U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2014–3102

February 2015

Prepared in cooperation with the Louisiana Department of Transportation and Development 

Water Resources of St. John the Baptist Parish, Louisiana

Introduction 

Information concerning the availability, use, and quality 

of water in St. John the Baptist 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 about 67.5 million gallons per day1

 (Mgal/d) of water 

were withdrawn in St. John the Baptist Parish. Surface-water 

sources accounted for about 80 percent of all withdrawals, whereas 

groundwater sources accounted for 20 percent (table 1). Withdrawals 

for industrial use accounted for 90 percent of the total water withdrawn. 

Other categories of use included public supply, rural domestic, 

livestock, and general irrigation (table 2). Water-use data collected at 

5-year intervals from 1960 to 2010 indicated that water withdrawals in 

the parish peaked in 1990 at about 110 Mgal/d (fig. 2). From 1980 to 

1985, surface-water withdrawals for industrial use declined from

93.7 to 35.0 Mgal/d before increasing to 91.0 Mgal/d in 1990. 

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 across text 

and tables may result in different totals because of rounding; nonrounded numbers are 

used for calculation of totals. 

SJB-145

A

A'

Lake

Pontchartrain

Lake

Maurepas

Mississippi River

Mississippi

Bayou

Tent Bayou Dutch Bayou

Pass Manchac

Lac des

Allemands

Blind River

310

310

10

55

22

18 18

52

61

90

61

51 641

640

626

306 631

3127

3160

ST CHARLES

PARISH

ST JAMES

PARISH

ASCENSION

PARISH

LIVINGSTON

PARISH

ST JOHN THE BAPTIST

PARISH

LAFOURCHE PARISH

JEFFERSON

PARISH

ST TAMMANY

PARISH

30°20' TANGIPAHOA PARISH

30°10'

30°00'

90°40' 90°30' 90°20' 90°10'

Base modified from U.S. Geological Survey digital data

Albers Equal-Area Conic projection

North American Datum of 1983

SJB-145

EXPLANATION

Approximate areas where aquifers within

 the Chicot equivalent aquifer system 

 contain only freshwater—Modified from

 Tomaszewski, 2003 

 Gramercy aquifer

 Norco aquifer—Boundary dashed and

 queried where uncertain

Approximate area of freshwater in the 

 Evangeline equivalent aquifer system—

 Modified from Griffith, 2003

Line of section (see fig. 3)

Fault—Approximate location at ground

 surface. Queried where uncertain 

Well for which hydrograph is shown

 (see fig. 4)

U.S. Geological Survey surface-water 

 quality site and number (see table 4)

U.S. Geological Survey surface-water 

 discharge site and number

A'A

07373291

C

07374400

O

0 5

0 5

10 MILES

10 KILOMETERS

07374400 O

Ruddock

Laplace

Luling

Edgard

Reserve

TEXAS ARKANSAS MISSISSIPPI

LOUISIANA

GULF OF MEXICO

ST JOHN THE BAPTIST

PARISH

C 07373291

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

in St. John the Baptist Parish, Louisiana, 2010 (Sargent, 2011; B.P. 

Sargent, unpub. data, 2011).

Aquifer, aquifer system, or 

surface-water body Groundwater Surface water

Gramercy aquifer 4.43

Norco aquifer 5.10

Gonzales-New Orleans aquifer 0.04

Evangeline equivalent

aquifer system

3.93

Mississippi River 53.97

Miscellaneous streams 0.08

Total 13.50 54.04

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

category in St. John the Baptist Parish, Louisiana, 2010 (modified 

from Sargent, 2011).

[<, less than]

Use category Groundwater Surface 

water Total

Public supply 3.93 2.53 6.46

Industrial 9.49 51.44 60.93

Rural domestic 0.09 0.00 0.09

Livestock 0.00 <0.01 <0.01

General irrigation 0.00 0.07 0.07

Total 13.50 54.04 67.55

0

10

20

30

40

50

60

70

80

90

100

110

120

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Year

Groundwater

Surface water

EXPLANATION

Annual withdrawals, in million gallons per day

Figure 2. Water withdrawals in St. John the Baptist Parish, 

Louisiana, 1960–2010 (Sargent, 2011).

Groundwater Resources 

The primary fresh groundwater sources (water with a 

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

less) in St. John the Baptist Parish include the Chicot equivalent 

aquifer system and the Evangeline equivalent aquifer system (fig. 

3). The Jasper equivalent aquifer system, which underlies the 

Evangeline equivalent aquifer system, may also contain limited 

supplies of freshwater in northern St. John the Baptist Parish, but 

it is not considered a primary source of fresh groundwater in the 

parish and is not discussed further.

Depth to the base of freshwater varies greatly within the 

parish. Freshwater is present to depths of about 700 feet (ft) 

below the National Geodetic Vertical Datum of 1929 (NGVD 

29) (fig. 3) south of the fault near Ruddock (fig. 1) in the Chicot 

equivalent aquifer system. North of the fault, freshwater is 

present at depths from about 200 ft to as much as 900 ft below 

NGVD 29 in the Chicot equivalent aquifer system and from 

about 2,300 to 3,100 ft below NGVD 29 in the Evangeline 

equivalent aquifer system (fig. 3); between these depths, the 

aquifer systems generally contain saltwater (water with a 

chloride concentration greater than 250 mg/L). 

Recharge to the freshwater areas of the Chicot and 

Evangeline equivalent aquifer systems results from infiltration 

of precipitation in areas where they outcrop or connect to 

outcropped aquifers to the north and northwest of Lake 

Pontchartrain. Recharge also comes through the clay confining 

layers that separate adjacent aquifers and in localized areas, 

where adjacent aquifers are merged or in hydraulic connection 

to unnamed shallow aquifers. These shallow aquifers receive 

recharge from infiltration of precipitation and from localized 

hydraulic connections to the Mississippi River (Dial and 

Kilburn, 1980; Dial and Sumner, 1989). Discharge from aquifers 

results from well pumping and from flow through hydraulic 

connections and confining layers to adjacent aquifers. State 

well-registration records listed 112 active water wells screened in 

the Chicot and Evangeline equivalent aquifer systems in St. John 

the Baptist Parish in 2009, including 52 domestic, 29 irrigation, 

17 industrial, and 14 public supply (Louisiana Department of 

Natural Resources, 2009). In 2010, groundwater withdrawals 

for various uses included public supply, industrial, and rural 

domestic (table 2). 

The Chicot Equivalent Aquifer System

In St. John the Baptist Parish, the primary aquifers of the 

Chicot equivalent aquifer system are the Gramercy, Norco, and 

Gonzales-New Orleans aquifers (fig. 3). Unnamed shallow sands 

may also contain limited supplies of freshwater. Figure 1 shows 

the locations of freshwater within the Gramercy and Norco 

aquifers in the Parish.

Gramercy Aquifer

In the areas of St. John the Baptist Parish where the 

Gramercy aquifer is present and contains freshwater (fig. 1), 

the top of the aquifer is about 175 to 200 ft below NGVD 29, 

and the aquifer thickness ranges from less than 100 ft to as 

much as about 160 ft, increasing generally from north to south 

(Tomaszewski, 2003). Grain size in the aquifer typically grades 

from fine sand at the top to coarse sand and fine gravel in the 

middle and lower parts of the aquifer (Dial and Kilburn, 1980). 

Water levels for well SJB-145 in the Gramercy aquifer fluctuate 
?

?

?

?

?

?

?

?

?

?

?

BEND INSECTIONBEND INSECTIONBEND INSECTIONBEND INSECTION

ST. CHARLESPARISHST. JOHNTHE BAPTISTPARISHST. JOHNTHE BAPTISTPARISH

TANGIPAHOAPARISH

PASS

MANCHAC

MISSISSIPPI

RIVER I-10 FAULT

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

“1,200-foot” sand

“1,200-foot” sand

?

Norco

aquifer

Gramercy Norco aquifer

aquifer

?

Slidell

aquifer

Upper Ponchatoula

aquifer

Tchefuncte

aquifer

Covington

aquifer

Abita

aquifer

Abita

aquifer

A

SOUTH

Chicot equivalent aquifer system

Chicot equivalent aquifer system

Evangeline equivalent aquifer system

Evangeline equivalent aquifer system Jasper equivalent aquifer system

A’

NORTH

VERTICAL DATUM IS NATIONAL GEODETIC VERTICAL DATUM OF 1929 (NGVD 29)

VERTICAL SCALE GREATLY EXAGGERATED 0

0 10 KILOMETERS

10 MILES

FEET

400

200

NGVD 29

-200

-400

-600

-800

-1,000

-1,200

-1,400

-1,600

-1,800

-2,000

-2,200

-2,400

-2,600

-2,800

-3,000

-3,200

-3,400

FEET

400

200

NGVD 29

-200

-400

-600

-800

-1,000

-1,200

-1,400

-1,600

-1,800

-2,000

-2,200

-2,400

-2,600

-2,800

-3,000

-3,200

-3,400

Big Branch

aquifer

Lower Ponchatoula 

aquifer

Lower 

Ponchatoula

aquifer

Upper

Ponchatoula

aquifer

Lower

Ponchatoula

aquifer

Big Branch aquifer

Abita 

aquifer

Covington aquifer

Slidell 

aquifer

GonzalesNew Orleans

aquifer

GonzalesNew Orleans

aquifer

EXPLANATION

?

?

Saltwater in sand—Saltwater contains

 greater than 250 milligrams per

 liter chloride

Freshwater in sand

Clay

Lithologic contact—Separates clay

 and sand units. Dashed where

 approximate. Queried where uncertain

Hydrogeologic contact—Defines

 boundary between conjoined

 or merged aquifers

Fault—Dashed where approximately

 located. Queried where uncertain

Big Branch

aquifer

Lower Ponchatoula aquifer

seasonally (fig. 4), coinciding with stages of the Mississippi 

River. The magnitude of fluctuation decreases with distance from 

the Mississippi River (Dial and Kilburn, 1980). 

State well-registration records listed 22 active wells screened 

in the Gramercy aquifer in St. John the Baptist Parish in 2009, 

including 8 domestic, 6 industrial, 6 irrigation, and 2 public 

supply. Depths of these wells ranged from 210 to 318 ft below 

land surface, with a median well depth of 260 ft. Reported yields 

from wells screened in the Gramercy aquifer in St. John the 

Baptist Parish have ranged from 2 to 2,006 gallons per minute 

(gal/min) (Louisiana Department of Natural Resources, 2009). In 

2010, groundwater withdrawals from the Gramercy aquifer in St. 

John the Baptist Parish totaled about 4.43 Mgal/d (table 1). All of 

the withdrawals were for industrial use, except about 0.01 Mgal/d 

for rural-domestic use. 

Previous reports and limited samples taken from nine wells 

during 1932–79 indicated that freshwater in the Gramercy aquifer 

is moderately hard to very hard,2

 has pH values ranging from 7.0 

to 7.7, and generally exceeds the U.S. Environmental Protection 

Agency’s Secondary Maximum Contaminant Levels3

 (SMCLs) 

for color and concentrations of total dissolved solids and iron 

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 might exist. SMCLs were established as guidelines 

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

Figure 3. South-to-north hydrogeologic 

section through St. John the Baptist 

Parish, Louisiana, showing aquifers and 

clay confining layers (modified from 

Griffith, 2003). Trace of section shown on 

figure 1.

(U.S. Geological Survey, 2013). Water quality, however, 

varies depending on location. Hardness tends to increase with 

increasing hydraulic connection to Mississippi River water 

(Hosman, 1972; Dial and Kilburn, 1980). 

Norco Aquifer 

In areas of St. John the Baptist Parish where the Norco 

aquifer is present and contains freshwater (fig. 1), the depth to 

the top of the aquifer ranges from about 250 ft below NGVD 29 

in the northern part of the parish to less than 400 ft below NGVD 

29 in the southern part of the parish (Tomaszewski, 2003; 

Griffith, 2003). The thickness of the aquifer ranges from less 

than 25 ft north of Laplace to more than 225 ft east of Laplace 

near the St. Charles Parish line. The upper part of the aquifer 

contains fine sand, and the lower part contains medium to coarse 

sand. Fine gravel may also be present in the lower part of the 

aquifer (Dial and Kilburn, 1980). 

State well-registration records listed 46 active wells 

screened in the Norco aquifer in St. John the Baptist Parish in 

2009, including 25 domestic, 9 irrigation, 8 industrial, and 4 

public supply. Depths of these wells ranged from 290 to 425 ft 

below land surface, with a median well depth of 370 ft. Reported 

yields from wells screened in the Norco aquifer in St. John the 

Baptist Parish have ranged from 22 to 3,460 gal/min (Louisiana 

Department of Natural Resources, 2009). In 2010, groundwater 

withdrawals from the Norco aquifer in St. John the Baptist 

Parish totaled about 5.10 Mgal/d (table 1). All of the withdrawals 

were for industrial use, except for about 0.04 Mgal/d for 
-4

-2

0

2

4

6

8

10

12

14

16

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Water level, in feet (ft) 

Year

Well: SJB-145

Altitude of land surface: 17.71 ft above NGVD 29

Well depth: 315 ft below land surface

Figure 4. Water levels in well SJB-145 screened in the Gramercy 

aquifer in St. John the Baptist Parish, Louisiana (see fig. 1 for well 

location; U.S. Geological Survey, 2009). Land surface and water 

levels are measured in feet relative to the National Geodetic 

Vertical Datum of 1929 (NGVD 29).

rural-domestic use. Freshwater samples taken from the Norco 

aquifer in St. John the Baptist Parish did not exceed the SMCL 

for pH but did exceed the SMCLs for color and dissolved solids 

concentration (table 3). Out of a total of 19 samples, 9 were 

found to be soft in respect to hardness, with the remaining 

10 samples ranging from moderately hard to very hard. 

Gonzales-New Orleans Aquifer 

The depth to the top of the Gonzales-New Orleans aquifer 

ranges from about 300 ft below NGVD 29 in the northern part 

of the parish to about 700 ft below NGVD 29 in the southern 

part (Tomaszewski, 2003; Griffith, 2003). The sand in the 

aquifer is very fine to fine (Hosman, 1972). The thickness of 

the Gonzales-New Orleans aquifer within the parish generally 

ranges from about 200 to less than 300 ft. In eastern and 

northwestern St. John the Baptist Parish, saltwater underlies 

the freshwater and is present at the base of the aquifer (fig. 3; 

Tomaszewski, 2003). 

State well-registration records listed 22 active wells 

screened in the Gonzales-New Orleans aquifer in St. John the 

Baptist Parish in 2009, including 10 domestic, 5 irrigation, 

3 industrial, and 4 public supply. Depths of these wells ranged 

from 458 to 625 ft below land surface, with a median well depth 

of 576 ft. Reported yields from wells screened in the GonzalesNew Orleans aquifer in St. John the Baptist Parish have ranged 

from 5 to 260 gal/min (Louisiana Department of Natural 

Resources, 2009). In 2010, about 0.04 Mgal/d were withdrawn 

from the Gonzales-New Orleans aquifer in St. John the Baptist 

Parish, mostly for rural-domestic use. During 1960–71, samples 

taken from 11 wells where freshwater is present in the upper 

part of the Gonzales-New Orleans aquifer in St. John the Baptist 

Parish indicated that water is soft, ranges in pH from 7.7 to 

8.4, exceeds the SMCL for color, and frequently exceeds the 

SMCL for total dissolved solids concentration (U.S. Geological 

Survey, 2013).

The Evangeline Equivalent Aquifer System

Freshwater is present in the deepest sand beds of the 

Evangeline equivalent aquifer system north of the approximate 

faultline shown on figure 1. The aquifer system is made up 

of a series of predominantly fine- to medium-grained sand 

beds separated by clay layers, which dip to the south (fig. 3). 

Thickness of individual sand beds varies but is typically from 

50 to 200 ft thick (Griffith, 2003). 

State well-registration records listed two active wells 

screened in the Evangeline equivalent aquifer system in 

St. John the Baptist Parish in 2009; both are public-supply 

wells located between Lakes Maurepas and Pontchartrain 

near Ruddock (fig. 1). Depths of these wells are 2,950 and 

3,000 ft below land surface. One of the wells reportedly yields 

2,120 gal/min (Louisiana Department of Natural Resources, 

2009). In 2010, groundwater withdrawals from the Evangeline 

equivalent aquifer system in St. John the Baptist Parish totaled 

about 3.93 Mgal/d (table 1). Samples taken during 1971–2005 

indicated that freshwater in the Evangeline equivalent aquifer 

system in St. John the Baptist Parish is soft and exceeds SMCLs 

for pH and color (table 3). 

Surface-Water Resources 

 In 2010, about 54.0 Mgal/d of surface water were 

withdrawn in St. John the Baptist Parish (table 1). Industrial use 

accounted for about 95 percent of the surface water withdrawn. 

Other uses included public supply and general irrigation (table 

2). Most surface water withdrawn for industrial use is used for 

cooling purposes and returned to its source after use (Sargent, 

2011). Major water bodies in or bordering the parish include 

the Mississippi River, Lakes Pontchartrain and Maurepas, 

and Lac des Allemands (fig. 1). There were no reported water 

withdrawals from these lakes in 2010. 

Mississippi River

St. John the Baptist Parish is divided by the Mississippi 

River (fig. 1), which flows in an easterly direction through 

the parish and is the major source of freshwater in the parish 

(table 1). In 2010, the river was the source of all surface-water 

withdrawals for industrial use and public supply in the parish. 

The average flow of the Mississippi River near Red River 

Landing (site number 07373291), about 170 mi upstream of 

Laplace (fig. 1, index map), was about 460,000 cubic feet per 

second for the period 1928–76 (Wells, 1980). The flow in the 

Mississippi River at Red River Landing is representative of 

flows in St. John the Baptist Parish because the section of the 

river between the landing and the parish is mostly leveed and 

has no major tributaries or distributaries. 
Table 3. Summary of selected water-quality characteristics of freshwater in the Norco aquifer and Evangeline equivalent aquifer 

system in St. John the Baptist Parish, Louisiana (U.S. Geological Survey, 2013).

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

CaCO3, calcium carbonate; SMCL, Secondary Maximum Contaminant Level established by the U.S. Environmental Protection Agency (2012); NA, not applicable]

Color

(PCU)

Specific

conductance, field 

(μS/cm at 25 °C)

pH,

field

(SU)

Hardness

(as CaCO3)

Chloride,

filtered

(as Cl)

Dissolved

solids, filtered

Norco aquifer, 1931–61 (19 wells) 

Median 90 1,350 7.7 72 170 872

10th percentile 40 1,290 7.4 45 140 753

90th percentile 140 1,460 8.0 230 210 1,040

Number of samples 19 5 9 19 19 12

Percentage of samples that 

do not exceed SMCLs

5 NA 100 NA 100 0

Evangeline equivalent aquifer system, 1971–2005 (4 wells)

Median 40 821 8.9 2.9 41 503

10th percentile 30 746 8.7 0 22 448

90th percentile 60 1,024 9 4 87.6 594

Number of samples 21 99 19 30 108 12

Percentage of samples that 

do not exceed SMCLs

0 NA 0 NA NA 42

SMCLs

15 NA 6.5–8.5 NA 250 500

Water samples analyzed during 1957–99 indicated that 

water in the Mississippi River at Luling, located about 27 miles 

downstream from Reserve (fig. 1), generally is hard and does 

not exceed SMCLs for pH and concentrations of chloride, 

sulfate, and iron (table 4). 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). 

Lakes

Lake Pontchartrain is a shallow estuarine bay which has 

a surface area of about 625 square miles (mi2) and an average 

depth of about 11 ft. There are appreciable spatial variations in 

salinity because Lake Pontchartrain is connected to the Gulf 

of Mexico. The northwestern and western areas of the lake 

may be fresh during some parts of the year (Demcheck, 1995; 

Shampine, 1971). Lake Maurepas has a surface area of 91 mi2

and an average depth of about 7 ft. Salinity in the lake varies 

because of the influx of saline water from Lake Pontchartrain at 

the east end of the lake and inflows of freshwater from tributary 

streams at the western and northern ends of the lake. Because 

of its salinity, the water in Lake Maurepas is unsuitable for 

many uses (Shampine, 1971). Lac des Allemands has a surface 

area of about 23 mi2 and an average depth of about 5 ft. Water 

quality in the lake varies spatially and seasonally. Chloride 

concentrations are moderately high and will occasionally 

exceed the SMCL of 250 mg/L (Shampine, 1971). 

References Cited 

Demcheck, D.K., 1995, The Lake Pontchartrain watershed—A 

unique resource of the Louisiana coast: U.S. Geological 

Survey Fact Sheet 118–95, 2 p.

Dial, D.C., and Kilburn, Chabot, 1980, Ground-water resources 

of the Gramercy area, Louisiana: Louisiana Department of 

Transportation and Development, Office of Public Works 

Water Resources Technical Report no. 24, 39 p. 

Dial, D.C., and Sumner, D.M., 1989, Geohydrology and 

simulated effects of pumpage on the New Orleans aquifer 

system at New Orleans, Louisiana: Louisiana Department of 

Transportation and Development Water Resources Technical 

Report no. 46, 54 p.

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

Louisiana: Louisiana Department of Transportation and 

Development Water Resources Technical Report no. 72, 21 p., 

18 pls. 

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.

Hosman, R.L., 1972, Ground-water resources of the Norco area, 

Louisiana: Department of Conservation, Louisiana Geological 

Survey, and Louisiana Department of Public Works Water 

Resources Bulletin no. 18, 61 p. 
Table 4. Summary of selected water-quality characteristics for the Mississippi River at Luling, Louisiana, 1957–99 (U.S. Geological 

Survey, 2013).

[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 (2012); 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)

 Mississippi River at Luling1

Median 398 8.2 7.6 150 40 11 21 24 50 <20

10th percentile 298 6.2 7.2 110 32 7.9 12 16 36 <10

90th percentile 500 11.2 7.9 180 48 15 34 36 71 60

Number of samples 665 328 656 659 634 636 365 662 662 294

Percent of samples 

that do not exceed SMCLs

NA NA 99.8 NA NA NA NA 100 100 98.6

SMCLs

NA NA 6.5–8.5 NA NA NA NA 250 250 300

1

Site number 07374400.

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, 2009, Strategic 

Online Natural Resources Information System (SONRIS): 

Louisiana Department of Natural Resources database, accessed 

August 17, 2009, at http://sonris.com/.

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

Department of Transportation and Development Water 

Resources Special Report no. 17, 135 p. 

Shampine, W.J., 1971, Chemical, biological, and physical data 

for the major lakes and reservoirs in Louisiana: Louisiana 

Department of Public Works Basic Records Report no. 5, 98 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. 

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, 2012, 2012 Edition 

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

Environmental Protection Agency publication EPA 822-

S-12-001, Office of Water, 12 p., accessed August 7, 2012, 

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

dwstandards2012.pdf.

U.S. Geological Survey, 2009, Ground-water levels for Louisiana, 

[data for USGS 300234090390301 SJB-145]: National Water 

Information System Web Interface, accessed August 20, 

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

no=300234090390301.

U.S. Geological Survey, 2013, Water quality samples for 

Louisiana: National Water Information System Web Interface, 

accessed December 3, 2013, at http://nwis.waterdata.usgs.gov/

la/nwis/qwdata/.

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. 

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 Vincent E. White, Lawrence B. Prakken, and

Robert B. Fendick, Jr.

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)

http://dx.doi.org/10.3133/fs20143102