U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2014–5232

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) Aquifer in Southern Arkansas 

and the Wilcox (Lower Wilcox) Aquifer of Northeastern and 

Southern Arkansas, 2012

36o

35o

34o

94o 93o 92o 91o

90o

MISSOURI

MISSISSIPPI

TEXAS

OKLAHOMA

TENNESSEE

LOUISIANA

ARKANSAS

West Gulf Coastal Plain

Mississippi Alluvial Plain

Ouachita Mountains

OZARK PLATEAUS

INTERIOR

OUACHITA

PROVINCE

Arkansas Valley

COASTAL

PLAIN

HIGHLANDS CLAY

GREENE

CRAIGHEAD MISSISSIPPI

POINSETT

CROSS

ST. FRANCIS

LEE

ARKANSAS

JEFFERSON

GRANT

DALLAS CLEVELAND

LINCOLN

DESHA

DREW

CHICOT ASHLEY

BRADLEY

CALHOUN

UNION

OUACHITA

COLUMBIA

NEVADA HEMPSTEAD

CLARK

HOT SPRING

CRITTENDEN

Mississippi River
 
Potentiometric Surfaces and WaterLevel Trends in the Cockfield (Upper 

Claiborne) Aquifer in Southern Arkansas 

and the Wilcox (Lower Wilcox) Aquifer of 

Northeastern and Southern Arkansas, 2012

By Kirk D. Rodgers

Prepared in cooperation with the Arkansas Natural Resources Commission and 

the Arkansas Geological Survey

Scientific Investigations Report 2014–5232

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2015

Suggested citation:

Rodgers, K.D., 2015, Potentiometric surfaces and water-level trends in the Cockfield (upper Claiborne) aquifer 

in southern Arkansas and the Wilcox (lower Wilcox) aquifer of northeastern and southern Arkansas, 2012: U.S. 

Geological Survey Scientific Investigations Report 2014–5232, 46 p., http://dx.doi.org/10.3133/sir20145232. 

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

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U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

ISSN 2328-0328 (online)
iii

Contents

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

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

Methods ..........................................................................................................................................................4

Water-Level Measurements ..............................................................................................................4

Linear Regression ................................................................................................................................4

Geographic Information Systems .....................................................................................................4

Cockfield (Upper Claiborne) Aquifer ..........................................................................................................6

Hydrogeologic Setting ........................................................................................................................6

Hydraulic Properties ..................................................................................................................6

Water Use ....................................................................................................................................8

Potentiometric Surface .......................................................................................................................9

Water-Level Trends .............................................................................................................................9

Water-Level Difference from 2006 to 2012 ..............................................................................9

Long-Term Hydrographs ..........................................................................................................12

Wilcox (Lower Wilcox) Aquifer .................................................................................................................19

Hydrogeologic Setting ......................................................................................................................19

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

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

Potentiometric Surface .....................................................................................................................20

Water-Level Trends ...........................................................................................................................23

Water-Level Difference from 2006 to 2012 ............................................................................23

Long-Term Hydrographs ..........................................................................................................23

Summary .......................................................................................................................................................33

References Cited .........................................................................................................................................34

Appendixes

1. Water-level data collected during February 2012 from wells completed in the 

Cockfield aquifer in southern Arkansas .................................................................................39

2. Difference in depth to water from 2006 to 2012 in the Cockfield aquifer in 

southern Arkansas ....................................................................................................................41

3. Water-level data collected during February and March 2012 from wells 

completed in the Wilcox aquifer in northeastern Arkansas ...............................................42

4. Water-level data collected during February and March 2012 from wells 

completed in the Wilcox aquifer in southern Arkansas ......................................................43

5. Difference in depth to water from 2006 to 2012 in the Wilcox aquifer in 

northeastern Arkansas .............................................................................................................44

6. Difference in depth to water from 2006 to 2012 in the Wilcox aquifer in southern 

Arkansas .....................................................................................................................................45
iv

Figures

1. Map showing location of study area of Cockfield aquifer in southern Arkansas 

and Wilcox aquifer in northeastern and southern Arkansas ...............................................3

2. Diagram showing well-numbering system ..............................................................................5

3. Diagram showing generalized section of the hydrogeologic and geologic units 

within the Mississippi Embayment ...........................................................................................8

4. Bar graph showing water use from the Cockfield aquifer in southern Arkansas, 

1975–2010 ......................................................................................................................................8

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

Arkansas, 2012 ...........................................................................................................................10

6. Map showing water-level difference for the Cockfield aquifer in southern 

Arkansas, 2006–12 .....................................................................................................................11

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

southern Arkansas ....................................................................................................................13

8. Bar graph showing water use from the Wilcox aquifer in Arkansas, 1975–2010 ...........20

9. Map showing potentiometric surface of the Wilcox aquifer in northeastern 

Arkansas, 2012 ...........................................................................................................................21

10. Map showing potentiometric surface of the Wilcox aquifer in southern 

Arkansas, 2012 ...........................................................................................................................22

11. Map showng water-level difference for the Wilcox aquifer in northeastern 

Arkansas, 2006–12 .....................................................................................................................24

12. Map showng water-level difference for the Wilcox aquifer in southern Arkansas, 

2006–12 ........................................................................................................................................25

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

northeastern Arkansas .............................................................................................................26

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

southern Arkansas ....................................................................................................................30

Tables

1. Hydrogeologic and geologic units within the Mississippi Embayment of 

Arkansas .......................................................................................................................................7

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

wells with 20 or more years of record completed in the Cockfield aquifer in 

Arkansas .....................................................................................................................................19

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

wells with 20 or more years of record completed in the Wilcox aquifer in 

Arkansas .....................................................................................................................................32
v

Conversion Factors

Inch/Pound to International System of Units

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Flow rate

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

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

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

/s)

Specific capacity

gallon per minute per foot 

[(gal/min)/ft)]

 0.2070 liter per second per meter 

[(L/s)/m]

Transmissivity*

foot squared per day (ft2

/d) 0.09290 meter squared per day (m2/d) 

Datum

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD of 1929)

Horizontal coordinate information is referenced to North American Datum of 1983 (NAD 83).

Supplemental Information

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

*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, foot 

squared per day (ft2/d), is used for convenience.

Potentiometric Surfaces and Water-Level Trends in the 

Cockfield (Upper Claiborne) Aquifer in Southern Arkansas 

and the Wilcox (Lower Wilcox) Aquifer of Northeastern 

and Southern Arkansas, 2012

By Kirk D. Rodgers

Abstract

The Cockfield aquifer, located in southern Arkansas, is 

composed of Eocene-age sand beds found near the base of the 

Cockfield Formation of Claiborne Group. The Wilcox aquifer, 

located in northeastern and southern Arkansas, is composed 

of Paleocene-age sand beds found in the middle to lower part 

of the Wilcox Group. The Cockfield and Wilcox aquifers are 

primary sources of groundwater. In 2010, withdrawals from 

the Cockfield aquifer in Arkansas totaled 19.2 million gallons 

per day (Mgal/d), and withdrawals from the Wilcox aquifer 

totaled 36.5 Mgal/d. 

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

cooperation with the Arkansas Natural Resources Commission 

and the Arkansas Geological Survey to measure water levels 

associated with the Cockfield aquifer and the Wilcox aquifer 

in northeastern and southern Arkansas. Water levels were 

measured at 43 wells completed in the Cockfield aquifer 

and 47 wells completed in the Wilcox aquifer in February 

and March 2012. Measurements from 2012 are presented 

as potentiometric-surface maps and in combination with 

measurements from 2006 as water-level difference maps. 

Trends in water-level change over time within the Cockfield 

and Wilcox aquifers were determined using the water-level 

difference maps and selected well hydrographs. 

The Cockfield aquifer study area in southern Arkansas 

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

west by the area that contains outcrops and subcrops of the 

Cockfield Formation. The northern boundary of the Cockfield 

aquifer study area is defined by the area that contains 

observation wells completed in the Cockfield aquifer and the 

southern boundary is the Louisiana State line. 

The Wilcox aquifer study area in northeastern Arkansas 

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

north by the Missouri State line. The southern and western 

boundaries are defined by areas containing observation wells 

completed in the Wilcox aquifer or by outcrop areas on or near 

Crowleys Ridge. The Wilcox aquifer study area in southern 

Arkansas is defined by observation wells completed in the 

Wilcox aquifer or by areas that contain outcrops of the Wilcox 

Group, or both. 

The potentiometric-surface map of the Cockfield 

aquifer shows the regional direction of groundwater flow 

was generally toward the east-southeast, except in areas of 

intense groundwater withdrawals such as southwestern Ashley 

County, where groundwater flows toward the town of Crossett. 

The highest water-level altitude measured was 350 feet (ft) 

above National Geodetic Vertical Datum of 1929 (NGVD 29) 

in central Columbia County. The lowest water-level altitude 

measured was 40 ft above NGVD 29 in southeastern Lincoln 

County.

The water-level difference map for the Cockfield 

aquifer in Arkansas was constructed using 42 water-level 

measurements made during 2006 and 2012. The difference in 

water levels for the Cockfield aquifer ranged from 27.4 ft to 

-10.4 ft. The largest water-level rise was in Calhoun County, 

and the largest water-level decline was 10.4 ft in Union 

County. Of the 42 wells, 13 wells had a rise in water level, and 

the remaining 29 wells had a decline in water level. 

Hydrographs for 32 wells in the Cockfield aquifer 

with historical water-level data were evaluated using linear 

regression to calculate the annual rise or decline for each 

well. These data were aggregated by county and statistically 

evaluated for the range, mean, and median of water-level 

change in each county. Hydrographs for Bradley, Calhoun, 

Chicot, Columbia, and Union Counties indicated both rising 

and declining water levels. The mean annual water-level rise 

or decline for Calhoun County was 0.00 foot per year (ft/yr) or 

unchanged. The mean annual water-level for Ashley, Bradley, 

Chicot, Cleveland, Columbia, Lincoln, and Union Counties 

show declines ranging from -0.02 to -1.10 ft/yr.

Two potentiometric-surface maps, one for the southern 

area and one for the northeastern area, were constructed to 

show the altitude of the water surface in the Wilcox aquifer. 

The direction of groundwater flow in the northeastern area was 

generally towards the south-southwest except for some areas 
2 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

immediately adjacent to the Mississippi River where the flow 

was more eastward towards the river. The highest water-level 

altitude was 219 ft in northern Mississippi County, and the 

lowest water-level altitude was 123 ft near West Memphis in 

Crittenden County. The direction of groundwater flow in the 

northern part of the southern area was generally towards the 

southwest. The direction of groundwater flow in the southern 

part was in all directions because of two cones of depression 

and two water-level mounds. The highest water-level altitude 

measured was 394 ft at the center of a water-level mound 

in eastern Hot Spring County and a water-level mound in 

southwestern Hempstead County. The lowest water-level 

altitude measured was 145 ft at the center of the cone of 

depression in Clark County. 

Water-level difference maps for the Wilcox aquifer in 

Arkansas were constructed using 47 water-level measurements 

made during 2006 and 2012. The difference in water levels 

for the Wilcox aquifer in the northeastern area ranged from 

22.0 ft to -17.9 ft. The largest rise in water level occurred in 

Crittenden County, and the largest decline occurred in Lee 

County. Twenty-one wells had rising water levels, and 10 

wells had declining water levels. The difference in water levels 

for the Wilcox aquifer in the southern area ranged from 18.1 ft 

to -4.2 ft. The largest rise and the largest decline in water level 

occurred in Nevada County. Twelve wells had rising water 

levels, and 4 wells had declining water levels.

Linear regression analysis of long-term hydrographs was 

used to determine the mean annual water-level rise and decline 

in the Wilcox aquifer in the northeastern and southern areas 

of Arkansas. In the northeastern area, the mean annual water 

level declined in all seven counties. The mean annual declines 

ranged from -0.55 ft/yr in Craighead County to -1.46 ft/yr in 

St. Francis County. In the southern area, the annual rise and 

decline calculations for wells with over 20 years of records 

indicate rising and declining water levels in Clark, Hot Spring, 

and Nevada Counties. The mean annual water level declined 

in all counties except Hot Spring County. 

Introduction

The Cockfield aquifer (recognized nationally as the 

Upper Claiborne aquifer), located in southern Arkansas, is 

composed of Eocene-age sand beds found near the base of 

the Cockfield Formation of Claiborne Group. The Middle 

and Lower Wilcox aquifer (recognized nationally as the 

lower Wilcox aquifer), located in northeastern and southern 

Arkansas, is composed of Paleocene-age sand beds found in 

the lower part of the Wilcox Group. The Cockfield and Wilcox 

aquifers are sources of groundwater for local use. In 2010, 

withdrawals from the Cockfield aquifer in Arkansas totaled 

19.2 million gallons per day (Mgal/d), and withdrawals from 

the Wilcox aquifer totaled 36.5 Mgal/d. In 2010, the Cockfield 

aquifer in Arkansas ranked fifth in combined usage for the 

State, and the Wilcox aquifer ranked third. 

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 

water levels associated with the Cockfield aquifer in southern 

Arkansas and the Wilcox aquifer in northeastern and southern 

Arkansas. In February and March 2012, water levels were 

measured at 43 wells completed in Cockfield aquifer and 

47 wells completed in the Wilcox aquifer. These water-level 

measurements are presented as potentiometric-surface maps, 

in combination with measurements from 2006 as water-level 

difference maps, and in long-term hydrographs. 

The study areas of the Cockfield and Wilcox aquifers 

are part of the Mississippi Embayment that includes much 

of the West Gulf Coastal Plain and the Mississippi Alluvial 

Plain in Arkansas (fig. 1). The Mississippi Embayment is a 

north-northeast trending syncline, plunging south-southwest, 

and is filled with Cretaceous and younger-age sediments. 

The study area of the Cockfield aquifer in southern Arkansas 

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

west by the area that contains outcrops and subcrops of the 

Cockfield Formation (Hosman, 1982). The northern boundary 

of the Cockfield aquifer study area is defined by the locations 

of observation wells completed in the Cockfield aquifer, and 

the southern boundary is the Louisiana State line (fig. 1). 

The Wilcox aquifer study area in northeastern Arkansas is 

bounded on the east by the Mississippi River and on the 

north by the Missouri State line. The southern and western 

boundaries are defined by areas containing observation 

wells completed in the Wilcox aquifer or by outcrop areas 

in or near Crowleys Ridge. Crowleys Ridge is an erosional 

remnant of Cretaceous- and Tertiary-age rocks that ranges 

from 0.5 to 12 miles (mi) wide, rises 250 to 550 feet (ft) 

above the surrounding Mississippi Alluvial Plain, and extends 

about 150 mi from southeastern Missouri to east-central 

Arkansas. The Wilcox aquifer study area in southern Arkansas 

is defined by observation wells completed in the Wilcox 

aquifer or by areas that contain outcrops of the Wilcox Group, 

or both. 

This is the sixth in a series of triennial reports discussing 

the potentiometric surfaces of the Cockfield and Wilcox 

aquifers in Arkansas. Earlier reports, with water-level 

measurements made in 1991, 1996–97, 2000, 2003, 2006, 

and 2009 are reported in Westerfield (1994), Joseph (1998), 

Schrader and Joseph (2000), Yeatts (2004), Schrader (2007), 

and Pugh (2010). 
Introduction 3

36o

35o

34o

94o 93o 92o 91o

90o

MISSOURI

MISSISSIPPI

TEXAS

OKLAHOMA

TENNESSEE

LOUISIANA

ARKANSAS

0 20 40 MILES

0 20 40 KILOMETERS

West Gulf Coastal Plain

Mississippi Alluvial Plain

Ouachita Mountains

OZARK PLATEAUS

INTERIOR

OUACHITA

PROVINCE

Arkansas Valley

COASTAL

PLAIN

HIGHLANDS

CLAY

GREENE

CRAIGHEAD MISSISSIPPI

POINSETT

CROSS

ST. FRANCIS

LEE

ARKANSAS

JEFFERSON

GRANT

DALLAS CLEVELAND

LINCOLN

DESHA

DREW

CHICOT ASHLEY

BRADLEY

CALHOUN

UNION

OUACHITA

COLUMBIA

NEVADA HEMPSTEAD

CLARK

HOT SPRING

CRITTENDEN

Mississippi River

Physiographic division boundaries 

from Fenneman and Johnson (1946)

Base from U.S. Geological Survey

digital data, 1:100,000

Aquifer

 Cockfield aquifer in southern Arkansas

 Wilcox aquifer in southern Arkansas

 Wilcox aquifer in northeastern Arkansas

EXPLANATION

Crowleys Ridge

Physiographic division boundary

 Major Division

 Province

 Section

Figure 1. Location of study area of Cockfield aquifer in southern Arkansas and Wilcox aquifer in northeastern and southern Arkansas.
4 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Methods 

The well-numbering system used in this report is based 

on location of wells according to the Public Land Survey 

System used in Arkansas (U.S. Geological Survey, 2014). 

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 quarterquarter section, and the quarter-quarter-quarter section in 

which the well is located, and a sequence number. The letters 

are assigned counterclockwise, beginning with “A” in the 

northeast quarter, 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 (Pugh, 2010).

The horizontal coordinate information (latitude and 

longitude) of a well was determined using a global positioning 

system, and land-surface altitude information was determined 

using a USGS 7.5-minute, 1:24,000 quadrangle topographic 

map. The horizontal coordinate information is based on the 

North American Datum of 1983 and is accurate to about onetenth of a second (approximately 10–20 ft). The location of 

the well was then plotted on the corresponding topographic 

map and the land-surface altitude at that point was determined 

by interpolation of the topographic contours. This altitude 

is accurate to about one-half the contour interval of the 

topographic map, which is based on the National Geodetic 

Vertical Datum of 1929 (NGVD 29). 

Water-Level Measurements 

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 2010, prior to collecting water-level measurements. 

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. The waterlevel data are stored in the USGS National Water Information 

System (NWIS) (U.S. Geological Survey, 2002).

Potentiometric-surface maps for the Cockfield and 

Wilcox aquifers in Arkansas were constructed by plotting 

well positions with their respective water-level altitude 

using ArcGIS (Esri, 2011). The altitude of the water level 

in each well was determined by subtracting the measured 

depth to water from the 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 2006 

and 2012. The difference in water level was calculated by 

subtracting the 2012 depth-to-water value from the 2006 

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

difference values indicate a rise in water level, and negative 

difference values indicate a decline in water level. 

Linear Regression

A linear regression analysis was used to determine the 

annual rise or decline of water level in selected wells using 

the well hydrograph. Water-level measurements made yearly 

during March, April, and May of the minimum 20-year period 

of record were used in the linear regression analysis. The 

equation of the regression line or line of best fit is Y = MX 

+ B. The slope, M from the equation, represents the daily 

rise or decline in water level, B is the water level measured 

in feet at the y-intercept and X is the year in which the 

measurement was made. Five assumptions are associated 

with linear regression: (1) Y is linearly related to X, (2) data 

used to fit the linear regression are representative of data of 

interest, (3) variance of the residuals is constant and does 

not depend on X or on anything else, (4) the residuals are 

independent, and (5) the residuals are normally distributed. 

The assumption of a normal distribution is involved only when 

testing hypotheses, requiring the residuals from the regression 

equation to be normally distributed (Helsel and Hirsch, 

1992). Water-level measurements collected during February 

and March of 2006 and 2012 were used for linear regression 

analysis.

Geographic Information Systems 

Longitudes, latitudes, and measured water-level altitudes 

of the Cockfield and Wilcox aquifer wells were obtained 

from NWIS and geocoded using ArcGIS (Esri, 2011), which 

is a computer-based application used to visually represent 

spatially based data using geographic coordinates. These data 

points were then interpolated using the kriging method of 

interpolation to construct potentiometric-surface maps of the 

Cockfield and Wilcox aquifers. This process produces a raster 

image in which each color represents a range of water-level 

values. The raster images were then converted to contour lines 

using the ArcGIS Contour tool. Upon conversion, the contour 

polylines were corrected and refined using the Polynomial 

Approximation with Exponential Kernel (PAEK) method of 

smoothing (Bodansky and others, 2002). The PAEK method 

uses a maximum allowable offset to smooth lines. PAEK is 

a smoothing algorithm that sets a tolerance by which lines 

are smoothed. A higher tolerance preserves less detail from 

the original interpolated contour line, and a lower tolerance 

preserves more detail. This method allows for the preservation 

of end points. 
Methods 5

PRINCIPAL MERIDIAN

BASE LINE

TOWNSHIPS

WEST EAST SOUTH NORTH

RANGES

1E

2E

3E

4E

1W 2W 3W 4W 5W

5E

6E

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

Figure 2. Well-numbering system.
6 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Cockfield (Upper Claiborne) Aquifer 

Hydrogeologic Setting

The Cockfield aquifer generally consists of discontinuous 

fine- to medium-grained sand units interbedded with silt, 

clay, and lignite of nonmarine origin. Most of the sand beds 

of the Cockfield aquifer are located near the base of the 

Cockfield Formation of Claiborne Group (hereafter referred 

to as Cockfield Formation) (table 1). The Cockfield Formation 

ranges from 100 to 400 ft thick in the outcrop areas and 

thickens downdip to about 625 ft in northeastern Chicot 

County (Onellion and Criner, 1955). The Cockfield Formation 

dips to the south and east towards the synclinal axis of the 

Mississippi Embayment (fig. 3). Thicknesses of the sand 

beds of the Cockfield aquifer generally range from 20 to 150 

ft. Throughout the study area, the Cockfield Formation is 

underlain by calcareous and sandy marl, carbonaceous clay, 

and limestone of the Cook Mountain Formation of Claiborne 

Group (table 1). In much of the study area, the Cockfield 

Formation is overlain by silty clays of the Jackson Group. 

The potentiometric surface can be near or above land 

surface in the confined part of the Cockfield aquifer. Sand beds 

at the base of the overlying Jackson Group in parts of southern 

Arkansas may be in hydraulic connection with the Cockfield 

aquifer (Ackerman, 1987). The Cockfield Formation and 

aquifer outcrop in Bradley, Calhoun, Cleveland, Columbia, 

Dallas, Grant, and Union Counties and dips to the southeast. 

In the subcrop area, Quaternary-age terrace deposits and 

alluvium overlie the Cockfield Formation. The thickness 

of terrace deposits may reach 40 ft, and as much as 60 ft of 

alluvium overlies the formation in some of the larger river 

valleys A generalized section of the hydrogeologic and 

geologic units within the Mississippi Embayment are shown in 

figure 3. 

Most of the Cockfield aquifer recharge 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 connecting them hydrologically with 

the aquifer. Discharge from the aquifer is to hydrologically 

connected rivers in the outcrop areas, vertically to adjacent 

hydrogeologic units where the aquifer is confined, and to wells 

completed in the aquifer (Ackerman, 1987). In the outcrop 

areas, well depths in the aquifer are less than 200 ft and well 

yields are small, usually less than 30 gallons per minute (gal/

min), but in areas downdip from the outcrop areas, wells 

screening the full thickness of the aquifer may yield from 100 

to 500 gal/min (Westerfield, 1994). 

Hydraulic Properties 

Values for specific capacity and transmissivity vary 

within the Cockfield aquifer. Specific capacity values 

range 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 range from 325 feet squared per day 

(ft2/d) to 6,280 ft2/d with a median of 3,350 ft2/d and a mean of 

3,300 ft2/d. Hydraulic conductivity values were not provided 

for any of the well tests completed in the Cockfield aquifer. 

An estimated hydraulic conductivity value for the Cockfield 

aquifer was determined by dividing the mean transmissivity 

value (3,300 ft2/d) by the maximum aquifer thickness (400 ft), 

resulting in a value of 8.33 ft/d (Pugh, 2008).
Cockfield (Upper Claiborne) Aquifer 7

Table 1. Hydrogeologic and geologic units within the Mississippi Embayment of Arkansas (modified from Hosman and Weiss, 1991; 

Hart and others, 2008). 

[Dashed lines indicate the approximate location where hydrogeologic units begin and end] Erathem System Series Group

Geologic unit

Hydrogeologic

Southern unit

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
8 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Water Use

Withdrawals from the Cockfield aquifer during 2010 

totaled about 19.2 Mgal/d (Terrance W. Holland, U.S. 

Geological Survey written commun., 2013) (fig. 4). These 

withdrawals were primarily for industrial and public supply 

use, but withdrawals for agricultural, commercial, and 

domestic use are important locally. Withdrawals from the 

Cockfield aquifer rose from 1975 to 2010, with the exception 

of 1985. Withdrawals were 5.2 Mgal/d in 1975, 7.2 Mgal/d in 

1980, 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 (Halberg 

and Johnson, 1977; Holland and Ludwig, 1981; Holland, 

1987, 1993, 1999, 2004, 2007). The increase in withdrawals 

from the Cockfield aquifer between 2000 (9.9 Mgal/d) and 

2005 (16.1 Mgal/d) are associated with increased use of 

water by public water-supply systems in eastern Arkansas 

(Holland, 2004, 2007; Pugh, 2010), and the increase in 

withdrawals from the aquifer between 2005 (16.1 Mgal/d) and 

2010 (19.2 Mgal/d) are associated with increased industrial 

use of water in eastern Arkansas (Terrance W. Holland, U.S. 

Geological Survey written commun., 2013). Most wells 

completed in the study area provide small volumes of water 

for domestic and livestock use, but in some locations, the 

aquifer yields volumes large enough to supply industrial and 

public-supply systems.

In 2010, the State of Mississippi withdrew 22.8 Mgal/d 

of water from the Cockfield aquifer. Across the State line from 

Chicot County, Ark., the city of Greenville, Miss., withdrew 

10.4 Mgal/d of water for public supply from the Cockfield 

aquifer in 2010 (D.E. Burt, U.S. Geological Survey, written 

commun., 2013). Withdrawals from the aquifer in Mississippi 

rose 170 percent between 1999 and 2005 (D.E. Burt, 

U.S. Geological Survey, written commun., 2009) and 

decreased by 50 percent between 2005 and 2010 (D.E. Burt, 

U.S.Geological Survey, written commun., 2013). The large 

amount of water withdrawn in Mississippi from the aquifer 

probably contributed to lower water levels in southeastern 

Arkansas (Ackerman, 1987; Joseph, 1998; Schrader and 

Joseph, 2000; Yeatts, 2004; Pugh, 2010). 

NOT TO SCALE

WEST EAST

MISSISSIPPI RIVER VALLEY

ALLUVIAL AQUIFER

OUTCROP

AREA

OUTCROP

AREA

LOESS, SILT, SAND,GRAVEL DEPOSITS

UPPER CLAIBORNE AQUIFER

(Cockfield aquifer)

MIDDLE CLAIBORNE AQUIFER

LOWER WILCOX AQUIFER

MIDWAY

CONFINING UNIT MIDWAY

CONFINING UNIT

VICKSBURG–JACKSON CONFINING UNIT

MIDDLE CLAIBORNE CONFINING UNIT

LOWER CLAIBORNE CONFINING UNIT

LOWER CLAIBORNE AQUIFER

Geology modified from Arthur and Taylor (1990)

Generalized groundwater

flow direction

EXPLANATION

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

1975 1980 1985 1990 1995 2000 2005 2010

Year

0

2

4

6

8

10

12

14

16

18

20

22

Water use, in million gallons per day 

5.2

7.2

5.0

8.1

9.8 9.9

16.1

19.2

Data compiled from Halberg and Johnson (1977),

 Holland and Ludwig (1981), and Holland (1987,

 1993, 1999, 2004, 2007, Terrance W. Holland,

 U.S. Geological Survey, written commun., 2010) 

Figure 4. Water use from the Cockfield aquifer in southern 

Arkansas, 1975–2010.
Cockfield (Upper Claiborne) Aquifer 9

Potentiometric Surface

The potentiometric-surface map shows the altitude of the 

water surface in tightly cased wells screened in the Cockfield 

aquifer in the study area (fig. 5). Water-level data used to 

construct the map are shown in appendix 1.

The potentiometric surface of the Cockfield aquifer 

in 2012 shows the regional direction of groundwater flow 

generally is towards the east-southeast, except in areas of 

intense groundwater withdrawals, such as southwestern 

Ashley County where groundwater flows toward the town 

of Crossett. In southern Columbia County, a trough in the 

potentiometic surface exists, which locally alters the flow 

of groundwater. This trough may indicate the formation of a 

cone of depression. In northeastern Drew County and northern 

Chicot County, groundwater flow is towards the northeast, and 

in southeastern Lincoln County, groundwater flow is towards 

the east. The highest water-level altitude measured was 350 ft 

above NGVD 29 in central Columbia County. This elevated 

water-level altitude is the result of the well being located on 

a higher land-surface altitude in the outcrop area. The lowest 

water-level altitude measured was 40 ft above NGVD 29 in 

southeastern Lincoln County.

Water-Level Trends 

Water-Level Difference from 2006 to 2012

A water-level difference map for the Cockfield aquifer 

in the study area was constructed to spatially evaluate 

short-term (6 years) changes in water levels (fig. 6). The map 

was constructed using the difference between water-level 

measurements made in 2006 and 2012 in 42 wells (app. 2). 

Positive values, represented with blue, upward pointing 

triangles, indicate a rise in water levels between 2006 and 

2012; negative values, represented with red, downward 

pointing triangles, indicate a decline in water levels between 

2006 and 2012. The triangles are scaled in size to the relative 

value of rise or decline. The 2006 to 2012 water-level 

difference map indicates short-term changes and may not 

represent long-term trends. 

The 2006 to 2012 difference in water levels for the 

Cockfield aquifer ranged from 27.4 to -10.4 ft (fig. 6). The 

largest water-level rise was in Calhoun County, and the largest 

water-level decline was in Union County (app. 2). Of the 

42 wells, 13 wells had a rise in water levels, and the remaining 

29 wells had a decline in water levels from 2006 to 2012. 

Rises in water levels occurred in Ashley, Bradley, Calhoun, 

Chicot, Cleveland, Columbia, Drew, and Union Counties and 

ranged from 27.4 ft in Calhoun County to 0.2 ft in Bradley 

County. Declines in water levels ranged from -0.3 ft in 

Calhoun and Columbia Counties to -10.4 ft in Union County, 

and most were less than -5.0 ft. 

East of the Saline River, water levels declined in 12 of 

the 16 wells between 2006 and 2012. In Ashley County, 6 of 

the 7 wells had declines in water levels. Eleven of the 15 wells 

located between the Saline and Ouachita Rivers had declines 

in water levels, and 6 of the 11 wells west of the Ouachita 

River had declines in water levels for the period between 2006 

and 2012. 
Base modified from U.S. Geological Survey digital data Area enlarged ARKANSAS EXPLANATION Outcrop of the Cockfield Formation (modified from Hosman, 1988) General direction of groundwater flow Well completed in Cockfield aquifer—Number is water-level altitude. Letter, where present, corresponds to hydrograph in figure 7 Potentiometric contour—Shows altitude at which water level would have stood in tightly cased wells. Dashed where approximately located. Contour interval 20 feet. Datum is National Geodetic Vertical Datum of 1929 200 A 81 0 10 20 

0 10 20 30 40 KIL

91°30' 92°00' 92°30' 

93°00' 34°30' 34°00' 33°30' 140 160 180220 220 240260 280 300320 340 200 280 240 140 180260 260 120 160 200100 60 80 80 40 6080 40 99 

75 

66 95 61 84 98 84 81 88 194 192 230 199 153 222 308260 232 268 119 124 133 175 193 209 257 107 131 102 108 111 256 290 350 Crossett UNION DREWASHLEY 

GRANT ARKANS

DALLAS JEFFERSON COLUMBIA OUACHITA BRADLEY LINCOLN CALHOUN CLEVELAND 

A B C 

E F G H I J K L Ouachita River Saline RiverMoro Creek 

Figure 5. Potentiometric surface of the Cockfield aquifer in southern Arkansas, 2012.
Base modified from U.S. Geological Survey digital data

Area enlarged

ARKANSAS

0 10 20 0 10 20 30 40 KIL

91°30'

92°00'

92°30'

93°00'

34°30'

34°00'

33°30'

UNION

DREW

ASHLEY

GRANT ARKAN

DALLAS

JEFFERSON

COLUMBIA

OUACHITA

BRADLEY

LINCOLN

CALHOUN

CLEVELAND

Crossett

Ouachita River

Saline River

Moro Creek 

2.2*

Outcrop of Cockfield Formation (modified from Hosman, 1988)Well completed in Cockfield aquifer—Value is rise in water level from 2006 to 2012, in feet. Symbols are scaled to valueWell completed in Cockfield aquifer—Value is decline in water level from 2006 to 2012, in feet. Symbols are scaled to value

EXPLANATION

-1.7

-0.9

-1.2

-0.6

-8.0

-1.4

-1.9

-4.0

-5.6

-2.3

-2.0

-0.3

-0.

-3.

-1.3

-0.3

-3.0

-3.1

-0.9

-5.0

-7.3

-5.7

-3.6

-10.4

0.6

-5.4

-0.4 -1.7 -1.6

0.9

3.4

4.4

2.2

27.4

0.2

9.6

1.5

18.5

3.2

4.7

Figure 6. Water-level difference for the Cockfield aquifer in southern Arkansas, 2006–12.
12 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Long-Term Hydrographs

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

trends for the Cockfield aquifer in Arkansas. The first method 

was to use the hydrograph for a well with a minimum of 20 

years of record and plot the water levels in relation to time. 

Hydrographs of selected wells are shown in figure 7A–L. The 

selected well locations are plotted on figure 5. The second 

method evaluated the annual rise or decline in water levels 

over a 20-year or more period through 2012, using the line 

of best fit (Y = MX + B) and residual (R2). The coefficient of 

determination (R2) is a measure of how close the data are to 

the line of best fit. 

Hydrographs for 32 wells with historical water-level data 

in the Cockfield aquifer with a minimum of 20 years of waterlevel data were constructed and evaluated. The annual rise or 

decline in water levels was aggregated by county. The values 

for the range, mean, and median of water-level change were 

computed for each county (table 2). 

Analysis of selected hydrographs is divided into 

three geographic regions: the area east of the Saline River 

(Ashley, Chicot, Desha, Drew, Lincoln, and part of Cleveland 

Counties), the area between the Saline and Ouachita Rivers 

(Bradley, Calhoun, and part of Cleveland Counties), and 

the area west of the Ouachita River (Columbia and Union 

Counties). The area east of the Saline River is confined by 

the overlying Jackson Group. The central area between the 

Saline and Ouachita Rivers is a mixed area, the northern part 

is an outcrop area, the eastern part is confined by the Jackson 

Group, and the southern part underlies Quaternary-age terrace 

deposits. The area west of the Ouachita River is in an outcrop 

area with overlying Quaternary-age terrace deposits.

Hydrographs for wells located in Ashley, Chicot, and 

Lincoln Counties, east of the Saline River and screened 

within the confined part of the Cockfield aquifer, are shown 

in figures 7A–E. These hydrographs indicate changes in 

water levels ranging from a rise of approximately 0.5 ft (well 

18S02W25ABB3, fig. 7D) to a decline of approximately 57 ft 

(well 10S05W06CAC1, fig. 7E) over the period of record.

Hydrographs for wells located in Bradley, Calhoun, and 

part of Cleveland Counties, the area between the Saline and 

Ouachita Rivers, are shown in figures 7F–I. These wells are 

screened in confined and unconfined areas of the Cockfield 

aquifer. The hydrographs indicate rises and declines in water 

levels ranging from a decline of approximately 23 ft (well 

14S10W31DBA1, fig 7F) to a rise of approximately 1 ft (well 

15S12W11CAB1, fig. 7G) over the period of record. 

Hydrographs for wells located in Union and Columbia 

Counties, the area west of the Ouachita River, are shown in 

figures 7J–L. The hydrographs indicate rises and declines 

over the period of record from a decline of approximately 5 ft 

(well 17S16W33BBA2, fig. 7K) to a rise of approximately 2 ft 

(well 17S13W17DDC1, fig. 7J).

Hydrographs for the 32 wells with historical waterlevel data were evaluated using linear regression to calculate 

the annual rise or decline for each well, and the data were 

aggregated by county and statistically evaluated for the range, 

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

(table 2). Cleveland and Lincoln Counties had only one well 

with a minimum of 20 years of record. Annual rise or decline 

calculations associated with wells with more than 20 years of 

record in Ashley and Chicot Counties indicated a decline in 

water levels. Bradley, Calhoun, Columbia, and Union Counties 

indicate rising and declining water levels. The mean annual 

water-level rise or decline for Calhoun County was 0.00 ft/yr 

or unchanged. The mean annual water-level data for Ashley, 

Bradley, Chicot, Cleveland, Columbia, Lincoln, and Union 

Counties show declines ranging from -0.02 to -1.10 ft/yr. 
Cockfield (Upper Claiborne) Aquifer 13

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

80

85

90

95

100

105

110

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

50

60

70

80

90

100

110

Water level, in feet aboveNational 

Geodetic Vertical Datum of 1929

A. ASHLEY COUNTY 17S04W10BCD2

B. ASHLEY COUNTY 18S08W04BBC1

NO DATA

NO DATA

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.
14 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

50

60

70

80

90

100

110

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

50

60

70

80

90

100

110

Water level, in feet above National 

Geodetic Vertical Datum of 1929

D. CHICOT COUNTY 18S02W25ABB3

C. ASHLEY COUNTY 19S05W12CAC1

NO DATA

NO DATA

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued
Cockfield (Upper Claiborne) Aquifer 15

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

30

40

50

60

70

80

90

100

110

Water level , in feet above National 

Geodetic Vertical Datum of 1929 

90

100

110

120

130

140

Water level, in feet above National 

Geodetic Vertical Datum of 1292 

80

F. BRADLEY COUNTY 14S10W31DBA1

E. LINCOLN COUNTY 10S05W06CAC1

NO DATA

NO DATA

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 Aquifer and the Wilcox Aquifer, Arkansas, 2012

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

100

110

120

130

140

150

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

120

130

140

150

160

170

180

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

90

G. BRADLEY COUNTY 15S12W11CAB1

H. CALHOUN COUNTY 14S13W29ADA1

NO DATA

NO DATA

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued
Cockfield (Upper Claiborne) Aquifer 17

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

190

200

210

220

230

240

250

120

130

140

150

160

170

180

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

J. UNION COUNTY 17S13W17DDC1

I. CLEVELAND COUNTY 11S11W23BBD1

NO DATA

NO DATA

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 Aquifer and the Wilcox Aquifer, Arkansas, 2012

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

200

210

220

230

240

250

260

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

290

310

330

350

370

390

410

Water level, in feet above National 

Geodetic Vertical Datum of 1929

K. UNION COUNTY 17S16W33BBA2

L. COLUMBIA COUNTY 17S20W35BBD1

NO DATA

NO DATA

Figure 7. Water-level hydrographs for selected wells completed in the Cockfield aquifer in southern Arkansas.—Continued
Wilcox (Lower Wilcox) Aquifer 19

Wilcox (Lower Wilcox) Aquifer

Hydrogeologic Setting

The Wilcox aquifer, in northeastern and southern 

Arkansas, is composed of the Wilcox Group and is distributed 

throughout the Mississippi Embayment. The Wilcox Group 

is part of a syncline approximately centered beneath the 

Mississippi River that plunges to the south-southeast (fig. 3). 

In the northeast part of Arkansas, the Wilcox Group is 

composed of three units: the Flour Island Formation, the Fort 

Pillow Sand, and the Old Breastworks Formation; in southern 

Arkansas, the formation is undifferentiated (table 1). In central 

Arkansas, the Wilcox aquifer is not extensively used, and 

water-level data are not sufficient to determine potentiometric 

surfaces. Because of the discontinuous nature of water-level 

data, the potentiometric-surface map of the Wilcox aquifer is 

divided into two areas—one in northeastern Arkansas and the 

second in southern Arkansas. 

The Wilcox Group is composed of thin interbedded layers 

of lignitic sand and clays in most of the northeastern area. The 

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

Craighead, and Greene 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 200 ft or more in thickness (Petersen and others, 

1985) in the middle to lower part of the unit which is referred 

to as the “1,400-foot sand” (Ryling, 1960; Plebuch, 1961) 

or the “lower Wilcox aquifer” (Hosman and others, 1968). 

In northeastern Arkansas, the Wilcox aquifer is overlain by 

a clay bed of the Wilcox Group and is underlain by a clay 

bed of the Wilcox Group or the Midway Group. Part of 

the Wilcox aquifer, within Crowleys Ridge, is perched and 

hydrologically separated from the aquifer in the surrounding 

Mississippi Alluvial Plain (fig. 1) (Petersen and others, 

1985). 

The Wilcox Group is composed of interbedded layers 

of clay, sandy clay, sand, and lignite in the southern area. 

The Wilcox Group overlies the Midway Group and underlies 

Quaternary-age terrace deposits and alluvium or crops out. 

The outcrop is generally thin and discontinuous over large 

areas. Downslope from the outcrop, the Wilcox Group 

becomes thicker, ranging from a few feet in the outcrop areas 

to about 750 ft at the center of the syncline (Albin, 1964). 

Recharge to the Wilcox aquifer in the northeastern area 

occurs through infiltration of precipitation in outcrop areas 

along the western side of Crowleys Ridge. Discharge occurs 

mainly through well withdrawals (Westerfield, 1994). The 

depth of wells in this area ranged from 462 ft in Greene 

County to 1,885 ft in Lee County. Well yield ranged from 

100 to 2,000 gal/min (Schrader and Joseph, 2000). 

Recharge to the Wilcox aquifer in the southern area 

occurs through infiltration of precipitation in outcrop areas 

and inflow from overlying alluvial and terrace deposits. 

Discharge occurs from flows into overlying formations, into 

streams in the outcrop area, and to wells (Westerfield, 1994). 

Well depths ranged from 14 ft within the recharge area in 

Hempstead County to 533 ft in Ouachita County. Well yields 

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

Table 2. Range, mean, and median of annual rise or decline in water level by county for wells with 20 or more years of record 

completed in the Cockfield aquifer in Arkansas.

[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 of 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

Ashley 6 -0.55 to -0.11 -0.32 -0.31 0.08 to 0.90

Bradley 4 -0.51 to 0.40 -0.04 -0.03 0.04 to 0.97

Calhoun 6 -0.11 to 0.22 0.00 -0.01 0.07 to 0.70

Chicot 3 -0.33 to -0.11 -0.19 -0.15 0.40 to 0.70

Cleveland 1 -0.04 -0.04 -0.04 0.16

Columbia 5 -0.11 to 0.04 -0.02 0.01 0.01 to 0.26

Lincoln 1 -1.10 -1.10 -1.10 0.84

Union 6 -0.18 to 0.11 -0.03 -0.02 0.001 to 0.85
20 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Hydraulic Properties 

Values for specific capacity and transmissivity vary 

within the Wilcox aquifer. Pugh (2008) reported the following 

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

pump tests. 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 and a mean of 10,700 ft2/d. Hydraulic 

conductivity values could not be determined based on well 

tests completed in the Wilcox aquifer. Pugh (2008) calculated 

an estimated hydraulic conductivity value of 9.7 ft/d for the 

Wilcox aquifer by dividing the mean transmissivity value 

(10,700 ft2/d) by the maximum aquifer thickness (1,100 ft).

Water Use

The majority of water withdrawals from the Wilcox 

aquifer were for industrial and public supply. Withdrawals 

for agricultural, commercial, and domestic use were less than 

those for industrial and public supply but important locally. 

Reported withdrawals from the Wilcox aquifer in Arkansas 

totaled 36.5 Mgal/d during 2010 (fig. 8), most of which 

occurred in the northeastern study area (Terrance W. Holland, 

U.S. Geological Survey, written commun., 2012). Withdrawals 

from 1975 through 2005 remained relatively constant, between 

21.0 Mgal/d and 27.0 Mgal/d, with the exception of 1990 and 

1995 when 30.9 Mgal/d and 41.0 Mgal/d were withdrawn, 

respectively. The rise in water use from 1990 to 1995 was 

attributed to withdrawals by a power generation plant that was 

operating during this time period (Terrance W. Holland, U.S. 

Geological Survey written commun., 2009). The rise in water 

use from 2005 to 2010 was attributed to increased withdrawals 

for industry, irrigation, and public supply (Aaron L. Pugh, 

U.S. Geological Survey written commun., 2014). In the 

northeastern area, the majority of water withdrawn from the 

Wilcox aquifer was for public supply. The aquifer is also an 

important source of water locally for agricultural, commercial, 

and domestic use. In the southern area, the majority of water 

withdrawn from the aquifer was for domestic use.

Potentiometric Surface 

Two potentiometric-surface maps, one for the 

northeastern area and one for the southern area, show the 

altitude of the water surface in the Wilcox aquifer (figs. 9 

and 10). The maps were constructed using water-level data 

collected in February and March 2012 from 47 wells; 31 wells 

in the northeastern area (app. 3) and 16 wells in the southern 

area (app. 4). 

The direction of groundwater flow in the Wilcox aquifer 

in the northeastern area in 2012 (fig. 9) was towards the southsouthwest except for some areas immediately adjacent to the 

Mississippi River where the flow was more eastward towards 

the river. Groundwater withdrawals have altered the direction 

of flow near West Memphis (Joseph, 1998). The highest waterlevel altitude was 219 ft in northern Mississippi County, and 

the lowest water-level altitude was 123 ft near West Memphis 

in Crittenden County. In Greene County, a water-level 

altitude of 182 ft was measured near Crowleys Ridge. Within 

Crowleys Ridge, the waters of the Wilcox aquifer are perched 

at higher altitudes than the surrounding Mississippi Alluvial 

Plain and have too few control points for contouring.

The direction of groundwater flow in the southern area 

(fig. 10) was generally towards the southwest in the northern 

part. The direction of groundwater flow in the southern part 

was in all directions because of two cones of depression and 

two water-level mounds. The cones of depression are located 

in southeastern Clark County and central Nevada County, 

and the water-level mounds are located in Hot Spring County 

and Hempstead County (fig. 10). The water-level mounds are 

the result of the higher land-surface altitudes in the outcrop 

area. Groundwater flow toward the cone of depression in 

southeastern Clark County was generally from the north, 

south, and west; water flows toward the cone of depression in 

Nevada County from all directions. Groundwater flow from 

the water-level mound in eastern Hot Spring County was 

generally to the north, south, and east; groundwater flows 

from the water-level mound in southern Hempstead County 

to the south, east, and west. The highest water-level altitude 

measured was 394 ft at the centers of the water-level mounds 

in eastern Hot Spring County and southwestern Hempstead 

County. The lowest water-level altitude measured was 145 ft 

at the center of the cone of depression in Clark County. 

1975 1980 1985 1990 1995 2000 2005 2010

Year

Water use, in million gallons per day 

0

5

10

15

20

25

30

35

40

45

50

24.3 25.7

21.0

30.9

41.0

22.2

27.0

36.5

Data compiled from Halberg and Johnson (1977),

 Holland and Ludwig (1981), and Holland (1987,

 1993, 1999, 2004, 2007, Terrance W. Holland,

 U.S. Geological Survey, written commun., 2010) 

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

1975–2010.
Wilcox (Lower Wilcox) Aquifer 21

Paragould

West

Memphis

CLAY

CROSS

POINSETT

GREENE

CRAIGHEAD

ST. FRANCIS

LEE

CRITTENDEN

MISSISSIPPI

Area enlarged

ARKANSAS

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 13

EXPLANATION

180

!

200 M

0 10 20 MILES

0 10 20 KILOMETERS

35°00’

36°00’

90°00’

91°00’

90° 30’

35° 30’

36° 30’

210

200

190

180

170

160

140

130

150

 170

136

127

136

143

141

145

135

182

183

179 178

219

206

204

191

189

187

205

200

193 197

196

197

205

203

148 176

123

166

165

163

M

N

O

P

Q

R

S

Figure 9. Potentiometric surface of the Wilcox aquifer in northeastern Arkansas, 2012.
22 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

CLARK

DALLAS

NEVADA

OUACHITA

HEMPSTEAD

HOT SPRING

Ouachita River

Little Missouri River

Area enlarged

ARKANSAS

EXPLANATION

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 14

 

180

T !

145

0 10 20 MILES

0 10 20 KILOMETERS

34°30'

93°30'

34°00'

92°30'

33°30'

93°00'

280

300

260

240

320

220

340

200

360

180

380

160

260

340

380

260

280

320

240

300

360

360

340

334

341

394 345

329

282

145

210

232

267

394

342

313

319

251

242

W

V

U

T

X

Figure 10. Potentiometric surface of the Wilcox aquifer in southern Arkansas, 2012.
Wilcox (Lower Wilcox) Aquifer 23

Water-Level Trends 

Water-Level Difference from 2006 to 2012

Water-level difference maps (figs. 11 and 12) for the 

Wilcox aquifer in Arkansas were constructed using 47 waterlevel measurements made during 2006 and 2012. Difference 

values were obtained from water levels measured in 31 wells 

in the northeastern area of the Wilcox aquifer and 16 wells 

measured in the southern area.

The 2006 to 2012 difference in water levels for the 

Wilcox aquifer in the northeastern area (fig. 11, app. 5) ranged 

from 22.0 to -17.9 ft. The largest rise in water levels occurred 

in Crittenden County, and the largest decline was in Lee 

County. Twenty-one wells in the northeastern area had rising 

water levels, and 10 wells had declining water levels. Wells 

in the northern part of this area had rising water levels, and 

wells in the southern part had declining water levels. In the 

central part of the area, water levels in all wells measured in 

Craighead County rose, and water levels rose in all but one 

well in Poinsett County and one well in Mississippi County. 

Water levels in wells in Crittenden County rose and declined. 

All water levels in wells measured in Lee and St. Francis 

Counties declined.

The 2006 to 2012 difference in water levels for the 

Wilcox aquifer in the southern area (fig. 12, app. 6) ranged 

from 18.1 to -4.2 ft. The largest rise and the largest decline in 

water levels occurred in Nevada County. Water-levels rose in 

12 wells in the southern area and declined in 4 wells. Water 

levels in wells in the northern area rose and declined in wells 

in the central part of the area (Clark County). Water levels in 

wells in the southern part of the area rose and declined. 

Long-Term Hydrographs

Hydrographs for 12 wells with a minimum of 20 years 

of record (7 wells in the northeastern area and 5 wells in the 

southern area) were used to evaluate long-term trends of the 

Wilcox aquifer. The well locations for the corresponding 

hydrographs are plotted on figures 9 and 10 and designated 

by the letters M–X positioned next to the well. These 

hydrographs are shown on figure 13 (northeastern, area) and 

figure 14 (southern area). Hydrographs for 36 wells (24 wells 

in the northeastern area of the Wilcox aquifer and 12 wells 

in the southern area) were used to calculate the annual rise 

or decline in water levels over a period of 20 or more years 

using linear regression. The annual rise or decline in water 

levels was aggregated by county, and values for the range, 

mean, and median of water-level change were computed for 

each county (table 3). The summary for Greene, Lee, and St. 

Francis Counties was for a single well. 

Selected hydrographs for the northeastern area 

(figs. 13M–S) all show declining water levels. Waterlevel changes in selected wells ranged from a decline of 

approximately 23 ft in well 14N07E17DCB1 (fig. 7M) 

in Craighead County to a decline of approximately 60 ft 

in well 04N06E21BAD2 (fig. 7S) in St. Francis County. 

Hydrographs in the southern area (figs. 14T–X) show rising 

and declining water levels. Water-level changes in selected 

wells ranged from a decline of approximately 20 ft in well 

10S18W10DDB1 (fig. 7T) in Clark County to a rise of 

approximately 14 ft in well 14S22W19AAA1 (fig. 7X) in 

Nevada County.

Linear regression analysis of long-term hydrographs 

was used to determine the mean annual water-level rise 

and decline in the Wilcox aquifer in the northeastern and 

southern areas of Arkansas. In the northeastern area, the 

mean annual water level declined in all seven counties. The 

mean annual declines ranged from -0.55 ft/yr in Craighead 

County to -1.46 ft/yr in St. Francis County. Greene, Lee, and 

St. Francis Counties had only one well with a minimum of 

20 years of record. 

In the southern area, the annual rise or decline 

calculations for wells with over 20 years of record indicate 

rising and declining water levels in Clark, Hot Spring, and 

Nevada Counties. The mean annual water level declined in 

all counties except Hot Spring County. 
24 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Paragould

West

Memphis

CLAY

CROSS

POINSETT

GREENE

CRAIGHEAD

ST. FRANCIS

LEE

CRITTENDEN

MISSISSIPPI

Area enlarged

ARKANSAS

*

0.5

*

-3.4

Crowleys Ridge (from Hosman, 1988)

Well completed in Wilcox aquifer, northeastern

 Arkansas—Value is rise in water level from 

 2006 to 2012, in feet. Symbols are scaled to 

 value

Well completed in Wilcox aquifer, northeastern 

 Arkansas—Value is decline in water level from

 2006 to 2012, in feet. Symbols are scaled to 

 value

EXPLANATION

0 10 20 MILES

0 10 20 KILOMETERS

35°00’

36°00’

90°00’

91°00’

90° 30’

35° 30’

36° 30’

Mississippi River

-0.1

-0.6

-4.5

-5.0

-5.0

-7.3

-5.3

-17.9

-1.2

-3.7

6.5

3.4

0.8

1.3

3.1

0.6 1.7

2.2

7.6

2.9 7.5

2.5

1.5

1.6

6.8

11.0

22.0

15.6

17.2

16.1

3.7

Figure 11. Water-level difference for the Wilcox aquifer in northeastern Arkansas, 2006–12.
Wilcox (Lower Wilcox) Aquifer 25

CLARK

DALLAS

NEVADA

OUACHITA

HEMPSTEAD

HOT SPRING

Ouachita River

Little Missouri River

Area enlarged

ARKANSAS

Outcrop of Wilcox Group (from Hosman, 1988)

Well completed in Wilcox aquifer, southern Arkansas—

 Value is rise in water level from 2006 to 2012, in feet. Symbols 

 are scaled to value

Well completed in Wilcox aquifer, southern Arkansas—

 Value is decline in water level from 2006 to 2012, in feet. 

 Symbols are scaled to value

EXPLANATION

-1.7

3.3

0 10 20 MILES

0 10 20 KILOMETERS

34°30'

93°30'

34°00'

92°30'

33°30'

93°00'

7.9

0.4

1.5

3.3

1.8

0.2

0.7 1.6

12.0

18.1

4.6

0.8 -4.2

-2.1

-1.7

-3.0

Figure 12. Water-level difference for the Wilcox aquifer in southern Arkansas, 2006–12.
26 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

180

190

200

210

220

230

240

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

150

160

170

180

190

200

210

Water level, in feet above National 

Geodetic Vertical Datum of 1929

M. CRAIGHEAD COUNTY 14N07E17DCB1

N. CRITTENDEN COUNTY 08N06E33CBD1

NO DATA

NO DATA

Figure 13. Water-level hydrographs for selected wells completed in the Wilcox aquifer in northeastern Arkansas.
Wilcox (Lower Wilcox) Aquifer 27

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

160

170

180

190

200

210

220

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

130

140

150

160

170

180

190

200

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

O. GREENE COUNTY 17N06E31DCB1

P. LEE COUNTY 01N04E09DCC1

NO DATA

Figure 13. Water-level hydrographs for selected wells completed in the Wilcox aquifer in northeastern Arkansas.—Continued
28 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

180

190

200

210

220

230

240

Water level, in feet above National 

Geodetic Vertical Datum of 1929

170

180

190

200

210

220

230

Water level, in feet above National 

Geodetic Vertical Datum of 1929

Q. MISSISSIPPI COUNTY 15N09E31ACD1

R. POINSETT COUNTY 12N05E13BBB1

NO DATA

NO DATA

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

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

120

130

140

150

160

170

180

190

200

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

S. ST. FRANCIS COUNTY 04N06E21BAD2

NO DATA

Figure 13. Water-level hydrographs for selected wells completed in the Wilcox aquifer in northeastern Arkansas.—Continued
30 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

170

180

190

200

210

220

230

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

110

120

130

140

150

160

170

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

U. CLARK COUNTY 09S18W20CBB1

T. CLARK COUNTY 10S18W10DDB1

NO DATA

NO DATA

Figure 14. Water-level hydrographs for selected wells completed in the Wilcox aquifer in southern Arkansas. 
Wilcox (Lower Wilcox) Aquifer 31

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

300

310

320

330

340

350

360

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

310

320

330

340

350

360

370

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

W. HEMPSTEAD COUNTY 14S24W29BCA1

V. HOT SPRING 04S16W20CBB1 

NO DATA

NO DATA

Figure 14. Water-level hydrographs for selected wells completed in the Wilcox aquifer in southern Arkansas.—Continued
32 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013

Year

270

280

290

300

310

320

330

340

Water level, in feet above National 

Geodetic Vertical Datum of 1929 

X. NEVADA COUNTY 14S22W19AAA1

NO DATA

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

Table 3. Range, mean, and median of annual rise or decline in water level by county for wells with 20 or more years of record 

completed in the Wilcox aquifer in Arkansas.

[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 of 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

Northeastern area

Craighead 4 -0.66 to -0.43 -0.55 -0.55 0.67 to 0.92

Crittenden 8 -1.57 to -0.88 -1.15 -1.11 0.78 to 0.98

Greene 1 -0.66 -0.66 -0.66 0.54

Lee 1 -1.31 -1.31 -1.31 0.97

Mississippi 6 -0.95 to -0.55 -0.73 -0.68 0.70 to 0.91

Poinsett 3 -0.91 to -0.80 -0.85 -0.84 0.76 to 0.93

St. Francis 1 -1.46 -1.46 -1.46 0.97

Southern area

Clark 3 -0.55 to 0.18 -0.15 -0.07 0.30 to 0.97

Hempstead 3 -0.62 to -0.07 -0.26 -0.07 0.05 to 0.67

Hot Spring 2 -0.01 to 0.11 0.05 0.05 0.01 to 0.88 

Nevada 4 -0.11 to 0.03 -0.03 -0.04 0.00 to 0.16
Summary 33

Summary

The Cockfield aquifer located in southern Arkansas is 

composed of Eocene-age sand beds found near the base of the 

Cockfield Formation of Claiborne Group. The Wilcox aquifer 

located in northeastern and southern Arkansas, is composed 

of Paleocene-age sand beds found in the middle to lower part 

of the Wilcox Group. The Cockfield and Wilcox aquifers are 

primary sources of groundwater. In 2010, withdrawals from 

the Cockfield aquifer in Arkansas totaled 19.2 (Mgal/d) and 

withdrawals from the Wilcox aquifer totaled 36.5 Mgal/d. 

Water levels were measured at 43 wells completed in 

the Cockfield aquifer and 47 wells completed in the Wilcox 

aquifer in February and March 2012. Measurements from 

2012 are presented as potentiometric-surface maps and in 

combination with measurements from 2006 as water-level 

difference maps. Trends in water-level change over time 

within the Cockfield and Wilcox aquifers were determined 

using the water-level difference maps and selected well 

hydrographs. Hydrogaphs for selected wells were constructed 

using 20 or more years of historical water-level data.

The Cockfield aquifer study area in southern Arkansas 

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

west by the area that contains outcrops and subcrops of the 

Cockfield Formation. The northern boundary of the Cockfield 

aquifer study area is defined by the area that contains 

observation wells completed in the Cockfield aquifer and the 

southern boundary is the Louisiana State line. The Wilcox 

aquifer study area in northeastern Arkansas is bounded on the 

east by the Mississippi River and on the north by the Missouri 

State line. The southern and western boundaries are defined by 

areas containing observation wells completed in the Wilcox 

aquifer or by outcrop areas on or near Crowleys Ridge. The 

Wilcox aquifer study area in southern Arkansas is defined by 

observation wells completed in the Wilcox aquifer or by areas 

that contain outcrops of the Wilcox Group, or both. 

The potentiometric surface of the Cockfield aquifer 

shows the regional direction of groundwater flow was 

generally toward the east-southeast, except in areas of intense 

groundwater withdrawals such as southwestern Ashley 

County, where groundwater flows toward the town of Crossett. 

In southern Columbia County, a trough in the potentiometic 

surface exists, which locally alters the flow of groundwater. 

The highest water-level altitude measured was 350 feet (ft) 

above National Geodetic Vertical Datum of 1929 (NGVD 29) 

in central Columbia County. The lowest water-level altitude 

measured was 40 ft above NGVD 29 in southeastern Lincoln 

County.

The 2006 to 2012 difference in water levels for the 

Cockfield aquifer ranged from 27.4 to -10.4 ft. The largest 

water-level rise was in Calhoun County, and the largest waterlevel decline was in Union County. Of the 42 wells, 13 wells 

had a rise in water levels, and the remaining 29 wells had a 

decline in water levels from 2006 to 2012.

Analysis of selected hydrographs was divided into 

three geographic regions: the area east of the Saline River 

(Ashley, Chicot, Desha, Drew, Lincoln, and part of Cleveland 

Counties), the area between the Saline and Ouachita Rivers 

(Bradley, Calhoun, and part of Cleveland Counties), and 

the area west of the Ouachita River (Columbia and Union 

Counties). Hydrographs for wells located east of the Saline 

River and screened within the confined part of the Cockfield 

aquifer indicated changes in water levels that range from a 

rise of approximately 0.5 ft to a decline of approximately 

57 ft over the period of record.

Hydrographs for wells located in the area between the 

Saline and Ouachita Rivers were screened in confined and 

unconfined areas of the Cockfield aquifer. The hydrographs 

indicate rises and declines in water levels that ranged from 

a rise of approximately 1 ft to a decline of approximately 

23 ft over the period of record. Hydrographs for wells 

located in the area west of the Ouachita River indicated 

rises and declines in water levels that ranged from a rise of 

approximately 2 ft to a decline of approximately 5 ft over the 

period of record.

Hydrographs for the 32 wells with historical water-level 

data in the Cockfield aquifer were evaluated using linear 

regression to calculate the annual rise or decline for each 

well and the data were aggregated by county and statistically 

evaluated for the range, mean, and median of water-level 

change in each county. Bradley, Calhoun, Columbia, and 

Union Counties indicate rising and declining water levels. 

The mean annual water-level rise or decline for Calhoun 

County was 0.00 ft/yr or unchanged. The mean annual waterlevel data for Ashley, Bradley, Chicot, Cleveland, Columbia, 

Lincoln, and Union Counties show declines ranging from 

-0.02 to -1.10 ft/yr.

Two potentiometric-surface maps, one for the 

northeastern area and one for the southern area, were 

constructed to show the altitude of the water surface in the 

Wilcox aquifer. The maps were constructed using water-level 

data collected in February and March 2012 from 47 wells; 

31 wells in the northeastern area and 16 wells in the southern 

area. The direction of groundwater flow in the northeastern 

area was generally towards the south-southwest except 

for some areas immediately adjacent to the Mississippi 

River where the flow was more eastward towards the river. 

The highest water-level altitude was 219 ft in northern 

Mississippi County, and the lowest water-level altitude was 

123 ft near West Memphis in Crittenden County. In Greene 

County, a water-level altitude of 182 ft was measured near 

Crowleys Ridge. Within Crowleys Ridge, water levels in the 

Wilcox aquifer were perched at higher water-level altitudes 

than the aquifer in the surrounding Mississippi Alluvial Plain. 

The direction of groundwater flow in the southern area was 

generally towards the southwest in the northern part. The 

direction of groundwater flow in the southern part was in 

all directions because of two cones of depression and two 

water-level mounds. The water-level mounds are the result 

of the higher land-surface altitudes in the outcrop area. The 

highest water-level altitude measured was 394 ft at the center 

of the water-level mounds in eastern Hot Spring County 
34 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

and southwestern Hempstead County. The lowest water-level 

altitude measured was 145 ft at the center of the cone of 

depression in Clark County. 

Water-level difference maps for the Wilcox aquifer in 

Arkansas were constructed using 47 water-level measurements 

made during 2006 and 2012. Difference values were obtained 

from water levels measured in 31 wells in the northeastern 

area of the Wilcox aquifer and 16 wells measured in the 

southern area. The difference in water levels for the Wilcox 

aquifer in the northeastern area ranged from 22.0 ft to -17.9 ft. 

The largest rise in water levels occurred in Crittenden County, 

and the largest decline was in Lee County. Twenty-one wells 

had rising water levels, and 10 wells had declining water 

levels. The difference in water levels for the Wilcox aquifer 

in the southern area ranged from 18.1 ft to -4.2 ft. The largest 

rise and the largest decline in water levels occurred in Nevada 

County. Twelve wells had rising water levels, and 4 wells had 

declining water levels.

Hydrographs for the northeastern area showed declining 

water levels. Water-level changes in selected wells ranged 

from a decline of approximately 23 ft to a decline of 

approximately 60 ft. Hydrographs in the southern area showed 

declining and rising water levels. Water-level changes in 

selected wells ranged from a rise of approximately 14 ft to a 

decline of approximately 20 ft.

Linear regression analysis of long-term hydrographs was 

used to determine the mean annual water-level rise and decline 

in the Wilcox aquifer in the northeastern area and southern 

area of Arkansas. In the northeastern area, the mean annual 

water level declined in all seven counties. The mean annual 

declines ranged from -0.55 ft/yr in Craighead County to -1.46 

ft/yr in St. Francis County. 

In the southern area, the annual rise or decline 

calculations for wells with over 20 years of record indicated 

rising and declining water levels in Clark, Hot Spring, and 

Nevada Counties. The mean annual water level declined in all 

counties except Hot Spring County. 

This is the sixth in a series of triennial reports discussing 

the potentiometric surfaces of the Cockfield and Wilcox 

aquifers. This report and the previous five reports were 

prepared in cooperation with the Arkansas Natural Resources 

Commission and the Arkansas Geological Survey.

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Appendixes

Appendix 1 39

Appendix 1. Water-level data collected during February 2012 from wells completed in the Cockfield aquifer in southern Arkansas.—

Continued

[Horizontal datum is North America Datum of 1983; NGVD 29, National Geodetic Vertical Datum of 1929; Letters in parentheses correspond to well locations 

in figure 5 and well hydrographs in figure 7; --, missing data]

Station name

Latitude 

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

Water-level 

altitude 

(feet above 

NGVD 29)

Depth to water 

(feet below 

land-surface 

datum)

Land-surface 

datum 

(feet above 

NGVD 29)

Well depth 

(feet)

Date of 

measurement

Ashley County

15S04W26CBC1 332144 912932 88 40.36 128 409 2/24/2012

17S04W10BCD2 (A) 331417 913030 81 43.58 125 340 2/24/2012

17S04W10CBA1 331406 913033 84 41.34 125 360 2/24/2012

17S06W07ADA1 331442 914510 98 76.43 174 426 2/24/2012

18S04W19DAA2 330710 913247 83 32.61 116 356 2/24/2012

18S08W04BBC1 (B) 331038 915627 61 87.62 149 314 2/24/2012

19S05W12CAC1 (C) 330336 913425 81 34.40 115 320 2/24/2012

Bradley County

12S10W10BCA1 334108 920807 102 125.02 227 425 2/23/2012

12S10W30CAC1 333815 921046 238 2.07 240 58 2/23/2012

14S10W31DBA1 (F) 332658 921025 95 98.12 193 349 2/23/2012

14S11W35CAB1 332656 921251 111 79.03 190 320 2/23/2012

14S11W35DAC1 332650 921233 107 67.32 174 345 2/23/2012

15S12W11CAB1 (G) 332536 921858 131 23.76 155 225 2/23/2012

16S11W11ACA1 332027 921223 109 32.39 141 140 2/23/2012

Calhoun County

11S13W15BBC1 334560 922534 257 53.44 310 70 2/23/2012

13S13W09CBD1 333555 922638 193 38.63 323 147 2/23/2012

13S13W15DBA1 333517 922520 209 22.78 232 122 2/23/2012

14S13W11CAC1 333045 922451 175 29.89 205 105 2/22/2012

14S13W29ADA1 (H) 332829 922722 133 27.22 160 81 2/22/2012

14S13W29DAC1 332815 922729 124 14.69 139 − 2/22/2012

14S14W21ACB1 332931 923249 119 12.87 132 160 2/22/2012

Chicot County

13S03W26BBB1 333247 912301 66 72.96 139 442 2/27/2012

16S02W04BAC1 332027 911857 86 38.98 125 330 2/27/2012

18S02W25ABB3 (D) 330640 911541 91 44.48 135 322 2/27/2012

18S03W14CCC1 330731 912319 83 15.32 98 320 2/27/2012

Cleveland County

09S10W17CDD1 335534 920942 268 2.49 270 361 2/23/2012

11S11W23BBD1 (I) 334449 921258 232 42.93 275 148 2/23/2012

Columbia County

17S20W35BBD1 (L) 331313 930914 350 10.52 361 − 2/22/2012

19S20W34ADC1 330233 930958 290 22.71 313 40 2/22/2012

19S21W17CBB1 330520 931857 260 46.16 306 55 2/22/2012

19S21W35ADC1 330247 931513 256 0.37 256 30 2/22/2012

19S22W36DBB1 330245 932034 308 43.43 351 69 2/22/2012

Desha County

12S03W30ADC1 333747 912611 75 78.54 153 280 2/27/2012

13S02W08CAA1 333504 911921 73 74.29 147 515 2/27/2012

Appendix 1. Water-level data collected during February 2012 from wells completed in the Cockfield aquifer in southern Arkansas.

[Horizontal datum is North America Datum of 1983; NGVD 29, National Geodetic Vertical Datum of 1929; Letters in parentheses correspond to well locations in 

figure 5 and well hydrographs in figure 7; --, missing data]

Appendix 1
40 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Appendix 1. Water-level data collected during February 2012 from wells completed in the Cockfield aquifer in southern Arkansas.—

Continued

[Horizontal datum is North America Datum of 1983; NGVD 29, National Geodetic Vertical Datum of 1929; Letters in parentheses correspond to well locations 

in figure 5 and well hydrographs in figure 7; --, missing data]

Station name

Latitude 

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

Water-level 

altitude 

(feet above 

NGVD 29)

Depth to water 

(feet below 

land-surface 

datum)

Land-surface 

datum 

(feet above 

NGVD 29)

Well depth 

(feet)

Date of 

measurement

Drew County

14S06W21BDC1 332846 914339 99 117.19 216 − 2/24/2012

11S05W35DDB1 334216 913438 60 119.60 180 500 2/27/2012

Lincoln County

10S05W06CAC1 (E) 335204 913918 40 130.29 170 550 2/27/2012

Union County

16S18W22DCD1 331913 925704 222 25.15 247 36 2/22/2012

17S13W17DDC1 (J) 331402 922746 153 40.52 193 24 2/22/2012

17S15W31DCA2 331144 924116 199 54.41 253 110 2/22/2012

17S16W33BBA2 (K) 331229 924601 230 24.63 255 31 2/22/2012

18S15W21DAC1 330824 923909 192 7.65 200 40 2/22/2012

19S12W28CBA1 330207 922109 194 6.02 200 25 2/22/2012
Appendix 2 41

Appendix 2. Difference in depth to water from 2006 to 2012 in the Cockfield aquifer in southern Arkansas.—Continued

[Horizontal datum is North American Datum of 1983;Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929; positive 

differences in depth to water indicate a rise in water levels from 2006 to 2012 whereas negative values indicate a decline in water levels from 2006 to 2012]

Station name

Latitude 

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

2006 depth to water 

(feet below landsurface datum)

2012 depth to water 

(feet below landsurface datum)

Difference in 

water level 

from 2006 to 2012 

(feet)

Ashley County

15S04W26CBC1 332144 912932 41.88 40.36 1.5

17S04W10BCD2 331417 913030 38.18 43.58 -5.4

17S04W10CBA1 331406 913033 33.30 41.34 -8.0

17S06W07ADA1 331442 914510 72.85 76.43 -3.6

18S04W19DAA2 330710 913247 26.89 32.61 -5.7

18S08W04BBC1 331038 915627 80.30 87.62 -7.3

19S05W12CAC1 330336 913425 29.38 34.40 -5.0

Bradley County

12S10W10BCA1 334108 920807 124.15 125.02 -0.9

12S10W30CAC1 333815 921046 11.66 2.07 9.6

14S10W31DBA1 332658 921025 96.47 98.12 -1.7

14S11W35CAB1 332656 921251 75.89 79.03 -3.1

14S11W35DAC1 332650 921233 65.68 67.32 -1.6

15S12W11CAB1 332536 921858 23.94 23.76 0.2

16S11W11ACA1 332027 921223 29.36 32.39 -3.0

Calhoun County

11S13W15BBC1 334560 922534 53.18 53.44 -0.3

13S13W09CBD1 333555 922638 38.03 38.63 -0.6

13S13W15DBA1 333517 922520 23.40 22.78 0.6

14S13W11CAC1 333045 922451 28.55 29.89 -1.3

14S13W29ADA1 332829 922722 26.02 27.22 -1.2

14S13W29DAC1 332815 922729 14.24 14.69 -0.4

14S14W21ACB1 332931 923249 40.27 12.87 27.4

Chicot County

13S03W26BBB1 333247 912301 69.34 72.96 -3.6

16S02W04BAC1 332027 911857 38.07 38.98 -0.9

18S02W25ABB3 330640 911541 46.27 44.48 1.8

18S03W14CCC1 330731 912319 14.86 15.32 -0.5

Cleveland County

09S10W17CDD1 335534 920942 4.73 2.49 2.2

11S11W23BBD1 334449 921258 42.03 42.93 -0.9

Columbia County

17S20W35BBD1 331313 930914 14.91 10.52 4.4

19S20W34ADC1 330233 930958 22.37 22.71 -0.3

19S21W17CBB1 330520 931857 44.12 46.16 -2.0

19S21W35ADC1 330247 931513 3.54 0.37 3.2

19S22W36DBB1 330245 932034 41.15 43.43 -2.3

Appendix 2. Difference in depth to water from 2006 to 2012 in the Cockfield aquifer in southern Arkansas.

[Horizontal datum is North American Datum of 1983; Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929; positive 

differences in depth to water indicate a rise in water levels from 2006 to 2012 whereas negative values indicate a decline in water levels from 2006 to 2012]

Appendix 2
42 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Appendix 2. Difference in depth to water from 2006 to 2012 in the Cockfield aquifer in southern Arkansas.—Continued

[Horizontal datum is North American Datum of 1983;Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929; positive 

differences in depth to water indicate a rise in water levels from 2006 to 2012 whereas negative values indicate a decline in water levels from 2006 to 2012]

Station name

Latitude 

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

2006 depth to water 

(feet below landsurface datum)

2012 depth to water 

(feet below landsurface datum)

Difference in 

water level 

from 2006 to 2012 

(feet)

Desha County

12S03W30ADC1 333747 912611 72.99 78.54 -5.6

13S02W08CAA1 333504 911921 64.48 74.29 -9.8

Drew County

14S06W21BDC1 332846 914339 120.62 117.19 3.4

Lincoln County

10S05W06CAC1 335204 913918 126.3 130.29 -4.0

Union County

16S18W22DCD1 331913 925704 14.71 25.15 -10.4

17S13W17DDC1 331402 922746 38.67 40.52 -1.9

17S15W31DCA2 331144 924116 52.99 54.41 -1.4

17S16W33BBA2 331229 924601 25.54 24.63 0.9

18S15W21DAC1 330824 923909 26.13 7.65 18.5

19S12W28CBA1 330207 922109 10.73 6.02 4.7
Appendix 3 43

Appendix 3. Water-level data collected during February and March 2012 from wells completed in the Wilcox aquifer in northeastern 

Arkansas.

[Horizontal datum is North America Datum of 1983; NGVD 29, National Geodetic Vertical Datum of 1929; Letters in parentheses correspond to well locations 

in figure 9 and well hydrographs in figure 13]

Station name

Latitude 

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

Water-level 

altitude 

(feet above 

NGVD 29)

Depth to water 

(feet below landsurface datum)

Land-surface 

datum 

(feet above 

NGVD 29)

Well depth 

(feet)

Date of 

measurement

Craighead County

13N07E14BBA2 354526 901911 196 24.72 221 1,028 2/29/2012

14N05E25DCB1 354843 903029 193 40.52 233 890 2/29/2012

14N06E27ACB2 354858 902613 197 30.39 227 999 2/29/2012

14N07E17DCB1 (M) 355008 902202 200 32.17 232 1,070 2/29/2012

15N07E33BAD1 355315 902107 205 26.68 232 1,034 2/29/2012

Crittenden County

04N07E36ADB1 345449 901828 135 66.38 201 1,638 2/28/2012

05N07E29ACC1 350129 902225 145 54.77 200 1,700 2/28/2012

06N07E01ABB1 350520 901807 141 66.16 207 1,541 2/28/2012

06N09E07CAC1 350907 901042 123 86.72 210 1,470 2/28/2012

07N07E14CCC1 351318 901930 176 46.91 223 1,584 2/28/2012

07N08E24CAB1 351238 901148 148 73.36 221 1,540 2/28/2012

08N06E33CBD1 (N) 351614 902752 163 52.41 215 1,750 2/28/2012

09N08E29ADD1 352225 901516 165 60.57 225 1,564 2/28/2012

Greene County

17N06E31DCB1 (O) 360328 902902 182 103.23 285 462 2/29/2012

Lee County

01N04E09DCC1 (P) 344209 904220 136 67.93 204 1,885 2/28/2012

03N05E01BAB1 345413 903136 127 69.06 196 1,702 2/28/2012

Mississippi County

11N09E33AAB1 353214 900739 187 49.77 237 1,560 3/1/2012

11N10E20ADA1 353349 900213 189 45.57 235 1,417 3/1/2012

12N11E17CDD1 353917 895618 191 54.02 245 1,500 3/1/2012

13N11E08DDA1 354528 895547 203 41.82 245 1,445 3/1/2012

13N11E31CCCC1 354221 895807 204 37.37 241 1,500 3/1/2012

14N11E20CCA1 354859 895626 205 34.77 240 1,518 3/1/2012

15N09E31ACD1 (Q) 355306 900952 206 34.19 240 1,158 2/29/2012

15N10E01ADC1 355712 895806 219 28.96 248 1,350 2/29/2012

15N12E23DBC1 355426 894701 197 41.03 238 1,491 3/1/2012

Poinsett County

10N07E16CBB2 352925 902129 166 51.60 218 1,500 3/1/2012

11N05E06CCD1 353622 903618 179 35.21 214 992 3/2/2012

11N07E03BDD1 353629 901955 178 38.15 216 1,456 3/2/2012

12N05E13BBB1 (R) 354038 903059 183 39.66 222 1,071 3/2/2012

St. Francis County

04N06E16CCB1 345712 902830 143 59.35 202 1,615 2/28/2012

04N06E21BAD2 (S) 345649 902815 136 65.48 201 1,740 2/28/2012

Appendix 3
44 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Appendix 4. Water-level data collected during February and March 2012 from wells completed in the Wilcox aquifer in southern 

Arkansas.

[Horizontal datum is North America Datum of 1983; NGVD 29, National Geodetic Vertical Datum of 1929; Letters in parentheses correspond to well locations 

in figure 10 and well hydrographs in figure 14; --, missing data]

Station name

Latitude 

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, 

minutes, 

seconds)

Water-level 

altitude 

(feet above 

NGVD 29)

Depth to water 

(feet below 

land-surface 

datum)

Land-surface 

datum 

(feet above 

NGVD 29)

Well depth 

(feet)

Date of 

measurement

Clark County

07S18W03BBD1 340917 925604 267 2.75 270 47 2/21/2012

07S18W20ABB2 340652 925757 232 9.86 242 19 2/21/2012

09S18W20CBB1 (U) 335611 925905 210 20.10 230 26 2/22/2012

10S18W10DDB1 (T) 335216 925613 145 49.99 195 215 2/21/2012

Hempstead County

13S23W04BDD1 333842 932911 345 4.51 350 14 2/21/2012

13S24W02DCA2 333829 933311 394 51.92 446 63 2/21/2012

13S24W29ACC1 333524 933635 341 29.98 371 60 2/21/2012

14S24W29BCA1 (W) 333017 933704 334 21.04 355 31 2/21/2012

Hot Springs County

04S16W20CBB1 (V) 342144 924532 342 2.73 345 18 2/21/2012

05S17W10AAC1 341836 924853 394 15.57 410 26 2/21/2012

Nevada County

12S22W24CDA1 334046 931941 313 31.21 344 41 2/21/2012

13S21W02DCC1 333754 931426 251 63.53 315 240 2/21/2012

13S21W11BDA1 333738 931432 242 25.91 268 − 2/21/2012

13S21W23ABC1 333556 931423 319 42.56 362 47 2/21/2012

14S22W19AAA1 (X) 333105 932443 329 7.92 337 75 2/21/2012

Ouachita County

12S19W11DCD1 334144 930105 282 5.92 288 533 2/21/2012

Appendix 4
Appendix 5 45

Appendix 5. Difference in depth to water from 2006 to 2012 in the Wilcox aquifer in northeastern Arkansas.

[Horizontal datum is North American Datum of 1983; Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929; positive 

differences in depth to water indicate a rise in water levels from 2006 to 2012 whereas negative values indicate a decline in water levels from 2006 to 2012]

Station name

Latitude 

(degrees, minutes, 

seconds)

Longitude 

(degrees, minutes, 

seconds)

2006 depth 

to water 

(feet below landsurface datum)

2012 depth 

to water 

(feet below landsurface datum)

Difference 

in water level 

from 2006 to 2012 

(feet)

Craighead County

13N07E14BBA2 354526 901911 26.89 24.72 2.2

14N05E25DCB1 354843 903029 42.24 40.52 1.7

14N06E27ACB2 354858 902613 30.98 30.39 0.6

14N07E17DCB1 355008 902202 35.57 32.17 3.4

15N07E33BAD1 355315 902107 28.00 26.68 1.3

Crittenden County

04N07E36ADB1 345449 901828 59.09 66.38 -7.3

05N07E29ACC1 350129 902225 61.52 54.77 6.8

06N07E01ABB1 350520 901807 66.06 66.16 -0.1

06N09E07CAC1 350907 901042 90.44 86.72 3.7

07N07E14CCC1 351318 901930 68.93 46.91 22.0

07N08E24CAB1 351238 901148 68.37 73.36 -5.0

08N06E33CBD1 351614 902752 53.96 52.41 1.6

09N08E29ADD1 352225 901516 56.03 60.57 -4.5

Greene County

17N06E31DCB1 360328 902902 104.00 103.23 0.8

Lee County

01N04E09DCC1 344209 904220 62.62 67.93 -5.3

03N05E01BAB1 345413 903136 51.18 69.06 -17.9

Mississippi County

11N09E33AAB1 353214 900739 52.29 49.77 2.5

11N10E20ADA1 353349 900213 47.07 45.57 1.5

12N11E17CDD1 353917 895618 52.79 54.02 -1.2

13N11E08DDA1 354528 895547 59.03 41.82 17.2

13N11E31CCCC1 354221 895807 53.51 37.37 16.1

14N11E20CCA1 354859 895626 37.88 34.77 3.1

15N09E31ACD1 355306 900952 40.69 34.19 6.5

15N10E01ADC1 355712 895806 39.93 28.96 11.0

15N12E23DBC1 355426 894701 56.59 41.03 15.6

Poinsett County

10N07E16CBB2 352925 902129 51.03 51.60 -0.6

11N05E06CCD1 353622 903618 42.72 35.21 7.5

11N07E03BDD1 353629 901955 41.03 38.15 2.9

12N05E13BBB1 354038 903059 47.28 39.66 7.6

St. Francis County

04N06E16CCB1 345712 902830 54.36 59.35 -5.0

04N06E21BAD2 345649 902815 61.81 65.48 -3.7

Appendix 5
46 Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012

Appendix 6. Difference in depth to water from 2006 to 2012 in the Wilcox aquifer in southern Arkansas.

[Horizontal datum is North American Datum of 1983; Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929; positive 

differences in depth to water indicate a rise in water levels from 2006 to 2012, whereas negative values indicate a decline in water levels from 2006 to 2012]

Station name

Latitude 

(degrees, minutes, 

seconds)

Longitude 

(degrees, minutes, 

seconds)

2006 depth to water 

(feet below landsurface datum)

2012 depth 

to water 

(feet below landsurface datum)

Difference in 

water level 

from 2006 to 2012 

(feet)

Clark County

07S18W03BBD1 340917 925604 14.72 2.75 12.0

07S18W20ABB2 340652 925757 11.63 9.86 1.8

09S18W20CBB1 335611 925905 18.03 20.10 -2.1

10S18W10DDB1 335216 925613 48.31 49.99 -1.7

Hempstead County

13S23W04BDD1 333842 932911 4.91 4.51 0.4

13S24W02DCA2 333829 933311 48.9 51.92 -3.0

13S24W29ACC1 333524 933635 31.6 29.98 1.6

14S24W29BCA1 333017 933704 25.68 21.04 4.6

Hot Springs County

04S16W20CBB1 342144 924532 4.25 2.73 1.5

05S17W10AAC1 341836 924853 18.85 15.57 3.3

Nevada County

12S22W24CDA1 334046 931941 32.01 31.21 0.8

13S21W02DCC1 333754 931426 59.31 63.53 -4.2

13S21W11BDA1 333738 931432 26.07 25.91 0.2

13S21W23ABC1 333556 931423 43.28 42.56 0.7

14S22W19AAA1 333105 932443 26.03 7.92 18.1

Ouachita County

12S19W11DCD1 334144 930105 13.82 5.92 7.9

Appendix 6

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Rodgers—Potentiometric Surfaces and Water-Level Trends in the Cockfield Aquifer and the Wilcox Aquifer, Arkansas, 2012—SIR 2014–5232

ISSN 2328-0328 (online)