SUMMARY OF THE HIGH PLAINS

REGIONAL AQUIFER-SYSTEM ANALYSIS

IN PARTS OF COLORADO, KANSAS, NEBRASKA,

NEW MEXICO, OKLAHOMA, SOUTH DAKOTA,

TEXAS, AND WYOMING

WYOMING

L.

; v COLORADO '

NEW MEXICO

LJ "Y

ILS, GEOLOGICAL SURVEY PROFESSIONAL PAPER 1400-A
Summary of the High Plains 

Regional Aquifer-System Analysis 

In Parts of Colorado, Kansas, Nebraska, 

New Mexico, Oklahoma, South Dakota, 

Texas, and Wyoming

By JOHN B. WEEKS, EDWIN D. GUTENTAG, 

FREDERICK J. HEIMES, and RICHARD R. LUCKEY

REGIONAL AQUIFER-SYSTEM ANALYSIS

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1400-A

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1988
DEPARTMENT OF THE INTERIOR 

DONALD PAUL HODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Library of Congress Cataloging-in-Publication Data

Summary of the High Plains Regional Aquifer-System Analysis in parts of Colorado, Kansas, 

Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming.

(Regional Aquifer-System Analysis) (U.S. Geological Survey professional paper ; 1400-A)

Bibliography: p.

1. High Plains Aquifer. I. Weeks, John B. II. Series. III. Series: Geological Survey 

professional paper; 1400-A. 

GB1199.3.H53S86 1988 333.91'04'0978 87-600459

For sale by the Books and Open-File Reports Section, U.S. Geological Survey 

Federal Center, Box 25425, Denver, CO 80225
FOREWORD

THE REGIONAL AQUIFER-SYSTEM ANALYSIS PROGRAM

The Regional Aquifer-System Analysis (RASA) Program was started in 

1978 following a congressional mandate to develop quantitative appraisals of 

the major ground-water systems of the United States. The RASA Program 

represents a systematic effort to study a number of the Nation's most 

important aquifer systems, which in aggregate underlie much of the country 

and which represent an important component of the Nation's total water 

supply. In general, the boundaries of these studies are identified by the 

hydrologic extent of each system and accordingly transcend the political 

subdivisions to which investigations have often arbitrarily been limited in the 

past. The broad objective for each study is to assemble geologic, hydrologic, 

and geochemical information, to analyze and develop an understanding of the 

system, and to develop predictive capabilities that will contribute to the 

effective management of the system. The use of computer simulation is an 

important element of the RASA studies, both to develop an understanding of 

the natural, undisturbed hydrologic system and the changes brought about in 

it by human activities, and to provide a means of predicting the regional 

effects of future pumping or other stresses.

The final interpretive results of the RASA Program are presented in a series 

of U.S. Geological Survey Professional Papers that describe the geology, 

hydrology, and geochemistry of each regional aquifer system. Each study 

within the RASA Program is assigned a single Professional Paper number, 

and where the volume of interpretive material warrants, separate topical 

chapters that consider the principal elements of the investigation may be 

published. The series of RASA interpretive reports begins with Professional 

Paper 1400 and thereafter will continue in numerical sequence as the interpretive products of subsequent studies become available.

Dallas L. Peck 

Director

PREFACE

The Regional Aquifer-System Analysis of the High Plains was conducted 

by U.S. Geological Survey personnel in each of the eight States in the High 

Plains Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, 

Texas, and Wyoming. To provide assistance, technical support, and additional 

information, contracts were awarded to the Kansas Geological Survey, New 

Mexico Natural Resources Department, Oklahoma Water Resources Board, 

and Texas Department of Water Resources. In addition, valuable information 

was provided by many other State and local agencies throughout the High 

Plains. Their contributions are an integral part of this investigation without 

which this study would not have been possible.

The U.S. Geological Survey coordinated its investigation of the High Plains 

aquifer with a concurrent study by the Economic Development Administration of the Department of Commerce. The Six-State High Plains Ogallala 

Aquifer Area study conducted by the Economic Development Administration 

was authorized by Congress in 1976. This study was charged with the responsibility of examining the feasibility of increasing water supplies to insure the 

economic growth and vitality of the High Plains. Together, these two studies 

provide a comprehensive evaluation of the High Plains aquifer and the potential impacts of declining ground-water supplies on the region. The Economic 

Development Administration study has developed and proposed alternative 

strategies to alleviate or mitigate those impacts and the U.S. Geological Survey 

has provided hydrologic data and models needed to evaluate the effects of those 

strategies on the ground-water resource.
CONVERSION FACTORS

The following report uses inch-pound units as the primary system of 

measurements and metric units for water-chemistry measurements. The units 

commonly are abbreviated using the notations shown below in parentheses. 

Inch-pound units can be converted to metric units by multiplying by the factors given in the following list.

Inch-pound unit Multiply by To obtain metric unit

inch 2.540 X 101 millimeter

foot (ft) 3.048 X 10' 1 meter

mile (mi) 1.609 kilometer

acre 4.047 X 10" 1 hectare

square mile (mi2) 2.59 square kilometer

acre-foot (acre-ft) 1.233 X 10"3 cubic hectometer

foot per day (ft/d) 3.048 X 10"1 meter per day

cubic foot per second (ft3/s) 2.832 X 10~2 cubic meter per second
CONTENTS

Abstract ....................................

Introduction ................................

High Plains Regional Aquifer-System Analysis 

Geohydrology ...............................

Physical setting ..........................

Hydrogeologic units ......................

Ground-water hydraulics ...................

Ground-water quality .....................

Ground-water development ....................

Irrigation pumpage .......................

1980 water use ...........................

Page

Al 

2 

2

2

3

3

5

7

10

10

11

Page

Effects of development .............................. A13

Water-level changes .............................

Saturated-thickness changes ......................

Digital models .....................................

Model calibration ...............................

Model sensitivity ...............................

Effects of future pumpage ...........................

Pumpage estimates .............................

Comparison of projections .......................

Selected references .................................

13

13

16

16

18

18

19

19

26

ILLUSTRATIONS

Page

FIGURES 1-4. Maps showing:

1. Principal geologic units in the High Plains aquifer ............................................ A4

5.

6.

7.

8.

9.

10.

11. 

12-15.

2. Geologic units underlying the High Plains aquifer ..........................

3. Saturated thickness of the High Plains aquifer in 1980 ......................

4. Dissolved-solids concentration in water from the High Plains aquifer ..........

Graph showing acreage irrigated by ground water in the High Plains, 1949-78 ........

Graph showing estimated ground-water pumpage from the High Plains aquifer, 1949-78 

Map showing water-level changes in the High Plains aquifer, predevelopment to 1980 . . Map showing saturated-thickness changes in the High Plains aquifer, predevelopment to 1980

9

11

11

14

15

Graph showing acres irrigated per well in seven Texas counties ........................................ 16

Map showing subdivisions used in modeling the High Plains aquifer .................................... 17

Graph showing pumpage estimates by strategy, 1980 to 2020 .......................................... 20

Maps showing:

12. Projected water-level change assuming baseline-strategy pumpage, 1980 to 2020 ................... 21

13. Projected saturated thickness by 2020 assuming baseline-strategy pumpage ....................... 22

14. Projected water-level change assuming management-strategy-2 pumpage, 1980 to 2020 ............. 24

15. Difference in projected saturated thickness by 2020 between management strategy 2 and the baseline strategy 25

TABLE

Page

TABLE 1. Estimated irrigated acreage and volume of ground water pumped for irrigation in areas of the High Plains during the

1980 growing season .............................................................................. A12

REGIONAL AQUIFER-SYSTEM ANALYSIS

SUMMARY OF THE HIGH PLAINS

REGIONAL AQUIFER-SYSTEM ANALYSIS

IN PARTS OF COLORADO, KANSAS, NEBRASKA,

NEW MEXICO, OKLAHOMA, SOUTH DAKOTA,

TEXAS, AND WYOMING

By JOHN B. WEEKS, EDWIN D. GUTENTAG, FREDERICK J. HEIMES, and RICHARD R. LUCKEY

ABSTRACT

In 1978, the U.S. Geological Survey initiated a study called the High 

Plains Regional Aquifer-System Analysis to evaluate the historical 

and future effects of ground-water development on the High Plains 

aquifer. Results of this study were published in a series of reports that 

presented: (1) The geohydrology of the High Plains aquifer, (2) the 

use of satellite imagery to map irrigated acreage and estimate groundwater use, (3) the use of digital models to simulate ground-water flow 

in the High Plains aquifer, and (4) the projected effects of future pumpage on the High Plains aquifer. This report summarizes the information presented in the series of reports.

The High Plains aquifer underlies 174,000 square miles in parts of 

Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, 

Texas, and Wyoming. About 20 percent of the irrigated land in the 

United States is in the High Plains, and about 30 percent of the ground 

water used for irrigation in the United States is pumped from the High 

Plains aquifer. During 1980, about 170,000 wells pumped almost 18 

million acre-feet of water to irrigate nearly 14 million acres.

The High Plains aquifer is a water-table aquifer that consists mainly 

of near-surface sand and gravel deposits. The Ogallala Formation, 

which underlies about 80 percent of the High Plains, is the principal 

geologic unit forming the aquifer. The maximum saturated thickness 

of the aquifer is about 1,000 feet, and the average saturated thickness 

is about 200 feet. Ground water generally flows from west to east at 

an average of about 1 foot per day and discharges naturally to streams 

and springs, and by evapotranspiration in areas where the water table 

is near land surface. Precipitation is the principal source of recharge 

to the aquifer. Estimates of recharge rates range from 0.024 inch per 

year in parts of Texas to 6 inches per year in areas of dune sand in 

Kansas and Nebraska.

During 1980, 3.25 billion acre-feet of drainable water was stored in 

the aquifer. Approximately 65 percent of the water in storage was 

in Nebraska, and 12 percent was in Texas. New Mexico, the State with 

the smallest water resource in the High Plains, had only 1.5 percent 

of the volume of water in storage.

The quality of water in the High Plains aquifer generally is suitable for irrigation use but, in many places, the water does not satisfy 

Environmental Protection Agency drinking-water regulations. Excessive concentrations of dissolved solids, fluoride, chloride, and sulfate 

occur in parts of the aquifer in all States.

The concentration of dissolved solids is 250-500 milligrams per liter 

in 62 percent of the area of the High Plains aquifer; the concentration exceeds 1,000 milligrams per liter in 3 percent of the area of the 

aquifer. Generally, dissolved-solids concentrations are lowest in areas

covered by sand because recharge is relatively high and the sand contains few highly soluble minerals. In most areas of the High Plains 

aquifer where the concentration of dissolved solids exceeds 1,000 

milligrams per liter, the chemical composition of the water is affected 

by the underlying bedrock.

Ground-water irrigation in the High Plains began in the late 1800's, 

but development was sparce until the 1940's. By 1949, about 2 million 

acres, mostly in the southern High Plains, were irrigated; and during 

1980, about 14 million acres were irrigated and more than one-half 

of the total acreage was in the northern High Plains. Annual pumpage of ground water for irrigation increased from about 4 million acrefeet during 1949 to nearly 18 million acre-feet during 1980.

Pumpage has caused areally extensive water-level declines in the 

aquifer. As of 1980, water levels had declined more than 10 feet in 

50,000 square miles and more than 50 feet in 12,000 square miles from 

predevelopment levels. Water-level declines of as much as 200 feet 

had occurred since irrigation started, and the volume of water in 

storage in the aquifer had decreased by 166 million acre-feet. About 

70 percent of the depletion occurred in Texas; about 16 percent of the 

depletion occurred in Kansas.

Water-level declines reduce saturated thickness of the aquifer which 

may affect well yields. The largest decreases in saturated thickness 

generally occur where the aquifer has been pumped for irrigation the 

longest. From predevelopment to 1980, saturated thickness of the 

High Plains aquifer decreased more than 25 percent in 14,000 square 

miles in parts of Kansas, New Mexico, Oklahoma, and Texas. In the 

High Plains of Texas where saturated thickness has declined more 

than 50 percent, the average number of acres irrigated per well decreased from 118 during 1958 to 62 during 1980. This decrease in acres 

irrigated per well is the result of decreasing well yields caused by 

declining water levels and decreasing saturated thickness.

Digital computer models of the High Plains aquifer were used to 

project aquifer response to estimated future pumpage. The High Plains 

aquifer system was modeled in three parts the southern, central, and 

northern High Plains. For each part of the High Plains, separate 

models were constructed to simulate the system prior to large-scale 

development for irrigation (predevelopment-period models) and after 

the beginning of large-scale development (development-period models). 

Water levels from the predevelopment models were the initial conditions for the development-period models. Likewise, water levels from 

the development-period models provided the initial conditions for pro 

jecting future water levels in the High Plains.

The models were used to project aquifer response to pumpage to 

the year 2020. Pumpage was simulated using 5-year averages between 

1980 and 2020, and the models were used to calculate future water

Al
A2 REGIONAL AQUIFER-SYSTEM ANALYSIS

levels in the High Plains. Pumpage estimates for three strategies were 

simulated: (1) The baseline strategy assumed that only existing waterconservation and water-use technology, practices, and public policy 

would affect future water use; (2) management strategy 1 assumed 

that future water use would be reduced by voluntary actions; and (2) 

management strategy 2 assumed that future water use would be further reduced by water-conservation measures imposed by governmental agencies.

Simulation of baseline pumpage from the High Plains aquifer showed 

that, between 1980 and 2020, water-level declines in excess of 100 feet 

would occur in areas totaling about 15,500 square miles in parts of 

all States except South Dakota and Wyoming. The maximum 

1980-to-2020 water-level decline was projected to be nearly 250 feet 

in northern Texas.

Total pumpage for management strategy 1 was only 3 percent more 

than that for the baseline strategy. Consequently, simulation of 

management-strategy-1 pumpage from the High Plains aquifer 

resulted in water-level declines that were similar to those projected 

for the baseline strategy.

Simulation of management-strategy-2 pumpage from the High 

Plains aquifer resulted in significantly different water levels than those 

projected for the baseline strategy. Between 1980 and 2020, waterlevel declines for management strategy 2 would exceed 100 feet in 

9,100 square miles. The maximum water-level decline projected from 

1980 to 2020 was about 180 feet in Kansas.

The saturated thickness projected for 2020 was more than 50 feet 

greater for management strategy 2 than for the baseline strategy in 

areas that total 1,830 square miles because of the lower water use 

assumed for management strategy 2. The maximum difference in 

saturated thickness projected for 2020 between management strategy 

2 and the baseline strategy was 68 feet, and the average difference 

was 7 feet.

INTRODUCTION

The High Plains aquifer underlies about 174,000 mi2 

(see Conversion Factors for definitions of abbreviated 

units) in parts of eight States Colorado, Kansas, 

Nebraska, New Mexico, Oklahoma, South Dakota, 

Texas, and Wyoming. The High Plains aquifer is the 

shallowest and most abundant source of water in one 

of the major agricultural areas in the United States. 

About 20 percent of the irrigated land in the United 

States is in the High Plains, and about 30 percent of 

the ground water used for irrigation in the United States 

is pumped from the High Plains aquifer. During 1980, 

about 170,000 wells pumped 18 million acre-ft of water 

from the aquifer to irrigate about 14 million acres.

The irrigated agricultural economy of the High Plains 

is dependent on the aquifer for continued growth and 

prosperity. However, declining water levels and decreasing well yields threaten the future of ground-water 

irrigation.

HIGH PLAINS REGIONAL 

AQUIFER-SYSTEM ANALYSIS

National concern about the economic impact of declining water supplies in the High Plains was responsible

for the initiation of this regional study of the High 

Plains aquifer. This study began in 1978 as one of the 

first studies within the Regional Aquifer-System 

Analysis (RASA) program of the U.S. Geological 

Survey. The purposes of the High Plains RASA were 

to provide: (1) Hydrologic information needed to 

evaluate the effects of continued ground-water development, and (2) computer models to predict aquifer 

response to changes in ground-water development. The 

results of this study will provide water-resources planners and managers with information needed for groundwater resource management and models of the aquifer 

capable of evaluating water-management alternatives.

The results of the High Plains RASA are summarized 

in this report, Chapter A of Professional Paper 1400. 

Chapters B, C, D, and E of Professional Paper 1400 

describe the results of the High Plains RASA in detail. 

Chapter B (Gutentag and others, 1984) presents the 

geohydrology of the High Plains aquifer including its 

depositional history and relation to bedrock, the quantity and quality of ground water, and the history of 

ground-water development. Chapter C (Thelin and 

Heimes, in press) describes the use of satellite imagery 

to map irrigated acreage and the use of irrigated acreage 

to estimate ground-water use. Chapter D (Luckey and 

others, 1986) discusses the digital models used to 

simulate ground-water flow in the High Plains aquifer. 

Chapter E (Luckey and others, in press) projects the effects of future pumpage on the High Plains aquifer for 

three pumpage scenarios.

Including the five chapters of this Professional Paper, 

the data, methods, and results of the High Plains RASA 

are documented in more than 130 publications. These 

publications were prepared by the U.S. Geological 

Survey, and its cooperators and contractors, in a joint 

effort to advance the scientific understanding of the 

High Plains aquifer. The Selected References section at 

the end of this report includes these publications.

GEOHYDROLOGY

The first regional study of the High Plains was conducted by the U.S. Geological Survey at the beginning 

of the twentieth century (Johnson, 1901). The study 

provided a reconnaissance of the geographic, physiographic, and hydrologic features of the area. The conclusions of the study pointed to the vast ground-water 

resources of the area but held little promise for 

agricultural development of the region because of 

limited rainfall, high evaporation, and few surface 

streams.

Since that time, technological advances have provided 

the means to recover the ground-water resource.
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS A3

However, hydrologic studies of the region did not keep 

pace with ground-water development. Many waterresource studies of small areas such as counties or 

groups of counties were made, but few studies of larger 

areas within the High Plains have been made. In fact, 

prior to the High Plains RASA, only one other regionwide hydrologic study (Lohman, 1953) had been made 

since the study by Johnson (1901).

Previous studies provided the initial geohydrologic 

framework for the Regional Aquifer-System Analysis 

of the High Plains aquifer. Results of previous investigations provided a wealth of information for areas 

within political boundaries but without continuity 

across those boundaries. In developing the geohydrologic framework of the High Plains aquifer, this investigation assembled, organized, and assimilated the 

geohydrologic information available from many 

previous studies. The principal published sources of information used in the High Plains RASA are listed in 

the reference section of the appropriate chapter of this 

Professional Paper.

PHYSICAL SETTING

The High Plains occupies the southern part of the 

Great Plains physiographic province which lies between 

the Rocky Mountains on the west and the Central 

Lowland on the east. The region extends from southern 

South Dakota to northwestern Texas. The High Plains, 

which is characterized by flat to gently rolling terrain, 

is a remnant of a vast plain formed by sediments that 

were deposited by streams flowing eastward from the 

Rocky Mountains.

Most of the High Plains has a middle-latitude dry continental climate with abundant sunshine, moderate 

precipitation, frequent winds, low humidity, and a high 

rate of evaporation. Mean annual precipitation increases 

eastward across the High Plains by about 1 inch every 

25 mi, from less than 16 inches in Colorado, New Mexico, and Wyoming to about 28 inches in eastern 

Nebraska and central Kansas. Normally, about 75 percent of the precipitation falls as rain during the growing season. However, much of the rain results from local 

thunderstorms, so large variations in rainfall can occur 

from place to place and year to year.

Persistent winds and high summer temperatures 

cause high rates of evaporation. Mean annual evaporation from Class A pans ranges from about 60 inches in 

northern Nebraska and southern South Dakota to about 

105 inches in western Texas and southeastern New 

Mexico. Because of the large evaporative demand, little 

precipitation is available to recharge the ground-water 

system. Except in areas with sandy soils where water

can readily percolate down to the water table, most of 

the water that enters the soil is returned to the atmosphere by evapotranspiration.

HYDROGEOLOGIC UNITS

The High Plains aquifer consists mainly of nearsurface deposits of late Tertiary or Quaternary age 

described by Gutentag and others (1984). The principal 

geological units in the High Plains aquifer are shown 

in figure 1. The Tertiary rocks include part of the Brule 

Formation (of the White River Group), Arikaree Group 

(or Formation), and Ogallala Formation. The Quaternary deposits consist of alluvial, dune-sand, and valleyfill deposits. Except for dune sand in figure 1, the 

Quaternary deposits are combined and shown only in 

areas where they do not overlie Tertiary aquifer units. 

In northern Texas, some Permian collapse structures, 

filled with Triassic, Jurassic, and Lower Cretaceous 

rocks that have secondary permeability, are considered 

part of the High Plains aquifer; however, they are minor 

and are not shown in figure 1.

The Ogallala Formation is the principal geologic unit 

in the High Plains aquifer and underlies about 134,000 

mi2 of the study area (fig. 1). Maximum thickness of the 

Ogallala is about 700 ft. The Ogallala was deposited by 

aggrading streams that filled and buried valleys eroded into pre-Ogallala rocks. Braided streams flowed 

eastward from the mountains and transported rock 

debris, which was deposited as a heterogeneous sequence of clay, silt, sand, and gravel. Within the 

Ogallala, zones cemented with calcium carbonate are 

resistant to weathering and form ledges in outcrops. 

These ledges form the escarpment that typically marks 

the boundary of the High Plains. The most distinctive 

of these layers, the Ogallala cap rock (commonly called 

caliche or mortar bed), is near the top of the Ogallala 

Formation. The cap rock underlies large areas in Texas 

and New Mexico, and may be as thick as 60 ft.

The Brule Formation is included in the aquifer in 

parts of Nebraska, Colorado, and Wyoming. The Brule 

is mainly a massive siltstone that contains beds of sandstone, volcanic ash, claystone, and fine sand. Maximum 

thickness of the Brule is about 600 ft. The Brule Formation generally has little permeability. However, in 

some areas the permeability of the formation has been 

increased by joints, fractures, and solution openings. 

In those areas, the Brule Formation is considered part 

of the aquifer (fig. 1).

The Arikaree Group (or Formation) is part of the High 

Plains aquifer in large areas in Nebraska, South Dakota, 

and Wyoming (fig. 1). The Arikaree is mainly a finegrained sandstone that contains localized beds of
A4 REGIONAL AQUIFER-SYSTEM ANALYSIS

43°

40°

102° 101" 100° 99°

39° U_^ (§ COLORADO

EXPLANATION 

Quaternary units 

Undivided 

Dune sand 

Tertiary units

Ogallala Formation 

Arikaree Group 

Brule Formation 

Contact

AQUIFER 

BOUNDARY

FIGURE 1. Principal geologic units in the High Plains aquifer.
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS A5

volcanic ash, silty sand, and sandy clay. Maximum 

thickness of the Arikaree is about 1,000 ft where it is 

part of the aquifer.

Dune-sand deposits, consisting predominantly of very 

fine to medium wind-blown sand, are part of the High 

Plains aquifer. Areas covered by dune sand are shown 

in figure 1. Of the 174,000 mi2 underlain by the High 

Plains aquifer, about 19 percent is covered by dune 

sand. The most extensive area of dune sand is in westcentral Nebraska where the deposits cover an area of 

20,000 mi2 and have a maximum thickness of about 

300 ft. Large areas south of the Arkansas River in Kansas also are covered by dune sand. Throughout the High 

Plains, dune sands are important recharge areas for the 

aquifer.

Valley-fill deposits consist of unconsolidated gravel, 

sand, silt, and clay associated with the most recent cycle 

of erosion and deposition along present streams. These 

deposits are as much as 60 ft thick. Saturated valleyfill deposits that overlie Tertiary or Quaternary aquifer 

deposits are considered part of the High Plains aquifer. 

The valley-fill deposits and associated streams form 

stream-aquifer systems that link the High Plains 

aquifer to surface streams, particularly along the Platte, 

Republican, and Arkansas Rivers.

Bedrock units in contact with the High Plains aquifer 

range in age from Permian to Tertiary (fig. 2). Although 

some bedrock units will yield large quantities of water 

to wells, the bedrock units generally are much less 

permeable than the High Plains aquifer. Bedrock of 

marine origin generally contains evaporite deposits and 

saline water that affects the quality of water in the 

overlying aquifer. This is particularly true in areas 

underlain by Permian bedrock and areas south of the 

Canadian River underlain by Lower Cretaceous rocks.

GROUND-WATER HYDRAULICS

Ground-water flow and storage are controlled by the 

hydraulic characteristics of the aquifer. Water flows 

from areas of recharge to areas of discharge in response 

to differences in the altitude of the potentiometric 

surface.

Recharge to the aquifer, which generally is under 

water-table conditions, is entirely from precipitation and 

seepage from streams. Because evapotranspiration demand greatly exceeds precipitation, little or no recharge 

occurs except in sandy soils with large infiltration rates, 

high permeability, and low field capacity.

Recharge rates in the High Plains are highly variable. 

Estimated recharge rates from previous studies range 

from 0.024 in./yr (0.1 percent of precipitation) in parts 

of Texas to 6 in./yr (20 percent of precipitation) in sandy

soils in Kansas (Gutentag and others, 1984, table 7). 

During this study, recharge to the aquifer was estimated by computer model simulations. The simulated 

average annual volume of recharge from predevelopment to 1980 was about 5.7 million acre-ft or 0.6 inch 

over the area of the aquifer. About 80 percent of the 

recharge occurred in the northern High Plains (north 

of lat 39° N.) where evapotranspiration is least and dune 

sands are prevalent.

Hydraulic conductivity and specific yield are the two 

principal hydraulic characteristics that control groundwater flow in unconfined aquifers. Hydraulic conductivity and specific yield vary both horizontally and vertically according to the variation in sediment types. The 

hydraulic conductivity of most (68 percent) of the High 

Plains aquifer is 25-100 ft/d (Gutentag and others, 1984, 

fig. 10), although the value is as high as 300 ft/d for individual lithologic units and averages 60 ft/d. The 

specific yield of most (76 percent) of the aquifer is 10-20 

percent (Gutentag and others, 1984, fig. 11), although 

the value ranges from 3 to 35 percent for individual 

lithologic units within the aquifer and averages 15 

percent.

In the High Plains aquifer, water generally flows from 

west to east in response to the slope of the water table. 

Based on average values of hydraulic gradient and 

aquifer characteristics, the velocity of water moving 

through the aquifer is about 1 ft/d.

Water from the High Plains aquifer discharges 

naturally to streams, springs, and seeps, and directly 

to the atmosphere by evapotranspiration. Streams that 

originate in the High Plains generally are ephemeral in 

upstream reaches and perennial where channels are incised to the water table. Ground-water discharge 

through springs and seeps mainly occurs along the 

eastern boundary of the High Plains. Ground-water 

discharge by evapotranspiration is greatest in stream 

valleys where the water table is near land surface. In 

the sand hills in Nebraska, evaporation from numerous 

lakes in hydraulic connection with the aquifer may equal 

or exceed seepage into streams.

During this study, ground-water discharge from the 

High Plains aquifer was estimated by computer-model 

simulations (Luckey and others, 1986). The simulated 

average annual ground-water discharge for predevelopment conditions was 2.87 million acre-ft (3,960 ft3/s). 

About 80 percent of the discharge occurred in the northern High Plains (north of lat 39° N.).

Saturated thickness of the aquifer is as much as 1,000 

ft in west-central Nebraska. During 1980, about 46 percent of the High Plains aquifer had less than 100 ft of 

saturated thickness, whereas only 5 percent had more 

than 600 ft of saturated thickness. Significant areas 

where the saturated thickness of the aquifer was greater
A6 REGIONAL AQUIFER-SYSTEM ANALYSIS

106°

105° ° 103° 102° 101° 100° 99'

970 96°

42°

WHITE CLAY 

TT-WHELAN FAULT

| FAULT

WHEATLAND \>£ 

FAULT

I

 J.___

39° ,L cS COLORADO

BEAR CREEK 

FAULT

CROOKED CREEK 

FAULT

EXPLANATION

Geologic units underlying

High Plains aquifer 

Tertiary rocks

Upper Cretaceous rocks 

Lower Cretaceous rocks 

Jurassic and Triassic rocks 

Permian rocks

AQUIFER 

BOUNDARY

Fault Bar and ball on 

downthrown side

FIGURE 2. Geologic units underlying the High Plains aquifer.
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS A7

than 600 ft occurred only in Nebraska and Wyoming. 

The average saturated thickness of the High Plains 

aquifer was about 200 ft. The saturated thickness of the 

aquifer in 1980 is shown in figure 3.

Salt dissolution in Permian rocks, which resulted in 

collapse features that have been filled with younger 

sediments, has affected the thickness of the High Plains 

aquifer. Evaporite beds in the Permian rocks underlying the High Plains are susceptible to dissolution by 

ground water. Sinkholes associated with salt dissolution have formed since Permian time, and collapse structures occur in large areas in southwestern Kansas, 

western Oklahoma, and northern Texas (areas with 

more than 200 ft of saturated thickness shown in figure 

3).

Drainable water in storage in the High Plains aquifer 

depends on the thickness and specific yield of the 

sediments. The variability in the distribution of water 

in storage can be inferred from the saturated-thickness 

map shown in figure 3. The total volume of drainable 

water in storage (product of specific yield, saturated 

thickness, and area) in the High Plains aquifer in 1980 

was estimated to be 3.25 billion acre-ft (Gutentag and 

others, 1984, table 8). About 65 percent of the water 

in storage was in Nebraska, where recharge is greatest 

because of the presence of dune sands. About 12 percent of the water in storage was in Texas, 10 percent 

in Kansas, 4 percent in Colorado, 3.5 percent in Oklahoma, 2 percent each in South Dakota and Wyoming, 

and 1.5 percent in New Mexico.

GROUND-WATER QUALITY

The quality of water in the High Plains aquifer 

generally is suitable for irrigation use; however, the 

water does not meet U.S. Environmental Protection 

Agency (1976, 1977) primary and secondary drinkingwater regulations in many places. Concentrations of 

sulfate, chloride, selenium, fluoride, nitrate, and dissolved solids in water from the High Plains aquifer exceed the primary and secondary drinking-water 

regulations at some sites (Krothe and others, 1982; 

Feder and Krothe, 1981).

Excessive fluoride concentrations (greater than 

2 mg/L) are a widespread problem in the High Plains 

aquifer. Fluoride concentrations exceed drinking-water 

regulations in parts of Colorado, Kansas, Nebraska, 

New Mexico, Oklahoma, and Texas. Some fluoride in 

water in the High Plains aquifer is derived from the 

solution of fluoride minerals in the sand and gravel that 

make up most of the aquifer. However, excessive concentrations (2-8 mg/L) occur where the aquifer contains 

volcanic-ash deposits or where it is underlain by

Cretaceous (especially Lower Cretaceous) rocks. 

Fluoride is a concern in drinking water; commonly occurring concentrations of fluoride are not of concern in 

irrigation water.

The High Plains aquifer is the only source of water 

for irrigation in most of the High Plains. The agricultural economy of the High Plains depends on the 

availability of large quantities of ground water of 

suitable quality for irrigation. Excessive concentrations 

of dissolved solids affect plant growth. Most crops can 

tolerate water with as much as 500 mg/L dissolved 

solids without adverse effects; if leaching or drainage 

is adequate, concentrations of 500-1,500 mg/L are not 

likely to be harmful (U.S. Salinity Laboratory Staff, 

1954).

The concentration of dissolved solids in most (85 percent) of the water in the High Plains aquifer contains 

less than 500 mg/L. About 27 percent of the volume of 

water in the aquifer contains less than 250 mg/L dissolved solids. Only 3 percent of the volume of water in 

the aquifer contains more than 1,000 mg/L dissolved 

solids. Except in local areas, the concentration of 

dissolved solids in water from the High Plains aquifer 

generally is less than 3,000 mg/L.

The chemical composition of water in the High Plains 

aquifer depends on the concentration of dissolved solids. 

In general, water in the High Plains aquifer that contains less than 250 mg/L dissolved solids is calcium 

bicarbonate type water. Ground water that contains 

more than 500 mg/L dissolved solids in this area 

generally is a mixed type, with calcium, sodium, sulfate, 

and chloride most prevalent.

Generally, dissolved-solids concentrations are least in 

areas covered by sand, because recharge is relatively 

high and the sand contains few readily soluble minerals. 

As shown in figure 4, water in the High Plains aquifer 

contains less than 250 mg/L dissolved solids in parts 

of Colorado, Kansas, Nebraska, and Wyoming. A large 

part of this area is covered by sandy soils and dune 

sands (fig. 1). In most areas of the High Plains aquifer 

where the concentration of dissolved solids exceeds 

1,000 mg/L (fig. 4), the chemical composition of the 

water is affected by the underlying bedrock.

In a small area in Colorado, the concentration of 

dissolved solids in water from the High Plains aquifer 

exceeds 1,000 mg/L (fig. 4). In this area, the aquifer is 

underlain by bedrock that contains gypsum (calcium 

sulfate). Sulfate is the dominant anion in water from the 

aquifer. The sulfate probably is derived from the solution of gypsum at the bedrock contact or from bedrock 

material contained in the aquifer.

Permian bedrock, which contains salt beds and saline 

water, underlies the High Plains aquifer in parts of Kansas, Oklahoma, and Texas (fig. 2). Water in the aquifer
A8 REGIONAL AQUIFER-SYSTEM ANALYSIS

105° 104° 103o 102° 101" 100° 99°

43°

42°

40°

38°

1980 saturated thickness,

in feet 

0 to 100

FIGURE 3. Saturated thickness of the High Plains aquifer in 1980.
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS

106° ° ° 97°

A9

43°

40'

Dissolved-solids concentration,

in milligrams per liter 

Less than 250

250 to 500 

500 to 1000 

More than 1000

FIGURE 4. Dissolved-solids concentration in water from the High Plains aquifer (modified from Krothe and others,

1982).
A10 REGIONAL AQUIFER-SYSTEM ANALYSIS

in these areas typically contains 250-500 mg/L dissolved solids, but concentrations exceed 1,000 mg/L 

near Permian outcrops in Oklahoma (fig. 4). Water in 

the aquifer generally is sodium chloride type, which indicates that saline water from the Permian bedrock is 

entering the aquifer.

The concentration of dissolved solids in water from 

the High Plains aquifer in northeastern Nebraska exceeds 1,000 mg/L in two small areas (fig 4). In these 

areas, the aquifer contains reworked bedrock material 

of marine origin. The solution of minerals from the 

reworked bedrock probably affects the concentration of 

dissolved solids in water from the aquifer.

Part of the aquifer in the southern High Plains of New 

Mexico and Texas is underlain by Lower Cretaceous 

bedrock (fig. 2) deposited in a deep-water marine environment. Water in these rocks is very mineralized. 

The concentration of dissolved solids in water from 

parts of the aquifer in the southern High Plains exceeds 

1,000 mg/L with unusually large proportions of magnesium, sodium, chloride, and sulfate. This probably is 

caused by the movement of solutes from the marine 

bedrock into the aquifer.

The concentration of dissolved solids in water from 

the High Plains aquifer exceeds 1,000 mg/L near outcrops of Late Cretaceous age in southeastern Wyoming 

(fig. 4). In this area, the concentration of dissolved solids 

in water from the bedrock is as large as 1,250 mg/L. 

Water from the bedrock in this area, which is under artesian pressure, may be moving upward into the High 

Plains aquifer.

The concentration of dissolved solids in water from 

the High Plains aquifer near streams is affected by irrigation practices. In stream valleys where the water 

table is near land surface, the salts that accumulate in 

the soil due to evapotranspiration are dissolved and 

flushed with irrigation water and transported to the 

aquifer. As shown in figure 4, the concentration of 

dissolved solids in ground water along the Arkansas, 

Platte, and Republican Rivers generally is 500-1,000 

mg/L and exceeds 1,000 mg/L along parts of the South 

Platte and Arkansas Rivers. These relatively large concentrations are due to irrigation.

GROUND-WATER DEVELOPMENT

The High Plains aquifer is the principal source of 

water for irrigated agriculture in the region. Rapid 

development of irrigation in the High Plains in recent 

years has transformed the area into one of the major 

agricultural regions of the United States. About 95 percent of all water pumped from the High Plains aquifer 

is used for irrigation.

IRRIGATION PUMPAGE

Ground-water irrigation in the High Plains began in 

the late 1800's with the use of windmills. However, 

ground-water development was sporadic until the 

drought of the 1930's. Spurred by the drought, technological advances in well drilling and pumping plants, 

low-cost energy, favorable crop prices, and available 

financing, ground-water irrigation developed rapidly 

after the 1930's. By 1949, about 2 million acres, mostly in the southern High Plains, were irrigated.

During the 1950's, irrigation development was 

spurred again by severe drought. In addition, development of natural-gas fields underlying the High Plains 

made inexpensive energy readily available, and irrigation development spread throughout large parts of the 

High Plains. Prior to the 1960's, most irrigation wells 

were drilled in areas where the water table was less than 

100 ft below land surface. Since the early 1960's, 

development of efficient turbine pumps has allowed 

areas with deeper water to be developed.

During the 1960's, development of center-pivot irrigation systems, which were adaptable to sandy soils and 

rolling terrain, made land available for irrigation that 

previously was not suitable. This resulted in a large increase in irrigated acreage in the northern part of the 

High Plains. During 1980, about 14 million acres were 

irrigated in the High Plains of which more than 5 million 

acres were in Nebraska.

Historical information on ground-water pumpage for 

irrigation was needed to calibrate computer models of 

the High Plains aquifer. Data on ground-water pumpage 

were not available for the entire High Plains from 

predevelopment to 1980. Therefore, ground-water 

pumpage was estimated from irrigated acreage, irrigation demand, and irrigation-system efficiency. Irrigation demand is the amount of irrigation water, in 

addition to precipitation, required by an individual crop 

growing in a given area. Ground-water pumpage was 

estimated by dividing irrigation demand (in feet) by efficiency of the irrigation systems (dimensionless), and 

multiplying by irrigated area (acres).

Estimates of irrigated acreage were obtained from the 

Census of Agriculture (U.S. Department of Commerce, 

1949-78) which provided data on irrigated acreage by 

crop type. Irrigation demand was calculated from 

consumptive-use formulas for all irrigated crops grown 

in a given area, based on average climatic conditions 

(Heimes and Luckey, 1982). The Blaney-Criddle formula 

(U.S. Department of Agriculture, 1967) was used to 

estimate irrigation demand on the High Plains because: 

(1) This formula was developed for semiarid areas, (2) 

climatic data for the formula commonly are available, 

and (3) data on crop growth-stage coefficients used in 

the formula are readily available.
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS All

Irrigated acreage in the High Plains, based on Census of Agriculture data from 1949-78, is shown in figure 

5. The graph shows that the rate of growth of irrigated 

acreage has decreased in some parts of the High Plains 

and increased in other areas. In Texas, irrigated acreage 

increased rapidly until 1959, but there was little change 

between 1959 and 1978. This is primarily the result of 

declining water availability in the southern High Plains 

of Texas. In contrast to Texas, irrigated acreage in 

Nebraska increased slowly during the early years and 

rapidly during later years primarily because of 

technological advances and the availability of large 

quantities of ground water. The total acreage irrigated 

by ground water in the High Plains increased from 

slightly more than 2 million acres in 1949 to about 13 

million acres in 1978. This rapid increase in irrigated 

acreage in the High Plains has resulted in a corresponding increase in ground-water pumpage.

Ground-water pumpage in the High Plains, estimated 

for 1949-78, is shown in figure 6. An average irrigation 

system efficiency of 65 percent was assumed for the 

calculation of pumpage presented in figure 6. System 

efficiency generally ranges from about 40 to 90 percent

12 

1 1 

10 

9 

8

6 

5 

4 

3 

2 

1 

0

| Colorado, New Mexico 

Oklahoma, South 

Dakota, and Wyoming 

combined

| Kansas 

[ | Nebraska 

[ | Texas

-

-

-

-

-

-

-

-

and depends on many factors, such as type of irrigation system, crop type, soil, and climate. A dramatic 

increase in pumpage during the 30 years is shown by 

figure 6. During 1978, estimated pumpage from the 

High Plains aquifer for irrigation was about 23 million 

acre-ft which is almost 20 million acre-ft more than the 

estimated pumpage for irrigation during 1949.

1980 WATER USE

Calculations based on irrigation demand and irrigated 

acreage give reasonable estimates of ground-water 

pumpage, but changes in irrigation techniques caused 

by increased energy costs and decreasing water 

availabililty are likely to decrease the accuracy of 

estimates of ground-water pumpage based on this approach. Consequently, a sampling program was designed to provide an estimate of ground-water pumpage 

for irrigation during 1980 based on measured data. A 

pilot program was conducted in 1979 to test methods 

(Heimes and Luckey, 1980) and instrumentation 

(Luckey, Heimes, and Gaggiani, 1980) to be used during the 1980 pumpage-sampling program.

The 1979 pilot program was designed to: (1) Develop

24

22 

20 

H- 18 hLU 

CC<J

J 16

O

C/3 z

O 14 

12

8 

C 6 

cc

4 -

| __ Colorado, New Mexico, 

_ Oklahoma, South 

Dakota, and Wyoming 

combined 

[ ] Kansas

[ ] Nebraska 

[ ) Texas

-

-

-

~}

i

'-

\

1949 1954 1959 1964 1969 1974 1978 1949 1954 1959 1964 1969 1974 1978

FIGURE 5. Acreage irrigated by ground water in the High Plains, 

1949-78.

FIGURE 6. Estimated ground-water pumpage from the High Plains 

aquifer, 1949-78.
A12 REGIONAL AQUIFER-SYSTEM ANALYSIS

a statistical approach to sample ground-water pumpage 

for irrigation, (2) test instrumentation and develop procedures for measuring the annual volume of ground 

water pumped from selected irrigation wells, (3) determine the relation between the annual volume of ground 

water pumped and the acreage irrigated, and (4) develop 

a suitable approach to map irrigated cropland for the 

entire High Plains in order to extend the sample.

For the 1979 pilot program, 250 sites were monitored 

and the annual volume of ground water pumped at each 

site was determined. Irrigated cropland maps were required to estimate the volume of water pumped, and 

several approaches to mapping irrigated cropland were 

evaluated. Landsat imagery proved to be the most efficient and least costly approach for mapping irrigated 

cropland in the High Plains (Heimes and Luckey, 1980).

For 1980, monitoring sites were randomly selected in 

15 counties. Discharge, time-of-operation of wells, croptype, and crop-acreage data were collected at each of 

the sites during the 1980 growing season. These data 

were used to determine the average depth of irrigation 

water applied (application) at each site and to evaluate 

the effects of climate, water availability, crop types, and 

irrigation-system types on application. The relations 

between irrigation demands (calculated using the 

Blaney-Criddle formula) and measured applications 

were used to estimate the applications in unsampled 

areas of the High Plains. Estimates of application were

combined with 1980 irrigated-acreage data mapped 

from Landsat imagery (Thelin and Heimes, in press) to 

calculate the volume of water pumped during the 1980 

growing season in the High Plains (Heimes and Luckey, 

1983).

The estimated volume of ground water pumped for 

irrigation in the High Plains is summarized by State 

in table 1. The estimated total volume pumped during 

1980 in the High Plains was 17,817,000 acre-ft applied 

to 13,385,000 acres. Three States (Kansas, Nebraska, 

and Texas) accounted for about 88 percent of this pumpage. Texas, with 29 percent of total pumpage, was the 

most developed area in the High Plains. South Dakota, 

with only 0.1 percent of the pumpage, virtually was 

undeveloped.

The estimated 1980 pumpage is 75 percent of the 1978 

pumpage estimated from irrigation demand, irrigation 

efficiency, and Census of Agriculture irrigated acreage. 

Although there is a difference in dates, the irrigated 

acreage estimates are within 5 percent. If the two pumpage estimates should be about equal, the efficiency used 

in the 1978 estimate (65 percent) would have to be 87 

percent which is large compared to published efficiency estimates (U.S. Department of Agriculture, 1976). 

The authors consider the sampling approach used to 

estimate pumpage to be more accurate than that based 

on irrigation demand and efficiency because of uncertainties in calculating irrigation demand and estimating

TABLE 1. Estimated irrigated acreage and estimated volume of ground water pumped for irrigation in areas of the High Plains

during the 1980 growing season

[From Heimes and Luckey, 1983]

Area of High Plains 

State aquifer within State 

(square miles)

Irrigated acreage

during 1980

(acres)

Volume of

ground water pumped 

(acre-feet)

Colorado 

Kansas 

Nebraska 

New Mexico 

Oklahoma 

South Dakota 

Texas 

Wyoming 

14,900

30,500

63,650

9,450

7,350

4,750

35,450

8,000

767,000

2,795,000

5,101,000

325,000

389,000

20,000

3,878,000

110,000

985,000

4,215,000

6,240,000

519,000

540,000

24,000

5,169,000

125,000

Total- 174,050 13,385,000 17,817,000
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS A13

efficiency. If so, the pumpage estimates based on irrigation demand, irrigation efficiency, and Census of 

Agriculture irrigated acreage are likely to overestimate 

pumpage, particularly in later years when irrigation 

costs and efficiency have increased.

EFFECTS OF DEVELOPMENT

Irrigation demand for crops grown in the High Plains 

generally is much larger than recharge from precipitation. Estimates of natural recharge range from 0.024 

in./yr in parts of the southern High Plains of Texas to 

6 in./yr in sand-dune areas in Kansas. Irrigation demand 

for most crops commonly grown in the High Plains is 

more than 1 ft per year, with the greatest demands 

occurring in the southern part and the least demands 

occurring in the northeastern part. The ratio between 

irrigation demand and recharge to the aquifer could be 

as small as 2 in areas with large recharge rates or more 

than 100 in areas with small recharge rates. Consequently, pumpage for irrigation in large areas of the 

High Plains greatly exceeds the rate of natural 

replenishment. Any long-term withdrawal of water from 

the aquifer that greatly exceeds the recharge rate will 

result in long-term declines in water level and decreases 

in saturated thickness.

WATER-LEVEL CHANGES

Water levels have declined since widespread irrigation development began. The date when significant irrigation development began varies within the High 

Plains. In general, predevelopment conditions ended 

about 1940 south of the Canadian River, 1950 in the 

area between the Canadian River and lat 39° N., and 

1960 north of lat 39° N. Water-level changes from 

predevelopment to 1980 in the High Plains aquifer are 

shown in figure 7. Areas of decline caused by irrigation 

pumpage occurred in all States except South Dakota, 

where irrigation pumpage, relative to other High Plains 

States, is sparse. The largest area of water-level declines 

exceeding 50 ft occurred south of the Canadian River 

in New Mexico and Texas. The maximum decline of 

nearly 200 ft occurred in Floyd County, Tex.

North of the Canadian River, water-level declines exceeding 50 ft occurred in northern Texas, western 

Oklahoma, and southwestern Kansas. Large areas of 

water-level decline also occurred in eastern Colorado, 

northwestern Kansas, and southern Nebraska. Declines 

in these areas were less severe, primarily because irrigation development started later.

Water-level rises in Nebraska (fig. 7) are due to

recharge from surface-water irrigation and leakage from 

canals and reservoirs. In Kansas and Oklahoma, waterlevel rises probably represent recovery from abnormally low water levels during the drought of 1933-40. In 

Texas, water-level rises are attributed to clearing sandy 

soils of native vegetation for cultivation, which increased the rate of recharge from precipitation.

Significant declines in water levels (more than 10 ft) 

occurred in 29 percent of the area of the High Plains 

aquifer, and significant rises in water level (more than 

10 ft) occurred in only 1 percent of the area. A total of 

50,000 mi2 (32 million acres) of the aquifer had waterlevel declines in excess of 10 ft, and more than 12,000 

mi2 (7.7 million acres) had water-level declines in excess 

of 50 ft.

SATURATED-THICKNESS CHANGES

Saturated-thickness changes (in percent) that occurred from predevelopment to 1980 in the High Plains 

aquifer are shown in figure 8. Significant (more than 10 

percent) increases in saturated thickness, mostly in 

Nebraska, occurred in only 1 percent of the area, or 

about 1,700 mi2 (1.1 million acres). Significant (more 

than 10 percent) decreases in saturated thickness occurred in 25 percent of the area, or about 44,000 mi2 

(28 million acres); saturated thickness decreased more 

than 25 percent in 14,000 mi2 (9 million acres). About 

166 million acre-ft of water was removed from aquifer 

storage from predevelopment to 1980. About 16 percent 

of the depletion occurred in Kansas and 70 percent occurred in Texas. No significant changes in saturated 

thickness of the High Plains aquifer occurred in South 

Dakota or Wyoming.

Increases in saturated thickness occurred in 

Nebraska and Texas (fig. 8). In Nebraska, recharge to 

the High Plains aquifer from surface-water irrigation 

and leakage from canals and reservoirs has increased 

saturated thickness in two areas. In Texas, the increase 

in saturated thickness was the result of increased 

recharge caused by clearing sandy soils of native 

vegetation.

Areas of significant decreases in saturated thickness 

generally occurred where the aquifer has been pumped 

for irrigation for a long time. Large-scale irrigation 

development began in the southern High Plains of New 

Mexico and Texas about 1940. As of 1980, saturated 

thickness had decreased more than 25 percent in more 

than one-quarter of the High Plains of New Mexico and 

Texas. Saturated thickness also had decreased more 

than 25 percent in parts of Kansas and Oklahoma where 

large-scale irrigation development began about 1950. 

In Colorado, northwestern Kansas, Nebraska, and
A14 REGIONAL AQUIFER-SYSTEM ANALYSIS

104° 103° 102° 1010 100° 99°

43°

Rise more than 10 

10to-10

-10 to-50

-50 to-100

Decline more than-100

FIGURE 7. Water-level changes in the High Plains aquifer, predevelopment to 1980.
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS A15

43°

42°

40°

Saturated-thickness changes

in percent 

Increase more than 10

10 to-10

-10 to-25

Decrease more than -25

FIGURE 8. Saturated-thickness changes in the High Plains aquifer, predevelopment to 1980.
A16 REGIONAL AQUIFER-SYSTEM ANALYSIS

Wyoming, most of the irrigation development has taken 

place since 1960. A large area of 10-25 percent decrease 

in saturated thickness occurred in Colorado and Kansas, and several smaller areas occurred in Kansas, 

Nebraska, and Wyoming (fig. 8). In these areas, groundwater pumpage is beginning to substantially decrease 

saturated thickness.

Changes in saturated thickness are important because 

large changes in saturated thickness are directly related 

to changes in well yield. In Texas, more than 10-percent 

decrease in saturated thickness occurred in 74 percent, 

or 26,000 mi2 (17 million acres), of the High Plains aquifer, more than 25-percent decrease in saturated thickness occurred in 29 percent of the aquifer, and more than 

50-percent decrease in saturated thickness occurred in 

8 percent of the aquifer. Saturated thickness decreased 

more than 50 percent in large parts of Castro, Crosby, 

Floyd, Hale, Lubbock, Farmer, and Swisher Counties, 

south of the Canadian River. The impact of this depletion of the aquifer is illustrated by figure 9, which shows 

the decrease in the average number of acres irrigated 

per well in these seven Texas counties from 1958 to 1980. 

Each data point on the graph is the average for all seven 

counties for each year of data. The average number of 

acres irrigated per well in these seven counties decreased 

from 118 in 1958 to 62 in 1980. This decrease in acres 

irrigated per well is the result of decreasing well yields 

caused by decreasing saturated thickness. From 1958 

to 1980, the number of irrigated acres in the seven counties decreased from 2.5 to 1.9 million, and the number 

of wells increased from about 21,000 to 30,000. Decreased well yields and increased pumping lifts in these 

seven counties have undoubtedly caused significant increases in farm-operation expenses. Similar declines in 

well yields can be expected as ground-water development 

continues in other areas of the High Plains.

DIGITAL MODELS

Digital models of ground-water flow in the High Plains 

aquifer were developed and calibrated by Luckey and 

others (1986). The High Plains aquifer system was divided into three parts for simulation as shown in figure 

10. The southern High Plains included most of the area 

(29,000 mi2) south of approximately lat 35 ° N., the central High Plains included the area (48,500 mi2) between 

lat 35° and 39° N., and the northern High Plains included the area (96,500 mi2) north of lat 39° N. Separate 

ground-water flow models were constructed for each part 

of the High Plains.

MODEL CALIBRATION

The models of the High Plains aquifer simulate

130

120 -

110 -

100 -

Data averaged from seven Texas counties

1955 1960 1965 1970 1975 1980 

FIGURE 9. Acres irrigated per well in seven Texas counties.

ground-water flow in two dimensions for a heterogeneous, isotropic, unconfined aquifer. A two-dimensional 

model was used because, on a regional scale, the vertical 

components of flow are small and probably can be 

neglected without causing significant errors in the 

results. A computer program was used to solve the 

finite-difference approximations to the ground-water 

flow equation for a regular network of nodes spaced 10 

mi apart in both the north-south and the east-west directions (Luckey and others, 1986, p. 3-8).

Four general categories of information were needed for 

use in the models: (1) Aquifer geometry (vertical and 

areal extent of the aquifer), (2) boundary conditions 

(hydraulic conditions at the limit of the aquifer), (3) 

aquifer parameters (hydraulic conductivity and specific 

yield), and (4) aquifer stresses (recharge and discharge). 

In addition, some model simulations required specification of an initial water-level configuration. The models 

integrate the input data and calculate water levels and 

outflow from the aquifer.

For each area of the High Plains, models were constructed to simulate the system prior to large-scale irrigation development (predevelopment-period model) 

and after the beginning of large-scale development 

(development-period model). The development period 

was assumed to be 1940 through 1979 for the southern 

High Plains, 1950 through 1979 for the central High 

Plains, and 1960 through 1979 for the northern High 

Plains. Although both predevelopment-period and 

development-period models are useful in understanding
REGIONAL AQUIFER-SYSTEM ANALYSIS

'05° 104° 103° 102° 101° 100° 99°

A17

97° 96°

NEBRASKA

NORTHERN HIGH

I CENTRAL 

HIGH PLAINS

FIGURE 10. Subdivisions used in modeling ground-water flow in the High Plains aquifer.
A18 REGIONAL AQUIFER-SYSTEM ANALYSIS

the hydrology, the development-period models were 

used to refine the concepts needed to estimate future 

water levels in the High Plains aquifer.

Prior to extensive agricultural development, the 

ground-water system in the High Plains was in a state 

of dynamic equilibrium with long-term natural recharge 

balanced by discharge along the eastern boundary 

and to streams (steady-state conditions). The 

predevelopment-period models simulated steady-state 

conditions and calculated a water-level configuration 

using estimates of the altitude of the base of aquifer, 

hydraulic conductivity, and predevelopment recharge. 

The estimated predevelopment recharge rate and 

hydraulic conductivity were varied in individual simulations until the calculated predevelopment water level 

was similar to the observed predevelopment water-level 

map, which was based on observation-well data, and the 

computed outflow to streams was comparable to the 

observed streamflow from gaging-station records.

The calculated predevelopment water levels were used 

as the initial conditions for the development-period 

models. Revised estimates of hydraulic conductivity 

and recharge from the predevelopment-period models 

were incorporated into the development-period models. 

In addition, the development-period models required information on the specific yield of the aquifer and aquifer 

stresses that occurred as a result of development. The 

distribution of specific yield was estimated using lithologic logs and was not varied during calibration. Pumpage for irrigation and return flow from irrigation were 

the predominant stresses resulting from development. 

Pumpage was calculated using reported irrigated 

acreage, calculated irrigation demand, and estimated irrigation efficiency. Return flow from irrigation was 

assumed to be a function of the difference between total 

pumpage and calculated irrigation demand. The 

development-period models integrated the input data 

and calculated the water-level configuration and the 

outflow from the aquifer. The inputs, particularly return 

flow from irrigation, were varied until the best correspondence between observed and calculated water 

levels or water-level changes was achieved.

MODEL SENSITIVITY

A sensitivity analysis was performed on the groundwater flow models to determine how changes in model 

input parameters affect simulation results (Luckey 

and others, 1986, p. 47-52). Separate sensitivity analyses were made for the predevelopment- and the 

development-period models. The sensitivity analyses 

consisted of uniformly changing values of input data 

and determining the change in water levels and groundwater discharge calculated by the models.

The sensitivity analysis for the predevelopmentperiod models indicated that the models were about 

equally sensitive to changes in recharge or changes in 

hydraulic conductivity. The analysis further indicated 

that recharge and hydraulic conductivity are highly interrelated and, as long as the two are in balance, the 

models will have small mean residuals (difference between observed and calculated water levels). Hence, the 

models could be used to accurately determine recharge 

only if the hydraulic conductivity is accurately known.

The sensitivity of the development-period models to 

changes in hydraulic conductivity, specific yield, and 

net pumpage (pumpage minus return flow to the 

aquifer) was evaluated. The development-period models 

were sensitive to changes in net pumpage and specific 

yield and insensitive to changes in hydraulic conductivity. Specific yield and net pumpage also are highly 

interrelated, and one cannot be accurately determined 

through a model analysis unless the other is accurately known. If neither is accurately known, calibration of 

the models can only insure that specific yield and net 

pumpage are in balance.

Calibration of the models verifies that appropriate 

parameters are in balance. Because hydraulic conductivity and specific yield were estimated independently 

of the models, they were known more accurately than 

recharge and net pumpage prior to model calibration. 

However, the sensitivity analyses demonstrated the interrelation between hydraulic conductivity and recharge 

for the predevelopment-period models and between 

specific yield and net pumpage for the developmentperiod models. Therefore, the model-calibration process 

provided estimates of the distribution of recharge and 

net pumpage that are about as accurate as the estimates 

of hydraulic conductivity and specific yield.

A model of the southern High Plains using 5-mi grid 

spacing was developed to test the effect of grid size on 

model results (Luckey and Stephens, 1987). The 5-migrid model was calibrated for the predevelopment and 

development periods.

Calibration of the 5-mi-grid and 10-mi-grid models for 

the southern High Plains did not produce identical 

water-level configurations, although the mean of the differences was near zero (difference between water levels 

calculated by the 5-mi-grid and 10-mi-grid models). 

Simulations using the 5-mi-grid model resulted in the 

same conclusions that were obtained from the 10-migrid model, indicating that grid size probably does not 

significantly affect the calibration and sensitivity 

analysis of the models of the High Plains aquifer.

EFFECTS OF FUTURE PUMPAGE

The calibrated models for the three areas of the High 

Plains were used by Luckey and others (in press) to
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS A19

project aquifer response to estimated pumpage from 

1980 to 2020. The pumpage estimates were based on 

projections of future withdrawal of water made by the 

Economic Development Administration (EDA), U.S. 

Department of Commerce.

PUMPAGE ESTIMATES

The EDA study estimated pumpage from much of the 

High Plains aquifer for 1977,1985,1990, 2000, and 2020 

(High Plains Associates, 1982; High Plains Study Council, 1982) for several different water-resource management strategies. Pumpage estimates for three of those 

strategies were used to project future water levels in 

the High Plains. The three management strategies 

simulated were:

1. Baseline strategy a water-use projection 

based on a continuation of existing water conservation and use technology, practices, and 

public policy;

2. Management strategy 1 a water-use projection based on voluntary actions to reduce water 

use through research, education, and incentives; 

and

3. Management strategy 2 a water-use projection based on mandatory programs of a regulatory nature to reduce water use. 

The baseline strategy assumes a continuation of current government policies and economic trends with no 

new State or Federal programs undertaken that have not 

already been implemented or authorized. Management 

strategy 1 assumes faster adoption of new techniques 

to conserve water and voluntary measures to reduce irrigation water use. Management strategy 2 assumes 

that, in addition to the voluntary water conservation 

measures assumed under management strategy 1, mandatory water conservation measures would be imposed 

by governmental agencies. Under management strategy 

2, water application rates for 1985,1990, and 2000 were 

assumed to be reduced to 90, 80, and 70 percent of those 

projected for management strategy 1, respectively. Between 2000 and 2020, water application rates were 

assumed to continue to be 70 percent of those projected 

for management strategy 1.

Pumpage was simulated using 5-yr averages between 

1980 and 2020. The pumpage estimates were based on 

the EDA projections made by the High Plains 

Associates (1982). Pumpage estimates for intervening 

years were based on linear interpolation of the EDA projections. Pumpage estimates for areas not included in 

the EDA study (primarily South Dakota and Wyoming) 

were based on assumed irrigated acreage and application rates.

The pumpage from the High Plains aquifer simulated 

for each management strategy and each 5-yr interval 

is summarized in figure 11. Average annual pumpage 

simulated for each 5-yr interval varied little between the 

baseline strategy and management strategy 1; however, 

average annual pumpage for management strategy 2 

was as much as 27 percent less than for the baseline 

strategy. The total pumpage simulated for the baseline 

strategy between 1980 and 2020 was 628 million acreft including 113 million acre-ft in the southern High 

Plains, 158 million acre-ft in the central High Plains, 

and 357 million acre-ft in the northern High Plains. The 

total pumpage simulated for management strategy 1 

between 1980 and 2020 was 647 million acre-ft including 

109 million acre-ft in the southern High Plains, 178 

million acre-ft in the central High Plains, and 360 million 

acre-ft in the northern High Plains. The total pumpage 

simulated for management strategy 2 between 1980 and 

2020 was 497 million acre-ft including 88 million acreft in the southern High Plains, 138 million acre-ft in the 

central High Plains, and 271 million acre-ft in the northern High Plains. Lower water use for management 

strategy 1 results in larger total pumpage than for the 

baseline strategy because more acreage would be 

irrigated.

COMPARISON OF PROJECTIONS

Pumpage was simulated using the projection models 

of the southern, central, and northern High Plains. 

However, return flow from irrigation (that part of pumpage that returns to the aquifer) was not considered in 

the projection models. During the model calibration 

process, return flow was assumed to be a function of 

water applied in excess of the irrigation requirement. 

Because pumpage estimates for most of 1980 to 2020 

were less than estimated irrigation requirement, return 

flow was assumed to be negligible (and not simulated) 

during the projection period.

The projected 1980-to-2020 water-level change, 

assuming baseline-strategy pumpage from the High 

Plains aquifer, is shown in figure 12. Between 1980 and 

2020, most of the High Plains will have water-level 

declines in excess of 10 ft. Declines are projected to exceed 100 ft in about 15,500 mi2 in parts of all States 

except South Dakota and Wyoming. The maximum 

1980-to-2020 water-level decline is projected to be 

almost 250 ft in northern Texas. In two small areas in 

the southern High Plains (not shown in figure 12), water 

levels are projected to rise more than 10 ft (Luckey and 

others, in press, fig. 6).

The average water-level decline from 1980 to 2020 

for the baseline strategy in the entire High Plains is
REGIONAL AQUIFER-SYSTEM ANALYSIS

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 t

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1980 to 1984 1985 to 1989 1 990 to 1 994 1995 to 1999 2000 to 2004 2005 to 2009 2010 to 201 4 201 5 to 201 9 

FIGURE 11. Simulated pumpage by management strategy, 1980 to 2020.

projected to be about 32 ft, and the median decline is 

projected to be about 13 ft; the median indicates that 

water-level declines will exceed 13 ft in one-half of the 

High Plains. The average 1980-to-2020 water-level 

decline for the baseline strategy is projected to be 32 ft 

in the southern High Plains, 26 ft in the central High 

Plains, and 36 ft in the northern High Plains. The 

median 1980-to-2020 water-level decline for the baseline 

strategy is projected to be 13 ft in the southern High 

Plains, 11 ft in the central High Plains, and 14 ft in the 

northern High Plains. The projected 1980-to-2020 

water-level declines are in addition to the water-level 

declines of as much as 200 ft that occurred in the High 

Plains prior to 1980 (Luckey and others, 1981).

The projected saturated thickness remaining in the 

High Plains by 2020, assuming baseline-strategy pumpage, is shown in figure 13. Saturated thickness is projected to exceed 100 ft in 72,500 mi2 (42 percent) and 

200 ft in 37,600 mi2 (22 percent) of the High Plains.

Areas where projected saturated thickness would exceed 200 ft in 2020 are significantly smaller than they 

were in 1980 (compare figs. 3 and 13). The average 

saturated thickness for the entire High Plains was 

about 200 ft in 1980. By 2020, the saturated thickness 

averages 154 ft for the entire High Plains, 36 ft for the 

southern High Plains, 104 ft for the central High Plains, 

and 217 ft for the northern High Plains. The maximum 

saturated thickness projected for 2020 exceeds 800 ft 

in 1,650 mi2 in the northern High Plains, 400 ft in 

400 mi2 in the central High Plains, and 100 ft in 

1,500 mi2 in the southern High Plains.

The projected 1980-to-2020 water-level changes, 

assuming management-strategy-1 pumpage from the 

High Plains aquifer, are virtually the same as for the 

baseline strategy. The maximum water-level decline 

from 1980 to 2020 is projected to be about 230 ft in 

northern Texas. Although the maximum decline is 

smaller for management-strategy-1 pumpage than for
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS

106° 105° 104° 1030 1020 101 o 10Do 99° 98° 97°

A21

43°

42°

40°

Water-level change

in feet 

Less than-10

37°

FIGURE 12. Projected water-level changes assuming baseline-strategy pumpage, 1980 to 2020.
A22 REGIONAL AQUIFER-SYSTEM ANALYSIS

42° -

103° 102° 101° 100° 99° 98° 97

&?/ COLORADO

EXPLANATION

Saturated-thickness

in feet 

Less than 100

FIGURE 13. Projected saturated thickness by 2020 assuming baseline-strategy pumpage.
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS A23

baseline-strategy pumpage, there generally is little difference in water-level declines between the two 

strategies because total management-strategy-1 pumpage is only 3 percent more than total baseline-strategy 

pumpage. The average 1980-to-2020 water-level decline 

projected for the baseline strategy is 32 ft, and the 

average decline projected for management strategy 1 

is 33 ft. The median water-level decline projected for the 

same period is 13 ft for both strategies.

Water-level changes projected for management 

strategy 2 are significantly different from the baseline 

strategy. The projected 1980-to-2020 water-level change 

in the High Plains aquifer, assuming managementstrategy-2 pumpage, is shown in figure 14. Water levels 

are projected to decline more than 10 ft in 86,370 mi2 

and more than 100 ft in 9,100 mi2 of the High Plains. 

The maximum water-level decline from 1980 to 2020 is 

projected to be about 180 ft in northern Texas.

The mandatory reduction in water use will reduce 

water-level changes compared to those for the baseline 

strategy. The average 1980-to-2020 water-level decline 

projected for management strategy 2 is 26 ft, and the 

median decline is 11 ft. The average water-level decline 

from 1980 to 2020 is projected to be 26 ft in the 

southern High Plains, 22 ft in the central High Plains, 

and 28 ft in the northern High Plains. The median 

decline is projected to be 11 ft in the southern High 

Plains, 10 ft in the central High Plains, and 11 ft in the 

northern High Plains.

Smaller declines result in significantly more saturated 

thickness projected for management strategy 2 than for 

the baseline strategy. The average saturated thickness 

by 2020, assuming management-strategy-2 pumpage, 

is projected to be 160 ft in the entire High Plains, 42 ft 

in the southern High Plains, 107 ft in the central High 

Plains, and 225 ft in the northern High Plains. The 

average saturated thickness by 2020 is projected to be 

154 ft assuming baseline-strategy pumpage. The difference in saturated thickness between the baseline 

strategy and management strategy 2 is shown in figure 

15. More than 50 ft of saturated thickness could be 

saved in several areas that total 1,830 mi2 as a result 

of the mandatory reduction in water use assumed for 

management strategy 2. The maximum difference between the baseline strategy and management strategy 

2 is projected to be 68 ft in 2020. The difference in 

saturated thickness is projected to exceed 10 ft in 23 

percent of the High Plains.

The total volume of water removed from storage in the 

aquifer from 1980 to 2020 is projected to be 429 million 

acre-ft for management-strategy-two pumpage of 497 

million acre-ft. The difference (68 million acre-ft) between 

the volume of water removed from storage and the 

volume pumped is supplied by reduced ground-water

discharge to streams and the atmosphere. The volume 

removed from storage was 80 million acre-ft in the 

southern High Plains, 121 million acre-ft in the central 

High Plains, and 228 million acre-ft in the northern High 

Plains. Prior to 1980, the total volume of water removed 

from storage was 166 million acre-ft.

Lower pumpage simulated for management strategy 

2 results in smaller water-level declines, larger saturated 

thickness, and more water in storage by 2020 than for 

the other strategies. The average water level would be 

6 ft higher and average saturated thickness would be 

6 ft greater for management strategy 2 than for the 

baseline strategy. From 1980 to 2020, the total volume 

of water removed from storage in the High Plains 

aquifer is projected to be 530 million acre-ft assuming 

baseline-strategy pumpage and 429 million acre-ft 

assuming management-strategy-2 pumpage. The difference of 101 million acre-ft that results from less water 

use projected for management strategy 2 is adequate 

to supply the 2020 pumpage (assuming management 

strategy 2) in the High Plains for nearly 9 years. Waterlevel-decline, saturated-thickness, and change-in-storage 

projections are summarized by management strategy 

in the following table:

Strategy

Average waterlevel decline 

from 1980 to 2020 

(feet)

Average

saturated

thickness by 2020

(feet)

Change in groundwater storage from

1980 to 2020 

(millions of acre-feet)

Baseline

strategy.

Management

strategy 1.

Management

strategy 2.

32

33

26

154

153

160

530

546

429

The projected declines in water levels and saturated 

thickness will reduce well yields. Luckey and others (in 

press, fig. 26) estimated the percentage change in probable well yields from 1980 to 2020 based on the difference in probable well yield in 1980 and that projected 

for 2020 assuming baseline-strategy pumpage. In 

general, declines in well yields are projected to be least 

in the northern High Plains and greatest in the southern 

High Plains. In about 17 percent of the High Plains, 

probable well yields are projected to decrease by more 

than 75 percent from 1980 to 2020. In 42 percent of the 

area, well yields are projected to decrease by more than 

25 percent by 2020.

Based on projections made by the High Plains Associates (1982), a redistribution of irrigated agriculture 

will occur between 1980 and 2020. Irrigated agriculture 

is expected to decline in Colorado, Kansas, New Mexico, Oklahoma, and Texas and increase greatly in 

Nebraska. This redistribution in irrigated agriculture
A24 REGIONAL AQUIFER-SYSTEM ANALYSIS

970 96°

38°

EXPLANATION

Water-level change

in feet 

Less than -10

-10 to-50

FIGURE 14. Projected water-level changes assuming management-strategy-2 pumpage, 1980 to 2020.
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS

105° 104° 103o 102o )01 o 100o 990 Qflo 97° 96°

A25

43°

Difference in saturated

thickness by 2020, in feet 

Less than -10

FIGURE 15. Difference in projected saturated thickness by 2020 between management strategy 2 and the baseline

strategy.
A26 REGIONAL AQUIFER-SYSTEM ANALYSIS

may be the result of decreasing well yields caused by 

declining water levels and decreasing saturated 

thickness.

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SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS A27

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Remote Sensing, v. 50, no. 10, p. 1479-1490.

Krothe, N.C., 1981, Quality of ground water in the High Plains aquifer 

[abs.]: Transactions of the American Geophysical Union, v. 62, 

no. 45, p. 872.

___1985, Chemistry of ground water in the High Plains aquifer 

[abs.], in The impact of regional variation on hydrogeologic investigations: Annual Meeting of the Association of Ground Water 

Scientists and Engineers, National Water Well Association, 

Baltimore, Md., 1985, p. 19.
A28 REGIONAL AQUIFER-SYSTEM ANALYSIS

Krothe, N.C., and Oliver, J.W., 1982, Sulphur isotopic composition 

and water chemistry in water from the High Plains aquifer, 

Oklahoma Panhandle and southwestern Kansas: U.S. Geological 

Survey Water-Resources Investigations Report 82-12, 28 p.

Krothe, N.C., Oliver, J.W., and Weeks, J.B., 1982, Dissolved solids 

and sodium in water from 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-658, scale 1:2,500,000, 2 sheets.

Lindner-Lunsford, J.B., and Borman, R.G., 1985, Potential well yields 

from the Ogallala aquifer in the northern High Plains of Colorado: 

U.S. Geological Survey Hydrologic Investigations Atlas HA-685, 

scale 1:1,000,000, 1 sheet.

Lohman, S.W., 1953, High Plains of west-central United States, 

general aspects, chapter 4 of Subsurface facilities of water management and patterns of supply-type area studies, v. 4 o/The physical 

and economic foundation of natural resources: U.S. 83d Congress, 

House Committee on Interior and Insular Affairs, p. 70-78.

Loskot, C.L., Case, H.L., III, and Hern, D.G., 1984, Geologic and 

hydrologic data from a test-drilling program in the High Plains 

area of South Dakota, 1979-80: U.S. Geological Survey Open-File 

Report 84-148, 31 p.

Luckey, R.R., 1984a, The High Plains regional aquifer Flow system 

simulation of the central and northern High Plains, in Whetstone, 

G.A., ed., Proceedings of the Ogallala Aquifer Symposium II: Lubbock, Tex., Texas Tech University, p. 48-66.

___1984b, Projected effects of ground-water development in the 

southern High Plains of Texas and New Mexico: Annual Conference of the American Water Works Association, Dallas, Tex., 

1984, Proceedings, p. 1345-1362. 

.1985, Projected effects of ground water development in the High

Plains in parts of Colorado, Kansas, Nebraska, New Mexico, 

Oklahoma, South Dakota, Texas, and Wyoming [abs.], in The impact of regional variation on hydrogeologic investigations: Annual Meeting of the Association of Ground Water Scientists and 

Engineers, National Water Well Association, Baltimore, Md., 

1985, p. 23-24.

Luckey, R.R., and Ferrigno, C.F., 1982, A data-management system 

for area! interpretive data for the High Plains in parts of Colorado, 

Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, 

and Wyoming: U.S. Geological Survey Water-Resources Investigations Report 82-4072, 112p.

Luckey, R.R., Gutentag, E.D., Heimes, F.J., and Weeks, J.B., 1986, 

Digital simulation of ground-water flow in 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-D, 57 p.

___in press, Effects of future ground-water pumpage on 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-E.

Luckey, R.R., Gutentag, E.D., and Weeks, J.B., 1981, Water-level 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, scale 

1:2,500,000, 2 sheets.

Luckey, R.R., Heimes, F.J., and Gaggiani, N.G., 1980, Calibration and 

testing of selected portable flowmeters for use on large irrigation 

systems: U.S. Geological Survey Water-Resources Investigations 

Report 80-72, 21 p.

Luckey, R.R., and Nethaway, C.D., Jr., 1980, Design and implementation of a data base to store area! hydrologic information [abs.]: 

American Geophysical Union, Transactions, v. 61, no. 46, p. 953.

Luckey, R.R., and Stephens, D.M., 1987, Effect of grid size on digital

simulation of ground-water flow in the southern High Plains of 

Texas and New Mexico: U.S. Geological Survey Water-Resources 

Investigations Report 87-4085, 32 p.

Mackey, G.W., 1987, Comparison of irrigation pumpage and change 

in water storage in the High Plains aquifer in Castro and Farmer 

Counties, Texas, 1975-83: U.S. Geological Survey WaterResources Investigations Report 87-4032, 48 p.

Martinko, E.A., Poracsky, J., Kipp, E.R., Krieger, H., and Gunn, K., 

1981, Crop phenology and Landsat-based irrigated lands inventory in the High Plains: Lawrence, Kans., University of Kansas, 

Applied Remote Sensing Program Final Report NAG 2-57,129 p.

McAda, D.P., 1984, Projected water-level declines in the Ogallala 

aquifer in Lea County, New Mexico: U.S. Geological Survey 

Water-Resources Investigations Report 84-4062, 84 p.

Muller, D.A., 1980, Results of surface electrical resistivity surveys: 

Texas Department of Water Resources Report LP-130, 27 p.

Nordstrom, P.L., 1984, Estimation of specific yield using drillers' 

lithologic descriptions, in Whetstone, G.A., ed., Proceedings of 

the Ogallala Aquifer Symposium II: Lubbock, Tex., Texas Tech 

University, p. 265-277.

Pabst, M.E., and Stullken, L.E., 1982a, Altitude and configuration 

of the water table in the High Plains aquifer of Kansas, 1970: U.S. 

Geological Survey Open-File Report 82-448, scale 1:500,000, 1 

sheet.

__1982b, Altitude and configuration of the water table in the High 

Plains aquifer of Kansas, 1960: U.S. Geological Survey WaterResources Investigations Report 82-429, scale 1:500,000,1 sheet.

___1982c, Altitude and configuration of the water table in the High 

Plains aquifer of Kansas, 1965: U.S. Geological Survey WaterResources Investigations Report 82-449, scale 1:500,000,1 sheet.

___1984, Altitude and configuration of the water table in the High

Plains aquifer of Kansas, 1980: U.S. Geological Survey WaterResources Investigations Report 81-1004, scale 1:500,000,1 sheet.

Pettijohn, R.A., and Chen, H.H., 1983a, Geohydrology of the High 

Plains aquifer system in Nebraska: U.S. Geological Survey OpenFile Report 82-502, scale 1:175,000, 3 sheets.

___1983b, Hydraulic conductivity, specific yield, and pumpage 

High Plains aquifer system, Nebraska: U.S. Geological Survey 

Water-Resources Investigations Report 82-4014, scale 1:175,000, 

3 sheets.

___1984a, Hydrologic analysis of the High Plains aquifer system 

in Box Butte County, Nebraska: U.S. Geological Survey WaterResources Investigations Report 84-4046, 54 p.

___1984b, Hydrologic characteristics and ground-water availability 

in the High Plains aquifer system in Nebraska, in Whetstone, 

G.A., ed., Proceedings of the Ogallala Aquifer Symposium II: Lubbock, Tex., Texas Tech University, p. 238-264. 

_1984c, Hydrologic characteristics and ground-water availability

in the High Plains aquifer system in Nebraska [abs.]: Midwest 

Groundwater Conference, 29th, Lawrence, Kans., 1984, Program 

with Abstracts, p. 3-4.

Rettman, P.L., and McAdoo, G.D., 1986, Irrigation data from Castro 

and Farmer Counties, Texas: U.S. Geological Survey Open-File 

Report 85-82, 35 p.

Stephens, D.M., Heimes, F. J., and Luckey, R.R., 1984, Irrigation data 

from Chase, Dundy, and Perkins Counties, southwestern 

Nebraska, 1983: U.S. Geological Survey Open-File Report 84-471, 

31 p.

___1985, Irrigation data from Chase, Dundy, and Perkins Counties, southwestern Nebraska, 1984: U.S. Geological Survey OpenFile Report 85-164, 32 p.

Stullken, L.E., and Pabst, M.E., 1981, Altitude and configuration of 

the water table in the High Plains aquifer of Kansas, 1975: U.S. 

Geological Survey Water-Resources Investigations Report 

81-144, scale 1:500,000, 1 sheet.
SUMMARY OF HIGH PLAINS REGIONAL AQUIFER-SYSTEM ANALYSIS A29

___1985, Altitude and configuration of the water table in the High 

Plains aquifer of Kansas, pre-1950: U.S. Geological Survey OpenFile Report 82-117, scale 1:500,000, 1 sheet.

Stullken, L.E., Watts, K.R., and Lindgren, R.J., 1985, Geohydrology 

of the High Plains aquifer, western Kansas: U.S. Geological 

Survey Water-Resources Investigations Report 85-4198, 86 p.

Thelin, G.P., 1984, The High Plains regional aquifer Mapping irrigated agriculture using Landsat data, in Whetstone, G.A., ed., 

Proceedings of the OgaUala Aquifer Symposium II: Lubbock, Tex., 

Texas Tech University, p. 40-47.

Thelin, G.P., and Heimes, F.J., 1980, Estimating area! extent of irrigated cropland using Landsat digital data [abs.]: American 

Geophysical Union, Transactions, v. 61, no. 46, p. 953.

___in press, Mapping irrigated cropland from Landsat data for 

determination of water use from 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-C.

Thelin, G.P., Johnson, T.L., and Johnson, R.A., 1981, Mapping irrigated cropland on the High Plains using Landsat, in Deutsch, 

Morris, Wiesnet, D.R., and Rango, Albert, eds., Satellite hydrology; Annual William T. Pecora Symposium on Remote Sensing, 

5th, Sioux Falls, S. Dak., 1979, Proceedings: Minneapolis, Minn., 

American Water Resources Association, p. 715-721.

U.S. Department of Agriculture, 1967, Irrigation water requirements: 

Soil Conservation Service, Engineering Division, Technical Release 

no. 21, 88 p.

___1976, Crop consumptive irrigation requirements and irrigation 

efficiency coefficients for the United States: Soil Conservation 

Division, Special Projects Division, 352 p.

U.S. Department of Commerce, 1949-78, Census of agriculture: Bureau 

of the Census, agricultural data for 1949,1954,1959,1964,1969, 

1974, and 1978 for Colorado, Kansas, Nebraska, New Mexico, 

Oklahoma, South Dakota, Texas, and Wyoming.

U.S. Environmental Protection Agency, 1976, National interim 

primary drinking water regulations: Office of Water Supply, 

EPA-570/9-76-003, 159 p.

___1977, National secondary drinking water regulations: Federal 

Register, v. 42, no. 62, Thursday, March 31, 1977, Part I, 

p.17143-17147.

U.S. Salinity Laboratory Staff, 1954, Diagnosis and improvement of 

saline and alkali soils: U.S. Department of Agriculture Handbook 

60, 160 p.

Watts, K.R., and Stullken, L.E., 1985, Generalized configuration of 

the base of the High Plains aquifer in Kansas: U.S. Geological 

Survey Open-File Report 81-344, scale 1:500,000, 1 sheet.

Weeks, J.B., 1978a, Plan of study for the High Plains regional aquifersystem analysis in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming: U.S. 

Geological Survey Water-Resources Investigations Report 78-70, 

28 p.

___1978b, High Plains regional aquifer-system analysis: Groundwater Management Districts Association Conference, 5th, 

Amarillo, Tex., 1978, Proceedings, p. 13-16.

___I978c, High Plains regional aquifer-system analysis, in Baird, 

F.L., ed., The multi-faceted water crisis of west Texas: Lubbock, 

Tex., Texas Tech University, Symposium, 1978, Proceedings, 

p. 195-201.

___1979, High Plains regional aquifer-system analysis Progress 

report: Groundwater Management Districts Association Conference, 6th, Colorado Springs, Colo., 1979, Proceedings, p. 10-13.

___1981, Effects of pumpage on the High Plains aquifer: Groundwater Management Districts Association Conference, 8th, Lubbock, Tex., 1981, Proceedings, p. 97-108.

___1985a, Geohydrology of the High Plains aquifer [abs.], in The

impact of regional variation on hydrogeologic investigations: Annual Meeting of the Association of Ground Water Scientists and 

Engineers, National Water Well Association, Baltimore, Md., 

1985, p. 18.

_1985b, A bibliography of the High Plains regional aquifersystem analysis: Groundwater Management Districts Association Conference, 12th, Reno, Nev., 1985, Proceedings, p. 4-18.

_1986a, High Plains regional aquifer-system study, in Sun, R.J., 

ed., Regional aquifer-system analysis program of the U.S. 

Geological Survey Summary of projects, 1978-84: U.S. 

Geological Survey Circular 1002, p. 30-49.

__1986b, High Plains regional aquifer system, phase II study, 

in Sun, R.J., ed., The regional aquifer-system analysis program 

of the U.S. Geological Survey Summary of projects, 1978-84: 

U.S. Geological Survey Circular 1002, p. 255-258. 

.1987, Geohydrology of the High Plains aquifer [abs.]: Geological

Society of America, Rocky Mountain Section, 40th Annual 

Meeting, Boulder, Colo., May 2-4,1987, Abstracts with Programs, 

v. 19, no. 5, p. 341.

Weeks, J.B., and Gutentag, E.D., 1981, Bedrock geology, altitude of 

base, and 1980 saturated thickness of 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-648, scale 1:2,500,000, 2 

sheets.

___1984, The High Plains regional aquifer Geohydrology, in 

Whetstone, G.A., ed., Proceedings of the Ogallala Aquifer Symposium II: Lubbock, Tex., Texas Tech University, p. 6-25.

___in press, Region 17, the High Plains, in Back, William, Rosenshein, J. S., and Seaber, P.R., eds., Hydrogeology: Boulder, Colorado, Geological Society of America, The Geology of North 

America, v. O-2.

Weeks, J.B., and Luckey, R.R., in press, Simulated effects of future 

pumpage on the High Plains aquifer, west-central United 

States: International Groundwater Conference, University 

Kebangsaan Malaysia, Kuala Lumpur, Malaysia, June 22-26, 

1987, Proceedings.

Wright, Bruce, 1980a, Irrigated cropland, 1978, Curry County, New 

Mexico: U.S. Geological Survey Open-File Report 80-169, scale 

1:250,000, 1 sheet.

___1980b, Irrigated cropland, 1978, Texas County, Oklahoma: U.S. 

Geological Survey Open-File Report 80-170, scale 1:250,000, 

1 sheet.

Wyatt, A.W., Smith, D.D., and McReynolds, Don, 1981a, Hydrologic 

atlas for Armstrong County, Texas: Lubbock, Tex., High Plains 

Underground Water Conservation District No. 1, scale 1:126,720, 

4 sheets.

___1981b, Hydrologic atlas for Bailey County, Texas: Lubbock, 

Tex., High Plains Underground Water Conservation District No. 

1, scale 1:126,720, 4 sheets.

___1981c, Hydrologic atlas for Castro County, Texas: Lubbock, 

Tex., High Plains Underground Water Conservation District No. 

1, scale 1:126,720, 4 sheets.

___1981d, Hydrologic atlas for Cochran County, Texas: Lubbock, 

Tex., High Plains Underground Water Conservation District No. 

1, scale 1:126,720, 4 sheets.

___1981e, Hydrologic atlas for Crosby County, Texas: Lubbock, 

Tex., High Plains Underground Water Conservation District No. 

1, scale 1:126,720, 4 sheets.

___1981f, Hydrologic atlas for Deaf Smith County, Texas: Lubbock, Tex., High Plains Underground Water Conservation District 

No. 1, scale 1:126,720, 4 sheets.

____1981g, Hydrologic atlas for Floyd County, Texas: Lubbock, 

Tex., High Plains Underground Water Conservation District No. 

1, scale 1:126,720, 4 sheets.
A30 REGIONAL AQUIFER-SYSTEM ANALYSIS

__1981h, Hydrologic atlas for Hale County, Texas: Lubbock, Tex.,

High Plains Underground Water Conservation District No. 1, scale

1:126,720, 4 sheets. 

__1981i, Hydrologic atlas for Hockley County, Texas: Lubbock,

Tex., High Plains Underground Water Conservation District No.

1, scale 1:126,720, 4 sheets. 

_1981J, Hydrologic atlas for Lamb County, Texas: Lubbock,

Tex., High Plains Underground Water Conservation District No.

1, scale 1:126,720, 4 sheets. 

_1981k, Hydrologic atlas for Lubbock County, Texas: Lubbock,

Tex., High Plains Underground Water Conservation District No.

1, scale 1:126,720, 4 sheets.

_19811, Hydrologic atlas for Lynn County, Texas: Lubbock, Tex.,

High Plains Underground Water Conservation District No. 1, scale

1:126,720, 4 sheets. 

_1981m, Hydrologic atlas for Farmer County, Texas: Lubbock,

Tex., High Plains Underground Water Conservation District No.

1, scale 1:126,720, 4 sheets. 

__1981n, Hydrologic atlas for Potter County, Texas: Lubbock,

Tex., High Plains Underground Water Conservation District No.

1, scale 1:126,720, 4 sheets. 

_1981o, Hydrologic atlas for Randall County, Texas: Lubbock,

Tex., High Plains Underground Water Conservation District No.

1, scale 1:126,720, 4 sheets.

A U.S. GOVERNMENT PRINTING OFFICE: 1988 573-047/66,075 REGION NO. 8