributaries. The exception is an urban 

runoff sample within the Rapid Creek Basin with a 

sulfate concentration of 1,100 mg/L.
122 Water-Quality Characteristics in the Black Hills Area, South Dakota

Table 10. Summary of concentrations of common ions in surface water by group

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter is approximately equal to one part per million; <, less than]

Dissolved constituent Number of 

samples

Number of 

censored 

samples

Mean Median Minimum Maximum

Headwater springs

Solids, residue at 180°C 224 0 249 252 147 476

Solids, sum of constituents 251 0 255 258 186 294

Calcium 255 0 55 56 25 70

Magnesium 255 0 29 30 20 40

Sodium 255 0 1.7 1.5 0.5 6.7

Sodium, percent 254 0 1.4 1.0 0.0 5.0

Sodium-adsorption ratio 254 0 0.0 0.0 0.0 0.2

Potassium 256 0 1.4 1.2 0.4 6.8

Bicarbonate 245 0 302 306 222 354

Sulfate 250 1 7.2 7.0 <1.0 29

Chloride 257 1 1.6 1.2 <0.1 25

Fluoride 256 8 0.2 0.1 <0.1 2.9

Silica 255 0 8.9 9.0 0.1 21

Crystalline core sites

Solids, residue at 180°C 100 0 184 192 53 350

Solids, sum of constituents 134 0 191 200 44 362

Calcium 134 0 41 41 8.6 79

Magnesium 134 0 13 14 1.8 28

Sodium 134 0 6.2 4.9 1.7 22

Sodium, percent 132 0 8.6 7.0 3.0 27

Sodium-adsorption ratio 132 0 0.2 0.2 0.1 0.7

Potassium 134 0 2.0 1.8 0.6 6.7

Bicarbonate 136 0 157 162 34 363

Sulfate 136 0 28 22 4.2 110

Chloride 138 0 7.1 3.7 0.2 48

Fluoride 116 4 0.4 0.3 <0.1 1.3

Silica 113 0 13 13 6.8 21

Artesian springs

Solids, residue at 180°C 6 0 936 990 206 2,130

Solids, sum of constituents 8 0 1,110 966 834 2,240

Calcium 8 0 248 245 150 470

Magnesium 8 0 43 38 33 83

Sodium 8 0 31 18 2.5 72

Sodium, percent 8 0 8.6 2.5 1.0 21
Water-Quality Characteristics of Selected Surface-Water Sites 123

Artesian springs—Continued

Sodium-adsorption ratio 8 0 0.4 0.2 0.0 1.0

Potassium 8 0 4.4 3.6 1.4 8.1

Bicarbonate 8 0 221 228 190 247

Sulfate 8 0 614 545 350 1,500

Chloride 8 0 39 22 0.7 94

Fluoride 8 0 0.5 0.5 0.3 0.7

Silica 8 0 16 14 11 23

Exterior sites

Solids, residue at 180°C 126 0 3,274 3,180 363 7,020

Solids, sum of constituents 72 0 2,768 2,605 346 6,460

Calcium 73 0 284 270 44 820

Magnesium 73 0 146 110 4.9 430

Sodium 73 0 371 370 44 890

Sodium, percent 72 0 37 38 19 60

Sodium-adsorption ratio 72 0 4.4 5.0 1.0 9.0

Potassium 72 0 9.6 9.2 1.2 17

Bicarbonate 134 0 273 268 82 757

Sulfate 73 0 1,667 1,400 140 4,200

Chloride 73 0 172 80 1.5 890

Fluoride 68 2 0.5 0.5 <0.1 1.0

Silica 61 0 7.1 6.3 0.9 38

Other sites

Solids, residue at 180°C 816 0 1,316 1,085 81 9,450

Solids, sum of constituents 1,646 0 1,368 1,150 78 8,380

Calcium 1,701 0 187 200 3.7 590

Magnesium 1,701 0 73 55 3.0 545

Sodium 1,702 0 134 83 1.0 1,420

Sodium, percent 1,641 0 20 20 1.0 63

Sodium-adsorption ratio 1,610 0 1.8 1.0 0.0 11

Potassium 1,663 1 7.6 7.6 <0.1 28

Bicarbonate 1,662 0 207 195 28 1,317

Sulfate 1,714 0 806 700 1.9 5,300

Chloride 1,930 4 39 8.8 <3.0 850

Fluoride 1,441 6 0.5 0.5 <0.1 6.0

Silica 1,418 0 8.9 8.6 0.0 41

Table 10. Summary of concentrations of common ions in surface water by group—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter except as 

indicated. One milligram per liter is approximately equal to one part per million; <, less than]

Dissolved constituent Number of 

samples

Number of 

censored 

samples

Mean Median Minimum Maximum
124 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 34. Boxplots of concentrations of selected ions by surface-water group.

251 134 8 72 1,646

0

10,000

2,000

4,000

6,000

8,000

DISSOLVED SOLIDS, SUM OF CONSTITUENTS

IN MILLIGRAMS PER LITER

255 134 8 73 1,701

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP

600

500

400

300

200

100

0

DISSOLVED MAGNESIUM,

IN MILLIGRAMS PER LITER

255 134 8 73 1,701

0

1,000

200

400

600

800

DISSOLVED CALCIUM,

IN MILLIGRAMS PER LITER 
Water-Quality Characteristics of Selected Surface-Water Sites 125

Figure 34. Boxplots of concentrations of selected ions by surface-water group.--Continued

255 134 8 73 1,702

DISSOLVED SODIUM,

IN MILLIGRAMS PER LITER

256 134 8 72 1,663

0

30

10

15

20

25

DISSOLVED POTASSIUM,

IN MILLIGRAMS PER LITER 

0.1

10,000

0.2

0.5

1

2

5

10

20

50

100

200

500

1,000

2,000

5,000

245 136 8 134 1,662

DISSOLVED BICARBONATE,

IN MILLIGRAMS PER LITER

0

1,400

1,200

1,000

800

600

400

200

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
126 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 34. Boxplots of concentrations of selected ions by surface-water group.--Continued

257 138 8 73 1,930

DISSOLVED CHLORIDE,

IN MILLIGRAMS PER LITER

256 116 8 68 1,441

0

8

2

4

6

DISSOLVED FLUORIDE,

IN MILLIGRAMS PER LITER 

0

1,000

200

400

600

800

250 136 8 73 1,714

DISSOLVED SULFATE,

IN MILLIGRAMS PER LITER

0.1

10,000

0.2

0.5

1

2

5

10

20

50

100

200

500

1,000

2,000

5,000

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
Water-Quality Characteristics of Selected Surface-Water Sites 127

Figure 34. Boxplots of concentrations of selected ions by group.--Continued

25th percentile

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

EXPLANATION

Number of samples Maximum Contaminant Level (mandatory)

 (U.S. Environmental Protection Agency,

 1994a)

134

Secondary Maximum Contaminant Level

 (recommended) (U.S. Environmental

 Protection Agency, 1994a)

Wildlife propogation and stock watering

 30-day average (South Dakota Department

 of Environment and Natural Resources,

 1998)

255 113 8 61 1,418

DISSOLVED SILICA,

IN MILLIGRAMS PER LITER

0

50

10

20

30

40

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
128 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 35. Relation between specific conductance and dissolved solids by surface-water group.

10 2,000 4,000 6,000 8,000 10,000

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

0

7,500

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

5,500

6,000

6,500

7,000

DISSOLVED SOLIDS, IN MILLIGRAMS PER LITER

EXPLANATION

HEADWATER SPRING

CRYSTALLINE CORE SITE

ARTESIAN SPRING

EXTERIOR SITE
Water-Quality Characteristics of Selected Surface-Water Sites 129

Figure 36. Trilinear diagrams showing proportional concentrations of major ions by surface-water group.

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

6040

20

40

60

80

80

60

40

20

HEADWATER SPRINGS

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

6040

20

40

60

80

80

60

40

20

ARTESIAN SPRINGS

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

PERCENT OF REACTING VALUES PERCENT OF REACTING VALUES

PERCENT OF REACTING VALUES PERCENT OF REACTING VALUES

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

604020

40

60

80

80

60

40

20

CRYSTALLINE CORE SITES

Calcium + Magnesium

Sulfate

Sodium + Potassium

Chloride + Fluoride + Nitrate + Sulfate

Bicarbonate + Carbonate

Magnesium

Calcium Chloride + Fluoride + Nitrate

80

60

40

20

80

80

60

40

20

20

20

40

60

80

40

60

80

60

40

20

20

80

604020

40

60

80

80

60

40

20

EXTERIOR SITES
130 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 37. Stiff diagrams for surface-water groups and selected sites.

STIFF DIAGRAMS FOR SELECTED HEADWATER SPRINGS

STIFF DIAGRAMS OF MEDIAN CONCENTRATIONS (BY GROUP)

Bicarbonate

Sulfate

Calcium

Magnesium

Bicarbonate

Sulfate

Calcium

Magnesium

20 0 20

MILLIEQUIVALENTS, PER LITER MILLIEQUIVALENTS, PER LITER

MILLIEQUIVALENTS, PER LITER MILLIEQUIVALENTS, PER LITER

20 0 20

06430770 06430850

Chloride + Fluoride

Bicarbonate

Sulfate

Sodium + Potassium

Sodium + Potassium Chloride + Fluoride

Sodium + Potassium Chloride + Fluoride

Sodium + Potassium Chloride + Fluoride

Calcium

Magnesium

Bicarbonate

Sulfate

Calcium

Magnesium

20 0 20 20 0 20

06408700 06409000

Bicarbonate

Sulfate

Calcium

Magnesium

Bicarbonate

Sulfate

Calcium

Magnesium

50 0 50

MILLIEQUIVALENTS, PER LITER

MILLIEQUIVALENTS, PER LITER

MILLIEQUIVALENTS, PER LITER

MILLIEQUIVALENTS, PER LITER

50 0 50

HEADWATER SPRINGS

EXTERIOR SITES

Chloride + Fluoride

Bicarbonate

Sulfate

Sodium + Potassium Chloride + Fluoride Sodium + Potassium

Sodium + Potassium Chloride + Fluoride Sodium + Potassium Chloride + Fluoride

Calcium

Magnesium

Bicarbonate

Sulfate

Calcium

Magnesium

50 0 50

50 0 50

CRYSTALLINE CORE SITES

ARTESIAN SPRINGS
Water-Quality Characteristics of Selected Surface-Water Sites 131

Figure 37. Stiff diagrams for surface-water groups and selected sites.--Continued

STIFF DIAGRAMS FOR SELECTED ARTESIAN SPRINGS

STIFF DIAGRAMS FOR SELECTED CRYSTALLINE CORE SITES

Bicarbonate

Sulfate

Calcium

Magnesium

Bicarbonate

Sulfate

Calcium

Magnesium

50 0 50

MILLIEQUIVALENTS, PER LITER MILLIEQUIVALENTS, PER LITER

MILLIEQUIVALENTS, PER LITER MILLIEQUIVALENTS, PER LITER

50 0 50

06430532 06430540

Chloride + Fluoride

Bicarbonate

Sulfate

Sodium + Potassium

Sodium + Potassium Chloride + Fluoride

Sodium + Potassium Chloride + Fluoride

Sodium + Potassium Chloride + Fluoride

Calcium

Magnesium

Bicarbonate

Sulfate

Calcium

Magnesium

50 0 50 50 0 50

06402000 06402470

Bicarbonate

Sulfate

Calcium

Magnesium

Bicarbonate

Sulfate

Calcium

Magnesium

20 0 20

MILLIEQUIVALENTS, PER LITER MILLIEQUIVALENTS, PER LITER

MILLIEQUIVALENTS, PER LITER MILLIEQUIVALENTS, PER LITER

20 0 20

06430800 06436156

Chloride + Fluoride

Bicarbonate

Sulfate

Sodium + Potassium

Sodium + Potassium Chloride + Fluoride

Sodium + Potassium Chloride + Fluoride

Sodium + Potassium Chloride + Fluoride

Calcium

Magnesium

Bicarbonate

Sulfate

Calcium

Magnesium

20 0 20 20 0 20

06404000 06404800
132 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 37. Stiff diagrams for surface-water groups and selected sites.--Continued

STIFF DIAGRAMS FOR SELECTED EXTERIOR SITES

MILLIEQUIVALENTS, PER LITER MILLIEQUIVALENTS, PER LITER

Chloride + Fluoride

Bicarbonate

Sulfate

Sodium + Potassium Chloride + Fluoride Sodium + Potassium

Calcium

Magnesium

Bicarbonate

Sulfate

Calcium

Magnesium

60 0 60 60 0 60

06395000 06436760

Generally, common ion concentrations tend to 

increase after the streams come in contact with the 

Cretaceous-age marine shales surrounding the Black 

Hills, which results in increased concentrations of 

sulfate complexed with calcium or sodium. Other ions 

such as chloride, magnesium, and potassium also tend 

to increase. figures 38 and 39 present spatial distributions of mean calcium and sulfate concentrations, 

respectively, for the study area. Specific conductance 

follows this same general pattern and linear relations 

commonly exist between specific conductance and 

selected common ion concentrations (fig. 40).

Additional Comparisons

A downstream progression of calcium and 

sulfate concentrations for Rapid Creek is shown in 

figure 41. Downstream from Rapid Creek above 

Canyon Lake, 06412500, concentrations of calcium 

and sulfate increase notably, which is consistent with 

the increased exposure to limestone and then 

Cretaceous-age marine shales.

Changes in ion concentrations over time often 

can provide indications of land-use changes near a site. 

Dissolved solids, sodium, and sulfate concentrations in 

the water from Bear Butte Creek near Deadwood, 

06437020, display increases during 1996 and 1997 

(fig. 42). In January 1996, the DENR issued a permit 

for mining in the Strawberry Creek Basin (South 

Dakota Department of Environment and Natural 

Resources, 1998), a tributary immediately upstream of 

the Bear Butte Creek site. Increases in sodium and 

sulfate may indicate that mining and reclamation 

activities were affecting the stream. A mining area in 

the Strawberry Creek Basin recently has been listed on 

the Superfund National Priorities List (South Dakota 

Department of Environment and Natural Resources, 

2001).

Table 11. Relation between specific conductance and 

dissolved solids for selected surface-water groups

[S = dissolved solids, in milligrams per liter; K = specific conductance, in 

microsiemens per centimeter

Group Equation of line R2

Number

of

samples

All S = 0.86K - 131.14 0.9692 2,355

Headwater springs S = 0.21K + 158.16 .2437 261

Crystalline core sites S = 0.55K + 15.83 .8914 136

Artesian springs S = 0.93K - 194.22 .9614 13

Exterior sites S = 0.85K - 249.50 .9676 174
Water-Quality Characteristics of Selected Surface-Water Sites 133

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Figure 38. Spatial distribution of median calcium concentrations in surface water.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

EXPLANATION

OUTCROP OF INYAN KARA

 GROUP (from Strobel and

 others, 1999)

MEDIAN CALCIUM CONCEN-

 TRATION, IN MILLIGRAMS

 PER LITER 

Less than 100

101 - 200

201 - 300

301 - 400

401 - 510

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
134 Water-Quality Characteristics in the Black Hills Area, South Dakota

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Figure 39. Spatial distribution of median sulfate concentrations in surface water.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

EXPLANATION

OUTCROP OF INYAN KARA

 GROUP (from Strobel and

 others, 1999)

MEDIAN SULFATE CONCEN-

 TRATION, IN MILLIGRAMS

 PER LITER 

Less than 330

331 - 660

661 - 990

991 - 1320

Greater than 1321

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
Water-Quality Characteristics of Selected Surface-Water Sites 135

Figure 40. Relation between specific conductance and calcium, sodium, and sulfate concentrations in surface water.

0 2,000 4,000 6,000 8,000 10,000

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

5,500

ION CONCENTRATIONS, IN MILLIGRAMS PER LITER

EXPLANATION

CALCIUM

SODIUM

SULFATE

Calcium=(0.056)(Specific Conductance)-11

R2=0.86

(1655 samples)

Sodium=(0.13)(Specific Conductance)-77

R2=0.90

(1672 samples)

Sulfate=(0.56)(Specific Conductance)-195

R2=0.95

(1295 samples)
136 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 41. Boxplots of selected ions for selected surface-water sites in Rapid Creek Basin.

237 166 11 3 2

20

100

80

60

40

DISSOLVED CALCIUM,

IN MILLIGRAMS PER LITER

06409000 06411500 06412500 06414000 06418900

STATION NUMBER IN DOWNSTREAM ORDER (FIGURE 7A)

231 166 11 3 2

0

250

200

150

100

50

DISSOLVED SULFATE,

IN MILLIGRAMS PER LITER

25th percentile

Single sample

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

EXPLANATION

237 Number of samples
Water-Quality Characteristics of Selected Surface-Water Sites 137

Figure 42. Changes in selected ions at Bear Butte Creek near Deadwood (06437020), 1988-97.

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

1

1,000

2

3

4

5

7

10

20

30

40

50

70

100

200

300

400

500

700

ION CONCENTRATION, IN MILLIGRAMS PER LITER

EXPLANATION

DISSOLVED SOLIDS

SULFATE

SODIUM

Nutrients

Nitrogen occurs in surface water as nitrite 

(NO2

-

), nitrate (NO3

-

), and as ammonium (NH4

+), as 

well as other oxidation states. Nitrate is the form most 

commonly found in oxygenated surface waters. Nitrate 

concentrations in drinking water above 10 mg/L (U.S. 

Environmental Protection Agency, 1994a) can cause 

methemoglobinemia (blue-baby syndrome) in small 

children. Some sources of nitrate in water include 

septic systems, barnyards where animals are confined 

to small areas, fertilizers, impacts from mining 

including explosives and the breakdown of cyanide, as 

well as nitrification associated with in-stream riparian 

systems. 

Summary statistics for selected nutrients are 

presented in table 12, and the significance of the 

various nutrients is described in table 1. Boxplots are 

presented in figure 43 for selected nutrients.

Group Comparisons

Nutrient concentrations for headwater springs 

are relatively low with most concentrations of nitrite 

below the laboratory reporting limit, and nitrate and 

nitrite plus nitrate concentrations much less than the 

MCL of 10 mg/L. For all sites, ammonia concentrations generally are low (less than 1 mg/L), with a few 

concentrations greater than 1 mg/L at exterior sites. 

Phosphate and orthophosphate concentrations generally also are less than 1 mg/L. Nutrient concentrations 

for crystalline core sites generally are higher than headwater springs but similar in magnitude to the other 

groups. The crystalline core sites do, however, have 

several nitrate and nitrite plus nitrate concentrations 

that exceed the MCL. The high concentrations are 

from Annie Creek near Lead (06430800). Nitrite plus 

nitrate concentrations at Annie Creek increased during 

the 1990’s (fig. 44), with the highest concentrations in 

1995 and 1996. Johnson (1992) concluded that mining 

effects were the cause of the higher nitrate levels in 

Annie Creek. Denitrification facilities were put in 

place within the Annie Creek Basin in 1997. Various 

levels of nitrate reduction by these facilities have been 

achieved (South Dakota Department of Environment 

and Natural Resources, 1998b).
138 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 43. Boxplots of concentrations of selected nutrients by surface-water group.

94/24 135/46 7/1 74/6 551/158

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP

DISSOLVED AMMONIA,

IN MILLIGRAMS PER LITER

133/28 139/50 7/0 67/12 1,326/172

DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER 

0.001

100

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

0.001

1,000

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

100

200

500

38/12 116/72 4/2 2/0 229/83

DISSOLVED AMMONIA PLUS ORGANIC NITROGEN,

IN MILLIGRAMS PER LITER

0.01

10

0.02

0.05

0.1

0.2

0.5

1

2

5
Water-Quality Characteristics of Selected Surface-Water Sites 139

Figure 43. Boxplots of concentrations of selected nutrients by surface-water group.--Continued

104/45 134/28 6/4 138/44 1,001/265

DISSOLVED ORTHOPHOSPHATE,

IN MILLIGRAMS PER LITER

136/35 118/24 5/4 38/14 1,065/270

DISSOLVED PHOSPHORUS,

IN MILLIGRAMS PER LITER 

0.0001

10

0.0002

0.0005

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

0.0001

10

0.0002

0.0005

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

25th percentile

Single sample

Highest detection limit

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

EXPLANATION

6/4

Maximum Contaminant Level (mandatory)

 (U.S. Environmental Protection Agency,

 1994a)

Number of samples/Number of samples

 with concentrations below the laboratory

 reporting limit

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
140 Water-Quality Characteristics in the Black Hills Area, South Dakota

Table 12. Summary of concentrations of nutrients in surface water by group

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in milligrams per liter. One 

milligram per liter is approximately equal to one part per million; --, not analyzed or determined; <, less than]

Dissolved constituent Number of 

samples

Number of 

censored 

samples

Mean Median Minimum Maximum

Headwater springs

Nitrate, as N 30 0 0.174 0.18 0.01 0.41

Nitrite, as N 62 54 1-- 1-- <0.01 <0.05

Nitrite plus nitrate, as N 133 28 0.141 0.13 0.01 1

Ammonia, as N 94 24 0.034 0.02 <0.01 0.19

Ammonia plus organic nitrogen, as N 38 12 0.355 0.31 <0.2 1.3

Phosphorus, as P 136 35 0.023 0.01 0.004 0.27

Orthophosphate, as P 104 45 0.012 0.009 0.006 0.06

Crystalline core sites

Nitrate, as N 20 0 1.588 0.139 0.019 14.1

Nitrite, as N 114 92 1-- 1-- 0.001 0.93

Nitrite plus nitrate, as N 139 50 0.950 0.14 <0.005 15

Ammonia, as N 135 46 0.026 0.01 <0.002 0.53

Ammonia plus organic nitrogen, as N 116 72 0.213 0.116 <0.2 2.1

Phosphorus, as P 118 24 0.036 0.02 0.003 0.75

Orthophosphate, as P 134 28 0.027 0.011 <0.001 0.65

Artesian springs

Nitrate, as N 0 0 -- -- -- --

Nitrite, as N 6 6 1-- 1-- <0.01 <0.01

Nitrite plus nitrate, as N 7 0 0.265 0.302 0.15 0.33

Ammonia, as N 7 1 0.081 0.055 <0.01 0.2

Ammonia plus organic nitrogen, as N 4 2 1-- 1-- <0.2 0.25

Phosphorus, as P 5 4 1-- 1-- <0.01 0.05

Orthophosphate, as P 6 4 1-- 1-- <0.01 0.024

Exterior sites

Nitrate, as N 36 0 0.365 0.205 0.01 2

Nitrite, as N 25 16 0.007 0.006 <0.01 0.03

Nitrite plus nitrate, as N 67 12 0.359 0.18 0.01 2

Ammonia, as N 74 6 3.708 0.06 <0.01 206

Ammonia plus organic nitrogen, as N 2 0 0.55 0.55 0.5 0.6

Phosphorus, as P 38 14 0.016 0.010 0.008 0.056

Orthophosphate, as P 138 44 0.020 0.012 0.002 0.23

Other sites

Nitrate, as N 171 0 0.716 0.233 0.003 29

Nitrite, as N 312 182 0.008 0.004 <0.001 0.16

Nitrite plus nitrate, as N 1326 172 0.821 0.2 <0.005 37

Ammonia, as N 551 158 0.083 0.027 <0.002 1.1

Ammonia plus organic nitrogen, as N 229 83 0.464 0.3 0.12 2.3

Phosphorus, as P 1065 270 0.033 0.01 <0.001 3.2

Orthophosphate, as P 1001 265 0.027 0.01 <0.001 3.7

1Percent of censored values is greater than 80 percent. Mean and median are not reported because they are unreliable.
Water-Quality Characteristics of Selected Surface-Water Sites 141

 

Figure 44. Nitrite plus nitrate concentrations in Annie Creek near Lead (06430800), 1988-97.

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

0

16

2

4

6

8

10

12

14

DISSOLVED NITRITE PLUS NITRATE, IN MILLIGRAMS PER LITER

Based on a relatively limited data set, nutrient 

concentrations from the artesian springs are similar to 

other hydrogeologic settings. With ground water 

(primarily from the Madison and/or Minnelusa aquifers) as the source for these springs, the low nutrient 

concentrations provide an indication that at least for 

these limited sites, impacts from septic systems, 

mining, or other nutrient contamination sources are not 

currently taking place to the ground-water system. 

Because major sources of recharge to these regional 

aquifers are the outcrop areas upstream from these 

springs, contamination is a concern, including continued urban development and the placement of rural 

septic systems. Delineation of source-water protection 

areas and education are ongoing efforts by State and 

local governmental agencies.

Exterior sites have low nutrient concentrations 

with the exception of a few high ammonia concentrations. The two ammonia concentrations above 5 mg/L 

were from the Cheyenne River at Edgemont 

(06395000) during January and February of 1975. 

Both concentrations (54 mg/L and 206 mg/L) are more 

than two orders of magnitude higher than monthly 

samples collected prior to and after these samples. 

Possible causes of high ammonia concentrations could 

be related to stagnant/semi-stagnant conditions under 

ice, which causes reducing conditions. With reducing 

conditions, ammonia would be the end-product of the 

breakdown of organic material in the sediments. The 

corresponding pH values were the lowest of record for 

this site, which would be consistent with consumption 

of oxygen and dissolution of carbon dioxide. 
142 Water-Quality Characteristics in the Black Hills Area, South Dakota

The majority of nutrient concentrations from the 

other-sites group are similar to concentrations from the 

hydrogeologic setting groups. Some high nitrate and 

nitrite plus nitrate concentrations occurred at Horse 

Creek near Vale (06436800) during the 1970’s, but 

concentrations decreased by the early 1980’s (fig. 45). 

It is unknown if these levels were due to irrigation or 

farming practices during that time period. Horse Creek 

drains a portion of the irrigated lands that are part of the 

Belle Fourche Irrigation Project. Further sampling 

during the late 1980’s and early 1990’s at Horse Creek 

above Vale (06436760), which is located about 

1.5 miles upstream, indicated concentrations similar to 

those from the early 1980’s at Horse Creek near Vale. 

Slight seasonal trends are apparent at the Horse Creek 

above Vale site with higher concentrations during late 

fall and winter when ground-water discharge from 

alluvial aquifers likely would constitute most of the 

streamflow. Additionally, relatively high nitrate levels 

are not uncommon to the shales in western South 

Dakota (South Dakota Department of Environment and 

Natural Resources, 2000).

Additional Comparisons

 Nutrient concentrations in Rapid Creek 

generally are low but do show a slight increase with 

distance downstream and a notable increase in nitrite 

plus nitrate and orthophosphate from samples at Rapid 

Creek near Farmingdale (06421500) (fig. 46). Limited 

data exist between just above Rapid City to Farmingdale for orthophosphates, so increases may be more 

gradual than indicated by the data. Trends indicate that 

urbanization and/or agricultural practices may be 

affecting Rapid Creek, although concentrations are 

relatively low. 

Figure 45. Nitrite plus nitrate concentrations at Horse Creek near Vale (06436800) and Horse Creek above Vale

(06436760).

1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1991

YEAR

0

40

5

10

15

20

25

30

35

DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

06436800, Horse Creek near Vale

06436760, Horse Creek above Vale
Water-Quality Characteristics of Selected Surface-Water Sites 143

Figure 46. Boxplots of selected nutrients for selected surface-water sites in Rapid Creek Basin.

99/0 133/1 25/4 35/0 0/0 144/0

0

5

4

3

2

1

DISSOLVED NITRITE PLUS NITRATE,

IN MILLIGRAMS PER LITER

06409000 06411500 06412500 06414000 06418900 06421500

STATION NUMBER IN DOWNSTREAM ORDER (FIGURE 7A)

95/43 4/4 134/32 9/2 0/0 218/1

DISSOLVED ORTHOPHOSPHATE,

IN MILLIGRAMS PER LITER 

25th percentile

Highest detection limit

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

EXPLANATION

4/4

4

1

0

2

3

Number of samples/Number of samples

 with concentrations below the laboratory

 reporting limit
144 Water-Quality Characteristics in the Black Hills Area, South Dakota

Trace Elements

Statistical summaries are presented in this section for selected trace elements (table 13). Boxplots 

are presented for those constituents where sufficient 

data were available above laboratory reporting limits 

(fig. 47).

Group Comparisons

Headwater springs generally have low concentrations of trace elements; most have similar concentrations as other groups or slightly higher than the 

crystalline core sites and artesian springs but less than 

exterior sites. For headwater springs, some concentrations exceed SMCL’s and aquatic standards for 

aluminum, copper, iron, lead, silver, and zinc. All of 

the concentrations exceeding standards were from 

Castle Creek above Deerfield Reservoir (06409000; 

samples from this site compose more than 90 percent 

of the headwater springs samples). Dissolved concentrations for aluminum (three at 200 μg/L), iron (one at 

540 μg/L), and manganese (71 μg/L and 60 μg/L) are 

greater than their respective SMCL’s. The maximum 

concentration for silver does not exceed the hardnessdependent aquatic standard. The concentrations of lead 

that are greater than aquatic standards were from 

samples collected during the 1960’s and 1970’s when 

lead contamination in samples was not uncommon. 

Lead contamination often was introduced during the 

collection and analyses of a sample because lead was 

so prevalent in the environment during that timeframe. 

One major source of lead in the environment was 

leaded gasoline. More recent analyses (1990’s) for 

lead along Castle Creek have all yielded concentrations 

less than the laboratory reporting limit of 1 μg/L. 

Three dissolved copper concentrations exceed the 

hardness-dependent aquatic chronic criteria and two 

exceed the hardness-adjusted acute criteria. These 

samples also were from the 1960’s and have higher 

concentrations than samples from the early 1990’s, 

which are at or near the laboratory reporting limit of 

1 μg/L. The four zinc concentrations above 100 μg/L 

are similar in that they occasionally exceeded hardness-dependent aquatic criteria, but more recent sampling indicates that concentrations are within a range of 

1 to 20 μg/L.

Samples from crystalline core sites generally 

have very low concentrations of trace elements but 

have the highest mean and maximum concentration for 

dissolved barium. One dissolved arsenic concentration 

from Elk Creek near Roubaix (06424000) exceeded the 

current MCL of 50 μg/L, and numerous dissolved 

arsenic concentrations (64 percent) are greater than the 

proposed MCL of 10 μg/L. The highest dissolved 

copper concentration (greater than 11 μg/L) does not 

exceed the hardness-dependent aquatic criterion for 

copper. A dissolved iron concentration of 1,700 μg/L 

at Bear Gulch near Hayward (06405800) and a concentration of 330 μg/L at Elk Creek near Roubaix 

(06424000) both are greater than the SMCL for iron. 

Dissolved lead concentrations of 20 μg/L from two 

northern Black Hills sites, Annie Creek near Lead 

(06430800) and Squaw Creek near Spearfish 

(06430898), exceed the action level. Dissolved manganese concentrations greater than the SMCL include 

two samples from Grace Coolidge Creek near the 

Game Lodge (06404998), two samples from Bear 

Gulch near Hayward (06405800), two samples from 

Spring Creek above Sheridan Lake (06406920), and 

one sample from Whitetail Creek at Lead (06436156). 

Trace element concentrations at artesian springs 

generally are very low but limited data are available 

from which comparisons could be made. No standards 

or criteria for trace elements have been exceeded in the 

available samples from artesian springs.

Concentrations of trace elements at exterior sites 

generally are either similar to or higher than concentrations from other hydrogeologic settings. Exterior sites 

have the highest median concentrations for boron, 

chromium, copper, iron, lithium, manganese, selenium, 

silver, strontium, and zinc. Samples from the 1960’s 

and 1970’s from Cheyenne River at Edgemont 

(06395000) had concentrations that exceed the 

SMCL’s for aluminum, iron, and manganese. Copper 

and zinc concentrations do not exceed hardnessdependent aquatic criteria. Two manganese concentrations greater than the SMCL are from Horse Creek 

above Vale. Seven of the nine selenium concentrations 

exceeding the chronic aquatic criteria are from Horse 

Creek above Vale, and two are from Cheyenne River at 

Edgemont. Selenium is present in the Cretaceous-age 

marine shales common to the plains surrounding the 

Black Hills.
Water-Quality Characteristics of Selected Surface-Water Sites 145

Table 13. Summary of concentrations of trace elements in surface water by group

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or determined; <, less than]

Dissolved Constituent Number of 

samples

Number of 

censored 

samples

Mean Median Minimum Maximum

Headwater springs

Aluminum 50 31 17 2.6 <10 200

Arsenic 51 24 0.95 1.0 <1.0 2.0

Barium 69 0 68 64 50 100

Boron 79 16 15 10 1.9 80

Cadmium 47 40 1-- 1-- <1.0 4.0

Chromium 47 29 0.84 0.71 <1.0 2.0

Cobalt 53 51 1

-- 1-- 2.0 3.0

Copper 51 22 3.5 1.0 <1.0 50

Iron 98 6 27 10 <3.0 540

Lead 29 19 1.1 0.29 <1.0 10

Lithium 54 12 7.5 6.0 <4.0 70

Manganese 90 7 10 7.0 0.02 71

Mercury 51 44 1-- 1-- <0.10 0.20

Molybdenum 5 1 1-- 5.0 <1.0 10

Nickel 47 28 1.1 0.47 <1.0 14

Selenium 69 60 1-- 1-- <1.0 4.0

Silver 49 43 1-- 1-- <1.0 11

Strontium 59 0 72 67 40 160

Vanadium 4 0 3.2 2.5 2.0 6.0

Zinc 61 16 41 6.0 <3.0 810

Crystalline core sites

Aluminum 3 2 1-- 1-- <10 10

Arsenic 112 6 15 12 <1.0 68

Barium 93 0 77 82 16 150

Boron 80 36 15 10 <10 130

Cadmium 49 45 1-- 1-- <1.0 3.0

Chromium 70 46 0.82 0.69 <1.0 2.0

Cobalt 17 15 1-- 1-- <3.0 12

Copper 73 42 0.98 0.55 <1.0 17

Iron 135 17 40 12 <3.0 1,700

Lead 62 54 1-- 1-- <1.0 20

Lithium 20 6 8.6 5.0 <4.0 37

Manganese 130 45 18 4.0 <1.0 440

Mercury 76 70 1-- 1-- <0.10 0.3

Molybdenum 2 0 12 11.5 10 13

Nickel 1 0 1

-- 1-- 11 11

Selenium 78 66 1-- 1-- <1.0 3.0

Silver 17 12 0.75 0.42 <1.0 3.0

Strontium 17 0 170 140 48 350

Vanadium 0 0 -- -- -- --

Zinc 91 36 4.9 4.0 <3.0 22
146 Water-Quality Characteristics in the Black Hills Area, South Dakota

Artesian springs

Aluminum 2 0 5.0 5.0 3.3 6.8

Arsenic 6 1 1-- 2.5 <1.0 4.0

Barium 4 0 64 68 18 104

Boron 6 0 120 130 30 210

Cadmium 2 2 1-- 1-- <1.0 <1.0

Chromium 5 3 1

-- 1-- <1.0 2.4

Cobalt 2 2 1-- 1-- <1.0 <1.0

Copper 5 5 1-- 1-- <1.0 <1.0

Iron 3 1 1

-- 5 <3.0 28

Lead 5 5 1-- 1-- <1.0 <1.0

Lithium 0 0 -- -- -- --

Manganese 5 3 1-- 1-- <1.0 11

Mercury 3 3 1-- 1-- <0.10 <0.10

Molybdenum 2 2 1-- 1-- <1.0 <1.0

Nickel 2 2 1-- 1-- <1.0 <1.0

Selenium 6 2 1-- 1-- <1.0 3.0

Silver 2 2 1-- 1-- <1.0 <1.0

Strontium 0 0 -- -- -- --

Vanadium 0 0 -- -- -- --

Zinc 4 0 4.6 4.8 2.0 7.0

Exterior sites

Aluminum 5 3 1-- 1-- <10 740

Arsenic 19 9 1.1 1.0 <1.0 7.0

Barium 0 0 -- -- -- --

Boron 55 0 592 430 10 1,600

Cadmium 20 14 0.94 0.17 <1.0 9.0

Chromium 17 8 1.6 1.3 <1.0 4.0

Cobalt 7 6 00 <1.0 <1.0 3.0

Copper 25 6 9.1 2.0 <1.0 75

Iron 10 0 209 27 4.0 1,900

Lead 11 8 1-- 1-- <1.0 10

Lithium 8 0 201 240 75 320

Manganese 17 0 122 60 2.0 670

Mercury 12 11 1-- 1-- <0.10 0.10

Molybdenum 21 1 3.8 3.0 <1.0 9.0

Nickel 14 0 5.7 4.5 2.0 18

Selenium 20 1 6.7 4.0 <1.0 20

Silver 9 4 0.91 1.0 <1.0 2.0

Strontium 8 0 3,984 3,950 750 8,620

Vanadium 21 2 3.0 2.0 <1.0 15

Zinc 20 1 65 20 <3.0 490

Table 13. Summary of concentrations of trace elements in surface water by group—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or determined; <, less than]

Dissolved Constituent Number of 

samples

Number of 

censored 

samples

Mean Median Minimum Maximum
Water-Quality Characteristics of Selected Surface-Water Sites 147

Other sites

Aluminum 35 14 33 9.4 3.5 281

Arsenic 260 59 2.6 2.0 <1.0 43

Barium 113 0 55 44 15 110

Boron 1322 30 235 160 4.0 2,300

Cadmium 175 151 1-- 1-- <0.10 5.0

Chromium 151 72 1.3 1.0 <1.0 10

Cobalt 44 39 1

-- 1-- <1.0 3.0

Copper 180 58 3.1 1.0 <1.0 100

Iron 255 19 53 21 <2.0 950

Lead 107 69 2.8 0.33 <0.01 57

Lithium 50 0 37 30 4.0 190

Manganese 273 27 90 30 0.06 1,010

Mercury 199 179 1-- 1-- <0.10 5.3

Molybdenum 76 8 5.6 6.0 <1.0 16

Nickel 36 5 7.5 4.5 <1.0 43

Selenium 198 106 2.4 0.83 <1.0 70

Silver 58 46 1-- 1-- <0.20 4.0

Strontium 43 0 1295 330 83 6,700

Vanadium 64 17 1.8 2.0 <1.0 6.0

Zinc 197 62 13 6.0 <0.50 150

1

Percent of censored values is greater than 80 percent or number of samples is less than 7. Mean and/or median are not reported because they are 

unreliable.

Table 13. Summary of concentrations of trace elements in surface water by group—Continued

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in micrograms per liter. One 

microgram per liter is approximately equal to one part per billion; --, not analyzed or determined; <, less than]

Dissolved Constituent Number of 

samples

Number of 

censored 

samples

Mean Median Minimum Maximum
148 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 47. Boxplots of concentrations of selected trace elements by surface-water group.

50/31 3/2 2/0 5/3 35/14

DISSOLVED ALUMINUM,

IN MICROGRAMS PER LITER

69/0 93/0 4/0 0/0 113/0

DISSOLVED BARIUM,

IN MICROGRAMS PER LITER

51/24 112/6 6/1 19/9 260/59

DISSOLVED ARSENIC,

IN MICROGRAMS PER LITER 

0.1

1,000

0.2

0.5

1

2

5

10

20

50

100

200

500

0.1

100

0.2

0.3

0.4

0.5

0.7

1

2

3

4

5

7

10

20

30

40

50

70

0

160

20

40

60

80

100

120

140

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
Water-Quality Characteristics of Selected Surface-Water Sites 149

Figure 47. Boxplots of concentrations of selected trace elements by surface-water group.--Continued

79/16 80/36 6/0 55/0 1,322/30

DISSOLVED BORON,

IN MICROGRAMS PER LITER

51/22 73/42 5/5 25/6 180/58

DISSOLVED COPPER,

IN MICROGRAMS PER LITER

47/29 70/46 5/3 17/8 151/72

DISSOLVED CHROMIUM,

IN MICROSIEMENS PER CENTIMETER 

0.1

100

0.2

0.3

0.4

0.5

0.7

1

2

3

4

5

7

10

20

30

40

50

70

1

10,000

2

5

10

20

50

100

200

500

1,000

2,000

5,000

0.1

1,000

0.2

0.5

1

2

5

10

20

50

100

200

500

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
150 Water-Quality Characteristics in the Black Hills Area, South Dakota

98/6 135/17 3/1 10/0 255/19

DISSOLVED IRON,

IN MICROGRAMS PER LITER

54/12 20/6 0/0 8/0 50/0

DISSOLVED LITHIUM,

IN MICROGRAMS PER LITER

29/19 62/54 5/5 11/8 107/69

DISSOLVED LEAD,

IN MICROGRAMS PER LITER 

1

10,000

2

5

10

20

50

100

200

500

1,000

2,000

5,000

0.0001

100

0.0002

0.0005

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

1

1,000

2

5

10

20

50

100

200

500

Figure 47. Boxplots of concentrations of selected trace elements by surface-water group.--Continued

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
Water-Quality Characteristics of Selected Surface-Water Sites 151

90/7 130/45 5/3 17/0 273/27

DISSOLVED MANGANESE,

IN MICROGRAMS PER LITER

47/28 1/0 2/2 14/0 36/5

DISSOLVED NICKEL,

IN MICROGRAMS PER LITER

5/1 2/0 2/2 21/1 76/8

DISSOLVED MOLYBDENUM,

IN MICROGRAMS PER LITER 

0.01

10,000

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

100

200

500

1,000

2,000

5,000

1

100

2

5

10

20

50

0.1

100

0.2

0.5

1

2

5

10

20

50

Figure 47. Boxplots of concentrations of selected trace elements by surface-water group.--Continued

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
152 Water-Quality Characteristics in the Black Hills Area, South Dakota

69/60 78/66 6/2 20/1 198/106

DISSOLVED SELENIUM,

IN MICROGRAMS PER LITER

59/0 17/0 0/0 8/0 43/0

DISSOLVED STRONTIUM,

IN MICROGRAMS PER LITER

49/43 17/12 2/2 9/4 58/46

DISSOLVED SILVER,

IN MICROGRAMS PER LITER 

0.1

100

0.2

0.5

1

2

5

10

20

50

0.001

100

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

10

10,000

20

50

100

200

500

1,000

2,000

5,000

Figure 47. Boxplots of concentrations of selected trace elements by surface-water group.--Continued

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
Water-Quality Characteristics of Selected Surface-Water Sites 153

61/16 91/36 4/0 20/1 197/62

DISSOLVED ZINC,

IN MICROGRAMS PER LITER

0.1

1,000

0.2

0.5

1

2

5

10

20

50

100

200

500

25th percentile

Single sample

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

EXPLANATION

4/0 Number of samples/Number of samples

 with concentrations below the laboratory

 reporting limit

Secondary Maximum Contaminant Level

 (recommended) (U.S. Environmental

 Protection Agency, 1996)

Highest detection limit

Maximum Contaminant Level (mandatory)

 (U.S. Environmental Protection Agency,

 1996)

Proposed Maximum Contaminant Level

 (U.S. Environmental Protection Agency, 

 2000)

Acute aquatic-life criteria (South Dakota

 Department of Environment and Natural

 Resources, 1998)

Chronic aquatic-life criteria (South Dakota

 Department of Environment and Natural

 Resources, 1998)

Figure 47. Boxplots of concentrations of selected trace elements by surface-water group.--Continued

Action level (U.S. Environmental Protection

 Agency, 1991)

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
154 Water-Quality Characteristics in the Black Hills Area, South Dakota

Concentrations for the other sites are similar to 

the exterior sites, with many of the higher concentrations from older samples including aluminum and lead 

concentrations. Concentrations for the other sites 

exceed various standards, including SMCL’s for 

aluminum, iron, and manganese; the action level for 

lead; and the MCL and aquatic-life criterion for 

selenium.

Arsenic concentrations exceeding the proposed 

MCL occur in surface waters in the Black Hills 

(fig. 47). Arsenic is associated with the mineralogy 

common to the northern Black Hills and with Precambrian metamorphic and igneous rocks (fig. 2) of the 

central core. Sulfide-bearing ore bodies common in the 

northern Black Hills and gold-mining activities have 

resulted in historic loading into the streams of mine 

tailings containing arsenopyrite, which has contributed 

to high arsenic (total and dissolved) concentrations at 

some sites (fig. 48). Arsenic concentrations above 

5 mg/L also occur at exterior sites with exposure to 

Cretaceous-age marine shales (Greene and others, 

1990). Streams with arsenic concentrations greater 

than 10 μg/L include Annie Creek, Battle Creek, Belle 

Fourche River, Cheyenne River, Elk Creek, French 

Creek, Spring Creek, and Whitetail Creek. 

Manganese is another trace element that commonly is found at concentrations greater than its SMCL 

throughout the Black Hills (fig. 49). Median concentrations for manganese range up to 337 μg/L with maximum concentrations as high as 1,010 μg/L (table 13). 

Selenium concentrations generally are higher at sites 

where the streams have exposure to Cretaceous-age 

marine shales (fig. 50) with concentrations greater than 

5 μg/L (aquatic chronic criterion) occurring in 

7 percent of all samples and 11 percent of the exterior 

sites and other-sites group (table 13).

Several samples at Bear Butte Creek near 

Deadwood (06437020) have exceeded the hardnessdependent chronic and/or acute aquatic-life copper 

criteria, generally for samples collected between 

1992-94 (fig. 51). These samples were collected prior 

to additional mining upstream of this site within the 

Strawberry Creek Basin. Insufficient data are available 

to determine if abandoned mines have contributed to 

these high copper concentrations. Concentrations for 

zinc at this site have not exceeded the hardnessdependent aquatic criteria. 

Additional Comparisons

Limited data are available for trace elements 

within the Rapid Creek Basin. A study to examine 

selected trace elements in water, sediment, plants, and 

fish in Rapid Creek from just above the City of Rapid 

City to just below the Rapid City Wastewater Treatment Plant (Williamson and others, 1996) found that 

there generally were slight increases in silver, copper, 

and zinc from upstream to downstream, but little variability in cadmium. Increases in concentrations from 

immediately above to below the Rapid City Wastewater Treatment Plant were consistent with concentrations being added by the Wastewater Treatment Plant.

Radionuclides

Radionuclides are unstable isotopes and have a 

certain probability of decay (Clark and Fritz, 1997). 

Radionuclides exist throughout the environment. Most 

occur naturally like uranium, thorium, radium, and 

radon, while others are mostly or entirely manufactured 

like technetium, plutonium, neptunium, and americium 

(Langmuir, 1997). More than 1,700 radionuclides have 

been identified (Clark and Fritz, 1997).

Radioactive decay series consist of a succession 

of radionuclides each with different decay rates. In 

each decay series, the original elements and each successive “daughter” product disintegrate, forming 

radionuclides until a stable lead isotope is formed. The 

decay rate usually is expressed as a half-life, which is 

the length of time required for one-half the quantity 

present to disintegrate. Uranium (238U and 235U) and 

thorium are the original elements in the three natural 

decay series (Wanty and Nordstrom, 1993) and give 

rise to most of the naturally occurring radioactivity in 

water (Hem, 1985). 

Radioactivity is the release of energy and energetic particles by changes occurring within atomic or 

nuclear structures (Hem, 1985). Radionuclide analyses 

can be expressed in terms of disintegrations per unit 

time (typically in units of picocuries per liter) or in 

mass units (typically in units of micrograms per liter).

Uranium concentrations between 0.1 and 

10 μg/L are common in most natural waters and concentrations greater than 1,000 μg/L can occur in water 

associated with uranium-ore deposits (Hem, 1985). 

Concentrations of radium in natural water generally are 

less than 1 pCi/L. Thorium probably is more abundant 

than uranium in most rocks, but is less soluble, so 

thorium generally has lower concentrations in water.
Water-Quality Characteristics of Selected Surface-Water Sites 155

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Figure 48. Spatial distribution of maximum arsenic concentrations in surface water.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

EXPLANATION

OUTCROP OF INYAN KARA

 GROUP (from Strobel and

 others, 1999)

MAXIMUM ARSENIC CONCEN-

 TRATION, IN MICROGRAMS

 PER LITER 

Less than 5

6 - 10

11 - 35

36 - 50

51 -68

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
156 Water-Quality Characteristics in the Black Hills Area, South Dakota

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Figure 49. Spatial distribution of median manganese concentrations in surface water.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

EXPLANATION

OUTCROP OF INYAN KARA

 GROUP (from Strobel and

 others, 1999)

MEDIAN MANGANESE CON-

 CENTRATION, IN MICRO-

 GRAMS PER LITER 

Less than 50

 51 - 100

 101 - 150

 151 - 200

 201 - 337

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
Water-Quality Characteristics of Selected Surface-Water Sites 157

 

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Figure 50. Spatial distribution of maximum selenium concentrations in surface water.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

EXPLANATION

OUTCROP OF INYAN KARA

 GROUP (from Strobel and

 others, 1999)

MAXIMUM SELENIUM CON-

 CENTRATION, IN MICRO-

 GRAMS PER LITER 

Less than 5

6 - 20

21 - 35

36 - 50

51 - 70

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
158 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 51. Comparison of dissolved copper concentrations to hardness-dependent chronic and acute aquatic-life

criteria for Bear Butte Creek near Deadwood (06437020).

1988 1989 1990 1991 1992 1993 1994

0

35

5

10

15

20

25

30

CONCENTRATION, IN MILLIGRAMS PER LITER

EXPLANATION

HARDNESS-DEPENDENT CHRONIC AQUATIC-LIFE CRITERIA

HARDNESS-DEPENDENT ACUTE AQUATIC-LIFE CRITERIA

DISSOLVED COPPER CONCENTRATION

Summary statistics for selected radionuclides 

including alpha radioactivity as thorium-230, gross 

alpha as uranium, gross beta as cesium-137 and as 

strontium/yttrium-90, radium-226, radium-228, radon222, tritium, and uranium are presented in table 14. 

Boxplots are presented in figure 52 for constituents 

with sufficient data.

Limited radionuclide data are available for 

analysis, especially for the artesian springs and exterior 

sites. Data for most of the radionuclide concentrations 

primarily are from the northern and north-central Black 

Hills and do not show any systematic spatial patterns 

(figs. 53); however, igneous rocks often are a source of 

radionuclides.

Uranium concentrations for crystalline core sites 

are greater than headwater springs, similar to artesian 

springs, and generally lower than the exterior sites and 

the other-sites group. Uranium concentrations for crystalline core sites are very similar to those summarized 

for the Precambrian aquifers. The highest uranium 

concentrations in the study area generally are beyond 

the Inyan Kara outcrop (fig. 54), and probably are due 

to influences from naturally occurring uranium in the 

Cretaceous-age marine shales. Historic uranium 

mining did occur near the Cheyenne River near the 

town of Edgemont. Uranium concentrations have 

exceeded the uranium MCL (table 2) at Iron Draw near 

Buffalo Gap and Horse Creek above Vale.
Water-Quality Characteristics of Selected Surface-Water Sites 159

Table 14. Summary of concentrations for radionuclides in surface water by group

[Results based on data stored in U.S. Geological Survey National Water Information System water-quality database. Results in picocuries per liter except as 

indicated. One microgram per liter (μg/L) is approximately equal to one part per billion; ND, not determined; <, less than]

Constituent Number of 

samples

Number of 

censored 

samples

Mean Median Minimum Maximum

Headwater springs

Alpha radioactivity as thorium-230 3 0 0.7 0.8 0.7 0.8

Gross alpha as uranium-natural 11 3 2.1 1.7 <0.8 6.4

Gross alpha as uranium-natural (μg/L) 39 2 3.8 2.1 <0.6 40

Gross beta as cesium-137 45 0 2.4 1.8 0.7 12

Gross beta as strontium/yttrium-90 45 0 1.9 1.4 0.6 9.8

Radium-226 39 1 0.09 0.08 0.04 0.22

Uranium (μg/L) 32 1 0.97 0.98 0.08 1.9

Crystalline core sites

Alpha radioactivity as thorium-230 10 2 2.3 1.6 <0.6 5.7

Gross alpha as uranium-natural (μg/L) 37 4 3.7 3.3 <0.6 8.4

Gross beta as cesium-137 37 0 3.7 3.6 1.6 7.4

Gross beta as strontium/yttrium-90 37 0 2.9 2.7 1.2 5.5

Tritium 12 0 79 69 51 190

Uranium (μg/L) 15 1 2.4 1.1 <0.4 6.4

Artesian springs

Tritium 3 0 45 61 8 67

Uranium (μg/L) 4 0 2.1 2 1.1 3.4

Exterior sites

Uranium (μg/L) 8 0 17 16 8.6 30

Other sites

Alpha radioactivity as thorium-230 5 0 1.6 1.2 1.1 3.3

Gross alpha as uranium-natural (μg/L) 52 5 2.9 1.6 <0.6 33

Gross beta as cesium-137 52 1 3.2 3.0 <0.6 6.9

Gross beta as strontium/yttrium-90 52 1 2.5 2.4 <0.6 5.4

Radium-228 3 0 4 4 4 4

Radon-222 3 1 ND 100 <80 220

Tritium 11 0 84 82 42 130

Uranium (μg/L) 64 6 8.5 7.0 <1 44
160 Water-Quality Characteristics in the Black Hills Area, South Dakota

Figure 52. Boxplots of concentrations of selected radionuclides by surface-water group.

3/0 10/2 0/0 0/0 5/0

ALPHA RADIOACTIVITY AS THORIUM-230,

IN PICOCURIES PER LITER

45/0 37/0 0/0 0/0 52/1

GROSS BETA AS CESIUM-137,

IN PICOCURIES PER LITER

39/2 37/4 0/0 0/0 52/5

GROSS ALPHA AS URANIUM-NATURAL,

IN MICROGRAMS PER LITER 

0

6

1

2

3

4

5

0

50

10

20

30

40

0

14

2

4

6

8

10

12

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
Water-Quality Characteristics of Selected Surface-Water Sites 161

Figure 52. Boxplots of concentrations of selected radionuclides by surface-water group.--Continued

45/0 37/0 0/0 0/0 52/1

GROSS BETA AS STRONTIUM/YTTRIUM-90

IN PICOCURIES PER LITER

32/1 15/1 4/0 8/0 64/6

URANIUM,

IN MICROGRAMS PER LITER 

0

10

2

4

6

8

0.01

100

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

25th percentile

Single sample

Highest detection limit

Median

75th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3

and more than 1.5 times the

interquartile range outside the quartile

Outlier data value more than 3 times the

interquartile range outside the quartile

EXPLANATION

4/0

Maximum Contaminant Level (mandatory) (U.S.

 Environmental Protection Agency, 2000b)

Number of samples/Number of samples

 with concentrations below the laboratory

 reporting limit

Headwater

springs

Crystalline

core sites

Artesian

springs

Exterior

sites

Other

sites

GROUP
162 Water-Quality Characteristics in the Black Hills Area, South Dakota

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater

Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Figure 53. Spatial distribution of median gross beta as cesium-137 concentrations in surface water.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

EXPLANATION

OUTCROP OF INYAN KARA

 GROUP (from Strobel and

 others, 1999)

MEDIAN GROSS BETA AS

 CESIUM-137, IN PICOCURIES

 PER LITER 

0.7 - 2.1

2.2 - 3.5

3.6 - 5.0

5.1 - 6.3

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
Water-Quality Characteristics of Selected Surface-Water Sites 163

BUTTE CO

LAWRENCE CO MEADE CO

PENNINGTON CO

CUSTER CO

FALL RIVER CO

WYOMING

SOUTH DAKOTA

Whitewood

Spearfish

Maurice

Savoy

Saint

Onge

DEADWOOD

Lead

Galena

Nemo

Central

City

BELLE FOURCHE Minnesela

Newell

Vale

Fruitdale Nisland

STURGIS

Blackhawk

Piedmont

Tilford

Box Elder 

RAPID CITY

Hill City

Hermosa

CUSTER

HOT SPRINGS

Edgemont

Roubaix

Keystone

Hayward

Fairburn

Buffalo Gap

Rochford

Cascade

Springs

Pringle

Wild Ditch

N Fork Rapid Cr

Belle Fourche

Reservoir

FOURCHE

Victoria

Spring

Rapid

Irishman

Hawthorn

Gulch

Canyon

South

Grace Cooli d ge

Cottonwood

Angostura

Reservoir

Iron

Creek

Little

Castle Cr

N Fork Castle Cr

Rhoads Fork

Canyon Red

Bear

Gulch

Creek

Crow

Sheridan

Lake

Stockade

Lake

Deerfield

Reservoir

Pactola

Reservoir

Indian Cr

Horse

Creek

Owl

Creek

BELLE

RIVER

REDWATER

R I VER

Creek

Spearfish

Whitewood

Creek

Creek

Bear

Butte

Elk

Elk

Creek

Creek

Creek

Boxelder

Rapid

Creek

Creek

Creek

Creek

Creek

Creek

Creek

Creek

S. Fork

S. Fork Rapid Cr

Battle

French

Beaver

Creek

Creek

Creek

Creek

Fall R

Hat

Creek

Creek

Horsehead

CHEYENNE

RIVER

Cottonwood

Hay Creek

Spokane

Lame Johnny

Beaver

Creek

Robison

Gulch

Gulch

Castle

Castle

Bear

Reno

Little

Strawberry

Creek

Gulch

H gi gins

Creek

Creek

Cr

Cr

Cr

Cr

East

Creek

Bottom

False

Spearfish

Squaw

Annie

Spearfish

North Canal

Canal

Iron

Draw

Angostura

Canal

Cox Lake

Murray

Ditch

Redwater Canal

Gulch

Sheridan

Lake

Tributary

City

Springs

Inlet

Wind Cave

National Park

CUSTER

STATE

PARK

Wind

Cave

Harney

Peak

x

0 10 20

0 10 20 MILES

KILOMETERS

Figure 54. Spatial distribution of median uranium concentrations in surface water.

Base modified from U.S. Geological Survey digital data, 1:100,000

Rapid City, Office of City Engineer map, 1:18,000, 1996

Universal Transverse Mercator projection, zone 13

OUTCROP OF MADISON LIME-

 STONE (from Strobel and

 others, 1999)

OUTCROP OF MINNELUSA

 FORMATION (from Strobel

 and others, 1999)

EXPLANATION

OUTCROP OF INYAN KARA

 GROUP (from Strobel and

 others, 1999)

MEDIAM URANIUM CONCEN-

 TRATION, IN MICROGRAMS

 PER LITER 

Less than 5

5.1 - 10

10.1 - 15

15.1 - 20

20.1 - 33

104o 45' 103o

30'

15' 103o

30'

44o

45'

15'

44o

45'

30'

43o

15'
164 Water-Quality Characteristics in the Black Hills Area, South Dakota

Summary for Surface-Water Groups in Relation to 

Water Use

Surface-water quality within the Black Hills and 

surrounding area generally is very good but the water is 

hard to very hard. The pH levels of some streams occasionally exceed beneficial-use pH ranges. Most surface water is calcium bicarbonate or calcium 

magnesium bicarbonate type water, with increased 

sodium and sulfate at sites exterior to the outcrop of the 

Minnelusa Formation. Dissolved solids, sodium, 

sulfate, selenium, and uranium concentrations tend to 

be higher exterior to the Black Hills, primarily due to 

influences from the Cretaceous-age marine shales. 

Arsenic concentrations greater than the proposed MCL 

of 10 μg/L can be found in several streams within the 

Black Hills and surrounding plains.

Headwater springs have relatively constant 

discharge, specific conductance, dissolved solids, and 

concentrations of most other constituents. These 

springs rarely show variability and generally do not 

approach drinking-water or beneficial-use criteria with 

the exception of occasional pH levels and temperature. 

Headwater springs have low common ion concentrations, with calcium and magnesium being the dominant 

cations and bicarbonate being the dominate anion. 

Both nutrient and trace element concentrations 

generally are low at headwater springs. 

Crystalline core sites generally show more variability in all physical properties and constituents. 

Temperature and pH occasionally may exceed various 

beneficial-use criteria. Crystalline core sites generally 

have low common ion concentrations, have calcium 

bicarbonate or calcium bicarbonate sulfate type waters, 

and have concentrations that are very similar to samples from the Precambrian aquifers. Some high nitrate 

concentrations greater than the MCL of 10 mg/L occur 

at Annie Creek near Lead and have been attributed to 

mining impacts (Johnson, 1992). Trace element concentrations generally are low with the exception of 

arsenic where 64 percent of samples exceed 10 μg/L; 

however, the samples exceeding are from only 

10 percent of the sites sampled. Samples with high 

arsenic concentrations predominately are from Annie 

Creek, Battle Creek, Elk Creek, French Creek, and 

Whitetail Creek. Iron and manganese concentrations 

that exceed the SMCL’s also occur at some crystalline 

core sites.

Artesian springs have relatively constant discharge and specific conductance at each site but show 

variability between sites. Dissolved solids concentrations greater than the SMCL of 500 mg/L are common 

for these sites, and sulfate concentrations greater than 

the SMCL of 250 mg/L are not uncommon. Artesian 

springs generally have calcium sulfate type waters with 

rock/water interactions in the Minnelusa Formation or 

contact with Spearfish Formation probably being the 

source of sulfate. The artesian springs generally have 

low nutrient and trace element concentrations.

Exterior sites show high variability in discharge, 

specific conductance, and dissolved solids. Low 

dissolved oxygen concentrations occur only at sites 

exterior to the Black Hills where high temperature and 

low flow are occasionally problematic. Exterior sites 

have a mixed water type of calcium magnesium sodium 

sulfate with 66 percent of the samples exceeding 

1,000 mg/L sulfate. Chloride also is much higher at 

these sites. Generally, nutrient concentrations are low 

with the exception of two high ammonia concentrations in the 1970’s. The high ammonia concentrations 

could possibly be due to stagnant/semi-stagnant conditions under ice. Exterior sites also have higher trace 

element concentrations than headwater springs, crystalline core sites, and artesian springs. Some concentrations exceeding the selenium aquatic-life criteria and 

the iron and manganese SMCL’s occur at these sites. 

Radionuclide data are limited, but higher uranium 

concentrations occur at sites exterior to the Inyan Kara 

outcrop.

Other site specific issues occur within the Black 

Hills. Occasionally very low pH levels are recorded 

immediately below abandoned mine sites (Torve, 

1991), but pH levels generally increase to within 

acceptable ranges after mixing with additional stream 

water. Water-quality changes in Bear Butte Creek also 

have been noted for specific conductance, sodium, and 

sulfate after additional mining activities in a tributary 

basin. Bear Butte Creek also had some samples that 

exceeded the acute and chronic copper aquatic-life 

criteria during 1992-94. Arsenic, manganese, and 

selenium are trace elements with geologic sources in 

the Black Hills area, and concentrations greater than or 

near the MCL, SMCL’s, and aquatic-life standards may 

occur.

Historic mining in the northern Black Hills has 

been shown to affect water quality, especially on 

Whitewood Creek (Cherry and others, 1986; Fuller and 

Davis, 1989; Fuller and others, 1988, 1989; Goddard, 

1989a, 1989b; Horowitz and others, 1989; Marron, 

1989; McKallip and others, 1989). High arsenic concentrations in Whitewood Creek have been attributed 
Summary 165

to more than 100 years of mine tailings being dumped 

into the stream. The Belle Fourche and Cheyenne 

Rivers downstream from Whitewood Creek also have 

been affected to lesser extents but were not included in 

the summaries of this report.

Within-basin changes for Rapid Creek followed 

the general trend of increasing concentrations from 

upstream to downstream. Nutrient levels are low but 

show an increase downstream, indicating that land-use 

practices, urban and/or agricultural, may be affecting 

the stream. A report summarizing and examining 

nutrient loading to Canyon Lake (Alliance of Engineers and Architects, 1992) noted a phosphorus source 

upstream of Canyon Lake and indicated that this may 

be the result of septic systems in the area. Effects to 

streams in the Black Hills area may include urban 

sprawl, urban stormwater runoff and point-source 

discharges, agricultural and farming land-use practices, 

and active and abandoned mining activities.

SUMMARY

This report summarizes the water-quality characteristics of ground water and surface water in the 

Black Hills area. Water-quality data for the Black Hills 

Hydrology Study and other studies from October 1, 

1930, to September 30, 1998, were used to identify 

similarities and differences between the major and 

minor aquifers as well as between groups of surfacewater sites. The major aquifers include the Precambrian, Deadwood, Madison, Minnelusa, Minnekahta, 

and Inyan Kara aquifers. The minor aquifers include 

the Spearfish, Sundance, Morrison, Pierre, Graneros, 

Newcastle, and alluvial aquifers. Surface-water sites 

are grouped by hydrogeologic settings, including headwater springs, crystalline core sites, artesian springs, 

and exterior sites. Constituents summarized and 

discussed include physical properties, common ions, 

nutrients, trace elements, and radionuclides. Comparisons of concentration levels are made to drinking-water 

standards for both ground and surface water and to 

beneficial-use and aquatic-life criteria for surface 

water.

Specific conductance generally is low for the 

Precambrian, Deadwood, and Minnekahta aquifers. 

Dissolved constituents tend to increase with residence 

time as indicated by the increase in specific conductance with well depth in the Madison and Minnelusa 

aquifers. Generally, water from the Inyan Kara aquifer 

and the minor aquifers, with the exception of the 

Newcastle aquifer, is higher in specific conductance 

due to shales within the units relative to the other major 

aquifers. Generally, the specific conductance of 

alluvial aquifers increases with increasing distance 

from the core of the Black Hills due to streams flowing 

across units with increasing amounts of shale.

Units that contain few carbonate rocks, such as 

the Precambrian rocks, generally contain water with 

lower carbonate hardness and alkalinity than units that 

are composed primarily of carbonate rocks. Water 

from the Deadwood, Madison, Minnelusa, and 

Minnekahta aquifers generally is hard to very hard. 

The hardness of water from the Inyan Kara aquifer 

ranges from soft to very hard. Hardness in the Inyan 

Kara aquifer decreases with increasing well depth, or 

distance from the outcrop. Water from the minor 

aquifers generally is very hard.

Generally, water from the major aquifers is fresh 

in and near the outcrop areas. The Madison, 

Minnelusa, and Inyan Kara aquifers may yield slightly 

saline water at distance from the outcrops especially in 

the southern Black Hills. Water from all aquifers, with 

the exceptions of the Pierre and Sundance aquifers, 

generally is suitable for irrigation, but may not be in 

specific instances if either the specific conductance or 

sodium-adsorption ratio (SAR) is high.

Many of the major aquifers yield a calcium 

bicarbonate type water in and near outcrop areas, with 

increasing concentrations of sulfate, chloride, and 

sodium with distance from the outcrop. The concentration of sulfate in the Minnelusa aquifer is dependent on 

the amount of anhydrite present in the Minnelusa 

Formation. Sulfate and dissolved solids concentrations 

generally are high in the minor aquifers, with the 

exception of the Newcastle aquifer.

Generally, concentrations of nitrogen and phosphorus are low in water from the aquifers considered. 

The extreme concentrations noted in this study are 

unusually high and may reflect poor well construction 

and surface contamination as opposed to aquifer 

conditions.

In all aquifers considered in this report, strontium generally is higher in concentration than the other 

trace elements. Barium, boron, iron, manganese, 

lithium, and zinc concentrations also may be high in 

comparison to other trace elements. Concentrations 

and variability of many trace elements are low in the 

aquifers. Boron concentrations generally are much 

higher and have larger variability in the minor aquifers 

than in the major aquifers, with generally higher 
166 Water-Quality Characteristics in the Black Hills Area, South Dakota

concentrations in the Inyan Kara aquifer than the other 

major aquifers. The Inyan Kara and Precambrian aquifers generally have lower barium concentrations and 

higher manganese concentrations than the other major 

aquifers. Lithium concentrations generally are much 

lower and have smaller variability in the Precambrian, 

Deadwood, Madison, Minnelusa, and Minnekahta 

aquifers than in the other aquifers. The Sundance 

aquifer has the highest selenium concentrations of all 

aquifers considered in this report. In general, strontium 

concentrations generally are lower and have smaller 

variability in the Precambrian, Deadwood, Madison, 

and Minnekahta aquifers than in the other aquifers. 

In general, gross alpha-particle activity, grossbeta activity, and radium-226, are higher in the Inyan 

Kara and Deadwood aquifers than in the Madison, 

Minnelusa, and Minnekahta aquifers. Radon-222 concentrations are much higher, and thorium and uranium 

concentrations are lower in the Deadwood aquifer than 

in the Madison and Minnelusa aquifers. Radon-222 

concentrations also can be high in alluvial aquifers. 

Uranium concentrations may be high in the Inyan Kara 

aquifer and have considerable variability in the 

Sundance, Morrison, Pierre, Graneros, and alluvial 

aquifers.

Concentrations that exceed the Secondary and 

Maximum Contaminant Levels may affect the use of 

water in some areas for many aquifers within the study 

area. Concentrations that exceed various Secondary 

Maximum Contaminant Levels (SMCL’s) generally 

affect the water only aesthetically. Radionuclide concentrations may be especially high in some of the major 

aquifers used within the study area and preclude the use 

of water in some areas. Hard water may require special 

treatment for certain uses. Other factors, such as the 

sodium-adsorption ratio and specific conductance, 

affect irrigation use. 

High concentrations of iron and manganese are 

the only concentrations that may hamper the use of 

water from Precambrian aquifers. No samples reported 

by this study from the Precambrian aquifers exceed any 

of the drinking-water standards for radionuclides. 

The principal deterrents to use of water from the 

Deadwood aquifer are the high concentrations of radionuclides, including radium-226 and radon-222. In 

addition, concentrations of iron and manganese may be 

high.

Water from the Madison aquifer may contain 

high concentrations of iron and manganese. Water 

from the Madison aquifer is hard to very hard and may 

require special treatment for certain uses. In downgradient wells (generally deeper than 2,000 feet), 

higher concentrations of dissolved solids and sulfate 

occur. In the southern Black Hills, hot water may not 

be desirable for some uses. Radionuclide concentrations in the Madison aquifer generally do not exceed 

drinking-water standards.

The principal properties or constituents in the 

Minnelusa aquifer that may hamper the use of water 

include hardness and high concentrations of iron and 

manganese. Generally, downgradient wells (generally 

deeper than 1,000 feet) also have high concentrations 

of dissolved solids and sulfate. Arsenic may be a 

problem for some wells if the Maximum Contaminant 

Level (MCL) is lowered to 10 μg/L (micrograms per 

liter). A few samples from the Minnelusa aquifer 

exceed the MCL’s for various radionuclides.

Water from the Minnekahta aquifer generally is 

suitable for all water uses because few samples exceed 

SMCL’s or MCL’s. No samples available for this study 

from the Minnekahta aquifer exceed any standards for 

radionuclides. However, water from the Minnekahta 

aquifer is harder than that from any of the other major 

aquifers in the study area.

The principal properties or constituents in the 

Inyan Kara aquifer that may hamper the use of water 

include high concentrations of dissolved solids, iron, 

sulfate, and manganese. In the southern Black Hills, 

radium-226 and uranium concentrations may preclude 

its use. Suitability for irrigation may be affected by 

high specific conductance and the adjusted SAR.

The principal properties or constituents in the 

minor aquifers included in this study that may hamper 

the use of water include hardness, dissolved solids, and 

sulfate concentrations. Concentrations of radionuclides, with the exception of uranium, generally are less 

than MCL’s in samples from the minor aquifers. 

Selenium concentrations from the Sundance aquifer 

exceeded the MCL of 50 μg/L in 2 of 8 samples.

Water from alluvial aquifers generally is very 

hard and may require special treatment for certain uses. 

In wells that overlie the Cretaceous-age shales, the high 

concentrations of dissolved solids, sulfate, iron, and 

manganese may limit the use of water. In the southern 

Black Hills, uranium concentrations are high.

Surface-water quality is influenced to a large 

extent by the geology of the area. Headwater springs 

tend to have very constant water-quality characteristics. Crystalline core sites tend to have more variability 

than the headwater springs. Artesian springs comprise 
Summary 167

much of the base flow for exterior streams beyond the 

Black Hills. Exterior sites have greater fluctuations in 

stream characteristics and water quality. 

Discharge at headwater springs displays little 

variability when compared to other groups with only 

artesian sites having similar flow characteristics. Artesian springs generally have more variability between 

sites, but individual sites do not have large seasonal 

fluctuations. Discharge for crystalline core sites displays wider ranges in variability than headwater 

springs and generally vary with season with increasing 

flows during the spring and summer when snowmelt 

and precipitation result in greater runoff. The greatest 

variability in discharge for the hydrogeologic settings 

occurs at exterior sites, which have much larger 

drainage basins and numerous sources for flow. 

Headwater springs have very stable characteristics of both discharge and specific conductance, while 

at crystalline core sites, specific conductance generally 

decreases as flow increases due to dilution. Specific 

conductance varies considerably from one artesian 

spring to another, however, specific conductance is 

relatively constant at each site. For exterior sites, 

specific conductance generally is much higher than at 

sites in the other hydrogeologic settings with a mean of 

3,400 μS/cm (microsiemens per centimeter) and a 

maximum of 9,250 μS/cm. Strong relations exist 

between discharge and specific conductance at the 

exterior sites.

In some samples, pH levels exceed the SMCL 

and fisheries criteria (coldwater permanent and coldwater marginal) at headwater springs and crystalline 

core sites. Dissolved oxygen generally varies with 

temperature, with lower dissolved oxygen occurring 

during higher temperature periods. For headwater 

springs, 1 percent of the samples exceed the coldwater 

permanent fisheries criterion for temperature. Almost 

12 percent of the temperature measurements for crystalline core sites exceed the coldwater permanent fisheries criterion, and just less than 1 percent exceed the 

coldwater marginal fisheries criterion. Dissolved 

oxygen generally remains above beneficial-use criteria 

although a few dissolved oxygen concentrations below 

4 mg/L (milligrams per liter) have been recorded at 

three sites. Dissolved oxygen measurements of 2.1, 

2.2, and 3.6 mg/L have been measured at an urban 

runoff site within the Rapid Creek Basin, indicating 

that urban runoff situations probably stress aquatic life. 

Two additional sites with low dissolved oxygen 

concentrations are Cottonwood Creek near Buffalo 

Gap and Cheyenne River near Buffalo Gap.

Specific conductance can be closely related to 

dissolved solids concentrations. Headwater springs 

have little variability in both specific conductance and 

dissolved solids with dissolved solids concentrations 

ranging from 147 to 476 mg/L, and specific conductance with a similar minimal range 304 to 705 μS/cm. 

The relation between dissolved solids and specific conductance is much stronger for crystalline core sites, 

artesian springs, and exterior sites where wider ranges 

of specific conductance and dissolved solids exist.

Generally, most surface waters are a calcium 

bicarbonate type water with increased magnesium at 

headwater springs and increased sulfate at crystalline 

core sites. Artesian springs have a calcium sulfate type 

water. Exterior sites generally have sodium calcium 

magnesium sulfate type waters after the streams come 

in contact with the Cretaceous-age marine shales surrounding the Black Hills, which results in increased 

concentrations of sulfate complexed with calcium or 

sodium. In downstream progressions of common ion 

concentrations for Rapid Creek, calcium and sulfate 

increase notably, which is consistent with increased 

exposure to limestone and then Cretaceous-age marine 

shales.

Nutrient concentrations generally are low with 

most concentrations less than or near the laboratory 

reporting limit. Annie Creek near Lead (0640800) had 

increasing nitrite plus nitrate concentrations since the 

1990’s, with the highest concentrations in 1995 and 

1996. Mining impacts were the cause of the higher 

nitrate levels in Annie Creek and denitrification 

facilities were put in place within Annie Creek Basin in 

1997. 

Two high ammonia concentrations were 

measured at Cheyenne River at Edgemont (06395000) 

during January and February of 1975 (54 mg/L and 

206 mg/L). The high ammonia concentrations could 

be related to stagnant/semi-stagnant conditions under 

ice, which causes reducing conditions. With reducing 

conditions, ammonia would be the end-product of the 

breakdown of organic material in the sediments. The 

corresponding pH values were the lowest of record for 

this site, which would be consistent with consumption 

of oxygen and dissolution of carbon dioxide. 

Headwater springs generally have low concentrations of trace elements, although some concentrations exceed SMCL’s and aquatic standards for 

aluminum, copper, iron, lead, and zinc. All concentra-
168 Water-Quality Characteristics in the Black Hills Area, South Dakota

tions exceeding standards were from Castle Creek 

above Deerfield Reservoir (06409000; samples from 

this site comprised over 90 percent of the headwater 

springs samples). Concentrations of copper, lead, and 

zinc exceeding aquatic standards were from samples 

collected during the 1960’s and 1970’s when trace 

element contamination in samples was not uncommon. 

Concentrations in more recent samples from Castle 

Creek have all been less than the aquatic standards. 

For crystalline core sites, there are numerous 

arsenic concentrations (60 percent) greater than 

10 μg/L (proposed MCL), and one sample from Elk 

Creek near Roubaix (06424000) exceeds the current 

MCL of 50 μg/L. Two iron concentrations greater than 

the SMCL and two lead concentrations greater than the 

SMCL have been reported from northern Black Hills 

sites. Several manganese concentrations greater than 

the SMCL also have been reported.

Trace element concentrations at artesian springs 

generally are very low, however, limited data are available from which comparisons can be made. No standards or criteria for trace elements have been exceeded 

in the available samples. Concentrations of trace 

elements at exterior sites generally are either similar to 

or higher than concentrations than other groups. 

Samples from the 1960’s and 1970’s exceeded SMCL’s 

for aluminum, iron, and manganese (possibly the result 

of sample contamination). Seven of the nine selenium 

concentrations exceeding the chronic aquatic criterion 

of 5 μg/L are from Horse Creek above Vale, and two 

are from Cheyenne River at Edgemont. Selenium is 

present in the Cretaceous-age marine shales common 

to the plains surrounding the Black Hills.

Several samples at Bear Butte Creek near 

Deadwood have exceeded the hardness-adjusted 

chronic and acute copper criteria, generally for samples 

collected between 1992-94. These samples were 

collected prior to additional mining upstream of this 

site within the Strawberry Creek Basin. Insufficient 

data are available to determine if abandoned mines 

have contributed to these high copper concentrations.

Limited radionuclide data are available for analysis, especially for artesian springs and exterior sites. 

Data for most of the radionuclides are from the 

northern and north-central Black Hills; however, 

igneous rocks are often a source of radionuclides. Concentrations of gross alpha as uranium are high in two 

samples from Spearfish Creek near Lead (40 pCi/L 

(picocuries per liter)) and Rapid Creek near Rochford 

(33 pCi/L). Uranium concentrations for crystalline 

core sites are very similar to those summarized for samples from Precambrian aquifers. Uranium is the only 

radionuclide with data distribution throughout the 

Black Hills with higher concentrations exterior to the 

outcrop of the Inyan Kara Group. Historic uranium 

mining did occur near the Cheyenne River near the 

town of Edgemont.

Other site specific issues occur within the Black 

Hills. Occasionally very low pH levels are recorded 

immediately below abandoned mine sites but pH levels 

generally increase to within acceptable ranges after 

mixing with additional stream water. Water-quality 

changes in Bear Butte Creek also have been noted for 

dissolved solids, sodium, and sulfate after additional 

mining activities in a tributary basin. Bear Butte Creek 

also had some samples that exceeded the acute and 

chronic copper aquatic-life criteria during 1992-94. 

Arsenic, manganese, and selenium are trace elements 

with geologic sources in the Black Hills area, and concentrations exceeding or near the MCL, SMCL’s, and 

aquatic-life standards may occur. Historic mining in 

the northern Black Hills has been shown to affect water 

quality, especially on Whitewood Creek.

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SUPPLEMENTAL INFORMATION

Supplemental Information — Table 15 175

 Table 15. Ground-water sampling sites summarized in this report

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)

Precambrian wells

442143103472601 5N 3E30DDAA 442143 1034726 5

442016103473401 4N 3E 5BCBC 442016 1034734 1

441612103342201 4N 4E25DDDD 441612 1033422 1

441644103380601 4N 4E28ADDB 441644 1033806 1

441639103410501 4N 4E30CAAA 441639 1034105 1

441344103401201 3N 4E 8CCAD 441344 1034012 1

441048103361401 3N 4E35BADB 441048 1033614 1

441142103301801 3N 5E27BAC 441142 1033018 1

440852103420501 2N 3E12ACDD 440853 1034201 1

440722103430401 2N 3E23AABC 440722 1034304 1

440607103440901 2N 3E27DABD 440607 1034409 1

440827103342601 2N 4E12DDDA 440827 1033426 1

440834103271401 2N 5E12DDBB 440834 1032714 1

440509103334601 2N 5E31DBCB 440509 1033346 1

440755103451801 2N 6E16DAAB 440755 1034518 1

440458103261601 2N 6E31DC3 440458 1032616 1

440456103255701 2N 6E31DDDD 440456 1032557 2

440456103255702 2N 6E31DDDD2 440456 1032557 2

440115103465101 1N 3E29ABDB 440115 1034651 1

440010103422801 1N 3E36BDCB 440010 1034228 1

440451103383801 1N 4E 4ABBB 440451 1033836 1

440339103391401 1N 4E 8ADD 440339 1033914 1

440007103383401 1N 4E33ACCC 440007 1033834 1

440248103321601 1N 5E17ADC 440248 1033216 1

440223103321701 1N 5E17DDC 440223 1033217 4

440003103301001 1N 5E34DBBB 440003 1033010 1

440550103255801 1N 6E 6AAAA 440550 1032558 3

435927103494801 1S 2E 1CBAA 435920 1034955 1

435916103463301 1S 3E 5DADD 435916 1034633 1

435642103433701 1S 3E23CADB 435642 1034337 1

435916103414201 1S 4E 6CBCC 435916 1034142 1

435709103370801 1S 4E24ABCC 435709 1033708 2

435616103344801 1S 4E25AACA 435616 1033448 1

435446103381601 1S 4E33DDAC 435446 1033816 1

435916103342201 1S 5E 6CBDC 435916 1033422 1

435549103342001 1S 5E30DABD 435602 1033346 1

435515103313001 1S 5E33ACBA 435515 1033130 1
176 Water-Quality Characteristics in the Black Hills Area, South Dakota

Precambrian wells—Continued

435645103211801 1S 6E 4CBAB 435922 1032504 1

435837103244601 1S 6E 9BDCB 435837 1032446 1

435837103204201 1S 6E12ACDC 435837 1032042 1

435657103221801 1S 6E22ADDD 435657 1032218 1

435642103233401 1S 6E22CACB 435642 1032334 1

435930103184401 1S 7E 5BACD 435930 1031844 2

435927103185201 1S 7E 5BCAA 435927 1031852 1

435327103351601 2S 4E12BDAD 435327 1033516 1

434948103413801 2S 4E31CBBD 434948 1034138 1

435356103320601 2S 5E 4CCAB 435356 1033206 1

435338103285801 2S 5E11ABDA 435338 1032858 1

435206103273701 2S 5E13DDD 435206 1032737 1

435428103224101 2S 6E 2BC 435428 1032241 4

435404103245501 2S 6E 4CC 435404 1032455 2

435300103265601 2S 6E 7CD 435300 1032656 1

435300103265001 2S 6E 7CDD 435300 1032650 1

435230103254502 2S 6E 8CAD2 435230 1032545 2

435230103254501 2S 6E 8CADA 435230 1032545 1

435334103233401 2S 6E10BACC 435339 1032329 1

435242103261801 2S 6E18ADDDB 435234 1032624 1

434752103380201 3S 4E10CCAC 434752 1033802 1

434742103351301 3S 4E12CDDD 434742 1033513 1

434616103354301 3S 4E24CBCD 434616 1033543 3

434604103362301 3S 4E24CDDC 434604 1033623 1

434555103363601 3S 4E26BA 434550 1033640 2

434549103363701 3S 4E26BACD 434549 1033637 6

434527103374101 3S 4E27CADA 434527 1033741 2

434521103380601 3S 4E27CBCD 434521 1033806 1

433531103371501 3S 4E27DABD 433531 1033715 2

434536103384702 3S 4E28 434534 1033843 2

434420103391401 3S 4E33CCDB 434420 1033914 1

434445103344801 3S 4E36ADCA 434445 1033448 1

434752103311901 3S 5E 9DDBC 434752 1033119 1

434438103311501 3S 5E33DABA 434438 1033115 1

434644103240001 3S 6E21AAAC 434644 1032400 1

434210103394601 4S 4E17ACDA 434210 1033946 1

434200103410201 4S 4E18DBBD 434200 1034102 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
Supplemental Information — Table 15 177

Precambrian wells—Continued

434113103363201 4S 4E23BDDC 434113 1033632 1

434018103373101 4S 4E27DBB 434018 1033731 1

434007103371901 4S 4E27DDBB 434007 1033719 1

433923103380501 4S 4E34CB 433923 1033805 1

434236103303201 4S 5E10CDBB 434236 1033032 1

434257103282601 4S 5E12BCDC 434257 1032826 1

433834103320601 5S 5E 4BCDD 433834 1033206 1

433657103322701 5S 5E17ADAC 433657 1033227 1

433444103300001 5S 5E27DDDD 433444 1033000 1

Deadwood wells

442102103552201 5N 2E31ACC 442111 1035508 1

442118103553401 5N 2E31BCBB 442120 1035546 1

442053103503901 5N 2E35CC 442053 1035039 2

442356103482501 5N 3E18BBCB 442356 1034825 1

442058103441201 5N 3E34DBC 442058 1034412 1

442340103393201 5N 4E17CAAD 442335 1033937 1

442200103370001 5N 4E27ACDC 442200 1033700 1

441938103475701 4N 3E 7AACB 441938 1034757 1

441920103420801 4N 3E12CAAD 441913 1034217 1

441758103465801 4N 3E17DBCB 441819 1034701 1

441803103465501 4N 3E17DCCA 441805 1034658 1

441648103481401 4N 3E30BDAD 441648 1034814 1

441431103315801 3N 5E 9BAB 441428 1033139 1

440811103222202 2N 6E15ADAA2 440811 1032222 1

440816103261801 2N 6E18ADAA 440809 1032601 1

440824103260201 2N 6E18ADBA 440810 1032607 1

440606103212701 2N 6E26DBDA 440606 1032127 1

440530103190101 2N 7E31ACAD 440539 1031916 1

440052103181201 1N 7E29CADD 440053 1031810 1

440049103194401 1N 7E30CBDD 440049 1031944 1

440003103185001 1N 7E31AAAB 440033 1031850 1

440034103190001 1N 7E31ABAA 440034 1031900 1

440025103190701 1N 7E31ABDC 440025 1031907 1

440032103191201 1N 7E31BAAB 440032 1031912 1

440019103181801 1N 7E32BDBB 440019 1031818 1

440002103181401 1N 7E32CA 440002 1031814 1

435959103181301 1N 7E32CADB 435959 1031813 1

435850103193001 1S 7E 7ACA 435850 1031930 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
178 Water-Quality Characteristics in the Black Hills Area, South Dakota

Deadwood wells—Continued

435830103200001 1S 7E 7CB 435830 1032000 1

435835103175001 1S 7E 9CBBD 435835 1031750 1

435641103195801 1S 7E19CCAA 435641 1031958 1

435206103194501 2S 7E18CA 435206 1031945 1

435212103200201 2S 7E18CCAD 435212 1032007 1

434406103503301 4S 2E 2ABD 434406 1035033 1

434407103461401 4S 3E 4BBDB 434408 1034626 1

Madison wells

444128103514701 9N 2E34CDD 444128 1035147 1

444129103514801 9N 2E34CDDCA 444129 1035148 1

444320103471801 9N 3E20CC 444320 1034718 1

444312103465901 9N 3E20CDDD 444313 1034653 1

444116103510301 8N 2E 3AAC 444116 1035103 1

443716103522501 8N 2E28DDCB 443716 1035225 1

444114103323901 8N 5E 5BCAB 444114 1033239 1

443511103575801 7N 1E11BCAD 443511 1035758 1

443210104021601 7N 1E30DDAB 443210 1040216 1

443100104002001 7N 1E33CCDD 443104 1040025 1

443227103503401 7N 2E26BDB 443227 1035034 1

443148103534001 7N 2E32AACC 443148 1035340 1

442842103505501 6N 2E14CBCC 442842 1035055 1

442919103511601 6N 2E15BBBB 442917 1035206 4

442802103544601 6N 2E19DABA 442759 1035449 1

442822103534501 6N 2E20ABAB2 442822 1035345 1

442435103571101 5N 1E11DABA 442435 1035711 1

442504103415301 5N 3E 1DCCB 442504 1034153 1

442335103311001 5N 5E16CAAD 442336 1033111 1

442217103272201 5N 5E26ABDA 442215 1032829 1

442024103545701 4N 2E 6AACD 442024 1035457 1

441749103515701 4N 2E22BACB 441749 1035157 1

441759103261202 4N 6E19AABA2 441759 1032612 1

441355103230901 3N 6E10CDBB 441355 1032309 1

441337103225002 3N 6E15ABB2 441335 1032250 1

441055103230501 3N 6E34BA 441055 1032305 3

441033103210301 3N 6E35ADDA 441040 1032107 1

440811103222201 2N 6E15ADAA 440811 1032221 1

440708103214301 2N 6E23BDD 440708 1032143 1

440541103211401 2N 6E35AADA 440541 1032114 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
Supplemental Information — Table 15 179

Madison wells—Continued

440527103220401 2N 6E35BCAB 440527 1032204 1

440931103141401 2N 7E 2DBDD 440931 1031414 1

440808103193701 2N 7E18BCA 440808 1031937 1

440655103140501 2N 7E23DACD 440655 1031407 1

440612103152001 2N 7E27DABB 440612 1031522 1

440541103192301 2N 7E31BADA 440541 1031923 1

440500103193601 2N 7E31CCCA 440458 1031950 1

440500103195001 2N 7E31CCCA2 440500 1031950 1

440544103180002 2N 7E32ABBD2 440543 1031805 1

440526103173001 2N 7E32ADDD 440526 1031730 2

440519103160701 2N 7E34CBAA 440519 1031607 1

440850103045001 2N 8E13BDC 440801 1030616 2

440650103110001 2N 8E20CCCD 440641 1031120 3

440851103044801 2N 9E 7CDCC 440855 1030510 4

440629103040901 2N 9E29BBCC 440629 1030409 1

440032103195901 1N 6E36AAAB 440032 1031959 3

440427103131701 1N 7E 1DBBB 440427 1031317 1

440446103161701 1N 7E 3BBCC 440445 1031616 2

440443103161301 1N 7E 3BBCD 440443 1031613 1

440430103160202 1N 7E 3CBAA2 440430 1031602 1

440338103173302 1N 7E 8ADDD2 440338 1031733 1

440310103173802 1N 7E 8DDCD2 440312 1031740 1

440342103160701 1N 7E10BCDB 440342 1031609 1

440220103164001 1N 7E16DCDC 440220 1031640 2

440300103173501 1N 7E17AAAC2 440305 1031739 4

440223103173201 1N 7E17DDDA 440225 1031734 2

440308103184601 1N 7E18AAAD 440308 1031847 1

440205103172001 1N 7E21BCAB 440205 1031720 1

440032103184601 1N 7E30DDDC 440032 1031846 1

440026103194001 1N 7E31BBDA 440026 1031940 1

440002103173901 1N 7E32DA2 440002 1031739 2

435916103161801 1S 7E 3CDBD 435915 1031620 1

435851103143501 1S 7E11ACAB 435848 1031445 1

435227103185301 2S 7E17CCAA 435227 1031852 1

434700104021401 3S 1E18DDDB 434701 1040215 1

434846103481801 3S 3E 6DCBB 434846 1034818 1

434402103502301 4S 2E 2ADB 434402 1035023 2

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
180 Water-Quality Characteristics in the Black Hills Area, South Dakota

Madison wells—Continued

434350103201901 4S 6E 1DAAA 434350 1032020 1

433517103534201 5S 2E28BCCB 433517 1035342 1

433849103442701 5S 3E 3ADBB 433849 1034427 1

433852103384901 5S 4E 4ABCB 433852 1033849 1

433607103383401 5S 4E21ACAD 433607 1033834 1

433506103344001 5S 4E25DAAA 433510 1033445 1

433000103393901 6S 4E29ADCA 433000 1033939 1

433114103281601 6S 5E24BAAA 433114 1032816 1

433150103230501 6S 6E15ABDD 433150 1032305 3

433115103251401 6S 6E21BBBB 433115 1032516 1

432548103414801 7S 4E19BCCB 432545 1034151 1

432616103294702 7S 5E14CBDD2 432616 1032947 1

432603103295901 7S 5E 14CCCC 432603 1032959 1

432136103321001 8S 5E16BBAD 432136 1033210 1

431810103491701 9S 2E 1AABC 431810 1034917 3

431804103492101 9S 2E 1ABDD 431804 1034921 1

431753103492601 9S 2E 1ACDB 431753 1034926 2

431750103500301 9S 2E 1BCDC 431750 1035003 6

431743103501501 9S 2E 2DAAA 431743 1035015 5

431232103513501 10S 2E 3DAA 431232 1035135 3

431218103512501 10S 2E 3DADD 431218 1035125 1

431220103514001 10S 2E 3DDAA 431220 1035140 1

Minnelusa wells

444253103440001 9N 3E27ADBD 444253 1034359 3

444108103432201 8N 3E 2BDBC 444108 1034322 2

443655103482001 8N 3E31ACA 443650 1034744 2

443627103460301 8N 3E33CCB 443625 1034555 2

443515103572501 7N 1E11ACAC 443508 1035730 2

443339103575701 7N 1E14CCD 443339 1035757 1

443355103574501 7N 1E14CCDD 443343 1035802 1

443320104004501 7N 1E20AAD 443328 1040045 3

443320104003501 7N 1E21BBC 443334 1040035 1

443215103573001 7N 1E26ACD 443215 1035730 1

443240104024001 7N 1E30AAAD 443240 1040155 1

443330104024501 7N 1E30CADD 443230 1040241 1

443150104020001 7N 1E30DDDC 443156 1040205 2

443153104015101 7N 1E32BBBB 443153 1040151 1

443100104002002 7N 1E33CCDD2 443104 1040025 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
Supplemental Information — Table 15 181

Minnelusa wells—Continued

443603103494001 7N 2E 1BBC 443603 1034940 1

443553103502101 7N 2E 2CACA 443553 1035021 2

443108103530601 7N 2E 4BD 443108 1035306 2

443010103523001 7N 2E 9ABAB 443010 1035230 4

443515103513901 7N 2E10BADC 443513 1035143 2

443423103510801 7N 2E15AADC 443423 1035108 1

443330103520301 7N 2E15CC 443348 1035203 1

443355103553001 7N 2E18CA 443359 1035532 1

443420103551001 7N 2E19CAAA 443315 1035514 1

443318103532701 7N 2E20ADD 443318 1035327 1

443323103515501 7N 2E22BCA 443324 1035158 2

443255103502501 7N 2E23CDAB 443300 1035028 1

443230103504101 7N 2E26BCDA 443230 1035041 2

443240103531002 7N 2E29AA2 443240 1035310 1

443215103533001 7N 2E29D 443215 1035330 1

443117103541301 7N 2E32BAC 443147 1035413 1

443124103531601 7N 2E33CBCD2 443124 1035316 1

443515103473001 7N 3E 7AABA 443525 1034732 1

443124103433401 7N 3E35CB 443124 1034334 1

443032103575001 6N 1E 2CABC 443032 1035750 1

443019103523101 6N 2E 4DCAD 443019 1035231 4

443100103543001 6N 2E 5BBBB 443104 1035437 1

442930103522001 6N 2E 9D 442930 1035220 1

442937103511201 6N 2E10DACB 442937 1035112 1

442906103504201 6N 2E14BBCC 442906 1035042 1

442906103510501 6N 2E15AADC 442906 1035105 1

442802103544601 6N2E19DABA 442759 1035449 1

442857103513401 6N 2E22ABBB 442827 1035132 1

442820103503501 6N 2E23BBBA 442820 1035035 1

442721103493701 6N 2E25BBCB 442721 1034937 1

442917103462901 6N 3E17ABAA 442917 1034629 2

442749103381401 6N 4E21DBCD 442749 1033814 4

442901103281601 6N 5E14ADBD 442901 1032816 1

442754103220801 6N 6E22DABD 442754 1032208 1

442545103343701 5N 4E 1ABBD 442544 1033437 1

442515103340401 5N 4E 1DAAD 442515 1033404 1

442306103352001 5N 4E23AAAD 442306 1033520 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
182 Water-Quality Characteristics in the Black Hills Area, South Dakota

Minnelusa wells—Continued

442533103324801 5N 5E 5BBCB 442533 1033248 2

442502103325401 5N 5E 5CC 442511 1033238 4

442435103320301 5N 5E 8ACDD 442435 1033203 1

442443103312701 5N 5E 9BCAA 442443 1033127 4

442431103314101 5N 5E 9CBCC 442431 1033141 2

442337103303501 5N 5E16DAA 442337 1033035 5

442311103303501 5N 5E21AAA 442311 1033035 2

442148103273801 5N 5E25CADB2 442148 1032738 2

442111103265701 5N 5E36ADDA 442111 1032657 3

441807103235601 4N 6E16DCAC 441807 1032356 1

441812103230501 4N 6E16DCB 441812 1032405 1

441759103261201 4N 6E19AABA 441759 1032612 1

441303103232601 3N 6E10CBBA 441303 1032326 2

441311103220801 3N 6E14CBAB 441311 1032208 3

441247103220701 3N 6E14CCDD 441247 1032207 2

441337103225001 3N 6E15ABB 441335 1032250 1

441208103205001 3N 6E24C 441208 1032050 3

441318103221301 3N 6E24CADD 441207 1032033 1

441127103195801 3N 6E25ADDC 441127 1031958 1

441130103205601 3N 6E25BCDC 441130 1032056 3

441028103200401 3N 6E36DA 441028 1032004 4

441033103193001 3N 7E31CAA 441033 1031930 2

441023103194401 3N 7E31CBDD 441023 1031944 1

440920103210401 2N 6E 1CCCD 440920 1032104 2

440919103210201 2N 6E 1CCCD2 440919 1032102 1

440939103142001 2N 7E 2DBDD 440939 1031420 1

440919103170501 2N 7E 4CDCD 440920 1031658 1

440901103184801 2N 7E 7ADAB 440901 1031848 4

440907103183501 2N 7E 8BBCD 440907 1031835 3

440833103184101 2N 7E 8CCBC 440833 1031841 2

440826103174701 2N 7E 8DDCC2 440826 1031747 1

440824103160401 2N 7E10CCDC 440824 1031604 1

440832103160901 2N 7E10CDCA 440837 1031609 1

440818103180801 2N 7E17BAAD 440819 1031809 1

440817103181701 2N 7E17BACA2 440817 1031817 2

440738103173601 2N 7E17DDDB 440738 1031736 2

440647103183201 2N 7E20CCDB 440647 1031832 2

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
Supplemental Information — Table 15 183

Minnelusa wells—Continued

440516103194001 2N 7E31CDCB 440501 1031933 1

440544103180001 2N 7E32ABBD 440544 1031800 1

440538103161201 2N 7E34BBBC 440538 1031612 1

440528103161001 2N 7E34BCCA 440528 1031610 3

440528103155201 2N 7E34BDAD 440528 1031552 1

440504103161501 2N 7E34CCBC 440504 1031615 3

440730103112001 2N 8E17CCCD 440730 1031120 1

440452103155301 1N 7E 3BABD 440452 1031553 1

440436103161201 1N 7E 3BCBC 440436 1031612 1

440430103160201 1N 7E 3CBAA 440430 1031602 4

440414103164601 1N 7E 4DCB2 440414 1031646 4

440338103173301 1N 7E 8ADDD 440338 1031733 1

440310103173801 1N 7E 8DDCD 440312 1031740 1

440351103171301 1N 7E 9BBCA 440351 1031713 3

440338103171601 1N 7E 9BCDC 440338 1031716 3

440331103171601 1N 7E 9CBAC 440331 1031716 1

440225103160801 1N 7E15CC 440225 1031608 2

440300103165801 1N 7E16BADB 440300 1031658 1

440237103173401 1N 7E17DADA 440237 1031734 1

440307103193001 1N 7E18BABB 440307 1031930 1

440202103164101 1N 7E21ACA 440202 1031641 3

440142103164301 1N 7E21DBDB 440142 1031643 2

440130103163401 1N 7E21DDC 440130 1031634 1

440213103153401 1N 7E22AB 440213 1031534 1

440140103152601 1N 7E22D 440140 1031526 1

440203103143601 1N 7E23BDAB 440203 1031436 1

440148103150001 1N 7E23CBBA 440148 1031500 1

435916103161802 1S 7E 3CDBD2 435915 1031620 1

435845103163401 1S 7E10BCAC 435845 1031634 1

435042103171101 2S 7E28DB 435042 1031711 1

435018103155801 2S 7E34ABBA 435018 1031558 1

435004103161301 2S 7E34BD 435004 1031613 1

434700104021402 3S 1E18DDDB2 434701 1040215 1

434503103183601 3S 7E32BABA 434503 1031836 1

434502103165801 3S 7E33AACB 434502 1031658 1

434326103555101 4S 2E 6CCDC 434326 1035551 1

434351103461501 4S 3E 4BCDA 434351 1034615 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
184 Water-Quality Characteristics in the Black Hills Area, South Dakota

Minnelusa wells—Continued

434218103463701 4S 3E17ADAB 434218 1034637 1

434350103201902 4S 6E 1DAAA2 434350 1032020 1

434236103201601 4S 6E12DDAD 434236 1032016 1

434001103131301 4S 7E25DDDB 434001 1031313 1

433545103502701 5S 2E23DCAB 433545 1035027 1

433517103534202 5S 2E28BCCB2 433517 1035342 1

433831103475201 5S 3E 6DAAC 433831 1034752 1

433440103465501 5S 3E32ABAB 433440 1034655 1

433628103173801 5S 7E16CDCA 433628 1031738 1

432927103520401 6S 2E34BA 432927 1035204 1

432927103521001 6S 2E34BABC 432927 1035210 1

432917103522101 6S 2E34BC 432917 1035221 2

433003103420701 6S 3E25ADDC 433000 1034158 2

433347103385101 6S 4E 4BADA 433343 1033857 1

433339103385601 6S 4E 4BADD 433339 1033856 1

433119103360001 6S 4E14DDAC 433119 1033600 1

433021103273601 6S 5E24DDDD 433021 1032736 1

432945103323801 6S 5E29DBDA 432945 1033238 1

433303103225801 6S 6E 3DDCA 433303 1032258 1

433115103251402 6S 6E21BBBB2 433115 1032516 1

432548103414802 7S 4E19BCCB2 432545 1034151 1

432808103294901 7S 5E 2CBAB 432808 1032949 1

432616103294701 7S 5E14CBDD 432616 1032947 2

432616103294702 7S 5E14CBDD2 432616 1032947 2

432622103291501 7S 5E14DBC 432622 1032915 1

432537103301401 7S 5E22ADBC 432537 1033014 1

432523103305401 7S 5E22CDCB 432523 1033054 1

432510103304801 7S 5E22CDCD 432510 1033048 2

432459103290101 7S 5E26AACA 432459 1032901 2

432127103325601 8S 5E17ACBB 432127 1033256 1

Minnekahta wells

443310104024501 7N 1E30BDA2 443230 1040242 2

443100104002003 7N 1E33CCDD3 443104 1040025 1

443253103515401 7N 2E22CCDB 443253 1035154 1

443213103530001 7N 2E28C 443213 1035300 1

443230103541501 7N 2E30AD 443230 1035415 1

443151103543601 7N 2E31AA 443151 1035436 3

443043103521801 6N 2E 4ADDB 443043 1035218 4

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
Supplemental Information — Table 15 185

Minnekahta wells—Continued

443101103530601 6N 2E 4BBAA 443101 1035306 2

443023103521301 6N 2E 4DDAA 443023 1035213 2

443024103522601 6N 2E 4DDBB 443024 1035226 2

443100103543002 6N 2E 5BBBB2 443104 1035437 1

442950103535801 6N 2E 8ACCC 442950 1035358 3

442634103425701 6N 3E35ABAB 442634 1034257 1

440740103174601 2N 7E17DDBC 440740 1031746 2

433115103251403 6S 6E21BBBB3 433115 1032514 1

432619103283501 7S 5E13CBDA 432619 1032835 1

Inyan Kara wells

444337103363001 9N 4E22DAAA 444337 1033630 5

444213103244601 9N 6E32ABBA 444217 1032449 4

444213103244602 9N 6E32ABBA2 444213 1032446 6

444046103504501 8N 2E 2CCAA 444046 1035045 3

443859103502801 8N 2E14CDD 443859 1035028 1

443905103501201 8N 2E14DC 443905 1035012 1

443855103521501 8N 2E16DDD 443855 1035215 1

443835103492001 8N 2E24BCAD 443835 1034920 3

443649103522001 8N 2E33ADCA 443649 1035220 2

444006103415201 8N 3E12 444006 1034152 1

444011103415302 8N 3E12 (2) 444011 1034153 5

444120103365301 8N 4E 3ABDB 444120 1033653 3

444035103330301 8N 5E 7AABA 444035 1033303 2

444024103330801 8N 5E 7AACC 444024 1033308 1

444020103323001 8N 5E 8BCB2 444020 1033230 1

443723103240701 8N 6E28CCAB 443721 1032414 4

443347103474701 7N 3E18DBCD 443352 1034754 1

443244103431501 7N 3E26BA 443244 1034315 1

443245103434001 7N 3E26BAAA 443245 1034312 4

443557103360401 7N 4E 2BDAC 443558 1033559 1

443451103403801 7N 4E 7CDCA 443435 1034053 1

443228103203701 7N 6E25BC 443228 1032037 2

442804103330401 6N 5E19AAAC 442804 1033304 1

442755103302501 6N 5E21DABA 442758 1033041 2

442545103291501 6N 5E22DDBC 442743 1032930 2

442708103311401 6N 5E28ADA2 442719 1033035 1

442038103240001 5N 6E33CDCD 442038 1032400 1

442027103235501 4N 6E 4ABD 442027 1032355 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
186 Water-Quality Characteristics in the Black Hills Area, South Dakota

Inyan Kara wells—Continued

441820103205801 4N 6E13BBBC 441850 1032105 1

441839103204901 4N 6E14BACC 441839 1032049 1

441834103232501 4N 6E25ACAB 441655 1032020 1

441345103210701 3N 6E12CCCB 441345 1032107 1

441219103090801 3N 8E21DAAD 441222 1030904 1

440949103140401 2N 7E 2ACAD 440949 1031404 1

440953103140801 2N 7E 2ADBC 440953 1031408 2

440941103052701 2N 8E 1DABB 440941 1030527 2

440735103105601 2N 8E17CDD 440735 1031056 1

440641103103501 2N 8E20DCDD 440641 1031035 3

440610103085201 2N 8E27CBBA 440610 1030852 1

440831103040801 2N 9E 8CDBA 440837 1030406 3

440640103041501 2N 9E19DDDD 440640 1030415 3

440330103094901 1N 8E10DAAA 440330 1030753 1

440330103080001 1N 8E10DADD 440326 1030753 3

435725103134001 1S 7E13DCBC 435725 1031340 1

435746103045101 1S 9E18ADCA 435746 1030451 1

435127103125201 2S 8E19CCCC 435127 1031252 1

434958103114901 2S 8E32BCBC 434958 1031149 1

434830103134301 3S 7E 1CAAD 434858 1031347 1

434832103150501 3S 7E11ABAD 434834 1031442 1

434752103130801 3S 7E12DDAD 434752 1031308 1

434638103135601 3S 7E24BDB 434638 1031356 1

434424103154601 3S 7E34DCAA 434424 1031546 1

434803103103501 3S 8E 9CBC 434803 1031035 1

434633103084401 3S 8E22ACDB 434633 1030844 1

434620103090601 3S 8E22CA 434620 1030906 1

434557103123201 3S 8E30BAAB 434557 1031232 1

433931103114401 4S 8E32BCDC 433933 1031144 1

433928103113801 4S 8E32BCDC3 433928 1031138 1

433350104030301 5S 1E31CCCD 433350 1040303 1

433720103192301 5S 7E18AAAB 433720 1031923 1

433224104021301 6S 1E 7DACA 433224 1040213 1

433158104021601 6S 1E18AACB 433158 1040216 1

433144104022701 6S 1E18ACDB 433144 1040227 1

433151104021601 6S 1E18ADBB 433151 1040216 1

433144104021601 6S 1E18ADCB2 433144 1040216 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
Supplemental Information — Table 15 187

Inyan Kara wells—Continued

433144104020901 6S 1E18ADDB 433144 1040209 1

433140104021301 6S 1E18DABA 433140 1040213 1

433054104024901 6S 1E19BDCA 433054 1040249 1

433000103585501 6S 1E27DBBA 433000 1035855 1

432945104015501 6S 1E29CBCD 432945 1040155 1

432956104031001 6S 1E30CBCA 432956 1040310 1

432906104025201 6S 1E31BDCC 432906 1040252 1

432909104003901 6S 1E33BCAC 432909 1040039 1

433055103202801 6S 7E19BCC 433055 1032028 1

432956103184001 6S 7E29 (2) 432956 1031840 1

432826103581501 7S 1E 2BBDD 432826 1035815 1

432837103593401 7S 1E 3BBBB 432837 1035934 1

432750104000001 7S 1E 4DDBC 432750 1040000 1

432710104005401 7S 1E 8DADA 432710 1040054 1

432735104000101 7S 1E 9AAAB 432749 1035949 1

432728103595301 7S 1E 9ADCA2 432728 1035953 1

432725103594901 7S 1E 9ADDD 432725 1035949 1

432703103594201 7S 1E 9DDAA 432703 1035942 1

432714103564901 7S 1E12CACA 432714 1035649 1

432645103575401 7S 1E14ABDD 432645 1035754 1

432638103585201 7S 1E15ACDA 432638 1035852 1

432602103582601 7S 1E23BBB 432602 1035826 2

432603103582801 7S 1E23BBB2 432603 1035828 2

432522103574601 7S 1E23DBCD 432522 1035746 1

432522103574301 7S 1E23DCBA 432522 1035743 1

432432103564901 7S 1E25CDAB 432432 1035649 1

432439103562001 7S 1E25DABC 432439 1035620 1

432443103590201 7S 1E27CAAA 432443 1035902 1

432501104001801 7S 1E28ABAC 432501 1040018 1

432710103553001 7S 2E 7CADA 432717 1035530 1

432638103541801 7S 2E17BDAD 432638 1035418 1

432508103560201 7S 2E30BBBB 432508 1035602 1

432425103555501 7S 2E30CCAC 432425 1035555 1

432436103545401 7S 2E30DADA 432436 1035454 1

432327103550101 7S 2E31DDCD 432327 1035501 1

432327103521901 7S 2E34CCDB 432327 1035219 1

432403103505601 7S 2E35BDBB 432403 1035056 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
188 Water-Quality Characteristics in the Black Hills Area, South Dakota

Inyan Kara wells—Continued

432813103210601 7S 6E 1BAAB 432835 1032106 1

432549103215701 7S 6E23AACC 432549 1032153 1

432214103234301 7S 6E34CBDB 432343 1032355 1

432834103203301 7S 7E 6BBBC 432834 1032028 1

432302103493701 8S 2E 1BDDB 432302 1034937 1

432302103502401 8S 2E 2ACDA 432302 1035024 1

432302103502001 8S 2E 2ADCB 432302 1035020 1

432233103513901 8S 2E 3DCDC 432233 1035139 1

432248103530201 8S 2E 4DBCC 432248 1035302 1

432233103542501 8S 2E 8BABA 432233 1035425 1

432015103535801 8S 2E20DACC 432015 1035358 2

431958103515001 8S 2E22DCCC 431958 1035150 1

431855103491301 8S 2E36ADBB 431855 1034913 1

432128103421401 8S 3E13ACAB 432128 1034214 1

432128103422101 8S 3E13ACBB 432128 1034221 1

432107103422101 8S 3E13DBCB 432107 1034221 1

432020103470601 8S 3E20CAAA 432020 1034706 1

431818103405101 8S 4E31DDCB 431818 1034051 1

431836103363901 8S 4E35BDCD 431836 1033639 1

432113103224801 8S 6E14ADCD 432116 1032214 1

432110103224001 8S 6E14BCDC 432110 1032240 1

431427103594501 9S 1E28ADAB 431427 1035945 1

431752103495701 9S 2E 1BCDA 431752 1034957 1

431632103511501 9S 2E11CCDC 431632 1035115 1

431500103452801 9S 3E22CCCC 431500 1034528 1

431420103302101 9S 5E27ADCA 431420 1033021 1

431124103431501 10S 3E11DDAC 431124 1034315 1

431242103451001 10S 3E15BA 431109 1034510 1

Spearfish wells

444330103502701 9N 2E23CAA 444330 1035027 1

442757103431201 6N 3E21CAAB 442757 1034312 1

442754103384901 6N 4E21CBBB 442754 1033849 1

442458103330901 5N 5E 7A 442458 1033309 3

441142103173101 3N 7E29AADB 441142 1031731 1

440003103151001 1N 7E34DABA 440003 1031510 1

434243103581901 4S 1E11CBCD 434243 1035819 1

434055104002501 4S 1E21CD 434055 1040025 1

433556103564501 5S 1E24CAAB 433556 1035645 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
Supplemental Information — Table 15 189

Spearfish wells—Continued

433245103532701 6S 2E 9BCAB 433245 1035327 1

433234103494401 6S 2E12BDCB 433234 1034944 1

Sundance wells

443421103515501 7N 2E15BDAD 443414 1035134 2

442734103384501 6N 4E21CCDC 442734 1033845 1

442720103380601 6N 4E28ABCC 442723 1033818 1

434908103145201 3S 7E 2ACC 434908 1031452 1

434111103183801 4S 7E20CAA 434111 1031838 1

433858103202001 5S 7E 6ACAA 433850 1031930 1

432653103580501 7S 1E14BAAC 432653 1035805 1

432816103513801 7S 2E 3ACDD 432816 1035138 1

432804103553001 7S 2E 6CADA 432804 1035530 1

432723103493201 7S 2E12DDAA 432723 1034932 1

431825103414201 8S 4E31CCBA 431825 1034142 1

431943103294701 8S 5E26BCAA 431943 1032947 2

Morrison wells

444333103590201 9N 1E22CAA 444333 1035902 1

442754103343301 6N 4E24DBB 442754 1033433 1

440659103064701 2N 8E23DA 440659 1030650 4

440844103050601 2N 9E 7CABC 440844 1030506 2

440759103045501 2N 9E18BDDC 440759 1030500 2

435338103160801 2S 7E10BADB 435338 1031608 1

433252103583001 6S 1E10AAAD 433252 1035830 1

432233103423201 8S 3E 1CDCA 432233 1034232 1

432034103392801 8S 4E20AADD 432034 1033928 1

Pierre wells

443834103241801 8N 6E 1BCBB 443834 1032418 1

443751103264201 8N 6E30BBBC 443751 1032642 1

443610103232701 7N 6E 4ABAA 443610 1032327 1

443300103242501 7N 6E20DAD 443300 1032425 1

441933103062801 4N 8E12BBC 441933 1030628 1

441301103035401 3N 9E17CBDA 441301 1030354 1

440834103013301 2N 9E10CBDC 440834 1030133 1

440646103035401 2N 9E20CCDA 440646 1030354 1

440628103014401 2N 9E28ADAA 440628 1030144 1

440148103040101 1N 9E20CBBA 440148 1030401 1

440018103025201 1N 9E33ACBA 440018 1030252 1

435631103053801 1S 9E19CCDA 435631 1030538 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
190 Water-Quality Characteristics in the Black Hills Area, South Dakota

Pierre wells—Continued

435031103005701 2S 9E26CCBA 435031 1030057 1

434800103022401 3S 9E 9DADB 434800 1030224 1

433932103084201 4S 8E34ACDB 433932 1030842 1

433701103075501 5S 8E14ABCC 433701 1030755 1

433440103022701 5S 9E27CCDC 433440 1030227 1

433202103091401 6S 8E10CDDD 433202 1030914 1

433137103013001 6S 9E15DAAA 433137 1030130 1

433108103055601 6S 9E19BBAA 433108 1030556 1

432952103004601 6S 9E26ACCD 432952 1030046 1

432754103125001 7S 8E 6CDAB 432754 1031250 1

432508103122801 7S 8E 9DCDD 432508 1031228 1

432244103140201 8S 7E 1CADC 432244 1031402 1

432244103164801 8S 7E 3CBCD 432244 1031648 1

432233103194001 8S 7E 6DCDC 432233 1031940 1

432009103192601 8S 7E19DADC 432009 1031926 1

431948103154601 8S 7E27AAAC 431948 1031546 1

Graneros wells

443842103463301 8N 3E20ABB 443842 1034633 1

443101103311501 7N 5E33CDCC 443101 1033115 1

443014103275401 6N 5E 1CCBC 443014 1032754 1

442757103303901 6N 5E21DABB 442757 1033039 1

442515103220101 5N 6E 3DAAD 442515 1032201 1

441745103164001 4N 7E21ABDC 441745 1031640 1

441402103161201 3N 7E10CBBB 441402 1031612 1

435251103114901 2S 8E17BBBC 435251 1031149 1

434810103103001 3S 8E 9BCDC 434810 1031030 1

431355103441601 9S 3E26CCCB 431355 1034416 1

Newcastle wells

440800103131301 2N 7E13BDAA 440800 1031313 1

435005103114901 2S 8E32BCBD 435005 1031149 3

435309103124501 2S 8E 7CDB 435309 1031245 1

433932103114401 4S 8E32BCDC2 433932 1031144 1

434348103131701 4S 7E 1DAAB 434348 1031317 2

Alluvial wells

444152103464001 9N 3E32ACC2 444152 1034640 1

443954103512401 8N 2E10DC 443954 1035124 1

443623103260301 8N 6E31DC 443623 1032603 1

443054103524201 6N 2E 4AB 443054 1035242 2

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
Supplemental Information — Table 15 191

Alluvial wells—Continued

443018103521901 6N 2E 4AD 443018 1035219 1

443024103522001 6N 2E 4D 443024 1035220 2

440506103142801 2N 7E35CDAA 440506 1031431 1

440506103142803 2N 7E35CDAA3 440506 1031431 1

440709103064001 2N 8E23ADAD 440709 1030640 2

440700103080000 2N 8E23C 440700 1030800 1

440651103065001 2N 8E23D 440651 1030650 1

440745103054001 2N 8E23DACD 440745 1030540 1

440713103061601 2N 8E24B 440713 1030616 1

440718103062201 2N 8E24B2 440718 1030622 2

440444103262601 1N 6E 6ABCD 440444 1032626 3

440350103243401 1N 6E 9BBDC 440350 1032434 4

440447103121220 1N 7E 1ABCB20 440447 1031220 1

440320103161501 1N 7E 3CCA 440412 1031603 1

440409103160501 1N 7E 3CCAD 440409 1031605 4

440320103161509 1N 7E 3CDCC 440405 1031559 1

440304103161505 1N 7E 3DBA5 440430 1031530 1

440315103182002 1N 7E 8CDAC2 440315 1031820 2

440328103190501 1N 7E 8DBC 440333 1031805 1

440327103180501 1N 7E 8DBC(2) 440327 1031805 3

440344103163006 1N 7E 9ADA6 440344 1031630 5

440344103163007 1N 7E 9ADA7 440344 1031630 4

440346103163201 1N 7E 9ADBB 440346 1031632 3

440343103163001 1N 7E 9ADCA 440343 1031630 2

440400103100000 1N 8E 4C 440400 1031000 1

440410103112601 1N 8E 5CCCB 440410 1031126 1

440222103033801 1N 9E19DCCB 440222 1030338 1

435602103340201 1S 5E30 435602 1033402 3

435630103340601 1S 5E30BDDD 435630 1033406 1

435537103342501 1S 5E30CCDD 435537 1033425 5

435808103100401 1S 8E20ABBC 435808 1031004 1

440200103110000 1S 8E20B 440200 1031100 1

435558103082701 1S 8E27DABA 435558 1030827 1

435408103243201 2S 6E 4CADA 435408 1032432 3

435038103202001 2S 6E25DAAC 435038 1032020 1

435045103160801 2S 7E27CAAA 435045 1031608 1

435410103075101 2S 8E 2CABD 435410 1030751 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
192 Water-Quality Characteristics in the Black Hills Area, South Dakota

Alluvial wells—Continued

435000103110000 2S 8E32BA 435000 1031100 1

435002103115001 2S 8E32BCCA 435002 1031150 5

435309103033601 2S 9E 8DADC 435309 1030336 1

435139103050901 2S 9E 9ACCD 435139 1030509 1

435237103013301 2S 9E15ACBD 435237 1030133 1

434803103162601 3S 7E10CBAC 434803 1031626 1

434601103074401 3S 8E23CDDC 434601 1030744 1

434818103053101 3S 9E 7BDDB 434818 1030531 1

434528103002801 3S 9E26CAAD 434528 1030028 1

434351103200901 4S 7E 6BCCB 434351 1032009 1

434104103192801 4S 7E18DCDA 434104 1031928 1

434238103065901 4S 8E12CC 434238 1030659 1

434100103120000 4S 8E19D 434100 1031200 1

433955103100802 4S 8E33BAAA2 433955 1031008 1

433913103033701 4S 9E32DDA 433913 1030337 1

433932103011901 4S 9E34ADBD 433932 1030119 1

433101103582601 6S 1E23BCBB 433101 1035826 1

433332103362801 6S 4E 2ACBC 433332 1033628 1

433231103152501 6S 7E11BCDC 433231 1031525 1

433245103134401 6S 7E12ABDB 433245 1031344 1

433043103103301 6S 8E21CABA 433043 1031033 1

432833103071501 6S 8E36CCCD 432833 1030715 1

433206103035401 6S 9E 8DDDD 433206 1030354 1

432613103283201 7S 5E13C 432613 1032832 2

432508103272501 7S 5E19CCDC 432508 1032725 1

432407103242501 7S 6E33ABAC 432407 1032425 1

432504103163001 7S 7E27BAB3 432504 1031630 1

432306103464401 8S 3E 5ADBD 432306 1034644 1

431532103392501 9S 4E21BBAA 431532 1033925 1

431445103352401 9S 4E24DCCA 431445 1033524 1

431724103224401 9S 6E 2CDBD 431724 1032244 1

431355103161501 9S 7E27DDCB 431355 1031615 1

Table 15. Ground-water sampling sites summarized in this report—Continued

Site identification Local number

Latitude Longitude Number of

valid

samples (degrees, minutes, seconds)
Supplemental Information — Table 16 193

 Table 16. Surface-water sampling sites summarized in this report

Station

identification Site Name

Latitude Longitude Number

 of

valid

 samples

(degree, minutes, seconds)

Headwater springs

06408700 Rhoads Fork near Rochford, SD 440812 1035129 142

06409000 Castle Creek above Deerfield Reservoir, near Hill City, SD 440049 1034948 478

06430770 Spearfish Creek near Lead, SD 441756 1035202 91

06430850 Little Spearfish Creek near Lead, SD 442058 1035608 93

Crystalline core sites

06402430 Beaver Creek near Pringle, SD 433453 1032834 67

06402995 French Creek above Stockade Lake, near Custer, SD 434610 1033210 76

06403300 French Creek above Fairburn, SD 434302 1032203 164

06404000 Battle Creek near Keystone, SD 435221 1032010 243

06404800 Grace Coolidge Creek near Hayward, SD 434807 1032603 101

06404998 Grace Coolidge Creek near Game Lodge, near Custer, SD 434540 1032149 240

06405800 Bear Gulch near Hayward, SD 434731 1032049 79

06406920 Spring Creek above Sheridan Lake, near Keystone, SD 435739 1032918 97

06407500 Spring Creek near Keystone, SD 435845 1032025 155

06422500 Boxelder Creek near Nemo, SD 440838 1032716 280

06424000 Elk Creek near Roubaix, SD 441741 1033547 70

06430800 Annie Creek near Lead, SD 441937 1035338 97

06430898 Squaw Creek near Spearfish, SD 442404 1035335 103

06436156 Whitetail Creek at Lead, SD 442036 1034557 104

Artesian springs

06400497 Cascade Springs near Hot Springs, SD 432010 1033307 157

06402000 Fall River at Hot Springs, SD 432550 1032833 218

06402470 Beaver Creek above Buffalo Gap, SD 433120 1032123 58

06412810 Cleghorn Springs at Rapid City, SD 440332 1031749 49

06430532 Crow Creek near Beulah, WY 443414 1040019 63

06430540 Cox Lake Outlet near Beulah, WY 443356 1035937 48

Exterior sites

06395000 Cheyenne River at Edgemont, SD 431820 1034914 520

06400000 Hat Creek near Edgemont, SD 431424 1033516 198

06433500 Hay Creek at Belle Fourche, SD 444001 1035046 144

06436760 Horse Creek above Vale, SD 443908 1032159 210

Other sites

06396300 Cottonwood Creek tributary near Edgemont, SD 431748 1035202 1

06400500 Cheyenne River near Hot Springs, SD 431819 1033343 221

06401500 Cheyenne River below Angostura Dam, SD 432042 1032612 305

06402150 Fall River at mouth near Hot Springs, SD 432312 1032420 5

06402400 Cheyenne River above Buffalo Gap, SD 432505 1031716 5
194 Water-Quality Characteristics in the Black Hills Area, South Dakota

Other sites—Continued

06402500 Beaver Creek near Buffalo Gap, SD 432800 1031820 236

06402520 Iron Draw near Buffalo Gap, SD 432655 1030923 5

06402600 Cheyenne River near Buffalo Gap, SD 433005 1030423 186

06402800 Cottonwood Creek near Buffalo Gap, SD 433136 1030614 5

06402990 French Creek below Custer, SD 434614 1033304 20

06403500 French Creek near Fairburn, SD 434050 1031610 5

06403810 Battle Creek above Keystone, SD 435417 1032748 4

06403850 Grizzly Bear Creek near Keystone, SD 435241 1032614 4

06405000 Grace Coolidge Creek near Custer, SD 434540 1032142 18

06405400 Grace Coolidge Creek near Fairburn, SD 434613 1032028 38

06405500 Grace Coolidge Creek near Hermosa, SD 434629 1031942 9

06405797 Bear Gulch above Hayward, SD 434737 1032117 8

06406000 Battle Creek at Hermosa, SD 434941 1031144 252

06406700 Spring Creek at Oreville, near Hill City, SD 435158 1033724 5

06406740 Sunday Gulch below Johnson Canyon, near Hill City, SD 435210 1033455 6

06406760 Reno Gulch near Hill City, SD 435435 1033643 6

06406950 Horse Creek at Highway 385, near Hill City, SD 435905 1032913 12

06406960 Sheridan Lake tributary near Calumet Ridge, near Keystone, SD 435751 1032735 9

06406994 Spring Creek below Sheridan Lake, near Keystone, SD 435843 1032654 9

06407000 Spring Creek near Hill City, SD 435900 1032600 11

06408000 Spring Creek near Rapid City, SD 435920 1031555 37

06408500 Spring Creek near Hermosa, SD 435631 1030932 202

06408860 Rapid Creek near Rochford, SD 440617 1033835 67

06410000 Castle Creek below Deerfield Dam, SD 440145 1034653 221

06410500 Rapid Creek above Pactola Reservoir, at Silver City, SD 440505 1033448 246

06411500 Rapid Creek below Pactola Dam, SD 440436 1032854 384

06411900 Rapid Creek above Johnson Siding, below Pactola Dam, SD 440455 1032732 3

06412000 Rapid Creek at Big Bend, near Rapid City, SD 440343 1032505 3

06412200 Rapid Creek above Victoria Creek, near Rapid City, SD 440248 1032106 142

06412220 Victoria Creek above Victoria Dam, near Rapid City, SD 440147 1032606 4

06412250 Victoria Creek below Victoria Dam, near Rapid City, SD 440105 1032307 5

06412300 Tittle Springs at Rapid City, SD 440242 1031937 87

06412500 Rapid Creek above Canyon Lake, near Rapid City, SD 440304 1031847 362

06412510 Rapid Creek above Rapid City, SD 440310 1031841 8

06412580 Wild Irishman Gulch near Rapid City, SD 440452 1032154 4

06412600 Cleghorn Springs main channel at Fish Hatchery, at Rapid City, SD 440332 1031754 84

06412700 Cleghorn Springs south channel at Fish Hatchery, at Rapid City, SD 440331 1031756 26

Table 16. Surface-water sampling sites summarized in this report—Continued

Station

identification Site Name

Latitude Longitude Number

 of

valid

 samples

(degree, minutes, seconds)
Supplemental Information — Table 16 195

Other sites—Continued

06412800 Cleghorn Springs north channel at Fish Hatchery, at Rapid City, SD 440332 1031754 24

06412900 Rapid Creek below Cleghorn Springs, at Rapid City, SD 440333 1031749 128

06413200 Rapid Creek below Park Drive, at Rapid City, SD 440333 1031702 78

06413300 Leedy Ditch at headgate below Canyon Lake Dam, at Rapid City, SD 440327 1031712 12

06413550 Leedy Ditch at mouth, at Rapid City, SD 440349 1031622 11

06413570 Rapid Creek above Jackson Boulevard, at Rapid City, SD 440355 1031621 30

06413600 City Springs at Rapid City, SD 440524 1031732 84

06413620 South Canyon near Rapid City, SD 440534 1031937 4

06413650 Lime Creek at mouth, at Rapid City, SD 440430 1031600 96

06413660 Storybook Ditch at headgate, at Rapid City, SD 440404 1031615 24

06413670 Storybook Ditch at mouth, at Rapid City, SD 440429 1031544 18

06413700 Rapid Creek above Water Treatment Plant, at Rapid City, SD 440429 1031534 170

06413800 Deadwood Avenue Drain at mouth, at Rapid City, SD 440458 1031522 42

06414000 Rapid Creek at Rapid City, SD 440509 1031431 392

06414700 Rapid Creek at East Main Street, at Rapid City, SD 440445 1031212 151

06415500 Hawthorn Ditch at Rapid City, SD 440430 1031110 1

06416000 Rapid Creek below Hawthorn Ditch, at Rapid City, SD 440402 1031049 203

06416300 Meade Street Drain at Rapid City, SD 440351 1031132 231

06418900 Rapid Creek below Sewage Treatment Plant, near Rapid City, SD 440124 1030543 193

06422650 Boxelder Creek at Doty School, near Blackhawk, SD 440703 1032154 27

06423000 Boxelder Creek at Blackhawk, SD 440750 1031910 1

06423010 Boxelder Creek near Rapid City, SD 440754 1031754 79

06425100 Elk Creek near Rapid City, SD 441425 1030903 152

06428500 Belle Fourche River at Wyoming-South Dakota State line 444459 1040249 582

06429000 Belle Fourche River at Belle Fourche, SD 444030 1035120 1

06429920 Bear Gulch near Maurice, SD 442514 1040226 27

06429997 Murray Ditch above headgate at Wyoming-South Dakota State line 443435 1040320 42

06430000 Murray Ditch at Wyoming-South Dakota State Line 443435 1040258 53

06430500 Redwater Creek at Wyoming-South Dakota State Line 443426 1040254 345

06430520 Beaver Creek near Maurice, SD 442257 1040013 27

06430525 McNenny State Fish Hatchery rearing pond outlet near Beulah, WY 443330 1040034 173

06430528 McNenny State Fish Hatchery viewing pond outlet near Beulah, WY 443331 1040036 167

06430765 East Spearfish Creek near Lead, SD 441744 1035210 73

06430865 Iron Creek near Lead, SD 442225 1035507 12

06430900 Spearfish Creek above Spearfish, SD 442406 1035340 102

06430910 Aqueduct Inlet below Maurice, SD 442432 1035352 1

06430950 Spearfish Creek below Robison Gulch, near Spearfish 442614 1035232 50

Table 16. Surface-water sampling sites summarized in this report—Continued

Station

identification Site Name

Latitude Longitude Number

 of

valid

 samples

(degree, minutes, seconds)
196 Water-Quality Characteristics in the Black Hills Area, South Dakota

Other sites—Continued

06431500 Spearfish Creek at Spearfish, SD 442857 1035140 235

06432020 Spearfish Creek below Spearfish, SD 443448 1035337 93

06432172 False Bottom Creek near Central City, SD 442328 1034758 10

06432180 False Bottom Creek near Spearfish, SD 442709 1034822 9

06432500 Redwater Canal at Minnesela, SD 443900 1034800 1

06432900 Redwater River above Willow Creek, at Belle Fourche, SD 443828 1034919 6

06433000 Redwater River above Belle Fourche, SD 444002 1035020 245

06434496 Crow Creek near Belle Fourche, SD 444229 1035101 3

06434500 Inlet Canal near Belle Fourche, SD 444214 1034923 563

06436000 Belle Fourche River near Fruitdale, SD 444127 1034414 297

06436100 Belle Fourche River Below Nisland, SD 444012 1032930 3

06436250 Belle Fourche River at Vale, SD 443810 1032537 50

06436800 Horse Creek near Vale, SD 443930 1032017 263

06436850 North Canal near Fruitdale, SD 444412 1034019 4

06437020 Bear Butte Creek near Deadwood, SD 442008 1033806 100

06437200 Bear Butte Creek near Galena, SD 442348 1033436 5

06437400 Bear Butte Creek at Sturgis, SD 442444 1032910 10

Additional sites used for basin or mining-related comparisons

06421500 Rapid Creek near Farmingdale, SD 435631 1025112 265

442125103483000 South Deadwood Creek above Hidden Treasure Mine, near Lead, SD 442125 1034830 1

442131103482000 Deadwood Creek below Hidden Treasure Mine, near Lead, SD 442131 1034820 1

442213103443900 Deadwood Creek below Broken Boot Mine, at Deadwood, SD 442213 1034439 1

442250103485700 Southeast False Bottom Creek near Lead, SD 442250 1034857 1

442251103493800 False Bottom Creek above Columbia Mine, near Lead, SD 442251 10349381 1

Table 16. Surface-water sampling sites summarized in this report—Continued

Station

identification Site Name

Latitude Longitude Number

 of

valid

 samples

(degree, minutes, seconds)