In cooperation with

Louisiana State University Agricultural Center

Cooperative Extension Service and the

Louisiana Rice Research Board

In cooperation with

Louisiana State University Agricultural Center

Cooperative Extension Service and the

Louisiana Rice Research Board

Withdrawals, Water Levels, and Specific

Conductance in the Chicot Aquifer System in

Southwestern Louisiana, 2000-03

U.S. Department of the Interior

U.S. Geological Survey

Scientific

Investigations Report

2004-5212
Withdrawals, Water Levels, and Specific 

Conductance in the Chicot Aquifer System 

in Southwestern Louisiana, 2000-03

By John K. Lovelace, Jared W. Fontenot, and C. Paul Frederick

In cooperation with Louisiana State University Agricultural Center

Cooperative Extension Service and the

Louisiana Rice Research Board

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2004-5212
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

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.

Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report.

Suggested citation:

Lovelace, J.K., Fontenot, J.W., and Frederick, C.P., 2004, Withdrawals, water levels, and specific conductance in 

the Chicot aquifer system in southwestern Louisiana, 2000-03: U.S. Geological Survey Scientific Investigations 

Report 2004-5212, 56 p.
 iii

Contents

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

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

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

Data Collection and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Previous Investigations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Hydrogeology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Withdrawals and Water Levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Specific Conductance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Selected References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figures

1. Map showing location of the study area in southwestern Louisiana. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

2. Graph showing water withdrawal rates for rice irrigation in southwestern Louisiana, 1960-2000. . . . .4

3. Diagram showing partial hydrogeologic column of aquifers in southwestern

Louisiana. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

4. Graph showing departure from normal monthly precipitation (1971-2000) in southwestern

Louisiana, January 1999 through June 2003. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

5-7. Maps showing:

5. Potentiometric surface of the massive, upper, and “200-foot” sands

of the Chicot aquifer system in southwestern Louisiana, June 2002. . . . . . . . . . . . . . . . . . . . . . . . . . . .8

6. Potentiometric surface of the massive, upper, and “200-foot” sands

of the Chicot aquifer system in southwestern Louisiana, January 2003 . . . . . . . . . . . . . . . . . . . . . . . .9

7. Water-level change in the massive, upper, and “200-foot” sands of the

Chicot aquifer system in southwestern Louisiana, June 2002 to January 2003 . . . . . . . . . . . . . . . 10

8. Hydrograph showing hourly water levels at selected wells screened in the

Chicot aquifer system in southwestern Louisiana, 2000-03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

9. Graph showing the relation between specific conductance values and chloride

concentrations in the Chicot aquifer system in southwestern Louisiana. . . . . . . . . . . . . . . . . . . . . . . . . . . 12

10-12. Maps showing:

10. Specific conductance in the massive, upper, and “200-foot” sands

of the Chicot aquifer system in southwestern Louisiana. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

11. Location of wells sampled for specific conductance in southwestern Louisiana, 2000-03. . . . 15

12. Location of wells sampled for specific conductance near Iowa, Louisiana, 2000-03 . . . . . . . . . 16

13. Graphs showing specific conductance values at selected wells in southwestern

Louisiana, 2000-03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

14. Graphs showing hourly specific conductance values during pumping at selected

wells screened in the Chicot aquifer system in southwestern Louisiana, 2000-03 . . . . . . . . . . . . . . . . . . 18
iv 

Tables

1. Water-level data used to construct potentiometric-surface maps for June 2002

and January 2003, and water-level change map, June 2002 to January 2003,

in the massive, upper, and “200-foot” sands of the Chicot aquifer system in 

southwestern Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

2. Commonly accepted tolerance of rice to selected saltwater concentrations. . . . . . . . . . . . . . . . . . . . . . 12

3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in

southwestern Louisiana, including specific conductance values and chloride 

concentrations, 2000-03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Conversion Factors, Datums, and Abbreviated 

Water-Quality Units

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

°F = (1.8 x °C) + 32

Vertical coordinate information in this report is referenced to the National Geodetic Vertical 

Datum of 1929 (NGVD 29)--a geodetic datum derived from a general adjustment of the first-order 

level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.

Horizontal coordinate information in this report is referenced to the North American Datum of 

1927 (NAD 27).

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

25°C).

Concentrations of chloride in water are given in milligrams per liter (mg/L).

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 0.004047 square kilometer (km2)

square mile (mi2) 2.590 square kilometer (km2)

Volume

gallon (gal) 3.785 liter (L)

Flow rate

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

million gallons per day (Mgal/d) 3,875 cubic meter per day (m3/d)
Withdrawals, Water Levels, and Specific Conductance 

in the Chicot Aquifer System in Southwestern Louisiana, 

2000-03

By John K. Lovelace, Jared W. Fontenot, and C. Paul Frederick

Abstract

The Chicot aquifer system is the principal source of fresh 

ground-water supplies in southwestern Louisiana. Much of the 

area is rural and rice cultivation is the primary agricultural 

activity. About 540 million gallons per day were withdrawn 

from the aquifer system in southwestern Louisiana in 2000. 

Potentiometric-surface maps of the aquifer system were created 

for June 2002 and January 2003 to determine where water-level 

declines occur due to seasonal ground-water withdrawals. During June 2002, water levels in the aquifer system were more 

than 40 feet below the National Geodetic Vertical Datum of 

1929 (NGVD 29) in parts of Acadia, Calcasieu, Evangeline, and 

Jefferson Davis Parishes, in an area that generally coincides 

with rice-farming areas. During January 2003, water levels 

were more than 30 feet below NGVD 29 in these areas.

From June 2002 to January 2003, water levels generally 

recovered between 5 and 20 feet in the Chicot aquifer system in 

most of Acadia and Jefferson Davis Parishes, southeastern Calcasieu Parish, and southern Evangeline Parish, in an area that 

generally coincides with rice-farming areas. These water-level 

changes are representative of the areal extent and magnitude of 

typical seasonal water-level fluctuations that occur in the aquifer system in response to seasonal ground-water withdrawals 

for rice irrigation.

The presence of saltwater has been documented in the Chicot aquifer system beneath coastal parishes and in some areas 

where the aquifer system merges with the stratigraphically adjacent Atchafalaya aquifer. Data collected during the period 1943 

to 2003 from 1,355 wells screened in the massive, upper, and 

“200-foot” sands of the Chicot aquifer system and the Atchafalaya aquifer were used to delineate areas having similar specific 

conductance values and determine areas where wells are 

affected by saltwater. Near the outcrop area, specific conductance values in the Chicot aquifer system generally are less than 

150 μS/cm (microsiemens per centimeter at 25 degrees Celsius). Specific conductance values increase south and east of the 

outcrop area. Specific conductance values generally range from 

151 to 500 μS/cm in rice-farming areas of northwestern Acadia 

Parish, southeastern Allen Parish, western Evangeline Parish, 

and northern and central Jefferson Davis Parish. Specific conductance values generally range from 501 to 1,000 μS/cm in 

most of the remaining rice-farming areas. Specific conductance 

values often exceed 1,000 μS/cm in an area along the border 

between Calcasieu and Jefferson Davis Parishes near Iowa, 

Louisiana, parts of northeastern Cameron Parish, an area of 

northwestern and central St. Landry Parish; parts of Vermilion 

Parish, and several areas along the eastern boundary of the 

study area where the Chicot aquifer system merges with the 

Atchafalaya aquifer. The maximum specific conductance value, 

12,100 μS/cm, is from a well in Cameron Parish.

During 2000-03, specific conductance was measured in 

521 water samples from 166 wells screened in the Chicot aquifer system or the Atchafalaya aquifer. Specific conductance values exceeded 1,000 μS/cm in water samples from wells in Calcasieu, Cameron, Jefferson Davis, St. Landry, St. Martin, St. 

Mary, and Vermilion Parishes. Specific conductance values 

exceeded 2,000 μS/cm in only two wells—an irrigation well 

located about 2 miles south of Iowa and a USGS observation 

well used to monitor saltwater encroachment in east-central 

Vermilion Parish. Specific conductance values increased 

steadily at one well, from 1,090 μS/cm in April 2000 to 

2,860 μS/cm in April 2003. Nearby wells did not show similar 

increases.

Specific conductance was measured hourly during pumping at two irrigation wells between 2000 and 2003. Specific 

conductance values were greater than 1,000 μS/cm in both 

wells, indicating the presence of saltwater near the wells. Specific conductance values generally fluctuated about 150 μS/cm 

at both wells, but no long-term trends in the specific conductance were evident in either well.

Introduction

The Chicot aquifer system underlies an area of about 

9,000 mi2 in southwestern Louisiana (fig. 1) and is the principal 

source of fresh ground-water supplies in the region. Much of the 

area is rural, and rice cultivation is the primary agricultural 

activity. Withdrawals from the aquifer system, primarily for 
LOUISIANA

TEXAS

MISSISSIPPI

ARKANSAS

Index Map

Study Area

IN

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Bayou

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RIVER

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S I MIS ISS PPI

RIVER

you Ba

N zpi ue e q

RED

CALCASIEU RIVER

RIVER

Houston

River

VERNON

CALCASIEU

RAPIDES

EVANGELINE

AVOYELLES

ST.

LANDRY

JEFFERSON

DAVIS

ACADIA

LAFAYETTE

ST.

MARTIN

POINTE COUPEE

CAMERON

VERMILION

IBERIA

ST.

MARY

Lake Charles

Cameron

Crowley

Jennings

Abbeville

Lafayette

St. Martinville

New Iberia

Franklin

DeRidder

Leesville

Oberlin

Ville Platte

Alexandria

Marksville

Opelousas

E

New Roads

A

T

X

S

Gulf of Mexico

31° 00 ́

93° 00 ́ 92° 30 ́ 92° 00 ́ 91° 30 ́

29° 30 ́

30° 00 ́

30° 30 ́

93° 30 ́

SAB NE I

RIVER

BEAUREGARD

ALLEN

5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

0

EXPLANATION

LAND USED FOR RICE FARMING

(SOURCE: LOUISIANA DEPARTMENT

OF ENVIRONMENTAL QUALITY, 1995)

Figure 1. Location of the study area in southwestern Louisiana.

BOUNDARY OF FRESHWATER IN

THE CHICOT AQUIFER SYSTEM

(modified from Smoot, 1986)

JD-485A

APPROXIMATE BOUNDARY BETWEEN

 THE CHICOT MASSIVE SAND TO THE

 NORTH AND THE UPPER AND LOWER

 SANDS TO THE SOUTH (Nyman, 1989)

APPROXIMATE BOUNDARY BETWEEN

 THE CHICOT MASSIVE SAND TO THE

 NORTH AND THE "200-," "500-," AND

 "700-FOOT" SANDS TO THE SOUTH

 (Nyman, 1989)

APPROXIMATE BOUNDARY BETWEEN

 THE UPPER AND LOWER SANDS TO

 THE EAST AND THE "200-" AND

 "700-FOOT" SANDS TO THE WEST

 (modified from Nyman, 1989)

CONTROL POINT AND WELL NUMBER

 FOR WHICH HYDROGRAPH IS

 SHOWN

OUTCROP AREA

Cu-1386

CONTROL POINT AND WELL NUMBER

 FOR WHICH GRAPH OF HOURLY

 SPECIFIC CONDUCTANCE IS SHOWN

BOUNDARY OF STUDY AREA

WESTERN BOUNDARY OF THE

ATCHAFALAYA AQUIFER

(modified from Nyman, 1989)

Map credit: Modified from Official Map of Louisiana, Louisiana Department of Transportation and Development, 1986

Ev-229

JD-485A

Ac-326

l

l

l l

l

l

Ac-428

Cn-92 Cn-196

l

Cu-1386

2 Withdrawals, Water Levels, and Specific Conductance in the Chicot Aquifer System
Introduction 3

rice irrigation, have caused water levels to decline as much as 

100 ft beneath some rice-farming areas of southwestern Louisiana since the early 1900’s, creating an elongated cone of 

depression in the water-level surface over much of the region 

(Zack, 1971, p. 7-9 and pl. 2). In 1999, about 610,000 acres of 

rice were planted in southwestern Louisiana (fig. 1) (Louisiana 

Cooperative Extension Service, 2000). The water withdrawal 

rate from the aquifer system for rice irrigation in 2000, which 

was estimated based on 1999 acreage, was about 540 Mgal/d 

(Sargent, 2002, p. 17 and 92). Figure 2 shows water withdrawal 

rates for rice irrigation in southwestern Louisiana from 1960 to 

2000.

From 1990 to 2000, water levels at several observation 

wells screened in the Chicot aquifer system and located in ricefarming areas declined at an average rate of 1 to 2 ft/yr 

(Tomaszewski and others, 2002, p. 11). Water levels in some 

areas of the aquifer system also fluctuate seasonally, primarily 

in response to ground-water withdrawals for rice irrigation 

(Nyman and others, 1990, p. 17), and wells in these areas could 

be affected seasonally.

The presence of saltwater1 has been documented in the 

Chicot aquifer system beneath coastal parishes, in some areas 

where the aquifer system merges with the stratigraphically adjacent Atchafalaya aquifer, and in isolated bodies of saltwater 

near Lake Charles, Iowa, and south of Abbeville, Louisiana 

(Nyman, 1984). Seasonal pumping for rice irrigation has altered 

flow directions in the Chicot aquifer system and can induce lateral or upward movement of saltwater (Nyman, 1984, p. 1). 

Some irrigation wells screened in the aquifer system may be 

affected by saltwater encroachment, especially during periods 

of increased pumping in response to drought conditions.

 Some farmers and residents of southwestern Louisiana are 

concerned that water levels in the Chicot aquifer system may 

decline below pump intakes in their wells, leaving them without 

water, or that their wells will be affected by saltwater encroachment. Current (2000-03) information is needed to (1) determine 

the location, duration, and magnitude of seasonal water-level 

declines; (2) delineate areas where wells are affected by saltwater; and (3) determine whether specific conductance, an indicator of saltwater, is increasing in water from wells in these areas. 

In response to this need, the U.S. Geological Survey (USGS), in 

cooperation with the Louisiana State University Agricultural 

Center, Louisiana Cooperative Extensive Service (LCES), and 

the Louisiana Rice Research Board, established a study in 2000 

to monitor water levels and specific conductance in wells 

screened in the Chicot aquifer system over a 3-year period. 

Results of this study were reported periodically; potentiometricsurface maps and data for June 2000 and January 2001 were 

published in Lovelace and others (2001; 2002). This is the third 

and final report.

Purpose and Scope

This report describes water withdrawals, water levels, and 

specific conductance in the Chicot aquifer system in southwestern Louisiana during 2000-03. Trends in water levels and specific conductance also are discussed. Maps illustrate the potentiometric surface of the massive, upper, and “200-foot” sands of 

the aquifer system during June 2002 and January 2003. Waterlevel data from 141 wells used to construct the potentiometric 

surfaces are presented in a table. A map, based on data collected 

during 1943-2003, shows areas having similar specific conductance values in the massive, upper, and “200-foot” sands of the 

aquifer system. Specific conductance data collected during 

2000-03 from 166 wells in southwestern Louisiana, are presented in a table. Graphs of water level and specific conductance data from selected wells also are presented. All data presented are on file at the USGS office in Baton Rouge, 

Louisiana, and stored in the USGS National Water Information 

System data base.

Data presented in this report establish baseline conditions 

that could enable current (2003) and future farmers, agricultural 

agents, and water-resources managers to determine the effects 

of ground-water withdrawals on water levels and water quality 

in the Chicot aquifer system. Results of this study may help 

improve understanding of conditions in similar coastal settings 

in other areas of the United States.

Description of Study Area

The study area includes all or parts of 15 parishes in southwestern Louisiana: Acadia, Allen, Beauregard, Calcasieu, 

Cameron, Evangeline, Lafayette, Iberia, Jefferson Davis, 

Rapides, St. Landry, St. Martin, St. Mary, Vermilion, and Vernon Parishes (fig. 1). The climate is generally warm, humid, and 

temperate. The average annual temperature is about 20oC and 

the average annual precipitation is 55 in. (National Oceanic and 

Atmospheric Administration, 1995, p. 7, 9).

Data Collection and Methods

Water levels were measured using steel or electrical tapes 

marked with 0.01-ft gradations. Wells in which water levels 

were measured were not being pumped at the time the measurements were made. In addition, water levels were measured 

hourly at five wells located in rice-farming areas during 

2000-03 using pressure transducers and data recorders.

Water samples for analysis of specific conductance and 

chloride concentration were collected from wells at a spigot or 

other discharge outlet. Many of the water samples were col1

For the purposes of this report, saltwater is defined as water containing greater than 250 mg/L of chloride. Concentrations of chloride greater than 250 mg/L 

exceed the Secondary Maximum Contaminant Level (SMCL) for drinking water (U.S. Environmental Protection Agency, 1992). SMCL’s are established for contaminants that can adversely affect the aesthetic quality of drinking water. At high concentrations or values, health implications as well as aesthetic degradation 

also may exist. SMCL’s are not federally enforceable, but are intended as guidelines for the states.
4 Withdrawals, Water Levels, and Specific Conductance in the Chicot Aquifer System

lected by well owners, farmers, or LCES agents; bottles and 

instructions on how to sample were supplied by the USGS. 

These samples were sent to the USGS office in Baton Rouge 

where they were analyzed for specific conductance using a 

hand-held or bench-top conductivity meter. To accurately identify and verify locations of wells sampled by well owners, farmers, or LCES agents, all wells were visited and many were resampled by USGS personnel. To increase the areal coverage of 

sampled wells, additional wells in the study area were sampled 

by USGS personnel. Samples collected by USGS personnel 

were analyzed for specific conductance using a hand-held meter 

in the field. Sample collection and measurements of specific 

conductance made in the field or at the USGS office in Baton 

Rouge were in accordance with methods described in U.S. Geological Survey (1997-present). Samples collected by USGS personnel for analysis of chloride concentrations were sent to a 

USGS laboratory in Ocala, Florida, where they were analyzed 

for dissolved chloride and specific conductance using laboratory methods described in Fishman and Friedman (1989).

Specific conductance and temperature were measured 

hourly during 2000-03 at two irrigation wells using a conductance meter and data recorder. The probe to the conductance 

meter was placed in a custom-made receptacle through which 

water flowed while the well pump was running. When the pump 

stopped, the receptacle drained. The periods during which the 

pump was not running were evident from temperature fluctuations, and data collected during these periods were discarded. 

Temperature data are not presented in this report.

State well-registration records currently (2003) list about 

3,200 active irrigation wells that are screened in the Chicot 

aquifer system. Less than 100 of these wells are screened in the 

deeper sands, which include the lower sand and the “500-foot” 

and “700-foot” sands of the Lake Charles area (Z. “Bo” 

Bolourchi, Louisiana Department of Transportation and Development, written commun., 2003). Therefore, for the purposes of 

this report, references to the Chicot aquifer system in following 

sections refer to the Chicot massive sand, upper sand, and 

“200-foot” sand of the Lake Charles area unless otherwise 

indicated.

1960 1965 1970 1975 1980 1985 1990 1995 2000

0

200

400

600

800

1,000

1,200

GROUND WATER

SURFACE WATER

WITHDRAWAL RATE, IN MILLION GALLONS PER DAY

Figure 2. Water withdrawal rates for rice irrigation in southwestern Louisiana, 1960-2000 (Snider and Forbes, 1961; Bieber and Forbes, 

1966; Dial, 1970; Cardwell and Walter, 1979; Walter, 1982; Lurry, 1987; Lovelace, 1991; Lovelace and Johnson, 1996; Sargent, 2002).
Hydrogeology 5

Previous Investigations

Since the early 1900’s, many studies have focused on the 

occurrence and use of ground water, declining water levels, and 

saltwater encroachment in the Chicot aquifer system in southwestern Louisiana. Harris (1904) presented information about 

the underground waters of southwestern Louisiana and included 

a section on their use for water supplies and rice irrigation. Stanley and Maher (1944) reported on declining water levels in Acadia and Jefferson Davis Parishes due to ground-water withdrawals for rice irrigation. Jones (1950a) discussed water 

quality and the occurrence of saltwater in the Chicot aquifer 

system and presented a map showing the maximum depth of 

occurrence of fresh ground water throughout southwestern Louisiana. Jones and others (1954) presented the first comprehensive report on the geology and ground-water resources of southwestern Louisiana, presented maps of the Chicot aquifer system 

and the base of freshwater, and discussed the presence of saltwater and possibilities of saltwater encroachment in basal sands 

and coastal areas of the aquifer system. Harder (1960) presented 

a detailed report on the geology and ground-water resources of 

Calcasieu Parish, including a discussion of the occurrence and 

mobility of saltwater in the “200-foot” sand.

Fader (1957) updated the base-of-freshwater map by Jones 

and others (1954) and suggested five possible reasons for the 

presence of saltwater in the Chicot aquifer system: (1) incomplete flushing of the aquifer by freshwater, (2) lateral movement 

through formations, (3) downward seepage from surface 

sources, (4) vertical movement through underlying or overlying 

materials, and (5) upward movement along faults or around salt 

domes. Whitman and Kilburn (1963) discussed the occurrence 

and inland movement of saltwater in coastal areas of the upper 

sand due to increased ground-water withdrawals. Harder and 

others (1967) presented maps of the freshwater-saltwater interface in the upper sand and discussed the rate of encroachment.

Zack (1971) summarized the results of 10 years of monitoring chloride concentrations in water from 30 wells of a network established to monitor saltwater intrusion in the Chicot 

aquifer system. Nyman (1984) summarized chloride and specific conductance data collected by the USGS from wells in the 

Chicot aquifer system since 1937, focusing on data from the 

network. Nyman (1989) presented maps showing the range of 

various water-quality constituents and properties, including 

specific conductance, in the Chicot aquifer system. Lovelace 

(1999) updated the study by Nyman (1984) with chloride data 

collected during 1995-96. Potentiometric-surface maps of water 

levels in the Chicot aquifer system were published in many of 

these reports. Most recently, Tomaszewski and others (2002) 

determined trends in ground-water levels in monitor wells 

screened in the Chicot aquifer system for the approximate 

period 1990-2000.

Acknowledgments

The authors gratefully acknowledge the assistance of rice 

farmers who collected water samples from their wells and sent 

them to the USGS for analysis. The authors also gratefully 

acknowledge the assistance and cooperation of public-water 

suppliers and private well owners who allowed water levels to 

be measured in their wells. The authors especially want to thank 

Eddie Eskew, Keith Fontenot, Howard Cormier, Ron Levy, 

Jerry Whatley, and Gary Wicke, County Agents of the Louisiana Cooperative Extension Service, who initiated contacts with 

many of the land owners and farmers, assisted in sample collection, and were instrumental in developing the study. Thanks 

also to Z. “Bo” Bolourchi, Chief, Public Works and Water 

Resources Division, Louisiana Department of Transportation 

and Development, for providing well information that was used 

during this study.

Hydrogeology

The Chicot aquifer system underlies most of southwestern 

Louisiana and parts of eastern Texas. The system is composed 

of deposits of silt, sand, and gravel separated by units of clay 

and sandy clay. The system dips and thickens toward the south 

and southeast. The sand units grade southward from coarse sand 

and gravel to finer sediments and become increasingly subdivided by clay units. Eastward, toward the Atchafalaya River 

area, the Chicot aquifer system is overlain by and hydraulically 

connected to the Atchafalaya aquifer (Nyman, 1984, p. 4).

The Chicot aquifer system has been divided into three subregions in Louisiana based on the occurrence of major clay 

units. In the northern part of the study area, which includes the 

outcrop area, the aquifer system is undifferentiated, mainly consisting of a single massive sand. The approximate southern 

boundary of the massive sand is shown in figure 1. South of the 

massive sand, from eastern parts of Calcasieu and Cameron Parishes to the Atchafalaya River, the Chicot aquifer system 

includes an upper and lower sand unit (Whitman and Kilburn, 

1963, p. 10). In most of Calcasieu Parish and central and western Cameron Parish, the aquifer system is subdivided into the 

“200-,” “500-,” and “700-foot” sands, named after their depths 

of occurrence in the Lake Charles area (Jones, 1950b, p. 2). The 

“200-foot” sand is stratigraphically equivalent to, and continuous with, the upper sand. Figure 3 shows a partial hydrogeologic column of aquifers and aquifer systems in southwestern 

Louisiana.

Recharge to the Chicot aquifer system is from infiltration 

of rainfall, vertical leakage, and lateral flow. Recharge from 

rainfall occurs in areas where the system crops out in northern 

Allen, Beauregard, and Evangeline Parishes and in southern 
6 Withdrawals, Water Levels, and Specific Conductance in the Chicot Aquifer System

Rapides and Vernon Parishes (fig. 1). In these areas, precipitation infiltrates sandy soil and moves slowly downdip toward 

points of discharge. Recharge from vertical leakage occurs 

through overlying and underlying confining units. Recharge by 

lateral movement of water occurs from the Atchafalaya aquifer 

(Nyman and others, 1990, p. 14). A computer simulation of the 

aquifer system indicated that, under 1981 conditions, more than 

90 percent of the water entering the Chicot aquifer system was 

discharged as pumpage, and 65 percent of the water pumped 

from the rice-farming area was supplied by recharge from the 

surface (Nyman and others, 1990, p. 33).

Withdrawals and Water Levels

During most of 1999 and 2000, southwestern Louisiana 

experienced below-average precipitation compared to the 

30-year period 1971-2000 (fig. 4) and moderate to severe 

drought conditions (Louisiana Office of State Climatology, 

1999-2003). Consequently, ground-water withdrawals for rice 

irrigation increased substantially during this period (fig. 2) (Sargent, 2002, p. 127). In addition, many coastal streams and 

canals normally used for irrigation supplies were inundated by 

saltwater from the Gulf of Mexico because of the lack of freshwater flushing that normally occurs after precipitation (Louisiana State University Agricultural Center, 2000). A comparison 

of data in water-use reports for 1990, 1995, and 2000, indicates 

that surface-water withdrawal rates for rice irrigation decreased 

and ground-water withdrawal rates for rice irrigation increased 

in Cameron and Vermilion Parishes in 2000 (Lovelace, 1991; 

Lovelace and Johnson, 1996; Sargent, 2002), presumably to 

offset the loss of surface-water supplies. 

The total water requirement for rice cultivation during the 

growing season, which typically extends from February 

through June, is between 36 and 42 in. During an average year, 

about half of this water is supplied by precipitation and half is 

supplied by irrigation (Covay and others, 1992). Zack (1971) 

showed that the amount of ground water withdrawn in southwestern Louisiana in any particular year is inversely proportional to the total precipitation during the rice-growing season. 

Seasonal water withdrawals for rice irrigation typically begin in 

February and end in June. Consequently, water levels in the 

Chicot aquifer system typically decline from February through 

June in the rice-farming areas and potentiometric-surface maps 

for June generally show the lowest annual water levels (Lovelace and others, 2002). After June, water levels typically begin 

to recover (rise) and potentiometric-surface maps for January 

generally show the highest annual water levels (Lovelace and 

others, 2001).

To determine the magnitude and areal extent of waterlevel declines caused by seasonal ground-water withdrawals for 

rice irrigation, water-level data from 141 wells screened in the 

massive, upper, and “200-foot” sands (table 1) were collected. 

These data were used to construct potentiometric-surface maps 

of the Chicot aquifer system for June 2002 and January 2003.

During June 2002, the highest water level measured in the 

Chicot aquifer system, more than 160 ft above NGVD 29, was 

measured in the outcrop area in northern Beauregard Parish 

(fig. 5). Water levels were more than 40 ft below NGVD 29 in 

parts of Acadia, Calcasieu, Evangeline, Jefferson Davis, and 

adjacent parishes, in an area that generally coincides with ricefarming areas. The lowest water level, 80 ft below NGVD 29, 

was measured at well Ev-751 in southern Evangeline Parish. A 

comparison of the shapes and locations of the -50-ft, -60-ft, and

-70-ft contours on the potentiometric-surface maps for June 

2000 (Lovelace and others, 2001, fig. 3) and June 2002 (fig. 5) 

indicates that water levels in the Chicot aquifer system 

responded similarly to water withdrawals for rice irrigation 

during the 2000 and 2002 rice-growing seasons.

System Series Aquifer system

Aquifer

Outcrop area Lake Charles area East of Lake 

Charles

Quaternary

Pleistocene

Chicot aquifer 

system

Chicot aquifer, undifferentiated (massive 

sand)

“200-foot” sand of Lake 

Charles area

Chicot aquifer, 

upper sand unit

“500-foot” sand of Lake 

Charles area

“700-foot” sand of Lake 

Charles area

Chicot aquifer, 

lower sand unit

Figure 3. Partial hydrogeologic column of aquifers in southwestern Louisiana (modified from Lovelace and Lovelace, 1995, p. 10).
Withdrawals and Water Levels 7

During January 2003, the highest water levels, more than 

160 ft above NGVD 29, were measured in the outcrop area of 

the Chicot aquifer system in northern Beauregard Parish (fig. 

6). Water levels were more than 30 ft below NGVD 29 in parts 

of Acadia, Calcasieu, Evangeline, Jefferson Davis, and adjacent 

parishes, in an area that generally coincides with rice-farming 

areas (fig. 6). The lowest water levels, more than 60 ft below 

NGVD 29, were measured in wells Ac-929 in northern Acadia 

Parish and Ev-79 in southern Evangeline Parish. The similarities between the shapes and locations of the -40-ft and -50-ft 

contours on the potentiometric-surface maps for January 2001 

(Lovelace and others, 2002, fig. 1) and January 2003 (fig. 6) 

indicate that water levels in the Chicot aquifer system recovered 

to similar levels after the 2000 and 2002 rice-growing seasons.

From June 2002 to January 2003, water levels recovered 

throughout most of the Chicot aquifer system in the study area 

in response to reduced withdrawals after the rice-growing season (fig. 7). Throughout much of the aquifer system, water levels recovered less than 5 ft. However, in most of Acadia and Jefferson Davis Parishes, southern Evangeline Parish, and 

southeastern Calcasieu Parish, in an area that generally coincides with rice-farming areas, water levels generally recovered 

between 5 and 20 ft. The magnitude of the water-level increase 

and the shape of the area over which water levels recovered 

more than 5 ft are generally consistent with the water-level 

recovery that occurred between June 2000 and January 2001 

(Lovelace and others, 2002, fig. 4). The water-level changes 

shown in figure 7 and the previous water-level-change map are 

typical of the magnitude and areal extent of seasonal waterlevel fluctuations that occur in the Chicot aquifer system in 

response to seasonal ground-water withdrawals for rice irrigation.

To determine the duration of seasonal water-level declines 

due to ground-water withdrawals for rice irrigation, water levels 

in the Chicot aquifer system were measured hourly at five wells 

in the rice-farming areas during 2000-03 (fig. 8). The water levels at these wells typically declined between 10 and 25 ft, beginning in February or March and continuing through May or June. 

After June, water levels began to recover and generally continued to rise until seasonal ground-water withdrawals began the 

following year. Slight water-level declines, which often 

occurred during October, probably were due to withdrawals for 

DEPARTURE FROM NORMAL MONTHLY PRECIPITATION, IN INCHES

YEAR

Jan.

Mar.

May

July

Sept.

Nov.

Jan.

Mar.

May

July

Sept.

Nov.

Jan.

Mar.

May

July

Sept.

Nov.

Jan.

Mar.

May

July

Sept.

Nov.

Jan.

Mar.

May

-5

0

5

10

15

1999 2000 2001 2002 2003

Figure 4. Departure from normal monthly precipitation (1971-2000) in southwestern Louisiana, January 1999 through June 2003 (Louisiana 

Office of State Climatology, 1999-2003).
OUTCROP AREA

Map credit: Modified from Official Map of Louisiana, Louisiana Department of Transportation and Development, 1986

LAND USED FOR RICE FARMING

(SOURCE: LOUISIANA DEPARTMENT

OF ENVIRONMENTAL QUALITY)

20

GENERAL DIRECTION OF GROUND-WATER

MOVEMENT

I-93

POTENTIOMETRIC CONTOUR -- Shows

 altitude at which water level would have

 stood in tightly cased wells. Dashed where

 approximately located. Interval 10 and 20

 feet. Datum is National Geodetic Vertical

 Datum of 1929

CONTROL POINT AND WELL NUMBER

BOUNDARY OF FRESHWATER EXTENT OF

THE CHICOT AQUIFER SYSTEM (modified

from Smoot, 1986)

S BINE

A

LAKE

A

CA

I

C

L

S EU

A

E

L

K

WHITE

LAKE

GRAND

LAKE

C

C S

U

AL A IE

RIVER

a ou B y

es d

Ca s nne

Merm t en au

Ri r ve

Vermilion River

Bayou

Teche

ATCHAFAL

YA

A

RIVER

B Y U

A O

U

U

Q

E

E

DE

TOR

E

TU

MISSISSIPPI

IV

R

ER

Bayou

ezpi ue N q

ER

D

CALCASIEU RIVER

I R VER

Houston

River

VERNON

CALCASIEU

RAPIDES

EVANGELINE

AVOYELLES

ST.

LANDRY

JEFFERSON

DAVIS

ACADIA

T

E

LAFAYE

T

ST.

MARTIN

POINTE

U

CO

PEE

CAMERON

VERMILION

IBERIA

ST.

MARY

Lake Charles

Cameron

Crowley

Jennings

Abbeville

Lafayette

St. Martinville

New Iberia

Franklin

DeRidder

Leesville

Oberlin

Ville Platte

Alexandria

Marksville

Opelousas

New Roads

Gulf of Mexico

31° 00 ́

93° 00 ́ 92° 30 ́ 92° 00 ́ 91° 30 ́

29° 30 ́

30° 00 ́

30° 30 ́

93° 30 ́

E SABIN

RIVER

BEAUREGARD

ALLEN

EXPLANATION

LOUISIANA

TEXAS

MISSISSIPPI

ARKANSAS

Index Map

Study Area

5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

0

#

#

#

# #

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

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#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

# #

#

#

#

#

#

#

#

#

#

#

#

#

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#

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#

#

#

# #

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#

#

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#

#

#

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#

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#

#

#

#

#

#

#

#

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#

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#

# #

#

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#

#

#

#

#

#

#

#

#

#

0

140

120

100

40

60

80

20

160

0

-40

-30

-40

-50

-50

-60

20

-20

20 -

60 -

-30

-20

0

02

40

0

-20

3- 0

-40

-50

-60

60

80

100

120

-30

0

-70

-40

-50

-80

No data

Ac- 24

Ac- 189

AC- 294

Ac- 296 Ac- 326

Ac- 334

Ac- 363

Ac- 376

Ac- 382

Ac- 428

Ac- 464

Ac- 475

Ac- 500

Ac- 537

Ac- 539

Ac- 618

Ac- 628

Ac- 669

Ac- 828

Ac- 836

Al- 6

Al- 215

Al- 241

Al- 283

Al- 294

Al- 304

Be- 367

Be- 430

Be- 431

Be- 433

Be- 435

Be- 439

Be- 440

Be- 446

Be- 457

Be- 469

Cn- 80l

Cn- 90

Cn- 92

Cn- 93

Cn- 118

Cu- 168

Cu- 395 Cu- 642

Cu- 771

Cu- 843

Cu- 962 Cu- 854

Cu- 967

Cu- 968 Cu- 971

Cu- 975

Cu- 990

Cu-1066

Cu-1159

Cu-1245 Cu-1422

Cu-6680Z

Cu-7082Z

Ev- 23

Ev- 229

Ev- 500

Ev- 547

Ev- 606

Ev- 659

Ev- 665

Ev- 667

Ev- 679

Ev- 680

Ev- 751

I- 19

I- 93

JD- 31

JD- 33

JD- 166

JD- 222

JD- 298

JD- 317

JD- 353

JD- 401

JD- 406

JD- 470

JD- 485A JD- 492

JD- 493

JD- 581

JD- 740

JD- 751

JD- 772

JD- 835

JD- 848

Lf- 524

Lf- 823

Lf- 914

Lf- 958

SL- 179

SL- 190

SL- 331

SL- 347

SL- 392

SL- 412

SL- 566

SM- 57U

SMn- 103

Ve- 28

Ve- 442

Ve- 501

Ve- 556

Ve- 586

Ve- 639

Ve- 654

Ve- 764

Ve- 882

Ve-1134

Ve-1152

Ve- 460

Ve- 637L

Ve- 637U

Ve- 630U

Ve- 629L

Ve- 629U

Figure 5. Potentiometric surface of the massive, upper, and “200-foot” sands of the Chicot aquifer system in southwestern Louisiana, June 2002.

JD- 9

Ev-UR008

Ev- 673

Ev- 79

SMn- 109

8 Withdrawals, Water Levels, and Specific Conductance in the Chicot Aquifer System

E

A

T

X

S
OUTCROP AREA

20 POTENTIOMETRIC CONTOUR -- Shows

 altitude at which water level would have

 stood in tightly cased wells. Dashed where

 approximately located. Interval 10 and 20

 feet. Datum is National Geodetic Vertical

 Datum of 1929

Figure 6. Potentiometric surface of the massive, upper, and “200-foot” sands of the Chicot aquifer system in southwestern Louisiana, January 2003.

Map credit: Modified from Official Map of Louisiana, Louisiana Department of Transportation and Development, 1986

LAND USED FOR RICE FARMING

(SOURCE: LOUISIANA DEPARTMENT

OF ENVIRONMENTAL QUALITY)

GENERAL DIRECTION OF GROUND-WATER

MOVEMENT

I-93 CONTROL POINT AND WELL NUMBER

BOUNDARY OF FRESHWATER EXTENT OF

THE CHICOT AQUIFER SYSTEM (modified

from Smoot, 1986)

S BINE

A

LAKE

A

CA

I

C

L

S EU

A

E

L

K

WHITE

LAKE

GRAND

LAKE

C

C S

U

AL A IE

RIVER

a ou B y

es d

Ca s nne

Merm t en au

Ri r ve

Vermilion River

Bayou

Teche

ATCHAFAL

YA

A

RIVER

B Y U

A O

U

U

Q

E

E

DE

TOR

E

TU

MISSISSIPPI

IV

R

ER

Bayou

ezpi ue N q

ER

D

CALCASIEU RIVER

I R VER

Houston

River

VERNON

CALCASIEU

RAPIDES

EVANGELINE

AVOYELLES

ST.

LANDRY

JEFFERSON

DAVIS

ACADIA

T

E

LAFAYE

T

ST.

MARTIN

POINTE

U

CO

PEE

CAMERON

VERMILION

IBERIA

ST.

MARY

Lake Charles

Cameron

Crowley

Jennings

Abbeville

Lafayette

St. Martinville

New Iberia

Franklin

DeRidder

Leesville

Oberlin

Ville Platte

Alexandria

Marksville

Opelousas

New Roads

Gulf of Mexico

31° 00 ́

93° 00 ́ 92° 30 ́ 92° 00 ́ 91° 30 ́

29° 30 ́

30° 00 ́

30° 30 ́

93° 30 ́

E SABIN

RIVER

BEAUREGARD

ALLEN

EXPLANATION

LOUISIANA

TEXAS

MISSISSIPPI

ARKANSAS

Index Map

Study Area

5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

0

140

120

100

40

60

80

20

160

0

-40

-50

-20

-60

50 -

-40

-30

20

40

0

- 02

-30

-40

-50

60-

60

80

100

120

-30

0

0

- 02

-40

-50

-20

-40

-30

-50

Ac- 189

Ac- 294

Ac- 296

Ac- 334

Ac- 351

Ac- 363

Ac- 475

Ac- 500 Ac- 539

Ac- 618

Ac- 628

Ac- 669

Ac- 836

Al- 6

Al- 215

Al- 241

Al- 283

Al- 293

Al- 294

Al- 304

Al- 396

Be- 367

Be- 430

Be- 431

Be- 433

Be- 435

Be- 439

Be- 440

Be- 443

Be- 457

Be- 461

Be- 469

Cn- 80L

Cn- 81L

Cn- 90

Cn- 92

Cn- 93

Cn- 118

Cu- 168

Cu- 395 Cu- 642

Cu- 771

Cu- 843

Cu- 854 Cu- 962

Cu- 967

Cu- 968

Cu- 971

Cu- 975

Cu- 990

Cu-1066

Cu-1245 Cu-1159

Cu-1386

Cu-1422

Cu-6680Z

Cu-7082Z

Ev- 23

Ev- 229

Ev- 500

Ev- 547

Ev- 606

Ev- 623

Ev- 659

Ev- 665

Ev- 667

Ev- 673

Ev- 679

Ev- 680

I- 19

I- 93

JD- 9

JD- 31

JD- 33

JD- 166

JD- 222

JD- 298

JD- 317

JD- 353

JD- 401

JD- 406

JD- 470

JD- 485A

JD- 492

JD- 493

JD- 740

JD- 751

JD- 772

JD- 835

JD- 848

Lf- 524

Lf- 662

Lf- 822

Lf- 822

Lf- 914

Lf- 958

SL- 142

SL- 179

SL- 190

SL- 392

SM- 57U

SMn- 103 SMn- 109

Ve- 28

Ve- 442 Ve- 460

Ve- 501

Ve- 586

Ve- 629L Ve- 629U

Ve- 630U

Ve- 637L

Ve- 637U

Ve- 639

Ve- 654

Ve- 764

Ve-1134 Ve- 882

Ve-1152

Ac- 825

Ac- 537

Ac- 326

Ac- 376

Ev- 79

SL- 331 SL- 412 Ev- 751

SL- 459

SL- 347 SL- 566

Ev-UR008

Ac- 24

Ac- 929

Ac- 464

Ac- 428

Be- 446

Ac- 876

Ac- 828

AC- 332

No data

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Withdrawals and Water Levels 9

E

A

T

X

S
LAND USED FOR RICE FARMING

(SOURCE: LOUISIANA DEPARTMENT

OF ENVIRONMENTAL QUALITY)

I-93

BOUNDARY OF FRESHWATER EXTENT OF

THE CHICOT AQUIFER SYSTEM (modified

from Smoot, 1986)

Figure 7. Water-level change in the massive, upper, and “200-foot” sands of the Chicot aquifer system in southwestern Louisiana, June 2002 to January 2003.

Map credit: Modified from Official Map of Louisiana, Louisiana Department of Transportation and Development, 1986

CONTROL POINT AND WELL NUMBER

S BINE

A

LAKE

A

CA

I

C

L

S EU

LA

EK

WHITE

LAKE

GRAND

LAKE

CALC SI U

A

E

RIVER

Ba ou y

des

n Ca nes

e m t M r en au

River

Ve io rmil n River

Bayou

Teche

T

F

A

CHA

ALAYA

RIVER

Y U

BA O

U

QUE

E

DE

TOR

UE

T

P

MISSISSIP I

RIV

RE

Bayou

ue Nezpiq

RED

CALCASIEU RIVER

RIVER

Houston

River

VERNON

CALCASIEU

RAPIDES

EVANGELINE

AVOYELLES

ST.

LANDRY

JEFFERSON

DAVIS

ACADIA

LAFAY

TTE

E

ST.

MARTIN

POINT

U

E CO

PEE

CAMERON

VERMILION

IBERIA

ST.

MARY

Lake Charles

Cameron

Crowley

Jennings

Abbeville

Lafayette

St. Martinville

New Iberia

Franklin

DeRidder

Leesville

Oberlin

Ville Platte

Alexandria

Marksville

Opelousas

New Roads

A

TEX

S

Gulf of Mexico

31° 00 ́

93° 00 ́ 92° 30 ́ 92° 00 ́ 91° 30 ́

29° 30 ́

30° 00 ́

30° 30 ́

93° 30 ́

E SABIN

RIVER

BEAUREGARD

ALLEN

EXPLANATION

LOUISIANA

TEXAS

MISSISSIPPI

ARKANSAS

Index Map

Study Area

5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

0

#

#

# #

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

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# #

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# #

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#

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#

#

AC- 189

AC- 294

AC- 296

AC- 334

AC- 363

AC- 475

AC- 500

AC- 539

AC- 618

AC- 628

AC- 669

AC- 836

AL- 6

AC- 828

AL- 215

AL- 241

AL- 283

AL- 294

AL- 304

BE- 367

BE- 430

BE- 457

BE- 469

CN- 80L

CN- 90

CN- 92

CN- 93

CN- 118

CU- 168

CU- 395

CU- 642 CU- 771

CU- 843

CU- 962 CU- 854

CU- 967

CU- 968

CU- 971

CU- 975

CU- 990

CU-1066

CU-1245 CU-1159

CU-1422

CU-7082Z

EV- 23

EV- 229

EV- 500

EV- 547

EV- 606

EV- 623

EV- 659

EV- 665

EV- 667

EV- 673

EV- 679

EV- 680

I- 19

I- 93

JD- 9

JD- 31

JD- 33

JD- 166

JD- 222

JD- 298

JD- 317

JD- 353

JD- 401

JD- 406

JD- 470

JD- 485A JD- 492

JD- 493

JD- 740

JD- 751

JD- 772

JD- 835

JD- 848

LF- 524

LF- 914

LF- 958

SL- 179

SL- 190

SM- 57U

VE- 28

VE- 442

VE- 460

VE- 501

VE- 586

VE- 629L

VE- 629U

VE- 630U

VE- 637L

VE- 637U

VE- 639

VE- 654

VE- 764

VE- 882

VE-1134

VE-1152

AC- 537

AC- 326

AC- 376

EV- 79

SL- 331 SL- 412 EV- 751

SL- 566 SL- 347

EV-UR008

AC- 24

AC- 464

AC- 428

BE- 446

SMN- 109

CU- 6680Z

BE- 440

BE- 439

BE- 435

BE- 433

BE- 431

-10 - -5 

 -5 - 0

 0 - 5

 5 - 10

 10 - 20

 20 - 30

WATER-LEVEL CHANGE, IN FEET

(dashed where approximate)

No data

10 Withdrawals, Water Levels, and Specific Conductance in the Chicot Aquifer System
Specific Conductance 11

other purposes. The largest fluctuation of water levels, about 

25 ft, was noted at well JD-485A. Water levels at this well probably are influenced by nearby active irrigation wells. Water levels fluctuated only about 10 ft annually at wells Ev-229 and 

Cn-92, which are located near the edge of the rice-farming area 

(fig. 1).

Specific Conductance

Specific conductance, as used in this report, is the primary 

indicator of saltwater (chloride concentration greater than 

250 mg/L). This chloride concentration correlates to a specific 

conductance value of about 1,300 μS/cm in water from the Chicot aquifer system (fig. 9).

When used for irrigation, saltwater can inhibit rice growth 

and reduce grain yields (Grattan and others, 2002). Hill [n.d.] 

developed guidelines for using saltwater on rice in Louisiana 

and a table of commonly accepted tolerance of rice to selected 

saltwater concentrations (table 2). Hill indicates that water with 

a specific conductance value greater than about 2,000 μS/cm 

can adversely affect rice during early stages of development. 

Hill also indicates that continued use of irrigation water with a 

specific conductance value greater than about 1,000 μS/cm can 

cause a buildup of salt in the soil that could damage both crop 

and soil.

Concentrations of salt, as sodium chloride, commonly 

referred to as “total salts,” in parts per million and grains per 

gallon (table 2), are used by many farmers and agricultural 

agents in Louisiana. The concentration of total salts, in parts per 

million, is approximately equivalent to the concentration of 

total dissolved solids and is calculated by multiplying the specific conductance value, in microsiemens per centimeter, by 

0.64 (E.R. Funderburg, Louisiana State University Agricultural 

Center, written commun., 2000). The concentration of total 

salts, in grains per gallon, can be calculated by dividing the specific conductance value by 26.56 or by dividing the concentration of total salts, in parts per million, by 17.14. 

Data collected during the period 1943 to 2003 from 

1,355 wells screened in the massive, upper, and “200-foot” 

sands of the Chicot aquifer system and the Atchafalaya aquifer 

were used to delineate areas having similar specific conductance values and determine areas where wells are affected by 

saltwater (fig. 10). Areas having similar specific conductance 

Figure 8. Hourly water levels at selected wells screened in the Chicot aquifer system in southwestern Louisiana, 2000-03 

(see fig. 1 for well locations).
12 Withdrawals, Water Levels, and Specific Conductance in the Chicot Aquifer System

0 500 1,000 1,500 2,000 2,500 3,000

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER AT 25 DEGREES CELSIUS

0

100

200

300

400

500

600

700

800

Chloride concentration = (0.2856 x specific conductance) - 121.2

R2 = 0.9342

CHL

ORIDE C

ONCEN

TRATION, IN MILLIGRAMS PER LI

TER

Figure 9. The relation between specific conductance values and chloride concentrations in the Chicot aquifer system in

southwestern Louisiana.

Table 2. Commonly accepted tolerance of rice to selected saltwater concentrations (modified from Hill, [n.d]).

Specific conductance,

in microsiemens per 

centimeter at 25 degrees 

Celsius

Salt, as sodium 

chloride, in parts per 

million

Salt, as sodium 

chloride, in grains per 

gallon

Stage of growth

938 600 35 Tolerable at all stages, not harmful.

2,031 1,300 75 Rarely harmful and only to seedlings after the soil is 

dry enough to crack. Tolerable from tillering on to 

heading.

2,656 1,700 100 Harmful before tillering. Tolerable from jointing to 

heading.

5,312 3,400 200 Harmful before booting. Tolerable from booting to 

heading.

7,969 5,100 300 Harmful to all stages of growth. This concentration 

stops growth and can only be used at the heading stage 

when the soil is saturated with freshwater.
WESTERN BOUNDARY OF THE

ATCHAFALAYA AQUIFER

(modified from Nyman, 1989)

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151 - 500

APPROXIMATE BOUNDARY OF FRESHWATER

IN THE CHICOT AQUIFER SYSTEM

(modified from Smoot, 1986)

1 - 150

Greater than 1,000

501 - 1,000

AREAS OF SIMILAR SPECIFIC CONDUCTANCE, IN

MICROSIEMENS PER CENTIMETER AT 25 DEGREES CELSIUS

(FROM DATA COLLECTED 1943-2003)

CONTROL POINT AND SPECIFIC CONDUCTANCE, IN

MICROSIEMENS PER CENTIMETER AT 25 DEGREES CELSIUS

151 - 500

1 - 150

1,001 - 2,000

501 - 1,000

2,000 - 12,500

LAND USED FOR RICE FARMING

(SOURCE: LOUISIANA DEPARTMENT

OF ENVIRONMENTAL QUALITY)

Figure 10. Specific conductance in the massive, upper, and “200-foot” sands of the Chicot aquifer system in southwestern Louisiana.

Map credit: Modified from Official Map of Louisiana, Louisiana Department of Transportation and Development, 1986

S BINE

A

LAKE

ALCASIE

C

U

LAKE

WHITE

LAKE

GRAND

LAKE

CA C S

U

L A IE

RIVER

Ba ou y

des

n Ca nes

m Mer entau

Ri r ve

Vermilion River

Bayou

Teche

ATCHAFAL

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A

RIVER

B Y U

A O

QUEUE

DE

TOR

UE

T

P

MISSISSIP I

RIV

RE

Bayou

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RED

CALCASIEU RIVER

I R VER

Houston

River

VERNON

CALCASIEU

RAPIDES

EVANGELINE

AVOYELLES

ST.

LANDRY

JEFFERSON

DAVIS

ACADIA

LAFA

TTE

YE

ST.

MARTIN

POINT

U

E CO

PEE

CAMERON

VERMILION

IBERIA

ST.

MARY

Lake Charles

Cameron

Crowley

Jennings

Abbeville

Lafayette

St. Martinville

New Iberia

Franklin

DeRidder

Leesville

Oberlin

Ville Platte

Alexandria

Marksville

Opelousas

New Roads

A

TEX

S

Gulf of Mexico

31° 00 ́

93° 00 ́ 92° 30 ́ 92° 00 ́ 91° 30 ́

29° 30 ́

30° 00 ́

30° 30 ́

93° 30 ́

E SABIN

ER RIV

BEAUREGARD

ALLEN

EXPLANATION

LOUISIANA

TEXAS

MISSISSIPPI

ARKANSAS

Index Map

Study Area

5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

0

Iowa

Specific Conductance 13
14 Withdrawals, Water Levels, and Specific Conductance in the Chicot Aquifer System

values were mapped based on the range of specific conductance 

values for water from the majority of wells sampled within an 

area. Specific conductance values at some wells are outside of 

the range shown for a particular area, but also are included in 

figure 10. For the purposes of this report, the maximum specific 

conductance value measured from a well was used when multiple measurements had been made for that well. Field specific 

conductance values were used when available; laboratory specific conductance values were used when field values were 

unavailable.

In and near the outcrop area (fig. 1), specific conductance 

values generally are less than 150 μS/cm (fig. 10). Specific conductance values increase south and east from the outcrop area. 

Specific conductance values generally range from 151 to 

500 μS/cm in rice-farming areas of northwestern Acadia Parish, 

southeastern Allen Parish, western Evangeline Parish, and 

northern and central Jefferson Davis Parish. Specific conductance values generally range from 501 to 1,000 μS/cm in most 

of the remaining rice-farming areas. Specific conductance values often exceed 1,000 μS/cm in an area along the border 

between Calcasieu and Jefferson Davis Parishes near Iowa; 

parts of northeastern Cameron Parish; an area of northwestern 

and central St. Landry Parish; parts of Vermilion Parish; and 

several areas along the eastern boundary of the study area where 

the Chicot aquifer system merges with the Atchafalaya aquifer. 

The maximum specific conductance value, 12,100 μS/cm, is 

from a well in Cameron Parish.

Fresh ground water is available throughout much of Louisiana, but is underlain by saltwater at some depth. The maximum depth of freshwater in an area is called the base of freshwater. In much of southwestern Louisiana, the base of 

freshwater within the Chicot aquifer system occurs at depths 

greater than 800 ft below NGVD 29 (Harder and others, 1967, 

pl. 6). In coastal parishes, the base of freshwater occurs within 

the Chicot aquifer system at depths less than 400 ft below 

NGVD 29 in several areas (Harder and others, 1967, pl. 6; 

Nyman, 1984, pl. 2). Specific conductance in wells sampled in 

these areas generally exceeds 1,000 μS/cm (fig. 10). In parts of 

northwestern, central, and eastern St. Landry Parish, where the 

base of freshwater occurs at depths less than 200 ft below 

NGVD 29 (Harder and others, 1967, pl. 6; Hosman and others, 

1970, pl. 1), specific conductance generally exceeds 

1,000 μS/cm.

Where the base of freshwater occurs within an aquifer, two 

distinct layers may be formed because saltwater is denser than 

freshwater. Because of the density difference, the contact 

between the freshwater and saltwater within an aquifer may 

form a mixing zone or interface. In areas of the Chicot aquifer 

system where a freshwater-saltwater interface is present 

(Nyman, 1984), high-capacity wells pumping from the freshwater part of the aquifer can draw saltwater from the lower part 

of the aquifer. As pumping continues, an increasing proportion 

of water drawn into the well could come from the lower, more 

saline part of the aquifer (Nyman, 1984, p. 11). According to 

Nyman (1984, p. 11), this saltwater coning, also termed “upconing,” is the most common cause of wells pumping saltwater in 

southwestern Louisiana. Some factors affecting the rate of 

upconing include: (1) the depth from the bottom of the well 

screen to the base of the aquifer, (2) the pumping rate, (3) the 

duration of pumping, (4) the vertical permeability of the aquifer, (5) the thickness of the aquifer, and (6) the difference in 

density between the two waters (Nyman, 1984, p. 11). Decreasing the rate or duration of pumping and screening high-capacity 

wells as far above the base of freshwater as possible could 

reduce the potential for upconing saltwater.

Specific conductance was measured in 521 water samples 

from 166 wells screened in the Chicot aquifer system or the 

Atchafalaya aquifer during 2000-03 to determine whether water 

from wells in areas where saltwater is present is becoming saltier. Most of the sampled wells were used for irrigation. Figures 

11 and 12 show the locations of sampled wells; well construction and specific conductance data are included in table 3. 

Well records from the Louisiana Department of Transportation and Development indicate that almost 100 percent of the 

3,750 registered irrigation wells in the parishes where samples 

were collected are screened in the Chicot aquifer system or 

Atchafalaya aquifer (Z. “Bo” Bolourchi, Louisiana Department 

of Transportation and Development, written commun., 2003). 

Well-depth and screen-depth data were unavailable for 61 of the 

sampled wells. Although these wells are assumed to be screened 

in the Chicot aquifer system or the Atchafalaya aquifer because 

of their locations and use, the data are considered ancillary and 

specific conductance at these wells were not compared with 

specific conductance in wells of known depth.

Specific conductance values exceeded 1,000 μS/cm in 

water samples from wells in Calcasieu, Cameron, Jefferson 

Davis, St. Landry, St. Martin, St. Mary, and Vermilion Parishes. 

Specific conductance values exceeded 2,000 μS/cm in only two 

wells (table 3)—well Cu-UR003, which is an irrigation well 

located about 2 mi south of Iowa, and well Ve-637L, which is a 

USGS observation well used to monitor saltwater encroachment in east-central Vermilion Parish.

Only a few wells used for irrigation were sampled frequently enough throughout the period of the study to determine 

whether any trends in specific conductance were evident 

(table 3, fig. 13). For most of these wells, specific conductance 

values usually varied within a narrow range. However, specific 

conductance values increased steadily at well Cu-UR003 from 

1,090 μS/cm in April 2000 to 2,860 μS/cm in April 2003 

(table 3, fig. 13). Nearby wells, such as D-860 (table 3, fig. 13), 

did not show similar increases.

Specific conductance was measured hourly at two irrigation wells, Cu-1386 (2001-03) and Cn-196 (2000-03) (fig. 14). 

Specific conductance values were greater than 1,000 μS/cm in 

both wells, indicating the presence of saltwater near the wells. 

The data indicate that several short pumping events took place 

at each well during the rice-growing seasons over the 3-year 

period of study. Specific conductance values generally fluctu- 
WESTERN BOUNDARY OF THE ATCHAFALAYA

AQUIFER (modified from Nyman, 1989)

See fig. 12

151 - 500

APPROXIMATE BOUNDARY OF FRESHWATER

IN THE CHICOT AQUIFER SYSTEM

(modified from Smoot, 1986)

1 - 150

Greater than 1,000

501 - 1,000

AREAS OF SIMILAR SPECIFIC CONDUCTANCE, IN MICROSIEMENS

PER CENTIMETER AT 25 DEGREES CELSIUS, IN THE MASSIVE,

UPPER, AND “200-FOOT” SANDS OF THE CHICOT AQUIFER

SYSTEM (FROM DATA COLLECTED 1943-2003)

WELL LOCATION AND NUMBER

Figure 11. Location of wells sampled for specific conductance in southwestern Louisiana, 2000-03.

Map credit: Modified from Official Map of Louisiana, Louisiana Department of Transportation and Development, 1986

S BINE

A

LAKE

I

CALCAS EU

E

LAK

WHITE

LAKE

GRAND

LAKE

C

CAL ASIEU

RIVER

Ba ou y

des a C nnes

Mermentau

River

Vermilion River

Bayou

Teche

ATCHAFALAYA

RIVER

BAYOU

QU

UE

E

DE

R

TO

TUE

MISSISSIPPI

RIVER

B you a

Nezpique

ER

D

CALCASIEU RIVER

RIVER

Houston

River

VERNON

CALCASIEU

RAPIDES

EVANGELINE

AVOYELLES

ST.

LANDRY

JEFFERSON

DAVIS

ACADIA T

LAFAYE

TE

ST.

MARTIN

E

POINTE COUPE

CAMERON

VERMILION

IBERIA

ST.

MARY

Lake

Charles

Cameron

Crowley

Jennings

Abbeville

Lafayette

St. Martinville

New Iberia

Franklin

DeRidder

Leesville

Oberlin

Ville Platte

Alexandria

Marksville

Opelousas

New Roads

A

TEX

S

Gulf of Mexico

31° 00 ́

93° 00 ́ 92° 30 ́ 92° 00 ́ 91° 30 ́

29° 30 ́

30° 00 ́

30° 30 ́

93° 30 ́

S I E AB N

VER RI

BEAUREGARD

ALLEN

EXPLANATION

LOUISIANA

TEXAS

MISSISSIPPI

ARKANSAS

Index Map

Study Area

5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

0

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Ac- 3

Ac- 69

Ac- 80

Ac- 113

Ac- 147

Ac- 179

Ac- 204

Ac- 222

Ac- 369

Ac- 394

Ac- 446

Ac- 475 Ac- 477

Ac- 548

Ac- 558

Ac- 618

Ac- 809 Ac- 711

Ac- 822

Ac- 836 Ac- 848

Ac- 855

Ac- 857

Ac- 919

Ac- 929

Ac- 971

Ac- 980

Ac-UR001

Ac-UR004

Ac-UR006

Ac-UR007

Ac-UR008

Cu- 688

Cu- 771

Cu- 787

Cu- 960

Cu-1385

Cu-UR001

Cu-UR002

Cn- 80L

Cn- 90

Ev- 673

Ev- 834

Ev- 879

Ev- 889

Ev- 923

Ev-UR001

Ev-UR003

Ev-UR004

Ev-UR005

Ev-UR006

Ev-UR007

Ev-UR009

 I- 93

JD- 50

JD- 79

JD- 135 JD- 176

JD- 469

JD- 491

JD- 493

JD- 499

JD- 523

JD- 650

JD- 727

JD- 751

JD- 772

JD- 867

JD- 871

JD-UR002

JD-UR011

JD-UR012

JD-UR013

JD-UR014

JD-UR017

Lf- 524

SL- 142

SL- 331

SL- 345

SL- 459

SL- 564

SL- 673

SL- 714 SL-UR001

SL-UR004 SL-UR005

SL-UR006

SL-UR007

SMn- 109

SM- 57U

Ve- 170

Ve- 312

Ve- 384

Ve- 425

Ve- 426

Ve- 432

Ve- 460

Ve- 586

Ve- 637L

Ve- 639

Ve- 725

Ve- 733

Ve-1081

Ve-1123

Ve-1152

Ve-UR001

Ve-UR002

Ve-UR003

Ve-UR004

Ve-UR005

Ve-UR007

Ve-UR010

Ve-UR011

Ve-UR012

Ac- 451

Ac- 809

Specific Conductance 15
0 5 MILES

0 5 KILOMETERS

Cu- 168

Cu- 171

Cu- 633

Cu- 812

Cu-1012

Cu-1093

Cu-1211

Cu-1253

Cu-1287

Cu-1369

Cu-1386

Cu-1387

Cu-1389

Cu-1391

Cu-1397

Cu-1398

Cu-1402

Cu-1415

Cu-1422

Cu-1432

Cu-9069Z

Cu-UR003

Cu-UR005

Cu-UR006

Cu-UR009

Cu-UR010

Cu-UR015

Cu-UR016

Cu-UR019

Cu-UR004

Cn- 22

Cn- 92

Cn- 196

Cn- 197

Cn- 198

Cn-UR001

Cn-UR002

JD- 241

JD- 352

JD- 817

JD- 860

JD-UR006

JD-UR008

JD-UR019

JD-UR018 JD-UR015

JD-UR009

JD-UR020

JD-UR022

JD- 447

Cu-1092

#

#

#

#

#

#

#

#

#

#

# # #

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

#

151 - 500

EXPLANATION

Greater than 1,000

501 - 1,000

AREAS OF SIMILAR SPECIFIC CONDUCTANCE, IN

MICROSIEMENS PER CENTIMETER AT 25 DEGREES

CELSIUS, IN THE UPPER AND “200-FOOT” SANDS OF

THE CHICOT AQUIFER SYSTEM (FROM DATA

COLLECTED 1943-2003)

Cu- 812 # WELL LOCATION AND NUMBER

Lake Charles

Iowa

Moss

Bluff

Figure 12. Location of wells sampled for specific conductance near Iowa, Louisiana, 2000-03.

CALCASIEU

CAMERON

CALCASIEU

JEFFERSON DAVIS

CALCASIEU

JEFFERSO

N

DAVIS

Map credit: Modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0

93° 10 ́ 93° 05 ́ 93°00 ́ 92°55 ́

30° 20 ́

30° 15 ́

30° 10 ́

30° 05 ́

30° 00 ́

16 Withdrawals, Water levels, and Specific Conductance in the Chicot Aquifer System

Fenton

Lacassine

Bell City

Hayes

Sweet Lake

Holmwood
Specific Conductance 17

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER AT 25 DEGREES CELSIUS

1,000

1,100

1,200

1,300

1,400

1,500

 

1,000

1,500

2,000

2,500

3,000

 0

 100

 200

 300

 400

500

1,000

1,100

1,200

1,300

1,400

1,500

Well Cu-1253

Well Cu-UR003

Well JD-447

Well JD-860

2000 2001 2002 2003

YEAR

Figure 13. Specific conductance values at selected wells in southwestern Louisiana, 2000-03 (see figs. 11 and 12 for well locations).
18 Withdrawals, Water Levels, and Specific Conductance in the Chicot Aquifer System

Well Cu-1386

1,000

1,100

1,200

1,300

1,400

1,500

Well Cn-196

 900

1,000

1,100

1,200

1,300

1,400

2000 2001 2002 2003

SPECIFI

C

C

ONDU

CTAN

CE, IN MI

C

R

OSIEMENS PER 

CENTIMETER AT 25 DEG

REES 

CELSIUS

YEAR

Figure 14. Hourly specific conductance values during pumping at selected wells screened in the Chicot aquifer system in 

southwestern Louisiana, 2000-03 (see fig. 1 for well locations).
Summary 19

ated about 150 μS/cm at both wells (fig. 14). Specific conductance values often increased 50 μS/cm or more in the wells during the first few hours of a pumping event, then usually stabilized to fluctuations within a range of 10 to 20 μS/cm. No longterm trends in the specific conductance were evident in either 

well during the periods monitored.

Summary

The Chicot aquifer system is the principal source of fresh 

ground-water supplies in southwestern Louisiana. Much of the 

area is rural and rice cultivation is the primary agricultural 

activity. Withdrawals from the aquifer system, primarily for 

rice irrigation, have caused water levels to decline as much as 

100 feet beneath some rice-farming areas of southwestern Louisiana since the early 1900’s, creating an elongated cone of 

depression in the potentiometric surface over much of the 

region. About 540 million gallons per day were withdrawn from 

the Chicot aquifer system in southwestern Louisiana in 2000.

From 1990 to 2000, water levels at several observation 

wells screened in the Chicot aquifer system and located in ricefarming areas declined at an average rate of 1 to 2 feet per year. 

Some farmers and residents of southwestern Louisiana are concerned that water levels in the aquifer system may decline 

below pump intakes in their wells, leaving them without water. 

Water levels in some areas of the aquifer system also fluctuate 

seasonally, primarily in response to ground-water withdrawals 

for rice irrigation, and wells in these areas could be affected seasonally.

To determine the magnitude and areal extent of waterlevel declines caused by seasonal ground-water withdrawals for 

rice irrigation, water-level data were collected from 141 wells 

screened in the massive, upper, and “200-foot” sands of the Chicot aquifer system. These data were used to construct potentiometric-surface maps of the aquifer system for June 2002 and 

January 2003. During June 2002, water levels in the aquifer system were more than 40 feet below the National Geodetic Vertical Datum of 1929 (NGVD 29) in parts of Acadia, Calcasieu, 

Evangeline, and Jefferson Davis Parishes, in an area that generally coincides with rice-farming areas. The lowest water level, 

80 feet below NGVD 29, was measured in southern Evangeline 

Parish. During January 2003, water levels were more than 

30 feet below NGVD 29 in parts of Acadia, Calcasieu, Evangeline, and Jefferson Davis Parishes, in an area that generally 

coincides with rice-farming areas. The lowest water levels, 

more than 60 feet below NGVD 29, were measured in small 

areas of northern Acadia and southern Evangeline Parishes.

From June 2002 to January 2003, water levels recovered 

throughout most of the Chicot aquifer system in the study area 

in response to reduced withdrawals after the rice-growing season. Throughout much of the aquifer system, water levels 

recovered less than 5 feet. However, in most of Acadia and Jefferson Davis Parishes, southeastern Calcasieu Parish, and 

southern Evangeline Parish, in an area that generally coincides 

with rice-farming areas, water levels generally recovered 

between 5 and 20 feet. These water-level changes are typical of 

the magnitude and areal extent of seasonal water-level fluctuations that occur in the Chicot aquifer system in response to seasonal ground-water withdrawals for rice irrigation.

To determine the duration of seasonal water-level declines 

due to ground-water withdrawals for rice irrigation, water-levels in the Chicot aquifer system were measured hourly at five 

wells in the rice-farming area during 2000-03. Water levels at 

these wells typically declined between 10 and 25 feet, beginning in February or March and continuing through May or June. 

After June, water levels began to recover and generally continued to rise until seasonal ground-water withdrawals began the 

following year.

Saltwater in the Chicot aquifer system is a concern to farmers in southwestern Louisiana. Continued use of irrigation water 

having a specific conductance value greater than about 

1,000 μS/cm (microsiemens per centimeter at 25 degrees Celsius) can cause a buildup of salt in the soil that could damage 

both crop and soil. The presence of saltwater has been documented in the aquifer system beneath coastal parishes and in 

some areas where the aquifer system merges with the stratigraphically adjacent Atchafalaya aquifer. Seasonal pumping for 

rice irrigation has altered flow directions in the Chicot aquifer 

system and can induce lateral or upward movement of saltwater. 

Some irrigation wells screened in the aquifer system may be 

affected by saltwater encroachment, especially during periods 

of increased pumping in response to drought conditions.

Data collected during the period 1943 to 2003 from 

1,355 wells screened in the massive, upper, and “200-foot” 

sands of the Chicot aquifer system and the Atchafalaya aquifer 

were used to delineate areas having similar specific conductance values and determine areas where wells are affected by 

saltwater. Areas having similar specific conductance values 

were mapped based on the range of specific conductance values 

for water from the majority of wells sampled within an area.

Near the outcrop area, specific conductance values typically are less than 150 μS/cm. Specific conductance values 

increase south and east from the outcrop area. Specific conductance values generally range from 151 to 500 μS/cm in ricefarming areas of northwestern Acadia Parish, southeastern 

Allen Parish, western Evangeline Parish, and northern and central Jefferson Davis Parish. Specific conductance values generally range from 501 to 1,000 μS/cm in most of the remaining 

rice-farming areas. Specific conductance values often exceed 

1,000 μS/cm in an area along the border between Calcasieu and 

Jefferson Davis Parishes near Iowa, Louisiana; parts of northeastern Cameron Parish; an area of northwestern and central St. 

Landry Parish; parts of Vermilion Parish; and several areas 

along the eastern boundary of the study area where the Chicot 

aquifer system merges with the Atchafalaya aquifer. The maximum specific conductance value, 12,100 μS/cm, is from a well 

in Cameron Parish.
20 Withdrawals, Water Levels, and Specific Conductance in the Chicot Aquifer System

In areas of the Chicot aquifer system where a freshwatersaltwater interface is present, high-capacity wells pumping 

from the freshwater portion of the aquifer can draw saltwater 

from the lower part of the aquifer. Screening high-capacity 

wells as far above the base of freshwater as possible could 

reduce the potential for upconing saltwater.

To document specific conductance in wells during 

2000-03 and determine whether water from wells in areas 

where saltwater is present is becoming saltier, specific conductance was measured in 521 water samples from 166 wells 

screened in the Chicot aquifer system or the Atchafalaya aquifer 

during 2000-03. Specific conductance values exceeded 

1,000 μS/cm in water samples from wells in Calcasieu, Cameron, St. Landry, St. Martin, St. Mary, and Vermilion Parishes. 

Specific conductance values exceeded 2,000 μS/cm in only two 

wells—an irrigation well located about 2 miles south of Iowa 

and a USGS observation well used to monitor saltwater 

encroachment in east-central Vermilion Parish. Specific conductance values increased steadily at one well, from 

1,090 μS/cm in April 2000 to 2,860 μS/cm in April 2003. 

Nearby wells did not show similar increases.

Specific conductance was measured hourly at two irrigation wells during 2000-03. Specific conductance values were 

greater than 1,000 μS/cm in both wells, indicating the presence 

of saltwater near the wells. Specific conductance values generally fluctuated about 150 μS/cm at both wells, but no long-term 

trends in the specific conductance were evident in either well.

Selected References

Bieber, P.P., and Forbes, M.J., Jr., 1966, Pumpage of water in 

Louisiana, 1965: Department of Conservation, Louisiana 

Geological Survey, and Louisiana Department of Public 

Works Water Resources Pamphlet 20, 8 p.

Cardwell, G.T., and Walter, W.H., 1979, Pumpage of water in 

Louisiana, 1975: Louisiana Department of Transportation 

and Development, Office of Public Works Water Resources 

Special Report no. 2, 15 p.

Covay, K.J., Sturrock, A.M., Jr., and Sasser, D.C., 1992, Water 

requirements for growing rice in southwestern Louisiana, 

1985-86: Louisiana Department of Transportation and 

Development Water Resources Technical Report no. 52, 

14 p.

Dial, D.C., 1970, Pumpage of water in Louisiana, 1970: Department of Conservation, Louisiana Geological Survey, and 

Louisiana Department of Public Works Water Resources 

Pamphlet 26, 10 p.

Fader, S.W., 1957, An analysis of contour maps of 1955 water 

levels, with a discussion of saltwater problems in southwestern Louisiana: Department of Conservation, Louisiana Geological Survey, and Louisiana Department of Public Works 

Water Resources Pamphlet no. 4, 27 p.

Fishman, M.J., and Friedman, L.C., 1989, Methods for determination of inorganic substances in water and fluvial sediments: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A1, 545 p.

Grattan, S.R., Zeng, Linghe, Shannon, M.C., and Roberts, S.R., 

2002, Rice is more sensitive to salinity than previously 

thought: California Agriculture, v. 56, no. 6, p. 189-195.

Harder, A.H., 1960, Water levels and water-level contour maps 

for southwestern Louisiana, 1958 and 1959: Department of 

Conservation, Louisiana Geological Survey, and Louisiana 

Department of Public Works Water Resources Pamphlet no. 

8, 27 p.

Harder, A.H., Kilburn, Chabot, Whitman, H.M., and Rogers, 

S.M., 1967, Effects of ground-water withdrawals on water 

levels and saltwater encroachment in southwestern Louisiana: Department of Conservation, Louisiana Geological Survey, and Louisiana Department of Public Works Water 

Resources Bulletin no. 10, 56 p.

Harris, G.D., 1904, Underground waters of southern Louisiana, 

with discussions of their uses for water supplies and for rice 

irrigation, by M.L. Fuller: U.S. Geological Survey WaterSupply Paper 101, 98 p.

Hill, Lewis, [n.d.], A general guide for using saltwater on rice: 

Louisiana State University Agricultural Center, 2 p. [The 

guide is available online at http://www.lsuagcenter.com/Subjects/rice/HotTopics/SaltWater.htm ]

Hosman, R.L., Broussard, W.L., and Calandro, A.J., 1970, 

Water resources of northwestern St. Landry Parish and vicinity, Louisiana: Department of Conservation, Louisiana Geological Survey, and Louisiana Department of Public Works 

Water Resources Pamphlet no. 23, 29 p.

Jones, P.H., 1950a, Depth of occurrence of fresh ground water 

in southwestern Louisiana: U.S. Geological Survey OpenFile Report, 5 p.

Jones, P.H., 1950b, Ground-water conditions in the Lake 

Charles area, Louisiana: U.S. Geological Survey Open-File 

Report, 16 p.

Jones, P.H., Turcan, A.N., Jr., and Skibitzke, H.E., 1954, Geology and ground-water resources of southwestern Louisiana: 

Louisiana Department of Conservation Geological Bulletin 

30, 285 p.

Louisiana Cooperative Extension Service, 1999, Louisiana 

Summary: Agriculture and Natural Resources, 1999: Baton 

Rouge, La., Louisiana State University Agricultural Center, 

320 p.

Louisiana Cooperative Extension Service, 2000, Louisiana 

Summary: Agriculture and Natural Resources, 2000: Baton 

Rouge, La., Louisiana State University Agricultural Center, 

322 p.

Louisiana Office of State Climatology, 1999-2003, Louisiana 

monthly climate review: Baton Rouge, La., Louisiana State 

University, v. 19, no. 1, through v. 23, no. 6.
Selected References 21

Louisiana State University Agricultural Center, 2000, Saline 

waters pose risks to cattle, crops; producers urged to monitor 

water supplies: Baton Rouge, La., LSU AgCenter News, 

accessed Map 26, 2004 at URL 

http://www/lsuagcenter.com/Communications/news/News/

Archive/3nws1012.htm

Lovelace, J.K., 1991, Water use in Louisiana, 1990: Louisiana 

Department of Transportation and Development Water 

Resources Special Report no. 6, 131 p.

Lovelace, J.K., 1998, Distribution of saltwater in the Chicot 

aquifer system in the Calcasieu Parish area, Louisiana, 

1995-96: Louisiana Department of Transportation and 

Development Water Resources Technical Report no. 62, 

59 p.

Lovelace, J.K., 1999, Distribution of saltwater in the Chicot 

aquifer system of southwestern Louisiana, 1995-96: Louisiana Department of Transportation and Development Water 

Resources Technical Report no. 66, 61 p.

Lovelace, J.K, Fontenot, J.W., and Frederick, C.P., 2002, Louisiana ground-water map no. 14: Potentiometric surface, January 2001, and water-level changes, June 2000 to January 

2001, in the Chicot aquifer system in southwestern Louisiana: U.S. Geological Survey Water-Resources Investigations 

Report 02-4088, 2 sheets.

Lovelace, J.K, Frederick, C.P., Fontenot, J.W., and Naanes, 

M.S., 2001, Louisiana ground-water map no. 12: Potentiometric surface of the Chicot aquifer system in southwestern 

Louisiana, June 2000: U.S. Geological Survey WaterResources Investigations Report 01-4128, 1 sheet.

Lovelace, J.K., and Johnson, P.M., 1996, Water use in Louisiana, 1995: Louisiana Department of Transportation and 

Development Water Resources Special Report no. 12, 128 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.

Lurry, D.L., 1987, Pumpage of water in Louisiana, 1985: Louisiana Department of Transportation and Development, 

Office of Public Works Water Resources Special Report 

no. 4, 14 p.

National Oceanic and Atmospheric Administration, 1995, Climatological data annual summary: Asheville, N.C., National 

Oceanic and Atmospheric Administration, National Climatic 

Data Center, 23 p.

Nyman, D.J., 1984, The occurrence of high concentrations of 

chlorides in the Chicot aquifer system of southwestern Louisiana: Louisiana Department of Transportation and Development Water Resources Technical Report no. 33, 75 p.

Nyman, D.J., 1989, Quality of water in freshwater aquifers in 

southwestern Louisiana: Louisiana Department of Transportation and Development Water Resources Technical Report 

no. 42, 22 p.

Nyman, D.J., Halford, K.J., and Martin, Angel, Jr., 1990, Geohydrology and simulation of flow in the Chicot aquifer 

system of southwestern Louisiana: Louisiana Department of 

Transportation and Development Water Resources Technical 

Report no. 50, 58 p.

Sargent, B.P., 2002, Water use in Louisiana, 2000: Louisiana 

Department of Transportation and Development Water 

Resources Special Report no. 15, 133 p.

Smoot, C.W., 1986, Louisiana hydrologic atlas map no. 2: 

Areal extent of freshwater in major aquifers of Louisiana: 

U.S. Geological Survey Water-Resources Investigations 

Report 86-4150, 1 sheet.

Snider, J.L., and Forbes, M.J., Jr., 1961, Pumpage of water in 

Louisiana, 1960: Louisiana Department of Public Works, 

Department of Conservation, and Louisiana Geological Survey, 6 p.

Stanley, T.B., Jr., and Maher, J.C., 1944, Ground-water 

resources of Jefferson Davis and Acadia Parishes, Louisiana: 

Louisiana Department of Public Works, 93 p.

Tomaszewski, D.J., Lovelace, J.K., and Ensminger, P.A., 2002, 

Water withdrawals and trends in ground-water levels and 

stream discharge in Louisiana: Louisiana Department of 

Transportation and Development Water Resources Technical 

Report no. 68, 30 p.

U.S. Environmental Protection Agency, 1992, Drinking water 

regulations and health advisories: Washington, D.C., U.S. 

Environmental Protection Agency, Office of Water, 11 p.

U.S. Geological Survey, (1997-present), National field manual 

for the collection of water-quality data: U.S. Geological 

Survey Techniques of Water-Resources Investigations, book 

9, chaps. A1-A9, 2 v., variously paged. [Chapters originally 

published from 1997-99 are available online at 

http://pubs.water.usgs.gov/twri9A 

Updates and revisions are ongoing and are summarized at

http://water.usgs.gov/owq/FieldManual/mastererrata.html]

Walter, W.H., 1982, Pumpage of water in Louisiana, 1980: 

Louisiana Department of Transportation and Development, 

Office of Public Works Water Resources Special Report 

no. 3, 15 p.

Walters, D.J., 1996, Louisiana ground-water map no. 10: Potentiometric surface, 1991, and water-level changes 1985-91, of 

the Chicot aquifer system in southwestern Louisiana: U.S. 

Geological Survey Water-Resources Investigations Report 

95-4044, 2 sheets.

Whitman, H.M., and Kilburn, Chabot, 1963, Ground-water 

conditions in southwestern Louisiana, 1961 and 1962, with a 

discussion of the Chicot aquifer in the coastal area: Department of Conservation, Louisiana Geological Survey, and 

Louisiana Department of Public Works Water Resources 

Pamphlet no. 12, 32 p.

Winslow, A.G., Hillier, D.E., and Turcan, A.N., Jr., 1968, 

Saline ground water in Louisiana: U.S. Geological Survey 

Hydrologic Investigations Atlas HA-310, 4 sheets.

Zack, A.L., 1971, Ground-water pumpage and related effects, 

southwestern Louisiana, 1970, with a section on surfacewater withdrawals: Department of Conservation, Louisiana 

Geological Survey, and Louisiana Department of Public 

Works Water Resources Pamphlet no. 27, 33 p.

Tables 1 and 3
Table 1. Water-level data used to construct potentiometric-surface maps for June 2002 and January 2003, and water-level change map, June 2002 to J

upper, and "200-foot" sands of the Chicot aquifer system in southwestern Louisiana. [NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112CHCT, massive sand; 112CHCTU, upper sand; and 11202LC, "200-foot" sand. --, no data] Well number Aquifer code Altitude of land surface (feet relative to NGVD 29) Depth of well (feet) Water-level data 

June 2002 January 2003 Date measured Depth to water level (feet below land surface) Altitude of water level (feet relative to NGVD 29) Date measured Depth to water level (feet below land surface) Altit

wate

(feet re

NGV

Acadia Parish Ac-24 112CHCT 41 284 6-05 109.45 -68.45 1-15 102.14 -61

Ac-189 112CHCTU 26 -- 6-13 88.84 -63.00 1-14 64.34 -38Ac-294 112CHCTU 25 260 6-05 78.99 -53.99 1-14 71.78 -46Ac-296 112CHCTU 31 250 6-05 90.78 -59.78 1-14 82.52 -51Ac-326 112CHCTU 25.80 202 6-23 90.92 -64.39 1-15 76.91 -51Ac-332 112CHCTU 20 294 -- -- -- 1-14 64.25 -44Ac-334 112CHCT 40 300 6-05 87.60 -47.60 1-15 85.57 -45Ac-351 113CHCTU 12 230 -- -- -- 1-14 39.17 -27Ac-363 112CHCTU 9 258 6-06 60.44 -51.44 1-14 48.26 -39Ac-376 112CHCTU 32 250 6-06 96.67 -64.67 1-15 88.98 -56Ac-382 112CHCTU 11 292 6-13 63.45 -52.45 -- -- -- Ac-428 112CHCT 42 203 6-06 105.02 -63.02 1-14 94.48 -52Ac-464 112CHCTU 40 250 6-05 104.63 -64.63 1-14 99.69 -59Ac-475 112CHCTU 14 286 6-06 69.43 -55.43 1-14 55.53 -41Ac-500 112CHCTU 22 248 6-13 86.95 -64.95 1-15 73.90 -51Ac-537 112CHCTU 25 211 6-04 87.71 -62.71 1-15 68.57 -43Ac-539 112CHCTU 31 251 6-05 84.57 -53.57 1-14 72.21 -41Ac-618 112CHCT 40 249 6-05 105.64 -65.64 1-15 97.23 -57Ac-628 112CHCTU 35 250 6-05 72.81 -37.81 1-15 69.32 -34Ac-669 112CHCTU 15 176 6-06 75.26 -60.26 1-14 52.02 -37
Acadia Parish—Continued

Ac-825 112CHCT 43 266 -- -- -- 1-15 93.28 -50Ac-828 112CHCTU 21 302 6-06 78.80 -57.80 1-15 72.24 -51Ac-836 112CHCT 37 275 6-13 96.77 -59.77 1-14 90.06 -53Ac-876 112CHCTU 21 298 -- -- -- 1-15 62.50 -41Ac-929 112CHCTU 40 286 -- -- -- 1-15 102.76 -62

Allen Parish

Al-6 112CHCT 80 -- 6-06 68.18 11.82 1-09 66.02 13

Al-215 112CHCT 70 207 6-06 80.73 -10.73 1-09 80.55 -10Al-241 112CHCT 42.97 62 6-06 33.04 9.93 1-08 29.81 13Al-283 112CHCT 62 93 6-06 39.47 22.53 1-09 37.95 24Al-293 112CHCT 100 84 -- -- -- 1-08 29.26 70Al-294 112CHCT 48 142 6-06 24.30 23.70 1-08 22.30 25Al-304 112CHCT 114 104 6-06 19.22 94.78 1-08 17.45 96Al-396 112CHCT 57 315 -- -- -- 1-08 29.53 27

Beauregard Parish

Be-367 112CHCT 45 455 6-04 70.38 -25.38 1-08 70.18 -25

Be-430 112CHCT 120 123 6-06 60.68 59.32 1-08 60.70 59Be-431 112CHCT 70 84 6-06 6.14 63.86 1-08 2.92 67Be-433 112CHCT 132 82 6-04 7.85 124.15 1-08 5.14 126Be-435 112CHCT 129 124 6-04 25.30 103.70 1-15 21.64 107

Table 1. Water-level data used to construct potentiometric-surface maps for June 2002 and January 2003, and water-level change map, June 2002 to J

upper, and "200-foot" sands of the Chicot aquifer system in southwestern Louisiana.—Continued

[NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112CHCT, massive sand; 112CHCTU, upper sand; and 11202LC, "200-foot" sand. --, no data]

Well number Aquifer code

Altitude of

land surface

(feet relative to 

NGVD 29)

Depth of well 

(feet)

Water-level data

June 2002 January 2003

Date

measured

Depth to 

water level (feet below 

land surface)

Altitude of 

water level 

(feet relative to 

NGVD 29)

Date

measured

Depth to 

water level (feet below 

land surface)

Altit

wate

(feet re

NGV
Beauregard Parish—Continued Be-439 112CHCT 169 189 6-04 48.06 120.94 1-08 47.37 121

Be-440 112CHCT 212 169 6-04 45.72 166.28 1-15 44.10 167Be-443 112CHCT 206 164 -- -- -- 1-15 36.10 169Be-446 112CHCT 83 157 6-04 25.30 57.70 1-07 23.80 59Be-457 112CHCT 95 155 6-04 48.23 46.77 1-07 43.99 51Be-461 112CHCT 140 228 -- -- -- 1-07 56.90 83Be-469 112CHCT 84 380 6-04 71.84 12.16 1-08 69.62 14

Calcasieu Parish Cu-168 11202LC 7.81 375 6-05 59.31 -51.50 1-07 57.98 -50

Cu-395 11202LC 12 200 6-04 38.00 -26.00 1-06 36.93 -24Cu-642 11202LC 19 287 6-06 62.70 -43.70 1-08 55.08 -36Cu-771 11202LC 17.76 241 6-05 61.02 -43.26 1-06 59.15 -41Cu-843 11202LC 12 205 6-05 54.01 -42.01 1-07 52.50 -40Cu-854 11202LC 20 430 6-05 73.37 -53.37 1-07 52.03 -32Cu-962 11202LC 11 287 6-05 52.48 -41.48 1-06 49.62 -38Cu-967 11202LC 12 240 6-05 57.08 -45.08 1-06 54.31 -42Cu-968 11202LC 10 276 6-05 39.53 -29.53 1-07 39.27 -29Cu-971 112CHCTU 5 500 6-07 46.29 -41.29 1-09 41.05 -36Cu-975 11202LC 20 237 6-06 47.30 -27.30 1-08 42.65 -22

Table 1. Water-level data used to construct potentiometric-surface maps for June 2002 and January 2003, and water-level change map, June 2002 to J

upper, and "200-foot" sands of the Chicot aquifer system in southwestern Louisiana.—Continued

[NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112CHCT, massive sand; 112CHCTU, upper sand; and 11202LC, "200-foot" sand. --, no data]

Well number Aquifer code

Altitude of

land surface

(feet relative to 

NGVD 29)

Depth of well 

(feet)

Water-level data

June 2002 January 2003

Date

measured

Depth to 

water level (feet below 

land surface)

Altitude of 

water level 

(feet relative to 

NGVD 29)

Date

measured

Depth to 

water level (feet below 

land surface)

Altit

wate

(feet re

NGV
Calcasieu Parish—Continued

Cu-990 11202LC 14 183 6-05 64.13 -50.13 1-06 58.74 -44

Cu-1066 11202LC 25 255 6-04 33.65 -8.65 1-07 30.49 -5Cu-1159 11202LC 13 280 6-05 58.15 -45.15 1-07 57.72 -44Cu-1245 11202LC 11 136 6-04 15.39 -4.39 1-07 12.44 -1Cu-1386 11202LC 24 325 -- -- -- 1-07 59.90 -35Cu-1422 11202LC 22 262 6-14 80.69 -58.69 1-07 57.77 -35Cu-6680Z 11202LC 11 170 6-04 40.72 -29.72 1-08 36.63 -25Cu-7082Z 11202LC 13 260 6-05 42.39 -29.39 1-07 41.74 -28

Cameron Parish

Cn-80L 112CHCTU 4.73 481 6-14 37.37 -32.64 1-10 31.70 -26

Cn-81L 112CHCTU 4.45 478 -- -- -- 1-10 33.71 -29Cn-90 11202LC 3.19 396 6-05 34.61 -31.42 1-07 29.22 -26Cn-92 11202LC 5.50 443 6-05 45.35 -39.85 1-07 34.70 -29Cn-93 112CHCTU 3.76 360 6-05 21.76 -18.00 1-07 22.33 -18Cn-118 112CHCTU 5 638 6-05 21.82 -16.82 1-07 22.19 -17

Evngeline Parish

Ev-23 112CHCT 51.06 360 6-05 103.23 -52.17 1-08 93.04 -41

Ev-79 112CHCT 55 250 6-04 126.62 -71.62 1-07 118.64 -63Ev-229 112CHCT 65.66 231 6-04 105.73 -40.07 1-07 95.71 -30Ev-500 112CHCT 117.52 120 6-04 50.11 67.41 1-07 50.41 67

Table 1. Water-level data used to construct potentiometric-surface maps for June 2002 and January 2003, and water-level change map, June 2002 to J

upper, and "200-foot" sands of the Chicot aquifer system in southwestern Louisiana.—Continued

[NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112CHCT, massive sand; 112CHCTU, upper sand; and 11202LC, "200-foot" sand. --, no data]

Well number Aquifer code

Altitude of

land surface

(feet relative to 

NGVD 29)

Depth of well 

(feet)

Water-level data

June 2002 January 2003

Date

measured

Depth to 

water level (feet below 

land surface)

Altitude of 

water level 

(feet relative to 

NGVD 29)

Date

measured

Depth to 

water level (feet below 

land surface)

Altit

wate

(feet re

NGV
Evngeline Parish—Continued Ev-547 112CHCT 113.38 80 6-04 53.61 59.77 1-06 44.77 68

Ev-606 112CHCT 75 255 6-05 110.29 -35.29 1-08 105.82 -30Ev-623 112CHCT 137.20 96 -- -- -- 1-07 59.44 77Ev-659 112CHCT 60.52 252 6-05 111.33 -50.81 1-07 105.89 -45Ev-665 112CHCT 59.29 100 6-04 70.91 -11.62 1-06 67.49 -8Ev-667 112CHCT 122.20 91.50 6-04 48.81 73.39 1-07 49.04 73Ev-673 112CHCT 60 247 6-05 126.16 -66.16 1-08 119.96 -59Ev-679 112CHCT 46 70 6-04 5.27 40.73 1-07 4.00 42Ev-680 112CHCT 120 89 6-04 55.76 64.24 1-07 55.28 64Ev-751 112CHCT 53 275 6-05 133.49 -80.49 1-08 109.59 -56Ev-UR008 -- 56 -- 6-12 123.68 -67.68 1-09 109.91 -53Ev-UR009 -- 58 -- -- -- -- 1-09 106.19 -48

Iberia Parish

I-19 112CHCTU 9.72 460 6-04 18.16 -8.44 1-13 15.68 -5

I-93 112CHCTU 18.53 585 6-04 19.66 -1.13 1-13 19.55 -1

Jefferson Davis Parish

JD-9 112CHCTU 24.10 318 6-11 84.70 -60.60 1-09 68.60 -44

JD-31 112CHCT 50 250 6-10 89.51 -39.51 1-09 87.96 -37JD-33 112CHCTU 7.18 350 6-07 49.67 -42.49 1-10 40.07 -32

Table 1. Water-level data used to construct potentiometric-surface maps for June 2002 and January 2003, and water-level change map, June 2002 to J

upper, and "200-foot" sands of the Chicot aquifer system in southwestern Louisiana.—Continued

[NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112CHCT, massive sand; 112CHCTU, upper sand; and 11202LC, "200-foot" sand. --, no data]

Well number Aquifer code

Altitude of

land surface

(feet relative to 

NGVD 29)

Depth of well 

(feet)

Water-level data

June 2002 January 2003

Date

measured

Depth to 

water level (feet below 

land surface)

Altitude of 

water level 

(feet relative to 

NGVD 29)

Date

measured

Depth to 

water level (feet below 

land surface)

Altit

wate

(feet re

NGV
Jefferson Davis Parish—Continued

JD-166 112CHCTU 2 -- 6-11 84.63 -46.63 1-09 76.88 -38

JD-222 112CHCTU 4.61 300 6-07 41.42 -36.81 1-09 35.38 -30JD-298 112CHCTU 15 297 6-14 66.08 -51.08 1-10 59.52 -44JD-317 112CHCT 42.27 289 6-11 91.18 -48.91 1-09 85.38 -43JD-353 112CHCT 25 300 6-06 40.70 -15.70 1-08 46.49 -21JD-401 112CHCTU 14 282 6-07 66.90 -52.90 1-09 50.33 -36JD-406 112CHCT 50 450 6-10 83.91 -33.91 1-09 83.26 -33JD-470 112CHCTU 10 325 6-07 65.08 -55.08 1-10 52.68 -42JD-485A 112CHCTU 21.36 290 6-07 75.52 -54.16 1-09 56.79 -35JD-492 112CHCTU 25 613 6-07 85.32 -60.32 1-10 77.90 -52JD-493 112CHCT 37.95 220 6-14 60.55 -22.60 1-09 59.04 -21JD-581 112CHCT 35 -- 6-11 88.44 -53.44 -- -- -- 

JD-740 112CHCT 35 264 6-10 89.67 -54.67 1-09 84.20 -49

JD-751 112CHCTU 10 193 6-14 53.30 -43.30 1-10 41.96 -31JD-772 112CHCTU 27 340 6-11 84.93 -57.93 1-09 68.27 -41JD-835 112CHCTU 31 280 6-14 70.83 -39.83 1-09 64.47 -33JD-848 112CHCTU 32 243 6-06 69.84 -37.84 1-09 61.38 -29

Table 1. Water-level data used to construct potentiometric-surface maps for June 2002 and January 2003, and water-level change map, June 2002 to J

upper, and "200-foot" sands of the Chicot aquifer system in southwestern Louisiana.—Continued

[NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112CHCT, massive sand; 112CHCTU, upper sand; and 11202LC, "200-foot" sand. --, no data]

Well number Aquifer code

Altitude of

land surface

(feet relative to 

NGVD 29)

Depth of well 

(feet)

Water-level data

June 2002 January 2003

Date

measured

Depth to 

water level (feet below 

land surface)

Altitude of 

water level 

(feet relative to 

NGVD 29)

Date

measured

Depth to 

water level (feet below 

land surface)

Altit

wate

(feet re

NGV
Lafayette Parish Lf-524 112CHCTU 25 174 6-04 30.80 -5.80 1-13 29.97 -4

Lf-662 112CHCTU 40.37 152 -- -- -- 1-13 49.58 -9Lf-822 112CHCTU 30 -- -- -- -- 1-14 54.80 -24Lf-823 112CHCTU 30 363 6-04 59.58 -29.58 -- -- -- 

Lf-914 112CHCTU 30 250 6-13 67.43 -37.43 1-14 62.79 -32

Lf-958 112CHCTU 50 115 6-05 53.53 -3.53 1-13 53.37 -3

St. Landry Parish SL-142 112CHCT 50 235 -- -- -- 1-09 85.58 -35

SL-179 112CHCT 55.23 94 6-04 58.47 -3.24 1-06 58.75 -3SL-190 112CHCT 74.36 175 6-06 87.97 -13.61 1-06 87.54 -13SL-331 112CHCT 62 -- 6-06 89.95 -27.95 1-09 89.51 -27SL-347 112CHCT 50 300 6-06 118.38 -68.38 1-09 107.82 -57SL-392 112CHCT 46.74 126 6-06 56.44 -9.70 1-10 95.39 -48SL-412 112CHCT 70 302 6-06 80.27 -10.27 1-10 79.65 -9SL-566 112CHCT 51 250 6-06 104.13 -53.13 1-10 102.68 -51

St. Martin Parish

SMn-109 112CHCTU 11.34 375 6-04 3.15 8.19 1-13 5.76 5

St. Mary Parish

SM-57U 112CHCTU 8.72 638 6-04 10.05 -1.33 1-13 10.52 -1

Table 1. Water-level data used to construct potentiometric-surface maps for June 2002 and January 2003, and water-level change map, June 2002 to J

upper, and "200-foot" sands of the Chicot aquifer system in southwestern Louisiana.—Continued

[NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112CHCT, massive sand; 112CHCTU, upper sand; and 11202LC, "200-foot" sand. --, no data]

Well number Aquifer code

Altitude of

land surface

(feet relative to 

NGVD 29)

Depth of well 

(feet)

Water-level data

June 2002 January 2003

Date

measured

Depth to 

water level (feet below 

land surface)

Altitude of 

water level 

(feet relative to 

NGVD 29)

Date

measured

Depth to 

water level (feet below 

land surface)

Altit

wate

(feet re

NGV
Vermilion Parish

Ve-28 112CHCTU 6.74 260 6-10 13.23 -6.49 1-15 12.47 -5

Ve-442 112CHCTU 5.42 281 6-11 31.23 -25.81 1-14 25.81 -20Ve-460 112CHCTU 9.78 300 6-11 26.63 -16.85 1-14 25.64 -15Ve-501 112CHCTU 22 227 6-04 29.61 -7.99 1-13 28.46 -6Ve-556 112CHCTU 6 263 6-11 40.91 -34.91 -- -- -- 

Ve-586 112CHCTU 15.40 259 6-11 36.00 -20.60 1-15 34.29 -18

Ve-629L 112CHCTU 1.79 487 6-10 9.25 -7.46 1-15 7.89 -6Ve-629U 112CHCTU 1.79 457 6-10 8.16 -6.37 1-15 6.87 -5Ve-630U 112CHCTU 4.75 528 6-10 14.95 -10.20 1-15 13.37 -8Ve-637L 112CHCTU 4.06 243 6-10 14.54 -10.48 1-15 13.43 -9Ve-637U 112CHCTU 4.06 198 6-10 14.15 -10.09 1-15 13.32 -9Ve-639 112CHCTU 5.84 608 6-10 10.73 -4.89 1-15 10.72 -4Ve-654 112CHCTU 9.60 267 6-11 30.80 -21.20 1-14 26.65 -17Ve-764 112CHCTU 15 250 6-11 44.50 -29.50 1-14 44.34 -29Ve-882 112CHCTU 10 279 6-11 39.79 -29.79 1-14 36.50 -26Ve-1134 112CHCTU 5 190 6-11 44.91 -39.91 1-14 35.99 -30Ve-1152 112CHCTU 10 235 6-11 57.57 -47.57 1-14 47.07 -37

Table 1. Water-level data used to construct potentiometric-surface maps for June 2002 and January 2003, and water-level change map, June 2002 to J

upper, and "200-foot" sands of the Chicot aquifer system in southwestern Louisiana.—Continued

[NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112CHCT, massive sand; 112CHCTU, upper sand; and 11202LC, "200-foot" sand. --, no data]

Well number Aquifer code

Altitude of

land surface

(feet relative to 

NGVD 29)

Depth of well 

(feet)

Water-level data

June 2002 January 2003

Date

measured

Depth to 

water level (feet below 

land surface)

Altitude of 

water level 

(feet relative to 

NGVD 29)

Date

measured

Depth to 

water level (feet below 

land surface)

Altit

wate

(feet re

NGV
Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance vaconcentrations, 2000-03. [NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well number Latitude (NAD 27) Longitude (NAD 27) Aquifer code Primary use of well Altitude of land surface (feet relative to NGVD 29) Depth of well (feet) Depth to top of screen (feet) Depth to bottom of screen (feet) Date sampled Field specific conductance (microsiemens per centimeter at 25 degrees Celsius) Laborat

cond

(micros

centim

degree

Acadia Parish Ac-3 302623 921939 112CHCT I 50 338 -- -- 6-05-2002 912 

Ac-69 302236 922029 112CHCT I 43 -- -- -- 6-05-2002 699 Ac-80 302240 921856 112CHCT I -- -- -- -- 5-22-2002 744 Ac-113 301441 922050 112CHCTU I 25 331 -- -- 5-03-2001 697 Ac-147 300731 922131 112CHCTU I 17.78 298 -- -- 6-28-2000 845 

7-18-2000 831 8-14-2000 849 8-30-2000 839 

10-09-2000 844 10-24-2000 852 

4-05-2001 808 5-02-2001 860 5-10-2001 827 

10-08-2001 858 

Ac-179 301904 922725 112CHCTU I 34.61 313 -- -- 6-06-2002 626 Ac-204 301323 921723 112CHCTU I -- -- -- -- 6-01-2000 602 

6-16-2000 555 6-28-2000 578 7-15-2000 602 8-02-2000 608 
Acadia Parish—Continued

Ac-204 301323 921723 112CHCTU I -- -- 8-15-2000 609 

9-03-2000 610 9-16-2000 606 

12-11-2000 606 

5-02-2001 619 

Ac-222 301904 921040 112CHCTU I 36 -- -- -- 6-05-2002 554 Ac-369 300850 922742 112CHCTU I 15 280 200 280 6-06-2002 727 Ac-394 302545 923445 112CHCT I 36 287 197.24 283.66 5-30-2002 386 Ac-446 302209 921924 112CHCT I 40 234 167 234 5-22-2002 735 Ac-451 300740 922650 112CHCTU N 14 293 212.5 293.4 3-15-2000 762 

9-13-2000 771 3-09-2001 771 9-19-2001 765 4-09-2002 770 9-13-2002 759 3-28-2003 761 

Ac-475 300848 922746 112CHCTU I 14 286 226.4 286.4 5-16-2001 735 Ac-477 300937 922144 112CHCTU I 20 269 208.95 269 5-16-2001 700 Ac-548 301558 922321 112CHCTU I 25 278 208 278 5-10-2001 676 

5-24-2001 678 6-19-2001 684 7-12-2001 684 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Acadia Parish—Continued Ac-558 302109 921634 112CHCTU I 42 205 175 205 5-30-2002 -- 

Ac-618 302533 922051 112CHCT I 40 249 209 249 5-30-2002 670 Ac-711 301337 921814 112CHCTU I 25 260 238 260 5-02-2001 665 Ac-809 301430 922647 112CHCTU I 23 235 160 220 5-15-2001 758 Ac-822 301343 922024 112CHCTU I 25 300 -- -- 6-05-2000 686 

6-20-2000 698 6-28-2000 569 7-15-2000 700 8-02-2000 679 8-15-2000 642 9-01-2000 700 9-16-2000 713 

12-11-2000 701 

5-02-2001 719 

Ac-836 302304 923431 112CHCT I 37 275 -- -- 5-31-2002 444 

6-06-2002 444 

Ac-848 302254 922045 112CHCT I 42 248 168 241 5-15-2001 692 Ac-855 302528 921742 112CHCT I 45 253 179 252 5-30-2002 727 Ac-857 302158 922756 112CHCT I 41 272 174 271 5-31-2002 771 Ac-919 300846 923227 112CHCTU I 10 274 202 273 4-30-2003 806 Ac-929 302515 922431 112CHCTU I 40 285 203 285 5-15-2001 690 Ac-971 302309 921835 -- I 46 -- -- -- 5-22-2002 750 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Acadia Parish—Continued

Ac-980 302055 921946 112CHCTU I 36 276 179 274 5-22-2002 727 Ac-UR001 300847 923245 -- I 10 -- -- -- 5-11-2000 847 

5-20-2000 787 

Ac-UR004 300847 923312 -- I 11 -- -- -- 6-28-2000 823 

7-29-2000 814 

Ac-UR006 300827 922501 -- I -- -- -- -- 6-28-2000 682 

7-18-2000 677 8-14-2000 690 8-30-2000 685 

10-09-2000 677 10-24-2000 687 

4-05-2001 676 5-02-2001 699 5-04-2001 675 5-18-2001 676 7-17-2001 682 

10-08-2001 692 

Ac-UR007 302202 922151 -- I 40 -- -- -- 5-15-2001 705 Ac-UR008 301629 922317 -- I -- -- -- -- 5-24-2001 690 

6-19-2001 689 7-12-2001 673 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Calcasieu Parish Cu-168 300440 930845 11202LC I 7.81 375 -- -- 6-04-2001 514 

Cu-171 300820 930837 11202LC I 13 375 -- -- 4-27-2000 466 

5-16-2000 466 5-06-2001 480 5-16-2001 491 5-19-2001 481 5-23-2001 497 5-30-2001 497 6-19-2001 491 6-26-2001 498 

Cu-633 300545 930652 11202LC I -- 300 -- -- 5-18-2000 732 

6-18-2000 754 5-22-2001 746 

Cu-688 300540 931303 11205LC I 10.96 694 614 694 6-22-2000 550 Cu-771 301336 931830 11202LC O 17.76 241 231 241 3-14-2000 420 

9-12-2000 425 3-07-2001 409 9-17-2001 424 4-11-2002 425 9-12-2002 430 3-27-2003 429 

Cu-787 300353 932102 11205LC O 4.33 734 729 734 3-14-2000 543 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Calcasieu Parish—Continued

Cu-787 300353 932102 11205LC O 4.33 734 9-12-2000 537 

3-06-2001 514 9-18-2001 527 4-11-2002 525 9-12-2002 523 3-27-2003 523 

Cu-812 301211 930133 112CHCTU I -- 265 -- -- 5-15-2000 993 

4-30-2003 1,010 

Cu-960 301031 932049 11205LC O 21 598 592 598 9-13-2000 774 

3-05-2001 759 9-17-2001 755 4-10-2002 758 9-12-2002 754 3-27-2003 766 

Cu-1012 300707 930435 11202LC I 20 363 280.2 363 5-17-2000 817 

6-20-2000 769 4-29-2003 789 

Cu-1092 300858 931131 11205LC I 17.5 600 519.2 600.1 5-18-2000 488 Cu-1093 301341 930024 112CHCTU I 25 303 243 303 4-24-2000 906 

5-20-2000 915 6-16-2000 916 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Calcasieu Parish—Continued 9-03-2000 901 

Cu-1093 301341 930024 112CHCTU I 25 303 4-16-2001 900 

5-28-2001 891 5-02-2002 933 

Cu-1211 301753 930239 11202LC I 20 205 143 205 5-16-2000 826 Cu-1253 301544 930455 11202LC I 21 236 176 236 4-24-2000 1,220 

5-08-2000 1,230 5-20-2000 1,180 7-07-2000 1,180 9-01-2000 1,190 3-08-2001 1,200 4-12-2001 1,190 5-03-2001 1,140 5-10-2001 1,070 5-22-2001 1,230 5-27-2001 1,180 4-02-2002 1,230 5-09-2002 1,220 5-01-2003 1,200 

Cu-1287 301223 930420 11202LC I 20 282 200 282 5-07-2000 1,270 

5-18-2000 1,270 

Cu-1369 301040 930823 11205LC I 21 594 -- -- 5-16-2000 504 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Calcasieu Parish—Continued

6-21-2000 512 

Cu-1369 301040 930823 11205LC I 21 594 5-15-2001 515 Cu-1385 301324 931705 11205LC N 15 580 400 575 3-14-2000 805 

9-13-2000 754 3-06-2001 715 

10-11-2001 699 

9-12-2002 699 3-27-2003 694 

Cu-1386 301048 930348 11202LC I 24 325 204 316 4-06-2000 1,380 

5-09-2001 1,380 6-05-2001 1,230 

Cu-1387 301100 930305 11202LC I 30 283 203 283 4-26-2000 1,350 

6-07-2000 1,330 6-05-2001 1,210 7-25-2001 1,160 

Cu-1389 301123 930119 112CHCTU I 24 302 182 302 5-22-2001 997 Cu-1391 301205 930157 11202LC I 23 254 -- -- 4-25-2000 1,080 

5-15-2000 1,090 

Cu-1397 301307 930409 11202LC I 22 291 181 291 4-26-2000 1,310 

6-07-2000 1,290 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Calcasieu Parish—Continued 5-22-2001 1,290 

6-05-2001 1,160 

Cu-1398 300954 930535 11202LC I 22 322 216 321 4-27-2000 1,060 Cu-1398 300954 930535 11202LC I 22 322 5-16-2000 985 

4-23-2001 973 

Cu-1402 301006 925948 112CHCTU I 17 275 255 275 5-05-2000 1,690 

5-15-2000 1,100 5-23-2000 1,360 6-09-2000 1,020 

Cu-1415 301353 930224 11202LC I 16 273 167 272 4-25-2000 1,240 

5-15-2000 1,250 5-23-2001 1,250 

Cu-1422 301250 930320 11202LC I 22 262 200 262 6-05-2002 1,120 Cu-1432 300930 930944 11202LC I 19 272 202 272 6-12-2000 488 

5-22-2001 494 

Cu-9069Z 300838 930318 11202LC I 21 270 260 270 4-26-2000 714 

5-16-2000 897 5-27-2000 713 6-08-2000 912 6-17-2000 907 6-22-2000 913 5-15-2001 900 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Calcasieu Parish—Continued

Cu-UR001 300928 932941 -- I 15 -- -- -- 5-17-2001 434 

5-18-2001 433 

Cu-UR002 300815 932836 -- I 10 -- -- -- 5-17-2001 506 Cu-UR002 300815 932836 -- I 10 -- 5-18-2001 526 

5-19-2001 534 

Cu-UR003 301225 925954 -- I 23 190 150 190 4-27-2000 1,090 

6-16-2000 1,130 4-02-2001 1,700 4-24-2001 2,020 5-22-2001 1,930 6-20-2001 2,010 8-30-2001 2,140 2-15-2002 2,750 3-18-2002 2,440 6-01-2002 2,150 4-08-2003 2,860 

Cu-UR004 301340 930133 -- I 23 -- -- -- 4-25-2000 1,080 

5-15-2000 1,090 

Cu-UR005 300536 930547 -- I 26 -- -- -- 6-12-2000 825 

6-17-2000 801 

Cu-UR006 300351 930648 -- I 16 -- -- -- 4-28-2000 714 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Calcasieu Parish—Continued Cu-UR009 300830 930559 -- I 19 -- -- -- 4-27-2000 982 

5-31-2000 988 

Cu-UR010 301009 930241 -- I 20 -- -- -- 7-11-2000 688 

7-18-2000 676 

Cu-UR010 301009 930241 -- I 20 -- 7-25-2000 674 Cu-UR015 300817 930250 -- I -- -- -- -- 5-16-2000 653 

6-21-2000 645 5-15-2001 640 

Cu-UR016 301347 925948 -- I 30 -- -- -- 4-25-2000 614 

5-16-2000 611 5-17-2000 617 

Cu-UR019 300639 930502 -- I -- -- -- -- 5-16-2000 962 

6-20-2000 957 

Cameron Parish

Cn-22 300042 930854 11202LC I 10 388 -- -- 1-30-2000 572 

4-27-2000 570 

Cn-80L 295846 923811 112CHCTU O 4.73 481 475 481 3-15-2000 1,290 

9-13-2000 1,210 3-09-2001 1,300 9-19-2001 1,300 4-09-2002 1,300 9-10-2002 1,280 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Cameron Parish—Continued

3-28-2003 1,320 

Cn-90 295611 930448 11202LC O 3.19 396 386 396 3-13-2000 998 

9-11-2000 985 3-07-2001 964 

Cn- 90 295611 930448 11202LC O 3.19 396 9-18-2001 980 

4-10-2002 985 9-11-2002 988 3-26-2003 996 

Cn-92 300104 930156 11202LC O 5.5 443 438 443 3-13-2000 1,830 

9-12-2000 1,820 3-07-2001 1,870 9-18-2001 1,950 4-10-2002 1,900 9-11-2002 1,870 3-26-2003 1,850 

Cn-196 300122 930604 11202LC I 10 420 320 420 4-20-2000 1,270 

5-11-2000 1,270 5-25-2000 1,270 6-03-2000 1,270 6-15-2000 1,270 4-29-2003 1,250 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Cameron Parish—Continued Cn-197 300216 930518 11202LC I 10 462 362 462 4-27-2000 762 

6-14-2000 764 

Cn-198 300029 930716 11202LC I 10 402 302 402 4-20-2000 1,190 

5-11-2000 1,190 5-25-2000 1,190 

Cn-198 300029 930716 11202LC I 10 402 6-03-2000 1,190 

6-16-2000 1,200 6-21-2000 1,180 6-29-2000 1,160 7-19-2000 1,190 

Cn-UR001 300001 930859 -- I 10 -- -- -- 4-27-2000 622 

5-31-2000 622 

Cn-UR002 300150 930718 -- I 20 -- -- -- 4-27-2000 853 

5-31-2000 861 

Evangeline Parish

Ev-673 303801 922500 112CHCT P 60 247 187 247 5-16-2001 740 Ev-834 303617 923013 112CHCT I 50 260 190 260 5-15-2001 336 Ev-879 304545 921911 112CHCT I 80 220 153 220 5-16-2001 341 Ev-889 303944 922725 112CHCT I 60 201 151 201 5-15-2001 599 Ev-923 304201 922636 112CHCT I -- 188 -- -- 5-16-2001 793 Ev-UR001 303832 922637 -- I -- -- -- -- 5-15-2001 737 Ev-UR003 303832 922744 -- I -- -- -- -- 5-15-2001 488 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Evangeline Parish—Continued

Ev-UR004 304036 922343 -- I -- -- -- -- 5-16-2001 479 Ev-UR005 303704 921717 -- I -- -- -- -- 5-16-2001 689 Ev-UR006 304254 922021 -- I -- -- -- -- 5-17-2001 648 Ev-UR007 304346 922015 -- I -- -- -- -- 5-17-2001 546 Ev-UR009 303222 922206 -- I 58 -- -- -- 4-07-2001 606 Ev-UR009 303222 922206 -- I 58 -- 4-17-2001 603 

4-23-2001 604 

Iberia Parish

I-93 300035 914433 112CHCTU O 18.53 585 580 585 3-16-2000 734 

9-15-2000 740 3-08-2001 728 9-13-2001 716 3-27-2002 729 9-10-2002 728 3-25-2003 730 

Jefferson Davis Parish

JD-50 301244 924435 112CHCTU I -- 310 -- -- 6-06-2000 455 

7-07-2000 450 

JD-79 300404 924429 112CHCTU I 18.77 313 -- -- 6-18-2001 588 

6-20-2001 585 

JD-135 301439 924637 112CHCTU I 20 -- -- -- 5-17-2000 449 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Jefferson Davis Parish—Continued 6-08-2000 450 

5-03-2001 454 3-06-2002 467 6-10-2002 452 

JD-176 301536 924405 112CHCTU I -- 290 -- -- 4-24-2000 888 

7-31-2000 857 

JD-176 301536 924405 112CHCTU I -- 290 8-10-2000 858 

9-04-2000 849 

10-02-2000 857 

3-02-2001 874 4-02-2001 867 5-08-2001 848 7-05-2001 846 8-25-2001 862 

JD-241 301913 925848 112CHCTU I 25 275 195 275 4-22-2001 554 JD-352 302314 925713 112CHCT I 30 329 -- -- 4-21-2000 259 

5-30-2000 259 

JD-447 302050 925645 112CHCT I -- 262 -- -- 3-06-2001 318 

4-05-2001 317 5-07-2001 321 5-25-2001 320 7-22-2001 325 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Jefferson Davis Parish—Continued

4-22-2002 344 5-06-2002 339 5-14-2002 341 6-05-2002 336 3-04-2003 337 

JD-469 300845 924313 112CHCTU I 15 276 196 276 2-25-2001 615 JD-469 300845 924313 112CHCTU I 15 276 4-06-2001 613 

5-22-2001 614 6-30-2001 616 8-24-2001 623 

JD-491 300508 924056 112CHCTU P 10 377 326 377 3-15-2000 701 

9-13-2000 713 3-09-2001 705 9-19-2001 712 4-09-2002 711 9-13-2002 712 3-28-2003 717 

JD-493 302509 925321 112CHCT I 37.95 220 160 220 5-25-2001 245 

6-06-2002 245 

JD-499 301752 924009 112CHCTU I 30 250 190 250 5-16-2001 448 JD-523 301550 924514 112CHCTU I 25 311 229.58 311 4-24-2000 466 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Jefferson Davis Parish—Continued JD-650 301350 924411 112CHCTU I 22 263 183 263 4-24-2000 437 

JD-727 300552 924559 112CHCTU I 15 327.5 247.04 327.5 5-02-2001 530 

5-24-2001 526 

JD-751 300547 924426 112CHCTU I 10 193 133 193 5-03-2001 606 

6-07-2002 578 

JD-772 301354 924455 112CHCTU I 27 340 259 340 5-16-2001 465 

6-07-2002 449 

JD-817 301352 925614 112CHCTU I 20 296 227 296 5-24-2000 779 

6-26-2000 982 2-20-2001 959 4-16-2001 982 

JD-860 301242 925920 112CHCTU I 26 275 215 275 4-27-2000 1,290 

5-16-2000 1,290 4-02-2001 1,050 4-24-2001 1,060 5-22-2001 1,090 6-20-2001 1,070 8-30-2001 1,060 2-15-2002 1,090 3-18-2002 1,170 6-01-2002 1,070 4-08-2003 1,060 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Jefferson Davis Parish—Continued

4-29-2003 1,120 

JD-867 301126 924801 112CHCTU I 16 202 142 202 6-06-2000 451 

7-13-2000 422 

JD-871 300604 924850 112CHCTU I 9 200 140 200 5-18-2000 540 

6-09-2000 542 5-03-2001 538 

JD-UR002 300616 924631 -- I 20 -- -- -- 5-18-2000 632 JD-UR002 300616 924631 -- I 20 -- 5-24-2000 631 

6-13-2000 618 7-18-2000 616 7-31-2000 616 8-15-2000 620 4-11-2001 604 5-03-2001 610 

JD-UR006 301203 925715 -- I 16 -- -- -- 9-12-2000 1,030 

10-19-2001 1,030 

9-15-2002 1,080 

JD-UR008 301701 925903 -- I 33 -- -- -- 2-22-2001 1,140 

4-08-2001 1,120 

JD-UR009 301724 930111 -- I 26 -- -- -- 4-21-2000 959 

5-30-2000 969 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Jefferson Davis Parish—Continued JD-UR011 301000 924807 -- I 13 -- -- -- 6-06-2000 456 

JD-UR012 301222 924747 -- I 16 -- -- -- 6-06-2000 398 

7-17-2000 391 

JD-UR013 301159 924630 -- I 20 -- -- -- 6-06-2000 456 

7-07-2000 447 

JD-UR014 301852 925724 -- I -- -- -- -- 4-06-2001 514 

4-15-2001 571 4-27-2001 516 

JD-UR014 301852 925724 -- I -- -- 5-11-2001 516 

5-26-2001 622 4-29-2002 653 5-11-2002 663 5-15-2002 626 6-17-2002 565 8-11-2002 589 

JD-UR015 301700 925903 -- I 33 -- -- -- 5-14-2000 1,310 

5-30-2000 1,300 

JD-UR017 300409 925222 -- I 7 -- -- -- 5-02-2001 536 

5-24-2001 550 

JD-UR018 301725 930111 -- I 26 -- -- -- 5-19-2000 969 

5-03-2001 957 

JD-UR019 301747 930020 -- I 33 -- -- -- 5-19-2000 918 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Jefferson Davis Parish—Continued

5-03-2001 812 

JD-UR020 301708 930048 -- I 33 -- -- -- 5-19-2000 828 JD-UR022 301836 925648 -- I -- -- -- -- 5-14-2001 435 

5-26-2001 447 8-11-2002 472 4-29-2002 480 5-11-2002 481 5-25-2002 465 

Lafayette Parish

Lf-524 300605 915935 112CHCTU P 25 174 141 174 3-15-2000 325 

9-14-2000 295 3-08-2001 282 9-14-2001 320 4-09-2002 310 9-10-2002 307 

St. Landry Parish

SL-142 302732 921029 112CHCT I 50 235 -- -- 5-03-2002 -- SL-331 303200 921005 112CHCT I 62 -- -- -- 4-03-2002 -- SL-345 304911 920637 112ACFL I 40 158 90 157.5 4-30-2003 1,220 SL-459 303151 922145 112CHCT I 51 249 179 249 4-07-2001 609 

4-17-2001 606 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
St. Landry Parish—Continued 4-23-2001 599 

6-07-2002 613 

SL-564 304845 921149 112ACFL I 43 199 123 199 5-04-2001 806 SL-673 304832 921142 112ACFL I 48 187 123 186 5-04-2001 773 SL-714 304827 921011 112CHCT I 45 178 126 176 2-24-2001 1,100 

5-30-2001 1,070 7-30-2001 1,080 4-30-2003 1,110 

SL-UR001 304920 921210 -- I 46 -- -- -- 4-20-2001 791 

11-09-2001 514 

SL-UR001 304920 921210 -- I 46 -- 2-01-2002 -- SL-UR004 304416 920343 -- I 40 -- -- -- 1-22-2001 1,800 

2-26-2001 1,710 4-05-2001 1,810 5-04-2001 1,810 7-27-2001 1,800 

SL-UR005 304555 915248 -- I 39 -- -- -- 4-26-2001 657 SL-UR006 304807 915239 -- I 39 -- -- -- 4-26-2001 910 

5-31-2001 821 

SL-UR007 303459 920852 -- I 66 -- -- -- 5-03-2002 -- 

St. Martin Parish

SMn-109 301304 914240 112CHCTU O 11.34 375 370 375 3-16-2000 1,200 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
St. Martin Parish—Continued

9-14-2000 1,190 3-08-2001 1,180 9-13-2001 1,170 3-27-2002 1,190 9-09-2002 1,190 3-25-2003 1,200 

St. Mary Parish

SM-57U 294749 914023 112CHCTU O 8.72 638 628 638 3-16-2000 1,140 

9-15-2000 1,170 3-08-2001 1,150 

SM-57U 294749 914023 112CHCTU O 8.72 638 9-13-2001 1,140 

3-28-2002 1,160 9-10-2002 1,170 3-25-2003 1,180 

Vermilion Parish

Ve-170 300121 920057 112CHCTS H -- 70 50 70 8-03-2000 300 Ve-312 300236 923910 112CHCTU I 6 205 155 205 5-17-2001 703 

6-18-2001 709 

Ve-384 300257 924011 112CHCTU I 6 348 -- -- 5-17-2001 630 

6-18-2001 645 

Ve-425 295927 922755 112CHCTU I -- -- -- -- 6-05-2000 831 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Vermilion Parish—Continued Ve-426 300000 922722 112CHCTU I -- 354 -- -- 6-12-2000 912 

6-13-2000 918 6-15-2000 920 8-28-2000 887 8-29-2000 900 5-30-2001 878 5-31-2001 877 

Ve-432 295835 922549 112CHCTU I -- 350 -- -- 4-26-2002 821 Ve-460 921655 295645 112CHCTU I 9.78 300 -- -- 5-05-2000 1,300 Ve-586 300240 920832 112CHCT I 15.4 259 195 259 4-24-2002 618 Ve-637L 295345 921007 112CHCTU O 4.06 243 233 243 3-16-2000 2,790 Ve-637L 295345 921007 112CHCTU O 4.06 243 9-11-2000 2,750 

3-08-2001 2,750 9-14-2001 2,760 3-28-2002 2,800 9-10-2002 2,860 3-26-2003 2,890 

Ve-639 293845 922649 112CHCTU O 5.84 608 603 608 3-13-2000 1,550 

9-11-2000 1,550 3-07-2001 1,510 9-14-2001 1,520 3-28-2002 1,540 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Vermilion Parish—Continued

9-10-2002 1,550 3-26-2003 1,560 

Ve-725 300315 921909 112CHCTU I 14 300 -- -- 4-24-2002 1,010 Ve-733 300537 921801 112CHCTU I 15 297 190.67 297.33 4-24-2002 -- Ve-1081 295947 922310 112CHCTU I 10 190 160 190 4-26-2002 726 Ve-1123 300351 923108 112CHCTU I 10 175 -- -- 5-16-2001 -- Ve-1152 300501 921534 112CHCTU I 10 235 195 235 4-24-2002 -- Ve-UR001 295951 922913 -- I 6 -- -- -- 6-13-2000 589 

8-18-2000 601 9-19-2000 593 5-10-2001 823 

Ve-UR002 300039 923232 -- H -- -- -- -- 5-09-2000 883 

6-06-2000 882 4-01-2001 856 5-02-2001 881 5-10-2001 894 5-29-2001 862 7-02-2001 887 

Ve-UR003 300129 921243 -- I 23 -- -- -- 6-03-2000 794 

6-17-2000 772 7-03-2000 755 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree
Vermilion Parish—Continued 7-15-2000 752 

8-15-2000 717 

Ve-UR004 300246 921344 -- I 26 -- -- -- 6-07-2000 681 

6-20-2000 687 7-07-2000 669 8-14-2000 666 

Ve-UR005 295705 921601 -- I 13 -- -- -- 6-14-2000 865 

6-28-2000 838 7-15-2000 842 7-28-2000 833 8-14-2000 835 

Ve-UR007 300239 924019 -- I 6 -- -- -- 5-17-2001 654 Ve-UR007 300239 924019 -- I 6 -- 6-18-2001 660 Ve-UR010 300524 920734 -- I 26 -- -- -- 5-10-2001 595 Ve-UR011 300233 922650 -- I 10 -- -- -- 4-26-2002 957 Ve-UR012 295644 921026 -- I 16 -- -- -- 5-08-2002 -- 

Table 3. Selected data for wells in the Chicot aquifer system or the Atchafalaya aquifer in southwestern Louisiana, including specific conductance va

concentrations, 2000-03.—Continued

[NAD 27, North American Datum of 1927; NGVD 29, National Geodetic Vertical Datum of 1929; aquifer code: 112ACFL, Atchafalaya aquifer; 112CHCT, massive sand; 112C

shallow sand; 11202LC, "200-foot" sand; and 11205LC, "500-foot" sand. Primary use of well: H, domestic; I, irrigation; N, industry; O, observation; and P, public supply. --, n

Well 

number

Latitude 

(NAD 27)

Longitude 

(NAD 27) Aquifer code

Primary

use of 

well

Altitude of 

land surface 

(feet relative

to NGVD 29)

Depth 

of well 

(feet)

Depth 

to top 

of 

screen 

(feet)

Depth to 

bottom 

of 

screen 

(feet)

Date

sampled

Field specific 

conductance 

(microsiemens 

per centimeter at 

25 degrees 

Celsius)

Laborat

cond

(micros

centim

degree