U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2014–3016

May 2014

Prepared in cooperation with the Louisiana Department of Transportation and Development 

Water Resources of Terrebonne Parish, Louisiana

EXPLANATION

Area where alluvial aquifer contains

 saltwater (freshwater may be available

 locally)

Marsh and swamp

Well completed in the Mississippi River 

 alluvial aquifer and name—Water-quality 

 site (see table 3)

U.S. Geological Survey surface-water 

 discharge site and number

U.S. Geological Survey surface-water 

 quality site and number (see table 4)

07381002

07381000

Te-5

#

C

O

315

57

.90

.

Bus

90

308

0 10 20 MILES

0 10 20 KILOMETERS

29°40'

29°30'

29°20'

29°10'

90°30'

90°40'

91°00' 90°50'

29°00'

29°50'

90°20'

30°00'

30°10' 91°10'

Base modified from U.S. Geological Survey digital data

Albers Equal-Area Conic projection

North American Datum of 1983

TEXAS

ARKANSAS MISSISSIPPI

LOUISIANA

TERREBONNE

PARISH

LAFOURCHE PARISH

ASSUMPTION PARISH

ST MARY

PARISH

TERREBONNE PARISH

ST JAMES

 PARISH

ASCENSION PARISH

LAFOURCHE PARISH

ASSUMPTION PARISH

ST MARY

PARISH

TERREBONNE

PARISH

ST JAMES

 PARISH

ASCENSION PARISH

Bayou Lafourche

Lake Raccourci 

Timbalier

Bay Terrebonne Bay 

GULF OF MEXICO

Atchafalaya

Bay Bayou Te rrebonne

Bayou Te rrebonne

Bayou Black

Lake

Barre

Waterway

Gulf IntracoastalGulf Intracoastal

Lower Atchafalaya RiverLower Atchafalaya River

Mississippi Mississippi River

Houma Navigation Canal

Bayou

Grand

Caillou Bayou du Large

Bayou

Petit

Caillou

Thibodaux

Houma

Dulac Dulac

Chauvin

Bayou Cane Bayou Cane

Donaldsonville

Valentine

Te-8

Te-4

Te-7

Te-6

Te-5

07381002

O

07381330

O

07381000 C

#

#

#

#

#

Introduction

Information concerning the availability, use, and quality 

of water in Terrebonne Parish, Louisiana (fig. 1), is critical for 

proper water-supply management. The purpose of this fact sheet 

is to present information that can be used by water managers, 

parish residents, and others for stewardship of this vital resource. 

Information on the availability, past and current use, use trends, 

and water quality from groundwater and surface-water sources 

in the parish is presented. Previously published reports (see 

References Cited section) and data stored in the U.S. Geological 

Survey’s National Water Information System (http://waterdata.

usgs.gov/nwis) are the primary sources of the information 

presented here. 

In 2010, 5.81 million gallons per day (Mgal/d) of water were 

withdrawn in Terrebonne Parish, including about 5.20 Mgal/d 

from surface-water sources and 0.61 Mgal/d from groundwater 

sources1

 (table 1). Public-supply use accounted for 70 percent 

(4.06 Mgal/d) of the total water withdrawn. Other categories of 

use included industrial, rural domestic, livestock, and aquaculture 

(table 2). Water-use data collected at 5-year intervals from 1960 

to 2010 (fig. 2) indicated that water withdrawals peaked in 1975 

at about 21.0 Mgal/d. Industrial use peaked at about 11.6 Mgal/d 

in 1970 and dropped to 0.07 Mgal/d in 1980. Aquaculture 

withdrawals were calculated to be about 11.9 Mgal/d in 1990 

and about 3.38 Mgal/d in 1995; however, most of the apparent 

decrease was due to a change in the calculations used to estimate 

water withdrawals for aquaculture, primarily crawfish farming 

(Lovelace and Johnson, 1996). 

1

Tabulation of numbers across text and tables may result in different totals 

because of rounding; nonrounded numbers are used for calculation of totals. 

Figure 1. Location of study area, Terrebonne Parish, Louisiana.
Table 1. Water withdrawals, in million gallons per day, by source 

in Terrebonne Parish, Louisiana, 2010 (modified from Sargent, 

2011).

Aquifer or

surface-water body Groundwater Surface water

Mississippi River alluvial aquifer 0.61

Bayou Black 0.23

Gulf Intracoastal Waterway 3.83

Other water bodies 1.14

Total 0.61 5.20

Table 2. Water withdrawals, in million gallons per day, by use 

category in Terrebonne Parish, Louisiana, 2010 (modified from 

Sargent, 2011).

Use category Groundwater Surface water Total

Public supply 0.00 4.06 4.06

Industrial 0.24 0.00 0.24

Rural domestic 0.01 0.00 0.01

Livestock 0.01 0.03 0.03

Aquaculture 0.35 1.12 1.47

Total 0.61 5.20 5.81

0

5

10

15

20

25

Year

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Annual withdrawals, in million gallons per day

Groundwater

Surface water

EXPLANATION

Figure 2. Water withdrawals in Terrebonne Parish, Louisiana, 

1960–2010 (Sargent, 2011).

Groundwater Resources 

In 2010, all reported groundwater withdrawals in 

Terrebonne Parish came from the Mississippi River alluvial 

aquifer. The Mississippi River alluvial aquifer is present 

throughout Terrebonne Parish and contains saltwater (water with 

chloride concentrations greater than 250 milligrams per liter 

[mg/L]); however, supplies of freshwater (water with chloride 

concentrations of 250 mg/L or less) can be found locally 

(Turcan, 1953). Within the parish, the base of the alluvial aquifer 

ranges from a maximum depth of about 425 feet (ft) below the 

National Geodetic Vertical Datum of 1929 (NGVD 29) to about 

75 ft below NGVD 29 in the southwestern corner of the parish. 

The base of the aquifer is about 300 ft below NGVD 29 in the 

vicinity of Houma (Saucier, 1994). 

The aquifer generally contains fine to medium sand in the 

upper part of the aquifer and grades to coarse sand and gravel 

in the lower part (Tomaszewski, 2003). Overlying the alluvial 

aquifer is a clayey surficial confining unit. The Mississippi River 

alluvial aquifer is hydraulically connected to the Mississippi 

River, which seasonally recharges the aquifer. The aquifer 

also is recharged by infiltration of rainfall through the surficial 

confining unit and by upward leakage from underlying aquifers. 

Discharge from the aquifer is by natural flow into rivers or 

canals, downward and lateral leakage into adjacent aquifers, and 

withdrawals from wells.

State well-registration records indicated that 41 active 

wells were screened in the Mississippi River alluvial aquifer in 

Terrebonne Parish in 2009, including 12 industrial, 11 irrigation, 

9 domestic, and 9 public supply. Depths of these wells ranged 

from 165 to 320 ft below land surface, with a median well depth 

of 240 ft. Reported yields from registered wells screened in the 

alluvial aquifer in Terrebonne Parish ranged from 4 gallons per 

minute (gal/min) for individual-user wells to 1,200 gal/min for 

large-capacity industrial wells (Louisiana Department of Natural 

Resources, 2012). In 2010, withdrawals from the alluvial aquifer 

in Terrebonne Parish were 0.61 Mgal/d, and uses included 

about 0.24 Mgal/d for industry, 0.01 Mgal/d for rural-domestic 

purposes, 0.01 Mgal/d for livestock, and 0.35 Mgal/d for 

aquaculture (tables 1 and 2). 

Selected water-quality characteristics for the Mississippi 

River alluvial aquifer in Terrebonne Parish from five wells (fig. 

1) are listed in table 3. Hardness levels were found to be in the 

very hard2

 range for these water samples from the aquifer. The 

U.S. Environmental Protection Agency’s Secondary Maximum 

Contaminant Levels (SMCLs)3 for drinking water were exceeded 

for color and concentrations of chloride, iron, manganese, and 

dissolved solids. 

2

Hardness ranges, expressed as milligrams per liter of calcium carbonate, are 

as follows: 0–60, soft; 61–120, moderately hard; 121–180, hard; greater than 

180, very hard (Hem, 1985).

3

The SMCLs are nonenforceable Federal guidelines regarding cosmetic 

effects (such as tooth or skin discoloration) or aesthetic effects (such as 

taste, odor, or color) of drinking water. At high concentrations or values, 

health implications as well as aesthetic degradation may result. SMCLs were 

established as guidelines for the States by the U.S. Environmental Protection 

Agency (1992).
Table 3. Selected water-quality characteristics for wells screened in the Mississippi River alluvial aquifer in Terrebonne Parish, 

Louisiana, 1954–76 (U.S. Geological Survey, 2012).

[Values are in milligrams per liter, except as noted. °C, degrees Celsius; PCU, platinum cobalt units; μS/cm, microsiemens per centimeter; SU, standard 

units; CaCO3, calcium carbonate; μg/L, micrograms per liter; —, insufficient data; SMCL, Secondary Maximum Contaminant Level established by the U.S. 

Environmental Protection Agency, 2011; NA, not applicable]

Well 

name

Well 

depth

(in feet, 

below 

land 

surface)

Sample date

Temperature 

(°C)

Color,

(PCU)

Specific 

conductance, field

(μS/cm

at 25 °C)

pH,

field

(SU)

Hardness 

(as 

CaCO3

)

Chloride,

filtered

(as Cl)

Iron,

unfiltered,

recoverable

(μg/L as 

Fe)

Manganese,

unfiltered,

recoverable

(μg/L as 

Mn) 

Dissolved 

solids, 

filtered

Te-4 188 Jan. 19, 1954 21.5 20 6,760 7.0 1,400 2,000 66,000 — —

Te-5 219 Feb. 2, 1962 20.5 100 2,070 7.0 620 460 16,000 400 1,390

Te-6 300 Oct. 19, 1976 23.0 — 8,390 — 1,400 2,500 — — —

Te-7 282 Oct. 19, 1976 — — 7,430 — 1,200 2,100 — — —

Te-8 280 Oct. 20, 1976 — — 14,600 — 2,200 4,800 — — —

SMCLs

NA 15 NA 6.5–8.5 NA 250 300 50 500

Surface-Water Resources 

In 2010, about 5.20 Mgal/d of surface water were 

withdrawn in Terrebonne Parish. Surface-water withdrawals 

in Terrebonne Parish for public supply came from the 

Gulf Intracoastal Waterway (GIWW) (3.83 Mgal/d) and 

Bayou Black (0.23 Mgal/d). Withdrawals for aquaculture 

(1.12 Mgal/d) and livestock (0.03 Mgal/d) from other water 

bodies accounted for the rest of the surface-water withdrawals 

in Terrebonne Parish (tables 1 and 2). Other notable water 

bodies, which did not have reported withdrawals, include 

Houma Navigation Canal and Bayous du Large, Terrebonne, 

Grand Caillou, and Petit Caillou (fig. 1). 

In 2010, about 9.93 Mgal/d of surface water were 

withdrawn from Bayou Lafourche in Lafourche Parish for use 

in Terrebonne Parish for public supply (Sargent, 2011). Bayou 

Lafourche is supplied by water from the Mississippi River 

at Donaldsonville. The bayou flows through southwestern 

Ascension Parish and northeastern Assumption Parish and 

into Lafourche Parish (fig. 1). Bayou Lafourche was a 

distributary channel of the Mississippi River until February 

23, 1904, when flow from the river was cut off by a dam at 

Donaldsonville to alleviate flooding. The dam turned Bayou 

Lafourche into a stagnant channel, and in 1955, a pumping 

plant at Donaldsonville began diverting about 250 cubic feet 

per second (ft3

/s) (161 Mgal/d) from the Mississippi River 

into Bayou Lafourche by a combined siphoning and pumping 

operation (Cardwell and others, 1965). During 1984–2013, the 

average daily discharge for Bayou Lafourche at Thibodaux (site 

number 07381000) (fig. 1) was about 191 ft3

/s (123 Mgal/d) 

(U.S. Geological Survey, 2013).

Water samples analyzed during 1996–99 indicated that 

water in Bayou Lafourche below the weir at Thibodaux (site 

number 07381002) (fig. 1) is generally hard and does not exceed 

the SMCLs for pH and concentrations of chloride, sulfate, and 

iron (table 4). Data analysis indicated that dissolved oxygen 

concentrations are generally greater than 5 mg/L, which is 

considered the minimum value for a diversified population 

of fresh, warmwater biota, including sport fish (Louisiana 

Department of Environmental Quality, 2008). 

In addition to providing the majority of freshwater within 

the parish, the GIWW is a major resource for commerce as the 

largest continuous ship channel in coastal Louisiana, traversing 

the entire Louisiana coast along the wetland-upland interface. 

Flow in the GIWW is generally from west to east in Terrebonne 

Parish as it captures freshwater from the Lower Atchafalaya 

River (Swarzenski, 2003).
Table 4. Summary of selected water-quality characteristics for Bayou Lafourche below weir at Thibodaux, Louisiana, and the Gulf 

Intracoastal Waterway (GIWW) at Houma, Louisiana (U.S. Geological Survey, 2012).

[Values are in milligrams per liter, except as noted. μS/cm, microsiemens per centimeter; °C, degrees Celsius; SU, standard units; CaCO3, calcium carbonate; 

μg/L, micrograms per liter; <, less than; SMCL, Secondary Maximum Contaminant Level established by the U.S. Environmental Protection Agency, 2011; NA, 

not applicable]

Specific 

conductance, 

field

(μS/cm

at 25 °C)

Oxygen, 

dissolved

pH,

field

(SU)

Hardness

(as CaCO3

)

Calcium, 

filtered

(as Ca)

Magnesium, 

filtered

(as Mg)

Sodium, 

filtered

(as Na)

Chloride, 

filtered

(as Cl)

Sulfate, 

filtered

(as SO4

)

Iron,

filtered

(μg/L

as Fe)

Bayou Lafourche below weir at Thibodaux, 1996–991

Median 429 6.5 7.6 150 39 12 21 26 46 <10

10th percentile 337 5.0 7.3 140 36 11 12 14 36 <10

90th percentile 510 10.0 7.9 180 46 15 30 33 58 10

Number of 

samples

9 8 10 11 11 11 10 10 11 8

Percentage of 

samples that 

do not exceed 

SMCLs

NA NA 100 NA NA NA NA 100 100 100

GIWW at Houma, 1978–812

Median 403 6.4 7.5 130 32 11 36 54 37 30

10th percentile 247 5.0 7.3 71 19 5.7 17 22 12 <10

90th percentile 2,930 9.2 7.8 420 62 64 490 810 150 140

Number of 

samples

25 24 25 24 24 24 24 25 25 24

Percentage of 

samples that 

do not exceed 

SMCLs

NA NA 100 NA NA NA NA 72 92 100

SMCLs

NA NA 6.5–8.5 NA NA NA NA 250 250 300

1

Site number 07381002 (U.S. Geological Survey, 2012; specific data at http://nwis.waterdata.usgs.gov/usa/nwis/qwdata/?site_no=07381002).

2

Site number 07381330 (U.S. Geological Survey, 2012; specific data at http://nwis.waterdata.usgs.gov/usa/nwis/qwdata/?site_no=07381330).

Water samples analyzed during 1978–81 indicated that the 

median value for hardness fell into the hard range in the GIWW 

at Houma (site number 07381330) (fig. 1). Constituent levels 

did not exceed the SMCLs for pH and iron and generally were 

below the SMCLs for concentrations of chloride and sulfate 

(table 4). Dissolved oxygen concentrations are generally greater 

than 5 mg/L. Saltwater from the Gulf of Mexico periodically 

intrudes into the GIWW and Bayou Lafourche, usually during 

low-flow or storm-surge events. This saltwater intrusion can 

cause substantial increases in specific conductance, hardness, 

and concentrations of calcium, magnesium, sodium, chloride, 

and sulfate. In the 5 years prior to the opening of Houma 

Navigation Canal in 1961, chloride concentrations above 

250 mg/L were unusual in the GIWW; however, from 1972 

to 1995, chloride concentrations in the GIWW breached the 

250 mg/L mark in all but 1 year. There were also several 

incidents of high chloride levels in Bayou Lafourche at 

Valentine. Because these two sources constitute about 87 percent 

of the Terrebonne Parish water supply, periods of elevated 

chlorides may affect the availability of freshwater in the parish 

(Johnson-Thibaut and others, 1998) (fig. 3).
0

50

100

Number of days

Figure 3. Days per year with chloride concentrations exceeding 250 milligrams per liter in the Gulf 

Intracoastal Waterway east of Houma Navigation Canal at Houma and Bayou Lafourche at Valentine, 

Louisiana, 1972-95 (modified from Johnson-Thibaut and other

Gulf Intracoastal Waterway east of Houma Navigation Canal at Houma

Bayou Lafourche at Valentine

EXPLANATION

1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983

Year

1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995

Figure 3. Days per year with chloride concentrations exceeding 250 milligrams per liter in the Gulf Intracoastal Waterway east of Houma 

Navigation Canal at Houma and Bayou Lafourche at Valentine, Louisiana, 1972–95 (modified from Johnson-Thibaut and others, 1998).

References Cited

Cardwell, G.T., Sloss, Raymond, and Duncan, A.C., 1965, Water, 

chap. V of Assumption Parish resources and facilities: Louisiana 

Department of Public Works and Assumption Parish Development 

Board, p. 25–38.

Hem, J.D., 1985, Study and interpretation of the chemical 

characteristics of natural water (3d ed.): U.S. Geological Survey 

Water-Supply Paper 2254, 264 p., accessed February 20, 2013, at 

http://pubs.er.usgs.gov/publication/wsp2254.

Johnson-Thibaut, P.M., Demcheck, D.K., Swarzenski, C.M., and 

Ensminger, P.A., 1998, Water use and quality of fresh surface-water 

resources in the Barataria-Terrebonne Basins, Louisiana: U.S. 

Geological Survey Open-File Report 98-632, 47 p., 1 pl. 

Louisiana Department of Environmental Quality, 2008, Environmental 

Regulatory Code, Title 33, Part IX, Subpart 1: Baton Rouge, 

Louisiana Department of Environmental Quality, accessed June 9, 

2009, at http:www.deq.louisiana.gov/portal/tabid/1674/Default.aspx.

Louisiana Department of Natural Resources, 2012, Strategic Online 

Natural Resources Information System (SONRIS): Louisiana 

Department of Natural Resources database, accessed May 11, 2012, 

at http://sonris.com/.

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

Louisiana Department of Transportation and Development Water 

Resources Special Report no. 11, 127 p. 

Sargent, B.P., 2011, Water use in Louisiana, 2010: Louisiana 

Department of Transportation and Development Water Resources 

Special Report no. 17, 135 p. 

Saucier, R.T., 1994, Geomorphology and Quaternary geologic history 

of the lower Mississippi Valley: Vicksburg, Miss., U.S. Army Corps 

of Engineers, v. 2, 28 pls. 

Swarzenski, C.M., 2003, Surface-water hydrology of the Gulf 

Intracoastal Waterway in south-central Louisiana, 1996–99: U.S. 

Geological Survey Professional Paper 1672, 51 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.
Turcan, A.N., Jr., 1953, Water, in Terrebonne Parish resources 

and facilities: Louisiana Department of Public Works and 

Terrebonne Parish Development Board, p. 42–44. 

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

Water Regulations—Guidance for nuisance chemicals: U.S. 

Environmental Protection Agency publication EPA 810/K-92-

001, 4 p., accessed September 28, 2011, at http://water.epa.gov/

drink/contaminants/secondarystandards.cfm. 

U.S. Environmental Protection Agency, 2011, 2011 Edition 

of the drinking water standards and health advisories: U.S. 

Environmental Protection Agency publication EPA 820-R11-002, Office of Water, 12 p., accessed September 2, 2011, 

at http://water.epa.gov/action/advisories/drinking/upload/

dwstandards2011.pdf. 

U.S. Geological Survey, 2012, Water-quality samples for 

Louisiana: National Water Information System Web Interface, 

accessed February 6, 2012, at http://nwis.waterdata.usgs.gov/la/

nwis/qwdata/. 

U.S. Geological Survey, 2013, Surface-water daily statistics for 

the Nation: National Water Information System Web Interface, 

accessed September 25, 2013, at http://waterdata.usgs.gov/nwis/

nwisman/.

This fact sheet was published by the U.S. Geological 

Survey, in cooperation with the Louisiana Department 

of Transportation and Development (DOTD). Thanks 

are given to Zahir “Bo” Bolourchi, Director, Water 

Resources Programs, DOTD, who contributed to the 

content of the fact sheet.

By Lawrence B. Prakken, John K. Lovelace, and

Vincent E. White

For additional information, contact: 

Director, USGS Louisiana Water Science Center

3535 S. Sherwood Forest Blvd., Suite 120

Baton Rouge, LA 70816

E-mail: dc_la@usgs.gov

Fax: (225) 298–5490

Telephone: (225) 298–5481

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

ISSN 2327-6916 (print)

ISSN 2327-6932 (online)

http://dx.doi.org/10.3133/fs20143016