Ground-Water and Surface-Water 

Relations along the Mojave River, 

Southern California

By GREGORY C. LINES

U.S. GEOLOGICAL SURVEY 

Water-Resources Investigations Report 95-4189

Prepared in cooperation with the 

MOJAVE WATER AGENCY

ON1 4

00

O

cs

Sacramento, California 

1996
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute 

endorsement by the U.S. Geological Survey.

For addtional information write to:

District Chief 

U.S. Geological Survey 

Federal Building, Room W-2233 

2800 Cottage Way 

Sacramento, CA 95825

Copies of this report can be purchased 

from:

U.S. Geological Survey 

Earth Science Information Center 

Open-File Report Section 

Box 25286, Mail Stop 417 

Denver Federal Center 

Denver, CO 80225
CONTENTS

Abstract ...................................................................................................................._^ 1

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

Problem and Objectives ............................................................................................................................. 1

Acknowledgments...................................................................................................................................... 3

The Mojave River ............................................................................................................................................... 3

Drainage-Basin Characteristics .................................................................................................................. 3

History of Gaging Stations ......................................................................................................................... 4

Streamflow from Headwaters .................................................................................................................... 8

Streamflow Along Main Stem ................................................................................................................... 11

Ungaged Tributary Streams ....................................................................................................................... 16

Manmade Discharges to River ................................................................................................................... 20

The Flood-Plain Aquifer ..................................................................................................................................... 22

Lithology, Thickness, and Extent .............................................................................................................. 22

Hydraulic Characteristics ........................................................................................................................... 23

The Water Table ......................................................................................................................................... 24

Historical Pumpage .................................................................................................................................... 25

Ground-Water Discharge to River ...................................................................................................................... 26

Ground-Water Recharge from River ................................................................................................................... 31

Streamflow Depletion ......................................................................................................................................... 35

Factors Controlling River-Aquifer Interaction .................................................................................................... 40

Potential for Artificial Recharge ......................................................................................................................... 40

Conclusions ................................................................. 41

References Cited ..................................................................................................................................... 42

FIGURES

1. Map showing the Mojave River drainage basin ...................................................................................................... 2

2,3- Graphs showing:

2. Annual precipitation in the headwaters of the Mojave River basin, water years 1931-94............................ 4

3. Cumulative departure from mean precipitation in the headwaters of the Mojave River basin,

water years 1931-94.................................................................................................................................... 4

4. Map showing gaging stations, channel-geometry sites, points of manmade discharge to river, and distance

downstream from Mojave River Forks Reservoir ............................................................................................... 5

5-7. Photographs showing:

5. Gaging station 10261500, Mojave River at Lower Narrows, near Victorville, January 31,1995 .................... 6

6. Gaging station 10262500, Mojave River at Barstow, January 18, 1993............................................................ 7

7. Gaging station 10263000, Mojave River at Afton, January 17, 1993 ............................................................... 8

8-14. Graphs showing:

8. Flow duration for Deep Creek at gaging station 10260500 (water years 1931-71 and 1972-94) and for 

West Fork Mojave River at gaging stations 10261000 and 10260950 (water years 1931-71 and 

1975-94)..............................................» 9

9. Total annual inflow to main stem of Mojave River from the headwaters, water years 1931-94....................... 10

Contents III
10. Exceedance probabilities and recurrence intervals for total annual inflow to main stem of Mojave River

from the headwaters...................................................................................................................................... 10

11. Daily mean discharge at gaging station 10261500, Mojave River at Lower Narrows, near Victorville,

water years 1931-94...................................................................................................................................... 11

12. Daily mean discharge at gaging station 10262500, Mojave River at Barstow, water years 1931-94............... 12

13. Daily mean discharge at gaging station 10263000, Mojave River at Afton, water years 1930-52,

1953-78, and 1981-94................................................................................................................................... 13

14. Flow duration for the Mojave River near Victorville (gaging station 10261500), at Barstow

(gaging station 10262500), and at Afton Canyon (gaging station 10263000) during selected periods........ 14

15. Diagram showing reaches of the main stem of the Mojave River that had streamflow during water years

1992-94.................................................................................................^ 15

16. Photograph showing channel-geometry measurement at site 10 on Bell Mountain Wash...................................... 18

17,18. Graphs showing:

17. Relation between channel width and annual mean discharge at 29 gaging stations in Mojave Desert

region ............................................................................................................................................................ 20

18. Estimated annual discharge of tributary streams along the main stem of the Mojave River and ratio of 

annual to average discharge of the Mojave River at Barstow (gaging station 10262500), wrter years 

1931-94 ........................................................................................_^^ 21

19. Photograph showing aerial view of California Department of Fish and Game fish hatchery and discharge to

Mojave River, February 25, 1993 ........................................................................................................................ 22

20. Graph showing wastewater and fish hatchery discharges to the Mojave River, water years 1949-94..................... 22

21. Map showing altitude of the water table in the flood-plain aquifer, November 1991, and estimated specific

yield ............................................._ 23

22. Profile showing altitude of Mojave River streambed and altitude of the water table, November 1991 and

March 1993 ................................................................... 24

23. Graph showing water levels in flood-plain aquifer at wells along the upper and middle main stem of the

Mojave River, April 1992-September 1994 ....................................................................................................... 26

24. Diagram showing idealized streamflow-hydrograph separation.............................................................................. 27

25-28. Graphs showing:

25. Estimated stormflow and base flow for the Mojave River at Lower Narrows (gaging station 10261500)

during water year 1982 ................................................................................................................................. 28

26. Base flow of Mojave River near Victorville (gaging station 10261500) during water years 19CO-01,

1904-05, and 1931-94....................^ 29

27. Base flow of Mojave River at Afton Canyon (gaging station 10263000) during water years 1930-32,

1953-78, and 1981-94................................_ 30

28. Cumulative annual recharge to the flood-plain aquifer from the Mojave River along the upper and middle 

main stem during water years 1931-94 and along the lower main stem during water years 1931-32 

and 1953-94 .............................................._ 33

29. Map showing areas of water-table rise along the Mojave River, November 1992 to March 1993.......................... 34

30-35. Graphs showing:

30. Streamflow depletion by a well that is pumped continuously for one month 720 feet from a stream.............. 35

31. Streamflow depletion by a well that is pumped continuously for 60 months for various stream-depletion

factors and distances from a stream ............................................................................................................. 36

32. Estimated streamflow depletion for Mojave River at Afton Canyon (gaging station 10263000) during

water years 1985-87 ..................................................................................................................................... 37

33. Estimated streamflow depletion for Mojave River at Lower Narrows (gaging station 10261500) during

water years 1948-50 ..................................................................................................................................... 38

34. Streamflow depletion of Mojave River at Afton Canyon (gaging station 10263000) caused mrinly by

evapotranspiration during selected water years............................................................................................ 39

35. Streamflow depletion of Mojave River at Lower Narrows (gaging station 10261500) caused b v groundwater pumping and evapotranspiration during selected water years ........................................................... 39

36. Photograph showing Mojave Water Agency's release of imported water to upper main stem of Mojave

River near river mile 4, August 29, 1994 ............................................................................................................ 41

IV Contents
TABLES

1. Annual mean discharge and channel width at 29 gaging stations in the Mojave Desert region........................... 17

2. Channel width and estimated annual mean discharge and runoff in selected ephemeral tributary

streams to the Mojave River ............................................................................................................................. 19

3. Estimated annual recharge to the flood-plain aquifer from the Mojave River, water years 1931-94..................... 32

CONVERSION FACTORS, DEFINITION OF WATER YEAR, AND VERTICAL DATUM

Multiply By To obtain

acre 0.4047 hectare

acre-foot (acre-ft) 1,233 cubic meter

acre-foot per year (acre-ft/yr) 0.001233 cubic hectometer per year

o

cubic foot per second (ft /s) 0.02832 cubic meter per second

foot (ft) 0.3048 meter

foot squared per day (ft2/d) 0.0929 meter squared per day

gallon per minute (gal/min) 0.06308 liter per second

inch (in.) 25.4 millimeter

mile (mi) 1.609 kilometer

f\

________square mile (mi )_____2.590_______square kilometer__________

Definition of Water Year

A water year is the 12-month period October 1 through September 30. The water year is designated by 

the calendar year in which it ends. Thus, the water year ending September 30,1994, is called water year 19^4.

Vertical Datum

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 a geodetic 

datum derived from a general adjustment of the first-order level nets of the United States and Canada, forme'ly 

called Sea Level Datum of 1929.

Contents
GROUND-WATER AND SURFACE-WATER 

RELATIONS ALONG THE MOJAVE RIVER, 

SOUTHERN CALIFORNIA

By Gregory C. Lines

Abstract

The Mojave River and the associated floodplain aquifer are important water supplies in the 

Mojave Desert of Southern California. The river 

and aquifer, in many areas, are in excellent 

hydraulic connection, and when flow conditions 

change in one, the other almost always is affected.

To better understand these relations, 

records of gaging stations were analyzed to determine the frequency and duration of historical 

streamflow. Annual ground-water recharge from 

the river during water years 1931-94 was estimated from an accounting of all streamflow 

accretions and losses. Annual recharge ranged 

from about 24,000 to 460,000 acre-feet and averaged about 96,000 acre-feet. Channel-geometry 

regression techniques were used to estimate runoff of ungaged ephemeral streams that are tributary to the river. Water-table and gravity changes 

were used to estimate specific yield of the aquifer 

and changes in ground-water storage following 

storm runoff during the winters of 1992-94. In 

addition, streamflow hydrographs were analyzed 

to estimate both ground-water discharge to the 

river (base flow) and historical streamflow depletion caused by ground-water pumping and evapotranspiration. Ground-water pumpage from the 

flood-plain aquifer was about 120,000 acre-feet 

during water year 1994. Annual evapotranspiration along the river probably ranges from about 

10,000 to 30,000 acre-feet.

Factors controlling the exchange of water 

are identified in this report on the basis of the 

historical response of the river-aquifer system to 

stress (stormflows and pumping). Also identified are reaches of the river that are hydraulically suitable for artificial recharge.

INTRODUCTION

Problem and Objectives

The Mojave River (fig. 1) has long been the 

"lifeblood" of the Mojave Desert. For the Vanj'ume 

and Chemehuevi Indians who lived along the river, 

water was the critical element for survival. River 

water and the vegetation that grew on the flood plain 

also were vital to the Spanish explorers of the late 

1700's, the American trappers of the early ISOC's, 

and the thousands of pioneers who later followed the 

Spanish Trail and Mormon Road (Walker, 1986).

By the 1880's, boosted by the Calico mining 

boom and completion of a transcontinental railroad, 

Euro-American settlement along the Mojave River 

was expanding (Earle, 1992). But with a heavy 

reliance on river water and natural subirrigatior, 

agriculture along the river was devastated by th*3- 

drought of 1894-1904. With the advent of combustion engines (and later, electric motors) to piwer 

pumps, a "new" source of water became availaHe. 

Instead of having to rely on the flow of the rive" and 

rainfall, users obtained large quantities of water from 

wells tapping sand and gravel beneath the flood plain 

(flood-plain aquifer). It seemed that the problems 

associated with an unpredictable water supply Hd 

been solved.

Introduction 1
However, it soon became apparent from the 

fluctuation of water levels in wells that the replenishment of the flood-plain aquifer was dependent on 

seepage from the river (Thompson, 1929, p. 490-494) 

and that this new supply of water thus was limited. As 

pumpage increased, the relation between the river and 

aquifer became even more apparent. Reaches of the 

river previously having perennial flow now flowed 

only in response to storm runoff. As the 20th century 

comes to a close and the demand for water continues 

to increase, the ground-water system in the Mojave 

River basin is recognized as being in an overdraft 

condition. Water rights in the basin currently (1995) 

are being determined by adjudication.

Future management of the water resources and 

the implementation of measures to mitigate the overdraft conditions will benefit from a greater understanding of ground-water and surface-water relations 

along the Mojave River. In 1991, the Mojave Water 

Agency and the U.S. Geological Survey (USGS) 

began a 4-year cooperative study with the following 

objectives:

(1) Determine the sources and quantities of historical ground-water recharge and discharge 

along the Mojave River,

(2) Determine the effects of ground-water pumping on flow in the river (streamflow depletion),

(3) Determine the hydraulic factors controlling 

interaction between the river and the floodplain aquifer, and

(4) Determine which reaches of the river are 

hydraulically suitable for artificial recharge.

35°30' 117°30' 115°30'

34°30'

EXPLANATION

Boundary of Mojave River drainage basin

Boundary of upper, middle, and lower subdivisions of Mojave River main stem

Gaging station 

Dry lake (playa)

.

A/Won 

/ ; Canyon

Mojave River 

Basin

Figure 1. The Mojave River drainage basin.

2 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
The study area includes the 100-mile reach of 

the Mojave River from the confluence of Deep Creek 

and West Fork Mojave River downstream to Afton 

Canyon (fig. 1). The purpose of this report is to 

summarize the results of the 4-year study.

Acknowledgments

The author expresses his gratitude to the many 

land owners in the area who supplied information on 

their wells and allowed access to their property for 

various measurements. Through conversations with 

many of these same people, the author gained a valuable historical perspective of water development and 

flow conditions of the Mojave River. Appreciation 

also is expressed to the California Department of Fish 

and Game and the Victor Valley Wastewater 

Reclamation Authority for supplying information on 

their discharges to the river. Thanks also are given to 

personnel of the Mojave River Valley Museum and the 

San Bernardino County Museum for allowing the 

author to review their photographic files and other 

historical reference materials.

THE MOJAVE RIVER

Drainage-Basin Characteristics

The Mojave River is formed by the junction of 

Deep Creek and West Fork Mojave River at The Forks 

at the northern foot of the San Bernardino Mountains 

(fig. 1). From The Forks, the river flows generally 

northward through the city of Victorville, then generally north and northeastward through the city of Barstow, and, eventually, through Afton Canyon. After 

emerging from Afton Canyon, the river splits and 

separate channels lead to East Cronese Lake and Soda 

Lake, both of which are dry playas except after major 

storms. During very wet winters, such as 1983 and 

1993, water from Soda Lake flows into Silver Lake. 

To the author's knowledge, no water has flowed from 

East Cronese Lake into West Cronese Lake in historical times. Local residents report that during the 

winter of 1983, the Mojave River overflowed its banks 

between Iron Mountain and Barstow, and part of the

river water flowed north-northwestward into Harper 

Lake (not generally considered a part of the river 

basin).

To aid in discussion of the hydrology, the author 

has divided the Mojave River basin into headwaters, 

main-stem, and tail water sections (fig. 1). The headwaters section includes the Deep Creek and West Fork 

drainage basins above The Forks. The main-stem 

section includes that part of the Mojave River basin 

between The Forks and Afton Canyon. The mainstem section, which is the primary focus of this report, 

has been further divided into upper, middle, and lower 

parts on the basis of the location of USGS gaging 

stations. The tailwater section downstream from 

Afton Canyon was not a part of the study.

The drainage area of the Mojave River basin at 

the mouth of Afton Canyon is about 2,121 mi2 (Mullen 

and others, 1994, p. 109). However, included in that 

area is about 120 mi2 of internal surface drainage in 

Apple Valley and about 400 mi2 of internal surface 

drainage to Troy Lake. Thus, the area contributing 

surface runoff to the river at Afton Canyon is, at most, 

about 1,600 mi2 (fig. 1). The headwaters section includes about 210 mi2 (13 percent) of this contributing 

drainage area, the upper main stem about 180 mi2 (11 

percent), the middle main stem about 780 mi2 (49 

percent), and lower main stem about 430 mi2 (27 

percent).

The altitude of the mountainous headwaters 

section ranges from about 2,960 ft above sea level at 

The Forks to about 8,535 ft at Butler Peak in the Deep 

Creek drainage basin. The altitude of the Mojave 

River streambed is about 2,700 ft at Victorville, 2,100 

ft at Barstow, and 1,400 ft near the mouth of Afton 

Canyon. The slope of the main stem of the Mojave 

River, on the basis of measured distances between 

topographic contours on USGS maps, ranges from 7 to 

42 ft/mi and averages about 16 ft/mi.

Large areal variations in precipitation occur 

within the Mojave River basin. In the headwaters 

section, mean annual precipitation may exceed 40 in. 

Annual precipitation at the Squirrel Inn II station at an 

altitude of 5,750 ft (water years 1931-40) and at the 

Lake Arrowhead station (water years 1941-94) at an 

altitude of about 5,200 ft is shown in figure 2. Combining the precipitation records of these two stations, 

both of which are at altitudes near the mean altitude of 

the headwaters section, gives a mean annual precipThe Mojave River 3
itation for the 64 years of record of about 42 in. In 

contrast, mean annual precipitation is about 6 in. at 

Victorville and about 4 in. at Barstow and Afton 

Canyon (James, 1992).

60 70 

WATER YEAR

90 1994

Figure 2. Annual precipitation in the headwaters of the 

Mojave River basin, water years 1931-94. (Squirrel Inn 

II, 1931-40; Lake Arrowhead, 1941-94.)

1930 50 60 70 

WATER YEAR

90 1994

Figure 3. Cumulative departure from mean 

precipitation in the headwaters of the Mojave River 

basin, water years 1931-94.

As will be illustrated later in this report, 

precipitation and runoff in the headwaters section of 

the Mojave River basin greatly influence flow along 

the main stem of the river. A graph (fig. 3) of 

cumulative departure from mean precipitation at the 

Squirrel Inn II and Lake Arrowhead stations shows 

relative wet and dry periods in the headwaters during 

water years 1931-94. Upward-sloping sections of the 

graph indicate years when annual precipitation 

exceeded the mean. Conversely, downward-sloping 

sections of the graph indicate years when annual 

precipitation was less than the mean. For example, a 

dry period during water years 1948-65 had only three 

years of "above-normal" precipitation. The graph also 

shows that the recent drought (water years 1984-91) 

that markedly diminished California's water supply 

had the same duration but was less severe than the 

drought during 1970-77, at least in the headwaters of 

the Mojave River basin.

Several lakes and a reservoir partially regulate 

streamflows in the headwaters section of the basin. 

Lake Arrowhead (capacity 48,000 acre-ft) in the Deep 

Creek drainage basin and Lake Gregory (capacity 

2,070 acre-ft) in the West Fork drainage basin are used 

primarily for recreation, and both slightly regulate 

streamflows during summer. Silverwood Lake 

(capacity 78,000 acre-ft), also in the West Fork 

drainage basin, was completed in 1971, mainly as a 

temporary holding reservoir for water imported via the 

California Aqueduct. Natural streamflow into 

Silverwood Lake is released through Cedar Springs 

Dam into West Fork as soon as possible after storms. 

The Mojave River Forks Reservoir (capacity 89,700 

acre-ft) at the confluence of Deep Creek and West 

Fork also was completed in 1971 and is used for flood 

control. No water is impounded in the reservoir 

except during extreme flooding, and then only for a 

few hours.

History of Gaging Stations

Much of the description in this report regarding 

surface-water hydrology is based on discharge records 

from USGS gaging stations (fig. 4) in the headwaters 

section and along the main stem of the Mojave River. 

Because these records are such an integral part of the 

analysis, a brief historical summary of these gaging 

stations follows.

4 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
The USGS has operated gaging station 

10260500, Deep Creek near Hesperia, since water 

year 1930. The station is located about 1 mi upstream 

from the confluence with West Fork Mojave River 

(fig. 4). The drainage area of Deep Creek at the station 

is 134 mi2.

Two gaging stations have been operated on West 

Fork Mojave River near The Forks. The first, 

10261000, West Fork Mojave River near Hesperia,

was located about 0.5 mi above the confluence with 

Deep Creek. At this location, the gage was operated 

by the USGS during water years 1930-1971, prior to 

the construction of Cedar Springs Dam and Mojave 

River Forks Reservoir. The second station, 10260950, 

West Fork Mojave River above Mojave River Forks 

Reservoir, near Hesperia, is located about 0.6 mi 

upstream from the first station. It has been operated 

since water year 1975. Although the drainage areas of

T11N 

35°

T10N

T9N

T8N

T7N

T6N

T5N 

34°30'

T4N

T3N

R5W R3W

(£l Hesperia 4-.' 

A g^

fCfUfOW. ll0261100A^2

MUCDUCT V The Forksftl iohiooo,^i'

U/estForfc m^iaiflisff-*^'^ MoiaueRM- 1D^ lfM'!)lr

-» <Nf

, \// / 10260500'.

Silverwoodf- Mojave tiiuer

Tnf iJ^ frrf- fjeseruoir

<Z5

Gaging station and number 

Discontinued gaging station and number 

Channel-geometry site and number

Man-made discharge to river F, fish hatchery; I, imported 

water; W, wastewater

Distance downstream from Mojave River Forks Reservoir, 

in river miles

Base from Calilornia, Soulti Hall, 1 500,000,1961, revised 1981

Figure 4. Gaging stations, channel-geometry sites, points of manmade discharge to river, and distance downstream from Mojave River Forks Reservoir.

The Mojave River 5
the first and second stations are 74.8 and 70.3 mi2, 

respectively, streamflow for all practical purposes is 

equivalent at the two sites, except perhaps for a few 

hundred acre-feet of storm runoff from the 4.5-mi2 

area between the stations.

On the main stem of the Mojave River, 0.8 mi 

downstream from the confluence of Deep Creek and 

West Fork, gaging station 10261100, Mojave River 

below Mojave River Forks Reservoir, near Hesperia, 

was operated during water years 1972-74. The station 

was inactive during water years 1975-79, and it was 

reactivated during water year 1980. Drainage area at 

the station is 211 mi2.

Gaging station 10261500, Mojave River at 

Lower Narrows, near Victorville (fig. 5), was operated 

during water years 1900-06 and 1931-36 at the Upper 

Narrows about 3 mi upstream from its present location 

where it has been in operation since December 9,

1936. Drainage area at the current location is 513 mi2, 

which includes about 120 mi2 of noncontributing 

internal drainage in Apple Valley.

Gaging station 10261900, Mojave River at Wild 

Crossing, near Helendale, was operated during water 

years 1967-70. About 7 mi farther downstream, 

gaging station 10262000, Mojave River near Hodge, 

was operated during water years 1931-32 and 1971- 

93. Both stations were discontinued because of 

unstable controls and changing stage-discharge 

relations that did not allow for acceptable discharge 

records.

The Mojave River at Barstow (fig. 6) has been 

measured at gaging station 10262500 since water year 

1931. Drainage area of the Mojave River at the station 

is 1,291 mi2, which includes about 120 mi2 of 

noncontributing area in Apple Valley.

Figure 5. Gaging station 10261500, Mojave River at Lower Narrows, near Victorville, January 31, 

1995. (Gage house in top right hand corner.)

6 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
At the mouth of Afton Canyon at the lower end 

of the main stem, the Mojave River has been measured 

at station 10263000 (fig. 7) periodically since water 

year 1930. The station was operated during water 

years 1930-32, and it was reactivated in water year 

1953. Records for water years 1979 and 1980 are 

incomplete, and only discharge measurements were 

published during these two years. Drainage area of 

the Mojave River at the station is 2,121 mi2, which 

includes a total of about 520 mi2 of noncontributing 

area (internal drainage in Apple Valley and to Troy 

Lake).

Mullen and others (1994) point out the 

following regarding accuracy of gaging-station 

records:

The accuracy of discharge data depends 

primarily on (1) the stability of the stage-discharge 

relation or, if the control is unstable, the frequency 

of discharge measurements, and (2) the accuracy 

of observations of stage, measurements of discharge, and interpretations of records.

For gaging stations on Deep Creek, West Fork, and the 

main stem of the Mojave River, the daily mean 

discharges generally have been rated as "fair" or 

"poor," "Fair" means that about 95 percent of the 

computed daily mean discharges are within 15 percent 

of the true daily mean discharge. "Poor" means that 

daily mean discharges have less than "fair" accuracy. 

According to Robert W. Meyer (U.S. Geological 

Survey, written commun., 1995), an analysis of 

gaging-station records indicates that uncertainty of 

daily mean discharges at the Deep Creek gage 

(10260500) ranges from about 5 to 35 percent and 

averages about 20 percent. Similarly, uncertainty of 

daily mean discharges at West Fork gaging stations 

(10260950 and 10261000) ranges from about 5 to 35 

percent and averages about 15 percent. Daily mean 

discharges at the Lower Narrows gaging station 

(10261500) have an uncertainty that ranges from 

about 5 to 70 percent and averages about 15 percent. 

Meyer"s analysis is based on a split-sample method 

developed by Dawdy and Burkham (1970), which can

Figures. Gaging station 10262500, Mojave River at Barstow, January 18,1993. (Discharge about 

4,200 cubic feet per second.)

The Mojave River 7
be applied to stations that have a large number of 

discharge measurements. Although too few 

measurements were available to apply the method to 

records at Barstow (10262500) and at Afton Canyon 

(10263000), Meyer estimates that uncertainty at these 

two stations probably ranges from 5 to 20 percent, but 

it could be as high as 50 percent during some days 

having no gage-height record because of instrument 

malfunction.

The following discussion in this report will 

concentrate on water years 1931-94. Although there 

are some breaks in the gaging-station record on West 

Fork and the Mojave River at Afton Canyon during 

this 64-year period, continuous record exists since 

water year 1931 for stations on Deep Creek, Mojave 

River at Lower Narrows, and Mojave River at 

Barstow.

Stream!low from Headwaters

Deep Creek at The Forks is a perennial stream. 

During the period of record at gaging station 

10260500, Deep Creek ceased to flow during only two 

days (July 17 and 18,1961). West Fork Mojave River, 

however, is an ephemeral stream at The Forks. West 

Fork flows only in response to storm runoff and 

releases from Silverwood Lake.

Flow-duration curves are shown in figure 8 for 

both Deep Creek and West Fork prior to and after 

completion of Cedar Springs Dam on Silverwood 

Lake in 1971. The curves show the percentage of time 

that specified stream discharges were equaled or 

exceeded at the gaging stations (Searcy, 1959). For 

example, the two curves for West Fork show that prior 

to construction of Cedar Springs Dam, the discharge 

(during 1931-71) exceeded 0.1 ft3/s about 37 percent 

of the time; after completion of the dam, discharge

Figure 7. Gaging station 10263000, Mojave River at Afton, January 17,1993.

8 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
exceeded 0.1 ftVs about 44 percent of time. In fact, 

the duration of flow was longer for the complete range 

of discharge after completion of the dam. Deep Creek, 

which is not regulated by Silverwood Lake, had a 

similar increase in flow duration after 1971.

The combined annual discharge of Deep Creek 

and West Fork at The Forks during water years 1931- 

94 is shown in figure 9. This annual inflow to the 

main stem of the Mojave River averaged about 71,000 

acre-ft (about 47,000 acre-ft from Deep Creek and 

24,000 acre-ft from West Fork). The smallest annual

inflow (2,200 acre-ft) occurred during water year 1951 

when West Fork did not flow the entire year. The five 

largest annual inflows occurred after 1968, and the 

largest (about 430,000 acre-ft) occurred during water 

year 1993. It should be noted that water years 1972- 

74 are queried in figure 9 because no gaging station 

was in operation on West Fork during these three 

years, and discharge at gaging station 10261100 below 

Mojave River Forks Reservoir was used to estimate 

inflow to the main stem.

10,000

1,000 i

o 

o

UJ (/>

DC 

HI

a. I111

UJ 

LL

o

CO

z> 

o

u 

(3 

cc

< I 

o

\ West Fork

' (1331-71) :f 975-94) '" '

013 12 5 10 20 30 40 50 60 70 80 90 95 98 99 9987 

PERCENTAGE OF TIME DISCHARGE EQUALED OR EXCEEDED

Figure 8. Flow duration for Deep Creek at gaging station 10260500 (water years 1931-71 and 

1972-94) and for West Fork Mojave River at gaging stations 10261000 and 10260950 (water 

years 1931-71 and 1975-94).

The Mojave River 9
Over a long period of time (water years 1931- 

94), runoff per unit area has been similar in the two 

headwaters basins. Annual runoff averaged 6.6 in. for 

the Deep Creek basin and 6.3 in. for the West Fork 

drainage basin.

The probability of a given inflow to the main 

stem being exceeded in any given water year is shown 

in figure 10. For example, there is a 90-percent 

probability that the combined annual runoff from 

Deep Creek and West Fork will exceed 10,000 acre-ft 

in any given year, a 50-percent probability that it will 

exceed 40,000 acre-ft, and about a 2-percent probability that it will exceed 400,000 acre-ft. Recurrence 

intervals also are shown in figure 10. A recurrence 

interval is simply the reciprocal of the exceedance 

probability when expressed as a decimal fraction. 

Thus, an exceedance probability of 0.20 (20 percent)

40 50 60 70 

WATER YEAR

90 1994

Figure 9. Total annual inflow to main stem of Mojave 

River from the headwaters, water years 1931-94. 

(Based on the combined annual runoff of Deep Creek 

and West Fork Mojave River.)

is equivalent to a recurrence interval of 5 years. From 

the graph, we see that an annual inflow of about 

100,000 acre-ft or greater will occur, on the average, 

once every 5 years (recurrence interval).

Selected water years are labeled in figure 10 to 

identify years at both the low and high extremes and 

the years during and immediately preceding this study. 

Here again, it is apparent that the 5 largest annual 

inflows to the main stem occurred after 1968. Five of 

the six lowest annual inflows occurred during the 

1950's and 1960's. Water years 1992-94, the period of 

field work for this study, include the year with the

500,000

101

RECURRENCE INTERVAL, IN YEARS

2 5 10 20 50 100

100,000

50.000

10,000

5.000

1.000

99 98 95 90 80 70 60 50 40 30 20 10 5 21 

EXCEEDANCE PROBABILITY, IN PERCENT

Figure 10. Exceedance probabilities and recurrence 

intervals for total annual inflow to main stem of Mojave 

River from the headwaters. (Based on the combined 

annual runoff of Deep Creek and West Fork Mojave 

River, water years 1931-94; selected water years 

identified.)

10 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
highest inflow of record (1993) and two years with 

slightly "above average" inflow.

Streamflow Along Main Stem

Most of the water entering the main stem of the 

Mojave River from the headwaters is lost by 

infiltration into the permeable streambed. As pointed 

out in the previous section, annual inflow from the 

headwaters averaged about 71,000 acre-ft during 

water years 1931-94. Whereas, during this same 

period, annual flow averaged about 54,000 acre-ft at 

the gaging station near Victorville (10261500) and 

about 18,000 acre-ft at the Barstow gaging station 

(10262500). The average annual flow at the gaging 

station in Afton Canyon (10263000) during water

years 1931-32,1953-78, and 1981-94 was about 7,500 

acre-ft.

The mean daily discharges for the gaging 

stations near Victorville, at Barstow, and in Afton 

Canyon are shown in figures 11-13. The perennial 

nature of the Mojave River near Victorville is apparent 

from its hydrograph (fig. 11), as is the annual cycle of 

wintertime high discharges and summertime low 

discharges. The low discharges in the annual cycle are 

caused by streamflow depletion by ground-water 

pumping and evapotranspiration, which is discussed in 

detail in a later section of this report. Superimposed 

on the annual cycle are periods of storm runoff, which 

commonly occur during January-March. The 

ephemeral nature of the river at Barstow is apparent 

from its hydrograph (fig. 12). The number of days of 

no flow at Barstow far exceed the number of days with

100,000 FT

1931 40 45 50 55 60 65 

WATER YEAR

70 75 80 85 90 94

Figure 11. Daily mean discharge at gaging station 10261500, Mojave River at Lower Narrows, 

near Victorville, water years 1931-94. (Recession index lines shown in red.)

The Mojave River 11
flow. The river at Barstow, at least since water year 

1931, has flowed only in response to storm runoff. 

Streamflow at Afton Canyon (fig. 13) has an annual 

cycle that is similar to that for flow near Victorville, 

except the summertime depletion in flow is due 

entirely to evapotranspiration. The river at Afton 

Canyon has ceased to flow several times, most 

recently during the summer of 1994.

It has been suggested that the regulation of 

Streamflow in the headwaters by Silverwood Lake and 

Mojave River Forks Reservoir has markedly changed 

Streamflow characteristics along the main stem of the 

Mojave River. Although both reservoirs undoubtedly 

have attenuated flood peaks, neither has had an effect 

on volumes of runoff entering the main stem. Flowduration curves for the periods of record prior to and

following the completion of the reservoirs in water 

year 1971 are shown for gaging stations near 

Victorville, at Barstow, and at Afton Canyon (fig. 

14). At all three stations, the duration of the largest 

discharges (greater than about 1,000 fWs) increased 

after the completion of Silverwood Lake and Forks 

Reservoir. Conversely, at all three stations, the smaller 

discharges seem to have decreased in duration since 

1971, mainly as a result of Streamflow depletion by 

ground-water pumping. This is in contrast to 

increased duration of low flows after 1971 at gaging 

stations on Deep Creek and West Fork (fig. 8).

Reaches of the main stem of the Mojave River 

that had Streamflow during water years 1992-94 are 

shown in blue in figure 15. River miles in figure 15 

correspond to river miles shown on the map in figure

100,000 FT

o 

o

LJJ

cc

LJJ 

Q_

LJJ 

LJJ 

LJ_

O

CO

LJJ 

O 

CC

Q

10,000

1,000

100

10

i : i i i i i i i i i

i i i i i i L L 1111 j 11 i

1931 35 40 45 50 55 60 65

WATER YEAR

70 75 85 90 94

Figure 12. Daily mean discharge at gaging station 10262500, Mojave River at Barstow, water 

years 1931 -94.

12 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
4. As can be seen in figure 15, most of the main stem 

of the Mojave River was dry during this 3-year period. 

The river flowed along the entire main stem for only a 

few weeks in the winter of water year 1993.

In non-storm periods during water years 1992- 

94, water from Deep Creek and West Fork emerged 

from the tunnel through the dam at Mojave River 

Forks Reservoir and flowed only a few miles before 

infiltrating in the sandy streambed of the Mojave 

River. At about miles 9 and 10, the river began to flow 

again with the discharge from two fish hatcheries (fig. 

4). These and other manmade discharges to the river 

are discussed in greater detail in a later section of this 

report. During summer and fall of each year, water 

discharged from the fish hatcheries also rapidly 

infiltrated into the streambed. At about mile 12,

because of thinning of the flood-plain aquifer, groundwater discharged naturally into the river. This 

discharge of ground water (base flow) continued 

through the Upper and Lower Narrows creating the 

perennial flow at gaging station 10261500 at the 

Lower Narrows.

Streamflow leaving the Lower Narrows and 

entering the middle section of the Mojave River main 

stem rapidly infiltrated into the flood-plain aquifer, 

and the river between about miles 18 and 22 was dry 

for long periods during water years 1993 and 1994. 

During water year 1992, this reach of the river had 

continuous flow, probably because of leakage from a 

sewage line beneath the river. (The sewage line was 

repaired in the spring of 1993.) At about mile 22, 

wastewater from the treatment facilities of Victor

100,000 F

o 

o

UJ

DC 

UJ 

O_

UJ 

UJ 

U.

O 

CO

10,000

1,000

0 100

UJ

o

DC

o 

5

10

1 I I I I I I I I I I I I I I I I I I I I I I I I I I I

1930 35 40 45 50 55 60 65 70 75 80 85 90 94

WATER YEAR

Figure 13. Daily mean discharge at gaging station 10263000, Mojave River at Afton, water years 

1930-32,1953-78, and 1981-94. (Recession index lines shown in red.)

The Mojeve River 13
Valley Wastewater Reclamation Authority was 

discharged into the river, creating a reach of perennial 

flow between river miles 22 and 26 (see fig. 15). The 

remainder of the middle main stem and most of the 

lower main stem were dry during water years 1992-94, 

except during periods of winter storm runoff primarily 

from the headwaters. Thinning of the flood-plain 

aquifer at Afton Canyon caused ground water to 

discharge into the river beginning about 1 mi above 

gaging station 10263000. The river flowed 

continuously at the gaging station in Afton Canyon

except for a few days in the summers of water years 

1992 and 1994.

The analysis of frequency and magnitude of 

annual runoff from the headwaters section (fig. 10) 

indicates that runoff in water year 1993 was the 

greatest during the period 1931-94 and that runoff in 

water years 1992 and 1994 also was above average 

(exceedance probabilities less than 50 percent). As 

shown in figure 15, the first peak of runoff from the 

headwaters during water year 1993 extended river 

flow to about river mile 32 (Helendale). The second

10,000

o 

o 111

C/)

cc 111 CL

HI 

HI 

u_

O

00

D 

O

LLJ

X

o

C/)

o

1,000

12 5 10 20 30 40 50 60 70 80 90 95 98 99 99.87 

PERCENTAGE OF TIME DISCHARGE EQUALED OR EXCEEDED

Figure 14. Flow duration for the Mojave River near Victorville (gaging station 10261500), at Barstow (gaging 

station 10262500), and at Afton Canyon (gaging station 10263000) during selected periods.

14 Ground-Water and Surf ace-Water Relations Along the Mojave River, Southern California
peak extended river flow to about river mile 79, about 

3 mi upstream from Camp Cady. Because most of the 

streambed had been wetted, the third, fourth, and fifth 

peaks extended the river flow to Afton Canyon and 

beyond.

During water year 1992, wintertime runoff from 

the headwaters, coupled with wintertime decreases in

ground-water pumping and evapotranspiration from 

the flood-plain aquifer, extended river flow to about 

river mile 45, which is about 2 mi upstream from 

Lenwood. But during 1994, a slightly-above-average 

year with headwaters inflow having an exceedance 

probability of about 45 percent, wintertime runoff 

from the headwaters completely infiltrated into the

CO

1

o

-J

ICO

.C

I 

o>

§

Lower Narrows 

Upper Narrows

The Forks

1992 1993 1994

WATER YEAR

Figure 15. Reaches of the main stem of the Mojave River that had streamflow 

(blue areas) during water years 1992-94.

The Mojave River 15
streambed by about river mile 6. The extension of 

flow to about river mile 36 during the winter of 1994 

was again largely due to wintertime decreases in 

pumping and evapotranspiration, both of which are 

discussed in greater detail later in this report.

Descriptions of the Mojave River during the 

18th and 19th centuries are brief, but diaries, journals, 

and reports of early travelers and explorers provide 

some insight into streamflow conditions. The first 

written record is a diary by Father Francisco Garce's 

(1738-81), a Franciscan priest who travelled along the 

Mojave River in search of a route from the Colorado 

River to Monterey in Spanish California. The diary 

has been translated into English and interpreted by 

Coues (1900). On March 9, 1776, Garce's describes 

entering a canyon (Afton Canyon) having a stream of 

brackish water. Garces continued his travel upstream 

along the Mojave River and camped at several places 

described by him as having abundant water and 

pasturage. Garce's described crossing the river 

somewhere near Hodge on March 16 and having to 

camp at the crossing for a day to dry cargo, carried by 

his mule, that had been soaked in crossing the river. 

Garce's encountered several Indian rancherias along 

reaches of the river having flow as he continued his 

travels through the Lower and Upper Narrows toward 

the headwaters.

Trappers and explorers the most notable being 

Jedediah Smith (in 1826), Capt. John C. Fremont (in 

1844), and Kit Carson (in 1848) and thousands of 

pioneers traveled the Spanish Trail and Mormon Road 

along the Mojave River during the 1800's. Along 

stretches of the river that had flowing water or a 

shallow water table, well-used camp sites were 

established. Camp Cady (an Army post occupied in 

1863-64 at river mile 82), Fork of Roads (mile 70), 

Fish Pond (mile 60), Grapevine (mile 55), 

Cottonwoods (mile 40), Point of Rocks (mile 34), and 

Lane's Crossing (mile 20) became well-known 

watering and resting spots (Walker 1986, p. 190). 

Many of these sites, particularly those along the lower 

main stem of the river, no longer have year-round flow 

in the river (see fig. 15) or a shallow water table.

Other changes in the river can be ascertained by 

comparing current conditions with those observed 

during land surveys of the 1850's. Ralph W. Norris1

survey of the Helendale area in 1853 note*1 an 

extensive swamp area in sections 29, 30, and 31, 

township 8 N., range 4 W. During water years 1992- 

94, this reach (river miles 31 and 32) was dry most of 

the time (see fig. 15). Also, Henry Hanccnk's survey 

of the Victorville area in 1855 notes swamps in 

sections 23, 24,25, 26, and 30, township 5 N., range 4 

W. (river miles 10 to 12). Comparison of Hancock's 

detailed descriptions with conditions during water 

years 1992-94 indicates that the swamps no longer 

exist, although the river flows through this reach most 

of the year. Microfilm of original land-su-vey notes 

and maps are on file in the U.S. Bureau of Land 

Management office in Barstow, California.

Ungaged Tributary Streams

Before the gaging-station records crn be used to 

quantitatively evaluate ground-water and surfacewater relations, all accretions to (and losses from) 

streamflow between the stations must be known. 

Along the main stem of the Mojave River, these accretions include runoff from ungaged tributary streams 

and manmade discharges to the river. Any diversions 

from a stream also would have to be accounted for; 

however, there have been no major divers; ons from 

the Mojave River main stem since the 1977s.

An area of about 1,400 mi2 contributes runoff to 

the main stem of the Mojave River between The Forks 

and Afton Canyon. Most of this runoff enters the river 

through ephemeral tributary streams that flow only in 

response to storm runoff. The runoff from tributary 

streams has been ungaged. For this study, channelgeometry techniques were used to estimate the mean 

annual flow of ephemeral tributary streams.

Channel-geometry techniques have been used 

by several researchers to estimate various streamflow 

characteristics in the Western United States. Hedman 

(1970) developed channel-geometry relations using a 

large number of streams in California, and the reader 

is referred to Hedman's report for discussions of the 

concepts and techniques. Because many of the 

streams in Hedman's study were in more humid coastal areas or had larger drainage areas than most streams 

in the Mojave River basin, the author developed new

16 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
relations between annual mean flow and channel 

geometry specifically for the Mojave Desert region.

Channel dimensions were measured at 29 active 

and discontinued gaging stations in the Mojave Desert

region, including several along the Mojave River. 

These 29 gaging stations are listed in table 1 along 

with drainage area, period of record, annual mem 

discharge, and average channel width. When

Table 1. Annual mean discharge and channel width at 29 gaging stations in the Mojave Desert region 

[mi2, square mile; acre-ft, acre-foot; ft, foot]

Station no.

10252550

10255700

10255805

10255810

10256000

10257720

10258000

10258500

10259000

10260400

10260500

10260620

10260630

10260950

10261100

10261500

10261800

10262500

10263000

10263500

10264560

10264590

10264600

10264710

10264740

10264750

10264770

10264878

11031500

Station name

Caruthers Creek near Ivanpah

San Felipe Creek near Julian

Coyote Creek below Box Canyon, near Borrego Springs

Borrego Palm Creek near Borrego Springs

Whitewater River at White Water

Chino Canyon Creek below tramway, near Palm Springs

Tahquitz Creek near Palm Springs

Palm Canyon Creek near Palm Springs

Andreas Creek near Palm Springs

Cushenbury Creek near Lucern Valley

Deep Creek near Hesperia

Houston Creek above Lake Gregory.at Crestline

Abondigas Creek above Lake Gregory, at Crestline

West Fork Mojave River above Mojave River Forks Reservoir,

near Hesperia

Mojave River below Mojave River Forks Reservoir, near

Hesperia

Mojave River at Lower Narrows, near Victorville

Beacon Creek at Helendale

Mojave River at Barstow

Mojave River at Afton

Big Rock Creek near Valyenno

Spencer Canyon Creek near Fairmont

Cottonwood Creek near Rosamond

Oak Creek near Mojave

Goler Gulch near Randsburg

Cache Creek near Mojave

Pine Tree Creek near Mojave

Cottonwood Creek near Cantil

Ninemile Creek near Brown

Agua Caliente Creek near Warner Springs

Drainage 

area 

(mi2)

1.13

89.2

154

21.8

57.5

4.70

16.9

93.1

8.65

6.36

134

35

1.15

70.3

211

513

72

1,291

2,121

22.9

3.68

35.7

15.8

41.3

96.5

33.5

163

10.4

19.0

Period of 

record 

(water years)

1964-81,

1983-93

1959-83

1951-93

1951-93

1949-79

1987-93

1948-82,

1984-93

1931-41,

1948-93

1949-93

1958-71

1905-22,

1930-93

1980-93

1980-93

1975-93

1972-74,

1981-93

1900-06,

1931-93

1961-67

1931-93

1930-32,

1953-78,

1981-93

1924-93

1965-73

1966-72

1958-86

1967-72

1966-72

1959-79

1967-72

1962-71

1962-87

Annual 

mean 

discharge 

(acre-ft)

94

710

1,930

750

12,600

658

3,880

3,960

2,220

46

52,700

518

878

33,140

45,920

56,700

.7

18,190

5,730

13,040

38

10

920

14

87

188

46

500

1,960

Average 

channel 

width 

(ft)

1.6

4.5

4.4

3.1

8.3

2.9

11

3.0

4.9

3.6

38

1.3

3.9

13

36

23

1.0

19

5.6

11

1.8

1.8

2.9

1.1

4.0

2.8

1.1

1.2

3.9

The Mojave River 17
determining channel dimensions, the channels were 

examined along reaches of 500 to 1,000 ft to 

determine if consistent channel sizes were being 

formed. The width between the streamward shoulders 

of berms and bars was measured as the channel width 

(see fig. 16). In most cases, a carpenter's ruler was 

laid across the shoulders of the bars or berms that 

formed the channel, and the depth of this reference 

level down to channel bottom was measured as 

channel depth. The measurements were made across 

one to four sections and then averaged.

Multiple regression was used to determine the 

relation between annual mean discharge and channel

width and depth at the gaging stations. As with most 

hydrologic relations, a logarithmic transformation of 

the data was necessary to linearize the relation. The 

regression analysis indicated that channel depth was 

not a statistically significant variable (at the 95 percent 

level, student t was less then 1.95), and it was omitted 

from further regression analysis. The logarithmic 

transformation of the annual mean discharge and 

channel width at the 29 gaging stations, and the 

regression equation used to estimate annual mean 

discharge at ungaged sites, in the Mojave River basin 

is shown in figure 17. The R2 (coefficient of 

determination) for this equation was 0.73, and the

Figure 16. Channel-geometry measurement at site 10 on Bell 

Mountain Wash. (Channel width at this section was about 4.5 feet. 

Wooded Mojave River flood plain in background.)

18 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
correlation coefficient was 0.86. An examination of 

residuals indicates that they are randomly scattered 

along the regression line.

Channel dimensions also were measured at 22 

sites on ungaged ephemeral streams tributary to the 

Mojave River. The sites are listed in table 2 along 

with drainage area, average channel width, the 

estimated annual mean discharge, and estimated 

runoff. Both annual mean discharge and runoff are 

rounded to one significant figure. The tributary 

streams were measured as close to their mouths as 

possible so that estimated discharge would represent 

accretion to flow of the Mojave River. The location of 

the 22 channel-geometry sites is shown in figure 4.

Estimated annual runoff ranged from less than 

0.001 to 2 in., although runoff from most sites ranged 

from 0.1 to 0.5 in. In general, the runoff estimates 

were smaller for streams draining relatively flat terrain 

and larger for streams draining steep and rocky terrain. 

Drainage areas of the 22 sites include 125 mi2 of the 

approximately 180-mi2 area that drains into the roper 

main stem of the Mojave River (excluding the 

headwaters), 557 mi2 of the approximately 778-ni2 

area that drains into the middle main stem, and 180 

mi2 of the approximately 432-mi2 area that drain' into 

the lower main stem. On the basis of a drainage-areaweighted average annual runoff (in.) for each section 

of the main stem, estimated ungaged tributary inflow

Table 2. Channel width and estimated annual mean discharge and runoff in selected ephemeral tributary streams 

to the Mojave River

[mi2, square mile; acre-ft, acre-foot; ft, foot; in., inch; <, less than]

Site No. 

(fig. 4)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

Stream name and location

Unnamed, SW1/4 NW1/4 sec.18, T.3N., R.3W.

Unnamed, NE1/4 SW1/4 sec.6, T.3N., R,3W.

Unnamed, SE1/4 SW1/4 sec.36, T.4N., R.4W.

Antelope Valley, SE1/4 NW1/4 sec.25, T.4N., R.4W.

Unnamed, SW1/4 SE1/4 sec. 12, T.4N., R4W.

Unnamed, NW1/4 NW1/4 sec. 12, T.4N., R4W.

Unnamed, SE1/4 SE1/4 sec.7, T.4N., R.3W.

Desert Knolls Wash, SW1/4 SE1/4 sec. 10, T.5N., R.4W.

Oro Grande Wash, NE1/4 SW1/4 sec.10, T.5N., R.4W

Bell Mountain Wash, SW1/4 NW1/4 sec.34, T.6W, R.4W

Unnamed, SE1/4 SE1/4 sec.30, T.6N., R.4W.

Fremont Wash, NE1/4 NE1/4 sec.2, T.7N., R.5W

Buckthorn Wash, NE1/4 SE1/4 sec.25, T.8N., R5W

Wild Wash, SE1/4 SE1/4 sec.7, T.8N., R.3W

Unnamed, NE1/4 SW1/4 sec.28, T.9N., R.3W

Stoddard Wash, SW1/4 SE1/4 sec.18, T.9N., R2W

Boom Creek, SW1/4 NE1/4 sec. 11, T.9N., R.1W

Daggett Wash SE1/4 SW1/4 sec. 17, T.9N., R.1E.

Calico Wash, NE1/4 NE1/4 sec.6, T.9N., R.2E.

Manix Wash, SE1/4 NE1/4 sec.10 T.10N., R.4E.

Wilhelm Wash, SE1/4 NE1/4 sec.32, T.I IN., R.5E.

Unnamed, SW1/4 SE1/4 sec.18, T.I IN., R.6E.

Drainage 

area 

(mi2)

1.2

1.3

7.5

16.1

5.6

15.6

7.5

7.6

27.8

34.9

7.6

254

104

47.7

1.9

142

1.6

24.0

100

45.2

7.6

1.6

Average 

channel 

width 

(ft)

1.0

0.9

1.3

3.0

1.5

1.4

<.l

2.2

1.2

4.2

1.7

.8

2.9

2.8

2.5

4.2

1.8

3.0

3.2

3.3

2.2

1.0

Estimated 

annual 

mean 

discharge 

(acre-ft)

30

20

50

400

70

60

<.l

200

40

800

100

20

300

300

200

800

100

400

400

500

200

30

Estiirated 

run iff

Or.)

0.5

.3

.1

.5

.2

.07

<.011

.5

.03

A

.2

.001

.05

.1

2

.1

1

.3

.0°

.2

.5

A

The Mojave River 19
averaged about 2,400 acre-ft along the upper main 

stem, 2,400 acre-ft along the middle main stem, and 

3,900 acre-ft along the lower main stem. In comparison, annual inflow from the headwaters averaged 

about 71,000 acre-ft during water years 1931-94.

It is not possible to determine when the runoff 

from ungaged tributaries occurred in the past. But, if 

one assumes that the runoff in the ephemeral tributary 

streams occurred at the same relative magnitude as the 

ephemeral runoff in the Mojave River at Barstow 

(gaging station 10262500), the distribution of runoff 

would be that shown in figure 18. For example, during

100,000

10,000

100

10

0.1

5 10 

CHANNEL WIDTH (W), IN FEET

50

Figure 17 Relation between channel width and annual 

mean discharge at 29 gaging stations in Mojave Desert 

region.

water year 1969 the annual discharge of the Mojave 

River at Barstow was about 820 percent of the average 

discharge. Assuming that ungaged runoff from 

tributaries also was 820 percent of average during 

water year 1969, total inflow to the Mojave River from 

ungaged tributaries was about 70,000 acre-ft (about 

20,000 acre-ft along the upper main stem, 20,000 acreft along the middle main stem, and 30,COO acre-ft 

along the lower main stem). In comparison, gaged 

inflow to the Mojave River from the headwaters 

section during water year 1969 was about 340,000 

acre-ft.

Manmade Discharges to River

The discharge from two fish hatcheries has 

contributed to the flow of the Mojave River along the 

upper main stem. Discharge from Jess Ranch Fish 

Hatchery, at about river mile 9 (fig. 4), was continuous during water year 1992 and interrrittent during 

water years 1993-94. Historically, water from the 

hatchery has been used for irrigation. Beginning in 

water year 1990, however, ground-water pumpage for 

the hatchery exceeded irrigation requirements, and the 

excess was discharged to the river (Gary Ledford, Jess 

Ranch, oral commun., 1993). With completion of a 

golf course, irrigation requirements rose hi 1994 and 

discharge to the river occurred only during the winter. 

The discharge to the river is not metered, but on the 

basis of periodic discharge measurements and the reported operations, it is estimated that about 2,000 acreft was discharged to the river in water years 1990 and 

1993, about 7,000 acre-ft during water y^.ars 1991 and 

1992, and about 1,000 acre-ft during water year 1994.

A fish hatchery operated by California 

Department of Fish and Game (fig. 19) has been 

discharging water to the river at about nile 10 almost 

continuously since water year 1949. Ground water 

pumped on site is circulated through the fish-rearing 

ponds and all but about 3,000 acre-ft/yr is discharged 

to the river. About 3,000 acre-ft/yr historically has 

been diverted and used for irrigation on the flood plain 

between the hatchery and Upper Narrovs (Richard 

Uplinger, California Department of Fisli and Game,

20 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
written commun., 1993). Although the discharge to 

the river is not metered, an accurate estimate of the 

discharge is made possible by electric power consumption and efficiency tests on water-supply wells. 

The estimated discharge to the river varied from about 

300 acre-ft during water year 1949 to about 18,000 

acre-ft during water year 1991. The estimated total 

discharge to the Mojave River from both this operation and the Jess Ranch hatchery is shown in figure 20.

At about river mile 22 along the middle main 

stem of the Mojave River (fig. 4), waste water from the 

Victor Valley Wastewater Reclamation Authority has 

been discharged to the river since water year 1982. 

The discharge was metered, and it ranged from about 

2,250 acre-ft during water year 1982 to 7,140 acre-ft 

during water year 1991 (N.B. Alien, Victor Valley

Wastewater Reclamation Authority, written commm., 

1994).

Periodically since February 1972, imported 

water has been released from Silverwood Lake tc the 

West Fork Mojave River. Through water year 19?4, 

these releases have totaled about 70,000 acre-ft. 

Except for a short period in March 1983 when wrter 

flowed past Afton Canyon into Soda Lake, all of this 

water percolated into the Mojave River streambed, 

mainly along the upper main stem. In addition, 

beginning in water year 1994, imported water has also 

been released from a turnout in Mojave Water 

Agency's Morongo Basin Pipeline at about river mile 

4. A total of about 6,600 acre-ft was released from the 

turnout in water year 1994, all of which percolated 

into the streambed within 2 mi (see fig. 15).

LLI 

DC

(A

a u< 

2ffi 

m LLJ

T <

oj§

S l 

§2

UJ

 600

H400 3g

200

og 

9. cc

55

CC O 

CO

o

60 70 

WATER YEAR

90 1994

Figure 18. Estimated annual discharge of tributary streams along the main stem of the Mojave River 

and ratio of annual to average discharge of the Mojave River at Barstow (gaging station 10262500), 

water years 1931-94. (Selected years are identified at top of bar.)

The Mojave River 21
Figure 19. Aerial view of California Department of Fish and Game fish hatchery (left foreground) 

and discharge to Mojave River, February 25, 1993. (Photograph by Thomas W. Bilhorn.)

30,000

I Wastewater discharge 

Fish hatchery discharge

1950 70 

WATER YEAR

80 90 1994

Figure 20. Wastewater and fish hatchery discharges 

to the Mojave River, water years 1949-94.

THE FLOOD-PLAIN AQUIFER

Lithology, Thickness, and Extent

The flood-plain aquifer consists mainly of 

unconsolidated gravel, sand, and silt of Holocene and 

Pleistocene age deposited by the Mojave River. 

Downstream from about river mile 70, the aquifer 

contains a large amount of silt and clay (Thompson, 

1929, fig. 14). The flood-plain aquifer is 150 to 250 ft 

thick in most places. In the area of the Upper 

Narrows, the maximum thickness of the aquifer is 

about 50 ft (Slichter, 1905). The aquifer underlies the 

Mojave River flood plain and is in direct contact with 

the river. The flood plain varies in width from about 

120 ft at the Upper Narrows to as much as 1.5 mi 

between Hodge and Lenwood. The flood-plain 

aquifer, in most places, is underlain by older alluvium, 

and along the margins of the flood plain the aquifer 

intertongues with alluvial fans. The older alluvium 

and the alluvial fans generally are fine grained and 

commonly are moderately consolidated. In some 

areas near Barstow and in the Upper and Lower

22 Ground-Water and Surface-Water Relations Along the Mojsve River, Southern California
Narrows, the flood-plain aquifer is directly underlain 

by consolidated rocks.

Hydraulic Characteristics

The flood-plain aquifer is the most productive 

aquifer in the area, and individual wells typically yield 

from 100 to 2,000 gal/min. Several wells about 6 mi 

west of Barstow have been tested at 4,000 gal/min 

(Hardt, 1971, p. 11).

Transmissivity of the flood-plain aquifer ranges 

from 10,000 to 25,000 ft2/d in most areas (Hardt, 

1971, fig. 8). Because of large temporal changes in

saturated thickness in some areas, transmissivity of the 

aquifer can change markedly with time. For example, 

in the area between Hodge and Barstow, water levels 

in wells rose as much as 87 ft during the storm runoff 

of water year 1993 and the transmissivity nearly 

doubled.

Hardt (1971, fig. 8) simulated flow through the 

aquifer using an electric analog model, and he varied 

specific yield from 25 percent along the upper main 

stem of the river to 20 percent along the middle and 

lower main stem. For this study, water-level and 

gravity changes were measured at selected wells, and 

specific-yield estimates based on these measurements 

varied from 14 to 39 percent (fig. 21). Specific yields

R1W R3E R 4 E 116-301 R5E R6E

T7N

T6N

T5N 

34°30

T4N

Water-table contour Shows altitude of water table, November 1991. 

Contour interval 50 and 100 feet. Datum is sea level

Gravity station at observation well Estimated specific yield of 

flood-plain aquifer shown in percent

Observation well R, continuous water-level recorder

Base from California. South Half, 1:500.000.1961. revised 1981

Figure 21. Altitude of the water table in the flood-plain aquifer, November 1991, and estimated specific yield.

The Flood-Plain Aquifer 23
of the aquifer are largest along the upper main stem of 

the river, and they generally decrease in a downstream 

direction. For a complete description of theory and 

methods for using gravity and water-level changes to 

estimate specific yield, a relatively new technique, the 

reader is referred to Pool and Eychaner (1995).

The Water Table

For this study, water levels were measured in 

about 100 wells in November and March of water 

years 1992-94. The measurements were used to define 

the depth to water, the configuration of the water table,

and the change in aquifer saturated volume caused by 

wintertime recharge of river water.

The altitude of the water table in the flood-plain 

aquifer during November 1991 (shown in fig. 21) 

decreased in a downstream direction. The difference 

in altitude for the 100-mile reach between The Forks 

and Afton Canyon was 1,500 ft. Ground-water flow, 

which is perpendicular to the water-table contours, 

was predominantly parallel to the river.

A profile of the Mojave River streambed and the 

water table during November 1991 and March 1993 is 

shown in figure 22. The water-table altitude in 

November 1991 represented conditions following

3,000

Water table Shows altitude 

of water level in wells in and 

adjacent to Mojave River flood 

plain. Dashed where approximately located

-- March 1993 

November 1991

1,400

10 20 30 40 50

RIVER MILE

60 70 90 100

Figure 22. Altitude of Mojave River streambed and altitude of the water table, November 1991 and March 1993.

24 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
several years of below-normal runoff from the headwaters area, and the water table during March 1993 

represented conditions following the largest runoff 

from the headwaters area since 1931. As indicated by 

the profile, the water table was 20 to 80 ft below the 

streambed along the first 10 mi of the river below The 

Forks. Beginning at about river mile 13, the water 

table was at stream level, and it remained at stream 

level until about river mile 27. Between river miles 27 

and 41, the water table was less than 25 ft below the 

stream. At about river mile 52, however, the water 

table was about 100 ft below the stream in November 

1991. Following runoff from major storms during the 

winter of water year 1993, the water table between 

Hodge and Barstow rose as much as 87 ft, and the 

water table at mile 52 was only about 20 ft below the 

river during March 1993.

The effects of the Waterman and CalicoNewberry Faults on the water-table gradient along the 

lower main stem are shown in figure 22. Both faults 

impede ground-water flow. Water-table gradients are 

very steep at the faults, and water-table altitudes upstream and downstream from the faults differ 

markedly. Downstream from both faults, the watertable gradient is almost flat. Following the stormflows 

of March 1993, and after most of the lower main stem 

had ceased to flow, the river continued to flow at the 

Waterman Fault for a period of several days as water 

drained from the flood-plain aquifer upstream from the 

fault.

Because of ground-water pumping, the water 

table has declined several tens of feet since the early 

1900's in some areas. In reaches of perennial flow in 

the river, the water-table decline has been much less. 

On the basis of water-level measurements in wells 

during 1929-31, the California Department of Public 

Works (1934, p. 47) reported:

At no place along the stream is the water 

table distant below the streambed, the greatest 

depths being about 40 feet five miles below the 

Forks and about 25 feet nine miles above Barstow during the period of this investigation.

A comparison of this statement with the March 1993 

water table shown in figure 15 indicates that the 

greatest water-table declines have occurred downstream from the Waterman and Calico-Newberry 

Faults and in the Lenwood area.

Two continuous water-level recorders were 

maintained on wells for this study, and the hydrographs are shown in figure 23. The two wells had 

markedly different water-level changes. Recorder well 

No. 1 located along the upper main stem of the river 

(fig. 21) had seasonal water-level changes of several 

tens of feet; whereas, water-level changes in recorder 

well No. 2 along the middle main stem (fig. 21) were 

only a few feet. Recorder well No. 1, located at about 

river mile 3, is along a reach of the river that was dry 

during much of water years 1992-94 (fig. 15), but this 

reach received considerable infiltration of river water 

during winter months. Recorder well No. 2, located at 

about river mile 26, is near the end of perennial flow 

along the middle main stem (fig. 15), and the floodplain aquifer was nearly full of water in this area. 

Consequently, infiltration of winter stormflows in the 

river during 1993 raised the water table only a few 

feet.

Historical Pumpage

Ground-water pumping at most municipal, 

military, and industrial wells in the Mojave River 

basin is metered, but most irrigation wells are not 

metered. Thus, most estimates of pumpage are, in 

part, based on indirect methods such as electric power 

consumption and water requirements of irrigated 

crops.

The first wells utilized by Indians, explorers, 

and pioneers along the Mojave River were nothing 

more than shallow depressions dug into the streambed 

to reach the shallow water table. By the 1880's, 

settlement of the region was well underway and more 

permanent dug wells were utilized. Thompson (1929) 

reported that by 1917, about 30 wells along the upper 

main stem of the Mojave River were being used to 

irrigate about 5,000 acres of alfalfa. On the basis of 

irrigated-acreage studies by the California Department 

of Public Works (1934), Hardt (1971) estimated that 

ground-water pumpage along the river was about 

40,000 acre-ft in 1930.

The first comprehensive surveys of pumpage 

were completed by Dibble (1967). On the basis of 

Dibble's work, it is estimated that pumpage from the 

flood-plain aquifer was about 100,000 acre-ft in 1951 

and about 120,000 acre-ft in 1960. On the basis of a

The Flood-Plain Aquifer 25
Recorder Well no. 2

(middle mairi stem)

Break In tine indicates 

no record

Recorder Well tip. 1

(upper main stem)

AMJJASONDJFMAMJJASONDJFMAMJJAS 

1992 1993 1994

WATER YEAR

Figure 23. Water levels in flood-plain aquifer at wells along the upper and middle main stem of the Mojave River, 

April 1992-September 1994.

recent inventory of pumpage completed for the 

Mojave River basin adjudication (James C. Hanson, 

written commun., 1995), pumpage from the floodplain aquifer during 1994 also is estimated to have 

been about 120,000 acre-ft. Of this 1994 total, about 

50,000 acre-ft was pumped from the flood-plain 

aquifer along the upper main stem of the Mojave 

River, about 50,000 acre-ft along the middle main 

stem, and about 20,000 acre-ft along the lower main 

stem.

GROUND-WATER DISCHARGE TO RIVER

One objective of this study was to determine the 

quantity of ground-water discharge to the Mojave 

River. During water years 1992-94, groundwater 

discharged primarily along two reaches of the main 

stem between approximately river miles 12 and 18 in 

the Upper and Lower Narrows area and between river 

miles 99 and 100 near the mouth of Afton Canyon. As 

mentioned earlier, ground water also discharged at the

26 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
Waterman Fault (about river mile 60) for a few days 

in March 1993 following wintertime storm runoff and 

filling of the flood-plain aquifer immediately upstream 

from the fault. Total discharge to the river at the fault 

was probably less than 100 acre-ft.

Hydrographs of mean daily discharges at gaging 

stations near Victorville and Afton Canyon, similar to 

those of figures 11 and 13, were used to estimate 

ground-water discharge upstream from the gages. 

Several researchers (Barnes, 1939 and 1940; Chow, 

1964; Daniel and others, 1970; and Linsley and others, 

1975) have proposed different empirical procedures to 

analyze and separate various flow components of 

streamflow hydrographs. During many years, the river 

flow near Victorville and in Afton Canyon consists 

entirely of ground-water discharge, and thus the base 

flow is easily determined (for example, see water 

years 1950 and 1989 in fig. 11). However, during 

most years, some storm runoff occurs, and the task 

becomes one of separating the base flow from the total 

flow.

For aquifers such as the flood-plain aquifer 

along the Mojave River, that both discharge water to 

the stream during non-storm periods and that are 

recharged almost entirely by the stream during storm 

runoff, the hydrograph-separation procedure proposed 

by Daniel and others (1970) is the most appropriate 

procedure. This procedure, unlike others, allows for 

the cessation of discharge from the aquifer to the 

stream during times when flow is actually in the 

opposite direction and the aquifer is being recharged 

by the stream. Because the procedure, to the author's 

knowledge, has not been fully utilized in any other 

study, it will be described here in some detail.

An idealized (dimensionless) hydrograph of a 

stream immediately preceding, during, and following 

a single peak in discharge caused by overland storm 

runoff is shown in figure 24. The hydrograph consists 

basically of three segments: The approach segment 

(ab), a rising segment (be), and the recession segment 

(eg). On these segments, b represents the point of rise 

in stream discharge, c represents the peak in discharge, 

d represents a point of inflection, and e,f, and g are 

three other characteristic points on the recession 

segment.

During the approach segment (ab), the aquifer is 

draining to the stream and all streamflow is base flow.

At point &, overland storm runoff reaches the stream, 

and the discharge increases until it peaks at point c. At 

point b, stage in the river begins to rise and the 

hydraulic gradient between the stream and aquifer 

decreases, resulting in a decrease of discharge from 

the aquifer to the river. Shortly after point b, at which 

a reversal occurs in hydraulic gradient between stream 

and aquifer, the aquifer ceases to discharge to the 

stream (base flow is zero) and, instead, begins to be 

recharged by the stream.

The ground-water discharge (base flow) remains 

at zero until the stream peaks and point d (point of 

inflection) on the recession segment is reached. At 

point d, the falling stage in the river no longer exceeds 

the hydraulic head in the aquifer, and the hydraulic 

gradient once again reverses. At point d, groundwater again begins to discharge to the stream, and 

recharge from the stream ceases. Between points d 

and e, the river stage continues to decline, the 

hydraulic gradient between the aquifer and stream 

increases, and likewise the ground-water discharge to 

the stream also increases. At point/, all streamflow is 

once again base flow. The base flow recedes between 

points/and g at a rate that is the same as the initial rate 

between points a and b.

TIME

Figure 24. Idealized streamflow-hydrograph 

separation. (Letters a-g are time points referred to in 

text.)

Ground-Water Discharge to River 27
Several factors, most notably ground-water 

pumping and evapotranspiration, can markedly alter 

the shape of streamflow hydrographs during periods of 

base flow. Thus, many times the selection of points d, 

e,f, and g is not only arbitrary but also difficult. For 

practical purposes, accurate estimates of base flow can 

be made by assuming that at point b (point of rise in 

stream stage) the base flow immediately drops to zero, 

and likewise, the base flow remains at zero until point 

e (midway between d and/) where it instantaneously 

rises and equals the stream discharge. As Daniel and 

others (1970) point out, there is little loss in accuracy 

by separating the base flow and stormflow in such a 

manner, especially if one is using hydrographs of daily 

mean discharge. Also, water entering or leaving "bank

storage" (Daniel and others, 1970) is considered 

ground-water recharge or discharge, and it is not 

accounted for separately.

The technique is illustrated (fig. 25) for the 

gaging station at the Lower Narrows during water year 

1982. As shown in figure 25, there were three peaks in 

storm runoff that required hydrograph separation to 

estimate base flow. The first was a single, simple peak 

similar to the idealized peak in figure 24, and the 

second and third peaks followed in quick succession 

without the river reaching ground-water discharge 

conditions (point d) between peaks.

Ground-water discharge (base flow) from the 

flood-plain aquifer represents a significant part of 

Mojave River flow near Victorville, averaging about

1,000 r

9 800

O

o

LLJ 

(/) 

CC 

LLJ 

CL

LLJ 

LLJ 

LL

O

CD

^ 

O

LLJ 

O 

CC

< 

I

o

Stormflow 

Base flow

OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP 

1981 1982

Figure 25. Estimated stormflow and base flow for the Mojave River at Lower Narrows (gaging station 10261500) 

during water year 1982.

28 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
37 percent of the total flow since water year 1931. 

During some years, for example 1950 and 1989, all 

flow at Victorville was due to ground-water discharge 

because there was no storm runoff. The estimated 

annual base flow of the Mojave River near Victorville 

(gaging station 10261500) is shown in figure 26. 

Since water year 1900, there has been a long-term 

decline in base flow. During water years 1900-01 and 

1904-05 when the gaging station was at the Upper 

Narrows, annual base flow averaged about 30,000 

acre-ft. Later, during water years 1931-36 with the 

gage still at the Upper Narrows, the annual base flow 

averaged about 22,000 acre-ft. During the first six

years at the Lower Narrows, water years 1937-42, 

annual base flows averaged about 26,000 acre-ft. The 

difference between water years 1931-36 and 1937-42 

mainly reflects an increase due to ground-water 

discharge between the Upper and Lower Narrows. 

During the 1950's and early 1960's, the base flow 

steadily declined and was only about 14,000 acre-ft 

during water year 1967. The decline in base flow was 

temporarily reversed in the late 1960's and late 1970's 

as a result of large inflows from the headwaters and 

recharge to the flood-plain aquifer during water years 

1969,1978,1980, and 1983. The base flow reached 

an all-time low of about 4,000 acre-ft during water

40,000

DC

2 30,000

>

DC

UJ

Q.

IUJ 

UJ

u.

LJJ

O 20,000

O

LJ_ 

UJ

<

m

\

Br&ak in tine mfficates no record

10,000

Upper Narrows

0

1900 10 20 30 60 70 80 90 1994

WATER YEAR

Figure 26. Base flow of Moj'ave River near Victorville (gaging station 10261500) during water years 1900-01, 

1904-05, and 1931-94.

Ground-Water Discharge to River 29
year 1992. After the large inflow from the headwaters 

during water year 1993, base flow increased to about 

11,000 acre-ft during water years 1993 and 1994.

Estimated annual base flow of the Mojave River 

at Afton Canyon (gaging station 10263000) is shown 

in figure 27. Whereas ground-water discharge near

Victorville accounted for about 37 percent of the river 

flow, ground-water discharge from the flood-plain 

aquifer above the gage in Afton Canyon has accounted 

 for about 7 percent of the total river flow since water 

year 1930. Stormflow has accounted for the remainder. During water years 1930-32, the first 3 years

1,400

1,200

1,000

LU

DC 

LU 

0.

UJ

III

LLi

111 

DC 

O

O

LL 

HI

CO

600

400

200

1930 40 50 60 70 

WATER YEAR

90 1994

Figure 27. Base flow of Mojave River at Afton Canyon (gaging station 10263000) during water years 1930-32, 

1953-78, and 1981-94.

30 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
of gage operation at Afton Canyon, annual base flow 

averaged about 980 acre-ft. Following reinstallation 

of the gage during water year 1953, base flow 

generally declined until reaching a low of about 130 

acre-ft during water year 1976. Large quantities of 

runoff and ground-water recharge during water year 

1969 are reflected in the reversal of this decline, with 

base flow increasing to about 400 and 530 acre-ft 

during water years 1969 and 1970. The gage was not 

in operation for the large-runoff year of 1980, but 

during water year 1981 the annual base flow was at an 

all-time high for the period of record of about 1,200 

acre-ft. Again the base flow generally declined, and it 

was only about 280 acre-ft during water year 1992. 

Following the large quantity of runoff in water year 

1993, base flow at Afton Canyon was about 470 acreft during water year 1994.

While ground water continued to discharge to 

the river at the Lower Narrows and in Afton Canyon 

during water year 1994, the flood-plain aquifer was no 

longer discharging to other reaches of the river that 

previously had some base flow. As pointed out earlier, 

Camp Cady (river mile 82), Fork of Roads (mile 70), 

Fish Pond (mile 60), Grapevine (mile 55), Cottonwoods (mile 41), Point of Rocks (mile 34), and Lane's 

Crossing (mile 20) all were camping sites used by the 

explorers and pioneers of the 1800's because water 

was available from the river or shallow dug wells year 

round. When the base flow ceased at these sites is not 

known precisely, but the base flow at Camp Cady 

reportedly ceased in the early 1980's. Base flow at 

Forks of Road (at the Calico-Newberry Fault) probably ceased in the early 1960's, on the basis of marked 

changes in riparian vegetation that can be seen in 

aerial photographs. The river flowed at Fish Pond 

(Waterman Fault) for only a few days in late March 

1993 following the large quantity of runoff and aquifer 

recharge of the previous 3 months. Children were 

reportedly still using a pond near the Grapevine (in 

Barstow) for swimming as late as the 1950's. When 

base flow may have ceased at Cottonwoods (the probable camp site of Father Francisco Garc6s on March 

16, 1776) and at Point of Rocks is unknown. Perennial flow at Lane's Crossing last occurred during water 

year 1992, mainly due to leakage of wastewater from 

an underground pipe, and the river was dry at this site 

much of water year 1994 (see fig. 15). Total annual 

ground-water discharge to the river at these sites is

unknown, but it probably was a few hundred acre-feet 

at each site. Although some of the water was lost to 

evapotranspiration, much of the water probably 

reinfiltrated into the streambed within a short distance 

downstream.

GROUND-WATER RECHARGE FROM 

RIVER

Recharge to the flood-plain aquifer from 

infiltration of Mojave River water can be computed 

from measured streamflow losses between gaging 

stations and estimates of tributary inflow, base flow, 

manmade discharges, and evaporation of river water 

between the gages. The estimates of annual recharge 

to the flood-plain aquifer along the upper, middle, and 

lower main stem during water years 1931-94 are given 

in table 3 and plotted cumulatively in figure 28. 

Previous estimates of recharge during water years 

1969 and 1978 (Buono and Lang, 1980) are revised on 

the basis of estimated tributary inflow, base flow, and 

manmade discharges to the river.

The method and the computations for estimating 

recharge during water year 1993 are described herein. 

For the upper main stem, inflow from the headwaters 

(combined annual flow of gaging stations 10261000 

and 10260950) in water year 1993 was about 

430,000 acre-ft. The annual discharge at the gaging 

station at the Lower Narrows (10261500) was 290,000 

acre-ft. Therefore, the net streamflow loss along the 

upper main stem of the Mojave River was about 

140,000 acre-ft. Inflow along the upper main stem 

during water year 1993 included about 20,000 acre-ft 

from ungaged tributary streams, about 11,000 acre-ft 

of ground-water discharge to the river (base flow) at 

The Narrows, and about 12,000 acre-ft from fish 

hatcheries. There were no diversions from the upper 

main stem, and direct evaporation from the river was 

about 100 acre-ft on the basis of an estimated average 

river area of 22 acres and an annual free-water-surface 

evaporation of 65 in. (National Oceanic and 

Atmospheric Administration, 1982). By adding all 

inflow to the net streamflow loss and subtracting the 

river evaporation, one obtains an estimate for groundwater recharge from the upper main stem of the river 

of 180,000 acre-ft (rounded) during water year 1993 

(140,000 acre-ft + 20,000 acre-ft + 11,000 acre-ft + 

12,000 acre-ft -100 acre-ft = 182,900 acre-ft).

Ground-Water Recharge from River 31
Similarly for the middle main stem, the net 

streamflow loss between the gaging station at the 

Lower Narrows (10261500) and the gaging station at 

Barstow (10262500) was 160,000 acre-ft during water 

year 1993. Inflow between the gages included about 

20,000 acre-ft from ungaged tributary streams and 

6,900 acre-ft of wastewater discharge. Evaporation 

from the river surface was about 200 acre-ft on the 

basis of an estimated average river area of 32 acres 

and an annual free-water-surface evaporation of 75 in. 

(National Oceanic and Atmospheric Administration, 

1982). Thus, ground-water recharge from the middle 

main stem was about 190,000 acre-ft (rounded).

Finally for the lower main stem, net 

streamflow loss between the gaging station at Barstow 

(10262500) and the gaging station at Afton Canyon 

(10263000) was 56,000 acre-ft during water year

1993. Inflow between the gages included about 

30,000 acre-ft from ungaged tributary streams and 

about 330 acre-ft of ground-water discharge to the 

river (base flow at Afton Canyon). Evaporation from 

the river surface was about 5 acre-ft, on the basis of an 

estimated average river area of 0.7 acre and an annual 

free-water-surface evaporation of 80 in. (National 

Oceanic and Atmospheric Administration, 1982). 

Thus, ground-water recharge from the lower main 

stem was about 86,000 acre-ft (rounded).

The plot of cumulative annual recharge (fig. 28) 

indicates that the flood-plain aquifer along the upper 

and middle main stem receives some recharge each 

year; whereas the aquifer along the lower main stem is 

recharged only during years of large runoff (for 

example, water years 1969,1980,1983, and 1993). 

Also, recharge along the upper and middle main stem

Table 3. Estimated annual recharge to the flood-plain aquifer from the Mojave River, water years 1931-94 

[Recharge in thousands of acre-feet]

Water 

year

1931

1932

1933

1934

1935

1936

1937

1938

1939

1940

1941

1942

1943

1944

1945

1946

1947

1948

1949

1950

1951

1952

Main stem reach

Upper

18

51

25

18

48

28

59

76

35

29

58

25

61

41

40

35

37

13

23

13

3

64

Middle Lower

22 0

52 39

24

24

33

20

56

70

29

27

60

25

49

46

35

33

35

26

23

21

21

56

Water 

year

1953

1954

1955

1956

1957

1958

1959

1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

Main stem reach

Upper

18

53

25

23

30

82

26

18

12

65

15

20

31

91

78

33

100

37

22

19

55

27

Middle

22

31

22

22

20

81

20

19

19

26

17

17

17

45

68

19

160

23

20

23

34

18

Lower

0

0

0

0

0

22

0

0

0

1

0

0

0

3

8

0

100

0

0

0

0

0

Water 

year

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

Main stem reach

Upper

18

26

24

200

79

140

26

54

120

41

38

49

17

27

18

15

54

72

180

45

Middle

16

20

28

170

67

110

23

37

110

30

25

21

18

21

17

16

18

31

190

18

Lower

0

0

0

14

*6

2 100

0

0

100

0

0

0

0

0

0

0

0

0

86

0

Estimated from similar streamflow conditions during water year 1967.

2Estimated from percentage of flow at Barstow that was recharged along the lower main stem during water years 1969 and 

1993.

32 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
was comparable until the early 1950's when several 

thousand acre-feet of fish-hatchery water began to be 

discharged each year to the upper main stem thus 

recharging the flood-plain aquifer. Annual recharge 

along the upper main stem averaged about 46,000 

acre-ft during water years 1931-94, and recharge along 

the middle main stem averaged about 39,000 acre-ft 

during this same period. During the 44 years that the 

annual recharge can be estimated along the lower main 

stem (water years 1931-32 and 1953-94), it averaged 

about 11,000 acre-ft.

Changes in ground-water storage can be estimated if changes in water-table altitude and the specific yield of the aquifer are known. On the basis of 

the water-table rise from November 1992 to March 

1993 (fig. 29), the saturated volume of the flood-plain 

aquifer increased by about 1,300,000 acre-ft, Using 

an average specific yield of 34 percent for the upper 

main stem, 22 percent for the middle main stem, and 

17 percent for the lower main stem, the author estimates that ground-water storage increased by about 

300,000 acre-ft during November 1992-March 1993.

3,000

1930 55 60 65 70 

WATER YEAR

80

J^JL 

85 90 1994

Figure 28. Cumulative annual recharge to the flood-plain aquifer from the Mojave River along the upper and middle 

main stem during water years 1931-94 and along the lower main stem during water years 1931-32 and 1953- 

94.(Queried where uncertain; see table 3.)

Ground-Water Recharge from River 33
Water-table-change maps also were prepared for 

the periods November 1991 to March 1992 and 

November 1993 to March 1994, but the maps are not 

included in this report. It is estimated, using the 

method described above, that recharge to the floodplain aquifer exceeded discharge, and ground-water 

storage increased by about 50,000 acre-ft during 

November 1991-March 1992 and by about 30,000 

acre-ft during November 1993-March 1994. Because 

the river was dry along the lower main stem all of 

water years 1992 and 1994, except for base flow at 

Afton Canyon, all of the recharge to the flood-plain

aquifer occurred along the upper and middle main 

stem.

Water-table change maps similar to figure 29 are 

useful in determining the areas between the gaging 

stations that did or did not receive recharge from the 

river. For example, water-table rises during the winter 

of 1993 indicate that ground-water recharge along the 

upper main stem occurred mainly along ephemeral 

reaches of the river between miles 0 and 10. Along 

the middle main stem, most of the recharge occurred 

between Hodge and Barstow; likewise, most of the 

recharge along the lower main stem occurred upstream

R5W R4W R2W 117° R1W R1E R4E 116-30' R5E R6E

' / -e

!/.._.._._. £ »--.-- 4 

T7N

T6N

T5N 

34°30'

T4N

T3N

Water-table rise, in feet

1 to 4 

4 to 8 

8 to 16

16 to 48 

Greater than 48

Observation well

Base from California. South Hall, 1 500.000.1961 revised 1981

Figure 29. Areas of water-table rise along the Mojave River, November 1992 to March 1993.

34 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
from Daggett. Such observations also are useful in the 

preliminary siting of artificial-recharge facilities that 

will rely on infiltration of water through the streambed 

or surface of the flood plain.

STREAMFLOW DEPLETION

Withdrawals from the flood-plain aquifer, by 

both ground-water pumping and transpiration by 

phreatophytes, cause depletions in streamflow. The 

withdrawals from the aquifer may cause river water to 

enter the aquifer, or they may "capture" ground water 

that normally would have been discharged to the river. 

In either case, the net effect is the same a depletion 

in streamflow.

The magnitude and timing of the streamflow 

depletion depend on the transmissivity of the aquifer 

(T), the specific yield (5v), and the distance from the 

point of stress (well or phreatophyte) to the river (r). 

Jenkins (1968a,b) developed a parameter known as 

stream-depletion factor (sdf) that characterizes these 

three variables. The sdf is equal to the distance 

squared times the specific yield divided by transmissivity (r*Sy/T), and it is expressed in units of days.

The use of sdf in determining streamflow 

depletion can be illustrated by an example (fig. 30). 

Consider a well 720 ft (r) from the river that is 

pumped for 1 month and then turned off. For this 

example, the transmissivity (7) is assumed to be 

13,000 ft2/d and the specific yield (Sy) 25 percent;

12 24 36 48 60 72 84 96 108 

TIME SINCE PUMPING BEGAN, IN MONTHS

120

Figure 30. Streamflow depletion by a well that is 

pumped continuously for one month 720 feet from a 

stream. (Modified from Burns, 1983.)

thus, sdf is 10 days. The graph shows the percentage 

of the volume pumped that comes from the stream or 

is prevented from entering the stream this is the 

streamflow depletion. During the 1 month that the 

well is pumped, the river will be depleted by about 50 

percent of the total volume pumped. During the 

second month (after pumping has ceased), the river 

will be depleted by about 24 percent of the volume 

pumped the first month. As can be seen from the 

graph, the effects of pumping are small after a few 

months, but they have not completely dissipated even 

after 10 years (120 months).

A series of curves for a range of sdf values is 

shown in figure 31. The curves show the streamflow 

depletion that would be caused by continuously 

pumping a well for 60 months (5 years) at various 

distances from the river. As in the previous example, 

it is assumed that transmissivity of the flood-plain 

aquifer is 13,000 fWd and specific yield is 25 percent. 

As indicated, a continuously pumped well 720 ft from 

the river (sdf=10 d) will deplete stream- flow by about 

50 percent of the first month's pumpage, by about 80 

percent of the first year's pumpage, and by about 91 

percent of the first 5 years' pumpage.

The curves in figure 31 can be used to estimate 

streamflow depletion for any combination of r, Sy, and 

T. For example, for a well 1,500 ft from the river in an 

area where the specific yield is 30 percent and transmissivity is 20,000 ft2/d, sdf would be equal to 34 

days, and the curve for sdf=30 days could be used. It 

should be noted that simplifying assumptions 

(discussed by Jenkins, 1968a,b) may preclude the use 

of the curves for a particular location of interest. Also, 

Wallace and others (1990) discuss the appropriate 

analytical techniques to determine streamflow depletion for wells with cyclic pumping, such as agricultural irrigation wells.

In addition to the analytical techniques that can 

be used for individual wells, streamflow records at 

gaging stations can be used to estimate regional 

streamflow depletion by wells and evapotranspiration. 

Tschmkel (1963) and Daniel (1976) present methods 

to compute evapotranspiration for short periods 

(several months) based on the difference between 

actual observed streamflow and the theoretical 

"potential streamflow" determined from the recession 

index. The recession index is the time required for 

natural ground-water discharge to a stream (base flow) 

to decline through one log cycle (decline of 90

Streamflow Depletion 35
percent) in the absence of any evapotranspiration, 

pumping, or recharge.

Using larger versions of figures 11 and 13, the 

author estimated the recession index for the Mojave 

River to be about 36 years at the Lower Narrows and 

about 40 years at Afton Canyon. Thus, without any 

recharge, evapotranspiration, or pumping, base flow of 

the Mojave River would decline 90 percent during a 

36- to 40-year period (about a 6-percent annual 

decline). The recession index was computed from the 

slope of a line drawn through the annual high wintertime base flows using several consecutive years not 

significantly affected by storm runoff and aquifer recharge (for example, see water years 1948-51 in fig. 11 

and water years 1953-57 in fig. 13). The winter-time

high base flow occurs each year when the depletion 

effects of evapotranspiration and pumping are at a 

minimum.

Streamflow hydrographs of selected years with 

little storm runoff are shown in figures 32 and 33. 

"Potential base flow" equivalent to the recession index 

line described above represents the highest wintertime 

Streamflow, exclusive of any stormflow. For convenience of computation, potential base flow is assumed 

to be constant each water year rather than declining 

about 6 percent annually. With minor adjustments 

during short periods of storm runoff, the annual 

Streamflow depletion is the difference between 

potential base flow and the actual daily mean 

discharges. For the Mojave River at Afton Canyon

100

'90

80

S 70

- 0-

F

LU

60

50 |g

9 £ 40

2

01 30

20

10

0

TransmlssMty 13,000 feet squared per day 

Specific yield 25 percent

0 12 24 36 48 

TIME SINCE PUMPING BEGAN, IN MONTHS

60

Figure 31 . Streamflow depletion by a well that is pumped continuously for 60 months for various stream-depletion 

factors (sdf) and distances (r) from a stream. (Modified from Burns, 1983.)

36 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
(fig. 32), the annual streamflow depletion is mainly 

due to evapotranspiration, as the gaging station is 

about 15 mi downstream from any significant 

pumping from the flood-plain aquifer. Also, the base 

flow is derived from ground-water discharge along a 

1-mile reach directly upstream from the gage. On the 

other hand, the streamflow depletion at the Lower 

Narrows (fig. 33) is partly due to evapotranspiration, 

but it is mainly due to ground-water pumping.

Annual streamflow depletion of the Mojave 

River at Afton Canyon is shown in figure 34 for 

selected water years. Streamflow depletion was not 

estimated for years when stormflow precluded identification of the high wintertime base flow. The depletion is due mainly to transpiration of phreatophytes 

along a 2-mile reach upstream from the gaging station 

and, to a much lesser degree, to evaporation from the 

river along the 1-mile reach of nearly perennial flow 

above the gage. The phreatophytes in Afton Canyon, 

which derive their water supply from both soil 

moisture and ground water consist mainly of tamarisk

or saltcedar (Tamarix sp.) but also include screw bean 

mesquite (Prosopic pubescent), honey mesquite (P. 

glandulosa), saltgrass (Distichlis spicata), cottonwood 

(Populus fremontii), black willow (Salix nigra), and 

desert willow (Chilopsis linearis). The phreatophytes 

grow in varying densities in an area of about 300 acres 

upstream from the gaging station. As can be seen in 

figure 34, evapotranspiration annually consumed 300 

to 900 acre-ft of water from the flood-plain aquifer 

and averaged about 600 acre-ft. Annual evaporation 

directly from the river, as pointed out earlier, averages 

about 5 acre-ft

The annual evapotranspiration estimates of 1 to 

3 ft represent the entire flood-plain environment. The 

average of 2 ft probably is biased on the low side 

because evapotranspiration during years with significant wintertime stormflow was not estimated. These 

evapotranspiration rates agree fairly well with the 

results of a water-budget study along the Gila River 

flood plain in Arizona (Culler and others, 1982) and 

energy-budget evapotranspiration measurements

1985 1986 

WATER YEAR

1987

Figure 32. Estimated streamflow depletion for Mojave River at Aftorr Canyon (gaging station 10263000) during 

water years 1985-87.

Streamflow Depletion 37
along the Pecos River flood plain in New Mexico 

(Weeks and others, 1987). Agreement with studies of 

tank-measured evapotranspiration (Gatewood and 

others, 1950; van Hylckama, T.E.A., 1980) is poor. As 

pointed out by Weeks and others (1987, p. 7 and 30), 

the much larger evapotranspiration rates determined 

from tank experiments are probably due to oases 

effects on the tanks, and they probably represent the 

maximum rates of evapotranspiration that might occur 

with an unlimited water supply. Extrapolation of tankexperiment data to natural flood-plain environments 

may lead to erroneous conclusions concerning water 

consumption in the natural environment.

A comparison of annual streamflow depletion 

(fig. 34) and annual base flow at Afton Canyon (fig. 

27) indicates a close correlation after about water year 

1958. This suggests that, like base flow, evapotranspiration is greatest when the water table is highest. 

One might hypothesize that the more water readily 

available to the phreatophytes, the more they will 

consume. The data from most years after 1958 support

this hypothesis. The lack of correlation between 

streamflow depletion and base flow prior to 1958 may 

be the result of a change in phreatophyte composition, 

but this is uncertain. An estimated 70 percent of the 

native riparian vegetation in Afton Canyon reportedly 

has been replaced by tamarisk (Johnson, 1989, p. 33). 

Tamarisk, a native of the Mediterranean area, was 

thought to have been introduced to the canyon in the 

early 1900's; however, extensive tamarisk stands were 

not noted until the 1960's. Stress on the native 

vegetation during water years 1948-65 (fig. 3), a 

period having only three years of above-normal 

precipitation, many have contributed to tamarisk 

proliferation in the canyon.

To the author's knowledge, the earliest mention 

of tamarisk growing along the lower main stem of the 

Mojave River was in the early 1950's by the Bureau of 

Reclamation (1952). Tree-ring counts on three 

specimens of old-growth tamarisk collected for this 

study in a U.S. Bureau of Land Management controlled burn area about 1 mi above the gaging station

1948 1949 

WATER YEAR

1950

Figure 33. Estimated streamflow depletion for Mojave River at Lower Narrows (gaging station 10261500) during 

water years 1948-50.

38 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
indicated germination dates of 1969,1971, and 1973. 

However, older specimens of tamarisk may exist 

elsewhere in Afton Canyon.

The estimated annual streamflow depletion of 

the Mojave River near Victorville for selected water 

years is shown in figure 35. Here again, streamflow 

depletion was not estimated for years when 

stormflows precluded identification of the high 

wintertime base flow. During the four years that 

depletion could be computed at the Upper Narrows 

(water years 1931, 33, 34, and 36), annual depletion 

averaged about 12,100 acre-ft. During the first four 

years that depletion could be computed at the Lower 

Narrows (water years 1939,40,42, and 46), annual 

depletion averaged 15,700 acre-ft. The 3,600-acre-ft 

difference in depletion between the Upper and Lower 

Narrows can be attributed to evapotranspiration from

about 800 acres of open water, marsh, cottonwoods, 

willows, and grassy bottomland and to ground-water 

pumping to irrigate about 200 acres of alfalfa.

Since the late 1930's, the annual depletion at the 

Lower Narrows has ranged from about 8,000 to 

20,000 acre-ft and averaged about 15,000 acre-ft, but a 

general long-term decline has occurred. The reasons 

for this long-term decline are unclear. It could be due, 

in part, to a long-term decline in ground-water 

pumpage from the flood-plain aquifer upstream from 

the gaging station, although the lack of pumpage 

records do not allow this to be verified. The long-term 

decline in streamflow depletion could also be due, in 

part, to lowering of the water table in former swamps 

and wetlands near the Upper Narrows and conversion 

to a cottonwood and willow woodland that probably 

would consume less water (Myers, 1992).

1,000

900

800

700

600

500

400

300

200

100

0

25,000 n:

1930 40 50 60 70 

WATER YEAR

90 1994

Figure 34. Streamflow depletion of Mojave River at 

Afton Canyon (gaging station 10263000) caused mainly 

by evapotranspiration during selected water years. 

(Open circle indicates no flow at times during water 

year; consecutive years joined by line.)

20,000

15,000

10,000

5,000

1930 40 50 60 70 

WATER YEAR

90 199'

Figure 35. Streamflow depletion of Mojave River at 

Lower Narrows (gaging station 10261500) caused by 

ground-water pumping and evapotranspiration during 

selected water years. (Consecutive years joined by 

line.)

Streamflow Depletion 39
It is not possible to directly separate streamflow 

depletion caused by evapotranspiration and depletion 

caused by ground-water pumping. However, if one 

assumes that evapotranspiration of the flood-plain 

environment near Victorville is similar to the evapotranspiration of the flood-plain environment at Afton 

Canyon, then 2,000 to 6,000 acre-ft would be consumed annually by the approximately 2,000 acres of 

open water, marsh, salt grass, cottonwoods, and 

willows upstream from the gaging station near 

Victorville, This would account for about one-quarter 

of the streamflow depletion since the late 1940's; the 

remaining three-quarters would be due to groundwater pumping.

Evapotranspiration along the main stem of the 

Mojave River has been estimated in the past using a 

variety of methods, all of which assume a constant 

annual water use of phreatophytes ranging from 3 to 7 

ft (based on annual water-consumption estimates from 

tank experiments). The California Department of 

Public Works (1934) estimated that in 1929 approximately 7,800 acres of phreatophytes consumed 

40,000 acre-ft of water. The Bureau of Reclamation 

(1952) estimated that annual evapotranspiration from 

about 11,000 acres of phreatophytes, open water, and 

wetted stream channel consumed about 35,000 acre-ft. 

A recent study completed for the California 

Department of Fish and Game estimates that about 

8,500 acres of phreatophytes annually consumed about 

30,000 acre-ft of water (Thomas W. Bilhorn, private 

consultant, written commun., 1993). On the basis of 

the evapotranspiration estimates for the flood-plain 

environment at Afton Canyon developed by this study, 

annual evapotranspiration probably varies by at least 

threefold, depending on prevailing hydrologic conditions. The estimate of 30,000 acre-ft probably is 

fairly accurate for "wet" years when the water table is 

high and large quantities of soil moisture are readily 

available for consumption. During periods of drought, 

however, total annual evapotranspiration along the 

Mojave River may be on the order of 10,000 acre-ft.

FACTORS CONTROLLING RIVERAQUIFER INTERACTION

Many factors control the river-aquifer 

interaction, but probably the most important factors 

directly controlling ground-water recharge are the 

magnitude and duration of stormflows, the

permeability of the streambed, and the volume of the 

unsaturated zone in the flood-plain aquifer. Flow 

occurred along the entire length of the main stem 

during the winter of 1993, and the water-table rise that 

occurred during this period of stress reflects the 

combined hydraulic effects of all these factors. From 

the water-table profile (fig. 22) and the water-table rise 

(fig. 29), one can see that along the upper and middle 

main stem, most of the ground-water recharge 

occurred along ephemeral reaches of the river where 

there was a thick unsaturated zone in the flood-plain 

aquifer. Along the lower main stem, even though 

much of the aquifer between Daggett and Camp Cady 

was unsaturated, recharge was relatively small. The 

lack of recharge along much of the lower main stem 

was due mainly to the presence of fine-grained, lowpermeability materials in the streambed and 

subsurface.

Ground-water pumping, in addition to directly 

depleting streamflow, is a major factor causing dewatering of the aquifer and creating unsaturated space 

in the flood-plain aquifer. Phreatophytes also deplete 

streamflow, but they have less immediate effect on I 

ground-water recharge during periods of storm runoff. ! 

Phreatophytes grow in areas where the water table is 

within a few feet of land surface and where there is 

little storage space remaining in the aquifer.

POTENTIAL FOR ARTIFICIAL RECHARGE

Reaches of the river channel and flood plain that 

are hydraulically suitable for artificial recharge are 

limited. The most suitable reaches are those that 

naturally accept large quantities of recharge during 

periods of stormflow. The most favorable reach along 

the upper main stem extends from river miles 0 to 10. 

Along the middle main stem, the reach from 

Helendale to Barstow (river miles 32 to 53) has 

favorable hydraulic conditions, and the reach between 

Hodge and Barstow (river miles 41 to 53) appears to 

be the most favorable. Along the lower main stem, the 

reach between Barstow and the Calico-Newberry 

Fault (river miles 53 to 72) has some potential for 

artificial recharge, but storage space in the aquifer is 

relatively small because of a shallow water table and a 

narrow flood plain along much of this reach.

The first 10 mi of the upper main stem already is 

receiving artificial recharge by releases of imported 

water from Silverwood Lake and from the Morongo

40 Ground-Water and Surface-Water Relations Along the Mojave River, Southern California
fc*

Figure 36. Mojave Water Agency's release of imported water to upper main stem of Mojave 

River near river mile 4, August 29,1994. (View looking upstream with dry river channel in 

background. Discharge about 60 cubic feet per second.)

Basin Pipeline (fig. 36). In both cases, the river channel itself is being utilized to convey and percolate the 

imported water. Because the water table was several 

tens of feet below land surface even after the large 

quantity of recharge during water year 1993 and the 

flood plain is one-half mile or more in width, additional artificial recharge in this reach is possible.

Along the middle main stem, the Mojave Water 

Agency has conducted percolation tests at pond sites 

near Hodge and Lenwood. The ponds are located on 

the adjacent flood plain rather than on the river channel itself. Results of the two tests are favorable, although a source of recharge water is not yet available.

A source of water also is not yet available for 

artificial recharge along the lower main stem. Because 

very little water seems to percolate through the 

streambed during storm runoff along much of the 

lower main stem, it may not be possible to use the 

river channel or ponds for the percolation of imported 

water. The reach between Daggett and river mile 80 

contains considerable storage space (see fig. 22), but

additional testing would be necessary to identify an 

acceptable site and means for artificial recharge.

CONCLUSIONS

The Mojave River and the alluvial aquifer 

beneath its flood plain are in excellent hydraulic 

connection in many areas; a change in the flow 

conditions in one affects the other. The flood-plain 

aquifer receives virtually all of its recharge from the 

river, and most of the water originates in the headwaters. Annual recharge along the upper main stem 

averaged about 46,000 acre-ft during water years 

1931-94, and recharge along the middle main stem 

averaged about 39,000 acre-ft during the same 

period. During the 44 years that annual recharge was 

estimated along the lower main stem, it averaged 

about 11,000 acre-ft.

Virtually all of the recharge water is eventually 

consumed by ground-water pumping and evapotranspiration. During 1994, ground-water pumpage from 

the flood-plain aquifer was about 120,000 acre-ft.

Factors Controlling River-Aquifer Interaction 41
Annual evapotranspiration probably ranges from 

about 10,000 acre-ft during drought years to perhaps 

as much as 30,000 acre-ft during years of large stormflows and high-water-table conditions.

Ground-water pumping and evapotranspiration 

cause both seasonal and long-term depletion in 

streamflow. The depletion in streamflow is most 

evident at the Lower Narrows and Afton Canyon 

where water from the flood-plain aquifer discharges 

naturally to the river. Since the late 1940's, annual 

streamflow depletion at the Lower Narrows has varied 

from about 8,000 to 20,000 acre-ft and averaged about 

15,000 acre-ft. Annual base flow at the Lower 

Narrows has declined from an average of about 26,000 

acre-ft during water years 1937-42 to about 11,000 

acre-ft during water years 1993 and 1994. Most of the 

streamflow depletion at the Lower Narrows is 

attributed to ground-water pumping.

The magnitude and duration of stormflows, the 

permeability of the streambed, and the thickness and 

volume of the unsaturated zone in the flood-plain 

aquifer are the most important factors controlling 

ground-water recharge. Most of the recharge during 

water years 1992-94 occurred along ephemeral 

reaches of the upper and middle main stem where the 

streambed is permeable and where there was a thick 

unsaturated zone. Despite a large unsaturated zone 

beneath the flood plain along much of the lower main 

stem, recharge along the lower main stem was 

relatively small, even during years with large 

stormflows. This lack of recharge is due mainly to the 

presence of fine-grained, low-permeability materials 

in that reach of the streambed. The most favorable 

reaches of the river for artificial recharge, using either 

percolation ponds on the flood plain or the river 

channel itself, are those that receive large quantities of 

recharge naturally from streamflow.

REFERENCES CITED

Barnes, B.S., 1939, The structure of discharge recession 

curves: American Geophysical Union Transactions, v. 

20, p. 721-725.

 1940, Discussion on analysis of run-off characteristics by O.H. Meyer: American Society of Civil Engineers, v. 105, p. 104-106.

Buono, Anthony, and Lang, D.J., 1980, Aquifer recharge 

from the 1969 and 1978 floods in the Mojave River 

Basin, California: U.S. Geological Svvey Open-File 

Report 80-207, 25 p.

Bureau of Reclamation, 1952, Report on Victor Project, 

California: Boulder City, Nevada, Regional Director's 

Report, 42 p.

Burns, A.W., 1983, Simulated hydrologic effects of possible 

ground-water and surface-water management alternatives in and near the Platte River, south-central 

Nebraska: U.S. Geological Survey Professional Paper 

1277-G, 30 p.

California Department of Public Works, Division of Water 

Resources, 1934, Mojave River invest1 gation: Bulletin 

47, 249 p.

Chow, V.T., 1964, Handbook of applied hydrology: New 

York, McGraw-Hill.

Coues, Elliott, 1900, On the trail of a Spanish pioneer: The 

diary and itinerary of Francisco Garce"0 (missionary 

priest) in his travels through Sonora, Arizona, and California, 1775-1776: New York, Franc's P. Harper, 2 

vols., 499 p.

Culler, R.C., Hanson, R.L., Myrick, R.M., Turner, R.M., 

and Kipple, P.P., 1982, Evapotranspirrtion before and 

after clearing phreatophytes, Gila River flood plain, 

Graham County, Arizona: U.S. Geological Survey 

Professional Paper 655-P, 67 p.

Daniel, J.F., 1976, Estimating ground-wate- evapotranspiration from streamflow records: Water Resources 

Research, v. 12, no. 3, p. 360-364.

Daniel, J.F., Cable, L.W, and Wolf, R.J., 1970, Ground 

water-surface water relation during periods of overland 

flow: U.S. Geological Survey Professional Paper 700- 

B, p. 219-223.

Dawdy, D.R., and Burkham, D.E., 1970, Error analysis of 

streamflow data for an alluvial stream: U.S. Geological Survey Professional Paper 655-C, 13 p.

Dibble, E.F., 1967, Mojave Water Agency, water production 

verification program: Redlands, California, 39 p.

Earle, David, 1992, Overview of the history of the upper 

Mojave River area, in Natural resources inventory of 

the Mojave River corridor: Riverside, California, 

Herra Madre Consultants, Inc., p. 15-72.

Gatewood, J.S., Robinson, T.W, Colby, B.R., Hem, J.D., 

and Halpenny, L.C., 1950, Use of water by bottomland vegetation in lower Safford Valley, Arizona: U.S. 

Geological Survey Water-Supply Paper 1103, 210 p.

Hardt, W.F., 1971, Hydrologic analysis of Mojave River 

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