Water-Level Surface in the Chicot Equivalent Aquifer System in Southeastern Louisiana, 2009

By

Dan J. Tomaszewski

2011

Prepared in cooperation with the 

LOUISIANA DEPARTMENT OF TRANSPORTATION AND DEVELOPMENT

OFFICE OF PUBLIC WORKS, HURRICANE FLOOD PROTECTION AND INTERMODAL TRANSPORTATION

WATER RESOURCES PROGRAMS

SCIENTIFIC INVESTIGATIONS MAP 3173

D O TD Chicot Equivalent aquifer system—SHEET 2 OF 2

APED TR MENT OF TRANSPORTATION AND DEVELOPMENT

Water-Level Surface

The 2009 water-level surface map for the Chicot equivalent aquifer system (fig. 5) was constructed from 96 water-level 

measurements collected April through July 2009 (table 1). The map shows the general configuration of the water-level surface 

(fig. 5) and includes areas where the aquifer system is unconfined (the recharge area) and areas where the system is confined 

by clay layers. In the recharge area, the water-level surface generally follows the topography. In the confined area, the 

water-level surface is smooth and less variable, and artesian conditions exist (the water level is above the top of the aquifer).

Water- level contours range from 250 ft above NGVD 29 along the northern boundary of the study area to 0 ft NGVD 29 

near the southern boundary (fig. 5). In the recharge area, water-level measurements range from about 80 to 280 ft above 

NGVD 29. Water levels in the confined area range from about 0 ft NGVD 29 (slightly below in the Mandeville-Slidell and 

Baton Rouge areas) to 100 ft above NGVD 29 near outcrop areas. The highest water level, 280.58 ft above NGVD 29, was 

measured in the recharge area at well Wa-160 in northern Washington Parish. The lowest water level, 2.67 ft below NGVD 29, 

was measured in the Baton Rouge area at well EB-1264.

Movement of groundwater in the Chicot equivalent aquifer system is generally from north to south in the study area 

(see flow arrows on fig. 5). Groundwater movement is perpendicular to the contours in the direction of the hydraulic gradient. 

In the recharge area, groundwater flow is from high areas (hilltops) toward major stream valleys. Major streams that receive 

streamflow from groundwater include the Mississippi, Amite, Tickfaw, Tangipahoa, Tchefuncte, and Pearl Rivers, as well as 

Thompson Creek and Bogue Chitto. Groundwater that is not discharged into streams or withdrawn from wells moves downdip 

toward confined areas. Vertical movement of water in the recharge area could also recharge underlying, deeper aquifers.

Water-Level Difference, 1991–2009

Comparison of the 1991 water-level data with the 2009 data indicates water-level decline was less than 4 ft in much 

of the study area (table 1). The difference between 1991 and 2009 water-level measurements is shown in table 1 and figure 5. 

If the differences between the 1991 and 2009 measurements are representative of the decline in the water level in the shallow 

aquifer, the average regional water-level decline has been less than 0.25 ft per year (ft/yr) in St. Helena, Tangipahoa, 

St. Tammany, and Washington Parishes and parts of Livingston Parish.

The greatest difference between the 1991and 2009 water-level measurements was in Baton Rouge and the surrounding 

area. In East Baton Rouge Parish and in western Livingston Parish, the water-level difference generally exceeded 5 ft between 

the 1991 and 2009 measurements (fig. 5). In East Baton Rouge Parish, differences in water-level measurements ranged from 

0.36 to -10.92 ft at four sites.

Hydrographs

Water levels at selected wells for the period 1990–2009 are shown on figure 6. Water levels fluctuated about 2 to 4 ft 

seasonally (each year) at sites Wa13 and Li122. Wells EB-827 and EB-1264 fluctuated 5 to 15 ft seasonally. Long-term 

declines for the period of record shown were about 0.5 ft/yr or slightly less at wells EB827, EB-1264, and Li122. Water 

levels in wells in and near the Baton Rouge area are influenced by groundwater withdrawals and changes in stage of the 

Mississippi River.

Selected References

Gesch, D.B., 2007, The National Elevation Dataset, in Maune, 

D., ed., Digital Elevation Model Technologies and 

Applications: The DEM Users Manual, 2nd Edition: 

Bethesda, Maryland, American Society for Photogrammetry 

and Remote Sensing, p. 99-118.

Gesch, D., Oimoen, M., Greenlee, S., Nelson, C., Steuck, M., 

and Tyler, D., 2002, The National Elevation Dataset: 

Photogrammetric Engineering and Remote Sensing, v. 68, 

no. 1, p. 5-11.

Golden Software, Inc., 2007, Grapher proprietary software 

version 7.0.1870: Golden, Colo., Golden Software, Inc.

Griffith, J.M., 2003, Hydrogeologic framework of 

southeastern Louisiana: Louisiana Department of 

Transportation and Development Water Resources Technical 

Report no. 72, 21 p., 18 pl.

Griffith, J.M., 2006, Hydrogeologic maps and sections of the 

“400-foot,” “600-foot,” and “800-foot” sands of the Baton 

Rouge area and adjacent aquifers in East and West Baton 

Rouge, East and West Feliciana, and Pointe Coupee Parishes, 

Louisiana: U.S. Geological Survey Scientific Investigations 

Report 2006-5072, 15 p., 13 pl.

Louisiana Oil Spill Coordinator’s Office, 2007, The 

Louisiana GIS CD—A digital map of the State, Version 2: 

Baton Rouge, La., Louisiana Oil Spill Coordinator’s 

Office, Office of the Governor, 2 CDs. (Also available at 

http://www.losco.state.la.us/products&publications.htm.)

Martin, Angel, Jr., and Whiteman, C.D., Jr., 1985, Map showing 

generalized potentiometric surface of aquifers of Pleistocene 

Age, southern Louisiana, 1980: U.S. Geological Survey 

Water-Resources Investigations Report 84-4331, 1 sheet.

Nyman, D.J., and Fayard, L.D., 1978, Ground-water resources 

of Tangipahoa and St. Tammany Parishes, southeastern 

Louisiana: Louisiana Department of Transportation and 

Development, Office of Public Works Water Resources 

Technical Report no. 15, 76 p.

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

Department of Transportation and Development Water 

Resources Special Report no. 16, 133 p.

Stuart, C.G., Knochenmus, Darwin, and McGee, B.D., 1994, 

Guide to Louisiana’s ground-water resources: U.S. Geological 

Survey Water-Resources Investigations Report 94-4085, 55 p.

Tomaszewski, D.J., 1988, Ground-water hydrology of 

Livingston, St. Helena, and parts of Ascension and Tangipahoa 

Parishes, southeastern Louisiana: Louisiana Department of 

Transportation and Development Water Resources Technical 

Report no. 43, 54 p.

Tomaszewski, D.J., 1996, Distribution and movement of 

saltwater in aquifers in the Baton Rouge area, Louisiana, 

1990-92: Louisiana Department of Transportation and 

Development Water Resources Technical Report no. 59, 44 p.

Tomaszewski, D.J., 2003, Ground-water resources along the 

lower Mississippi River, southeastern Louisiana: Louisiana 

Department of Transportation and Development Water 

Resources Technical Report no. 69, 23 p.

Walters, D.J., 1995, Louisiana ground-water map 

no. 7—Potentiometric surface, 1991, and water-level 

changes, 1969–91, of the Chicot equivalent aquifer system 

in southeastern Louisiana: U.S. Geological Survey 

Water-Resources Investigations Report 944202, 2 sheets.

Whiteman, C.D., Jr., 1979, Saltwater encroachment in the 

"600-foot" and "1,500-foot" sands of the Baton Rouge area, 

Louisiana, 1966–78, including a discussion of saltwater in 

other sands: Louisiana Department of Transportation and 

Development, Office of Public Works Water Resources 

Technical Report no. 19, 49 p.

Well name

Date

measured

Altitude of

land

surface, in

feet

above

NGVD 29

Water level,

2009, in feet

above or

below (-)

NGVD 29

Water level,

1991,

in feet

above or

below (-)

NGVD 29

Difference in

1991 and 2009

water level

(in feet)

EB-155 05/19/09 60 0.98 0.62 0.36

EB-827 04/22/09 63.96 17.34 26.28 -8.94

EB-896 04/16/09 82 61.44 66.12 -4.68

EB-934 04/24/09 51 2.03 12.95 -10.92

EB-1234 04/23/09 97 1.03

EB-1264 04/16/09 38 -2.67

EB-1278 04/21/09 31 -2.28

EB-1326 06/07/09 100 33.99

EF-256 06/19/09 210 162.59

EF-5282Z 06/22/09 260 192.77

EF-5499Z 06/22/09 272 200.24

Li-122 05/15/09 11 9.46

Li-209 05/26/09 59 30.32 37.56 -7.24

Li-231 05/28/09 37 22.07 28.14 -6.07

Li-258 05/15/09 73 53.26

Li-7288Z 05/14/09 12 4.02

Li-7294Z 05/14/09 55 32.43

Li-7405Z 05/15/09 60 46.41

Li-7412Z 05/14/09 37 12.94

Li-7763Z 05/28/09 50 38.31

Li-7945Z 06/01/09 2 0.24

Li-8038Z 06/01/09 12 -2.21

SH-46 05/01/09 185 149.74 153.35 -3.61

SH-48 05/26/09 245 185.77 188.51 -2.74

SH-53 05/04/09 170 154.24 155.03 -0.79

SH-54 05/01/09 235 190.75 192.55 -1.80

SH-56 05/26/09 77 67.22 70.05 -2.83

SH-74 05/05/09 270 229.59 232.72 -3.13

SH-75 05/01/09 110 102.19 103.22 -1.03

SH-76 05/01/09 250 231.39 234.22 -2.83

SH-5501Z 05/04/09 165 156.19

SH-5608Z 05/05/09 260 241.33

SH-5742Z 05/01/09 162 112.76

SH-5936Z 05/04/09 285 208.48

SH-5937Z 05/01/09 117 102.39

SH-6309Z 05/01/09 215 147.76

ST-604 07/23/09 66 53.57 57.56 -3.99

ST-611 06/02/09 28 19.74

ST-640 05/27/09 155 120.75 121.28 -0.53

ST-878 06/01/09 39 20.00

ST-920 06/05/09 40 26.01

ST-928 06/02/09 17 -1.27 2.00 -3.27

ST-9226Z 06/01/09 100 75.11

ST-12584Z 06/05/09 24 12.98

ST-15308Z 06/05/09 51 46.11

ST-16582Z 06/05/09 21 6.38

ST-17692Z 06/01/09 45 29.02

ST-18056Z 06/05/09 25 4.73

ST-18964Z 06/05/09 52 40.71

ST-22002z 06/05/09 59 42.57

ST-22003z 06/01/09 95 70.26

Ta-330 04/20/09 135 125.63 127.96 -2.33

Ta-351 04/20/09 210 139.63 142.05 -2.42

Ta-372 04/21/09 162 80.32 80.49 -0.17

Ta-384 04/23/09 58 45.35

Ta-427 04/15/09 240 219.22 221.25 -2.03

Ta-481 04/23/09 26 23.29 24.08 -0.79

Ta-502 04/23/09 66 54.83 54.04 0.79

Ta-518 04/20/09 221 156.53 158.76 -2.23

Ta-529 05/26/09 77 66.22 66.23 -0.01

Ta-556 04/21/09 101 84.73 88.51 -3.78

Ta-557 05/28/09 26 21.26 21.12 0.14

Ta-622 04/15/09 208 181.19

Ta-6551Z 05/27/09 206 152.11

Ta-8564Z 04/15/09 239 221.34

Ta-8818Z 05/28/09 200 139.92

Ta-10603Z 04/21/09 158 98.42

Ta-11368Z 04/20/09 237 180.19

Ta-11554Z 05/05/09 203 140.71

Ta-10243Z 04/21/09 76 66.19

Wa-13 05/27/09 95 87.61 87.57 0.04

Wa-76 04/15/09 261 189.36

Wa-160 05/28/09 330 280.58

Wa-209 06/10/09 95 101.00

Wa-233 05/28/09 195 147.92

Wa-238 06/10/09 104 109.60

Wa-5151Z 04/28/09 260 220.32 220.97 -0.65

Wa-5682Z 05/27/09 189 169.48

Wa-5985Z 05/28/09 185 180.97

Wa-6640Z 06/01/09 269 228.61

Wa-7427Z 05/28/09 144 138.89

Wa-8199Z 06/01/09 130 111.78

Wa-8410z 05/27/09 320 233.94

Wa-8920Z 06/10/09 200 184.38

Wa-8958Z 04/28/09 337 266.19

Wa-9086Z 04/28/09 250 209.44

Wa-9087Z 04/28/09 180 177.54

Wa-9228Z 06/10/09 119 109.77

Wa-9229Z 06/10/09 188 162.31

Wa-9230Z 05/28/09 134 127.13

WF-158 04/28/09 198 95.98

WF-5013Z 06/19/09 183 135.59

Washington Parish

West Feliciana Parish

Table 1. Water-level data used to construct the water-level surface of the

Chicot equivalent aquifer system in southeastern Louisiana, 2009.

East Baton Rouge Parish

East Feliciana

Livingston Parish

St. Helena Parish

St. Tammany Parish

Tangipahoa Parish

[Altitudes are presented in feet above the National Geodetic Vertical Datum of 1929

(NGVD 29); water-levels are presented in feet above or below (−) NGVD 29; differences in

water levels are presented in feet; --, no data]

Morganza

St. Francisville

Fordoche

Livonia

Frisco

New

Roads

Bueche

Port

Allen

Baker

Clinton

Denham Springs Livingston

Roseland

Amite

Greensburg

Albany

Ponchatoula

Hammond

Franklinton

Covington Abita Springs

Hickory

Mandeville

Slidell

Lacombe

Pearl River

Lake 

Pontchartrain

Lake 

Maurepas

200

200

150

150

100

100 50

50

0

0

250

250

100

200

150

75

50

25

0

250

75

125

125 125

250

250

250

200

200

Wa-13

Li-122

EB-1264

EB-827

EB-155

EB-896

EB-934

EB-1234

EB-1278

EB-1326

EF-256

EF-5282Z

EF-5499Z

Li- 209

Li- 231

Li-258

Li-7288Z

Li-7294Z

Li-7405Z

Li-7412Z

Li-7763Z

Li-7945Z

Li-8038Z

SH-46

SH-48

SH-53

SH- 54

SH-56

SH-74

SH-75

SH-76

SH-5501Z

SH-5608Z

SH-5742Z

SH-5936Z

SH-5937Z

SH-6309Z SH-Kedron 

Bap Ch

ST-22002Z

ST-604

ST-611

ST-640

ST-878

ST- 920

ST-928

ST-12584Z

ST-15308Z

ST-16582Z

ST-17692Z

ST-18056Z

ST-18964Z

ST-9226Z

ST-22003Z

Ta-330

Ta-351

Ta-372

Ta-384

Ta-427

Ta-481

Ta-502

Ta-518

Ta-529

Ta-556

Ta-557

Ta-622

Ta-11368Z

Ta-11554Z Ta-6551Z

Ta-8564Z

Ta-8818Z

Ta-10243Z

Ta 10603Z

Wa-160

Wa-209

Wa-233 Wa- 238

Wa-9230Z

Wa- 9228Z

Wa-9229Z

Wa-9087Z

Wa-5151Z

Wa-5682Z

Wa-5985Z

Wa-6640Z

Wa-7427Z

Wa-76

Wa-8199Z

Wa-8410Z

Wa-8920Z

Wa-8958Z

Wa-9086Z

WF-158

WF-5013Z

WEST 

FELICIANA

EAST

FELICIANA

ST. 

HELENA

EAST

BATON

ROUGE

LIVINGSTON

TANGIPAHOA

ST. TAMMANY

WASHINGTON

Bogalusa

WEST

BATON 

ROUGE

POINTE COUPEE

Tangipahoa River

Tickfaw River

Amite River

Bogue Chitto River

Mississippi River

Pearl River

Tchefuncte River

Thompson Creek

BATON

ROUGE

Modified from Louisiana Oil Spill Coordinator’s Office (2007)

WATER-LEVEL CONTOUR—Shows altitude at which water level would have stood in tightly 

cased wells. Dashed where approximately located. Contour interval, in feet, is variable. 

Datum is National Geodetic Vertical Datum of 1929 (sea level). 

FLOW ARROW—Shows general direction of groundwater flow.

CONTROL POINT USED FOR WATER-LEVEL SURFACE—Number is well identifier. 

See table 1 for water-level measurements in 2009. 

WELL WITH HYDROGRAPH—See figure 6

DIFFERENCE, IN FEET, BETWEEN 1991 AND 2009 WATER-LEVEL MEASUREMENTS AT WELL—

 +1 to -4

 -4 to -6 

 -6 to -12

100

EXPLANATION

+

A R K A N S A S

M

I S S I S S I P P

T

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X

A

S

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

Study Area

Boundary

LOUISIANA

9 1 ° 0 0  ́ 9 0 ° 0 0  ́

3 0 ° 0 0  ́

3 0 ° 3 0  ́

3 1 ° 0 0  ́

9 2° 0 0  ́

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Baton Rouge Fault

MILES

KILOMETERS

0 10 20

0 10 20

1990 2000 2010

0

4

8

12

16

20

1990 2000 2010

76

80

84

88

92

1990 2000 2010

-20

-10

0

10

20

30

YEAR

EB-1264

Land-surface 38 ft above NGVD29

Well depth 498 ft below land surface.

EB-827

Land-surface 63.96 feet above NGVD29

Well depth 370 feet below land surface.

Li-122

Land-surface 11 ft above NGVD29

Well depth 500 ft below land surface.

Wa-13

Land-surface 95 ft above NGVD29

Well depth 156 ft below land surface.

WATER LEVEL, IN FEET ABOVE OR BELOW NATIONAL GEODETIC VERTICAL DATUM OF 1929 (NGVD 1929)

Water-level measurement

Figure 5. Water-level surface in the Chicot equivalent aquifer system in southeastern Louisiana, 2009.

For additional information, contact:

Director, U.S. Geological Survey Louisiana Water Science Center

3535 S. Sherwood Forest Blvd.,Suite 120

Baton Rouge, Louisiana 70816

E-mail: dc_la@usgs.gov

Fax: (225) 298-5490

Telephone: (225) 298-5481

Home Page: http://la.water.usgs.gov

Figure 6. Water levels at selected wells, Wa-13, Li-122, EB-827, and EB-1264, screened in the Chicot 

equivalent aquifer system in southeastern Louisiana.

Publishing support provided by Lafayette Publishing Service Center

Suggested citation:

Tomaszewski, D.J., 2011, Water-level surface in the Chicot 

equivalent aquifer system in southeastern Louisiana, 2009: 

U.S. Geological Survey Scientific Investigations Map 3173, 2 pl.

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