Flow-System Analysis of the Madison and

Minnelusa Aquifers in the Rapid City Area,

South Dakota—Conceptual Model

Water-Resources Investigations Report 02-4185

Prepared in cooperation with the

CITY OF RAPID CITY

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

U.S. Geological Survey

Flow-System Analysis of the Madison and

Minnelusa Aquifers in the Rapid City Area,

South Dakota—Conceptual Model

By Andrew J. Long and Larry D. Putnam

Water-Resources Investigations Report 02-4185

Prepared in cooperation with the 

CITY OF RAPID CITY
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. Government.

Rapid City, South Dakota: 2002

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Description of Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Previous Investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Hydrogeologic Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Madison Hydrogeologic Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Minnelusa Hydrogeologic Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Concepts of the Ground-Water-Flow System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

General Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Hydraulic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Transmissivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Anisotropic Transmissivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Vertical Hydraulic Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Specific Yield. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Storage Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Hydraulic Head and Ground-Water Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Potentiometric Surfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Hydraulic Response to Recharge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Unconfined Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Flowpaths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Water-Budget Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

General Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Seepage from Deadwood Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Streamflow Recharge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Estimation of Streamflow Recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Continuously Gaged Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Battle Creek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Spring Creek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Rapid Creek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Boxelder Creek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Elk Creek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Ungaged Streams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Areal Recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Estimation of Areal Recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Springflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Estimation of Springflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Jackson-Cleghorn Springs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

City Springs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Deadwood Avenue Springs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Boxelder Springs and Elk Springs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Water Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Estimation of Water Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Rapid City Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Other Public-Supply Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Irrigation and Industrial Water Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
IV Contents

CONTENTS—Continued

Water-Budget Analysis—Continued

Leakage to Overlying Aquifers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Regional Outflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Appendices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 

Appendix A: Aquifer Test at RC-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Appendix B: Additional Tables and Hydrographs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

PLATES

[Plates are in pocket]

1. Average potentiometric surface of the Madison aquifer for water years 1988-97

2. Average potentiometric surface of the Minnelusa aquifer for water years 1988-97

3. Hydrologic features considered in water-budget analysis

FIGURES

1. Map showing location of study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. Map showing detail of aquifer analysis area shown in figure 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3. Stratigraphic section for the study area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4. Geologic map of study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5. Schematic showing conceptual hydrogeologic section of the study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

6. Generalized diagram with vertical exaggeration of an artesian aquifer recharged at the updip end . . . . . . . . . . 10

7. Diagram showing recharge conditions and vertical gradients in the Madison and

Minnelusa hydrogeologic units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8. Generalized diagram of an artesian spring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

9-13. Maps showing:

9. Effective transmissivity distribution estimates for the Madison aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

10. Effective transmissivity distribution estimates for the Minnelusa aquifer . . . . . . . . . . . . . . . . . . . . . . . . . 15

11. Hydrogeologic features indicating transmissivity distribution in the Madison aquifer . . . . . . . . . . . . . . . 18

12. Hydrogeologic features indicating transmissivity distribution in the Minnelusa aquifer . . . . . . . . . . . . . . 19

13. Comparison of hydraulic head in Madison and Minnelusa aquifers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

14. Cross section showing geologic features that could enhance vertical hydraulic conductivity . . . . . . . . . . . . . . . 24

15. Photograph of entrance to Onyx Cave in the Madison Limestone in Wildcat Canyon of the

southern Black Hills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

16. Hydrographs for Madison-Minnelusa aquifer paired wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

17. Graph showing possible response of hydraulic head at West Camp Rapid Minnelusa well

to pumping from Madison aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

18. Hydrographs of continuous-record observation wells in the Madison aquifer. . . . . . . . . . . . . . . . . . . . . . . . . . . 31

19. Hydrographs of continuous-record observation wells in the Minnelusa aquifer . . . . . . . . . . . . . . . . . . . . . . . . . 32

20. Graph showing maximum hydraulic head change in selected continuous-record observation

wells during WY88-97 versus distance from Jackson-Cleghorn Springs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

21. Graph showing relation between Spring Creek streamflow loss and hydraulic head in Madison aquifer . . . . . . 33

22. Hydrogeologic section showing average potentiometric surfaces of the Madison and

Minnelusa aquifers in relation to hydrogeologic strata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

23. Map showing generalized ground-water flowpath in the Madison aquifer determined from

Boxelder Creek dye test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

24. Graph showing temporal variation of δ18O in Spring Creek, Rapid Creek, and Boxelder Creek . . . . . . . . . . . . 41

25. Map showing generalized distribution of δ18O in surface water and ground water near recharge areas . . . . . . . 42

26. Map showing generalized ground-water flowpaths in the Madison aquifer based on δ18O. . . . . . . . . . . . . . . . . 43

27. Conceptual model of water budget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

28. Hydrograph of monthly mean streamflow losses from Elk Creek to the Madison

and Minnelusa outcrops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Contents V

FIGURES—Continued

29. Graph showing correlation of total yield to precipitation on basins in Precambrian core . . . . . . . . . . . . . . . . . . 61

30. Graph showing spatially averaged precipitation and estimated areal recharge per

6-month period for the Madison and Minnelusa outcrops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

31. Graph showing spatially averaged areal recharge as a percentage of precipitation on the

Madison and Minnelusa outcrops for winter and summer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

32. Schematic showing construction details of Rapid City well no. 9 (RC-9) completed

in the Madison aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

33. Diagram showing aquifer test conceptual model for multiple aquifer system . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

34. Aquifer test well hydrograph for CL-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

35. Drawdown and recovery curves for CL-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

36. Drawdown curves and curve fit for the Hantush (1960) method for RC-9 aquifer test, October 1995 . . . . . . . . 83

37. Graph showing hydraulic head in Hart Ranch No. 1 and 2 wells plotted with the

Reptile Gardens (RG) Madison well. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

38. Graph showing hydraulic head in well RC-11 completed in the Madison aquifer. . . . . . . . . . . . . . . . . . . . . . . . 100

39. Graph showing hydraulic head in the Wildwood North and South wells completed

in the Minnelusa aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

TABLES

1. Long-term average temperatures in the study area for months of January and July . . . . . . . . . . . . . . . . . . . . . . . 5

2. Hydraulic properties reported for the Madison and Minnelusa hydrogeologic units determined

from aquifer tests in the aquifer analysis area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3. Estimates of regional values of hydraulic conductivity, transmissivity, vertical hydraulic

conductivity, and storage coefficient. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4. Selected information for Rapid City production wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5. Estimates of porosity and specific yield (Sy) for the Madison and Minnelusa hydrogeologic

units from previous investigations and this study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

6. Summary of δ18O for Spring Creek, Rapid Creek, and Boxelder Creek. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

7. Average water budget for WY88-97 (full 10-year budget) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

8. Average water budget for October 1987 through March 1993 (dry period) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

9. Average water budget for April 1993 to September 1997 (wet period) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

10. Selected water-budget components for 6-month stress periods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

11. Selected data for drainage areas, streamflow, and gaging stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

12. Streamflow recharge rates to the Madison and Minnelusa hydrogeologic units. . . . . . . . . . . . . . . . . . . . . . . . . . 55

13. Elk Creek streamflow-loss rates for the Madison and Minnelusa outcrops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

14. Areal recharge zones and average annual precipitation on Madison and Minnelusa outcrops . . . . . . . . . . . . . . . 60

15. Redistribution of average areal recharge from the unsaturated area of the Minnelusa outcrop

to the Madison aquifer in inches per 6-month period, WY88-97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

16. Areal recharge rates to the Madison and Minnelusa hydrogeologic units by zones . . . . . . . . . . . . . . . . . . . . . . . 63

17. Summary of estimated springflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

18. Water use from Madison and Minnelusa aquifers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

19. Total Rapid City water use as an average per stress period. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

20. Rapid City production well withdrawals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

21. Public water supply withdrawals from Madison aquifer excluding Rapid City wells . . . . . . . . . . . . . . . . . . . . . 69

22. Public water supply withdrawals from Minnelusa aquifer excluding Rapid City wells . . . . . . . . . . . . . . . . . . . . 70

23. Industrial and irrigation withdrawals from Madison aquifer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

24. Industrial and irrigation withdrawals from Minnelusa aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

25. Outflow from boundary zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

26. Aquifer properties for the Madison aquifer estimated by the Hantush (1960) method. . . . . . . . . . . . . . . . . . . . . 83

27. Drawdown data for the RC-9 aquifer test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

28. Water wells completed in the Madison aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

29. Water wells completed in the Minnelusa aquifer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
VI Contents

CONVERSION FACTORS AND VERTICAL DATUM

Temperature in degrees Fahrenheit (° F) may be converted to degrees Celsius (°C) as follows:

°C = (° F - 32) / 1.8

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 (WY): 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, 1999, is 

called “WY99.”

Multiply By To obtain

cubic foot per second (ft3/s) 0.02832 cubic meter per second 

foot (ft) 0.3048 meter

foot per day (ft/d) 0.3048 meter per day

foot per mile (ft/mi) 0.1894 meter per kilometer

foot squared per day (ft2/d) 0.09290 meter squared per day 

gallon per day (gal/d) 0.003785 cubic meter per day

gallon per minute (gal/min) 0.06309 liter per second

million gallons per day (Mgal/d) 0.04381 cubic meter per second

inch 2.54 centimeter

inch 25.4 millimeter

inch per year (in/yr) 25.4 millimeter per year

mile (mi) 1.609 kilometer

square mile (mi2) 259.0 hectare

square mile (mi2) 2.590 square kilometer 
Contents VII

SYMBOL DEFINITIONS AND DIMENSIONS

Symbol Dimensions Description

K L/T Horizontal hydraulic conductivity

Kv L/T Vertical hydraulic conductivity

S dimensionless Storage coefficient

Sy dimensionless Specific yield (unconfined aquifer)

T L2/T Transmissivity

Q V/T Discharge rate

A A Area

∆H L Hydraulic head potential

∆L L Length over which ∆H applies

ET L Evapotranspiration

L = length

T = time

A = area

V = volume

OTHER DEFINITIONS

Aquifer analysis area - Includes the outcrops and aquifer areas of the Madison and Minnelusa hydrogeologic units (fig. 1).

Areal recharge - Infiltration from precipitation falling directly on the outcrop recharge areas.

Basin yield - The rate of streamflow leaving a basin divided by the area of the basin, usually expressed in inches per year.

Unsaturated area - The area of a formation that does not contain a water table because the bottom of the dipping formation 

is at a higher altitude than the elevation of the water table.

High-flow area - The near-outcrop area that includes Rapid City and extends 2 to 3 mi north of Boxelder Creek where 

extensive tectonic activity, carbonate and sulfate dissolution, brecciation, ground-water recharge, and ground-water 

circulation has taken or is taking place.

Paired wells - Two wells in the same location or very close proximity that are each open in a different aquifer.

Streamflow recharge - Recharge from streamflow that loses water to the outcrop recharge areas.

Summer period - April through September (S-88 = summer 1988 = April 1988 to September 1988).

Winter period - October through March (W-88 = winter 1988 = October 1987 to March 1988).
Abstract 1

Flow-System Analysis of the Madison and

Minnelusa Aquifers in the Rapid City Area,

South Dakota—Conceptual Model

By Andrew J. Long and Larry D. Putnam

ABSTRACT

The conceptual model of the Madison and 

Minnelusa aquifers in the Rapid City area synthesizes the physical geography, hydraulic properties, 

and ground-water flow components of these 

important aquifers. The Madison hydrogeologic 

unit includes the karstic Madison aquifer, which is 

defined as the upper, more permeable 100 to 200 ft 

of the Madison Limestone, and the Madison confining unit, which consists of the lower, less permeable part of the Madison Limestone and the 

Englewood Formation. Overlying the Madison 

hydrogeologic unit is the Minnelusa hydrogeologic unit, which includes the Minnelusa aquifer in 

the upper, more permeable 200 to 300 ft and the 

Minnelusa confining unit in the lower, less permeable part. The Madison and Minnelusa hydrogeologic units outcrop in the study area on the eastern 

flank of the Black Hills where recharge occurs 

from streamflow losses and areal recharge. The 

conceptual model describes streamflow recharge, 

areal recharge, ground-water flow, storage in 

aquifers and confining units, unsaturated areas, 

leakage between aquifers, discharge from artesian 

springs, and regional outflow.

Effective transmissivities estimated for the 

Madison aquifer range from 500 to 20,000 ft2/d 

and for the Minnelusa aquifer from 500 to 

10,000 ft2/d. Localized anisotropic transmissivity 

in the Madison aquifer has tensor ratios as high as 

45:1. Vertical hydraulic conductivities for the Minnelusa confining unit determined from aquifer 

tests range from 1.3x10-3 to 3.0x10-1 ft/d. The 

confined storage coefficient of the Madison and 

Minnelusa hydrogeologic units was estimated as 

3x10-4 ft/d. Specific yield was estimated as 0.09 

for the Madison and Minnelusa aquifers and 0.03 

for the Madison and Minnelusa confining units. 

Potentiometric surfaces for the Madison and Minnelusa aquifers have a general easterly gradient of 

about 70 ft/mi with local variations. Temporal 

change in hydraulic head in the Madison and 

Minnelusa aquifers ranged from about 5 to 95 ft in 

water years 1988-97. The unconfined areas were 

estimated at about 53 and 36 mi2 for the Madison 

and Minnelusa hydrogeologic units, respectively, 

in contrast to an aquifer analysis area of 629 mi2.

Dye-tracer tests, stable isotopes, and hydrogeologic features were analyzed conjunctively to 

estimate generalized ground-water flowpaths in 

the Madison aquifer and their influences on the 

Minnelusa aquifer. The western Rapid City area 

between Boxelder Creek and Spring Creek was 

characterized as having undergone extensive tectonic activity, greater brecciation in the Minnelusa 

Formation, large transmissivities, generally 

upward hydraulic gradients from the Madison 

aquifer to the Minnelusa aquifer, many karst 

springs, and converging flowpaths.

Water-budget analysis included: (1) a 

dry-period budget for declining water levels; 

October 1, 1987, to March 31, 1993; (2) a wetperiod budget for rising water levels, April 1,
2 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

1993, to September 30, 1997; and (3) a full 

10-year period budget for water years 1988-97. By 

simultaneously balancing these water budgets, 

initial estimates of recharge, discharge, change in 

storage, and hydraulic properties were refined. 

Inflow rates for the 10-year budget included 

streamflow recharge of about 45 ft3/s or 61 percent 

of the total budget and areal recharge of 22 ft3/s or 

30 percent. Streamflow recharge to the Madison 

hydrogeologic unit was about 86 percent of the 

total streamflow recharge. Outflow for the 10-year 

budget included springflow of 31 ft3/s or 

42 percent of the total budget, water use of about 

10 ft3

/s or 14 percent, and regional outflow of 

22 ft3/s or 30 percent. Ground-water storage 

increased 9 ft3

/s during the 10-year period, and net 

ground-water movement from the Madison to 

Minnelusa hydrogeologic unit was about 8 ft3

/s.

INTRODUCTION

The Madison and Minnelusa aquifers are the 

main source of ground water in the Black Hills area 

(Driscoll and Carter, 2001). The city of Rapid City 

obtains more than one-half of its municipal water 

supply from these two bedrock aquifers via deep wells 

and springs. Numerous additional users in the Rapid 

City area obtain water from the Madison or Minnelusa 

aquifers for domestic, industrial, and irrigation usage. 

Ground-water flow within the Madison and Minnelusa 

aquifers is complex. Extensive fracturing, solution 

enhancement, and brecciation contribute to heterogeneity, anisotropic transmissivity, and spatially variable ground-water seepage between the two aquifers. 

A long-term cooperative study between the U.S. Geological Survey and the city of Rapid City has provided 

hydrogeologic data and interpretation for planning and 

management of the Madison and Minnelusa aquifers.

 Purpose and Scope

The primary purpose of this report is to present a 

conceptual model of ground-water flow in the Madison 

and Minnelusa aquifers in the Rapid City area leading 

to a better understanding of the unique concepts 

involved. The conceptual model consists of discussions 

of hydraulic properties, hydraulic head, and groundwater flow. A detailed water-budget analysis encompassing WY88-97 characterizes and quantifies 

recharge and discharge for the study area and is used to 

refine estimates of hydraulic properties. An additional 

purpose of the conceptual model was to compile data 

for numerical modeling and other research efforts in 

the future. 

Description of Study Area

The study area, which includes Rapid City and 

the surrounding area, extends north of Elk Creek, to the 

south near Battle Creek, east of the city of Boxelder, 

and west into the central Black Hills (fig. 1). Streams 

flowing from the central Black Hills contribute to 

streamflow losses that recharge the Madison and 

Minnelusa aquifers. The western extent of the study 

area comprises these stream basins, which include Elk, 

Boxelder, Rapid, Spring, and Battle Creeks. This 

western area is included in the study area for analysis 

of streamflow recharge and evapotranspiration. The 

eastern part of the study area, where the Madison and 

Minnelusa hydrogeologic units exist, is referred to as 

the aquifer analysis area (figs. 1 and 2). These hydrogeologic units are described in subsequent sections of 

the report. 

Land-surface altitudes range from more than 

7,000 ft in the western highlands of the study area to 

about 3,000 ft in the eastern lowlands. The western 

extent of the study area is characterized by high relief 

with predominantly pine and spruce forests. The 

eastern lowlands comprise approximately the eastern 

one-half of the aquifer analysis area and are characterized by rolling prairies with bottom lands along stream 

channels. The outcrops of the Madison and Minnelusa 

hydrogeologic units are located in the western part of 

the aquifer analysis area (fig. 2) along the eastern flank 

of the Black Hills uplift. These outcrops are characterized by high-relief forested areas cut by deep canyons 

with entrenched meanders and steep cliffs formed by 

resistant limestone and sandstone. Average precipitation rates range from about 27 in/yr in the northwest to 

17 in/yr in the eastern lowlands with most precipitation 

occurring in March, April, May, and June (Driscoll, 

Hamade, and Kenner, 2000). Summer temperatures in 

the western highlands generally are cooler and have 

less variation during the winter (table 1). As of 1999, 

about 88,000 people lived in the Rapid City metropolitan area (U.S. Census Bureau, 2000), whereas population is much sparser in other parts of the study area.
Introduction 3

Figure 1. Location of study area.

Elk

Rapid

Creek

Rapid

Spring

Creek

Creek

Battle

Creek

Boxelder

Creek

Creek

Pactola

Reservoir

Sheridan

Lake

Deerfield

Reservoir

DEADWOOD

Lead

Piedmont

Tilford

Roubaix

Black Hawk

Box

Elder

RAPID CITY

Hermosa

Hill City

Keystone

CUSTER

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

T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

T. 1 S.

T. 2 S.

T. 3 S.

90

90

14

385 16A

16A

16A

385

385

16

16

16

14

14A 14A

85

85

79

79

87

244

87

89

36

40

40

44

44

PENNINGTON CO

PENNINGTON CO

LAWRENCE CO

LAWRENCE CO MEADE CO

CUSTER CO

Rapid

City

Airport

EXPLANATION

DRAINAGE AREAS USED IN CALCULATION

 OF STREAMFLOW LOSSES

AQUIFER ANALYSIS AREA

44o

15'

45' 30' 15' 103o

104o

44o

43o

45'

2 4 6 MILES

0 2 4 6 KILOMETERS

0

SOUTH DAKOTA

Study

Area

Black

Hills

Base from U.S. Geological Survey digital data, 1:100,000, 1977

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

Universal Transverse Mercator projection, zone 13
4 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 2. Detail of aquifer analysis area shown in figure 1.

Elk

Creek

Creek

Creek

Creek

Spring

Rapid

Boxelder

16

79

40

79

44

44

90

90

14

14

R. 7 E.

R. 6 E.

R. 5 E.

R. 8 E. R. 9 E.

T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

T. 1 S.

T. 2 S.

1 2 3 4 5 6 MILES

0 1 2 3 4 5 6 KILOMETERS

0

OUTCROP OF THE MADISON

 HYDROGEOLOGIC UNIT

 (modified from Strobel and

 others, 1999)

OUTCROP OF THE MINNELUSA

 HYDROGEOLOGIC UNIT

 (modified from Strobel and

 others, 1999)

44o

10'

44o

44o20'

103o

103o30'

103o

15' SOUTH DAKOTA

Area

Shown

Black

Hills

EXPLANATION

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 Base from U.S. Geological Survey digital data, 1:100,000, 1977

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

Universal Transverse Mercator projection, zone 13

RAPID CITY

Tilford

Box Elder

Black Hawk

Piedmont
Hydrogeologic Setting 5

Previous Investigations

Greene (1993) analyzed aquifer tests and geophysical well logs to determine aquifer properties for 

the Madison and Minnelusa aquifers in the Rapid City 

area. Greene and Rahn (1995) presented evidence 

based on cave-passageway orientations, dye tests, 

aquifer tests, and well-bore geophysics that the directional orientation of anisotropic transmissivity is localized. Long and Derickson (1999) analyzed hydraulic 

response to recharge in the Madison aquifer using a 

linear-systems approach. Long (2000) modeled flow in 

the Madison aquifer in the Rapid City area by incorporating localized anisotropy. Carter, Driscoll, Hamade, 

and Jarrell (2001) presented a water budget for the 

Madison and Minnelusa aquifers for the Black Hills 

area.

The Madison aquifer has been characterized as 

both a dual-porosity aquifer (Greene and others, 1998) 

and a leaky aquifer (Greene, 1993). In the northern 

Black Hills, Greene and others (1998) adapted a 

method similar to the Theis (1935) method to determine 

aquifer properties for dual porosity from an aquifer test. 

In the eastern Black Hills, Greene (1993) used the 

method of Neuman and Witherspoon (1969a, 1969b) to 

determine aquifer properties from an aquifer test for a 

leaky, two-aquifer system. Long (2000) used numerical 

modeling to show that dual porosity and leakage might 

be simultaneously affecting the hydraulics. Rahn 

(1992) characterized the permeability of the Madison 

aquifer and summarized published data related to the 

Madison aquifer in the Black Hills area.

Studies of Madison and Minnelusa springs 

include Rahn and Gries (1973), Klemp (1995), Wenker 

(1997), and Anderson and others (1999). Dye-tracer 

tests in the Madison aquifer include Rahn (1971), Rahn 

Table 1. Long-term average temperatures in the study

area for months of January and July

[Data averaged from 1961 to 1990 (National Oceanic and Atmospheric

Administration, 1996)]

January July

(degrees Fahrenheit)

Pactola Dam1

(western highlands)

1

Shown in figure 1.

21.2 64.4

Rapid City Airport1

(eastern lowlands)

22.1 72.2

Difference .9 7.8

and Gries (1973), and Greene (1999). Studies of 

Madison Limestone cave development in the Black 

Hills include Howard (1964) and Ford (1989). 

Geochemical studies on the Madison and Minnelusa 

aquifers include Busby and others (1991, 1995) and 

Naus and others (2001). Regional studies include 

Downey (1984, 1986), Cooley and others (1986), 

Downey and Dinwiddie (1988), Kyllonen and Peter 

(1987), and Plummer and others (1990). 

Acknowledgments

The authors thank the city of Rapid City for providing extensive assistance with data collection associated with this study. The Water Rights Program of 

the South Dakota Department of the Environment and 

Natural Resources (DENR) provided monitoring 

wells and assisted in the collection and compilation of 

water-level data. The South Dakota DENR also provided water-use data. Other assistance with data collection was provided by Chapel Lane Water Company, 

Carriage Hills Water User’s Association, Hart Ranch, 

and Black Hills Power and Light Company.

HYDROGEOLOGIC SETTING

Uplift at the end of the Cretaceous period followed by erosion has created the dome-like structure 

and geomorphology of the Black Hills. Metamorphic 

and igneous rocks of Precambrian age are exposed in 

the Black Hills’ central core, whereas stratigraphic 

layers of Paleozoic age and younger are exposed on its 

flanks. The outcrops of Paleozoic units form concentric rings surrounding the Precambrian core and dip 

radially outward.

The Madison and Minnelusa aquifers are contained within the Madison and Minnelusa hydrogeologic units, which are exposed in the western part of 

the aquifer analysis area (fig. 2). These units coincide 

with stratigraphic units shown in figures 3 and 4 by 

the symbols MDme and . In the aquifer analysis 

area, stratigraphic units dip in an easterly direction 

away from the Precambrian core (fig. 5). Water-table 

conditions generally exist in outcrop areas; however, 

the updip parts of the outcrops (western extent) may 

not have a water table because of their higher altitudes. 

East of the water-table areas, hydraulic head is above 

the tops of the units due to their easterly dip causing 

artesian (confined) conditions to exist (fig. 5).

PPm
6 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 3. Stratigraphic section for the study area.

STRATIGRAPHIC UNIT DESCRIPTION THICKNESS IN FEET

ABBREVIATION

FOR

STRATIGRAPHIC

INTERVAL

SYSTEM ERATHEM

QUATERNARY

& TERTIARY (?)

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

1,200-2,000

Light colored clays with sandstone channel fillings and local limestone lenses. Includes rhyolite, latite, trachyte, and phondite.

WHITE RIVER GROUPINTRUSIVE IGNEOUS ROCKS

Tw

Tui 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 100-225 Impure chalk and calcareous shale.CARLILE FORMATION Turner Sand Member

Wall Creek Sands

400-750

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

GRANEROS GROUP

GREENHORN FORMATION

Kps

25-380

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

300-550

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

150-250

20-60

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

170-270 Dark-gray to black siliceous shale.

CRETACEOUS

FALL RIVER FORMATIONLAKOTA FORMATION

INYAN KARA

GROUP

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. 35-700

0-2200-225

Green to maroon shale. Thin sandstone.Massive fine-grained sandstone.

250-450

0-45

Greenish-gray shale, thin limestone lenses.Glauconitic 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

250-700

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-crystaline, purplish-gray laminated limestone.Red shale and sandstone. 50-135

1,2375-800

2250-550

30-60

0-60

0-100

375-400

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 buff to purple sandstone. Greenish glauconitic shale, flaggy dolomite, and flatpebble limestone conglomerate. Sandstone, with conglomerate locally 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

PALEOZOIC MESOZOIC CENOZOIC

PRECAMBRIAN

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

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

0-600

- -

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

1 Modified based on drill-hole data.3 Based on Carter and others, 2001.2 Thickness based on structure contours of Minnelusa Formation,

Madison Limestone, and Deadwood Formation tops (Carter andRedden, 1999a, 1999b, 1999c).
Hydrogeologic Setting 7

Figure 4. Geologic map of study area.

Qa

Qc

Qg

Tg

Tw

Tui

Kps

Ju

TRPs

MDme

Kik

Pmk

Po

Ou

Xh

XWui

Xush

XWgw

XWus

PPm

OCd

Qa

Qa

Qa

Qa

Qa

Qa

Qc

Qc

Qc

Qc

Qg

Qg

Qg

Tg

Tg

Tw

Tw

Tw

Tw

Tui

Tui

Kps

Kps

Kps

Kps

Kps

Kik

Kik

Kik

Kik

Ju

Ju

Ju

Ju

TRPs

Pmk

Pmk

Po

Po

PPm

PPm

PPm

PPm

MDme

MDme MDme

MDme

MDme

Ou Ou

Ou

OCd

OCd

OCd

OCd

Xh

Xush

Xush

Xush

Xush

Xush

XWui

XWui

XWui

XWgw

XWgw

XWgw

XWgw

XWus

XWus

XWus

XWus XWus

Elk

Rapid

Creek

Rapid

Spring

Creek

Creek

Battle

Creek

Boxelder

Creek

Creek

90

385 16A

16A

385

16

14

14A 14A

85

85

89

36 40

EXPLANATION

44o

15'

45' 30' 15' 103o

104o

44o

43o

45'

2 4 6 MILES

0 2 4 6 KILOMETERS

0

Base from U.S. Geological Survey digital data, 1:100,000, 1977

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

Universal Transverse Mercator projection, zone 13

Alluvium

Colluvium

Gravel deposits

White River Group

Undifferentiated shallow intrusive igneous rocks

Pierre Shale to Skull Creek Shale, undifferentiated

Inyan Kara Group

Morrison Formation to Sundance Formation,

 undifferentiated

Spearfish Formation (Triassic and Permian)

Minnekahta Limestone 

Minnelusa Formation

Madison (Pahasapa) Limestone and Englewood

 Formation

Whitewood Formation and Winnipeg Formation

Deadwood Formation

Harney Peak Granite

Undifferentiated metamorphosed phyllite and schist

Undifferentiated metamorphosed sedimentary deposits

Metamorphosed graywacke

Undifferentiated igneous rocks

Opeche Shale

Gravel deposits

QUATERNARY UNITS PALEOZOIC UNITS

AREA NOT COVERED BY STROBEL AND OTHERS,

 1999

PRECAMBRIAN UNITS

TERITIARY UNITS

MESOZOIC UNITS

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

T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

T. 1 S.

T. 2 S.

T. 3 S.

Geology from Strobel and others, 1999
8 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 5 also illustrates potential ground-water flowpaths and features that influence flow in the Madison 

and Minnelusa aquifers. Breccia pipes, which have the 

potential to enhance hydraulic connection between 

aquifers, are discussed in greater detail in the “Vertical 

Hydraulic Conductivity” section. Hydrogeologic 

units that may hydraulically affect the Madison and 

Minnelusa aquifers are composed of rocks of Precambrian age through Early Cretaceous age (Inyan Kara 

Group) and also Quaternary surficial deposits, which 

include alluvial aquifers (saturated sand and gravel 

along streams).

Madison Hydrogeologic Unit

The Mississippian-age Madison Limestone is 

composed of limestone and dolomite. In the study area 

to the east of its outcrop, the formation is 250 to 550 ft 

thick (fig. 3). The Madison hydrogeologic unit is 

defined in this report as the Madison aquifer and underlying confining unit, which includes the lower Madison 

Limestone and Englewood Formation. The Madison 

aquifer is defined as the upper 100 to 200 ft of the 

Madison hydrogeologic unit where secondary permeability generally is high because of solution openings 

Figure 5. Schematic showing conceptual hydrogeologic section of the study area (modified from Hayes, 1999). Each aquifer 

shown is separated from other aquifers by confining units. Hydraulic connection between aquifers is increased by vertical 

breccia pipes and fractures. The schematic shows: (1) exposed breccia pipe above hydraulic head in Madison aquifer; (2) 

exposed breccia pipe with hydraulic head below land surface; (3) breccia pipe at active spring-discharge point; (4) developing 

breccia pipe; (5) fractures in confining unit; (6) breccia pipe originating in the Madison Limestone; (7) breccia pipe extending 

from Minnelusa Formation to the Inyan Kara Group; and (8) discontinuous residual clay soil. Arrows show general areal 

leakage, focused leakage at breccia pipes, or ground-water flow directions.

Potentiometric surface

of Madison aquifer

Alluvium

Dip of sedimentary rocks greatly exaggerated

Precambrian metamorphic

and igneous rocks

Deadwood

Inyan Kara Group

Thicknesses not to scale

Madison

Minnelusa

Minnekahta

Limestone

AQUIFER CAVE

BRECCIA PIPE

RESIDUAL CLAY SOIL

 (COLLAPSED AREA)

CONFINING UNIT

EXPLANATION

Formation

Formation

Water

table

(1)

(2)

(3)

(4)

(5)

(6)

(8)

(7) Limestone

Spring

West

East
Concepts of the Ground-Water-Flow System 9

and fractures (Greene, 1993). The upper surface of the 

formation is a weathered karst surface, unconformable 

with the overlying Minnelusa Formation (Cattermole, 

1969). The aquifer is considered karstic because of the 

extensive solution enlargement of fractures that have 

resulted in a predominance of conduit flow.

Secondary permeability in the lower part of the 

Madison Limestone (Madison confining unit) generally 

is much smaller than in the upper part (Greene, 1993); 

however, the confining unit can have greater permeability near outcrop areas, especially along stream 

channels. The Englewood Formation, which underlies 

the Madison Limestone and is less than 60 ft thick, is 

considered part of the confining unit. The Englewood 

Formation is composed of argillaceous, dolomitic limestone and probably could logically be considered a 

member of the Madison Limestone because of its 

lithology (Gries and Martin, 1985). Strobel and others 

(1999) combined the Madison Limestone and Englewood Formation as a single hydrogeologic unit. For 

simplicity, the outcrop of the Madison hydrogeologic 

unit is referred to as the Madison outcrop in this report.

Wells completed in the Madison aquifer in the 

study area are capable of producing 5 to 2,500 gal/min. 

About 64 percent of the wells yield 5 to 50 gal/min, 

11 percent yield 50 to 200 gal/min, and 25 percent 

yield 200 to 2,500 gal/min. The depth of wells ranges 

from 20 to 4,600 ft with 78 percent of the wells less 

than 1,000 ft and 41 percent less than 500 ft.

Minnelusa Hydrogeologic Unit

In the study area to the east of its outcrop, the 

Pennsylvanian- and Permian-age Minnelusa Formation 

is 375 to 800 ft thick (fig. 3). Bowles and Braddock 

(1963) describe the upper part as thick sandstone with 

thin limestone, dolomite, and mudstone, and the lower 

part as having less sandstone and more shale, limestone, and dolomite. Siltstone, gypsum, and anhydrite 

also can be present. At the base of the Minnelusa 

Formation is a red clay shale that varies between 0 and 

50 ft thick (Cattermole, 1969; Greene, 1993). This 

shale, which is discontinuous in the aquifer analysis 

area, is an ancient residual soil developed on the surface 

of the Madison Limestone (Gries, 1996).

The Minnelusa hydrogeologic unit is defined in 

this report as the Minnelusa aquifer and underlying 

confining unit. The Minnelusa aquifer is defined 

as the upper, more permeable 200 to 300 ft of the 

Minnelusa Formation because of the coarser sandstone, solution openings, breccias, and other collapse 

features (Peter and others, 1988; Greene, 1993). The 

aquifer is confined by the overlying Opeche Shale. 

The lower part of the formation, which is less permeable and generally impedes flow between the Minnelusa and Madison aquifers (Kyllonen and Peter, 

1987; Peter and others, 1988; Greene, 1993) is defined 

as the Minnelusa confining unit. Near outcrop areas, 

however, the lower part can have greater permeability 

due to weathering. For simplicity, the outcrop of the 

Minnelusa hydrogeologic unit is referred to as the 

Minnelusa outcrop in this report.

Wells completed in the Minnelusa aquifer in the 

study area are capable of producing 5 to 700 gal/min. 

About 66 percent yield from 5 to 50 gal/min, 

28 percent yield 50 to 200 gal/min, and 6 percent 

yield 200 to 700 gal/min. The depth of wells ranges 

from 80 to 3,000 ft with 90 percent of the wells less 

than 1,000 ft and 60 percent less than 500 ft. 

CONCEPTS OF THE GROUND-WATER-FLOW 

SYSTEM

Pertinent concepts of the ground-water-flow 

system include general concepts such as basic hydraulics, recharge, spring discharge, and aquifer interaction. Hydraulic properties described in this section, 

such as transmissivity, anisotropy, vertical hydraulic 

conductivity, and storage properties, influence 

hydraulic head and ground-water flow. Estimated 

potentiometric surfaces give valuable insight into the 

spatial distribution of these hydraulic properties. 

Long-term observation wells provide essential data 

for the analysis of hydraulic response to stress. The 

areal extent and location of unconfined areas is important because of the large changes in ground-water 

storage occurring there. All of the items mentioned 

above influence ground-water flowpaths, which can 

be analyzed using natural and artificial tracers.
10 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

General Concepts

Figure 6 conceptually illustrates an artesian 

aquifer with hydrogeology similar to that of the 

Madison and Minnelusa aquifers. Infiltrating precipitation or streamflow losses may have an easterly flow 

component rather than a strictly vertical one because of 

the greater hydraulic conductivity parallel to bedding 

planes dipping easterly. The hydraulic head at the 

recharge area fluctuates with the changing recharge rate 

and causes a pressure wave to propagate through the 

confined part of the aquifer. This wave decreases in 

amplitude with distance traveled because of head losses 

in the aquifer. For this reason, hydraulic head fluctuations in downgradient locations east of the recharge 

area are less than at the recharge area unless other 

stresses such as pumping are introduced.

In a setting such as that shown in figure 6, the 

unconfined area occurs on the downdip side of the outcrop area. The western updip part of the outcrop not 

containing a water table is defined as the “unsaturated 

area” in this report. The unsaturated area may contain 

infiltrating or perched water, but should not be confused with the space directly above the water table 

often called the “vadose zone” or “unsaturated zone.”

Movement of ground water between the Madison and Minnelusa aquifers is influenced by vertical 

hydraulic gradients, hydraulic properties of the intervening confining unit, and recharge rates (fig. 7). 

Recharge water may be stored under perched conditions before percolating downward to the regional 

water table. Pools of perched water can be found in 

Madison Limestone caves, and water perched on discontinuous layers of low permeability material may 

exist in the Minnelusa Formation.

Figure 6. Generalized diagram with vertical exaggeration of an artesian aquifer recharged at the updip end. The

diagram shows: (1) recharge infiltrates and moves downward vertically or diagonally parallel to bedding planes; (2)

near horizontal flow with head losses resulting from resistance from aquifer material; (3) sloping potentiometric

surface results from head losses; (4) artesian spring discharges through high-conductivity breccia pipe or fracture

because hydraulic head is above the land surface; (5) spring causes depression in the potentiometric surface; (6)

outflow rate is controlled by hydraulic gradient and transmissivity; (7) hydraulic head fluctuation at recharge area is

controlled by changes in recharge rate; and (8) smaller hydraulic head fluctuation downgradient is in response

to larger fluctuation at recharge area.

4

5

3

2

1

7

AREAL RECHARGE OR

 INFILTRATION

UNSATURATED ZONE

BEDDING PLANE

EXPLANATION

Aquifer

Confining unit

Confining unit

Outcrop

unsaturated

area

Outcrop area

Unconfined

area Confined area

DIRECTION OF FLOW

BRECCIA PIPE

8

6

Land surface

Potentiometric surface

Losingstream

Water table

West East
Concepts of the Ground-Water-Flow System 11

Although the confining units generally do not 

transmit water at a high rate, their capacity to store 

water could have significant effects on the hydraulics of 

the ground-water-flow system. Water that leaks 

between the Madison and Minnelusa aquifers must pass 

through a confining unit as much as 500 ft thick that is 

composed of material of variable porosity where a substantial amount of water can be held in storage. The 

confining units also can affect solute transport and 

hydraulic response to recharge because ground water 

can move into and out of these layers in response to 

changes in hydraulic head. 

Discharge from artesian springs is an important 

consideration in the analysis of the Madison and 

Minnelusa aquifers. There can be difficulty determining whether an artesian spring originates in the 

Madison aquifer, the Minnelusa aquifer, or both. An 

example of the hydraulics of ground-water flow from a 

hypothetical artesian spring includes a vertical conduit 

of high permeability, such as a breccia pipe, beginning 

in the Madison aquifer and ending in an alluvial 

aquifer (fig. 8). In this example, hydraulic head in the 

Madison aquifer is higher than in the Minnelusa 

aquifer, and the permeability of the Madison aquifer, 

breccia pipe, and alluvium is greater than the 

Minnelusa aquifer. Based on these assumptions, 

ground water would flow from the Madison aquifer up 

through the breccia pipe, discharging partly into the 

Minnelusa aquifer and partly into the alluvium where 

it may emerge as seepage to the stream. This discharge 

would create a depression in the Madison aquifer 

potentiometric surface. Minnelusa aquifer water also 

may flow into the alluvium, mixing with Madison 

aquifer water, thus ultimately discharging as a mixture 

of the two waters.

Figure 7. Recharge conditions and vertical gradients in the Madison and Minnelusa hydrogeologic units. The diagram

shows: (1) perched water; (2) part of the recharge on the Minnelusa outcrop infiltrates to the Madison aquifer;

(3) hydraulic head in Madison aquifer greater than in Minnelusa aquifer creating upward hydraulic gradient; and

(4) hydraulic head greater in Minnelusa aquifer than in Madison aquifer creating downward hydraulic gradient.

Minnelusa aquifer

potentiometric surface

(water table in unconfined area)

Madison aquifer

potentiometric surface

(water table in unconfined area)

4 3

1

AREAL RECHARGE

 OR INFILTRATION

LEAKAGE

PERCHED WATER

BEDDING PLANE

EXPLANATION

Aquifer

Aquifer

Confining unit

Confining unit

Confining unit

Madison

hydrogeologic unit

Minnelusa

hydrogeologic unit

Upward

hydraulic gradient

Madison > Minnelusa

Downward

hydraulic gradient

2 Minnelusa > Madison

West East
12 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Hydraulic Properties

Hydraulic properties, including transmissivity, 

anisotropic transmissivity, vertical hydraulic conductivity, storage coefficient, and specific yield, were estimated based on (1) previously published work, (2) a 

water-budget analysis presented later in this report, and 

(3) an aquifer test at well RC-9 (appendix A). In areas 

where little or no data were available, aquifer properties 

were estimated based on a combination of factors. Well 

locations and average potentiometric surfaces included 

in this discussion are shown on plates 1 and 2 and are 

discussed in more detail in the “Hydraulic Head and 

Ground-Water Flow” section. Preliminary investigations (Long, 2000) also were helpful in estimating 

aquifer properties, and water-budget analysis served to 

refine estimates because these properties needed to 

be adjusted to achieve a balance between inflow and 

outflow.

Transmissivity

An aquifer test in the Madison aquifer at well 

RC-9 is described in appendix A, and results are summarized in table 2 along with the results of two previously published aquifer tests in the aquifer analysis 

area. Locations of pumped wells and observation wells 

are shown in figures 9 and 10, which also show the 

estimated transmissivity (T) distributions for the 

Madison and Minnelusa aquifers. These distributions 

are generally in agreement with table 2; however, 

anisotropy and heterogeneity could account for variations. For example, an aquifer test measures the directional T between a pumped well and observation well. 

A general or “effective” T can be estimated based on 

multiple observation wells in an aquifer test (see 

“Anisotropic Transmissivity” section). Estimates of 

this effective T (figs. 9 and 10) are based on aquifer 

tests, well yields, potentiometric surfaces, water 

budgets, and other hydrogeologic information. Table 3 

Figure 8. Generalized diagram of an artesian spring. The diagram shows: (1) the Madison aquifer hydraulic

head is higher than that of the Minnelusa aquifer causing an upward hydraulic gradient inducing flow through a

natural pipe; (2) the spring discharges into the alluvial aquifer; (3) spring discharge causes a depression in the

Madison aquifer potentiometric surface surrounding the spring; and (4) Minnelusa aquifer hydraulic head is

influenced by the stream and water table in the alluvial aquifer.

Minnelusa

hydrogeologic unit

Madison

hydrogeologic unit

Minnelusa aquifer

potentiometric surface

(water table in unconfined area)

Madison aquifer

potentiometric surface

Alluvial aquifer Alluvial aquifer lluvial aquifer

Brecchia pipe?

4

3

1

2

DIRECTION OF FLOW POTENTIOMETRIC SURFACE--

SOLUTION OPENING Dashed where aquifer is confined

EXPLANATION

Confining unit Confining unit
Hydraulic Properties 13

lists aquifer properties reported for the Madison and 

Minnelusa aquifers in the general region but not necessarily within the study area. Additional data compiled 

for the Black Hills area by Rahn (1992) show a similar 

range in Madison aquifer transmissivity.

Well production rates in comparison to drawdown and potentiometric surfaces are also indicative of 

relative T values. The production rates and drawdowns 

shown in table 4 are in general agreement with the 

effective T distributions shown in figures 9 and 10. The 

low production rate and large drawdown in well RC-7 

(fig. 9) indicate that T decreases to the east of Rapid 

City. In addition, a water sample from well RC-7 in 

1991 (Feb. 7, 1991) had a specific conductance of 

3,490 microsiemens per centimeter at 25 degrees 

Celsius indicating a high concentration of dissolved 

solids in contrast to water from many other Madison 

aquifer wells. The high specific conductance is interpreted to be a result of limited ground-water flow in 

that area. Inferences in some local areas can be made 

from the potentiometric surfaces (pls. 1 and 2) by 

assuming that T is generally larger in areas where the 

hydraulic gradient is small. Potentiometric surfaces for 

both aquifers have low gradients in the west-central 

part of the aquifer analysis area. Although this is only a 

general indication of T because recharge rates affect 

hydraulic gradients, aquifer tests also indicate high T 

values in that area.

A zone of relatively large T for the Madison 

aquifer in the eastern part of the area (fig. 9) is based in 

part on a trough in the potentiometric surface at that 

location. This type of potentiometric feature would 

most likely be related to highly transmissive rocks. The 

production rate of 350 gal/min and relatively low dissolved solids concentration (Vince Finkhouse, City of 

Boxelder Public Works, oral commun., 2001) from a 

Madison aquifer production well in the city of Boxelder (pl. 2, site 30) is consistent with large T within 

this zone. In addition, a regional analysis of the 

Madison aquifer by Downey (1986, p. E54) shows a 

similar spatial T distribution. The lower T values in 

the northeast and southeast parts of the area for the 

Madison aquifer were estimated by balancing the water 

budget (see “Water Budget” section) and are consistent 

with those estimated by Downey (1986, p. E54).

Table 2. Hydraulic properties reported for the Madison and Minnelusa hydrogeologic units determined from aquifer tests in 

the aquifer analysis area

[T, transmissivity; Kv, vertical hydraulic conductivity; S, storage coefficient; ft, feet; ft2/d, feet squared per day; ft/d, feet per day; NA, not applicable;

--, no data available]

Pumped

well and

date of test

Layer

Observation

well and site

number

(pls. 1 and 2)

Distance from

pumped well

(ft)

T

(ft2/d)

Kv of the

Minnelusa

confining unit

(ft/d)

S

(dimensionless)Source

RC-51

Spring 1990

(site 79)

1

Anisotropic transmissivity of 56,000 ft2/d was determined with the major axis at an angle of 42 degrees east of north. The minor axis of 

transmissivity was 1,300 ft2/d at an angle of 48 degrees west of north.

Madison aquifer LC (43) 685 1,600 6.8x10-3 1.0x10-4 Greene (1993)

SP-2 (46) 1,700 2,600 1.6x10-2 1.0x10-4

BHPL (36) 3,950 5,200 1.1x10-2 1.0x10-4

CL-2 (50) 8,900 40,000 9.1x10-3 3.0x10-4

CHLN-2 (56) 11,700 40,000 5.3x10-3 3.0x10-4

RC-6

Spring 1990

(site 35)

Minnelusa aquifer CQ-1 (200) 2,930 12,000 NA 3.0x10-3 Greene (1993)

Minnelusa confining 

unit

CQ-1 (200)

CQ-2 (33)

2,930

2,919

-- 3.0x10-1 2x10-7

Madison aquifer CQ-2 (33) 2,919 17,000 NA 2x10-3

RC-9

Fall 1995

(site 49)

Madison aquifer CL-2 (50) 6,290 14,700 1.7 2.1x10-5 Appendix A

RC-11 (62) 8,603 11,500 2.7 2.7x10-4

CHLN-2 (56) 7,562 14,100 0.9 1.4x10-5

SP-2 (46) 4,564 13,900 0.3 6.8x10-5
14 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 9. Effective transmissivity distribution estimates for the Madison aquifer. Transmissivity estimates are provided

for areas where the Madison aquifer exists as shown on plate 1 and do not extend into areas where only the Madison

confining unit exists.

Elk

Creek

Creek

Creek

Creek

Spring

Rapid

Boxelder

R. 7 E.

R. 6 E.

R. 5 E.

R. 8 E. R. 9 E.

T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

T. 1 S.

T. 2 S.

CHLN-2

RC-11

RC-9

SP-2

RC-5

BHPL

RC-10

RC-8

CQ-2

RC-6

LC RC-7

CL-2

RC-11

Jackson-Cleghorn Springs

1 2 3 4 5 6 MILES

0 1 2 3 4 5 6 KILOMETERS

0

OUTCROP OF THE MADISON

 HYDROGEOLOGIC UNIT

 (modified from Strobel and

 others, 1999)

EFFECTIVE TRANSMISSIVITY IN SQUARE

 FEET PER DAY--Shaded area includes full

 extent of the Madison aquifer saturated

 on average for water years 1988-97.

 Interpretation of transmissivity outside

 area where wells are shown is based on

 limited data and regional studies

WATER WELL COMPLETED IN MADISON

 AQUIFER--Letters and numbers indicate

 well name

SPRING

500 to 1,000

Greater than 1,000 to 3,000

Greater than 3,000 to 5,000

Greater than 5,000 to 7,500

Greater than 7,500 to 10,000

Greater than 10,000 to 20,000

44o10'

44o

44o20'

103o

103o30'

103o

15'

EXPLANATION

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

RC-8

RC-10

CQ-2

RC-6

BHPL

LC

RC-7

RC-9

CL-2

CHLN-2

RC-11

RC-5

26

32

33

35

36

43

47

49

50

56

62

79

Well

name

Site

number

(table 28)

Base from U.S. Geological Survey digital data,

1:100,000, 1977

Universal Transverse Mercator projection,

zone 13
Hydraulic Properties 15

Figure 10. Effective transmissivity distribution estimates for the Minnelusa aquifer. Transmissivity estimates are 

provided for areas where the Minnelusa aquifer exists as shown on plate 2 and do not extend into areas where only

the Minnelusa confining unit exists.

Elk

Creek

Creek

Creek

Creek

Spring

Rapid

Boxelder

R. 7 E.

R. 6 E.

R. 5 E.

R. 8 E. R. 9 E.

T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

T. 1 S.

T. 2 S.

Jackson-Cleghorn Springs

1 2 3 4 5 6 MILES

0 1 2 3 4 5 6 KILOMETERS

0

WATER WELL COMPLETED IN MINNELUSA

 OR MADISON AQUIFER--Letters and numbers

 indicate well name

SPRING

Greater than 1,000 to 3,000

500 to 1,000

Greater than 3,000 to 5,000

Greater than 5,000 to 7,500

Greater than 7,500 to 10,000

44o10'

44o

44o20'

103o

103o30'

103o

15'

EXPLANATION

RC-3

RC-4

CQ-1

RC-6

RC-3

RC-6

CQ-1

RC-4

RC-3

35

200

315

316

Well

name

Site

number

(tables 28

and 29)

OUTCROP OF THE MINNELUSA

 HYDROGEOLOGIC UNIT

 (modified from Strobel and

 others, 1999)

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

Base from U.S. Geological Survey digital data,

1:100,000, 1977

Universal Transverse Mercator projection,

zone 13

EFFECTIVE TRANSMISSIVITY IN SQUARE

 FEET PER DAY--Shaded area includes full

 extent of the Minnelusa aquifer saturated

 on average for water years 1988-97.

 Interpretation of transmissivity outside area

 where wells are shown is based on limited

 data and regional studies
16 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Table 3. Estimates of regional values of hydraulic conductivity, transmissivity, vertical hydraulic conductivity, and storage 

coefficient

[Modified from Kyllonen and Peter, 1987, p. 20-21. ft/d, feet per day; ft2/d, feet squared per day; --, no data available]

Original source

Hydraulic

conductivity

(ft/d)

Transmissivity

(ft2/d)

Vertical

hydraulic

conductivity

(ft/d)

Storage

coefficient

(dimensionless)

Data source or method

Madison Aquifer

Konikow (1976, p. 41) -- 860 - 2,200 -- -- Flow net analysis and model, 

includes correction for temperature variation.

Miller (1976, p. 25) -- 0.01 - 5,400 -- -- Drill-stem tests in southeastern 

Montana.

Blankennagel and others

(1977, p. 52-53)

2.4x10-5 - 1.9 -- -- -- Permeability test core.

Woodward-Clyde Consultants 

(1980, p. 4-13)

-- 3,000 -- 2x10-4 - 3x10-4 Aquifer test, long-term response of 

aquifer to pumping in western 

Black Hills region, and model.

Blankennagel and others

(1981, p. 50)

-- 5,090 -- 2x10-5 Step-drawdown tests.

Downey (1984, p. 45) -- 250 - 1,500 -- -- The range given is for Black Hills 

part of Downey’s model.

Kyllonen and Peter (1987, 

p. 21)

-- 4.3 - 8,600 -- -- Model calibrated values.

Downey (1986, p. E54) -- less than 250 to 

3,000

-- -- Model calibrated values.

Carter, Driscoll, Hamade, and 

Jarrel (2001)

-- 100 - 7,400 -- -- Water-budget analysis.

Greene and others (1998) -- 41,700 3x10-4 Interference test.

Minnelusa Aquifer

Blankennagel and others

(1977, p. 50)

less than 

2.4x10-5 to 

1.4

-- -- -- Permeability test of core.

Pakkong (1979, p. 41) -- 880 -- -- Aquifer test.

Woodward-Clyde Consultants 

(1980, p. 4-12)

-- 30 - 300 -- 6.6x10-5 - 

2.0x10-4 Aquifer test, flow and specific capacity data, permeability data, 

and lithologic considerations.

J.S. Downey, U.S. Geological 

Survey, Denver, Colo., 

written commun., 1982)

-- 700 - 1,000 -- -- Model calibrated values.

Kyllonen and Peter

(1987, p. 21)

-- 0.86 - 8,600 -- -- Model calibrated values.

Downey (1986, p. E55) -- less than 250 to 

1,000

-- -- Model calibrated values.

Greene and others (1998) 9,600 7x10-5 Interference test.

Minnelusa Confining Unit

Blankennagel and others

(1977, p. 50-51)

-- -- less than 2.4x10-5

to 0.01

-- Permeability test of core.

Downey (1982, p. 74) -- -- 5.0x10-7 - 7.0x10-7 -- Model calibrated values.

Kyllonen and Peter

(1987, p. 21)

-- -- 3.4x10-6 - 3.4x10-4 -- Model calibrated values.
Hydraulic Properties 17

Table 4. Selected information for Rapid City production wells

[From Anderson and others, 1999. --, no data available]

Well

Site

number 

(pls. 1 

and 2)

Year 

drilled

Major

aquifer

Depth of hole 

(feet below 

land surface)

Approximate 

static water level

(feet below or 

above (-) land 

surface)

Approximate 

pumping

water level

(feet below

land surface)

Drawdown

(pumping level 

minus static 

level)

Approximate 

well yield

(gallons per 

minute)

RC-1 317 1935 Minnelusa1

1

Also may produce from Madison and Deadwood aquifers.

1,460 -32 -- -- 640

RC-3 316 1936 Minnelusa2

2

Also may produce from Madison aquifer.

957 30 -- -- 670

RC-4 315 1939 Minnelusa 1,070 -5 -- -- 700

RC-5 79 1989 Madison 1,292 -102 210 312 1,700

RC-6 35 1990 Madison3

3

Also may produce from Minnelusa aquifer.

1,300 8 426 418 770

RC-7 47 1991 Madison 3,280 250 773 523 150

RC-8 26 1991 Madison 2,680 125 440 315 545

RC-9 49 1991 Madison 1,050 -85 -- -- 2,580

RC-10 32 1991 Madison 1,790 -73 277 350 1,790

RC-11 62 1991 Madison 1,280 64 374 310 820

Transmissivity in the Madison aquifer is primarily influenced by fractures and solution openings. 

Geophysical well logs indicate that in the Rapid City 

area, the relative volume of solution openings is generally largest near the outcrop areas (Greene, 1993), 

which is a result of fracturing caused by the Black Hills 

uplift. The potential for enlargement of fracture openings by dissolution is greatest near recharge areas 

where carbon dioxide is readily available and the 

dissolved solids concentration is low. Carbon dioxide 

in recharge water, which increases in concentration 

within the soil zone, combines with water to form 

carbonic acid causing the dissolution of calcite. As 

carbonate rock is dissolved and water becomes more 

saturated along the flowpath, dissolution potential 

decreases and secondary porosity is less developed.

Fracturing was assumed to coincide with areas 

where there is curvature in strata indicated by a change 

of dip. Areas where changes in dip for the Madison and 

Minnelusa hydrogeologic units are greater than 

2 percent where determined from contour maps of altitude of tops (Carter and Redden, 1999a,1999b) and are 

concentrated near the outcrops (figs. 11 and 12). Curvature also could be the result of an erosional surface of 

the top of the Madison Limestone; however, formation 

thickness in the area showing curvature is relatively 

uniform. Areas where change in dip is greater than 

2 percent generally extend about 3 mi to the east of the 

outcrop and about 5 mi in the area east of the Boxelder 

and Rapid Creek streamflow-loss zones. This wider 

area could indicate more extensive tectonic activity and 

help explain the higher T values. Because of this tectonic activity and other reasons to be discussed later, 

this area is referred to as the high-flow area. Near the 

center of the high-flow area is a syncline-anticline set 

(a, figs. 11 and 12) with a fault at the southern end. 

Jackson-Cleghorn Springs are also located in the central part of the high-flow area, and another synclineanticline set (b, figs. 11 and 12) crosses the Boxelder 

Creek loss zone and extends to the southeast toward 

Jackson-Cleghorn Springs. A third syncline-anticline 

set (c, figs. 11 and 12) is located south of JacksonCleghorn Springs extending toward Spring Creek.
18 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 11. Hydrogeologic features indicating transmissivity distribution in the Madison aquifer. A change in dip indicates 

formation curvature and a likelihood of fracturing.

Elk

Creek

Creek

Creek

Creek

Spring

Rapid

Boxelder

R. 7 E.

R. 6 E.

R. 5 E.

R. 8 E. R. 9 E.

T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

T. 1 S.

T. 2 S.

Jackson-Cleghorn Springs

City

Springs

3,500

3,500

3,400

3,300

3,200

3,100

3,000

2,900

2,800

2,700

2,600

2,500

2,600

2,700

2,800

2,900

3,000

3,100

3,200

3,400

3,300

3,500

3,700

3,600

3,800

1 2 3 4 5 6 MILES

0 1 2 3 4 5 6 KILOMETERS

0

OUTCROP OF THE MADISON

 HYDROGEOLOGIC UNIT

 (modified from Strobel and

 others, 1999)

CHANGE IN DIP OF TOP OF

 MADISON HYDROGEOLOGIC

 UNIT GREATER THAN 2 PER-

 CENT--Altitude of top of Madison

 Limestone from Carter and Redden

 (1999b). A change in dip indicates

 formation curvature and a high likeli-

 hood of fracturing

HIGH-FLOW AREA

44o10'

44o

44o20'

103o

103o30'

103o15'

EXPLANATION

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

SPRING

ANTICLINE-SYNCLINE SET

Base from U.S. Geological Survey digital data,

1:100,000, 1977

Universal Transverse Mercator projection,

zone 13

MADISON AQUIFER POTENTIOMETRIC

 CONTOUR (average, water years 1988-97)--

 Shows altitude at which water would have

 stood in tightly cased, nonpumping well.

 Dashed where inferred. Contour interval

 100 feet. Datum is sea level

AQUIFER ANALYSIS AREA

(a)

(a)

(c)

(b)
Hydraulic Properties 19

Figure 12. Hydrogeologic features indicating transmissivity distribution in the Minnelusa aquifer. A change in dip 

indicates formation curvature and a likelihood of fracturing.

Elk

Creek

Creek

Creek

Creek

Spring

Rapid

Boxelder

R. 7 E.

R. 6 E.

R. 5 E.

R. 8 E. R. 9 E.

T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

T. 1 S.

T. 2 S.

Jackson-Cleghorn Springs

City

Springs

3,300

2,600

2,700

2,700

2,800

2,800

2,900

3,000

3,100

3,200

3,300

3,400

3400

3,500

3,600

2,900

3,000

3,100

3,200

3,300

3,400

3,500

1 2 3 4 5 6 MILES

0 1 2 3 4 5 6 KILOMETERS

0

OUTCROP OF THE MINNE-

 LUSA HYDROGEOLOGIC

 UNIT (modified from Strobel

 and others, 1999)

CHANGE IN DIP OF TOP OF

 MINNELUSA HYDROGEOLOGIC

 UNIT GREATER THAN 2 PER-

 CENT--Altitude of top of Minnelusa

 Formation from Carter and Redden

 (1999a). A change in dip indicates

 formation curvature and a high likeli-

 hood of fracturing

AQUIFER ANALYSIS AREA

HIGH-FLOW AREA

SULFATE TRANSITION ZONE, LOW 

 SULFATE CONCENTRATION TO WEST,

 HIGH CONCENTRATION TO EAST

 (modified from Naus and others, 2001)

44o10'

44o

44o20'

103o

103o30'

103o15'

EXPLANATION

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

SPRING

Base from U.S. Geological Survey digital data,

1:100,000, 1977

Universal Transverse Mercator projection,

zone 13

MINNELUSA AQUIFER POTENTIOMETRIC

 CONTOUR (average, water years 1988-97)--

 Shows altitude at which water would have

 stood in tightly cased, nonpumping well.

 Contour interval 100 feet. Datum is sea level

(a) ANTICLINE-SYNCLINE SET

(a)

(c)

(b)
20 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Estimated T values greater than 7,500 ft2/d in the 

high-flow area (figs. 11 and 12) are consistent with 

aquifer test results in the Madison aquifer (table 2). 

Also, aggressive dissolution of carbonate rocks in the 

Jackson-Cleghorn Springs area is likely to have 

occurred because of the convergence of large volumes 

of recharge water moving toward the springs, which 

probably flow primarily from the Madison aquifer 

(Rahn and Gries, 1973; Back and others, 1983; 

Anderson and others, 1999). Karst solution enlargement of fractures often is initiated at a spring and proceeds radially outward from the spring (Clemens and 

others, 1997), which can create large T values in areas 

surrounding a spring. Jackson-Cleghorn Springs are 

likely to be similar to the generalized diagram of an 

artesian spring shown in figure 8.

A large part of the transmissivity of the Minnelusa aquifer (fig. 10) is due to the primary porosity of 

the sandstone layers; secondary porosity results from 

brecciation and from fracturing due to faulting, folding, 

and separation of bedding planes. Dissolution of interbedded carbonate rock layers and carbonate cements 

also can increase secondary porosity. Although there 

are very little T data for the Minnelusa aquifer in the 

study area, a similarity to the spatial distribution of T in 

the Madison aquifer is likely because the same tectonic 

forces have lead to increased secondary porosity in 

both aquifers.

A process that probably has increased T in the 

Minnelusa aquifer in the near-outcrop area is the collapse resulting from the dissolution of gypsum and 

anhydrite, which are calcium sulfate minerals. Greater 

dissolution is more likely to occur closer to the outcrops because of smaller concentrations of dissolved 

solids in recharge waters. Brobst and Epstein (1963) 

discuss the removal of up to 200 to 300 ft of gypsum 

and anhydrite layers in the southwestern Black Hills 

due to this process, which could result in significant 

collapse and fracturing. The downdip advancement of 

evaporite removal beginning near the outcrop was documented by Naus and others (2001) by an analysis of 

sulfate concentrations in Minnelusa aquifer water. The 

zone of transition for sulfate concentrations (fig. 12) 

separates concentrations less than 250 mg/L (milligrams per liter) to the west, which indicates removal of 

gypsum and anhydrite, from concentrations greater 

than 1,000 mg/L to the east. The transition zone generally ranges from 2 to 3 mi downdip from the Minnelusa 

outcrop and about 7 mi downdip from the outcrop 

congruent with the high-flow area (fig. 12). The wider 

area probably results from increased ground-water 

circulation due to a combination of factors within the 

high-flow area.

Anisotropic Transmissivity

In well-developed karst aquifers, solutionenhanced fractures and bedding planes provide secondary porosity that dominates ground-water flow and 

results in anisotropic transmissivity. Anisotropic transmissivity can be represented by an ellipse with perpendicular axes that define the magnitude and direction of 

the maximum and minimum transmissivity tensors 

(Tmax and Tmin) (Freeze and Cherry, 1979). Effective 

transmissivity (Te), as defined by Hantush (1966a), is 

, or the geometric mean of Tmax and 

Tmin. Greene (1993) reported a ratio of Tmax to Tmin of 

45:1 from an aquifer test at RC-5 (site 79, table 3) in 

the Madison aquifer. 

The distribution of T shown in figures 9 and 10 

refer to effective transmissivity. For the aquifer test at 

RC-5 (table 2), the large discrepancy in T calculated for 

each of the five observation wells was interpreted as 

resulting from anisotropy with the major axis of transmissivity (Tmax) trending northeast-southwest (Greene, 

1993). To determine this anisotropy, Greene (1993) 

applied the method of Hantush (1966a, 1966b), which 

assumes the aquifer is homogeneous and anisotropic. 

However, the results of the aquifer test at RC-5 also 

could be interpreted as resulting, at least in part, from 

heterogeneity. In addition to this, Greene and Rahn 

(1995) and Long (2000) indicated that anisotropy in the 

Madison could be localized in its horizontal orientation.

Anisotropic transmissivity not only can affect 

flow direction but also hydraulic head and hydraulic 

gradients as well. Long (2000) used a numerical model 

to show how the potentiometric surface changes when 

comparing isotropic to anisotropic conditions. A ratio 

of 40:1 can cause flow direction to deflect as much as 

70 degrees from perpendicular to equipotential lines 

(Long, 2000). There is much evidence in support of the 

presence of anisotropy in the Madison aquifer but very 

little data to approximate its spatial distribution.

Some formations have been found to contain two 

mutually perpendicular fracture sets. McQuillan (1973) 

described the fractured-limestone Asmari Formation of 

southwestern Iran, which has such fracture sets. 

Stearns and Friedman (1972) described a major class of 

fracture systems called “regional orthogonal fractures.” 

Tmax Tmin ( ) ×
Hydraulic Properties 21

Also, according to Price (1959), uplift can create 

fractures in one orientation, and further uplift can create 

a new set of fractures orthogonal to the first. 

Greene and Rahn (1995) determined that anisotropic transmissivity in the Madison aquifer near the 

Black Hills had predominantly one of two mutually 

perpendicular orientations, depending on the local area, 

and called this “localized anisotropic transmissivity.” 

The orientation was found to be mainly either northeast 

or northwest. Those authors presented evidence based 

on analysis of cave orientations, fracture traces, aquifer 

tests, tracer tests, and geophysical methods. Within the 

study area for this report, seven out of the eight diagrams of the orientations of cave passageways from 

Greene and Rahn (1995) generally display a predominant orientation that ranges from about 40 to 70 degrees 

east of north. Interpretation of an aquifer test at RC-5 

resulted in an anisotropic orientation of 42 degrees east 

of north (Greene, 1993). Interpretation of bedding 

plane solution openings from an acoustic televiewer log 

at RC-6 showed a predominant orientation approximately perpendicular to anisotropy determined from 

the RC-5 aquifer test (Greene and Rahn, 1995). Synclines and anticlines in the aquifer analysis area (fig. 2) 

are generally oriented about 20 to 25 degrees west of 

north. Downey (1984) inferred a lineament pattern from 

satellite imagery in the northern Great Plains, where in 

the Black Hills area, the predominant lineament pattern 

appears to be either 45 degrees west of north or 

45 degrees east of north. Using localized anisotropy in 

these two general orientations was effective in calibrating a numerical model of the Madison aquifer for 

the Rapid City area (Long, 2000). 

This localized anisotropy may have occurred 

when one set of orthogonal fractures was selectively 

enhanced by dissolution in comparison to the other 

fracture set. Many researchers have studied the conditions that influence conduit network patterns (Howard 

and Groves, 1995; Clemens and others, 1997; Kaufman 

and Braun, 1999, 2000; Gabrovsek and Dreybrodt, 

2000). Tectonic movements can contribute to the 

hydraulic conditions that allow fracture permeability to 

be enhanced in a particular direction in a particular 

area. Local hydraulic gradients can cause the enhancement of one set of fractures over another because the 

fracture set that is aligned most closely with the groundwater flow direction will capture the largest flows and 

become preferentially enlarged. As the increasingly 

dominant fracture set captures progressively more of 

the flow, the gradient and the direction of the resultant 

flow vector also would change. Another factor that 

may have influenced the present conduit network is 

development of cave and solution openings prior to 

the Black Hills uplift. Because the Madison Limestone was being eroded at the land surface after the 

Mississippian sea retreated (Gries, 1996), the surface 

topography and drainage would have been a factor in 

the development of these paleo-cave networks.

Vertical Hydraulic Conductivity

Vertical hydraulic conductivities (Kv) of the 

Minnelusa confining unit estimated from aquifer tests 

in the aquifer analysis area range from 5.3x10-3 to 

2.7 ft/d (table 2), which indicates potential for large 

spatial variability in leakage between the Madison and 

Minnelusa aquifers. These Kv values are notably 

larger than regional values reported by various investigators (table 3). Because the aquifer tests reported in 

table 2 represent only a small sample of the aquifer 

analysis area, Kv values calculated do not necessarily 

represent the entire area. Indeed, these Kv values could 

be some of the largest in the study area because the 

aquifer tests were conducted in the high-flow area 

(figs. 11 and 12) where extensive structural deformation has occurred as previously discussed in the 

“Transmissivity” section. However, because of the 

variable distribution of structural features, this highflow area probably has some of the largest variability 

of Kv values in the study area as well.

Part of the variability of Kv in the Minnelusa 

confining unit determined from aquifer tests (table 2) 

could be due to the selection of the analytical model 

and associated assumptions. Three different models 

were used for the RC-5, RC-6, and RC-9 aquifer tests, 

which included Hantush and Jacob (1955), Neuman 

and Witherspoon (1969a), and Hantush (1960), 

respectively. An important difference in the assumptions made by these models relates to the storage properties of the confining units. The models selected for 

RC-6 and RC-9 take into account storage in the confining units, whereas the model used for RC-5 

assumes no storage in the confining units. The lower 

Kv values determined for RC-5 as compared to RC-6 

and RC-9 (table 2) could be partly due to the different 

assumptions related to storage in confining units.
22 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 13. Comparison of hydraulic head in Madison and Minnelusa aquifers.

Elk

Creek

Creek

Creek

Creek

Spring

Rapid

Boxelder

R. 7 E.

R. 6 E.

R. 5 E.

R. 8 E. R. 9 E.

T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

T. 1 S.

T. 2 S.

Reptile Gardens (68, 272)

Canyon Lake (50, 229)

Sioux Park

(40, 223)

City Quarry

(33, 200)

Tilford 

(1, 104)

Piedmont

(3, 124)

WCR-3 (224)

CP (209)

WRC-3

(224)

(40, 223)

Jackson-Cleghorn Springs

Elk Creek

Springs

Boxelder

Creek

Springs

City

Springs

Deadwood Avenue Springs 2

Deadwood Avenue Springs 1

1 2 3 4 5 6 MILES

0 1 2 3 4 5 6 KILOMETERS

0

OUTCROP OF THE

 MADISON HYDROGEO-

 LOGIC UNIT (modified

 from Strobel and others,

 1999)

OUTCROP OF THE MINNELUSA

 HYDROGEOLOGIC UNIT

 (modified from Strobel and

 others, 1999)

More than 20 feet higher in Minnelusa aquifer

Within 20 feet

More than 20 feet higher in Madison aquifer

MINNELUSA AQUIFER POTENTIOMETRIC

 CONTOUR--Shows altitude in feet above sea

 level (plate 2)

44o10'

44o

44o20'

103o

103o30'

103o

15'

EXPLANATION

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

DIFFERENCE IN POTENTIOMETRIC

 SURFACES OF MADISON AND

 MINNELUSA AQUIFER (plates 1 and 2)

WELL PAIR WITH CONTINUOUS RECORD--

 Numbers in parentheses indicate site numbers

 in tables 28 and 29

OBSERVATION WELL OPEN TO THE MINNELUSA

 AQUIFER--Number in parentheses indicates site

 number in table 29

SPRING

3,500

Base from U.S. Geological Survey digital data,

1:100,000, 1977

Universal Transverse Mercator projection, zone 13

Creek

Boxelder

3,400

3,300

3,500

City

Quarry

(33, 200)

Sioux

Park

(40, 223)

WCR-3 (224)

CP (209)

Deadwood Avenue

Springs 2

Deadwood Avenue

Springs 1

Boxelder

Creek

Springs

City

Springs Creek

Lime
Hydraulic Properties 23

The uneven distribution of a residual clay soil on 

top of the Madison Limestone after weathering and 

reworking during the Mississippian and Pennsylvanian 

Periods (Gries, 1996) could cause heterogeneities in 

hydraulic connection. Greater leakage rates might 

occur where the residual clay is not present. Cattermole 

(1969) and Greene (1993) described this residual 

deposit as 0 to 50 ft of red, clayey shale at the base of 

the Minnelusa aquifer.

Other possible features influencing variability of 

hydraulic connection are faults, fractures, or breccia 

pipes. Hayes (1999) concluded that collapse brecciation within the Minnelusa Formation was the cause of 

episodic sediment discharge at Cascade Springs, which 

is located in the southern Black Hills. Hayes (1999) 

also used geochemical modeling to conclude that dissolution of anhydrite within the Minnelusa Formation by 

upward leakage from the Madison aquifer was the 

mechanism for development of the breccia pipes, which 

are the spring throats at Cascade Springs. Hayes (1999) 

further concluded that collapse brecciation resulting 

from upward leakage of water from the Madison 

aquifer is a probable mechanism that has contributed to 

development of numerous other artesian springs around 

the Black Hills area. Dye-tracer tests and geochemical 

analysis of artesian springs in the Black Hills area that 

flow from outcrops of geologic units overlying the 

Madison Limestone often indicate a source from the 

Madison aquifer (Klemp, 1995; Anderson and others, 

1999, p. 37; Greene, 1999). Many breccia pipes that are 

visible in outcrop sections of the Minnelusa Formation 

probably are throats of previous artesian springs that 

have been abandoned over geologic time (Hayes, 

1999). Breccia pipes that connect the Madison and 

Minnelusa aquifers but do not presently extend to the 

land surface could allow highly localized leakage 

between aquifers.

Breccia pipes can form when ground water 

dissolves gypsum and anhydrite in the Minnelusa 

Formation, thus, creating voids that initiate collapse 

brecciation, which may propagate upward to form vertical breccia pipes (fig. 14). Many breccia pipes probably formed along fractures, especially the intersection 

of fractures (fig. 14), where increased vertical groundwater flow could occur (Brobst and Epstein, 1963). 

Breccia pipes also can be initiated by collapse of the 

lower Minnelusa Formation into Madison Limestone 

caves (figs. 14 and 15) and propagate upward through 

the Minnelusa aquifer (Bowles and Braddock, 1963; 

Brobst and Epstein, 1963; Gott and others, 1974). 

These localized breccia pipes are in addition to the 

areally extensive brecciation in the Minnelusa Formation documented by Brobst and Epstein (1963).

Comparisons of hydrographs for paired observation wells indicate possible hydraulic connection 

between the Madison and Minnelusa aquifers at some 

locations but not at others. There are six paired wells 

within the aquifer analysis area (fig. 16). Three of 

these pairs (Tilford, City Quarry, Reptile Gardens) 

have similar hydrographs indicating a possible 

hydraulic connection between aquifers. The City 

Quarry wells, which have nearly identical hydrographs (fig. 16c), are located about one-half mile from 

City Springs and RC-6, where an aquifer test (Greene, 

1993) and dye-tracer test (Greene, 1999) have indicated nearly certain hydraulic connection.

If recharge rates for the Madison and Minnelusa 

aquifers were similar, this could explain similarities in 

hydrographs; however, streamflow recharge rates, 

which are generally larger than areal recharge within 

the study area, are very different for the Madison and 

Minnelusa aquifers as discussed later. This is especially true in the southern part of the aquifer analysis 

area near the Reptile Gardens wells where the outcrop 

area is very small and streamflow losses are much 

larger than areal recharge, yet the paired wells have 

similar hydrographs (fig. 16f). This indicates that at 

least part of the hydrograph similarity could be the 

result of hydraulic connection. For example, the rise in 

hydraulic head in both aquifers in the summer of 1995 

was about 20 ft. However, the estimated streamflow 

recharge rate from Spring Creek into the Madison 

aquifer was about 18 ft3

/s, whereas the estimated 

recharge rate to the Minnelusa aquifer was about 

2 ft3

/s (see “Recharge from Streamflow Loss” 

section).

Conversely, dissimilarity of hydrographs does 

not necessarily indicate the absence of hydraulic connection. The Canyon Lake paired wells (fig. 16e) are 

located about 0.5 mi from Jackson-Cleghorn Springs 

where Madison aquifer water passes through the 

Minnelusa aquifer before discharging at the surface. 

Hydraulic head in the Minnelusa aquifer is generally 

more than 50 ft lower than in the Madison aquifer and 

shows no resemblance to the Madison hydrograph at 

Canyon Lake. Hydraulic head in the Minnelusa 

aquifer is apparently influenced by the level of 

Canyon Lake, as evidenced by a sharp water-level 

decline when the lake was drained near the end of 

1995.
24 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 14. Geologic features that could enhance vertical hydraulic conductivity including (a) breccia pipe that

formed along a fracture and (b) breccia pipe initiated by collapse of Minnelusa Formation into Madison Limestone cave.

EXPLANATION

DOLOMITIC LIMESTONE

LIMESTONE

SANDSTONE

SOLUTION OPENING

FRACTURE

SHALE BRECCIA PIPE

ANHYDRITE

NOT TO SCALE

a b

Opeche

Shale

Minnelusa

Formation

Madison

Limestone
Hydraulic Properties 25

Figure 15. Entrance to Onyx Cave in the Madison Limestone in Wildcat Canyon of the

southern Black Hills. Just above the cave opening are brecciated rocks of the Minnelusa

Formation that have collapsed.

Approximate Approximate

geologic geologic

contact contact

Approximate

geologic

contact
26 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 16. Hydrographs for paired wells. HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

3,560

3,570

3,590

3,580

3,600

3,620

3,610

3,640

3,630

3,650

3,660

3,670

3,680

Tilford No. 1 (TF-1), site 104, Minnelusa

Tilford No. 2 (TF-2), site 1, Madison

Dotted line indicates discontinuous record. Site number

 refers to tables 28 and 29 and plates 1 and 2

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

CALENDAR YEAR

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

CALENDAR YEAR

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 

3,460

3,480

3,500

3,520

3,540

3,560

3,580

3,600

3,620

A

B

C

D

E

F

Piedmont No. 1 (PDMT-1), site 124, Minnelusa

Piedmont No. 2 (PDMT-2), site 3, Madison

Dotted line indicates discontinuous record. Site number

 refers to tables 28 and 29 and plates 1 and 2

3,420

3,430

3,440

3,450

3,460

3,470

3,480

3,490

Dotted line indicates discontinuous record. Site number

 refers to tables 28 and 29 and plates 1 and 2

City Quarry No. 1 (CQ-1), site 200, Minnelusa

City Quarry No. 2 (CQ-2), site 33, Madison 

3,360

3,370

3,380

3,390

3,400

3,410

3,420

3,430

3,440

3,450

3,460

Sioux Park No. 2 (SP-2), site 40, Madison 

Sioux Park No. 1 (SP-1), site 223, Minnelusa 

Dotted line indicates discontinuous record. Site

number refers to tables 28 and 29 and plates 1

and 2

3,350

3,360

3,370

3,380

3,390

3,400

3,410

3,420

3,430

3,450

3,470

3,460

3,510

3,500

3,490

3,480

3,520

3,530

3,540

3,550

3,560

3,570

Canyon Lake No. 1 (CL-1), site 229, Minnelusa 

Canyon Lake No. 2 (CL-2), site 50, Madison

Dotted line indicates discontinuous record. Site number

 refers to tables 28 and 29 and plates 1 and 2

Dotted line indicates discontinuous record. Site number

 refers to tables 28 and 29 and plates 1 and 2

Reptile Gardens No. 2 (RG-2), site 272, Minnelusa 

Reptile Gardens (RG), site 68, Madison 
Hydraulic Properties 27

Additional evidence of hydraulic connection 

between the aquifers is observed in the hydrograph of 

the Minnelusa observation well WCR-3 (figs. 13 

and 17), which is located about 2 mi south of the City 

Quarry paired observation wells. Well WCR-3 shows 

declines in hydraulic head that are coincident with 

pumping from the Madison aquifer during September 

and October 1995. In October, an aquifer test 

(appendix A) was conducted in the Madison aquifer 

using production well RC-9 (fig. 9). Except for a short 

period of pumping from well RC-10, municipal withdrawals from the Madison and Minnelusa aquifers were 

terminated in that area from September 25 through 

October 16. On September 25, the WCR-3 hydrograph 

shows an upward deflection in hydraulic head (fig. 17) 

presumably due to the termination of pumping. When 

RC-10 began pumping on September 29, hydraulic 

head in WCR-3 declined until pumping ceased less than 

2 days later. When RC-9 began pumping for the aquifer 

test beginning October 4, there was a sharp decline in 

hydraulic head. Hydraulic head began to increase on 

October 6 before pumping from RC-9 was terminated, 

which may have resulted because the aquifer was in a 

general recovery period and drawdown due to 

pumping RC-9 was beginning to flatten. The Black 

Hills Power and Light well (BHPL) was either not 

pumping or pumping intermittently because of plant 

maintenance until October 12 when the pumping rate 

increased, which is coincident with a decline at 

WCR-3. When Chapel Lane Water Company began 

using its production well (CHLN-2) on October 16, a 

similar decline was noted. These observations also 

indicate that hydraulic connection between the two 

aquifers is spatially variable, because noticeable 

responses did not occur in the Sioux Park Minnelusa 

well (fig. 13), which is located closer to the pumping 

wells than is WCR-3. Also, the Sioux Park paired 

wells have dissimilar hydrographs (fig. 16d). 

Irregularities in the potentiometric surface of 

the Minnelusa aquifer near the 3,400-ft contour 

(fig. 13 inset) could be the result of localized upward 

leakage from the Madison aquifer. The central area of 

Figure 17. Possible response of hydraulic head at West Camp Rapid Minnelusa well (WCR-3) to pumping

from Madison aquifer.

9/16 9/18 9/20 9/22 9/24 9/26 9/28 9/30 10/2 10/4 10/6 10/8 10/10 10/12 10/14 10/16 10/18

HYDRAULIC HEAD, IN FEET BELOW LAND SURFACE

175

176

177

178

179

180

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

3,402

3,403

3,404

3,405

3,406

1995 (MONTH/DAY)

All

production

wells off

RC-10 on

(site 32

Madison

well)

RC-8 on

(site 49

Madison

well)

BHPS on

(site 36

Madison

well)

CHLN-2 on

(site 56 

Madison 

well) 
28 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

upward hydraulic gradient coincides with the high-flow 

area (figs. 11 and 12) and contains several artesian 

springs that are assumed or known to originate from the 

Madison aquifer. These upward hydraulic gradients 

could result in movement of Madison aquifer water into 

the Minnelusa aquifer through vertical breccia pipes to 

produce an irregular potentiometric surface in the 

Minnelusa aquifer.

Specific Yield

Specific yield (Sy) is the storage term used to 

describe and make calculations for storage in unconfined areas described in this report. Lohman and others 

(1972) defined Sy and related properties, which include 

total porosity, effective porosity, and specific retention. 

Sy of a rock or soil is defined as the ratio of (1) the 

volume of water that the rock or soil, after being saturated, will yield by gravity to (2) the volume of the rock 

or soil. Sy is equal to total porosity minus specific retention. The specific retention of a rock or soil is the ratio 

of (1) the volume of water that the rock or soil, after 

being saturated, will retain against the pull of gravity to 

(2) the volume of the rock or soil. Specific retention 

increases with decreasing grain size or pore size. Total 

porosity is the ratio of the total volume of pore space in 

a material to the total volume of the material. Effective 

porosity, which is an upper limit for Sy, is the ratio of 

interconnected pore space available for the transmission of water to the total volume of the material. 

Due to heterogeneity, a wide range of porosity 

values for the Madison hydrogeologic unit have been 

reported (table 5). Although direct measurements of Sy

were not available for the study area, estimates were 

made based on porosities and other hydrogeologic 

information. The average Sy was estimated as 0.09 for 

the Madison and Minnelusa aquifers and 0.03 for the 

Madison and Minnelusa confining units.

The definitions of Sy and specific retention imply 

sufficient time for gravity drainage to complete, which 

often is not the case in natural environments (Lohman 

and others, 1972). Therefore, the effective value of Sy

is generally lower than that based strictly on the definition depending on factors such as particle or pore size, 

rate of water-table change, and time. Perching of water 

also can decrease the effective value of Sy because 

water is retained in these perched spaces as the water 

table declines. Other than in solution openings and 

fractures, the permeability of the Madison hydrogeologic unit is generally low, and water collects in poorly 

drained depressions on the floors of solution openings 

above the water table. These depressions often form 

on the floors of enlarged bedding planes, which have 

irregular surfaces and are nearly horizontal. The Minnelusa hydrogeologic unit also has a high potential to 

retain perched water because of low-permeability shale 

layers.

Estimates of Sy for the Madison and Minnelusa 

confining units are lower than for the aquifer units 

because of differences in lithology. Sy of the Madison 

confining unit is less than that of the aquifer because 

of smaller effective porosity and larger specific retention, which results from porosity dominated by small 

fractures rather than solution openings. The lower 

Minnelusa Formation generally contains less sandstone 

and more limestone, dolomite, and shale than the upper 

part (Bowles and Braddock, 1963). Therefore, smaller 

effective porosity and greater specific retention in the 

Minnelusa confining unit results in smaller Sy than in 

the aquifer. 

Storage Coefficient

Storage coefficient, S, is the volume of water an 

aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in hydraulic 

head (Lohman and others, 1972). In a confined aquifer, 

storage coefficient can be orders of magnitude smaller 

that in an unconfined aquifer. This is because in an 

unconfined aquifer, large changes in storage can occur 

due to the rise and fall of the water table; in a confined 

aquifer, smaller changes in storage occur as a result of 

the slight expansion or contraction of the aquifer material and water due to hydraulic-head changes. For an 

unconfined aquifer, storage coefficient is virtually 

equal to the specific yield (Lohman and others, 1972). 

Aquifer tests in the aquifer analysis area indicate that S

varies between 1x10-4 and 2x10-3 for confined conditions of the Madison aquifer (table 2). The only value 

for the Minnelusa aquifer from these aquifer tests is 

3x10-3. However, table 3 shows that S as low as 7x10-5

has been estimated for the Minnelusa aquifer outside 

of the study area. Because there doesn’t appear to be a 

definitive pattern, S for all confined areas of the 

Madison and Minnelusa aquifers is taken at a middle 

value of 3x10-4 for this report.
Hydraulic Head and Ground-Water Flow 29

Table 5. Estimates of porosity and specific yield (Sy) for the Madison and Minnelusa hydrogeologic units from previous 

investigations and this study

[--, no data available]

Total porosity

(as a fraction of 1)

Effective porosity

(as a fraction of 1)

Specific yield

(dimensionless) Data source or method Source

Madison Limestone

0.11 0.05 -- Oil tests Rahn (1985)

Madison Aquifer

-- 0.35 (average) -- Well RC-6 resistivity log Greene (1993)

-- 0.35 (average) -- Well LC resistivity log Greene (1993)

-- -- 0.09 Water budget1

1

See “Water-Budget Analysis” section.

This report

Madison Confining Unit

-- -- 0.03 Water budget1 This report

Minnelusa Formation

0.10 0.05 -- Oil tests Rahn (1985)

Minnelusa Aquifer

-- 0.10 - 0.15 -- Well RC-6 neutron porosity log Greene (1993)

-- 0.05 - 0.10 -- Well RC-5 neutron porosity log Greene (1993)

-- -- 0.09 Water budget1 This report

Minnelusa Confining Unit

-- 0.05 (average) -- Well RC-6 neutron porosity log Greene (1993)

-- 0.05 (average) -- Well RC-5 neutron porosity log Greene (1993)

-- -- 0.03 Water budget1 This report

Hydraulic Head and Ground-Water Flow

Potentiometric surfaces, hydraulic response to 

stress, the extent of unconfined areas in relation to confined areas, and flowpaths are important considerations 

in understanding the dynamics of the ground-waterflow system. Analysis of hydraulic response to stress 

can be used to characterize the aquifers and estimate 

properties such as storage and transmissivity. 

Hydraulic gradients can be useful for estimating transmissivities, recharge areas, discharge areas, and flow 

directions. The areal extent of unconfined areas is 

important for analysis of storage and ground-water 

flow near recharge areas. Flowpaths are important 

when considering sources of springs and wells.

Potentiometric Surfaces

Potentiometric maps of the Madison and 

Minnelusa aquifers (pls. 1 and 2; figs. 11 and 12) were 

interpreted based on available hydraulic heads in observation wells, public-supply wells, and private wells. 

The potentiometric surfaces for both aquifers show a 

general easterly gradient of about 1,000 ft in 15 mi. 

Detailed information for the wells used in interpreting 

potentiometric maps is listed in tables 28 and 29 

(appendix B). Where data are sparse in the eastern part 

of the aquifer analysis area, contours were based on 

Downey (1986).

Because the hydraulic heads were measured at 

various times, a potentiometric surface could not be 

interpreted for a particular date; therefore, the potentiometric maps represent an average potentiometric 
30 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

surface for WY88-97. To achieve this, each hydraulichead measurement was either adjusted up if the 

measurement was made during a period of low water 

levels or adjusted down if made during a period of high 

water levels. Adjustment to each hydraulic head 

measurement was based on the WY88-97 hydrograph 

of the nearest continuous-record well (figs. 18 and 19). 

Hydrographs of longer periods of record are available 

for some wells (Driscoll, Bradford, and Moran, 2000). 

WY88-97 included a range of climatic conditions from 

dry during the late 1980’s through wet conditions in the 

middle to late 1990’s. Periods of continuous records 

that included the influence of pumping were eliminated 

from the analysis. Water levels for many wells have 

been obtained from drillers’ reports, which generally 

are fairly accurate; however, locations can be inaccurate. In areas of large topographic relief, accurate locations are essential to determine land-surface altitudes. 

However, because it was infeasible to visit all of the 

wells to check or verify locations, hydraulic head 

measurements not considered reliable were not used 

(tables 28 and 29).

In a few cases, unusually high hydraulic heads 

were measured in wells located on or near the outcrop 

areas and are likely to represent perched water, which 

is known to exist near the Madison outcrop area. Wind 

Cave in the southern Black Hills contains a 300-ft-long 

body of water (Phantom Lake) that is perched considerably above the water table (Marc Ohms, Wind Cave 

National Park, oral commun., 2001). Hydraulic head 

measurements thought to be from perched water were 

omitted from the potentiometric-surface analysis.

The trough in the potentiometric surface in the 

eastern part of the Madison aquifer, where data are 

sparse, is based on the regional potentiometric surface 

of the Madison aquifer shown in Downey (1986, 

p. E39). The few hydraulic heads measurements available for the eastern part of the Madison aquifer (pl. 1) 

are in agreement with Downey’s (1986) interpretation. 

Downey and Dinwiddie (1988, p. A47) show a narrow 

path of high easterly ground-water velocity in the Madison aquifer along the axis of this area, and Downey 

(1986, p. E54) shows a zone of anomalously high transmissivity in this area. If there is a high-transmissivity 

pathway in this area of the Madison aquifer that draws 

down the hydraulic head, it is likely to draw down 

hydraulic head in the Minnelusa aquifer as well, especially if there is enhanced vertical hydraulic conductivity in the Minnelusa confining unit. Therefore, the 

Minnelusa aquifer was interpreted as having a lowered 

potentiometric surface in this area (pl. 2).

Hydraulic Response to Recharge

Hydraulic-head changes in the Madison and 

Minnelusa aquifers in the study area are highly variable 

(figs. 18 and 19). The difference of the maximum and 

minimum hydraulic head in continuous-record observation wells during WY88-97 ranged from about 5 to 

120 ft (fig. 20). With the effects of pumping from RC-5 

removed from the LC and SP-2 hydrographs, a pattern 

emerges whereby hydraulic-head change is small in the 

Jackson-Cleghorn Springs area and increases with distance from the springs (fig. 20). The transmissivity distribution probably is part of the reason for this pattern 

because higher transmissivity tends to damp hydraulic 

head fluctuations in response to stresses such as 

recharge or pumping. Based on aquifer tests and the 

hydraulic gradients shown on plates 1 and 2, transmissivity near the Jackson-Cleghorn Springs area is high 

and generally decreases with distance from the springs.

Hydraulic head fluctuates in response to 

changing recharge rates at the outcrop areas. In the 

Spring Creek area where areal recharge is small compared to streamflow recharge, a direct correlation of 

streamflow loss to hydraulic head in the Madison 

aquifer was described by Long and Derickson (1999) 

by invoking a time-invariant transfer function (fig. 21). 

Hydraulic head can be predicted based on this transfer 

function applied to the streamflow-loss rate. Based on 

data from the Reptile Gardens Madison well (RG) 

about 3 mi from the recharge area, the transfer function 

showed that (1) the peak response is less than one 

month, (2) the system has memory of about 4 years, 

and (3) ground-water recession follows a logarithmic 

curve. The very long memory (elapsed time before all 

effects of a stress have diminished) in contrast to the 

short response time of the system probably results from 

dual porosity. A long-term system memory can result 

from delayed storage within the aquifer’s matrix of tiny 

fractures and small pore spaces in contrast to the very 

fast flowpaths of large solution openings. This also can 

result from leakage to and from overlying or underlying 

confining units, which can store water in a similar way 

to that of a dual-porosity system. Numerical modeling 

has shown that hydraulic head fluctuation in the Madison aquifer can be damped by leakage into and out of 

vertically adjacent layers and also by dual-porosity 

effects (Long, 2000). Storage properties and/or the 

hydraulic response of dual-porosity reservoirs are 

described in Barenblatt and others (1960), Warren and 

Root (1963), Streltsova (1988), and Bai and others 

(1993). Streltsova (1988) also describes these properties for leaky aquifers. 
Hydraulic Head and Ground-Water Flow 31

Figure 18. Hydrographs of continuous-record observation wells in the Madison aquifer.

CALENDAR YEAR

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

3,300

3,350

3,400

3,450

3,500

3,550

3,600

3,650

3,700

3,750

Canyon Lake No. 2 (CL-2, site 50)

Sioux Park No. 2 (SP-2, site 46)

Lime Creek (LC, site 43)

City Quarry No. 2 (CQ-2, site 33)

Reptile Gardens (RG, site 68)

Tilford No. 2 (TF-2, site 1)

Piedmont No. 2 (PDMT-2, site 3)

WELL--Ordered from closest to farthest from

 Jackson-Cleghorn Springs. Discontinuous

 record is dotted. Site numbers refer to

 table 28 and plate 1

SP-2

CQ-2

TF-2

CL-2

LC

RG

PDMT-2
32 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 19. Hydrographs of continuous-record observation wells in the Minnelusa aquifer.

CALENDAR YEAR

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

3,300

3,350

3,400

3,450

3,500

3,550

3,600

3,650

3,700

Canyon Lake No. 1 (CL-1, site 229)

Chaple Lane No. 1 (CHLN-1, site 233)

West Camp Rapid No. 3 (WCR-3,

 site 224)

Sioux Park No. 1 (SP-1, site 223)

City Quarry No. 1 (CQ-1, site 200)

Cement Plant (CP, site 209)

Blackhawk No. 1 (BLHK-1, site 181)

Tilford No. 1 (TF-1, site 104)

Piedmont No.1 (PDMT-1, site 124)

Reptile Gardens No. 2

 (RG-2, site 272)

Well--Ordered from closest to farthest from Jackson-Cleghorn Springs. Discontinuous record is dotted.

 Site numbers refer to table 29 and plate 2

CL-1

SP-1

WCR-3

CHLN-1

CP

BLHK-1 CQ-1

RG-2

TF-1

PDMT-1
Hydraulic Head and Ground-Water Flow 33

Figure 20. Maximum hydraulic head change in selected continuous-record observation wells

during WY88-97 versus distance from Jackson-Cleghorn Springs. In general, maximum hydraulic

head change increases with distance from Jackson-Cleghorn Springs. Maximum hydraulic head

change in wells with shorter periods of record was estimated. Hydrographs are plotted in

figures 18 and 19.

DISTANCE FROM JACKSON-CLEGHORN SPRINGS,

IN MILES

0 5 10 15 20

MAXIMUM CHANGE IN HYDRAULIC HEAD,

IN FEET

0

20

40

60

80

100

120

Minnelusa aquifer well

Madison aquifer well

TF-2

RG

CQ-2

SP-2

CL-2

LC

TF-1

PDMT-1

BLHK-1

CP

CQ-1 SP-1

WCR3

CL-1

CHLN-1

Well

name

Site

number

TF-2

CQ-2

LC

SP-2

CL-2

RG

TF-1

PDMT-1

BLHK-1

CQ-1

CP

SP-1

WCR-3

CL-1

CHLN-1

1

33

43

46

50

68

104

124

181

200

209

223

224

229

233

Site number refers to tables

28 and 29 and plates 1 and 2

Figure 21. Relation between Spring Creek streamflow loss and hydraulic head in Madison aquifer.

Spring Creek loss rate to the Madison hydrogeologic unit (loss rate was assumed not to

 exceed a threshold of 21 cubic feet per second estimated by Hortness and Driscoll (1998))

Hydraulic head in the Madison aquifer at well RG (site 68, table 28 and plate 1)

25

20

15

10

5

0

STREAMFLOW-LOSS RATE, IN CUBIC FEET PER SECOND

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

WATER YEAR

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

3,450

3,460

3,470

3,480

3,490

3,500

3,510

3,520

3,530

3,540

3,550

3,560

3,570

3,580
34 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Unconfined Areas

The boundaries of unconfined areas (pls. 1 

and 2) are determined by the locations where the 

average potentiometric surfaces (WY88-97) contact the 

tops and bottoms of the Madison and Minnelusa aquifers and associated confining units. Altitudes for top 

and bottom of the Madison and Minnelusa hydrogeologic units were taken from maps of the structural tops 

of the Minnelusa Formation, Madison Limestone, and 

Deadwood Formation from Carter and Redden (1999a, 

1999b, 1999c). The top of the Minnelusa Formation 

was taken as the top of the Minnelusa hydrogeologic 

unit. The top of the Madison Limestone was taken as 

the top of the Madison hydrogeologic unit and the 

bottom of the Minnelusa hydrogeologic unit. The top of 

the Deadwood Formation was taken as the bottom of 

the Madison hydrogeologic unit. A uniform thickness 

of 150 ft (assumed thickness of the Madison aquifer) 

was subtracted from the top of the Madison hydrogeologic unit to estimate the altitude of the surface between 

the aquifer and confining unit. The same was done for 

the Minnelusa hydrogeologic unit, with a uniform 

thickness of 250 ft assumed for the aquifer thickness. 

These aquifer thicknesses are the midpoints of ranges 

given by Greene (1993). 

Because potentiometric surfaces are generally 

some distance below the land surface in the outcrop 

areas, and the aquifers and confining units dip to the 

east (fig. 6), unconfined areas are present eastward of 

outcrop areas. The western part of outcrop areas generally are not saturated but may contain infiltrating or 

perched water.

Boundaries of the unconfined areas of the 

Madison and Minnelusa aquifers shift to the east or 

west as hydraulic head fluctuates. During WY88-97, 

the maximum fluctuation in measured hydraulic head 

was about 100 ft, which would cause these boundaries 

to shift a distance of 600 to 2,000 ft or about 1 to 

2 percent of the total east-west dimension of the aquifer 

analysis area. Although unconfined areas shift horizontally, the total areal coverage changes negligibly. 

Because of these comparatively small changes in position and area, the unconfined zones shown on plates 1 

and 2 were assumed to be spatially constant in time for 

water-budget purposes. Saturated thickness and transmissivity of the unconfined zones were assumed constant in time, which is justifiable if the dip of the beds 

are relatively constant within areas where the unconfined areas shift from east to west. It follows that even 

if unconfined areas change position vertically and 

horizontally as hydraulic heads rise and fall, saturated 

thicknesses also would be assumed constant.

The location and extent of the unconfined areas 

are significant in analyzing aquifer storage because 

most of the change in storage occurs in these areas. 

Estimates of specific yield (unconfined storage term) 

for the Madison and Minnelusa aquifers are three or 

more orders of magnitude larger than estimates of 

storage coefficient for confined conditions (tables 2, 3, 

and 5). Estimates of unconfined area coverages for the 

Madison and Minnelusa hydrogeologic units are 

52.9 mi2

 and 36.3 mi2, respectively. Although the 

unconfined areas represent a small percentage of the 

aquifer analysis area (629.4 mi2

), the amount of water 

these areas are capable of releasing from storage with a 

given change in head is orders of magnitude larger than 

that released in the confined part of the aquifer.

Eight hydrogeologic sections (fig. 22), A-A′

through H-H′ , (pls. 1 and 2), show differences in 

unconfined areas. Section A-A′ shows how the steep 

dip of a monocline results in a small unconfined area in 

the Madison aquifer relative to that of the Minnelusa 

aquifer. Section B-B′ illustrates an area where the 

Madison outcrop is large, but most of the outcrop area 

is unsaturated with a small unconfined area near the 

eastern edge of the outcrop. Although most of the outcrop is not saturated at this location, the areal extent of 

the outcrop makes it a large source of areal recharge. 

The “unsaturated area” in section B-B′ consists mainly 

of the lower part of the Madison hydrogeologic unit, 

which is generally considered a confining unit; however, weathering and dissolution of fractures has 

probably increased its permeability in outcrop areas 

allowing recharge water to quickly infiltrate and flow 

laterally toward water-table areas. This flow might consist of water cascading through a series of subsurface 

pools or non-Darcian channel flow, and could have 

very high velocities in some areas. For example, dye 

testing (Rahn and Gries, 1973; Greene, 1999) indicated 

ground-water flow velocities on the order of miles per 

hour along a flowpath starting in a swallow hole in 

Boxelder Creek, located in the Madison confining unit 

outcrop, and emerging from Gravel and Doty Springs 

(see cover photo). 

Sections C-C′ and D-D′ illustrate how an 

anticline-syncline structural feature with a southeasterly plunge influences ground-water flow and the 

areal extent of the unconfined area near Boxelder 

Creek (pl. 1). Section C-C′ shows that saturated areas 
Hydraulic Head and Ground-Water Flow 35

of the Madison hydrogeologic unit are separated by an 

anticline. Section D-D′ shows how an anticline blocks 

much easterly flow in the Madison aquifer, thus, 

diverting flow to the southeast along the syncline axis 

(pl. 1). Therefore, a large part of the streamflow 

recharge from Boxelder Creek probably is directed 

toward Rapid City. Some easterly flow within the 

Madison confining unit also is plausible but probably is 

minor compared to southeasterly flow in the aquifer.

Section E-E′ shows the uniform dip of the 

hydrogeologic strata in the Rapid Creek and JacksonCleghorn Springs area. A fault separates section E-E′

from section F-F′ on the upthrown side (pl. 1) where 

strata have been lifted higher than on the downthrown 

side in relation to the potentiometric surfaces. In addition, gently dipping beds and structural features have 

resulted in large unconfined areas or unsaturated areas 

along section F-F′ .

Section G-G′ shows how variations in dip create 

a wide Madison outcrop area in comparison to that of 

the Minnelusa outcrop. Section H-H′ illustrates the 

reason that the unconfined area of the Madison hydrogeologic unit is farther to the east of the outcrop than at 

section G-G′ .

Flowpaths

Dye-tracer tests, stable isotopes, and hydrogeologic features were analyzed conjunctively to estimate 

generalized ground-water flowpaths in the Madison 

aquifer and analyze the influences of flowpaths in the 

Minnelusa aquifer. A dye-tracer test (Greene, 1999) 

showed that ground water moved rapidly from the Boxelder Creek loss zone to five ground-water sampling 

sites in the Madison aquifer. Natural tracers in the form 

of stable isotopes provided more generalized evidence 

but were available for a larger part of the study area. 

The spatial configuration of saturated areas in relation 

to unsaturated areas indicated probable flowpaths at 

some locations.

 As discussed in the previous section, the 

anticline-syncline set that crosses Boxelder Creek 

(fig. 23) has the potential to impede easterly ground 

water recharged near Boxelder Creek. Section D-D′ 

(fig. 22,) shows that easterly ground-water flow across 

the anticline, if any, would be within the Madison confining unit. Τhe more likely flowpath, however, is to 

the southeast along the axis of the syncline where the 

Madison aquifer is fully saturated.

The dye-tracer test (Greene, 1993) indicates a 

focused flowpath, which probably follows the syncline 

southeasterly before turning to the east (fig. 23). The 

dye-tracer test consisted of injection of Rhodamine WT 

dye at the Boxelder Creek loss zone, which was 

detected at City Springs, RC-6, RC-10, BHPL, WT-2, 

and CQ-2 but was not detected at Jackson-Cleghorn 

Springs, RC-5, RC-8, or RC-9 (fig. 23). Except for 

observation well CQ-2, all these wells are production 

wells that were being pumped. The sites where dye was 

detected are grouped in a semi-linear pattern oriented 

downgradient, bounded by RC-8 on the north and RC-5 

on the south. Greene (1993) measured breakthrough 

curves for all sites where dye was detected except for 

CQ-2. Dye detection at City Springs began 30 days 

after injection and continued until the 261st day with a 

peak concentration at 48 days. Dye detection at RC-10 

and BHPL began less than 50 days after injection and 

continued until the 198th and 159th day respectively 

with peak concentrations less than 10 days after that of 

City Springs. If the flowpath was dispersive rather than 

focused, dye may have been detected at RC-5 and 

RC-8, especially considering the duration of breakthrough curves at the other sites. In addition, the mass 

recovery of 36 percent of the injected dye reported by 

Greene (1993) probably would not be possible without 

a focused flowpath.

Stable isotopes of oxygen and hydrogen (18O 

and 2

H) in recharge water can be used as natural tracers 

to determine source areas and flowpaths for ground 

water. Isotope values are reported as a ratio of 18O/16O 

or 2H/1H of a sample water compared to a standard. 

The equation for oxygen given in parts per thousand 

(per mil) is as follows:

(1)

A smaller delta (δ) value is referred to as being isotopically lighter, while a larger value is considered heavier. 

For further discussion on stable isotope analysis in natural waters and distribution in the Black Hills area, see Naus 

and others (2001). 

δ18Osample

O/ O 18 16 ( )sample O/ O 18 16 – ( )standard

O/ O 18 16 ( )standard

= --------------------------------------------------------------------------------------- × 1 000. ,
36 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 22. Hydrogeologic section showing average potentiometric surfaces of the Madison and Minnelusa aquifers (plates 1 and2) in relation to hydrogeologic strata (location of sections shown on plates 1 and 2).

0.5 1 MILES

0.5 1 KILOMETERS

00

A A' FEET

5,0004,0003,0002,000

B B' FEET

5,0004,0003,0002,000 VERTICAL EXAGGERATION X3.3

DATUM IS SEA LEVEL

Altitude of tops of hydrogeologic units modified

from Carter and Redden, 1999a, 1999b, 1999c

OVERLYING HYDROGEOLOGIC UNITSMINNELUSA HYDROGEOLOGIC UNITMADISON HYDROGEOLOGIC UNITUNDERLYING HYDROGEOLOGIC UNITS

MINNELUSA AQUIFERMADISON AQUIFER

POTENTIOMETRIC SURFACE OF MINNELUSA AQUIFER--Dashed in confining unit POTENTIOMETRIC SURFACE OF MADISON AQUIFER--Dashed in confining unit 

EXPLANATION

Monocline

Unsaturated area

Elk Creek

West East
Hydraulic Head and Ground-Water Flow 37 Figure 22. Hydrogeologic section showing average potentiometric surfaces of the Madison and Minnelusa aquifers (plates 1 and 2) in relation to hydrogeologic strata (location of sections shown on plates 1 and 2).—Continued 0.5 1 MILES 0.5 1 KILOMETERS 00

C C' FEET

5,0004,0003,0002,000

D D' FEET

5,0004,0003,0002,000 VERTICAL EXAGGERATION X3.3

DATUM IS SEA LEVEL

Boxelder Creek

Boxelder Creek

Boxelder Creek

Boxelder Creek

Boxelder Creek

Boxelder Creek

Altitude of tops of hydrogeologic units modified

from Carter and Redden, 1999a, 1999b, 1999c

OVERLYING HYDROGEOLOGIC UNITSMINNELUSA HYDROGEOLOGIC UNITMADISON HYDROGEOLOGIC UNITUNDERLYING HYDROGEOLOGIC UNITS

MINNELUSA AQUIFERMADISON AQUIFER

POTENTIOMETRIC SURFACE OF MINNELUSA AQUIFER--Dashed in confining unit POTENTIOMETRIC SURFACE OF MADISON AQUIFER--Dashed in confining unit 

Syncline

EXPLANATION

Anticline

Syncline Anticline

West East
38 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 22. Hydrogeologic section showing average potentiometric surfaces of the Madison and Minnelusa aquifers (plates 1 and2) in relation to hydrogeologic strata (location of sections shown on plates 1 and 2).—Continued

0.5 1 MILES

0.5 1 KILOMETERS

00

E E' FEET

5,0004,0003,0002,000

F F' FEET

5,0004,0003,0002,000 VERTICAL EXAGGERATION X3.3

DATUM IS SEA LEVEL

Altitude of tops of hydrogeologic units modified

from Carter and Redden, 1999a, 1999b, 1999c

OVERLYING HYDROGEOLOGIC UNITSMINNELUSA HYDROGEOLOGIC UNITMADISON HYDROGEOLOGIC UNITUNDERLYING HYDROGEOLOGIC UNITS

MINNELUSA AQUIFERMADISON AQUIFER

POTENTIOMETRIC SURFACE OF MINNELUSA AQUIFER--Dashed in confining unit POTENTIOMETRIC SURFACE OF MADISON AQUIFER--Dashed in confining unit 

EXPLANATION

Rapid Creek

Rapid Creek

Jackson-Cleghorn Springs

Syncline

Anticline

West East
Hydraulic Head and Ground-Water Flow 39 Figure 22. Hydrogeologic section showing average potentiometric surfaces of the Madison and Minnelusa aquifers (plates 1 and 2) in relation to hydrogeologic strata (location of sections shown on plates 1 and 2).—Continued 0.5 1 MILES 0.5 1 KILOMETERS 00

G G' FEET

5,0004,0003,0002,000

H H' FEET

5,0004,0003,0002,000 VERTICAL EXAGGERATION X3.3

DATUM IS SEA LEVEL

Spring Creek

Spring Creek

Spring Creek

Spring Creek

Spring Creek

Altitude of tops of hydrogeologic units modified

from Carter and Redden, 1999a, 1999b, 1999c

OVERLYING HYDROGEOLOGIC UNITSMINNELUSA HYDROGEOLOGIC UNITMADISON HYDROGEOLOGIC UNITUNDERLYING HYDROGEOLOGIC UNITS

MINNELUSA AQUIFERMADISON AQUIFER

POTENTIOMETRIC SURFACE OF MINNELUSA AQUIFER--Dashed in confining unit POTENTIOMETRIC SURFACE OF MADISON AQUIFER--Dashed in confining unit 

EXPLANATION

Syncline

Anticline

West East
40 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 23. Generalized ground-water flowpath in the Madison aquifer determined from Boxelder Creek dye test.

Rapid

Spring

Boxelder

Creek

Creek

Creek

T.3N.T.2N.T.1N.T.1S.

R. 9 E. R. 8 E. R. 7 E. R. 6 E.

R. 5 E.

RAPID CITY

2,500

2,500

2,600

2,600

2,700

2,700

2,800

2,800

2,900

2,900

3,000

3,100

3,200

3,300

3,400

3,500

3,600

3,000

3,100

3,200

3,300

3,400

3,500

BHPL

RC-5

RC-10

RC-8

RC-9

CQ-2

WT-2

City Springsand RC-6

JacksonCleghornSpring

1 2 3 4 5 6 MILES

1 2 3 4 5 6 KILOMETERS

00

SOUTH DAKOTA

AreaShown

Aquifer analysis area

BlackHills

OUTCROP OF THE MADISON HYDROGEOLOGIC UNIT (modified from Strobel and others, 1999)MADISON AQUIFER CONFINED AREAMADISON AQUIFER UNCONFINED (WATER TABLE) AREAUNCONFINED (WATER TABLE) AREA OF THE MADISON CONFINING UNITFAULT--Dashed where approximated. Bar and ball on downthrown sideANTICLINE--Showing trace of axial plane and direction of plunge. Dashed where approximatedSYNCLINE--Showing trace of axial plane and direction of plunge. Dashed where approximatedMONOCLINE--Showing trace of axial plane. Dashed where approximatedMADISON AQUIFER POTENTIOMETRIC CONTOUR (average, water years 1988-97)--Shows altitude at which water would have stood in tightly cased, nonpumping well. Contour interval 100 feet. Datum is sea levelPOTENTIAL GROUND-WATER FLOWPATHDYE RELEASED INTO STREAMWELLS AND SPRINGS WHERE DYE WAS DETECTED (from Greene, 1999)WELLS AND SPRINGS WHERE DYE WAS NOT DETECTED (from Greene, 1999)

EXPLANATION

RC-6

RC-9

44o10'

103o30'

103o20' 103o10'

44o00'

44o05'

RC-8RC-10CQ-2RC-6BHPLWT-2RC-9RC-5

2632333536404979

Well

name

Site

number

(table 28)

Base from U.S. Geological Survey digital data, 1:100,000, 1977Rapid City, Office of City Engineer map, 1:18,000, 1996Universal Transverse Mercator projection, zone 13
Hydraulic Head and Ground-Water Flow 41

Boxelder Creek, Rapid Creek, and Spring Creek 

have unique isotopic signatures in recharge water, 

which makes estimation of flowpaths possible in some 

locations. With respect to δ18O, Spring Creek is the isotopically heaviest of the three streams, Boxelder Creek 

is lightest, and Rapid Creek is between the two (table 6, 

fig. 24). Precipitation is isotopically lightest in the 

northwestern part of the study area and becomes 

heavier to the southeast. Figure 25 presents a generalized distribution of δ18O in surface water and ground 

water near recharge areas (Naus and others, 2001). 

Figure 26 shows flowpaths interpreted from 

isotope analysis and other information previously 

described. The flowpaths originate from streamflowloss zones in the central and southern areas and from 

areal outcrop recharge in the northern area where the 

Madison outcrop is large. δ18O values in the Madison 

aquifer in the Rapid City area (Naus and others, 2001) 

were grouped into three ranges: a heavy range (greater 

than -13 per mil) indicating Spring Creek origin, a 

medium range (-13 to -14 per mil) indicating Rapid 

Creek origin, and a light range (less than -14 per mil) 

indicating Boxelder Creek origin. The -13 to -14 per 

mil range also is representative of areal recharge to the 

north of Boxelder Creek (fig. 25) where the influence of 

areal recharge is relatively large because of the large 

outcrop area. Ranges indicating recharge from Rapid 

Creek and Boxelder Creek are heavier than the values 

shown in table 6 because of mixing with areal recharge 

from the outcrop, which is isotopically heavier. 

Figure 25 shows that stream basins collect water from 

isotopically lighter areas and recharge the aquifers in 

areas where areal recharge is isotopically heavier. The 

exception to this is Spring Creek, where the basin centroid is isotopically similar to the outcrop area near its 

loss zone. 

Table 6. Summary of δ18O for Spring Creek, Rapid Creek, and Boxelder Creek

[Values reported by Naus and others (2001) for sampling locations upstream from loss zones]

Site

number

(fig. 25)

Gaging station name and number

Number

of

samples

δ18O value (per mil)

Average Maximum Minimum

24 Spring Creek near Keystone (06407500) 41 -12.6 -10.7 -14.1

30 Rapid Creek above Victoria Creek (06412200) 39 -14.2 -13.4 -15.2

34 Boxelder Creek near Nemo (06422500) 33 -15.4 -14.3 -17.1

Figure 24. Temporal variation of δ18O in Spring Creek,

Rapid Creek, and Boxelder Creek (modified from Naus and

others, 2001).

CALENDAR YEAR

-18

-10

-17

-15

-13

-11

-16

-14

-12

δ18O, IN PER MIL (‰)

EXPLANATION

SPRING CREEK NEAR KEYSTONE (06407500)

RAPID CREEK ABOVE VICTORIA CREEK (06412200)

BOXELDER CREEK NEAR NEMO (06422500)

1993 1994 1996 1995 1997 1998
42 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 25. Generalized distribution of δ18O in surface water and ground water near recharge areas. Contours

indicate δ18O values of areal-recharge water, whereas δ18O values of streamflow-gaging stations indicate that

of streamflow recharge.

Elk

Rapid

Creek

Rapid

Spring

Creek

Creek

Battle

Creek

Boxelder

Creek

Creek

Pactola

Reservoir

Sheridan

Lake

Deerfield

Reservoir

DEADWOOD

Lead

Piedmont

Black Hawk

Box

Elder

RAPID CITY

Hermosa

Hill City

CUSTER

Tilford

Roubaix

Keystone

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

T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

T. 1 S.

T. 2 S.

T. 3 S.

90

90

14

385 16A

16A

16A

385

385

16

16

16

14

14A 14A

85

85

79

79

87

244

87

89

36

40

40

44

44

PENNINGTON CO

PENNINGTON CO

LAWRENCE CO

LAWRENCE CO MEADE CO

CUSTER CO

Rapid

City

Airport

-15

-12

-13

-14

-15

-16

-17

34

-15.4

34

-15.4

30

14.2

24

-12.6

44o

15'

45' 30' 15' 103o

104o

44o

43o

45'

2 4 6 MILES

0 2 4 6 KILOMETERS

0 Base from U.S. Geological Survey digital data, 1:100,000, 1977

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

Universal Transverse Mercator projection, zone 13

OUTCROP OF THE MADISON HYDROGEOLOGIC

 UNIT (modified from Strobel and others, 1999)

OUTCROP OF THE MINNELUSA HYDROGEOLOGIC

 UNIT (modified from Strobel and others, 1999)

EXPLANATION

DRAINAGE AREAS CONTRIBUTING TO

 STREAMFLOW LOSS

AQUIFER ANALYSIS AREA

STREAMFLOW-GAGING STATION--Numbers indicate

 gage-site table and average δ18O value in per mil

LINE OF EQUAL AVERAGE δ18O VALUE--Contour interval

 1 per mil (modified from Naus and others, 2001)
Hydraulic Head and Ground-Water Flow 43Figure 26. Generalized ground-water flowpaths in the Madison aquifer based on δ18O.

Rapid

Spring

Boxelder

Creek

Creek

Creek

T.3N.T.2N.T.1N.T.1S.

R. 9 E. R. 8 E. R. 7 E. R. 6 E.

R. 5 E.

RAPID CITY

2,500

2,500

2,600

2,600

2,700

2,700

2,800

2,800

2,900

2,900

3,000

3,100

3,200

3,300

3,400

3,500

3,600

3,000

3,100

3,200

3,300

3,400

3,500

3

2

1

5

5

4

6

7

8

BHPL

RC-5

RC-10

RC-8

RC-9

CQ-2

WT-2

JacksonCleghornSpring

City Springsand RC-6

FAULT--Dashed where approximated. Bar and ball on downthrown sideANTICLINE--Showing trace of axial plane and direction of plunge. Dashed where approximatedSYNCLINE--Showing trace of axial plane and direction of plunge. Dashed where approximatedMONOCLINE--Showing trace of axial plane. Dashed where approximatedMADISON AQUIFER POTENTIOMETRIC CONTOUR (average, water years 1988-97)--Shows altitude at which water would have stood in tightly cased, nonpumping well. Contour interval 100 feet. Datum is sea levelPOTENTIAL GROUND-WATER FLOWPATHS-- Number is flowpath label

δ18O less than -14 (light)

δ18O -14 to -13 (medium)δ18O greater than -13 (heavy) 

OUTCROP OF THE MADISON HYDROGEOLOGIC UNIT (modified from Strobel and others, 1999)MADISON AQUIFER CONFINED AREAMADISON AQUIFER UNCONFINED (WATER TABLE) AREAUNCONFINED (WATER TABLE) AREA OF THE MADISON CONFINING UNIT

EXPLANATION

RC-6

WT-2

RC-9

44o10'

103o30'

103o20' 103o10'

44o00'

44o05'

SAMPLE SITES--Letters and numbers indicate well name. δ18O values, in per mil, from Naus and

 others (2001)

RC-8RC-10CQ-2RC-6BHPLWT-2RC-9RC-5

2632333536404979

Well

name

Site

number

(table 28)

1 2 3 4 5 6 MILES

1 2 3 4 5 6 KILOMETERS

00

Base from U.S. Geological Survey digital data, 1:100,000, 1977Rapid City, Office of City Engineer map, 1:18,000, 1996Universal Transverse Mercator projection, zone 13
44 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Ground-water flowpaths in the Madison aquifer 

probably are influenced by the large and stable discharge (about 22 ft3

/s) of Jackson-Cleghorn Springs 

(Anderson and others, 1999). Naus and others (2001) 

reported a δ18O value of -12.92 per mil (average from 

1986 to 1998) for Jackson-Cleghorn Springs, which 

indicates a large, and probably dominant, contribution 

from the south (table 6). Numerous other sites in the 

heavy range (greater than -13 per mil) indicate a northward flowpath (fig. 26, flowpath 2) from Spring Creek 

as well. This interpretation is consistent with conclusions of Anderson and others (1999) and Greene 

(1997). Streamflow recharge from Spring Creek combined with outcrop recharge between Spring Creek and 

Rapid Creek is estimated at about 12 ft3

/s on average 

(see “Water Budget” section). The steady streamflowloss rate from Rapid Creek of about 10 ft3/s to the 

Madison and Minnelusa outcrops (Hortness and 

Driscoll, 1998) is the maximum that Rapid Creek could 

supply to Jackson-Cleghorn Springs. Based on these 

recharge rates and discharge at the spring complex, all 

of the streamflow recharge from Spring Creek probably 

moves northward during periods of lower streamflows; 

some of this recharge probably moves easterly during 

higher streamflow periods (flowpath 1). Because of 

these temporal variations in flow direction, ground 

water surrounding the Spring Creek loss zone could be 

a mixture of Spring Creek water and water from farther 

south.

Because of the sites east of the Rapid Creek loss 

zone indicating water from the south, Rapid Creek 

streamflow recharge probably moves initially northward, then eastward in the Madison aquifer (fig. 26, 

flowpath 3). Anderson and others (1999) drew similar 

conclusions based on isotope analysis. Probably, some 

of the water recharged from Rapid Creek discharges 

from Jackson-Cleghorn Springs and some continues to 

the east.

The light-range isotope value near flowpath 5 

(fig. 26) is similar to values for Boxelder Creek and 

probably results from streamflow recharge that occurs 

within the isolated Madison outcrop on the east side of 

the anticline. δ18O values for two sites that are farther 

east near Boxelder Creek are slightly heavier and probably indicate influence from areal recharge north of 

Boxelder Creek (flowpaths 6, 7, and 8). 

The Boxelder Creek dye-tracer flowpath 

(fig. 23) coincides with δ18O values in the light range 

as well. The δ18O values along flowpath 4 that are 

influenced by water originating from Boxelder Creek 

are isotopically heavier than the stream water due to 

mixing with areal recharge water. The two δ18O values 

to the northeast of Rapid City in the light range indicate 

that flowpath 4 probably extends farther eastward in 

that direction.

Although light δ18O at RC-5 and RC-8 (fig. 26) 

indicate the presence of water recharged from Boxelder 

Creek, dye was not detected in these wells. Non detection of dye does not necessarily indicate the absence of 

water recharged from Boxelder Creek, but does indicate that preferential flowpaths were not being sampled. Furthermore, flowpaths could be somewhat 

transient in nature, influenced by factors such as 

changing hydraulic head, pumping, or dual porosity.

Sufficient information is not available for estimation of flowpaths in the Minnelusa aquifer; however, 

increased ground-water circulation in the Minnelusa 

aquifer could, in part, be the result of collapse of solution features in the Madison aquifer where there is a 

convergence of preferential flowpaths in the high-flow 

area (fig. 11). The easterly bulge in the transition zone 

between low and high sulfate concentrations in the 

Minnelusa aquifer (fig. 12) is congruent with flowpath 4 (fig. 26). Some of this converging water in the 

Madison aquifer discharges to springs; some probably 

leaks upward through fractures, faults, and breccia 

pipes into the Minnelusa aquifer, then flows outward; 

and some flows eastward in the Madison aquifer. Much 

of the water that flows eastward in the Madison aquifer 

probably flows toward the zone of high transmissivity 

in the east-central part of the aquifer analysis area 

(fig. 9).

WATER-BUDGET ANALYSIS

Water-budget analysis of the Madison and 

Minnelusa hydrogeologic units included a 10-year 

period, WY88-97. Adequate data were available for 

this period, which includes periods of low and high 

recharge rates that represent long-term variability 

(Carter, Driscoll, and Hamade, 2001) fairly well.

Generally, ground-water levels declined during 

the first 5 or 6 years, then steadily rose during the 

remaining time (fig. 16). The 10-year period was 
Water-Budget Analysis 45

divided into 20 seasonal stress periods for analysis. 

Each water year was divided into a winter period 

(October 1 through March 31), which generally has 

relatively low precipitation, and a summer period 

(April 1 through September 30), which generally has 

greater precipitation.

The water-budget conceptual model (fig. 27) 

includes the inflows and outflows as well as the general 

flow interactions within the model. The northern and 

southern boundaries of the aquifer analysis area are 

approximately perpendicular to potentiometric contours (pls. 1 and 2) and, therefore, were assumed to be 

boundaries where ground-water flow does not cross 

(pl. 3). Isotropic conditions near boundaries also were 

assumed. In order to balance a water budget, it was necessary to include many other simplifying assumptions 

and approximations because of incomplete data in 

many cases.

General Concepts

General concepts and water-budget summaries 

are described in this section, followed by detailed discussions of methods and results for individual budget 

components. Three budgets were developed: (1) a dryperiod budget for declining water levels, (2) a wetperiod budget for rising water levels, and (3) a fullperiod budget. All inflows and outflows were estimated 

separately for the Madison and Minnelusa aquifers. In 

general, hydraulic head declined during the dry-period 

budget (October 1, 1987, to March 31, 1993, 5.5 years) 

resulting in a decrease in storage. Hydraulic head rose 

during the wet-period budget (April 1, 1993, to 

September 30, 1997, 4.5 years) resulting in an increase 

in storage. By simultaneously balancing three water 

budgets, initial estimates of recharge, discharge, 

change in storage, and hydraulic properties were 

refined. 

Figure 27. Conceptual model of water budget.

Deadwood aquifer

Madison confining unit

Minnelusa

confining

unit

Minnelusa aquifer

Madison aquifer

Spring wells

Water use Discharge to

overlying units

Discharge by regional outflow

EXPLANATION

AQUIFER

CONFINING UNIT

WELL

BRECCIA PIPE

FLOW DIRECTION AREAL RECHARGE

STREAMFLOW RECHARGE
46 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Water-budget results are summarized in tables 7 

through 9. The equation for balancing the water budgets is the sum of inflows minus the sum of outflows, 

which is equal to the change in storage or:

(2)

where

∆S = change in ground-water storage;

SD = seepage from Deadwood aquifer;

SR = streamflow recharge;

AR = areal recharge; 

SF = springflow;

WU = water use;

OO = outflow to overlying units; and

OE = outflow across eastern boundary.

Independent estimates of changes in storage for 

each of the three budgets could be made because there 

were two distinct periods of storage change during the 

10-year period. Change in ground-water storage was 

computed by estimating the rise or fall in the potentiometric surface and multiplying this difference by area 

and specific yield for unconfined areas or by storage 

coefficient for confined areas. Hydraulic-head records 

for continuous-record observation wells (figs. 18 

and 19, pls. 1 and 2) were used to estimate change in 

hydraulic head over the aquifer analysis area for the 

two periods. Some of the wells did not exist in October 

1987, so water levels for part of the 10-year period 

were estimated based on comparisons to other wells 

with continuous records. Hydraulic head was interpolated between wells and extrapolated out to the boundaries of the aquifer analysis area. Most of the wells are 

located near the unconfined areas, and therefore gave a 

fairly accurate estimate of hydraulic head in the unconfined area. Potential error in the estimate of hydraulichead change was estimated to be 15 percent.

Specific yield in the unconfined area is about 

three orders of magnitude larger than storage coefficient in the confined areas. Thus, change in storage in 

the confined areas is negligible by comparison, and the 

accuracy of hydraulic-head change in the confined 

areas is of little concern. The estimated hydraulic-head 

change over the aquifer analysis area was discretized 

into square cells 100 ft on a side to accurately quantify 

the change in storage in all areas.

Changes in hydraulic gradient across the eastern 

boundary were assumed to be small; therefore, regional 

outflow across the eastern boundary was assumed constant in all three budgets. Inflow from and outflow to 

adjacent hydrogeologic units also were assumed to be 

constant. Seepage from the Deadwood aquifer was estimated based on the approximate hydraulic head difference between the Madison and Deadwood aquifers 

and an estimated vertical hydraulic conductivity. A 

smaller amount was assumed to seep upward from the 

Minnelusa aquifer into overlying units.

∆S SD SR AR = ( ) + + – ( ) SF WU OO OE +++

Table 7. Average water budget for WY88-97 (full 10-year budget)

[Flow rate in cubic feet per second (ft3/s); Mdsn, Madison hydrogeologic unit; Mnls, Minnelusa hydrogeologic unit]

Component

Mdsn Mnls Total

Relative

confidence

in estimates

Flow rate 

(ft3/s)

Percent

of Mdsn 

budget

Flow rate 

(ft3/s)

Percent

of Mnls 

budget

Flow rate 

(ft3/s)

Percent

of total 

budget

Inflow Streamflow recharge 38.8 63.4 6.5 32.2 45.3 61.4 High

Areal recharge 16.1 26.3 6.1 30.2 22.2 30.1 Medium

Seepage from Deadwood aquifer 6.3 10.3 0 0 6.3 8.5 Low

Outflow Springflow -30.8 -50.3 0.0 0.0 -30.8 41.7 High

Water use -6.7 10.9 -3.4 16.8 -10.1 13.7 High

Leakage to units overlying Mnls 0 0 -2.0 9.9 -2.0 2.7 Low

Regional outflow -11.0 18.0 -11.2 55.4 -22.2 30.1 Medium

Leakage between Madison

and Minnelusa hydrogeologic units

-7.6 12.4 7.6 37.6 0 0 Medium

Change in storage (as a flow rate) 5.1 8.3 3.6 17.8 8.7 11.8 Medium
Water-Budget Analysis 47

Table 8. Average water budget for October 1987 through March 1993 (dry period)

[Flow rate in cubic feet per second (ft3/s); Mdsn, Madison hydrogeologic unit; Mnls, Minnelusa hydrogeologic unit]

Component

Mdsn Mnls Total

Relative

confidence

in estimates

Flow rate 

(ft3/s)

Percent

of Mdsn 

budget

Flow rate 

(ft3/s)

Percent

of Mnls 

budget

Flow rate 

(ft3/s)

Percent

of total 

budget

Inflow Stream-loss recharge 24.1 51.9 2.8 16.7 26.9 46.7 High

Areal recharge 8.2 17.7 3.1 18.5 11.3 19.6 Medium

From Deadwood aquifer 6.3 13.6 0 0 6.3 10.9 Low

Outflow Springflow -25.3 54.5 0 0 -25.3 43.9 High

Water use -4.5 9.7 -3.6 21.4 -8.1 14.1 High

Leakage to units overlying Mnls 0 0 -2.0 11.9 -2.0 3.5 Low

Regional outflow -11.0 23.7 -11.2 66.7 -22.2 38.5 Medium

Leakage between Madison and

Minnelusa hydrogeologic units

-5.6 12.1 5.6 33.3 0 0 Medium

Change in storage (as a flow rate) -7.8 16.8 -5.3 31.5 -13.1 22.7 Medium

Table 9. Average water budget for April 1993 to September 1997 (wet period)

[Flow rate in cubic feet per second (ft3/s); Mdsn, Madison hydrogeologic unit; Mnls, Minnelusa hydrogeologic unit]

Component

Mdsn Mnls Total

Relative

confidence

in estimates

Flow rate 

(ft3/s)

Percent

of Mdsn 

budget

Flow rate 

(ft3/s)

Percent

of Mnls 

budget

Flow rate 

(ft3/s)

Percent

of total 

budget

Inflow Stream-loss recharge 56.9 63.9 ‘ 11.1 35.6 68.0 61.8 High

Areal recharge 25.9 29.1 9.8 31.4 35.7 32.5 Medium

From Deadwood aquifer 6.3 7.1 0 0 6.3 5.7 Low

Outflow Springflow -37.4 42.0 0 0 -37.4 34.0 High

Water use -9.3 10.4 -3.2 10.3 -12.5 11.4 High

Leakage to units overlying Mnls 0 0 -2.0 6.4 -2.0 1.8 Low

Regional outflow -11.0 12.3 -11.2 35.9 -22.2 20.2 Medium

Leakage between Madison and

Minnelusa hydrogeologic units

-10.3 11.6 10.3 33.0 0 0 Medium

Change in storage (as a flow rate) 21.1 23.7 14.8 47.4 35.9 32.6 Medium
48 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Streamflow recharge, springflow, and water use 

were known or estimated with a relatively high level of 

confidence because these estimates generally were 

based on measured values. Estimates of areal recharge, 

outflow across the eastern boundary, leakage between 

aquifer units, inflow and outflow to adjacent hydrogeologic units, and change in storage were less certain. 

Simultaneously balancing the three water budgets provided an additional constraint to test estimates of the 

less certain water-budget components. Preliminary 

estimates of these less certain components were modified within plausible ranges. Transmissivities were 

adjusted within reasonable ranges to modify calculations of outflow across the eastern boundary. Estimates 

of changes in storage were modified by adjusting 

specific yield and estimated hydraulic-head change. 

Leakage between the Madison and Minnelusa hydrogeologic units was estimated by balancing the three 

water budgets. 

Although the solution to the budget equation was 

not unique, the requirement that all three budgets 

simultaneously balance constrained the solution and 

improved estimates of specific yield and aquifer transmissivity near the eastern boundary. The two shortperiod budgets were especially sensitive to changes in 

specific yield, and thus, storage volume. Because the 

net change in storage for the 10-year period was small, 

the 10-year budget was more sensitive to transmissivity 

near the eastern boundary, which affected regional 

outflow.

Flow rates for selected water-budget components 

are listed in table 10 for each 6-month stress period. 

Average streamflow recharge to the Madison hydrogeologic unit was about 2.4 times that of areal recharge, 

while streamflow recharge to the Minnelusa hydrogeologic unit was about equal to areal recharge (table 7). 

This contrast is primarily due to the larger loss thresholds on the Madison outcrop and because streams lose 

to the Madison outcrop first, which often leaves little or 

no flow to cross the Minnelusa outcrop. 

The Minnelusa hydrogeologic unit received 

about 7.6 ft3

/s or 38 percent of its total inflow (table 7) 

in the form of net leakage from the Madison hydrogeologic unit. The mechanisms that produce leakage 

between the Madison and Minnelusa aquifers are probably similar to those responsible for artesian springflow 

from the Madison aquifer. Therefore, the estimated net 

leakage from the Madison to the Minnelusa hydrogeologic unit of about 7.6 ft3

/s is plausible in comparison 

to the average flow from all Madison aquifer springs 

passing through the Minnelusa hydrogeologic unit, 

which was about 31 ft3/s (tables 7 and 10). In general, 

hydraulic head was higher at the end of the 10 years 

than at the beginning. The largest discharge component 

from the Minnelusa hydrogeologic unit was regional 

outflow, whereas the largest discharge from the 

Madison hydrogeologic unit was springflow.

In addition to the 10-year water budget, two 

additional water budgets representing the first and 

second parts of the 10-year period were useful for 

refining the estimates of less certain water budget components (tables 8 and 9). The three largest total-budget 

components for the 10-year period (table 7) were 

streamflow recharge, springflow, and areal recharge. 

The largest total-budget components for the dry period 

(table 8) were streamflow recharge, springflow, and 

regional outflow, whereas the largest components for 

the wet period (table 9) were streamflow recharge, 

springflow, and change in storage. The total recharge 

rate during the wet period was about 110 ft3/s or about 

2.4 times the recharge rate during the dry period, which 

was 45 ft3/s. 

Seepage from Deadwood Aquifer

Underlying the Madison hydrogeologic unit are 

older rocks that potentially provide an additional 

source of recharge to the Madison hydrogeologic unit. 

These rocks primarily consist of the Cambrian-age 

Deadwood Formation, which contains a sandstone 

aquifer, and underlying Precambrian-age igneous and 

metamorphic rocks. Although the lower part of the 

Madison hydrogeologic unit generally is a confining 

unit, fractured and weathered areas near the outcrop 

provide paths for movement of water from these older 

rocks into the Madison hydrogeologic unit. 

The seepage rate from the Deadwood aquifer 

into the Madison aquifer was estimated as 6.3 ft3/s 

within the aquifer analysis area using Darcy’s Law. 

Darcy’s Law is given by the equation:

(3)

where

Q = flow rate [V/T];

Kv = vertical hydraulic conductivity for the Madison confining unit [L/T];

A = area where upward leakage takes place [L2];

∆H = hydraulic-head difference between the 

Deadwood and Madison aquifers [L]; and

∆L = vertical distance that corresponds to the 

hydraulic head difference [L].

Q KvA∆H

∆L = -------
Seepage from Deadwood Aquifer 49

Table 10. Selected water-budget components for 6-month stress periods[Flow rates in cubic feet per second (ft3/s)]

Stress period Dates

Madison hydrogeologic unit Minnelusa hydrogeologic unit

Streamflow 

recharge

Areal 

recharge Springflow Water use Streamflow recharge Areal recharge Water use

Dry period

Winter 1988 (W-88) October 1, 1987 - March 31, 1988 15.6 0.9 26.6 1.9 2.0 0.2 2.9Summer 1988 (S-88) April 1, 1988 - September 30, 1988 19.0 1.9 25.7 4.7 2.2 .5 5.7Winter 1989 (W-89) October 1, 1988 - March 31, 1989 12.3 1.6 25.4 1.7 1.8 .6 1.7Summer 1989 (S-89) April 1, 1989 - September 30, 1989 18.0 10.0 25.1 3.4 2.1 4.0 3.7Winter 1990 (W-90) October 1, 1989 - March 31, 1990 16.5 3.2 25.2 1.8 2.0 1.0 2.9Summer 1990 (S-90) April 1, 1990 - September 30, 1990 35.3 7.4 25.2 4.2 3.2 4.1 4.9Winter 1991 (W-91) October 1, 1990 - March 31, 1991 15.7 1.8 24.8 2.9 1.8 .5 3.3Summer 1991 (S-91) April 1, 1991 - September 30, 1991 54.4 52.5 25.8 7.2 8.8 19.5 4.6Winter 1992 (W-92) October 1, 1991 - March 31, 1992 27.5 2.4 25.0 5.4 2.2 .8 2.6Summer 1992 (S-92) April 1, 1992 - September 30, 1992 29.9 5.9 24.8 12.5 2.2 2.3 4.3Winter 1993 (W-93) October 1, 1992 - March 31, 1993 20.6 2.2 25.0 3.7 2.3 .5 2.6

Average for dry period 24.1 8.2 25.3 4.5 2.8 3.1 3.6

Wet period

Summer 1993 (S-93) April 1, 1993 - September 30, 1993 69.4 46.0 26.8 13.7 14.1 19.9 4.0Winter 1994 (W-94) October 1, 1993 - March 31, 1994 39.6 2.9 26.3 6.2 3.9 .5 2.1Summer 1994 (S-94) April 1, 1994 - September 30, 1994 47.2 2.0 26.2 15.1 9.4 1.0 4.1Winter 1995 (W-95) October 1, 1994- March 31, 1995 32.3 6.5 34.8 5.8 2.7 1.5 2.3Summer 1995 (S-95) April 1, 1995 - September 30, 1995 67.4 72.7 36.8 11.0 14.9 25.7 3.7Winter 1996 (W-96) October 1, 1995 - March 31, 1996 46.1 5.8 37.9 3.1 3.8 1.3 2.1Summer 1996 (S-96) April 1, 1996 - September 30, 1996 71.5 31.1 39.1 11.3 17.5 11.5 4.0Winter 1997 (W-97) October 1, 1996 - March 31, 1997 60.6 9.6 53.6 5.5 8.9 3.2 2.5Summer 1997 (S-97) April 1, 1997 - September 30, 1997 77.8 56.3 55.0 12.0 24.4 23.3 4.1

Average for wet period 56.9 25.9 37.4 9.3 11.1 9.8 3.2Overall average 38.8 16.1 30.8 6.7 6.5 6.1 3.4
50 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

The area where upward seepage is considered to 

take place is between the western extent of the Madison 

outcrop and the Inyan Kara Group outcrop (171 mi2; 

fig. 4). A general range of Kv values for limestone 

and dolomite is about 10-4 to 10-2 ft/d (Domenico and 

Schwartz, 1990, p. 67). Kv is likely to be higher toward 

the outcrop because of uplift and fracturing and lower 

toward the east. East of the Inyan Kara Group outcrop, 

upward seepage is assumed to be minimal and is 

neglected. As an average for the area west of the Inyan 

Kara outcrop, Kv was taken as 3x10-4 ft/d. Hydraulic 

head in the Deadwood aquifer was estimated to be 

about 100 ft on average above the Madison aquifer in 

the seepage area. The estimated length of ∆L includes 

the thickness of the Madison confining unit (250 ft) 

plus about one-half of the Deadwood Formation thickness (100 ft) for a total of 350 ft. The Whitewood and 

Winnipeg Formations are absent throughout most of 

the aquifer analysis area.

Streamflow Recharge

Streams lose much or all of their flow into 

swallow holes and fractures on the Madison and 

Minnelusa outcrops. Swallow holes are solutional 

features that extend upward to the land surface and 

intercept stream water. The Madison outcrop receives 

preferential recharge because of its upstream location. 

Large streamflow recharge rates of more than 25 ft3

/s 

to the Madison aquifer (Hortness and Driscoll, 1998) 

may have led to extensive karst development near 

streamflow-loss areas. Streamflow recharge to the Minnelusa aquifer also occurs but generally in smaller 

quantities. A description of methods used, a summary 

of streamflow-recharge estimates, and details on 

individual loss zones follow.

Methods

Drainage areas that contribute flow to the streamflow recharge are delineated for the western part of the 

study area (pl. 3). Although streamflow-loss zones are 

shown extending across the entire Madison and Minnelusa outcrop areas, losses are generally concentrated 

in certain areas of the outcrops. Because 

the Madison aquifer is more permeable, much of the 

streamflow lost to the confining unit located on the 

western part of the outcrop probably reaches the aquifer 

via underground conduits. An example of this can 

be seen along Boxelder Creek where much of the 

streamflow lost to the western part of the Madison outcrop reemerges as springflow and then disappears 

again in the eastern part of the loss zone. Rahn and 

Gries (1973) determined from dye testing that Gravel, 

Doty, and Dome Springs (pls. 1 and 2) on the Madison 

outcrop along Boxelder Creek are directly connected to 

upstream losses. At outcrop areas of the Minnelusa 

hydrogeologic unit, ground water probably moves from 

confining unit to aquifer in a similar way because of 

weathering and increased permeability of the confining 

unit.

Streamflow recharge is calculated for 10 streams 

that cross the Madison and Minnelusa outcrops in the 

study area. Daily streamflow records are available for 

the larger streams that lose flow to the outcrops, 

including Battle, Spring, Rapid, Boxelder, and Elk 

Creeks (pl. 3 and table 11). Loss thresholds were determined by Hortness and Driscoll (1998) and were used 

if available, but were not determined for some of the 

smaller streams and were not always separated by formation (table 11). According to Hortness and Driscoll 

(1998), all of the flow in these streams up to a threshold 

is lost to outcrops of Paleozoic rocks. Measured or 

estimated daily streamflow up to an estimated loss 

threshold is assumed to recharge the Madison hydrogeologic unit, and once that threshold flow is exceeded, 

recharge to the Minnelusa hydrogeologic unit (not to 

exceed its threshold) can occur. A diagram representing 

streamflow losses from Elk Creek (fig. 28) illustrates 

that during low-flow periods, such as WY88-90, the 

Minnelusa hydrogeologic unit may receive little or no 

streamflow recharge. 

In some cases, gages were not located at the 

western contact of the Madison hydrogeologic unit, but 

were farther upstream. For these streams, the gaged 

flow was adjusted proportional to drainage area 

(table 11). Some streams were continuously gaged for 

only part of the 10-year period, and a few smaller 

basins were not gaged at all. Missing data for continuously gaged streams were synthesized using linear 

regression of the measured streamflow against streamflow in a nearby basin. The equation of the regression 

line was used to estimate missing parts of the 

hydrograph. Streamflow records for ungaged streams 

were estimated by proportioning flows of nearby gaged 

streams relative to drainage area size.
Seepage from Deadwood Aquifer 51

In the study area, the Minnelusa hydrogeologic 

unit contains “unsaturated areas,” as previously 

defined (see “Concepts of the Ground-Water Flow 

System” section), across about 73 percent of the 

outcrop. Plate 2 shows the extent of saturated and 

unsaturated areas in relation to the outcrops. About 

36 percent of the total length of the losing streams 

crossing the Minnelusa outcrop is on these unsaturated 

areas. Much of the streamflow loss to the unsaturated 

areas of the Minnelusa outcrop probably reaches the 

Madison aquifer because of fractures and breccias that 

extend through the outcrop. According to Gott and 

others (1974), solution breccias in the Minnelusa 

Formation permit rapid infiltration of ground water that 

probably recharges the Madison aquifer. However, 

because of easterly dipping beds, the movement of 

infiltrating water probably has a horizontal component 

and some will reach the Minnelusa hydrogeologic 

unit’s water table. Because of the lack of data to quantify the proportion, 50 percent of this water infiltrating 

the unsaturated area on the Minnelusa outcrop was 

assumed to recharge the Madison aquifer and 

50 percent to recharge the Minnelusa aquifer. Streamflow losses on the Minnelusa outcrop were assumed to 

be evenly distributed across the length of the stream 

reach. Therefore, the fraction of redistributed recharge 

from the Minnelusa outcrop is equal to the ratio of the 

unsaturated-area reach length to the total Minnelusa 

outcrop reach length multiplied by one-half of the loss 

across the Minnelusa outcrop:

Redistributed recharge = . (4) Dry reach length

Total outcrop reach length

---------------------------------------------------------------     Minnelusa outcrop loss

2 -------------------------------------------------------     ×

Figure 28. Hydrograph of monthly mean streamflow losses from Elk Creek to the Madison and Minnelusa

outcrops. Loss thresholds estimated by Hortness and Driscoll (1998). STREAMFLOW-LOSS RATE, IN CUBIC FEET PER SECOND

0

20

40

60

80

100

120

140

160

180

Oct87Apr88Oct88Apr89Oct89Apr90Oct90Apr91Oct91Apr92Oct92Apr93Oct93Apr94Oct94Apr95Oct95Apr96Oct96Apr97Oct97

Flow across Minnelusa outcrop

Loss to Minnelusa outcrop

Loss to Madison outcrop

Loss threshold for Madison outcrop

Total loss threshold for Madison

 and Minnelusa outcrop
52 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model Table 11. Selected data for drainage areas, streamflow, and gaging stations [WY, water year; Mdsn, Madison hydrogeologic unit; Mnls, Minnelusa hydrogeologic unit; mi2, square miles; ft3/s, cubic feet per second; mi, miles; --, undetermined; NA, not applicable] Drainage areas contributing to streamflow-loss zones Streamflow-loss-zone data Streamflow-gaging stations used in calculation of streamflow loss or springflow1 Loss-zone stream reach length Approximate loss threshold Drain- age area identi- fier (pl. 3) Name Area (mi2) Average annual precipitation2 1961-98 (inches) Average annual streamflow, WY88-97 (ft3/s) Average annual yield, WY88-97 (inches) Mdsn (mi) Mnls (mi) Mdsn (ft3/s) Mnls (ft3/s) Gage- site number3 (pl. 3) Station identification number Station name Drainage area4 (mi2)

A Battle Creek 66.0 21.1 13.1 2.70 1.2 -- 514 6

0 14 06404000 Battle Creek near 

Keystone

58.4

B Deadman Gulch 1.49 19.9 7.2 71.82 1.5 4.8 72 7

4

C Rockerville Gulch 3.68 19.5 7.7 72.58 .8 4.7 72 7

4

D Spring Creek 163 20.6 25.3 2.11 2.3 2.4 821 53.5 24 06407500 Spring Creek near 

Keystone

163

E Victoria Creek 11.1 19.8 71.6 71.96 .6 NA 82.1 NA

F Rapid Creek 355 22.4 59.0 2.26 2.2 1.8 8 2 30 06412200 Rapid Creek above 

Victoria Creek

355

G Unnamed tributary .92 20.1 7.1 71.48 1.5 5.4 72 7

4

H Boxelder Creek 103 23.1 25.1 3.31 7.9 4.6 730 716 34 06422500 Boxelder Creek near 

Nemo

96

I Little Elk Creek 11.6 23.4 71.9 72.22 .1 1.5 8.7 82.6

J Elk Creek 35.1 26.1 14.0 5.42 8.5 2.4 811 8

8 39 06424000 Elk Creek near 

Roubaix

21.5

NA -- -- -- -- NA NA NA NA 43 44182310324100 Elk Creek below trib 

from north, near Tilford

--

NA -- -- -- -- NA NA NA NA 44 441701103282700 Elk Creek below 

Madison outcrop

--

NA -- -- -- -- NA NA NA NA 45 441614103253300 Elk Creek at Minnekahta outcrop --
Seepage from Deadwood Aquifer 53

NA -- -- -- -- NA NA NA NA 90 906413650 Lime Creek at 

mouth, at Rapid City9

--

NA -- -- -- -- NA NA NA NA 91 906413800 Deadwood Avenue 

drain at mouth, at Rapid City9

--

1Flow rates from U.S. Geological Survey (1989-98).2Calculated from precipitation distribution for 1961-98 (Driscoll, Hamade, and Kenner, 2000).3Site number corresponds to site number in Hortness and Driscoll, 1998.4Drainage area from U.S. Geological Survey (1967-97) except for site number 14, which is a corrected value.5Carter, Driscoll, and Hamade, 2001.6Generally, there is a net gain in streamflow in this reach. During very dry periods, some streamflow loss to the Minnelusa hydrogeologic unit could be possible, however, the impact on the water budget was assumed to be negligible.7Estimated.8Hortness and Driscoll, 1998.9Gaging station used to estimate springflow.

Table 11. Selected data for drainage areas, streamflow, and gaging stations–Continued[WY, water year; Mdsn, Madison hydrogeologic unit; Mnls, Minnelusa hydrogeologic unit; mi2, square miles; ft3/s, cubic feet per second; mi, miles; --, undetermined; NA, not applicable]

Drainage areas contributing to streamflow-loss zones

Streamflow-loss-zone data

Streamflow-gaging stations used in calculation

of streamflow loss or springflow1 Loss-zone stream reach 

length

Approximate 

loss 

threshold

Drainage 

area

identifier

(pl. 3)

 Name Area (mi2)

Average 

annual

precipitation2

1961-98

(inches)

Average

annual

streamflow,

WY88-97

(ft3/s)

Average

annual

yield,

WY88-97

(inches)

Mdsn

(mi)

Mnls

(mi)

Mdsn (ft3/s)

Mnls

(ft3/s)

Gagesite

number3

(pl. 3)

Station

identification

number

Station name

Drainage

area4

(mi2)
54 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Estimation of Streamflow Recharge

Estimated streamflow recharge is presented in 

table 12, which summarizes recharge for both continuously-gaged and ungaged streams. Values in table 12 

have been adjusted, when appropriate, to reflect redistribution of estimated recharge to the Minnelusa outcrop that infiltrates into the Madison hydrogeologic 

unit. Because most of the loss occurs on the Madison 

outcrop, total streamflow recharge to the Madison 

hydrogeologic unit was only increased by about 

1 percent due to redistribution, but streamflow recharge 

to the Minnelusa hydrogeologic unit decreased by 

about 8 percent.

Total estimated streamflow recharge rates for the 

Madison hydrogeologic unit for summer periods 

ranged from about 18 ft3

/s during dry years to almost 

80 ft3/s during wet years (table 12). Total streamflow 

recharge rates for the Madison hydrogeologic unit for 

winter periods ranged from about 12 ft3/s during dry 

years to about 60 ft3/s during wet years. Average 

streamflow recharge to the Minnelusa hydrogeologic 

unit (about 7 ft3

/s) was only about 14 percent of the 

combined streamflow recharge to the Madison and 

Minnelusa aquifers (45 ft3

/s). Increases in recharge 

rates during wet years largely were due to increases in 

the duration and quantity of stream base flow that was 

maintained over longer periods of time. 

Continuously Gaged Streams

Calculations of streamflow recharge to the 

Madison and Minnelusa hydrogeologic units for continuously gaged streams are described in this section. 

Different loss zones required different approaches 

depending on loss-zone characteristics and gage 

location.

Battle Creek

Estimated streamflow recharge from Battle 

Creek to the Madison hydrogeologic unit averaged 

about 2.7 ft3

/s (table 12). Streamflow recharge to the 

Minnelusa hydrogeologic unit was assumed to be zero 

because the stream gains flow as a result of springflow 

along the Minnelusa outcrop (Hortness and Driscoll, 

1998). Battle Creek exceeded its loss threshold to the 

Madison hydrogeologic unit 16 percent of the time 

during WY88-97 and did not flow at the gage upstream 

from the loss zone 6 percent of the time. Gage site 14 

(pl. 3) is located about 2 mi upstream from the loss 

zone, and the drainage area for that location is about 

88 percent of the total basin area contributing to the 

loss zone. Therefore, the gaged flow was increased 

proportionately to account for the ungaged flow. This 

synthetic record was used to compute streamflow 

recharge. 

Spring Creek

Estimated streamflow recharge from Spring 

Creek to the Madison and Minnelusa hydrogeologic 

units averaged 9.9 and 0.8 ft3/s, respectively (table 12). 

Although Spring Creek is impounded by a dam at 

Sheridan Lake, streamflow results primarily from 

uncontrolled overflow and fluctuates similarly to 

uncontrolled streams in the study area. Spring Creek 

has the second largest drainage area in the study area 

(table 11) and accounted for 24 percent of the total 

streamflow recharge to the Madison and Minnelusa 

hydrogeologic units during the 10-year period. Spring 

Creek exceeded its loss threshold of about 25 ft3/s to 

the Madison and Minnelusa hydrogeologic units 

21 percent of the time and did not flow at the gage 

above the loss zone 5 percent of time during the 

10-year period. The continuous gage above the Spring 

Creek loss zone (pl. 3, gage site 24) accounts for all of 

the flow contributing to the loss zone and, therefore, 

required no adjustments to the measured flow.

Rapid Creek

Estimated streamflow recharge from Rapid 

Creek to the Madison and Minnelusa hydrogeologic 

units averaged 8.0 and 2.0 ft3

/s, respectively (table 12). 

Rapid Creek is regulated by releases from Pactola 

Reservoir, and releases greater than the loss threshold 

are generally maintained. Although Rapid Creek has 

the largest drainage area in the study area, the stream 

has a relatively small loss threshold of about 10 ft3/s 

(Hortness and Driscoll, 1998) for the Madison and 

Minnelusa hydrogeologic units combined. Despite the 

small loss threshold, Rapid Creek accounted for about 

22 percent of the total streamflow recharge to the 

Madison and Minnelusa hydrogeologic units because 

flow was seldom less than the threshold. Hortness and 

Driscoll (1998) did not estimate separate loss thresholds for the two hydrogeologic units; however, investigations by Hines (1991) indicate that about 80 percent 

of the total loss threshold can be attributed to the 

Madison hydrogeologic unit.

Flow from Tittle Springs, located on the Madison 

outcrop near Rapid Creek (pl. 1), probably originates 

from Rapid Creek (Hines, 1991). Therefore, this 

springflow was not included in streamflow-recharge or 

water-budget calculations. 
Seepage from Deadwood Aquifer 55

Table 12. Streamflow recharge rates to the Madison and Minnelusa hydrogeologic units

[Recharge rates in cubic feet per second. Mdsn, Madison; Mnls, Minnelusa; W, winter; S, summer (W-88 = winter 1988)]

Stress period

Continuously gaged streams

Battle Creek1 Spring Creek Rapid Creek Boxelder Creek Elk Creek1

Mdsn Mnls Mdsn Mnls Mdsn Mnls Mdsn Mnls Mdsn Mnls

Dry Period

W-88 0.3 0.0 1.1 0.0 8.0 2.0 4.2 0.0 1.2 0.0

S-88 .5 .0 2.5 .0 8.0 2.0 5.7 .0 1.5 .0

W-89 .2 .0 .2 .0 7.9 1.7 2.8 .0 .8 .0

S-89 .7 .0 1.8 .0 8.0 2.0 5.3 .0 1.5 .0

W-90 1.1 .0 1.3 .0 8.0 1.9 4.3 .0 1.2 .0

S-90 4.1 .0 11.2 .9 8.0 2.0 7.7 .0 2.1 .0

W-91 .8 .0 3.1 .0 8.0 1.8 2.4 .0 .7 .0

S-91 4.4 .0 16.8 1.9 8.0 2.0 17.1 2.7 3.8 1.0

W-92 1.5 .0 6.7 .0 8.0 2.0 7.8 .0 1.9 .0

S-92 2.3 .0 8.2 .0 8.0 2.0 6.9 .0 2.9 .1

W-93 1.1 .0 4.1 .1 8.0 1.9 5.0 .1 1.3 .1

Average dry 1.5 .0 5.2 .3 8.0 1.9 6.3 .3 1.7 .1

Wet Period

S-93 5.7 .0 19.9 2.6 8.0 2.0 25.3 5.5 4.8 2.3

W-94 3.3 .0 11.1 .2 8.0 2.0 11.2 .5 3.0 .7

S-94 2.1 .0 11.0 .9 8.0 2.0 19.2 3.8 4.1 1.6

W-95 2.0 .0 7.1 .1 8.0 2.0 9.7 .1 3.5 .2

S-95 5.0 .0 18.0 2.1 8.0 2.0 25.5 6.7 4.6 2.0

W-96 3.1 .0 13.1 .1 8.0 2.0 14.1 .5 4.2 .5

S-96 5.2 .0 20.3 2.5 8.0 2.0 28.8 7.6 3.4 3.4

W-97 4.6 .0 18.5 1.5 8.0 2.0 21.5 2.1 3.1 1.9

S-97 6.0 .0 21.0 3.4 8.0 2.0 32.3 12.6 3.0 3.9

Average wet 4.1 .0 15.6 1.5 8.0 2.0 20.8 4.4 3.7 1.8

Overall average 2.7 .0 9.9 .8 8.0 2.0 12.8 2.1 2.6 .9
56 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

1Loss rate at model boundary. Table shows 50 percent of total loss assumed to enter the aquifer analysis area.

Table 12. Streamflow recharge rates to the Madison and Minnelusa hydrogeologic units—Continued

[Recharge rates in cubic feet per second. Mdsn, Madison; Mnls, Minnelusa; W, winter; S, summer (W-88 = winter 1988)]

Stress period

Ungaged streams

Total of all 

streams

Total 

Mdsn 

Mnls

Deadman Gulch Rockerville 

Gulch Victoria Gulch Unnamed

tributary Little Elk Creek

Mdsn Mnls Mdsn Mnls Mdsn Mnls Mdsn Mnls Mdsn Mnls Mdsn Mnls

Dry Period

W-88 0.1 0.0 0.2 0.0 0.1 0.0 0.0 0.0 0.4 0.0 15.6 2.0 17.6

S-88 .0 .0 .1 .0 .2 .0 .1 .0 .4 .2 19.0 2.2 21.2

W-89 .0 .0 .1 .0 .0 .0 .0 .0 .3 .1 12.3 1.8 14.1

S-89 .0 .0 .1 .0 .1 .0 .0 .0 .5 .1 18.0 2.1 20.1

W-90 .0 .0 .1 .0 .1 .0 .0 .0 .4 .1 16.5 2.0 18.5

S-90 .2 .0 .4 .0 .9 .0 .1 .0 .6 .3 35.3 3.2 38.5

W-91 .1 .0 .1 .0 .2 .0 .0 .0 .3 .0 15.7 1.8 17.5

S-91 .6 .1 1.2 .2 1.4 .0 .2 .0 .9 .9 54.4 8.8 63.2

W-92 .1 .0 .3 .0 .4 .0 .1 .0 .7 .2 27.5 2.2 29.7

S-92 .1 .0 .3 .0 .5 .0 .1 .0 .6 .1 29.9 2.2 32.1

W-93 .1 .0 .2 .0 .3 .0 .0 .0 .5 .1 20.6 2.3 22.9

Average dry .1 .0 .3 .0 .4 .0 .1 .0 .5 .2 24.1 2.8 26.9

Wet Period

S-93 .8 .0 1.7 .1 1.7 .0 .4 .0 1.1 1.6 69.4 14.1 83.5

W-94 .4 .0 .9 .0 .8 .0 .1 .0 .8 .5 39.6 3.9 43.5

S-94 .2 .0 .5 .0 .9 .0 .3 .0 .9 1.1 47.2 9.4 56.6

W-95 .2 .0 .4 .0 .5 .0 .1 .0 .8 .3 32.3 2.7 35.0

S-95 1.1 .1 2.1 .3 1.5 .0 .5 .1 1.1 1.6 67.4 14.9 82.3

W-96 .5 .0 1.2 .0 .9 .0 .1 .0 .9 .7 46.1 3.8 49.9

S-96 .8 .0 1.7 .1 1.7 .0 .5 .0 1.1 1.9 71.5 17.5 89.0

W-97 .7 .0 1.6 .0 1.4 .0 .2 .0 1.0 1.4 60.6 8.9 69.5

S-97 1.2 .1 2.5 .2 1.9 .0 .7 .1 1.2 2.1 77.8 24.4 102.2

Average wet .7 .0 1.4 .1 1.3 .0 .3 .0 1.0 1.2 56.9 11.1 68.0

Overall average .4 .0 .8 .0 .8 .0 .2 .0 .7 .7 38.8 6.5 45.3
Seepage from Deadwood Aquifer 57

Boxelder Creek

Estimated streamflow recharge from Boxelder 

Creek to the Madison and Minnelusa hydrogeologic 

units averaged 12.8 and 2.1 ft3/s, respectively 

(table 12). Loss threshold estimates for Boxelder Creek 

were complicated by hydrogeologic features in the outcrop areas. Three springs are located along Boxelder 

Creek within the Madison outcrop: Gravel Spring, Doty 

Spring, and Dome Spring (pl. 1). Rahn and Gries 

(1973) determined from dye testing that these springs 

are directly connected to upstream losses. Although 

complicated by variable springflow, estimated thresholds reflect approximate net losses (Hortness and 

Driscoll, 1998), and therefore, these springflows were 

not included in streamflow-recharge or water-budget 

calculations. Hortness and Driscoll (1998) estimated 

general loss thresholds of greater than 25 ft3/s for the 

Madison outcrop, less than 20 ft3

/s for the Minnelusa 

outcrop, less than 5 ft3

/s for the Minnekahta outcrop, 

and a combined threshold for the three outcrops of 

approximately 50 ft3

/s. These estimates, however, did 

not consider the isolated Madison outcrop near the anticline along Boxelder Creek (pl. 1).

An important effect of the anticline is that it 

separates the Minnelusa recharge area to the west from 

Minnelusa aquifer to the east causing much of the 

recharge on the Minnelusa outcrop to enter the Madison 

aquifer. A hydrogeologic section through this area illustrates this point, showing that a large area of the Minnelusa hydrogeologic unit is mostly above the water 

table west of the anticline (fig. 22, section D-D′ ). 

Because the Minnelusa hydrogeologic unit in this area 

is largely in the unsaturated zone, there is little horizontal Darcian flow, and recharge to the Minnelusa 

outcrop can infiltrate vertically into the underlying 

Madison aquifer under the force of gravity. Considering 

these various hydrogeologic conditions, the estimated 

loss thresholds for the Madison and Minnelusa hydrogeologic units for this report are 30 and 16 ft3

/s, respectively, for a total of 46 ft3

/s (table 11).

Boxelder Creek has the third largest drainage 

area in the study area but accounted for the largest 

streamflow recharge to the Madison and Minnelusa 

hydrogeologic units, about 33 percent during the 

10-year period. This relates to the fact that Boxelder 

Creek is located in the northern part of the study area 

where precipitation is greater and the loss threshold is 

the largest for streams in the study area (table 11). Boxelder Creek flowed continually during the 10-year 

period but exceeded its estimated loss threshold to the 

Madison and Minnelusa hydrogeologic units only 

12 percent of the time. The continuous gage on Boxelder Creek above the loss zone (pl. 3, gage site 34) 

accounts for about 93 percent of the total basin area 

contributing to the loss zone. Therefore, the gaged 

flow was increased proportionately to account for the 

ungaged flow.

Elk Creek

Estimated streamflow recharge from Elk Creek 

to the Madison and Minnelusa hydrogeologic units 

averaged 2.6 and 0.9 ft3

/s, respectively (table 12). 

Measured flow in Elk Creek just upstream of the Madison outcrop (pl. 3, gage site 39) was used to calculate 

streamflow recharge. Because data for this site were 

not collected before September 1991, a synthetic flow 

record was generated for the missing period by 

regressing measured streamflow in Elk Creek against 

flow in Boxelder Creek at gage sites 39 and 34 (pl. 3). 

Because the Elk Creek loss zone is located at the 

northern boundary of the aquifer analysis area, only 

one-half of the streamflow recharge was assumed to 

flow into the aquifer analysis area.

Elk Creek flowed continually during the 

10-year period and exceeded its loss threshold 

11 percent of time. This basin generally receives 

greater precipitation than Boxelder Creek but is 

smaller in size and has a smaller loss threshold. Elk 

Creek accounted for about 8 percent of the total 

streamflow recharge to the Madison and Minnelusa 

hydrogeologic units.

Four tributaries downstream from gage site 39 

contribute to flow in the Elk Creek loss zone (pl. 3). 

The drainage basins for these tributaries are partially 

on the Madison outcrop. Because direct precipitation 

on the outcrop is accounted for in areal recharge, only 

the areas of the basins outside the outcrop were used 

to estimate additional streamflow below gage site 39. 

These basin areas outside the outcrop have a total area 

of 13.6 mi2

, which is 63.3 percent of the basin above 

gage site 39; thus, the flow record at the gage (partially synthetic) was increased by 63.3 percent. 

Results of streamflow measurements for several 

reaches of Elk Creek that were compiled by Hortness 

and Driscoll (1998) are presented in table 13 along 

with additional measurements made after August 20, 

1996. Loss thresholds of 11 ft3

/s for the Madison outcrop and 8 ft3

/s for the Minnelusa outcrop (table 11) 

were estimated by Hortness and Driscoll (1998) based 
58 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Table 13. Elk Creek streamflow-loss rates for the Madison and Minnelusa outcrops

[Modified from Hortness and Driscoll (1998). All values given in cubic feet per second. Site locations are shown on plate 3 and listed in table 11.

--, undetermined]

Date

Flow rate

at gage

site 39

Madison outcrop loss

rate between gage

sites 39 and 43

Madison outcrop loss

rate between gage

sites 43 and 44

Total Madison

outcrop loss rate

Minnelusa outcrop

loss rate (gage

sites 44 to 45)

04-24-96 31.9 6.8 3.3 10.1 7.9

05-07-96 26.6 6.5 4.8 11.3 8.1

07-01-96 12.1 7.6 -7.5 .1 6.4

07-12-96 9.9 8.1 -5.4 2.7 5.3

07-22-96 7.4 8.2 -5.1 3.1 4.8

08-20-96 4.7 7.0 -5.2 1.8 4.5

10-03-96 3.8 5.4 -3.0 2.4 --

10-21-99 15.2

1

Mean daily value.

-- -6.1 -- 4.2

on the first two measurement dates (April 24 and 

May 7, 1996). Subsequent measurements, which were 

made during particularly wet climatic conditions, indicated that the loss rate on the Minnelusa outcrop 

decreased only slightly, but the loss rate on the Madison 

outcrop decreased substantially because of streamflow 

gains in the reach between gage sites 43 and 44. Measured losses between gage sites 39 and 43 remained 

relatively stable.

Hortness and Driscoll (1998) attributed the 

streamflow gain that occurred between sites 43 and 44 

to springflow from the Madison aquifer and indicated 

that local areal recharge during a climatically wet 

period contributed to springflow. A laccolith, which is 

exposed on the northern side of the springflow area 

(Strobel and others, 1999), could cause areal recharge 

water to be perched on low-permeability igneous intrusive bodies. Water stored in perched areas might seep 

downgradient and discharge as springflow after periods 

of greater precipitation. Conversely, part of the springflow could result from reemerging upstream losses 

because of the larger streamflows during that period. 

Because streamflow losses and gains both can occur in 

the same stream reach at the same time, it is not known 

what effect springflow has on streamflow losses. The 

complex nature of this transient springflow precludes 

the determination of the ratio of areal-recharge source 

water to streamflow-recharge source water. Therefore, 

it was arbitrarily assumed that one-half of the estimated 

springflow resulted from areal recharge and one-half 

resulted from streamflow recharge, and those estimates 

were adjusted accordingly (also see “Areal Recharge” 

section). In addition, estimated springflow was added 

to streamflow that could potentially be lost to the 

Minnelusa outcrop. 

Based on streamflow gains (table 13) springflow 

was estimated as about 5 ft3

/s for the latter part of the 

summer-1996 period (S-96), 3 ft3/s for the winter-1997 

period (W-97), and 5 ft3

/s for the summer-1997 period 

(S-97). Because the earlier part of the 10-year period 

was climatically dryer, springflow was assumed not to 

have occurred prior to S-96. 

Ungaged Streams

 Ungaged streams include Deadman Gulch, 

Rockerville Gulch, Victoria Creek, the unnamed tributary, and Little Elk Creek (table 11 and pl. 3). These 

smaller basins accounted for about 8 percent (3.5 ft3

/s) 

of the total streamflow recharge to the Madison and 

Minnelusa hydrogeologic units (table 12). 

Synthetic flow records were generated for 

smaller ungaged basins by correlating flow rates in 

nearby larger gaged basins. An assumption was made 

that flow rates are directly correlated to the size of the 

basin. Streamflow in Rapid Creek was not used to generate synthetic flow records because streamflow is regulated by Pactola Dam. Streamflow in Battle Creek was 
Areal Recharge 59

used to create a synthetic flow record for Deadman 

Gulch and Rockerville Gulch (pl. 3). Streamflow in 

Spring Creek was used to create a synthetic flow record 

for Victoria Creek. Streamflow in Boxelder Creek was 

used to create a synthetic flow record for the unnamed 

tributary and for Little Elk Creek. Streamflow in Little 

Elk Creek was estimated based on Boxelder Creek 

rather than Elk Creek because precipitation for Little 

Elk Creek is similar to that of Boxelder Creek (table 11 

and pl. 3).

Loss thresholds for Victoria Creek and Little Elk 

Creek were determined by Hortness and Driscoll 

(1998) but were not determined for Deadman Gulch, 

Rockerville Gulch, and the unnamed tributary. Thresholds for these streams were assumed to be small compared to those of the larger streams and were estimated 

as 2 and 4 ft3/s for the Madison and Minnelusa outcrops, respectively. The Minnelusa outcrop thresholds 

were assumed to be larger than thresholds for the 

Madison outcrop because stream reaches crossing the 

Minnelusa outcrop are longer than those of the Madison 

outcrop. Although these loss-threshold estimates are 

very uncertain, error in the estimate has a small effect 

on total calculated streamflow recharge because these 

basins account for less than 1 percent of the total area 

contributing to loss zones in the study area.

Areal Recharge

Areal recharge is recharge resulting from infiltration of precipitation on outcrops. Methods used in estimating areal recharge are discussed in the following 

section, after which estimates are presented.

Methods

The Madison and Minnelusa outcrop areas were 

each divided into five areal recharge zones, bounded by 

major streams that cross the outcrops. These zones 

include Battle Creek to Spring Creek (zone 1), Spring 

Creek to Rapid Creek (zone 2), Rapid Creek to Boxelder Creek (zone 3), Boxelder Creek to Little Elk 

Creek (zone 4), and Little Elk Creek to Elk Creek 

(zone 5) (table 14 and pl. 3). Average annual precipitation for each zone (table 14) shows that the northern 

outcrop areas receive a greater amount of precipitation 

than do the southern areas. 

Evapotranspiration (ET) on the Precambrian core 

of the Black Hills could be estimated with greater 

confidence than in other areas of the Black Hills. This 

relates to an assumption that precipitation on the 

Precambrian core that does not evapotranspire infiltrates and reemerges as streamflow and can, therefore, 

be measured for a given basin. Therefore, streamflow 

yield on the Precambrian core was used as a surrogate 

to indirectly estimate recharge on the Madison and 

Minnelusa outcrops. Because of the high permeability 

of the Madison and Minnelusa outcrops, runoff from 

the outcrops is considered negligible (Carter, Driscoll, 

and Hamade, 2001) and therefore, recharge is 

assumed to be the difference between ET and precipitation. This method also assumes that ET on the 

Madison and Minnelusa outcrops is similar to that of 

the Precambrian core.

ET on the Precambrian core was estimated by 

correlating precipitation on drainage basins in the 

study area with basin yield. The estimated ET was 

then extrapolated to the Madison and Minnelusa outcrops areas. Because of the general decreased porosity 

with depth in these rocks (Rahn, 1985, p. 161), ground 

water probably does not infiltrate deeper than about 

500 ft; however, a small amount of ground water probably moves from the Precambrian core into the 

Madison hydrogeologic unit via upward seepage 

through the Deadwood aquifer. Therefore, the ultimate destination of precipitation falling on drainage 

basins in the Precambrian core can be divided into 

three categories: (1) evapotranspiration, (2) flow into 

streams either as shallow ground-water interflow or 

direct runoff, or (3) ground-water outflow into overlying Paleozoic rocks near the periphery of the Precambrian core. Therefore, the fraction of precipitation 

that is evapotranspired can be estimated from 

equation 5.

(5)

where the subscript PC represents the Precambrian 

core and,

ET = evapotranspiration;

P = precipitation on basin;

Y = streamflow yield from basin in Precambrian 

core; and

 GWO = ground-water outflow from Precambrian 

core.

ET

P

------    

PC

1

Y GWO +

P ----------------------    

PC

= –
60 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Table 14. Areal recharge zones and average annual precipitation on Madison and Minnelusa outcrops

[NA, not applicable]

Zone Area covered

Area

(square miles)

Average annual precipitation1

(inches)

1

Calculated from precipitation data for WY61-98 (Driscoll, Hamade, and Kenner, 2000).

Madison Minnelusa Madison Minnelusa

1 Battle Creek to Spring Creek 6.6 15.1 19.9 19.4

2 Spring Creek to Rapid Creek 4.6 7.1 19.1 18.6

3 Rapid Creek to Boxelder Creek 9.8 12.5 19.6 18.9

4 Boxelder Creek to Little Elk Creek 27.3 15.2 20.0 19.2

5 Little Elk Creek to Elk Creek 10.1 3.6 24.0 22.3

Total 58.4 53.5 NA NA

Because runoff is assumed to be zero on the Madison 

and Minnelusa outcrops, precipitation is equal to the 

sum of areal recharge and ET:

(6)

where the subscript MM represents the Madison and 

Minnelusa outcrops and R = areal recharge.

Based on assumptions described previously:

. (7)

Therefore, equations 5, 6 and 7 can be combined as:

(8)

where the quantity, Y + GWO, is the “total yield” from 

a drainage basin.

Four surface-water basins in the Precambrian 

core were analyzed to determine the terms on the right 

hand side of equation 8. These basins include Battle, 

Spring, Boxelder, and Elk Creeks measured above 

the Madison outcrop (table 11 and pl. 3). Although 

these basins mainly are composed of Precambrian 

rocks, small outcrop areas of Madison Limestone and 

Deadwood Formation exist near the western and 

eastern boundaries of some of the basins. 

Monthly precipitation data (Driscoll, Hamade, 

and Kenner, 2000) were used to interpolate digital grids 

describing the distribution of precipitation for the 

drainage basins. These grids were used to compile 

average precipitation for each 6-month period for each 

of the drainage basins. Daily streamflow data for all 

four basins was separated into summer and winter 

seasons and averaged into 6-month time intervals 

(October 1 to March 31 and April 1 to September 30). 

Ground-water outflow from the Precambrian core 

(GWO, eq. 5), which was estimated to be 6.3 ft3

/s (see 

“Seepage from Deadwood Aquifer” section), was proportioned according to basin area among all of the 

basins in the Precambrian core in the study area. The 

proportioned amount was then added to measured 

streamflow to compute total yield and divided by 

average precipitation for each of the four basins (eq. 6). 

Total yield versus precipitation was plotted, and separate curves were fitted through data for the winter and 

summer periods (fig. 29) using a least-squares method 

for nonlinear regression. The nonlinear regression produced a better fit (higher R2

 value) than linear regression, especially for the summer period. This relates to 

the fact that during intense precipitation events, ET 

consumes a smaller percentage of precipitation than for 

smaller precipitation events.

These fitted curves were used for estimating 

areal recharge to the Madison and Minnelusa outcrops 

for 6-month periods. Based on equation 8, areal 

recharge on the Madison and Minnelusa outcrops as a 

R ET +

P -----------------    

MM

= 1

ET

P

------    

MM

ET

P

------    

PC

=

R

P

---    

MM

Y GWO +

P ----------------------    

PC

=
Areal Recharge 61

function of precipitation was equated to total yield 

from basins in the Precambrian core. Precipitation for 

each areal recharge zone was calculated using the same 

method as for the Precambrian core and used to estimate areal recharge from the curves in figure 29. The 

winter curve shows that the colder months allow 

greater recharge for the same precipitation rate than the 

summer period. The summer curve shows substantially 

increasing total yield for precipitation exceeding 

18 inches per 6-month period. The curves are not valid 

for precipitation exceeding the range of data shown in 

figure 29.

Areal recharge for the summer periods ranged 

from less than 1 inch to more than 5 inches per 

6-month period with an average summer recharge 

of 2.3 inches (fig. 30). Areal recharge in the winter 

periods was less than 1 inch. The average areal 

recharge was 13 percent of precipitation. Areal 

recharge ranged from about 2 percent of precipitation 

in the summer of 1988 to about 26 percent in summer 

1995 (fig. 31).

In the study area, the Minnelusa hydrogeologic 

unit contains “unsaturated areas,” as previously 

defined (see “Concepts of the Ground-Water Flow 

System” section), across about 73 percent of the 

outcrop (pl. 2). Some of the precipitation infiltrating 

the unsaturated area of the Minnelusa outcrop probably 

infiltrates the underlying Madison aquifer. The same 

assumptions for the redistribution of streamflow 

recharge also were applied to areal recharge (table 15).

Estimation of Areal Recharge

Estimated areal recharge rates for each of the five 

areal recharge zones for the Madison and Minnelusa 

hydrogeologic units are shown in table 16. About 

64 percent of areal recharge occurred north of Boxelder 

Creek (zones 4 and 5) because of larger outcrop areas 

and greater precipitation amounts than the zones to the 

south. Average total areal recharge was about 

49 percent of streamflow recharge (table 7) for the 

study area. Total areal recharge rates in the summer 

ranged from less than 3 ft3

/s during dry years to almost 

100 ft3

/s during wet years. Areal recharge rates in the 

winter ranged from about 1 ft3/s during dry years to 

about 12 ft3/s during wet years. During the extremely 

wet summer-1995 period (S-95), areal recharge 

exceeded that of streamflow recharge (tables 12 

and 16).

Figure 29. Correlation of total yield to precipitation on basins in Precambrian core.

0

2

4

6

8

10

12

14

0 5 10 15 20 25 30

Winter season

Summer season

Summer curve fit, R2 = 0.57, y = (3.2*10-5) x3.9

Winter curve fit, R2 = 0.76, y = (8.8*10-3) x2.1

TOTAL YIELD, IN INCHES PER 6-MONTH PERIOD

PRECIPITATION, IN INCHES PER 6-MONTH PERIOD
62 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 30. Spatially averaged precipitation and estimated areal recharge per 6-month period for the Madison

and Minnelusa outcrops. INCHES

0

5

10

15

20

25

W-88 S-88 W-89 S-89 W-90 S-90W-91 S-91 W-92 S-92 W-93 S-93 W-94 S-94 W-95S-95 W-96S-96 W-97 S-97

Areal recharge

Precipitation

Figure 31. Spatially averaged areal recharge as a percentage of precipitation on the Madison and Minnelusa

outcrops for winter (W) and summer (S). RECHARGE, AS A PERCENT OF PRECIPITATION

W-88 S-88 W-89 S-89 W-90 S-90 W-91S-91 W-92 S-92 W-93S-93 W-94S-94 W-95S-95W-96 S-96 W-97 S-97

0

5

10

15

20

25

30
Areal Recharge 63

Table 15. Redistribution of average areal recharge from the unsaturated area of the Minnelusa outcrop to the Madison 

aquifer in inches per 6-month period, WY88-97

Zone1

1

Zones are described in table 14.

Recharge to 

Madison

outcrop

Recharge to 

Minnelusa

outcrop

Percentage of

Minnelusa

outcrop area

unsaturated

Percentage of

infiltration on

Minnelusa outcrop

redistributed

Adjusted

Madison 

recharge

Adjusted

Minnelusa

recharge

a b c d e f

d = c/2 e = a+b*d/100 f = b-b*d/100

1 1.2 0.9 59.4 29.7 1.5 0.7

2 1.0 .8 84.5 42.2 1.4 .5

3 1.4 1.1 70.0 35.0 1.8 .7

4 1.4 1.6 68.7 34.3 1.9 1.0

5 1.9 1.7 70.1 35.0 2.4 1.1

Table 16. Areal recharge rates to the Madison and Minnelusa hydrogeologic units by zones

[Recharge rates in cubic feet per second (ft3/s); W, winter; S, summer (W-88 = winter 1988); Mdsn, Madison, Mnls, Minnelusa]

Stress

period

Madison recharge by zone1

1

See table 14 for description of zones.

Minnelusa recharge by zone1 Total Total 

Mdsn 

Mnls Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Mdsn Mnls

Dry Period

W-88 0.0 0.0 0.1 0.3 0.5 0.0 0.0 0.0 0.1 0.1 0.9 0.2 1.1

S-88 .2 .1 .1 .6 .9 .2 .0 .1 .1 .1 1.9 .5 2.4

W-89 .1 .1 .3 .6 .5 .1 .0 .2 .2 .1 1.6 .6 2.2

S-89 .9 1.6 2.0 3.1 2.4 1.0 .8 1.0 .9 .3 10.0 4.0 14.0

W-90 .2 .1 .3 1.1 1.5 .2 .1 .2 .3 .2 3.2 1.0 4.2

S-90 2.3 .8 1.2 2.2 .9 2.2 .5 .6 .7 .1 7.4 4.1 11.5

W-91 .1 .1 .2 .6 .8 .1 .0 .1 .2 .1 1.8 .5 2.3

S-91 4.5 5.5 11.0 24.0 7.5 4.3 2.6 4.9 6.4 1.3 52.5 19.5 72.0

W-92 .3 .1 .3 .8 .9 .3 .1 .1 .2 .1 2.4 .8 3.2

S-92 .5 .4 .9 3.1 1.0 .6 .2 .4 .9 .2 5.9 2.3 8.2

W-93 .1 .1 .2 .7 1.1 .1 .0 .1 .2 .1 2.2 .5 2.7

Average dry .8 .8 1.5 3.4 1.6 .8 .4 .7 .9 .2 8.2 3.1 11.3

Wet Period

S-93 6.2 4.0 6.2 19.6 10.0 7.1 2.3 3.5 5.3 1.7 46.0 19.9 65.9

W-94 .1 .0 .2 .8 1.8 .0 .0 .1 .2 .2 2.9 .5 3.4

S-94 .4 .1 .3 .8 .4 .4 .1 .1 .3 .1 2.0 1.0 3.0

W-95 .3 .1 .6 2.4 3.1 .2 .0 .3 .6 .4 6.5 1.5 8.0

S-95 5.5 2.1 10.9 35.8 18.4 5.5 1.1 4.6 11.6 2.9 72.7 25.7 98.4

W-96 .2 .1 .5 2.2 2.8 .2 .1 .2 .5 .3 5.8 1.3 7.1

S-96 3.0 1.5 4.3 17.8 4.5 3.0 .9 2.1 4.4 1.1 31.1 11.5 42.6

W-97 .5 .4 1.3 4.8 2.6 .5 .2 .7 1.2 .6 9.6 3.2 12.8

S-97 3.1 1.8 10.6 35.0 5.8 3.3 1.1 5.9 11.6 1.4 56.3 23.3 79.6

Average wet 2.1 1.1 3.9 13.2 5.5 2.2 .6 1.9 4.0 1.0 25.9 9.8 35.7

Overall average 1.4 1.0 2.6 7.8 3.4 1.5 .5 1.3 2.3 .6 16.1 6.1 22.2
64 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Springflow

Springs in the aquifer analysis area that are 

included in water-budget calculations are JacksonCleghorn Springs, City Springs, Deadwood Avenue 

Springs, and springs along Boxelder and Elk Creeks 

(pl. 3). Geochemical analysis indicates that the largest 

spring complex in the aquifer analysis area, JacksonCleghorn, flows from the Madison aquifer (Back and 

others, 1983; Anderson and others, 1999). All of these 

springs are located in areas where hydraulic head in the 

Madison aquifer is generally higher than in the 

Minnelusa aquifer. Because of the upward hydraulic 

gradient, and for simplicity, it is assumed that the 

source of all springs considered is the Madison aquifer.

Flow from some springs can be relatively steady, 

whereas flow from others may fluctuate considerably. 

Topographic altitude, hydraulic head variation, and 

hydraulic properties of the overlying material may 

affect springflow rates. Flows from Tittle Springs, 

Gravel Spring, Doty Spring, and Dome Spring occur 

within the Madison streamflow-loss zones (pl. 1). 

Because estimated streamflow-loss thresholds represent approximate net loss (Hortness and Driscoll, 

1998), flow from these springs was accounted for in 

streamflow loss estimates and, therefore, was omitted 

from water-budget calculations. A summary of springflow estimates and details on individual springs follow.

Estimation of Springflow

Springs included in the water budget area are 

listed in table 17. A total of about 31 ft3

/s is the estimated average flow from these springs for WY88-97. 

Total springflow averaged 25.3 ft3

/s for the dry period 

and 37.4 ft3/s for the wet period.

Table 17. Summary of estimated springflow

[Discharge rates in cubic feet per second; W, winter; S, summer (W-88 = winter 1988)]

Stress period Jackson-Cleghorn

Springs

City

Springs

Deadwood Avenue

Springs

Boxelder

Springs

Elk

Springs Total

Dry Period

W-88 21.6 1.9 2.8 0.0 0.3 26.6

S-88 21.6 1.0 2.8 .0 .3 25.7

W-89 21.6 1.0 2.8 .0 .0 25.4

S-89 21.6 .7 2.8 .0 .0 25.1

W-90 21.6 .8 2.8 .0 .0 25.2

S-90 21.6 .8 2.8 .0 .0 25.2

W-91 21.6 .3 2.8 .0 .1 24.8

S-91 21.6 1.3 2.8 .0 .1 25.8

W-92 21.6 .6 2.8 .0 .0 25.0

S-92 21.6 .4 2.8 .0 .0 24.8

W-93 21.6 .3 2.8 .2 .1 25.0

Average dry 21.6 .8 2.8 .0 .1 25.3

Wet Period

S-93 21.6 2.1 2.8 .2 .1 26.8

W-94 21.6 1.5 2.8 .0 .4 26.3

S-94 21.6 1.4 2.8 .0 .4 26.2

W-95 21.6 1.3 2.8 .5 8.6 34.8

S-95 21.6 3.3 2.8 .5 8.6 36.8

W-96 21.6 2.8 2.8 2.5 8.2 37.9

S-96 21.6 4.0 2.8 2.5 8.2 39.1

W-97 21.6 3.5 2.8 6.8 18.9 53.6

S-97 21.6 4.9 2.8 6.8 18.9 55.0

Average wet 21.6 2.8 2.8 2.2 8.0 37.4

Overall average 21.6 1.7 2.8 1.0 3.7 30.8
Water Use 65

Jackson-Cleghorn Springs

Anderson and others (1999) estimated springflow from Jackson-Cleghorn Springs to be about 

21.6 ft3/s during WY88-89 using a control-volume 

analysis. This spring complex probably is a regional 

discharge point with a relatively stable flow (see 

“Hydraulic Response to Recharge” and “Flowpaths” 

sections). Therefore, in the absence of further data, the 

springflow was estimated to be constant at 21.6 ft3

/s for 

the 10-year period.

City Springs

Flow from City Springs and some unnamed 

springs about 0.3 mi to the east were estimated from the 

streamflow record at gage site 90 (table 11 and pl. 3), 

which is located about 2 mi downstream on a tributary 

of Rapid Creek. Base flow at this site was assumed to 

be equal to springflow and was estimated by using a 

hydrograph separation program called HYSEP (Sloto 

and Crouse, 1996). Estimated springflow for 6-month 

periods varied from 0.3 to 4.9 ft3

/s with an average of 

1.7 ft3/s.

Deadwood Avenue Springs

Flow from Deadwood Avenue Spring no. 1 was 

estimated from the streamflow record for gage site 91 

(pl. 3 and table 11), which is located about 1 mi downstream on a tributary of Rapid Creek. Gage site 91 was 

measured continuously during WY88-90. Base flow at 

this site was assumed to be equal to flow from spring 

no. 1 and was estimated by using the hydrograph separation program HYSEP (Sloto and Crouse, 1996). The 

estimated base flow was relatively steady with a mean 

of 2.4 ft3

/s, a maximum and minimum daily rate of 1.8 

and 3.3 ft3/s, respectively, and standard deviation of 

0.3. Because flow records were available only for a 

3-year period, the mean value of 2.4 ft3

/s was used in 

water-budget calculations for the entire 10-year period 

for spring no. 1.

On October 18, 2000, Deadwood Avenue 

Springs nos. 1 and 2 were measured at 2.22 and 

0.43 ft3

/s, respectively, at the locations where flow 

enters Rapid Creek. The fall of 2000 was very dry, and 

all flow in these streams was assumed to have originated from the springs. Because flow from spring no. 1 

on this date was nearly equal to the estimated average, 

it was assumed that the measured flow from spring 

no. 2 was also equal to the average rate for that spring. 

Therefore, total flow for the two springs was estimated 

to be constant at 2.8 ft3

/s.

Boxelder Springs and Elk Springs

Springs along Boxelder Creek 2 mi west of I-90 

and Elk Creek near I-90 (pl. 3) generally flow only 

when hydraulic head in the Madison aquifer is estimated to be above the land surface. Annual flow from 

these springs was estimated for WY87-97 by Carter, 

Driscoll, Hamade, and Jarrell (2001). These annual 

springflow estimates were included as 6-month time 

steps for this report by assuming flow remained 

constant during winter and summer for each year. 

Springflow was negligible during the early part of the 

analysis period until 1995 when flow increased 

rapidly due to rising water levels. The combined 

estimated flow from these springs during WY97 was 

about 26 ft3

/s.

Water Use

Locations of public supply, irrigation, and 

industrial wells are shown on plate 3. The city of 

Rapid City maintained water-use records that were 

used to compile data for water-budget calculations. 

Water use from public-supply wells outside of Rapid 

City was estimated by extrapolating per capita water 

use in Rapid City to populations served by other 

public water supplies. Irrigation and industrial water 

use was estimated based on water-permit information 

including pump capacities and acreage. A summary of 

water-use estimates follows, which is followed by separate descriptions of water use from Rapid City wells, 

other public-supply wells, irrigation, and industrial 

sources.

Estimation of Water Use

Rapid City withdrew an average of 3.8 ft3/s 

(2,500,000 gal/d) from the Madison aquifer and 

1.0 ft3/s (680,000 gal/d) from the Minnelusa aquifer 

during WY88-97 (table 18), which was about 

48 percent of all water use from the Madison and 

Minnelusa aquifers in the aquifer analysis area. In the 

1980’s, the city of Rapid City obtained much of its 

water from the Minnelusa aquifer. Madison aquifer 

production surpassed the Minnelusa aquifer production after 1991 as new city wells were completed. 

Other public-supply wells and domestic wells 

accounted for about 36 percent of all Madison and 

Minnelusa aquifer water use during WY88-97, while 

irrigation and industrial wells accounted for about 

16 percent. 
66 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Water use from the Madison and Minnelusa 

aquifers accounts for about 14 percent of the total water 

budget for WY88-97 (table 7). Total withdrawal rates 

from the Madison aquifer averaged 6.7 ft3/s and ranged 

from about 2 to 15 ft3

/s. Total withdrawal rates from 

the Minnelusa aquifer averaged 3.4 ft3/s and ranged 

from about 2 to 5 ft3/s (table 18). 

Rapid City Wells

Rapid City’s production wells (pl. 3) are completed primarily in the Madison aquifer (table 4). In 

response to drought conditions in the late 1980’s, the 

city initiated a drilling program in the Madison aquifer 

to reduce dependence on surface water and infiltration 

galleries along Rapid Creek (Anderson and others,

Table 18. Water use from Madison and Minnelusa aquifers

[Rates in cubic feet per second; W, winter; S, summer (W-88 = winter 1988)]

Stress period

Madison aquifer Minnelusa aquifer

Total

Madison 

Minnelusa

Rapid

City

Other

public and 

domestic 

water

supplies

Industrial 

and

irrigation

Total Rapid

City

Other

public and 

domestic 

water

supplies

Industrial

and

irrigation

Total

Dry Period

W-88 0.0 1.3 0.6 1.9 1.5 1.2 0.2 2.9 4.8

S-88 .0 3.4 1.3 4.7 1.4 3.1 1.2 5.7 10.4

W-89 .0 1.1 .6 1.7 .5 1.0 .2 1.7 3.4

S-89 .1 2.0 1.3 3.4 .7 1.8 1.2 3.7 7.1

W-90 .0 1.2 .6 1.8 1.6 1.1 .2 2.9 4.7

S-90 .9 2.0 1.3 4.2 1.9 1.8 1.2 4.9 9.1

W-91 1.0 1.4 .6 3.0 1.8 1.3 .2 3.3 6.3

S-91 3.3 2.2 1.7 7.2 1.6 2.0 1.0 4.6 11.8

W-92 3.6 1.2 .6 5.4 1.3 1.1 .2 2.6 8.0

S-92 9.1 2.1 1.3 12.5 1.2 1.9 1.2 4.3 16.8

W-93 1.7 1.4 .6 3.7 1.1 1.3 .2 2.6 6.3

Average dry 1.8 1.8 1.0 4.5 1.3 1.6 .6 3.6 8.1

Wet Period

S-93 10.6 1.9 1.1 13.6 1.1 1.8 1.1 4.0 17.6

W-94 4.2 1.4 .6 6.2 .6 1.3 .2 2.1 8.3

S-94 10.9 2.8 1.3 15.0 .3 2.6 1.2 4.1 19.1

W-95 3.7 1.4 .7 5.8 .8 1.3 .2 2.3 8.1

S-95 7.5 2.3 1.2 11.0 .6 2.1 1.0 3.7 14.7

W-96 .9 1.6 .7 3.2 .5 1.4 .2 2.1 5.3

S-96 7.6 2.6 1.2 11.4 .6 2.4 1.0 4.0 15.4

W-97 3.2 1.6 .7 5.5 .8 1.5 .2 2.5 8.0

S-97 8.4 2.3 1.2 11.9 .9 2.2 1.0 4.1 16.0

Average wet 6.3 2.0 1.0 9.3 .7 1.8 .7 3.2 12.5

Overall average 3.8 1.9 1.0 6.7 1.0 1.7 .7 3.4 10.1
Water Use 67

1999). Estimated water use for all Rapid City groundwater and surface-water sources is shown in table 19 

and averaged about 20 ft3/s during summer periods and 

12 ft3

/s during winter periods. Average production 

from the Madison and Minnelusa aquifers is shown in 

table 20 and sometimes accounted for more than onehalf of the total water use, with withdrawals from the 

Madison aquifer exceeding 10 ft3/s during S-93 and 

S-94. The average withdrawal after 1991, when most of 

the Madison wells were completed, was about 7 ft3/s. 

Table 19 shows total Rapid City water use as a fraction 

of the average for WY97 so that water use could be calculated for other public-supply wells based on Rapid 

City population equivalents in 1997.

Other Public-Supply Wells

The Madison and Minnelusa aquifers are used 

extensively as public water supplies outside of Rapid 

City. Most of these wells are located within a band 

about 2 to 3 mi wide, on or adjacent to the Minnelusa 

outcrop (pl. 3). These public water supplies predominately serve small suburban developments and commercial establishments (tables 21 and 22). 

To estimate the water use from public water 

supplies outside of Rapid City, per capita water use was 

assumed to be similar to that of Rapid City. Average 

withdrawal from each public-supply well was estimated based on the population served by that well and 

the per capita water use within Rapid City. This 

assumption would, however, overestimate water use 

from public supplies outside of Rapid City because per 

capita commercial water use inside of Rapid City is 

greater than that outside. However, this overestimation 

of water use from public water supplies was assumed to 

be offset by water use from private domestic wells 

outside of Rapid City, which was neglected.

The estimated per capita water use for Rapid City 

during the winter-1997 period (W-97) was 123 gal/d 

and the summer-1997 period (S-97) was 177 gal/d. 

These were calculated by dividing water use for Rapid 

City in WY97 (table 19) by the population equivalent 

of 73,000 in 1997 (South Dakota Department of 

Environment and Natural Resources, written commun., 

1999). Water use for each public water supply for 

WY97 was based on Rapid City population equivalents. Water use for each 6-month period was determined by multiplying by the water-use fraction of 

WY97 (table 19). Average water use for each public 

supply well for the 10-year period is shown in tables 21 

and 22. The average withdrawal rate from the Madison aquifer totaled about 1.9 ft3

/s and ranged from 

0.01 to 0.47 ft3

/s for individual water supplies. The 

average withdrawal rate from the Minnelusa aquifer 

totaled about 1.7 ft3

/s and ranged from 0.01 to 

0.20 ft3/s for individual water supplies.

Table 19. Total Rapid City water use as an average per 

stress period

[Includes all surface- and ground-water sources. Mgal/d, million

gallons per day; ft3/s, cubic feet per second; W, winter; S, summer

(W-88 = winter 1988)]

Stress

period

Total

water use

(Mgal/d)1

1

Rapid City Water Department, written commun, 1999.

Total

water use

(ft3/s)

Water use as

fraction of average

WY97 water use for

each season

Dry Period

W-88 6.94 10.74 0.77

S-88 18.79 29.07 1.46

W-89 6.03 9.33 .67

S-89 10.99 17.01 .85

W-90 6.67 10.32 .74

S-90 10.9 16.87 .85

W-91 7.59 11.74 .84

S-91 11.91 18.43 .92

W-92 6.8 10.52 .76

S-92 11.57 17.90 .90

W-93 7.79 12.05 .87

Wet Period

S-93 10.58 16.37 .82

W-94 7.90 12.22 .88

S-94 15.55 24.06 1.21

W-95 7.81 12.08 .87

S-95 12.81 19.82 .99

W-96 8.46 13.09 .94

S-96 14.19 21.96 1.10

W-97 8.99 13.91 1.00

S-97 12.89 19.95 1.00
68 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Table 20. Rapid City production well withdrawals

[Rate in cubic feet per second; Mdsn, Madison aquifer; Mnls, Minnelusa aquifer; W, winter; S, summer (W-88 = winter 1988). Source is Rapid City Water 

Department, written commun., 1999]

Stress 

period

Well name and the aquifer the well is completed in Total

RC-11

Mdsn

RC-11

Mnls

RC-32

Mnls

RC-4

Mnls

RC-5

Mdsn

RC-63

Mdsn

RC-8

Mdsn

RC-9

Mdsn

RC-10

Mdsn

RC-11

Mdsn Mdsn Mnls

Dry Period

W-88 0.00 0.00 0.59 0.94 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.53

S-88 .00 .00 .52 .90 .00 .00 .00 .00 .00 .00 .00 1.42

W-89 .00 .00 .52 .01 .00 .00 .00 .00 .00 .00 .00 .53

S-89 .07 .07 .48 .18 .00 .00 .00 .00 .00 .00 .07 .73

W-90 .00 .00 .60 1.03 .00 .00 .00 .00 .00 .00 .00 1.63

S-90 .21 .21 .69 .97 .71 .00 .00 .00 .00 .00 .92 1.87

W-91 .10 .10 .74 .96 .34 .52 .00 .00 .00 .00 .96 1.80

S-91 .32 .32 .30 .96 2.18 .48 .36 .00 .00 .00 3.34 1.58

W-92 .31 .31 .00 1.00 3.12 .00 .14 .00 1.35 .00 4.92 1.31

S-92 .31 .31 .00 .87 2.06 .64 .76 3.86 .26 .16 8.05 1.18

W-93 .31 .31 .00 .80 .00 .06 .18 .85 1.99 .05 3.44 1.11

Wet Period

S-93 .33 .33 .00 .79 .75 .81 1.21 5.22 1.62 .32 10.26 1.12

W-94 .32 .32 .00 .32 .18 .65 .71 .48 2.53 .19 5.06 .64

S-94 .31 .31 .00 .02 1.05 1.01 1.18 4.19 2.03 .65 10.42 .33

W-95 .08 .08 .00 .73 .56 .16 .10 .53 2.14 .24 3.81 .81

S-95 .00 .00 .00 .63 1.17 .59 1.11 2.07 .62 .39 5.95 .63

W-96 .00 .00 .00 .48 .09 .00 .00 .19 1.86 .00 2.14 .48

S-96 .00 .00 .00 .64 .94 .87 1.02 2.39 1.82 .51 7.55 .64

W-97 .00 .00 .00 .83 .38 .16 .04 .72 2.07 .06 3.43 .83

S-97 .00 .00 .00 .87 1.76 .47 .98 2.65 .00 .46 6.32 .87

Average .13 .13 .22 .70 .77 .32 .39 1.16 .91 .15 3.83 1.05

1Minnelusa and Madison aquifer withdrawals were each estimated as 0.4 times the total withdrawal because the well is open to the Minnelusa, Madison, and Deadwood aquifers. 2

Also may produce from Madison aquifer.

3Also may produce from Minnelusa aquifer.
Water Use 69

Table 21. Public water supply withdrawals from Madison aquifer excluding Rapid City wells

[gal/min, gallons per minute; ft3/s, cubic feet per second; WY, water year; Well information (excluding withdrawals) is from South Dakota Department of 

Environment and Natural Resources, written commun., 1999]

Site

number

(pl. 3)

Public water-supply

identification

number

Name Year of

construction

Population 

equivalent1

Average

estimated 

WY88-97 

withdrawal

(gal/min)

Average

estimated 

WY88-97 

withdrawal2

(ft3/s)

1 4602159 Stagebarn Subdivision 1993 165 18 0.04

2 4600893 Stagebarn Elementary School 1980 360 36 .08

3 4602000 Peaceful Pines 1976 102 9 .02

4 4600043a Black Hawk Water Company 1986 900 90 .20

5 4600862 Weston Heights 1985 220 22 .05

6 4602106 Cavalry Trails Homeowner Association 1980 54 4 .01

7 4602150 Coca Cola Bottling Company 1991 70 9 .02

8 4600046 Box Elder 1982 2,137 211 .47

9 4600863a Ponderosa Ridge 1974 45 4 .01

10 4600863 Ponderosa Ridge 1977 45 4 .01

11 4600253 Westberry Trails Water Users Association 1972 157 13 .03

12 4602084 Rimrock Ridge Water Association 1978 36 4 .01

13 4600264 Chapel Lane Water Company 1975 1,200 117 .26

14 4600265 Carriage Hills 1980 270 27 .06

15 4600274 Rapid Valley Sanitary District 1991 1,360 94 .21

16 4600405 Ponderosa Park 1950 54 4 .01

17 4602149 CPH - Countryside South 1972 35 4 .01

18 4600263a CPH - Whispering Pines 1964 35 4 .01

19 4600263 CPH - Whispering Pines 1976 35 4 .01

20 4600050 Highland Hills 1986 40 4 .01

21 4600015 Spring Canyon Water Company 1968 42 4 .01

22 4600528 Bear Country 1975 304 31 .07

23 4600910a Hart Ranch 1984 600 58 .13

24 4600910 Hart Ranch 1984 20 45 .10

25 4600948 Pine Grove 1983 270 27 .06 

Total 8,556 847 1.90

1

When the reported population for a public water supply included more than one well location, the population was prorated based on estimates from 

water managers or the well capacity. 2

Average withdrawals less than 0.01 ft3/s were rounded up to 0.01 ft3/s for several smaller public water supplies.
70 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Table 22. Public water supply withdrawals from Minnelusa aquifer excluding Rapid City wells

[gal/min, gallons per minute; ft3/s, cubic feet per second; WY, water year. Well information (excluding withdrawals) is from South Dakota Department of 

Environment and Natural Resources, written commun., 1999]

Site

number

(pl. 3)

Public

water-supply

identification

number

Name Year of

construction

Population 

equivalent1

Average 

WY88-97

withdrawal

(gal/min)

Average 

WY88-97

withdrawal2

(ft3/s)

26 4600929 Elk Creek Steakhouse 1978 104 8 0.02

27 4600630 Elk Creek Resort 1994 60 5 .01

28 4602133 Covered Wagon Resort -- 390 40 .09

29 4602123 Dakotah Spirit Resort -- 100 8 .02

30 4600239 Elk Creek Water Company 1973 321 31 .07

31 4600421a Wonderland Homes 1982 325 31 .07

32 4600639 Piedmont Medical Center 1976 75 8 .02

33 4600421 Wonderland Homes 1975 325 31 .07

34 4601000a East Ridge Acres 1972 55 5 .01

35 4600402 The Niche 1974 50 5 .01

36 4600515 Midland Heights 1975 177 17 .04

37 4601000 East Ridge Acres 1978 55 5 .01

38 4600041a Pine Hills Park 1984 150 13 .03

39 4600041 Pine Hills Park 1972 155 13 .03

40 4600516 Golden Meadows 1978 114 8 .02

41 4602165 Fort Welikit Family Campground 1994 27 4 .01

42 4600587 Heritage Park 1963 188 17 .04

43 4600042 Woodland Hills 1945 110 8 .02

44 4600043 Black Hawk Water Company 1982 885 85 .19

45 4600040 Valley View Mobile Home Park 1973 291 26 .06

46 4600257 Cimarron Park 1972 200 17 .04

47 4600514 Northdale Sanitary District 1978 489 49 .11

48 4600258 Leos Trailer Court 1990 25 4 .01

49 4602122 B & J Mobile Home Park 1994 156 5 .01

50 4600260 Ponderosa Mobile Home Ranch 1963 100 8 .02

51 4600269 Hidden Valley Water Association Inc. 1954 50 5 .01

52 4602039 Buck N Gator Bar 1960 100 8 .02

53 4602070 Dacotah Cement - North 1941 35 4 .01

54 4600643 Dacotah Cement - East/west 1923 75 8 .02

55 4600643a Dacotah Cement - East/west 1934 75 8 .02

56 4600253a Westberry Trails Water Users Association 1974 20 4 .01

57 4602182 Sioux San Hospital 1960 200 17 .04

58 4601062 Cedar Canyon Weslyan Camp 1956 93 8 .02

59 4600908 Lake Park Motel 1976 80 8 .02

60 4602134 Ponderosa Water Company 1985 38 4 .01

61 4602153 Pineview Water Association 1984 34 4 .01

62 4601115 Memorial Christian School 1976 177 17 .04

63 4600589 Travelodge 1992 175 8 .02
Leakage to Overlying Aquifers 71

64 4601037 Rushmore Waterslide 1984 500 49 0.11

65 4600890 Reptile Gardens Inc. 1965 900 89 .20

66 4601061 Flying T Chuckwagon Suppers 1993 204 17 .04

67 4602118 Dairy Barn - Hayloft B&b 1994 42 5 .01

68 4600669 Happy Holiday Inc. 1965 67 5 .01

Total 7,792 719 1.65

1

When the reported population for a public water supply included more than one well location, the population was prorated based on estimates from 

water managers or the well capacity. 2

Average withdrawals less than 0.01 ft3/s were rounded up to 0.01 ft3/s for several smaller public water supplies.

Table 22. Public water supply withdrawals from Minnelusa aquifer excluding Rapid City wells–Continued

[gal/min, gallons per minute; ft3/s, cubic feet per second; WY, water year. Well information (excluding withdrawals) is from South Dakota Department of 

Environment and Natural Resources, written commun., 1999]

Site

number

(pl. 3)

Public

water-supply

identification

number

Name Year of

construction

Population 

equivalent1

Average 

WY88-97

withdrawal

(gal/min)

Average 

WY88-97

withdrawal2

(ft3/s)

Irrigation and Industrial Water Use

Irrigation and industrial withdrawals from the 

Madison and Minnelusa aquifers were estimated from 

water-rights permit information (South Dakota Department of Environment and Natural Resources, written 

commun., 1999) including well capacity and acreage. 

Average withdrawal rates totaled about 0.95 ft3

/s from 

the Madison aquifer (table 23) and ranged from 0.03 to 

0.55 ft3

/s for individual wells. Average withdrawal 

rates totaled 0.65 ft3

/s from the Minnelusa aquifer 

(table 24) and ranged from 0.04 to 0.2 ft3

/s for individual wells.

Leakage to Overlying Aquifers

Water from the Minnelusa aquifer under artesian 

pressure probably moves into overlying units including 

the Minnekahta and Inyan Kara aquifers through fractures or breccia pipes. According to Davis and others 

(1961), the Inyan Kara aquifer probably receives some 

recharge from underlying aquifers because recharge on 

its outcrop is relatively small. Gott and others (1974) 

suggest that the upward leakage occurs through breccia 

pipes. Behal (1988) applied statistical analysis to water 

quality in the Inyan Kara aquifer, in which t-tests 

Table 23. Industrial and irrigation withdrawals from 

Madison aquifer

[gal/min, gallons per minute; ft3/s, cubic feet per second; WY, water year]

Site

number

(pl. 3)

Water-rights

permit

number1

1

Well information compiled from South Dakota Department of Environment and Natural Resources, written commun., 1999.

Year of

construction

Average 

WY88-97 

withdrawal1

(gal/min)

Average

WY88-97

withdrawal

(ft3/s)

69 2286-2 1993 31 0.07

70 2256-2 1992 76 .17

71 2313-2 1994 13 .03

72 454-2 1957 246 .55

73 1911-2 1984 58 .13

Total 424 .95

Table 24. Industrial and irrigation withdrawals from 

Minnelusa aquifer

[gal/min, gallons per minute; ft3/s, cubic feet per second; WY, water year]

Site

number

(pl. 3)

Water-rights

permit

number1

1Well information compiled from South Dakota Department of 

Environment and Natural Resources, written commun., 1999.

Year of

construction

Average 

WY88-97 

withdrawal1

(gal/min)

Average 

WY88-97 

withdrawal

(ft3/s)

74 842-1 1968 35 0.08

75 1656-2 1954 89 .20

76 1798-2 1956 22 .05

77 815-2 1923 89 .20

78 2137-2 1990 35 .08

79 1901-2 1984 17 .04

Total 287 .65
72 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

indicated water near lineaments was different from 

water away from lineaments for some constituents but 

not others. This statistical analysis also indicated that 

water near lineaments was geochemically similar to a 

mixture of Madison and Minnelusa aquifer water for 

some constituents but not others. Although these 

results were not conclusive, the analysis indicated a 

strong possibility that ground water leaks upward from 

the Madison and Minnelusa aquifers through fractures 

or breccia pipes.

Because very little data were available to estimate the upward leakage from the Minnelusa aquifer, 

the overall water-budget calculation was used to estimate this amount to be about 2 ft3/s or about 3 percent 

of the total budget (table 7).

Regional Outflow

Regional outflow occurs from the Madison and 

Minnelusa aquifers across the eastern boundary of the 

aquifer analysis area and was calculated by Darcy’s 

Law using the hydraulic gradient from plates 1 and 2 

and estimated transmissivity (T). T along the eastern 

boundary was adjusted in balancing the water budgets. 

The eastern boundary was subdivided into 14 zones 

(pl. 3), and outflow from each zone was calculated 

separately (table 25). The values listed in table 25 are 

within the ranges of effective T shown in figures 9 

and 10 and represent the T tensor perpendicular to the 

boundary. The northern and southern boundaries were 

assumed to be parallel to flow and, therefore, would 

have no flow across them. Outflow from the confining 

units was assumed to be negligible.

Hydraulic gradient along the eastern boundary 

was assumed to remain relatively constant; hence, estimated regional outflow also was constant throughout 

the 10-year period. Regional outflow was estimated to 

be about 11 ft3/s for both the Madison and Minnelusa 

hydrogeologic units (table 25).

Table 25. Outflow from boundary zones

[Boundary zones shown on plate 3. ft, feet; ft2/d, square feet per day; ft3/s, cubic feet per second; T, transmissivity]

Boundary

zone

Boundary

width

(ft)

Madison aquifer Minnelusa aquifer

Hydraulic

gradient

T

(ft2/d)

Outflow

(ft3/s)

Hydraulic

gradient

T

(ft2/d)

Outflow

(ft3/s)

1 14,492 0.004 664 0.4 0.006 600 0.6

2 14,492 .006 664 .7 .007 600 .7

3 14,492 .005 664 .6 .009 600 .9

4 14,492 .003 664 .3 .012 600 1.2

5 14,492 .001 1,005 .2 .010 600 1.0

6 14,492 .000 3,096 .0 .012 600 1.2

7 14,217 .005 3,310 2.7 .008 600 .8

8 14,217 .004 1,009 .7 .009 600 .9

9 14,217 .007 664 .8 .008 600 .8

10 14,217 .011 664 1.2 .007 600 .7

11 14,217 .010 664 1.1 .007 600 .7

12 14,217 .007 664 .8 .007 600 .7

13 14,217 .007 664 .8 .007 600 .7

14 14,217 .006 664 .7 .003 600 .3

Total outflow across eastern boundary 11.0 11.2
Summary 73

SUMMARY

The Madison and Minnelusa aquifers are important sources of water for Rapid City and surrounding 

communities. To provide information for effective 

management of these important aquifers, a conceptual 

model of ground-water flow was developed. The 

western part of the study area includes drainage areas 

that contribute streamflow recharge to the Madison and 

Minnelusa aquifers. The eastern part of the study area 

is referred to as the aquifer analysis area and includes 

the part of the study area where the Madison and the 

Minnelusa aquifers exist.

In the study area, the Madison and Minnelusa 

hydrogeologic units outcrop on the eastern flank of the 

Black Hills and dip easterly. Recharge to the Madison 

and Minnelusa hydrogeologic units is from streamflow 

losses and areal recharge on outcrop areas. The Madison hydrogeologic unit includes the karstic Madison 

aquifer, which is the upper, more permeable 100 to 

200 ft of the Madison Limestone, and the Madison confining unit, which consists of the lower, less permeable 

part of the Madison Limestone and the Englewood 

Formation. Reported well yields are as high as 

2,500 gal/min. Overlying the Madison hydrogeologic 

unit is the Minnelusa hydrogeologic unit. This unit 

includes the Minnelusa aquifer, which is the upper, 

more permeable 200 to 300 ft of the Minnelusa Formation, and the Minnelusa confining unit, which consists 

of the lower, less permeable part. Reported well yields 

are as high as 700 gal/min. 

Important concepts described in the conceptual 

model include streamflow recharge, areal recharge, 

ground-water flow, storage, unsaturated areas west of 

the unconfined areas, leakage between aquifers, springflow, and regional outflow.

Hydraulic properties described for the hydrogeologic units include transmissivity, vertical hydraulic 

conductivity, storage coefficient, and specific yield. 

Estimates of effective transmissivity for the Madison 

aquifer range from 500 to 20,000 ft2

/d with the highest 

values in the Jackson-Cleghorn Springs area and the 

lowest values in the northeastern and southeastern parts 

of the aquifer analysis area. Generalized estimated 

transmissivity distributions for the Minnelusa aquifer 

ranged from 500 to 10,000 ft2

/d with the highest values 

in the Jackson-Cleghorn Springs area and the lowest 

values in the eastern part of the aquifer analysis area. 

Anisotropic transmissivity in the Madison aquifer may 

be localized in orientation and has been documented to 

have tensor ratios as high as 45:1. Vertical hydraulic 

conductivities for the Minnelusa confining unit determined from aquifer tests in the Rapid City area range 

from 1.3x10-3 to 3.0x10-1 ft/d. Leakage between the 

Madison and Minnelusa aquifers is spatially variable, 

which is consistent with the large range of vertical 

hydraulic conductivity. The confined storage coefficient for the Madison and Minnelusa hydrogeologic 

units was estimated as 3x10-4. Specific yield was estimated as 0.09 for the Madison and Minnelusa aquifers 

and 0.03 for the Madison and Minnelusa confining 

units.

Potentiometric surfaces for the Madison and 

Minnelusa aquifers interpreted from hydraulic head in 

wells show a general easterly gradient with many local 

variations and changes in slope. The hydraulic gradient was estimated to be about 70 ft/mi on average for 

both aquifers. Temporal hydraulic-head change during 

WY88-97 ranged from about 5 to 95 ft in continuousrecord observation wells. Temporal hydraulic-head 

change is small in the Jackson-Cleghorn Springs area 

and increases with distance from the springs. Confined and unconfined areas are identified based on the 

structural tops of formations and the potentiometric 

surface. The location where the average potentiometric surfaces contact the top and bottom of the aquifers and the confining units determine the boundaries 

of unconfined zones. The areas of Madison and Minnelusa hydrogeologic units unconfined zones are 

about 53 and 36 mi2, respectively. Although the 

unconfined area represents a small part of the entire 

aquifer analysis area (629 mi2), change in storage in 

the unconfined area is orders of magnitude larger than 

that of the confined area. 

Dye-tracer tests, stable isotopes, and hydrogeologic features were analyzed conjunctively to estimate 

generalized ground-water flowpaths in the Madison 

aquifer and to analyze their influence on the Minnelusa aquifer. Streamflow losses to the Madison 

hydrogeologic unit from Boxelder Creek generally 

flow southward from the loss zone along structural 

features before flowing eastward. Rapid Creek 

streamflow loss generally flows north from its loss 

zone before moving towards Jackson-Cleghorn 

Springs or toward the east. Most of the streamflow 

loss from Spring Creek moves north towards JacksonCleghorn Springs. The western Rapid City area 

between Boxelder Creek and Spring Creek is 

described as a high-flow area and is characterized as 

having undergone extensive tectonic activity, greater 

brecciation in the Minnelusa Formation, high transmissivities, generally upward hydraulic gradients 
74 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

from the Madison to Minnelusa aquifer, many karst 

springs, and converging flowpaths.

 Water-budget analysis of the Madison and 

Minnelusa hydrogeologic units for WY88-97 was 

divided into 6-month stress periods representing winter 

and summer seasons. WY88-97 included periods of 

both low and high recharge rates and were representative of the range of hydrologic conditions during the 

last 30 years. Three budgets were developed for the 

water-budget analysis: (1) a dry-period budget for 

declining water levels, October 1987 through March 

1993; (2) a wet-period budget for rising water levels, 

April 1993 through September 1997; and (3) a full 

10-year period budget. By simultaneously balancing 

these three water budgets, initial estimates of recharge, 

discharge, change in storage, and related properties 

were refined. Compiled water-budget flow components 

include streamflow recharge, areal recharge, seepage 

from Deadwood aquifer, water use, outflow to overlying units, regional outflow, springflow, and change in 

ground-water storage. 

Total streamflow recharge increased from about 

27 ft3/s during the dry period to 68 ft3

/s during the wet 

period and accounted for 45 ft3

/s or 61 percent of the 

total budget for the10-year period. Streamflow 

recharge to the Minnelusa hydrogeologic unit was only 

14 percent of the total streamflow recharge. Total areal 

recharge for the dry and wet periods was 11 and 

36 ft3/s, respectively, and 22 ft3/s or 30 percent of the 

10-year budget.

 Average springflow for the dry and wet periods 

was 25 and 37 ft3

/s, respectively, and accounted for 

31 ft3

/s or 42 percent of the 10-year budget. Water use 

increased from about 8 ft3/s during the dry period to 

13 ft3/s during the wet period with a slight decrease in 

Minnelusa aquifer withdrawals and an increase in 

Madison aquifer withdrawals resulting from newly 

completed wells. Water use accounted for 10 ft3

/s or 

14 percent of the 10-year budget. Regional groundwater outflow was 22 ft3

/s or 30 percent of the 10-year 

budget. Leakage to hydrogeologic units overlying the 

Minnelusa aquifer was about 2 ft3/s for the 10-year 

budget. Average net leakage from the Madison hydrogeologic unit to the Minnelusa hydrogeologic unit was 

8 ft3/s.

Ground-water storage was initially estimated 

from changes in hydraulic head in confined and unconfined areas, specific yields, and storage coefficients. 

These properties were refined based on water-budget 

balances. Total storage decreased by about 8 ft3/s for 

the dry period and increased 21 ft3

/s for the wet period 

with a net increase in storage for the 10-year period of 

5.0 ft3/s.

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APPENDICES
80 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

APPENDIX A: AQUIFER TEST AT RC-9 

An aquifer test of the Madison aquifer was conducted in October 1995 by pumping well RC-9 and 

measuring drawdown in wells CHLN-2, RC-11, CL-2, 

and SP-2 (fig. 9). Industrial and municipal withdrawals 

from the Madison aquifer were discontinued in the 

area 9 days before the aquifer test began, during the 

pumping period, and for 6 days after pumping. The 

pumping rate from RC-9 was about 2,550 gal/min. A 

schematic diagram of RC-9 is shown in figure 32, and 

conceptual illustration of the aquifer test is shown in 

figure 33. Hydraulic-head trends were measured for 

5 days prior to the test. Based on this trend and the level 

of recovery after a period equivalent to that of pumping 

(6 days), a hydraulic-head trend was estimated for the 

pumping and recovery period (fig. 34). The estimated 

trend line reflects the fact that full recovery does not 

take place after a period equivalent to that of pumping 

(Driscoll, 1986, p. 252-253). Drawdown was calculated as the difference between this trend line and the 

measured hydraulic head (fig. 35). The trend line was 

checked by extrapolating the drawdown curve that 

would occur if pumping had continued through the 

recovery period. The extrapolated drawdown curve was 

calculated by requiring that L1 = L2 for every ∆t value 

(fig. 35) (Ferris and others, 1962, p. 100-102). If the 

extrapolated drawdown curve appeared reasonable, the 

trend line was assumed to be a good estimate. 

Before any analysis of data, all measurements 

were corrected for fluctuations induced by changes in 

barometric pressure (Ferris and others, 1962; 

Kruseman and de Ridder, 1991). Prior to the aquifer 

test, the relationship between barometric pressure and 

hydraulic head in each observation well was established. This relationship was used to correct the data so 

that it represents drawdown under conditions of constant barometric pressure. Measured drawdown corrected for trend and barometric effects is listed in 

table 27 at the end of this section.

The drawdown portion of the curves was analyzed using the method of Hantush (1960) for estimating aquifer properties in a leaky confined aquifer. 

The method assumes there is storage in the intervening 

confining unit(s). The analysis computes T, S, and β, 

which is given by the following equation:

(9)

where

β = a dimensionless “lumped” parameter;

r = distance from the pumped well to the observation well [L];

T = transmissivity of the pumped aquifer [L2/T];

 Kv′ = vertical hydraulic conductivity of the overlying confining unit [L/T];

Kv′′ = vertical hydraulic conductivity of the underlying confining unit [L/T];

S = storage coefficient of the pumped aquifer 

[dimensionless];

S′ = storage coefficient of the overlying confining 

unit [dimensionless];

S′′ = storage coefficient of the underlying confining unit [dimensionless];

b′ = thickness of the overlying confining unit [L]; 

and

b′′ = thickness of the underlying confining unit 

[L].

β r

4

-- Kv′ S′

b′ TS ---------------- Kv′ ′ S′ ′b′ ′ TS = + -----------------------

Figure 32. Schematic showing construction details of Rapid City well no. 9 (RC-9,

site 49, table 28, plate 1) completed in the

Madison aquifer.

ALLUVIUM

SPEARFISH

FORMATION

MINNEKAHTA

LIMESTONE

OPECHE

SHALE

MINNELUSA

FORMATION

MADISON

LIMESTONE

Land surface

Altitude 3,330 feet above

 sea level

Measuring point 4.2 feet above

 land surface

30-inch diameter borehole

20-inch diameter steel casing

17.5-inch diameter borehole

13.6-inch diameter steel casing

12.3-inch diameter

open borehole

55 ft

1,008 ft 960 ft

400 ft

260 ft

220 ft

34 ft

1,051 ft

GROUT

EXPLANATION

NOT TO SCALE
Appendix A 81

Figure 33. Diagram showing aquifer test conceptual model for multiple aquifer system.

Deadwood aquifer (constant hydraulic head)

Madison confining unit

(vertical flow)

Madison aquifer

(2-dimensional radial flow)

Minnelusa confining unit

(vertical flow)

Minnelusa aquifer

(constant hydraulic head)

Impermeable boundary

Casing

Open

hole

Casing

Open

hole

Kv' S' b'

Kv" S" b"

T S

Pumped well

RC-9 Observation

well

Not to scale

Q

Figure 34. Aquifer test well hydrograph for CL-2 (site 50, table 28, plate 1). The trend line is the estimated

water level that would have occurred without pumping.

MONTH/DAY (1995)

SEP

29 

OCT

1

OCT

3

OCT

5

OCT

7

OCT

9

OCT

11

OCT

13

OCT

15

OCT

17

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

3,415.5

3,416.0

3,416.5

3,417.0

3,417.5

3,418.0

3,418.5

3,419.0

Measured 

Estimated trend
82 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Aquifer properties were estimated using a nonlinear least squares parameter estimation technique to 

achieve a best fit of the drawdown data (fig. 36). 

Although this curve fitting method allows upper and 

lower limits to be placed on parameter values to be estimated, estimates were all within reasonable ranges 

without any constraints imposed. Table 26 shows the 

properties estimated by the Hantush (1960) method. Kv

for the Minnelusa confining unit was computed using 

equation 9 by assuming that S′ for the Minnelusa confining unit is 10-4 and b′ is 300 ft. It was also assumed 

that Kv for the Minnelusa confining unit was at least 

one order of magnitude greater than that of the Madison 

confining unit, which makes the second term in 

equation 9 negligible. Because of this, no values of Kv

or S for the Madison confining unit are reported. 

Except for RC-11, the pumped well and observation wells do not fully penetrate the aquifer. The flow 

pattern to partially penetrating wells is different from 

fully penetrating wells. However, these effects are 

negligible when the distance from pumped well to 

observation well is larger than twice the saturated 

aquifer thickness (Todd, 1980, p. 149-150). This was 

confirmed because the aquifer test analysis produced 

the same results with and without applying corrections 

for partial penetration. 

Interference in the aquifer test occurred in well 

SP-2 when well BHPL (fig. 9) began pumping about 

2 days into the test. The increased drawdown in SP-2 

was estimated and corrected for by applying the 

method of Hantush and Jacob (1955) to the variable 

pumping rate of BHPL. This method was used because 

it was applied in a previous investigation whereby well 

RC-5 was pumped and drawdown measured in SP-2 

(Greene, 1993). That aquifer test was interpreted as 

indicating the presence of anisotropic transmissivity. 

Because these three wells are nearly in a line, it was 

assumed that the directional T and other aquifer properties between RC-5 and SP-2 were similar to that 

between BHPL and SP-2. Therefore, by applying the 

same analytical model as in Greene (1993) and using 

the same properties, the drawdown at SP-2 resulting 

only from pumping at BHPL could be estimated 

because of the principle of superposition (Reilly and 

others, 1987). This drawdown was then subtracted 

from the total drawdown to obtain the drawdown 

resulting from withdrawal at RC-9.

Figure 35. Drawdown and recovery curves for CL-2 (site 50, table 28 and plate 1). Curve shows drawdown if pumping had continued. For the extrapolated drawdown, L2 = L1 for every ∆t.

MONTH/DAY (1995)

DRAWDOWN OR RECOVERY, IN FEET ABOVE SEA LEVEL

OCT

4

OCT

5

OCT

6

OCT

7

OCT

8

OCT

9

OCT

10

OCT

11

OCT

12

OCT

13

OCT

14

OCT

15

OCT

16

OCT

17

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Drawdown and recovery

Extrapolated drawdown

 if pumping had continued 

L1

L2

∆t

∆t
Appendix A 83

Table 26. Aquifer properties for the Madison aquifer estimated by the Hantush (1960) method

[ft, feet; ft2/d, feet squared per day; ft/d, feet per day; r, distance from pumped well; T, transmissivity; S, storage coefficient;

β, lumped parameter; Kv, vertical hydraulic conductivity]

Observation well

and site number

(pl. 1)

r

(ft)

T

(ft2/d)

S

(dimensionless)

β

(dimensionless)

Kv of Minnelusa

confining unit

(ft/d)

CL-2 (50) 6,290 14,700 2.1x10-5 2.1 1.7

RC-11 (62) 8,603 11,500 2.7x10-4 1.2 2.7

CHLN-2 (56) 7,562 14,100 1.4x10-5 2.3 .9

SP-2 (46) 4,564 13,900 6.8x10-5 .36 .3

Figure 36. Drawdown curves and curve fit for the Hantush (1960) method for RC-9 aquifer test,

October 1995.

ELAPSED TIME, IN MINUTES FROM THE START OF PUMPING

1 10 100 1,000 10,000

DRAWDOWN, IN FEET

0.01

0.1

1

10

CHLN-2 (site 56)

r = 7,562

Pumping rate = 2,550 gallons

 per minute

r = distance from pumping

 well, in feet

RC-9

CHLN-2 Type curve

CL-2 (site 50)

r = 6,290

CL-2 type curve 

RC-11 (site 62)

r = 8,603

RC-11 Type curve

SP-2 (site 46)

r = 4,564

SP-2 type curve 

Site number refers to table 28 and

plate 1
84 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Table 27. Drawdown data for the RC-9 aquifer test

Observation well CHLN-2

(site 56)

Observation well CL-2

(site 50)

Observation well RC-11

(site 62)

Observation well SP-2

(site 46)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

5 0.01 5 0.02 375 0.01 15 0.04

15 .03 15 .04 385 .03 25 .16

25 .05 25 .07 395 .04 35 .28

35 .08 35 .11 405 .05 45 .36

45 .11 45 .11 415 .07 55 .45

55 .12 55 .14 445 .07 65 .62

65 .14 65 .18 485 .08 75 .74

75 .17 75 .21 535 .08 85 .79

85 .19 85 .21 595 .10 95 .89

95 .22 95 .21 665 .12 105 .99

105 .24 105 .23 745 .14 115 1.04

115 .26 115 .25 835 .15 125 1.14

125 .27 125 .27 935 .15 135 1.21

135 .27 135 .30 1,045 .19 145 1.30

145 .29 145 .30 1,165 .22 175 1.48

155 .31 155 .35 1,295 .28 215 1.71

165 .33 165 .35 1,435 .29 265 1.92

175 .34 175 .37 1,575 .31 325 2.16

185 .36 205 .42 1,725 .33 395 2.48

195 .38 245 .46 1,895 .37 475 2.77

225 .43 295 .53 2,065 .42 565 3.01

255 .46 355 .59 2,245 .45 665 3.26

295 .51 425 .69 2,425 .48 775 3.44

345 .56 505 .81 2,625 .53 895 3.55

405 .65 595 .90 2,825 .59 1,025 3.71

465 .72 695 .97 3,035 .61 1,165 3.99

535 .79 805 1.07 3,255 .67 1,305 4.17

615 .87 925 1.16 3,475 .72 1,455 4.31

695 .94 1,055 1.24 3,715 .76 1,625 4.33

785 1.02 1,195 1.32 3,955 .79 1,795 4.37

875 1.07 1,335 1.40 4,215 .85 1,085 3.85

975 1.14 1,485 1.49 4,465 .89 1,225 4.08

1,085 1.21 1,655 1.55 4,735 .92 1,365 4.28
Appendix A 85

1,195 1.27 1,825 1.61 5,005 0.97 1,515 4.31

1,315 1.36 2,005 1.70 5,275 .98 1,685 4.37

1,435 1.43 2,185 1.80 5,565 1.01 1,855 4.43

1,555 1.49 2,385 1.82 5,855 1.07 1,165 3.99

1,695 1.54 2,585 1.85 6,155 1.06 1,215 4.07

1,825 1.59 2,795 1.97 6,475 1.13 1,265 4.13

1,965 1.65 3,015 2.01 6,785 1.13 1,325 4.22

2,115 1.71 3,235 2.08 7,105 1.17 1,385 4.28

2,265 1.75 3,475 2.16 7,445 1.20 1,435 4.28

2,425 1.78 3,715 2.22 7,775 1.22 1,495 4.30

2,585 1.84 3,965 2.27 8,125 1.26 1,555 4.30

2,745 1.90 4,215 2.34 8,465 1.30 1,615 4.33

2,915 1.97 4,485 2.34 8,825 1.30 1,665 4.34

3,085 2.01 4,755 2.43 1,725 4.37

3,265 2.06 5,025 2.49 1,785 4.21

3,445 2.10 5,315 2.52 1,855 4.26

3,635 2.15 5,605 2.57 1,915 4.34

3,825 2.19 5,905 2.58 1,975 4.39

4,015 2.21 6,215 2.64 2,035 4.45

4,215 2.25 6,525 2.65 2,105 4.49

4,425 2.32 6,845 2.73 2,165 4.54

4,625 2.35 7,175 2.77 2,225 4.50

4,845 2.39 7,505 2.78 2,295 4.48

5,055 2.46 7,855 2.79 2,355 4.45

5,275 2.46 8,195 2.81 2,425 4.46

5,495 2.50 8,555 2.86 2,495 4.48

5,725 2.55 8,765 2.87 2,555 4.56

5,955 2.58 2,625 4.63

6,195 2.61 2,695 4.69

6,435 2.63 2,765 4.74

6,675 2.68 2,835 4.70

6,915 2.69 2,905 4.76

7,175 2.72 2,975 4.75

Table 27. Drawdown data for the RC-9 aquifer test–Continued

Observation well CHLN-2

(site 56)

Observation well CL-2

(site 50)

Observation well RC-11

(site 62)

Observation well SP-2

(site 46)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)
86 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

7,435 2.73 3,045 4.77

7,695 2.75 3,115 4.81

7,955 2.77 3,185 4.82

8,215 2.80 3,265 4.87

3,335 4.93

3,405 4.99

3,485 5.08

3,555 5.12

3,625 5.20

3,705 5.21

3,775 5.15

3,855 5.13

3,935 5.11

4,005 5.14

4,095 5.19

4,175 5.29

4,255 5.30

4,335 5.23

4,405 5.25

4,485 5.24

4,565 5.31

4,645 5.34

4,725 5.43

4,815 5.52

4,895 5.61

4,975 5.69

5,055 5.65

5,135 5.64

5,225 5.63

5,305 5.58

5,385 5.51

5,475 5.52

5,555 5.56

Table 27. Drawdown data for the RC-9 aquifer test–Continued

Observation well CHLN-2

(site 56)

Observation well CL-2

(site 50)

Observation well RC-11

(site 62)

Observation well SP-2

(site 46)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)
Appendix A 87

5,645 5.68

5,725 5.69

5,815 5.76

5,895 5.79

5,985 5.80

6,075 5.77

6,155 5.77

6,245 5.81

6,335 5.90

6,425 5.97

6,515 6.04

6,605 6.10

6,695 6.16

6,775 6.13

6,865 6.17

6,955 6.19

7,055 6.28

7,165 6.24

7,255 6.30

7,345 6.29

7,435 6.32

7,525 6.27

7,625 6.31

7,715 6.32

7,805 6.41

7,905 6.48

7,995 6.56

8,085 6.61

8,185 6.59

8,275 6.54

8,375 6.52

8,465 6.60

8,565 6.57

Table 27. Drawdown data for the RC-9 aquifer test–Continued

Observation well CHLN-2

(site 56)

Observation well CL-2

(site 50)

Observation well RC-11

(site 62)

Observation well SP-2

(site 46)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)

Elapsed time

since start

of pumping

(minutes)

Drawdown 

(feet)
88 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

APPENDIX B: ADDITIONAL TABLES AND HYDROGRAPHS

Table 28. Water wells completed in the Madison aquifer

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 1)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)

1 441759103261202 4N6E19AABA2 MD-90A Tilford No. 2 (TF-2) 3,621 3,637 1 840

2 441500103253501 3N6E 5CACC 3,655 3,690 4 238

3 441337103225002 3N6E15ABB2 MD-94A Piedmont No. 2 (PDMT-2) 3,603 3,475 1 880

4 441220103213601 3N6E23ACD 3,341 3,540 2 918

5 441157103234301 3N6E21DDCD 3,854 3,900 4 71

6 440958103253401 2N6E 5BAC 4,340 4,640 4 400

7 440934103252001 2N6E 5CAD 4,280 4,465 4 245

8 440933103250701 2N6E 5DBD 4,280 4,500 4 282

9 441636103183801 2N7E 8BBC Blackhawk Water Company No. 4 3,511 3,530 2 1,160

10 440851103044801 2N9E 7CDCC Ellsworth AFB 2,687 3,230 4 4,640

11 440828103222601 2N6E10DD 3,895 4,120 4 380

12 440826103174701 2N7E 8DDCC2 3,450 3,600 4 790

13 440823103162701 2N7E16AAB 3,448 3,400 3 1,530

14 440820103232601 2N6E15BBBD 3,981 4,290 4 372

15 440811103222201 2N6E15ADAA PE-95C Doty Madison 3,808 4,059 1 425

16 440807103225801 2N6E15BDA 3,973 4,260 4 340

17 440804103230501 2N6E15BDB 3,976 4,260 4 370

18 440804103223001 2N6E15AD 3,874 4,160 4 420

19 440804103222701 2N6E15ADDB 3,774 4,140 4 400

20 440753103110801 2N8E13BDCD Ellsworth AFB No. 3 -- 3,190 4 4,440

21 440758103225601 2N6E15CBDD 3,913 4,260 4 540

22 440753103232401 2N6E15CBBD 3,980 4,260 4 410

23 440749103221501 2N6E14CBC 3,772 4,120 4 560

24 440744103223401 2N6E15DDB 3,876 4,210 4 407

25 440658103213001 2N6E23DBAB 3,660 3,860 4 420

26 440655103140501 2N7E23DACD Rapid City No. 8 (RC-8) 3,423 3,527 2 2,680

27 440650103193201 2N7E19CDAD 3,528 3,990 4 745

28 440631103211201 2N6E26AAD 3,645 3,940 4 357

29 440630103192501 2N7E30BADC 3,536 4,000 4 745

30 440629103040901 2N9E29BBCC City of Box Elder 2,575 3,043 2 4,450

31 440622103152701 2N7E27ACAB Coke Plant 3,481 3,400 3 1460

32 440612103152001 2N7E27DABB Rapid City No. 10 (RC-10) 3,444 3,363 2 1,790
Appendix B 89

33 440544103180002 2N7E32ABBC2 PE-89C City Quarry No. 2 (CQ-2) 3,451 3,492 1 826

34 440540103211301 2N6E35AADA2 3,646 4,120 2 740

35 440526103173001 2N7E32ADDD Rapid City No. 6 (RC-6) 3,447 3,440 2 1,300

36 440523103155701 2N7E34BDCC Black Hills Power & Light (BHPL) 3,424 3,300 3 --

37 440518103193001 2N7E31CAB 3,477 3,670 4 420

38 440512103215701 2N6E35CAC 3,734 4,130 4 436

39 440508103220701 2N6E35CCAB 3,764 4,140 4 450

40 440500103193601 2N7E31CCCA Westberry Trails No. 2 (WT-2) 3,520 3,974 2 680

41 440453103184001 1N7E 5BBBC 3,405 3,785 4 560

42 440446103193201 1N7E 6BACB 3,430 4,020 4 770

43 440446103161701 1N7E 3BBCC Lime Creek (LC) 3,417 3,314 1 1,390

44 440441103193301 1N7E 6BDCD 3,428 4,080 4 930

45 440432103191401 1N7E 6ACCC 3,405 3,940 4 770

46 440430103160202 1N7E 3CBAA2 PE-65A Sioux Park No. 2 (SP-2) 3,423 3,297 1 1,170

47 440427103131701 1N7E 1DBBB Rapid City No. 7 (RC-7, Star Village) 3,146 3,396 1 3,280

48 440337103191801 1N7E 7ACBD 3,418 3,640 4 380

49 440342103160701 1N7E10BCDB Rapid City No. 9 (RC-9) 3,415 3,330 2 1,051

50 440338103173302 1N7E 8ADDD2 PE-89A Canyon Lake (CL-2) 3,418 3,371 1 700

51 440334103095601 1N8E 9CAB2 Rapid Valley No. 4 2,655 3,108 4 3,800

52 440326103180702 1N7E 8DBCC Jackson Springs Well 1A (JS-1A) 3,418 3,380 4 640

53 440310103173802 1N7E 8DDCD2 Chapel Lane No. 3 (CHLN-3) 3,418 3,410 2 940

54 440308103184601 1N7E18AAAD PE-96A Cleghorn (CLEG) 3,417 3,414 1 200

55 440308103180701 1N7E17ABCC 3,419 3,430 4 460

56 440300103173501 1N7E17AAAC Chapel Lane No. 2 (CHLN-2) 3,419 3,433 2 820

57 440247103192401 1N7E18AACB 3,415 3,720 4 400

58 440302103194601 1N7E18BDBA 3,438 3,640 4 450

59 440247103191701 1N7E18ACCC 3,434 3,540 4 150

60 440238103185201 1N7E18DADB 3,416 3,620 4 321

61 440223103173201 1N7E17DDDA Carriage Hills No. 1 3,426 3,871 2 725

62 440220103164001 1N7E16DCDC Rapid City No. 11 (RC-11) 3,423 3,487 2 1,280

63 440205103172001 1N7E21BCAB 3,445 3,900 4 --

64 440054103173801 1N7E29DAAC 3,475 3,900 4 1,000

65 440523103194201 1N7E31BCAD 3,806 4,260 4 598

66 440004103174001 1N7E32DABA Highland Hills 3,531 3,999 2 780

Table 28. Water wells completed in the Madison aquifer–Continued

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 1)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)
90 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

67 435937103184101 1S7E 5BAA 3,626 3,920 2 --

68 435916103161801 1S7E 3CDBD PE-86A Reptile Gardens (RG) 3,497 3,520 1 1,220

69 435903103181301 1S7E 8ABAA 3,594 4,100 4 754

70 435851103184201 1S7E 8BDBA 3,580 4,180 4 640

71 435851103143501 1S7E11ACAB Hart Ranch No. 2 3,498 3,466 2 1,740

72 435746103160601 1S7E15CBBB 3,488 3,985 4 820

73 435718103130301 1S8E19BBBB Hart Ranch No. 1 3,498 3,555 2 2,600

74 435635103181401 1S7E20DCAD Pine Grove 3,515 4,120 2 903

75 435619103161901 1S7E27BACA 3,509 4,140 4 1,190

76 435518103173001 1S7E33BDBD 3,530 4,090 4 680

77 435227103185301 2S7E17CCAA PE-95A Hayward (HWRD) 3,542 3,932 1 540

Wells Not Shown on Plate 1 (unreliable hydraulic heads)

78 442217103272201 5N5E26ABDA 3,129 3,625 4 1,460

79 440443103161301 1N7E 3BBCD Rapid City No. 5 (RC-5) -- 3,310 2 1,292

80 442058103273001 5N5E36DBCB 3,204 3,720 2 1,050

81 441845103352001 4N4E13B 4,890 5,050 4 227

82 441838103344301 4N4E13A 4,720 4,880 4 227

83 441830103312701 4N5E16BDD 4,540 4,620 4 115

84 441817103311901 4N5E16DBC 4,455 4,620 4 360

85 440933103253301 2N6E 5CAC 4,300 4,500 4 245

86 440908103193401 2N7E 7BAC 3,439 3,679 4 --

87 440805103223001 2N6E15AD 3,786 4,160 4 430

88 440810103234401 2N6E15BC 4,022 4,300 4 505

89 440755103231801 2N6E15CBA 4,015 4,320 4 480

90 440758103214301 2N6E14CAC 3,804 4,150 4 540

91 440737103222501 2N6E15DDD 3,781 4,160 4 415

92 440636103214701 2N6E26BAAC 3,694 3,950 4 340

93 440602103194201 2N7E31BCB 3,393 3,770 4 525

94 440244103191901 1N7E18BAC 3,417 3,620 4 380

95 440254103191801 1N7E18ACB 3,420 3,630 4 320

96 440248103195001 1N7E18BCC 3,585 3,600 4 32

97 440245103192501 1N7E18CAAB 3,410 3,500 4 280

98 440242103192301 1N7E18CAA 3,342 3,440 4 280

99 440241103194001 1N7E18CBA 3,650 3,700 4 185

100 435143103184401 2S7E20BDC 3,490 3,890 4 624

Table 28. Water wells completed in the Madison aquifer–Continued

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 1)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)
Appendix B 91

Table 29. Water wells completed in the Minnelusa aquifer

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 2)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

 surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)

102 441812103230501 4N6E16DCB 3,454 3,460 4 1,460

103 441826103263301 4N6E17CCDA 3,564 3,578 4 590

104 441759103261201 4N6E19AABA MD-84B Tilford No. 1 (TF-1) 3,608 3,636 1 302

105 441701103251101 4N6E29ABC Piedmont East (PDMT-East) 3,515 3,542 1 180

106 441656103261601 4N6E30A 3,592 3,860 4 340

107 441649103262401 4N6E30ADCC 3,593 3,930 4 540

108 441620103255301 4N6E29CCC 3,529 3,630 4 240

109 441612103252801 4N6E32BAA 3,532 3,590 4 265

110 441606103252501 4N6E32BAD 3,557 3,620 4 225

111 441556103253201 4N6E32BBDD 3,514 3,680 4 280

112 441504103230301 3N6E 3BCBC 3,428 3,460 4 755

113 441500103240601 3N6E 4 3,422 3,520 4 300

114 441453103243801 3N6E 4CB 3,486 3,570 4 328

115 442221103245501 3N6E 5DA 3,527 3,590 4 250

116 441314103233301 3N6E10ABAA 3,412 3,400 4 425

117 441424103243601 3N6E 9BBCD 3,506 3,780 4 320

118 441421103242302 3N6E 9BCBB2 3,510 3,740 4 365

119 441400103231501 3N6E10BDDB 3,478 3,435 4 625

120 441358103241801 3N6E 9CABB 3,526 3,760 4 260

121 441643103232801 3N6E10CCC 3,490 3,530 4 275

122 441339103232701 3N6E16AAAB 3,530 3,570 4 237

123 441338103233201 3N6E16AABA 3,528 3,590 4 190

124 441337103225001 3N6E15ABBB MD-84A Piedmont No. 1 (PDMT-1) 3,481 3,475 1 440

125 441335103223202 3N6E15AAB 3,414 3,490 4 110

126 441335103223201 3N6E15AB 3,414 3,490 4 100

127 441333103222801 3N6E15AAAC 3,457 3,470 4 640

128 441331103230701 3N6E15BA3 3,454 3,530 4 160

129 441322103234202 3N6E16AD2 3,547 3,660 4 260

130 441322103234201 3N6E16AD 3,581 3,660 4 340

131 441315103224001 3N6E15DABBB 3,489 3,530 4 365

132 441257103222501 3N6E15DAA 3,458 3,590 4 263

133 441241103183401 3N7E20BB2 3,268 3,460 4 340
92 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

134 441219103204801 3N6E24CABB 3,414 3,570 2 1,005

135 441242103215701 3N6E23CAB 3,495 3,730 4 288

136 441216103215801 3N6E23CABD 3,477 3,700 4 460

137 441210103215101 3N6E23CADA 3,483 3,570 4 328

138 441212103201501 3N6E24DBDA 3,366 3,840 2 1,542

139 441211103213701 3N6E23DBCA 3,458 3,560 4 375

140 441202103211301 3N6E23DDAC 3,476 3,558 4 860

141 441318103221301 3N6E24CADD 3,449 3,600 4 824

142 442137103213801 3N6E23DCB 4 3,444 3,600 4 300

143 441202103213301 3N6E23DC 3,474 3,580 4 360

144 441200103213001 3N6E23DCCB 3,471 3,605 4 305

145 441157103213701 3N6E23DDDC 3,445 3,580 4 440

146 441220103214001 3N6E23DCDC 3,451 3,608 4 360

147 441151103213002 3N6E26AABB 3,459 3,600 4 395

148 441147103270001 3N7E30BCAD 3,413 3,870 2 1,600

149 441136103221301 3N6E26ACAD 3,415 3,680 4 360

150 441134103211601 3N6E26ADBB 3,460 3,645 4 300

151 441131103200101 3N6E25ADDA 3,418 3,615 4 783

152 441130103205601 3N6E25BCDC 3,466 3,630 4 400

153 441119103210301 3N6E25CBCB 3,453 3,680 4 303

154 441105103192001 3N7E30CDD 3,454 3,650 4 1,120

155 441125103203001 3N6E25DCCD 3,413 3,690 4 500

156 441038103203001 3N6E36BADB 3,403 3,735 4 420

157 441049103203701 3N6E36BADD 3,423 3,725 4 400

158 441047103203301 3N6E36BDAA 3,423 3,720 4 400

159 441323103232301 3N6E36BDCA 3,496 3,780 4 520

160 441040103203201 3N6E36BDDA 3,438 3,740 4 --

161 441038103203002 3N6E36B 3,492 3,820 4 400

162 441037103203502 3N6E36BDD2 3,472 3,760 4 360

163 441037103203501 3N6E36BDD 3,450 3,760 4 360

164 441033103193001 3N7E31CAA 3,463 3,630 4 520

165 441031103195201 3N7E31CBBC 3,443 3,690 4 462

Table 29. Water wells completed in the Minnelusa aquifer–Continued

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 2)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

 surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)
Appendix B 93

166 441024103201301 3N6E36DBD 3,487 3,720 4 440

167 441023103204001 3N6E36CADD 3,474 3,780 4 565

168 441023103203101 3N6E36DBCC 3,440 3,810 4 540

169 441023103203001 3N6E36DBBD 3,423 3,740 4 312

170 441007103201101 2N6E 1AABB 3,432 3,725 4 340

171 440930103175201 2N7E 5DBDD 3,489 3,460 4 --

172 440936103191801 2N7E 6CDAC Blackhawk Water Co. No. 3 3,447 3,545 2 340

173 440919103170501 2N7E 4CDCD 3,416 3,405 4 920

174 440929103163501 2N7E 4DDC 3,379 3,435 4 1,025

175 440916103163301 2N7E 9AABB 3,392 3,420 4 1,260

176 440907103183501 2N7E 8BBCD Blackhawk Water Co. No. 2 3,386 3,510 2 750

177 440908103193101 2N7E 7BACA 3,462 3,720 4 480

178 440901103184801 2N7E 7ADAB Blackhawk Water Co. No. 1 3,403 3,580 2 600

179 440829103183801 2N7E 8CCC 3,414 3,560 4 590

180 440826103174601 2N7E 8DDCC 3,410 3,600 4 815

181 440818103180801 2N7E17BAAD PE-84B Blackhawk No. 1 (BLHK-1) 3,422 3,500 1 560

182 440818103174701 2N7E17BACA 3,449 3,500 4 650

183 440800103163001 2N7E16 3,313 3,360 4 320

184 440738103173901 2N7E17DDBD 3,409 3,450 4 371

185 440736103173701 2N7E17DDAA 3,412 3,450 2 400

186 440719103174801 2N7E20ABAD 3,434 3,480 4 263

187 440636103152001 2N7E27AABA 3,400 3,435 4 992

188 440635103161801 2N7E27BBCB 3,420 3,450 3 --

189 440607103155901 2N7E27CAAB 3,383 3,360 3 615

190 440606103174701 2N7E29DACB 3,419 3,600 4 349

191 440605103174701 2N7E29DAC1 3,419 3,600 4 349

192 440552103173401 2N7E29DAC5 3,421 3,570 4 220

193 440603103174501 2N7E29DAC3 3,427 3,600 4 190

194 440552103162301 2N7E28DACD 3,336 3,360 3 300

195 440557103174401 2N7E29DDB 3,414 3,600 4 308

196 440556103174801 2N7E29DDBD2 3,449 3,620 4 320

197 440542103172501 2N7E28CC 3,410 3,500 4 320

Table 29. Water wells completed in the Minnelusa aquifer–Continued

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 2)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

 surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)
94 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

198 440639103173701 2N7E29DDCA 3,443 3,620 4 340

199 440545103173501 2N7E32AAAC 3,438 3,610 4 300

200 440544103180001 2N7E32ABBD PE-89D City Quarry No. 1 (CQ-1) 3,450 3,492 1 --

201 440544103174301 2N7E32AABD 3,444 3,640 4 302

202 440544103173601 2N7E32AAA 3,468 3,640 4 340

203 440540103194601 2N7E31BBCD 3,553 3,810 4 270

204 440539103205401 2N6E36BBD 3,769 4,080 4 390

205 440538103161001 2N7E34B 3,328 3,340 4 220

206 440534103174801 2N7E32AACD 3,467 3,640 4 195

207 440534103171401 2N7E33BCAA 3,450 3,460 4 200

208 440533103193801 2N7E31BCAA 3,416 3,720 4 440

209 440528103161001 2N7E34BCCA PE-64A Cement Plant (CP) 3,412 3,331 1 400

210 440528103155201 2N7E34BDAD 3,406 3,350 4 585

211 440521103184401 2N7E32BCCC 3,471 3,602 4 --

212 440532103182001 2N7E32CADA 3,462 3,510 4 310

213 440514103161401 2N7E34CBCD 3,403 3,340 3 371

214 450512103182101 2N7E32CAC 3,434 3,520 4 230

215 440516103194001 2N7E31CDCB Westberry Trails No. 1 (WT-1) 3,406 3,860 2 565

216 440501103181501 2N7E32CDAD 3,475 3,520 4 200

217 440459103181001 2N7E32CDDD 3,450 3,480 4 180

218 440458103181101 2N7E32CDDDB 3,450 3,480 4 180

219 440452103155301 1N7E 3BABD South Dakota ARNG 3,396 3,340 4 600

220 440449103181501 1N7E 5ABCA 3,435 3,490 4 207

221 440446103181801 1N7E 5BAC 3,415 3,700 4 430

222 440445103181601 1N7E 5BACA 3,470 3,700 4 360

223 440430103160201 1N7E 3CBAA PE 64B Sioux Park No. 1 (SP-1) 3,392 3,300 1 570

224 440423103180501 1N7E 5DBCA West Camp Rapid No. 3 (WCR-3) 3,400 3,580 1 224

225 440403103183701 1N7E 5CDD 3,382 3,580 4 330

226 440347103190501 1N7E 7ACA 3,435 3,497 4 --

227 440344103190801 1N7E 7AC 3,456 3,506 4 152

228 440344103173701 1N7E 8AC 3,360 3,460 4 140

229 440338103173301 1N7E 8ADDD PE-89B Canyon Lake No. 1 (CL-1) 3,360 3,371 1 --

Table 29. Water wells completed in the Minnelusa aquifer–Continued

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 2)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

 surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)
Appendix B 95

230 440331103155101 1N7E10CADD 3,396 3,410 4 700

231 440326103180703 1N7E 8DBCC2 Jackson Springs Well 1B (JS-1B) 3,395 3,380 1 --

232 440321103181001 1N7E 8CDAA 3,365 3,460 4 135

233 440310103173801 1N7E 8DDCD Chapel Lane No. 1 (CHLN-1) 3,383 3,410 1 360

234 440309103170101 1N7E16BAAB 3,360 3,430 4 183

235 440308103183001 1N7E17BBA 3,435 3,480 4 --

236 440308103172501 1N7E16BBB 3,378 3,580 4 312

237 440308103144301 1N7E14BABD 3,353 3,833 4 1,817

238 440336103165301 1N7E16BBBB 3,353 3,575 4 250

239 440307103181501 1N7E17BABD 3,399 3,724 4 --

240 440305103164501 1N7E16BADA2 3,364 3,440 4 250

241 440211103165601 1N7E16BADA 3,370 3,440 4 207

242 440301103165701 1N7E16BAD 3,350 3,440 4 300

243 440300103170901 1N7E16BAC 3,380 3,500 4 220

244 440257103171101 1N7E16BACC 3,355 3,520 4 240

245 440252103172201 1N7E16BC 3,336 3,540 4 280

246 440249103182101 1N7E17BDC 3,450 3,480 4 115

247 440247103165401 1N7E16BDBB 3,342 3,500 4 235

248 440242103170801 1N7E16CAB 3,386 3,500 4 260

249 440244103154102 1N7E15CBBD2 3,374 3,475 4 460

250 440236103145801 1N7E14CBCA 3,351 3,880 4 1,650

251 440233103170501 1N7E16CACD 3,387 3,580 4 258

252 440223103161701 1N7E15CCBC 3,381 3,440 2 360

253 440224103172601 1N7E16CCCA Carriage Hills No. 2 3,372 3,840 2 612

254 440214103153501 1N7E15DCCA 3,388 3,600 2 780

255 440211103165201 1N7E21BADA 3,401 3,650 4 422

256 440211103164301 1N7E21ABDB 3,409 3,570 4 200

257 440204103150001 1N7E23BCB 3,392 3,858 4 1,680

258 440203103143601 1N7E23BDAB 3,390 3,840 4 1,870

259 440158103160401 1N7E22BDCC Spring Brook South No. 3 3,429 3,565 2 445

260 440149103164901 1N7E21DBBD Wildwood North 3,412 3,675 1 --

261 440130103163401 1N7E21DDCD Wildwood South 3,429 3,720 1 400

Table 29. Water wells completed in the Minnelusa aquifer–Continued

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 2)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

 surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)
96 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

262 440103103144801 1N7E26BCDA 3,376 3,720 4 1545

263 440059103154101 1N7E27DADB 3,456 3,815 4 1,430

264 440048103145001 1N7E26CCAA 3,455 3,820 4 1,460

265 440038103172601 1N7E28CCC 3,475 3,840 4 600

266 440031103162701 1N7E33AAA 3,459 3,830 4 560

267 440028103160801 1N7E34BAC 3,412 3,815 4 660

268 440027103161001 1N7E34BBCA 3,499 3,840 4 516

269 440022103163401 1N7E33AABC 3,494 3,850 4 623

270 440007103165301 1N7E33ADBB 3,455 3,840 4 540

271 440010103154201 1N7E34 3,404 3,820 4 700

272 435916103161802 1S7E 3CDBD2 PE-94A Reptile Gardens No. 2 (RG-2) 3,493 3,519 1 660

273 435858103155701 1S7E10ABBD 3,476 3,518 4 515

274 435803103160301 1S7E15ABC 3,539 3,680 4 245

275 445809103162201 1S7E15CABA 3,548 3,765 4 430

276 435720103141601 1S7E13CBCA Hart Ranch No. 3 3,547 3,780 2 1,525

277 435352103170801 2S7E 4ACDB 3,558 3,800 4 358

278 435325103171701 2S7E 9CBDA 3,527 3,960 4 580

279 435225103172801 2S7E16CACA 3,551 3,700 4 240

280 435119103175001 2S7E21CCC 3,536 3,865 4 500

281 435115103170501 2S7E21DDC 3,511 3,750 4 350

Wells Not Shown on Plate 2 (unreliable hydraulic heads)

282 442213103283101 5N5E26ABD 3,124 3,620 4 1,375

283 442158103284701 5N5E26 3,248 3,800 4 1,140

284 442146103272001 5N5E25CADB 3,113 3,710 2 1,000

285 442108103270301 5N5E36ADD 3,164 3,690 2 1,120

286 441903103261601 4N6E7DDBB 3,464 3,710 4 700

287 441641103252001 4N6E29BCAD 3,627 3,700 4 176

288 441648103264001 4N6E30BDA 3,743 4,000 4 540

289 441640103245901 4N6E29DAB 3,612 3,620 4 220

290 441549103252002 4N6E32(2) 3,480 3,618 4 220

291 441544103253001 4N6E32CA 3,628 3,640 4 260

292 441538103255601 4N6E32CCB 3,770 3,800 4 300

Table 29. Water wells completed in the Minnelusa aquifer–Continued

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 2)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

 surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)
Appendix B 97

Wells Not Shown on Plate 2 (unreliable hydraulic heads)—Continued

293 441522103252501 3N6E 5BAB 3,430 3,700 4 558

294 441443103223701 3N6E 3DD 3,305 3,420 4 1260

295 441441103252301 3N6E 5CD 3,620 3,650 4 140

296 441228103185301 3N7E19ADCA 3,429 3,540 4 1,200

297 441108103205701 3N6E25CC 3,383 3,670 4 --

298 441118103210001 3N6E25CCDD 3,400 3,720 4 370

299 441051103205901 3N6E36BBCA 3,363 3,760 4 570

300 441029103202201 3N6E36DB 3,547 3,722 4 338

301 440930103190501 2N7E 6DCD 3,426 3,520 4 --

302 440927103173501 2N7E 5DDA 3,380 3,440 4 885

303 440913103194001 2N7E 7BB -- 3,520 4 380

304 440820103164701 2N7E16ABBD 3,267 3,400 4 445

305 440747103174901 2N7E17D 3,399 3,460 4 440

306 440702103181401 2N7E20CAAC 3,300 3,580 4 380

307 440605103182801 2N7E29DBD 3,505 3,685 4 330

308 440525103171701 2N7E33BCD 3,340 3,430 4 240

309 440522103185301 2N7E31ADCD 3,534 3,680 4 247

310 440518103163604 2N7E33DAB4 3,388 3,400 4 220

311 440517103194801 2N7E31CBBD 3,672 3,800 4 260

312 440508103221001 2N6E35CCBA 3,827 4,180 4 582

313 440458103180101 2N7E32CCDC 3,400 3,640 4 --

314 440447103183101 1N7E 5BBDB 3,394 3,770 4 500

315 440414103164601 1N7E 4DCB Rapid City No. 4 (RC-4) -- 3,350 2 1,080

316 441351103171301 1N7E 9BBCA Rapid City No. 3 (RC-3) -- 3,376 2 902

317 440338103171601 1N7E 9BCDC Rapid City No. 1 (RC-1) -- 3,360 2 1,460

318 440331103200301 1N6E12DAAC 3,560 3,860 4 415

319 440328103191001 1N7E7DBC 3,640 3,700 4 155

320 440302103172601 1N7E16BAD2 3,415 3,440 4 222

321 440255103172601 1N7E16BCB 3,432 3,560 4 200

322 440249103172701 1N7E16BCC 3,404 3,580 4 317

323 440246103180801 1N7E17 3,683 3,700 4 78

Table 29. Water wells completed in the Minnelusa aquifer–Continued

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 2)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

 surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)
98 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Wells Not Shown on Plate 2 (unreliable hydraulic heads)—Continued

324 440331103142701 1N7E11DBAD 3,164 3,560 4 1,755

325 440234103171201 1N7E16CACC 3,415 3,600 4 300

326 440202103165801 1N7E21BDA 3,384 3,760 4 565

327 440158103165601 1N7E21(2) 3,622 3,740 4 240

328 440155103165001 1N7E21ACC 3,574 3,660 4 --

329 440149103144301 1N7E23CAB 3,425 3,810 4 1,563

330 440148103164101 1N7E21DBA 3,388 3,620 4 602

331 440130103153901 1N7E22DCC 3,365 3,780 4 875

332 440129103161301 1N7E22CCC 3,591 3,650 4 315

333 440022103171301 1N7E33(3) 3,693 3,860 4 430

334 435845103163401 1S7E10BCAC 3,476 3,700 4 300

335 435340103161001 2S7E10BAD 3,366 3,660 4 675

336 435053103170001 2S7E28ADCB 3,492 3,760 4 300

337 435052103182801 2S7E29 3,661 3,800 4 --

338 435052103172901 2S7E28BDCA 3,459 3,825 4 425

339 435050103170501 2S7E28ACDC 3,608 3,700 4 167

340 435050103165301 2S7E28ADD 3,571 3,740 4 320

341 435042103180301 2S7E29DACA 3,527 3,590 4 75

342 435048103171301 2S7E28CABA 3,439 3,545 4 320

343 435031103173401 2S7E28CDBC 3,488 3,560 4 77

344 435028103240601 2S7E28DDCB 3,477 3,760 4 309

345 435018103155801 2S7E34ABBA CU-83A West Hermosa (WH) 3,554 3,478 1 510

346 435019103173101 2S7E33BABA 3,533 3,820 4 468

347 435010103173001 2S7E33BAC 3,500 3,760 4 292

348 435008103162501 2S7E34BDBC 3,477 3,500 4 225

349 435006103163801 2S7E34BCB 3,590 3,560 4 240

Table 29. Water wells completed in the Minnelusa aquifer–Continued

[Use codes: 1, continuous-record observation well; 2, public supply well; 3, industrial/commercial; 4, other/unknown. --, no data available]

Site

number

(pl. 2)

Station

identification

number

Local number Name

Adjusted

hydraulic

head

Land

 surface

altitude

Use 

code

Depth 

(feet)

(feet above sea level)
Appendix B 99

Some wells were monitored discontinuously 

or were monitored continuously for brief periods 

(figs. 37-39). Although very few hydraulic-head 

measurements have been made at the Hart Ranch wells, 

the measurements indicate that a continuous 

hydrograph at these locations probably would be 

very similar to that of well RG (fig. 37). 

Figure 37. Hydraulic head in Hart Ranch No. 1 and 2 wells plotted with the Reptile Gardens (RG)

Madison well. The three wells were completed in the Madison aquifer. The plot shows the similarity

of hydraulic head in the Hart Ranch wells to that of the Reptile Gardens well.

CALENDAR YEAR

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

3,450

3,460

3,470

3,480

3,490

3,500

3,510

3,520

3,530

3,540

3,550

3,560

3,570

Reptile Gardens Madison well (RG, site 68)

Site number refers to table 28 and plate 1

Hart Ranch No. 2 (site 71)

Hart Ranch No. 1 (site 73)

Discontinous record
100 Flow-System Analysis of Madison and Minnelusa Aquifers in the Rapid City Area, SD—Conceptual Model

Figure 38. Hydraulic head in well RC-11 (site 62, table 28 and plate 1) completed in the Madison aquifer. 

The well is influenced by pumping during the summer months.

Figure 39. Hydraulic head in the Wildwood North and South wells completed in the Minnelusa aquifer.

CALENDAR YEAR

1995 1996 1997 

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

3,428

3,429

3,430

3,431

3,432

3,433

3,434

3,435

3,436

3,437

3,438

MONTH

JAN

1996

JAN

1997

JAN

1998

HYDRAULIC HEAD, IN FEET ABOVE SEA LEVEL

3,430

3,435

3,440

3,445

3,450

3,455

3,460

3,465

Wildwood North (site 260)

Wildwood South (site 261)

Site number refers to table 29 and

plate 2