Ground-Water Resources of 

the South A Frontier of the 

o Nation's Water Supply

GEOLOGICAL SURVEY 

CIRCULAR 441

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1
Ground-Water Resources of the

South A Frontier of the

Nation's Water Supply

By P. E. LaMoreaux

GEOLOGICAL SURVEY CIRCULAR 441

Washington 

7960
United States Department of the Interior

FRED A. SEATON, SECRETARY

Geological Survey

THOMAS B. NOLAN, DIRECTOR

Free on application to the U. S. Geological Survey, Washington 2), D. C.
CONTENTS

Page Page 

An important source of water for Summary_________ ______________ - 9

the Nation__________________________ 2 References cited __________________ _ 9

Water problems ______________________ 8

ILLUSTRATIONS

Page

Figure 1. Water demand-_____________________________..._.____.____________-_------- 2

2. Precipitation is the source of our water supply _____»____________________-_--- 4

3. Availability of ground water is related to geology and precipitation______________ 5

4. Geology determines dependability of streamflow _________________-___-___----- 6

5. Precipitation and geology control runoff._____________________________________ 7

6. Major water problems -----___-.___._--_----------------------------------- 8

TABLE

Page 

Table 1. Availability of ground water ___________________________ ____________________ 3

III
Ground-Water Resources of the South 

A Frontier of the Nation's Water Supply

By P. E. LaMoreaux

Up to a few centuries ago, practically all of 

Man's nee.ds for water were supplied from 

streams and springs. As bands or tribes of 

people grew, Man was forced to move farther 

from these surface sources of water in search 

of food, clothing, and other useful materials 

that would allow him to live more comfortably 

in a very competitive world. He solved his 

new water problems at first by scooping out 

shallow dug wells; then, guided by his experience, he dug, and later drilled, deeper and 

deeper wells. There is some record of wells 

being dug as early as 6,000 years ago, and 

very substantial information that the ancient 

Egyptians and Romans, more than 3,000 years 

ago,, learned that a well bored deep into the 

sandstone beds beneath the oases of the 

Libyan Desert would flow fresh water. At 

about the same time the Persians learned that 

by tunneling or digging inclined wells known 

as "kanats" into the stream deposits known as 

alluvial fans, they could obtain large quantities of water. Remnants of the work of these 

ancients in their search for water are historic 

monuments to the capabilities of Man to satisfy his water needs.

This quest for water was a very great challenge to early man for he was delving into a 

completely mysterious unknown. That this 

mystery was important to him is indicated by 

the number of references to water in the Bible 

and other ancient writings, and by the amount 

of time the early philosophers devoted to the 

discussion of this subject. The solution of 

some of Man's water problems, and especially 

those related to the development of ground 

water, permitted civilization to spread and 

gave Man greater latitude in selecting his 

homesite, in carrying out the development of 

his new environment, and in improving his 

techniques for doing things.

The challenge that faced the ancients in locating water, however, was no greater than

that faced by the generations that followed. 

We know from the record that Man's experience did not keep pace with water needs. Evidence of this is the rise and fall of civilizations along the Tigris, the Euphrates, and the 

Nile and in other parts of the world. Even today Man, with all his technology and scientific 

"knowhow," is having considerable trouble 

with water problems he has not been able to 

solve problems related to the appraisal of 

supplies, and their 'development, protection, 

and management. Our world today is faced 

with a rapidly expanding population for which 

the term "explosive" is already becoming 

hackneyed but is none the less appropriate. 

It is forecast that the population of the United 

States will be slightly more than 200,000,000 

by 1970 and 230,000,000 by 1~975. The population is both growing, and shifting, as parts 

of our country grow more rapidly than others. 

In addition, our population is moving rapidly 

to metropolitan areas, and forecasters suggest that by 1970 about 70 percent and by 1975 

about 90 percent of our population will be concentrated in urban areas. Therefore, we no 

less than the ancients are faced with complex 

water problems, for our millions must have 

food, water, clothing, proper sanitation facilities, and a great variety of materials if we 

are to maintain and continue to improve our 

living standards. As shown in figure 1, it is 

estimated that by 1980 our Nation will need 

600 billion gallons of water a'day, and that a 

large part of the increase over the 200 billion 

used at present will have to come from Eastern United States. (U.S. Senate Select Committee on National Water Resources, 1960, 

fig. 2). The need to develop water supplies 

of this magnitude must have a very profound 

influence on the water-resources programs 

that we devise for the future> and a large resource of water, such as that existing in 

parts of the South, becomes tremendously 

significant to ihe welfare of our Nation when 

it is placed in this perspective.
GROUND-WATER RESOURCES OF THE SOUTH A FRONTIER OF THE NATION'S WATER SUPPLY

WATER DEMAND

E S T E R

1950 I960 1970 I960

AN IMPORTANT SOURCE OF WATER FOR THE 

NATION

Precipitation throughout most of the South 

exceeds 40 inches a year, as compared with 

the national average of 30 inches, and in much 

of the Southeast it exceeds 50 inches. From 

figure 2 one can see that the South is one of 

the areas of the United States most blessed 

with rainfall, the ultimate source of ground 

water. Accompanying this large potential 

source of usable water are favorable geologic 

conditions for replenishment and storage of 

water underground. In fact, no other large 

area of the United States and few other places 

in the world meet so favorably the requisite 

conditions for optimum supplies of ground 

water as does the southern Atlantic and Gulf 

Coastal Plain and the Mississippi Embayment. 

Let us refer to figure 3 and table 1 for an 

overall look at the geology and its relation to 

the availability of water.

The South can be divided into three areas: 

The first is the Blue Ridge and Piedmont, the 

oldest geologically and that having the smallest ground-water potential. It is an area

underlain by igneous and metamorphic rocks 

from which wells will yield only limited water 

for rural, domestic, and small municipal and 

industrial uses. The second area, the Appalachian Ridge and Valley and the Appalachian 

Plateau, is underlain predominantly by relatively compact consolidated shale, sandstone, 

and limestone. The water available from 

these rocks varies greatly in quantity; it 

ranges from very small water supplies from 

wells in shale to very large supplies, measured in millions of gallons per day, from 

wells and springs in cavernous limestone.

The third area, the Atlantic and Gulf Coastal 

Plain, is underlain by tremendous volumes of 

relatively unconsolidated sediments capable 

of producing many billions of gallons of water 

per day. It is about this "sleeping giant" 

among our Nation's water sources that I 

would like to make some remarks here.

A few years ago the Geological Society of 

America authorized a Symposium on Sedimentary Volumes (Murray and others, 1952). 

The Gulf Coastal Plain was chosen as the 

logical area for study because of the wealth
AN IMPORTANT. SOURCE OF WATER FOR THE NATION 

Table 1. Availability of ground water

Areas

A. Atlantic and Gulf Coastal Plain

area.

B. Southern Great Plains areas_____

C. Appalachian Mountain and

Piedmont area.

D. Rocky Mountains, northern Great

Plains, and northern Pacific

Coast area.

E. Unglaciated central plateaus and

lowlands.

F 1. Basin and Range _____________

F-2. Columbia Plateau ._ __ _______

G. Glaciated area of the East and

Midwest.

U.S. total (rounded)--__________.

Water use (excluding

water power) in millions of gallons per

day and percent of

total from ground - 

water sources

Total

millions of

gallons

per day)

32,000

21,000

8,000

28,000

26,000

41,000

24,000

57,000

240,000

Ground

water

(percent

of total)

25

45

50

12

10

42

7

10

20

Availability of ground water

Abundant water supplies in sand and

limestone. Large potential. Saltwater encroachment a factor near

coast.

Abundant supplies in sand and gravel,

but replenishment low, especially

in southern part large demands

result in mining of the water.,

Small but reliable supplies for domestic and limited municipal and

industrial use. Potential good for

limited demands.

Generally small supplies adequate

only for domestic and stock use.

Quality very poor in places. Potential not great.

Bedrock generally yields meager

supplies, often of poor quality.

Large supplies of hard water from

limestone locally. Valley alluvium

yields moderate and locally large

supplies of variable quality. Potential not great.

Productive valley alluvium, but recharge low in many places. Large

developments may "mine" the

water. Substantial potential with

judicious management.

Productive lava rocks throughout

province. Locally, recharge is

generous. Potential still great

with proper management, especially in eastern part (Snake River

Plain), which contains one of

largest unused ground-water supplies in the Nation.

Glaciated area, many local deposits

of productive and amply recharged

sand and gravel. Bedrock variable

but highly productive in relatively

few places. Substantial potential

for future.
GROUND-WATER RESOURCES OF THE SOUTH A FRONTIER OF THE NATION'S WATER SUPPLY

PRECIPITATION IS THE SOURCE OF 

OUR WATER SUPPLY

AVERAGE ANNUAL 

PRECIPITATION

OVER £0 INCHES 

___ 10TO£0 INCHES 

I | LESS THAN 10 INCHES

of information from thousands of oil test 

holes and from surface geologic mapping. 

The results of this work were extremely valuable to geologists in the petroleum industry 

and educational field; however, its full implication has not been and still is not generally 

appreciated in the field of water resources.

Geologically the Coastal Plain can be divided into a complex system of strata having 

definite physical character and traceable 

boundaries. Here, however, I'm going to show 

great restraint as a geologist and refrain 

from the details of stratigraphic names as I 

try to convey an idea of the volume and areal 

extent of this mass of material, most of which 

has a high porosity, 30 percent or more, and 

much of which is relatively permeable and 

capable of transmitting tremendous quantities 

of water.

The greatest bulk of the beds in the Coastal 

Plain consist of sand, clay, and gravel or a 

mixture of these materials; however, some 

notable exceptions are the chalk beds of Texas, 

Mississippi, and Alabama and the shell limestone beds of southern Georgia and Florida.

Outcrops of these formations are represented 

by bands of color on the geologic map that 

simulate a huge lazy W extending from Texas 

up the Mississippi embayment, down across 

the eastern Gulf Coastal Plain, and northward 

along the Atlantic Coast. In general, each formation dips gently coastwardand thickens into 

a great tabular wedge of sediments. As we 

travel toward the coast, succeeding outcrop 

patterns, or bands of color on the geologic 

map, represent the outcrops of successively 

younger formations, each resting on older beds 

like the pages of a book. If cut open like a pie, 

the wedge of Coastal Plain sediments would 

appear as a featheredge in its northern extremity, thickening seaward to the coast to a 

total of something less than half a mile in the 

Atlantic Coastal Plain north of South Carolina, 

to about 2 miles in southern Florida, and to an 

estimated thickness of perhaps as much as 

40,000 feet in southern Louisiana. This estimate is based on seismic studies and projections of known geologic information, as the 

deepest oil test in the Coastal Plain, one of the 

2 or 3 deepest wells in the world, had penetrated only the upper half of these formations 

at a depth of 22,570 feet (Butler, 1960). When
AN IMPORTANT SOURCE OF WATER FOR THE NATION

AVAILABILITY OF GROUND WATER 

IS RELATED TO GEOLOGY AND PRECIPITATION

EXCELLENT- QUANTITY AND QUALITY

VARIABLE- GLACIAL DRIFTS

VARIABLE - VALLEY FILL

POOR - QUANTITY AND QUALITY

totaled up, these formations in the Gulf and 

Atlantic Coastal Plain underlie an area between the Mexican border and the GeorgiaSouth Carolina line of about 333,000 square 

miles (nearly one-tenth of the area of the U. 

S.), and the volume of these sediments is some 

875,000 cubic miles (Murray and others, 1952). 

The alternation of permeable sands and limestones with relatively impermeable marls and 

clay create an immense artesian system in the 

Coastal Plain, simple in general design but 

complex in many details. The alternate layers 

of permeable and relatively impermeable beds 

and their gentle dips C eastward are ideally 

suited to the occurrence of artesian water. 

The most important aquifers are commonly 

the coarser grained sands or the limestones. 

The aquifers are separated by beds that are 

more clayey or limy, many of which are also 

very porous but relatively much less permeable. These less permeable beds are significant not only as confining beds for artesian 

conditions but also as sources of water, for 

it has been discovered that, as artesian pressures are reduced in the aquifers, water is 

squeezed out of the highly porous clays and 

marls, is added to the water available to wells.

We have described the receptacle the general physical character of this water-storage 

facility; now let's have a more specific look 

at the "payload" the part in which we as 

fresh-water explorers, producers, or managers are interested. Beneath the whole 

Coastal Plain the ground water occurs in 

three zones in downward succession: a shallow zone of unconfined water in the outcrop 

areas of the water-bearing beds; a zone of 

fresh artesian water below the point at which 

water becomes confined and commonly extending down to depths of as much as 2,000 

feet; and a zone of salty artesian water in the 

lower aquifers, or in the downdip extremities 

of the same aquifers that yield fresh water 

inland.

The shallow zone represents a volume of 

material nearly filled with water under watertable conditions. It extends throughout the 

Coastal Plain and contains freshwater everywhere except in a few places where the plain 

is narrow and is cut by channels connected 

with the sea. The relation of rainwater to 

geology is very intimate in this near-surface 

zone. Figure 4 illustrates this relationship
GROUND-WATER RESOURCES OF THE SOUTH A FRONTIER OF THE NATION'S WATER SUPPLY

GEOLOGY DETERMINES 

DEPENDABILITY OF STREAMFLOW

BAD RIVER FLOWS FROM PIERRE SHALE

3.000

2.000

1.000

MIDDLE LOUP RIVER 

FLOWS FROM SANDHILLS

JAN.

by comparing the streamflow on a sand outcrop area with that on a clay or chalk out-? 

crop. To carry this thought further, a study of 

streamflow records in the Coastal Plain, when 

plotted on abase map.canbe used to delineate 

many of the major geologic boundaries. This 

concept of the close relation between precipitation, surface runoff, and water in the ground 

is important in evaluating the ground-water 

resources of the South, for if one looks at the 

map in figure 5 showing average annual runoff for the United States, practically all the 

Coastal Plain area east of Texas lies within 

the area of highest average runoff. That 

highly permeable beds crop out across this 

area, and further that their water appetite 

must be satisfied before streams will flow 

across them, is substantial evidence that 

these tremendous reservoirs not only are full 

but are rejecting recharge from rainfall. In 

addition, the water table in much of this area 

is near the ground surface and substantial 

amounts of water are being lost by evapotranspiration.

The second, or fresh-artesian-water zone 

that part of the aquifer between the uppermost 

artesian confining beds and the salt-water

zone below also is present throughout the 

Coastal Plain except beneath a thin strip along 

the northern margin of each aquifer and locally along the outer margin of the Coastal 

Plain. This zone may consist of many different water-bearing beds aggregating many 

hundreds of feet of sediments. The deepest 

known fresh water in the Coastal Plain is obtained from a well 5,900 feet deep in Karnes 

County, Tex. Interpretation of electric logs 

from oil tests indicates that fresh water extends to depths of 5,000 feet in McMullen 

County, Tex., and to 3,500 feet just north of 

New Orleans, La., (Sundstrom, R.W., and Turcan, A. N.,U.S. Geol. Survey, written communication^ 1960). Pressure release resulting 

from withdrawal of water from wells in these 

systems is quite rapid and has been recorded 

over large distances for example, as much 

as 60 miles in response to withdrawal of water 

in the Houston area of Texas. The actual 

movement of water at depths of several hundred feet and more in these aquifers may be 

quite slow, how ever, measured in feet per year 

or even in feet per century, in spite of the 

rapid transmission of pressure changes. This 

factor is of great practical importance. On
AN IMPORTANT SOURCE OF WATER FOR THE NATION

PRECIPITATION AND GEOLOGY

CONTROL RUNOFF

AVERAGE ANNUAL RUNOFF

OVER 10 INCHES 

1 TO 10 INCHES 

BELOW 11NCH

the one hand, it affords protection from immediate encroachment of salt water when artesian pressure is lowered, but on the other 

hand it retards the flushing out ofsalt water 

in the down-dip extensions of the aquifers by 

fresh water moving from outcrop areas.

The third, or salt-water, zone includes the 

deeper beds in the outer margin of the region, 

and this salt-water zone occupies more than 

nine-tenths of the aggregate volume of sediments in the Coastal Plain. Even so, if 1,000 

feet is a fair average for the thickness of sediments in the fresh-water zone, there would 

be about 60,000 cubic miles of sediments containing fresh water in the Coastal Plain area 

of Texas, Louisiana, Mississippi, Arkansas, 

Missouri, Illinois, Kentucky, Tennessee, Alabama, and Georgia, and more than 800,000 

cubic miles containing saltwater. By further 

conversion we can estimate that there is 

20,000 cubic miles of fresh water in storage 

in this same area, or enough fresh water to 

cover the 48 States to a depth of 35 feet.

Even though a large source of water supply 

is known to exist, it would not be of value to 

us unless its quality allowed its extensive use. 

From a quick review of many hundred analyses of water from wells spaced geographically 

over the Coastal Plain and tapping more than 

100 different water-bearing beds it can be seen 

that, though the water varies greatly in quality, in general it may be classed as some of 

the best natural water in the Nation. In most 

places the water in the shallow water-table 

aquifers is low in dissolved mineral matter; 

however, in general it is slightly acid. Where 

fresh artesian water occurs in limestone, it 

is largely of the calcium bicarbonate type, the 

hardness ranging between 100 and 300 parts 

per million. Where the fresh artesian water 

occurs in sand, there is- generally a gradual 

increase in mineral content with depth in each 

aquifer, the character of the water changing 

from chiefly calcium bicarbonate to chiefly 

sodium bicarbonate.
GROUND-WATER RESOURCES OF THE SOUTH A FRONTIER OF THE NATION'S WATER SUPPLY

MAJOR WATER PROBLEMS

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SEDIME

The temperature of water in the water-table 

aquifers is usually about 2° to 3°F above the 

average annual air temperature. The temperature of the water increases with depth, in 

most places at the rate of 1°F for each 60 to 

90 feet of increase in depth.

WATER PROBLEMS

So far we have been looking at the good side 

of the ledger. We have seen that there is much 

rainfall in the South, and that the geology is 

highly favorable for its catchment and storage 

underground. We can say further that, whatever water problems the South has, they are 

not as grave as in some other parts of the 

country as, for example, where the economy 

of whole sections of some western States is 

tied to a ground-water resource that is being 

depleted by pumping rates far in excess of 

replenishment.

However, there are symptoms that our 

sleeping giant may have ills which if not properly treated may develop into major problems. Let us take a brief look at these symptoms as depicted on figure 6, showing water 

problems of the Nation (U.S. Senate Select 

Committee on National Water Resources, 

1960). The principal water problems shown 

for the South relate to surface water and 

specifically to floods and pollution. Indicated 

also are quality-of-water problems in coastal 

areas.

Not long ago we had our district representatives in each State list the ground-water 

problems and describe their magnitude and 

extent, and we requested that they project 

these into the next 20 and 40 years. The list 

developed was rather long and seemingly 

rather formless, but when it was plotted on a 

map certain patterns related to water use and 

geologic controls began to shape up. The 

problem areas were expansions of existing 

areas of overdraft, contamination by wastes, 

and salt-water intrusion in coastal areas, as 

related to existing or expected agricultural, 

industrial, and urban growth.
SUMMARY

It should be noted, however, that the map 

showing problems for the Senate Select Committee report and the projection of groundwater problems point out the favorable position of the South. Granted, problems are impending, but many of them can be minimized 

by good engineering and geologic practices, 

based on sound hydrogeologic facts which will 

allow much fuller and more economical development of water.

SUMMARY

The South has a great water supply and at 

the same time has a grave responsibility to 

develop this resource to the maximum benefit 

to all. This is why we are meeting here, and 

why many other similar meetings are being 

held throughout the Nation. All agree as to 

the objective, but to attain it will require much 

more than just desire. Let me Irst the tasks 

that lie before us.

Fir_s±, we must know all about our water 

resources tneir. source, occurrence, movement, quantity, and quality. In other words, we 

must know what our total water potential is 

before we can decide what can be done with it.

Second, we must delve deeper into the mysteries about water that are still held tenaciously by nature the laws that control water 

movement, what happens to it while in storage, what energies drive or obstruct its 

movement through the earth's crust. We are 

now learning that some of the laws such as 

Darcy's law upon which our quantitative 

ground-water studies are based may have 

certain limitations not recognized heretofore, 

and that until we discover the answers to 

some of these unknowns we cannot solve certain critical problems related to waste disposal, salt-water encroachment, an even just 

plain water supply. This means that we must 

place more emphasis on basic research on 

water.

Third, our water developers and distributors must be able to meet the skyrocketing 

demand for water by more efficient methods 

of water withdrawal, treatment, and transmission. To do this they must understand 

and be guided by the results of water investigations.

Finally, we must recognize the extent to 

which development and use of water are tied 

to personal factors the humanistic, the social, the economic situation of our Nation. To 

develop water fully, in the best interests of 

all, will require the utmost in unselfish and 

objective action by individuals, municipalities, 

industries, farmers, and water agencies of all 

types. Herein lies, of course, our most complex problem a problem that can be solved 

only if there is adequate communication between those who know about water and the 

layman, educator, and legislator who are the 

final judges of what will and will not be done.

So now you have the challenge not only are 

these huge supplies of water in the South of 

great value to you, but they are supplies that 

will have to satisfy a large percentage of the 

future agricultural, industrial, and municipal 

needs of our thirsty country. They are one of 

the last great frontiers of the Nation's freshwater resources deal with them judiciously.

REFERENCES CITED

Butler, E. A., 1960, Paleontology of the L. L. 

and E. et al well: Louisiana Geol. Survey 

Folio Ser., No. 1.

Murray, G. E.,Applin, P. L., Toulmin, L. D., 

Colle, Jack, Guzman, E. J., and Nettleton, 

L. L., 1952, Sedimentary volumes in Gulf 

Coastal Plain of United States and Mexico: 

Geol. Soc. America Bull.,v. 63, p. 1157-1228.

U.S. Senate Select Committee on National 

Water Resources, 1960, National water resources and problems: Comm. Print No. 3, 

42 p.

INT.DUP..D.C.60- 35 271