U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010-5014

Prepared in cooperation with the Arkansas Natural Resources Commission and the 

Arkansas Geological Survey

Potentiometric Surfaces and Water-Level Trends in 

the Cockfield (Upper Claiborne) and Wilcox (Lower Wilcox)

Aquifers of Southern and Northeastern Arkansas, 2009

36o

35o

34o

94o 93o 92o 91o

90o

MISSOURI

MISSISSIPPI

TEXAS

OKLAHOMA

TENNESSEE

LOUISIANA

ATLANTIC

West Gulf Coastal Plain

Mississippi

Alluvial

Plain

Ouachita Mountains

Ozark Plateaus

Coastal Plain

INTERIOR

HIGHLANDS

Ouachita

province

Arkansas Valley

PLAIN

CLAY

GREENE

CRAIGHEAD MISSISSIPPI

POINSETT

CROSS

CRITTENDEN

ST. FRANCIS

LEE

ARKANSAS

GRANT JEFFERSON

DALLAS

CLEVELAND LINCOLN

DESHA

DREW

CHICOT

ASHLEY

BRADLEY

CALHOUN

UNION

OUACHITA

COLUMBIA

NEVADA

HEMPSTEAD

CLARK

HOT SPRING

Mississippi River
Potentiometric Surfaces and Water-Level 

Trends in the Cockfield (Upper Claiborne) 

and Wilcox (Lower Wilcox) Aquifers of 

Southern and Northeastern Arkansas, 2009

By Aaron L. Pugh

Prepared in cooperation with the Arkansas Natural Resources Commission and the

Arkansas Geological Survey

Scientific Investigations Report 2010-5014

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

This and other USGS information products are available at http://store.usgs.gov/

U.S. Geological Survey

Box 25286, Denver Federal Center

Denver, CO 80225

To learn about the USGS and its information products visit http://www.usgs.gov/

1-888-ASK-USGS

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Pugh, A.L., 2010, Potentiometric surfaces and water-level trends in the Cockfield (upper Claiborne) and Wilcox (lower 

Wilcox) aquifers of southern and northeastern Arkansas, 2009: U.S. Geological Survey Scientific Investigations Report 

2010-5014, 47 p.
iii

Contents

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

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

Methods...........................................................................................................................................................2

Cockfield Aquifer............................................................................................................................................4

Hydrogeologic Setting .........................................................................................................................4

Hydraulic Properties ...................................................................................................................5

Water Use .....................................................................................................................................5

Potentiometric Surface........................................................................................................................7

Water-Level Trends ..............................................................................................................................7

Water-Level Difference from 2003 to 2009...............................................................................7

Long-Term Hydrographs .............................................................................................................7

Wilcox Aquifer..............................................................................................................................................20

Hydrogeologic Setting .......................................................................................................................20

Hydraulic Properties .................................................................................................................20

Water Use ...................................................................................................................................20

Potentiometric Surface......................................................................................................................21

Water-Level Trends ............................................................................................................................21

Water-Level Difference from 2003 to 2009.............................................................................21

Long-Term Hydrographs ...........................................................................................................26

Summary........................................................................................................................................................34

References....................................................................................................................................................35

Appendix 1. Water-level data collected during February 2009 from wells completed in the

Cockfield aquifer in southern Arkansas .....................................................................................38

Appendix 2. Difference in depth to water from 2003 to 2009 in the Cockfield aquifer in southern

Arkansas..........................................................................................................................................40

Appendix 3. Water-level data collected during February 2009 from wells completed in the

Wilcox aquifer in southern Arkansas .........................................................................................42

Appendix 4. Water-level data collected during February 2009 from wells completed in the

Wilcox aquifer in northeastern Arkansas ..................................................................................43

Appendix 5. Difference in depth to watr from 2003 to 2009 in the Wilcox aquifer in southern

Arkansas..........................................................................................................................................45

Appendix 6. Difference in depth to water from 2003 to 2009 in the Wilcox aquifer in

northeastern Arkansas..................................................................................................................46
iv

Figures

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

2. Diagram showing well-numbering system...............................................................................4

3. Generalized section of the hydrogeologic and geologic units within the Mississippi

embayment ....................................................................................................................................5

4. Graph showing water use from the Cockfield aquifer in Arkansas, 1975-2005..................7

5. Map showing potentiometric surface of the Cockfield aquifer in southern Arkansas,

2009 .................................................................................................................................................8

6. Map showing water-level difference from 2003 to 2009 of the Cockfield aquifer in

southern Arkansas .......................................................................................................................9

7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in

southern Arkansas .....................................................................................................................11

8. Graph showing water use from the Wilcox aquifer in Arkansas, 1975-2005....................21

9. Map showing potentiometric surface of the Wilcox aquifer in southern Arkansas,

2009 ...............................................................................................................................................22

10. Map showing potentiometric surface of the Wilcox aquifer in northeastern Arkansas,

2009 ...............................................................................................................................................23

11. Map showing water-level difference from 2003 to 2009 for the Wilcox aquifer in

southern Arkansas .....................................................................................................................24

12. Map showing water-level difference from 2003 to 2009 for the Wilcox aquifer in

northeastern Arkansas ..............................................................................................................25

13. Water-level hydrographs for selected wells completed in the Wilcox aquifer in

southern Arkansas .....................................................................................................................27

14. Water-level hydrographs for selected wells completed in the Wilcox aquifer in

northeastern Arkansas ..............................................................................................................30

Tables

1. Hydrogeologic and geologic units within the Mississippi embayment of Arkansas ........6

2. Range, mean, and median of annual rise/decline in water level by county for wells

completed in the Cockfield aquifer in Arkansas, 1990-2009 ................................................10

3. Range, mean, and median of annual rise/decline in water level by county for wells

completed in the Wilcox aquifer in Arkansas, 1990-2009 ....................................................26
v

 Conversion Factors and Datums

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Flow rate

million gallons per day (Mgal/d) 0.04381 cubic meters per second (m3/s)

foot per year (ft/yr) 0.3048 meter per year (m/yr)

Specific capacity

gallon per minute per foot

(gal/min)/ft)

0.2070 liter per second per meter

(L/s)/m)

Transmissivity*

square foot per day (ft2/d) 0.09290 square meter per day (m2/d)

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 1929).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 1983).

Altitude, as used in this report, refers to distance above the vertical datum.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 25°C).

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L) or micrograms per liter (μg/L).

*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times foot of aquifer thickness 

[(ft3/d)/ft2]ft. In this report, the mathematically reduced form, square foot per day (ft2/d), is used for convenience.

Potentiometric Surfaces and Water-Level Trends in the 

Cockfield (Upper Claiborne) and Wilcox (Lower Wilcox) 

Aquifers of Southern and Northeastern Arkansas, 2009

By Aaron L. Pugh

Abstract

Eocene-age sand beds near the base of the Cockfield 

Formation of Claiborne Group constitute the aquifer known 

locally as the Cockfield aquifer. Upper-Paleocene age sand 

beds within the lower parts of the Wilcox Group constitute the 

aquifer known locally as the Wilcox aquifer. In 2005, reported 

water withdrawals from the Cockfield aquifer in Arkansas 

totaled 16.1 million gallons per day, while reported water 

withdrawals from the Wilcox aquifer in Arkansas totaled 27.0 

million gallons per day. Major withdrawals from these units 

were for industrial and public water supplies with lesser but 

locally important withdrawals for commercial, domestic, and 

agricultural uses. 

During February 2009, 56 water-level measurements 

were made in wells completed in the Cockfield aquifer and 57 

water-level measurements were made in wells completed in 

the Wilcox aquifer. The results from the 2009 water-level measurements are presented in potentiometric-surface maps and in 

combination with previous water-level measurements. 

Trends in water-level change over time within the two 

aquifers are investigated using water-level difference maps 

and well hydrographs. Water-level difference maps were constructed for each aquifer using the difference between depth to 

water measurements made in 2003 to 2009. Well hydrographs 

for each aquifer were constructed for wells with 20 or more 

years of historical water-level data. The hydrographs were 

evaluated individually using linear regression to calculate the 

annual rise or decline in water levels, and by aggregating the 

regression results by county and statistically summarizing 

for the range, mean, and median water-level change in each 

county.

The 2009 potentiometric surface of the Cockfield aquifer 

map indicates the regional direction of groundwater flow 

generally towards the east and southeast, except in two areas 

of intense groundwater withdrawals that have developed into 

cones of depression. The lowest water-level altitude measured 

was 43 feet and the highest water-level altitude measured was 

351 feet. 

A water-level difference map was constructed from 54 

wells completed in the Cockfield aquifer within Arkansas. The 

largest rise in water level was 14.9 feet and the largest decline 

was 27.4 feet. Seven wells had a rise in water level, and the 

remaining 47 wells had a decline in water level. 

Hydrographs for 33 wells completed in the Cockfield 

aquifer were developed. Hydrographs indicate water-level 

changes in individual wells ranged from rises of 0.33 feet per 

year to declines of 1.21 feet per year over the 20-year period 

(1990-2009). County summaries of the linear regression 

analysis indicate Cleveland and Columbia Counties have mean 

annual rises. Arkansas, Ashley, Bradley, Calhoun, Chicot, 

Desha, Drew, Lincoln, and Union Counties have mean annual 

declines. 

The potentiometric surface for the Wilcox aquifer is presented using two maps, one for a southern area and another for 

a northeastern area, because of the absence of water-level data 

in the central part of the State. The direction of groundwater 

flow in the southern area is generally the east, except around 

two cones of depression and around two mounds of elevated 

water levels. Water-level altitudes in the southern area range 

from 147 feet to 400 feet. The direction of groundwater flow 

in the northeastern area is generally to the south and southeast 

except in an area of intense groundwater withdrawals that has 

altered the flow to a westerly direction.

Two water-level difference maps were constructed using 

water-level altitudes measured in 2003 to 2009 from 53 wells 

completed in the Wilcox aquifer within southern and northeastern Arkansas. In the southern area the largest rise in water 

level was 16.0 feet and the largest decline was 17.7 feet. Eight 

wells in the southern area had rising water levels and the 

remaining five wells had declining water levels. In the northeastern area, the largest rise in water level was 1.3 feet and the 

largest decline was 21.7 feet. Four wells in the northeastern 

area had rising water levels, 35 wells had declining water levels, and the remaining well had no change in water level.

Hydrographs for 42 wells completed in the Wilcox 

aquifer were developed to show water-level altitude variation over the past 20 years. Hydrographs for the southern area 
2 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

indicate water-level changes in individual wells ranged from 

rises of 0.44 feet per year to declines of 1.68 feet per year over 

the 20-year period. County summaries of the linear regression 

analysis for the southern area indicate that Hot Spring County 

had a mean annual rise; all other counties had mean annual 

declines. Hydrographs for the northeastern area indicate waterlevel changes in individual wells ranged from rises of 0.51 

feet per year to declines of 2.16 feet per year over the 20-year 

period. County summaries of the linear regression analysis for 

the northeastern area indicate that Greene County had a mean 

annual rise; all other counties had mean annual declines.

Introduction

Eocene-age sand beds near the base of the Cockfield Formation of the Claiborne Group constitute the aquifer known 

locally as the Cockfield aquifer and are recognized nationally 

as the upper Claiborne aquifer (herein referred to as the Cockfield aquifer). Upper Paleocene-age sand beds within the lower 

parts of the Wilcox Group constitute the aquifer known locally 

as the Middle and Lower Wilcox aquifer and are recognized 

nationally as the lower Wilcox aquifer (herein referred to as 

the Wilcox aquifer). The Cockfield aquifer provides groundwater in southern Arkansas, and the Wilcox aquifer provides 

groundwater in southern and northeastern Arkansas. In 2005, 

reported withdrawals from the Cockfield aquifer in Arkansas 

totaled 16.1 million gallons per day (Mgal/d), and reported 

withdrawals from the Wilcox aquifer in Arkansas totaled 27.0 

Mgal/d (Holland, 2007). Major withdrawals from these units 

were for industrial and public water supplies with lesser but 

locally important withdrawals for commercial, domestic, and 

agricultural uses. 

A study was conducted by the U.S. Geological Survey 

(USGS) in cooperation with the Arkansas Natural Resources 

Commission and the Arkansas Geological Survey to determine 

the water levels associated with the Cockfield and Wilcox 

aquifers in southern and northeastern Arkansas. During 

February 2009, 56 water-level measurements were made in 

wells completed in the Cockfield aquifer and 57 water-level 

measurements were made in wells completed in the Wilcox 

aquifer. The 2009 water-level measurements are presented in 

potentiometric-surface maps and, in combination with previous years’ water-level measurements, in water-level difference 

maps and long-term hydrographs. 

The study areas of the Cockfield and Wilcox aquifers 

(fig. 1) are part of the Mississippi embayment which includes 

much of the West Gulf Coastal Plain and the Mississippi 

Alluvial Plain in Arkansas. The Mississippi embayment is a 

north-northeast trending syncline, which plunges to the southsouthwest, which is filled with Cretaceous to recent sediments. 

The study area of the Cockfield aquifer in southern Arkansas is 

bounded on the east by the Mississippi River and on the south 

by the Louisiana State line. The western boundary is defined 

by the counties that contain outcrops and subcrops (Hosman, 

1982) of the Cockfield Formation. The northern boundary is 

defined by counties that contain observation wells completed 

in the Cockfield aquifer. The study area boundary of the 

Wilcox aquifer in southern Arkansas is defined by the counties that contain outcrops of the Wilcox Group or observation 

wells completed in the Wilcox aquifer or both. The study area 

of the Wilcox aquifer in northeastern Arkansas is bounded 

on the north by the Missouri State line and on the east by the 

Mississippi River. The western and southern boundaries of the 

study area are defined by counties that contain outcrops in or 

near Crowleys Ridge, or observation wells that penetrate the 

Wilcox aquifer.

This report is the fifth in a triannual series of reports 

investigating the potentiometric surfaces of the Cockfield 

and Wilcox aquifers. Earlier reports with water-level measurements made in 2006, 2003, 2000, and 1996-1997 can be 

referenced through Schrader (2007), Yeatts (2004), Schrader 

and Joseph (2000), and Joseph (1998), respectively. The 

potentiometric surfaces for 1991were published in a plate map 

by Westerfield (1994). The previous report (Schrader, 2007) 

describes the potentiometric surfaces of the Cockfield and Wilcox aquifers developed from data measured during February 

and March of 2006. The 2006 report includes 56 water-level 

measurements of wells penetrating the Cockfield aquifer and 

59 water-level measurements of wells penetrating the Wilcox 

aquifer. The 2006 report also includes analysis of 10 longterm hydrographs from the Cockfield aquifer and 7 long-term 

hydrographs from the Wilcox aquifer.

Methods

The well-numbering system used in this report is based 

upon the location of the wells according to the Public Land 

Survey System used in Arkansas. The component parts of a 

well number are the township number, the range number, the 

section number, three letters which indicate, respectively, the 

quarter section, the quarter-quarter section, and the quarterquarter-quarter section in which the well is located, and a 

sequence number. The letters are assigned counterclockwise, 

beginning with “A” in the northeast quarter or quarter-quarter 

or quarter-quarter-quarter section in which the well is located. 

For example, well 01S03W04BBD16 (fig. 2) is located in 

Township 1 South, Range 3 West, and in the southeast quarter 

of the northwest quarter of the northwest quarter of section 4. 

This well is the 16th well in this quarter-quarter-quarter section of section 4 from which data were collected.

Wells locations were verified using a Wide Area Augmentation System (WAAS) Global Positioning System (GPS) 

receiver to acquire the horizontal coordinate information and 

topographic maps to acquire land-surface altitude information. 

The horizontal coordinate information (latitude and longitude) 

of the wells was recorded using a WAAS GPS accurate to 

one-tenth of a second (approximately 10 to 20 ft), based on the 

North American Datum of 1983. The latitude and longitude 
Methods 3

Figure 1. Location of study areas.

36o

35o

34o

94o 93o 92o 91o

90o

0 20 40 MILES

0 20 40 KILOMETERS

MISSOURI

MISSISSIPPI

TEXAS

OKLAHOMA

TENNESSEE

LOUISIANA

ATLANTIC

West Gulf Coastal Plain

Mississippi

Alluvial

Plain

Ouachita Mountains

Ozark Plateaus

Coastal Plain

INTERIOR

HIGHLANDS

Ouachita

province

Arkansas Valley

PLAIN

CLAY

GREENE

CRAIGHEAD MISSISSIPPI

POINSETT

CROSS

CRITTENDEN

ST. FRANCIS

LEE

ARKANSAS

GRANT JEFFERSON

DALLAS

CLEVELAND LINCOLN

DESHA

DREW

CHICOT

ASHLEY

BRADLEY

CALHOUN

UNION

OUACHITA

COLUMBIA

NEVADA

HEMPSTEAD

CLARK

HOT SPRING

Mississippi River

Physiographic division boundaries 

from Fenneman and Johnson (1946)

Base from U.S. Geological Survey

digital data, 1:100,000

Study areas

 Cockfield aquifer in southeastern Arkansas

 Wilcox aquifer in southwestern Arkansas

 Wilcox aquifer in northeastern Arkansas

EXPLANATION

Crowley Ridge

Physiographic division boundary

 Major Division

 Province

 Section
4 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

PRINCIPAL MERIDIAN

BASE LINE

TOWNSHIPS

SOUTH NORTH

WEST EAST RANGES

1E

2E

3E

4E

1W 2W 3W 4W 5W

5E

1N 2N 3N 4N

1S

2S

3S

4S 5S

6S

7S

8S

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36 RANGE: 03 West TOWNSHIP: 01 South

DD

C

B

A A

B

C

D

A

B

C

D

A

B

C

D

A

B

C

D

A

B

C D

SECTION: 04

WELL 01S03W04BBD16

N

S

E

W

determined by subtracting the measured depth to water from 

the known land surface altitude. The direction of groundwater flow is perpendicular to the contours in the direction of 

decreasing water level.

Water-level difference maps for the Cockfield and Wilcox 

aquifers in Arkansas were constructed using the differences 

between depth to water measurements made during 2003 

(Yeatts, 2004) to 2009. The difference in water level was calculated by subtracting the 2009 depth-to-water value from the 

2003 depth-to-water value for each individual well. Positive 

difference values indicate a rise and negative difference values 

indicate a decline in water level.

Annual rises or declines in water levels were determined 

by performing linear regressions on the well hydrographs. The 

slope, m from the regression line equation (y = mx + b) represents the daily rise or decline in water level. The annual rise 

or decline in water level is obtained by multiplying the slope, 

(daily rise or decline) by 365.25 days. The R2 term is the coefficient of determination or the fraction of variance explained 

by the regression (Helsel and Hirsch, 1992). 

Cockfield Aquifer

Hydrogeologic Setting

The Cockfield aquifer, in southern Arkansas, is part of 

the Cockfield Formation of the Claiborne Group (hereafter 

referred to as Cockfield Formation) of Eocene age and generally consists of discontinuous fine- to medium-grained sand 

units interbedded with silt, clay, and lignite, all of nonmarine 

origin. Most of the sand beds that constitute the Cockfield 

aquifer media are found near the base of the Cockfield Formation and are known nationally as the upper Claiborne aquifer. 

The Cockfield Formation and aquifer are part of a north-northeast trending syncline, which plunges to the south-southwest, 

approximately centered beneath the Mississippi River (fig. 3). 

The Cockfield Formation generally ranges from 100 to 400 

ft thick near outcrop areas and thickens downdip towards the 

center of the syncline, reaching 625 ft thick in northeastern 

Chicot County (Onellion and Criner, 1955). Thicknesses of 

the sand beds near the base of the Cockfield Formation that 

compose the Cockfield aquifer generally range from 20 to 150 

ft. The Cockfield Formation is underlain throughout the study 

area by calcareous and sandy marl, limestone, and carbonaceous clay of the Cook Mountain Formation of Claiborne 

Group (table 1). The Cockfield Formation is overlain by silty 

clays of the Jackson Group throughout much of southeastern 

Arkansas. In the confined part of the aquifer, the potentiometric surface can be near or above land surface. Sand beds at the 

base of the overlying Jackson Group in parts of southeastern 

Arkansas may be in hydraulic connection with the Cockfield 

aquifer (Ackerman, 1987).

Figure 2. Well-numbering system.

of the well location was then transferred to a topographic map 

and the altitude of the land surface at the well was determined by interpolation of the topographic contours at the 

well location. The well measuring point altitude is accurate to 

about one-half of the contour interval (5, 10, or 20 ft) of the 

topographic maps, which are based on the National Geodetic 

Vertical Datum of 1929.

Water levels were measured by USGS personnel at public 

water supply, industrial, commercial, domestic, and observation wells completed in the Cockfield or Wilcox aquifers. 

Measurements were made using steel or electric field tapes 

graduated to hundredths of a foot. The steel and electric tapes 

used by USGS personnel were calibrated during January 2009 

prior to collecting measurements from wells. Calibration of 

steel and electric tapes was performed by comparing the field 

steel or electric tape to a standardized steel tape used only for 

calibration of field tapes.

Potentiometric-surface maps for the Cockfield and 

Wilcox aquifers in Arkansas were constructed by plotting well 

positions with their respective water-level altitude and manually constructing contour lines along points of equal waterlevel altitude. The altitude of the water level in each well was 
Methods 5

MISSISSIPPI RIVER VALLEY

ALLUVIAL AQUIFER OUTCROP

AREA

OUTCROP

AREA

LOESS, SILT, SAND,GRAVEL DEPOSITS

VICKSBURG -JACKSON CONFINING UNIT

UPPER CLAIBORNE AQUIFER

(Cockfield aquifer)

MIDDLE CLAIBORNE AQUIFER

LOWER WILCOX AQUIFER

LOWER

AQUIFER

LOWER

CLAIBORNE CONFINING

UNIT

MIDDLE CLAIBORNE CONFINING UNIT

CLAIBORNE

MIDWAY

CONFINING UNIT MIDWAY

CONFINING UNIT

WEST EAST

NOT TO SCALE Geology modified from Arthur and Taylor (1990)

Groundwater flow direction

EXPLANATION

Figure 3. Generalized section of the hydrogeologic and geologic units within the Mississippi embayment (modified from Hart and 

others, 2008).

The Cockfield Formation and aquifer outcrop in a band 

trending north-northeast across the study area and dip southeastward. In the subcrop area, the Cockfield Formation is 

overlain by terrace deposits and alluvium of Quaternary age. 

The terrace deposits may attain a thickness of 40 ft, and as 

much as 60 ft of alluvium overlies the Cockfield Formation in 

some of the larger river valleys. 

Most recharge to the Cockfield aquifer occurs by infiltration of rainfall on the upland outcrop areas and by inflow from 

the overlying alluvium or rivers that have eroded through the 

overburden and are hydrologically connected with the aquifer. 

Most discharge is to rivers in outcrop areas, to vertically 

adjacent units where the Cockfield aquifer is confined, and to 

wells (Ackerman, 1987). Well depths are shallow (less than 

200 ft) and yields of most wells in the outcrop areas are small, 

less than 30 gallons per minute (gal/min), but in other areas 

downdip from the outcrop areas, wells screening the full thickness of the aquifer often yield 100 to 500 gal/min (Westerfield, 

1994).

Hydraulic Properties

Specific capacity and transmissivity values are variable 

for the Cockfield aquifer. The following values are based on 

single-well pump tests and multiple-well aquifer tests (Pugh, 

2008). Specific capacity values ranged from 0.15 gallon per 

minute per foot (gal/min/ft) to 23.7 gal/min/ft with a median 

of 0.76 gal/min/ft. Transmissivity values ranged from 325 

square feet per day (ft2/d) to 6,280 ft2/d with a median of 3,350 

ft2/d. Hydraulic conductivity values were not provided by any 

of the well tests associated with the Cockfield aquifer. Pugh 

(2008) estimated a hydraulic conductivity value for the Cockfield aquifer by dividing the mean transmissivity value (3,330 

ft2/d) by the maximum aquifer thickness (400 ft), providing an 

estimated hydraulic conductivity value of 8.33 ft/d.

Water Use

Withdrawals from the Cockfield aquifer in the study area 

during 2005 totaled about 16.1 Mgal/d (Holland, 2007) (fig. 

4). Withdrawals from the Cockfield aquifer have continued 

to rise from 1985 to 2005, producing 5.0 Mgal/d in 1985, 8.1 

Mgal/d in 1990, 9.8 Mgal/d in 1995, 9.9 Mgal/d in 2000, and 

16.1 Mgal/d in 2005 (Holland 1987, 1993, 1999, 2004, 2007). 

Withdrawals from the Cockfield aquifer were 5.2 Mgal/d in 

1975 and 7.2 Mgal/d in 1980 (Halberg, 1977; Holland and 

Ludwig, 1981). The increase in withdrawals between 2000 

(9.9 Mgal/d) and 2005 (16.1 Mgal/d) are associated with 

increased use of waters from the Cockfield aquifer by public 

supply systems in eastern Arkansas (T.W. Holland, U.S. Geological Survey written commun., 2009). Most wells completed 

in the Cockfield aquifer study area provide small volumes 

of water for domestic and livestock use. In some locations, 

the Cockfield aquifer yields volumes large enough to supply 

industrial and public supply systems.

Adjacent to Arkansas, in 2005 about 46 Mgal/d were 

withdrawn from the Cockfield aquifer in Mississippi (D.E. 

Burt, U.S. Geological Survey, written commun., 2009). Withdrawals from the Cockfield aquifer in Mississippi increased 

170 percent between 1999 and 2005. Immediately across the 

Mississippi River from Chicot County, Arkansas, the city of 

Greenville, Mississippi, withdrew about 22 Mgal/d from the 
6 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Table 1. Hydrogeologic and geologic units within the Mississippi embayment of Arkansas (modified from Hart and 

others, 2008). ERATHEM SYSTEM

SERIES

GROUP

GEOLOGIC UNIT

HYDROGEOLOGIC UNIT

Southern 

Arkansas

Northeastern 

Arkansas

CENOZOIC

QUATERNARY

HOLOCENE

Alluvium and terrace deposits Mississippi River Valley alluvial aquifer

PLEISTOCENE

TERTIARY

OLIGOCENE

Vicksburg

Not present in study areas

Vicksburg-Jackson confining unit

EOCENE

Jackson

Jackson Formation

Claiborne

Cockfield Formation Upper Claiborne aquifer (Cockfield aquifer)

Cook Mountain Formation Middle Claiborne confining unit

Sparta Sand

Memphis Sand Middle Claiborne aquifer

Cane River 

Formation

Lower 

Claiborne 

confining 

unit

Carrizo Sand

Lower 

Claiborne 

aquifer

UPPER PALEOCENE

Wilcox

Undifferentiated

Flour Island 

Formation Middle Wilcox aquifer

Fort Pillow Sand

Lower Wilcox aquifer Old 

Breastworks 

Formation

Midway Group Midway confining unit

Modified from Hosman and Weiss, 1991
Methods 7

Cockfield aquifer in 2005 (D.E. Burt, U.S. Geological Survey, 

written commun., 2009), or about 37 percent more than was 

withdrawn from the Cockfield aquifer in all of Arkansas in 

2005. The large amount of withdrawal from the Cockfield 

aquifer in Mississippi probably contributes to lower water levels in southeastern Arkansas (Ackerman, 1987; Joseph, 1998; 

Schrader and Joseph, 2000). 

YEAR

1975 1980 1985 1990 1995 2000 2005

W

ATER USE, IN

MILLION GALLONS PER DAY 18.0

16.0

14.0

12.0

10.0

8.0

6.0

4.0

2.0

0.0

16.1

9.8 9.9

8.1

5.0

7.2

5.2

Data compiled from Halberg, 1977;

Holland and Ludwig, 1981; and

Holland,1987, 1993, 1999, 2004, 2007

Figure 4. Water use from the Cockfield aquifer in Arkansas, 

1975-2005.

Potentiometric Surface

The potentiometric-surface map shows the altitude of the 

water surface in tightly cased wells screened in the Cockfield 

aquifer (fig. 5). The map is based upon water-level data collected during February 2009 from 56 wells completed in the 

Cockfield aquifer in southern Arkansas (appendix 1). 

The regional direction of groundwater flow generally 

is towards the east and southeast, except in areas of intense 

groundwater withdrawals, such as western Drew County, 

southeastern Lincoln County and near Crossett in Ashley 

County (Schrader and Joseph, 2000). There are two cones of 

depression indicated by relatively low water levels in southwestern Calhoun County and near Crossett in Ashley County. 

The cone of depression in southwestern Calhoun County is 

associated with a depression in the top surface of the Cockfield 

formation (Hart and others, 2008). The cone of depression 

near Crossett in Ashley County is associated with groundwater withdrawals. There are also two groundwater mounds 

indicated by relatively high water levels in central Cleveland 

County and bordering Ashley and Drew Counties. The lowest 

water-level altitude measured was 43 ft above NGVD of 1929 

in Lincoln County; the highest water-level altitude measured 

was 351 ft above NGVD of 1929 in Columbia County. 

Water-Level Trends

Water-Level Difference from 2003 to 2009

A water-level difference map (fig. 6) was constructed to 

spatially evaluate the short-term (6 years) change in water levels of the Cockfield aquifer within Arkansas. The water-level 

difference map was constructed using the difference between 

water-level measurements made in 2003 (Yeatts, 2004) and 

2009 for 54 wells completed in the Cockfield aquifer within 

Arkansas. Positive values, represented with blue, upward 

pointing triangles, indicate a rise in water level between 2003 

and 2009; whereas negative values, represented with red, 

downward pointing triangles, indicate a decline in water level 

between 2003 to 2009. The triangles are scaled in size to the 

relative value of rise or decline. The 2003 to 2009 waterlevel difference map does not necessarily equate to long-term 

trends, but is intended to show how water levels in the Cockfield aquifer have changed over the short term.

The 2003 to 2009 difference in water levels for the 

Cockfield aquifer within Arkansas ranged from -27.4 to 14.9 

ft (fig. 6). The largest rise (14.9 ft) in water level was in Drew 

County. The largest decline (27.4 ft) was in Lincoln County. 

Of the 54 well data points presented, 7 wells had a rise in 

water level, the remaining 47 wells had a decline in water 

level from 2003 to 2009. Most of the declines in water levels 

between 2006 and 2009 were 4 ft or less. Rises in water levels 

occurred in Bradley, Calhoun, Chicot, Cleveland, Drew, and 

Union Counties. Declines in water levels occurred in Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland, Columbia, 

Desha, Lincoln, and Union.

One area, northern Cleveland County, had a slight rise in 

water levels in the Cockfield aquifer from 2003 to 2009 (fig. 

6). Parts of northern Cleveland County are within an outcrop 

area of the Cockfield Formation and the area is on the northwestern flank of a groundwater mound (fig. 5). The outcrop 

areas provide recharge to the Cockfield aquifer and the 

groundwater mound separates the area from the falling water 

levels to the south.

The remaining areas of the Cockfield aquifer study have 

general decline in water levels from 2003 to 2009 (fig. 6). 

Large declines in water levels have occurred along the eastern 

and southern Arkansas borders. In Arkansas, Desha, and 

Chicot Counties, on or near the eastern border, water levels 

generally have declined 2 to 4 ft. In Columbia County, along 

the southern border, water levels generally have declined 3.5 

to 6 ft. Water levels in the remaining parts of the Cockfield 

aquifer study area generally have declined 1 to 3 ft.

Long-Term Hydrographs

Two methods are used to evaluate long-term water-level 

trends for the Cockfield aquifer in Arkansas. The first method 

was to develop hydrographs for each well with 20 or more 
8 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

UNION

DREW

ASHLEY

CHICOT

DESHA

ARKANSAS

GRANT

DALLAS

JEFFERSON

COLUMBIA

OUACHITA

BRADLEY

LINCOLN

CALHOUN

CLEVELAND

Ouachita

River

Saline

River

Moro

Creek

Greenville,

Mississippi

Crossett 320

280

280

300

300

240

220

200

120

160

240

240

220

140

140

120

100

160

100

80

80

220

260

180

200

160

140

120

100

80

80

60 180

200

280

260

60

180

180

!

!

!! !

!

!

!

!

!

!

!! !

!

! !

!

! !

!

!! !

!

!

!

!

!! !

!

!

!

!

!

!

! !

!

!

!

!

!

! !

!

!

!

!

!

! !

!

!

!

43

95

70

98

82

80

65

83

88

81

79

77

62

67

92 96

86

85 70

68

88

99 91

87

86

72

189

174

262 230 201

155 158

234

159

104

307

260 251 289

351

234

267

164

126

134

177

211

194

257

111 107

131

109

113

102

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

ARKANSAS

Study area

Outcrop of Cockfield Formation (modified from Hosman, 1988)

Potentiometric contour—Shows altitude at which water

 level would have stood in tightly cased wells. Hachures

 indicate depression. Dashed where approximately located. 

 Contour interval 20 feet. Datum is National Geodetic Vertical 

 Datum of 1929

General direction of groundwater flow

Well completed in Cockfield aquifer—Number is

 water-level altitude. Letter, where present, corresponds

 to hydrograph in figure 7

EXPLANATION

180

! C 68

0 10 20 30 40 MILES

0 10 20 30 40 KILOMETERS

34°00'

33°30'

91°30'

92°30'

92°00'

93°00'

91°00'

Figure 5. Potentiometric surface of the Cockfield aquifer in southern Arkansas, 2009.
Methods 9

UNION

DREW

ASHLEY

CHICOT

DESHA

ARKANSAS

GRANT

DALLAS

JEFFERSON

COLUMBIA

OUACHITA

BRADLEY

LINCOLN

CALHOUN

CLEVELAND

Ouachita

River

Saline

River

Moro

Creek

Greenville,

Mississippi

Crossett

ARKANSAS

Study area

-2.1

C

*

0.2

H *

Outcrop of Cockfield Formation (modified from Hosman, 1988)

Well completed in Cockfield aquifer—Value is rise in water

 level from 2003 to 2009, in feet. Symbols are scaled to value. 

 Letter, where present, corresponds to hydrograph in figure 7 

Well completed in Cockfield aquifer—Value is decline in water

 level from 2003 to 2009, in feet. Symbols are scaled to value. 

 Letter, where present, corresponds to hydrograph in figure 7

EXPLANATION

0 10 20 30 40 MILES

0 10 20 30 40 KILOMETERS

34°00'

33°30'

91°30'

92°30'

92°00'

93°00'

91°00'

*

*

* *

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

* *

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

A

B

C

D E

F

G

H

I

J

K

L

M

N

O

P Q

R

-2.0

-1.0 -4.0

-1.0 -1.0

-2.0

-2.0

-2.0

-0.8

-1.4

-0.7 -0.3 -2.3

-2.9

-2.9 -2.6

-3.3

-2.6 -3.5

-4.5 -3.6

-3.6

-5.9

-2.8

-1.1

-2.5

-1.3

-7.1

-2.3

-0.3

-1.5

-3.1

-3.6

-1.4

-0.8

-1.9

-3.1

-0.7

-2.6

-2.8

-2.1

-1.7 -0.8

-1.5

-0.3

-3.4

-27.4

0.4

0.2

1.3

0.2

0.1

8.6

14.9

Figure 6. Water-level difference from 2003 to 2009 of the Cockfield aquifer in southern Arkansas.
10 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

years of records by plotting the water-level values in relation 

to time (fig. 7). The second method was to calculate the annual 

rise or decline in water levels over the past 20 years (1990-

2009), aggregate the data by county, and statistically evaluate 

the range, mean, and median of water-level change in each 

county (table 2). 

Hydrographs for 33 wells with 20 or more years of 

historical water-level data were developed and examined. 

Selected hydrographs for 18 wells are presented in figure 7 

(wells A-R). The locations of these wells are plotted on figures 

5 and 6 and are designated by the letters A through R next to 

the well location. 

Examination of the hydrographs is divided into three 

geographic areas: the area south and west of the Ouachita 

River, the area between the Ouachita and Saline Rivers, and 

the area east of the Saline River. The area south and west of 

the Ouachita River, including Columbia (fig.7-L) and Union 

(fig. 7-P, -Q, and -R) Counties, contains an outcrop area with 

overlying Quaternary-age terrace deposits along the western 

edge. All of these hydrographs are relatively flat indicating 

only a small, 1- to 3-ft drop in water levels over the past 30 

to 40 years. The hydrograph for well 17S13W17DDC1 (fig. 

7-P) in Union County has a water-level rise of approximately 

3 ft over the more than 40-year period of record. The area 

between the Ouachita and Saline Rivers, including Bradley 

(fig. 7-D and -E), Calhoun (fig. 7-F and -G), and Cleveland 

(fig. 7-J and -K) Counties, is a mixed area with the northern 

part being in an outcrop area, the eastern part being confined 

by the Eocene-age Jackson Group (confining unit), and the 

southern part underlying Quaternary-age terrace deposits. 

These hydrographs display both rises and declines ranging 

from a decline of approximately 20 ft (well 14S10W31DBA1, 

fig. 7-D) over the period of record to rises of approximately 2 

ft (well 15S12W11CAB1, fig. 7-E and well 11S11W23BBD1, 

fig. 7-K) over the period of record. The area east of the Saline 

River, including Arkansas (fig. 7-A), Ashley (fig. 7-B and -C), 

Chicot (fig. 7-H and -I), Desha (fig. 7-M), Drew (fig. 7-N), 

and Lincoln (fig. 7-O) Counties, is within a confined part of 

the aquifer. These hydrographs all show declining water levels 

over their period of record ranging from approximately 60 ft 

(Well 10S05W06CAC1, fig. 7-O) to approximately 5 ft (well 

18S03W14CCC1, fig. 7-I).

Hydrographs for 33 wells with historical water-level data 

from 1990 to 2009 were evaluated using linear regression to 

calculate the annual rise or decline for each well and the data 

aggregated by county and statistically evaluated for the range, 

mean, and median of water-level change in each county (table 

2). Arkansas, Columbia, Desha, Drew, and Lincoln Counties 

only had one well with a minimum of 20 years of record. Of 

the counties with more than one well with over 20 years of 

record, annual rise-decline calculations associated with wells 

in Ashley and Chicot Counties indicated declining water 

levels. Annual rise-decline calculations associated for wells 

with over 20 years of record in the remaining counties, Bradley, Calhoun, Cleveland, and Union, indicate both rising and 

declining water levels. Cleveland and Columbia Counties have 

mean annual water-level rises of 0.11 and 0.03 ft/yr, respectively. Arkansas, Ashley, Bradley, Calhoun, Chicot, Desha, 

Drew, Lincoln, and Union Counties have mean annual well 

water-level declines ranging from 0.02 to 1.46 ft/yr (table 2). 

Table 2. Range, mean, and median of annual rise/decline in water level by county for wells completed in the Cockfield aquiifer in Arkansas, 

1990-2009.

[Annual rise or decline in water level for each well is calculated using linear regression; negative value indicates decline; positive value indicates rise; R2: coefficient of determination]

County Number of wells

Range or values of 

annual rise (+) or 

decline (-) in water 

level (feet/year)

Mean annual rise (+) 

or decline (-) in water level (feet/year)

Median annual rise 

(+) or decline (-) in 

water level (feet/

year)

Range of R2 values 

for trend lines

Arkansas1 1 -0.11 -0.11 -0.11 0.08

Ashley 6 -0.69 to -0.07 -0.44 -0.49 0.02 to 0.94

Bradley 4 -0.44 to 0.26 -0.17 -0.26 0.21 to 0.91

Calhoun 3 -022 to 0.11 -0.02 0.04 0.02 to 0.65

Chicot 5 -0.77 to -0.22 -1.46 -0.33 0.46 to 0.91

Cleveland 2 -0.11 to 0.33 0.11 0.11 0.29 to 0.71

Columbia1 1 0.03 0.03 0.03 0.01

Desha1 1 -1.21 -1.21 -1.21 0.87

Drew1 1 -0.51 -0.51 -0.51 0.97

Lincoln1 1 -0.73 -0.73 -0.73 0.28

Union 8 -0.55 to 0.23 -0.11 -0.13 0.03 to 0.77

1

 County included only one well with 20 or more years of measurements.
Methods 11

90

100

110

120

130

120

110

100

90

80

70

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

B. ASHLEY COUNTY, WELL 17S06W07ADA1

A. ARKANSAS COUNTY, WELL 08S02W04ACA1

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.
12 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued

90

100

110

120

60

70

80

90

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

D. BRADLEY COUNTY, WELL 14S10W31DBA1

C. ASHLEY COUNTY, WELL 18S08W04BBC1
Methods 13

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

270

260

250

240

120

130

140

150

No data No data

F. CALHOUN COUNTY, WELL 11S13W15BBC1

E. BRADLEY COUNTY, WELL 15S12W11CAB1
14 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

100

90

80

70

60

120

110

100

90

H. CHICOT COUNTY, WELL 14S03W05BBA1

G. CALHOUN COUNTY, WELL 14S14W21ACB1
Methods 15

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

180

170

160

150

100

90

80

70

No data

J. CLEVELAND COUNTY, WELL 08S13W34BDA1

I. CHICOT COUNTY, WELL 18S03W14CCC1

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued
16 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

280

270

260

250

250

240

230

220

L. COLUMBIA COUNTY, WELL 19S21W17CBB1

K. CLEVELAND COUNTY, WELL 11S11W23BBD1

No data

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued
Methods 17

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

140

130

120

110

100

100

90

80

70

60

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

N. DREW COUNTY, WELL 14S07W26BAB1

M. DESHA COUNTY, WELL 12S01W32DCA1

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued
18 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

170

160

150

140

110

100

90

80

70

60

50

40

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

P. UNION COUNTY, WELL 17S13W17DDC1

O. LINCOLN COUNTY, WELL 10S05W06CAC1

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued
Methods 19

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

200

190

180

170

280

270

260

250

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

No data

No data

R. UNION COUNTY, WELL 19S12W28CBA1

Q. UNION COUNTY, WELL 17S18W15CDA1
20 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Wilcox Aquifer

Hydrogeologic Setting

The Wilcox aquifer is composed of the Wilcox Group of 

Upper Paleocene age and is distributed throughout the Mississippi Embayment including most of southern and eastern 

Arkansas. The group is part of a north-northeast trending 

syncline, which plunges to the south-southeast, approximately 

centered beneath the Mississippi River (fig. 3). The Wilcox 

aquifer in central Arkansas is not extensively used, and waterlevel data are insufficient to determine the potentiometric 

surface. Because water-level altitude data are discontinuous, 

the potentiometric surface of the Wilcox aquifer is constructed 

in two parts; one in southern Arkansas and the other in northeastern Arkansas. The Wilcox Group in southern Arkansas is 

undifferentiated, while in northeastern Arkansas, the Wilcox 

Group is divided into three units: Flour Island Formation, Fort 

Pillow Sand, and Old Breastworks Formation (table 1). 

The Wilcox Group in the southern area consists of interbedded layers of clay, sandy clay, sand, and lignite. Sand beds 

generally are thin and are not continuous over large areas. In 

most of the southern area, the Wilcox Group overlies the Midway Group and is overlain by terrace deposits and alluvium 

of Quaternary age or crops out. The Wilcox Group becomes 

progressively thicker downslope from the outcrop, ranging 

in thickness from a few feet in the outcrop to about 750 ft at 

the center of the syncline (Albin, 1964). The Wilcox aquifer 

comprises water-yielding strata within the basal sand beds of 

the Wilcox Group in southern Arkansas.

The Wilcox Group in most of the northeastern area consists of thin interbedded layers of lignitic sand and clays. The 

Wilcox Group crops out at or near Crowleys Ridge in Clay, 

Greene, and Craighead Counties (Broom and Lyford, 1981). 

East of Crowleys Ridge, the Wilcox Group, including the Fort 

Pillow Sand and the Old Breastworks Formation, contains a 

sand bed of 200 ft or more in thickness (Petersen and others, 

1985), which is referred to as the “1,400-foot sand” (Ryling, 

1960; Plebuch, 1961) or the “lower Wilcox aquifer” (Hosman and others, 1968). The Wilcox aquifer in the northeastern 

area is confined above by a clay bed of the Wilcox Group and 

underlain by a clay bed of the Wilcox Group or by the Midway 

Group.

Within Crowleys Ridge, part of the Wilcox aquifer is 

perched and hydrologically separated from the aquifer in the 

surrounding Mississippi Alluvial Plain. Four water-level measurements were made from wells completed in this perched 

portion of the Wilcox aquifer, two in Green County and two in 

Clay County.

Recharge to the aquifer occurs in locations where the 

Wilcox Group crop outs or subcrops. The Wilcox Group crops 

out in southern Arkansas in discontinuous, 1- to 3-mile (mi) 

wide bands along the western edge of the aquifer. In subcrop 

areas, the Wilcox Group is overlain by terrace deposits and 

alluvium of Quaternary age. Terrace deposits may attain thicknesses of 40 ft, and as much as 60 ft of alluvium overlie the 

Wilcox Group in some of the major river valleys. In northeastern Arkansas, the Wilcox Group crops out along a narrow, 

discontinuous band along the western edge of Crowleys Ridge 

(not shown at map scales used in this report). 

Recharge to the Wilcox aquifer in the southern area 

occurs by infiltration of rainfall in the outcrop areas and by 

inflow from overlying terrace and alluvial deposits. Discharge 

flows into streams in the outcrop area, to overlying formations where the aquifer is confined, and to wells (Westerfield, 

1994). Well depths range from 14 ft within the recharge area in 

Hempstead County to 533 ft in Ouachita County. Well yields 

range from 10 to 100 gal/min (Schrader and Joseph, 2000).

Recharge to the Wilcox aquifer in the northeastern area 

occurs by infiltration of rainfall in the outcrop areas along 

the western side of Crowleys Ridge. Discharge occurs from 

well withdrawals (Westerfield, 1994). Well depths range 

from 120 ft on Crowleys Ridge in Greene County to 1,885 ft 

in Lee County. Well yields range from 100 to 2,000 gal/min 

(Schrader and Joseph, 2000).

Hydraulic Properties

Specific capacity and transmissivity values are extremely 

variable for the Wilcox aquifer. The following values are 

based on single-well pump tests and multiple-well aquifer 

tests (Pugh, 2008). Specific capacity values ranged from 0.25 

gal/min/ft to 641 gal/min/ft with a median of 21.1 gal/min/ft. 

Transmissivity values ranged from 30 ft2/d to 32,000 ft2/d with 

a median of 8,170 ft2/d. Hydraulic conductivity values were 

not provided by any of the well tests associated with the Wilcox aquifer. Pugh (2008) estimated a hydraulic conductivity 

value for the Wilcox aquifer by dividing the mean transmissivity value (10,700 ft2

/d) by the maximum aquifer thickness 

(1,100 ft), providing an estimated hydraulic conductivity value 

of 9.7 ft/d.

Water Use

Reported withdrawals from the Wilcox aquifer in Arkansas totaled 27.0 Mgal/d during 2005 (fig. 8), most of which 

occurred in the northeastern area (Holland, 2007). Withdrawals from 1975 through 2005 have remained relatively constant, 

between 21.0 Mgal/d and 27.0 Mgal/d, except in 1990 (30.9 

Mgal/d) and 1995 (41.0 Mgal/day). During the reporting 

years of 1990 and 1995, the increase in reported water use is 

attributed to withdrawals by a power generation plant that was 

operating during this time period (T.W. Holland, U.S. Geological Survey written commun., 2009). In the southern area, 

the primary use of water from the aquifer was for domestic 

supplies, usually from wells in or near the outcrop areas. In the 

northeastern area, the primary use of water from the aquifer was for public supplies, but the aquifer is also important 

locally as a source of water for commercial, domestic, and 

industrial users.
Wilcox Aquifer 21

Figure 8. Water use from the Wilcox aquifer in Arkansas, 1975-

2005.

Potentiometric Surface

The potentiometric-surface maps show the altitude of the 

water surface in tightly cased wells screened in the Wilcox 

aquifer (figs. 9 and 10). The maps are based upon water-level 

data collected from 57 wells during February 2009, 16 of the 

wells were in the southern area and the remaining 41 wells 

were in the northeastern area. The direction of groundwater flow is perpendicular to the contours in the direction of 

decreasing water level.

The direction of groundwater flow in the southern area 

(fig. 9) is generally to the east, except around two cones of 

depression, one in Nevada County and the other in Clark 

County, and around two mounds of elevated water levels, one 

in Hot Spring County and the other in Hempstead County. 

Water flows into the cone of depression in Nevada County 

from all directions. The direction of water flow toward the 

cone of depression in Clark County is generally from the 

north, west, and south. The direction of water flow from the 

northern mound in Hot Spring County is generally to the 

south and east with some to the north. The direction of water 

flow from the southwestern mound in Hempstead County is 

generally to the south and east. The lowest water-level altitude 

measured in the southern area was 147 ft at the center of the 

cone of depression near the Ouachita River in Clark County. 

The highest water-level altitude measured was 400 ft at the 

center of the potentiometric-surface mound in an outcrop area 

of Hempstead County (appendix 3).

The direction of groundwater flow in the northeastern 

area (fig. 10) is generally to the south and southeast except 

in the northern part of the area (Clay, Greene, and Craighead 

Counties) where the flow is in a westerly direction towards 

Paragould. Groundwater withdrawals have altered the natural 

direction of flow near centers of pumping at Paragould and 

West Memphis (Joseph, 1998). The lowest water-level altitude 

measured in the northeastern area was 114 ft near West Memphis in Crittenden County; the highest water-level altitude 

measured was 368 ft on Crowleys Ridge in Clay County. 

Crowleys Ridge is an erosional remnant of Cretaceous 

and Tertiary rocks covered with loess deposits. Crowleys 

Ridge varies from 0.5 to 12 mi wide, rises 250 to 550 ft above 

the surrounding Mississippi Alluvial Plain, and extends approximately 150 mi southwest and south from southeastern 

Missouri to east-central Arkansas. Water levels measured in 

wells on Crowleys Ridge are higher than measurements collected in the surrounding Mississippi Alluvial Plain because of 

the higher altitude of the Wilcox aquifer underlying Crowleys 

Ridge and the influence of direct recharge from outcrops and 

subcrops on the ridge. Water-level measurements collected 

on Crowleys Ridge (four wells) were not considered in the 

construction of the potentiometric surface. The waters of the 

remnant Wilcox Group deposits, locally considered the Upper 

Wilcox aquifer, within Crowleys Ridge tend to be perched 

at higher altitudes than the surrounding Mississippi Alluvial 

Plain, and control points were too few for contouring.

Water-Level Trends

Water-Level Difference from 2003 to 2009

Water-level difference maps for the Wilcox aquifer in 

Arkansas (figs. 11 and 12) were constructed using 53 waterlevel measurements made during 2003 (Yeatts, 2004) and 

2009. Positive values indicate a rise and negative values 

indicate a decline in water level. In figures 11 and 12, rises 

in the water level are indicated using upward pointing, blue 

triangles; while declines in the water level are indicated using 

downward pointing, red triangles. The triangles are scaled to 

the relative value of the rise or decline in water level. Waterlevel differences do not necessarily equate to water-level 

trends, but are intended to show where water levels have 

increased or decreased between 2003 and 2009.

The difference in water levels from 2003 to 2009 in the 

southern area (fig. 11) ranged from -17.7 to 16.0 ft with the 

largest decline (17.7 ft) in water level in Nevada County, and 

the largest rise (16.0 ft) in water level in Hempstead County. 

Water levels rose in the northern and eastern parts of the 

southern area (eight wells in Hempstead, Hot Spring, Clark, 

and Ouachita Counties), and the water levels in the southern 

part of the area declined (five wells in Hempstead and Nevada 

Counties) (appendix 5).

The differences in water levels from 2003 to 2009 in the 

northeastern area (fig. 12) ranged from -21.7 to 1.3 ft, with the 

largest decline (21.7 ft) in water level in Greene County, and 

the largest rise (1.3 ft) in water level in Crittenden County. 

Four well in the northeastern area had rising water levels, 35 

YEAR

1975 1980 1985 1990 1995 2000 2005

WATER USE, IN MILLION GALLONS PER DAY 

50.0

45.0

40.0

35.0

30.0

25.0

20.0

15.0

10.0

5.0

0.0

Data compiled from Halberg, 1977;

Holland and Ludwig, 1981; and

Holland, 1987, 1993, 1999, 2004, 2007

27.0

22.2

41.0

30.9

21.0

25.7 24.3
22 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

34°30'

93°30'

34°00'

92°30'

33°30'

93°00'

340

360

300

320

380

160

180

200

220

240

260

280

300

320

340

360

380

240

260

220

280

160

180

200

CLARK

DALLAS

NEVADA

OUACHITA

HEMPSTEAD

HOT SPRING

River

Little

Ouachita

Missouri

River

ARKANSAS

Study area

275

311

243

256

312

393 342

333

344

400 346

265

147

212

231

257

A

B

C

D

E !

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

Outcrop of Wilcox Group (from Hosman, 1988)

Potentiometric contour—Shows altitude at which water level would have

 stood in tightly cased wells. Hachures indicate depression. Dashed where

 approximately located. Contour interval 20 feet. Datum is National

 Geodetic Vertical Datum of 1929

General direction of groundwater flow

Well completed in Wilcox aquifer, southern Arkansas—Number is

 water-level altitude. Letter, where present, corresponds to hydrograph

 in figure 13

180

EXPLANATION

A !

231

0 10 20 MILES

0 10 20 KILOMETERS

Figure 9. Potentiometric surface of the Wilcox aquifer in southern Arkansas, 2009.
Wilcox Aquifer 23

Figure 10. Potentiometric surface of the Wilcox aquifer in northeastern Arkansas, 2009.

Paragould

West

Memphis

CLAY

CROSS

POINSETT

GREENE

CRAIGHEAD

ST. FRANCIS

LEE

CRITTENDEN

MISSISSIPPI

ARKANSAS

Study

area

Crowleys Ridge (from Hosman, 1988)

Potentiometric contour—Shows altitude at which water

 level would have stood in tightly cased wells. Dashed

 where approximately located. Contour interval 10 feet. 

 Datum is National Geodetic Vertical Datum of 1929

General direction of groundwater flow

Well completed in Wilcox aquifer, northeastern

 Arkansas—Number is water-level altitude. Letter, 

 where present, corresponds to hydrograph in figure 14

EXPLANATION

180

!

199

F

0 10 20 MILES

0 10 20 KILOMETERS

35°00’

36°00’

90°00’

91°00’

90° 30’

35° 30’

36° 30’

210

210

200

190

180

160

150

140

170

190

180

120

130

200

180

180

190

170

140

130

160

170

220

130

139

174

174

184 175

171

165

181 207

199

201

187

186

184

187

184

179

171

140

136

296

180

352

168

168

160

153 154

114

133

131

133

203

195

195 187

193

296

368

190

E

C

F

A

B

D

G

H
24 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Figure 11. Water-level difference from 2003 to 2009 for the Wilcox aquifer in southern Arkansas.

34°30'

93°30'

34°00'

92°30'

33°30'

93°00'

CLARK

DALLAS

NEVADA

OUACHITA

HEMPSTEAD

HOT SPRING

River

Little

Ouachita

Missouri

River

ARKANSAS

Study area

0 10 20 MILES

0 10 20 KILOMETERS

-4.2

-3.9

-2.0 -0.6

-17.7

0.1

0.4

0.5

0.6

1.2

1.7

2.3

16.0

A

D

*

*

*

* *

*

*

*

*

*

*

*

*

Outcrop of Wilcox Group (from Hosman, 1988)

Well completed in Wilcox aquifer, southern Arkansas—Value is rise in water

 level from 2003 to 2009, in feet. Symbols are scaled to value. Letter where 

 present, corresponds to hydrograph in figure 13

Well completed in Wilcox aquifer, southern Arkansas—Value is decline in water

 level from 2003 to 2009, in feet. Symbols are scaled to value

EXPLANATION

0.6

*A

-2.0*
Wilcox Aquifer 25

Figure 12. Water-level difference from 2003 to 2009 for the Wilcox aquifer in northeastern Arkansas.

Paragould

West

Memphis

CLAY

CROSS

POINSETT

GREENE

CRAIGHEAD

ST. FRANCIS

LEE

CRITTENDEN

MISSISSIPPI

35°00’

36°00’

90°00’

91°00’

90° 30’

35° 30’

36° 30’

*

0.5

A

-3.4*

F

0.0

Crowleys Ridge (from Hosman, 1988)

Well completed in Wilcox aquifer, northeastern

 Arkansas—Value is rise in water level from 2003 

 to 2009, in feet. Symbols are scaled to value. Letter,

 were present, corresponds to hydrograph in figure 14 

Well completed in Wilcox aquifer, northeastern 

 Arkansas—Value is decline in water level from 2003

 to 2009, in feet. Symbols are scaled to value. Letter, 

 where present, corresponds to hydrograph in figure 14

Well completed in Wilcox aquifer, northeastern 

 Arkansas—No change in water level from 2003 to

 2009, in feet 

EXPLANATION

0 10 20 MILES

0 10 20 KILOMETERS

ARKANSAS

Study

area

*

**

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

C

A

D

G

H

B

-5.0

-3.0

-9.8

-8.8

-8.6

-7.2

-6.7

-6.5

-4.4

-4.3

-4.1

-3.6

-3.5

-3.4

-3.1

-3.1

-2.9

-2.8

-2.7

-2.5

-2.5

-2.4

-2.4

-2.3

-2.2

-2.1

-1.7

-1.4

-1.1

-0.8

-0.2 -21.7

-11.4

-10.8

-10.5

0.2

1.3

F

0.0

0.5

0.1
26 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

had declining water levels, and the remaining well had no 

change in water level. Water levels declined throughout the 

northeastern area with the exception of one well in Crittenden 

County. Three other wells, one in Greene County and two in 

Clay County, also indicate a rise in water levels from 2003 to 

2009. These three wells are located within the upper, perched 

part of the Wilcox aquifer on Crowleys Ridge (appendix 6).

Long-Term Hydrographs

Hydrographs from 42 wells with a minimum of 20 years 

of USGS water-level measurements were constructed (10 in 

the southern area and 32 in the northeastern area). Selected 

hydrographs are shown in figures 13-14 with locations 

indicated on figures 9-12. The minimum 20-year period of 

record was used to evaluate long-term trends not dominated 

by variations in climate and localized pumping rates on water 

levels in a single well. A trend line using linear regression was 

calculated for the period from 1990 to 2009. The slope of the 

trend line represents the computed annual decline or rise in 

water level during the 20-year period. A statistical summary of 

the number of wells, the range of the annual rise or decline in 

water level for the county, the mean, the median, and the range 

of the R2 values for each county are listed in table 3. Negative 

values denote a decline in water level. The statistical summary 

for Clay, Hempstead, and St. Francis Counties was for a single 

well in each county.

Mean annual water-level rise and decline data for the 

period from 1990 to 2009 varied by county. In the southern 

area, Hot Spring County mean annual water-level rose 0.15 ft/

yr, and mean annual declines between 0.03 ft/yr and 0.71 ft/yr 

were computed for Clark, Hempstead, and Nevada Counties. 

In the northeastern area, Greene County mean annual waterlevel rose 0.46 ft/yr, and mean annual declines between 0.03 

ft/yr and 2.12 ft/yr were computed for Clay, Craighead, Crittenden, Lee, Mississippi, Poinsett, and St. Francis Counties. 

Hydrographs for the southern area indicate water-level 

changes in individual walls ranged from rises of 0.44 ft/

yr to declines of 1.68 ft/yr over the 20-year period (fig. 13). 

Hydrograph A, well 07S18W20ABB2 in Clark County (fig. 

13), shows approximately a 6 ft increase in water level over 

the period of record. This well is unconfined and is located in 

the subcrop, receiving vertical recharge. Hydrograph B, well 

10S18W10DDB1, also in Clark County (fig. 13), is located at 

the eastern edge of the outcrop and is under semiconfined conditions, receiving limited vertical recharge. This hydrograph 

shows a general decline through most of the period of record. 

Hydrographs A and B demonstrate the variability within this 

area caused by different confining conditions.

Table 3. Range, mean, and median of annual rise/decline in water level by county for wells completed in the Wilcox aquifer in Arkansas, 

1990-2009.

[Annual rise or decline in water level for each well is calculated using linear regression; negative value indicates decline; positive value indicates rise; R2: 

coefficient of determination ]

County Number of wells

Range or values of 

annual rise (+) or 

decline (-) in water 

level (feet/year)

Mean annual rise (+) 

or decline (-) in water level (feet/year)

Median annual rise 

(+) or decline (-) in 

water level (feet/

year)

Range of R2 values 

for trend lines

Southern area

Clark 5 -0.33 to 0.44 -0.03 -0.22 0.10 to 0.82

Hempstead1 1 -0.07 -0.07 -0.07 0.32

Hot Spring 2 0.11 to 0.18 0.15 0.15 0.53 to 0.56

Nevada 2 -1.68 to 0.26 -0.71 -0.71 0.32 to 0.68

Northeastern area

Clay1 1 -0.03 -0.03 -0.03 0.30

Craighead 4 -0.80 to -0.47 -0.61 -0.58 0.29 to 0.70

Crittenden 8 -2.16 to -0.69 -1.38 -1.41 0.55 to 0.93

Greene 2 0.40 to 0.51 0.46 0.46 0.26 to 0.61

Lee 2 -1.83 to -0.80 -1.31 -1.31 0.89 to 0.99

Mississippi 8 -1.53 to -0.55 -0.89 -0.80 0.32 to 0.95

Poinsett 4 -1.79 to -0.18 -0.99 -0.99 0.07 to 0.98

St. Francis1 1 -2.12 -2.12 -2.12 0.91

1

 County included only one well with 20 or more years of measurements.
Wilcox Aquifer 27

Figure 13. Water-level hydrographs for selected wells completed in the Wilcox aquifer in southern Arkansas.

1975 1980 1985 1990 1995 2000 2005 2010

YEAR

210

220

240

230

WATER LEVEL, IN FEET ABOVE N

ATIONAL GEODETIC VERTICAL D

ATUM OF 1929

No data

A. CLARK COUNTY, WELL 07S18W20ABB2

170

160

150

140

No data

B. CLARK COUNTY, WELL 10S18W10DDB1
28 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

WATER LEVEL, IN FEET ABOVE N

ATIONAL GEODETIC VERTICAL D

ATUM OF 1929

410

400

390

380

D. HOT SPRING COUNTY, WELL 05S17W10AAC1

No data

1975 1980 1985 1990 1995 2000 2005 2010

YEAR

360

350

340

330

No data

C. HEMPSTEAD COUNTY, WELL 13S23W04BDD1

Figure 13. Water-level hydrographs for selected wells completed in the Wilcox aquifer in southern Arkansas.—Continued
Wilcox Aquifer 29

Hydrographs for the northeastern area indicate waterlevel changes in individual wells ranged from rises of 0.51 ft/

yr to declines of 2.16 ft/yr over the 20-year period (fig.14). 

Note there is an inconsistency between the long-term hydrograph data (fig. 14-D and table 3) and the 2003 to 2009 waterlevel difference data for Greene County (fig. 12 and appendix 

6). The summary of long-term hydrograph data for Greene 

County indicates a slight rise in water levels because only two 

wells have 20 or more years of data. The analysis of long-term 

hydrograph data for Greene County does not include well 

16N05E13BAB1, which has the decline of 21.7 ft in the 2003 

to 2009 water-level difference data, because the well does not 

have 20 or more years of water-level measurements. Three 

hydrographs (fig. 14) indicate declining water levels in the 

WATER LEVEL, IN FEET ABOVE N

ATIONAL GEODETIC VERTICAL D

ATUM OF 1929

1975 1980 1985 1990 1995 2000 2005 2010

YEAR

240

250

260

270

E. NEVADA COUNTY, WELL 13S21W02DCC1

No data

Figure 13. Water-level hydrographs for selected wells completed in the Wilcox aquifer in southern Arkansas.—Continued

Wilcox aquifer in counties located on the eastern Arkansas 

border. Hydrograph C, well 06N09E07CAC1 in Crittenden 

County, shows a decline for the period of record and supports 

the existence of the cone of depression near West Memphis. 

This well has an annual decline of 1.57 ft/yr for the period 

1990 to 2009. The annual decline is in reasonable agreement 

with the difference from 2003 to 2009 (fig. 12) of -7.2 ft or 

-1.2 ft/yr. Hydrograph E, well 01N04E09DCC1 in Lee County, 

shows a decline for the period of record and has an annual 

decline of 1.83 ft/yr for the period 1990 to 2009. Hydrograph 

F, well 15N09E31ACD1 in Mississippi County, shows a general decline for the period of record and has an annual decline 

of 0.77 ft/yr for the period 1990 to 2009. 
30 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

220

210

200

190

340

350

360

370

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

B. CRAIGHEAD COUNTY, WELL 14N06E27ACB2

No data

A. CLAY COUNTY, WELL 20N07E1CBB1

Figure 14. Water-level hydrographs for selected wells completed in the Wilcox aquifer in northeastern Arkansas.
Wilcox Aquifer 31

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

210

200

190

180

170

160

120

110

130

140

160

150

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

D. GREENE COUNTY, WELL 17N06E31DCB1

C. CRITTENDEN COUNTY, WELL 06N09E07CAC1

Figure 14. Water-level hydrographs for selected wells completed in the Wilcox aquifer in northeastern Arkansas.—Continued
32 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

190

200

210

220

230

130

140

150

160

170

180

190

200

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

F. MISSISSIPPI COUNTY, WELL 15N09E31ACD1

E. LEE COUNTY, WELL 01N04E09DCC1

Figure 14. Water-level hydrographs for selected wells completed in the Wilcox aquifer in northeastern Arkansas.—Continued
Wilcox Aquifer 33

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

130

140

150

160

170

180

190

200

170

180

190

200

210

220

WATER LEVEL, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

H. ST. FRANCIS COUNTY, WELL 04N06E21BAD2

G. POINSETT COUNTY, WELL 12N05E13BBB1

Figure 14. Water-level hydrographs for selected wells completed in the Wilcox aquifer in northeastern Arkansas.—Continued
34 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

period. The hydrographs in the area between the Ouachita and 

Saline Rivers display mixed results ranging from a decline of 

approximately 20 feet to rises of approximately 2 feet over 

the period of record. The hydrographs in the area east of the 

Saline River show declining water levels over their period of 

record ranging from approximately 60 feet to approximately 5 

feet.

County summaries of the linear regression analysis of the 

33 well hydrographs for the Cockfield aquifer indicate water 

level changes in individual wells ranged from a rise of approximately 0.11 ft/yr to a decline of approximately of 1.46 ft/yr 

over the 20-year period. Cleveland and Columbia Counties 

have mean annual rises 0.11 and 0.03 ft/yr respectively. Wells 

in Arkansas, Ashley, Bradley, Calhoun, Chicot, Desha, Drew, 

Lincoln, and Union Counties have mean annual declines ranging from 0.02 to 1.46 ft/yr. 

The potentiometric-surface for the Wilcox aquifer 

is presented using two maps, one southern Arkansas and 

another for northeastern Arkansas, because of the absence 

of water-level data in the central part of the State. The direction of groundwater flow in the southern area is generally 

the east, except around two cones of depression and around 

two mounds of elevated water levels. The lowest water-level 

altitude measured in the southern area was 147 feet in Clark 

County; the highest water-level altitude measured was 400 

feet in Hempstead County. The direction of groundwater flow 

in the northeastern area is generally to the south and southeast 

except in an area of large groundwater withdrawals that has 

altered the flow to a westerly direction. The lowest water-level 

altitude measured in the northeastern area was 114 feet near 

West Memphis in Crittenden County; the highest water-level 

altitude measured was 368 feet on Crowleys Ridge in Clay 

County. 

Water-level difference maps for the Wilcox aquifer in 

Arkansas were constructed using water-level measurements 

collected from 53 wells made during 2003 and 2009. In the 

southern area, the largest decline in water level (17.7 feet) 

was in Nevada County, and the largest rise in water level 

(16.0 feet) was in Hempstead County. Water levels rose in the 

northern and eastern parts of the southern area, but declined 

in the southern part of the area with the exception of one well 

in Hempstead County. The largest water-level decline in the 

northeastern area was in Greene County (21.7 feet), and the 

largest rise was in Crittenden County (1.3 feet). Water levels 

declined throughout the northeastern area with the exception 

of one well in Crittenden County. Three other wells, one in 

Green County and two in Clay County, also indicate a rise in 

water levels; but these are located within the upper, perched 

part of the Wilcox aquifer on Crowleys Ridge which is hydrologically disconnected from the Wilcox aquifer within the 

surrounding Mississippi Alluvial Plain. 

Mean annual water-level rise and decline data for the 

period 1990-2009 varied by county. In the southern area, Hot 

Spring County’s mean annual water-level rose 0.15 ft/yr, and 

mean annual declines between 0.03 ft/yr and 0.71 ft/yr were 

computed for Clark, Hempstead, and Nevada Counties. In the 

Summary

Eocene-age sand beds near the base of the Cockfield Formation of the Claiborne Group constitute the aquifer known 

locally as the Cockfield aquifer. Upper Paleocene-age sand 

beds within the lower parts of the Wilcox Group constitute the 

aquifer known locally as the Wilcox aquifer. In 2005, reported 

water withdrawals from the Cockfield aquifer in Arkansas 

totaled 16.1 million gallons per day, while reported water 

withdrawals from the Wilcox aquifer in Arkansas totaled 27.0 

million gallons per day. Major withdrawals from these units 

were for industrial and public water supplies with lesser but 

locally important withdrawals for commercial, domestic, and 

agricultural uses. 

During February 2009, 56 water-level measurements 

were made in wells completed in the Cockfield aquifer and 57 

water-level measurements were made in wells completed in 

the Wilcox aquifer. The results from the 2009 water-level measurements are presented in potentiometric-surface maps and in 

combination with previous years’ water-level measurements. 

Trends in water-level change over time within the two 

aquifers are investigated using water-level difference maps 

and well hydrographs. Water-level difference maps were constructed for each aquifer using the difference between depth 

to water measurements made in 2003 and 2009. Well hydrographs for each aquifer were constructed for wells with 20 or 

more years of historical water-level data. The hydrographs 

were evaluated individually using linear regression to calculate the annual rise or decline in water levels and by aggregating the regression results by county and statistically summarizing for the range, mean, and median water-level change in 

each county. 

The 2009 potentiometric surface of the Cockfield aquifer 

map indicates the regional direction of groundwater flow 

generally towards the east and southeast, except in two areas 

of intense groundwater withdrawals that have developed into 

cones of depression. The lowest water-level altitude measured 

was 43 feet in Lincoln County; the highest water-level altitude 

measured was 351 feet in Columbia County. 

A water-level difference map was constructed from 54 

wells completed in the Cockfield aquifer within Arkansas. 

The largest rise in water level (14.9 feet) was in Drew County. 

The largest decline (27.4 feet) was in Lincoln County. Seven 

wells had a rise in water level, and the remaining 47 wells 

had a decline in water level for the 6-year period. The largest 

declines in water levels have occurred along Arkansas’ eastern 

and southern borders. 

Hydrographs for 33 wells with 20 or more years of historical water-level data for the Cockfield aquifer were developed. 

Examination of the hydrographs is divided into three geographic areas: the area south and west of the Ouachita River, 

the area between the Ouachita and Saline Rivers, and the area 

east of the Saline River. The hydrographs in the area south and 

west of the Ouachita River are relatively flat indicating only a 

small, 1- to 3-foot drop in water levels over the 30- to 40-year 
References 35

northeastern area, Greene County’s mean annual water-level 

rose 0.46 ft/yr and mean annual declines between 0.03 ft/yr 

and 2.12 ft/yr were computed for Clay, Craighead, Crittenden, 

Lee, Mississippi, Poinsett, and St. Francis Counties. Hydrographs from 42 wells completed in the Wilcox aquifer were 

constructed (10 in the southern area and 32 in the northeastern 

area). Hydrographs for the southern area indicate water-level 

changes in individual wells ranged from rises of 0.44 ft/yr to 

declines of 1.68 ft/yr over the 20-year period. Hydrographs for 

the northeastern area indicate water-level changes in individual wells ranged from rises of 0.51 ft/yr for declines of 2.16 ft/

yr over the 20-year period. 

References

Ackerman, D.J., 1987, Generalized potentiometric surface 

of the aquifers in the Cockfield Formation, southeastern 

Arkansas, spring 1980: U.S. Geological Survey WaterResources Investigations Report 87-4212, scale 1:500,000, 

1 sheet.

Albin, D.R., 1964, Geology and ground-water resources of 

Bradley, Calhoun, and Ouachita Counties, Arkansas: U.S. 

Geological Survey Water-Supply Paper 1779-G, 32 p.

Arthur, J.K., and Taylor, R.E., 1990, Definition of the geohydrologic framework and preliminary simulation of groundwater flow in the Mississippi Embayment aquifer system, 

Gulf Coastal Plain, United States: U.S. Geological Survey 

Water-Resources Investigations Report 86-4364, 97 p.

Broom, M.E., and Lyford, F.P., 1981, Alluvial aquifer of the 

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Hart, R.M., Clark, B.R., and Bolyard, S.E., 2008, Digital 

surfaces and thicknesses of selected hydrogeologic units 

within the Mississippi Embayment Regional Aquifer Study 

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Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in 

water resources: New York, N.Y., Elsevier Science Publishing Co., 522 p.

Holland, T. W., 1987, Use of water in Arkansas, 1985: Arkansas Geological Commission Water Resources Summary 

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Holland, T.W., 1999, Water use in Arkansas, 1995: U.S. Geological Survey Open-File Report 99-188, 1 sheet.

Holland, T.W., 2004, Estimated water use in Arkansas, 2000: 

U.S. Geological Survey Scientific Investigations Report 

2004-5230, 31 p.

Holland, T.W., 2007, Water use in Arkansas, 2005: U.S. Geological Survey Scientific Investigations Report 2007-5241, 

32 p.

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Arkansas, 1980: Arkansas Geological Commission Water 

Resources Summary Number 14, 30 p.

Hosman, R.L., Long, A.T., Lambert, T.W., and others, 1968, 

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of the Mississippi Embayment and Texas Coastal Uplands 

aquifer systems, South-Central United States: U.S. Geological Survey Professional Paper 1416-B, 19 p.

Hosman, R.L., 1982, Outcropping Tertiary units in southern 

Arkansas: U.S. Geological Survey Miscellaneous Investigations Series I-1405, 1 sheet.

Hosman, R.L., 1988, Geohydrologic framework, Gulf Coastal 

Plain: U.S. Geological Survey Hydrologic Investigations 

Atlas HA-695, 2 sheets.

Joseph, R.L., 1998, Potentiometric surface of the Cockfield 

aquifer in southeastern Arkansas and the Wilcox aquifers 

in southern and northeastern Arkansas, October 1996-July 

1997: U.S. Geological Survey Water-Resources Investigations Report 98- 4084, 19 p.

Onellion, F.E., and Criner, J.H., Jr., 1955, Ground-water 

resources of Chicot County, Arkansas: Arkansas Geological 

and Conservation Commission Water Resources Circular 

No. 3, 27 p.

Petersen, J.C., Broom, M.E., and Bush, W.V., 1985, Geohydrologic units of the Gulf Coastal Plain in Arkansas: U.S. 

Geological Survey Water-Resources Investigations Report 

85-4116, 20 p.

Plebuch, R.O., 1961, Fresh-water aquifers of Crittenden 

County, Arkansas: Arkansas Geological and Conservation 

Commission Water Resources Circular 8, 65 p.

Pugh, A.L., 2008, Summary of aquifer test data for Arkansas 

— 1940-2006: U.S. Geological Survey Scientific Investigations Report 2008-5149, 33 p.
36 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Ryling, R.W., 1960, Ground-water potential of Mississippi 

County, Arkansas: Arkansas Geological and Conservation 

Commission Water Resources Circular 7, 87 p.

Schrader, T.P., and Joseph, R.L., 2000, Potentiometric surfaces of aquifers in the Cockfield Formation in southeastern 

Arkansas and the Wilcox Group in southern and northeastern Arkansas, 2000: U. S. Geological Survey WaterResources Investigations Report 00-4206, 22 p.

Schrader, T.P., 2007, Potentiometric surfaces and water-level 

trends in the Cockfield and Wilcox aquifers of southern and 

northeastern Arkansas, 2006: U.S. Geological Survey Scientific Investigations Report 2007-5218, 27 p.

Westerfield, P.W., 1994, Potentiometric-surface maps of the 

Cockfield and lower Wilcox aquifers in Arkansas, 1991: 

U.S. Geological Survey Water-Resources Investigations 

Report 93-4134, scale 1:500,000, 2 sheets.

Yeatts, Daniel S., 2004, Potentiometric Surfaces in the Cockfield and Wilcox aquifers of southern and northeastern 

Arkansas, 2003: U.S. Geological Survey Scientific Investigations Report 2004-5169, 24 p.
Appendixes 1-6
38 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Appendix 1. Water-level data collected during Feburary 2009 from wells completed in the Cockfield aquifer in southern 

Arkansas.—Continued

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929; --, missing data]

Station name

Latitude

 (degrees, 

minutes,

 seconds)

Longitude

(degrees, 

minutes, 

seconds)

Water-level 

altitude

 (feet above 

NGVD of 

1929)

Depth 

to water

 (feet below 

land-surface 

datum)

Land-surface 

datum 

(feet above 

NGVD of 

1929)

Well depth 

(feet)

Date of 

measurement

Arkansas County

08S02W04ACA1 340139 911406 72 92.92 165 453 2/23/2009

Ashley County

15S04W26CBC1 332144 912932 86 42.28 128 409 2/20/2009

17S04W10BCD2 331417 913030 87 38.50 125 340 2/20/2009

17S04W10CBA1 331406 913033 91 33.78 125 360 2/20/2009

17S06W07ADA1 331442 914510 99 74.75 174 426 2/20/2009

18S04W19DAA2 330710 913247 88 27.79 116 356 2/20/2009

18S08W04BBC1 331038 915627 68 81.06 149 314 2/20/2009

18S08W29DDD2 330630 915629 70 69.68 140 -- 2/20/2009

19S05W12CAC1 330336 913425 85 30.03 115 320 2/20/2009

Bradley County

12S10W10BCA1 334108 920807 102 124.79 227 425 2/19/2009

14S10W01BAD1 333139 920522 86 145.04 231 540 2/19/2009

14S10W31DBA1 332658 921025 96 96.78 193 349 2/19/2009

14S11W35CAB1 332656 921251 113 76.71 190 320 2/19/2009

14S11W35DAC1 332650 921233 109 64.78 174 345 2/19/2009

15S12W11CAB1 332536 921858 131 23.57 155 225 2/19/2009

16S10W11DCB1 331951 920619 107 44.59 152 152 2/19/2009

16S11W11ACA1 332027 921223 111 30.00 141 140 2/19/2009

Calhoun County

11S13W15BBC1 334560 922534 257 53.40 310 70 2/19/2009

13S13W09CBD1 333555 922638 194 37.92 232 147 2/19/2009

13S13W15DBA1 333517 922520 211 21.14 232 122 2/19/2009

14S13W11CAC1 333045 922451 177 28.12 205 105 2/19/2009

14S13W29ADA1 332829 922722 134 26.00 160 81 2/19/2009

14S13W29DAC1 332815 922729 126 13.46 139 -- 2/19/2009

14S14W21ACB1 332931 923249 92 40.13 132 160 2/19/2009

Chicot County

13S03W26BBB1 333247 912301 67 72.38 139 422 2/20/2009

14S03W05BBA1 333106 912602 62 76.74 139 510 2/20/2009

15S03W21ABA1 332314 912438 77 45.33 122 400 2/20/2009

16S02W04BAC1 332027 911857 79 46.39 125 330 2/20/2009

18S02W24CDB1 330652 911547 81 48.47 129 364 2/20/2009

18S02W25ABB3 330640 911541 88 47.42 135 332 2/20/2009

18S03W14CCC1 330731 912319 83 14.62 98 320 2/20/2009
Appendix 39

Appendix 1. Water-level data collected during Feburary 2009 from wells completed in the Cockfield aquifer in southern 

Arkansas.—Continued

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929; --, missing data]

Station name

Latitude

 (degrees, 

minutes,

 seconds)

Longitude

(degrees, 

minutes, 

seconds)

Water-level 

altitude

 (feet above 

NGVD of 

1929)

Depth 

to water

 (feet below 

land-surface 

datum)

Land-surface 

datum 

(feet above 

NGVD of 

1929)

Well depth 

(feet)

Date of 

measurement

Cleveland County

08S13W34BDA1 335902 922444 164 84.14 248 181 2/19/2009

09S10W17CDD1 335534 920942 267 3.42 270 361 2/19/2009

11S11W23BBD1 334449 921258 234 41.16 275 148 2/19/2009

Columbia County

17S20W35BBD1 331313 930914 351 10.35 361 -- 2/18/2009

19S20W34ADC1 330233 930958 289 23.65 313 39.8 2/18/2009

19S21W17CBB1 330520 931857 260 46.06 306 54.8 2/18/2009

19S21W35ADC1 330247 931513 251 4.52 256 30.1 2/18/2009

19S22W36DBB1 330245 932034 307 43.70 351 68.6 2/18/2009

Desha County

12S01W32DCA1 333628 911245 65 71.27 136 495 2/23/2009

12S03W30ADC1 333747 912611 80 72.84 153 280 2/23/2009

13S02W08CAA1 333504 911921 82 65.26 147 515 2/23/2009

Drew County

11S05W35DDB1 334216 913438 98 81.73 180 500 2/23/2009

12S08W33AAB1 333750 915551 70 102.53 173 543 2/23/2009

14S06W21BDC1 332846 914339 95 121.33 216 -- 2/23/2009

14S07W26BAB1 332754 914744 104 125.77 230 440 2/23/2009

Lincoln County

07S06W14BBC1 340709 914026 159 22.82 182 483 2/23/2009

10S05W06CAC1 335204 913918 43 127.32 170 550 2/23/2009

Union County

16S18W22DCD1 331913 925704 234 13.50 247 36 2/18/2009

17S12W27DCA1 331219 921929 158 12.14 170 24 2/18/2009

17S13W17DDC1 331402 922746 155 38.28 193 156 2/18/2009

17S15W31DCA2 331144 924116 201 52.12 253 110 2/18/2009

17S16W33BBA2 331229 924601 230 24.87 255 31 2/18/2009

17S18W15CDA1 331453 925723 262 28.50 290 35 2/18/2009

18S15W21DAC1 330824 923909 174 25.86 200 40 2/18/2009

19S12W28CBA1 330207 922109 189 11.12 200 25 2/18/2009
40 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Appendix 2. Difference in depth to water from 2003 to 2009 in the Cockfield aquifer in southern Arkansas.—Continued

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929; positive differences in 

depth to water indicate a rise in water levels from 2003 to 2009 whereas, negative values indicate a decline in water levels from 2003 to 

2009]

Station name

Latitude

 (degrees,

 minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

2003 depth

 to water

 (feet below 

land-surface 

datum)

2009 depth 

to water

 (feet below

 land-surface 

datum)

Difference in 

depth to water 

 from 2003-2009

 (feet)

Arkansas County

08S02W04ACA1 340139 911406 89.53 92.92 -3.4

Ashley County

15S04W26CBC1 332144 912932 41.99 42.28 -0.3

17S04W10BCD2 331417 913030 37.04 38.50 -1.5

17S04W10CBA1 331406 913033 32.96 33.78 -0.8

17S06W07ADA1 331442 914510 73.05 74.75 -1.7

18S04W19DAA2 330710 913247 25.75 27.79 -2.0

18S08W04BBC1 331038 915627 78.95 81.06 -2.1

19S05W12CAC1 330336 913425 27.24 30.03 -2.8

Bradley County

12S10W10BCA1 334108 920807 122.23 124.79 -2.6

12S10W30CAC1 333815 921046 10.49 11.21 -0.7

14S10W01BAD1 333139 920522 141.96 145.04 -3.1

14S10W31DBA1 332658 921025 94.86 96.78 -1.9

14S11W35CAB1 332656 921251 74.73 76.71 -2.0

14S11W35DAC1 332650 921233 63.94 64.78 -0.8

15S12W11CAB1 332536 921858 22.19 23.57 -1.4

16S10W11DCB1 331951 920619 53.2 44.59 8.6

16S11W11ACA1 332027 921223 26.45 30.00 -3.6

Calhoun County

11S13W15BBC1 334560 922534 50.33 53.40 -3.1

13S13W09CBD1 333555 922638 36.47 37.92 -1.5

13S13W15DBA1 333517 922520 19.11 21.14 -2.0

14S13W11CAC1 333045 922451 27.11 28.12 -1.0

14S13W29ADA1 332829 922722 25.72 26.00 -0.3

14S13W29DAC1 332815 922729 13.53 13.46 0.1

14S14W21ACB1 332931 923249 39.11 40.13 -1.0

Chicot County

13S03W26BBB1 333247 912301 70.1 72.38 -2.3

14S03W05BBA1 333106 912602 76.91 76.74 0.2

15S03W21ABA1 332314 912438 38.2 45.33 -7.1

16S02W04BAC1 332027 911857 45.12 46.39 -1.3

18S02W24CDB1 330652 911547 45.99 48.47 -2.5

18S02W25ABB3 330640 911541 43.42 47.42 -4.0

18S03W14CCC1 330731 912319 13.66 14.62 -1.0
Appendix 41

Appendix 2. Difference in depth to water from 2003 to 2009 in the Cockfield aquifer in southern Arkansas.—Continued

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929; positive differences in 

depth to water indicate a rise in water levels from 2003 to 2009 whereas, negative values indicate a decline in water levels from 2003 to 

2009]

Station name

Latitude

 (degrees,

 minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

2003 depth

 to water

 (feet below 

land-surface 

datum)

2009 depth 

to water

 (feet below

 land-surface 

datum)

Difference in 

depth to water 

 from 2003-2009

 (feet)

Cleveland County

08S13W34BDA1 335902 922444 85.46 84.14 1.3

09S10W17CDD1 335534 920942 3.57 3.42 0.2

11S11W23BBD1 334449 921258 40.1 41.16 -1.1

Columbia County

17S20W35BBD1 331313 930914 7.57 10.35 -2.8

19S20W34ADC1 330233 930958 17.71 23.65 -5.9

19S21W17CBB1 330520 931857 42.47 46.06 -3.6

19S21W35ADC1 330247 931513 0.91 4.52 -3.6

19S22W36DBB1 330245 932034 39.18 43.70 -4.5

Desha County

12S01W32DCA1 333628 911245 67.78 71.27 -3.5

12S03W30ADC1 333747 912611 70.89 72.84 -2.0

13S02W08CAA1 333504 911921 62.62 65.26 -2.6

Drew County

11S05W35DDB1 334216 913438 96.66 81.73 14.9

12S08W33AAB1 333750 915551 99.26 102.53 -3.3

14S06W21BDC1 332846 914339 118.77 121.33 -2.6

14S07W26BAB1 332754 914744 122.87 125.77 -2.9

Lincoln County

07S06W14BBC1 340709 914026 19.89 22.82 -2.9

10S05W06CAC1 335204 913918 99.9 127.32 -27.4

Union County

17S12W27DCA1 331219 921929 9.81 12.14 -2.3

17S13W17DDC1 331402 922746 38.02 38.28 -0.3

17S16W33BBA2 331229 924601 25.25 24.87 0.4

17S18W15CDA1 331453 925723 27.83 28.50 -0.7

18S15W21DAC1 330824 923909 24.43 25.86 -1.4

19S12W28CBA1 330207 922109 10.35 11.12 -0.8
42 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Appendix 3. Water-level data collected during Feburary 2009 from wells completed in the Wilcox aquifer in southern Arkansas.

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929; --, missing data]

Station name

Latitude

 (degrees, 

minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

Water-level

altitude

 (feet above 

NGVD of 1929)

Depth to water 

(feet below 

land-surface 

datum

Land-surface 

datum 

(feet above 

NGVD of 

1929)

Well depth 

(feet)

Date of 

measurement

Clark County

07S18W03BBD1 340917 925604 257 13.36 270 47 2/17/2009

07S18W20ABB2 340652 925757 231 10.71 242 19 2/17/2009

09S18W20CBB1 335611 925905 212 17.58 230 26 2/17/2009

10S20W01BAC1 335403 930612 265 29.69 295 53 2/17/2009

10S18W10DDB1 335216 925613 147 47.76 195 215 2/17/2009

Hempstead County

13S23W04BDD1 333842 932911 346 4.02 350 14 2/17/2009

13S24W02DCA2 333829 933311 400 45.98 446 63 2/17/2009

13S24W29ACC1 333524 933635 344 27.05 371 60 2/17/2009

14S24W29BCA1 333017 933704 333 21.62 355 31 2/17/2009

Hot Spring County

04S16W20CBB1 342144 924532 342 2.90 345 18 2/17/2009

05S17W10AAC1 341836 924853 393 16.74 410 26 2/17/2009

Nevada County

12S22W24CDA1 334046 931941 312 31.73 344 41 2/18/2009

13S21W02DCC1 333754 931426 256 58.86 315 240 2/18/2009

13S21W11BDA1 333738 931432 243 25.39 268 -- 2/18/2009

14S22W19AAA1 333105 932443 311 25.92 337 75 2/18/2009

Ouachita County

12S19W11DCD1 334144 930105 275 13.25 288 533 2/18/2009
Appendix 43

Appendix 4. Water-level data collected during February 2009 from wells completed in the Wilcox aquifer in northeastern 

Arkansas.—Continued

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929]

Station name

Latitude

 (degrees, 

minutes, 

seconds)

Longitude 

(degrees,

 minutes, 

seconds)

Waterlevel altitude 

(feet above 

NGVD of 

1929)

Depth to

water 

(feet below 

land-surface 

datum)

Landsurface 

datum 

(feet above 

NGVD of 

1929)

 Well depth 

(feet) 

Date of 

measurement

Clay County

21N08E14CBB1 362716 901126 296 83.99 380 157 2/25/2009

20N07E01CBB1 362347 901703 368 92.32 460 200 2/25/2009

Craighead County

15N07E33BAD1 355315 902107 203 29.29 232 1,034 2/24/2009

14N07E17DCB1 355008 902202 195 37.39 232 1,070 2/24/2009

14N06E27ACB2 354858 902613 195 32.10 227 999 2/24/2009

14N05E25DCB1 354843 903029 190 43.05 233 890 2/24/2009

14N05E34DAA1 354803 903208 187 43.25 230 865 2/24/2009

13N07E14BBA2 354526 901911 193 27.79 221 1,028 2/24/2009

Crittenden County

09N08E29ADD1 352225 901516 168 56.61 225 1,564 2/26/2009

08N06E33CBD1 351614 902752 160 54.84 215 1,750 2/26/2009

07N07E14CCC1 351318 901930 154 69.20 223 1,584 2/26/2009

07N08E24CAB1 351238 901148 153 67.69 221 1,540 2/26/2009

06N09E07CAC1 350907 901042 114 96.27 210 1,470 2/26/2009

06N07E01ABB1 350520 901807 133 74.01 207 1,541 2/26/2009

05N07E29ACC1 350129 902225 131 69.35 200 1,700 2/26/2009

04N07E36ADB1 345449 901828 133 67.65 201 1,638 2/26/2009

Greene County

18N06E10DCD1 361209 902520 296 24.41 320 120 2/25/2009

17N04E36BCA1 360348 903658 352 153.39 505 311 2/25/2009

17N06E31DCB1 360328 902902 180 105.04 285 462 2/25/2009

16N05E13BAB1 360123 903026 168 122.04 290 545 2/25/2009

Lee County

03N05E01BAB1 345413 903136 140 55.94 196 1,702 2/27/2009

01N04E09DCC1 344209 904220 136 68.08 204 1,885 2/27/2009

Mississippi County

15N10E01ADC1 355712 895806 207 40.54 248 1,350 2/25/2009

15N12E23DBC1 355426 894701 181 57.21 238 1,491 2/25/2009

15N09E31ACD1 355306 900952 199 41.34 240 1,158 2/25/2009

14N11E20CCA1 354859 895626 201 39.03 240 1,518 2/25/2009

13N11E08DDA1 354528 895547 186 59.36 245 1,445 2/25/2009

13N11E31CCCC1 354221 895807 187 54.38 241 1,500 2/25/2009

12N11E17CDD1 353917 895618 184 60.93 245 1,500 2/25/2009

11N08E10AAC2 353538 901301 179 41.47 220 1,380 2/26/2009
44 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Appendix 4. Water-level data collected during February 2009 from wells completed in the Wilcox aquifer in northeastern 

Arkansas.—Continued

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929]

Station name

Latitude

 (degrees, 

minutes, 

seconds)

Longitude 

(degrees,

 minutes, 

seconds)

Waterlevel altitude 

(feet above 

NGVD of 

1929)

Depth to

water 

(feet below 

land-surface 

datum)

Landsurface 

datum 

(feet above 

NGVD of 

1929)

 Well depth 

(feet) 

Date of 

measurement

Mississippi County—Continued

11N10E20ADA1 353349 900213 187 48.03 235 1,417 2/25/2009

11N09E33AAB1 353214 900739 184 52.98 237 1,560 2/26/2009

10N08E17ADD1 352923 901505 171 53.52 225 1,521 2/26/2009

Poinsett County

12N05E13BBB1 354038 903059 174 47.68 222 1,071 2/24/2009

11N07E03BDD1 353629 901955 174 41.79 216 1,456 2/24/2009

11N05E06CCD1 353622 903618 171 42.88 214 992 2/24/2009

11N05E36AAA1 353234 903009 175 38.83 214 1,175 2/24/2009

11N06E35CDA3 353152 902520 184 30.97 215 1,301 2/24/2009

10N07E16CBB2 352925 902129 165 52.53 218 1,500 2/24/2009

St. Francis County

04N06E16CCB1 345712 902830 139 62.65 202 1,615 2/27/2009

04N06E21BAD2 345649 902815 130 70.79 201 1,740 2/27/2009
Appendix 45

Appendix 5. Difference in depth to water from 2003 to 2009 in the Wilcox aquifer in southern Arkansas.

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929; 

positive differences in depth to water indicate a rise in water levels from 2003 to 2009 whereas negative values 

indicate a decline in water levels from 2003 to 2009]

Station name

Latitude

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

2003 depth 

to water 

(feet below

land-surface 

datum)

2009 depth 

to water

 (feet below 

land-surface 

datum)

Difference in 

depth to water 

from 2003-2009

 (feet)

Clark County

07S18W03BBD1 340917 925604 14.51 13.36 1.2

07S18W20ABB2 340652 925757 11.29 10.71 0.6

09S18W20CBB1 335611 925905 17.97 17.58 0.4

10S20W01BAC1 335403 930612 29.75 29.69 0.1

Hempstead County

13S24W29ACC1 333524 933635 43.08 27.05 16.0

13S24W02DCA2 333829 933311 45.43 45.98 -0.6

14S24W29BCA1 333017 933704 17.70 21.62 -3.9

Hot Spring County

04S16W20CBB1 342144 924532 4.62 2.9 1.7

05S17W10AAC1 341836 924853 17.23 16.74 0.5

Nevada County

13S21W11BDA1 333738 931432 23.44 25.39 -2.0

12S22W24CDA1 334046 931941 27.58 31.73 -4.2

14S22W19AAA1 333105 932443 8.25 25.92 -17.7

Ouachita County

12S19W11DCD1 334144 930105 15.59 13.25 2.3
46 Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers

Appendix 6. Difference in depth to water from 2003 to 2009 in the Wilcox aquifer in northeastern 

Arkansas.—Continued

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929; positive differences in depth to water indicate a rise in water levels from 2003 to 2009 whereas negative values indicate a decline in water 

levels from 2003 to 2009]

Station name

Latitude

 (degrees, 

minutes,

 seconds)

Longitude

 (degrees, 

minutes, 

seconds)

2003 depth 

to water

(feet below

 land-surface 

datum)

2009 depth 

to water

 (feet below

 land-surface 

datum)

Difference in 

water level from 

2003-2009 

(feet)

Clay County

20N07E01CBB1 362347 901703 92.85 92.32 0.5

21N08E14CBB1 362716 901126 84.08 83.99 0.1

Craighead County

14N06E27ACB2 354858 902613 30.36 32.10 -1.7

15N07E33BAD1 355315 902107 26.87 29.29 -2.4

14N05E25DCB1 354843 903029 39.96 43.05 -3.1

14N05E34DAA1 354803 903208 39.64 43.25 -3.6

13N07E14BBA2 354526 901911 23.71 27.79 -4.1

14N07E17DCB1 355008 902202 30.74 37.39 -6.7

Crittenden County

07N08E24CAB1 351238 901148 66.87 67.69 -0.8

08N06E33CBD1 351614 902752 52.39 54.84 -2.5

07N07E14CCC1 351318 901930 66.46 69.20 -2.7

06N09E07CAC1 350907 901042 89.08 96.27 -7.2

05N07E29ACC1 350129 902225 60.72 69.35 -8.6

04N07E36ADB1 345449 901828 58.87 67.65 -8.8

06N07E01ABB1 350520 901807 64.25 74.01 -9.8

09N08E29ADD1 352225 901516 57.89 56.61 1.3

Greene County

17N06E31DCB1 360328 902902 104.85 105.04 -0.2

16N05E13BAB1 360123 903026 100.38 122.04 -21.7

18N06E10DCD1 361209 902520 24.63 24.41 0.2

17N04E36BCA1 360348 903658 153.38 153.39 0.0

Lee County

03N05E01BAB1 345413 903136 49.44 55.94 -6.5

Mississippi County

13N11E31CCCC1 354221 895807 52.17 54.38 -2.2

11N10E20ADA1 353349 900213 45.62 48.03 -2.4

10N08E17ADD1 352923 901505 51.03 53.52 -2.5

13N11E08DDA1 354528 895547 56.52 59.36 -2.8

15N12E23DBC1 355426 894701 54.23 57.21 -3.0

15N09E31ACD1 355306 900952 37.98 41.34 -3.4

14N11E20CCA1 354859 895626 35.53 39.03 -3.5

15N10E01ADC1 355712 895806 36.25 40.54 -4.3
Appendix 47

Appendix 6. Difference in depth to water from 2003 to 2009 in the Wilcox aquifer in northeastern 

Arkansas.—Continued

[Horizontal datum is North American Datum of 1983; NGVD of 1929, National Geodetic Vertical Datum of 1929; positive differences in depth to water indicate a rise in water levels from 2003 to 2009 whereas negative values indicate a decline in water 

levels from 2003 to 2009]

Station name

Latitude

 (degrees, 

minutes,

 seconds)

Longitude

 (degrees, 

minutes, 

seconds)

2003 depth 

to water

(feet below

 land-surface 

datum)

2009 depth 

to water

 (feet below

 land-surface 

datum)

Difference in 

water level from 

2003-2009 

(feet)

Mississippi County—Continued

11N08E10AAC2 353538 901301 37.09 41.47 -4.4

11N09E33AAB1 353214 900739 47.98 52.98 -5.0

12N11E17CDD1 353917 895618 50.40 60.93 -10.5

Poinsett County

12N05E13BBB1 354038 903059 45.59 47.68 -2.1

11N07E03BDD1 353629 901955 38.92 41.79 -2.9

11N05E06CCD1 353622 903618 41.50 42.88 -1.4

11N05E36AAA1 353234 903009 36.57 38.83 -2.3

11N06E35CDA3 353152 902520 29.87 30.97 -1.1

10N07E16CBB2 352925 902129 49.40 52.53 -3.1

St. Francis County

04N06E16CCB1 345712 902830 51.86 62.65 -10.8

04N06E21BAD2 345649 902815 59.38 70.79 -11.4
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For more information concerning the research 

described in the report: contact:

U.S. Geological Survey

Arkansas Water Science Center

401 Hardin Road

Little Rock, AR 72211-3528

(501) 228-3600

http://ar.water.usgs.gov
Pugh—Potentiometric Surfaces and Water-Level Trends in the Cockfield and Wilcox Aquifers—Scientific Investigations Report 2010-5014

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