UNITED STATES

DEPARTMENT OF THE INTERIOR 

GEOLOGICAL SURVEY

THE SOUTHERN HILLS REGIONAL AQUIFER SYSTEM OF SOUTHEASTERN 

LOUISIANA AND SOUTHWESTERN MISSISSIPPI 

By Anthony Buono

Water-Resources Investigations Report 83-4189

Prepared in cooperation with the 

U.S. ENVIRONMENTAL PROTECTION AGENCY

Baton Rouge, Louisiana 

1983
UNITED STATES DEPARTMENT OF THE INTERIOR 

WILLIAM P, CLARK, Secretary

GEOLOGICAL SURVEY 

Dallas L. Peck, Director

For additional information 

write to:

District Chief

U.S. Geological Survey

P.O. Box 66492

Baton Rouge, LA 70896

(Telephone: (504) 389-0281)

Copies of this report can be 

purchased from:

Open-File Services Section 

Western Distribution Branch 

U.S. Geological Survey 

Box 25425, Federal Center 

Denver, CO 80225 

(Telephone: (303) 234-5888)
CONTENTS

Page

Abstract 1

Introduction 2

Purpose and scope 2

Approach 3

Previous studies and agencies having water-resources-related

functions - 3

Source of public-water and domestic-water supply 6

The Southern Hills regional aquifer system 7

Geohydrology 7

Aquifer recharge 16

Aquifer vulnerability to contamination 17

Direction and velocity of ground-water movement 17

Water quality 26

Alternate source of water supply 26

Population and water use 30

Southeastern Louisiana 30

Southwestern Mississippi 32

Summary and conclusions 33

Selected references 35

Louisiana 35

Mississippi 37

ILLUSTRATIONS

Figure 1. Map showing the location of the study area in Louisiana

and Mississippi 4

2. Map showing the extent and recharge area of the aquifer 

system and locations of detailed geohydrologic 

sections 5

3. Geohydrologic section from Mississippi to Baton Rouge 8

4. Geohydrologic section through Tangipahoa Parish in

southeastern Louisiana 10

5. Generalized geologic section showing the relation of

formations in southern Mississippi 11

6. Generalized section showing movement of ground water 

from the recharge area to the discharge area in 

southeastern Louisiana 12

7. Diagram showing the movement of a contaminant from a

surface source into the aquifer system 18 

8-12. Map showing the potentiometrie surface of the:

8. "600-foot" sand r April 1976, and the Ponchatoula

aquifer, May 1969 r in southeastern Louisiana 19

9. "1,500-foot" sand, 1979, and the Abita and Kentwood

aquifers, May 1974, in southeastern Louisiana 20

10. "2,000-foot" sand, 1979, computed by a digital

ground-water-flow model 21

11. Hammond aquifer, May 1974, in southeastern

Louisiana 22

12. Amite aquifer, May 1974, in southeastern Louisiana 23 

13. Map showing major streams in southeastern Louisiana 28

III
TABLES

Page

Table 1. Correlation of aquifer units in the Southern Hills 

aquifer system in southeastern Louisiana and 

southern Mississippi 13

2. Thickness and hydraulic conductivities of aquifers in

southeastern Louisiana and southwestern Mississippi 25

3. Water types and dissolved-solids concentrations in

aquifers in southeastern Louisiana and southwestern 

Mississippi 27

4. Discharge data and dissolved-solids concentrations for 

streams that are possible alternative sources of 

freshwater in southeastern Louisiana 29

5. Population and water use in southeastern Louisiana, 1970

and 1980, and projected to 1990 and 2000 31

6. Population and water use in southwestern Mississippi 32

IV
CONVERSION FACTORS

For use of readers who prefer to use metric units, conversion factors 

for terms used in this report are listed below:

Multiply By To obtain 

foot (ft) 0.3048 meter (m)

cubic foot per second 0.02832 cubic meter per second 

(ft3/s) (m3/s)

gallon (gal) 0.003785 cubic meter (m3 )

3.785 liter (1)

million gallons per day 3785 cubic meter per day 

(Mgal/d) (m3/d)

mile (mi) 1.609 kilometer (km)

square mile (mi2 ) 2.590 square kilometer (km2)

National Geodetic Vertical Datum of 1929 (NGVD of 1929): A geodetic 

datum derived from a general adjustment of the first-order level nets of 

both the United States and Canada, formerly called Mean Sea Level Datum of 

1929; referred to as sea level in this report.
THE SOUTHERN HILLS REGIONAL AQUIFER SYSTEM OF SOUTHEASTERN 

LOUISIANA AND SOUTHWESTERN MISSISSIPPI

By Anthony Buono

ABSTRACT

The Southern Hills regional aquifer system that is the primary source 

of water for public and domestic use in the northern 10 parishes of southeastern Louisiana was named in a petition to the Environmental Protection 

Agency to be protected as a sole or principal source of drinking water 

under Section 1424 of Public Law 93-523, the Safe Drinking Water Act. 

The aquifer system is comprised of a gulf ward dipping and thickening wedge 

of sediments that generally range in age from Pleistocene or Pliocene at 

the top to Miocene at the base. The system extends from the northern 

limit of the recharge area in the vicinity of Vicksburg, Mississippi, 

southward approximately to the Baton Rouge fault in the Baton Rouge area 

and the southern part of the eastern Florida Parishes of southeastern 

Louisiana.

In southeastern Louisiana, the aquifer system has been divided into 

as many as 13 aquifer units that are recognized to decrease in number 

northward where aquifer units coalesce because many of the separatinq clay 

layers disappear or are no longer mappable, or where younger formations in 

the geologic sequence pinch out in the updip section. Although the system 

has been locally divided into many aquifer units, these aquifers are 

recognized to be interdependent, collectively forming the Southern Hills 

regional aquifer system. Water in the aquifer system is almost exclusively a soft sodium bicarbonate type. In southeastern Louisiana, dissolvedsolids concentrations average about 210 mg/L (milligrams per liter). In 

southwestern Mississippi the Citronelle aquifer has an average dissolvedsolids concentration of 51 mg/L. In southern Mississippi the Miocene 

aquifer system has a median dissolved-solids concentration of 170 mg/L.

Within the study area several streams are available as alternative 

sources of water for public and domestic supply, the largest of which are 

the Mississippi and Pearl Rivers. Water from these streams, although of 

relatively good chemical quality, has not been accepted by local officials 

as a viable alternative supply. The reason for non-acceptance is the 

increased costs to users resulting from additional water treatment and the 

extensive delivery system that would be needed to distribute surface 

water, especially to users remotely located from a source stream. Based 

on the additonal water treatment alone, costs to users would nearly 

double.

In the 10 parishes of southeastern Louisiana, where the Southern 

Hills regional aquifer system is the primary source of water for public 

and domestic supply, during 1980 water use for these categories totaled
about 121 Mgal/d (million gallons per day), serving about 744,000 persons. 

In addition, in southwestern Mississippi, where the aquifer system is 

also the primary source of water for public and domestic supply, a total 

of 25 Mgal/d were used for these categories by about 273,000 persons. 

Based on projected growth, by the year 2000 water use will total about 

220 Mgal/d serving a population of about 1.5 million persons in 

southeastern Louisiana and southwestern Mississippi.

INTRODUCTION

The Capital Area Ground Water Conservation Commission (CAGWCC) was 

established by the 1974 Louisiana Legislature for the primary purpose of 

conserving and protecting the ground-water resources of a five-parish area 

in the vicinity of Baton Rouge in southeastern Louisiana. To ensure the 

most strict protection of the local ground-water resources from contamination, the commission has petitioned the U.S. Environmental Protection 

Agency (EPA) to designate the aquifer system serving the area as a sole 

or principal source of drinking water. The petition was submitted in 

accordance with Public Law 93-523, known as the Safe Drinking Water Act. 

Included in the area covered by the petition are the eastern Florida 

Parishes of southeastern Louisiana and the neighboring Mississippi 

counties that also depend on the aquifer system for drinking water. The 

northernmost parishes of southeastern Louisiana and all of the counties 

in Mississippi that have been included in the petition are in the recharge 

area for the aquifer system. The recharge area, which also has been 

included in accordance with Section 1424(e) of the Safe Drinking Water 

Act, is of particular concern to the petition because this is where the 

aquifer system intersects land surface, and is where contaminants could 

most easily enter and degrade water in the system.

The U.S. Geological Survey, under an interagency agreement with the 

Environmental Protection Agency, was requested to prepare detailed 

information on the petitioned aquifer system. The information will be 

used by EPA to determine whether the aquifer should be protected under 

the sole or principal source designation.

Purpose and Scope

The purposes of the investigation were to develop from available 

information (1) a description of the regional aquifer system serving as a 

public supply in the Capital Area Ground Water Conservation Commission 

district, the Florida Parishes1 of southeastern Louisiana, and the 

counties of southwestern Mississippi; and (2) to discuss potential 

alternative sources of freshwater.

The Florida Parishes of Louisiana are the parishes of East Baton 

Rouge, East Feliciana, West Feliciana, Livingston, St. Helena, St. 

Tammany, Tangipahoa, and Washington, collectively known in 1810 as the 

"Free and Independent State of West Florida" (Louisiana Legislative 

Council, 1955, p. 31-32).
'The study area (fig. 1) covers about 14,000 mi2 in 

Louisiana and southern Mississippi. The Louisiana parishes 

Mississippi counties that compose the study area are as follows:

southeastern 

and

LOUISIANA PARISHES

The CAGWCC district parishes

East Baton Rouge 

West Baton Rouge 

East Feliciana 

West Feliciana 

Pointe Coupee

The eastern Florida Parishes

Livingston 

St. Helena 

St. Tammany 

Tangipahoa

MISSISSIPPI COUNTIES

Adams

Amite

Claiborne

Copiah

Franklin

Hinds

Jefferson

Jefferson Davis

Lawrence

Lincoln

Marion

Pike

Rank in

Simpson

Warren

Walthall

Wilkinson

These parishes and counties compose the area of the study that 

extends from the northern limit of the recharge area in southwestern 

Mississippi to the approximate southern limit of the aquifer system in the 

vicinity of the Baton Rouge fault zone (fig. 2) in southeastern Louisiana.

Approach

The investigation was made through the use of information from 

previous investigations reporting on the geohydrology of southeastern 

Louisiana and southern Mississippi. Information used included: geohydrologic maps and cross sections showing the distribution of and stratigraphic and hydraulic relation of aquifer units within the aquifer system; 

water-quality data; potent iometric maps and diagrams showing the head 

distribution or the direction of ground-water movement within the system; 

and water-use data indicating the sources and quantities of water used. 

The information was compiled to present a detailed overview of the aquifer 

system, water use, and the sources of drinking water available to the 

Capital Area Ground Water Conservation Commission district and the 

Florida Parishes.

Previous Studies and Agencies Having Water-Resources-Related Functions

The reports of investigations used during this study are too numerous 

to be individually cited here. Therefore, the reader is referred to the 

"Selected References" section of this report, and to references cited 

within the text and on illustrations. This report has been written based 

on details of the geohydrology and water use obtained from these reports, 

which are county or parish, state, or regional in scope.
N

32° 

0 50 100 MILES

I I I I I l I I I I I

I ! I

0 50 100 KILOMETERS

Figure l.--The location of the study area in Louisiana and Mississippi
SCOTT

32

.._._u... - J

NEWTON j LAUDERDALE I

t 

I

CLARKE L

f*

\ «r; r

Northern limit of regional 

aquifer system and the

wuruiem iimu ui iwgKjnai 

aquifer system and the - 

systems recharge area

!

I ! LINCOLN I (.""n^SS*** - FRANKLIN - i

I

ijErri7^-

i j f \

1 / i ;_ eg. 

y/ j I WALTHALL 1^ V^

 JGj4!§§!§§!£ELL F&- 4 J. _ Jil? 7"T LOUISIANA \7 "T "" "" 7

A. / EAST / __ I S in » Brrrlkr/-'»J>niU 'I

89"

jo ->.I..OME T E:RS:

Figure 2. The extent and recharge area of the aquifer system and locations of

detailed geohydrologic sections.
The agencies that have water-resources-related functions in the study 

area are as follows:

Louisiana

1. Capital Area Ground Water Conservation Commission

2. Louisiana Department of Transportation and Development, Office of 

Public Works (formerly the Department of Public Works)

3. Louisiana Geological Survey

4. Louisiana Water Resources Institute, Louisiana State University, 

Baton Rouge

5. U.S. Geological Survey

Mississippi

1. Mississippi Bureau of Land and Water Resources

2. Mississippi Research and Development Center

3. Mississippi Geological Survey

4. U.S. Geological Survey

5. Water Resources Research Institute, Mississippi State University.

SOURCE OF PUBLIC-WATER AND DOMESTIC-WATER SUPPLY

The primary source of water for public and domestic supply in the 

CAGWCC district and the Florida Parishes is ground water (Walter, 1982, 

table 3) . Within this area, ground water is obtained primarily from the 

Southern Hills regional aquifer system that underlies and contains freshwater in the northern half of southeastern Louisiana. A secondary source 

of ground water that is used for rural-domestic self-supplied systems is 

from isolated local shallow aquifers that occur within the Quaternary 

alluvial deposits and within the shallow Pleistocene sands overlying the 

regional aquifer system. The area of the aquifer system named in the 

petition for protection as a sole or principal source of drinking water 

encompasses the area of use of the regional aquifer system in southeastern 

Louisiana and the recharge area affecting the aquifer system of southeastern Louisiana (fig. 2). Emphasis has been placed on the recharge 

area because this is where the aquifer system intersects land surface and 

is highly vulnerable to the introduction of contaminants into the system. 

Included in the study, because they are in the recharge area, are 17 counties in southwestern Mississippi that lie directly north of southeastern 

Louisiana. Within southwestern Mississippi, the Southern Hills aquifer 

system is the primary source of public and domestic water supply in 14 of 

the 17 counties, or about 85 percent of the Mississippi part of the study 

area.

SOUTHERN HILLS REGIONAL AQUIFER SYSTEM

The Southern Hills regional aquifer system extends from the northern 

limit of the Miocene formations in southwestern Mississippi, in the vicinity of Jackson and Vicksburg, southward to the area of the Baton Rouge 

fault zone. (See fig. 2.) The fault zone acts as a barrier to groundwater movement and is approximately the southern limit of freshwater in 

the system. South of the fault zone, water within the formations that 

compose the aquifer system is saline and not usable for potable water.
The western extent of the Southern Hills aquifer is marked by a zone 

of saline water within the Pliocene and Miocene sediments that lie 

beneath the Mississippi River alluvial valley (Rollo f 1960; Whitfield, 

1975). This zone represents the limit of flushing of saline water from 

the Pliocene and Miocene aquifers by ground water moving southeasterly 

and southwesterly toward the Mississippi River alluvial valley.

Ihe eastern boundary of the aquifer system is less clearly defined, 

because detailed potentiometric maps of the aquifer system in southern 

Mississippi are not available. However, based on potentiometric levels 

within the aquifer system in southern Mississippi (J. K. Arthur and B. E. 

Wasson, written commun., 1982), potentiometric maps of the aquifer system 

in St. Tammany and Tangipahoa Parishes (figs. 8, 9, and 11) and a potentiometric map of the "2,000-foot" sand of the Baton Rouge area (fig. 10), 

the direction of the ground-water movement within the Southern Hills 

aquifer is generally southerly or southwesterly toward the southern or 

western boundary of the study area. (See fig. 10.) East of the study 

area the direction of ground-water movement is southerly or southeasterly 

away from the aquifer system. The resulting, somewhat tenuous, groundwater divide forms the eastern boundary and is the basis for limiting the 

aquifer system to the area of Mississippi directly north of southeastern 

Louisiana.

Geohydrology

The Southern Hills aquifer system as named in this report is 

comprised of a gulfward thickening and dipping, complexly interbedded, 

series of sandy and clayey formations that generally range in age from 

Pleistocene or Pliocene at the top, to Miocene at the base. (See figs. 

3, 4, 5, and 6; table 1.) The base of the aquifer system generally has 

 been considered to be the base of freshwater (diagramaticallv shown in 

fig. 6) within the sedimentary sequence, defined as 250 mg/L or less 

chloride concentration in southeastern Louisiana and 1,000 mg/L or less 

dissolved-solids concentration in southern Mississippi. Based on these 

chemical concentrations, the aquifer system attains a thickness of more 

than 2,500 ft in the southernmost part of the study area (Nyman and 

Fayard, 1978, pi. 1; and Morgan, 1963, pi. 1). However, in accordance 

with Public Law 93-523, EPA has established (Federal Register, May 19, 

1980, vol. 45, No. 98, sec. 122.3, p. 33424) that all ground water 

containing dissolved-solids concentrations of 10,000 mg/L or less shall 

be considered as an underground source of drinking water and protected 

from endangerment by injection wells. To include all such underground 

sources of drinking water under a sole-source designation would increase 

slightly the thickness of the aquifer system to be protected under the 

petition. Because the mapping used for this report was based on chloride 

concentrations of 250 mg/L or dissolved-solids concentrations of 1,000 

mg/L or less to define the base of freshwater, these limits have been 

used in this description of the aquifer system.
North Updip

FEET

400;

200-

SEA LEvtL200- 

400-

600-

800-

1000-

1200-

1400-

1600-

1800-

2000

2200-

2400-

2600-

2800-

3000-

CITRONELLEr

FORMATION!

o

<.

2 

a. 

o

U-

<. _i 3 

o

§

0

<

0.

HATTIESBURG , 

FORMATION

CATAHOULA . 

SANDSTONE

MISSISSIPPI EAST 

FELICIANA

Vertical exaggeration approximately 26X

5 MILES

5 KILOMETERS

(For section location see figure 2.]

T,

T2

EXPLANATION

Quaternary Upland deposits 

Zone 1 

Zone 2 

Zone 3

Figure 3. Geohydrologic section
Downdip South

"2,800-FOOT" 

SAND

From Morgan. 1963. pi. 1

FEET 

4OO

ZOO

SEA LEVEL 

ZOO 

4OO 

600 

800 

IOOO

-1300

-1400

-1600

-1800

-2000

-2200

-2400

-2600

-2800

-3000

Quaternary aquifers

Pliocene and Miocene aquifers

Brackish-water aquifers

trom Mississippi to Baton Rouge.
SOUTH

2000

2200 H2400-\

2600 H

2800 H

3000 H3200

1012 KILOMETERS

(For location see figure 2.)

000

320C

Figure 4. Geohydrologic section through Tangipahoa Parish in southeastern Louisiana.
H- c

0>

LT! I

1-5 

0)

H- Na

0) oM

fi

H- O

CO8

ft 

HO D

cnsn>

i-«

0)

ClH- sor-h

i-h O1-5

rr

H- o

D 

cn

H- D

CO8

1-5

3! Hcn

CO HCO 

CO 

Hdeposits Coastal 

o * SOUND MISSISSIPPI } MEXICO OF GULF 
RECHARGE AREA DISCHARGE AREA

FEET 

+500-

5£4 

LEVEL'

500-

1000-

I500J

ARROWS SHOW GENERAL DIRECTION 

OF WATER MOVEMENT

FEET 

r«500

SEA

'LEVEL

-500

-1000

H500

From Morgan, 1963

Figure 6. Generalized section showing movement of ground water from the 

recharge area to the discharge area in southeastern Louisiana.

Within the study area the aquifer system has been subdivided into as 

many as 13 recognizable aquifer units (Nyman and Fayard, 1978). The division is based on the presence of clayey confining layers interbedded with 

sandy aquifer units within the system's sedimentary sequence. Most of 

these confining layers, however, are only mappable locally and not present 

throughout the study area. Where these confining layers either become 

discontinuous or disappear completely, a coalescing of the aquifer units 

occurs, forming fewer units of thicker proportions. Table 1 shows the 

stratigraphic relation and correlation of aquifer units in the aquifer 

system as used in selected reports on parts of the study area. According 

to these reports, the maximum number of aquifer units is downdip (figs. 3, 

4, and 5) within the geologic sequence in the southernmost part of the 

study area. In the eastern Florida Parishes up to 13 aquifer units 

compose the aquifer system, depending on local interconnection of the 

shallow aquifer and upper Ponchatoula aquifer (Nyman and Fayard, 1978, o. 

7 f pi. 1). These units range in age from Holocene-Pleistocene at the top 

to Miocene at the base. In the Baton Rouge area up to 12 aquifer units 

are recognized (Meyer and Turcan, 1955, pi. 2; and Morgan, 1961, pi. 1) , 

depending on localized hydraulic interconnection of the shallow Quaternary 

aquifers with the deeper Pleistocene "400-foot" and "600-foot" sands. 

Where the shallow aquifers are not interconnected to the underlying 

regional aquifer system they are referred to in this report as the isolated local shallow aquifers.

12
Table 1. Correlation of aquifer units of the Southern Hills aquifer system 

in southeastern Louisiana and southern Mississippi

Southeastern Louisiana

System

Quaternary

Tertiary

Series

Holocene

Pleistocene

Pliocene

Miocene

Aquifer unit

Baton Rouge area,l 

Pointe Coupee 

Parish^

Alluvial 

deposits

Shallow , 

Pleistocene

"400-foot" sand1

"600-foot" sand

"800-foot" sand"1, 000-foot" sand

"1,200-foot" sand

"1,500-foot" sand"1,700-foot" sand

"2, 000-foot" sand

"2,400-foot" sand"2, 800-foot" sand

West 

Feliciana 

Parish^

Quaternary 

alluvium

Quaternary 

upland 

deposits

Zone 1

Zone 2

Zone 3

St. Tammany and . 

Tangipahoa Parishes, 

Washington Parish^

Shallow

Upper 

Ponchatoula

Lower 

Ponchatoula

Big Branch

Kentwood

Abita

Covington

Slidell

Tchefuncta

HammondAmite

Ramsay

Franklinton

Aquifer 

unit

Alluvial 

deposits

Citronelle fi 

Formation

Graham 

Ferry _ 

Formation

Pascagoula 

Formation

Hattiesburg 

Formation

Catahoula 

Sandstone

(Miocene aquifer system 7

Series

Pliocene

Miocene

System

Quaternary

Tertiary

Southern Mississippi

u>

"Storgan, 1961; winner and Forces, 1968; Morgan, 

6Boswell f 1979; and 7Newcome, 1975.

1963; 4Nyman and Fayard, 1978; 5Case, 1979;
Northward within southeastern Louisiana, fewer units are recognized 

within the regional aquifer system. This decrease in aquifer units 

results from the disappearance of many of the locally mappable clay layers 

that exist further south, and because of the pinch out (disappearance) of 

the younger geologic units updip in the geologic sequence toward the 

north. In East and West Feliciana Parishes, for example, only five 

aquifer units were recognized by Morgan (1963, p. 8) . Further north, 

based on reports by Boswell (1979) and Newcome (1975, pi. 1), the aquifer 

system in Mississippi can be divided into two aquifer units in some areas, 

while in other areas the system cannot be divided at all. Figure 5 

(modified from Boswell, 1979, fig. 2) is a generalized geologic section 

that shows the formations that compose the aquifer system and their 

decrease in number toward the north (updip). This north-south geologic 

section through the southern half of Mississippi to the Gulf of Mexico is 

representative of the geologic structure in southern Mississippi and 

southeastern Louisiana. The Miocene, Pliocene, and Pleistocene aquifers 

of southeastern Louisiana are correlative with the aquifer units named in 

southern Mississippi (table 1). In addition to the generalized cross 

section, the geohydrologic sections in figures 3, 4, and 6 show the 

aquifer units recognized at different locations within the study area.

Although the sedimentary sequence that underlies the study area has 

been subdivided in some areas into many aquifer units, the units are 

recognized to collectively operate as a single aquifer system, referred 

to as the Southern Hills aquifer system. (See fig. 6.) Heavily pumped 

aquifer units within the system are known to derive part of their water 

from overlying and underlying aquifer units. The movement of water from 

one unit to another occurs where aquifer units are not separated by confining layers, as leakage through confining layers, or where the influence 

of heavy pumping in one aquifer unit extends horizontally beyond the area 

where an intervening clay layer occurs. This interaquifer connection has 

been recognized in water-resources investigations made within the study 

area.

In the Florida Parishes Nyman and Fayard (1978, p. 62) indicate that 

the rates of water-level decline in the deeper aquifer units reflect 

pumping inside and outside their report area and adjustments in artesian 

pressure are occurring throughout the aquifer system. Specifically they 

state:

Water is moving from the little-used aquifers that have 

relatively high artesian heads to heavily pumped aquifers of 

lower artesian head.

In the Baton Rouge area Torak and Whiteman (1982, p. 4) state:

The "2,000-foot" sand is the most heavily pumped aquifer in the 

system of alternating sands and confining layers in the Baton 

Rouge area. Because of the unequal pumpage distribution among 

aquifers, the "2,000-foot" sand has the most drawdown. This 

results in vertical leakage into this aquifer through the 

confining layer above, from the "1,500-1,700-foot'1 sand, and 

through the confining layer below, from the "2,400-foot" sand.

14
The following excerpt from Morgan (1963, p. 11-13) discusses and 

illustrates aquifer zone interconnection in southeastern Louisiana and 

southwestern Mississippi.

The fresh-water-bearing aquifers in southeastern Louisiana are 

basically a single hydrologic system (fig. 3 [refer to figure 6 

in this report]); however, this system can be divided into 

several hydraulic zones. Movement of water begins in the 

highland or outcrop area where a small part of the total 

precipitation infiltrates the exposed zone. The water moves 

downward and laterally toward the area of lowest head within 

the zone or to adjacent zones. A very small quantity of the 

water moving through hydraulic zone 1 in the recharge area 

passes downward through the underlying relatively impermeable 

clay zones into zone 2, which has a lower head or water level. 

Some water from zone 2 moves downward into zone 3, which in 

turn has a lower head than zone 2. Thus all three zones

receive recharge in the highland area. 

* * *

In the discharge area, as shown on figure 3 [refer to figure 6 

in this report], the water levels are higher in zone 3 than in 

zone 2, higher in zone 2 than in zone 1, and higher in zone 1 

than in the Quaternary aquifers. This is a reversal of their 

relative positions as determined in the recharge area. The 

water in the lower zones of higher head slowly moves upward 

through the overlying clay zones and aquifers and eventually is 

discharged as seepage at the land surface. However, the water 

movement will be downward in discharge areas where withdrawals 

have lowered the naturally higher artesian pressures in the 

deeper zones to a level below those in the shallower zones.

u

In Mississippi, Newcome (1975) found no identifiable or mappable 

means for separating the Pliocene and Miocene Formations (the Graham 

Ferry, Pascagoula, Hattiesburg, and Catahoula Sandstone) into separate 

aquifer units. Newcome therefore included all of these formations as the 

Miocene aquifer system. Newcome states (1975, sheet 1) :

The Miocene sequence in southern Mississippi has been 

subdivided by some workers into the Pascagoula Formation, 

Hattiesburg Formation, ana Catahoula Sandstone from youngest 

to oldest but these divisions cannot be reliably identified or 

traced in the subsurface. Likewise, a 400- to 900-ft-thick 

(120-270 m) unit at the top in the coastal counties has been 

identified as Pliocene in age on the basis of fossil evidence 

and assigned the name Graham Ferry Formation. Again, the unit 

cannot be distinguished from the next lower formation by lithological, geophysical, or hydrological means. Consequently, all 

the material between the Citronelle Formation, a blanket deposit 

of Pliocene age, and the limy Vicksburg Group of Oligocene age 

is herein considered to compose the Miocene aquifer system.

15
The following excerpt from Morgan (1963, p. 11-13) discusses and 

illustrates aquifer zone interconnection in southeastern Louisiana and 

southwestern Mississippi.

The fresh-water-bearing aquifers in southeastern Louisiana are 

basically a single hydrologic system (fig. 3 [refer to figure 6 

in this report]); however, this system can be divided into 

several hydraulic zones. Movement of water begins in the 

highland or outcrop area where a small part of the total 

precipitation infiltrates the exposed zone. The water moves 

downward and laterally toward the area of lowest head within 

the zone or to adjacent zones. A very small quantity of the 

water moving through hydraulic zone 1 in the recharge area 

passes downward through the underlying relatively impermeable 

clay zones into zone 2, which has a lower head or water level. 

Some water from zone 2 moves downward into zone 3 f which in 

turn has a lower head than zone 2. Thus all three zones

receive recharge in the highland area. 

* * *

In the discharge area, as shown on figure 3 [refer to figure 6 

in this report], the water levels are higher in zone 3 than in 

zone 2, higher in zone 2 than in zone 1, and higher in zone 1 

than in the Quaternary aquifers. This is a reversal of their 

relative positions as determined in the recharge area. TTie 

water in the lower zones of higher head slowly moves upward 

through the overlying clay zones and aquifers and eventually is 

discharged as seepage at the land surface. However, the water 

movement will be downward in discharge areas where withdrawals 

have lowered the naturally higher artesian pressures in the 

deeper zones to a level below those in the shallower zones.

In Mississippi, Newcome (1975) found no identifiable or mappable 

means for separating the Pliocene and Miocene Formations (the Graham 

Ferry, Pascagoula, Hattiesburg, and Catahoula Sandstone) into separate 

aquifer units. Newcome therefore included all of these formations as the 

Miocene aquifer system. Newcome states (1975, sheet 1):

The Miocene sequence in southern Mississippi has been 

subdivided by some workers into the Pascagoula Formation, 

Hattiesburg Formation, and Catahoula Sandstone from youngest 

to oldest but these divisions cannot be reliably identified or 

traced in the subsurface. Likewise, a 400- to 900-ft-thick 

(120-270 m) unit at the top in the coastal counties has been 

identified as Pliocene in age on the basis of fossil evidence 

and assigned the name Graham Ferry Formation. Again, the unit 

cannot be distinguished from the next lower formation by lithological, geophysical, or hydrological means. Consequently, all 

the material between the Citronelle Formation, a blanket deposit 

of Pliocene age, and the limy Vicksburg Group of Oligocene age 

is herein considered to compose the Miocene aquifer system.

16
In addition, in many areas the Citronelle aquifer is in direct hydraulic 

contact with the underlying Miocene aquifer units, forming a single 

aquifer. Boswell (1979) states:

The Citronelle Formation is very permeable and readily 

receives and transmits water from precipitation. In Mississippi, water infiltrates to the water table and then either 

moves laterally to valley walls to be discharged by springs and 

seeps or it continues downward into underlying aquifers. Where 

the underlying units are permeable sand (fig. 2 [refer to fig. 

5 in this report]) , a large part of the water may continue 

downward and where underlying clays predominate, most of the 

water moves laterally to discharge points.

Further Boswell states: "Ohe stored water, [referring to water in the 

Citronelle aquifer] also recharges the underlying confined aquifers that 

are hydraulically connected to the basal sand and gravel in the 

Citronelle."

Based on the presently (1983) available information the aquifer 

units that compose the Southern Hills regional aquifer system are 

recognized to function as a single hydrologic system. However, results 

of the Mississippi Embayment West Gulf Coast Regional Aquifer System 

Analysis (scheduled for completion in 1986) may more clearly define 

hydraulic relations between major aquifer units within the aquifer system.

Aquifer Recharge

Aquifer recharge is primarily from direct percolation of precipitation to the water table in areas where the geologic formations that 

compose the Southern Hills aquifer system intersect land surface (recharge 

area outlined in plan, fig. 2, and section, fig. 6). Aquifer recharge 

from stream flow is less significant. Because base flow in local streams 

is sustained by excess water that is discharged from the aquifer (referred 

to as rejected recharge) , aquifer recharge can only occur during periods 

when stream stages are above the water level in the aquifer system. Additionally, much of these stream losses enter the aquifer system temporarily 

as bank storage, and are returned to the stream as stages decline. An 

example of this is described by Morgan (1963, p. 23) concerning the interaction between the Quaternary alluvium and the stage of the Mississippi 

River. Based on aquifer water-level and river-stage records for 1958-61, 

water from the Quaternary alluvial aquifer flows to the river about 80 

percent of the time.

The recharge area of the Southern Hills aquifer system extends

approximately from the southern boundary of the northern tier of parishes

_j.n southeastern Louisiana to the northern limit of the Miocene formations

in southwestern Mississippi (fig. 2) and encompasses about 80 percent of

the study area. Southward from the recharge area the aquifer system is

16
In addition, in many areas the Citronelle aquifer is in direct hydraulic 

contact with the underlying Miocene aquifer units, forming a single 

aquifer. Boswell (1979) states:

The Citronelle Formation is very permeable and readily 

receives and transmits water from precipitation. In Mississippi, water infiltrates to the water table and then either 

moves laterally to valley walls to be discharged by springs and 

seeps or it continues downward into underlying aquifers. Where 

the underlying units are permeable sand (fig. 2 [refer to fig. 

5 in this report]), a large part of the water may continue 

downward and where underlying clays predominate, most of the 

water moves laterally to discharge points.

Further Boswell states: "The stored water, [referring to water in the 

Citronelle aquifer] also recharges the underlying confined aquifers that 

are hydraulically connected to the basal sand and gravel in the 

Citronelle."

Based on the presently (1983) available information the aquifer 

units that compose the Southern Hills regional aquifer system are 

recognized to function as a single hydrologic system. However, results 

of the Mississippi Embayment West Gulf Coast Regional Aquifer System 

Analysis (scheduled for completion in 1986) may more clearly define 

hydraulic relations between major aquifer units within the aquifer system.

Aquifer Recharge

Aquifer recharge is primarily from direct percolation of precipitation to the water table in areas where the geologic formations that 

compose the Southern Hills aquifer system intersect land surface (recharge 

area outlined in plan, fig. 2, and section, fig. 6). Aquifer recharge 

from stream flow is less significant. Because base flow in local streams 

is sustained by excess water that is discharged from the aquifer (referred 

to as rejected recharge), aquifer recharge can only occur during periods 

when stream stages are above the water level in the aquifer system. Additionally, much of these stream losses enter the aquifer system temporarily 

as bank storage, and are returned to the stream as stages decline. An 

example of this is described by Morgan (1963, p. 23) concerning the interaction between the Quaternary alluvium and the stage of the Mississippi 

River. Based on aquifer water-level and river-stage records for 1958-61, 

water from the Quaternary alluvial aquifer flows to the river about 80 

percent of the time.

The recharge area of the Southern Hills aquifer system extends 

approximately from the southern boundary of the northern tier of parishes 

in southeastern Louisiana to the northern limit of the Miocene formations 

in southwestern Mississippi (fig. 2) and encompasses about 80 percent of 

the study area. Southward from the recharge area the aquifer system is

17
Source of contaminants

00

Citronelle Formation Unsaturated zone of percolation

t-.'-'-'.ld water table-'-.-

, !-I-I-£Hr-~-~-~-~-~-~-~-~-7-^~-~-~^^^ Conf i ned a quite r :^^>, 

^-_-_r-_-^n_-Miocene or older deposits _-_-^_-_T-_-_J^-. Confining bed ^r*- . ^ .

Figure 7. The movement of a contaminant from a surface source into the aouifer system.
91°

30C

! MISSISSIPPI 

LOUISIANA

31'

EXPLANATION

.£0 ~ POTENTIOMETRIC CONTOUR-Shows altitude of 

potentiometric surface. Dashed where 

approximately located. Contour interval 10 

and 20 feet. Datum is sea level

30s

30 MILES

0 0

" I T

0 20 30 KILOMETERS

Figure 8. Potentiometric surface of the "600-foot" sand near Baton Rouge, April 1976 , and the Ponchatoula 

aquifer in the eastern Florida Parishes, May 1969 (after Whiteman, 1979; and Nyman and Fayard, 1978; 

respectively).
9 90°

to 

o

,/"^'r

WI^KINSON AMITE | PIKE j L, < j

j | |WALTHALL\ \^ j

______ _LMISSISSIPPI! __ J. __ ^QjllJ

r LOUTSIANA f\"T~f,o ~ / 

k WEST / I 200r-^C±-sirl r1

FELICIANA/ EAST J |8Q V^TAflHINQTON 1 

f y FELICIANA J HEL^A j~-| -tW /

*. ^" ^VMM^BK^^^V '^ J * A ^1^

LAMAH

i

X BA*T(

^*\v X

'{^

< LIVINGSTON

.^

/ PEARL EIVEE 

%

' ^v_f

QO U-* TAMMANY J1

\^-^ \

EXPLANATION

POTENTIOMETRIC CONTOUR-Shows altitude of 

potentiometric surface. Dashed where 

approximately located. Contour interval 10 and 20 feet. Datum is sea level

10

I I

I !

10

04-

0

10 

1

T I

10 20

20 30 MILES 

1 i

I

30 KILOMETERS

3f

30°

Figure 9.--Potentiometric surface of the "1,500-foot" sand near Baton Rouge, 1979, and the Abita and Kentwood 

aquifers in the eastern Florida Parishes, May 1974 (after Whiteman, 1979; and Nyman and Fayard, 1978; 

respectively).
9f 9cr

30°

50

EXPLANATION

POTENTIOMETRIC CONTOUR-Shows altitude of 

potentiometric surface. Contour interval 50 

and 100 feet. Datum is sea level

Direction of ground-water flow

90°

I0 20 

J_____I

30 MILES

i I

so

i i i

10 20 30 KILOMETERS

31'

30C

Figure 10. Potentiometric surface of the "2,000-foot" sand, 1979, conputed by a digital ground-water-flow model

(after Torak and Whiteman, 1982).
WILKINSON AMITE

L MISSISSIPPI

LOUTSIANA

FELICIANAf EAST

FELICIANA

MARION

PIKE

i WALTHALL 1, , v«.

r

LAMAR

"H.T

WASHINGTON I

/ PEAEL RIVEE

*o ( ~r

' >' / vx i ..-i 20 V^

x\ /i i» v i * % r~

' / *£ \ \^ | JTAMM/u&Jtf1 ° Y H

t

HANCOCK!

V

EXPLANATION

POTENTIOMETRIC CONTOUR-Shows altitude of 

potentiometric surface. Dashed where 

approximately located. Contour Interval 

10 feet. Datum is sea level

%

^J-^rr -rr Vr -rr^

,-3^7<^*-

10 20 30 MSLES

0 10 20 30 KILOMETERS

Figure 11. Potentiometric surface of the Hanmond aquifer, May 1974, in southeastern Louisiana

(after flyman and Fayard, 1978).
9f 90C

UJ

30C

FELICIANA EAST

EAST BATON 

ROUGE X

31'

120 

EXPLANATION

POTENTIOMETRIC CONTOUR-Shows altitude of 

potentiometric surface. Dashed where 

approximately located. Contour interval 

10 feet. Datum is sea level

30 C

10 30 MILES

0 0 10 20 30 KILOMETERS

Figure 12. Potentiometric surface of the Amite aquifer, May 1974, in southeastern Louisiana

(after Nyman and Fayard, 1978).
Water within the aquifer system moves very slowly, ranging from a few 

tens of feet per year to several hundreds of feet per year. The rate of 

ground-water movement for each aquifer unit within the system can be estimated using values of hydraulic conductivity, hydraulic gradient, and 

effective porosity of the unit. Values of hydraulic conductivity for the 

aquifer units within the system are shown in table 2. Hydraulic gradients 

can be obtained from available potentiometric maps of the aquifer units 

(figs. 8-12). The effective porosity for each of the aquifer units was 

assumed to be 0.20 (20 percent) of the aquifer volume. Effective porosity 

is the interconnected pore space available for fluid transmission 

expressed as a decimal fraction of the volume of aquifer material. These 

data can be substituted in the following equation to estimate the average 

velocity of the ground water.

365 d/yr K

Vgw =

Ne

Where: VgW = the average velocity of ground-water movement in 

feet per year,

K = the hydraulic conductivity of the aquifer in 

feet per day,

dh = the hydraulic gradient of the aquifer unit along a flow 

dl path (dimensionless) , and

ISJe = the effective porosity of the aquifer unit as a decimal 

fraction (dimensionless).

For example, using data for the "600-foot" sand in the Baton Rouge area 

(table 2, fig. 8) an estimate of the average velocity of ground-water 

movement can be made as follows:

K = 90 ft/d 

dh 7.5 ft

= 0.00142 dl 5,280 ft

N = 0.20 

e

v - 365 d/yr (90 ft/d) (0.00142) _

vgw ~ 0.20 ~ 2JJ tt/yr

24
Table 2. Thickness and hydraulic conductivity of aquifers in southeastern Louisiana and southern Mississippi

[Hydraulic conductivity, K, in feet per day]

Baton Rouge area

Aquifer 

unit

Alluvial 

deposits

Shallow 

Pleistocene

"400-foot" 

sand

"600- foot 

sand

"800-foot" 

sand

"1,000-foot" 

sand

"1,200-foot 11 

sand

11 1,500-foot 11 

sand

"1, 700-foot" 

sand

"2, 000-foot" 

sand

"2, 400-foot" 

sand

"2, 800-foot" 

sand

Hydraulic conductivity

230

5084

36

75

140

32

170

79

Unit 

thickness 

(feet)

250-600200-400

25-200

25-200

80-150

50- 8U

100-200100-300

20-240

150-300

80-259

190-350

East and West ~ 

Feliciana Parishes

Aquifer 

unit

Quaternary 

alluvium

Quaternary 

upland 

deposits

Zone 1

Zone 2Zone 3

Hydraulic conductivity

200

70

40, sand 

unit 1

115, sand 

unit 3

115200

Unit 

thickness 

(feet)

0-300

0-300

485-670 

(combined 

units)

410-660 

(combined 

units

85-400 

(combined 

units)

St. Tammany and 3 

Tangipahoa Parishes

Aquifer 

unit

Shallow

Upper 

PonchatoulaLower Ponchatoula

Big BranchKentwoodAbita

Covington

Slidell

Tchefuncta

HammondAmite

Ramsay

Franklinton

Hydraulic conduct ivity

70-140

180

35- 6570

135

120

220

190

65-13585-200

150210

290

Unit 

thickness 

(feet)

100-400

200-300

100-200

50-150

400-500

50-100

100-200

100-200100-150

100-200

100-150100-250100-250

Southern Mississippi

Aquifer 

unit

Citronelle 

Formation

Graham 

Ferry 

Formation

Pascagoula 

Formation

Hattiesburg 

Formation

Catahoula 

Sandstone

Hydraulic conductivity

12 5-200^

956/

Unit 

thickness 

(feet)

0- 1000- 200

0-1,000

0- 400

0- 900

KJ

Morgan, 1961; 2Morgan, 1963; 3Nyman and Fayard, 1978; 4Shows, 1970; 5Boswell, 1979; 6Newcome, 1975.
The calculated value of ground-water velocity in turn can be used to 

estimate the minimum residence time2 of water in the aquifer unit as it 

moves from the recharge area to H point of discharge. Points of discharge 

are where water (1) is pumped from a well open to the aquifer unit, (2) 

moves through a confining layer to an overlying or underlying aquifer unit 

that has a lower potentiometrie level, or (3) discharges to land surface 

or to streams, where the potent iome trie level of the aquifer unit is above 

land surface or above the water level in streams, either where the aquifer 

is unconfined or as upward leakage through a confining layer.

Water Quality

Table 3 shows dissolved-solids concentrations and water types for the 

aquifer units within the system in southeastern Louisiana and southwestern 

Mississippi. Ground water is of good quality and almost exclusively a 

soft, sodium bicarbonate type. In southeastern Louisiana, the dissolvedsolids concentration in water from the Southern Hills aquifer system 

averages about 210 mg/L, ranging from 27 mg/L in the Quaternary upland 

deposits of the Feliciana parishes (Morgan, 1963, table 10) to 531 mg/L 

in the alluvial deposit in the Baton Rouge area (Morgan, 1961, table 1) . 

In southern Mississippi, dissolved-solids concentrations were reported by 

Boswell (1979) and Newcome (1975) . In southwestern Mississippi the 

Citronelle aquifer had an average dissolved-solids concentration of 51 

mg/L in water from 19 wells within the study area that ranged from 22 to 

135 mg/L. In southern Mississippi the Miocene aquifer units had a median 

dissolved-solids concentration of 170 mg/L in water from 609 wells located 

within and outside the study area that ranged from 13 to 1,390 mg/L. 3

ALTERNATE SOURCE OF WATER SUPPLY

In southeastern Louisiana several streams (fig. 13) are available as 

alternate sources of freshwater for public and domestic supply. Table 4 

shows discharge and dissolved-solids concentrations for these streams.

2 This method of estimating the minimum residence time should not be

used as a strict measure of the time of travel of water within the system, 

because it assumes a straight path of flow between two points and a homogeneous and isotropic aquifer of uniform thickness. In actuality, water 

may travel in a more tortuous path between two points, varying in velocity 

in response to changes in aquifer properties and thickness. The equation 

should therefore be limited to making gross approximations of the minimum 

residence time of water between two points.

 ^Data used from Newcome (1975) indicated a maximum dissolved-solids 

concentration of 1,390 mg/L in the Miocene aquifer units in Jefferson 

County, Miss. Although this value is in excess of the 1,000 mg/L 

dissolved-solids concentration indicated in that report as the limit of 

freshwater, the values were reported as a median and range and therefore 

retained in this report.

26
Table 3.--Water types and dissolved-solids concentrations in aquifers in southeastern Louisiana and southwestern Mississippi

[Dissolved-solids concentration in milligram per liter]

Baton Rouge area

Aquifer 

unit

Alluvial 

deposits

Shallow 

Pleistocene

11 4 00- foot" 

sand

11 600- foot" 

sand

"800- foot" 

sand

"1,000- foot" 

sand

"1,200- foot", 

sand

11 1,500-foot11 

sand

"1,700-foot11 

sand

"2, 000-foot" 

sand

"2, 400-foot" 

sand

"2, 800-foot" 

sand

Water 

type

Hard 

calcium bicarbonate

Hard 

calcium 

bicarbonate

All 

soft, sodiumbicarbonate 

type

Dissolved 

solids

Mean: 387 

Range: 172-719 

(samples: 8)

Mean: 415 

Range: 277-508 

(samples: 5)

Mean: 245 

Range: 184-403 

(samples: 4)

Mean: 324 

Range: 185-593 

(samples: 6)

Mean: 201 

Range: 182-213 

(samples: 3)

248 

(sample: 1)

Mean: 218 

Range: 181-426 

(samples: 8)

Mean: 260 

Range: 193-666 

(samples: 9)

Mean: 206 

Range: 197-235 

(samples: 5)

Mean: 285 

Range: 178-635 

(samples: 6)

Mean: 260 

Range: 188-322 

(samples: 7)

Mean: 364 

Range: 192-538 

(samples: 8)

:Morgan, 1961; 

^Morgan, 1963; TNyman and Fayard, 1978; IBoswell, 1979; Tfewcome, 1975.

East and West Feliciana Parishes

Aquifer 

unit

Quaternary 

alluvium

Quaternary 

upland 

deposits

Zone 1

Zone 2

Zone 3

Water 

type

Hard 

calcium bicarbonate

All 

soft, sodiumbicarbonate type

Dissolved 

solids

Mean: 441 

Range: 152-515 

(samples: 6)

Mean: 79 

Range: 27-163 

(samples: 14)

Mean: 117 

Range: 40-195 

(samples: 33)

Mean: 192 

Range: 122-308 

(samples: 29)

Mean: 264 

Range: 175-531 

(samples: 12)

St. Tanmany and Tangipahoa Parishes

Aquifer 

unit

Shallow

Upper 

Ponchatoula

Lower 

Ponchatoula

Big Branch

KentwoodAbita

Covington

SlidellTbhefunctaHammond

Amite

Ramsay

Franklinton

Water 

type

Mixed type in 

northern areas; 

predominantly 

sodium bicarbonate in 

southern areas

All soft sodiumbicarbonate 

type

Dissolved 

solids

Mean: 108 

Range: 29-255 

(samples: 10)

Mean: 196 

Range: 188-206 

(samples: 3)

Mean: 220 

Range: 144-354 

(samples: 3)

Mean: 244 

Range: 138-401 

(samples: 3)

Mean: 93 

Range: 62-129 

(samples: 4)

Mean: 257 

Range: 171-383 

(samples: 5)

Mean: 187 

Range: 154-223 

(samples: 6)

Mean: 219 

Rarae: 175-262 

(samples: 2)

Mean: 168 

Range: 138-187 

(samples: 4)

Mean: 169 

Range: 139-209 

(samples: 5)

Mean: 206 

Rarae: 160-294 

(samples: 7)

Mean: 165 

Range: 151-184 

(samples: 3)

Mean: 251 

Rarae: 236-279 

(samples: 3)

Southern Mississippi

Aquifer 

unit

Citronelle 

Formation

Graham 

Ferry Formation

Pascagoula 

Formation

Hattiesburg 

Formation

Catahoula

Sandstone

Water 

type

Almost 

exclusively 

soft, sodiumbicarbonate 

type

Dissolved 

solids

Mean: 51^ 

Range: 22-135 

(samples: 19)

Median: 170^ 

Range: 13-1390 

(samples: 609)

to
31

la

EXPLANATION 

Surface-water discharge station 

(some with water-quality data)

Surface-water water-quality station

1. Mississippi River at Tarbert Landing, Miss,

la. Mississippi River near St. Francisville, La.

2. Atchafalaya River at Simmesport, La.

2a. Atchafalaya River at Melville. La.

3. Pearl River near Bogalusa, La.

4. Amite River near Denham Springs, La.

4a. Amite River at 4-H Camp, near 

	Denham Springs, La.

5. Bogue Chitto near Bush, La.

6. Tangipahoa River at Robert, La.

7. Tickfaw River at Holden, La.

8. Natalbany River at Baptist, La.

	(See table 4.)

GKEKNE PERRY

B9'-

90"

! !

(0

20 

 r-l 

30 MILES

Figure 13.--Major streams in southeastern Louisiana.

GEOEGE

JACKSON

<

s 

<

CD

<

28
Table 4. Discharge data and dissolved-solids concentrations for streams that are

possible alternative sources of freshwater in southeastern Louisiana

Site 

No.

(fig. 

13)

1 la 

2 2a 3

jo 4

5 

67 8

Stream and 

data -collect ion 

site

Mississippi River: 

At Tarbert Landing, Miss 

Near St. Franc isville, LaAtchafalaya River:

At Simmesport, La 

At Melville, La 

Pearl River near Bogalusa, 

La.

Amite River: 

Near Denham Springs, La At 4-H Camp, near Denham 

Springs, La.

Bogue Chito near Bush, La 

Tangipahoa River at Robert, 

La.

Tickfaw River at Holden, LaNatalbany River at Baptist, 

La.

m° £* £

Average Minimum Maximum

537,000 160,000 1,500,000

256,800 22,000 781,000

9,671 1,020 129,000 

1,980 271 110,000

1,927 366 57,400 

1,134 245 50,500

368 65 19,000 

115 1.8 9,550

Period of Mini- Maxirecord mum mum

.1972-80

150 321

1972-80 

120 366

1938-81 13 142

1938-81 24 131

£-i~ J_ wr-l1937-81 11 347 

1938-81 25 58

1940-81 

1943-81

Period of 

record1954-81

1979-81 1962-81

1974-81 

1979-81

Cubic foot per second equals 0.646 million gallons per day.
Although these streams are local sources of abundant freshwater, they 

have not been considered as practicable alternative sources of water for 

public and domestic supply. The reasons cited in the petition to EPA are 

the increased cost of water to the users because of (1) the additional 

water treatment, and (2) the extensive distribution system necessary to 

deliver the water, especially to areas remotely located from a source 

stream. Ground water, on the other hand, is available from wells located 

in the vicinity of the users and can be delivered at nearly half the 

cost of river water when considering water treatment alone. For example, 

in Baton Rouge, where ground water is presently used (1983), water costs 

about 12 cents per 1,000 gal (Ike Peairs, Baton Rouge Water Works, oral 

commun., 1982). In New Orleans, because of the water treatment needed 

prior to the delivery of Mississippi River water into the public-supply 

system, water costs about 22 cents per 1,000 gal (J. Sullivan, New Orleans 

Sewerage and Water Board, oral commun., 1982). In addition to the 

increased cost of drinking water because of required treatment, an 

accidental spill of hazardous chemicals in the Mississippi River could 

temporarily disrupt the New Orleans water supply.

POPULATION AND WATER USE

In 1980 about one million persons resided in the 10 parishes of 

southeastern Louisiana and 14 counties of southwestern Mississippi, where 

the Southern Hills aquifer system is the primary source of water for 

public and domestic supply. The average water use for these categories 

in the area was about 146 Mgal/d during 1980. Based on projected population (K. McGinnis, Louisiana State Planning Office, oral commun., 1982) 

and water use (Urban System Associates, Inc, 1982) , by the year 2000 the 

population of this area will reach about 1.5 million persons, and publicand domestic-supply water use will be about 220 Mgal/d.

Southeastern Louisiana

Table 5 shows the average daily use of water for public supply and 

domestic purposes and population data for each of the 10 parishes within 

the study area. The table shows actual data for the years 1970 and 1980, 

and projections for the years 1990 anci 2000.

In 1970 the population of the CAGWCC district and the Florida 

Parishes totaled about 571,000 persons, and the average public supply and 

domestic use was 91 Mgal/d. By 1980, the population increased to about 

744,000 persons and public supply and domestic use increased to about 121 

Mgal/d. According to growth projections, from 1980 to the year 2000 the 

population will increase an additional 51 percent, reaching 1,123,000 

persons for the 10-parish area. Water use for public and domestic supply 

is expected to increase 57 percent during this 20-year period, reaching 

about 190 Mgal/d.

30
Table 5.--Population and water use in southeastern Louisiana, 1970 and 1980, and projected to 1990 and 2000

u>

[Data in millions of gallons per day]

1970

Parish

East Baton Rouge East Feliciana 

Livingston 

Pointe Coupee 

St. Helena 

St. Tammany 

Tangipahoa 

Washington West Baton Rouge 

West Feliciana 

Total 

Population

285,167 

17,657 

36,511 

22,002 

9,937 

63,585 

65,875 

41,987 16,864 

11,376

570,961

Public 

and 

domestic 

supply

32.75 

.84 

5.12 

1.02 

.37 

25.98 

12.75 

8.73 2.46 

.55

90.57

1980

Population

366,164 

19,015 

58,655 

24,045 

9,827 

110,554 

80,698 44,207 

19,086 

12,186

744,437

Public 

and 

domestic 

supply

55.63 

1.47 

5.74 1.56 

.73 

23.50 

12.84 

12.13 

5.53 

1.91

121.04

1990 

(Projected)

Population1

444,076 

21,807 83,928 26,740 10,087 

162,856 

96,134 47,062 

22,241 13,099

928,030

Public 

and 

domestic 

supply^

61.23 

1.66 

10.04 

1.79 

.96 

39.32 

15.51 

17.04 

6.19 

2.09

155.83

2000 

(Projected)

Population1

.^ 14,822 

25,504 

113,844 

29,306 

10,265 

227,777 

112,368 

48,772 

24,959 

15,384

1,123,001

Public 

and 

domestic 

supply^

70.38 

1.83 

14.64 

1.99 

1.16 

50.74 

18.62 

21.54 

6.80 

2.25

189.95

Louisiana State Planning Office. 

TJrban Systems Associates, Inc.
Southwestern Mississippi

Table 6 shows the average daily use of water and population data for 

the 14 Mississippi counties within the study area where the aquifer system 

is the primary source of water for public and domestic supply. The 

population and water-use data used in this report was limited to county 

totals for the 14 counties directly north of southeastern Louisiana. In 

the northern three counties of the study area (Hinds, Rankin, and Warren), 

ground-water withdrawals (Callahan, 1983) are primarily from the Oligocene 

and Eocene aquifers underlying the Catahoula Sandstone, the basal unit of 

the Miocene aquifer system in Mississippi or from the Quaternary alluvium 

(Warren Co.). Between the years 1970 and 1980 the total population of the 

14 counties increased from about 252,000 to about 273,000 persons, about 

an 8-percent growth for the period. In 1980 water use for public and 

domestic supply averaged about 25 Mgal/d.

Table 6. Population and water use in southwestern Mississippi 

[Data in million of gallons per day]

County

iTLJCUllO

Copiah - 

Franklin -

Jefferson Davis 

Lawrence - 

Lincoln 

Marion -

Pike -

Simpson - 

Walthall -

TV .£. JL IX .Li lt^7\M/ 1 1

1970

Population

 37 90-5

J 1 f £. .2J

^ -> "if -> 13,763

10,086 

94 t."i , 7/Q/ "4 .7

8,011

9

*5Q c.

_ 19 q"3£ J_£, -/OO

11,137

O£ 1 QQ

__ 99 071 £.£. ,O / JL

31,756

__ T Q Q/1'7

 jLy ,y*± /

12,500

U OQQ

Population

38,035 

13,369 

12,279 

26,503 

8,208 

9,181 

13,846 

12,518 

30,174 

25,708 

36,173 

23,441 

13,761 

10,021

1980

Public and 

domestic supply

4.30 

1.02 

1.22 

2.96 

.68 

.73 

1.04 

.84 

2.30 

1.92 

4.63 

2.12 

1.00 

.56

Total 251,641 273,217 25.32

Data projections for water use and population were not available for 

southwestern Mississippi. For the purposes of this report, projections 

for southwestern Mississippi were made by the author based on growth 

trends projected for southeastern Louisiana. The Mississippi growth 

projections were determined based on the ratio of population growth for 

southwestern Mississippi versus southeastern Louisiana between 1970 and 

1980 (1:3.5). This ratio was then applied to the percentage growth that

32
was projected for southeastern Louisiana to obtain the estimate of percent 

growth for southwestern Mississippi. Based on this growth assumption, the 

population total for the 14 counties of Mississippi will increase 15 

percent from the 1980 level of 273,000 to about 314,000 persons by the 

year 2000. Correspondingly, water use for public and domestic supply will 

increase 20 percent from the 1980 level of 25 Mgal/d to about 30 Mgal/d by 

the year 2000.

SUMMARY AND CONCLUSIONS

The Southern Hills regional aquifer system, which ranges in age from 

Pleistocene or Pliocene at the top to Miocene at the base, is the primary 

source of water for public and domestic supplies in the Capital Area 

Ground Water Conservation Commission (CAGWX) five-parish district in the 

Baton Rouge area and in the Florida Parishes of southeastern Louisiana. 

A secondary source of ground water that is used for rural self-supplied 

systems is from local shallow aquifers that occur within the Quaternary 

alluvial deposits and the shallow Pleistocene sands overlying the regional 

aquifer system. The CAQWCC has petitioned the U.S. Environmental Protection Agency to designate the Southern Hills regional aquifer system as a 

sole or principal source of drinking water under Section 1424(e) of the 

Safe Drinking Water Act, Public Law 93-523. Included in the area covered 

by the petition is the recharge area that is the source of water for the 

aquifer system. Inclusion of the recharge area was emphasized because 

this is the most vulnerable area for the introduction of contaminants into 

the aquifer. The recharge area extends northward beyond southeastern 

Louisiana into southwestern Mississippi. In about 85 percent of the 

Mississippi part of the study area, the aquifer system is the primary 

source of water for public and domestic supply.

The aquifer system is comprised of a gulfward dipping and thickening 

sedimentary sequence that extends from the northern limit of the Miocene 

outcrop in southwestern Mississippi southward approximately to the Baton 

Rouge fault in the Baton Rouge area and to the southern part of the 

Florida Parishes of southeastern Louisiana. In the southernmost part of 

the area, the aquifer system achieves a thickness of more than 2,500 ft 

to the base of the freshwater within this sedimentary sequence. (Freshwater is defined as having a chloride concentration of 250 mg/L or less.) 

In southeastern Louisiana, the system has been divided into as many as 13 

aquifer units, based on the presence of locally mappable clay layers. 

These aquifer units are recognized to decrease in number northward where 

many of the clay layers either disappear completely or are no longer 

mappable, or where younger formations in the geologic sequence pinch out 

in the updip section. Although the system has been subdivided into many 

aquifer units, they are recognized to operate as a single hydraulic 

system. The relations between major aquifer units may be more clearly 

defined by the Mississippi Embayment West Gulf Coast Regional Aquifer 

System Analysis that is scheduled for completion in 1986.

33
Water in the aquifer system is almost exclusively a soft, sodium 

bicarbonate type and low in dissolved solids. In southeastern Louisiana 

dissolveci-solids concentrations average about 210 mg/L. In southwestern 

Mississippi the Citronelle aquifer has an average dissolved-solids concentration of 51 mg/L. In southern Mississippi, the Miocene aquifer unit has 

a median dissolved-solids concentration of 170 mg/L.

As an alternative to the use of ground water for public and domestic 

supply, several streams, the largest of which are the Mississippi and 

Pearl Rivers, are local sources of abundant freshwater. Although these 

v ters are of relatively good quality, ranging from 11 to 366 mg/L in 

dissolved-solids concentration, they have not been considered by local 

officials as a practicable alternative for public and domestic supply. 

The major reasons for nonacceptance are the additional cost to the user 

because of water treatment and the extensive distribution system necessary 

to deliver water to users remotely located from the streams. Ground 

water, on the other hand, generally requires less treatment and wells can 

be located close to users. Using surface water would nearly double the 

cost to users, based on the required water treatment alone.

In the 10 parishes of southeastern Louisiana where the Southern Hills 

aquifer system is the primary source of water for public and domestic 

supply, water use for these categories for 1980 totaled about 121 Mgal/d, 

serving about 744,000 persons. In the 14 counties of southwestern 

Mississippi, where the aquifer system is also the primary source of water 

for public and domestic supply, water use for these categories in 1980 

totaled about 25 Mgal/d serving about 273,000 persons. Based on growth 

in southeastern Louisiana and southwestern Mississippi from 1970 to 1980 

and growth projections for southeastern Louisiana, water use for public 

and domestic supply for the 10 southeastern Louisiana parishes and 14 

Mississippi counties will total about 220 Mgal/d serving about 1.5 million 

persons by the year 2000.

34
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Rollo, J. R., 1960, Ground water in Louisiana: Louisiana Department of 

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36
Mississippi

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37
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38