1

The Story of Ground Water in the 

San Joaquin Valley, California

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GEOLOGICAL SURVEY 

CIRCULAR 459

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JB^^jj^^^SH REPARED IN COOPERATION WITH THE CALIFORNIA DEPARTMENT OF WATER RESOURCES
The Story of Ground Water in the 

San Joaquin Valley, California

By R. H. Dale, J. J. French, and H. D. Wilson Jr.

Prepared in cooperation with the California Department of Water Resources

GEOLOGICAL SURVEY CIRCULAR 459

Washington 

1964
United States Department of the Interior

STEWART L. UDALL, SECRETARY

Geological Survey

THOMAS B. NOLAN, DIRECTOR

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

Page Page

The underground lake of San Joaquin Investigating ground water in the

Valley ____________________________ 1 alluvial fans ____________________ ?

Future of the lake____________________ 2 Mapping the water table ______________ ?

The sand and gravel framework of the Understanding the hydrologic system __ 8

lake ______________________________ 5 Quality of water _____________________ 9

The river fans_______________________ 6 Conclusion__________________________ 9

ILLUSTRATIONS

Page 

Figure 1. Lake Isabella ___________________________________________________________ 1

2. Kern River Canyon ______________________________________________________ 2

3. Mouth of Kern Canyon ___________________________________________________ 2

4. The river in Indian times.________________________________________________ 3

5. The river today _________________________________________________________ 3

6. The effect of increased area-wide pumping on the water level in a well near

Wasco, Calif _____________________________________________ 4

7. The hydrologic cycle-___-_-________-_______-_-_______________-_____-_-___ 5

8. Generalized shape of the embayment of the ancient Central Valley of

California ____________________________________________________________ 5

9. Debris from surrounding mountains progressively filled up the embayment,

forcing out the sea _______ _____________________________________________ 6

10. An idealized alluvial fan__________________________________________________ 6

11. Bluffs along Panorama Drive _____________________________________________ 6

12. The pumping test ________________________________________________________ 8

13. Measuring the water level in an irrigation well _____________________________ 9

14. Operation of a water-level recorder _______________________________________ 9

15. Water levels in wells ____________________________________________________ 10

16. Carbon dioxide tanks at a well near Oildale ________________________________ 10

17. Ground-water work by the U.S. Geological Survey in San Joaquin Valley _______ H

III
The Story of Ground Water in the San Joaquin Valley, California

By R. H. DaleJ. J. French, and H. D. Wilson, Jr.

THE UNDERGROUND LAKE OF SAN JOAQUIN 

VALLEY

The underground lake of the San Joaquin 

Valley stretches from the Sierra Nevada to 

the Coast Ranges and from the Tehachapi 

Mountains to the San Francisco Bay area. 

Fantasy? No, fact! The San Joaquin Valley 

is really like a huge lake that is clogged with 

alluvium (clay, silt, sand, and gravel). The 

amount of water in this lake is tremendous 

93 million acre-feet contained in the upper 

200 feet alone enough to cover the entire 

10,000-square-mile valley with a layer of 

water 14^ feet deep. In comparison, Lake 

Isabella (fig. 1) at full capacity holds only 

570,000 acre-feet; thus, the "lake" in the San 

Joaquin Valley holds more water than 163 

Lake Isabellas!

This lake is not a mysterious subterranean 

cavern complete with rushing channels, 

whirlpools, sightless fish, and the like. It is 

a large porous body of loosely packed sand 

and gravel that is saturated with water. To 

get an idea of what this lake is like, fill a 

bucket brimful with dry sand and begin pouring water into it. You'll be surprised how 

much water you can pour into this bucket. 

This is also true of the alluvial fill of the San 

Joaquin Valley.

But where does the water come from to fill 

this alluvium? The answer is stated in a 

court decision that regarded the San Fernando 

Valley as a "great lake filled with loose detritus, into which the drainage from the 

neighboring mountains flows, and the outlet 

of which is the Los Angeles River." The San 

Joaquin Valley is very similar. In the southern part of the valley, for example, the major 

drainage from the mountains is the Kern River, which begins high on the slopes of Mount 

Whitney and then winds its tortuous 155-mile

journey to recharge the underground lake of 

the San Joaquin Valley. Melting snow in the 

mountains is the chief source of water; most 

of the runoff is in late spring and early summer. The water flows over very hard crystalline granite from its source to the mouth 

of Kern Gorge (fig. 2), and virtually none 

seeps into the ground. However, once the 

river bursts out of the confining gorge, it 

flows over highly permeable sand and gravel 

that soak up the water just as our "full" 

bucket of sand did. This water becomes 

ground water a part of the 93 million acrefeet lake and continues its journey seaward 

through the pores between the sand grains.

Replenishment of recharge of the "lake" 

similarly occurs along the other streams of 

the valley, such as the Tule, Kaweah, Kings, 

San Joaquin, Merced, Tuolumne, and Stanislaus Rivers. For simplicity, however, the 

hydrologic discussion that follows is limited 

to the Kern River area (fig. 3).

Figure 1. Lake Isabella.
THE STORY OF GROUND WATER IN THE SAN JOAQUIN VALLEY. CALIFORNIA

Figure 2. Kern River Canyon.

Figure 3. Mouth of Kern Canyon.

FUTURE OF THE LAKE

The average annual runoff in the Kern 

River is estimated at about 700,000 acre-feet. 

That is almost three-fourths of a million 

acre-feet of water that pours into the Kern 

County section of the "lake" each year. Yet 

in this same area about 2 million acre-feet 

of ground water is pumped annually three 

times the flow of the river! Much of the 

ground water, however, returns to the underground reservoir.

Back in the days of the Indians (fig. 4) the 

river and the "lake" had a nice sort of working agreement. In dry years when the river

was low, the "lake" still contained plenty of 

water to keep much of the valley green. In 

fact the valley generally was so brimfull of 

water that the ground water spilled out into 

two visible surface lakes, Kern and Buena 

Vista. In wet years when the river brought 

in more water than usual, it simply evaporated or flowed over the low barrier to the 

north into the San Joaquin River and on out 

to the sea (fig. 5).

Along came the white men who drilled 

wells and dug canals to spread the water 

around. This spreading of water over the 

surface of the ground permitted a steady 

agricultural growth that required more and 

more water. Eventually, as more water was 

spread, less reached the two surface lakes. 

This increase in water use did not create 

much of a problem until about 1946. Until 

then the amount of ground water pumped was 

about the same as the recharge from the 

river. The postwar period brought about a 

tremendous increase in the amount of pumping for irrigation, and as shown by figure 6, 

water levels declined as the pumpage of 

ground water increased.

With about 2 million acre-feet of ground 

water being pumped yearly, water levels in 

wells are declining in much of the area. 

What is going to happen? Unless the present 

trend is changed, water levels would continue 

to decline and the cost of pumping would increase. Will this happen? and can something 

be done? Two possibilities come to mind: 

using the present supply of water more efficiently or providing a new supply. Greater 

use of ground-water storage would be one 

means of reducing the present water loss by 

evaporation. Some large scale water-spreading experiments to increase ground-water 

storage have been carried out in the Kern 

River area, but serious problems are involved.

The rainfall might be increased through 

cloud seeding, but that is an uncertain operation. The most practical solution would be 

to import new supplies of water, and the State 

of California and the U.S. Bureau of Reclamation have offered specific solutions 

namely large imports via canals.

Many things can be done to alter the trend, 

but the most effective choice depends on a 

full understanding of the hydrologic system 

at hand. For this reason the U.S. Geological
FUTURE OF THE LAKE

Figure 4. The river in Indian times.

Figure 5. The river today.

Survey is investigating the Kern River fan 

area and other parts of the San Joaquin Valley. In each investigation the goal is to understand the geology and hydrology of the 

area so choices and decisions may be made 

intelligently by those who must make them.

To understand how the desired objectives 

might be accomplished one must have a general basic knowledge about water and specific knowledge about the geology and hydrology of the alluvial fans in which the ground 

water occurs. First, water is not consumed
THE STORY OF GROUND WATER IN THE SAN JOAQUIN VALLEY. CALIFORNIA

300 1935 1937 1939 1941 1943 1945 1947 1949 1951 1953 1955 1957 1959 

Figure 6. The effect of increased area-wide pumping on the water level in a well near Wasco, Calif.

1961

like coal or oil, water is employed. Also, 

unlike petroleum, ground water is not stationary. Petroleum, except for a moderate 

amount of movement, is trapped and is stationary in a body of rock, the pores of which 

are saturated with crude oil. Ground water 

is not commonly trapped, but rather it is 

constantly on the move from places of recharge to places of discharge. Where trapped, it is generally known as connate water 

and is commonly of poor quality and thus will 

not be suitable for domestic or irrigation 

uses.

The surface water flowing down the Kern 

River, for example, is in one phase of the 

hydrologic cycle. After it leaves the Kern 

Gorge it infiltrates into the ground and becomes ground water (another phase in the 

cycle). The movement of the ground water is 

in accordance with the same law that applies 

to surface water: it seeks the lowest level 

possible. These low areas may be natural 

such as the low central part of the valley including Buena Vista and Tulare Lakes toward 

which most of the ground water of the area 

eventually moved prior to man's interference

with the hydrologic cycle or they may be man 

made, as in the vicinity of a pumped well 

where the water level is drawn down by 

pumping.

Under natural conditions the flow of the 

ground water didn't stop at Buena Vista Lake 

because there is a still lower level the 

ocean. The flowing water collected at Buena 

Vista Lake continued underground down the 

San Joaquin Valley past Tulare Lake and the 

San Joaquin River to San Francisco Bay, 

where the surface water and the ground water discharged into the sea. From there it 

eventually evaporated into the atmosphere, 

was transported as clouds, and precipitated 

as rain or snow to begin the cycle all over. 

This is a constantly occurring and neverending sequence called the hydrologic cycle 

(fig. 7).

This underground flow is present throughout part of the San Joaquin Valley, but in the 

example area of Buena Vista Lake the water 

levels have been lowered by pumping so that 

now there is no underground flow from here 

to the ocean.
THE SAND AND GRAVEL FRAMEWORK OF THE LAKE

Figure 7. The hydrologic cycle.

Figure 8. Generalized shape of the embayment of the ancient 

Central Valley of California.

THE SAND AND GRAVEL FRAMEWORK OF THE 

LAKE

Let's take a closer look at the underground 

lake. What is it and how did it get there ?

The San Joaquin Valley is a great structural trough (fig. 8) or downwarp in the 

earth's crust, having a bedrock floor of hard 

granitic and metamorphic or altered rocks. 

When it assumed its general shape, about 60 

million years ago, the bottom of the trough 

was below the level of the sea, creating a 

huge embayment connected to the ocean. The 

rivers from the mountains to the east and 

west brought down great amounts of clay, 

silt, sand, and gravel and deposited them in 

this salt-water bay. These sediments were 

eventually consolidated into shale, sandstone, 

and conglomerate that retained some salt 

water and trapped large reserves of petroleum. The low rounded hills, Sharktooth, 

Pyramid, and Round Mountain, which border 

the valley, are surface outcrops of these 

consolidated rocks.

The debris from the rivers (fig. 9) continued to fill the valley, and as more sediments 

were added the embayment became shallower 

and the sea withdrew.
THE STORY OF GROUND WATER IN THE SAN JOAQUIN VALLEY. CALIFORNIA

Figure 9. Debris from surrounding mountains progressively filled 

up the embayment, forcing out the sea.

Deposition of sediments from the rivers, 

however, did not stop when the sea was 

crowded out. As long as rain and snow melt 

drained from the mountains, debris was carried along and deposited in the valley, and 

this deposition of debris is occurring even 

today.

The latest of these accumulations are the 

beds of clay, silt, sand, and gravel that are 

penetrated today by wells drilled in the exploration for water. They are like the earlier underlying sediments but are not yet 

consolidated into rock. It is these latest deposits, fed by the fresh-water streams from 

the mountains, that make up the "lake" from 

which usable ground water is obtained.

THE RIVER FANS

The Kern and other rivers, by serving as 

transporters of sediment, have done most of 

the filling and building in the valley. During 

times of heavy runoff from melting snow, for 

example, the rivers carry much debris. As 

the water careens down the steep, narrow 

gorge, the power to carry this load becomes 

very great. Any casual traveler to the gorge 

of the Kern River has noticed the huge boulders which were moved there by the power 

of the river (figs. 2 and 3). Shooting out of 

this steep canyon and onto the wide flat expanse of the San Joaquin Valley, the river, no 

long confined in its narrow chute, spreads 

out and loses much of its velocity. As the 

velocity is reduced the load is dropped right 

at the mouth of the gorge. Sand and gravel 

clog the river, forcing it to cut new channels 

just as in a delta. Each new channel spreads

the finer grained debris farther into the valley to form a fan-shaped deposit (fig. 10) of 

clay, silt, sand, and gravel a process that 

has been going on for many million years. 

Today the Kern fan reaches from the Kern 

Gorge to the Elk Hills near Tupman.

About a million years ago the beginning 

of the Pleistocene epoch or great ice age the 

Sierra Nevada was uplifted. This uplift tilted 

the alluvial fans slightly and increased the 

gradient or steepness of the rivers. This 

steepening caused the rivers to flow more 

swiftly and gave them greater erosive power. 

With its new power the Kern River, for example, began to cut into the old alluvial fan 

and produced the steep bluffs along Panorama 

Drive northeast of Bakersfield (fig. 11). A 

little farther downstream the river again

Figure 10. An idealized alluvial fan.

Figure 11. Bluffs along Panorama Drive. At right, is the old fan 

surface. Uplift in mountains renewed the power of the river enabling it to cut into the old fan.
MAPPING THE WATER TABLE

broke away from the bluffs of the old alluvial 

fan and swept out into the valley, where a 

new alluvial fan was formed on the surface of 

the old one.

The other rivers of the valley also have 

been building alluvial fans, and they have 

overlapped, so that the whole valley floor today is made up of these merged, or coalescing, alluvial fans.

Searching above and below the land surface, the Geological Survey seeks information 

about the ground water and materials through 

which it moves. Where is the ground water? 

How far below the surface is it? How much 

is there? How much can be removed? How 

and where does it move? How much can be 

replaced? Is it of good quality? These are 

some of the many questions asked. Geologic, 

hydrologic, and chemical studies provide 

these answers.

INVESTIGATING GROUND WATER IN THE 

ALLUVIAL FANS

Geologic maps, which show the materials 

exposed on the surface, indicate the areas in 

which the pore spaces of sedimentary rocks 

are large enough to store water. In effect, 

these maps delineate the upper surface of the 

ground-water reservoir fans whose thickness 

can be determined from study of well logs.

To find out how much water the alluvial 

fans hold it is necessary to estimate how 

much pore space there is in relation to the 

total volume of the ground-water reservoir. 

Remember our sand-filled bucket? The water poured into the bucket infiltrated into 

millions of tiny air spaces or pores between 

the sand grains. The ground water in the alluvial fan does the same thing, only on a 

much larger scale. There are billions and 

billions of pores in the fan, each capable of 

storing water.

The pore space can be estimated on the 

basis of laboratory examination of sand-grain 

samples from many different locations and 

from many different depths. These samples 

are collected from bore holes drilled specifically for exploration, or they may be acquired more economically during the drilling 

of a water-supply or oil well. The size and 

shape of the grains are an indication of the 

pore spaces between them. Where the grains 

are large, the pore spaces are large. Where 

the grains are very small, as in clay, the

pore spaces may be so small that the free 

flow of ground water is restricted.

Water contained in the pore space, however, is not all recoverable. If we were to 

punch a hole in the bottom of our sand-filled 

bucket, we would drain off a little less water 

than we poured into it. Why? Because very 

thin films of water, resisting the pull of gravity, will cling to the surface of the sand 

grains. When you wash your hands, some of 

the water clings to your skin in the same 

manner. They must be dried with a towel before all the water can be removed. Gravity 

is not enough to pull the film from either our 

hands or the sand grains. The amount of water to be yielded from an aquifer, then, is 

something less than the total water stored 

between the sand grains.

The yield characteristics of the alluvialfan deposits may be studied in the laboratory 

using samples of the materials, or they may 

be studied in the field using a pumping-test 

procedure on wells (fig. 12). In this procedure one well is pumped for a period of 

time while water-level drawdowns are measured in other wells nearby. Information 

gained from such tests is useful in selecting 

new well sites, in planning multiple-site developments so as to avoid mutual, interference between pumping wells, in planning optimum pumping schedules for existing well 

fields, and for locating and identifying hydrologic features that may contribute to or withdraw water from the system.

MAPPING THE WATER TABLE

If all the pore spaces in the alluvial fan 

were filled with water, we would have a vast 

swampy area, and in the past there were 

large swampy areas on the floor of the valley. For this reason the early Spanish explorers called the San Joaquin Valley the 

valley of the tules, or bull rushes.

Now, of course, there is no swamp. This is 

because the alluvial fans do not contain all 

the water they are capable of holding. This 

brings up the question how much water is in 

an alluvial fan at a given time ? To find the 

answer the Geological Survey measures the 

water level in wells.

When water infiltrates into the ground from 

the rivers, it percolates downward through 

the empty pores until it reaches the zone
THE STORY OF GROUND WATER IN THE SAN JOAQUIN VALLEY, CALIFORNIA

Pumped well

Successive water 

levels at various 

times during 

pumping

Observation wells

Figure 12. The pumping test.

where the pores are already filled with water. As more water trickles downward the 

level of filled pores rises, just as adding water to any container will raise its water 

level. This upper level of saturation is 

called the water table, and its surface can be 

shown graphically by preparing a contour 

map that is based on water-level measurements in wells.

Of course, the water table is not static. 

Water put in the ground during rainy seasons 

raises the water table and pumping for human use lowers the water table. These 

changes are continuous, and the level in any 

well can change from day to day even minute to minutel

Some farmers, like Elie Crettol (fig. 13) 

have made monthly measurements of the 

depth to water in their wells for many years, 

providing an invaluable long-term record of 

water-level fluctuations. The U.S. Geological 

Survey, California Department of Water

Resources, and other government and private 

agencies make similar measurements and 

also install and maintain water-level recorders, similar to the one shown in figure 14, to 

provide a continuous record of fluctuations in 

key wells. The information from water-level 

measurements is used to make the waterlevel maps that show changes in ground-water storage, depth to water, and the direction 

of movement.

UNDERSTANDING THE HYDROLOGIC SYSTEM

In most areas of the San Joaquin Valley, 

ground water does not occur as simply as it 

does in the sand-filled bucket. Generally 

there are two or more water-bearing zones 

or aquifers, commonly sand and gravel, separated by beds of clay that restrict the 

movement of water from one aquifer to another. Water-level measurements and well 

data collected from individual well owners 

permit the study of the relation of one aquifer to another.
CONCLUSION

Figure 13. Measuring the water level in an irrigation well. Elie 

Crettol, Wasco farmer, has made monthly measurements of 

this well for the past 30 years.

Pen

Recorded graph of 

water-table fluctuations

Clock

Record chart on 

revolving drum

Drum revolves with 

cable wheel

 /: ' ' '"- \ Land" surface"/.': 

: P.:-.-'V.'~-'-

.o . " <p- - . 

' \\tell casing /. 0; \ ;o -. .-

 Perforations-

= . - o - /

' Water-table' ' ' 

: c> : ' '.

-Cable : >O "

Counterweight.

f* .' 
.: 

.-0__ 14. C^ejsition oi a water lev si recorder.

Figure 15 depicts a ground-water situation 

common in the San Joaquin "Valley. Static 

water levels in all three wells shown are different because the wells tap different aquifers. For the same reason water-level fluctuations in these wells will differ also. Well 

3 is of particular interest because its type of 

construction introduces the problem of 

"falling water,"which may greatly reduce the

efficiency of the pump. In addition, it permits the lower zone of good-quality water to 

be contaminated by poor-quality water from 

the shallow zone. Because large withdrawals 

have lowered water levels in many deep aquifers, the situation depicted in figure 15 is 

not uncommon in the San Joaquin Valley.

QUALITY OF WATER

"Water, water, everywhere, and not a drop 

to drink," is an appropriate saying for the 

thirsty man who is adrift upon the open sea. 

It is also appropriate for a final consideration of our ground-water reservoir, because, 

unless the water is of suitable quality for our 

intended use, it is not worth developing. 

Some forms of contamination are harmless, 

others merely inconvenient or unpleasant, 

but in those areas in which only waters of 

marginal quality exist, development can be 

costly (fig. 16).

The U.S. Geological Survey collects samples of water for analysis from many pumping wells in the project area. Interpretation 

of these analyses permits the Survey to delineate the areas in which the water is of 

poor chemical quality and to identify the nature and source of the contamination.

CONCLUSION

This is the story of the San Joaquin "lake" 

and the U.S. Geological Survey's and your 

own interest in it. This tremendous reservoir of water is the life blood of the valley, 

but like the blood in our body, it must be replenished. When something happens to our 

blood supply, we need a transfusion. The San 

Joaquin Valley needs a transfusion now, and 

through pumping tests, water-level measurements, geologic, hydrologic, and chemicalquality studies, the necessary data on which 

to base intelligent water-management decisions will be accumulated.

Reports on these findings have been prepared for several areas in the San Joaquin 

Valley (fig. 17). Those now available pertain 

to the Edison-Maricopa, Avenal-McKittrick, 

and Mendota-Huron areas. More general reports covering the whole valley are available 

also. Studies in progress in 1961 include the 

Terra Bella-Lost Hills, Kern Fan, Kings 

Fan, and Kaweah-Tule areas. It is the joint 

plan of the U.S. Geological Survey and the
10 THE STORY OF GROUND WATER IN THE SAN JOAQUIN VALLEY. CALIFORNIA

Note* When no wells ore pumping,water will drain 

from aquifer A into aquifer B through well 3. 

This well pierces the confining bed and is perforated in both aquifers. Well 1 also pierces the 

confining bed but is not perforated in aquifer A.

->f cloy and «»» -J^lr-^ - '

oodsquQlitv^flwate

Figure 16. Carbon dioxide tanks at a well near Oildale. The 

gas is injected into the well to prevent calcium deposits from 

choking off the flow of water.

State of California to initiate studies in additional areas of the valley.

Investigations of this type are invaluable 

for long-range, Statewide planning, but to the 

farmer, rancher, and ordinary citizen, they 

have even more tangible worth. Among the 

findings of benefit to you are accurate up-todate information on the rate of water-table 

decline in your area, present position and 

average yearly rise and fall of the water table, chemical quality of the waters in various 

localities and at various depths, expected 

yield of wells, and information on correct 

depths for best yield in various areas.

More information may be obtained by 

writing for the book "Publications of the Geological Survey," address: Superintendent of 

Documents, Government Printing Office, 

Washington, D. C. 20402. This book lists all 

publications on water investigations by the 

Geological Survey. Most of the California 

investigation reports are available at local 

public libraries.
CONCLUSION 11

122'

INVESTIGATIONS COMPLETED OR IN PROGRESS

I.San Joaquin Reconnaissance,U.S.G.S.Water 

Supply Paper 1469

2. Mendota-Huron Area,U.S.G.S. Water Supply 

Paper 1360-G

3. Avenal-McKittrick Area, U.S.G.S. Water 

Supply Paper 1457

4. Use of ground-water reservoirs,U.S.G.S. 

Water Supply Paper 1618

5. Los Banos-Kettleman City Subsidence, Openfile report

6. Edison-Maricopa Area,U.S.G.S. Water Supply 

Paper 1656

7. Terra Bella-Lost Hills Area, Open-file report

8. Tulare-Wasco Area, Subsidence (in progress)

9. Kern River Fan (in progress)

10. Kaweah-Tule Area (in progress)

Figure 17. Ground-water work by the U.S. Geological Survey in San Joaquin Valley.

INT.DUP.,D.C.