Simulated Ground-Water Flow in the Ogallala

and Arikaree Aquifers, Rosebud Indian

Reservation Area, South Dakota

Water-Resources Investigations Report 03-4043

Prepared in cooperation with the

Rosebud Sioux Tribe

U.S. Department of the Interior

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

U.S. Geological Survey

Simulated Ground-Water Flow in the Ogallala 

and Arikaree Aquifers, Rosebud Indian 

Reservation Area, South Dakota

By Andrew J. Long, Larry D. Putnam, and Janet M. Carter

Water-Resources Investigations Report 03-4043

Prepared in cooperation with the

Rosebud Sioux Tribe
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: 2003

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

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

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

Physiography, Land Use, and Climate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Drainage Features and Streamflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Hydrogeologic Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Simulated Ground-Water Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Conceptual Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Potentiometric Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Hydraulic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Evapotranspiration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Discharge to Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Well Withdrawals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Numerical Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Model Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Grid and Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Representation of Hydraulic Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Representation of Recharge and Discharge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Model Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Steady-State Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Transient Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Model Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Supplemental Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

FIGURES

1. Map showing study area and locations of main physiographic divisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2. Map showing drainage basins in study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3. Generalized geologic map showing surficial geology of study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4. Map showing estimated average potentiometric surface of the Ogallala aquifer. . . . . . . . . . . . . . . . . . . . . . . . . . 11

5. Map showing estimated average potentiometric surface of the Arikaree aquifer . . . . . . . . . . . . . . . . . . . . . . . . . 12

6. Graph showing relation between average hydraulic head, hydrogeologic units, and topographic features. . . . . . 14

7-13. Maps showing:

7. Streamflow measurement sites for seepage runs during water year 1999 . . . . . . . . . . . . . . . . . . . . . . . . . . 18

8. Locations of irrigation wells completed in the Ogallala and Arikaree aquifers . . . . . . . . . . . . . . . . . . . . . . 22

9. Cell types in the Ogallala aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

10. Cell types in the Arikaree aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

11. Estimated horizontal hydraulic conductivity of the Ogallala aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

12. Generalized specific capacity ranges in the Ogallala aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

13. Hydraulic conductivity estimated from grain-size descriptions in the High Plains aquifer . . . . . . . . . . . . . 29
IV Contents

FIGURES—Continued

14-18. Maps showing:

14. Estimated horizontal hydraulic conductivity of the Arikaree aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

15. Estimated vertical hydraulic conductivity of the Arikaree aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

16. Evapotranspiration, river cells, drain cells, and irrigation wells in the Ogallala and Arikaree aquifers . . . 34

17. Potentiometric surface of the Ogallala aquifer for the steady-state simulation. . . . . . . . . . . . . . . . . . . . . . 37

18. Potentiometric surface of the Arikaree aquifer for the steady-state simulation . . . . . . . . . . . . . . . . . . . . . 38

19. Histograms of residuals of estimated average observed and steady-state simulated hydraulic head

in A) all wells, B) State observations wells, and C) Tribal observation wells for the Ogallala and

Arikaree aquifers, water years 1979-98 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

20. Graph showing linear regression of observed and simulated hydraulic heads for all wells . . . . . . . . . . . . . . . . . 40

21. Graph showing results of sensitivity analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

22. Hydrographs showing simulated and observed data for State observation wells . . . . . . . . . . . . . . . . . . . . . . . . . 42

23. Hydrographs showing simulated and annual average observed data for Tribal observation wells. . . . . . . . . . . . 46

24. Graphs showing comparison of estimated and simulated base flow for the Little White

and Keya Paha Rivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

TABLES

1. Generalized stratigraphic column showing geologic units and hydrologic characteristics. . . . . . . . . . . . . . . . . . 6

2. Previously published hydraulic properties within or near the study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3. Maximum evapotranspiration during summer stress periods, water years 1979-98 . . . . . . . . . . . . . . . . . . . . . . . 17

4. Measured streamflow at selected sites during seepage runs in water year 1999. . . . . . . . . . . . . . . . . . . . . . . . . . 19

5. Estimates of base flow in the Little White and Keya Paha Rivers, water years 1979-98 . . . . . . . . . . . . . . . . . . . 21

6. Estimated ground-water withdrawals for irrigation use in the study area, 1979-98 . . . . . . . . . . . . . . . . . . . . . . . 23

7. Estimated recharge to the Ogallala and Arikaree aquifers, water years 1979-98 . . . . . . . . . . . . . . . . . . . . . . . . . 33

8. Selected data for State observation wells in the study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

9. Selected data for Tribal observation wells in the study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

10. Comparison of simulated and estimated base flow for the Little White and Keya Paha Rivers

for the steady-state simulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

11. Steady-state water budget for numerical simulation compared with flow estimates for conceptual model . . . . . 40

12. Comparison of observed and simulated hydraulic heads for State observation wells for the

transient simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

13. Comparison of observed and simulated hydraulic heads for Tribal observation wells for the

transient simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

14. Comparison of average simulated and estimated base flow for the Little White and Keya Paha Rivers

for the transient-state simulation, water years 1979-98. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

15. Wells used for estimating potentiometric surface of the Ogallala aquifer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

16. Wells used for estimating potentiometric surface of the Arikaree aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Contents V

CONVERSION FACTORS, VERTICAL DATUM, AND WELL-NUMBERING SYSTEM

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

°C = (° F - 32) / 1.8

Altitude: In this report, vertical coordinate information is referenced 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, 1998, is 

called “WY98.”

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 squared per day (ft2/s) 0.09290 meter squared per day 

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

gallon per minute per foot [(gal/min)/ft] 0.2070 liter per second per meter

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 
VI Contents

36

A B

C D

A B

C D

C

A B

C D

D

A

B

1 2 3 4 5 6

12

11

10 9 8 7

13

14

15

16

17

24

23

22

21

20

19

25

26

27

28

29

30

18

35

34

33

32

31

R. 28 W. T. 38 N.

MELLETTE COUNTY

TODD COUNTY

SOUTH DAKOTA

NEBRASKA

T. 36 N.

T. 37 N.

T. 38 N.

T. 39 N.

T. 40 N.

T. 41 N.

T. 42 N.

T. 35 N.

R. 31 W.

R. 32 W.

R. 33 W.

R. 27 W.

R. 28 W.

R. 29 W. R. 30 W.

R. 25 W.

R. 26 W.

Well

38N28W36ABCB

Well-numbering system. The well number consists of the township number, followed by "N," the range number followed 

by "W," and the section number followed by a maximum of four uppercase letters that indicate, respectively, the 160-, 

40-, 10-, and 2 1/2-acre tract in which the well is located. These letters are assigned in a counterclockwise direction 

beginning with "A" in the northeast quarter. A serial number following the last letter is used to distinguish between wells 

in the same 2 1/2-acre tract.
Abstract 1

Simulated Ground-Water Flow in the Ogallala

and Arikaree Aquifers, Rosebud Indian

Reservation Area, South Dakota

By Andrew J. Long, Larry D. Putnam, and Janet M. Carter

ABSTRACT

The Ogallala and Arikaree aquifers are 

important water resources in the Rosebud Indian 

Reservation area and are used extensively for irrigation, municipal, and domestic water supplies. 

Continued or increased withdrawals from the 

Ogallala and Arikaree aquifers in the Rosebud 

Indian Reservation area have the potential to affect 

water levels in these aquifers. This report describes 

a conceptual model of ground-water flow in these 

aquifers and documents the development and calibration of a numerical model to simulate groundwater flow. Data for a twenty-year period (water 

years 1979 through 1998) were analyzed for the 

conceptual model and included in steady-state and 

transient numerical simulations of ground-water 

flow for the same 20-year period.

A three-dimensional ground-water flow 

model, with two layers, was used to simulate 

ground-water flow in the Ogallala and Arikaree 

aquifers. The upper layer represented the Ogallala 

aquifer, and the lower layer represented the Arikaree aquifer. The study area was divided into grid 

blocks 1,640 feet (500 meters) on a side, with 153 

rows and 180 columns.

Areal recharge to the Ogallala and Arikaree 

aquifers occurs from precipitation on the outcrop 

areas. The recharge rate for the steady-state simulation was 3.3 inches per year for the Ogallala 

aquifer and 1.7 inches per year for the Arikaree 

aquifer for a total recharge rate of 266 cubic feet 

per second.

Discharge from the Ogallala and Arikaree 

aquifers occurs through evapotranspiration, discharge to streams, and well withdrawals. Discharge rates in cubic feet per second for the steadystate simulation were 184 for evapotranspiration, 

46.8 and 19.7 for base flow to the Little White and 

Keya Paha Rivers, respectively, and 11.6 for well 

withdrawals from irrigation use. Estimated horizontal hydraulic conductivity used for the numerical model ranged from 0.2 to 120 feet per day in 

the Ogallala aquifer and 0.1 to 5.4 feet per day in 

the Arikaree aquifer. A uniform vertical hydraulic 

conductivity value of 6.6x10-4 feet per day was 

applied to the Ogallala aquifer. Vertical hydraulic 

conductivity was estimated for five zones in the 

Arikaree aquifer and ranged from 8.6x10-6 to 

7.2x10-1 feet per day. Average rates of recharge, 

maximum evapotranspiration, and well withdrawals were included in the steady-state simulation, whereas the time-varying rates were included 

in the transient simulation.

Model calibration was accomplished by 

varying parameters within plausible ranges to 

produce the best fit between simulated and 

observed hydraulic heads and base-flow discharges from the Ogallala and Arikaree aquifers. 

For the steady-state simulation, the root mean 

square error for simulated hydraulic heads for all 

wells was 26.8 feet. Simulated hydraulic heads 

were within ±50 feet of observed values for 

95 percent of the wells. For the transient simulation, the difference between the simulated and 

observed means for hydrographs was within 
2 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

±40 feet for all observation wells. The potentiometric surfaces of the two aquifers calculated by 

the steady-state simulation established initial conditions for the transient simulation.

A sensitivity analysis was used to examine 

the response of the calibrated steady-state model to 

changes in model parameters including horizontal 

and vertical hydraulic conductivity, evapotranspiration, recharge, and riverbed conductance. The 

model was most sensitive to recharge and horizontal hydraulic conductivity.

INTRODUCTION

 The Ogallala and Arikaree aquifers are included 

in the High Plains aquifer system that underlies parts of 

eight States and extends from southern South Dakota to 

Texas. About 20 percent of the irrigated land in the 

United States is in the region underlain by the High 

Plains aquifer, and nearly 30 percent of the ground 

water used for irrigation in the United States is pumped 

from the High Plains aquifer (Weeks and others, 1988). 

 The High Plains aquifer underlies about 

4,750 square miles in south-central South Dakota 

(Gutentag and others, 1984) including most of the 

Rosebud Indian Reservation. In this area, the Ogallala 

and Arikaree aquifers are important water resources 

and are used extensively for irrigation, municipal, and 

domestic water supplies. Water levels in the High 

Plains aquifer in South Dakota generally did not change 

significantly from 1980 to 1999 (McGuire, 2001). 

However, water-level declines greater than 60 feet were 

measured from 1980 to 1999 in the aquifer in other 

areas, including Kansas, New Mexico, and Texas 

(McGuire, 2001). Prior to 1980, water levels in the 

High Plains aquifer had declined more than 100 feet in 

some areas (Luckey and others, 1981). Thus, continued 

or increased withdrawals from the Ogallala and 

Arikaree aquifers in the Rosebud Indian Reservation 

area have the potential to affect water levels in these 

aquifers and base-flow discharge to area streams.

The Rosebud Sioux Tribe has identified a need 

for water-resource tools to evaluate management issues 

associated with the Ogallala and Arikaree aquifers, 

such as planning for source-water protection, 

describing potential impacts of contamination, and estimating sustainable aquifer withdrawals. A primary tool 

conceived by the Tribe was a numerical ground-water 

flow model of these aquifers for the Rosebud Indian 

Reservation. Therefore, the Tribe has worked in cooperation with the U.S. Geological Survey (USGS) to 

develop the model described in this report. Further 

development of this numerical model would allow the 

Tribe to simulate the effects of various hydrologic 

stresses such as increased ground-water withdrawals or 

drought conditions. 

Purpose and Scope

The purpose of this report is to describe a numerical model developed to simulate ground-water flow in 

the Ogallala and Arikaree aquifers in the Rosebud 

Indian Reservation area. This report also describes a 

conceptual model used in developing the numerical 

ground-water flow model of the aquifers. Steady-state 

and transient simulations performed for the 20-year 

period of water years (WY) 1979-98 (October 1, 1978, 

through September 30, 1998) are described in this 

report.

Acknowledgments

The authors would like to recognize important 

contributions by the Rosebud Sioux Tribe to the 

development of the ground-water flow model described 

in this report. Development of a calibrated numerical 

model has resulted from the Tribe's long-term commitment to obtaining hydrologic information, which has 

been obtained through a series of water-resource investigations that the Tribe has participated in and by datacollection networks operated or supported by the Tribe. 

Characterization of the Ogallala and Arikaree aquifers 

was enabled by a substantial program of test-hole 

drilling and installation of observation wells that was a 

major component of a water-resource investigation 

(Carter, 1998) involving the Tribe, USGS, and Geological Survey Program of the South Dakota Department 

of Environment and Natural Resources. Water-level 

data from the resulting network of observation wells 

and from other State and Tribal observation wells have 

been instrumental for calibration of the numerical 

model. Tribal support and involvement in collection of 

streamflow data has been critical for estimation of 

ground-water discharge rates. The Tribe also was 

actively involved in study design, conceptualization of 

the ground-water flow system, technical evaluation of 

model performance, and review of this completion 

report.
Description of Study Area 3

DESCRIPTION OF STUDY AREA

The study area includes areas within and immediately surrounding the Rosebud Indian Reservation 

where the Ogallala and Arikaree aquifers are present 

(fig. 1). The original boundaries of the Rosebud Indian 

Reservation included all or nearly all of Mellette, Todd, 

Tripp, and Gregory (east of Tripp) Counties, and a 

small portion of Lyman County (east of northern Tripp 

County). Various revisions to the Rosebud Indian 

Reservation boundary have occurred; the boundary was 

revised to include only Todd County in 1975 (fig. 1).

Physiography, Land Use, and Climate

Much of the study area has rolling topography, 

and numerous deep valleys drain into the White River 

to the north. The northern portion of the study area is in 

the Great Plains physiographic province, and the 

southern portion is in the Sand Hills physiographic 

province (fig. 1).

Agriculture is the primary land use within the 

study area. Cattle ranching is the primary agricultural 

activity, with most land used for grazing or hay production. Less than 15 percent of the land is used for crops, 

which include wheat, sorghum, oats, corn, and alfalfa 

(Springer, 1974). Most of the crop land is located in 

south-central Todd County, where extensive irrigation 

from the Ogallala aquifer occurs.

The climate is subhumid, and the average annual 

precipitation (1961-1990) is about 19 inches (U.S. 

Department of Commerce, 1998). About 8 percent of 

the average annual precipitation becomes streamflow; 

however, this quantity varies due to climatic conditions 

(Carter, 1998).

Drainage Features and Streamflow

The major streams that drain the study area 

(fig. 2) are the Little White River, which flows into the 

White River in northern Mellette County, and the Keya 

Paha River, which flows into the Niobrara River in 

Nebraska. Some of the smaller streams include Black 

Pipe, White Thunder, Oak, and Minnechaduza Creeks.

Ground-water discharge from the Ogallala and 

Arikaree aquifers provides base flow to the Little White 

River, Keya Paha River, and Minnechaduza Creek. 

These streams generally receive more than one-half of 

their flow from ground-water discharge, especially 

during the winter months (Carter, 1998). Direct runoff 

is the largest component of streamflow for streams 

with minimal discharge from the Ogallala and 

Arikaree aquifers. In addition, numerous ephemeral 

springs occur along the Little White River.

Geology

The exposed rocks and sediments in the study 

area range from sedimentary rocks of Cretaceous age 

to unconsolidated deposits of Quaternary age. Deeper 

rocks include rocks of Precambrian age, the Ordovician-age Winnipeg and Red River Formations, the 

Mississippian-age Madison Limestone, and the 

Pennsylvanian- and Permian-age Minnelusa Formation. Cretaceous-age rocks include the Inyan Kara 

Group, Skull Creek Shale, Dakota Formation, 

Graneros Shale, Greenhorn Formation, Carlile Shale, 

Niobrara Formation, and Pierre Shale. Tertiary-age 

rocks include the White River Group, Arikaree 

Formation, and Ogallala Formation. Unconsolidated 

deposits include windblown, terrace, and alluvial 

deposits (table 1). The following descriptions of the 

Arikaree and Ogallala Formations are from Ellis and 

others (1971).

The Arikaree Formation consists of silicified 

claystone, silty clays, siltstone, and poorly consolidated sandstone, all of which are a light pinkish-tan. 

The basal 50 to 150 feet usually is composed of silty 

and sandy beds that commonly are separated from the 

upper clayey part by 5 to 10 feet of thin-bedded limestone. Thickness of the Arikaree Formation ranges 

from 0 to 620 feet. The Arikaree Formation forms 

gently rolling grass-covered hills similar to those 

formed by the Ogallala Formation, but the banks 

formed by the Arikaree Formation along streams 

usually are steeper.

The Ogallala Formation consists of an upper 

unit composed of well-cemented, fine-grained sandstone and a lower unit composed of poorly consolidated clay, silt, and sand. The contact between the 

units commonly is marked by a bed of silty volcanic 

ash in the base of the upper unit. This marker bed 

ranges in thickness from 1 to 4 feet. Locally, however, 

silty limestone or gravel beds may be found at the base 

of the upper unit. The composition of the beds in the 

lower unit ranges from silty clay to coarse sand and 

varies both vertically and horizontally. A 5- to 20-

foot-thick bed of coarse sand and gravel commonly
4 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 1. Study area and locations of main physiographic divisions (physiographic divisions modified from Fenneman,

1946; Flint, 1955).

Black

Hills

Sand

Hills

Central

Lowland

Great

Plains

PHYSIOGRAPHIC DIVISIONS

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Mission Antelope

Rosebud

Olsonville

Blackpipe

St. Francis

Norris

83

83

18

18

Little

White

Keya Paha

River

River

South

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Thunder

Creek

White

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

North

Pine

Branch

Branch

Creek

Creek

Minnechaduza

Creek

Dry

Creek

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

SOUTH DAKOTA

Study

Area

Missouri

River

Todd

County

Mellette County

EXPLANATION

ROSEBUD INDIAN RESERVATION
Description of Study Area 5

Figure 2. Drainage basins in study area.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Mission Antelope

Rosebud

Blackpipe

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood

Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

Little White River Little White River

Keya Paha River Keya Paha River

Minnechadu Minnechaduza

Creek

White

Thunder Thunder

Creek

Black

Pipe

Creek

Little

Dog

Creek

Oak

Creek

Little White River

Keya Paha River

Minnechaduza

Creek

White

Thunder

Creek

Black

Pipe

Creek

Little

Dog

Creek

Oak

Creek

Louis Creek Louis Creek ouis Creek

White River Basin White River Basin

Niobrara River Basin Niobrara River Basin

White River Basin

Niobrara River Basin

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

EXPLANATION

DRAINAGE BASIN

DRAINAGE SUBBASIN
6 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak. Table 1. Generalized stratigraphic column showing geologic units and hydrologic characteristics [From Carter, 1998] Era System Formation or deposit Thickness (feet) Description and origin Hydrologic characteristics

Cenozoic

Quaternary

Alluvium 0-35 Brown, varies between clay, silts, fine to coarse sand, and 

gravel. Generally sandy along the Little White River and other streams that flow over deposits of Tertiary age. Generally clayey with some thin sand beds along intermittent streams that flow over the Pierre Shale. Fluvial.

Locally, deposits are moderately permeable along the Little 

White River and relatively impermeable along streams that flow over the Pierre Shale. Yields generally are adequate to supply domestic and stock wells except along streams that flow over the Pierre Shale. Water is fresh, low in concentrations of dissolved solids, and soft to moderately hard except in deposits underlain by the Pierre Shale.

Windblown sand 

deposits

0-150 Brown, unconsolidated, very fine to medium grained, 

uniform, quartz sand; characterized by dune topography and blowouts. Eolian.

Generally very permeable and water bearing; yields are 

adequate to supply stock and domestic wells except where deposits are small.

Terrace deposits 0-105 Brown, silty clay, sand, and gravel. Commonly, the silty and 

sandy layers are partly cemented, and the gravel and sand beds commonly are interbedded with laminated silty clay. Fluvial.

Generally water bearing in the basal portion of the deposits. 

Yields are usually adequate to supply stock and domestic wells. Water is fresh, low in concentrations of dissolved solids, and soft to moderately hard except in areas where the water-bearing deposits are underlain by the Pierre Shale.

Tertiary

Ogallala Formation 0-240 Tan to olive, fine- to medium-grained sandstone with some 

silty clay. Upper unit of Ogallala Formation also is known as the Ash Hollow Formation and the lower unit as the Valentine Formation. Fluvial.

The upper part of the formation generally has low 

permeability, but small seeps occur near its base. The lower part of the formation can be very permeable and generally is water-bearing; yields are adequate to supply stock and domestic wells and can supply irrigation wells in some areas. Water is fresh, low in concentrations of dissolved solids, and soft to moderately hard.

Arikaree Formation 0-620 Pinkish tan to red; consists of poorly consolidated, tuffaceous 

sandstone, siltstone, shale, and silty clay. The Rosebud Formation sometimes is differentiated as a unit within the Arikaree Formation. Basal unit is composed mostly of silts and sands. Fluvial.

The upper part of the formation generally has low 

permeability, but can yield small amounts of water from fractures, joints, and silty layers. The basal part is moderately permeable and can supply water for domestic and stock wells. Water is fresh, low in concentrations of dissolved solids, and soft to moderately hard.

White River Group 

(undifferentiated)

0-470 Yellow to brown, poorly consolidated siltstone and claystone 

with some beds of fine sand. Units of the White River Group sometimes are differentiated into the Brule and Chadron Formations. Fluvial.

Permeability varies from low to moderate, depending on the 

clay content. Yields are usually adequate to supply water to stock and domestic wells. Water is slightly saline, moderate in concentrations of dissolved solids, and hard depending on the proximity of the aquifer to the Pierre Shale.
Description of Study Area 7

Mesozoic

Cretaceous

Pierre Shale 600-1,395 Bluish-black shale with some layers of bentonite. Marine. Most of the formation is relatively impermeable. Can yield 

small amounts of water if fractures or sandy zones are present. Typically not considered an aquifer. Water is saline, high in concentrations of dissolved solids, and very hard.

Niobrara Formation 125-175 Tan to gray, highly calcareous shale. Commonly described by 

drillers as “chalk.” Marine.

Water-bearing traits are largely unknown. May yield 

sufficient water for some purposes.

Carlile Shale 300-400 Light grayish blue to black, noncalcareous shale. Marine. Very low permeability. Water-bearing traits are largely 

unknown.

Greenhorn Formation 100-120 Tan, bluish, white, or gray calcareous shale. Marine. Water-bearing traits are largely unknown.Graneros Shale 130-200 Dark-gray non-calcareous shale. Marine. Very low permeability. Water-bearing traits are largely 

unknown.

Dakota Formation 

(Dakota Sandstone)

270-340 Interbedded tan to white sandstone and dark-colored shale. 

Sandstone is composed of loose to well-cemented, very fine to coarse quartz sand; cement most commonly is calcium carbonate. Marine.

Permeable sandstone beds yield moderate quantities of water 

under artesian pressure for stock and domestic wells. The water is highly mineralized and cannot be used for irrigation purposes.

Skull Creek Shale 95-150 Dark bluish-gray shale. Marine. Very low permeability. Water-bearing traits are largely 

unknown.

Inyan Kara Group 

(undifferentiated)

100-275 White to light-gray or tan sandstone and siltstone; contains 

beds of gray to black and reddish to buff shale. The Inyan Kara Group sometimes is divided into the Fall River and Lakota Formations. Continental to marginal marine.

Permeable sandstone beds yield moderate quantities of water 

under artesian pressure for stock and domestic wells. The water is highly mineralized and cannot be used for irrigation purposes.

Paleozoic

Permian and

PennsylvanianMinnelusa Formation 300-530 Consists of interbedded sandstone, siltstone, dolomite, limestone, anhydrite, and shale. Marine. Permeable zones can yield adequate water for stock and domestic wells under artesian pressure. Water is lower in dissolved solids than the Dakota Sandstone and Inyan Kara aquifers. Can be used for irrigation on crops that are tolerant of salt with proper salinity management.

MississippianMadison Formation 90-240 Light gray to buff, varies from pure limestone to pure dolomite with various combinations of the two. Marine. Permeable zones can yield adequate water for stock and domestic wells under artesian pressure. Water is lower in dissolved solids than the Dakota Sandstone and Inyan Kara aquifers. Can be used for irrigation on crops that are tolerant of salt with proper salinity management. Ordovician Red River and Winnipeg Formations (undifferentiated) 0-170 The Red River Formation mostly consists of dolomite, and the Winnipeg Formation mostly consists of sandstones. Marine. Water-bearing traits largely unknown. Not used as an aquifer in vicinity of study area.

Precambrian Granite. Water-bearing traits largely unknown. Not used as an aquifer 

in vicinity of study area.
8 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

occurs in the basal part of the lower unit. Thickness of 

the upper unit ranges from 0 to 40 feet and the lower 

unit ranges from 0 to 200 feet. The upper unit forms the 

caprock on the isolated buttes and ridges in the southeastern and northwestern parts of Todd County. The 

lower unit forms the gently rolling grasslands in southcentral Todd County. The upper unit of the Ogallala 

Formation also is known as the Ash Hollow Formation, 

and the lower unit also is known as the Valentine 

Formation.

Hydrogeologic Setting

The shallow aquifers in the study area are the 

alluvial, Ogallala, Arikaree, and White River aquifers. 

These shallow aquifers consist primarily of unconsolidated sand and gravel or poorly consolidated sandstones and siltstones. The deeper, bedrock aquifers are 

the Pierre, Dakota Sandstone, Inyan Kara, Minnelusa, 

and Madison aquifers. In the southern part of the study 

area, ground water generally can be obtained from 

shallow wells (less than 300 feet) completed either in 

Quaternary-age alluvial deposits or in Tertiary-age 

deposits (Ogallala Formation, Arikaree Formation, or 

White River Group). Ground water is more difficult to 

obtain in the northern part of the study area where the 

Tertiary deposits have been eroded resulting in surface 

exposure of the Pierre Shale (fig. 3). 

The Ogallala aquifer comprises the saturated 

sandstones and silt of the Ogallala Formation. The 

upper unit of the Ogallala Formation has relatively low 

permeability, but small seeps occur near its base (Ellis 

and others, 1971). The lower unit of the Ogallala Formation generally is water bearing; however, the permeability of that unit varies with lithology (Ellis and 

others, 1971).

The Ogallala aquifer is present throughout most 

of the southern part of the study area, where it underlies 

950 square miles in Todd County with an estimated 17 

million acre-feet of water in storage (Carter, 1998). The 

Ogallala aquifer is not present in the northern part of 

the study area. The saturated thickness of the Ogallala 

aquifer in the study area averages 137 feet (Carter, 

1998), and the aquifer is fully saturated in some areas. 

In the study area, the aquifer generally is thickest in the 

central portion of Todd County, where withdrawals 

from the aquifer for irrigation are highest. The Ogallala 

aquifer is overlain by unconsolidated deposits consisting of alluvium and windblown sand in the southwestern part of the study area (fig. 3).

The Ogallala aquifer is unconfined except in the 

southwestern part of the study area where the aquifer is 

confined by well-cemented or concretion beds in the 

upper part of the formation (Carter, 1998). Where 

unconfined, the depth to water ranges from 0 to greater 

than 150 feet below land surface (Carter, 1998). In 

some areas, the water table in the Ogallala aquifer can 

be considerably above the altitude of stream bottoms, 

and numerous seeps occur along hillsides and cliffs in 

these areas. The Ogallala aquifer has the highest yield 

potential of all aquifers in the study area with wells 

yielding from 1 to 1,250 gallons per minute (Carter, 

1998).

The Arikaree aquifer generally comprises the 

saturated sandstones and siltstones of the Arikaree Formation. The Arikaree Formation underlies the Ogallala 

aquifer, where present, everywhere in the study area 

except in the extreme eastern part of Todd County 

where the Arikaree Formation does not exist. Beds in 

the upper clayey part of the Arikaree Formation are 

composed of relatively low-permeability material, but 

generally yield water from fractures, joints, and thin 

silty zones (Ellis and others, 1971). The basal sandy 

and silty part of the formation is moderately permeable 

(Ellis and others, 1971). 

The Arikaree aquifer underlies 1,360 square 

miles in Todd and Mellette Counties with an estimated 

50 million acre-feet of water in storage (Carter, 1998). 

The thickness of the Arikaree aquifer ranges from 0 to 

618 feet, with an average of 290 feet (Carter, 1998). In 

the study area, the Arikaree aquifer is thickest in 

southern Todd County.

The Arikaree aquifer generally is confined where 

overlain by less permeable materials in the lower part 

of the Ogallala Formation, and the lower part of the 

Arikaree aquifer can be confined where low-permeability material occurs in the upper part of the aquifer. 

Hydraulic heads in the aquifer generally are within 

60 feet below land surface under confined conditions, 

and range from 0 to greater than 150 feet under unconfined conditions (Carter, 1998). Like the Ogallala 

aquifer, the water table in the Arikaree aquifer can be 

considerably higher in some areas than the altitude of 

stream bottoms, and numerous seeps occur along hillsides and cliffs in these areas. Well yields range from 1 

to 1,005 gallons per minute depending on clay content 

in the aquifer, consolidation of the materials, and well 

construction; yields generally are less than those from 

the Ogallala aquifer but are substantially greater than 

yields from the underlying White River aquifer (Carter, 

1998). 
Description of Study Area 9

Figure 3. Generalized geologic map showing surficial geology of study area (modified from Ellis and others, 1971).

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Mission Antelope

Rosebud

Blackpipe

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

QUATERNARY-AGE UNCONSOLIDATED DEPOSITS

Alluvium and terrace deposits

Windblown sand deposits

EXPLANATION

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

CRETACEOUS-AGE SEDIMENTARY DEPOSITS

Kp Pierre Shale

Kp Kp

Kp

Qwd

Qwd

Qwd

TERTIARY-AGE SEDIMENTARY DEPOSITS

Ogallala Formation

Arikaree Formation

To

To To

To

Ta

Ta Ta

Ta

Tw White River Group

Tw

Tw

Tw
10 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

SIMULATED GROUND-WATER FLOW

A conceptual model of the Ogallala and Arikaree 

aquifers was used to analyze ground-water flow and to 

develop a numerical model to simulate ground-water 

flow in the aquifers. Steady-state and transient simulations were done with the numerical model. For transient simulations, a 20-year period (1979-98) was 

subdivided into 60 stress periods.

Conceptual Model

The conceptual model includes the potentiometric surface, hydraulic properties, and recharge and 

discharge components. The conceptual model and simplifying assumptions are discussed in this section.

The windblown deposits overlying the Ogallala 

aquifer in the southwest part of the study area are composed of fine- to medium-grained sand, similar to that 

of the Ogallala Formation, and were included with the 

Ogallala aquifer as a single layer for ground-water flow 

analysis. The Ogallala and Arikaree aquifers were 

assumed to be hydraulically connected. The White 

River Group contains an aquifer but was considered an 

underlying confining unit because of numerous clay 

lenses that impede vertical ground-water movement. 

Areal recharge to the Ogallala and Arikaree 

aquifers occurs from precipitation on the outcrop areas, 

and regional flow enters the study area from the west. 

Ground water from areal recharge moves from areas of 

higher altitude toward streams that gain flow from the 

Ogallala and Arikaree aquifers. Discharge by evapotranspiration from the aquifers occurs in areas where 

the water table is near the land surface, which generally 

occurs in topographically low areas. Many of the 

springs that discharge along the banks of the Little 

White and Keya Paha Rivers probably flow from the 

Ogallala aquifer because the Arikaree aquifer generally 

has lower permeability than the Ogallala aquifer. The 

Arikaree aquifer discharges to springs and seeps on the 

northern boundary of the aquifer where the surface 

drainage is towards the north. In addition, discharge 

from the aquifers occurs through withdrawals from 

irrigation, domestic, and stock wells.

For analysis of ground-water flow, data for a 

twenty-year period (WY 1979-98) were analyzed. Each 

water year was subdivided into three periods (hereinafter referred to as stress periods) for a total of 60 stress 

periods for analysis based on the hydrologic characteristics of each period: (1) a fall and winter period, which 

included the months of October through February; (2) 

a spring period, which included the months of March 

through May; and (3) a summer period which included 

the months of June through September. The 60 stress 

periods are numbered 1 through 60 starting with the fall 

and winter period of WY 1979. For example, fall and 

winter of WY 1979 is stress period 1, spring of WY 

1979 is stress period 2, and summer of WY 1979 is 

stress period 3. During most of the fall and winter 

period, evapotranspiration is very small because the 

ground is frozen, plant growth is limited, and precipitation is less than in the spring or summer periods. 

During the spring period, precipitation is greater than 

during the fall and winter period, and the evapotranspiration rate is less than during the summer period. 

During the summer period, evapotranspiration is 

greatest and irrigation withdrawals are largest. 

Potentiometric Surface

Average potentiometric surfaces were estimated 

for the analysis period (WY 1979-98) for the Ogallala 

and Arikaree aquifers (figs. 4 and 5, respectively) for 

calibration of the steady-state model. Boundaries of the 

aquifers were modified from Carter (1998) to represent 

areas with sufficient saturation for inclusion in the 

numerical model. The parts of the aquifers not included 

were areas where saturation was intermittent or that 

generally had less than 10 feet of saturation. Water 

levels during 1996 were documented by Carter (1998) 

for wells completed in the Ogallala and Arikaree aquifers. Long-term water-level records are available for 17 

observation wells completed in the Ogallala aquifer 

and 6 observations wells completed in the Arikaree 

aquifer that are maintained by the South Dakota 

Department of Environment and Natural Resources 

(State observation wells). During the 20-year period, 

some of the water levels for wells with long-term 

records increased, some decreased, and some changed 

very little. Water levels changed as much as about 

6 feet for the Ogallala aquifer and 12 feet for the 

Arikaree aquifer. These water levels generally fluctuate 

between 1 and 4 feet seasonally.
Simulated Ground-Water Flow 11

Figure 4. Estimated average potentiometric surface of the Ogallala aquifer (modified from Carter, 1998).

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Mission Antelope

Rosebud

Blackpipe

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

2,700

2,700

2,650

2,750 2,600

2,800

2,800

2,900

2,950

2,550

2,500

3,000

2,450

2,400

3,050

2,850

2,850

2750

2,500

2,500 2,450

2,450

2,900

2,900

3,050

2,800

3,000

2,850

2,500

2,750 2,700

2,550

2,550

2,400

2,400

2,800

,,

2,623

2,686 2,607

2,514

2,753 2,669 2,707

2,579 2,677

2,467

2,601

2,665

2,819

2,773

2,756

2,819

2,815

2,785

2,821

2,809

2,843

2,848

2,823

2,916

2,947

2,742 2,803

2,812

2,768

2,732

2,750

2,729

2,791 2,740

2,662

2,601

2,467

2,711

2,778

2,594

2,660

2,815

2,850

!

! !

! !

! ! !

!

!

! ! !

!

!

!

!

!

!

! ! !

!

!

! ! ! ! !

! ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

2,489

2,623

2,434 2,666

2,576 2,678

3,032 2,893 2,785 2,709 2,650

2,744 2,623 3,035 2,850 2,815 2,831 2,913 2,705 2,573 2,698,

2,686

2,496

2,711 2,619 2,818

2,975 2,496

2,875 2,780

2658 2,832 2,791 2,821

2,927 2,628 2,809 2,603 2,510

2,679 2,834 2,829 2,607

2,810 2,660

2,850 2,794

2,836 2,849 2,818 2,530 2,856 2,723

2,823 2,514

2,819

2,854 2,526 2,843 2,773

2,832 2,801 2,756 2,851 2,608

2,811 2,845 2,613 2,858

2,831 2,543

2,665

2,848

2,821 2,622 2,815

2,855 2,871 2,866 2,779 2,753 2,850 2,823

2,916 2,669 2,827

2,839

2,890 2,817 2,7932,764 2,421

2,850 2,707

2,778 2,804 2,579

2,602 2,816 2,7832,740 2,872 2,785 2,677

2,801 2,778 2,777 2,895 2,768

2,742 2,662 2,803 2,882

2,584 2,812 2,810 2,882 2,876 2,772 2,646

2,714 2,605 2,766

2,955

2,768

2,757 2,755 2,732

2,762

2,716 2,876 2,740 2,386

2,947

3,0323,009 2,466 2,960 2,818 2,750

2,729 2,504

2,467 2,406

2,647

2,743 2,601

2,804

2,837

2,594

2,834

2,843 2,822

2,816

2,750 2,817

2,791 2,727 2,745

2,727

2,790

2,930 2,754

2,902

2,918

A A'

2,815 2,725

2,865

2,811

2,660

2,600

2,589

2,792

2,671

!

!

! !

!

!

! !

!

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

EXPLANATION

AREA OF THE OGALLALA AQUIFER CONSIDERED

POTENTIOMETRIC CONTOUR—Shows average altitude

 at which water level would have stood in tightly cased

 wells, 1979-98. Contour interval is 50 feet. Datum is

 NGVD of 1929.

WATER WELL—Number is estimated average hydraulic head

 for water years 1979-98, in feet above NGVD of 1929

LINE OF GEOLOGIC SECTION (figure 6)

2,400

!

2,804

A

A'

GENERAL DIRECTION OF GROUND-WATER FLOW
12 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 5. Estimated average potentiometric surface of the Arikaree aquifer (modified from Carter, 1998).

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Mission Antelope

Rosebud

Olsonville

Blackpipe

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

2,550

2,600

2,600

2,650

2,650

2,700

2,700

2,750

2,750

2,800

2,800

2,800

2,500

2,850

2,900

2,950

3,050

3,000

2,450

3,050

2,400

2,500

2,500

2,550

2,600

2,550

2,850

2,850

2,400

2,500

2,500

2,800

3,000

2,900

2,450

2,450

2,450

2,843

2,931

2,488

2,668 2,851 2,565

2,783

2,831

2,611

2,569

2,824 2,558 2,673 2,593 2,812 2,783 2,558

2,719 2,513

2,646

2,660

2,842 2,550

2,614

2,673

2,546 2,628 2,525

2,712 2,645

2,860 2,534 2,447 2,820

2,722 2,734 2,856

2,674 2,736 2,498 2,642

2,428

2,597

2,614 2,631 2,395

2,521

2,667

2,511

2,603 2,734

2,781

2824 2,533 2,839 2,802 2,522

2,359 2,737

2,442 2,495 2,557

2,753 2,548 2,418 2,609 2,876 2,639 2,453 2,789

2,472

2,466

2,792 2,537

2,498 2,604 2,526 2,347

2,740

2,718 2,401 2,451 2,351 2,373

2,582 2,694 2,506 2,394

2,414 2,716

2,341

2,701 2,413

2,477 2,736 2,437 2,540 2,926 2,605 2,708 2,609

2,624 2,573 2,645 2,476 2,388 2,417 2,507

2,724

2,670 2,563 2,416

2,686 2,627 2,827 2,638 2,505 2,657 2,539

2,431 2,453 2,639 2,505 2,699 2,907 2,878 2650 2,670

2,688 2,782 2,610

2,732 2,416 2,632 2,587 2,529 2,486 2,553 2,468

2,931 2,716

2,841 2,606

2,474

2,492 2,656 2,497

2,502 2,681 2,489 2,457

2,536 2477 2,521

2,513

2,597 2,625

2,601 2,671 2,534 2,629 2,648 2,543 2,646 2,646 2,552 2,587 2,505

2,471

2,599

2,603 2,645 2,768

2,568 2,626 2,625 2,615 2,609

2,469 2,583 2,545 2,585

2,616

2,525

2,506

2,600

2,639 2,482 2510 2,517

2,585 2,479 2,449 2,469

2,686

2,686 2,600

2,586 2,543 2,570

2,523

2,516

2,781 2,523

2,458

2,764

2,578

2,561

2,832

2,586

!

!

!

!

!

!

!

!

! ! ! !

! !

!

!

! !

! ! ! ! ! ! ! !

! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! ! ! ! !

! ! ! !

! ! ! ! !

! ! !

! !

! ! ! !

! ! ! ! !

! ! ! ! ! ! ! ! ! !

!

! 2,843

2,931

2,488

2,668 2,851 2,565

2,783

2,831

2,611

2,569

2,824 2,558 2,673 2,593 2,812 2,783 2,558

2,719 2,513

2,646

2,660

2,842 2,550

2,614

2,673

2,546 2,628 2,525

2,712 2,645

2,860 2,534 2,447 2,820

2,722 2,734 2,856

2,674 2,736 2,498 2,642

2,428

2,597

2,614 2,631 2,395

2,521

2,667

2,511

2,603 2,734

2,781

2824 2,533 2,839 2,802 2,522

2,359 2,737

2,442 2,495 2,557

2,753 2,548 2,418 2,609 2,876 2,639 2,453 2,789

2,472

2,466

2,792 2,537

2,498 2,604 2,526 2,347

2,740

2,718 2,401 2,451 2,351 2,373

2,582 2,694 2,506 2,394

2,414 2,716

2,341

2,701 2,413

2,477 2,736 2,437 2,540 2,926 2,605 2,708 2,609

2,624 2,573 2,645 2,476 2,388 2,417 2,507

2,724

2,670 2,563 2,416

2,686 2,627 2,827 2,638 2,505 2,657 2,539

2,431 2,453 2,639 2,505 2,699 2,907 2,878 2650 2,670

2,688 2,782 2,610

2,732 2,416 2,632 2,587 2,529 2,486 2,553 2,468

2,931 2,716

2,841 2,606

2,474

2,492 2,656 2,497

2,502 2,681 2,489 2,457

2,536 2477 2,521

2,513

2,597 2,625

2,601 2,671 2,534 2,629 2,648 2,543 2,646 2,646 2,552 2,587 2,505

2,471

2,599

2,603 2,645 2,768

2,568 2,626 2,625 2,615 2,609

2,469 2,583 2,545 2,585

2,616

2,525

2,506

2,600

2,639 2,482 2510 2,517

2,585 2,479 2,449 2,469

2,470 2,686

2,686 2,600

2,586 2,543 2,570

2,523

2,516

2,781 2,523

2,458

2,764

2,578

2,561

2,832

2,586

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

EXPLANATION

AREA OF THE ARIKAREE AQUIFER CONSIDERED

WATER WELL—Number is estimated average hydraulic head

 for water years 1979-98, in feet above NGVD of 1929

LINE OF GEOLOGIC SECTION (figure 6)

2,800

!

2,824

A

A'

A' A'

GENERAL DIRECTION OF GROUND-WATER FLOW

POTENTIOMETRIC CONTOUR—Shows average altitude

 at which water level would have stood in tightly cased

 wells, 1979-98. Contour interval is 50 feet. Datum is

 NGVD of 1929.
Conceptual Model 13

For the wells with long-term records, average 

water levels for the 20-year period were calculated, and 

the difference between the 20-year average water level 

and the 1996 water level was calculated for each well. 

The calculated differences for the Ogallala aquifer 

ranged from -1.9 to 4.1 feet with a mean difference for 

the 17 wells of -1.0 foot. The difference was positive at 

only four of the 16 wells located in the southeastern, 

south-central, and northwestern parts of the study area. 

The calculated differences for the Arikaree aquifer 

ranged from -5.7 to 4.9 feet with a mean difference for 

the six wells of -1.8 ft. The difference was positive at 

only one of the seven wells located in the south-central 

part of the study area. A continuous surface was interpolated from these differences using an inversedistance-weighting method. Single water-level measurements made during 1996 at 398 water wells were 

adjusted to an average for the 20-year period by adding 

the value of the interpolated difference surface at each 

well’s location to obtain an estimated water-level 

altitude. 

These estimated and calculated average waterlevel altitudes for 398 wells were used as control points 

to construct the estimated average potentiometric surfaces. Because the estimated average water levels are 

generally based on only one measurement and the longterm records of nearby observation wells, the estimates 

do not necessarily represent accurate average values; 

however, because water-level fluctuations at observation wells were relatively small, potential errors in these 

estimates also are small. In addition, the accuracy of the 

estimated average potentiometric surface decreases 

with distance from control points. Average hydraulic 

heads for the wells used as control points are listed in 

tables 15 and 16, in the “Supplemental Information” 

section at the end of this report. Surface-water altitudes 

for perennial stream reaches also were used as control 

points.

Ground-water flow in both the Ogallala and 

Arikaree aquifers in the study area generally is to the 

east or northeast. Locally, ground-water flow is topographically controlled and is towards the Little White 

River, Keya Paha River, and associated tributaries 

(figs. 4 and 5). Ground water flows from recharge areas 

towards streams and topographically low areas where 

discharge occurs as base flow to streams or evapotranspiration. The relation between hydraulic heads and 

topographic features (fig. 6) shows the local influence 

of streams on the general northeasterly direction of 

ground-water flow. In particular, the Little White River, 

which is deeply incised into the Ogallala aquifer and 

to a lesser extent into the Arikaree aquifer, strongly 

influences ground-water flow. The Keya Paha River is 

hydraulically connected to the Arikaree aquifer 

(fig. 3), and tributary streams gain water from the 

Ogallala aquifer. A comparison of the surfacedrainage basins (fig. 2) and the potentiometric surfaces (figs. 4 and 5) shows that ground-water divides 

are related to the surface-drainage basins. 

Hydraulic head in the Ogallala aquifer ranges 

from about 3,000 feet on the western boundary of the 

study area to about 2,400 feet on the eastern boundary 

(fig. 4). To the east of the Little White River, groundwater flow is northwesterly toward the river from 

topographically higher areas. In the south-central portion of the study area, ground-water flow is southerly 

toward streams flowing into Nebraska. In the northeastern portion of the study area, ground-water flow is 

towards the Keya Paha River. In a small area in the 

northeastern part of the study area, ground water flows 

northerly from the topographic ridge. 

Hydraulic head in the Arikaree aquifer ranges 

from about 3,000 feet on the western and southwestern boundary of the study area to about 2,400 feet 

on the northeastern boundary of the aquifer (fig. 5). 

Ground-water flow in the Arikaree aquifer is similar 

to flow in the Ogallala aquifer in areas where the 

Arikaree aquifer is overlain by the Ogallala aquifer. 

Ground-water flow in the northern portion of the study 

area, where the Arikaree Formation is exposed, is 

northerly following the topography. 

Hydraulic Properties

Hydraulic properties of the Ogallala and 

Arikaree aquifers in and near the study area have been 

estimated by previous investigators (table 2). For the 

High Plains aquifer, hydraulic conductivities in southcentral South Dakota, estimated from 205 well logs, 

ranged from 3.6 to 160 feet per day, with an average of 

30 feet per day (Kolm and Case, 1983).

For the Ogallala aquifer, hydraulic conductivities determined from aquifer tests in south-central 

Todd County ranged from 7.9 to 21.6 feet per day, and 

specific yields ranged from 0.02 to 0.03 (KremlinSmith, 1984). Hydraulic conductivities estimated 

from specific capacity data for 21 wells ranged from 

1.2 to 25.2 feet per day (Kremlin-Smith, 1984).
14 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 6. Relation between average hydraulic head, hydrogeologic units, and topographic features. Location of section is shown in figures 4 and 5. This sectionshows an area (1) of intermittent saturation, which is not included in the area of the Ogallala aquifer considered in figure 4.

Ogallala aquifer

Arikaree aquifer

Eagle Creek

Antelope Creek

Rock Creek

Keya Paha River

Little White River

White River Group

A A'

FEET

3,2003,0002,8002,6002,4002,200

2,000

FEET

3,2003,0002,8002,6002,4002,200

2,000

AVERAGE HYDRAULIC HEAD IN OGALLALA AQUIFER, WATER YEARS 1979-98

AVERAGE HYDRAULIC HEAD IN ARIKAREE AQUIFER, WATER YEARS 1979-98

VERTICAL SCALE IS GREATLY EXAGGERATEDVERTICAL DATUM IS NGVD OF 1929

Tops of hydrogeologic units modified from Carter (1998)

EXPLANATION

0 12 3 4 MILES01234 KILOMETERS

(1)

GENERAL DIRECTION OF GROUND-WATER FLOW
Conceptual Model 15

Table 2. Previously published hydraulic properties within or near the study area

[ft2/d, feet squared per day; ft/d, feet per day; --, no data]

Method In study

area

Transmissivity

(ft2/d)

Hydraulic

 conductivity

 (ft/d)

Storage

coefficient

(dimensionless)

Specific

yield

(dimensionless)

Location Source

Ogallala Aquifer

Time drawdown

aquifer test

Yes 7,005 170

1

Calculated from transmissivity based on saturated thickness of 100 feet.

2.6x10-3 0.057 36N32W22 Rahn and Paul, 1975

Distance drawdown 

aquifer test

Yes 3,234 132 5.5x10-2 -- 36N32W22 Rahn and Paul, 1975

Aquifer test Yes 2,995 21.6 -- 0.02 37N29W31CCA Kremlin-Smith, 1984

Aquifer test Yes 1,644 7.9 -- 0.03 36N29W14CAC Kremlin-Smith, 1984

Aquifer test Yes 3,088 17.5 -- 0.02 37N29W 8ABB Kremlin-Smith, 1984

Specific capacity Yes 180-3,476 1.2-25.2 -- -- Todd County Kremlin-Smith, 1984

Specific capacity Yes 2-2,400

Average 600

-- -- -- Todd County Carter, 1998

Unknown No 800-9,200

Average 

2,800

-- -- -- 16 wells to the 

south and east of 

Todd County 

within 100 miles 

of Todd County

Newport, 1959

Arikaree Aquifer

Specific capacity Yes 2-2,000

Average 90

-- -- -- Todd County Carter, 1998

Aquifer test No 1,250 13 7.0x10-3 0.03 Shannon County 

35N44W17

Greene and others, 

1991

Aquifer test No 300 1 3.0x10-4 -- Shannon County 

35N44W17

Greene and others, 

1991

Aquifer test No 310 1.0 3.9x10-4 -- Shannon County 

35N44W

Sipe, 1989

Time drawdown

(single well)

No 298 1.0 3.9x10-4 -- Shannon County 

35N44W

Sipe, 1989

Time recovery

(single well)

No 326 1.0 -- -- Shannon County 

35N44W

Sipe, 1989

Core sample No -- 2 -- -- Sioux County, 

Nebraska

28N55W6

Bradley, 1956

High Plains Aquifer2

2

Includes Ogallala aquifer and upper Arikaree aquifer.

Grain size descriptions Yes -- 3.6-160

Average 30

-- 0-0.25 Todd County Kolm and Case, 1983
16 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Based on aquifers tests of the Arikaree aquifer 

near Pine Ridge, South Dakota (located about 70 miles 

west of the study area), Sipe (1989) estimated hydraulic 

conductivity to be 1.0 foot per day and storage coefficient to be 3.9x10-4. Greene and others (1991) reported 

aquifer tests in two of the sandier units of the Arikaree 

aquifer near Pine Ridge. Hydraulic properties determined for an upper unconfined unit composed of fine to 

medium sand include hydraulic conductivity of 13 feet 

per day, storage coefficient of 7x10-3, and specific yield 

of 0.03. Hydraulic properties determined for a lower 

confined unit composed of fine to very fine sand 

include hydraulic conductivity of 1 foot per day and 

storage coefficient of 3x10-4. The hydraulic conductivity of a core sample from the Arikaree Formation in 

Nebraska was about 2 feet per day (Bradley, 1956).

Recharge

Recharge to the Ogallala aquifer occurs from 

infiltration of precipitation on the outcrop of the Ogallala Formation and the windblown sands in the southeast portion of the study area. Recharge to the Arikaree 

aquifer occurs from infiltration of precipitation on the 

outcrop of the Arikaree Formation.

Previous investigators have estimated recharge 

for the High Plains aquifer, which includes the Ogallala 

and Arikaree aquifers. These estimates include 

15 percent of precipitation or 2.5 to 3.0 inches per year 

(Langbein, 1949), 2.6 inches per year in the upper 

Niobrara River Basin (Bradley, 1956), 1.0 to 2.5 inches 

per year (McGuinness, 1963), 3.07 inches per year for 

the Sand Hills of Nebraska (Rahn and Paul, 1975), and 

8 percent of precipitation or 1.3 to 1.8 inches per year 

for South Dakota (Kolm and Case, 1983). The lower 

permeability of the Arikaree aquifer, particularly in the 

upper part, may prevent that aquifer from accepting as 

much recharge as the Ogallala aquifer. The range of 

estimated values given by all of these investigators is 

1.0 to 3.07 inches per year, which is equal to 111 to 

341 cubic feet per second when applied over the outcrop areas of the Ogallala and Arikaree aquifers in the 

study area (1,509 square miles).

Discharge

Discharge from the Ogallala and Arikaree aquifers occurs through evapotranspiration, discharge to 

streams, and well withdrawals. Discharge by evapotranspiration generally occurs in topographically low 

areas. Discharge to streams occurs as springs and seeps. 

For the purpose of this analysis, all spring discharge is 

assumed to reach a stream and contribute to base flow. 

Well withdrawals are from irrigation, domestic, and 

stock wells.

Evapotranspiration

Evapotranspiration is an important mechanism 

of ground-water discharge from the Ogallala and 

Arikaree aquifers. Evapotranspiration occurs when the 

water table is at or near the land surface and thus generally occurs in topographically low areas such as river 

valley bottoms. Maximum evapotranspiration occurs 

when the water table is at the land surface; however, 

evapotranspiration is limited by the depth of the root 

zone. Generally, the depth of this root zone is assumed 

to be 5 to 10 feet in the study area, with deeper root 

penetration associated with trees. Areas of trees are 

common up to one-half mile from the Little White 

River and its tributaries between Spring Creek and 

Soldier Creek. Trees also are common near streams 

along the northern extent of the outcrop of the Arikaree 

Formation (fig. 3). Other parts of the study area are 

generally grasslands or agricultural.

Maximum evapotranspiration during summer 

stress periods was estimated as about 70 percent of pan 

evaporation based on the relation between pan evaporation and evapotranspiration described by Farnsworth 

and others (1982). Pan evaporation rates in the study 

area were assumed to be similar to those at a National 

Weather Service climatological data station at Cottonwood (U.S. Department of Commerce, 1978-98), 

which is located about 75 miles northwest of the study 

area. Pan evaporation records were available for the 

months of June through September for the 20 water 

years included in the analysis. The estimated maximum 

evapotranspiration for the 20 summer stress periods 

(table 3) ranged from 20.4 to 30.7 inches, with an 

average of 25.6 inches. Based on limited pan evaporation data for spring and late fall, a value for the spring 

stress periods was estimated as 9 inches, and a value for 

the winter stress periods was extrapolated as 3 inches. 

Based on these estimates, the maximum evapotranspiration was calculated as 6.3 and 2.1 inches, respectively, for the spring and winter stress periods. The 

estimated 20-year average maximum evapotranspiration rate was 34 inches per year. The actual evapotranspiration rate for the study area was not estimated 

because it is a complex process and dependent on 

multiple factors.
Conceptual Model 17

Discharge to Streams

Springs and seeps discharge ground water to 

streams in the study area. Seepage runs, which consisted of synoptic measurements of streamflow under 

near base-flow conditions, were conducted in the study 

area to obtain information describing streamflow gains 

in the study area. Streamflow was measured at 35 sites 

(fig. 7, table 4). These measurements were taken during 

periods when direct runoff was not observed to occur 

and thus represent near base-flow conditions. Although 

the seepage runs occurred during WY 1999, which was 

after the period considered in the model (WY 1979-98), 

the measurements provide insights regarding the relative magnitude of ground-water discharge that contributes to base flow in various streams.

Table 3. Maximum evapotranspiration during summer 

stress periods, water years 1979-98

[--, not applicable]

Water

year

Stress

period

Pan

evaporation

(inches)

Maximum

June-September

evapotranspiration

(inches)

1979 3 35.4 24.8

1980 6 41.5 29.1

1981 9 35.5 24.8

1982 12 31.3 21.9

1983 15 40.4 28.3

1984 18 38.0 26.6

1985 21 39.7 27.8

1986 24 29.9 20.9

1987 27 39.5 27.6

1988 30 43.8 30.7

1989 33 42.1 29.5

1990 36 40.5 28.3

1991 39 37.8 26.5

1992 42 30.8 21.6

1993 45 29.2 20.4

1994 48 37.4 26.2

1995 51 36.2 25.3

1996 54 39.5 27.7

1997 57 32.1 22.5

1998 60 31.3 21.9

Average -- 36.6 25.6

Base flow in the Little White and Keya Paha 

Rivers in the study area was estimated for the 60 stress 

periods during WY 1979-98 using the hydrograph 

separation program, HYSEP (Sloto and Crouse, 

1996). Streamflow at gaging stations 06449100 (Little 

White River near Vetal; site 1), 06449500 (Little 

White River near Rosebud; site 12), and 06464100 

(Keya Paha River near Keyapaha; site 33) was used to 

estimate average base flow for each month in these 

two streams for the study area. Base flow for the Little 

White River Basin in the study area was determined 

by subtracting the base flow at site 1 from the base 

flow at site 12. All base flow estimated for site 33 was 

assumed to originate in the study area because the 

headwaters for the Keya Paha River are contained in 

the study area. Records for WY 1979-81 were unavailable for site 33; streamflow for this period was 

estimated from correlation with streamflow at downstream station 06464500 (Keya Paha River at 

Wewela).

Base flow calculated by HYSEP for the spring 

stress periods (March-May) generally increased dramatically from the fall-winter stress periods (OctoberFebruary); however, actual base flow probably does 

not fluctuate to this magnitude. The large increases 

during the spring periods probably include a component of shallow interflow that occurs after periods of 

precipitation and possibly some direct runoff. The 

fall-winter periods are probably a better estimate of 

base flow, because these periods are influenced very 

little by recent precipitation. However, springtime 

base flow is assumed to increase somewhat in 

response to rising ground-water levels followed by a 

gradual decline during summer. Therefore, calculated 

base flow for spring periods was adjusted by reducing 

the increase from the fall-winter periods by 

75 percent. The summer period was then estimated as 

the average of the two previous periods (table 5). 

Although this method is considered an improvement 

over the HYSEP estimate, it is only a very general 

estimate, and its accuracy has not been verified. The 

estimated 20-year average base flow was 49 cubic feet 

per second for the Little White River and 23 cubic feet 

per second for the Keya Paha River. 

Other springs are located along the northern 

contact of the Arikaree Formation with the White 

River Group and discharge from the Arikaree aquifer 

into streams flowing to the north. Spring discharge 

probably takes place near this contact because of the 

very low permeability of the White River Group, 

which causes northerly flowing ground water to 

emerge as springflow.
18 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 7. Streamflow measurement sites for seepage runs during water year 1999.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

#

## ##

#

# #

#

#

#

#

# #

#

#

# #

#

#

# #

#

#

#

#

#

#

##

#

#

9

8

7

5 6

1 3

4

2

34

35

32

31

30

29

28

27

24

23

22

21

19

20

18

17

15

16

14

13

12

11

10

33

25

26

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

EXPLANATION

# MEASUREMENT SITE—Number is map label number in table 4 10
Conceptual Model 19

Table 4. Measured streamflow at selected sites during seepage runs in water year 1999

[e, estimated; --, not measured]

Map

label

(fig. 7)

Site

identification

number

Latitude Longitude Station Name

Streamflow

(cubic feet per second)

July 27-29,

1999 

Aug. 30-

Sept. 1, 1999

Little White River Drainage Basin

1 06449100 430603 1011349 Little White River near Vetal, SD 72 44.9

2 430158101045400 430158 1010454 Spring Creek near Cody, NE 2.08 --

3 430610101044300 430610 1010443 Spring Creek near Spring Creek, SD 9.18 4.29

4 430611101044500 430611 1010445 Little White River below Spring Creek 117.4 66.1

5 431146100574900 431146 1005749 Omaha Creek near Rosebud, SD 0.91 0.79

6 431205100580200 431205 1005802 Beads Creek near Rosebud, SD 1.5 1.0

7 431208100580300 431208 1005803 Little White River below Beads Creek 117 75.6

8 431343100571700 431343 1005717 South Fork Ironwood Creek 1.77 1.60

9 06449300 431547 1005502 Little White River above Rosebud, SD 119 84.9

10 06449400 431414 1005126 Rosebud Creek at Rosebud, SD 8.0 7.84

11 431911100525200 431911 1005252 Soldier Creek near Rosebud, SD 1.73 1.88

12 06449500 431932 1005300 Little White River near Rosebud, SD 140 99.3

Cut Meat Creek Drainage Basin

13 431830101033400 431830 1010334 Phister Creek near Parmelee, SD 0.74 0.56

14 431837101033200 431837 1010332 Cut Meat Creek below Phister Creek 1.1 0.67

15 432249100595500 432249 1005955 Cut Meat Creek near Parmelee, SD 2.38 0.01

16 432405100591300 432405 1005913 Gray Eagletail Creek near Parmelee, SD 2.09 2.25

Black Pipe Creek Drainage Basin

17 432323101113300 432323 1011133 Black Pipe Creek near Black Pipe, SD 3.9 2.79

18 432743101100900 432743 1011009 Black Pipe Creek near Norris, SD 3.6 --

Minnechaduza Creek Drainage Basin

19 430021101075300 430021 1010753 Minnechaduza Creek near Cody, NE e0.1 --

20 430114100574900 430114 1005749 Minnechaduza Creek near Kilgore, NE 2.72 116.3

Keya Paha River Drainage Basin

21 06463900 431626 1004056 Antelope Creek near Mission, SD 2.0 3.17

22 431700100412500 431700 1004125 Antelope Creek tributary above Mission, SD 0.5 0.58

23 431648100331800 431648 1003318 Antelope Creek below Antelope Lake near 

Mission, SD

4.33 1.29

24 431506100281600 431506 1002816 Antelope Creek above Keya Paha River near 

Mission, SD

6.1 1.74

25 430940100294800 430940 1002948 Lone Tree Creek near Olsonville, SD 0.72 0.56

26 430940100294600 430940 1002946 Rock Creek below Lone Tree Creek 5.24 4.44

27 431258100240000 431258 1002400 Rock Creek near Mission, SD 9.39 8.56

28 431257100220000 431257 1002200 Keya Paha River below Rock Creek near 

Mission, SD

19.3 14.1

29 431132100184700 431132 1001847 Keya Paha River above Eagle Creek near 

Mission, SD

19.8 15.4

30 430645100185200 430645 1001852 Eagle Creek near Olsonville, SD 0.21 0.36
20 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Keya Paha River Drainage Basin—Continued

31 430930100171500 430930 1001715 Eagle Creek near Keyapaha, SD 1.56 2.21

32 431008100140300 431008 1001403 Keya Paha River below Eagle Creek, SD 22.0 15.6

33 06464100 430745 1000624 Keya Paha River near Keyapaha, SD 26.5 22.4

34 425959100174900 425959 1001749 Sand Creek near Valentine, NE 0 0

35 430254100111000 430254 1001110 Sand Creek near Keya Paha, SD 4.43 4.45

1

Streamflow influenced by rain storm.

Table 4. Measured streamflow at selected sites during seepage runs in water year 1999–Continued

[e, estimated; --, not measured]

Map

label

(fig. 7)

Site

identification

number

Latitude Longitude Station Name

Streamflow

(cubic feet per second)

July 27-29,

1999 

Aug. 30-

Sept. 1, 1999

Well Withdrawals

Well withdrawals in the study area occur from 

irrigation, domestic, and stock wells. Withdrawals for 

irrigation use are much larger than for domestic and 

stock uses; thus, withdrawals for domestic and stock 

uses were assumed to be negligible. Municipal withdrawals also were considered negligible because of the 

small and disperse population.

Irrigation withdrawals from the Ogallala aquifer 

are especially important in Todd County. Pivot irrigation units were identified using aerial photographs. 

Most irrigation wells in the study area are located east 

of St. Francis (fig. 8), where the saturated thickness of 

the Ogallala aquifer is greatest. Of the 97 pivot irrigation units identified from aerial photographs in the 

study area, 94 were assumed to be completed in the 

Ogallala aquifer based on well data in the USGS 

Ground-Water Site Inventory (GWSI) database. Most 

of the wells used for irrigation in the study area were 

constructed in the 1970’s, and well construction records 

are incomplete.

Water-use data are compiled every 5 years as part 

of the USGS National Water-Use Information Program 

in cooperation with local, State, and Federal agencies 

and is aggregated by counties for each State. The acres 

of irrigated land in Todd County that were compiled for 

1985, 1990, and 1995 remained steady at slightly more 

than 10,000 acres (U.S. Geological Survey, 1996, 

2001). The estimated area of traces for pivots shown in 

figure 8 is about 11,000 acres, which is close to the 

reported irrigated acreage. Irrigation withdrawals are 

variable because they are affected by numerous factors, 

such as climatic conditions, commodity prices, and 

energy costs.

Data on irrigation withdrawals from the Ogallala 

and Arikaree aquifers in the study area were compiled 

from the USGS Site-Specific Water-Use Data System 

(SWUDS) for the period of available record (1981-98). 

The SWUDS database includes irrigation water use 

reported by operators under specific water-use permits. 

The reported use for a permit can include more than one 

well or center-pivot irrigation system. In the study area, 

water-use records were identified for 41 of the center 

pivots (fig. 8) by examining well data in the GWSI 

database, which usually includes a water-rights permit 

number. When the water use reported under a specific 

permit included more than one center pivot, the 

reported values were allocated equally among the associated irrigation wells. Irrigation withdrawals for the 

remaining center pivots were estimated based on the 

average withdrawals for the 41 identified wells. Irrigation withdrawals for 1979 and 1980 were estimated 

based on the reported withdrawals in the early 1980’s. 

The estimated irrigation withdrawal for the study area 

by year ranged from about 3,000 to 21,000 acre-feet, 

and averaged 8,415 acre-feet (table 6), or 34.8 cubic 

feet per second over a 4-month period at an average 

application rate of 8.7 inches per year. The average 

withdrawal rate is 11.6 cubic feet per second if a 

12-month period is assumed. The largest estimated irrigation use during the analysis period was in 1989 when 

precipitation was about 4 inches below normal. 
Conceptual Model 21

Table 5. Estimates of base flow in the Little White and Keya Paha Rivers, water years 1979-98

[--, not applicable]

Stress

period Time period

Base flow

(cubic feet per second) Stress

period Time period

Base flow

(cubic feet per second)

Little White

River

Keya Paha

River

Little White

River

Keya Paha

River

1 Oct. 1978 - Feb. 1979 30 6 32 Mar. - May 1989 41 17

2 Mar. - May 1979 41 13 33 June - Sept. 1989 38 15

3 June - Sept. 1979 35 9 34 Oct. 1989 - Feb. 1990 40 14

4 Oct. 1979 - Feb. 1980 26 14 35 Mar. - May 1990 45 17

5 Mar. - May 1980 32 16 36 June - Sept. 1990 43 15

6 June - Sept. 1980 29 15 37 Oct. 1990 - Feb. 1991 51 12

7 Oct. 1980 - Feb. 1981 49 7 38 Mar. - May 1991 56 18

8 Mar. - May 1981 50 8 39 June - Sept. 1991 53 15

9 June - Sept. 1981 49 8 40 Oct. 1991 - Feb. 1992 49 16

10 Oct. 1981 - Feb. 1982 40 9 41 Mar. - May 1992 53 18

11 Mar. - May 1982 42 17 42 June - Sept. 1992 51 17

12 June - Sept. 1982 41 13 43 Oct. 1992 - Feb. 1993 51 13

13 Oct. 1982 - Feb. 1983 50 30 44 Mar. - May 1993 61 23

14 Mar. - May 1983 62 34 45 June - Sept. 1993 56 18

15 June - Sept. 1983 56 32 46 Oct. 1993 - Feb. 1994 44 18

16 Oct. 1983 - Feb. 1984 50 29 47 Mar. - May 1994 55 21

17 Mar. - May 1984 54 40 48 June - Sept. 1994 50 20

18 June -Sept. 1984 52 34 49 Oct. 1994 - Feb. 1995 38 19

19 Oct. 1984 - Feb. 1985 43 17 50 Mar. - May 1995 52 34

20 Mar. - May 1985 45 21 51 June - Sept. 1995 45 27

21 June - Sept. 1985 44 19 52 Oct. 1995 - Feb. 1996 46 43

22 Oct. 1985 - Feb. 1986 39 13 53 Mar. - May 1996 55 48

23 Mar. - May 1986 46 26 54 June - Sept. 1996 51 45

24 June - Sept. 1986 43 19 55 Oct. 1996 - Feb. 1997 85 48

25 Oct. 1986 - Feb. 1987 59 26 56 Mar. - May 1997 85 58

26 Mar. - May 1987 66 38 57 June - Sept. 1997 85 53

27 June -Sept. 1987 63 32 58 Oct. 1997 - Feb. 1998 48 34

28 Oct. 1987-Feb. 1988 48 14 59 Mar. - May 1998 58 39

29 Mar. - May 1988 52 22 60 June - Sept. 1998 53 36

30 June - Sept. 1988 50 18 Average -- 49 23

31 Oct. 1988 - Feb. 1989 36 13
22 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 8. Locations of irrigation wells completed in the Ogallala and Arikaree aquifers.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

.

.

... .

. .. . . . . .. . . .. ...... . . ... . . ...... .. . . .. . . .. ......... . .. .. . . . . . . . .. .. .. .. . . . . . .... . .

.. .

.

.

.

.

!

!

!!

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

EXPLANATION

AREA OF OGALLALA AQUIFER CONSIDERED

AREA OF ARIKAREE AQUIFER CONSIDERED

IRRIGATION WELL IN OGALLALA AQUIFER

IRRIGATION WELL IN ARIKAREE AQUIFER
Numerical Model 23

Numerical Model

A numerical model of the Ogallala and Arikaree 

aquifers in the study area was used for steady-state and 

transient simulations of ground-water flow. A 20-year 

analysis period (WY 1979-98), which was temporally 

discretized into 60 seasonal stress periods as previously 

described, was used in the transient simulation. Design 

and calibration of the numerical model are described in 

the following sections. 

Table 6. Estimated ground-water withdrawals for irrigation 

use in the study area, 1979-98

Year

Irrigation withdrawals

Acre-feet Cubic feet per second1

1

Withdrawal rate based on a 4-month irrigation season (JuneSeptember).

Total Total Ogallala

aquifer

Arikaree

aquifer

1979 4,617 19.1 18.7 0.4

1980 4,617 19.1 18.7 .4

1981 4,697 19.4 18.7 .7

1982 3,291 13.6 13.5 .1

1983 5,861 24.2 24.0 .2

1984 4,385 18.1 17.9 .2

1985 7,763 32.1 31.9 .2

1986 7,344 30.4 30.4 0

1987 5,878 24.3 24.3 0

1988 11,561 47.8 47.7 .1

1989 20,843 86.1 85.9 .2

1990 11,314 46.8 46.8 0

1991 10,121 41.8 41.6 .2

1992 5,037 20.8 20.7 .1

1993 7,793 32.2 32.1 .1

1994 9,548 39.5 39.2 .3

1995 8,962 37.0 37.0 0

1996 15,284 63.2 63.0 .2

1997 12,198 50.4 50.3 .1

1998 7,192 29.7 29.5 .2

Average 8,415 34.8 34.6 .2

Model Design

MODFLOW-2000 (Harbaugh and others, 

2000), which is a numerical, three-dimensional, 

finite-difference ground-water model, was used to 

simulate flow in the aquifers. Detailed descriptions of 

MODFLOW-2000 packages that were incorporated in 

the model are presented in McDonald and Harbaugh 

(1988) and Harbaugh and others (2000). These packages included Layer-Property Flow, River, Recharge, 

Well, Drain, and Evapotranspiration. Average rates of 

recharge, maximum evapotranspiration, and well 

withdrawals were included in the steady-state simulation, whereas the time-varying rates that the averages 

were computed from were included in the transient 

simulation. 

Grid and Boundary Conditions

The model grid consisted of two layers, each 

with 153 rows and 180 columns. All grid cells were 

1,640 feet (500 meters) on a side. The upper layer 

(layer 1) represented the Ogallala aquifer, and the 

lower layer (layer 2) represented the Arikaree aquifer. 

The height of each cell was equal to the estimated formation thickness, which was determined based on 

structure-contour maps of the Arikaree Formation and 

White River Group (Carter, 1998) and a 30-meter 

digital elevation model (DEM) of the land surface. 

The DEM was used to represent the top of layer 1 and 

the top of layer 2 where the Arikaree Formation is 

exposed to the land surface. The altitude of the top of 

the Arikaree Formation represented the bottom of 

layer 1 and top of layer 2; the altitude of the top of 

the White River Group represented the bottom of 

layer 2. 

Both layers were modeled so that cells were 

convertible between confined and unconfined conditions. Cells of constant hydraulic head were used on 

the western model boundary and the western part of 

the southern boundary for both layers and also in the 

southeastern corner for layer 1 (Ogallala aquifer) 

(figs. 9 and 10). All other boundaries were designated 

as “no-flow boundaries,” which includes the edges of 

the aquifers or where model boundaries were approximately parallel to the estimated ground-water flow 

direction. 
24 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 9. Cell types in the Ogallala aquifer (layer 1). Locations of observation wells completed in Ogallala aquifer also

are shown.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

3 8

6

7

4

5

9

13 16

11

18

23

22

10

21

27

17

12

19

41 20

2 80

87

125

130 126

145

160

175

176 177

194 201

207 219

170

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

ACTIVE CELLS

INACTIVE CELLS

CONSTANT-HEAD CELLS

EXPLANATION

STATE OBSERVATION WELL COMPLETED IN

 OGALLALA AQUIFER—Label is well number

 in tables 8 and 15 

TRIBAL OBSERVATION WELL COMPLETED IN

 OGALLALA AQUIFER—Label is well number

 in tables 9 and 15

41

10
Numerical Model 25

Figure 10. Cell types in the Arikaree aquifer (layer 2). Locations of observation wells completed in Arikaree aquifer also

are shown.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

205 210

274

361

374

384

15

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

ACTIVE CELLS

INACTIVE CELLS

CONSTANT-HEAD CELLS

EXPLANATION

STATE OBSERVATION WELL COMPLETED

 IN ARIKAREE AQUIFER—Label is well

 number in tables 8 and 16 

TRIBAL OBSERVATION WELL COMPLETED

 IN ARIKAREE AQUIFER—Label is well

 number in tables 9 and 16

361

15
26 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Representation of Hydraulic Properties

Estimated horizontal hydraulic conductivity for 

the Ogallala aquifer ranged from 0.2 to 120 feet per day 

(fig. 11). Estimated values were based on previously 

published values (table 2), the spatial distribution of 

specific capacities in the study area (fig. 12), and model 

calibration. Specific capacity computed for 64 wells 

completed in the Ogallala aquifer ranges from 0.01 to 

58.0 gallons per minute per foot, with an average of 

3.8 gallons per minute per foot. Figure 12 shows the 

generalized distribution of specific capacity in the 

Ogallala aquifer based on these 64 wells. These specific 

capacity ranges do not represent actual values because 

the data were smoothed and compared relatively within 

the study area. The greater specific capacity in the central part of the model area between the Little White and 

Keya Paha Rivers coincides with a concentration of 

irrigation pivots, and the overall specific capacity distribution is generally consistent with the distribution of 

hydraulic conductivity shown in figure 11. Kolm and 

Case (1983) analyzed grain-size distributions to estimate horizontal hydraulic conductivity for the High 

Plains aquifer (fig. 13), which includes the Ogallala 

and Arikaree aquifers. The spatial distribution of horizontal hydraulic conductivity estimated by Kolm and 

Case (1983) is in general agreement with that shown in 

figure 11.

Estimated horizontal hydraulic conductivity for 

the Arikaree aquifer ranged from 0.05 to 6.0 feet per 

day (fig. 14). Estimated values were based on previously published values (table 2) and model calibration. 

Specific capacity computed for 14 wells completed in 

the Arikaree aquifer ranges from 0.01 to 10.0 gallons 

per minute per foot, with an average of 0.4 gallons per 

minute per foot. Although specific capacity data were 

insufficient to estimate the spatial distribution of horizontal hydraulic conductivity in the Arikaree aquifer, 

these data and the horizontal hydraulic conductivity 

values shown in table 2 indicate that horizontal 

hydraulic conductivity values in the Arikaree aquifer 

are lower and have less variability than in the Ogallala 

aquifer. Zones of large horizontal hydraulic conductivity were assigned along the Little White and Keya 

Paha Rivers (fig. 14) in order to calibrate to the substantial ground-water discharge that occurs to these 

streams. In these areas, the alluvium was combined 

with model layer 2 and thus required a higher hydraulic 

conductivity. Other possible reasons for higher 

hydraulic conductivity are near-surface weathering, 

which probably extends below the water table in these 

topographically low areas. In addition, if the locations 

of these streams are influenced by fractures or faults, 

higher hydraulic conductivity could result.

Previously published values and specificcapacity data were used as general indicators for 

hydraulic conductivity values and distributions; however, model calibration carried the most weight in 

determining the final values and distributions. 

Hydraulic conductivity values and the spatial distribution of zones were varied by trial and error to obtain an 

optimum fit to observed hydraulic heads and base 

flows. Greater discretization of zones could have 

improved that fit by adjusting hydraulic conductivities 

near individual wells or very small groups of wells; 

however, the data did not support this degree of heterogeneity. Therefore, the calibration accuracy obtained 

using the larger zones shown in figures 11 and 14 was 

considered sufficient to fulfill the objectives of this 

study.

A uniform vertical hydraulic conductivity value 

was applied to the Ogallala aquifer, whereas vertical 

hydraulic conductivity was estimated for five zones in 

the Arikaree aquifer (fig. 15). Zone delineation for 

hydraulic properties was determined by considering 

potential structural features and by trial-and-error 

methods to achieve an optimum fit to observed data. 

Because stream locations may have structural control, 

zone boundaries were initially placed along streams to 

create five major zones for horizontal and vertical 

hydraulic conductivity. Although the use of potential 

structural features for these boundaries is arbitrary, data 

were not sufficient to determine different boundaries. 

These five zones were used as a starting point for the 

delineation of subzones when necessary. Subzone 

delineation and estimated values were determined by 

trial-and-error model calibration.

MODFLOW-2000 calculates vertical hydraulic 

conductivity between adjacent layers as the harmonic 

mean of the two layers, which resulted in unique values 

of the harmonic mean for each of the five conductivity 

zones in the Arikaree aquifer. Estimated vertical 

hydraulic conductivity was 6.6x10-4 feet per day for 

the Ogallala aquifer and ranged from 8.6x10-6 to 

7.2x10-1 feet per day for the Arikaree aquifer (fig. 15).
Numerical Model 27

Figure 11. Estimated horizontal hydraulic conductivity of the Ogallala aquifer.

2.0

20

7.1

120

9.3

0.9

37

0.2

7.6

23

9.3

46 T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Sand Creek

Creek

Creek

Creek

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Rock

Cut

Meat

Creek

Dry

Creek

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

HYDRAULIC CONDUCTIVITY, IN FEET PER DAY—

 Shading indicates ranges of values; numbers

 indicate actual values for cells in block, except

 the transition cells along block boundaries

0 to 1

Greater than 1 to 10

Greater than 10 to 25

Greater than 25 to 50

Greater than 50 to 120

0.2

7.6

20

37

120

EXPLANATION

INACTIVE CELLS
28 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 12. Generalized specific capacity ranges in the Ogallala aquifer.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!!

!!!!

!

!

!

!

!

!

! ! !

!

!

!

!

!

!

!

!

!

! !

!

! !

!

!

!

! !

.

.

. . . .

. .. . . . . .. . . .. .. . . .. . .. . . . . .. .. . . . . . . .. . . .. . . .. . .. . . . . . .. . . . . . . . .. .. .. .. . . . . . .. . . . . .. .

.

. .

.

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

EXPLANATION

ESTIMATED SPECIFIC CAPACITY RANGE

IRRIGATION WELL IN THE OGALLALA AQUIFER

WELL WITH COMPUTED SPECIFIC CAPACITY

Low

Medium

High
Numerical Model 29

Figure 13. Hydraulic conductivity estimated from grain-size descriptions in the High Plains aquifer.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

25

25

25

25

25

25

25

25

15

15

15

15

15

15

15

50

50

50

EXPLANATION

LINE OF EQUAL HYDRAULIC CONDUCTIVITY,

 IN FEET PER DAY. Interval is variable

 (modified from Kolm and Case, 1983)

HIGH PLAINS AQUIFER

25

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS
30 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 14. Estimated horizontal hydraulic conductivity of the Arikaree aquifer.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

0.05 to 0.1

Greater than 0.1 to 2.0

Greater than 2.0 to 4.0

Greater than 4.0 to 6.0

EXPLANATION

0.1

5.4

0.1

1.2

1.2

2.4

4.7

1.3

2.3

1.2

2.3

5.4

HYDRAULIC CONDUCTIVITY, IN FEET PER DAY—

 Shading indicates ranges of values; numbers

 indicate actual values for cells in block, except

 the transition cells along block boundaries
Numerical Model 31

Figure 15. Estimated vertical hydraulic conductivity of the Arikaree aquifer.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

VERTICAL HYDRAULIC CONDUCTIVITY,

 IN FEET PER DAY

8.6x10-6

7.2x10-1

1.8x10-3

2.0x10-2

2.6x10-3

EXPLANATION
32 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Representation of Recharge and Discharge

Recharge rates for the steady-state simulation 

were estimated from previously published values and 

model calibration. Recharge was 3.3 inches per year for 

the Ogallala aquifer (17 percent of average precipitation) and 1.7 inches per year for the Arikaree aquifer 

(8.5 percent of average precipitation). Although 

recharge probably is spatially variable, a uniform distribution was assumed for each of the two outcrop areas 

because of insufficient data. A lower rate of recharge 

for the Arikaree aquifer than the Ogallala aquifer 

allowed a better fit to observed heads. These percentages were applied to the precipitation rates for each 

stress period to obtain recharge rates for the transient 

simulation (table 7). Precipitation records (table 7) 

were available for a National Weather Service Climatological Data station at Mission (U.S. Department of 

Commerce, 1978-98), which is located near the center 

of the study area. 

Various MODFLOW-2000 packages were used 

to simulate the discharge components of evapotranspiration, discharge to streams, and well withdrawals. The 

“Evapotranspiration” package was designed to simulate evapotranspiration from the uppermost aquifer in 

any given cell where the water table is within a specified depth below the land surface (McDonald and 

Harbaugh, 1988). This so-named extinction depth was 

set to 10 feet in areas with woody vegetation (U.S. 

Geological Survey, 1955) and to 5 feet elsewhere, 

which reflects estimated rooting depths for woody vegetation, grasslands, and crops (fig. 16). The evapotranspiration (ET) rate is zero at the extinction depth and 

increases linearly to a maximum rate when the water 

level is at or above the land surface. The land-surface 

altitude was set to the average altitude for each cell 

based on a 30-meter DEM.

Discharge to streams, which includes springs and 

seeps, was represented using two packages. The 

“River” package in MODFLOW-2000 was used to simulate the hydraulic connection between ground water 

and surface water by allowing streams to gain or lose 

water based on the difference between the surrounding 

hydraulic head and stream stage through riverbed 

material of a specified hydraulic conductance 

(McDonald and Harbaugh, 1988). Estimated riverbed 

conductance was based on model calibration. Model 

cells were designated as river cells along major streams 

and tributaries where the potentiometric surface intersected the land surface (fig. 16). The “Drain” package 

simulated springs discharging from the Ogallala 

aquifer along the banks of the Little White River and 

springs along the northern edge of the Arikaree aquifer 

(fig. 16). Drains were added in stream channels where 

springs were likely to occur and where drains improved 

model calibration. Drain conductance was estimated by 

model calibration. The “Drain” package is similar to 

the “River” package except that drain cells can only 

take water out of the aquifer, whereas river cells also 

can recharge the aquifer (McDonald and Harbaugh, 

1988). 

Irrigation well withdrawals were simulated with 

the “Well” package (McDonald and Harbaugh, 1988) 

to withdraw water from each well at a specified rate. 

Irrigation withdrawals are listed in table 6, and locations are shown in figures 8 and 16.

Model Calibration

Model calibration was accomplished by varying 

the model-input parameters within plausible ranges to 

produce the best fit between simulated and observed 

hydraulic heads in the Ogallala and Arikaree aquifers 

and base flows in streams. Steady-state and transient 

simulations were analyzed to determine the best combination of model-input parameters.

Water-level measurements for 398 wells that 

were used for estimation of potentiometric surfaces of 

the Ogallala and Arikaree aquifers (figs. 4 and 5) were 

considered for calibration of the steady-state model. 

These wells include 44 observation wells with longterm water-level records that were used for calibration 

of the transient model and 354 public and private wells. 

The observation wells include 23 State wells (of which 

17 are completed in the Ogallala aquifer and 6 are completed in the Arikaree aquifer) and 21 Tribal wells (of 

which 20 are completed in the Ogallala aquifer and 1 is 

completed in the Arikaree aquifer) (figs. 9 and 10). 

Selected data for the State and Tribal observation wells 

are presented in tables 8 and 9, respectively.

The majority of the State and Tribal observation 

wells are concentrated in the central part of the study 

area (fig. 9) where irrigation is prevalent (fig. 8). The 

Ogallala aquifer in the central part of the study area is 

of primary concern to the Rosebud Sioux Tribe and is 

the main focus of the numerical model.
Numerical Model 33

Table 7. Estimated recharge to the Ogallala and Arikaree aquifers, water years 1979-98

[--, not applicable]

Water

year

Stress

period

Precipitation

(inches)

Recharge to

Ogallala

aquifer

(inches)

Recharge to

Arikaree

aquifer

(inches)

Water

year

Stress

period

Precipitation

(inches)

Recharge to

Ogallala

aquifer

(inches)

Recharge to

Arikaree

aquifer

(inches)

1979 1 1.5 0.3 0.1 1989 31 1.2 .2 .1

2 4.7 .8 .4 32 3.0 .5 .3

3 11.5 2.0 1.0 33 9.8 1.7 .8

1980 4 3.2 .5 .3 1990 34 2.6 .4 .2

5 3.3 .6 .3 35 6.7 1.1 .6

6 7.2 1.2 .6 36 10.7 1.8 .9

1981 7 3.2 .5 .3 1991 37 2.4 0.4 0.2

8 5.9 1.0 .5 38 10.7 1.8 .9

9 10.1 1.7 .9 39 8.2 1.4 .7

1982 10 4.7 .8 .4 1992 40 2.3 .4 .2

11 9.8 1.7 .8 41 2.0 .3 .2

12 13.5 2.3 1.1 42 13.2 2.2 1.1

1983 13 5.4 .9 .5 1993 43 2.4 .4 .2

14 8.5 1.4 .7 44 5.4 .9 .5

15 9.7 1.7 .8 45 9.8 1.7 .8

1984 16 3.8 .7 .3 1994 46 4.0 .7 .3

17 5.4 .9 .5 47 3.8 .6 .3

18 7.7 1.3 .7 48 12.5 2.1 1.1

1985 19 2.8 .5 .2 1995 49 2.9 .5 .2

20 3.1 .5 .3 50 10.4 1.8 .9

21 7.7 1.3 .7 51 8.1 1.4 .7

1986 22 4.0 .7 .3 1996 52 6.3 1.1 .5

23 8.3 1.4 .7 53 7.0 1.2 .6

24 12.8 2.2 1.1 54 7.7 1.3 .7

1987 25 3.5 .6 .3 1997 55 4.6 .8 .4

26 8.4 1.4 .7 56 6.5 1.1 .6

27 6.6 1.1 .6 57 11.1 1.9 .9

1988 28 3.1 .5 .3 1998 58 3.1 .5 .3

29 6.6 1.1 .6 59 5.7 1.0 .5

30 7.9 1.3 .7 60 13.8 2.3 1.2

Average

 annual

-- 19.6 3.3 1.7
34 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 16. Evapotranspiration, river cells, drain cells, and irrigation wells in the Ogallala and Arikaree aquifers.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

# #

#

#

#

#

# ## # #

# # ## #

#

# # ## # # # #

#

#

## #

#

#

#

## # # # # #

#

#

G

G

G

G

G

G

GGG

G

G

G GGGGGG G G GGG GGGGG GG GG GG GGGGGG G G GGG G G GG G GG G GGGG GGG GG G G GG G G GG G GG GGG GG GGGGG G G G GG GGG GG G G GG

GGGG

GGGGGG

GG GGG GGG GGG G G GG G G G GG G G GGGG GGGG G GG GGGG GGGG GGG GGGGG GG

G

G GGGGG GG GGGG G G G GG G GGG G GG G GGGGGGGGG GGGGG G G GGG GGGG GG GG GG GGGG G G GG GG GGGGG GGGGGG G GGG GG G G

G

G GG G G

GGG GG G GG G GGG G G

GG GG

GGG

G

GGG GG G GGG G

G

G

G G G GG

GGG G GG GG GGGG

G GGGGGGG

GGG G G GGGG G GG G G G GG G GG G GG G

GG

G

G

GGG G G GGGG GGGGGG GGG GG GGG GG G GG GGG GG G GGGG GG GGG GGGG GGGG GGGG

GGG G GG G G G G G GG GG G G G G GG GG G

G GGGG

G

G

G

GGGGG

G GGGGGGGGG

G

G

G

GG

GGGG

GG G GGGGGG GGG GGGGGGG G GGGGGGGGGGG G

GGGGG GG GGGGGGG G GG G G GGGGGGGG GG G GGGGGGG G GGG G G G GG G GGG

G GG G GGG G GGG GG GGGGGGGGG GG GGGG G G GGG G G GG G GGG GGG GGG G GGGG GG GG GG GG GGG G GG GG GG G GG G GGGG G GG GG G GG G GG GGG GGGGG G G G GG GGGG G

GGG

G

G

G

G GGG G GGG GGGG

GGG G GGG

G

GGG

G

GGG

GGG

GGGG GGGGG G GG

GGGG

GG GGG

G

G

G GG

G G GG GG GG G GG GG GGG G

G

GG

G GGG

G

G

G

G

G

G

G

GGGGG

G

G

G

G

G

GG G GGGGGG .

.

... .

. .. . . . . .. . . .. ...... . . ... . . ...... .. . . .. . . .. ......... . .. .. . . . . . . . .. .. .. .. . . . . . .... . .

.. .

.

.

.

.

!

!!

!

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

EXPLANATION

ACTIVE CELLS IN OGALLALA FORMATION OUTCROP

ACTIVE CELLS IN ARIKAREE FORMATION OUTCROP

EVAPOTRANSPIRATION EXTINCTION DEPTH

 EQUALS 10 FEET (5 FEET ELSEWHERE)

IRRIGATION WELL IN OGALLALA AQUIFER

IRRIGATION WELL IN ARIKAREE AQUIFER

DRAIN CELL SIMULATING SPRING DISCHARGE

RIVER CELL SIMULATING RIVER LEAKAGE
Numerical Model 35

Table 8. Selected data for State observation wells in the study area

Well

number

(figs. 9 

and 10)

Site

identification

number

Local number Aquifer

Landsurface

altitude

(feet above

NGVD of 

1929)

Well

number

(figs. 9 

and 10)

Site

Identification

number

Local number Aquifer

Landsurface

altitude

(feet above

NGVD of 

1929)

2 425957100445601 35N29W20AADD Ogallala 2,890 177 430842100411301 37N28W30CCCB Ogallala 2,770

41 430148100471001 35N29W 7BBBB Ogallala 2,903 194 430924100460601 37N29W29AAAA Ogallala 2,868

80 430310100245501 36N26W31ADDD Ogallala 2,620 201 430932100390001 37N28W21CCCC Ogallala 2,772

87 430340101012301 36N32W25DDDD Ogallala 2,841 207 431018101152001 37N33W17CCCC Ogallala 2,998

125 430609100434201 36N29W16AAAA Ogallala 2,863 219 431109100445901 37N29W16AAAA Ogallala 2,852

126 430610100481701 36N30W13BBBB Ogallala 2,916 205 430959100444001 37N29W22CCCC Arikaree 2,882

130 430613101561701 36N31W14BAAA Ogallala 2,955 210 431020100243501 37N26W16CCBB Arikaree 2,530

145 430701100363001 36N28W10BBBB Ogallala 2,823 274 431430100195901 38N25W30BCBB Arikaree 2,483

160 430748100455601 37N29W33CCCC Ogallala 2,909 361 432044101115201 39N33W15DDDD Arikaree 2,800

170 430825101151801 37N33W32BBBB2 Ogallala 2,960 374 432310101045501 39N32W 3AAAA Arikaree 2,610

175 430839100373801 37N28W27CCCC Ogallala 2,805 384 432554101065601 40N32W21BBBB Arikaree 2,576

176 430840100445601 37N29W28DDDD Ogallala 2,858

Table 9. Selected data for Tribal observation wells in the study area

Well

number

(figs. 9 

and 10)

Site

identification

number

Local number Aquifer

Landsurface

altitude

(feet above

NGVD of 

1929)

Well

number

(figs. 9 

and 10)

Site

Identification

number

Local number Aquifer

Landsurface

altitude

(feet above

NGVD of 

1929)

3 430309100570901 36N31W34DBBC Ogallala 2,920 16 430820100371401 37N28W34ABDA Ogallala 2,783

4 430017100595101 35N31W17CCDA Ogallala 2,896 17 431027100333001 37N27W18DDAB Ogallala 2,609

5 430159100531001 35N30W 6DDDD Ogallala 2,853 18 430702100330501 36N28W12AABA Ogallala 2,806

6 430501100504901 36N30W21DAAA Ogallala 2,888 19 430243100371701 36N28W33BDDD Ogallala 2,753

7 430415100451401 36N29W29ACAA Ogallala 2,870 20 430122100344501 35N28W11DBBB Ogallala 2,728

8 430258100471401 36N30W36DDDA Ogallala 2,885 21 430057100275401 35N27W14BAAB Ogallala 2,690

9 430100100460501 35N29W18AAAA Ogallala 2,870 22 430335100241401 36N26W32BBAA Ogallala 2,619

10 430154100411801 35N29W 2DDDD Ogallala 2,800 23 430728100135801 36N27W 1BDDD Ogallala 2,627

11 430530100422501 36N29W14CDAB Ogallala 2,893 27 431127100532801 37N30W 8DACC Ogallala 2,880

12 430712100421301 36N29W 2CDCC Ogallala 2,850 15 431342100344101 38N28W36ABCB Arikaree 2,620

13 430755100582301 37N29W31DACC Ogallala 2,921
36 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Steady-State Simulation

The numerical model was used to simulate 

average (steady-state) flow conditions for the 20-year 

period (WY 1979-98) previously described. Steadystate conditions were numerically approximated for the 

steady-state simulation by using a transient simulation 

with one 100-year stress period using constant input 

flow rates. The model was more stable and closed in 

fewer iterations with the 100-year transient stress 

period than with a steady-state stress period. The potentiometric surface from the steady-state simulation 

established initial conditions for the transient simulation.

The first calibration criterion for the steady-state 

simulation was that the simulated potentiometric surfaces and hydraulic gradients generally match those of 

the estimated average potentiometric surfaces. The 

simulated steady-state potentiometric surfaces (figs. 17 

and 18) generally are similar to the estimated average 

potentiometric surfaces (figs. 4 and 5) in comparison to 

both hydraulic heads and gradients, indicating satisfaction of this criterion.

A second calibration criterion included matching 

95 percent of all wells to within ±50 feet of the 

observed hydraulic heads. This second criterion was 

considered adequate because 50 feet is about 7 percent 

of the difference between the maximum and minimum 

hydraulic heads of the estimated average potentiometric surfaces in the model area (total hydraulic head 

relief); hydraulic head relief is about 780 feet in the 

Ogallala aquifer and 720 feet in the Arikaree aquifer.

Simulated hydraulic heads matched observed 

values to within ±50 feet for 95 percent of the wells. A 

histogram shows the distribution of the difference 

between the observed and simulated hydraulic heads 

(residuals) (fig. 19). The fit was considerably better for 

the 44 State observation wells (fig. 19B) than for all 

wells (fig. 19A). Observation well data were weighted 

more heavily in calibration because of a higher degree 

of confidence in that data. Simulated hydraulic heads at 

all of the State observation wells were within ±22 feet 

of the observed hydraulic heads, which is about 

3 percent of the total hydraulic head relief in the Ogallala and Arikaree aquifers. The residuals for 20 of these 

State observation wells were within ±12 feet (fig. 19B). 

Simulated hydraulic heads at all of the Tribal observation wells were within ±45 feet of the observed 

hydraulic heads, which is about 6 percent of the total 

hydraulic head relief in the Ogallala and Arikaree aquifers. The residuals for 15 of these Tribal observations 

wells were within ±20 feet (fig. 19C). The root mean 

square error (RMSE) for all wells was 26.8 feet. The 

mean error was -3.7 feet, which indicates a model bias 

toward overestimating head values. For the State and 

Tribal observation wells only, the RMSE was 21.4 feet, 

and the mean error was -1.6 feet. A linear regression 

analysis of simulated hydraulic heads and observed 

hydraulic heads for all wells (fig. 20) yielded an R2

value (coefficient of determination) of 0.97.

Base flow is another important component of 

calibration. Base flow is sensitive to many model components besides riverbed conductance. Results of the 

steady-state calibration to estimated base flow are 

shown in table 10.

A sensitivity analysis was used to examine the 

response of the numerical model calibrated to the 

steady-state condition to changes in model parameters 

including horizontal and vertical hydraulic conductivity, evapotranspiration, recharge, and riverbed conductance. During each simulation when a parameter 

was being tested, the other parameters were set to the 

steady-state calibrated value. Each parameter was 

changed uniformly over the entire model area. The percent changes in the sum of squared weighted residuals 

between the simulated and observed hydraulic heads 

for selected changes in parameter values are shown in 

figure 21. The model was most sensitive to recharge 

and horizontal hydraulic conductivity.

The water budget for the steady-state simulation 

balances (inflows minus outflows) with a percent discrepancy of -0.41 (table 11). The recharge rate used for 

the numerical model was within the range of values 

listed in the conceptual model. The exact amount of 

irrigation well withdrawals that were estimated 

(table 6) was used in the numerical model. The river 

leakage from the aquifers into the Little White and 

Keya Paha Rivers calculated by the numerical model 

was within 3.3 cubic feet per second of the estimated 

base flow for each of the two rivers. 

Table 10. Comparison of simulated and estimated base 

flow for the Little White and Keya Paha Rivers for the steadystate simulation

Stream

Base flow

(cubic feet per second)

Percent error

of simulated

compared to

estimated

base flow

Estimated1

1From table 5.

Model

simulated

Little White River 49 46.79 4.5

Keya Paha River 23 19.70 14
Numerical Model 37

Figure 17. Potentiometric surface of the Ogallala aquifer for the steady-state simulation.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Blackpipe

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

EXPLANATION

ACTIVE CELLS IN THE OGALLALA AQUIFER

SIMULATED POTENTIOMETRIC CONTOUR—

 Shows average altitude at which water level

 would have stood in tightly cased wells,

 1979-98. Contour interval is 50 feet. Datum

 is NGVD of 1929.

2,400

2,750

2,750

2,650

2,700

2,800

2,600

2,950

2,900

2,850

3,000

2,500

2,550

2,400

2,450

3,050

2,350

2,800

2,600

2,700

2,550

2,600

2,750

2,900

2,650

2800

2600

2,450

2,750

2,950

2,800

3,000

2400

2800

3,050

2,550

2,700

2850

2,950

2,850

2900

2,850

2700

2,450

2,600

2,800

2,700

2450

2,850

2,450

2,800

2500

2,600

2,900
38 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 18. Potentiometric surface of the Arikaree aquifer for the steady-state simulation.

T.

35

N.

T.

36

N.

T.

38

N.

T.

39

N.

T.

37

N.

T.

40

N.

T.

41

N.

T.

42

N.

T.

102

N.

T.

101

N.

T.

100

N.

T.

98

N.

T.

97

N.

T.

96

N.

T.

95

N.

T.

99

N.

R. 33 W. R. 32 W. R. 30 W. R. 29 W. R. 28 W. R. 27 W. R. 26 W. R. 25 W. R. 79 W. R. 31 W.

MELLETTE COUNTY

BENNETT COUNTY

TODD COUNTY

TODD COUNTY

CHERRY COUNTY

JACKSON COUNTY

TRIPP COUNTY

NEBRASKA

SOUTH DAKOTA

White River

Wood

Okreek Carter

Parmelee

Mission Antelope

Rosebud

St. Francis

Olsonville

Norris

Blackpipe

83

83

18

18

Little

White

Keya Paha

River

River

Thunder

Creek

White

Creek

North

Pine

Branch

So

Branch

uth

Cr

Cr

Cr

Gray

Beads

Omaha

Rosebud

Phister

S. Ironwood Creek

Creek

Lone Tree

Creek

Creek

Soldier Creek

Eagletail

Sand Creek

Creek

Creek

Creek

Rock

Spring

Black

Pipe

Creek

Antelope

Antelope

Eagle

Oak

Creek

Cut

Meat

Creek

Creek

Creek

Minnechaduza

Creek

Dry

Creek

2,600

2,650

2,700

2,750

2,800

2,800

2,750

2,700

2,650

2,600

2,550

2,500

2,550

2,850

2,850

2,900

2,900

2,950

2,500

2,500

2,550

3,000

2,450

2,400

2,400

3,050

2,350

2,400

2,800

2,800

2400

2,500

2,600

2,450

2,500

3,000

2,450

2,450

2,500

2,950

2,500

2,450

2,450

2,450

2,550

2,350

101 ̊15' 101 ̊0' 100 ̊45' 100 ̊30' 100 ̊15'

43 ̊

43 ̊15'

43 ̊30'

Base from U.S. Geological Survey digital data 1:100,000, 1980, 1982, 1983, 1985

Universal Transverse Mercator projection, zone 14

0 10 5 MILES

0 10 5 KILOMETERS

EXPLANATION

ACTIVE CELLS IN THE ARIKAREE AQUIFER

2,800 SIMULATED POTENTIOMETRIC CONTOUR—

 Shows average altitude at which water level

 would have stood in tightly cased wells,

 1979-98. Contour interval is 50 feet. Datum

 is NGVD of 1929.
Numerical Model 39

Figure 19. Histograms of residuals of estimated average observed and steady-state simulated hydraulic head 

in A) all wells, B) State observation wells, and C) Tribal observation wells for the Ogallala and Arikaree aquifers, 

water years 1979-98.

0 20 40 60 80 100 120

ABSOLUTE VALUE OF RESIDUAL,

IN FEET

ABSOLUTE VALUE OF RESIDUAL,

IN FEET

ABSOLUTE VALUE OF RESIDUAL,

IN FEET

0 2 4 6 8 10 12 14 16 18 20 22

0

10

20

30

40

0

5

10

15

20

25

0

5

10

15

20

25

FREQUENCY, IN PERCENT FREQUENCY, IN PERCENTFREQUENCY, IN PERCENT

A All wells (398 wells) B State observation wells (23 wells)

C Tribal observation wells (21 wells)

0 15 20 25 30 35 40 45 5 10
40 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 20. Linear regression of observed and simulated hydraulic heads for all wells.

Table 11. Steady-state water budget for numerical simulation compared with flow estimates for conceptual model

[--, not estimated or not applicable]

Flow component Flow rate (cubic feet per second)

Numerical model Conceptual model

Inflows

Storage 0.52 --

Constant-head boundaries 17.90 --

River leakage 2.05 --

Recharge 266.20 111-341

Total inflows 286.67 --

Outflows

Storage 0.74 --

Constant-head boundaries 13.16 --

Irrigation wells 11.60 11.6

Springs along northern boundary 0.50 --

Little White River 146.79 149

Keya Paha River 19.70 23

Other river leakage 11.50 --

Evapotranspiration 183.87 --

Total outflows 287.86 --

Inflows - outflows -1.19 --

Percent discrepancy -0.41 -- 1Includes springflow contributing to base flow in river

OBSERVED HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929

2,400 2,600 2,800 3,000

SIMULATED HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929

2,300

2,400

2,500

2,600

2,700

2,800

2,900

3,000

3,100

R2=0.97
Numerical Model 41

Figure 21. Results of sensitivity analysis.

PERCENTAGE CHANGE IN CALIBRATED VALUE

-80 -60 -40 -20 0 20 40 60 80

PERCENTAGE CHANGE IN SUM OF SQUARED WEIGHTED RESIDUALS

-100

0

100

200

300

400

500

Horizontal hydraulic conductivity

Vertical hydraulic conductivity

Evapotranspiration

Recharge

Riverbed conductance

Transient Simulation

Calibration criteria for the transient simulation 

consisted of approximately reproducing the general 

temporal trends of the hydrographs for the 23 State 

observation wells and 21 Tribal observation wells. 

There was no attempt to calibrate the transient simulation to match hydraulic heads in the observation wells 

closer than that required for the steady-state simulation 

(±50 feet). Therefore, a difference of up to 50 feet 

between the observed and simulated well hydrographs 

was acceptable if the general trends matched reasonably well.

Hydrographs for State and Tribal observation 

wells are shown in figures 22 and 23, which show that 

the general trends in simulated and observed hydraulic 

heads matched reasonably well. Basic statistics were 

calculated for comparison of observed and simulated 

hydraulic heads for observation wells (tables 12 

and 13). The differences of the means of observed and 

simulated data were within 40 feet for all observation 

wells. Comparison of standard deviations, variances, 

and ranges for observed and simulated data are indications of how well the model simulated hydraulic head 

fluctuations for each well. The model overestimated 

hydraulic heads for 13 of the State wells and 8 of the 

Tribal wells. These wells have a negative number in the 

“Difference of observed and simulated means” column. 

The model underestimated hydraulic heads for 10 of 

the State wells and 13 of the Tribal wells. For all observation wells, the model overestimated hydraulic heads 

for 48 percent of the wells and underestimated 

hydraulic heads for 52 percent of the wells. However, 

the mean of the difference of observed and simulated 

means (tables 12 and 13) is -3.7 for State wells, -1.0 for 

Tribal wells, and -2.4 for all observation wells, which 

indicates a model bias toward overestimating hydraulic 

heads.
42 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 22. Hydrographs showing simulated and observed data for State observation wells. HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929

Ogallala aquifer, well 2, 35N29W20AADD Ogallala aquifer, well 87, 36N32W25DDDD 2,830

2,820

2,810

2,800

2,790

2,850

2,840

2,830

2,820

2,810

Ogallala aquifer, well 41, 35N29W7BBBB Ogallala aquifer, well 125, 36N29W16AAAA

CALENDAR YEAR CALENDAR YEAR

Ogallala aquifer, well 80, 36N26W31ADDD Ogallala aquifer, well 126, 36N30W13BBBB

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

Observed

Simulated

2,860

2,850

2,840

2,830

2,820

2,840

2,830

2,820

2,810

2,800

2,620

2,610

2,600

2,590

2,580

2,870

2,860

2,850

2,840

2,830

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated
Numerical Model 43

Figure 22. Hydrographs showing simulated and observed data for State observation wells.—Continued HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929

Ogallala aquifer, well 130, 36N31W14BAAA

Ogallala aquifer, well 175, 37N28W27CCCC

2,840

2,830

2,820

2,810

2,800

2,750

2,740

2,730

2,720

2,710

Ogallala aquifer, well 145, 36N28W10BBBB

CALENDAR YEAR CALENDAR YEAR

Ogallala aquifer, well 160, 37N29W33CCCC

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

2,770

2,760

2,750

2,740

2,730

2,830

2,820

2,810

2,800

2,790

Ogallala aquifer, well 176, 37N29W28DDDD 2,800

2,790

2,780

2,770

2,760

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Ogallala aquifer, well 170, 37N33W32BBBB2 2,930

2,920

2,910

2,900

2,890
44 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 22. Hydrographs showing simulated and observed data for State observation wells.—Continued

Ogallala aquifer, well 194, 37N29W29AAAA 2,810

2,800

2,790

2,780

2,770

Ogallala aquifer, well 201, 37N28W21CCCC

CALENDAR YEAR CALENDAR YEAR

Arikaree aquifer, well 205, 37N29W22CCCC

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

2,750

2,740

2,730

2,720

2,710

2,790

2,780

2,770

2,760

2,750

Ogallala aquifer, well 219, 37N29W16AAAA 2,780

2,770

2,760

2,750

2,740

Ogallala aquifer, well 207, 37N33W17CCCC

2,950

2,940

2,930

2,920

2,910

Ogallala aquifer, well 177, 37N28W30CCCB 2,770

2,760

2,750

2,740

2,730

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated
Numerical Model 45

Figure 22. Hydrographs showing simulated and observed data for State observation wells.—Continued

Arikaree aquifer, well 210, 37N26W16CCBB Arikaree aquifer, well 374, 39N32W3AAAA

Arikaree aquifer, well 384, 40N32W21BBBB

CALENDAR YEAR

CALENDAR YEAR

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

2,540

2,530

2,520

2,510

2,500

2,600

2,590

2,580

2,570

2,560

2,580

2,570

2,560

2,550

2,540

HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929

Arikaree aquifer, well 274, 38N25W30BCBB 2,470

2,460

2,450

2,440

2,430

Arikaree aquifer, well 361, 39N33W15DDDD 2,790

2,780

2,770

2,760

2,750

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated
46 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 23. Hydrographs showing simulated and annual average observed data for Tribal observation wells.

CALENDAR YEAR CALENDAR YEAR

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929

Ogallala aquifer, well 3, 36N31W34DBBC

2,870

2,860

2,850

2,840

2,820

2,830

Simulated

Annual average observed

Ogallala aquifer, well 4, 35N31W17CCDA

Simulated

Annual average observed

2,920

2,910

2,900

2,890

2,880

2,860

2,850

2,840

2,830

2,820

Ogallala aquifer, well 5, 35N30W6DDDD

Simulated

Annual average observed

Ogallala aquifer, well 6, 36N30W21DAAA 2,880

2,870

2,860

2,850

2,840

Simulated

Annual average observed

Ogallala aquifer, well 7, 36N29W29ACAA 2,860

2,850

2,840

2,830

2,820

Simulated

Annual average observed

Ogallala aquifer, well 8, 36N30W36DDDA 2,860

2,850

2,840

2,830

2,820

Simulated

Annual average observed
Numerical Model 47

Figure 23. Hydrographs showing simulated and annual average observed data for Tribal observation wells.—Continued

CALENDAR YEAR CALENDAR YEAR

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929

2,810

2,800

2,790

2,780

2,760

2,770

Ogallala aquifer, well 12, 36N29W2CDCC

Simulated

Annual average observed

Ogallala aquifer, well 11, 36N29W14CDAB 2,820

2,810

2,800

2,790

2,780

Simulated

Annual average observed

Ogallala aquifer, well 9, 35N29W18AAAA 2,860

2,850

2,840

2,830

2,820

Simulated

Annual average observed

Ogallala aquifer, well 10, 35N29W2DDDD

Simulated

Annual average observed

2,820

2,810

2,800

2,790

2,780

Ogallala aquifer, well 13, 37N29W31DACC 2,850

2,840

2,830

2,820

2,810

Simulated

Annual average observed

Ogallala aquifer, well 16, 37N28W34ABDA 2,740

2,730

2,720

2,710

2,700

Simulated

Annual average observed
48 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 23. Hydrographs showing simulated and annual average observed data for Tribal observation wells.—Continued HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929

Ogallala aquifer, well 17, 37N27W18DDAB 2,640

2,630

2,620

2,610

2,600

Simulated

Annual average observed

Ogallala aquifer, well 18, 36N28W12AABA 2,710

2,700

2,690

2,680

2,670

2,660

2,650

Simulated

Annual average observed

Ogallala aquifer, well 19, 36N28W33BDDD 2,750

2,740

2,730

2,720

2,710

Simulated

Annual average observed

Ogallala aquifer, well 20, 35N28W11DBBB

Simulated

Annual average observed

2,740

2,730

2,720

2,710

2,700

Ogallala aquifer, well 21, 35N27W14BAAB

Simulated

Annual average observed

2,680

2,670

2,660

2,650

2,640

Ogallala aquifer, well 22, 36N26W32BBAA 2,620

2,610

2,600

2,590

2,580

Simulated

Annual average observed

CALENDAR YEAR CALENDAR YEAR

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998
Numerical Model 49

Figure 23. Hydrographs showing simulated and annual average observed data for Tribal observation wells.—Continued

Ogallala aquifer, well 27, 37N30W8DACC

CALENDAR YEAR

Ogallala aquifer, well 15, 38N28W36ABCB

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 2,795

2,785

2,775

2,765

2,755

HYDRAULIC HEAD, IN FEET ABOVE NGVD OF 1929 2,620

2,610

2,600

2,590

2,580

Simulated

Annual average observed

Simulated

Annual average observed

Ogallala aquifer, well 23, 36N27W1BDDDD 2,620

2,610

2,600

2,590

2,580

Simulated

Annual average observed
50 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Table 12. Comparison of observed and simulated hydraulic heads for State observation wells for the transient

simulation

[Hydraulic heads in feet above NGVD of 1929. --, not applicable]

State well

number Data type Mean Standarddeviation Variance Range Minimum Maximum

Difference

of observed

and

simulated

means

Average of 

absolute

value of

residuals1

2 Observed 2,804 0.90 0.80 4 2,802 2,806

Simulated 2,825 .81 .66 3 2,824 2,827 -21 20.9

41 Observed 2,837 .47 .22 3 2,835 2,838

Simulated 2,842 .96 .93 4 2,840 2,844 -5 4.9

80 Observed 2,594 1.81 3.26 8 2,590 2,598

Simulated 2,601 .69 0.47 3 2,600 2,603 -7 6.7

87 Observed 2,834 1.31 1.70 7 2,831 2,838

Simulated 2,827 .79 .62 4 2,825 2,829 7 7.3

125 Observed 2,822 1.90 3.60 8 2,817 2,825

Simulated 2,814 2.62 6.88 9 2,809 2,818 8 7.4

126 Observed 2,843 .69 .48 5 2,840 2,845

Simulated 2,850 2.40 5.75 8 2,846 2,854 -7 6.7

130 Observed 2,816 1.46 2.14 6 2,813 2,819

Simulated 2,823 1.25 1.57 5 2,821 2,826 -7 6.9

145 Observed 2,750 1.06 1.12 4 2,748 2,752

Simulated 2,742 1.75 3.05 8 2,737 2,745 8 8.7

160 Observed 2,817 2.04 4.17 11 2,810 2,821

Simulated 2,802 4.34 18.86 15 2,793 2,808 15 15.4

175 Observed 2,727 .95 .91 7 2,722 2,729

Simulated 2,735 2.03 4.12 8 2,731 2,739 -8 8.1

176 Observed 2,791 2.87 8.26 11 2,785 2,796

Simulated 2,783 6.63 43.99 29 2,765 2,794 8 7.5

177 Observed 2,745 1.09 1.20 5 2,742 2,747

Simulated 2,761 2.62 6.88 10 2,756 2,766 -16 16.2

194 Observed 2,790 2.38 5.68 10 2,784 2,794

Simulated 2,788 4.62 21.34 16 2,779 2,795 2 3.1

201 Observed 2,726 1.31 1.71 6 2,723 2,729

Simulated 2,733 2.43 5.89 11 2,728 2,739 -7 7.0
Numerical Model 51

207 Observed 2,930 1.06 1.12 5 2,928 2,933

Simulated 2,929 .64 .41 3 2,927 2,930 1 1.6

219 Observed 2,754 1.55 2.40 8 2,749 2,757

Simulated 2,773 3.76 14.12 11 2,767 2,778 -19 18.9

170 Observed 2,902 .44 .20 3 2,900 2,903

Simulated 2,906 .36 .13 2 2,906 2,908 -4 4.6

205 Observed 2,781 2.39 5.70 9 2,776 2,785

Simulated 2,777 3.45 11.90 10 2,772 2,782 4 3.7

210 Observed 2,523 2.81 7.89 11 2,517 2,528

Simulated 2,522 .62 .38 3 2,520 2,523 1 2.7

274 Observed 2,458 2.08 4.31 9 2,453 2,462

Simulated 2,454 .73 .54 3 2,453 2,456 4 3.4

361 Observed 2,763 2.37 5.60 20 2,760 2,780

Simulated 2,784 1.48 2.20 6 2,782 2,788 -21 21.4

374 Observed 2,578 3.06 9.39 12 2,574 2,586

Simulated 2,589 1.38 1.92 7 2,586 2,593 -11 11.1

384 Observed 2,561 5.25 27.56 22 2,552 2,574

Simulated 2,570 .86 .74 5 2,568 2,573 -9 8.8

Mean -- -- -- -- -- -- -- -3.7 8.8

1

The residual is the difference of the observed and simulated value.

Table 12. Comparison of observed and simulated hydraulic heads for State observation wells for the transient

simulation–Continued

[Hydraulic heads in feet above NGVD of 1929. --, not applicable]

State well

number Data type Mean Standard

deviation Variance Range Minimum Maximum

Difference

of observed

and

simulated

means

Average of 

absolute

value of

residuals1
52 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Table 13. Comparison of observed and simulated hydraulic heads for Tribal observation wells for the transient

simulation

[Observed data based on annual averages. Hydraulic heads in feet above NGVD of 1929. --, not applicable]

Tribal

well

number

Data type Mean Standard 

deviation Variance Range Minimum Maximum

Difference of

observed and

simulated

means

3 Observed 2,826 .89 .80 3 2,825 2,828

Simulated 2,865 1.67 2.79 7 2,862 2,869 -39

4 Observed 2,896 .64 .41 3 2,895 2,898

Simulated 2,892 .85 .71 3 2,891 2,894 4

5 Observed 2,844 .59 .34 3 2,842 2,845

Simulated 2,831 .82 .68 3 2,830 2,833 13

6 Observed 2,853 1.52 2.30 5 2,851 2,856

Simulated 2,858 .80 .64 4 2,856 2,860 -5

7 Observed 2,834 1.75 3.05 7 2,830 2,837

Simulated 2,851 1.69 2.87 7 2,845 2,852 -17

8 Observed 2,843 .90 .81 3 2,842 2,845

Simulated 2,836 2.98 8.90 12 2,827 2,839 7

9 Observed 2,836 .73 .54 3 2,835 2,838

Simulated 2,832 7.45 55.56 22 2,824 2,846 4

10 Observed 2,793 .51 .26 2 2,792 2,794

Simulated 2,792 1.11 1.23 3 2,791 2,794 1

11 Observed 2,795 3.29 10.83 10 2,790 2,800

Simulated 2,810 3.83 14.65 13 2,804 2,817 -15

12 Observed 2,770 3.83 14.70 13 2,762 2,775

Simulated 2,804 1.54 2.38 5 2,801 2,806 -34

13 Observed 2,831 6.93 47.99 28 2,814 2,842

Simulated 2,815 1.71 2.94 5 2,813 2,818 16

16 Observed 2,726 2.50 6.24 10 2,721 2,731

Simulated 2,725 1.32 1.75 5 2,724 2,729 1

17 Observed 2,622 1.58 2.49 5 2,620 2,625

Simulated 2,604 1.09 1.18 4 2,602 2,606 18

18 Observed 2,700 .90 .81 3 2,698 2,701

Simulated 2,660 1.40 1.97 5 2,657 2,662 40

19 Observed 2,735 .55 .30 2 2,734 2,736

Simulated 2,724 .77 .59 2 2,723 2,725 11

20 Observed 2,716 .45 .21 2 2,715 2,717

Simulated 2,711 1.81 3.28 6 2,708 2,714 5
Numerical Model 53

21 Observed 2,644 1.15 1.31 4 2,642 2,646

Simulated 2,671 1.43 2.04 5 2,669 2,674 -27

22 Observed 2,591 .76 .58 3 2,590 2,593

Simulated 2,589 1.58 2.50 5 2,587 2,592 2

23 Observed 2,590 .75 .56 3 2,589 2,592

Simulated 2,600 2.21 4.89 8 2,597 2,605 -10

27 Observed 2,789 1.34 1.78 5 2,787 2,792

Simulated 2,759 3.08 9.50 13 2,756 2,769 30

15 Observed 2,583 0.98 0.96 3 2,582 2,585

Simulated 2,609 1.04 1.09 4 2,606 2,610 -26

Mean -- -- -- -- -- -- -- -1.0

Table 13. Comparison of observed and simulated hydraulic heads for Tribal observation wells for the transient

simulation–Continued

[Observed data based on annual averages. Hydraulic heads in feet above NGVD of 1929. --, not applicable]

Tribal

well

number

Data type Mean Standard 

deviation Variance Range Minimum Maximum

Difference of

observed and

simulated

means

The simulated base flow from ground-water discharge for the Ogallala and Arikaree aquifers had less 

fluctuation between stress periods than did the estimated base flow (fig. 24), which corresponds with the 

data in table 5. This may represent limitations of either 

base-flow estimates or the model or both. The average 

simulated base flow was within 8 percent of the 

average of estimated values for the Little White River 

and within 13 percent for the Keya Paha River 

(table 14). The simulated base flow for the Little White 

River included springs within the Little White River 

Basin above Soldier Creek, which were assumed to 

contribute base flow to the river.

Model Limitations

The numerical model adequately simulates flow 

in the Ogallala and Arikaree aquifers in the study area 

for the purposes and objectives of this study; however, 

water managers should be aware of the model’s limitations. There are uncertainties in many model input 

parameters, most importantly recharge, evapotranspiration, and horizontal and vertical hydraulic conductivity. 

Although these parameters had a major influence on 

model results, extensive data were not available. The 

combination of parameter values used in this model 

were based on many considerations. The parameter 

values were chosen within the general ranges of previously published values, and therefore, the model’s 

accuracy is dependent, in part, on the accuracy of those 

estimates. Calibration of the model possibly could be 

improved by breaking down further the spatial discretization of some parameters, such as hydraulic conductivity or recharge; however, without more field data, 

finer discretization was not justifiable. In this case, a 

simpler model adequately represented the system. The 

degree of discretization and the parameter values 

chosen for this model were a balance between that 

based on calibration and that based on available parameter data; however, combinations of parameter values 

other than that used in this model also may give 

satisfactory results.

Table 14. Comparison of average simulated and estimated 

base flow for the Little White and Keya Paha Rivers for the 

transient-state simulation, water years 1979-98

Stream

Base flow

(cubic feet per second)

Percent error

of simulated

to estimated

Estimated base flow 1

1From table 5.

Model

simulation

Little White River 49 45 8

Keya Paha River 23 20 13
54 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Figure 24. Comparison of estimated and simulated base flow for the Little White and Keya Paha Rivers.

CALENDAR YEAR CALENDAR YEAR

RIVER GAIN,

IN CUBIC FEET PER SECOND

Little White River Keya Paha River

0

20

40

60

80

100

0

20

40

60

80

100

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

Estimated base flow

Simulated base flow

Estimated base flow

Simulated base flow

This numerical model is suitable as a tool to help 

understand the flow system, to confirm that previous 

estimates of aquifer properties are reasonable, and to 

estimate aquifer properties in areas without data. 

Limitations of the model should be taken into account 

when applying the model to water management. With 

additional data, further refinement of the model would 

be possible, which could improve the accuracy of 

model prediction of the effects of additional stresses on 

the system, such as increased withdrawals or drought.

SUMMARY

The Ogallala and Arikaree aquifers are important 

water resources in the Rosebud Indian Reservation area 

and are used extensively for irrigation, municipal, and 

domestic water supplies. Continued or increased withdrawals from the Ogallala and Arikaree aquifers in the 

Rosebud Indian Reservation area have the potential to 

affect water levels in these aquifers. A water-resource 

tool was needed to evaluate management and environmental issues associated with the Ogallala and Arikaree 

aquifers, such as planning for source-water protection, 

describing potential impacts of contamination, and estimating sustainable aquifer withdrawals. To address this 

need, the U.S. Geological Survey (USGS) has worked 

in cooperation with the Rosebud Sioux Tribe to develop 

a numerical model to simulate ground-water flow in the 

Ogallala and Arikaree aquifers in the Rosebud Indian 

Reservation area. This report describes a conceptual 

model of ground-water flow in the aquifers and documents the development and calibration of a numerical 

model to simulate ground-water flow. Data for a 

twenty-year period (water years 1979 through 1998) 

were analyzed for the conceptual model. Steady-state 

and transient simulations were performed for the same 

20-year period.

Areal recharge to the Ogallala and Arikaree aquifers occurs from precipitation on the outcrop areas, and 

regional flow enters the study area from the west. 

Ground water from areal recharge moves from areas of 

higher altitude toward streams that gain flow from the 

Ogallala and Arikaree aquifers. Discharge from the 

Ogallala and Arikaree aquifers occurs through evapotranspiration, discharge to streams, and well withdrawals. Evapotranspiration generally occurs in 

topographically low areas and along streams, and maximum evapotranspiration occurs when the water level is 

at the land surface.

Seepage runs were conducted in the study area to 

obtain information describing streamflow gains in the 

study area. Base flow was estimated at gaging stations 

using a hydrograph separation method. The 20-year 

average estimated base flow was 49 cubic feet per 
References 55

second for the Little White River and 23 cubic feet per 

second for the Keya Paha River. 

Well withdrawals in the study area occur from 

irrigation, domestic, and stock wells. Withdrawals for 

domestic and stock uses were assumed to be negligible 

compared with irrigation use. The 20-year average estimated irrigation withdrawal was 11.6 cubic feet per 

second.

The conceptual model of ground-water flow was 

simulated with a numerical model with two aquifer 

layers using MODFLOW-2000. The upper layer represented the Ogallala aquifer, and the lower layer represented the Arikaree aquifer. The study area was divided 

into grid blocks 1,640 feet (500 meters) on a side, with 

153 rows and 180 columns. Combinations of constanthead and no-flow boundaries were used to best represent boundary conditions.

Estimated horizontal hydraulic conductivity used 

for the numerical model ranged from 0.2 to 120 feet per 

day in the Ogallala aquifer and 0.1 to 5.4 feet per day in 

the Arikaree aquifer. A uniform vertical hydraulic conductivity value of 6.6x10-4 feet per day was applied to 

the Ogallala aquifer. Vertical hydraulic conductivity 

was estimated for five zones in the Arikaree aquifer and 

ranged from 8.6x10-6 to 7.2x10-1 feet per day.

The recharge rate for the steady-state simulation 

was 3.3 and 1.7 inches per year for the Ogallala and 

Arikaree aquifers, respectively, for a total recharge rate 

of 266 cubic feet per second. Discharge rates in cubic 

feet per second for the steady-state simulation were 184 

for evapotranspiration, 46.8 and 19.7 for base flow to 

the Little White and Keya Paha Rivers, respectively, 

and 11.6 for well withdrawals from irrigation.

Model calibration was accomplished by varying 

the model parameters within plausible ranges to produce the best fit between simulated and observed 

hydraulic heads in the Ogallala and Arikaree aquifers. 

Steady-state simulations representing average conditions over the 20-year analysis period were analyzed to 

determine the optimum combination of model parameters. The potentiometric surface calculated from the 

steady-state simulation established initial conditions 

for the transient simulation. Water-level measurements 

were available for 354 public and private wells, 23 State 

observation wells, and 21 Tribal observation wells. 

Calibration criteria for the steady-state simulation included: (1) generally matching the simulated 

potentiometric surfaces and hydraulic gradients to 

those of the estimated potentiometric surfaces, and (2) 

matching hydraulic heads at 95 percent of the wells to 

within ±50 feet of the observed hydraulic heads. 

Calibration criteria for the transient simulation 

included matching the general trends of the 23 State 

observation well hydrographs and 21 Tribal observation well hydrographs. There was no attempt to calibrate the well hydrographs closer than that required by 

the steady-state model (±50 feet). Results of the 

steady-state and transient simulations were within the 

calibration criteria established to meet the objectives 

of the study.

A sensitivity analysis was used to examine the 

response of the numerical model calibrated to steadystate conditions to changes in model parameters 

including horizontal and vertical hydraulic conductivity, evapotranspiration, recharge, and riverbed conductance, which were increased and decreased for the 

sensitivity analysis. The model was most sensitive to 

recharge and horizontal hydraulic conductivity.

REFERENCES

Bradley, Edward, 1956, Geology and ground-water 

resources of the Upper Niobrara River Basin, 

Nebraska and Wyoming: U.S. Geological Survey 

Water-Supply Paper 1368, 70 p.

Carter, J.M., 1998, Water resources of Mellette and Todd 

Counties, South Dakota: U.S. Geological Survey 

Water-Resources Investigations Report 98-4146, 68 p.

Ellis, M.J., Ficken, J.H., and Adolphson, D.G., 1971, 

Hydrology of the Rosebud Indian Reservation, South 

Dakota: U.S. Geological Survey Hydrologic Investigations Atlas HA-335, 2 sheets, scale 1:100,000.

Farnsworth, R.K., Thompson, E.S., and Peck, E.L., 1982, 

Evaporation atlas for the contiguous 48 United 

States: National Oceanic and Atmospheric Administration Technical Report NWS 33, 26 p.

Fenneman, N.M., 1946, Physical divisions of the United 

States: U.S. Geological Survey map prepared in cooperation with the Physiographic Commission, U.S. 

Geological Survey, scale 1:700,000 (reprinted 1964).

Flint, R.F., 1955, Pleistocene geology of eastern South 

Dakota: U.S. Geological Survey Professional Paper 

262, 173 p.

Greene, E.A., Anderson, M.T., and Sipe, D.D., 1991, Aquifer tests and water-quality analyses of the Arikaree 

Formation near Pine Ridge, South Dakota: U.S. 

Geological Survey Water-Resources Investigations 

Report 91-4005, 45 p.
56 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

Gutentag, E.D., Heimes, F.J., Krothe, N.C., Luckey, R.R., 

and Weeks, J.B., 1984, Geohydrology of the High 

Plains aquifer in parts of Colorado, Kansas, Nebraska, 

New Mexico, Oklahoma, South Dakota, Texas, and 

Wyoming: U.S. Geological Survey Professional Paper 

1400-B, 63 p.

Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, 

M.G., 2000, Modflow-2000, the U.S. Geological 

Survey modular ground-water model—User guide to 

modularization concepts and the ground-water flow 

process: U.S. Geological Survey Open-File Report 

00-92, 121 p.

Kolm, K.E., and Case, H.L., III, 1983, A two-dimensional, 

finite-difference model of the High Plains aquifer in 

southern South Dakota: U.S. Geological Survey WaterResources Investigations Report 83-4175, 34 p.

Kremlin-Smith, D.J., 1984, Hydrogeology of a portion of the 

Ogallala aquifer, south-central Todd County, South 

Dakota: Rapid City, South Dakota School of Mines and 

Technology, unpublished M.S. Thesis, 77 p.

Langbein, W.B., 1949, Annual runoff in the United States: 

U.S. Geological Survey Circular 52, 14 p.

Luckey, R.R., Gutentag, E.D., and Weeks, J.B., 1981, Waterlevel and saturated-thickness changes, predevelopment 

to 1980, in the High Plains aquifer in parts of Colorado, 

Kansas, Nebraska, New Mexico, Oklahoma, South 

Dakota, Texas, and Wyoming: U.S. Geological Survey 

Hydrologic Investigations Atlas HA-652, 2 sheets, 

scale 1:2,500,000.

McDonald, M.G., and Harbaugh, A.W., 1988, A modular 

three-dimensional finite-difference ground-water flow 

model: U.S. Geological Survey Techniques of WaterResources Investigations, book 6, chap. A1 [variously 

paged].

McGuinness, C.L., 1963, The role of ground water in the 

national water situation: U.S. Geological Survey 

Water-Supply Paper 1800, 1,121 p.

McGuire, V.L., 2001, Water-level changes in the High Plains 

aquifer, 1980 to 1999: U.S. Geological Survey Fact 

Sheet FS-029-01, 2 p.

Newport, T.G., 1959, Ground-water resources of the Lower 

Niobrara River and Ponca Creek Basins, Nebraska and 

South Dakota: U.S. Geological Survey Water-Supply 

Paper 1460-G, p. 272-323, 3 pl.

Rahn, P.H., and Paul, H.A., 1975, Hydrogeology of a portion 

of the Sand Hills and Ogallala aquifer, South Dakota 

and Nebraska: Ground Water, v. 13, no. 5, p. 428-437.

Sipe, D.D., 1989, Hydrogeology of part of the Arikaree aquifer near Pine Ridge, South Dakota: Rapid City, South 

Dakota School of Mines and Technology, unpublished 

M.S. Thesis, 81 p.

Sloto, R.A., and Crouse, M.Y., 1996, HYSEP—A computer 

program for streamflow hydrograph separation and 

analysis: U.S. Geological Survey Water-Resources 

Investigations Report 96-4040, 46 p.

Springer, R.F., 1974, Soil survey of Todd County, South 

Dakota: U.S. Department of Agriculture, 89 p.

U.S. Department of Commerce, 1978-98, Climatological 

data, annual summary, South Dakota, 1998: Asheville, 

North Carolina, 1978 to 1998 (published annually).

U.S. Geological Survey, 1955, Martin, South Dakota: U.S. 

Geological Survey Topographic Map, scale 1:250,000.

———1996, The National Water-Use Program downloading water-use information: U.S. Geological Survey 

data available on the World Wide Web, accessed 

April 2, 2002, at URL 

http://water.usgs.gov/watuse/wudownload.html 

———2001, Downloading 1995 water-use data: U.S. 

Geological Survey data available on the World Wide 

Web, accessed April 2, 2002, at URL 

http://water.usgs.gov/watuse/spread95.html

Weeks, J.B., Gutentag, E.D., Heimes, F.J., and Luckey, R.R., 

1988, Summary of the High Plains Regional AquiferSystem Analysis in parts of Colorado, Kansas, 

Nebraska, New Mexico, Oklahoma, South Dakota, 

Texas, and Wyoming: U.S. Geological Survey Professional Paper 1400-A, 30 p.
SUPPLEMENTAL INFORMATION

Supplemental Information - Table 15 59

 Table 15. Wells used for estimating potentiometric surface of the Ogallala aquifer

[Well locations are shown in figure 4. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of 1929)

Average

hydraulic

head altitude

(feet above

NGVD of 1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 9)

430239100174301 35N25W 5BBAA 430242 1001731 2,518 2,509.5 --

430200100164801 35N25W 5DDD 430200 1001648 2,501 2,495.5 --

430151100173901 35N25W 8BB 430139 1001730 2,513 2,495.5 --

430023100115602 35N25W13DADD2 430023 1001156 2,443 2,433.9 --

430002100174801 35N25W20BBBC 430002 1001748 2,493 2,488.6 --

430237100241201 35N26W 5BA 430237 1002419 2,635 2,603.1 --

430126100222001 35N26W10CBBA2 430126 1002220 2,618 2,572.8 --

430033100203001 35N26W14DB 430028 1002036 2,530 2,520.4 --

430040100233901 35N26W17DAB 430033 1002349 2,583 2,576.3 --

430006100254301 35N26W19BBAC 430004 1002545 2,660 2,623.4 --

430236100274201 35N27W 2ABCC 430232 1002740 2,700 2,628.3 --

430215100273301 35N27W 2DBCC 430207 1002742 2,695 2,658.3 --

430245100292801 35N27W 3BBBB 430245 1002928 2,671 2,660.2 --

430230100320301 35N27W 6AAC 430235 1003205 2,710 2,679.1 --

430121100323001 35N27W 7CACB 430119 1003245 2,724 2,698.1 --

430115100322101 35N27W 7DACC 430115 1003208 2,731 2,705.1 --

430119100291801 35N27W10CBBB 430124 1002909 2,717 2,685.6 --

430103100280601 35N27W11CCDC 430102 1002806 2,682 2,650.5 --

430106100271403 35N27W11DD 430106 1002714 2,637 2,623.4 --

430139100264401 35N27W12B 430139 1002644 2,636 2,619.3 --

430057100275401 35N27W14BAAB 430100 1002751 2,690 2,671.0 T21

430022100270901 35N27W14DAA 430022 1002709 2,676 2,666.4 --

430039100301001 35N27W16BD 430039 1003010 2,695 2,677.8 --

430039100320801 35N27W18A 430039 1003208 2,725 2,709 --

430122100344501 35N28W11DBBB 430126 1003446 2,728 2,711.2 T20

430055100362702 35N28W15BBBD2 430055 1003627 2,754 2,744.2 --

430154100411801 35N29W 2DDDD 430156 1004118 2,800 2,792.0 T10

430156100411901 35N29W 2DDDD2 430156 1004119 2,800 2,791.2 --

430238100434801 35N29W 4AA 430238 1004348 2,830 2,810 --

430226100445203 35N29W 4BCCB3 430225 1004450 2,845 2,828.9 --

430148100471001 35N29W 7BBBB 430151 1004711 2,903 2,837.3 S41

430151100415402 35N29W11ABBB2 430151 1004154 2,800 2,779.7 --

430100100460501 35N29W18AAAA 430100 1004604 2,870 2,831.4 T9

425957100445601 35N29W20AADD 425957 1004453 2,890 2,804.3 S2

430212100524001 35N30W 5CA 430212 1005240 2,828 2,808.7 --
60 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

430153100521303 35N30W 5DDCC3 430153 1005213 2,842 2,821.5 --

430217100535201 35N30W 6CABA 430217 1005352 2,873 2,833.7 --

430159100531001 35N30W 6DDDD 430153 1005309 2,853 2,831.6 T5

430139100474801 35N30W12ACBB 430139 1004748 2,935 2,875.3 --

430037100471601 35N30W13ADD 430037 1004716 2,895 2,784.8 --

430045100495701 35N30W15ACA 430045 1004957 2,880 2,850 --

430231100591501 35N31W 5AACC 430231 1005915 2,865 2,849.8 --

430120100574901 35N31W10CBBC 430120 1005749 2,823 2,817.9 --

430042100565801 35N31W15ACA 430042 1005658 2,822 2,814.7 --

430017100595101 35N31W17CCDA 430014 1005947 2,896 2,892.5 T4

430113101062401 35N32W 8D 430111 1010624 2,980 2,974.6 --

430152101054803 35N32W 9BABB3 430152 1010548 2,935 2,927.5 --

430047101025001 35N32W14A 430047 1010250 2,982 2,912.7 --

430028101111701 35N33W15DB 430028 1011117 3,060 3,035.4 --

425956101134503 35N33W20ABCC3 425956 1011345 3,050 3,032.4 --

430704100145901 36N25W10BABB 430704 1001459 2,442 2,420.8 --

430348100172001 36N25W29CDAC 430344 1001720 2,573 2,525.5 --

430315100184301 36N25W31BDCB 430315 1001843 2,552 2,530.4 --

430331100153301 36N25W33AA 430331 1001533 2,585 2,513.6 --

430454100255101 36N26W19BBC 430454 1002551 2,650 2,608.3 --

430515100225001 36N26W21AAB 430517 1002238 2,585 2,543.3 --

430310100245501 36N26W31ADDD 430312 1002455 2,620 2,594.4 S80

430335100241401 36N26W32BBAA 430337 1002431 2,619 2,589.2 T22

430246100222302 36N26W34CCC2 430246 1002223 2,634 2,607.2 --

430728100135801 36N27W 1BDDD 430735 1002632 2,627 2,600.0 T23

430721100290001 36N27W 3CA 430721 1002900 2,663 2,602.2 --

430705100304701 36N27W 5DDD 430709 1003045 2,600 2,579.4 --

430512100291801 36N27W15CC 430527 1002920 2,698 2,621.9 --

430458100300901 36N27W21BDDB 430500 1003013 2,664 2,613 --

430737100350602 36N28W 2BDAC2 430740 1003453 2,773 2,676.7 --

430719101380501 36N28W 5DACC 430718 1003804 2,818 2,782.9 --

430604100390801 36N28W 7DDB 430624 1003911 2,829 2,793.1 --

430649100364801 36N28W 9ADDA 430643 1003638 2,805 2,764.2 --

430701100363001 36N28W10BBBB 430705 1003635 2,823 2,750.3 S145

430700100344501 36N28W11ABB 430703 1003444 2,807 2,706.6 --

Table 15. Wells used for estimating potentiometric surface of the Ogallala aquifer–Continued

[Well locations are shown in figure 4. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of 1929)

Average

hydraulic

head altitude

(feet above

NGVD of 1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 9)
Supplemental Information - Table 15 61

430702100330501 36N28W12AABA 430706 1003313 2,806 2,659.8 T18

430618100330301 36N28W12DD 430620 1003310 2,675 2,668.8 --

430614100362503 36N28W15BABB3 430614 1003625 2,778 2,753 --

430601100364501 36N28W16ABCA 430607 1003705 2,805 2,779.4 --

430515100331201 36N28W24AAA 430518 1003306 2,685 2,664.8 --

430406100380701 36N28W29ACDC 430405 1003810 2,771 2,756.4 --

430403100395001 36N28W30BCDD 430403 1003950 2,820 2,800.8 --

430348100390401 36N28W30DDAB 430348 1003904 2,792 2,772.7 --

430314100392301 36N28W31ACDC 430314 1003923 2,839 2,819.1 --

430243100371701 36N28W33BDDD 430311 1003712 2,753 2,723.0 T19

430712100421301 36N29W 2CDCC 430706 1004208 2,850 2,804.3 T12

430714100445001 36N29W 4CCBC 430715 1004448 2,853 2,816.4 --

430624100461601 36N29W 7DDB 430624 1004616 2,925 2,889.7 --

430659100434901 36N29W 9AA 430659 1004349 2,845 2,777.8 --

430629100434401 36N29W 9DAD 430629 1004344 2,885 2,817.4 --

430530100422501 36N29W14CDAB 430528 1004158 2,893 2,810.8 T11

430522100411902 36N29W14DDDD2 430522 1004119 2,884 2,814.9 --

430558100430301 36N29W15ACBB 430558 1004303 2,884 2,866.4 --

430609100434201 36N29W16AAAA 430613 1004346 2,863 2,821.7 S125

430604100445201 36N29W17AADD1 430604 1004453 2,905 2,822.9 --

430603100460501 36N29W18AADD 430603 1004605 2,940 2,849.9 --

430450100453701 36N29W20CA 430450 1004537 2,868 2,845.4 --

430508100431901 36N29W22BBDD 430508 1004319 2,911 2,830.6 --

430415100451401 36N29W29ACAA 430415 1004512 2,870 2,850.8 T7

430305100455401 36N29W32CB 430305 1004554 2,835 2,823.3 --

430252100431301 36N29W34CD 430252 1004313 2,804 2,794.2 --

430302100412001 36N29W35DAD 430302 1004120 2,834 2,818.5 --

430723100512101 36N30W 4DBCB 430723 1005121 2,978 2,871.7 --

430652100484001 36N30W11ADBB 430652 1004840 2,949 2,850.5 --

430615100472701 36N30W12DDCD 430615 1004723 2,960 2,826.6 --

430610100481701 36N30W13BBBB 430613 1004820 2,916 2,843.4 S126

430518100533701 36N30W19ABB 430518 1005337 2,902 2,854.9 --

430501100504901 36N30W21DAAA 430453 1005045 2,888 2,858.3 T6

430507100483701 36N30W23ADBB 430507 1004837 2,934 2,848.4 --

430342100482901 36N30W26DDDB 430342 1004829 2,851 2,831.9 --

Table 15. Wells used for estimating potentiometric surface of the Ogallala aquifer–Continued

[Well locations are shown in figure 4. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of 1929)

Average

hydraulic

head altitude

(feet above

NGVD of 1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 9)
62 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

430250100532701 36N30W31DCDA 430250 1005327 2,868 2,848.8 --

430327100512301 36N30W33BADD 430327 1005123 2,945 2,853.8 --

430334100515201 36N30W33BBB 430334 1005152 2,896 2,842.8 --

430254100515001 36N30W33CCBD 430254 1005150 2,879 2,855.7 --

430258100471401 36N30W36DDDA 430250 1004712 2,885 2,836.1 T8

430721100563001 36N31W 2CB 430721 1005630 2,934 2,784.8 --

430613101561701 36N31W14BAAA 430613 1005606 2,955 2,816.3 S130

430541100555501 36N31W14DB 430541 1005555 2,970 2,870.8 --

430555100570301 36N31W15ACAC 430555 1005703 3,005 2,915.8 --

430603101003401 36N31W18ABDD 430603 1010034 2,877 2,838.8 --

430309100570901 36N31W34DBBC 430306 1005714 2,920 2,864.8 T3

430458101042001 36N32W22CADA 430458 1010420 2,850 2,820.7 --

430426101020201 36N32W25BAA 430426 1010202 2,845 2,810.8 --

430340101012301 36N32W25DDDD 430340 1010123 2,841 2,833.9 S87

431236100172601 37N25W 4BCCA 431236 1001726 2,467 2,386.1 --

430932100262401 37N26W19DCC 430932 1002624 2,655 2,584.2 --

431027100333001 37N27W18DDAB 431035 1003306 2,609 2,604.5 T17

430909100333501 37N27W30BDDA 430909 1003335 2,722 2,662.1 --

431159100412103 37N28W 7BBBC3 431159 1004121 2,793 2,715.8 --

431021100384701 37N28W16CCDD 431024 1003845 2,744 2,714.4 --

430956100402901 37N28W19ACDD 430956 1004029 2,800 2,772.5 --

430932100390001 37N28W21CCCC 430930 1003858 2,772 2,726.6 S201

430839100373801 37N28W27CCCC 430839 1003745 2,805 2,726.6 S175

430907100401001 37N28W30ADDA 430907 1004010 2,757 2,741.5 --

430842100411301 37N28W30CCCB 430841 1004119 2,770 2,744.9 S177

430820100371401 37N28W34ABDA 430828 1003655 2,783 2,725.1 T16

430809100372401 37N28W34BDA 430725 1003715 2,800 2,740.4 --

431212100472901 37N29W 6DDBD 431212 1004727 2,868 2,739.8 --

431138100441601 37N29W10DBBB 431136 1004414 2,818 2,755.5 --

431141100422501 37N29W12BCDD 431141 1004215 2,825 2,761.5 --

431133100402201 37N29W13CBCD 431133 1004222 2,796 2,731.7 --

431109100445901 37N29W16AAAA 431112 1004457 2,852 2,753.6 S219

431100100461601 37N29W17AACD 431106 1004604 2,845 2,767.7 --

430920100444801 37N29W27BBCA 430920 1004448 2,877 2,810.4 --

430852100435001 37N29W27DACD 430850 1004348 2,825 2,768.1 --

Table 15. Wells used for estimating potentiometric surface of the Ogallala aquifer–Continued

[Well locations are shown in figure 4. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of 1929)

Average

hydraulic

head altitude

(feet above

NGVD of 1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 9)
Supplemental Information - Table 15 63

430909100452701 37N29W28ACBC 430905 1004527 2,880 2,803.4 --

430840100445601 37N29W28DDDD 430837 1004454 2,858 2,790.7 S176

430924100460601 37N29W29AAAA 430927 1004607 2,868 2,790.1 S194

430836100464301 37N29W29CDDD 430836 1004641 2,870 2,800.8 --

430755100582301 37N29W31DACC 430757 1004729 2,921 2,815.4 T13

430748100455601 37N29W33CCCC 430745 1004601 2,909 2,817.2 S160

431127100532801 37N30W 8DACC 431114 1005333 2,880 2,759.4 T27

431033100493201 37N30W13CBCD 431033 1004932 2,783 2,766.1 --

430910100490201 37N30W25ACBC 430911 1004902 2,899 2,882.2 --

430912100542301 37N30W29BCBB 430912 1005421 2,997 2,812.3 --

430848100544001 37N30W30DDBC 430842 1005437 2,980 2,778.2 --

430831100580301 37N31W25CCCB 430831 1005803 2,970 2,776.9 --

431200101034801 37N32W11ABA 431157 1010356 3,060 2,876.3 --

430907101073801 37N32W29ACB 430907 1010738 2,910 2,882.1 --

431222101093501 37N33W 1DAA 431222 1010954 3,104 3,008.8 --

431148101165001 37N33W 7ABD 431154 1011544 3,018 2,947.4 --

431156101105801 37N33W11AAB 431157 1011052 3,153 3031.6 --

431018101132301 37N33W16DCDC 431018 1011323 3,023 2,955.4 --

431018101152001 37N33W17CCCC 431018 1011520 2,998 2,930.3 S207

430929101104203 37N33W26AAAA3 430929 1011042 2,953 2,875.8 --

431432101123401 37N33W27BAA 430921 1011230 2,978 2,917.5 --

430836101152201 37N33W32BBBB 430836 1011522 2,960 2,894.8 --

430825101151801 37N33W32BBBB2 430834 1011518 2,960 2,901.8 S170

431250101163701 37N34W 1AAAA 431250 1011637 3,113 2,959.9 --

431540100154501 38N25W15DCCB 431540 1001545 2,467 2,406.2 --

431509100185901 38N25W19ADCC 431509 1001859 2,530 2,504.3 --

431327100164501 38N25W33ACD 431327 1001645 2,475 2,466.1 --

431716100212001 38N26W11AAB 431716 1002120 2,651 2,600.8 --

431532100200101 38N26W24AAAB 431532 1002001 2,503 2,467.3 --

431714100364101 38N28W20AAAD 431524 1003906 2,700 2,646.4 --

431427100375201 38N28W28ADAA 431427 1003754 2,781 2,729.1 --

431354100375201 38N28W28DDDD 431351 1003753 2,781 2,749.8 --

431435100414101 38N29W25AACB 431433 1004130 2,663 2,646.9 --

431318100532301 38N30W32DAAB 431318 1005321 2,838 2,818.3 --

431550100590501 38N31W16CABD 431550 1005905 2,747 2,743 --

Table 15. Wells used for estimating potentiometric surface of the Ogallala aquifer–Continued

[Well locations are shown in figure 4. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of 1929)

Average

hydraulic

head altitude

(feet above

NGVD of 1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 9)
64 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

 Table 16. Wells used for estimating potentiometric surface of the Arikaree aquifer

[Well locations are shown in figure 5. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of

1929)

Adjusted

hydraulic

head altitude

(feet above

NGVD of

1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 10)

430242100184801 35N25W 6BBA 430242 1001842 2,525 2,513.4 --

430003100174802 35N25W20BBBC3 430003 1001748 2,493 2,488.1 --

430204100212001 35N26W 3DDAB 430204 1002120 2,617 2,593.1 --

430216100252101 35N26W 6DBBA 430216 1002517 2,620 2,558.3 --

430127100230601 35N26W 9BDAD 430135 1002320 2,585 2,558.3 --

430126100221901 35N26W10CBBA3 430126 1002219 2,617 2,569.1 --

430033100234902 35N26W17DAB2 430033 1002349 2,583 2,565.4 --

430245100292701 35N27W 3BBBB4 430245 1002927 2,671 2,659.9 --

430106100271402 35N27W11DD2 430106 1002714 2,637 2,610.7 --

430000100285401 35N27W22ABBC 430003 1002855 2,679 2,668.1 --

430154100332601 35N28W 1DC 430154 1003326 2,683 2,673.1 --

430217100370801 35N28W 4ACCB 430224 1003707 2,753 2,719.4 --

430613100352901 35N28W14AAAA 430102 1003415 2,735 2,722 --

430226100445201 35N29W 4BCCB 430226 1004452 2,845 2,832.2 --

430225100445401 35N29W 5DDDA 430157 1004454 2,880 2,783.1 --

430048100450201 35N29W17AACD 430048 1004502 2,913 2,830.8 --

430014100445401 35N29W17DDDA 430014 1004454 2,878 2,850.6 --

430113100491601 35N30W11C 430113 1004916 2,910 2,824.1 --

430142100580301 35N31W 9AACD 430142 1005803 2,840 2,811.9 --

430021100543301 35N31W13D 430021 1005433 2,840 2,782.5 --

430153101054902 35N32W 9BABB5 430153 1010549 2,938 2,930.5 --

430727100170304 36N25W 5DBD 430721 1001700 2,440 2,427.6 --

430326100185001 36N25W31ABC 430326 1001819 2,597 2,549.9 --

430700100225701 36N26W 9AB 430700 1002257 2,505 2,498.3 --

430607100212101 36N26W15AAAB 430611 1002119 2,505 2,447.5 --

430528100242001 36N26W17CDD 430523 1002416 2,554 2,533.6 --

430455100241301 36N26W20CAD 430455 1002413 2,537 2,524.7 --

430424100214301 36N26W27ABBB 430427 1002147 2,588 2,545.7 --

430727100262801 36N27W 1 430727 1002628 2,650 2,597.4 --

430451100290001 36N27W22CDBA 430451 1002906 2,638 2,628.4 --

430410100261701 36N27W25ADBB 430415 1002611 2,658 2,614 --

430412100323001 36N27W30BDA 430413 1003233 2,693 2,672.6 --

430245100272401 36N27W35DCD 430246 1002730 2,673 2,646.5 --

430702100330501 36N28W12AAA 430706 1003313 2,806 2,641.6 --

430454100341801 36N28W23DAAC 430454 1003418 2,730 2,712.3 --
Supplemental Information - Table 16 65

430448100332401 36N28W24ACA 430503 1003324 2,655 2,644.9 --

430627100532601 36N30W 7D 430627 1005326 2,960 2,856.3 --

430301100492101 36N30W35CBCC 430300 1004930 2,917 2,842.5 --

430630100565401 36N31W10DACD3 430630 1005654 2,958 2,736.1 --

430613100544901 36N31W12DCCD 430613 1005449 2,899 2,842.6 --

430650101021001 36N32W 1DCDC 430708 1010147 2,623 2,613.9 --

430721101032801 36N32W 2C 430721 1010328 2,660 2,666.6 --

430712101042801 36N32W 3CD 430712 1010428 2,686 2,631.4 --

430619101020501 36N32W12CD2 430619 1010205 2,895 2,733.9 --

430612101014401 36N32W12DD 430620 1010130 2,842 2,674.1 --

430537101062801 36N32W17DBD 430537 1010628 2,860 2,820.2 --

431500101133301 36N33W21BBC 430511 1011307 2,985 2,859.6 --

431254100191001 37N25W 6ABA 431254 1001910 2,410 2,372.6 --

431211100194502 37N25W 6CCC2 431211 1001945 2,369 2,346.5 --

430908100175801 37N25W29ACDD 430908 1001758 2,374 2,359.5 --

430757100183301 37N25W32CCAB 430757 1001833 2,423 2,395.5 --

431245100210801 37N26W 2ADAA 431245 1002108 2,383 2,350.5 --

431215100225801 37N26W 3CDA 431215 1002258 2,444 2,401.2 --

431020100243501 37N26W16CCBB 431020 1002435 2,530 2,522.9 S210

430931100251801 37N26W20CDD 430931 1002518 2,605 2,557 --

430932100211701 37N26W23DDCD 430932 1002117 2,538 2,495.2 --

431019100200001 37N26W24AAA 431019 1002000 2,471 2,453.3 --

430953100200001 37N26W24DAA 430953 1002000 2,451 2,418.3 --

430858100202301 37N26W25DBBD 430858 1002023 2,565 2,522.3 --

430851100210801 37N26W26DADD 430851 1002108 2,576 2,533.2 --

430756100231601 37N26W34CCAA 430756 1002316 2,540 2,521.2 --

430803100212801 37N26W35DBDA 430803 1002128 2,554 2,511.3 --

431212100280601 37N27W 1CC 431212 1002806 2,474 2,451.4 --

431245100320601 37N27W 5A 431245 1003206 2,593 2,581.7 --

431126100321001 37N27W 8D 431127 1003206 2,553 2,536.7 --

431139100311501 37N27W 9CAAA 431139 1003115 2,540 2,526.3 --

431050100274501 37N27W13BDD 431050 1002745 2,530 2,472.2 --

431051100293101 37N27W15ADD 431051 1002931 2,518 2,465.6 --

431000100325101 37N27W20BCD 431000 1003251 2,620 2,609.1 --

430938100273701 37N27W24DCB 430939 1002735 2,595 2,548.2 --

Table 16. Wells used for estimating potentiometric surface of the Arikaree aquifer–Continued

[Well locations are shown in figure 5. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of

1929)

Adjusted

hydraulic

head altitude

(feet above

NGVD of

1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 10)
66 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

430926100290301 37N27W26BAB 430926 1002903 2,564 2,441.5 --

430817100312001 37N27W33BD 430817 1003120 2,620 2,603.5 --

431159100412102 37N28W 7BBBC2 431159 1004121 2,793 2,718 --

430922100410302 37N28W30BBAA2 430922 1004103 2,818 2,753.3 --

430821100373401 37N28W34BCAB 430821 1003734 2,808 2,734.4 --

431149100462301 37N29W 8AADC 431158 1004608 2,810 2,739.6 --

430959100444001 37N29W22CCCC 430929 1004453 2,882 2,780.9 S205

431238100490301 37N30W 1ACB 431240 1004858 2,740 2,693.9 --

431250100530101 37N30W 4BAA 431252 1005256 2,842 2,716.5 --

431122100551202 37N30W 7CDBA2 431124 1005506 2,770 2,604.2 --

431022100542301 37N30W17CCCB 431019 1005423 2,995 2,788.8 --

430824100522501 37N30W33ABD 430808 1005143 2,985 2,838.7 --

430800100491801 37N30W36A2 430812 1004845 2,935 2,824.5 --

431234100574401 37N31W 3ADAC 431234 1005744 2,512 2,506.3 --

431131100580701 37N31W10DBBB 431131 1005807 2,530 2,498.1 --

430920100581201 37N31W22ABCD2 431005 1005804 2,943 2,639.4 --

430838100561701 37N31W25CC 430836 1005611 3,015 2,802.3 --

430845100571903 37N31W26C3 430845 1005719 3,017 2,736.9 --

430807100591001 37N31W33DAA 430805 1005852 3,037 2,780.6 --

431030101031201 37N32W13CAD 431034 1010311 2,970 2,792.3 --

430929101104202 37N33W26AAAA2 430929 1011042 2,953 2,875.7 --

431430100195901 38N25W30BCBB 431428 1001955 2,483 2,457.6 S274

431311100193201 38N25W31CDBA 431311 1001932 2,426 2,413.6 --

431637100264101 38N26W 7CDB 431637 1002641 2,513 2,485.8 --

431554100203301 38N26W13BCCA 431604 1002101 2,608 2,504.6 --

431413100244901 38N26W29DAA 431413 1002449 2,440 2,417.5 --

431356100255401 38N26W30DAD 431405 1002558 2,420 2,387.5 --

431340100253901 38N26W32BBD 431340 1002539 2,452 2,437.4 --

431328100240901 38N26W33BDD 431328 1002409 2,424 2,413.4 --

431308100223101 38N26W34DDB 431308 1002231 2,417 2,394.5 --

431323100213501 38N26W35DBBA 431323 1002135 2,403 2,340.5 --

431736100293201 38N27W 3DAD 431736 1002932 2,526 2,474.3 --

431808100312801 38N27W 4BAB 431808 1003128 2,550 2,488.8 --

431757100323302 38N27W 5BDAB 431757 1003233 2,522 2,497 --

431650100330701 38N27W 7DAAB 431650 1003307 2,477 2,468.2 --

Table 16. Wells used for estimating potentiometric surface of the Arikaree aquifer–Continued

[Well locations are shown in figure 5. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of

1929)

Adjusted

hydraulic

head altitude

(feet above

NGVD of

1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 10)
Supplemental Information - Table 16 67

431548100314401 38N27W16CBCD 431548 1003144 2,484 2,452.7 --

431440100275301 38N27W25BABA 431440 1002753 2,448 2,415.8 --

431430100320101 38N27W28B 431430 1003201 2,518 2,506.7 --

431337100312101 38N27W33BDA 431337 1003121 2,570 2,540.5 --

431539100352401 38N28W13CCCC 431535 1003530 2,577 2,539.2 --

431625100361301 38N28W14BAAB 431625 1003613 2,589 2,529.4 --

431615100390701 38N28W17AADD 431615 1003907 2,664 2,609.6 --

431625100411801 38N28W18BBBA 431625 1004118 2,596 2,587.3 --

431512100402501 38N28W19ADCD 431509 1004029 2,673 2,638.5 --

431506100363601 38N28W23CBBB 431508 1003641 2,635 2,626.8 --

431430100371601 38N28W27ACB 431430 1003716 2,768 2,724.3 --

431347100404901 38N28W31ABBB 431347 1004049 2,666 2,645.1 --

431342100344101 38N28W36ABCB 431347 1003452 2,620 2,608.7 T15

431551100441601 38N29W15DBCD 431550 1004416 2,696 2,698.9 --

431536100472201 38N29W17BCDA 431605 1004705 2,687 2,669.5 --

431502100443801 38N29W22CAC 431500 1004426 2,730 2,686.3 --

431424100430601 38N29W26ACB 431425 1004305 2,750 2,670.5 --

431340100430401 38N29W35ACBB 431336 1004307 2,803 2,707.8 --

431809100483401 38N30W 1AAAA 431809 1004834 2,763 2,625.5 --

431740100502201 38N30W 2CAA 431737 1005027 2,640 2,492.2 --

431610100484701 38N30W13ADBB 431612 1004845 2,645 2,631.8 --

431537100504701 38N30W14CCCA 431537 1005047 2,723 2,639.4 --

431601100514301 38N30W15BDC 431601 1005143 2,650 2,649.7 --

431612100551201 38N30W18BADB 431612 1005512 2,550 2,415.7 --

431515100501701 38N30W23ACBC 431515 1005017 2,720 2,656.8 --

431255100545701 38N30W31DCCD 431254 1005439 2,872 2,701.4 --

431315100541301 38N30W32CBD 431309 1005415 2,887 2,735.7 --

431340100521405 38N30W33AA5 431408 1005206 2,840 2,624.3 --

431335100511101 38N30W34A 431335 1005111 2,600 2,572.8 --

431252100501801 38N30W35BDDB 431327 1005024 2,708 2,605.2 --

431744100561401 38N31W 1BACB2 431744 1005601 2,600 2,502.4 --

431744100583601 38N31W 3ABAB 431800 1005753 2,692 2,600.9 --

431733100585701 38N31W 4DABD2 431733 1005857 2,725 2,656 --

431623101010501 38N31W 8CCC 431623 1010105 2,787 2,732 --

431654100574302 38N31W10ADAC2 431654 1005743 2,698 2,606 --

Table 16. Wells used for estimating potentiometric surface of the Arikaree aquifer–Continued

[Well locations are shown in figure 5. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of

1929)

Adjusted

hydraulic

head altitude

(feet above

NGVD of

1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 10)
68 Simulated Ground-Water Flow in the Ogallala and Arikaree Aquifers, Rosebud Indian Reservation Area, S. Dak.

431630100570201 38N31W11CDAA 431630 1005702 2,652 2,552.8 --

431520100593601 38N31W16DBAA 431555 1005907 2,710 2,688 --

431551101003901 38N31W17CAA 431551 1010039 2,880 2,878.1 --

431501101005701 38N31W20CBAA 431501 1010057 2,837 2,827.1 --

431526100563202 38N31W23AAAB2 431526 1005635 2,443 2,431.2 --

431508100562101 38N31W24BDAD 431508 1005620 2,605 2,504.8 --

431427100561201 38N31W25BBAC 431426 1005601 2,722 2,563.2 --

431259100574401 38N31W34DDAC 431259 1005744 2,502 2,477.2 --

431338100570901 38N31W35BA 431338 1005709 2,485 2,476.1 --

431738103035702 38N32W 1BAAC 431759 1010303 2,750 2,671.1 --

431740101044601 38N32W 3ADDD 431740 1010446 2,750 2,681.3 --

431637101084802 38N32W 7DCAB2 431637 1010848 2,890 2,841.3 --

431639101043102 38N32W11CBD2 431639 1010431 2,785 2,716.3 --

431554101044501 38N32W15DAAA 431554 1010445 2,805 2,782.3 --

431533101080501 38N32W17CCD 431533 1010805 3,059 2,906.7 --

431303101075401 38N32W32CDB 431303 1010754 3,032 2,926.3 --

431625101103001 38N33W12CCDC 431623 1011029 2,943 2,930.7 --

431843100263301 39N26W31BDA 431847 1002633 2,600 2,543 --

431830100250201 39N26W32DCDA 431816 1002502 2,533 2,456.9 --

432242100281201 39N27W 1CCB 432242 1002812 2,520 2,478.6 --

432316100305801 39N27W 3BBD 432316 1003058 2,500 2,468.9 --

432205100294301 39N27W10DABB 432205 1002943 2,513 2,481.7 --

432033100305601 39N27W21ADDA 432033 1003056 2,754 2,582.8 --

432009100290301 39N27W23CDBA 432009 1002903 2,651 2,609.5 --

431937100320101 39N27W29ADBD 431937 1003201 2,676 2,645 --

431815100341801 39N27W31CCC 431815 1003418 2,537 2,476.6 --

431818100324201 39N27W32CDCB2 431818 1003242 2,544 2,513.1 --

431814100302602 39N27W34CCDC2 431814 1003026 2,562 2,535.6 --

431903100282002 39N27W35AAAB2 431903 1002820 2,598 2,552.3 --

432150100381701 39N28W 9DCA 432150 1003817 2,518 2,506.3 --

432203100361301 39N28W11CAA 432203 1003613 2,535 2,509.9 --

432117100371601 39N28W15ACC 432117 1003716 2,585 2,525.1 --

432108100400001 39N28W17CBD 432103 1004006 2,683 2,615.8 --

432003100352501 39N28W24CC 432003 1003525 2,675 2,614.8 --

431907100350201 39N28W25CCD 431907 1003502 2,565 2,504.7 --

Table 16. Wells used for estimating potentiometric surface of the Arikaree aquifer–Continued

[Well locations are shown in figure 5. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of

1929)

Adjusted

hydraulic

head altitude

(feet above

NGVD of

1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 10)
Supplemental Information - Table 16 69

431947100354001 39N28W26AADB 431947 1003540 2,628 2,567.9 --

431927100381501 39N28W28DBAA 431927 1003815 2,628 2,598.6 --

431949100392901 39N28W29ABAD 431949 1003929 2,634 2,624.9 --

431933100412101 39N28W30BCDB 431933 1004121 2,622 2,603.4 --

431912100410501 39N28W30CDBD 431912 1004105 2,601 2,587.4 --

431812100383901 39N28W33CDD 431812 1003839 2,563 2,520.9 --

432049100415301 39N29W13CC 432053 1004229 2,640 2,584.7 --

432025100434001 39N29W23BCD 432025 1004340 2,500 2,468.8 --

431830100450901 39N29W33DA 431830 1004509 2,657 2,628.6 --

431822100424301 39N29W35DDAB 431822 1004243 2,681 2,647.6 --

431813100413101 39N29W36DDDC 431813 1004131 2,645 2,596.7 --

432244100594502 39N31W 4CBDB2 432244 1005945 2,467 2,448.7 --

432149101005001 39N31W 8CACB 432149 1010050 2,653 2,516.8 --

432020101010901 39N31W19ACDA2 432020 1010127 2,625 2,544.9 --

431903100561701 39N31W25CCCA 431902 1005615 2,558 2,470.9 --

431933101010501 39N31W29BCB 431933 1010105 2,640 2,585.9 --

431823101005201 39N31W32CBDB 431823 1010052 2,685 2,646 --

431813100571001 39N31W35CDBD 431813 1005710 2,620 2,533.9 --

432310101045501 39N32W 3AAAA 432320 1010441 2,610 2,577.9 S374

432205101032201 39N32W11ACDA 432205 1010322 2,595 2,584.8 --

432131101034001 39N32W14AAA 432131 1010340 2,634 2,599.9 --

432131101053001 39N32W15BAB 432131 1010528 2,678 2,638.9 --

431922101032201 39N32W25CBAB 431922 1010322 2,705 2,626 --

431913101084001 39N32W30DBDC 431913 1010840 2,820 2,767.9 --

431820101045002 39N32W34DADC2 431820 1010450 2,781 2,646.2 --

432044101115201 39N33W15DDDD 432044 1011152 2,800 2,763.7 S361

432416100315601 40N27W32AAA 432412 1003200 2,478 2,470.1 --

432540101092202 40N32W19BCC2 432540 1010922 2,595 2,569.8 --

432515101071701 40N32W20DDBB 432518 1010737 2,597 2,586.4 --

432554101065601 40N32W21BBBB 432557 1010703 2,576 2,561.3 S384

432530101024801 40N32W24CBB 432530 1010319 2,568 2,543.3 --

432453101075601 40N32W29BCAB 432452 1010803 2,618 2,599.7 --

432654101130401 40N33W 9DDDA 432654 1011304 2,570 2,515.6 --

432545101102701 40N33W24BBDD 432545 1011027 2,548 2,523.1 --

432446101131104 40N33W28AD 432446 1011311 2,740 2,686.1 --

432407101131201 40N33W33AAB 432407 1011312 2,742 2,686.4 --

Table 16. Wells used for estimating potentiometric surface of the Arikaree aquifer–Continued

[Well locations are shown in figure 5. Hydraulic heads are estimated averages for water years 1979-98. NGVD of 1929, National Geodetic Vertical Datum of 

1929. Agency code: S, State; T, Tribal. --, not applicable]

Site

identification

 number

Local number Latitude Longitude

Land surface

altitude

(feet above

NGVD of

1929)

Adjusted

hydraulic

head altitude

(feet above

NGVD of

1929)

Agency (S/T)

and well

number for

observation

wells

(fig. 10)