Water Management 

Agriculture, and 

Ground-Water Supplies

GEOLOGICAL SURVEY 

CIRCULAR 415
Water Management 

Agriculture, and 

Ground-Water Supplies

By R. L. Nace

GEOLOGICAL SURVEY CIRCULAR 415

Washington I960
United States Department of the Interior

STEWART L. UDALL, Secretary

Geological Survey

William T. Pecora, Director

First printing 1960 

Second printing 1 964

Third printing 1 965 

Fourth printing 1967

Free on application to the U.S. Geological Survey, Washington, D.C. 20242
CONTENTS

Abstract._____________________________________________ i

Introduction__________________________________________ i

World's supply of water. _ _______________________________ 2

The United States' share of world water supply________________ 3

Use of water__________________________________________ 5

Trends in water use____-_______--_______-______---__ 5

Mined water is not self-renewing. _______________________ 5

Some sample water situations-_____________________________6

The meaning of water problems- ____-________---______--___8

The challenge to water management-____________________9

More efficient use of water____________________________c)

Quantitative evaluation of water supplies- ________________ IQ

Scientific management-______________________________40

The ultimate critical problem._________________________n

References cited. _______________________________________ 12

ILLUSTRATIONS

FIGURE 1. Number of acres irrigated in the United States, by States, 

1954____________________________________...4

2. Use of water in the United States, 1958. . _______.____5

3. The irrigated acreage in the High Plains of Texas______6

4. In 1948 there were 8,336 wells in the High Plains of 

of Texas_ _______________________________ ______ 7

TABLES

TABLE 1. World area of arid and semiarid land_ ________________2

2. Distribution of the world's supply of water 3
Water Management, Agriculture, and Ground-Water Supplies

By R. L. Nace

Based on a paper read before the Annual Meeting of the 

American Association for the Advancement of Science, Section 

0 Agriculture, in Washington, D. C., December 29, 1958.

ABSTRACT

Encyclopedic data on world geography strikingly illustrate 

the drastic inequity in the distribution of the world's water 

supply. About 97 percent of the total volume of water is in the 

world's oceans. The area of continents and islands not under 

icecaps, glaciers, lakes, and inland seas is about 57.5 million 

square miles, of which 18 million (36 percent) is arid to semiarid.

The total world supply of water is about 326.5 million.cubic 

miles, of which about 317 million is in the oceans and about 9.4 

million is in the land areas. Atmospheric moisture is equivalent 

to only about 3,100 cubic miles of water.

The available and accessible supply of ground water in the 

United States is somewhat more than 53,000 cubic miles (about 

180 billion acre ft). The amount of fresh water on the land 

areas of the world at any one time is roughly 30,300 cubic miles 

and more than a fourth of this is in large fresh-water lakes on 

the North American Continent.

Annual recharge of ground water in the United States may 

average somewhat more than 1 billion acre-feet yearly, but the 

total volume of ground water in storage is equivalent to all the 

recharge in about the last 160 years. This accumulation of 

ground water is the nation's only reserve water resource, but 

already it is being withdrawn or mined on a large scale in a few 

areas.

The principal withdrawals of water in the United Staes are 

for agriculture and industry. Only 7.4 percent of agricultural 

land is irrigated, however; so natural soil moisture is the principal source of agricultural water, and on that basis agriculture is 

incomparably the largest water user. In view of current forecasts of population and industrial expansion, new commitments 

of wafer for agriculture should be scrutinized very closely, and 

thorough justification should be required. The 17 Western States 

no longer contain all the large irrigation developments. Nearly 

10 percent of the irrigated area is in States east of the western 

bloc, chiefly in several Southeastern States.

Ground water is not completely "self-renewing" because, 

where it is being mined, the reserve is being diminished and 

the reserve would be renewed only if pumping were stopped.

Water is being mined at the rate of 5 million acre-feet per 

year in Arizona and 6 million in the High Plains of Texas. In 

contrast, water has been going into storage in the Snake River 

Plain of Idaho, where deep percolation from surface-water 

irrigation has added about 10 million acre-feet of storage since 

irrigation began.

Situations in California illustrate problems of land subsidence 

resulting from pumping and use of water, and deterioration of 

ground-water reservoirs due to sea-water invasion.

Much water development in the United States has been 

haphazard and rarely has there been integrated development of 

ground water and surface water. Competition is sharpening and 

new codes of water law are in the making. New laws, however, 

will not prevent the consequences of bad management. An 

important task for water management is to recognize the contingencies that may arise in the future and to prepare for them. 

The three most important tasks at hand are to make more 

efficient use of water, to develop improved quantitative evaluations of water supplies arid their quality, and to develop 

management practices which are based on scientific hydrology.

INTRODUCTION

The poor geographic distribution of water in 

the world is a principal problem in water 

management. This is very well known. Yet 

each year many thousands of published words 

describe the locally poor geographic and seasonal 

distribution of water as a fundamental point.

Poor distribution of water is strikingly evident on an ordinary geographic map of the 

world. The total surface area of the earth is 

197 million square miles. About 139 million 

square miles (70.8 percent) is covered by the 

world's oceans, about 6.9 million (3.4 percent) 

by polar icecaps and glaciers, about 330,000 

(0.17 percent) by natural fresh-water lakes, and 

about 270,000 (0.14 percent) by natural saline 

lakes. About 50 million square miles (about
25.4 percent) is continental and insular dry 

land. The total land area, including that under 

ice, lakes, and inland seas is about 57 million 

square miles. More than two-thirds of the land 

area is in the Northern Hemisphere. Somewhat 

more than 18 million square miles (about 36 

percent) of the land area is arid to semiarid 

(table 1).

The inequity in water distribution is indeed 

drastic. Therefore, before discussing water 

management, it is pertinent to consider how 

much water we have to manage. Therefore, 

some typical water problems and situations will 

be used to illustrate that the optimum effective 

use of water can be attained only of it is managed in accordance with scientific principles.

TABLE 1. WORLD AREA OF ARID AND SEMIARID LAND

[Based on data given by Shantz (1956, p. 4-5)]

Area (square miles) based on 

Class of land Vegetation Climate

2,430,000 2,244,000

------------ 12,900,000 8,418,000

------_---._ 2,720,000 8,202,000

Total..........__ 18,050,000 18,864,000

WORLD'S SUPPLY OF WATER

The world's supply of water is estimated 

approximately as follows. The volume of ocean 

water is about 317 million cubic miles 

(or 1.07 x 10' 5 acre ft 1 . (See table 2.) The estimated water volume of polar icecaps and glaciers 

on the continents is about 7.3 million cubic miles 

(about 2.47 x 10' 3 acre-ft). Fresh-water lakes 

contain about 30,000 cubic miles (1.01 x 10" 

acre-ft), and saline lakes and inland seas contain 

about 25,000 cubic miles (8.7 x 10'' acre-ft). The 

average amount of water in stream channels at 

any one time is on the order of 280 cubic miles 

(9.5 x 108 acre-ft).

Based on an ocean area of 139 million sq mi and a rounded 

mean depth of 12,000 ft (2.27 miles). A mean depth of 

12,450 ft is commonly assumed, but recent surveys indicate 

that the shallow continental shelves are broader than was 

once believed and the oceans' ridges are larger; so a somewhat smaller rounded value seems appropriate. One cubic 

mile = 3,379,200 acre-ft= 1,101,215,599,200 gal.

Extremely arid (desert) ____

Arid..._._.._.._.......

Semiarid ____---_______._

The main root zone (about the upper 3 feet) 

of the soil probably contains at least about 

6,000 cubic miles of water (2 x 10 10 acre-ft). 

The estimated additional amount of water in 

the rock crust of the earth is about 1 million 

cubic -miles (3.4 x 10 12 acre-ft) to a depth of 

half a mile and an equal amount at the depth 

between l/2 and 2 miles.

The estimated volume of moisture in the 

atmosphere is equivalent to only about 3,100 

cubic miles (1.15 x 10 10 acre-ft) of water, or 

enough to cover the entire earth to a depth of 

only about 1.0 inch.

The data summarized in table 2 show that 

the total world supply of water is somewhat 

more than 326 million cubic miles. Though the 

estimates are inexact, they help to define the 

magnitude of the problem of water management. 

About 97 percent of the world's water supply 

is in the oceans. The conversion of salt water 

to fresh is a great and intriguing challenge. 

Even though conversion processes become 

economically feasible, however, the cost of 

transportation may prohibit the use of converted sea water by inland areas for a long 

time. Conversion of locally available salt water 

may become feasible in some inland areas, and 

may resolve problems that are locally serious. 

On the whole, however, the available amount 

of such water is not sufficient to add materially 

to regional or national water supplies. Therefore, for an indefinitely long future period, 

inland areas will receive water from the sea only 

indirectly and in the same manner that they 

always have as vapor carried inland in the air 

and dropped as rain and snow.

The total volume of water on the land and 

beneath its surface is only about 9.4 million 

cubic miles. About 78 percent is locked up m 

icecaps and glaciers, and about 0.27 percent is 

in inland saline lakes and seas. Much of the 

ground water at depths greater than half a mile 

is economically inaccessible at present or is 

saline. Thus, less than 3 percent of the world's
TABLE 2. DISTRIBUTION OF THE WORLD'S ESTIMATED SUPPLY OF WATER

(All quantities rounded]

Location

Surface area 

(thousands of 

sq mi)

Volume of

water 

(thousands of cu mi)

World (total area) ________________________ 197,000

Land area._____________________________ 57,500

Surface water on the continents:

Polar icecaps and glaciers. ___________________ 6,900

Fresh-water lakes ________________________ 330

Saline lakes and inland seas __________________ 270

Average in stream channels- ______________________

Total surface water _ ___________________ 7,500

Subsurface water on the continents:

Root zone of the soil- _____________________ 50,000

Ground water above depth of

2,640 ft_________________________________

Ground water, depth of 2,640 to

13,200 ft________________________________

Total subsurface water _ _________________ 50,000

World's oceans- __________________________ 139,500

Total water on land _____________________________

Atmospheric moisture_ ___________________________

Total, world supply of water. _________'_____

7,300

30

25

.28

7,360

1,000

1,000

2,000

317,000

9,360

3.1

326,000

Percentage

of total

water

2.24

.009

.008

.0001

2.26

0.0018

.306

.306 

.61

97.1

2.87

.0001

100

water supply is available on the continents, and 

only about 11 percent of the water on the continents, actually is usable or accessible. Furthermore, the yearly renewal and continued availability of this relatively minute supply of water 

depend wholly on precipitation from a tenuous 

bit of water vapor in the atmosphere.

THE UNITED STATES' SHARE OF WORLD 

WATER SUPPLY

The total land area of the 48 contiguous 

States, including lakes, is somewhat more than 

3 million of the world land area of 57.5 million 

square miles. On a proportional basis, our share 

of the world ground-water supply in the upper 

one-half mile of the earth's mantle is about 

5.3 percent, or 53,400 cubic miles (180 billion 

acre-ft). In contrast, large lakes on the North 

American Continent contain about 8,000 cubic 

miles, or about one-fourth of all the fresh surface water on the globe.

Precipitation on the 48 States averages about 

30 inches (about 2.5 ft) yearly, and the total 

yearly volume is about 1,370 cubic miles

(4.64 billion acre-ft). Natural annual recharge 

of ground water may average a fourth of the 

precipitation, or about 340 cubic miles (1.15 

billion acre-ft) yearly. This is a liberal estimate, 

which many hydrologists wold dispute. However, it indicates the order of magnitude of 

ground-water recharge.

On the basis of the above estimates, the volume of ground water in storage above a depth 

of half a mile evidently is equivalent to the total 

of all recharge during the last 160 years. This 

estimate is very crude, but whether the true 

figure is 50, 100, or 200 years is unimportant. 

The significiant fact is that a reserve of water 

has been accumulating in the ground-water 

bank for generations. This is the only real water 

reserve we have. Annual recharge in any one 

year is proportionately a very small increment 

to the total reserve. Now, by pumping, we are 

placing heavy drafts on the local "branch banks" 

in some parts of the United States enough 

that the manager of the "main bank" must look
37,672 

27.700.000

; 9207 , 

L -- ..__.._..__. N.22,193,000;

 - ) I8.I99_ 

9O,37i \ v 12,680,000 

19.629,000 23. A 73 \ 

10.788.o66g,

2396

_ -25981,000 J 

22,867,000 V ' (* 

/ o 

(^sT^oobl

'\.. ;

32,998 ._ 

! 17.705.000

108.151 \ 

14,471.000 ; 857-.8gj_ / ")'

( 132,490 I \

I 7,792.000j /665fl \ 

' -480000( 8

' ! 

X>C/?£S IRRIGATED _ 4,707.028 

TOTAL CROPLAND ACRES 36,660.000

Figure 1 Number of acres irrigated in the United States in 1954, by States. The total irrigated area was 29,552,155 acres of a total cro
to the total reserve and estimate how long the 

drafts can continue. This is the job for water 

management.

USE OF WATER

Total water use commonly is estimated in 

terms of diversions from streams and pumpage 

from the ground, ignoring the principal use of 

water the water derived directly from natural 

soil moisture. The soil moisture demand for 

nonirrigated farm land is met largely and 

directly by precipitation. The water demand for 

irrigation is, in fact, a demand to increase and 

maintain soil moisture. Only 7.4 percent of our 

cultivated land is irrigated (fig. 1), yet withdrawal of water for irrigation about equals 

industrial wihtdrawls (see fig. 2), and exceeds 

them if we include conveyance losses in irrigation. Since natural soil moisture is the principal 

source of water for agriculture, agriculture gets 

incomparably the largest share of the yearly 

water supply, even without irrigation.

PUBLIC SUPPLY 

4.6 PERGENJ

RURAL SUPPLY 

1.0 PERCENT

INDUSTRIAL

SUPPLY 

48.2 PERCENT

Figure 2 Use of water in the United States in 1958. The 

use in 1955 was estimated (MacKichan, 1955, p. 16) at 

210,500 million gallons per day plus 28,900 million 

gallons per day conveyance losses in irrigation. In the 

diagram, total use in 1958 is estimated at 240,000 million 

gallons a day, not including conveyance losses of 32,400 

million gallons a day.

There is nothing wrong with the use of soil 

moisture by agriculture, especially because we 

have no other way to use soil moisture. Looking to the future, however, and to the increasingly 

narrow margin between water supply and water 

demand, perhaps management and economic and 

legal authorities will begin to scrutinize very 

closely all new commitments of water for agriculture. From the standpoint of optimum 

water use, perhaps the best place to expand 

agriculture is in areas where its water demand 

can be met largely and directly by natural soil 

moisture.

TRENDS IN WATER USE

Trends in water use also deserve close scrutiny. 

For example, the practice of irrigation is 

increasing rapidly in the humid Eastern States. 

We still speak of the "17 Western States" as 

the home of irrigation; yet more than 9 percent 

of the total irrigated area in the United States 

is east of the bloc of western States. Irrigation 

has become widespread in Florida, Mississippi, 

Louisiana, and Arkansas, and several other 

Southern States are developing irrigation rapidly. 

We now have to reckon with 21 "irrigation 

States." Extensive use of water for irrigation in 

the Southeast may become directly competitive 

with the current trend toward industrialization 

in that region.

MINED WATER IS NOT SELF-RENEWING

Water is commonly called "a self-renewing 

natural resource," because a new supply is furnished each year by rainfall. Actually, only the 

yield of streams and the dependable perennial 

yield of aquifers is self-renewing. Withdrawn 

ground water is fully renewed by natural recharge 

only at places where withdrawal does not exceed 

the dependable perennial yield. Where the 

accumulated reserve of ground water is being 

depleted, the reserve would be renewed only if 

withdrawals were stopped. Mining of water, in 

effect, is a gamble by society that some major
scientific accomplishment, such as weather modification or desalting of saline water, will provide 

a new or added source of water when the mine 

goes dry. In the present state of knowledge, the 

odds in this gamble cannot be calculated.

SOME SAMPLE WATER SITUATIONS

Texas withdraws about a fifth of all the ground 

water used in the United States (Sundstrom, 

1957). Ground water is the sole source of 

supply for nearly 600 towns and cities in the 

State, which is second only to California in the 

volume of ground-water withdrawls. Use of 

ground water in Texas for all purposes increased 

twenty fold in the last 18 years and tenfold in 

the last 8.

Of the total ground water used in Texas, 

about 83 percent is for irrigation, 7 percent for 

industry, 6 percent for municipal supply, and 4 

percent for rural domestic and stock supply.

Out of 8 million acre-ft of ground water 

withdrawn in Texas in 1956, about 2 million 

acre-feet was intercepted water that otherwise 

would have been discharged by natural means. 

As withdrawals increase in the future, the proportionate draft on ground-water storage will 

increase.

An irrigation survey of the High Plains of 

northwestern Texas (Sherrill, 1958) showed that 

4,752,570 acres was irrigated in that area in 1958 

(fig. 3), all with ground water and water from 

small local lakes. Out of 45,522 irrigation wells, 

33,766 were lifting water more than 125 feet. 

More than 1,000 new wells were added in that 

year. The phenomenal growth of pumping 

coincided with a 10-year drought in that part of 

Texas, and the drought obviously supplied a 

strong stimulus to ground-water development.

Runoff is very small in the High Plains area, 

and most of the water supply is underground. 

About 6,348,000 acre-ft of water was pumped in 

this area in 1956 (Texas Board of Water 

Engineers and others, 1958, p. 28-29). Pumpage 

in 1958 probably was about 7 million acre-ft.

wmmm.

YEAR

Figure 3 The irrigated acreage in the High Plains 

of Texas increased 362 percent in the 10 years 

after 1948.

The principal bulk of pumpage since the 

beginning of pumping (mostly since 1948), 

was a draft on reserve storage because natural 

discharge of ground water has not lessened 

appreciably. The increasing draft on ground 

water is reflected in increased pumping lifts and 

lowered yields from wells (fig. 4). Water is 

being mined rapidly in this area. Unquestionably, the mining is profitable now, and this 

kind of operation is self-regulating to some 

extent. As pumping lifts increase and well 

yields decline, costs rise and economic factors 

may force a balance between water supply and 

water use. The balancing may entail social and 

economic adjustments. To what extent can 

management aid orderly adjustment and assure 

optimum use of the water?

Quite a different situation has developed on 

the Snake River Plain of Idaho, where irrigation 

development, using water from the Snake River,
became rapid soon after 1909. The plain was 

underlain by a very large body of natural ground 

water, overflow from which was discharged 

through springs into the Snake River below the 

irrigated area. Excess irrigation water that was 

applied to the land filtered into the ground, 

joined the ground-water body, and was discharged through the springs. The capacity of 

the ground-water reservoir was so great that 

water levels did not generally rise much, but 

the average aggregate rate of discharge from the 

springs increased from about 3,800 cfs to about 

5,500 cfs in a quarter of a century.

A somewhat specialized situation prevailed in 

the Twin Falls (south side) tract on the Snake

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YEAR

Figure 4 In 1948 there were 8,356 wells in the High 

Plains of Texas; only 17.5 percent of these lifted water 

more than 125 feet and 74 percent yielded more than 

700 gallons per minute per well. In 1958 the number 

had increased to 45,522 and the percentages had changed 

to 74 and 43 respectively.

River Plain, where ground water originally 

occurred only at considerable depth. During the 

first 25 years of irrigation on this 200,000-acre 

tract, the water table rose 200 to 300 feet and 

at least several hundred thousand acre-feet of 

water went into underground storage.

Water was not mined on the Snake River 

Plain. It was put in the bank. The increase in 

storage beneath the whole plain was on the 

order of 10 million acre-feet. This was not 

planned; it merely happened as an incident to 

irrigation with surface water. Further irrigation 

expansion is under way, using water from the 

ground, including extensive private developments and the first large Federal reclamation 

project that is based on ground-water irrigation.

Consider the tremendous capacity of the 

basalt aquifer in the 10-million acre area of the 

plain east of the longitude of King Hill, Idaho. 

Normal precipitation on this plain, averaged for 

the entire area, is about 10 inches. In much of 

the area the amount is only about 7 inches. 

Probably, less than an inch of precipitation, on 

the average, becomes direct recharge about 

680,000 acre-feet yearly. Most perennial replenishment of the ground water is by underflow 

from adjacent highlands. The estimated volume 

of saturated aquifer is 10 acre-feet, in which 

the estimated total water content is 2 x 109 

acre-feet. This is roughly a thousand times the 

combined storage capacity of all the surface 

reservoirs on the Snake River, above King Hill 

 one of the most completely regulated large 

rivers in America. Much of this ground water 

is in capillary pores and could not be extracted 

by gravity drainage into wells. The extractable 

volume probably is about 5 x 10 acre-feet, or 

about 135 times the storage capacity of the 

surface reservoirs.

The currently unconsumed perennial yield of 

the aquifer in the Snake River Plain is about 

4.2 x 106 acre-feet. If spread out in the zone of 

saturation east of King Hill, this water would
occupy a thickness of only 8.4 feet, or about 1 

or 2 percent, of the aquifer. All the remaining 

water is potentially recoverable and is in what 

amounts to "dead storage." Of course, only 

part of this water is effectively available, but 

this area offers a tremendous opportunity for 

scientific water management.

Entirely different problems are illustrated in 

California. Among many situations created by 

pumping, two are chosen to illustrate the 

diversity of water problems: land subsidence 

caused by dewatering of aquifers; and intrusion 

of sea water into fresh-water aquifers in certain 

coastal areas.

Land subsidence has occurred widely in the 

San Joaquin Valley of California, and less widely 

in the Sacramento and Santa Clara Valley areas. 

The rate of subsidence in recent years has beenas much as 0.8 foot per year, and this subsidence 

in some areas is attributed to lowering of the 

artesian head in pumped aquifers (Poland and 

Davis, 1958). Little imagination is needed to 

visualize the consequences of subsidence in 

terms of disturbed drainage and irrigation 

systems and other effects. Factors other than 

dewatering of aquifers also cause subsidence of 

the land, as is shown by several examples in 

California. Wetting of noncompacted soil and 

subsoil by irrigation has caused compaction and 

subsidence in the Central Valley. Subsidence 

has deranged certain canal systems in the 

Central Valley. Oil-field development at Long 

Beach has caused subsidence, and some land in 

that area is now below sea level.

Sea-water invasion of aquifers is a common 

problem in coastal areas of many seaboard States. 

Invasions of sea water in about 20 ground-water 

basins along the coast and inland bays of 

California have been observed for about 35 

years (Baumann, 1953, p. 521). Not until 1950, 

however, were systematic experiments begun at 

Manhattan Beach, Redondo Beach, and El 

Segundo to combat the invasion by creating a

fresh-water mound or ridge, inshore from the 

sea, to retard or stop the invasion. Two methods 

were used: recharging the aquifer through 

spreading grounds at Redondo and El Segundo 

to sustain water levels generally, and recharge 

through batteries of injection wells at Manhattan 

Beach, to create a ground-water mound a 

barrier to invasion. The results from small-scale 

water-spreading, were inconclusive; those from 

recharging wells were more positive. Much 

remains to be done in California and many 

other places, to rescue aquifers from marine 

invasion and to forestall further invasion.

THE MEANING OF WATER PROBLEMS

The few examples given above of widely 

contrasting situations emphasize the basic fact 

that water development in the United States 

has been mainly a laissez-faire process, in accord 

with the individualistic tradition inherited from 

the pioneers. Surface-water users commonly 

have been forced by the high cost of construction to join hands in development projects. 

Most ground-water users have gone independent ways. Each class of users tends to regard its 

source of water as distinct from the others. In 

many areas, however, overdevelopment is now 

forcing recognition of the unity of water as a 

single resource. For example, a water authority 

in one Western State recently ruled that 

permission to pump new wells in a certain area 

would be conditioned on concurrent purchase 

and release of rights to an equal amount of 

surface water.

The situations here described illustrate that 

development which is based on a selfish philosophy leads to situations which could be 

avoided because we have at our disposal the 

scientific knowledge needed for the guidance of 

water management. Certain highly developed 

areas in the Southwest today face a situation 

which eventually will confront all highly 

developed areas that depend heavily on ground 

water: water is being withdrawn at a rate, that
cannot be continued indefinitely, yet the demand 

is increasing. What is the future of these areas 

after the recoverable reserve of ground water is 

exhausted? The High Plains of Texas has or 

will have this problem. Will the plains one 

day revert to their native condition?

A reverse and favorable situation exists in the 

Snake River Plain, which contains what is 

probably the largest naturally unified water 

system in North America. The reserve of 

ground-water storage has been building up 

unseen, owing to irrigation, and today the 

ground-water resource is virtually undeveloped. 

The area offers a great opportunity for scientifically guided development and management of 

the total water resource.

The situation in southern California also has 

$ome important lessions. Although the problems 

of salt-water encroachment have been appreciated and studied for many years, no permanent 

or general solution has been found. Much of 

the scientific knowledge and data necessary for 

solution are available, but management in many 

parts of the country is not sufficiently sensitive 

to scientific principles to attempt effective use 

of them. This leads us to the real problem for 

water management.

THE CHALLENGE TO WATER MANAGEMENT

Reportedly, there are more than 500 principal 

local water-supply agencies in the United States, 

and there is a host of minor ones. Texas alone 

has about 500 water agencies, including irrigation districts and other small agencies. Each 

State has several State agencies with responsibilities for water, and about 25 Federal agencies 

have important responsibilities or concern with 

water. All these agencies have made and are 

making decisions and taking actions that commit 

water or affect its quality and availability. Some 

of these decisions and actions may have 

prejudiced the future.

Several recent forecasts indicate that the 

national water requirement will double by 1975

or 1980. In how many States could withdrawal 

be doubled? How could the withdrawals be 

made? What will be done if such withdrawals 

are not possible?

In view of forecasts of the national water 

demand, some commentators say that our main 

problem is where to get the water and still have 

enough for expansion in the next generation. 

But is it? Three things seem more important: 

more efficent use of the water we already have 

developed; improved quantitative evaluation of 

water supplies and their quality; and scientific 

management.

MORE EFFICIENT USE OF WATER

Projections of history are the basis for most 

forecasts of future water use. But history is an 

index of the future only in those things over 

which we exercise no control. With scientific 

water conservation and management and more 

efficient use of water, most of or all the increased 

demand during the next 10 to 20 years might 

be met without material increase in our gross 

water demand.

During the 40 minutes, it takes to read this 

paper, about 100,000 acre-feet of water has 

flowed from the United states back into the 

sea from whence it came. How much did we 

get out of it before it returned to the sea? 

Water uses in the United States are generally 

rather lavish, though there are some notable 

specific exceptions. Abundant data show that 

many current uses of water are wasteful, some 

extremely so.

In one area in the arid West, comprising 

1 million irrigated acres, the water diverted for 

irrigation, averaged for the whole area, was 

about 6.6 feet in the 1957 water year. Some 

districts in the area used up to 10 feet of water. 

On the other hand, the potential evapotranspiration in that area, computed by the 

Thornthwaite method, is about 2.2 feet. About 

0.2 to 0.4 feet of the requirement is supplied 

directly by precipitation, and only 1.8 to 2.0
feet is needed from irrigation. Thus, the 

efficiency of water use is about 30 percent or 

less. Increasing the efficiency even to 50 percent would free enough water to irrigate more 

than 600,000 acres of new land more new land 

than seems to be suitable for irrigation in that 

area. The whole potential irrigation expansion 

in this area by, say, 1975 could be met without 

additional gross water demand. In this area, 

much of the excess irrigation water gets into 

the ground-water reservoir and is available for 

reuse. But it is not necessarily available at the 

places where it could best be used. Moreover, 

the cost of pumping could be avoided by more 

effective use of the water while it is still at the 

surface.

A few miles from the area just considered, in 

an area having about the same potential natural 

water demand, farmers irrigate some crops 

successfully with less than 2.0 feet of water and 

pride themselves on their ability to make a crop 

with what others would look upon as a starvation ration of water.

QUANTITATIVE EVALUATION OF WATER SUPPLIES

A recently published report on ground water 

states that "only after years of development 

may the effects of overdevelopment become 

evident." Similar statements appear in many 

reports. They are true in the present state of 

knowledge. But "after years of development" 

is too late. To determine "the effects of overdevelopment" is to determine the course of 

history to describe a problem without solving 

it. The "solution" applied "after years of 

development" often is the adoption of some 

drastic control or of some new law.

Some water planners now advocate drastic 

changes in State laws and policies about water 

rights. Rather than grant rights in perpetuity, 

they would assign rights for consuming uses of 

water for terms of say 10 or 25 years; rights for 

nonconsuming uses might be for 25 to 50 years.

These are signs of the times, and new laws

undoubtedly are needed. But laws will not create 

water where none existed before, or restore it 

where it has been mined. Nor will they restore 

the quality of water that has deteriorated. 

Generations might be required to rehabilitate a 

contaminated aquifer, because ground water 

moves very slowly. New laws will not prevent 

the consequences of bad management. So the 

first need is not laws but intelligent management. 

Many people seem to believe that our main 

problem is to locate ground-water supplies. This 

was true a generation ago, but it is true no 

longer. Although techniques can be improved, 

we have good methods for locating water 

supplies and can find them just about wherever 

they exist. The real problem of today is twofold: to determine the quality of water and its 

quality; to manage the water in accord with 

principles of hydrology. The continuing problem is how to manage a total water supply, a 

small part of which is perennially self-renewing, 

but which is largely a nonrenewable resource.

SCIENTIFIC MANAGEMENT

Water all water is a single resource. Almost 

everyone knows that pumping from a flood 

plain near a river can deplete the flow of the 

river. But this is only a small part of the problem. Pumping anywhere affects the total available water. Management requires the study of 

whole regions, not merely of basins or districts.

Another example will illustrate the pointnamely, the 11-county tristate area adjacent to 

the lower Delaware River, including Philadelphia, Pa., Camden and Trenton, N. J., and 

Wilmington, Del. Barksdale and others (1958, 

p. xii) estimate that current withdrawal of 

ground water in the region is somewhat more 

than 200 million gallons per day. More than 

1 billion gallons per day could be developed 

within the region, and additional water could 

be developed outside the region and imported 

if the need arose. The report shows that recharge 

from the Delaware River, induced by heavy

10
pumping, contributes a substantial part of the 

total ground water now drawn from the Raritan 

and Magothy formations. Increased pumping of 

ground water would increase recharge. Therefore, maintenance of good quality in the river 

water is necessary, both for its own sake and to 

preserve the quality of the ground water.

Deepening of the Delaware River channel 

from Philadelphia to Trenton, which has been 

proposed, would increase the opportunity for 

interchange of water between the river and the 

adjacent aquifers. Whether this would be 

beneficial or detrimental to the quality of the 

ground water would depend on the quality of 

the water in that reach of the river. River 

water of acceptable quality would augment the 

ground-water resources of the region. If salt 

water from the ocean or contamination from 

other sources depreciates the quality of the river 

water, actual and potential ground-water supplies 

aggregating about 250 million gallons per day 

would be endangered. Therefore, a proposal has 

been made to construct a low dam on the river 

near the head of Delaware Bay, to prevent 

incrusion of salt water.

This kind of situation calls for aggressive, 

intelligent management, and the report that has 

been cited outlines a scientific basis for developing management plans as further scientific 

studies continue.

"Management through knowledge" should be 

a watchword. Management of ground water and 

surface water jointly as a unit resource should 

be expanded and continued. Each kind of water 

has peculiar advantages. What are the advantages in this case or that? How do we apply 

hydrology to the profitable use of water so as 

to safeguard the total resource? How can 

efficiency of use be improved?

Joint management of surface-water and 

ground-water storage is an especially efficient

scheme of management. But management 

including legal principles fails to permit this 

because stored ground water cannot be reserved 

for withdrawal solely by intended users.

New techniques have been proposed, such as 

rain-making, salt-water rectification, and evaporation suppression. We could review and 

assess their place in the future. But at long last 

this conclusion is inescapable: There is no 

panacea for problems; no hydrologic magic will 

substitute for scientifically sound hydrologic 

management.

THE ULTIMATE CRITICAL PROBLEM

Many means are available for conserving 

water supplies and making less wasteful use of 

them. Rather than add to the voluminous 

literature on this topic, it seems to be more 

important to clinch one fact: The ultimate 

critical water problem of the United States 

and of the world is ground-water supply. This 

is fairly obvious from table 2; the rough estimates 

of which are sufficiently realistic to warrant sober 

reflection.

The yearly disposition of rainfall on the 

United States probably is somewhat more than 

one-third each to runoff and soil moisture, and 

about one-fourth to ground-water recharge. 

Each part is the total we can count on having 

perennially for human requirements. Eventually, 

our water use will approach the total recoverable from precipitation; we will convert salt 

water to fresh on a large scale; and we may 

have some control of the weather to increase 

precipitation. Meantime, we will have drawn 

heavily on the accumulated reserve of groundwater storage. As is shown by table 2, ground 

water in natural storage is our principal reserve 

in fresh water, and for a long time to come the 

extent to which we can conserve and manage 

that reserve will be the deciding factor in 

development.

11
REFERENCES CITED

Barksdale, H. C, Greenman, D. W., Lang, S. M., Hilton, G. S., 

and Outlaw, D. E., 1958, Ground-water resources in the tristate region adjacent to the lower Delaware River: New 

Jersey Dept. Conserv. and Econ. Dcvel., Div. of Water 

Policy and Supply (in cooperation with the U. S. Geol. 

Survey), Spec. Kept. 13, 190 p., 24 figs., 1 pi.

Baumann, Paul, 1953, Experiments-with fresh-water barrier to 

prevent sea water intrusion: Am. Water Works Assoc. Jour., 

v. 45, p. 521-534.

Fox, C. S., 1952, Water; a study of its properties, its constitution, 

its circulation on the earth, and its utilization by man: New 

York, the Philosophical Library, Inc., 148 p.

Poland, J. F., and Davis, G. H., Subsidence of the land surface 

in the Tulare-Wasco (Delano) and Los Banos-Kettleman Gty

area, San Joaquin Valley, California: Am. Geophys. Union 

Trans., v. 37, p. 287-296.

Shantz, H. L., 1956, History and problems of arid lands development in White, G. F. [ed.], The future of the arid lands: 

Am. Assoc. Adv. Sci., pub. no. 43, p. 3-25.

Sherrill, D. W., 1958, High Plains irrigation survey: Texas Agri. 

and Mech. College, Extension Service [duplicated rept.], lip.

Sundstrom, R. W., 1957, Our underground water: Address to 

Texas Women's Forum on water, Belton, Tex., February 9.

Texas Board of Water Engineers, Corps of Engineers, Soil Conservation Service and Bureau of Reclamation Joint Report, 

1958, Water developments and potentialities of the State of 

Texas: U. S. 85th Cong., 2d sess., Senate Doc. Ill, 175 p. 

16 maps.

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INT.DUP..D.C.63-

U.S. GOVERNMENT PRINTING OFFICE : 1967 0 272-011