U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2016–3049

July 2016

Prepared in cooperation with the Louisiana Department of Transportation and Development 

Water Resources of Tangipahoa Parish, Louisiana

Introduction

Information concerning the availability, use, and quality 

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

for proper water-resource 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 20.1 million gallons per day (Mgal/d) 

of water were withdrawn in Tangipahoa Parish, Louisiana, 

including 19.90 Mgal/d from groundwater sources and 

0.18 Mgal/d from surface-water sources1

 (table 1). Withdrawals 

for public supply accounted for nearly 73 percent of the total 

water withdrawn in 2010 (table 2). Water withdrawals for other 

categories of use included industrial, rural domestic, livestock, 

general irrigation, and aquaculture. Water-use data collected at 

5-year intervals from 1960 to 2010 indicated that total water 

withdrawals during the years 1960 and 2010 were similar at 

about 20 Mgal/d (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 across text and tables may result in different totals 

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

Lake Maurepas

subbasin

Tickfaw

subbasin

Tangipahoa

subbasin

Bogue Chitto subbasin

Liberty Bayou-Tchefuncta

 subbasin

Lake Pontchartrain

 subbasin

LIVINGSTON

PARISH

ST HELENA

PARISH

TANGIPAHOA

 PARISH

WASHINGTON

PARISH 

ST TAMMANY

PARISH

ST JOHN

 THE BAPTIST

 PARISH

90°30' 90°20'

90°10'

30°40'

30°30'

30°20'

90°40'

30°50'

31°00'

0 10 20 MILES

0 10 20 KILOMETERS

51

55

12

10

Kentwood

Amite

Roseland

Baptist

Hammond Robert

Folsom

Ponchatoula

Little Silver Creek

Tchefuncte River

Natalbany River

Tickfaw River

Pass

Manchac

Lake

Pontchartrain

 Lake

Maurepas

Tangipahoa River

B

ogue Chitto

Ta-268

Ta-278

O O

C

Ta-362

Ta-260

C

C

07375000

07376500 07375500

A

A'

LOUISIANA

MISSISSIPPI

GULF OF MEXICO

TANGIPAHOA

PARISH

TEXAS

ARKANSAS MISSISSIPPI

LOUISIANA

Base modified from U.S. Geological Survey digital data

Albers Equal-Area Conic projection

North American Datum of 1983

EXPLANATION

Approximate altitude of base of fresh

 groundwater, in feet below National 

 Geodetic Vertical Datum of 1929 

 (modified from Smoot, 1988)—Deepest 

 freshwater contained within the Jasper

 equivalent aquifer system

 Above 2,000

 2,000 to 2,499

 2,500 to 2,999

 3,000 to 3,499

 3,500 and deeper

Approximate area where intermediate sands

 contain saltwater

Line of section (see fig. 3)

River subbasin boundary

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)

Ta-278

A'A

O

C

07376500

07375500

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

in Tangipahoa Parish, Louisiana, 2010 (Sargent, 2011; B.P. Sargent, 

U.S. Geological Survey, written commun., 2015).

Aquifer system or

surface-water body Groundwater Surface water

Chicot equivalent

aquifer system

4.85

Evangeline equivalent

aquifer system

2.46

Jasper equivalent

aquifer system

12.59

Miscellaneous streams 0.18

Total 19.90 0.18

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

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

Use category Groundwater Surface water Total

Public supply 14.59 0.00 14.59

Industrial 1.14 0.00 1.14

Rural domestic 3.66 0.00 3.66

Livestock 0.18 0.18 0.36

General irrigation 0.27 0.00 0.27

Aquaculture 0.08 0.00 0.08

Total 19.90 0.18 20.08

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Year

0

2

4

6

8

10

12

14

16

18

20

22

Annual withdrawal, in million gallons per day

Groundwater

Surface water

EXPLANATION

Figure 2. Water withdrawals in Tangipahoa Parish, Louisiana, 

1960–2010 (Sargent, 2011).

Groundwater Resources 

The primary freshwater-bearing aquifer systems in 

Tangipahoa Parish, from near surface to deepest, include the 

Chicot equivalent, Evangeline equivalent, and Jasper equivalent 

aquifer systems (fig. 3). The base of fresh groundwater (water 

with a chloride concentration of 250 milligrams per liter 

[mg/L] or less) generally ranges from greater than 2,000 to 

3,500 feet (ft) below the National Geodetic Vertical Datum 

of 1929 (NGVD 29) in Tangipahoa Parish (fig. 1) (Smoot, 

1988). Aquifers in the parish generally dip and thicken to the 

south. Recharge to the aquifers is primarily from infiltration 

of precipitation in the area extending from central Tangipahoa 

Parish northward to about 100 miles (mi) into Mississippi. 

Leakage from adjacent aquifers and seasonal input from rivers 

also provide for some recharge (Griffith, 2003). Discharge 

from the aquifers is by natural flow into rivers, leakage into 

underlying aquifers, and withdrawal from wells. 

The Chicot Equivalent Aquifer System 

The primary aquifers composing the Chicot equivalent 

aquifer system in Tangipahoa Parish are the GonzalesNew Orleans aquifer, Upland terrace aquifer, and the upper 

Ponchatoula aquifer. The Upland terrace aquifer is present at or 

near land surface in the northern half of the parish. The upper 

Ponchatoula aquifer is present in the southern half of the parish 

and may be considered a subsurface extension of the Upland 

terrace aquifer (fig. 3) (Nyman and Fayard, 1978). The altitude 

of the base of the Chicot equivalent aquifer system ranges 

from about 125 ft above NGVD 29 near the northern parish 

line to about 900 ft below NGVD 29 near the southern parish 

line (Griffith, 2003). Aquifers in the Chicot equivalent aquifer 

system typically range in thickness from 100 to 400 ft (Nyman 

and Fayard, 1978). 

In 2009, water levels in the aquifer system ranged from 

about 250 ft above NGVD 29 near the northern parish line to 

about the NGVD 29 in the lowlands near the southern parish 

line. In the hilly northern part of the parish, the direction of 

groundwater flow in the Upland terrace aquifer is generally 

from hilltops towards major stream valleys. Regionally, the 

overall direction of flow in the Chicot equivalent aquifer system 

is to the south along the dip of the sediments (Tomaszewski, 

2011). In Tangipahoa Parish, water-level changes within the 

Chicot equivalent aquifer system are primarily related to longand short-term changes in precipitation. Water levels generally 

fluctuate during the year and declined about 5 ft between 1998 

and 2012 at well Ta-362 (fig. 4). 

State well-registration records indicated 7,877 active wells 

screened in the Chicot equivalent aquifer system in Tangipahoa 

Parish in 2015, including 7,042 domestic, 587 irrigation, 

221 public supply, and 27 industrial. Depths of these wells 

ranged from 16 to 800 ft below land surface. Reported well 

yields ranged from 1 to 1,000 gallons per minute (gal/min) 

(Louisiana Department of Natural Resources, 2015). In 2010, 

groundwater withdrawals from the Chicot equivalent aquifer 

system in Tangipahoa Parish totaled about 4.85 Mgal/d, 

including 1.19 Mgal/d for public supply, 3.29 Mgal/d for 

rural-domestic use, 0.10 Mgal/d for livestock, 0.26 Mgal/d 

for general irrigation, and 0.02 Mgal/d for aquaculture (B.P. 

Sargent, U.S. Geological Survey, written commun., 2012). 
VERTICAL SCALE GREATLY EXAGGERATED 10 MILES

10 KILOMETERS

0

0

5

5

400

FEET

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

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

A’

SOUTH

A

NORTH

(Source well-log data limited to approximately this depth)

Gonzales-New Orleans aquifer

Upper Ponchatoula

aquifer

Lower Ponchatoula aquifer

Lower Ponchatoula

aquifer Big Branch aquifer

Abita

aquifer

Covington

aquifer

Tchefuncte

aquifer ?

?

?

?

?

?

?

?

?

?

?

?

?

?

Tchefuncte

aquifer

Covington

aquifer

Hammond

aquifer

Tchefuncte

aquifer

Abita aquifer

Big Branch aquifer

Lower Ponchatoula aquifer

Lower Ponchatoula aquifer

Upper Ponchatoula aquifer

Upland terrace aquifer

Big Branch

aquifer

Covington aquifer

Abita aquifer

Kentwood

aquifer

Hammond

aquifer

Amite

aquifer

Amite aquifer

PassManchac

I-55 Generalized

surface profile

I-55 I-12

Kentwood Amite

TANGIPAHOAPARISH

ST. JOHN THEBAPTIST PARISH

Hammond

Chicot equivalent

aquifer system

Evangeline equivalent

aquifer system

Jasper equivalent aquifer system

EXPLANATION

Freshwater in sand

Saltwater in sand—Saltwater 

 contains greater than 250 milligrams 

 per liter chloride

Clay

Lithologic contact—Separates

 clay and sand layers. Dashed where

 approximate. Queried where uncertain

Hydrogeologic contact—Defines 

 boundary between conjoined or

 merged aquifers

Fault

?

Hydrogeologic contact—Defines the

 approximate boundary between

 aquifers or aquifer systems

Bend in section

Figure 3. Generalized north-tosouth hydrogeologic section through 

Tangipahoa Parish, Louisiana (modified 

from Griffith, 2003). Trace of section 

shown on figure 1.

Year

1990 1995 2000 2005 2010 2015

Water level, in feet

NGVD 29

25

50

75

100

125

235

240

245

250

Well: Ta-260 Aquifer: Amite

Aquifer system: Jasper equivalent

Well depth: 2,013 ft below land surface

Altitude of land surface: 130.86 ft above NGVD 29

Well: Ta-278 Aquifer: Covington

Aquifer system: Evangeline equivalent

Well depth: 1,430 ft below land surface

Altitude of land surface: 52 ft above NGVD 29

Well: Ta-268 Aquifer: Hammond

Aquifer system: Jasper equivalent

Well depth: 2,449 ft below land surface

Altitude of land surface: 35 ft above NGVD 29

Well: Ta-362 Aquifer: Upland terrace

Aquifer system: Chicot equivalent

Well depth: 43 ft below land surface

Altitude of land surface: 265 ft above NGVD 29

Figure 4. Water levels in wells Ta-362 screened in the Chicot 

equivalent aquifer system, Ta-278 screened in the Evangeline 

equivalent aquifer system, and wells Ta-260 and Ta-268 screened 

in the Jasper equivalent aquifer system in Tangipahoa Parish, 

Louisiana (see fig. 1 for well locations; U.S. Geological Survey, 

2012a). Land surface and water levels are measured in feet (ft) 

relative to the National Geodetic Vertical Datum of 1929 (NGVD 29).

The Evangeline Equivalent Aquifer System 

The aquifers composing the Evangeline equivalent aquifer 

system in Tangipahoa Parish are the lower Ponchatoula, 

Kentwood, Big Branch, Abita, and Covington aquifers (fig. 3). 

In Tangipahoa Parish, the altitude of the base of the Evangeline 

equivalent aquifer system ranges from about 600 ft below NGVD 

29 near the northern parish line to greater than 2,700 ft below 

NGVD 29 near the southern parish line (fig. 3) (Griffith, 2003). 

Aquifers in the Evangeline equivalent aquifer system typically 

range in thickness from 50 to 500 ft (Nyman and Fayard, 1978). 

In 2003, water levels in the Kentwood aquifer ranged from 

about 225 ft above NGVD 29 near the northern parish line to 

about 75 ft above NGVD 29 at Ponchatoula and indicated that 

groundwater flow was generally to the south in this aquifer 

(Prakken, 2004). Water levels declined about 15 ft between 1991 

and 2012 at well Ta-278 (fig. 4), located northeast of Hammond 

(fig. 1) and screened in the Covington aquifer. 

State well-registration records listed 101 active wells 

screened in the Evangeline equivalent aquifer system in 

Tangipahoa Parish in 2015, including 54 domestic, 24 public 

supply, 15 irrigation, and 8 industrial. Depths of these wells 

ranged from 155 to 2,040 ft below land surface. Reported well 

yields ranged from 6 to 1,500 gal/min (Louisiana Department 

of Natural Resources, 2015). In 2010, groundwater withdrawals 

from the Evangeline equivalent aquifer system in Tangipahoa 

Parish totaled about 2.47 Mgal/d, including 1.82 Mgal/d for 

public supply, 0.14 Mgal/d for industrial use, 0.37 Mgal/d for 

rural-domestic use, 0.07 Mgal/d for livestock, 0.01 Mgal/d for 

general irrigation, and 0.06 Mgal/d for aquaculture (B.P. Sargent, 

U.S. Geological Survey, written commun., 2012). 

The Jasper Equivalent Aquifer System 

The primary aquifers composing the Jasper equivalent 

aquifer system in Tangipahoa Parish are the Tchefuncte, 

Hammond, Amite, and Ramsay aquifers. The altitude of the 

top of the Jasper equivalent aquifer system ranges from about 

700 ft below NGVD 29 near Kentwood to about 2,700 ft below 

NGVD 29 near the southern parish line (fig. 3) (Griffith, 2003). 

Aquifers in the Jasper equivalent aquifer system typically range 

in thickness from 100 to 250 ft (Nyman and Fayard, 1978). 
Groundwater levels in the Hammond and Amite aquifers 

have declined since the 1950s because of groundwater 

withdrawals (Nyman and Fayard, 1978). Water levels in well 

Ta-268, located near Hammond and screened in the Hammond 

aquifer, declined about 7 ft from 1991 to 2012 (fig. 4). Water 

levels in well Ta-260, located in west-central Tangipahoa Parish 

at Roseland and screened in the Amite aquifer, declined about 

10 ft from 1991 to 2012. 

State well-registration records listed 83 active wells 

screened in the Jasper equivalent aquifer system in Tangipahoa 

Parish in 2015, including 54 public supply, 20 domestic, 

6 irrigation, and 3 industrial. Depths of these wells ranged from 

1,250 to 2,743 ft below land surface. Reported well yields ranged 

from 40 to 2,285 gal/min (Louisiana Department of Natural 

Resources, 2015). In 2010, groundwater withdrawals from the 

Jasper equivalent aquifer system in Tangipahoa Parish totaled 

about 12.59 Mgal/d, including 11.57 Mgal/d for public-supply 

use, 0.99 Mgal/d for industrial use, 0.01 Mgal/d for livestock,

and 0.01 Mgal/d for general irrigation. 

Groundwater Quality

Samples taken from freshwater wells in Tangipahoa Parish 

indicated that the Chicot, Evangeline, and Jasper aquifer systems 

have similar water quality, but some variation is present (table 

3). Samples were found to be soft2

 with respect to hardness and 

generally did not exceed the U.S. Environmental Protection 

Agency’s Secondary Maximum Contaminant Levels3

 (SMCLs) 

for dissolved solids and color. Median values for pH ranged 

from 7.0 to 7.9. Temperature increased with depth. Locally, 

concentrations of iron and manganese can greatly exceed 

the SMCLs. Hydrogen sulfide may be present locally in the 

Evangeline and Jasper equivalent aquifer systems (Nyman and 

Fayard, 1978).

Surface-Water Resources 

Surface-water resources in Tangipahoa Parish are found 

within three regional drainage basins that comprise multiple 

subbasins (fig. 1). Most of the parish is in the Lake Maurepas 

Basin (Hydrologic Unit Code [HUC] 080702), with much smaller 

areas in the Lake Pontchartrain Basin (HUC 080902) and Pearl 

Basin (HUC 031800). All three basins eventually discharge into 

Lake Maurepas, Lake Pontchartrain, or the Gulf of Mexico (U.S. 

Geological Survey, 2015). In 2010, about 0.18 Mgal/d of surface 

water were withdrawn for livestock from streams in Tangipahoa 

Parish (table 2). 

Lake Maurepas Basin

The Lake Maurepas Basin comprises the Tangipahoa (HUC 

08070205), Tickfaw (HUC 08070203), and Lake Maurepas 

(HUC 08070204) subbasins (fig. 1). The Tangipahoa River 

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), 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).

(within the Tangipahoa subbasin) flows into the parish from 

Mississippi, is fed by small streams, and eventually flows into 

Lake Pontchartrain about 12 mi southeast of Ponchatoula. The 

average streamflow for the Tangipahoa River at Robert (site 

number 07375500) was 1,148 cubic feet per second (ft3

/s) for the 

period 1938–2009 from a drainage area of about 646 square miles 

(mi2

) (U.S. Geological Survey, 2009). 

The Tickfaw subbasin within Tangipahoa Parish is primarily 

drained by the Natalbany River, which is fed by small streams 

and discharges into the Tickfaw River about 1.5 mi upstream 

from the mouth of the Tickfaw River on Lake Maurepas. The 

average streamflow for the Natalbany River at Baptist (site 

number 07376500) was 117 ft3

/s for the period 1943–2009 from a 

drainage area of about 79.5 mi2

 (U.S. Geological Survey, 2009).

Lake Maurepas and Pass Manchac are located in the Lake 

Maurepas subbasin. Lake Maurepas has a surface area of about 

91 mi2

 and an average depth of about 7 ft and is connected to 

Lake Pontchartrain by way of Pass Manchac (Shampine, 1971). 

Lake Pontchartrain and Pearl Basins

The Lake Pontchartrain Basin comprises the Liberty 

Bayou-Tchefuncta (HUC 08090201) and Lake Pontchartrain 

(08090202) subbasins in Tangipahoa Parish (fig. 1). The 

Tchefuncte River begins near the Tangipahoa-Washington 

Parish border and eventually flows into St. Tammany Parish 

and then Lake Pontchartrain. The average streamflow for the 

Tchefuncte River near Folsom (site number 07375000) was 

158 ft3

/s for the period 1943–2009 from a drainage area of about 

103 mi2

 (U.S. Geological Survey, 2009). Lake Pontchartrain is 

a shallow estuarine bay of the Gulf of Mexico and has a surface 

area of about 621 mi2

 and an average depth of about 11 ft 

(Shampine, 1971). 

The Pearl Basin is composed of only the Bogue Chitto 

subbasin (HUC 0318005) in Tangipahoa Parish. This subbasin 

contains Little Silver Creek which drains out of Tangipahoa 

Parish and into the Bogue Chitto in Washington Parish.

Surface-Water Quality

Surface-water quality varies greatly in Tangipahoa Parish. 

Streams in the Tangipahoa and Liberty Bayou-Tchefuncta 

subbasins have good connection to the shallow aquifers, resulting 

in substantial groundwater influence on the quality of the surface 

water in these two basins. The Natalbany River and its tributaries 

are poorly connected to the shallow aquifers and are less affected 

by groundwater interaction (Fayard and Nyman, 1976). The 

majority of the parish is drained by freshwater streams that 

ultimately discharge into Lake Maurepas and Lake Pontchartrain. 

In both lakes, salinity varies substantially because of the influx 

of freshwater from streams and saline water from the Gulf of 

Mexico (Shampine, 1971). Saltwater intrusion may occur during 

droughts or storm events in the lower reaches of the streams that 

discharge into these lakes. 

Water samples analyzed during the period 1968–99 from the 

Tangipahoa River at Robert and during the period 1943–69 from 

the Natalbany River at Baptist were found to be soft with respect 

to hardness and did not exceed SMCLs for concentrations of 

chloride and sulfate (table 4). Dissolved-oxygen concentrations 

in samples from the Tangipahoa River were generally greater 

than 5 mg/L, which is considered the minimum value for a 
Table 3. Summary of selected water-quality characteristics for freshwater in the Chicot, Evangeline, and Jasper equivalent aquifer 

systems in Tangipahoa Parish, Louisiana (U.S. Geological Survey, 2012b).

[Values are in milligrams per liter, except as noted. °C, degrees Celsius; PCU, platinum cobalt unit; μS/cm, microsiemen per centimeter; 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]

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

Chicot equivalent aquifer system, 1939–2001 (31 wells)

Median 21.0 2 179 7.0 11 4.0 50 40 152

10th percentile 20.0 0 31 5.0 3 2.2 <10 <3 41

90th percentile 24.0 20 278 8.3 25 15 690 110 198

Number of samples 27 16 25 28 30 31 21 21 22

Percentage of samples that 

do not exceed SMCLs

NA 81 NA 57 NA 100 67 62 100

Evangeline equivalent aquifer system, 1939–2005 (36 wells)

Median 24.2 2 198 7.2 15 3.0 120 70 160

10th percentile 21.0 0 84 6.2 7 2.0 30 <20 67

90th percentile 29.4 13 300 8.8 26 4.5 1,500 320 187

Number of samples 28 20 27 22 29 36 18 17 22

Percentage of samples that 

do not exceed SMCLs

NA 90 NA 59 NA 100 67 35 100

Jasper equivalent aquifer system, 1939–2005 (55 wells)

Median 30.5 10 264 7.9 4 3.1 120 30 196

10th percentile 26.3 0 147 6.8 1 2.3 20 <20 161

90th percentile 34.0 30 428 9.1 9 6.1 1,100 140 265

Number of samples 37 36 46 43 45 55 31 19 35

Percentage of samples that 

do not exceed SMCLs

NA 72 NA 67 NA 100 68 63 97

SMCLs

NA 15 NA 6.5–8.5 NA 250 300 50 500

diverse population of fresh, warmwater biota, including sport fish 

(Louisiana Department of Environmental Quality, 2008). The 

median value for pH in samples from the Tangipahoa River was 

6.5 standard units and from the Natalbany River was 6.2 standard 

units. Turbidity may be more of a concern in the Natalbany 

River because of its path cutting through numerous clay deposits 

(Fayard and Nyman, 1976). 

References Cited 

Fayard, L.D., and Nyman, D.J., 1976, Surface-water resources of the Tangipahoa, 

Tchefuncta, and Natalbany River Basins, southeastern Louisiana: Louisiana 

Department of Public Works Water Resources Technical Report no. 11, 49 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.

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, 2015, Strategic Online Natural 

Resources Information System (SONRIS): Louisiana Department of Natural 

Resources database, accessed May 18, 2015, at http://sonris.com/.

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

and St. Tammany Parishes, southeastern Louisiana: Louisiana Department of 

Transportation and Development, Office of Public Works Water Resources 

Technical Report no. 15, 76 p. 

Prakken, L.B., 2004, Louisiana ground-water map no. 17—Generalized 

potentiometric surface of the Kentwood aquifer system and the “1,500-foot” 

and “1,700-foot” sands of the Baton Rouge area in southeastern Louisiana, March–April 2003: U.S. Geological Survey Scientific Investigations 

Map 2862, 2 sheets, accessed February 24, 2012, at http://pubs.er.usgs.gov/

publication/sim2862.

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. 

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/wri864314.
Table 4. Summary of selected water-quality characteristics for the Tangipahoa and Natalbany Rivers in Tangipahoa Parish, Louisiana 

(U.S. Geological Survey, 2012b). 

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

microgram per liter; SMCL, Secondary Maximum Contaminant Level established by the U.S. Environmental Protection Agency (2016); NA, not applicable; PCU, 

platinum cobalt units]

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)

Tangipahoa River at Robert, 1968–991

Median 49 8.6 6.5 10 2.3 1.0 4.9 5.9 2.2 220

10th percentile 45 7.1 6.1 8 2.0 0.6 3.7 4.5 1.1 130

90th percentile 57 10.3 7.0 12 2.8 1.2 5.8 7.4 4.5 350

Number of samples 130 114 128 130 131 130 128 128 128 75

Percentage of 

samples that do not 

exceed SMCLs

NA NA 52 NA NA NA NA 100 100 79

 SMCLs 

NA NA 6.5–8.5 NA NA NA NA 250 250 300

Natalbany River at Baptist, 1943–692

Specific

conductance, 

field

(μS/cm

at 25 °C)

Color 

(PCU)

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

)

Dissolved 

solids, 

filtered

Median 72 20 6.2 16 3.5 1.4 8 7.9 6.4 63

10th percentile 67 5 5.8 13.0 3.1 1.3 6.7 5.0 4.1 54.2

90th percentile 92 54 6.7 18.0 4.2 1.9 10.8 9.2 9.0 82.0

Number of samples 17 19 19 19 17 17 17 21 19 15

Percentage of 

samples that do not 

exceed SMCLs

NA 42 NA NA NA NA NA 100 100 100

SMCLs

NA 15 6.5–8.5 NA NA NA NA 250 250 500

1

Site number 07375500.

2

Site number 07376500.

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

system in southeastern Louisiana, 2009: U.S. Geological Survey Scientific 

Investigations Map 3173, 2 pls., accessed February 24, 2012, at http://pubs.

usgs.gov/sim/3173/.

U.S. Environmental Protection Agency, 2016, Secondary Drinking Water Standards: Guidance for Nuisance Chemicals, accessed April 13, 2016, https://

www.epa.gov/dwstandardsregulations/secondary-drinking-water-standardsguidance-nuisance-chemicals.

U.S. Geological Survey, 2009, Annual water-data reports: Accessed July 30, 

2010, at http://wdr.water.usgs.gov/.

U.S. Geological Survey, 2012a, Groundwater levels for Louisiana: National 

Water Information System Web Interface, accessed October 23, 2012, at 

http://nwis.waterdata.usgs.gov/la/nwis/gwlevels.

U.S. Geological Survey, 2012b, Water quality samples for Louisiana: National 

Water Information System Web Interface, accessed August 20, 2012, at 

http://nwis.waterdata.usgs.gov/la/nwis/qwdata/.

U.S. Geological Survey, 2015, Science in your watershed: Locate your watershed, accessed May 4, 2015, at http://water.usgs.gov/wsc/map_index.html.

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 DOTD, who 

contributed to the content of the fact sheet.

By Vincent E. White and Lawrence B. Prakken

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/fs20163049