U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2016-3099

February 2017

Prepared in cooperation with the Louisiana Department of Transportation and Development 

Water Resources of Concordia Parish, Louisiana

Introduction 

Information concerning the availability, use, and 

quality of water in Concordia 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 

(U.S. Geological Survey, 2016) are the primary sources of 

the information presented here. 

In 2010, over 50 million gallons per day (Mgal/d) of 

water were withdrawn in Concordia Parish, including about 

28.7 Mgal/d from groundwater sources and 22.3 Mgal/d from 

surface-water sources1

 (table 1). Withdrawals for agricultural 

use, composed of livestock, rice irrigation, general irrigation, 

and aquaculture accounted for about 77 percent (39.2 Mgal/d) 

of the total water withdrawn (table 2). Other categories of use 

included public supply, power generation, and rural domestic. 

Water-use data collected at 5-year intervals from 1960 to 2010 

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

1

Water-withdrawal data are based on estimated or reported site-specific data 

and aggregated data, which are distributed to sources. For a full description 

of water-use estimate methodology, see “Data Collection” in Sargent (2011). 

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

rounding; nonrounded numbers are used for calculation of totals. 

0 10 20 MILES

0 10 20 KILOMETERS

Base modified from U.S. Geological Survey digital data

Albers Equal-Area Conic projection

North American Datum of 1983

84

65

425

15

Co-50

Co-215

Co-45

07373291

07373420

07355601

07370190

07373291

07355601

07370190

Approximate altitude of base of fresh

 groundwater, in feet below National 

 Geodetic Vertical Datum of 1929 

 (NGVD 29) (modified from Smoot, 

 1988)—Deepest freshwater contained

 within the alluvial aquifer, except 

 where noted

 50 to 99

 100 to 149

 150 to 199

 200 to 299

 300 to 399

 400 to 499

 500 to 599

 600 to 699

 700 to 799

 800 to 999

 1,000 to 1,299

 1,300 and deeper 

Area where data indicate that aquifers 

 may contain freshwater at depths 

 greater than shown by Smoot, 1988

Area where intermediate sands contain 

 saltwater

Approximate boundary of area showing 

 deepest freshwater contained within 

 underlying Jasper aquifer system and

 Catahoula aquifer

River subbasin boundary

Line of section (see fig. 3)

Well for which hydrograph is shown

 (see fig. 4)

U.S. Geological Survey surface-water

 discharge site and number

U.S. Geological Survey surface-water

 quality site and number (see table 4)

EXPLANATION

Co-50

A'A

07355601

07373291

Bayou Cocodrie

subbasin

Black

subbasin

Lower Red

subbasin

Lower

MississippiNatchez

subbasin

Tensas

subbasin

Bayou Cocodrie

subbasin

Black

subbasin

Lower Red

subbasin

Lower

MississippiNatchez

subbasin

Tensas

subbasin

A'

A

A'

LOUISIANA

MISSISSIPPI

OLD RIVER CONTROL

STRUCTURE

Red River

Ouachita River Black River

Little River

Tensas River

Mississippi River

Cocodrie

Lake

Cocodrie

Lake

Concordia 

Lake

St John

Marengo Bend

Black River Lake

Atchafalaya

River

Cross

Bayou

Red River

Ouachita River Black River

Little River

Tensas River

Mississippi River

Cocodrie

Lake

Bay o u

Cocodrie

Lake

Concordia 

Lake

St John

Marengo Bend

Black River Lake

Atchafalaya

River

Cross

Bayou

Jasper

aquifer

system

Catahoula

aquifer

Catahoula

aquifer

Mississippi River

alluvial aquifer

Jasper

aquifer

system

Catahoula

aquifer

Catahoula

aquifer

Mississippi River

alluvial aquifer

Shaw

Monterey

Ferriday

Clayton

Vidalia

Fairview

Jonesville

Shaw

Monterey

Ferriday

Clayton

Vidalia

Fairview

Jonesville

TENSAS

PARISH 

AVOYELLES

PARISH

CATAHOULA

PARISH

WEST FELICIANA

PARISH

CONCORDIA

PARISH

TENSAS

PARISH 

AVOYELLES

PARISH

CATAHOULA

PARISH

POINTE

COUPEE

PARISH

WEST FELICIANA

PARISH

CONCORDIA

PARISH

91°20'

91°40'

92°00'

31°40'

31°20'

31°00'

GULF OF MEXICO

CONCORDIA

TEXAS

PARISH

ARKANSAS MISSISSIPPI

LOUISIANA

07355500

07373420

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

in Concordia Parish, Louisiana, 2010 (B.P. Sargent, U.S. Geological 

Survey, written commun., 2015).

Aquifer, aquifer system,

or surface-water body Groundwater Surfacewater

Mississippi River

alluvial aquifer

26.16

Jasper aquifer system 2.17

Catahoula aquifer 0.41

Bayou Cocodrie 9.14

Cross Bayou 2.95

Marengo Bend 1.50

Mississippi River 8.26

Miscellaneous streams 0.41

Total 28.74 22.25

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

category in Concordia Parish, Louisiana, 2010 (Sargent, 2011).

Use category Groundwater Surface water Total

Public supply 2.00 1.50 3.50

Power generation 0.00 8.26 8.26

Rural domestic 0.06 0.00 0.06

Livestock 0.10 0.02 0.11

Rice irrigation 10.81 10.81 21.62

General irrigation 14.08 1.56 15.64

Aquaculture 1.70 0.10 1.80

Total 28.74 22.25 50.99

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Year

Annual withdrawal, in million gallons per day

0

5

10

15

20

25

30

35

40

45

50

55

60

Groundwater

Surface water

EXPLANATION

Figure 2. Water withdrawals in Concordia Parish, Louisiana, 

1960–2010 (Sargent, 2011).

Groundwater Resources 

The primary freshwater-bearing aquifer in Concordia Parish 

is the Mississippi River alluvial aquifer. Other aquifers with 

freshwater underlying Concordia Parish include the Jasper aquifer 

system (fig. 3) and Catahoula aquifer (fig. 1). In the western part 

of the parish, the base of fresh groundwater (water with a chloride 

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

in the Mississippi River alluvial aquifer at depths ranging from 

about 50 feet (ft) to about 200 ft below the National Geodetic 

Vertical Datum of 1929 (NGVD 29) (fig. 1). In the eastern part of 

the parish, the base of fresh groundwater is present in the Jasper 

aquifer system or Catahoula aquifer at depths ranging from less 

than 200 ft to 1,000 ft below NGVD 29 (fig. 1) (Smoot, 1988). 

Saltwater (water with a chloride concentration that exceeds 

250 mg/L) is present in some localized areas above the base of 

freshwater (fig.1; Seanor and Smoot, 1995).

Mississippi River Alluvial Aquifer

The Mississippi River alluvial aquifer extends across all of 

Concordia Parish and is composed of the coarser part of sediments 

deposited primarily by the Mississippi River. These deposits 

generally grade from clay and silt at the surface to coarse sand 

and gravel at the base. The Mississippi River alluvial deposit 

thickness ranges from less than 140 ft to greater than 200 ft within 

the parish. The base of the aquifer ranges from shallower than 80 

ft below NGVD 29 in the northern part of the parish to greater 

than 160 ft below NGVD 29 near the southern tip of the parish 

(Whitfield, 1975). 

The primary source of recharge for the alluvial aquifer 

is the infiltration of precipitation with secondary sources of 

recharge from streams and rivers during high stage. Water 

generally moves southward in the alluvial aquifer. Groundwater 

discharges naturally by way of flow into streams and rivers and 

evapotranspiration, and artificially by way of well withdrawals 

(Whitfield, 1975).

In 1990, water levels in wells screened in the Mississippi 

River alluvial aquifer ranged from less than 50 ft above NGVD 

29 in the northern part of the parish to about 30 ft above NGVD 

29 in the southern part of the Parish (Seanor and Smoot, 1995). 

Water levels at well Co-215, located in the central part of the 

parish, have fluctuated annually less than about 10 ft and remained 

relatively stable during 1989–2015 (fig. 4). Water levels at well 

Co-45, located in the northeastern part of the parish near Lake 

St. John, fluctuated annually during 2012–2016, but show little 

change overall since the well was drilled in 1968. 

State well-registration records listed 383 active water wells 

screened in the Mississippi River alluvial aquifer in Concordia 

Parish in 2015, including 309 irrigation wells, 64 domestic wells, 

and 10 public-supply wells. Depths of these wells ranged from 

45 to 235 ft below land surface, and reported yields ranged from 

8 to 3,400 gallons per minute (gal/min) (Louisiana Department 

of Natural Resources, written commun., 2015). In 2010, about 

26.2 Mgal/d were withdrawn from the aquifer, with use categories 

including 0.15 Mgal/d for public supply, 0.05 Mgal/d for rural 

domestic, 0.09 Mgal/d for livestock, 10.38 Mgal/d for rice 

irrigation, 13.80 Mgal/d for general irrigation, and 1.70 Mgal/d 

for aquaculture (B.P. Sargent, U.S. Geological Survey, written 

commun., 2015). 
laf15-0712_fig03

0 5

5 10 KILOMETERS

10 MILES

0

-100

NGVD 29

A’

-200

-300

-400

-500

-600

Catahoula

aquifer

Williamson Creek aquifer Carnahan Bayou aquifer

Castor Creek 

confining unit

Cockfield

aquifer

Generalized land surface

A

Mississippi River alluvial aquifer

(Jasper aquifer system)

 100

-100

NGVD 29

-200

-300

-400

-500

-600

 100

SOUTH NORTH

Dough Hills confining unit

Vicksburg-Jackson confining unit

Lena confining unit

Freshwater in aquifer

Saltwater in aquifer—Saltwater

contains greater than

250 milligrams per liter chloride 

Clay

EXPLANATION

VERTICAL SCALE GREATLY EXAGGERATED

Figure 3. Idealized south-tonorth hydrogeologic section 

through Concordia Parish, 

Louisiana, showing aquifer 

and confining layer intervals 

(individual sand and clay 

layers not shown; modified 

from Whitfield, 1975, and 

Smoot, 1988, 1989). Trace of 

section shown on figure 1.

Jasper Aquifer System and Catahoula Aquifer

The Jasper aquifer system is composed of the Williamson 

Creek aquifer, the Dough Hills confining unit, and the 

Carnahan Bayou aquifer (fig. 3; Martin and others, 1988). In 

Concordia Parish, freshwater in these aquifers is only available 

in a less than 10-mile-wide band along the Mississippi River 

(fig. 1) and is recharged by precipitation in southwestern 

Mississippi (Martin and others, 1988; Smoot, 1988).

The Catahoula aquifer underlies all of Concordia 

Parish but contains freshwater only in the northeastern 

and northwestern parts of the parish (fig. 1). The aquifer is 

composed of sands that are typically white to light gray, range 

from very coarse to very fine grained, are seldom areally 

extensive, and are interbedded with silts and clays. Recharge 

to the aquifer is provided by the infiltration of precipitation and 

flow from underlying aquifers (Martin and Whiteman, 1986; 

Fendick and Carter, 2015). In 2013, water levels in two wells 

screened in the Catahoula aquifer, one near Jonesville and the 

other at the southern end of Lake St. John were about zero and 

40 ft above NGVD 29, respectively (Fendick and Carter, 2015). 

Water levels in the Catahoula aquifer at well Co-50 (fig. 1) 

declined about 50 ft from 1972 to 2015 (fig. 4).

 State well-registration records listed 28 active water wells 

screened in the Jasper aquifer system and Catahoula aquifer in 

Concordia Parish in 2015, including 6 domestic, 3 industrial, 3 

irrigation, and 16 public supply. Depths of these wells ranged 

from 275 to 765 ft below land surface, and reported yields 

ranged from 15 to 1,070 gal/min (Louisiana Department of 

Natural Resources, written commun., 2015). In 2010, about 

2.58 Mgal/d were withdrawn from the Jasper aquifer system 

and Catahoula aquifer, with use categories including 1.85 

Mgal/d for public supply, 0.008 Mgal/d for rural domestic, 0.01 

Mgal/d for livestock, 0.43 Mgal/d for rice irrigation, and 0.28 

Mgal/d for general irrigation (B.P. Sargent, U.S. Geological 

Survey, written commun., 2015).

 Groundwater Quality

Groundwater samples taken from the Mississippi River 

alluvial, Carnahan Bayou, and Catahoula aquifers were found 

to be within the U.S. Environmental Protection Agency’s 

Secondary Maximum Contaminant Levels2

 (SMCLs) for pH 

and sulfate (table 3). Median hardness was within the very hard3

range for the Mississippi River alluvial aquifer and within the 

soft range for the Carnahan Bayou and Catahoula aquifers. Iron 

and manganese concentrations were in excess of SMCLs for 

over 90 percent of samples in the Mississippi River alluvial and 

Carnahan Bayou aquifers. 

Surface-Water Resources 

Numerous surface-water resources in Concordia Parish 

are present in three regional drainage basins and flow in a 

general southerly direction. The Lower Mississippi-Natchez 

Basin (Hydrologic Unit Code [HUC] 080601) and co-located, 

co-named subbasin (HUC 08060100) drain the land adjacent to 

the Mississippi River (fig. 1). The Boeuf-Tensas Basin (HUC 

080500) contains the Tensas subbasin (HUC 08050003) and 

drains a relatively small area of land that is roughly adjacent 

to the Tensas River in the northern part of the parish (fig. 1). 

The majority of the parish is drained by the Lower Red Basin 

(HUC 080403), which is subdivided into three subbasins within 

Concordia Parish, including the Bayou Cocodrie subbasin (HUC 

08040306), Black subbasin (HUC 08040305), and the Lower 

Red subbasin (HUC 08040301) (fig. 1) (U.S. Geological Survey, 

2016). Numerous canals, control structures, and levees have 

modified the natural state of these resources.

2

The SMCLs are nonenforceable Federal guidelines regarding cosmetic 

effects (such as tooth or skin discoloration), aesthetic effects (such as taste, odor, 

or color), or technical effects (such as damage to water equipment or reduced 

effectiveness of treatment for other contaminants) of drinking water. SMCLs were 

established as guidelines by the U.S. Environmental Protection Agency (2016). 3

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).
laf15-0712_fig 04

No Data

No Data

No Data

1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012 2016

-10

NGVD 29

10

20

30

40

50

60

70

80

Year

Water level, in feet

Well: Co-215 

Aquifer: Mississippi River alluvial aquifer

Altitude of land surface: 45 ft above NGVD 29

Well depth: 121 ft below land surface

Well: Co-50

Aquifer: Catahoula aquifer

Altitude of land surface: 55 ft above NGVD 29

Well depth: 700 ft below land surface

Well: Co-45 

Aquifer: Mississippi River alluvial aquifer

Altitude of land surface: 65 ft above NGVD 29

Well depth: 133 ft below land surface

Figure 4. Water levels in well Co-45 and Co-215 screened in the Mississippi River alluvial aquifer 

and well Co-50 screened in the Catahoula aquifer in Concordia Parish, Louisiana (see fig. 1 for well 

locations; U.S. Geological Survey, 2016). Land surface and water levels are in feet (ft) relative to the 

National Geodetic Vertical Datum of 1929 (NGVD 29).

Lower Mississippi-Natchez and

Boeuf-Tensas Basins

The Mississippi River is sustained by drainage from 

over 40 percent of the conterminous United States but drains 

little land area in Concordia Parish because of levees along 

the river. The average flow of the Mississippi River near Red 

River Landing, near the southern tip of Concordia Parish (site 

number 07373291; fig. 1), was about 460,000 cubic feet per 

second (ft3

/s) for the period 1928–76 (Wells, 1980; Demcheck 

and others, 2004). The Old River Control Structure, located in 

the southern part of the parish (fig. 1), directs approximately 

30 percent of the combined flow of the Mississippi River and 

Red River above the structure to the Atchafalaya River (U.S. 

Army Corps of Engineers, 2009). In 2010, 8.26 Mgal/d were 

withdrawn from the Mississippi River for power generation, 

and 1.50 Mgal/d from the Marengo Bend oxbow lake for public 

supply (table 1). An additional 0.39 Mgal/d was withdrawn from 

miscellaneous streams for general irrigation (B.P. Sargent, U.S. 

Geological Survey, written commun., 2015). 

The Boeuf-Tensas Basin includes a reach of the Tensas 

River that forms the northwestern border of the parish. The 

Tensas River and subbasin end near Jonesville where the Tensas 

River merges with the Ouachita River and Little River to form 

the Black River (fig. 1). 

Lower Red Basin

The Bayou Cocodrie subbasin occupies the majority of 

the surface area of Concordia Parish and is drained primarily 

by Bayou Cocodrie, which originates near Ferriday, flows 

through the parish, and empties 

into the Red River near the 

southern tip of the parish. In 

2010, 9.14 Mgal/d of water were 

withdrawn from Bayou Cocodrie 

for rice irrigation (7.89 Mgal/d), 

general irrigation (1.17 Mgal/d), 

and aquaculture (0.08 Mgal/d). 

In addition, 2.95 Mgal/d of 

water were withdrawn from 

Cross Bayou for rice irrigation 

(2.92 Mgal/d) and aquaculture 

(0.03 Mgal/d) and 0.02 Mgal/d 

of water were withdrawn from 

miscellaneous streams for 

livestock (B.P. Sargent, U.S. 

Geological Survey, written 

commun., 2015).

The Black subbasin 

contains the Black River which 

serves as the southwestern border 

of the parish until emptying into 

the Red River. The Lower Red 

subbasin contains the Red River 

which forms part of the boundary 

of the southern tip of the parish 

and eventually merges with 

Mississippi River water diverted 

from the Old River Control 

Structure to form the Atchafalaya 

River (fig. 1). The average discharge of the Red River upstream 

from Concordia Parish at Alexandria (site number 07355500; 

fig. 1 index map) was 30,770 ft3

/s during 1928–82 (Carlson and 

others, 1983). 

Several lakes are present within or bordering these subbasins 

including Cocodrie Lake, Black River Lake, Lake Concordia, and 

Lake St. John. Recreational watersports, fishing, and swimming are 

popular on these lakes (Louisiana Wildlife and Fisheries, 2016). 

Surface-Water Quality

Water samples collected from the Mississippi River near 

St. Francisville (site number 07373420; fig. 1 index map) during 

1954–2013, Tensas River at Clayton (site number 07370190) 

during 1968–91, and Red River near Simmesport (site number 

07355601) during 1977–86 (fig. 1) were found to be generally 

within SMCLs for pH and concentrations of chloride, sulfate, 

iron, and dissolved solids (table 4). Median hardness values were 

within the hard range in the Mississippi River and within the 

moderately hard range in the Tensas River and Red River. Median 

values for dissolved-oxygen concentrations were greater than 

7 mg/L, whereas 5 mg/L is considered the minimum value for a 

diverse population of fresh, warmwater biota, including sport fish 

(Louisiana Department of Environmental Quality, 2008). 

Upstream activities affect the quality of Mississippi River 

water available to the parish. Concentrations of constituents such 

as agricultural pesticides and nutrients, are generally highest in late 

spring-early summer, commonly referred to as the “spring flush,” 

which results from the runoff of upstream applications of these 

pesticides and nutrients (Demcheck and others, 2004). Suspendedsediment concentrations are generally highest in late winter and 

early spring and lowest in late summer and fall (Wells, 1980).
Table 3. Summary of selected freshwater-quality characteristics for the Mississippi River alluvial, Carnahan Bayou, and Catahoula 

aquifers in Concordia Parish, Louisiana (U.S. Geological Survey, 2016).

[Values are in milligrams per liter, except as noted. μS/cm, microsiemen per centimeter; °C, degree Celsius; SU, standard unit; CaCO3, calcium carbonate; μg/L, 

microgram per liter; <, less than; SMCL, Secondary Maximum Contaminant Level established by the U.S. Environmental Protection Agency (2016);

NA, not applicable]

Specific 

conductance, 

field (μS/

cm

at 25 °C)

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, 

in μg/L

(as Fe)

Manganese, 

filtered, 

in μg/L

(as Mn) 

Dissolved 

solids, 

filtered

Mississippi River alluvial aquifer, 1941–2015 (47 wells)

Median 893 7.1 400 100 33.5 33 28 12.5 10,650 690 528

10th percentile 773 6.8 249.6 72.4 22.3 15.0 8.0 <0.2 5,950 194.2 425.8

90th percentile 1,250 7.8 480.2 120 43.2 81.2 141.8 30.3 16,000 1,336 729.6

Number of samples 81 34 40 33 33 28 103 30 20 17 25

Percentage of samples 

that do not exceed 

SMCLs

NA 100 NA NA NA NA 100 100 5 6 40

Carnahan Bayou aquifer, 1941–83 (13 wells) 

Median 632 7.2 16 4.5 1.2 120 12 5.4 895 205 406

10th percentile 527 7.0 4.6 1.2 <0.1 73 7.0 <0.4 494 79 351.1

90th percentile 1,144 7.8 180 46.8 13 264 214 17.5 1,380 345 715.9

Number of samples 13 13 17 13 13 13 17 16 8 4 12

Percentage of samples 

that do not exceed 

SMCLs

NA 100 NA NA NA NA 100 100 0 0 75

Catahoula aquifer, 1969–83 (10 wells)

Median 533 7.9 4 1.1 0.4 120 69 <1 105 40 354.5

10th percentile 411.5 7.5 1.9 0.5 0.1 97.4 42.4 <0.4 29 <10 302.8

90th percentile 976 8.1 6 1.4 0.6 202 171 3.2 409 62 595

Number of samples 10 10 10 10 10 10 10 10 10 9 10

Percentage of samples 

that do not exceed 

SMCLs

NA 100 NA NA NA NA 100 100 80 78 80

SMCLs

NA 6.5–8.5 NA NA NA NA 250 250 300 50 500

References Cited 

Carlson, D.D., Stallworth, G.R., Dantin, L.J., and Stuart, C.G., 1983, Water resources data, 

Louisiana, water year 1983: U.S. Geological Survey Water-Data Report LA–83–1.

Demcheck, D.K.; Tollett, R.W.; Mize, S.V.; Skrobialowski, S.C.; Fendick, R.B., 

Jr.; Swarzenski, C.M.; and Porter, Stephen, 2004, Water quality in the AcadianPontchartrain Drainages, Louisiana and Mississippi, 1999–2001: U.S. Geological 

Survey Circular 1232, 41 p. [Also available at http://pubs.water.usgs.gov/cir1232.]

Fendick, R.B., Jr., and Carter, Kayla, 2015, Potentiometric surface of the Catahoula aquifer 

in central Louisiana, 2013: U.S. Geological Survey Scientific Investigations Map 3339, 

1 sheet, accessed February 19, 2016, at http://dx.doi.org/10.3133/sim3339. 

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.

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 Wildlife and Fisheries, 2016, Waterbody management plans—Inland: Louisiana 

Wildlife and Fisheries Web page, accessed February 4, 2016, at http://www.wlf.

louisiana.gov/fishing/waterbody-management-plans-inland. 

Martin, Angel, Jr., and Whiteman, C.D., Jr., 1986, Generalized potentiometric surface of the 

Catahoula aquifer in central Louisiana, 1980: U.S. Geological Survey Water-Resources 

Investigations Report 86–4059, 1 pl.

Martin, Angel, Jr.; Whiteman, C.D., Jr.; and Becnel, M.J., 1988, Generalized potentiometric 

surfaces of the upper and lower Jasper and equivalent aquifers in Louisiana, 1984: U.S. 

Geological Survey Water-Resources Investigations Report 87–4139, 2 pls., accessed 

February 19, 2016, at https://pubs.er.usgs.gov/publication/wri874139.

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

and Development Water Resources Special Report no. 17, 135 p. 

Seanor, R.C., and Smoot, C.W., 1995, Louisiana ground-water map no. 6—Potentiometric 

surface, 1990, and water-level changes, 1974–90, of the Mississippi River alluvial 

aquifer in northeastern Louisiana: U.S. Geological Survey Water-Resources 

Investigations Report 95–4146, 2 sheets.

Smoot, C.W., 1988, Louisiana hydrologic atlas map no. 3—Altitude of the base of 

freshwater in Louisiana: U.S. Geological Survey Water-Resources Investigations Report 

86–4314, 1 sheet, accessed November 2, 2011, at http://pubs.er.usgs.gov/publication/

wri864150.

Smoot, C.W., 1989, Louisiana hydrologic atlas map no. 4—Geohydrologic sections of 

Louisiana: U.S. Geological Survey Water-Resources Investigations Report 87–4288, 1 

sheet, accessed February 10, 2012, at http://pubs.er.usgs.gov/publication/wri874288.

U.S. Army Corps of Engineers, 2009, Old River Control brochure: U.S. Army Corps of 

Engineers New Orleans District, accessed March 9, 2016, at http://www.mvn.usace.

army.mil/Portals/56/docs/PAO/Brochures/OldRiverControlBrochure.pdf.
Table 4. Summary of selected water-quality characteristics for the Mississippi River near St. Francisville, Tensas River at Clayton, and 

Red River near Simmesport, Louisiana (U.S. Geological Survey, 2016).

[Values are in milligrams per liter, except as noted. μS/cm, microsiemen per centimeter; °C, degree Celsius; SU, standard unit; CaCO3, calcium carbonate; μg/L, 

microgram per liter; <, less than; E, estimated; SMCL, Secondary Maximum Contaminant Level established by the U.S. Environmental Protection Agency 

(2016); 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, 

in μg/L

(as Fe)

Dissolved 

solids, 

filtered

Mississippi River near St. Francisville, 1954–20131

Median 378 8.6 7.7 140 39 11.7 18 20 47 <12.6 230

10th percentile 290 6.5 7.2 110 31.7 8.6 11.4 14 33.7 E <6 178

90th percentile 470 11.3 8 178 46.5 15.7 27.3 30 68 58 286

Number of samples 841 529 982 966 666 670 584 976 974 511 1,231

Percentage of 

samples that do 

not exceed SMCLs

NA NA 100 NA NA NA NA 100 100 100 100

Tensas River at Clayton, 1968–912

Median 292 7.9 7.3 110 28 9 15 18 11 25 168

10th percentile 123 5.6 6.5 42 12 3 4 4 6 <10 86.8

90th percentile 525 10.8 8.2 210 54 18 33 45 16 51 312.9

Number of samples 58 35 58 58 58 58 58 58 58 10 58

Percentage of 

samples that do 

not exceed SMCLs

NA NA 90 NA NA NA NA 100 100 100 100

Red River near Simmesport, 1977–863

Median 328 7.5 7.1 74 21 6 33 50 28 80 187

10th percentile 158 5.5 6.6 42 12 3 12 18 13 20 98

90th percentile 867 10.4 7.7 172 49 14 87 136 70 246 488

Number of samples 79 78 79 76 76 76 76 78 78 35 77

Percentage of 

samples that do 

not exceed SMCLs

NA NA 92 NA NA NA NA 100 100 94 90

SMCLs

NA NA 6.5–8.5 NA NA NA NA 250 250 300 500

1

Site number 07373420 (see fig. 1).

2

Site number 07370190 (see fig. 1).

3

Site number 07355601 (see fig. 1).

U.S. Environmental Protection Agency, 2016, Secondary Drinking Water Standards: 

Guidance for Nuisance Chemicals, accessed April 13, 2016, at https://www.epa.gov/

dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisancechemicals. 

U.S. Geological Survey, 2016, National Water Information System—Web interface, 

accessed September 28, 2016, at http://dx.doi.org/10.5066/F7P55KJN.

Wells, F.C., 1980, Hydrology and water quality of the lower Mississippi River: Louisiana 

Department of Transportation and Development, Office of Public Works Water 

Resources Technical Report no. 21, 83 p. [Also available at http://la.water.usgs.gov/

publications/pdfs/TR21.pdf.]

Whitfield, M.S., Jr., 1975, Geohydrology and water quality of the Mississippi River 

alluvial aquifer, northeastern Louisiana: Louisiana Department of Public Works Water 

Resources Technical Report no. 10, 29 p. [Also available at http://la.water.usgs.gov/

publications/pdfs/TR10.pdf.]

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

Survey in cooperation with the Louisiana Department 

of Transportation and Development. 

By Vincent E. White

For additional information, contact: 

Director, USGS Lower Mississippi-Gulf Water Science Center

3535 S. Sherwood Forest Blvd., Suite 120

Baton Rouge, LA 70816

E-mail: gs-w-lmg_center_director@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) https://doi.org/10.3133/fs20163099