Potentiometric Surface

The potentiometric surface of the Catahoula aquifer 

(fig. 1) was constructed by using the altitude of water 

levels measured at 29 wells during the period May through 

September 2013 (table 2). Water levels were measured by 

using a steel or electric tape marked with 0.01-ft graduations. 

Water-level measurements were reported to 0.01 ft. Wells in 

which water levels were measured were not being pumped 

at the time of measurement. Two or more measurements 

were collected at each well to ensure the water level was 

static. The altitude of water levels ranged from 0.02 ft above 

the National Geodetic Vertical Datum of 1929 (NGVD 29) 

in well Co-51 to 238 ft above NGVD 29 in well Na-317 

(table 2). Groundwater movement in the Catahoula aquifer 

is generally to the southeast and towards discharge areas 

beneath the Sabine, Red, Little, and Tensas River Valleys 

(fig. 1). Much of the water flowing southward in areas 

between the river valleys is discharged by upward leakage 

through the confining layer to overlying sediments (Martin 

and Whiteman, 1986).

A visual comparison with the generalized potentiometric 

map of the Catahoula aquifer for 1980 (Martin and 

Whiteman, 1986) indicates that water levels in most areas 

of the aquifer generally declined about 20 ft between 1980 

and 2013. The hydrograph for well La-124 (depth of 365 ft), 

located in La Salle Parish, shows seasonal fluctuations and 

about a 27-ft decline since 1971, when the well was drilled 

(fig. 3). The hydrograph for well R-1299 (depth of 1,060 

ft), located in central Rapides Parish, also shows seasonal 

fluctuations but shows a much larger decline of about 67 ft 

since the well was drilled in 1986 (fig. 4). Withdrawals from 

the Catahoula aquifer increased about 45 percent (2.74 to 

3.96 Mgal/d) during the period 2005–10 (Sargent, 2007), 

primarily for public supply. The largest withdrawal increase 

was in Catahoula Parish (table 1).

Table 2. Water-level data used to construct the potentiometric-surface map of the Catahoula aquifer in 

central Louisiana, May–September 2013.

[NGVD 29, National Geodetic Vertical Datum of 1929]

Well number Well depth 

(in feet)

Water level 

(in feet below land surface)

Water level 

(in feet above NGVD 29)

Date 

measured

Catahoula Parish

Ct-12 405 88.75 11.25 07-16-13

Ct-45 229 54.14 11.86 07-24-13

Ct-62 736 25.47 29.53 07-16-13

Ct-105 189 25.75 24.25 07-24-13

Ct-293 402 36.84 15.16 07-16-13

Ct-318 346 61.92 28.08 07-16-13

Ct-5288Z 220 146.04 78.96 07-24-13

Concordia Parish

Co-51 740 54.98 0.02 07-29-13

Co-165 335 25.58 40.42 07-29-13

Grant Parish

G-7 560 23.76 56.24 05-21-13

G-181 353 140.87 72.13 05-22-13

G-225 473 102.65 87.35 06-26-13

G-393 75 28.76 93.24 07-15-13

La Salle Parish

La-124 365 91.02 69.98 07-30-13

La-172 97 46.44 133.56 07-29-13

La-262 431 149.23 40.77 06-26-13

Natchitoches Parish

Na-101 270 115.14 182.86 05-21-13

Na-317 254 122.42 237.58 07-01-13

Na-567 220 115.90 182.10 05-21-13

Rapides Parish

R-1113 852 147.08 28.92 05-23-13

R-1299 1,060 147.01 12.99 07-24-13

R-1310 535 99.96 110.04 05-21-13

Sabine Parish

Sa-287 208 81.05 228.95 09-25-13

Sa-386 131 17.05 224.95 07-02-13

Sa-429 356 105.58 161.42 09-25-13

Sa-442 210 61.06 138.94 09-25-13

Vernon Parish

V-425A 1,792 138.11 166.89 06-04-13

V-458 1,200 27.67 212.33 05-20-13

V-656 1,478 241.73 138.27 09-25-13

The Catahoula aquifer crops out in a narrow band across north-central Louisiana 

(fig. 1). This band is broken by alluvial deposits in the valleys of the Red, Little, and 

Ouachita Rivers that have incised into the aquifer. In Grant, La Salle, and Catahoula 

Parishes, the Catahoula aquifer is overlain by a thin veneer of Quaternary terrace 

deposits in upland areas between major stream valleys. South of this outcropsubcrop area, the aquifer dips towards the south and southeast, is overlain and 

confined by clays of the Lena Member of the Fleming Formation, and is underlain 

by clays of the Vicksburg and Jackson Groups (fig. 2). Saltwater ridges under the 

Red, Little, and Tensas River Valleys divide the freshwater extents of the Catahoula 

aquifer and limit the flow of freshwater between these areas (Gaydos and others, 

1973). The small area of freshwater in the aquifer in northeastern Concordia Parish 

and southeastern Tensas Parish is part of a large area of freshwater in the Catahoula 

aquifer in Mississippi.

The Catahoula aquifer generally ranges in thickness from about 50 feet (ft) in 

the outcrop area to about 450 ft in southern Vernon Parish. Sand beds in the aquifer 

are generally discontinuous, lenticular, and interbedded with silts and clays (Martin 

and Whiteman, 1986). The sands of the aquifer are typically white to light gray 

and range from very fine to very coarse grained, with various degrees of sorting 

(Newcome and others, 1963). 

Beneath the upland areas, within the outcrop-subcrop area, water-table 

conditions commonly occur in the upper part of the Catahoula aquifer. The lower 

part of the aquifer beneath the upland areas and the full thickness of the aquifer 

beneath the alluvium are generally under artesian conditions (Martin and Whiteman, 

1986).

Recharge to the Catahoula aquifer is primarily from infiltration of rainfall in 

the upland outcrop-subcrop area and leakage from underlying aquifers. Discharge 

is to streams and small springs and from wells. The depths of wells screened in the 

Catahoula aquifer generally range from less than 200 ft below land surface in upland 

areas to 1,880 ft deep along the downdip limit of freshwater in Rapides Parish. 

Hydrogeology

References

Gaydos, M.W., Rogers, J.E., and Smith, R.P., 

1973, Water resources of the Little River 

Basin, Louisiana: U.S. Geological Survey 

Water-Supply Paper 1989, 74 p.

Lovelace, J.K., and Lovelace, W.M., 1995, 

Hydrogeologic unit nomenclature and 

computer codes for aquifers and confining 

units in Louisiana: Louisiana Department 

of Transportation and Development Water 

Resources Special Report no. 9, 12 p.

Martin, Angel, Jr.; and Whiteman, C.D., Jr., 1986, 

Generalized potentiometric surface of the 

Catahoula aquifer in central Louisiana, 1980: 

U.S. Geological Survey Water-Resources 

Investigations Report 86–4059, 1 sheet.

Newcome, Roy, Jr.; Page, L.V.; and Sloss, 

Raymond, 1963, Water resources of 

Natchitoches Parish, Louisiana: Department of 

Conservation, Louisiana Geological Survey, 

and Louisiana Department of Public Works 

Water Resources Bulletin no. 4, 

189 p.

Sargent, B.P., 2007, Water use in Louisiana, 2005: 

Louisiana Department of Transportation and 

Development Water Resources Special Report 

no. 16, 133 p.

Sargent, B.P., 2011, Water use in Louisiana, 

2010: State of Louisiana Department of 

Transportation and Development Special 

Report no. 17, 134 p. 

Introduction

The Catahoula aquifer is an important source of fresh groundwater in an area 

of central Louisiana that includes parts of Catahoula, Concordia, Grant, La Salle, 

Natchitoches, Rapides, Sabine, Tensas, and Vernon Parishes. In 2010, about 3.96 

million gallons per day (Mgal/d) (table 1) were withdrawn from the Catahoula 

aquifer in Louisiana (Sargent, 2011). About 89 percent (3.51 Mgal/d) of the water 

was withdrawn for public-supply use (B.P. Sargent, U.S. Geological Survey, written 

commun., 2013), and about 49 percent (1.93 Mgal/d) was withdrawn in Catahoula 

Parish. 

Additional knowledge about the effects of withdrawals on water levels and flow 

directions in the Catahoula aquifer is needed to assess the current condition of the 

aquifer. The most recent potentiometric map constructed for the Catahoula aquifer 

in Louisiana was published more than 25 years ago (Martin and Whiteman, 1986). 

An updated potentiometric map is needed to spatially visualize water levels and the 

effects of pumping and to delineate cones of depression, water-level gradients, and 

flow paths. 

In 2012, the U.S. Geological Survey (USGS) in cooperation with the Louisiana 

Department of Natural Resources began a study to document current water levels in 

selected aquifers in Louisiana. This report presents water-level data and a map that 

illustrates the potentiometric surface of the Catahoula aquifer in 2013. The data were 

collected during the period May to September 2013. The potentiometric-surface map 

(fig. 1) can be used for determining the direction of groundwater flow, hydraulic 

gradients, and effects of withdrawals on water levels. Water-level data collected for 

this study are stored in the USGS National Water Information System and are on file 

at the USGS office in Baton Rouge, La.

Table 1. Groundwater withdrawals from the Catahoula aquifer 

in the study area, 2005 and 2010 (Sargent 2007, 2011).

Parish

Withdrawals by parish

(million gallons per day)

1990 2010

Catahoula 1.14 1.93

Concordia 0.32 0.41

Grant 0.47 0.61

La Salle 0.07 0.16

Natchitoches 0.03 0.03

Rapides 0.51 0.59

Sabine 0.06 0.05

Vernon 0.14 0.18

Total 2.74 3.96

Figure 3. Hydrograph of well La-124, La Salle Parish, Louisiana.

No data

50

60

70

80

90

100

1971197219741975197619781979198019821983198419861987198819901991

1992199419951996199819992000200220032004200620072008201020112012

2013

Water level, in feet above National Geodetic Vertical Datum of 1929

Date

Figure 4. Hydrograph of well R-1299, Rapides Parish, Louisiana.

-20

0

20

40

60

80

100

198519861987198819891990199119921993

1994199519961997199819992000

2001

2002

20032004

200520062007

20082009

2010

201120122013

Water level, in feet above National Geodetic Vertical Datum of 1929

Date

No data

Figure 2. Hydrogeologic column of aquifers in central Louisiana.

Red River alluvial deposits

Mississippi River alluvial deposits

Aquifer system or 

confining unit Aquifer or confining unit

Chicot aquifer or surficial confining unit

System Series Stratigraphic unit

Hydrogeologic unit

Central Louisiana

Quaternary

Pleistocene Northern Louisiana terrace deposits

Unnamed Pleistocene deposits

Catahoula aquifer

Miocene

Williamson Creek Member

Dough Hills Member Carnahan 

Bayou Member

Lena Member

Williamson Creek aquifer Dough 

Hills confining unit 

Carnahan Bayou aquifer

No freshwater occurs in older aquifers

(modified from Lovelace and others, 1995)

Castor Creek Member Castor Creek confining unit

Pliocene Blounts Creek Member Evangeline aquifer or surficial confining unit

Catahoula Formation

Vicksburg Group, undifferentiated

Jackson Group, undifferentiated

Tertiary

Oligocene

Eocene

Fleming Formation

Jasper aquifer system or surficial 

confining unit

Lena confining unit

?

?

Figure 1. Potentiometric surface of the Catahoula aquifer in central Louisiana, 2013.

Ouachita River

Little River

Red River

Red River

VERNON PARISH

RAPIDES PARISH

SABINE PARISH

GRANT

PARISH

NATCHITOCHES

PARISH

TENSAS 

PARISH

AVOYELLES PARISH

LA SALLE

PARISH

CATAHOULA

PARISH

CONCORDIA

 PARISH

Approximate li mit of freshwater

Northern limit of the

Catahoula aquifer

Tensas River

60

40

60

20

80

120

40

140

120

180

160

80

200

100

100

140

220

60

80

20

80

20

20

Co-51

G-393 0.02

93.24

G-181

72.13

56.24

V-656 138.27

V-458

212.33

R-1299

12.99

Na-567

182.10

La-262

40.77

Ct-45 11.86

Ct-318

28.08

Ct-293 15.16

Ct-105

24.25

Ct-12 11.25

Co-165

40.42

Sa-442

138.94

Sa-429

161.42

Sa-386

224.95

Sa-287

228.95

R-1310

110.04

Na-317

237.58

La-172

133.56

Na-101

182.86

V-425A 166.89

28.92

La-124 69.98 Ct-62

29.53

R-1113

G-7

G-225

87.35

Ct-5288Z 78.96

Sicily Island

Alexandria

Leesville

93° 92° 91°

32°

31°

0 12.5 25 50 MILES

0 12.5 25 50 KILOMETERS

EXPLANATION

Altitude of freshwater in feet above the National

Geodetic Vertical Datum of 1929. Contour interval 20 ft. 

Dashed where approximate

Control point

General direction of groundwater flow

Outcrop area for the Catahoula aquifer 

Observation well for which hydrograph is shown

220

M I S S I S S I P P I

G U L F O F M E X I C O

Study Area

LOUISIANA

ARKANSAS

TEXAS

I SBN 978- 1- 4113-3976- 7

9 7 8 1 4 1 1 339 767

U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation with the Scientific Investigations Map 3339

Louisiana Department of Natural Resources

Potentiometric Surface of the Catahoula Aquifer in 

Central Louisiana, 2013

By

Robert B. Fendick, Jr., and Kayla Carter

2015

Any use of trade, product, or firm names in this publication is for descriptive purposes only

and does not imply endorsement by the U.S. Government

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, 

Denver, CO 80225, 1–888–ASK–USGS

Digital files available at http://dx.doi.org/10.3133/sim3339

Suggested citation: Fendick, R.B., Jr., and Carter, Kayla, 2015, Potentiometric surface of the 

Catahoula aquifer in central Louisiana, 2013: U.S. Geological Survey Scientific Investigations 

Map 3339, 1 sheet, http://dx.doi.org/10.3133/sim3339.

Printed on recycled paper

ISSN 2329-1311 (print)

ISSN 2329-132X (online)

http://dx.doi.org/10.3133/sim3339