GEOLOGICAL SURVEY CIRCULAR 374

WATER RESOURCES OF THE 

NEW ORLEANS AREA

LOUISIANA
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

GEOLOGICAL SURVEY CIRCULAR 374

WATER RESOURCES OF THE NEW ORLEANS AREA, LOUISIANA

By M. L. Eddards, L. R. Kister, and Glenn Scarcia

Washington, D. C., 1956

Free on application to the Geological Survey, Washington 25, D. C.
PREFACE

This report is one of a series concerning water resources and present water use in selected industrial 

areas of national importance, which has been prepared 

at the request of and in consultation with the Water and 

Sewerage Industry and Utilities Division of the Business 

and Defense Administration of the U. S. Department of 

Commerce. This series is designed to serve the dual 

purpose of providing information for national defense 

planning and at the same time render a service to 

business and industry, as well as to municipalities, in 

their development of water resources for present and 

future use. This report was prepared with the assistance of the Water Utilization Section, Technical Coordination Branch. It was prepared under the direct 

supervision of F. N. Hansen, district engineer (Surface Water Branch); Rex R. Meyer, district geologist 

(Ground Water Branch); and Burdge Ireland, district 

chemist (Quality of Water Branch). E. L. Hendricks 

(Technical Coordination Branch) assisted in planning 

and writing it.

Many of the data summarized herein have been collected over a period of many years by the U. S. Geological Survey in cooperation with the Department of 

Conservation, Department of Public Works, Department of Highways, and Louisiana University, and 

Agricultural and Medical College. Data on the Mississippi River at New Orleans and chloride content of 

the water of Lake Pontchartrain were furnished by the 

Corps of Engineers, U. S. Army. Chemical-quality 

data on the Mississippi River at New Orleans were 

furnished by the Sewerage and Water Board of New 

Orleans. Bacterial analyses were furnished by the 

City Board of Health.

Additional information pertaining to the use of water 

was obtained from industries in the area and from the 

Sewerage and Water Board of New Orleans.

II
CONTENTS

Page

Abstract............................ .......................... 1

Introduction.................................................. 1

Purpose and scope of investigation.. .............. 1

Description of area................ .................... 2

Topography and drainage.... ................. .... 2

Climate....................... .......................... 3

Natural resources......... ...................... ... 3

Population........... .. ............................... 3

Transportation.................................. ..... 3

Industrial development....... ...................... 5

Definition of terms........................................ 5

Principles of occurrence of water.. .................. 5

Sources of water.............. .......................... 5

Significance of the quality of water.. .............. 7

Surface water..................... ..... .................... 8

Records available....................................... 8

Mississippi River....................................... 8

Floods and flood protection..... .................. 8

Discharge........................ ...................... 12

Port facilities and navigation..................... 14

Quality of the water....... .......................... 16

Temperature................ .......................... 16

Sediment................................................ 18

Pollution and its control..... ...................... 18

Lake Pontchartrain drainage basin.. .............. 19

Lake Pontchartrain.... ............................ 19

Tributaries to Lake Pontchartrain.............. 19

Page 

Surface water Continued

Pearl River and lakes .................................. 25

Pearl River............................................ 25

Lakes.................................................... 25

Ground water................................................ 25

Geology.......................... .......................... 25

Water-bearing units.................................... 26

General features. 

"200-foot" sand.. 

"400-foot" sand.., 

"700-foot" sand..,

.............................. 26

............................... 26

............................... 28

............................... 32

"1,200-foot" sand.......... .......................... 34

Depth to salt water..........

Public water-supply system. 

New Orleans..................

...................... 36

....................:. 36

...................... 36

Other public water supplies.......................... 37

Use of water................................................. 37

Public supplies................ .......................... 38

Surface water............... .......................... 38

Ground water.......................................... 38

Potential water resources............................... 39

Surface water.................. ................... ..... 39

Ground water............................................. 40

Water laws.................................................... 40

Federal law................................................ 40

Louisiana law.................. .......................... 40

Selected references....................................... 41

ILLUSTRATIONS

Page 

Plate 1. Map and geologic sections showing fresh-water salt-water interface in major

aquifers underlying the New Orleans area........................................................ Inside back cover

Figure 1. Map of New Orleans area showing location of streams, lakes, and wells sampled for chemical

analysis .................................................................................................................. 2

2. Climatological data, New Orleans, La................................................... .............................. 4

3. Map of New Orleans area and vicinity showing river systems, lakes, and gaging stations.............. 6

4. Maximum annual stages of the Mississippi River at New Orleans (Carrollton gage), 1872 1953....... 10

5. Distribution graph showing frequency of annual floods by months, Mississippi River at New

Orleans, 1872-1953..... ...................................................................;.............................. 11

6. Water-surface profiles for selected floods oh the Mississippi River, New Orleans and vicinity...... 12

7. Stage hydrographs of the Mississippi River near New Orleans (Huey P. Long Bridge)................... 13

8. Maximum, minimum, and average mean monthly discharge of the Mississippi River at Baton

Rouge, 1931-53.............................. ................. ............................................................. 14

9. Relationship between streamflow and chemical composition of Mississippi River water at

Carrollton plant, New Orleans, 1953............................................................................ ..... 15

10. Monthly average chloride content of Mississippi River water at Algiers and Carrollton treatment

plants, New Orleans, 1953............................................................................................... 16

11. Mean monthly air and Mississippi River water temperatures at New Orleans, 1921 50.................. 16

12. Cumulative frequency graph of water temperature of Mississippi River at New Orleans................. 18

13. Sediment concentration of the Mississippi River at Baton Rouge, water year 1953........................ 18

14. Cumulative monthly suspended sediment load of Mississippi River at Baton Rouge, water

year 1953......................................................................... ............................................ 19

15. Cumulative frequency graph of sediment concentration, Mississippi River at Baton Rouge, water

year 1953...................................................................................................................... 20

III
 CONTENTS

Page 

Figure 16. Duration curve of daily flows, Amite River near Denham Springs, water years, 1939 54............... 21

17. Maximum period of deficient discharge, Amite River near Denham Springs, water years 1939 52... 22

18. Mean daily discharge of the Amite River near Denham Springs, 1946......................................... 22

19. Graph showing chemical characteristics of water from wells in the New Orleans area.................. 27

20. Graph showing the general decline in artesian head, in feet, with reference to land-surface datum

in the principal aquifers in the New Orleans area................................................................. 31

21. Graph showing the relationship of pumping to water levels in wells screened in the "400-foot" sand

in northern St. Charles Parish......................................................................................... 32

22. Graph showing water-level fluctuations in wells screened in the "700-foot" sand in New Orleans

area............................................................................................................................ 33

23. Graph showing the relationship of pumping to water levels screened in the "700-foot" sand in

northern St. Charles Parish............................................................................................. 34

24. Isochloride map of the "700-foot" sand in New Orleans............................................................. 35

25. Average daily pumpage of treated Mississippi River water from the Carrollton treatment plant at

New Orleans, 1909-54..................................................................................................... 39

TABLES

Page 

Table 1. Location and duration of selected gaging-station records in the vicinity of New Orleans................ 9

2. Concentrations of several constituents in the raw Mississippi River water at the Carrollton

treatment plant. New Orleans, 1953................................................................................. 17

3. Summary of streamflow data for streams tributary to Lake Pontchartrain................................. 20

4. Mineral analyses and related physical measurements of surface water in the Lake Pontchartrain

drainage basin and the Pearl River at Bogalusa.................................................................. 23

5. Approximate maximum, minimum, and average chloride concentration in water from Lake

Pontchartrain, Little Woods........................................................................................... 24

6. Summary of ground-water pumpage, in million gallons a day, from each sand in the New Orleans

industrial area, 1953... ..................................................................................i.............. 28

7. Chemical analyses and related physical measurements of ground water in the New Orleans

area........................................................................................................................... 29

8. Maximum, minimum, and average concentrations of several constituents in the raw and finished

water at Carrollton treatment plant.................................................................................. 37

9. Mineral constituents and related physical measurements of the raw and finished water of the

public supplies in the New Orleans area............................................................................ 38
WATER RESOURCES OF THE NEW ORLEANS AREA, LOUISIANA

By M. L. Eddards, L. R Kister, and Glenn Scarcia

ABSTRACT

Industry, commerce, and public utilities in 1954 

withdrew about 1,500 mgd from surface- and groundwater sources in the New Orleans area. Most of the 

withdrawal was made from the Mississippi River. 

However, some withdrawal of surface water was made 

from Lake Pontchartrain. A large part of the withdrawal from both ground- and surface-water sources 

is available for reuse. Ground-water withdrawal 

amounts to about 100 mgd and is primarily for industrial and commercial uses. The average flow of the 

Mississippi River for the 23-year period, 1931 54, 

amounted to 309,000 mgd, and the approximate average 

flow of all the tributaries to Lake Pontchartrain is 

about 4,000 mgd. The flow of the Pearl River, which 

adjoins the tributary drainage area of Lake Pontchartrain, averages about 8,000 mgd. Total withdrawal 

of ground and surface waters amounts to less than 3 

percent of the recorded minimum flow of the Mississippi River or less than 1 percent of the average flow. 

Although large quantities of water are always available in the Mississippi River the quality of the water 

is not suitable for all uses.

Streams from the north that drain into Lake$ 

Maurepas and Pontchartrain, and the aquifers in that 

area, offer one of the best sources of fresh water in 

the State. Industry, if located on the northern shores 

of Lake Maurepas or Lake Pontchartrain near the 

mouths of these tributaries, would be assured of an 

ample supply of either ground or surface water of 

excellent quality. All the tributaries north of Lake 

Pontchartrain have dry-weather flows which are dependable. The Pearl River above Bogalusa also is a 

good source of fresh water of excellent quality. At 

present it serves to dilute the tidal flow of salt water 

into Lake Pontchartrain through the Rigolets, the 

principal outlet of the lake.

In the area north of Lake Pontchartrain, wells 60 

to 2,000 feet deep yield fresh water. There are no 

known wells tapping sands below 2,000 feet. However, 

electrical logs of oil-test wells show that fresh water 

is available to a maximum depth of 3,000 feet. In the 

area south of Lake Pontchartrain, there is no withdrawal of ground water for public water supplies because of the saline content of the water.

Three principal water-bearing sands, the "200- 

foot, " "400-foot, " and "700-foot" sands, are tapped 

in the New Orleans area south of Lake Pontchartrain 

for industrial and commercial use. In this area all 

deeper sands yield salt water.

In some areas the "200-foot" sand contains saline 

water of the sodium chloride type. Consequently, this 

sand is not developed extensively. Water from the 

"200-foot" sand is relatively fresh north of the Mississippi River and becomes increasingly saline to the 

south and west.

The "400-foot" sand is the second most highly developed aquifer in the New Orleans industrial district. 

The aquifer appears to be very prolific, but its full 

capabilities have not yet been determined. This aquifer 

yields a highly mineralized sodium chloride water in 

some areas; however, elsewhere it is a source of 

large quantities of fresh water.

The "700-foot" sand is the most continuous freshwater bearing sand in the area and is the principal 

source of fresh ground water in the New Orleans 

industrial district. Most of the wells tapping this 

aquifer yield soft water of the bicarbonate type. In 

the southern and western parts of the industrial district 

the water in the "700-foot" sand is too mineralized to 

be suitable, for human consumption.

INTRODUCTION 

Purpose and Scope of Investigation

The purpose of this report is to summarize available 

data on the water resources of the greater New Orleans 

area and to evaluate these resources as to their present 

and potential use insofar as possible. Water use has 

been increasing constantly throughout the area owing to 

the rapid increase in industrial and municipal requirements, and this increase should be met by the most 

satisfactory and economical method possible.

This report does not solve all questions and problems 

which relate to water supplies in any specific area, as 

there are too many unknown factors which will call for 

future detailed investigations. However, it contains 

data useful to defense or nondefense industries and 

municipalities for the preliminary planning of new 

works or the expansion of existing facilities. It describes the quantity, quality, and physical characteristics of the surface waters in the area, and it outlines 

the water-bearing sands and describes their hydrologic 

properties.

Although large quantities of water are available from 

the Mississippi River, other sources of water supplies 

should be considered for supplementary development 

because the quality of the water is poor at times.
WATER RESOURCES OF THE NEW ORLEANS AREA

During periods of extreme low flow, salt water moves 

as a wedge along the bottom of the river and some 

mixing within the channel takes place. Infrequently, 

at low water, salinities at the surface exceed standards set for potable water and exceed desirable limits 

set for other uses. Continuous pumping in the area 

has caused ground-water levels to decline; however, 

not enough information has been gathered to determine 

the effects of present and future withdrawal. It is 

hoped that a more detailed study of the area will be 

made in the future to determine the availability of 

large quantities of ground water for specific uses.

Description of Area 

Topography and Drainage

The New Orleans area is in the Gulf Coastal Plain 

and lies in two sections of the Coastal Plain province 

the Mississippi Alluvial Plain to the south and the East 

Gulf Coastal Plain to the north (Fenneman, 1938, 

p. 65 87). As described in this report, the New 

Orleans area covers about 3,100 square miles, of 

which about 840 square miles is in bodies of water. 

The area includes all of St. Charles and Orleans

EXPLANATION

Sc-57

________.Si._I I 

%\ I 1

Figure 1. Map of the New Orleans area showing location of streams, lakes^and wells sampled for chemical 

analysis. Insert map shows location of New Orleans area.
INTRODUCTION

Parishes and parts of St. Bernard, Plaquemines, 

Jefferson, St. John the Baptist, Tangipahoa, and St. 

Tammany Parishes (fig. 1).

Topographically, the East Gulf Coastal Plain to the 

north of Lake Pontchartrain is of low relief, the altitude ranges from 5 to 45 feet. The land surface slopes 

toward the south and usually is covered by secondand third-growth pine trees. The principal streams 

flow southward into Lake Pontchartrain, draining an 

area of about 3,650 square miles. Runoff into Lake 

Pontchartrain from all directions is from an area of 

about 4,200 square miles. Although the principal 

streams draining into Lake Pontchartrain have an 

abundant supply of water of good quality, very little 

water is withdrawn at present from the streams for 

industrial use.

South of Lake Pontchartrain the Mississippi Alluvial 

Plain ranges in altitude from 5 feet below to about 10 

feet above sea level; the crest of the artificial levees 

have a maximum altitude of about 25 feet. As described by Fisk (1944, p. 35), the Metairie Ridge 

extends from the Mississippi River near Kenner, La. , 

eastward to New Orleans and is about 5 10 feet above 

sea level. This ridge marks the course of a former 

Mississippi River distributary which flowed eastward 

to the Rigolets.

The Mississippi Alluvial Plain, composed of marshy 

delta land, flat brush-covered plains, and large lakes, 

is dissected by the Mississippi River,-bayous, drainage ditches, and canals. The Mississippi River flows 

southeastward through most of the New Orleans area, 

then makes a sharp turn southward in St. Bernard and 

Plaquemines Parishes. The river now occupies a position on the east side of the Mississippi Alluvial Plain, 

which was formed by its aggradation. This position 

is the result of regional eastward tilting.

The area south of Lake Pontchartrain and near the 

banks of the Mississippi River in northern St. Charles, 

Jefferson, Plaquemines, northern St. Bernard, and 

southwestern Orleans Parishes will be referred to in 

this report as the New Orleans industrial district. 

Most of the larger industrial plants, commercial establishments, and public water-supply systems are 

located along the river where they can gain access to 

its large flow of water and its means of transportation.

Climate

The area is characterized by a humid subtropical 

climate, and usually has long summers and short 

winters. The mean annual temperature based upon an 

80-year period of record is 69.8°F and the mean 

monthly temperature ranges from 55°F in January to 

83°F in July (fig. 2). The maximum temperature observed to date was 102°F in July 1901 and June 1915 

and the minimum temperature was 7°F in February 

1899. Temperatures of 100° are infrequent, and temperatures of 95°F or higher occur on an average of 

only 5 times a year. Only 23 times during the period 

of record has the temperature fallen as low as 24°F.

Precipitation is well distributed throughout the year, 

the mean annual precipitation being 60.53 inches for 

1871 1953. The maximum annual precipitation was 

85.73 inches in 1875, and the minimum was 31.07 

inches in 1899. The mean monthly precipitation for 

the period of record is shown in figure 2. There are

no definite rainy seasons; however, the highest normal 

monthly precipitation occurs in July and August and 

the lowest in October and November. No measurable 

snow has fallen on the city since January 22, 1935, 

when 0.1 inch was recorded.

Tornadoes are rare, and only 3 hurricanes have 

passed through the area in the past half century. The 

relative humidity is high throughout the year. There 

is sunshine about 59 percent of the time and the average annual wind velocity is about 8 miles per hour, the 

maximum of record being 98 in September 1915. These 

data were collected and furnished by the U. S. Weather 

Bureau.

Natural Resources

The primary natural resources of the greater New 

Orleans area are oil, gas, and water. Locally in 

southern St. Tammany Parish, clay, sand, and gravel 

are used mostly for.concrete and ceramic products. 

Oil is produced in 20 localities and gas in 15; thus, the 

area is an important source of petroleum (La. Dept.. 

Conserv. ,1953). Water has always been an important 

natural resource; its principal uses are for public 

water supplies, industrial supplies, waste disposal, 

and navigation.

Population

The total population of the New Orleans area cannot 

be determined exactly because parts of several parishes are included, but a reliable estimate from the 

1950 U. S. Census is 685,000. The city of New Orleans 

shows the greatest concentration with 570,445, which 

represents about 80 percent of the population of the 

area. The 1950 population of the principal cities (more 

than 5,000) follows:

New Orleans................................ 570,445

Gretna.......................................... 13,813

Westwego.:................................... 8,328

Kenner........................................ 5,535

Covihgton..................................... 5,113

Transportation

The area is served by 8 tru,nk railroad lines which 

carried about 12,000,000 tons of cargo in 1953; 4 

buslines; 9 airlines of which 8 are passenger and 1 is 

cargo; 75 trucklines of which 35 are common carriers 

and 40 are contract carriers; 80 steamship lines which 

carried about 17,000,000 net tons in 1953; 40 barge 

lines which carried about 23,000,000 net tons in 1953; 

and a network of Federal, State, and Parish highways. 

These data were obtained from publications of the New 

Orleans Chamber of Commerce.

One of the most important waterways of the nation is 

the Mississippi River, on which "the port of New Orleans 

is located. The Inner Harbor-Navigation Canal (Industrial Canal) was built as a connecting link between 

Lake Pontchartrain and the Mississippi River and joins 

the Gulf Intra-Coastal Waterway, which extends from 

Brownsville, Tex. , to Florida. Thus, these different 

modes of transportation provide direct and indirect 

passenger and freight service to principal cities 

throughout the world.
MONTHLY PRECIPITATION AIR TEMPERATURE 80-VtAR RECO

ANNUAL PRECIPITATION

Figure 2. Climatological data, New Orleans, La.
PRINCIPLES OF OCCURRENCE OF WATER

The Industrial Development

The industrial growth of the greater New Orleans 

area is primarily the result of its geographic location 

near the mouth of the Mississippi River. The port of 

New Orleans is now second in the United States in 

dollar value of foreign trade, handling more than a 

billion dollars of cargo annually. It is a general cargo 

port and leads the nation in the export of corn, wheat 

flour, and cotton, and in the importation of sugar, 

molasses, burlap and bagging, sisal, jute, and hemp. 

It is second in the importation of bananas and coffee. 

With the discovery of oil and natural gas and with an 

abundance of water, the area contains one of the largest refining potential capacities in the State. The area 

is within the chief region of the State for truck-crop 

production and on the fringe zone of the largest sugarcane belt in the United States.

It would be impracticable to mention in this report 

allthe industries that have aided in the growth of the 

area; however, some of the important ones are: canning of food and kindred products, brewing, powergenerating plants, transportation equipment including 

ship and boat building, defense plants, textile and 

textile products, chemical and allied products, fabricated metal products, and paper and milled products. 

It is a major U. S. Navy repair base and is the home 

of four universities.

DEFINITION OF TERMS

In this report the chemical concentrations are expressed either in parts per million or equivalents per 

million. A part per million (ppm) is a unit weight of 

a substance dissolved in 1 million unit weights : of the 

solution. For example, 50 ppm of chloride means 

that there are 50 milligrams of chloride in 1,000,000 

milligrams of the solution.

An equivalent per million (epm) is an expression of 

the reacting value of a substance. It is a unit equivalent weight of an ion contained in 1 million unit 

weights of the water. An equivalent weight is defined 

as the weight that is exactly equal in reacting capacity 

to one atomic weight of hydrogen (1.0080 g). The 

equivalent per million of a substance is calculated by 

dividing the concentration in parts per million by its, 

equivalent weight.

A water that contains more than 1,000 ppm of dissolved solids is called saline. .Water containing from 

1,000 3,000 ppm is said to be slightly saline; water 

containing 3,000 10,000 ppm of dissolved solids is 

moderately saline.

Biochemical oxygen demand (B.O. D.) is the amount 

of oxygen used by micro-organism sin the biochemical 

oxidation of organic matter in a specified time at a 

specified temperature. The B. O. D. , as determined 

by standard laboratory procedure for 5 days at 20°C, 

is usually expressed in parts per million.

Suspended sediment is that sediment which remains 

in suspension in water owing to the upward components 

of turbulent currents and as a colloid. Suspended sediment is usually expressed in parts per million.

Cubic foot per second (cfs) is the rate of discharge 

of a stream whose channel is 1 square foot in crosssectional area and whose average velocity is 1 cfs. 

Mgd is the abbreviation for million gallons per day and 

gpm is the abbreviation for gallons per minute 1 cfs = 

0.646 mgd = 449 gpm. An acre-foot is the amount of 

water required to cover an area of 1 acre to a depth of 

1 foot and is equivalent to 43,560 cubic feet, or 325,851 

gallons.

Cubic feet per second per square mile is the average 

number of cubic feet of water flowing per second per 

square mile drained, on the assumption that the runoff 

is distributed uniformly in relation to time and area.

Specific capacity of a well is its rate of yield per 

unit of drawdown. It depends upon the hydraulic characteristics of the aquifer; rate and length of time of 

pumping, andeffeciencyof well construction. Thus if a 

well is pumped at a rate of 500 gpm and the drawdown 

is 50 feet, the specific capacity of the well is 10 gpm 

per foot.

PRINCIPLES OF OCCURRENCE OF WATER 

Sources of Water

Precipitation is the source of fresh water, and 

reaches the earth in the form of rain, snow, hail, or 

sleet. It rarely occurs in the New Orleans area except 

as rain. In the endless cycle of water from the clouds 

to the earth and back again, a part returns to the atmosphere through evaporation and transpiration and a 

part runs off the land into natural waterways and returns to the seas. The remainder seeps into the ground; 

and a part is evaporated and transpired and the rest 

eventually reaches the ground-water zone, from which 

it is discharged by seepage or by evapotranspiration.

Precipitation on the city of New Orleans is about 60 

inches annually, and excess precipitation must be 

pumped into Lake Pontchartrain to prevent flooding of 

the city, a great part of which is below mean sea level. 

Excess precipitation that falls on the city, and precipitation that falls on the marshlands and coastal lagoons 

such as Lakes Salvador, Des Allemands, Cataouatche, 

Maurepas, and Pontchartrain, is lost at present as a 

fresh-water source, because it soon becomes saline 

upon mixing with salt water from the Gulf of Mexico.

The principal sources of water of all kinds for the 

New Orleans area are the Mississippi River, Lakes 

Pontchartrain and Maurepas, and wells. The flow of 

the Mississippi River at New Orleans comes mostly 

from large land areas outside Louisiana. Lakes Pontchartrain and Maurepas (fig. 3) receive, continual 

fresh-water inflows from local tributaries that drain 

eastern Louisiana and a part of the State of Mississippi. Water from wells in the New Orleans area 

comes largely from water-bearing, sands that receive 

recharge north of the New Orleans area. Locally some 

of the sands probably receive their recharge from 

streams and precipitation in that region of the New 

Orleans area just north of Lake Pontchartrain.

Large quantities of water which require much chemical treatment for public water supplies are available
WATER RESOURCES OF THE NEW ORLEANS AREA

discharge

®29 

River mure, stage only

A17

Discontinued river gage, 

stage, and discharge

Figure 3. Map of the New Orleans area and vicinity showing river systems, lakes, and gaging stations.

in the Mississippi River. During low-flow periods, 

salt water has extended in the Mississippi River as 

far as and beyond the city of New Orleans.

Most of the water in the Industrial Canal used by 

industries comes from Lake Pontcha train. It is too 

saline, however, to be suitable to all users and is 

Especially unsuitable as a source of potable water. 

Lake Pontchartrain receives saline water by tidal 

inflow from the Gulf of Mexico through Lake Borgne 

and the Rigolets and other smaller outlets. However, 

water entering through the Rigolets has been diluted 

by Pearl River inflow into Lake Borgne. After entering Lake Pontchartrain this water is further diluted

by large volumes of water from those tributaries 

emptying along its northern shore. The saline content 

probably is not constant throughout the lake because of 

the variable inflow of fresh and saline water. The waters of the lake are probably fresher along the northern 

shore where the major tributaries enter The principal 

tributary streams are the Amite and Tickfaw Rivers, 

which empty into Lake Maurepas, and the Tangipahoa 

and Chefuncte Rivers. All these streams are among 

the best sources of water in the State of Louisiana 

because they have dependable flows of excellent quality. The salinity of Lake Maurepas is pr <bably lower 

than that of Lake Pontchartrain because it is less likely 

to be affected by salt-water encroachment from the Gulf
PRINCIPLES OF OCCURRENCE OF WATER

of Mexico and is more affected by dilution from the 

Amite and Tickfaw Rivers.

Ground water south of Lake Pontchartrain is not 

used as a source for public water supplies. Ground 

water is withdrawn for industrial uses from three 

principal water-bearing sands, the "200-foot, " "400- 

foot, " and "700-foot" sands. Although water from a 

"1,200-foot" sand is used to some extent, it is not 

considered a principal source of ground water because 

of the poor quality of its water. The "700-foot" sand 

is the most important water-bearing sand because it 

is the most extensive and generally contains water of 

the best quality.

North of Lake Pontchartrain, wells 60-2,000 feet 

deep yield fresh water used mostly for public and 

private water supplies. There are no known watersupply wells deeper than 2,000 feet in the New Orleans 

area; however, fresh-water-bearing sands are present 

to a maximum depth of about 3,000 feet north of Lake 

Pontchartrain.

Significance of the Quality of Water

Water probably has more different uses than any 

other single natural resource. The quality of water is 

a very important factor, sometimes more important 

than the quantity. Because of its wide variety of uses, 

no single set of standards can be established. Treatment costs are often higher in converting a water 

supply of poor quality to one of good quality than the 

cost of a new supply.

The quality of the water comprises its chemical, 

physical, and sanitary characteristic's.

The chemical quality of the water refers to the total 

amount and the interrelationship of the dissolved mineral constituents in the water, which determine its 

suitability for a great number of uses. Physical 

quality refers to such properties as turbidity, color, 

temperature, and odor, which also are important 

factors in evaluating the suitability of the water for 

industrial, municipal, and domestic uses.

The sanitary quality of the water shows the degree 

of pollution of surface and ground water. The term 

pollution implies the fouling of an otherwise inoffensive 

water by sewage or other liquids or suspensions, thus 

rendering it offensive to sight and smell and unsatisfactory for potable, culinary, or industrial uses (Am. 

Water Works Assoc. , 1950, p. 29). Natural pollution 

occurs where the drainage from unpreventable sources 

caused the fouling of clean water. Some of the results 

of the pollution of a stream, such as color, turbidity, 

odor, and taste, are easily seen or detected. The 

effects of acid and oil wastes, oxygen depletion, and 

toxicity are not as easily recognized by the casual 

observer, although studies of the stream fauna may 

reveal the presence of a serious pollution problem.

The water in a stream free from pollution generally 

has a high dissolved-oxygen content, and no significant 

B.O. D. , taste, or odor. However, in the zone of 

recent pollution the amount of dissolved oxygen in the 

water is decreased, and the B.O. D. and turbidity are 

increased. The septic zone is characterized also by 

noxious odors. Temperature is an important physical

characteristic of water for industrial and domestic 

uses. Uniformity of temperature is important to operators of industrial plants, especially for the water used 

for cooling. In municipal water-treatment plants, the 

amount of coagulant to be added to water to form a floe 

in a specified time is dependent on the water temperature; the lower the temperature, the longer it takes to 

form a floe with a given amount of coagulant.

Hardness is a measure of the soap-consuming property of water and is generally considered troublesome 

in concentrations greater than 150 ppm because more 

soap is required to form a lather. The use of excessively hard water also results in the formation of 

scale in water pipes (especially in hot-water pipes), 

thus reducing the carrying capacity of the pipes. A 

certain amount of hardness is desirable in prevention 

of rust by the deposition of a thin protective coating of 

calcium carbonate on the inner surface of water pipes. 

Hardness in water is caused primarily by the presence 

in solution of calcium and magnesium salts. Iron, 

aluminum, barium, zinc, some other metals, and free 

mineral acid also may cause hardness, but the amount 

of these ions normally found in a natural water is small 

and therefore they do not appreciably affect the hardness. Carbonate ("temporary") hardness is that part 

of hardness caused by the combination of calcium and 

magnesium ions chemically equivalent to the bicarbonate ion. This type of hardness can be removed by 

heating, thus precipitating as calcium and magnesium 

carbonate. The remaining hardness is noncarbonate 

("permanent") hardness and is more difficult to remove.

The residue on evaporation (dissolved solids) is a 

measure of the weight of dissolved mineral salts and 

is also a measure of the usability of the water. Water 

used for certain industrial purposes not only must 

meet specific requirements for allowable concentrations 

of individual ions but also must conform to allowable 

concentrations of dissolved solids.

Staining of porcelain plumbing fixtures and laundry 

may result from the use of water containing excess 

iron and maganese. Generally accepted drinking-water 

standards limit the combined iron and manganese concentration to 0.3 ppm (U. S. Public Health Service, 

1946). When soluble iron compounds are oxidized they 

become insoluble and form precipitates which may 

impart color and turbidity to the water. Crenothrix, 

an organism associated with waters containing iron 

and manganese, may cause clogging of pipes and well 

screens by forming in clumps or as slime attached to 

the wells or pipes or other submerged surfaces.

Excessive quantity of fluoride in water is associated 

with dental fluorosis (mottled enamel) whereas about 1 

ppm reduces the incidence of dental caries (tooth 

decay) in children's teeth. The U. S. Public Health 

Service Drinking Water Standards (1946) states that 

the presence of fluoride in excess of 1.5 ppm in water 

supplies used by common carriers subject to Federal 

quarantine regulations shall constitute grounds for 

rejection of the supply. Water containing fluoride in 

concentrations greater than 1.5 ppm may cause mottling 

and discoloration of teeth if used during the period of 

calcification. Investigations, however, have disclosed 

that children with mottled enamel caused by an excess 

of fluoride in the drinking water experienced fewer 

dental caries than children whose drinking water contained no fluoride or only trace quantities (Am. Water
WATER RESOURCES OF THE NEW ORLEANS AREA

Works Assoc. , 1950, p. 57). Many health agencies 

recommend that about 1 ppm fluoride be present in 

potable water supplies.

Turbidity in water is caused by suspended sediment 

or organic material. In water-treatment plants where 

the water is processed through zeolite material, the 

raw turbid water, unless previously clarified, will 

deposit suspended material on the surface of the resin 

grains and eventually will interfere with the passage 

of water and cause difficulty in the flushing process. 

Turbidity in the water also causes soiling of paper, 

linen, and other textile products.

SURFACE WATER

Records Available

Records of stage and of discharge in the New 

Orleans area are available in the Water-Supply Papers 

of the U. S. Geological Survey, publications of the 

Mississippi River Commission, the Corps of Engineers, and the U. S. Weather Bureau. Continuous 

records of stage on the Mississippi River at New 

Orleans (Carrollton gage) and at Baton Rouge began 

in 1872. Continuous records of discharge at Baton 

Rouge have been available since 1939. Discharge 

records between 1931 and 1939 were computed on the 

basis of the stations closest to Baton Rouge. Records 

of discharge and (or) stage are available at several 

other sites on the Mississippi River and on other 

streams, lakes or canals in the vicinity of the New 

Orleans area for shorter periods since 1872.

The location and duration of selected gaging-station 

records in the vicinity of New Orleans area is given 

in table 1. Data collection sites are shown on figure 

3. Numbered points refer to table 1. Records of floodcrest stages and miscellaneous discharge measurements at 17 sites, not indicated in table 1, are available in the Baton Rouge office of the Surface Water 

Branch of the U. S. Geological Survey. Some stage 

records not indicated in table 1, but collected by the 

Corps of Engineers, are available in the district 

office in New Orleans. These stage records are 

principally on the Intracoastal Waterway, Industrial 

Canal, and the Mississippi River.

Mississippi River

The Mississippi River, one of the great rivers of 

the world, has been important in the establishment 

and growth of the New Orleans area, as well as in the 

development of the United States. Below Baton Rouge, 

the river has built a great fan-shaped delta on which 

the city of New Orleans is located.

About 200 miles upstream from New Orleans, the 

Mississippi River divides into the distributary 

system of the lower Mississippi River valley. At this 

point Old River connects the Mississippi River with 

the Atchafalaya River, the main distributary channel 

to the Gulf of Mexico. The head of the Atchafalaya 

River is at the juncture of Red and Old Rivers. A 

part of the flow of the Mississippi River moves west 

through Old River for 6.2 miles and thence down the 

Atchafalaya River to the gulf.

Distribution of the flow in the channels between the 

Mississippi and Atchafalaya Rivers vitally affects the 

volume of flow past New Orleans in the main stem of 

the Mississippi River. When the Red River is high 

some of its waters flow through Old River into the 

Mississippi River. Not since 1942, and then for only 

9 days, has water from the Red River flowed into the 

Mississippi River. The distance to the Gulf of Mexico 

via Old and Atchafalaya Rivers is 142 miles whereas 

it is 315 miles by way of the Mississippi River. As a 

result, slopes are steeper and velocities are higher 

through the shorter route in the Atchafalaya River 

channel (Mississippi River Comm. , 1950).

Below New Orleans, near the Head of Passes, the 

Mississippi River divides into several distributary 

channels through the recent delta fan (fig. 3).

In its history, the Mississippi River has passed 

through several channels in its course to the Gulf of 

Mexico. In the last 200 years, meandering in the lower 

Mississippi River has been halted by man-made improvements for navigation, flood control, and channel 

stabilization. The Corps of Engineers, through the 

Mississippi River Commission, which was organized 

in 1879 has made studies and recommendations for the 

control and development of the Mississippi River, its 

tributaries and distributaries.

Floods and Flood Protection

Since the early days of settlement of the lower Mississippi River valley, settlers have been plagued with 

floods. Efforts to control these floods have produced 

a progressive decrease in flood hazards to the valley. 

Not since 1849 has the city of New Orleans suffered 

serious flooding.

Stages of the Mississippi River in New Orleans, at 

the Carrollton gage operated by the Corps of Engineers, 

have been recorded intermittently between 1828 and 

1871, and continuously since 1872. Maximum yearly 

elevations of the Mississippi River as recorded at the 

Carrollton gage for the period 1872 1953 are shown in 

figure 4. An increase in the height of flood crest between 1872 and 1927 was the result of confining the 

channel between levees. Levee crevasses generally 

prevented floods from reaching a stage of 20 feet at 

the Carrollton gage. However, the great floods of 

1912, 1922, and 1927 did crest higher than 20 feet. 

Bonnet Carre spillway, essentially complete in 1931, 

prevented crests of the great floods of 1937, 1945, and 

1950 from exceeding 20 feet at Carrollton.

The number of occurrences, by months, of the maximum annual stages of the Mississippi River at New 

Orleans from 1872 to 1953 is shown in figure 5. 

During the 82 years of record, the maximum annual 

stages occurred more than 90 percent of the time in 

the 5 months, February through June, and more than 

50 percent of the time in April and May. Water-surface 

profile's of the Mississippi River at New Orleans and 

vicinity during the floods of 1927, 1945, and 1950 are 

shown in figure 6. The difference between mean low 

water and floods of extreme stages is about 33 feet at 

Donaldsonville, 19 feet at Carrollton, 17 feet at 

Chalmetteand about 10 feet at West Pointe a la Hache.
Table 1. Location and duration of selected gaging-station records in the vicinity of New Orleans, La. 

[ USGS, >U. S. Geological Survey; CE, Corps of Engineers, Department of Army; USWB, U. S. Weather Bureau]

Index

no.

(fig. 3)

Station Location Records available 

Pearl River basin

1

2

9

4

5

Pearl River near Bogalusa^...........................................

Bogne f-Wttn at Frai^ldlnlni,,,.,^^ ^ ,,,,,, ,,, I..M,

Pearl River at Pearl River............................................

Bridge on State Highway 35..............................................

do

do

Bridge on State Highway 7..................,...........................^

Gage heights and daily discharge, October 19

Oct. 1948 to date...................................

Gage heights and daily discharge, Aug. 1928 

Oct. 1938 to date. Gage heighls since Feb

USGS,' October 1937 to date, CE, gage heigh

(unpublished). 

Gage heights, since October 1899 to date (un

Lake Pontchartrain basin

Lake Pontchartrain at Mandeville 

Chefuncte River near Folsom......

Tangipahoa River at Robert^.....

Tickfaw River at Holden...........

Tickfaw River near Springfield... 

Natalbany River at Baptist^.., 

Amite River near Darlington.^...,

Comite River near OKve Branch...........................

Comite River near Comitew..............................t

Amite River near Denham SpringsnM...M...............

Ward Creek at Government St., Baton Rouge.^......,

Bayou Duplantier at City Park Lake, at Baton Rouge, 

Ward Creek at Siegen Lane near Baton Rouge.^....,

Bayou Manchac at Hone Villa..................

Amitp River at Port Vincent^............. ..........

Petite Amite River near Sorrento.....................

Lake Pontchartrain at Frenier..........................

Lake Pontchartrain at West End........................

Lake Pontchartrain at Little Woods...................

Rigolets near Lake Pontchartrain......................

On lake side at end of Lotf s Pier....,

Bridge on State Highway 189..........

Bridge on U. S. Highway 190.^......

*"

Bridge on U. S. Highway 190.,

Bridge on State Highway 35..^................................

Bridge on State Highway 36....................................

Bridge on State Highway 877...................................

Bridge on U. S. Highway 190...^..........«..«......Mi...,

U. S. Highway 61 (Government Street) -in Baton Rouge, 

Lower end of City Park Lake,...............^.......,........,

Bridge on Siegen Lane,. ....M.....^.,.,... ....................

Bridge on U. S. Highway 61 at Hope Villa^..............,

Bridge on State Highway 46 at Port Vincent..., 

Junction with New River Canal near Sorrento., 

Frenier on structure 400 feet east of shoreline.................

Attached to west end of Municipal Yacht Building in west

Harbor in New Orleans. 

Right side of C orison's wharf......................................

Southwest end of U. S. Highway 90 bridge across Rigolets

extreme east end of Lake Pontchartrain.

end

Gage heights, Sept. 26, 1931 to date..........

Gage heights, and daily discharge, January 1

Gage heighls and daily discharge, October 19

Gage heighls and daily discharge, October 19

Gage heights, May 1947 to date.................

Gage heights and daily discharge, August 194

Crest stages, March 1949 to November 1950, 

October 1950 to date. 

Gage heights and daily discharge, August 194

Gage heights and daily discharge, March 194

Gage heights and daily discharge, September 

Gage heights and daily discharge, March 29, 

Gage heights and daily discharge, April 1933 

Gage heights and daily discharge, December 

Gage heights, February 1945 to date (unpubl

Gage heights, August 1945 to date (unpublis

Gage heights, intermittently Mar. 10, 1950 t

Gage heights. Sept 25, 1931, to date........

Gage heights, Sept. 25, 1931 to November 3

1949 to date. 

Gage heights, Sept. 28, 1931 to date,........,

Gage heights, Sept. 28, 1931 to date..........

Mississippi River main stem

Mississippi River near Baton Rouge.

Mississippi River at PlaquemineMn..M. 

Mississippi River at Donaldsonville. 

Mississippi River at College

Mississippi River at Reserve.............................

Mississippi River at Bonnet Carre.......................

Mississippi River at New Orleans.^...,................

Mississippi River at Carrollton (New Orleans).......

Mississippi River at Chalmette....................

Mississippi River at West Pointe a la Hache..., 

Mississippi River at Fort Jackson..................

Bridge on U. S. Highway 190............,.,....^........,,.,,.,,,.M.

Yazoo and Mississippi Valley railroad station.......................

Plaquemine lock...........................................................

Donaldsonville City waterworks plant^.............................M

Left,, bank 300 feet downstream from new College Point Pharmacy.

Wharf of Godchaux Sugars, Inc.........................................

Spillway structure near Norco...........................................

Huey P. Long bridge on U. S. Highway 90..........................

Near intersection of St. Charles Avenue and Levee............... 

Batween berths B and C of Southern Railway slip no. 1M.M..., 

Right bank at ferry landing^..............,...........................

Wharf 1 mile downstream from Fort Jackson.......................

Gage heights, June 1940 to date................

Gage heights, January 1872 to date, occasion

ments 1929 and June 1938 to date, daily di

to date.

Jan. 1880 to May 1885, Dec. 1888 to date..

Gage heights, June 1890 to date.................

Gage heights, December 1879 to September 

to date.

Gage heights, March 1929 to date.............

Gage heights, March 1930 to date..............

Gage heights, November 1934 to date.........

Gage heights, January 1872 to date, occasion

ments 1851, 1852 and 1879-1927; daily dis

1938-44.

Gage heights, October 1923 to date............

Gage heights, February 1926 to date...........

Gage heights, February 1891 to date...........

Sites at or near Lake Des Allemands and Lake Salvador

Bayou Chevreuil near ChegbyM.Mv.., 

Bayou Des Allemands at AUemands,, 

Bayou Barataria at Barataria...........

Bridge on State Highway 83 near Chegby......

U. S. Highway 90 at Allemands.................

Wharf near junction with Bayou Villars........

Gage heights, July 11 1951 to date...........

Gage heights, Jan. 18, 1950 to date...........

Gage heights, Jan. 6, 195') to Sept 26, 1950
FEET IN HEIGHT, GAGE 

1872

1875

1880

1885

1890

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1953

t yyyyyyyyyyyyyyyy* Yyyyyyyyy^/yyyyyyyyyyyyTA

y/yyyyyyyyyyyyyyyyyyyyyyyyyyyyA

yyyy/yyyyyyy/yyyyyyyyyyyyyyyyyyyy/yyyyA

yy/////;////^^^

yyyyyyyyyyyyyyyyyyyyyyyyyyyx

yyyyyyyyyyyyyyyyyy/yywyyyyyyyyyyyyyyyyA

yyyyyyyyyyyyyyyyyyy/yy/yy/yyyyyy^^

CQ.Q."

aaag

33^ 

12

'/////'.//S'///'?//^

Y/yyyyyyyyyy/yyyyyyyyyyyyyyyyyy/yyyyyyA

OT H3XVM S3OHnOS3H JO 3HJL M3N SNVaiHO V3HV 
SURFACE WATER 11

Each column shows number of years 

in which highest stage of the year 

occurred in the month indicated

Jan. Feb. Mar. Apr. Aug. Sept. Oct Nov. Dec.

Figure 5. Distribution graph showing frequency of annual floods by months, Mississippi River at New Orleans,

1872-1953.

The 1927 flood in the lower Mississippi River valley 

was one of the great national disasters. The valley 

was largely submerged, scores of lives were lost, and 

property damage was high. Crevasses above Angola 

and below New Orleans saved the city from being 

flooded.

The devastation wrought by the 1927 flood spurred 

Congress to pass the Flood Control Act of May 15, 

1928 which committed the Federal government to a 

definite program of flood control that through the 

years has been modified and enlarged by subsequent 

Flood Control Acts. The flood control plan adopted 

for the Mississippi River provides for protection 

against a project flood, the greatest hypothetical flood 

that meteorologists consider possible. Below the 

mouth of the Arkansas River the project flood is IT27 percent greater than the greatest flood of record, 

that of 1927 (Mississippi River Commission, Feb. 

1950).

In the vicinity of Old River, the project flood is 

estimated to be about 3,000,000 cfs. The Atchafalaya 

River system will carry about half, or 1,500,000 cfs, 

and the main stem of the Mississippi River below Old 

River will carry half, of which 250,000 cfs will be 

diverted through the Bonnet Carre spillway, with the 

remainder, or 1,250,000 cfs, flowing in the main stem 

of the Mississippi River past New Orleans.

Since the passing of the Flood Control Act of 1928, 

floods in 1929, 1937, 1945, and 1950 in the lower Mississippi River valley have proved the effectiveness of 

the flood-control measures which have been undertaken. 

Work has been continuous and is so extensive that it is 

impossible here to completely describe the different 

phases.

To safely pass the project flood below Old River, 

several floodways, levees, and control structures 

have been built and some structures remain to be built. 

Flow of the Mississippi River through Old River into 

the Atchafalaya River is uncontrolled. West Atchafalaya Floodway, practically completed by 1938, the 

Atchafalaya River, and Morganza Floodway and Control 

Structure, recently completed, are designed to carry 

about 1,500,000 cfs of the project flood. Bonnet Carre 

spillway, built specifically to prevent flooding of New 

Orleans, was essentially complete in 1931. Bonnet 

Carre spillway will probably be used about once in 5 

years, for periods ranging from 1 to 3 months. The 

spillway is used when necessary to prevent stages 

exceeding 20 feet on the Carrollton gage, a stage 5 

feet below levee grade. This stage was selected to 

prevent disturbance/ of waterborne and railroad traffic, removal of goods from wharves and river-front 

storehouses, and acute apprehension and fear among 

the general populace and business interests.
12 WATER RESOURCES OF THE NEW ORLEANS AREA

High water profiles plotted from highest 

observed gage readings and do not 

represent instantaneous slopes

180 160 120 100 80 60 

MILES ABOVE THE HEAD OF PASSES

Figure 6. Water^surface profiles for selected floods on the Mississippi River, New Orleans and vicinity.

A careful watch of stages and discharges along the 

Mississippi River above New Orleans is maintained 

when floods are in progress and daily instructions are 

issued for operation of the bays of the spillway to prevent stages from rising higher than 20 feet at the 

Carrollton gage. By opening or closing any or all of 

350 bays, the stage at New Orleans can be regulated 

within close limits.

The gates have been operated three times since the 

Bonnet Carre spillway was completed. The spillway 

was used from January 30 to March 16, 1937, from 

March 20 to May 17, 1945, and from February 10 to 

March 19, 1950. The effectiveness of the operation

of Bonnet Carre spillway in maintaining elevations in 

the vicinity of New Orleans below 20 feet on the 

Carrollton gage during the time the spillway was 

opened February 10 to March 19, 1950 may be observed in the graph shown in figure 7.

Discharge

The farthest point downstream t»n the Mississippi 

River at which discharge records are collected on a 

systematic basis is at Baton Rouge, about 130 miles 

from New Orleans. The inflow between Baton Rouge 

and New Orleans is negligible, so that the flow
SURFACE WATER 13

JANUARY FEBRUARY MARCH AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER

Figure 7. Stage hydrographs of the Mississippi River near New Orleans (Huey P. Long Bridge).

observed at Baton Rouge is essentially the same as 

that in the vicinity of New Orleans. Hence, discharges 

for that station will be considered applicable at New 

Orleans.

The mean flow for the 24-year period, 1931 54, is 

309,000 mgd, according to the Corps of Engineers. 

Maximum discharge recorded during that period was

952,000 mgd on April 16, 1945, and the minimum discharge recorded was 47,600 mgd on October 19, 1939.

The maximum, average, and minimum of the mean 

monthly discharges are shown on figure 8. This diagram shows that in most years the maximum of the 

average discharges occur during March, April, and 

May and that the season of low runoff extends usually
14 WATER RESOURCES OF THE NEW ORLEANS AREA

1,400,000

1,200,000

1,000,000

800,000

600,000

400,000

200,000

From reports of the Mississippi River Commission. 

Discharge prior to 1939 and for 1946 computed 

on basis of records collected at the other stations 

on the Mississippi River

Jan. Feb. Mar. Oct. Nov. Dec.

Figure 8. Maximum, minimum, and average mean monthly discharge of the Mississippi River

at Baton Rouge, 1931-53.

from August through November. Although there is a 

considerable range in discharge between the typically 

high and low season of a year, generally the flow 

changes relatively slowly and uniformly between these 

periods. Mississippi River elevations at the Carrollton gage in New Orleans for 1947, a year of near medium flow, are shown in figure 7.

Port Facilities and Navigation

The normal width of the navigable channel within 

the limits of the port of New Orleans ranges from 

1,600 to 2,400 feet. Provisions have been made to 

maintain a minimum channel depth of 35 feet and minimum width of 1,500 feet.

The harbor has an average depth of 150 feet at midstream and along the wharves the depth ranges from 

30 to 60 feet. The range in tides averages about 10 

inches during low stages and becomes negligible during high stages of the river.

From the lower limits of the port of New Orleans 

south on the Mississippi River to Head of Passes, a 

channel 40 feet deep by 1,000 feet wide and 86.7 miles

long is available for navigation by ocean-going vessels. 

Southwest Pass has a channel depth of 35 feet, width 

between 600 and 800 feet, and length of 21.2 miles; 

South Pass has a channel depth of 30 feet, width of 450 

feet, and length of 14.2 miles. These passes provide 

for passage from the Head of Passes to the Gulf of 

Mexico.

The Gulf Intracoastal Waterways, an inland navigation channel generally parallel to the coast of the Gulf 

of Mexico is available for barge traffic from New 

Orleans. This channel, 12 feet deep and 125 feet wide, 

extends eastward from New Orleans to Carrabelle, 

Fla., and westward to Brownsville, Tex. A navigable 

channel 35 feet deep and 500 feet wide, extends 128.6 

miles from New Orleans to Baton Rouge and accommodates ocean-going vessels to that point.

The Mississippi River Inland Waterways system developed for barge traffic connects New Orleans by navigable channels with the Great Lakes, Sioux City on 

the Missouri River, Minneapolis on the Mississippi 

River, Chicago on the Illinois River, Pittsburgh on the 

Ohio River, and Knoxville on the Tennessee River. 

Above Baton Rouge, it is at least 9 feet in depth and of 

variable widths.
January February March April June July August September Oc

Figure 9. Relationship between Streamflow and chemical composition of Mississippi River water at Carrollton treatment 
16 WATER RESOURCES OF THE NEW ORLEANS AREA

Quality of the Water

The concentration of the mineral constituents of the 

Mississippi River water at New Orleans varies 

throughout the year, although the chemical elements, 

expressed as a percentage of the total mineral content, 

remains uniform except during periods of saline-water 

encroachment. Daily determinations of chloride, alkalinity, and sanitary quality are made at Carrollton. 

Total and noncarbonate hardness, calcium, magnesium, sulfate, and dissolved solids are determined 

weekly.

The chemical composition of the Mississippi River 

water at the Carrollton treatment plant in relation to 

streamflow for the year 1953 is shown in figure 9. 

During the period of low flow, from October through 

December, the chloride increased from 33 ppm on 

October 19 to 230 ppm on November 23; likewise, the 

dissolved solids increased from 290 ppm to 480 ppm 

on these dates. When the discharge of the river decreases below 170,000 cfs the danger of saline-water 

encroachment increases. The increase of the chloride 

content of the river water indicates that there is insufficient flow to hold back the wedge of saline water 

that gradually moves upstream along the bottom of the 

river channel as the flow of the river decreases. This 

explanation of the increase in the chloride content of 

the water at the Carrollton plant is substantiated by 

the fact that the chloride content in the river water at 

the Algiers plant downstream from Carrollton is consistently higher. According to the Corps of Engineers, 

New Orleans District, the normal chloride content of 

the Mississippi River at and below New Orleans is 

about 30 ppm. An increase in the-surface salinity substantially greater than this amount is generally indicative of movement of the salt wedge up to and beyond

CHLORIDE, PARTSER MILLION IN 

S R> !PSQ _-l\»<J" -*O 

uiOuiOuiocnJStnJ c-O 

^^ ~"^

Algiers

'\/

Carrollton

1

reatme

 

treatmi

it plant

/

I/

'

;nt plan

1

 

1^ 

i i i

i i

i i

i -i

i 

; j

/

i

\

\ \

\

n. Feb. Mar. Apr. May June July Aug. Sept. Oct Nov. De

Figure 10. Monthly average chloride content of Mississippi River water at Algiers and Carrollton treatment plants, New Orleans, 1953.

the point of observation. A comparison of the chloride 

concentrations at both plants is shown in figure 10. 

The Corps of Engineers also states that "*** brine 

wedge extended up the Mississippi River at practically 

full strength to Norco, La. , at a depth of 120 feet on 

October 2, 1936. It was accompanied by a peak salinity condition at the surface of the river at the following 

places to the indicated extent:"

Parts per million Date

Port Sulphur............... 2,195.................. October 8

Chalmette.................. 825.................. 7

Algiers...................... 620.................. 7

Celotex...................... 430.................. 7

Carrollton.................. 383.................. 9

Reserve..................... 120.................. H

Baton Rouge............... 130.................. 13

The results of the analyses of the raw water at the 

Carrollton treatment plant for the year 1953 are shown 

in table 2. The water is of the calcium bicarbonate 

type, ranging in concentration of dissolved solids from 

about 100 to more than 500 ppm.

Temperature

The mean monthly air and Mississippi River water 

temperatures at New Orleans for a period of 30 years 

is shown in figure 11. The mean monthly air temperature exceeds the water temperature by about 8° 10°F

Jan. Feb. Mar. Apr. May June July Aug. Sept Oct Nov. Dec.

Figure 11. Mean monthly air and Mississippi River 

water temperatures at New Orleans, 1921 50.

from January to April. The temperature difference 

then gradually decreases through May and June; during 

July and August the water temperature exceeds the air 

temperature by about 1° 3°.

During the 1953 calendar year the temperature of the 

Mississippi River at New Orleans equaled or exceeded 

65°F on 51 percent of the days. It exceeded 85°F on 15 

percent of the days and was less than 50°F on about 18 

percent of the days (fig. 12).
SURFACE WATER 17

Table 2. Concentrations of several constituents in the raw Mississippi River water at the Carrollton treatment

plant, New Orleans, La. , 1953

[Analyzed by New Orleans Sewerage and Water Board]

Date of

collection

Jan. 3......................

10......................

17......................

24......................

Feb. 7......................

14.....................

21.....................

28.....................

Mar. 7.....................

14.....................

21.....................

28.....................

A*%T> A

11..... ................

18.....................

25.....................

May 2.....................

9.....................

16.....................

23.....................

30.....................

13......................

20..... ................

27.....................

July 4.....................

11.....................

18..... ................

2&.......... ...........

An tr 1

8.....................

15.....................

22.....................

29.....................

Sept. 5.....................

12.....................

19.....................

26.....................

Oct. 3.....................

10.....................

17.;...................

24.....................

31.....................

Nov. 7.....................

14.....................

21.....................

28.. ....................

Dec. 5..... ................

12.....................

19......................

26.....................

Calcium

(Ca)

46.4

46.7

46.9

44.0

35.2

34.8

33.2

30.0

29.6

30.4

26.8

29.5

32

33

35

35

35.2

33.2

29.6

29.6

31.2

32.4

33.2

37.6

39.6

40.4

42.8

46.4

45.6

44.0

46.4

45.6

42.8

42.4

45.2

44.0

46.0

46.4

50.0

52.0

52.0

53.2

58.0

58.8

56.8

57.6

58.4

58.0

54.8

54.0

53.2

Magnesium

(Mg)

13.1

13.1

14.6

14.6

12.9

9.7

8.5

8.8

7.8

7.8

7.8

7.5

8.5

14.1

10.0

9.7

12.6

8.7

10.2

8.7

9.2

7.5

10.4

10.9

13.9

14.8

12.2

13.6

13.9

13.1

12.4

11.9

12.4

12.6

12.9

13.1

15.6

16.8

17.0

14.8

13.1

18.4

22.1

24.1

24.8

14.5

24.1

23.1

23.3

21.4

19.4

Alkalinity

(as CaCO^

97

104

119

98

81

76

74

72

70

70

63

74

82

83

79

82

84

77

76

75

75

82

91

98

100

106

103

115

106

107

105

109

112

114

123"

1 99

136

1 ^7

142

145

145

151

1 ^9

147

147

140

143

142

135

130

Sulfate

(S04)

66.5

69.1

62.0

53.0

39.0

36.8

38.8

33.5

30.4

30.8

29

30.0

3?, 6

44.6

41.1

40.7

35.3

32.9

25.9

35.3

35.6

42.3

57.1

57.5

52.2

75.4

74.6

53.4

48.1

45.2

54.5

38.8

48.3

78.3

56.5

70.3

81.0

104.8

104.8

81.4

80.8

81

68.6

66.6

*

Chloride

(Cl)

47

36

36

30

24

21

20

16

16

19

15

17

15

20

17

17

15

20

14

17

14

14

14

18

22

19

23

21

23

24

52

50

31

31

35

48

39

33

52

37

59

96

106

115

111

116

106

101

127

65

Dissolved

solids

317

320

285

281

209

211

195

206

184

184

165

175

198

204

233

201

204

194

170

175

192

180

191

216

255

341

248

242

286

271

304

287

261

260

283

287

273

278

315

339

288

304

454

469

510

507

474

474

497

444

Hardn 

as CaC

Calcium, 

magnesium

170

173

177

170

141

127

118

111

106

108

99

105

115

121

129

128

130

119

116

110

116

112

126

139

156

162

157

172

171

164

167

163

158

158

166

164

179

185

195

191

236

246

244

245

245

240

233

223

213

ess

:o3

Noncarbonate

74

70

57

60

59

46

41

36

34

33

35

29

33

38

44

44

55

40

42

33

38

29

35

42

52

54

54

56

57

54

59

51

40

43

46

48

56

50

55

52

47

64

89

94

97

114

105

92

87

83

78
18 WATER RESOURCES OF THE NEW ORLEANS AREA

90

5 80

70

60

50

40

85°F or above, 

15 percent of year

0 20 40 60 80 100 

PERCENT OF TIME TEMPERATURE EQUALED OR EXCEEDED THAT SHOWN

Figure 12. Cumulative frequency graph of water 

temperature of Mississippi River at New Orleans.

Sediment

The Mississippi River Delta has been built up by the 

deposition of sediments transported by the River. The 

deposition of this waterborne material is a continuous 

process.

At the present time sediment measurements are not 

being made in the reach of the Mississippi River at

New Orleans; however, the Corp of Engineers, U. S. 

Army, measures sediment at Baton Rouge which probably represents the sediment concentrations and loads 

of the river at New Orleans. Figure 13, taken from 

data furnished by the New Orleans District, shows the 

sediment concentration for the 1953 water year. These 

concentrations were obtained from complete analyses 

of samples taken on dates indicated on the figure.

The cumulative monthly sediment load of the Mississippi River at Baton Rouge is shown in figure 14. 

The total sediment load for the year was about 213 

million tons. The heaviest monthly sediment loads 

occurred during March, April, and May. The river 

carried about 53 million tons or 25 percent of the total 

1953 sedimentload in May. The sediment concentration of the River equaled or exceeded 250 ppm during 

60 percent of the 1953 water year (fig. 15).

Pollution and its Control

The Federal Government is authorized by the Water 

Pollution and Control Act of 1950 to appropriate one 

million dollars annually to the states for research 

and studies to prevent and control pollution of the water by industries. Money is also available to the 

states for studies preliminary to the construction of 

approved sewage treatment works and other projects.

The danger of stream pollution is ever present in 

Louisiana "because of the location of diversified 

industrial plants. The raw or partly treated wastes 

from sugar refineries, paper mills, fertilizer plants, 

meatpacking houses, canneries, oil refineries, cement 

plants, wood creosote treating plants, oilfield operations, and other processing plants are discharged 

into Louisiana streams. In addition to the aforementioned possible sources of pollution, some communities release untreated sewage to the streams.

t=t r=t

2 4000 

=! 3000

a: 2000

£ 1000

< 800

| 600

z' 400

2 300

I 200

§ 100

o 8°

fe 60

^ 40

5 30

84 20

	10

^

EXPLANATION -

.Complete analysis on date shown obtained

from Corps of Engineers, 

- U. S. Army, New Orleans District -

OCTOBER NOVEMBER DECEMBER JANUARY FEBRUARY APRIL MAY JUNE AUGUST SEPTEMBER

Figure 13. Sediment concentration of the Mississippi River at Baton Rouge, water year 1953.
SURFACE WATER 19

150,000

125,000

100,000

75,000

50,000

25,000

Figures above columns indicate percent 

of total sediment load for year. Upper 

part of each bar represents the monthly 

suspended sediment load

Figure 14. Cumulative monthly suspended sediment 

load of Mississippi- River at Baton Rouge, water 

year 1953.

Lake Pontchartrain Drainage Basin 

Lake Pontchartrain

Lake Pontchartrain is the largest of several shallow coastal lagoons in the Mississippi River Delta. 

New Orleans is on its southern shore.

The average elevation of Lake Pontchartrain is 

about 0.8 foot above mean sea level. At mean sea level 

its volume is about 4,600,000 acre-feet; the average 

depth is about 12 feet; the surface area is about 610 

square miles; and the normal tide range is about 1 

foot.

Stages in Lake Pontchartrain are dependent on 

inflow from the tributaries to the north of the lake, 

tides in the Gulf of Mexico, and the effect of winds. 

Winds cause higher stages than tides do. The maximum stage recorded on the lake was about 6 feet 

above mean sea level and was the result of a hurricane on September 19, 1947. The minimum stage of 

record occurred on January 26, 1938, and was about 

2 feet below mean sea level.

Large volumes of fresh water flow into Lake Pontchartrain from the tributary areas bordering the lake. 

These areas lie principally to the north of the lake, 

and extend into the southern parts of the State of 

Mississippi.

Saline water can enter Lake Pontchartrain from the 

Gulf of Mexico through Lake Borgne and the Rigolets, 

the principal connecting channel. Gulf waters that 

reach Lake Pontchartrain are reduced in salinity, 

however, owing to the fresh water from East Pearl 

River and other streams that discharge into Lake 

Borgne, and by West Pearl River which empties into 

the Rigolets.

Levees on the east bank of the Mississippi River 

prevent the natural discharge of Mississippi flood waters 

into Lake Pontchartrain. Since the construction of the 

Bonnet Carre spillway, water has been diverted from 

the Mississippi River three times through Lake Pontchartrain, with little effect on the elevation of the lake. 

A levee on the southern shore of the lake protects New 

Orleans from flooding. Because parts of New Orleans 

are as much as 3 feet below mean tide level and the 

greater part is below the high-water level of Lake 

Pontchartrain and the Mississippi River, it is necessary during heavy storms for pumps with a combined 

capacity of 16,500 mgd to pump water into Lake Pontchartrain. Along its northern shores, breakwater 

walls prevent beach erosion.

Lake Pontchartrain has ample facilities for recreational activities, which at present include bathing 

beaches on both the northern and southern shores, 

and boating and fishing. One large State park and 

several smaller parks are located on its northern 

shores. It is open to navigation by barge traffic from 

the Gulf of Mexico, Mississippi River, and Lake 

Maurepas.

The Greater New Orleans Causeway, 23 miles long 

across the middle of the lake extending from near 

Mandeville on the northern shore to New Orleans on 

the southern shore, is under construction. This 

causeway is expected to become a major link between 

New Orleans and regions north of Lake Pontchartrain.

Tributaries to Lake Pontchartrain

Lake Pontchartrain is fed by several streams that 

head in the hills of southern Mississippi and drain 

the area between the Mississippi River and the Pearl 

River basin.

Lake Pontchartrain drains about 4,200 square miles 

of land area. Lakes Pontchartrain and Maurepas have a 

combined surface area of 705 square miles. Of the 

4,200 square miles of drainage area, 2,433 square 

miles is gaged. The gaged tributaries to Lake Pontchartrain, principally the Amite, Tangipahoa, Tickfaw, 

and Chefuncte Rivers, drain a region abundant in water 

resources. The waters are of excellent quality and 

are not being utilized at present. Tributaries south of 

Lake Pontchartrain are probably poor as a source of 

water supply.

Discharge

The gaged inflow to Lake Pontchartrain is summarized in table 3. Runoff into Lake Pontchartrain from 

the gaged area of 2,433 square miles averages about 

2,520 mgd (2,826,000 acre-feet per year) or from the 

total drainage area of about 4,200 square miles runoff 

is estimated to average about 4,000 mgd (4,480,000 

acre-feet per year). Although it is beyond the scope of
20 WATER RESOURCES OF THE NEW ORLEANS AREA

1400

1200

1000

800

600

400

200

250 ppm or more of sediment 

during 60 percent of the year

10 20 30 40 50 60 70 80 

PERCENT OF TIME SEDIMENT CONCENTRATION EQUALED OR EXCEEDED THAT SHOWN

90 100

Figure 15. Cumulative frequency graph of sediment concentration, Mississippi River at Baton Rouge,

water year 1953.

Table 3. Summary of streamflow data for streams tributary to Lake Pontchartrain, Louisiana

Index

no.

(fig. 3)

15

9

11

8

6

Stream

apd

location

Amite River near

Denham Springs.

Tickfaw River at

Holden.

Natalbany River at

Baptist.

Tangipahoa River at

Robert.

Chefuncte River

near Folsom.

Drainage

area

(square 

miles)

1,330

242

79.5

646

95.5

"VoQT«C L C*dX 0

of

record

Sept. 1938 to

Sept. 1953

Nov. 1940 to

Sept. 1953

Aug. 1943 to

Sept. 1953

Oct. 1938 to

Sept. 1953

Jan. 1944 to

Sept. 1953

Discharge

Averace

(mgd)

1,320

253

82.7

742

125

Maximum

Rate

(mgd)

43,300

6,260

6,170

32,600

11,800

Date

"May 20, 1953

Mar',, 22, 1943

May 3, 1953

May 3, 1953

May 3, 1955

Momentary minimum

Rate

(mgd)

180

50

1.55

171

23.3

Date

November 1938.

Oct. 20 to Nov. 2,

and Nov. 5,: 1952

Oct. 22, 1952.

Several days in

Oct. 1939.

Several days in

Oct. 1952.
SURFACE WATER 21

100

80 

70 60 

d2=

LU30- 

0-20 

{£.

£

9 10 

LU -3 

U. -3

O

m 2-

o

ol.O 

oc 

< .8=

M .6 

0 .5 1 

.4 

.3 

.2 

80 

70 

60 

50 

40

LU .,- _i 30

5

g 20

<

g 10

>- 8 

^ 6

CC c

- 4

3 3

3 2

o

d

2 1.0 

? .8

is

fc -4

0 .3 

.2

0.1

*x

^

\

s

>

^v

>>,

XN, L

N.

N.

V

\ V

x.^^_

^^

DRAINAGE AREA, 133O SQUARE MILES

s

\

^v.

^>x^

Exampl<

^v,

^^.

,'

j: The daily flow equaled or exceeded 0.16 mgd 

square mile during 98 percent of the time c 

ing the water years, 1938-54

^^-^^

"^--^

y

\

\

\

- \

\

\

^= MB*M« ^BS=

-1 

-"

jer

0.01 0.050.1 0.2 0.5 1 5 10 20 30 40 50 60 70 80 90 95 

PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN

98 99 99.5 99.899.9 99.99

Figure 16. Duration curve of daily flows, Amite River near Denham Springs, water years 1939 54.

this report to present in detail all the flow records for 

the tributary area north of Lake Pontchartrain, flow 

characteristics for the Amite River, the largest of the 

gaged rivers, is given as an example.

Records for the gaging station on Amite River near 

Denham Springs are summarized in a duration curve, 

which is shown in figure 16. A duration curve indicates the percent of time, within the period of record, 

during which any given rate of flow was equaled or 

exceeded. The slope of the curve is a good indication 

of the storage within a basin, including ground-water 

storage; that is, the flatter the general slope of the 

curve, the lower the flood peaks and the higher the 

sustained dry-weather flow. A, comparison of flowduration curves for several streams in an area may 

be used to show which ones have the highest dryweather flow and are, therefore, the most dependable 

source of water.

The slope of the duration curve for Amite River 

(fig. 16) is almost flat indicating high sustained dryweather flow. As an example of its use, this curve 

shows that the flow of Amite River near Denham 

Springs equaled or exceeded 0.16 mgd per square 

mile, or a total of 213 mgd, for 98 percent of the 

time during the water years, 1939 54.

Although the above example indicates that during 

the period of record the flow of Amite River near 

Denham Springs was below 0.16 mgd per square mile 

(213 mgd) for only 2 percent of the time, further analysis of the records is required to determine the maximum number of consecutive days during which the

flow was below that rate. Such an analysis, for a range 

in rates of flow, is summarized in the curve shown in 

figure 17. This curve shows that the flow near Denham 

Springs was below 0.16 mgd per square mile (213 mgd) 

for a maximum of 40 consecutive days.

The Amite River drains about 1,800 square miles 

above its mouth at Lake Maurepas. If the flow from 

the ungaged area in the Amite River basin could be 

assumed to be proportional to the flow from the gaged 

area above the Denham Springs gaging station, then 

the above example may be extended to estimate the 

flow into Lake Maurepas during the water years 1939 

54. Preliminary studies, however, indicate that low 

flows are somewhat less per square mile in the southernmost parts of the areas tributary to Lake Pontchartrain than in the northernmost parts of those areas.

The flow of the Amite River combined with that of the 

Tickfaw River averages about 2,500 mgd (2,800,000 

acre-feet per year). This inflow represents most of 

the runoff into Lake Maurepas. The volume of water in 

Lake Maurepas at about 0.5 foot above mean sea level 

is about 570,000 acre-feet.

Low-flow yields of the streams tributary to Lake 

Pontchartrain appear to depend on the location of the 

drainage area. Streams draining the Recent alluvium 

of the Mississippi River south of the lake yield less 

water than streams incising the geologically older sands 

to the north (fig. 1). The principal tributaries all have 

highly sustained low flows, and an industry located on 

the northern shore of Lake Pontchartrain near the 

mouth of any of these streams would have dependable
22 WATER RESOURCES OF THE NEW ORLEANS AREA

851.0-

a.

o 

S .5-

Q.

-

3 -

-.0.2-

UJ

SQUAR GALLONS DAYPERMILLION INDISCHARGE, 

.....!- o .

ho i-.o cr>-P» GO en

 1 ^ 

 E

IH-M « ^

xample:

 MMBi

The daily flow of Amite River near Denham 

Springs was less than 0.16 mgd per square mile 

(213mgd) for not more than 40 consecutive day

== ^ ^»» == ^

^^^

,

s S

j

/

/

/

/

L 2 345678 10 20 1 2 345678 910 1

 v Y

CONSECUTIVE DAYS CONSECUTIVE MONTHS

LONGEST PERIOD OF TIME THAT FLOW WAS LESS THAN THAT SHOWN

Figure 17. Maximum period of deficient discharge, Amite River near Denham Springs, water years 1939 52.

fresh water supplies commensurate with the drainage 

area of the stream. The low-flow yield per square 

mile of the Tangipahoa River is the highest of the tributaries discussed here. Low-flow yields per square 

mile of the Chefuncte, Tickfaw, Amite, and Natalbany

100,000 

_80,000

Rivers are lower than that of the Tangipahoa River, 

in the order given.

The characteristic seasonal fluctuation of daily flows 

is shown in figure 18, which is a discharge hydrograph

JANUARY FEBRUARY MARCH APRIL JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER

Figure 18. Mean daily discharge of the Amite River near Denham Springs, 1946.
Table 4. -Mineral analyses and related physical measurements of surface water in the Lake Pontchartrain drainage basin and the Pearl River a

[Analyses in parts per million, except as indicated]

Date of 

collection

Discharge 

(cfs)

Temperature

OF)

Silica 

(SiOj)

Iron 

(Fe)

Calcium 

(Ca)

Magnesium 

(Mg)

Sodium 

(Na)

Potassium 

OQ

Bicarbonate 

(HCOj)

Sulfate 

(SOJ

Chloride 

(Cl)

Fluoride 

(F)

Nitrate 

(NOa)

Boron 

(B)

Dissolved 

solids

Hardne

as CaC

Calcium, 

magnesium

N

Chefuncte River near Folsom

Oct. 7, 1943 

Feb. 7, 1944 

Apr. 26 

Aug. 20, 1954

42 

118 

214 

43

59 

66 

78

"**7*r

12

"676*7* 

.09

~*"*T~*"

1.0

..........

.7

............ 

4.1

*""i**3 

.5

15 

10 

8 

10

"~T.*<r*

.6

4.0 

5.0 

4.0 

4.0

........ 

.1

........ 

.5

"**o76*5*

....... 23«

29

a 20 

a !6 

8

5

..

Tangipahoa River at Robert

Oct. 6, 1943 

Feb. 4. 1944 

Apr. 27 

Aug. 20, 1954 

Oct. 26

453 

909 

1,480 

328 

341

71 

60 

66 

79 

71

"*To**"

14 

15

"oTJe*

JLO 

.10

'""Ta*"

1.7 

1.6

**"**"679** 

.9 

.8

""**"**.**

4.6 

6.6

1.9 

1.0 

1.0

15 

19 

13 

16 

19

........

1.5 

1.6

4.0 

5.0 

3.0 

4.2 

4.0

'T's**

.0

"****T*o*

.2 

.2

*"'67o*4"

.............

38 

40

a 39 

a 36 

9 

8 

7

.

Natalbany River at Baptist

Oct. 6, 1943 

Feb. 10, 1944 

Apr. 27 

Aug. 20, 1954

11.0 

122 

78.4 

6.4

70 

59 

72 

80

"To****

19

"67*8* 

.25

 £4 

4.0

"**"*i7o"

1.7

"~£7'" 

10

*~**1J9 

1.5

24 

11 

12 

25

""*****T 

5.8

8.0 

5.0 

5.0 

9.2

"6T 

.1

* * * 

"*""72*

.5

Tickfaw River at Holden

Oct. 6, 1943 

Feb. 10, 1944 

Aug. 20, 1954

117 

305 

84

Oct. 8, 1943 

May 4, 1944 

Sept. 2, 1952 

Sept. 15 

Oct. 10 

Nov. 26 

Jan. 9, 1953 

Feb. 12 

Mar. 17 

June 26 

July 3 

Sept. 14 

Aug. 20, 1954

460 

1,190 

365 

380 

291 

402 

703 

1,330 

11, 500 

635 

1,130

"*"*340*"**

Aug. 26, 1952 

Sept. 10 

Oct. 7 

Nov. 25 

Jan. 6, 1953 

Feb. 10 

Mar. 10 

Apr. 21 

June 24 

July 21

1,675 

1,220

"*i742o"*** 

3,170 

11.370- 

24,500 

6,490 

3.070 

3,150

70 

60 

81

70 

72 

85 

81 

59 

58 

58

 gg*

82 

82

""***"**80*

..........

..........

13 

13 

11 

13 

13 

9.6 

7.0 

13 

9.9 

12 

13

"67*8 """XT' *oj .......... '""675*

14 

26

12

*"*"o"T"

4.0 

5.0 

4.0

**"""*o7f *'~**675*

Amite River near Denham Springs

0.43 

.10 

.26 

.45 

.47 

.66 

.48 

.40 

.21 

.53 

.25 

.14

2.9 

2.8 

1.2 

1.6 

1.6 

1.8 

2.1 

2.0 

1.7 

2.1 

1.6 

1.9 

2.0

1.6 

1.1 

1.5 

1.6 

1.0 

1.7 

1.1 

1.1 

1.1 

1.1 

1.3 

1.2 

1.1

5* 

4.1 

5.2 

5.3 

4.9 

5.9 

5.4 

3.0 

2.6 

5.8 

3.0 

6.3 

5.4

1.6 

3.2

.0 

1.0

*'"T.9 

1.3 

1.0

19 

15 

14 

15 

15 

16 

12 

11 

10 

14 

12 

18 

14

b 3 

1.9 

1.9 

1.3 

.5 

1.0 

2.2 

1.6 

2.5 

1.4 

1.9 

.8 

1.2

5.0 

5.0 

7.5 

6.5 

5.2 

7.2 

6.2 

4.2 

2.5 

6.0 

3.5 

6.0 

6.2

...........

.1

.3 

.0

.0 

 " """£ 

0.0 

1.0 

2.0 

1.0 

.2 

.5 

.5 

.8 

1.0

1.5 

1.5 

.8

.5

*"**67oT

**"67o*°

 * 

36 

64

..............

a 32 

a !8 

10 

17

..

a 26 

a 21 

7

..

""*o763*

..........

27 

40 

49 

39 

40 

40 

37 

28 

24 

38 

31 

40 

38

14 

12 

9 

11 

81 

12 

10 

10 

9 

10 

10 

10 

10

Pearl River near Bogalusa

84 

...............

50 

 "" " £5* 

...........

12 

13 

13 

11 

12 

8.0 

7.8 

11 

14 

12

0.03 

.01 

.06 

.17 

.63 

.45 

.28 

.63 

.05 

.12

2.3 

2.6 

2.2 

2.2 

2.7 

2.4 

3.2 

3.4 

4.2 

3.2

1.8 

1.5 

1.4 

1.2 

1.1 

1.2 

1.6 

1.3 

1.5 

1.2

6.6 

7.8 

8.0 

7.2 

6.5 

3.3 

3.1 

4.3 

5.2 

5.4

3.6 

.4

 * * 

1.6 

1.1 

1.3

9 

12 

12 

14 

12 

7 

4 

14 

16 

14

9.0 

8.6 

5.2 

2.7 

4.2 

6.3 

14 

6.1 

7.7 

5.8

8.5 

8.2 

9.5 

8.5 

8.0 

3.8 

2.8 

6.0 

6.2 

7.2

0.1

.5

.............

1.0 

.5 

.4 

.4 

.8 

1.0 

.2 

1.5 

1.0 

.5

""6706* 61 

49 

46 

40 

42 

29 

35 

43 

49 

44

13 

13 

11 

10 

11 

11 

15 

15 

17 

13

a By soap method, 

b By turbidity.
24 WATER RESOURCES OF THE NEW ORLEANS AREA

of Amite River near Denharn Springs for a typical calendar year. Other principal tributaries follow this 

same general pattern.

Quality of water

The waters from tributary streams north of Lake 

Pontchartrain are of good quality and generally would 

require a minimum amount of treatment for most uses 

(table 4.) However, the pH values indicate that some 

of these stream waters probably would be corrosive 

to water pipes or other metal surfaces; color and 

silica would be objectionable for some uses of the water. The waters are soft and contain only small 

amounts of dissolved solids, of which silica constitutes 

about one-third.

Daily determinations of chloride in the water of Lake 

Pontchartrain at Little Woods are made by the Corps 

of Engineers. The approximate monthly maximum, 

minimum, and average chloride content of the lake 

water at Little Woods from 1947 to 1954 are given in 

table 5. The data in this table indicate that the chloride concentration is generally higher from August 

through December than during the remainder of the 

year. The chloride content of the water is not constant 

for any given point on the lake. The tributaries to 

Lake Pontchartrain contribute water very low in

dissolved solids. Undoubtedly the chloride concentration 

near the mouths of the tributary streams is considerably 

less than was found at Liitle Woods. Lake Pontchartrain 

is unsuitable as a source of potable water because of the 

inflow of saline water from the gulf.

The salinity of Lake Maurepas is probably less than 

that of Lake Pontchartrain because it is less likely to 

be affected by salt water from the gulf, and it is affected more by dilution from streams entering from the 

north and west.

An analysis of a single sample of the water of Lake 

Maurepas at Pass Manchac at the railroad bridge, collected on November 5, 1953, is shown below:

Parts per million 

Constituent (except pH, color,

and turbidity) 

Iron (total)............................................ 0.7

Chloride (Cl)........................................... 1,130

Dissolved solids..................................... 2,240

................. 426

................. 405

................. 20

................. 6.2

................. 30

................. 16

................. 9.3

Ignition loss....................

Hardness (as CaCOa)........

Alkalinity (as CaCOs).......

pH.................................

Color.............................

Turbidity........................

Free carbon dioxide (CO2).

Table 5. Approximate maximum, minimum, and average chloride concentration in water from Lake Pontchartrain,

Little Woods, La.

[Analyses made by Corps of Engineers; results in parts per million]

Year

1947

1948 

1949 

1950 

1951 

1952 

1953 

1954

Concentration

Maximum 

Minimum 

Average

Maximum 

Minimum 

Average

Maximum 

Minimum 

Average

Maximum 

Minimum 

Average

Maximum, 

Minimum 

Average

Maximum 

Minimum 

Average

Average

January

1,050

400

648

2,200 

1,000 

1,760

1,000 

500 

729

1,900 

1,200 

1,500

2,500 

1,750 

2,080

2,450 

2,000 

2,170

4,000 

2,750 

3,580

1,000

700

781

February

650

400

532

2,100 

750 

1,140

750 

400 

493

1,200 

700 

1,100

1,750 

1,500 

1,580

2,400 

1,750 

2,120

3,750 

2,550 

3,440

800

600

757

March

650

350

390

950 

500 

634

500 

400 

485

700 

50 

158

2,000 

1,250 

1,620

2,000 

1,500 

1,910

3,250 

2,250 

2,780

1,000

700

865

April

350

200

280

750 

500 

651

500 

200 

375

200 

50 

95

1,750 

1,000 

1,310

2,100 

1,500 

1,850

2,500 

1,700 

2,220

1,000

900

957

May

700 

500 

583

400 

150 

290

150 

50 

100

1,000 

750 

865

1,800 

1,500 

1,690

2,500 

1,300 

2,140

1,300

1,000

1,150

June

700 

600 

634

450 

200 

281

250 

50 

110

1,250 

850 

975

1,800 

1,500 

1,620

1,300 

1,200 

1,280

1,600

1,000

1,440

July

2,200 

850 

1,280

300 

150 

242

500 

150 

221

1,250 

750 

1,080

2,800 

1,500 

2,180

1,600 

1,000 

1,410

2,000

1,000

1,640

August

2,900

250

660

1,450 

900 

1,200

300 

150 

216

1,750 

350 

573

2,000 

1,000 

1,360

6,000 

2,800 

3,210

1,500 

1,100 

 1,330

7,500

1,800

September

3,650

1,000

1,590

3,100 

1,000 

1,770

2,300 

250 

1,150

3,700 

1,750 

2,830

3,600 

1,400 

2,160

5,950 

3,700 

4,240

3,000 

1,400 

1,820

October

4,250

3,000

3,550

2,000 

1.4CO 

1,560

2,300 

1,050 

1,610

6,000 

1,500 

3,230

3,600 

2,650 

2,840

5,200 

3,900 

4,240

2,600 

1,900 

2,140

November

5,250

2,000

2,700

1,700 

950 

1,450

1,500 

1,050 

1,340

3,500 

2,500 

2,570

2,750 

2,150 

2,440

4,750 

4,250 

4,610

3,700 

1,600 

2,090

December

3,100

1,500

2,200

1,400 

800 

1,180

3,000 

1,200 

1,640

2,650 

2,250 

2,490

2,700 

2,000 

2,390

5,500 

3,750 

4,600

2,000 

1,200 

1,630
GROUND WATER 25

Pearl River and Lakes 

Pearl River

Pearl River rises in the east-central part of Mississippi and flows southward for 485 miles to its 

mouths. The lower 116 miles is the boundary between 

Mississippi and Louisiana, and the basin adjoins the 

tributary drainage area of Lake Pontchartrain. About 

50 miles above its mouths, Pearl River divides into 

East Pearl River, which flows into Lake Borgne, and 

West Pearl River, which flows into the Rigolets, the 

principal outlet of Lake Pontchartrain.

The Pearl River, at its mouths, drains an area of 

about 8,700 square miles, of which 7,840 square miles 

is gaged. Records of daily stage and discharge are 

available since October 1938 for Pearl River at Bogalusa (6,630 square miles). The average daily flow for 

15 years at Bogalusa is 6,060 mgd. The highest daily 

and momentary flow was 38,800 mgd on January 25 

26, 1947. The lowest daily and momentary flow was 

737 mgd from October 22 to November 2, 1952.

Analyses of water samples collected monthly from 

the Pearl River near Bogalusa show the water to be 

low in dissolved solids. (See table 4.) The principal 

constituents in the water are sodium chloride and 

calcium bicarbonate. The observed dissolved solids 

for the period of sampling ranged from 29 to 6.1 ppm. 

The pH values ranged from 5.3 to 7.0 thus indicating 

that the water would be somewhat corrosive to metal 

surfaces.

Lakes

Lakes Des Allemands and Salvador are two interconnected coastal lagoons existing as arms of the sea, 

in the swamps of the lower Mississippi River Delta.

Lake Des Allemands contains about 79,000 acre-feet 

and Lake Salvador contains about 294,000 acre-feet of 

water at about mean sea level. Although no specific 

information is available as to salinity in these two 

lakes, the water is probably moderately saline, and 

Lake Des Allemands is probably less saline than Lake 

Salvador.

GROUND WATER 

Geology

The New Orleans area lies within the Gulf Coastal 

Plain and is immediately underlain by unconsolidated 

river alluvium of Recent and Pleistocene (Quaternary) 

age. The Recent river alluvium lies at the surface in 

the greatest part of the area. These deposits, which 

immediately overlie the Pleistocene deposits, range 

in thickness from about 30 to 120 feet and were laid 

down in a fresh-water or brackish-water environment 

(Fisk, 1947, p. 59-63). At the top are clay and silt 

beds that are high in organic content; these grade 

downward into alternating marine beach sand and clay 

containing scattered shell beds and sand and silt 

lenses. The deposits of Pleistocene age are exposed 

at the surface north of Lake Pontchartrain. These 

deposits consist mostly of oxidized clay, silt, and 

sand and some local gravel beds. North of Lake 

Pontchartrain, where the deposits of late Pleistocene

age dip southward beneath the alluvium of the Misfeissippi Alluvial Plain, they form a low southwestwardfacing scarp which trends southeastward (fig. 1).

South of the scarp the Pleistocene sediments were 

deposited as part of a great deltaic mass in a freshto marine-water environment. The sediments that 

form the upper part of the Pleistocene in this area 

consist of lenticular beds of clay, silt, and sand and 

many scattered shell beds. The upper part of the 

Pleistocene deposits is well oxidized and more indurated than the overlying Recent alluvium (Fisk, 1947, 

p. 59 63). The lower sand beds in the Pleistocene deposits are more continuous and areally extensive. The 

southerly dip of the beds is irregular, but successively 

deeper beds appear to have greater dips. North of 

Lake Pontchartrain, sediments of Miocene age lie 

beneath the Pleistocene deposits, at a depth of about 

2,000 feet below sea level (Fisk, 1944, fig. 69). The 

Miocene deposits are the oldest in this area that contain 

fresh water. In the industrial district these deposits 

contain saline water.

The Mississippi Alluvial Plain is a valley that was 

formed during the final cycle of the world-wide glaciation. About 100,000 years ago, during the last glacial 

stage, sea level was several hundred feet lower than 

at present and the Mississippi River valley became 

deeply incised within the sediments of the Gulf Coastal 

Plain (Fisk, 1944, fig. 75). With the subsequent 

rise in sea level the river meandered throughout the 

valley, filling it with sand, silt, and clay and forming 

the present surface.

Geologic structures, associated chiefly with the Gulf 

Coast geosyncline, are important in the accumulation 

of oil and gas and have an effect on the occurrence of 

fresh ground water in the area. The exact location of 

most of the structures is unknown; however, in the 

latitude of Lake Pontchartrain they are believed to 

have caused a sharp decrease in the depth of occurrence 

of fresh ground water within short distances. Further 

investigation would be necessary to determine their 

detailed relationship to the occurrence of fresh water 

in the area.

As described by Russell (1936, p. 6 9), the migration 

of the mouth of the river along the coast concentrated 

sediments in a belt parallel to the coast and along the 

axis of the Gulf Coast geosyncline. The weight of these 

deposits probably caused the subsidence of the coastal 

area and an uplift of the land to the north. The subsidence is evident by the drowning of depressions in the 

area which are typified by Mississippi Sound and Lakes 

Borgne, Maurepas, and Pontchartrain. The subsidence 

of the area is still active. For example, an Indian village has subsided to 14 feet below sea level at the north 

end of Lake Pontchartrain. Moreover, Fisk (1944, p. 

34) reports the active subsidence of benchmarks, 

buildings, cemeteries and engineering works in the 

New Orleans area.

The principal water-bearing sands in the New Orleans 

area crop out or are near the surface north of Lake 

Pontchartrain where they receive recharge primarily 

from local precipitation. In these areas the sands are 

incised by streams and may either supply water to the 

streams during periods of low flow or be recharged 

when the stream level is above the water table. In 

these areas, where there are no impervious layers
26 WATER RESOURCES OF THE NEW ORLEANS AREA

overlying the sand, the ground water is under watertable conditions. As the water moves southward 

toward the city of New Orleans it passes beneath impervious layers of clay and becomes confined under 

artesian pressure. Thus, the water in all the princ'pal water-bearing sands in the New Orleans industrial ^rea occurs under artesian conditions.

Any rock stratum that yields sufficient quantities of 

water to make it a usable source of supply is called 

an aquifer or a water-bearing unit. The amount of 

water that may be obtained from an aquifer is dependent principally on its ability to transmit and store water. The capacity of an aquifer to transmit water is 

a function of its permeability and thickness. Thus, 

the yield of wells is potentially greater in areas of 

maximum sand thickness and permeability.

The movement of ground water from areas of recharge to areas of discharge generally is unlike 

surface-water flow, in that it is not confined to definite channels. The movement of water through an 

areally extensive bed of sand is retarded by the small 

size of the pore spaces between the sand grains. Consequently, the natural rate of ground-water movement 

is measured in feet or fractions of a foot per day, 

much less than the ordinary velocity of streams.

Water-Bearing Units 

General Features

As shown by geologic cross sections (pi. 1), the 

deltaic sediments underlying the New Orleans area 

include sand beds which, in the northern part of the 

area, contain fresh water to a maximum depth of 

about 3,000 feet below the land surface. The generalized geologic cross section D-D' (pi. 1) shows the 

depth to the fresh-water salt-water interface from 

the northern part of Lake Pontchartrain southward 

through the industrial district. Between the northern 

and southern shores of Lake Pontchartrain the interface rises abruptly from a maximum depth of 3,000 

to 900 feet. The abrupt change in depth may be caused 

by structures such as faults which inhibit the flushing 

of the saline water from the deeper sand beds.

Additional data on the aquifers are needed, as most 

of the sands are similar in appearance, and, owing to 

their mode of origin, may lens out abruptly. However, 

the available information indicates that the correlations shown on the sections in plate 1 are approximately correct.

In general, fresh water from the principal sands is 

of the soft sodium bicarbonate type. As shown in 

figure 19 the quality of the water varies greatly within 

the same sand aquifer, depending upon the location of 

the supply well. The cause of this variation in mineralization with location is not the result of any known 

surface contamination, but is probably the result of 

saline-water movement within the aquifer, in part in 

response to pumping. Southward from the city of New 

Orleans the mineralization of the water increases, 

and it is likely that pumping for a long period may 

cause migration of saline water northward toward 

areas of heavy withdrawals. Water from most wells 

just south of Lake Pontchartrain has a low chloride 

content, whereas southward in the vicinity of Gretna

the water generally has a high chloride content. The 

deeper sands come to the surface to the north, probably in the State of Mississippi, where they receive 

their recharge. The dip or slope of these sands is 

gulfward at a rate of 30 50 feet per mile (La. Dept. 

Public Works 1954) South of Lake Pontchartrain, 

beneath the New Orleans industrial district, are four 

principal water-bearing sands above a depth of about 

1,200 feet (pi. 1, A-A'). Each sand dips or slopes 

gulfward, and the depth to the top of each sand becomes 

greater in that direction. The areal extent of each 

principal aquifer within the New Orleans industrial 

district and its correlation from well to well were determined by a study of driller' logs, electrical logs, 

and hydrologic data. For convenience, the different 

sands are discussed in this report according to their 

depth of occurrence in the New Orleans industrial 

district.

Ground water for industrial and commercial uses in 

the New Orleans industrial area is obtained primarily 

from the "200-, " "400-, " and "700-foot" sands. The 

principal fresh-water bearing sand is the "700-foot" 

sand; however, the "400-foot" sand supplies most of 

the ground water used for industrial purposes in northern St. Charles Parish, where the "700-foot" sand 

contains highly mineralized water. The quality of 

ground water in each sand varies throughout the report 

area.

The temperature of water within a given sand is 

comparatively uniform from place to place and through 

out the year, generally fluctuating only a few degrees. 

That of water at a depth of a few tens of feet is about 

the same as the mean annual air temperature. At 

greater depths the temperature increases in the New 

Orleans area at a rate of 1°F for about each 90 feet of 

increased depth. Thus the observed temperature of 

the water from about 200 wells in the New Orleans area 

ranged from 69° at 20 feet to 91° at about 2,500 feet. 

These ranges occurred in the Florida Parishes north 

of Lake Pontchartrain.

North of Lake Pontchartrain, in St. Tammany 

Parish, wells screened in sands between 60 and 2,000 

feet below the land surface yield fresh water. The 

wells screened in the deeper sands generally are 

under sufficient artesian pressure to flow. The recorded artesian flows range from 1 to 450 gpm depending chiefly on the diameter of the well and the artesian 

pressure.

"200-Foot" Sand

The "200-foot" sand is the shallowest of the important 

water-bearing sands that yield water to wells within 

the industrial district. It is of late Pleistocene age. 

As shown in plate 1, the "200-foot" sand is irregular 

in areal extent, as it thickens and thins and pinches out 

abruptly. However, the sand generally ranges from 

about 30 to 150 feet in thickness. It has a slight southerly regional dip of about 8 to 10 feet per mile and 

generally increases in thickness from north to south. 

In the western part of the industrial district in St. 

Charles Parish the "200-foot" sand is relatively continuous, as shown in cross section C-C', and is separated from the "400-foot" sand by a cleiy bed which 

pinches out west of Norco (section B-B'j. Thus, the 

"200-foot" and the "400-foot" sands in that areabecome
GROUND WATER 27

EXPLANATION

Sodium and 

potassium

Chloride, fluoride, 

and nitrate

Sulfate

Bicarbonate

Figure 19. Graph showing chemical characteristics of water from wens in the New Orleans area.

one hydrologic unit. East of well 4 in section A-A' 

and north of well 37 in section E-E', the "200-foot" 

sand appears to pinch out completely. The electrical 

logs directly east of well 5 begin at depths greater 

than the "200-foot" sand, and additional information 

would be necessary to show a definite pinch out. However, there are no water wells in this area screened 

at depths that would indicate the presence of the "200- 

foot' sand. Logs of wells in the southern part of Lake

Pontchartrain show that the "200-foot" sand pinches 

out south of the lake and does not crop out in the bed 

of the lake.

The "200-foot" sand is medium to very fine grained, 

and there is only a small percentage of coarse grains 

and silt. In some areas drillers' logs indicate the 

presence of some coarser material including streaks 

of lignite, shell beds, and cypress stumps. The sand
28 WATER RESOURCES OF THE NEW ORLEANS AREA

Table 6. Summary of ground-water pumpage, in million gallons a day, from each sand in the New Orleans

industrial area, 1953

Parish

Orleans..... ...............................................

Plaquemines..............................................

St. Bernard...............................................

St. Charles................................ ...............

Total......................................................

Aquifers

" 260-foot"

0.40 

.40

0.80

"400-foot"

0.50 

.05

19.60

20.15

"700-foot"

10.00 

23.00

2.00 

6.00

41.00

"1,200-foot"

0.05

0,05

Total

10.90 

23.50

2.00 

25.60

62.00

grains range from angular to subangular. The color 

is generally grayish-orange to pink.

Yield of wells

Records show only 4 industrial wells tapping the 

"200-foot" sand in the New Orleans area. The yield 

of these wells, which have diameters of 6 to 10 inches, 

ranges from 175 to 350 gpm and averages about 275 

gpm. About 15 domestic and stock wells are screened 

in this sand and are used mostly for laundering, washing, and emergency supplies. Further data will be 

necessary to determine the possibility of obtaining 

greater quantities of water from the "200-foot" sand; 

however, this sand has not been developed extensively 

to date.

Water-level fluctuations

A water well screened in the "200-foot" sand in 

southwestern New Orleans flowed saline water 1 foot 

above the land surface at a rate of 12 gpm in 1904 

(Harris, 1905, p. 43). At the present time some wells 

in this sand still flow; however, in a few areas the water level has declined to about 20 feet below the land 

surface. Unless withdrawal from this sand is increased, future decline of water levels probably will 

be small.

Withdrawal

The average daily withdrawal from the "200-foot" 

sand in the industrial area is 0. 8 mgd (table 6), or 

about 292 million gallons annually. The greatest concentration of pumping-occurs in the north-central and 

southwestern parts of Jefferson and Orleans Parishes, 

respectively. Most of the water is used for industrial 

and cooling purposes, and the pumpage is about the 

same in winter and summer.

Quality of water

Chemical analyses of water from 9 wells screened 

in the "200-foot" sand are given in table 8, together 

with analyses of water from the other sands. These 

samples were selected to show the range in constituents and general type of water available from each 

sand. Partial and complete chemical analyses of

samples taken from 19 wells indicate that the "200- 

foot" sand yields a highly mineralized sodium bicarbonate chloride water having a hardness ranging from 

42 to about 840 ppm. In general as the chloride content 

increases the hardness also increases. The chloride 

content of the samples ranged from 165 to 2,180 ppm. 

The silica content ranges from 26 to 42 ppm, and 

treatment may be required before the water can be 

used by some industries. Most of the samples were 

high in dissolved solids, ranging from 839 to 4,230 

ppm. The pH of all samples collected from wells 

screened in the "200-foot" sand ranged from 7.4 to 

7.8. The observed total-iron content is as much as 

1.9 ppm. The temperature of the ground water is 

about 71°F and generally fluctuates only a few degrees 

during the year. Owing to the moderate salinity of the 

water in this sand in some areas, the water is not 

suitable for some industrial and domestic uses. In 

general, the water is relatively fresh north of the Mississippi River and becomes increasingly saline southeastward, as indicated by the chloride content of water 

from well StB-9 near the village of St. Bernard (see 

table 7, wells Sc-57 and Sc-61).

"400-Foot" Sand

Within the New Orleans industrial district, the "400- 

foot" sand is more continuous in areal extent and more 

uniform in thickness than the "200-foot" sand. The 

thickness ranges from a maximum of about 250 feet in 

western St. Charles Parish to a minimum of about 40 

feet northward in the vicinity of Lake Pontchartrain. 

The average thickness of this sand is about 140 feet. 

Plate 1 indicates that the "400-foot" sand pinches out 

near the southern shoreline and does not crop out in 

the lake. Toward the southern part of the area, the 

"400-foot" sand breaks up into thin stringers and loses 

its identity. The sand is usually separated from the 

"200-foot" and "700-foot" sands by shale and clay beds 

containing interbedded sand stringers. The regional 

dip or slope is gulfward at about 5 feet per mile, as 

shown by the geologic cross section C-C'.

The sand is medium to fine grained and the material 

is less uniform in grain size than that from the "200- 

foot" and "700-foot" sands. It consists largely of 

yellowish quartz grains and has a yellowish-gray color, 

and the grains range from angular to subrounded. Thin 

beds of shells and of coarser sand an<£ gravel are present at some places.
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C5 3 

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well of Depth 

feet) (in 

of Date 

collection

Silica ) 2 (Si0

iron Total 

(Fe)

Calcium 

(Ca)

Magnesium 

(Mg)

Sodium 

(Na)

Potassium 

(K)

Carbonate ) 3 (C0

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Sulfate ) 4 (S0

Chloride 

(Cl)

Fluoride 

(F)

Nitrate ) 3 (N0

Dissolved 

solids

as Hardness 3 CaCO

Percent 

sodium

Specific 

conductance 

(micromhos 

25°C) at 

Color

PH

in million as partser Analyses except indicated]

 Table and7.Chemical related inofthe area measurements waterNew Orleans analyses physical ground

ONflOHD H31VM 
Table 7 Chemical analyses and related physical measurements of ground water in the New Orleans area 

uses

'well no.

01 

^ £T~

*!

£ c CL'^

&

°l

4) O

a S

0 9 

o

rt "^, 

0 £? 

^ O

cn£.

c 

o

S*

'rt oT

s b"o 

ECalcium (Ca) Magnesium (Mg) 6

3'e? 

%& 

O^

cn

Potassium 

(K)

1 Carbonate 

(C03)

Bicarbonate 

(HCO3)

<D

a "51 

SO 

3 en en 

Chloride (Cl)

Fluoride 

(F)

<y .

?p 

 1*

Dissolved 

solids

"700-foot" sand Continued

Or-37

Or-57

Or- 100

Or-61

Tf-7

Jf-24-A

Jf-34

Jf-36

Jf-37

790

ono

580

670

700

708

807

454

688

Oct. 12, 1951

Apr. 1, 1950

Jan. 13, 1955

Oct. 12, 1951

May 19, 1942

May 30, 1950

Jan. 14, 1955

Oct. 12, 1951

Jan. 14, 1955

26

29

36

2a

28

36

32

41

36

0.19

.25

.08

.03

.30

.45

.08

.16

35

4.0

2.0

5.6

2.7

3.2

42

5.2

3.2

20

1 Q

1.7

3.8

1.1

1.4

20

4.3

1.4

706

220

233

139

132

1,220

208

205

2.0

235

2.2

.8

1.2

7.6

13

.8

2.2

0

0

0

0

0

0

0

478

C 500

385

478

277

275

442

456

350

12

5.0

.1

.5

1.2

1.4

.2

.2

.3

940

80

131

96

64

60

1,770

76

128

0.7

.4

1.0

.6

.3

.7

1.2

.7

1.0

.2

.00

3.0

1.0

1.8

.0

.5

.00

1,980

626

590

608

382

384

3,320

572

549

"1,200-foot" sand

Or-10

Or-75

1,248

760

Sept. 11, 1941

Jan. 13, 1955 38

 

0.10 3.2 1.4 378 i.5 i 0

322

350

1.0

.2

lX200

396 0.5 0.0 976

a Soap hardness.

b Includes equivalent of 35 ppfln of carbonate (COs).

c Includes equivalent of 14 ppm of carbonate (COs).
GROUND WATER 31

Yield of wells

About 20 industrial wells tap this aquifer, yielding 

250 to 2,400 gpm. The average discharge is about 700 

gpm to wells that are 8 12 inches in diameter and are 

completed with about 80-90 feet of screen. The reported specific capacities of 11 wells screened in the "400- 

foot" sand range from 6.1 to 71 gpm per foot and average about 30. The information on yields and the relatively slight decline in artesian head for long periods 

indicates hat the '400-foot" sand is /e-y prolific, 

but the available hydrologic data to determine the full 

capabilities of the aquifer are meager.

Water-level fluctuations

The extent to which the water level in the "400-foot" 

sand has declined varies greatly in the New Orleans 

industrial district, depending upon the local rate of 

pumping. Records show that a well ending in this sand 

flowed at a rate of 6 gpm in 1903 (Harrisj 1905, p. 

43), and, in areas where there is very little pumping, 

wells tapping this aquifer will still flow small quantities of water.

The upper line on figure 20 shows the general decline in artesian head of the "400-foot" sand in northern St. Charles Parish, which has averaged about 1 foot 

per year since 1903. It should be noted that there was a 

gradual drop between 1903 and 1943 and then a sharp 

decline between 1943 and 1949. In those 6 years the 

average decline was about 5.3 feet per year, and the 

artesian head declined to about 74 feet below the land 

surface. Since 1949, pumping from the "400-foot" 

sand has decreased slightly, and the artesian head 

recovered about 8 feet, to about 66 feet below 

the land surface by 1953, at which time the well in 

which observations were being made was destroyed. 

Figure 21 shows the relationship of pumping to water 

levels in wells screened in the "400-foot" sand in 

northern St. Charles Parish between 1943 and 1953. 

This graph shows that the water levels declined from 

194^3 to 1950 in response to increasing rates of

withdrawal and from 1950 to 1953 recovered as withdrawals decreased. To the east, in Jefferson and 

Orleans Parishes, the water levels in the "400-foot" 

sand are probably much nearer the land surface, as 

few wells are screened in this aquifer there.

Withdrawal

Pumping from the "400-foot" sand is approximately 

uniform throughout the year. As shown by table 6, the 

average withdrawal from the "400-foot" sand is about

20 mgd, which amounts to about 7,300 million gallons 

annually. About 98 percent of the total pumpage occurs 

in the northern part of St. Charles Parish, where the 

water is used chiefly for industrial cooling.

Data in table 6 indicate that there is very little pumping from the sand outside St. Charles Parish. Figure

21 shows an increase in pumping of about 6.2 mgd occurred in the "400-foot" sand between 1943 and 1953.

Quality of water

A total of 30 partial and complete chemical analyses 

of water from wells indicate the "400-foot" sand generally yields a highly mineralized sodium chloride bicarbonate type of water. Chemical analyses of water from 

7 wells screened in the "400-foot" sand in St. Charles 

and Jefferson Parishes are presented in table 7.. The 

samples ranged in hard ess from 90 to 3,480 ppm, 

depending upon the location of the well. A well (Jf-33) 

in Westwego, screened in the "400-foot sand, yielded 

water having a chloride content of 7 270 ppm and a 

hardness of 3,480 ppm. To the west, in northern 

Jefferson and St. Charle-s Parishes, the water from 

this sand is less saline, as indicated by the chloride 

content which ranges from 245 to 1,410 ppm. Most of 

the analyses indicate that "the water is high in dissolved 

solids, ranging from 1,050 to 12,300 ppm. In all samples of water collected from the "400-foot" sand for 

which the pH has been determined, the pH ranged from 

7.0 to 8.8. The silica content ranges from 29 to 40 ppm

20

40

60

I 80

100

"400-foot" sand

1900 1910 1920 1930 1940 1950

"700-foot" sand

1900 1920 1930 1940 1950

Figure 20. Graph showing the general decline in artesian head, in feet, with reference to land-surface datum in

the principal aquifers in the New Orleans area.
32 WATER RESOURCES OF THE NEW ORLEANS AREA

Figure 21. Graph showing the relationship of pumping to water levels in wells screened in the "400-foot" sand in

northern St. Charles Parish.

and the total-iron content usually ranges from 0 to 

0.64 ppm. The average temperature of water from 

this sand is about 73°F.

The water is used mostly for cooling and is not palatable in some areas.

"700-Foot" Sand

The "700-foot" sand is the most important aquifer 

within the New Orleans industrial district. As is

shown by the geologic cross sections in plate 1, this 

aquifer is continuous throughout the New Orleans area. 

One of the outstanding markers used in selecting the 

top of the "700-foot" sand, in differentiating it from 

the sand stringers overlying it, is a thin clay layer 

ranging from 10 to 70 feet in thickness and averaging 

about 10 to 20 feet throughout most of the area. There 

are usually one or more sand stringers, ranging from 

about 30 to 100 feet in thickness, between the "400- 

foot" and "700-foot" sands. The base of the "700-foot" 

sand also is separated from underlying sand beds by a 

clayof variable thickness. This aquifer is considered to
GROUND WATER 33

be of Pleistocene age, because, according to structure 

maps by Lowman (1949, p. 1190) and Morgan (1953), 

it is above the basal deposits of Pleistocene age.

The "700-foot" sand appears to be relatively uniform 

in thickness (pi. 1). The average thickness of this 

sand is about 200 feet; however, locally it may range 

from 90 to 320 feet. As shown on cross sections A-A' 

and B-B', the thickness is more uniform along an eastwest line roughly parallel to the Mississippi River than 

from north to south through the industrial district. The 

sand has a regional southerly dip of about 10 feet per 

mile. The sand crops out north of Lake Pontchartrain, 

where it receives its recharge primarily from rainfall. Present geologic information and quality-of-water 

data indicate that this sand is not hydraulically connected with Lake Pontchartrain. It is separated from 

the lake by several clay layers.

The material of the "700-foot" sand is fine grained 

and very uniform in texture. The sand is usually light 

olive gray; however, some of the grains have yellowish stains. This sand is composed of angular to subrounded quartz grains and contains thin layers of shell 

beds in some local areas.

Yield of wells

The "700-foot" sand is the principal aquifer, owing 

to its large yield to wells and the relatively low chloride content of the water in most of the industrial 

district. At present, about 55 large-diameter industrial wells tap this sand, yielding 250 to 2,000 gpm and 

averaging about 500 gpm.

The specific capacity of wells tapping this sand 

ranges from 8 to 67 gpm per foot and averages 30. 

Most of the wells are equipped with deep-well turbine 

pumps. Pump bowls are set between depths of 100 

and 250 feet below the land surface, depending on the 

water level, yield, and specific capacity of the well.

Water-level fluctuations

A general decline in artesian head averaging 1.8 feet 

per year has occurred in the "700-foot" sand in New 

Orleans since 1903 (fig. 20). The artesian head in 

the "700-foot" sand in 1903 was about 3 feet below the 

land surface (Harris, 1905, p. 43) and declined to 94 

below land surface by 1954. A gradual decline in artesian head occurred at a rate of 1 foot per year between 

1903 and 1940. After 1940, a sharp decline in artesian 

head occurred at a rate of about 4 feet per year. Since 

1945 water levels in the "700-foot" sand in southwest 

Orleans Parish have declined almost continuously, as 

shown by figure 22. The water-level graph presented 

in figure 22 shows a general decline in water levels 

due to increased pumping during the summer and a 

recovery of the artesian head during the winter. The 

recovery of water levels during the winter is generally less than the decline in the summer, resulting in 

a general decline for a long period. The lowest water 

level on record in southwestern Orleans Parish occurred during the period of heavy pumping in 1953, 

when it was 103 feet below the land surface.

The relationship of pumping to water-level decline in 

northern St. Charles Parish from the "700-foot" sand 

is shown in figure 23. Because fewer wells are screened

Figure 22. Graph showing water-level fluctuations in wells screened in the "700-foot" sand in New Orleans area.
34 WATER RESOURCES OF THE NEW ORLEANS AREA

Pi/mpage from "700-foot" sand in the northern 

St Charles Parish industrial area

LEVEL, WATR INFEETBELOW LAND-SURFACE DATUM8 5£

Sc-9

*M\A

 ys^-

V^^ ^

r_r/ ^\

 - -y^__ysA______^

Figure 23. Graph showing the relationship of pumping to water levels in wells screened in the "700-foot" sand in

northern St. Charles Parish.

in the sand in that area, the aquifer is not pumped as 

heavily there as it is in the eastern part of the industrial district. Water-level declines in the past 5 years 

have been at a rate of about 5 feet per year, reaching 

a low level of 38 feet below the land surface.

Withdrawal

The average ground-water withdrawal from the "700- 

foot" sand in the New Orleans industrial district is 

about 41 mgd, or about 14,900 million gallons annually. 

The average daily summer pumpage is about 1.2 times 

greater than the average daily winter pumpage. About 

56 percent of the withdrawal is in the western part of 

Orleans Parish, 24 percent in Jefferson Parish, 15 

percent in St. Charles Parish, and 5 percent in St. 

Bernard Parish.

Quality of water

The "700-foot" sand yields fresh water to wells in 

most of the northern part of the New Orleans industrial 

district and in eastern Orleans Parish. Generally, in 

the southern and western parts of the industrial district the water from the "700-foot" sand is too highly 

mineralized to be suitable for human consumption. 

The geologic cross sections show the fresh-water 

salt-water interface in the "700-foot" sand.

An isochloride map (fig. 24) of the "700-foot" sand 

in New Orleans and vicinity shows the distribution of 

chloride by means of lines of equal chloride content. 

This map is based upon 40 field tests of water collected from wells within a 1-month period. The general 

shape of the isochloride lines on this map indicates 

that concentrated pumping in this area has lowered the 

water levels sufficiently to cause salt water to move 

updip from the south. In comparing this recent isochloride map with similar data obtained in 1942, there 

appears to have been a slight movement of salt water

updip to the north in the Algiers area. However, there 

has been a decrease in chloride content in the Gretna 

area, owing to the abandonment of some industrial 

wells. In the future, as in the past, the movement of 

water and variations in chloride content probably will 

change with rates of pumping. There is a high chloride 

concentration in the Norco area, ranging from about 

1,000 to 2,200 ppm. As few data are available on the 

"700-foot" sand in that area, movement of high-chloride 

water on a regional basis is difficult to determine. 

However, a sampling program should be maintained to 

determine movement of saline water there.

The quality of water in the "700-foot" sand varies 

considerably, as shown by 11 complete chemical 

analyses in table 7, and 62 supplementary partial and 

complete analyses (not given in this report). Water 

from wells tapping this aquifer is a soft sodium bicarbonate type except in areas of high chloride concentration, where the water is extremely hard. The results 

of analyses show the concentration of dissolved solids 

generally is less than 1,000 ppm. The pH generally 

ranged from 7.6 to 8.6.

A small amount of hydrogen sulfide has been reported 

in the water from some wells, and locally the water is 

high in color. The color ranges from tight to dark 

amber and is probably due to the organic material present in the sand. Color greater than 20 units makes the 

water undesirable for-public supply and for some industrial uses.

"1,200-Foot" Sand

The deepest water-bearing sand tapped by wells in 

the New Orleans industrial district is the "1,200-foot" 

sand, which usually yields salt water. The top of this 

sand lies at about 1,150 feet below sea level in downtown New Orleans, and ranges in thickness from about 

40 to 180 feet. In some places the sand is lenticular 

and contains interbedded clay and shale. A driller's 

log (Harris, 1905, p. 42) shows the sand is overlain
GROUND WATER 35

EXPLANATION

- i 250 

Isochloride line joining points at 

which aquifer yields water having 

specified concentration of chloride 

Number shows chloride content 

in parts per million

Supply well from which water 

sample was collected

4 Miles

Approximate scale 

Figure 24. Isochloride map of the "700-foot" sand in New Orleans.

by 6 feet of fine shells in downtown New Orleans, and 

the material is reported to consist of fine clean sand. 

Well 22, at the New Orleans Athletic Club (section 

B-B'), is screened in this sand between the depths of 

1,148 and 1,181 feet, and 1,214 and 1,248 feet and 

yields water having a chloride content of 12,200 ppm. 

The "1,200-foot" sand is separated from the "700- 

foot" sand by a continuous bed of clay. The sand contains several lenses of clay; however, it is believed 

to be a continuous hydrologic unit. The electrical log 

of well 4 indicates fresh water, grading laterally and 

with depth into salt water. The depth of about 900 feet 

at well 4 is the greatest known depth to which fresh 

water occurs in the New Orleans industrial district.

The sand dips to the south at a rate of about 15 feet 

per mile. It probably crops out north of the report 

area in Louisiana or perhaps in the State of Mississippi.

Yield of wells

Harris (1905) reports that a well tapping the "1,200- 

foot" sand flowed about 55 gpm in 1-904. Only a few 

wells are screened in this sand and the two highest 

yields reported are 115 and 200 gpm from 6-inch diameter wells. No data are available on the specific 

capacity of wells in this sand.
36 WATER RESOURCES OF THE NEW ORLEANS AREA

Water-level fluctuations

The artesian head was about 12 feet above the land 

surface in 1904 (Harris, 1905) and is reported to have 

remained at that level until 1937. No recent data are 

available, but, because only small quantities of water 

are withdrawn from this sand, the artesian head is 

probably near the same level at the present time 

(1955).

Withdrawal

The daily withdrawal from the "1,200-foot" sand is 

about 50,000 gallons, or about 18 million gallons per 

year.

Quality of water

A well drilled into the 1,200-foot" sand at the New 

Orleans Athletic Club at the turn of the century flowed 

40 gpm of salt water and 830 cubic feet of gas a day in 

1904 (Harris, 1905). Another well drilled in 1937 for 

the swimming pool at the New Orleans Athletic Club 

flowed salt water having a chloride content of 12,200 

ppm, and a reported temperature of 82°F. (See table 

7 for a partial chemical analysis of water from the 

"1,200-foot" sand.) In the northeastern part of Orleans 

Parish the water from the "1,200-foot" sand is relatively fresh, as shown by the chemical analysis of 

water from well Or-75.

Depth to Salt Water

Plate 1 section D-D', shows the general maximum 

depth of the fresh-water salt-water interface from the 

northern shore of Lake Pontchartrain to the southern 

boundary of the report area. The decrease in the depth 

to the interface between wells 29 and 4 is about 2,000 

feet, and its upward slope is about 120 feet per mile. 

Southward from well 4 the upward slope becomes more 

gentle. In the New Orleans industrial district the 

depth to salt water decreases southward. The variations, in depth to the interface are due both to geologic 

structure and to concentrated pumping within the 

district. There are many factors which may affect 

the movement of salt water into a sand originally containing fresh water.

Over a long period of time, it is possible for salt 

water to migrate upward through a relatively impervious bed, such as clay, into sands containing fresh water, as a result of a pressure-head differential caused 

by pumping from wells screened in the fresh-water 

sands. The magnitude of such movement can be determined only if there is detailed information on the 

thickness and permeability of the clay.differences in 

head and changes in quality of the wafer.

The movement of saline connate water (salt water 

deposited or entrapped concurrently with the deposition of sediments) from downdip within the aquifer may 

occur when the normal hydraulic gradient is reversed 

because of pumping. It appears that this type of movement has occurred in the "700-foot" and "400-foot" 

sands in some areas (pi. 1, well 25, section C-C', 

and wells 16 and 17, section B-B'); however, further

information would be necessary to determine accurately the updip rate of movement of the salt water. 

In many areas the upper part of a sand contains fresh 

water, which grades into salt water with depth. The 

interface between the fresh water and the salt water is 

not stationary but moves, at a rate depending upon the 

amount of pumping and the drawdown within the aquifer. 

If the pressure head in the fresh-water zone is reduced 

by pumping, the salt-water interface rises and moves 

northward in response to the density head of the salt 

water; but, if the equilibrium level of the interface is 

below the bottom of the wells tapping the fresh-water 

zone, then fresh water is "skimmed off. " Nevertheless, the presence of salt water beneath a pumped well 

poses a constant threat of movement, as pointed out 

by Jones, Turcan, and Skibitzke (1954, p. 225) in their 

report on southwestern Louisiana,

Structural discontinuities (principally faults) may 

act as conduits allowing salt water to migrate from 

sands containing it into fresh-water sands.

PUBLIC WATER-SUPPLY SYSTEMS 

New Orleans

The present Sewerage and Water Board of New 

Orleans was created in 1899 by an act of the Louisiana 

Legislature and is responsible for the design, construction, operation and maintenance of the waterworks, 

sewerage and drainage systems. By the end of 1908 a 

nodern water plant was put into operation in New 

Orleans.

The water supply for the city of New Orleans is obtained from the Mississippi River through two pumping 

plants, the Carrollton and the Algiers plants. The 

treatment of the water at the Carrollton plant consists 

of plain sedimentation, softening with lime, intermittent addition of activated carbon for taste and odor 

control, coagulation with ferrous sulfate, sedimentation, ammoniation, stabilization with polyphosphates, 

chlorination, rapid sand filtration, and postchlorination.

The treatment of the water at the Algiers plant is 

essentially the same as at the Carrollton plant. It 

ncludes prechlorination, coagulation, softening, 

sedimentation, ammoniation, filtration and postchlorination. Activated carbon is used for taste and odor 

control if necessary.

The rated capacities of the Carrollton and Algiers 

plants in 1954 were 112 mgd and 7 mgd, respectively. 

The storage capacity for the finished water at Carrollton is 15,000,000 gallons and at Algiers, 7,000,000 

gallons.

The water consumption as reported by the Sewerage 

and Water Board of New Orleans (1952) is as follows: 

41,000 million gallons of water was pumped during 

1952. Fifty-three percent of this amount was sold. 

Unmetered free uses such as fire fighting, street 

cleaning, sewer flushing, leaks, and uses of water at 

the water plant accounted for 38 percent. The remaining 9 percent consisted of free-metered water to the 

city departments and charitable institutions that are 

entitled, by law, to free water.
USE OF WATER 37

Table 8. Maximum, minimum, and average concentrations of several constituents in the raw and finished water at

Carrollton treatment plant

[Chemical analyses by New Orleans Sewerage and Water Board; bacterial analyses by City Board of Health; in parts

per million, except as indicated]

Year

1945

1946

1947

1948

1949

1950

1951

1952

Concentration

Maximum

Minimum

Average

Maximum

Minimum

Average

Maximum

Minimum

Average

Maximum

Minimum

Average

Maximum

Minimum

Average

Maximum

Minimum

Average

Maximum

Minimum

Average

Maximum

Minimum

Average

Alkalinity

Raw

140

55

94

135

61

95

147

64

105

146

57

98

134

61

90

130

58

85

139

56

97

157

65

109

Filtered

47

27

35

48

29

35

70

26

36

44

25

33

42

24

31

45

24

31

50

23

30

58

27

40

Hardness

Raw

174

84

126

200

88

133

205

107

151

194

85

141

192

90

130

182

85

121

171

88

135

255

99

145

Filtered

88

58

71

109

54

75

103

66

83

98

53

79

91

52

74

82

54

67

87

57

72

1 i. 9Q£* »3

71

87

Noncarbonate 

hardness

Raw

47

14

32

75

20

38

63

30

46

59

26

44

63

26

43

72

23

37

63

2.5

39

80

33

47

Filtered

49

24

36

77

19

39

64

33

47

59

27

45

62

26

43

62

26

36

53

29

41

81

33

47

Turbidity

Raw

1,500

120

555

1,770

55

540

1,365

25

425

1,765

36

560

1,450

47

533

1,570

163

667

1,500

155

610

750

11

317

Filtered

1.4

0

.03

1.2

0

.09

1.2

0

.05

1.1

0

.04

1.9

0

.26

4.0

0

.35

3.3

0

.76

3.3

0

.66

Bacteria per 

cubic centimeter 

37°C Agar

Raw

110,000

28

42,800

200,000

100

41,004

200,000

16

78,068

200,000

400

123,595

1,000,000

20,500

150,055

Filtered

65

0

3

200

0

7

200

0

9

200

0

10

200

0

6

The finished water supplied to New Orleans is consistently of good quality. The average hardness as 

CaCO3 for 1948 52 was 76 ppm. The maximum, minimum, and average concentrations of several constituents in the raw and finished water at the Carrollton 

treatment plant is shown in tab! <* 8.

Other Public Water Supplies

East Jefferson Parish Waterworks District 1 supplies Harahan, Kenner, Metaire, Shrewsbury, Southport, and other communities. The treatment plant at 

Shrewsbury has a daily capacity rated at 10 mgd. The 

finished-water storage at Jefferson Parish plant is 

3,500,000 gallons. The raw Mississippi River water 

is treated by plain sedimentation, lime softening, 

coagulation with lime and iron salts, ammoniation, 

sedimentation, rapid sand filtration and chlorination.

The chemical quality of the raw and finished water 

is similar to the raw and finished water of New 

Orleans. (See table 9.)

The town of Gretna in Jefferson Parish also obtains 

its water supply from the Mississippi River. The 

treatment given the raw water is essentially the same 

as at East Jefferson Parish water plant. The treatment 

consists of sedimentation, softening, coagulation, 

filtration, and chlorination. The finished-water storage 

at Gretna is 1,250,000 gallons. Analysis of the raw and 

finished water at Gretna is shown in table 9.

The municipal water supplies in the New Orleans 

area serve about 650,000 people. This information is 

based on the 1950 census.

USE OF WATER

About 1,500 mgd of water from ground and surface 

sources was used in 1954. Of this volume, about 1,250 

mgd from surface sources was used for industrial and 

commercial purposes and about 150 mgd was used by 

public utilities. About 100 mgd from ground-water 

sources was used primarily for industrial and commercial purposes. There is no withdrawal of ground
38 WATER RESOURCES OF THE NEW ORLEANS AREA

Table 9. Mineral constituents and related physical measurements of the raw and finished water of the public

supplies in the New Orleans area

Silica (SiO2 ) . .....................

Iron (Fe). .......... ................

Calcium (Ca)..... .................

Potas sium (K) ....................

Carbonate (CO 3)...... ...........

Bicarbonate (HCO3)... .........

Sulfate (SO4)..................... .

Chloride (Cl)..... ................

Fluoride (F)......................

Nitrate (NO-j)... ..................

» O'

Dissolved solids .................

Hardness as CaCOg ; 

Total.............................

None arbonate . ................

pH.... ..............................

Specific conductance 

(micromhos at 25°C)........

Date of collection (1951)......

Treatment plant at

Carrollton

Raw

10 

.36 

.00 

47 

14 

21 

.8 

0 

161 

51 

24 

.3 

2.5 

262

175 

43

7.5

438 

Aug. 31

Finished

12 

.08 

.00 

16 

8.1 

21 

.8 

0 

37 

52 

26 

.2 

2.0 

158

73 

43

7.1

270 

Aug. 31

Algiers

Raw

10 

.17 

.00 

48 

14 

21 

.8 

0 

162 

51 

24 

.3 

2.0 

266

177

45

7.5

439 

Aug. 31

Finished

10 

.03 

.00 

20 

8.3 

20 

.8 

6 

24 

58 

27 

.3 

2.0 

166

84 

54

8.8

285 

Aug. 31

East Jefferson

Raw

10 

.02

41 

13 

21

0

144 

41 

26 

.3 

3.0 

234

156 

38

7.7

400 

Oct. 12

Finished

12 

.03 

,00 

21 

5.5 

21 

2.0 

5 

23 

56 

27 

.2 

2.0 

163

75

48

8.9

279 

Oct. 12

Gretna

Raw

8.4 .06' 

.00 

35 

9.7 

13

0 

114 

38 

14 

.2 

3.0 

193

127

34

7.3 :

317

May 14

Finished

9.8 

.05 

.00 

21 

3.0 

13 

4.4 

15 

6 

42 

15 

.3 

2.5 

133

65 

35

9.8

237 

May 14

water for public-supply use in the area south of Lake 

Pontchartrain.

The total daily recorded usage from pumped publicsupply wells at Covington, Slidell, and Mandeville is 

450,000 gallons. The average artesian flow from 

public - supply wells screened in sands between the 

depths of 600 and 1,750 feet at Covington, Slidell, 

Abita Springs, Mandeville, Lacombe, Goodbee, and 

Pearl River is about 250 gpm (360,000

Public Supplies

The use of surface water in the New Orleans area 

far exceeds the use of ground water. The Mississippi 

River is the principal source of water for municipal 

supplies in the area.

The average daily pumpage of treated Mississippi 

River water from the Carrollton treatment plant is 

shown in figure 25. The pumpage from this plant has 

increased about fivefold since 1909.

Surface Water

Seventeen large private industrial water supply 

systems in the New Orleans industrial district pump 

on the average about 1,000 mgd from surface-water 

sources. Twelve plants are on the west bank of the 

Mississippi River opposite New Orleans, four are on 

the east bank in or near Chalmette, and one is on the 

Industrial Canal. Most withdrawal for private, industrial and commercial supplies in the New Orleans area 

is made by this group of privately developed watersupply systems.

Of the 1,000 mgd total, about 855 mgd is pumped for 

cooling in the generation of electricity by steam power 

and is immediately returned to the river or canal at a 

slightly higher temperature. The Kaiser Aluminum 

and Chemical Corp. is the largest single user of surface water which is used mostly for cooling in the production of electricity. The cooling process involves 

circulation of 515 mgd through heat exchangers, 

condensers, and boiler feed water systems and then a 

return directly to the Mississippi River.

Except for the American Sugar Refinery, which uses 

22 mgd for cooling, and the Celotex Corp., which uses 

24 mgd for washing and cooling, most of the private 

systems pump less than 5 mgd. Most of the water is 

used for cooling, chemical processing, washing, and 

air conditioning and after passing through the process 

is returned to the surface-water source, essentially 

undiminished in quantity but generally with an increased 

temperature. Some surface water below New Orleans 

is used in the mining of sulfur and is not returned to 

the Mississippi River.

Several of the private, industrial and commercial 

systems pump continuously throughout the year, 

whereas a few pump on a seasonal basis for periods 

ranging from 4 to 8 months.

Ground Water

A summary of the average daily pumpage from 84 

industrial wells within the industrial district is shown 

in table 6. An average of about 62 mgd of ground water 

was used for private, industrial, and commercial uses 

in the New Orleans industrial district during 1953.
POTENTIAL WATER RESOURCES 39

Figure 25. Average daily pumpage of treated Mississippi River water from the Carrollton treatment plant at

New Orleans, 1909-54.

The two major areas of concentrated pumping of 

ground water are in northern St. Charles Parish along 

the Mississippi River, and in western Orleans Parish 

and northeastern Jefferson Parish, where the water 

is used primarily for cooling in industrial plants and 

commercial buildings. Past records of pumping from 

ground-water reservoirs are not available, but the 

steady decline in artesian head in most of the sands 

indicates that more water is being withdrawn today 

than in the past. Although 65 industrial wells have 

been abandoned in recent years, most of them have 

been replaced by new installations at existing or new 

plants.

POTENTIAL WATER RESOURCES 

Surface Water

Less than about 3 percent of the minimum flow or 

less than about 1 percent of the average flow of Mississippi River water is now being used. Most of the 

water that is withdrawn is for cooling and is returned 

to the river, although at a slightly higher temperature, 

and is available for reuse. Public water-supply 

system withdrawal is in great part returned below

New Orleans by way of the city's sewerage system and 

is diluted by the Mississippi River. Although a large 

volume of water is available, the quality is undesirable 

for many uses.

Lake Des Allemands, storage volume about 79,000 

acre-feet, and Lake Salvador, storage volume about 

294,000 acre-feet at mean sea level are n6ar New 

Orleans. The suitability of these lakes as a source of 

supply was not determined for this report.

The streams that drain into Lakes Maurepas and 

Pontchartrain are important sources of fresh water of 

good quality. These lakes serve only as temporary 

storage basins. The Amite and Tickfaw Rivers together discharge an average of about 2,500 mgd 

(2,800,000 acre-feet per year) into Lake Maurepas, 

which has a storage volume of about 570,000 acre-feet 

at 0.5 foot above mean sea level. The Tangipahoa and 

Chefuncte Rivers discharge an average of about 1,300 

mgd (1,460,000 acre-feet per year) into Lake Pontchartrain directly. Water from all these streams is soft 

and generally would require a minimum amount of 

treatment. The Pearl River has an average flow of 

about 8,000 mgd, which serves to dilute salt water that
40 WATER RESOURCES OF THE NEW ORLEANS AREA

enters Lake Pontchartrain from the Gulf of Mexico. 

The quality of this water is good above Bogalusa.

Ground Water

North of Lake Pontchartrain, large supplies of 

fresh ground water are available from water-bearing 

sand and gravel deposits of Pleistocene and possible 

Pliocene age and deeper sands of Miocene age. Wells 

tapping these sands generally have a flow of 1 450 

gpm and yield larger quantities by pumping. No known 

wells tap sands below 2,000 feet, and consequently the 

potential yield of these deep sands has not been determined. However, electrical logs of oil-test wells 

show that fresh water is present in sands to a maximum depth of 3,000 feet. The many hydrologic and 

geologic factors that are necessary to determine the 

full capabilities of the sands are not available. Nevertheless, as the small quantities of water withdrawn 

from the many fresh-water sands have caused only 

slight local decline in water levels, the area north of 

Lake Pontchartrain appears to be favorable for large 

supplies of ground water.

South of Lake Pontchartrain in the industrial district the three principal water-bearing sands, the 

"200-foot, " "400-foot," and "700-foot, " supply about 

62 mgd of ground water, principally for industrial 

purposes. This relatively large local withdrawal has 

resulted in declines in water levels to as much as 100 

feet below the land surface in .the immediate vicinity 

of areas of heavy pumping. This decline does not necessarily indicate an overdevelopment of the waterbearing sands, as the water-level decline has not been 

excessive.

One of the primary factors limiting the potential 

ground-water supply from these sands is the quality 

of water. For example, at Gretna the chloride content 

of the water from the "700-foot" sand is more than 

1,500 ppm; whereas; to the north along the southern 

shore of Lake Pontchartrain, wells screened in this 

sand yield water having a chloride content of less than 

100 ppm. Although the movement of salt water within 

the aquifer has been negligible since 1942, a continual 

increase in withdrawal in the northern part of the industrial district may eventually cause salt-water contamination to become more widespread.

In most areas the "200-foot" sand contains unpalatable water and consequently is not considered a principal source of fresh ground water. The "400-foot" 

sand contains highly mineralized water in some areas; 

however, elsewhere it is uncontaminated and is a 

large source of fresh water. Reported yields from 

individual wells tapping this sand are as high as 2,400 

gpm. There has been no serious decline in water 

levels in the "400-foot" sand in the industrial district 

as a result of the present rate of pumping. The "700- 

foot" sand is the most continuous and has the greatest 

areal extent of the fresh-water-bearing sands in the 

report area. This sand yields as much as 2,000 gpm 

to large-diameter wells. Since 1940 the water level 

in the "700-foot" sand has declined about 54 feet in 

wells near the center of the pumping area; however, 

the decline has been much less in wells away from this 

area. Thus, in the northern part of the industrial 

district, where the aquifer contains fresh water, the

"700-foot" sand provides a potential source for large 

ground-water supplies.

Owing to the poor quality of the water in the "1,200- 

foot" sand, it is not considered a principal source of 

fresh ground water.

Other promising sources of additional fresh ground 

water probably could be developed in Lake Pontchartrain north of the industrial district, where the depth 

of salt water is greater than it is south of the lake. 

However, the development of ground water in this area 

should be preceded by a detailed investigation that 

would include a test-drilling program.

WATER LAWS 

Federal Law

The Federal Government controls interstate navigable streams, keep them free from trash and any 

other potential obstruction, and designs and constructs 

structures for flood control and power development. 

In 1913 the United States Supreme Court recognized a 

relationship of flood control to the "plenary power of 

the United States to legislate for the benefit of navigation" (President's Water Resources Policy Commission, 1950, p. 18) and upheld the right of the Federal 

Government to dispose of waterpower developed using 

a Federal multiple-purpose navigation dam.

Louisiana Law

In addition to Federal laws controlling the use of water, most of the states have enacted water laws in an 

effort to conserve water resources, to safeguard public 

health, and to provide for enforcement of rules and 

regulations deemed to be in the best interest of the 

people of the state.

Louisiana applies the riparian-rights doctrine to 

water. Unlike other states, Louisiana adopted the 

riparian-rights doctrine direct from the Code Napoleon 

and not from the English common law. However, the 

State of Louisiana does not have organized control of 

its water resources. Only one watershed the Sabine 

River is supervised and the use of water from it 

controlled. The Sabine River is regulated by the 

Sabine River Authority, composed of Federal and State 

officials.

It is the responsibility of the Stream Control Commission, Department of Wild Life and Fisheries, to control pollution of streams in Louisiana.

A 1938 legislative act granted to parish police juries 

the right to establish irrigation districts if petitioned 

to do so by property owners of the district. However, 

this act did not provide the right to regulate the use of 

water and may not include incorporated towns and cities. 

The irrigation district is authorized to "...conserve 

the fresh water supply..... provide water for irrigation 

..... The governing authority may do and perform all 

acts necessary to construct, lease, acquire in any 

manner, maintain, and operate dikes, dams, reservoirs, storage basins, locks, levees, flumes, conduits, 

and acquire or lease any private canals and other bodies
SELECTED REFERENCES 41

of water which may be within or without the irrigation 

district and necessary or suitable to the operation of 

the district. " (Louisiana Legislative Council, 1955).

Act 113 of the 1955 Louisiana Legislature constitutes 

enabling legislation providing for a water district in 

southwestern Louisiana comprising the parishes of 

Acadia, Alien, Beauregard, Calcasieu, Cameron, 

Evangeline, Iberia, Jefferson Davis, Lafayette, St. 

Landry, St. Martin, St. Mary, and Vermilion.

The State Department of Health is authorized to 

prescribe sewage treatment and treatment of other 

wastes that are discharged into streams and to prepare a sanitary code which provides rules and regulations for the maintenance of the general sanitary conditions in the State.

The State of Louisiana does not have laws to control 

the use of ground water. The Louisiana Department of 

Health supervises the construction of wells used for 

public supply and usually requires the sealing of 

abandoned wells. In order to prevent the pollution of 

fresh-water sands, the Commissioner of Conservation 

designates the minimum amount of surface casing to 

be set in oilfield wells and salt-water injection wells.

SELECTED REFERENCES

Am. Water Works Assoc. , Inc., 1950, Water quality

and treatment: 2d ed. , New York, N. Y. 

Collins, W. D., 1925, Temperature of water available

for industrial use in the United States: U. S. Geol.

Survey Water-Supply Paper 520-F, p. 97-104. 

Clarke, F. W. , 1924, The composition of the river

and lake waters of the United States: U. S. Geol.

Survey Prof. Paper 135-. 

Fenneman, N. M. , 1938, Physiography of Eastern

United States: 714 p., New York, McGraw-Hill

Book Co. , Inc. 

Fisk, H. N., 1944, Geological investigation of the

alluvial valley of the lower Mississippi River;

Mississippi River Comm. , Vicksburg, Miss. 

 1947- Fine-grained alluvial deposits and their

effects on Mississippi River activity: Mississippi

River Comm. , Vicksburg, Miss. 

Harris, G. D. , 1905, A report on the underground

water of Louisiana: La. Geol. Survey Bull. no. 1. 

Jones, P. H. , Turcan, A. N., Jr. , and Skibitzki,

H. E., 1954, Geology and ground-water resources

of southwestern Louisiana: Dept. Conserv. Bull.

30, p. 285. 

Latimer, R. A. , May 1951, The Atchafalaya River

study: v. 1 3, Vicksburg, Miss. , for the Mississippi River Comm., Vicksburg, Miss. 

La. Dept. Conserv., 1953, Oil and gas map of

Louisiana. 

La. Dept. Public Works, 1954, St. Tammany Parish

Planning Rept., p. 37-38.

La. Legislative Council, 1955, Water problems in the

Southeastern States: Research rept. no. 5. 

Lowman, S. W. , 1949, Sedimentary facies in Gulf

Coast: Am. Assoc. Petroleum Geologists

Bull.,v. 33, no. 12, p. 1939-1997. 

Mississippi River Comm. , Feb. 1&50, Flood control

in the lower Mississippi River Valley: Vicksburg,

Miss. 

 Jan. 1940, History of the improvement of the

lower Mississippi River for flood control and navigation: Vicksburg, Miss.

Sept. 1949, Navigation on the Mississippi River:

Vicksburg, Miss.

Annual report, Stage and discharges of the

Mississippi River and its outlets and tributaries: 

Vicksburg, Miss.

June 1940, The Mississippi River, a short

historic description of the development of flood control and navigation: Vicksburg, Miss. 

Moore, E. W. , 1940, Progress report of the committee

on quality tolerances of the water for industrial uses:

Jour. New England Water Works Assoc. , v. 54. 

Morgan, A. L. , 1953, Analysis of delta farm field:

Am. Assoc. Petroleum Geologists Bull., v.

37, No. 12. 

Odom, L. M. , 1951, Atchafalaya Diversion and its

effect on the Mississippi River: Am. Soc. Civil

Eng. Trans. v. 116, p. 503 526. 

President's Water Resources Policy Commission,

1950, Water resources law: v. 3, Washington,

Government Printing Office, 445 p. 

Russell, R. J. , 1936, The lower Mississippi River

Delta: La. Geol. Survey Bull. no. 8, report on

the geology of Plaquemines and St. Bernard Parishes. 

Sewerage and Water Board of New Orleans, 1949, One

hundredth semi-annual report: New Orleans, La.

 1952, One hundred sixth semi-annual report: 

New Orleans, La.

U. S. Dept. of the Army, Corps of Engineers, Bonnet 

Carre spillway, New Orleans, La: U. S. Dept. of 

the Army, Corps of Engineers, New Orleans Dist.

 1929, Report on the Amite River: New Orleans, 

U. S. 71st Cong. , 2dsess., H. Doc. 480.

1929, Report on the Chefuncte River: New

Orleans, U. S. 71st Cong. , 2d sess., H. Doc. 487. 

1929, Report on Pearl River, La. and Miss.:

Mobile, U. S. 71st Cong., 2d sess. , H. Doc. 445. 

1929, Report on the Tangipahoa River: New

Orleans, U. S. 71st Cong. , 2d sess. , H. Doc. 484. 

1929, Report on the Tickfaw River: New

Orleans, U. S. 71st Cong. , 1st sess., H. Doc. 110. 

1953, Annual report of the Chief of Engineers:

U. S. Army, pt. 1.

U. S. Geol. Survey, Surface Water Supply of the 

United States, pts. 7 and 2B (published annually): 

U. S. Geol. Survey Water-Supply Papers.

U. S. Public Health Service, 1946, Public Health 

Service drinking water standards: Reprint 2697, 

U. S. Pub. Health Serv. reports, v. 61, no. 11, 

p. 371-384.

INT.-CUP. SEC.. WASH., D.C. «(,?

UNITED STATES DEPARTMENT OF THE INTERIOR

GEOLOGICAL SURVEY 

R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 12 E.

CIRCULAR 374 PLATE 1 

R. 14 E. R. 15 E.

R. 21 E. R. 22 E. R.24E. w R.25E. R. 13 E. R. 15 E.

(Jf-37) (Or-57) (Or-10) (St B-5) 

10 11 12 13 14 15 16 17_____18_____19 20 21 22 23 level -4- I l S \- 4- 4- I -!- -FT

Freshwater ) Saltwater

X

£ S (st_

33 34 3536 23 37 38 39

_ _Fresh water ____ 

Saltwater

(Or-73) 

5 

O

Water well

Figures in parenthesis are 

USGS numbers. Letters 

refer to parish names

MAP AND GEOLOGIC SECTIONS SHOWING THE FRESH-WATER-SALT-WATER INTERFACE IN MAJOR AQUIFERS UNDERLYING THE NEW ORLEANS AREA, LOUISIANA

50 20 Mile*