U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2011–3086

August 2011

In cooperation with the Louisiana Department of Transportation and Development 

Water Resources of Caddo Parish

Printed on recycled paper

D O TD

APED TR MENT OF TRANSPORTATION AND DEVELOPMENT

Introduction 

In 2005, about 72.9 million gallons per day (Mgal/d) of 

water were withdrawn in Caddo Parish, Louisiana (fig. 1), 

including about 7.70 Mgal/d from groundwater sources and 

65.2 Mgal/d from surface-water sources (table 1). Public-supply 

use accounted for about 71 percent, and power generation 

accounted for about 19 percent of the total water withdrawn. 

Other categories of use included general irrigation, rural 

domestic, aquaculture, livestock, and industrial (table 2). 

Water-use data collected at 5-year intervals from 1960 to 2005 

indicate water withdrawals in the parish peaked in 1965 and 

generally decreased afterwards (fig. 2), primarily because of 

reduced surface-water withdrawals for power generation. From 

1965 to 2005, surface-water withdrawals for power generation 

declined from 419 to 14.2 Mgal/d.

This fact sheet summarizes basic information on the water 

resources of Caddo Parish, La. Information on groundwater 

and surface-water availability, quality, development, use, and 

trends is based on previously published reports listed in the 

references section. 

Base map modified from Official Map of Louisiana,

Louisiana Departmentof Transportation and Development, 1986

L O U I S I A N A

A R K A N S A S

M I S

S I S

S I P P

T

I

E X A S

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

ENLARGED

AREA

10 KILOMETERS

0

0

10 MILES

Cd-336 Well for which hydrograph 

 is shown (see fig. 4)

A A’ Trace of hydrogeologic

 section (see fig. 3)

0 to above 100

0 to -400 and deeper

Approximate altitude of the base of 

 fresh groundwater, in feet above or

 below National Geodetic Vertical 

 Datum of 1929 (Smoot, 1988)

Area where no major aquifer

 contains freshwater

EXPLANATION

07344370

Surface-water

 discharge site

Shettleworth

Bayou A

A’

ARKANSAS

BOSSIER

PARISH

TEXAS

Gilliam

Ida

Greenwood

Belcher

33° 00’

94° 00’ 93° 45’

32° 15’

Cd-336

Re d

Ri v e r Black Bayou Lake

Caddo Lake

e Jam s Bayou

32° 45’

32° 30’

Boggy Bayou

Paw Paw Bayou Paw Paw Bayou

07344370

I-49

I-20

71

71

171

1

5

3

2

Stonewall

Wallace Lake

Bayou Pierre

Cypress Bayou

Keatchie Bayou

RED RIVER

PARISH

DE SOTO

PARISH

Plain

Dealing

Hosston

Black Bayou

Black

Bayou

Vivian

Rodessa

Oil City

Bayou

Twelvemile

Shreveport

Blanchard

Bossier

City Cross Lake

Mooringsport Benton

CADDO

PARISH

Cross Bayou

Figure 1. Location of study area, 

Caddo Parish, Louisiana.
Groundwater Resources 

The primary groundwater resources of Caddo Parish, from 

near surface to deepest, include the Red River alluvial aquifer, 

the upland terrace aquifer, and the Carrizo-Wilcox aquifer. The 

Sparta aquifer and aquifers within the Cane River formation also 

yield freshwater in the northernmost parts of the parish (table 

1) but are not considered to be major resources because of their 

limited extents in the parish. Fresh groundwater (water with a 

chloride concentration of 250 milligrams per liter [mg/L] or less) 

is available throughout most of the parish at depths ranging from 

about 100 feet (ft) above the National Vertical Datum of 1929 

(NGVD 29) (sea level) near the western parish line to about 400 

ft below NGVD 29 near the northern parish line (fig. 1). Fresh 

groundwater is not available in an area east of Caddo Lake. 

Groundwater recharge and flow in Caddo Parish are affected 

by the Sabine uplift (an asymmetric structural dome) and faulting 

(fig. 3). Recharge to aquifers is from precipitation, leakage from 

adjacent aquifers, and seasonal input from streams. Discharge from 

the aquifers is by natural flow into streams, leakage into adjacent 

aquifers, and withdrawals from wells.

State well-registration records listed 3,741 active water wells 

in Caddo Parish in 2009, including 3,198 domestic, 233 publicsupply, 213 irrigation, 96 industrial, and 1 power generation wells. 

In 2005, groundwater withdrawals for various uses included public 

supply, industry, rural domestic, livestock, general irrigation, and 

aquaculture (table 2). 

The Red River Alluvial Aquifer 

The Red River alluvial aquifer borders the Red River and 

extends a maximum distance of about 10 miles (mi) westward into 

Caddo Parish from the river, which forms the eastern boundary 

of the parish. The aquifer is composed of sand and gravel beds 

within the alluvial deposits that are associated with the Red River 

and is hydraulically connected to the river. The alluvial deposits 

characteristically have a uniform sequence of clay, silt, sand, and 

gravel, with grain size increasing with depth. The thickness of the 

alluvial deposits ranges from about 25 to 100 ft. 

Recharge to the alluvial aquifer is primarily from precipitation 

that infiltrates the overlying silty soil and from adjacent aquifers. 

In some areas, the aquifer is partially confined by clay deposits, 

and infiltration is restricted. Clayey deposits underlie the Red 

River alluvial aquifer and restrict downward movement of water. 

Water in the alluvial aquifer tends to flow by gravity downdip 

along the base of the aquifer towards the south or southeast and 

along troughs cut into the base of the aquifer, where the alluvial 

deposits are thicker and coarser grained. 

Water levels in the alluvial aquifer fluctuate seasonally in 

response to precipitation, changes in the stage of adjacent rivers 

and streams, and withdrawal of water from the aquifer. Near the 

Red River, the alluvial aquifer receives recharge from the river 

when the river stage is higher than the water level in the aquifer; 

however, except for short periods when the Red River is at high 

stage, the alluvial aquifer generally discharges into the river. The 

hydrograph for well Cd-336 illustrates fluctuations in water levels 

in the alluvial aquifer (fig. 4). 

A statistical summary of selected water-quality characteristics 

for freshwater from the Red River alluvial aquifer is listed in table 

3. Freshwater from the aquifer is usually very hard (greater than 

180 mg/L as calcium carbonate) and generally exceeds the U.S. 

Table 1. Water withdrawals, in million gallons per day, by source 

in Caddo Parish, Louisiana, 2005 (modified from Sargent, 2007).

Aquifer or surface-water body Groundwater Surface water

Red River alluvial aquifer 1.96 —

Upland Terrace aquifer 0.46 —

Sparta aquifer 0.03 —

Cane River aquifer 0.02 —

Carrizo-Wilcox aquifer 5.23 —

Caddo Lake — 2.16

Cross Lake — 47.92

Pond (power generation) — 14.12

Twelvemile Bayou — 0.06

Miscellaneous streams — 0.89

Total 7.70 65.15

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

category in Caddo Parish, Louisiana, 2005 (modified from

Sargent, 2007).

Category Groundwater Surface 

water Total

Public supply 1.56 50.04 51.61

Industrial 0.09 0.04 0.12

Power generation 0.00 14.18 14.18

Rural domestic 1.63 0.00 1.63

Livestock 0.10 0.16 0.27

General irrigation 2.94 0.73 3.66

Aquaculture 1.39 0.00 1.39

Total 7.70 65.15 72.85

0

25

50

75

100

125

150

175

200

225

250

275

300

325

350

375

400

425

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Annual withdrawal, in million gallons per day

Year

Groundwater

Surface water

EXPLANATION

Figure 2. Water withdrawals in Caddo Parish, Louisiana, 1960–2005
0

0 10 KILOMETERS

10 MILES

EXPLANATION

Fault, relative movement

indicated by arrows

Vertical datum is National Geodetic Vertical Datum of 1929 (NGVD 29)

Vertical scale greatly exaggerated

NORTH

A A’

FEET

200

NGVD 29

-200

-400

-600

-800

-1,000

200

NGVD 29

-200

-400

-600

-800

-1,000

FEET

SOUTH

Land surface

Carrizo-Wilcox Aquifer

Midway

Confining

Unit

Sabine 

uplift

Carrizo-Wilcox Aquifer

Sparta

Aquifer

Cane River

Aquifer

Figure 3. Generalized north-to-south hydrogeologic section through Caddo Parish, Louisiana (Rapp, 1996). Trace of section shown on figure 1.

0

5

10

15

20

25

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Well: Cd-336

Altitudeof land surface: 182.47 ftaboveNGVD29

Well depth: 86 ftbelow landsurface

Water level, in feet below land surface

Year

Figure 4. Water levels in well Cd-336 screened in the Red River 

alluvial aquifer in Caddo Parish, Louisiana (see fig. 1 for well 

location; U.S. Geological Survey, 2011). Land surface is measured in 

feet above the National Geodetic Vertical Datum of 1929 (NGVD 29).

Environmental Protection Agency’s (EPA) Secondary Maximum 

Contaminant Levels (SMCLs)1 for drinking water for iron, 

manganese, and dissolved solids. Locally, water in the aquifer 

may be salty, with chloride concentrations exceeding the SMCL 

of 250 mg/L. 

State well-registration records listed 141 active water wells 

screened in the Red River alluvial aquifer in Caddo Parish in 

2009, including 70 irrigation, 52 domestic, 11 industrial, and 8 

1

 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 might exist. SMCLs were established as guidelines 

for the States by the U.S. Environmental Protection Agency (1992). 

public-supply wells. Depths of these wells ranged from 31 to 101 

ft below land surface, with a median depth of 61.5 ft. Reported 

yields from wells screened in the alluvial aquifer in Caddo Parish 

have ranged from 2 to 100 gallons per minute (gal/min). In 2005, 

groundwater withdrawals from the Red River alluvial aquifer in 

Caddo Parish totaled about 1.96 Mgal/d (table 1), including 0.07 

Mgal/d for public supply, 0.03 Mgal/d for rural-domestic use, 

0.03 Mgal/d for livestock, 1.27 Mgal/d for general irrigation, and 

0.56 Mgal/d for aquaculture. 

The Upland Terrace Aquifer 

In Caddo Parish, the upland terrace aquifer is present in 

a discontinuous band along the western edge of the Red River 

alluvial valley. About 10 percent of the surface area of Caddo 

Parish is underlain by terrace deposits, which range in thickness 

by about 25–60 ft. Primary outcrop areas are located along the 

tributaries to Wallace Lake in southern Caddo Parish, along 

the northern shore of Cross Lake, along the northeastern shore 

of Caddo Lake, and discontinuously along Black Bayou in 

northwestern Caddo Parish. 

Upland terrace deposits consist of clay, silt, and fine sand 

at the top, grading to coarse sand and gravel at the bottom. The 

principal source of recharge to the terrace deposits is precipitation 

in the outcrop area. Few water-quality data are available for wells 

screened in the upland terrace aquifer in Caddo Parish; however, 

data from four wells indicate the water is soft (0–60 mg/L as 

CaCO3) to moderately hard (60–120 mg/L as CaCO3). 

State well-registration records listed 32 active water wells 

screened in the upland terrace aquifer in Caddo Parish in 2009, 

including 17 irrigation, 13 domestic, and 2 public-supply wells. 

Depths of these wells ranged from 20 to 195 ft below land surface, 

with a median depth of 94 ft. Reported yields from wells screened 

in the upland terrace aquifer in Caddo Parish have ranged 10-100 

gal/min. In 2005, groundwater withdrawals from the upland 

terrace aquifer in Caddo Parish were about 0.46 Mgal/d (table 1), 

including about 0.45 Mgal/d for general irrigation and less than 

0.01 Mgal/d each for public-supply and rural-domestic uses. 
The Carrizo-Wilcox Aquifer 

The Carrizo-Wilcox aquifer is the most important aquifer 

in Caddo Parish because the aquifer contains freshwater 

throughout most of the parish. The aquifer outcrops in central and 

southwestern areas of the parish and dips towards both the north 

and south from central Caddo Parish (fig. 3). In the northern part 

of the parish, the aquifer is confined by clays of the Cane River 

Formation. The base of the Carrizo-Wilcox aquifer ranges from 

about 900 ft below NGVD 29 in northern Caddo Parish to 100 ft 

above NGVD 29 in central Caddo Parish and 400 ft below NGVD 

29 in southeastern Caddo Parish. In Caddo Parish, the CarrizoWilcox aquifer mainly consists of poorly interconnected, thin 

sand beds interbedded with clay, although some thick sands are 

present north of Caddo Lake. Saltwater is present in deeper sands 

of the aquifer throughout the parish. The aquifer is recharged 

by precipitation in outcrop areas and from overlying strata and 

primarily discharges into wells and streams. Flow of water in the 

aquifer is generally eastward towards the Red River. A statistical 

summary of selected water-quality characteristics for freshwater 

from the Carrizo-Wilcox aquifer is listed in table 3. Freshwater 

from the aquifer is soft (less than 60 mg/L as calcium carbonate) 

and generally does not exceed the SMCLs for color, pH, iron, 

manganese, and dissolved solids. Locally, iron concentrations can 

greatly exceed the SMCL of 300 μg/L (as indicated by the 90th

percentile value of 1,100 mg/L in table 3). 

Table 3. Summary of selected water-quality characteristics of freshwater in the Red River alluvial and Carrizo-Wilcox aquifers in 

Caddo Parish, Louisiana.

[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; <, less than; NA, not applicable; SMCL, Secondary Maximum Contaminant Level established by the 

U.S. Environmental Protection Agency (2006)]

Temperature 

(°C)

Color

(PCU)

Specific 

conductance, 

field(μS/cm

at 25°C)

pH,

field

(SU)

Hardness

(as CaCO3)

Chloride,

filtered

(as Cl)

Iron,

filtered

(μg/L as Fe)

Manganese,

filtered

(μg/L as Mn)

Dissolved

solids,

filtered

Red River alluvial aquifer, 1940–2000

Median 20.0 5 963 7.0 470 30 5,500 520 590

10th percentile 19.0 <5 679 6.6 220 7.4 330 130 396

90th percentile 22.4 12 1,340 7.3 610 120 15,400 2,300 826

Number of samples 43 36 59 47 80 83 57 59 38

Percentage of samples 

that do not exceed 

SMCLs

NA 94 NA 91 NA 100 11 3 29

Carrizo-Wilcox aquifer, 1940–2004

Median 20.7 8 587 7.9 40 40 50 12 350

10th percentile 19.5 <5 258 6.7 11 9.0 <6 <5 161

90th percentile 22.0 20 1,270 8.4 140 140 1,100 70 685

Number of samples 89 69 76 82 207 210 64 51 73

Percentage of samples 

that do not exceed 

SMCLs

NA 80 NA 89 NA 100 75 84 75

SMCLs

NA 15 NA 6.5–8.5 NA 250 300 50 500

State well-registration records listed 2,650 active water wells 

screened in the Carrizo-Wilcox aquifer in Caddo Parish in 2009, 

including 2,284 domestic, 202 public-supply, 84 irrigation, and 

80 industrial wells. Depths of these wells ranged 6–826 ft below 

land surface, with a median depth of 200 ft. Reported yields from 

wells screened in the Carrizo-Wilcox aquifer in Caddo Parish have 

ranged 3–800 gal/min. 

In 2005, groundwater withdrawals from the Carrizo-Wilcox 

aquifer in Caddo Parish totaled about 5.23 Mgal/d (table 1), 

including 1.48 Mgal/d for public supply, 0.09 Mgal/d for industry, 

1.57 Mgal/d for rural-domestic use, 0.07 Mgal/d for livestock, 1.19 

Mgal/d for general irrigation, and 0.83 Mgal/d for aquaculture. 

Surface-Water Resources 

In 2005, 65.1 Mgal/d of surface water was withdrawn in 

Caddo Parish for public-supply, industrial, power-generation, 

livestock, and irrigation uses (table 2). Sources of withdrawal in 

2005 included Cross Lake, a power-generation plant pond, Caddo 

Lake, miscellaneous streams, and Twelvemile Bayou (table 1). 

Most of the surface water withdrawn for power generation was 

used for cooling purposes and was returned to its source after use. 

Cross Lake is the primary source of fresh surface water in 

Caddo Parish. In 2005, the Shreveport Water System withdrew 

about 47.9 Mgal/d from Cross Lake for public supply. Smaller 

water systems withdrew about 2.13 Mgal/d from Caddo Lake 
in 2005. Other surface-water resources in the parish include the 

Red River, Cypress Bayou, Black Bayou Lake, and Wallace Lake. 

Cross Lake (fig. 1) was formed in 1926 when a dam was 

constructed across Cross Bayou to provide an adequate source 

of drinking water for the residents of the city of Shreveport. The 

elongated lake is oriented east to west and is approximately 9 

miles (mi) in length with an average depth of 7.7 ft. The lake 

covers approximately 13.4 square miles (mi2) in surface area and 

is 65,807 acre-ft in volume at spillway crest, which is 171.19 ft 

above NGVD 29. Much of the shoreline is urbanized, particularly 

along the eastern and southern shores. The major types of land use 

surrounding Cross Lake and within its watershed are forest land, 

forested wetlands, residential, and to a lesser degree, cropland and 

pastures. The lake receives inflow from a 253-mi2 watershed that 

includes eight major tributaries and supplemental flow through 

a pipeline from nearby Twelvemile Bayou. Most of the tributary 

inflow enters at the western end of the lake. The three largest 

tributaries and watershed areas are Paw Paw Bayou (82.02 mi2), 

Cross Bayou (62.43 mi2), and Shettleworth Bayou (19.54 mi2). 

The lake has two distributaries, the Cross Lake Dam and Spillway 

and a water-treatment plant intake, both located at the eastern 

end of the lake. 

A water-quality study of Cross Lake conducted from 1997 

to 1999 indicated that water in the lake is a sodium-bicarbonate 

type and is soft. Fluoride, sulfate, and total dissolved solids 

concentrations did not exceed the EPA’s SMCLs. Total (unfiltered) 

iron and total (unfiltered) manganese concentrations exceeded EPA 

SMCLs. Both iron and manganese occur naturally in the sediments 

of the Cross Lake watershed, and the high concentrations of 

total iron and total manganese in the lake water are most likely 

naturally occurring. 

A statistical summary of selected water-quality characteristics 

for Cross Lake collected from 10 sites during the 1997-1999 study 

is presented in table 4. Based on median values, water in the lake 

generally does not exceed the SMCLs for pH, chloride, or filtered 

iron. Dissolved oxygen is generally above 5 mg/L.

Caddo Lake (fig. 1) is located in northwestern Caddo Parish 

and extends into Marion County, Tex. The lake has a drainage 

area of 2,744 mi2. Major tributaries are Big Cypress Bayou in 

Texas and James Bayou in Louisiana, which enter at the western 

and northern ends of the lake. There also are numerous smaller 

tributaries. Lake water level is controlled by a spillway located at 

the eastern end. Spillway water discharges into Willow Pass, which 

becomes Twelvemile Bayou. The crest elevation of the spillway is 

Table 4. Summary of selected water-quality characteristics for Cross and Caddo Lakes in Caddo Parish, Louisiana, and the Red River at 

Coushatta, in Red River Parish, La. 

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

calcium carbonate; <, less than; NA, not applicable; SMCL, Secondary Maximum Contaminant Level established by the U.S. Environmental Protection Agency (2006)]

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)

Cross Lake, 1997–1999

Median 168 8.2 7.0 37 8.5 3.8 13 17 13 120

10th percentile 102 4.3 6.4 23 5.3 2.3 8.2 11 7 8

90th percentile 290 10.4 8.8 71 17 7.1 29 42 28 240

Number of samples 128 129 129 75 75 75 74 75 72 41

Percentage of samples that 

do not exceed SMCLs

NA NA 74 NA NA NA NA 100 100 95

Caddo Lake, 1973–1992

Median 105 8.8 6.7 22 5.1 2.3 9.3 13 11 140

10th percentile 94 6.9 6.2 18 4.1 2 8.2 11 7.3 20

90th percentile 122 10.5 7.2 27 6.6 2.5 11 17 15 370

Number of samples 32 32 32 31 31 31 30 31 32 29

Percentage of samples that 

do not exceed SMCLs

NA NA 84 NA NA NA NA 100 100 72

Red River at Coushatta, 1995–20091

Median 504 8.1 7.8 140 37 10 49 65 64 20

10th percentile 232 5.6 7.3 67 20 4.5 18 21 23 <6

90th percentile 1,200 11.8 8.2 290 73 23 130 190 160 90

Number of samples 170 156 172 167 167 169 168 170 170 66

Percentage of samples that 

do not exceed SMCLs

NA NA 93 NA NA NA NA 99 100 100

SMCLs

NA NA 6.5–8.5 NA NA NA NA 250 250 300

1

Station number 07350500 (U.S. Geological Survey, 2010b; specific data at http://nwis.waterdata.usgs.gov/la/nwis/qwdata/?site_no=07350500&).
By Lawrence B. Prakken and Jason M. Griffith

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

168.5 ft above NGVD 29, and the maximum design discharge 

of the spillway is 36,000 cubic feet per second (ft3/s). Caddo 

Lake is a wide, shallow lake, and shallow areas of the lake 

are densely vegetated. The lake has a surface area of about 26 

mi2, an average depth of 4.6 ft, and a depth of 4.6 ft or greater 

in more than 50 percent of the lake area. Greatest depths are 

located in the eastern part of the lake; east of the bridge on 

State Highway 538 (near Moorsingsport) the water depth is 

approximately 27 ft. Thirty-three water samples collected 

from Caddo Lake at the Highway 1 bridge near Mooringsport 

or at the spillway during 1973-1992 indicate that water in 

Caddo Lake is generally soft (0- 60 mg/L as CaCO3) and does 

not exceed EPA’s SMCLs for pH and for chloride and sulfate 

concentrations. Concentrations of filtered iron exceeded the 

SMCL of 250 mg/L in 8 of 29 samples (table 4). 

Although there were no reported withdrawals of water 

from the Red River in Caddo Parish in 2005, the river is a 

large potential source of freshwater. The average discharge of 

the Red River was 19,480 ft3/s for water years 1998–2008 at a 

site about 4.5 mi upstream from Caddo Parish at Spring Bank, 

Arkansas (station number 07344370). The highest mean daily 

discharge of the Red River during this 10-year period was 

138,000 ft3/s on March 14, 2001, and the lowest was 1,100 

ft3/s on October 11, 2006. Water samples collected during 

1995–2009 in the Red River at Coushatta, La., located about 17 

mi south of Caddo Parish in Red River Parish, indicate that the 

water is generally hard (121–180 mg/L as CaCO3). The pH and 

concentrations of chloride, sulfate, and iron generally meet the 

EPA’s SMCLs (table 4). 

Selected References 

McGee, B.D., 2004, Water-quality and bottom-material characteristics 

of Cross Lake, Caddo Parish, Louisiana, 1997-99: U.S. Geological 

Survey Water-Resources Investigations Report 03-4135, 101 p. 

Page, L.V., and May, H.G., 1964, Water Resources of Bossier and 

Caddo Parishes, Louisiana: Department of Conservation, Louisiana 

Geological Survey, and Louisiana Department of Public Works 

Water Resources Bulletin no. 5, 105 p. 

Rapp, T.R., 1996, Ground-water resources of Caddo Parish, Louisiana, 

1992: Louisiana Department of Transportation and Development 

Water Resources Technical Report no. 58, 89 p. 

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

Department of Transportation and Development Water Resources 

Special Report no. 16, 133 p. 

Smoot, C.W., 1988, Louisiana hydrologic atlas map no. 3: Altitude of 

the base of freshwater in Louisiana: U.S. Geological Survey WaterResources Investigations Report 86-4314, 1 sheet. 

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 July 29, 2009, at http://www.epa.gov/safewater/

consumer/2ndstandards.html.

U.S. Environmental Protection Agency, 2006, 2006 Edition of the 

drinking water standards and health advisories: Washington D.C., 

U.S. Environmental Protection Agency, Office of Water, 12 p. 

U.S. Geological Survey, 2010a, Water Quality Samples for Louisiana 

[data for USGS 07350500 Red R @ Coushatta, La.]: National Water 

Quality Information System Web Interface, accessed November 

5, 2009, at http://nwis.waterdata.usgs.gov/la/nwis/qwdata/?site_

no=07350500&.

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, Louisiana 

Department of Transportation and Development, who 

contributed to the content and design of the fact sheet.

U.S. Geological Survey, 2010b, Annual water-data report 2008 [for 

gage 07344370 Red River at Spring Bank, AR]: USGS Water 

Resources of the United States, Publications—Annual Water Data 

Reports, accessed November 6, 2009, at http://wdr.water.usgs.gov/

wy2008/pdfs/07344370.2008.pdf. 

U.S. Geological Survey, 2011, Ground-water levels for Louisiana 

[data for USGS 324207093484801 Cd- 336]: National Water 

Quality Information System Web Interface, accessed January 12, 

2011, at http://nwis.waterdata.usgs.gov/la/nwis/gwlevel/?site_

no=324207093484801&.