Water Budgets of the Walker River Basin and 

Walker Lake, California and Nevada

Scientific Investigations Report 2009–5157 

Prepared in cooperation with the Bureau of Reclamation

U.S. Department of the Interior

U.S. Geological Survey

Diversions Pumpage

Precipitation

Evaporation

Pumpage

Walker Lake Reach

Riparian ET

Recharge

Evaporation

Precipitation

Subsurface

inflow

Subsurface

flow

Pumpage

Diversions

Return

flow

Local

runoff

Walker Lake

ET by other than

riparian vegetation

ET by other than

riparian vegetation

Riparian,

other ET

Walker River inflow

Stream

infiltration Stream

infiltration

Subsurface

discharge

Subsurface

discharge

Induced

recharge

Induced

recharge

Subsurface outflow

to Double Spring

Subsurface outflow to

Wabuska lineament

Wabuska–Schurz Reach Schurz–Lake Reach

Weber

Reservoir

Walker River outflow

Riparian and

saltcedar ET
Cover: Photographs from left to right: 

Left: Alfalfa field in Antelope Valley, Nevada and California, with the Sweetwater Range in the 

background, May 31, 2006.

Middle: Sacks filled with onions during the 2006 autumn harvest, Pete Hendrichs Road, 

Mason Valley, Nevada, October 13, 2006.

Right: View from Walker Lake looking southwest at Mount Grant, Nevada, February 28, 2005. 

(Photographs taken by Thomas J. Lopes, U.S. Geological Survey.)

Diagram: Water budget components for the lower Walker River basin, Nevada. The length of 

the arrow indicates the relative amount of flow. The Walker Lake reach includes surrounding 

riparian and phreatophytic vegetation and the town of Walker Lake.
Water Budgets of the Walker River Basin and 

Walker Lake, California and Nevada

By Thomas J. Lopes and Kip K. Allander

Prepared in cooperation with the Bureau of Reclamation

Scientific Investigations Report 2009–5157

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Lopes, T.J., and Allander, K.K., 2009, Water budgets of the Walker River basin and Walker Lake, California and 

Nevada: U.S. Geological Survey Scientific Investigations Report 2009–5157, 44 p.
iii

Contents

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

Introduction ....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................2

Description of the Walker River Basin..............................................................................................2

Physiography................................................................................................................................6

Climate...........................................................................................................................................9

Native, Invasive, and Agricultural Vegetation ........................................................................9

Population ...................................................................................................................................11

Previous Investigations......................................................................................................................11

Methods.........................................................................................................................................................13

Precipitation Normals ........................................................................................................................13

Streamflow Normals at Gaging Stations ........................................................................................15

Streamflow Normals at Ungaged Drainages .................................................................................19

Correction to Evapotranspiration Rates..........................................................................................23

Upper Walker River Basin 

Surface-Water Budgets................................................................................................................25

Antelope Valley ...................................................................................................................................25

Smith Valley .........................................................................................................................................26

Bridgeport Valley ................................................................................................................................27

East Fork of the Walker River ...........................................................................................................28

Mason Valley.......................................................................................................................................28

Lower Walker River Basin 

Water Budgets................................................................................................................................28

Wabuska to Schurz Reach................................................................................................................30

Overall Water Budget ...............................................................................................................30

Groundwater Budget.................................................................................................................34

Schurz to Walker Lake Reach ..........................................................................................................35

Overall Water Budget ...............................................................................................................35

Groundwater Budget.................................................................................................................37

Walker Lake.........................................................................................................................................38

Summary........................................................................................................................................................41

Acknowledgments.......................................................................................................................................42

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

Figures

Figure 1. Map showing locations of selected features in the Walker River basin,

California and Nevada ..................................................................... 3

Figure 2. Photograph showing view looking north from the southwestern end of

Walker Lake, Nevada ..................................................................... 4

Figure 3. Graph showing lake-surface altitude and dissolved-solids concentrations of

Walker Lake, Nevada, from 1882 through September 30, 2008 ........................ 4

Figure 4. Photograph showing vew looking upstream and southwest at the

streamflow-gaging station Walker River near Wabuska, Nevada. .................. 5

Figure 5. Photograph showing Bridgeport Valley, California, looking south from

Highway 395 towards the Twin Lakes area and 12,000-foot peaks of the

Sierra Nevada. .............................................................................. 5

Figure 6. Photograph showing riparian vegetation along the Walker River between the

Wabuska gage and Weber Reservoir, Nevada .......................................... 6

Figure 7. Photograph showing vew looking south at Walker Lake from the mouth of

the Walker River, Nevada .................................................................. 7

Figure 8. Photograph showing view from northeastern Smith Valley looking southwest

towards Artesia Lake and the Pine Nut Range, Nevada .............................. 7

Figure 9. Photograph showing view from Walker Lake looking southwest at Mount

Grant, Nevada .............................................................................. 8

Figure 10. Photograph showing view from Walker Lake looking east at a thunderstorm

over the Gillis Range, Nevada ............................................................ 8

Figure 11. Map showing distribution of 88,600 acres of irrigated land in the Walker

River basin, California and Nevada, during the 2000 growing season ............... 10

Figure 12. Map showing distribution of precipitation in the Walker River basin,

California and Nevada ..................................................................... 14

Figure 13. Map showing locations of stream gages in the Walker River basin, California

and Nevada ................................................................................. 16

Figure 14. Map and table showing locations of drainages in California and Nevada that

were used to estimate runoff from ungaged drainages in the Walker River

basin .......................................................................................... 20

Figure 15. Graphs showing predicted compared to observed 1971–2000 streamflow

normals and constrained regressions compared to observed streamflow

normals ....................................................................................... 22

Figure 16. Schematic diagram showing water budget components for the lower Walker

River basin, Nevada ........................................................................ 29

Figure 17. Map showing selected areas of the lower Walker River basin, Nevada,

where net evapotranspiration was quantified .......................................... 31

Figure 18. Graphs showing annual stream discharge at Schurz, Nevada, compared to

annual discharge at the Wabuska gage prior to and after construction of

Weber Reservoir in 1934 and subset of data plotted on log scale to show

differences at low discharge............................................................... 33

Figure 19. Graph showing discharge at streamflow gaging stations Walker River near

Wabuska, Nevada, and Walker River at Lateral 2-A Siphon near Schurz,

Nevada ....................................................................................... 36

Figure 20. Graph showing dissolved-solids concentrations versus lake altitude,

Walker Lake, Nevada ..................................................................... 39
v

Tables

Table 1. Mean annual precipitation volumes for hydrographic areas in the Walker

River basin, California and Nevada, 1971–2000 .......................................... 9

Table 2. Summary of precipitation zone regression equations ................................. 13

Table 3. Streamflow normals at selected gaging stations with 30 complete years of

data, Walker and Carson River basins and Toiyabe Range, California and

Nevada, 1971–2000 ........................................................................ 15

Table 4. Streamflow data from drainages in the Wassuk Range, Nevada ..................... 17

Table 5. Estimated streamflow normals at selected gaging stations with less than 30

complete years of data, California and Nevada, 1971–2000 ........................... 18

Table 6. Estimated streamflow normals from ungaged drainages in the Walker River

basin, California and Nevada, 1971–2000 ................................................ 24

Table 7. Estimated evaporation from Walker Lake, Nevada, during the 1987–94 drought ... 25

Table 8. Summary of surface-water inflows in the upper Walker River basin,

California and Nevada ..................................................................... 26

Table 9. Summary of surface-water budgets for the upper Walker River basin,

California and Nevada, 1971–2000......................................................... 27

Table 10. Overall water budget for the Wabuska–Schurz reach, lower Walker River

basin, Nevada .............................................................................. 30

Table 11. Estimates of subsurface flow through Walker and Parker Gaps, lower

Walker River basin, Nevada ............................................................... 32

Table 12. Net evapotranspiration from selected areas of the lower Walker River basin,

Nevada ....................................................................................... 34

Table 13. Ground-water budget for the Wabuska–Schurz reach, lower Walker River

basin, Nevada .............................................................................. 35

Table 14. Overall water budget for the Schurz–Lake reach, lower Walker River basin,

Nevada ....................................................................................... 35

Table 15. Overall water budget from Wabuska to Walker Lake, lower Walker River

basin, Nevada .............................................................................. 37

Table 16. Ground-water budget for the Schurz–Lake reach, lower Walker River basin,

Nevada. ....................................................................................... 37

Table 17. Overall water budget for Walker Lake, Nevada.......................................... 38

Table 18. Water budget to maintain lake-surface altitudes between 3,952 and 3,986

feet at Walker Lake, Nevada ............................................................... 40
vi

Conversion Factors and Datums

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 0.004047 square kilometer (km2)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

acre-foot (acre-ft) 1,233 cubic meter (m3)

Flow rate

foot per year (ft/yr) 0.3048 meter per year (m/yr)

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year (m3/yr)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

mile per hour (mi/h) 1.609 kilometer per hour (km/h) 

Hydraulic conductivity

foot per day (ft/d) 0.3048 meter per day (m/d)

Transmissivity*

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d) 

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8

*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times 

foot of aquifer thickness [(ft3/d)/ft2]ft. In this report, the mathematically reduced form, foot 

squared per day (ft2/d), is used for convenience.

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) 

or micrograms per liter (μg/L).

Datums

Vertical coordinate information is referenced to National Geodetic Vertical Datum of 1929 

(NGVD 29).

Horizontal coordinate information is referenced to North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.
Water Budgets of the Walker River Basin and 

Walker Lake, California and Nevada

By Thomas J. Lopes and Kip K. Allander

Abstract

The Walker River is the main source of inflow to 

Walker Lake, a closed-basin lake in west-central Nevada. 

The only outflow from Walker Lake is evaporation from the 

lake surface. Between 1882 and 2008, upstream agricultural 

diversions resulted in a lake-level decline of more than 

150 feet and storage loss of 7,400,000 acre-feet. Evaporative 

concentration increased dissolved solids from 2,500 to 

17,000 milligrams per liter. The increase in salinity threatens 

the survival of the Lahontan cutthroat trout, a native species 

listed as threatened under the Endangered Species Act. This 

report describes streamflow in the Walker River basin and an 

updated water budget of Walker Lake with emphasis on the 

lower Walker River basin downstream from Wabuska, Nevada. 

Water budgets are based on average annual flows for a 30-year 

period (1971–2000).

Total surface-water inflow to the upper Walker 

River basin upstream from Wabuska was estimated 

to be 387,000 acre-feet per year (acre-ft/yr). About 

223,000 acre-ft/yr (58 percent) is from the West Fork of the 

Walker River; 145,000 acre-ft/yr (37 percent) is from the 

East Fork of the Walker River; 17,000 acre-ft/yr (4 percent) 

is from the Sweetwater Range; and 2,000 acre-ft/yr (less 

than 1 percent) is from the Bodie Mountains, Pine Grove 

Hills, and western Wassuk Range. Outflow from the upper 

Walker River basin is 138,000 acre-ft/yr at Wabuska. About 

249,000 acre-ft/yr (64 percent) of inflow is diverted for 

irrigation, transpired by riparian vegetation, evaporates from 

lakes and reservoirs, and recharges alluvial aquifers.

Stream losses in Antelope, Smith, and Bridgeport 

Valleys are due to evaporation from reservoirs and 

agricultural diversions with negligible stream infiltration 

or riparian evapotranspiration. Diversion rates in Antelope 

and Smith Valleys were estimated to be 3.0 feet per year 

(ft/yr) in each valley. Irrigated fields receive an additional 

0.8 ft of precipitation, groundwater pumpage, or both for a 

total applied-water rate of 3.8 ft/yr. The average corrected 

total evapotranspiration rate for alfalfa is 3.2 ft/yr so about 

0.6 ft/yr (15 percent) flushes salts from the soil. The diversion 

rate in Bridgeport Valley was estimated to be 1.1 ft/yr and 

precipitation is 1.3 ft/yr. The total applied-water rate of 

2.4 ft/yr is used to irrigate pasture grass.

The total applied water rate in the East Fork of the 

Walker River and Mason Valley was estimated to be 4.8 ft/yr 

in each valley. The higher rate likely is due to appreciable 

infiltration, riparian evapotranspiration, or both. Assuming a 

diversion rate of 3.0 ft/yr, stream loss due to infiltration and 

riparian evapotranspiration is about 3,000 acre-ft/yr along the 

East Fork of the Walker River and 14,000 acre-ft/yr in Mason 

Valley.

In the lower Walker River basin, overall and groundwater 

budgets were calculated for Wabuska to Schurz, Nev., 

and Schurz to Walker Lake. An overall water budget was 

calculated for the combined reaches. Imbalances in the water 

budgets range from 1 to 7 percent, which are insignificant 

statistically, so the water budgets balance. Total inflow to the 

Wabuska–Walker Lake reach from the river and others sources 

is 140,000 acre-ft/yr. Stream and subsurface discharge into 

the northern end of Walker Lake totals 110,000 acre-ft/yr. 

About 30,000 acre-ft/yr is lost on the Walker River 

Indian Reservation from agricultural evapotranspiration, 

evapotranspiration by native and invasive vegetation, domestic 

pumpage, and subsurface outflow from the basin through 

Double Spring and the Wabuska lineament. 

Alfalfa fields in the upper Walker River basin are lush 

and have an average corrected total evapotranspiration rate of 

3.2 ft/yr. Alfalfa fields on the Walker River Indian Reservation 

are not as lush and have a total corrected evapotranspiration 

rate of 1.6–2.1 ft/yr, which partly could be due to alkaline 

soils that were submerged by Pleistocene Lake Lahontan. The 

total applied-water rate is 7.0 ft/yr, almost twice the rate for 

alfalfa in the upper Walker River basin. Most of this excess 

water becomes induced recharge, which is irrigation water that 

infiltrates to the water table.

Surface and subsurface inflow to Walker Lake total 

130,000 acre-ft/yr. Virtually all outflow is evaporation from 

the lake and totals 162,000 acre-ft/yr at the 1971–2000 

average lake altitude of 3,959.3 feet. The difference between 

inflow and outflow is ‐32,000 acre-ft/yr. Storage change 

estimated directly is -29,000 acre-ft/yr for an imbalance of 

3,000 acre-ft/yr (2 percent). This imbalance is insignificant 

statistically so the water budget balances.

Water budgets were calculated to provide managers a 

range in supplemental inflows needed to maintain dissolvedsolids concentrations at 8,000, 10,000, and 12,000 milligrams 

per liter (mg/L). From about 700,000 to 2,000,000 acre-ft 
2 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

are needed to dilute the lake to these concentrations from the 

current (2008) concentration of 17,000 mg/L. From 26,000 to 

53,000 acre-ft/yr of supplemental inflow is needed to maintain 

concentrations of 8,000 to 12,000 mg/L. Years of supplemental 

inflow, above average inflow, or both, will be needed to raise 

the lake-surface altitude and dilute salts.

Introduction 

The Walker River basin is a topographically closed basin 

in east-central California and west-central Nevada (fig. 1). All 

surface water drains toward Walker Lake, the lowest point in 

the basin and the terminus of the Walker River (fig. 2). The 

Walker River is the main source of inflow, but small tributaries 

from adjacent mountains and groundwater also discharge 

into Walker Lake (Everett and Rush, 1967; Schaefer, 1980; 

Lopes and Allander, 2009). The only outflow from Walker 

Lake is evaporation from the lake surface. The Walker River 

has been diverted for irrigation in upstream valleys since 

1860, which has reduced flow into Walker Lake (Russell, 

1885; Horton, 1995). Between 1882 and 2008, agricultural 

diversions resulted in a lake-level decline of more than 150 ft 

and evaporative concentration increased dissolved solids 

from 2,500 to 17,000 mg/L (fig. 3). The increase in salinity 

threatens the survival of the Lahontan cutthroat trout, a species 

listed as threatened under the Endangered Species Act.

Section 2507 of Public Law 107‐171 (2002 Farm 

Bill) provided $200 million to be used by the Secretary of 

Interior, acting through the Commissioner of Reclamation, 

to provide water to at-risk natural desert terminal lakes. This 

bill was later amended under Public Law 108‐7, section 

207 to include this language, “Restoration of fish, wildlife, 

and associated habitats in watersheds of certain lakes.” The 

amendment specified that only Pyramid, Summit, and Walker 

Lakes in Nevada were to be considered under Section 2507, 

PL107-171.

In response to the 2002 Farm Bill, the U.S. Geological 

Survey (USGS), in cooperation with the Bureau of 

Reclamation, began a study to refine the water budget for 

Walker Lake and to develop the capability to predict how 

changes in upstream water management will affect flows 

in the lower Walker River basin. This is the final report 

from the study. Lopes (2005) described the objectives and 

tasks of the study; Lopes and Smith (2007) described the 

bathymetry of Walker Lake, Lopes and Medina (2007) 

estimated precipitation in west-central Nevada including the 

Walker River basin; Allander and others (2009) quantified 

evapotranspiration (ET) from Walker Lake and agricultural, 

native, and invasive vegetation; and Lopes and Allander 

(2009) described the hydrologic setting, groundwater flow 

directions, and a conceptual model of groundwater/surfacewater interactions from Smith Valley to Walker Lake.

Purpose and Scope

This report describes streamflow in the Walker River 

basin and presents an updated water budget of Walker Lake. 

The report emphasizes the lower Walker River basin, which 

is the area downstream from the streamflow-gaging station 

Walker River near Wabuska, Nev. (Wabuska gage, 10301500; 

figs. 1, 4). Surface-water budgets for the upper Walker River 

basin upstream from the Wabuska gage also are presented. 

Data for this study were collected from 2004 through 2008 and 

used with existing data to calculate average annual flows.

Water budgets are based on average annual flows for a 

30-yr period (1971–2000). Using average flows may give the 

impression of steady-state conditions but, as shown in figure 3, 

the lake level continues to decline and flows into and out from 

the lake vary annually. However, it was beyond the scope 

of this study to account for the transient nature of the basin 

hydrology.

Description of the Walker River Basin

The following is an abbreviated description of the Walker 

River basin from Lopes and Allander (2009). The Walker 

River basin is about 3,950 mi2 and straddles the California–

Nevada border (fig. 1). About 23 percent (920 mi2) of the 

basin is in California. Most streamflow in the basin originates 

as snowmelt in the Sierra Nevada, which reach an altitude of 

more than 12,000 ft (fig. 5). Snowmelt from the Sierra Nevada 

and other ranges flows down the East and West Forks of the 

Walker River, which merge in southern Mason Valley, Nev. 

Outflow from Mason Valley and inflow to the lower Walker 

River basin is measured at the Wabuska gage in northern 

Mason Valley. 

Bridgeport Reservoir on the East Fork of the Walker 

River and Topaz Lake on the West Fork of the Walker River 

are used for fishing and recreation, and have a combined 

useable storage capacity of about 103,000 acre-ft. Stored water 

is used to irrigate mostly alfalfa in Smith and Mason Valleys 

and to sustain a minimum streamflow into the Walker River 

Indian Reservation (Reservation). Streams also are diverted 

upstream from Bridgeport Reservoir to irrigate pasture grass 

(fig. 5) and upstream from Topaz Lake to irrigate mostly 

alfalfa fields in Antelope Valley.

Russell (1885) described lush cottonwood groves, willow 

stands, and meadows along the banks of the Walker River 

from its mouth at Walker Lake to many miles upstream. 

Since 1885, most cottonwood between the Wabuska gage and 

Weber Reservoir were cut down. Except for the cutting of 

cottonwood, the Walker River between the Wabuska gage and 

Weber Reservoir is relatively unaffected by human activities 

(fig. 6). Willows grow along the river, beaver built dams from 

willow branches, and grass meadows cover the inside banks of 

stream meanders. 
Introduction 3

tac09-4153_fig01

West Walker River

East Walker River

Walker

River

Walker

Lake

Topaz

Lake

Bridgeport

Reservoir

Artesia

Lake

Weber

Reservoir

Mono

Lake

Schurz

Walker

Wabuska

Yerington

Hawthorne

Coleville

Walker

Lake

Bridgeport

CARSON

CITY

Dayton

SMITH

VALLEY

ANTELOPE

VALLEY

WHISKEY

FLAT

MASON

VALLEY

ADRIAN

GAP

NEVADA

CALIFORNIA

ANCHORITE

PASS

AGAI PAH

HILLS

CALICO HILLS

MOUNTAINS

EXCELSIOR

PINE GROVE HILLS

PINE NUT RANGE

SINGATSE RANGE

DESERT MOUNTAINS

TERRILL MOUNTAINS

GILLIS RANGE

WASSUK RANGE

SIERRA

NEVADA

95

50

95

95

239

208

338

182

108

359

167

395

88

89

89

4

395

Mount

Grant

Parker

Butte

Double

Spring

SWEETWATER RANGE

110C

110B

110A

109

108

107

106

119°45' 119°30' 119°15' 119° 118°45' 118°30' 118°15'

39°

15'

39°

00'

38°

45'

38°

30'

38°

15'

38°

00'

37°

45'

Base from U.S. Geological Survey digital data, 1:24,000 and 1:100,000, 1978-88. Walker Lake 

average lake altitude of 3937.5 ft for November 2006; Projection: Universal Transverse 

Mercator, Zone 11, North American Datum of 1983. Shaded-relief base from 90-meter 

Shuttle Radar Topography Mission digital data, 2000.

CALIFORNIA

NEVADA

Area

of map

EXPLANATION

Hawthorne Army Ammunition Depot

Mason Valley Wildlife Management Area

Walker River Indian Reservation

Lower Walker River study area

Walker River basin boundary

Walker River hydrographic-area boundary—

 labeled with hydrographic area number

Walker Lake shoreline of 1882 (Rush, 1970)

Wabuska streamflow-gaging station (10301500)

110A

0 10 20 MILES

0 10 20 KILOMETERS

Figure 1. Locations of selected features in the Walker River basin, California and Nevada.
4 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Figure 2. View looking north from the southwestern end of Walker Lake, Nevada. The town of Walker 

Lake is in the left center of the photo. (Photograph taken by Thomas J. Lopes, April 23, 2004.)

Figure 3. Lake-surface altitude and dissolved-solids concentrations of Walker Lake, Nevada, from 1882 through 

September 30, 2008.

3,920

3,940

3,960

3,980

4,000

4,020

4,040

4,060

4,080

4,100

LAKE-SURFACE ALTITUDE, IN FEET ABOVE

NATIONAL GEODETIC VERTICAL DATUM OF 1929

DISSOLVED-SOLIDS CONCENTRATION, IN MILLIGRAMS PER LITER

1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Topaz Lake (1921)

Weber Reservoir (1934)

Bridgeport Reservoir (1924)

Topaz Lake storage

increased (1937)

2,000

4,000

8,000

6,000

12,000

10,000

14,000

18,000

Lake-surface altitude 16,000

Dissolved solids
Introduction 5

Figure 4. Vew looking upstream and southwest at the streamflow-gaging station Walker River near 

Wabuska, Nevada. (USGS station number 10301500). (Photograph taken by Thomas J. Lopes, April 23, 

2004.)

Figure 5. Bridgeport Valley, California, looking south from Highway 395 towards the Twin Lakes area 

and 12,000-foot peaks of the Sierra Nevada. Pasture grass in the foreground is irrigated by ditches that 

divert snowmelt. (Photograph taken by Thomas J. Lopes, June 3, 2008.)
6 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Weber Reservoir is used for fishing, recreation, and 

storing irrigation water on the Reservation. Downstream from 

Weber Reservoir, cottonwood grows along the Walker River 

to about 2 mi downstream from Schurz, Nev., near the 1882 

shoreline where cottonwood were first observed by Russell 

(1885). The Walker River continues downstream through 

stands of saltcedar, an invasive shrub also known as tamarisk. 

Saltcedar grows in alkaline lake clays that became exposed 

as Walker Lake receded. The river then discharges into the 

northern end of Walker Lake (fig. 7).

Physiography

The Walker River basin is in the Great Basin subdivision 

of the Basin and Range Physiographic Province. The Basin 

and Range is characterized by north-south trending mountain 

ranges separated by valleys. The Great Basin is the part of 

the Basin and Range that has no surface-water drainage to the 

ocean, is centered in Nevada, and includes parts of California, 

Idaho, Oregon, and Utah.

Many watersheds in the Great Basin are comprised 

of multiple valleys that are interconnected by streams and 

subsurface flow (Anning and Konieczki, 2005). Where 

hydraulically connected, rivers and groundwater flow between 

valleys, and the valley at the lowest altitude is the terminus for 

the watershed. Most watersheds in the Great Basin do not have 

perennial rivers so the terminus is a playa consisting of barren 

mud and salt flats with intermittent water, such as Artesia 

Lake in northern Smith Valley (fig. 8). Terminuses that have 

perennial water include Mono Lake, Calif., and the Great Salt 

Lake, Utah. Owens Lake, Calif., was a perennial terminal lake 

until the early 1900s when diversions turned the lake into a 

100 mi2 playa. Walker, Pyramid, and Summit Lakes are three 

of the few terminal lakes in the United States that support a 

fishery. 

Walker Lake fills a depression within the Walker Lane, 

a broad zone of mostly north-northwest trending faults that 

extends from near Las Vegas, Nev., to Honey Lake Valley, 

Calif. (Bonham, 1969; Stewart, 1988). Walker Lake is 

bounded on the west by the Wassuk Range and on the east 

by the Gillis Range. The Wassuk Range rises abruptly from 

the lake by more than 7,000 ft and has a maximum altitude 

of 11,239 ft at Mount Grant (fig. 9). The Gillis Range is not 

as steep and has a maximum altitude of 7,887 ft (fig. 10). The 

lowest altitude is 3,849 ft at the deepest part of Walker Lake 

(Lopes and Smith, 2007).

Figure 6. Riparian vegetation along the Walker River between the Wabuska gage and Weber 

Reservoir, Nevada. Bare soil in the foreground is lake sediment deposited during the Pleistocene. View 

looking south towards the Wassuk Range. (Photograph taken by Thomas J. Lopes, April 23, 2004.)
Introduction 7

Figure 7. Vew looking south at Walker Lake from the mouth of the Walker River, Nevada. 

(Photograph taken by Thomas J. Lopes, April 23, 2004.)

Figure 8. View from northeastern Smith Valley looking southwest towards Artesia Lake and the Pine 

Nut Range, Nevada. (Photograph taken by Thomas J. Lopes, February 6, 2008.)
8 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Figure 9. View from Walker Lake looking southwest at Mount Grant, Nevada. (Photograph taken by 

Thomas J. Lopes, February 28, 2005.)

Figure 10. View from Walker Lake looking east at a thunderstorm over the Gillis Range, Nevada. 

(Photograph taken by Thomas J. Lopes, July 25, 2007.)
Introduction 9

Climate

Precipitation in Nevada is highly variable temporally 

and spatially. Winter cold fronts and summer monsoons are 

the two seasonal weather patterns that bring precipitation to 

Nevada (Houghton and others, 1975). Cold fronts typically 

are long-duration, low-intensity, broad storms that account 

for about 75 percent of the annual precipitation in the Walker 

River basin. Monsoons typically are short-duration, highintensity, localized thunderstorms that account for about 

25 percent of the annual precipitation in the Walker River 

basin. Months with no precipitation are common between cold 

fronts and monsoons.

Lopes and Medina (2007) estimated the distribution of 

precipitation in the Walker River basin and surrounding areas 

of west-central Nevada. Mean annual precipitation for the 

period 1971–2000 ranges from about 4 in. at Walker Lake 

to 56 in. along the crest of the Sierra Nevada. Mean annual 

precipitation at Mount Grant, the highest mountain adjacent 

to Walker Lake, is about 16 in/yr. However, mean annual 

precipitation is an average of dry and wet periods and seldom 

occurs during any particular year.

The State of Nevada divided major hydrographic 

basins into 232 hydrographic areas (HAs) for planning and 

management purposes (Cardinalli, 1968; Rush, 1968). The 

Walker River basin is comprised of HA 106 (Antelope Valley), 

HA 107 (Smith Valley), HA 108 (Mason Valley), HA 109 

(East Walker Area) and HA 110 (Walker Lake Valley). HA 

110 was divided into the Schurz Subarea (HA 110A), Lake 

Subarea (HA 110B), and Whisky Flat–Hawthorne Subarea 

(HA 110C). Lopes and Medina (2007) used topographic 

divides to extend the boundaries of HA 106 and HA 109 to 

the crest of the Sierra Nevada in California and calculated the 

total volume of precipitation for the five HAs (table 1). HA 

106 and HA 109 receive the largest amount of precipitation 

in the Walker River basin, especially for precipitation greater 

than 24 in/yr. Precipitation volumes were 18 percent less than 

the Parameter-elevation Regressions on Independent Slopes 

Model (PRISM; Daly and others, 1994), which is another 

source of precipitation estimates for the Walker River basin.

Mean minimum and maximum temperatures in the 

Walker River basin range from 25 to 95°

F, respectively, in 

Hawthorne, Nev., and from 6 to 77°F, respectively, in Bodie, 

Calif. The minimum recorded temperature is about -30°F and 

the maximum is 110°F. July is the hottest month and December 

typically is the coldest month. Average wind speed is from 

about 3 to 5 mi/h on the valley floor of the lower Walker River 

basin and 9 mi/h on Walker Lake. Walker Lake is known for 

strong winds that can capsize boats and close Highway 95. 

The predominant wind direction is from the southwest. 

Native, Invasive, and Agricultural Vegetation

Native vegetation in the lower Walker River basin 

includes scrub brush, riparian, and pinyon-juniper woodland 

communities. The scrub brush community is prevalent on the 

valley floor except along the river and relies mostly on direct 

precipitation. Plants transpire shallow groundwater in some 

areas.

The riparian community grows along the lower Walker 

River where there is abundant water, just south of Walker 

Lake in an area of groundwater discharge, and along perennial 

streams in the Wassuk Range. The riparian community can 

be dense and lush with cottonwood trees, willow and other 

shrubs, and a variety of grasses. The riparian community 

abruptly changes to invasive saltcedar 2–3 mi south of Schurz 

where alkaline lake clays became exposed as Walker Lake 

receded.

The pinyon-juniper woodland community grows in the 

Wassuk Range at altitudes between 5,500 ft and 9,000 ft where 

precipitation ranges from about 7 to 13 in/yr. Sagebrush also 

grows in open areas and between the pinyon pine and juniper 

trees. The pinyon-juniper woodland community relies on 

direct precipitation for its water needs.

Mason Valley has long been the largest agricultural area 

in the Walker River basin. Most of Mason Valley was mapped 

as agricultural by Russell (1885), who described “irrigable 

lands where abundant harvests are annually secured.” In 

2000, a total of 88,600 acres of irrigated land was mapped in 

the Walker River basin (fig. 11). Total irrigated land included 

39,100 acres (44 percent) in Mason Valley; 18,900 acres 

(21 percent) in Smith Valley; 15,900 acres (18 percent) 

upstream from Bridgeport Reservoir; 7,700 acres (9 percent) 

in Antelope Valley; 3,500 acres (4 percent) along the East Fork 

of the Walker River below Bridgeport Reservoir; 3,000 acres 

Table 1. Mean annual precipitation volumes for hydrographic 

areas in the Walker River basin, California and Nevada, 1971–2000.

[Values are in acre-feet per year. Volumes estimated using the precipitationzone method (Lopes and Medina, 2007). Abbreviations: LCL, lower 

95th-percentile confidence limit of mean; UCL, upper 95th–percentile 

confidence limit of mean]

Hydrographic area LCL Mean UCL

106 (Antelope Valley) 552,000 591,000 630,000

107 (Smith Valley) 295,000 319,000 342,000

108 (Mason Valley) 152,000 164,000 176,000

109 (East Walker Area) 737,000 786,000 835,000

110 (Walker Lake Valley) 452,000 487,000 520,000
10 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Figure 11. Distribution of 88,600 acres of irrigated land in the Walker River basin, California and Nevada, during the 

2000 growing season.

tac09-4153_fig11

West Walker River

East Walker River

Walker

River

Walker

Lake

Topaz

Lake

Bridgeport

Reservoir

Artesia

Lake

Weber

Reservoir

Mono

Lake

Schurz

Walker

Wabuska

Yerington

Hawthorne

Coleville

Walker

Lake

Bridgeport

CARSON

CITY

Dayton

SMITH

VALLEY

ANTELOPE

VALLEY

WHISKEY

FLAT

MASON

VALLEY

ADRIAN

GAP

NEVADA

CALIFORNIA

ANCHORITE

PASS

AGAI PAH

HILLS

CALICO HILLS

MOUNTAINS

EXCELSIOR

PINE GROVE HILLS

PINE NUT RANGE

SINGATSE RANGE

DESERT MOUNTAINS

TERRILL MOUNTAINS

GILLIS RANGE

WASSUK RANGE

SIERRA

NEVADA

95

50

95

95

239

208

338

182

108

359

167

395

88

89

89

4

395

Mount

Grant

Parker

Butte

Double

Spring

110C

110B

110A

109

108

107

106

119°45' 119°30' 119°15' 119° 118°45' 118°30' 118°15'

39°

15'

39°

00'

38°

45'

38°

30'

38°

15'

38°

00'

37°

45'

Base from U.S. Geological Survey digital data, 1:24,000 and 1:100,000, 1978-88. Walker Lake 

average lake altitude of 3937.5 ft for November 2006; Projection: Universal Transverse 

Mercator, Zone 11, North American Datum of 1983. Shaded-relief base from 90-meter 

Shuttle Radar Topography Mission digital data, 2000.

CALIFORNIA

NEVADA

Area

of map

EXPLANATION

Hawthorne Army Ammunition Depot

Mason Valley Wildlife Management Area

Walker River Indian Reservation

Walker River basin boundary

Land irrigated during 2000

110A Walker River hydrographic-area boundary—

labeled with hydrographic area number

Lower Walker River study area

Walker Lake shoreline of 1882 (Rush, 1970)

0 10 20 MILES

0 10 20 KILOMETERS
Introduction 11

(3 percent) on the Reservation; and 500 acres (less then 

1 percent) in Whisky Flat south of Hawthorne, Nev. The 

primary crop in the basin is alfalfa, except upstream from 

Bridgeport Reservoir where fields are irrigated for pasture 

grass (fig. 5).

Population

The population of the Walker River basin from the 2000 

census was 18,682 (GeoLytics, Inc., 2001). Yerington, Nev., 

the Lyon County seat, is the largest town in the basin with a 

population of 3,257 (Hardcastle, 2006). Mason Valley, which 

includes Yerington, has a total population of 9,886 and Smith 

Valley has a total population of 1,788. Hawthorne, Nev., the 

Mineral County seat, has a population of 2,931. Schurz, Nev., 

is the only town on the Reservation and has a population of 

721. Most of the population depends on agriculture to support 

their livelihood. Other major employers are the Hawthorne 

Army Ammunition Depot (Army Depot); State, and local 

Governments; and mining. The towns of Topaz Lake, Nev. 

(population 2,128), Bridgeport, Calif. (population 817), and 

Walker Lake, Nev. (population 391), depend on outdoor 

recreation and tourism.

Previous Investigations

Water budgets for the lower Walker River basin and 

Walker Lake have been computed by Harding (1965), Everett 

and Rush (1967), Rush (1970), Schaefer (1980), Milne 

(1987), and Thomas (1995). In addition, the State of Nevada 

summarized streamflow, lake, and reservoir gaging records 

(Pahl, 1997), summarized surface-water irrigation diversions 

(Pahl, 2000a), and computed a surface-water budget for the 

Walker River basin (Pahl, 2000b). For this report, waterbudget estimates were summarized in chronological order of 

publication.

Harding (1965) estimated the evaporation rate for 

selected closed-basin lakes as a residual of a water budget. 

Harding (1965) assumed that evaporation is the only outflow 

from closed-basin lakes and subsurface inflow is negligible. 

Thus, the annual volume that evaporates from the lake surface 

(Ve) is:

 ,

where

is the annual volume of streamflow into the lake;

is the annual volume of precipitation on the lake; 

and

is the annual change in lake storage (p

e sw ppt s

sw

ppt

s

V V V

V

V

= + + ∆

∆ ositive for 

a declining lake).

(1)

The annual evaporation rate is estimated by dividing Ve

by the lake surface area. Harding (1965) estimated an average 

evaporation rate of 4.10 ft/yr from Walker Lake. This estimate 

compared well to estimates for Pyramid Lake (4.02 ft/yr) 

and Winnemucca Lake (3.98 ft/yr), which have a climate 

and altitude similar to Walker Lake. Harding’s estimate is 

biased low because there is subsurface inflow to Walker Lake 

(Everett and Rush, 1967; Schaefer, 1980; Lopes and Allander, 

2009).

Everett and Rush (1967) computed a water budget for 

the lower Walker River basin, including Whisky Flat south of 

Hawthorne, Nev. Average annual flows were calculated for 

the period 1908–65. Average flow at the Wabuska gage was 

estimated to be 140,000 acre-ft/yr. The method described by 

Moore (1968) was used to estimate 10,000 acre-ft/yr of runoff 

and an average runoff coefficient of 1.3 in/yr for the Whisky 

Flat–Hawthorne area. Runoff from the Wassuk Range from 

Cat Creek and north was estimated to be 5,000 acre-ft/yr with 

an average runoff coefficient of 1.9 in/yr. Measured runoff 

from Cottonwood, Rose, and Squaw Creeks indicates these 

estimates are too high (Boyle Engineering Corp., 1976).

About 2,000 acre-ft/yr of runoff from Cat Creek and 

north is diverted to the Army Depot (Everett and Rush, 1967). 

Everett and Rush (1967) estimated 3,000 acre-ft/yr of runoff 

reaches Walker Lake, which includes 1,000 acre-ft/yr from 

the Whisky Flat–Hawthorne area and 2,000 acre-ft/yr from 

Cat Creek and north. The remaining 1,000 acre-ft/yr of runoff 

from Cat Creek and north is stored in reservoirs or evaporates.

Everett and Rush (1967) used the Maxey-Eakin method 

(Maxey and Eakin, 1949) to estimate 2,000 acre-ft/yr of 

recharge in the Whisky Flat area, 3,400 acre-ft/yr around the 

town of Hawthorne, 500 acre-ft/yr along the Wassuk Range 

north of Walker Lake, and 600 acre-ft/yr along the Gillis 
12 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Range east of Walker Lake. Recharge west of Walker Lake 

was assumed to be negligible because the steep consolidated 

rocks extend to the lake. Thus, runoff that might become 

recharge flows directly into the lake. However, some recharge 

occurs because the town of Walker Lake obtains all their water 

from domestic and municipal wells.

Everett and Rush (1967) note that between 1908 and 

1965 the water table declined an average of 40 ft over a 

40 mi2 area south of Walker Lake. Based on this decline and a 

specific yield of 15 percent, they estimated subsurface inflow 

to the lake is 2,000 acre-ft/yr. No information existed for areas 

north and east of Walker Lake, but Everett and Rush (1967) 

estimated a combined 1,000 acre-ft/yr from these areas for a 

total of 3,000 acre-ft/yr of subsurface inflow.

Everett and Rush (1967) used Harding’s (1965) rate 

of 4.10 ft/yr to estimate 220,000 acre-ft/yr of evaporation. 

Average storage loss was estimated to be 100,000 acre-ft/yr.

Prior to 1935, about 9,450 acre-ft/yr of streamflow was 

diverted to irrigate 2,100 acres on the Reservation (Everett 

and Rush, 1967). After Weber Dam was completed in 1934, 

diversions increased to 31,900 acre-ft/yr and irrigated land 

increased to 6,280 acres. Irrigated acreage has since decreased 

to 3,000 acres that was mapped in 2000 (Lopes and Allander, 

2009).

Everett and Rush (1967) used published ET rates to 

estimate 16,000–17,000 acre-ft/yr of ET in the Schurz area, 

800 acre-ft/yr around Walker Lake, and 4,600 acre-ft/yr in 

the Whisky Flat area. The rounded total is 22,000 acre-ft/yr, 

but the total is 21,000 acre-ft/yr in table 5 of Everett and 

Rush (1967). Pumpage by municipal wells in Hawthorne and 

the Army Depot was estimated to be 440 acre-ft/yr. About 

300 acre-ft/yr was pumped in 1965 to irrigate 100 acres in the 

Whisky Flat area. Pumpage for all uses in the Schurz area was 

estimated to be 200 acre-ft/yr. 

Total inflow to the lower Walker River basin 

was estimated to be 169,000 acre-ft/yr, total outflow 

was 256,000 acre-ft/yr, and total storage loss was 

103,000 acre-ft/yr (Everett and Rush, 1967). However, errors 

were found in the water budget. Total inflow was based on 

3,000 acre-ft/yr of runoff into Walker Lake but local runoff 

was estimated to be 15,000 acre-ft/yr. Total outflow was 

based on 21,000 instead of 22,000 acre-ft/yr of ET. Harding’s 

(1965) evaporation rate assumes no groundwater inflow but 

the water budget includes this component, so groundwater was 

accounted for twice.

In addition to making a bathymetric map, Rush (1970) 

computed a water budget for Walker Lake based on a 50-year 

period (1919–68). Rush (1970) estimated 85,000 acre-ft/yr 

of discharge from the Walker River and a total of 

108,000 acre-ft/yr of inflow from all sources.

Harding’s (1965) evaporation rate of 4.10 ft/yr was 

used to estimate 200,000 acre-ft/yr of evaporation. Storage 

loss was estimated to be 110,000 acre-ft/yr. The difference 

between evaporation and storage loss (90,000 acre-ft/yr) is 

inflow estimated as a residual, which is 18,000 acre-ft/yr 

less than inflow estimated directly. Rush (1970) attributed 

the imbalance to errors in the estimates and “unresolved 

hydrologic problems.” One error was including subsurface 

inflow and using Harding’s evaporation rate, which assumed 

no subsurface inflow.

Schaefer (1980) conducted a water-resource assessment 

of the Reservation and estimated 116,000 acre-ft/yr of inflow 

and outflow. Inflow from the Walker River at the Wabuska 

gage was estimated to be 113,800 acre-ft/yr. The remaining 

inflow is subsurface inflow and precipitation.

Schaefer (1980) estimated 69,600 acre-ft/yr of outflow 

from the Walker River to Walker Lake. The total stream 

loss of 44,000 acre-ft/yr is about 40 percent of streamflow 

entering the Reservation. Subsurface outflow was estimated 

to be 11,000 acre-ft/yr to the northern end of Walker Lake and 

4,500 acre-ft/yr through Double Spring and out of the Walker 

River basin. ET from native vegetation was estimated to be 

19,100 acre-ft/yr and 12,000 acre-ft/yr from irrigated lands. 

Evaporation from the Walker River and Weber Reservoir was 

estimated to be 3,800 acre-ft/yr. Pumpage by domestic and 

stock wells was estimated to be 250 acre-ft/yr.

Milne (1987) estimated what the levels of Walker Lake 

and other lakes in the Great Basin would have been if there 

were no human influences on streamflow. As part of the study, 

Milne (1987) used the water-budget method and assumed 

negligible groundwater inflow to estimate an evaporation rate 

of 4.4 ft/yr for Walker Lake. Milne’s model indicated that 

if the Walker River had not been diverted, then the level of 

Walker Lake in 1987 would have been near the 1882 level. 

Thomas (1995) updated the water budget for Walker 

Lake based on a 55-yr period (1939–93). Harding’s (1965) 

rate of 4.10 ft/yr was used to estimate 166,000 acre-ft/yr of 

evaporation. Thomas (1995) used previous estimates of local 

runoff and subsurface inflow and estimated 17,000 acre-ft/yr 

of direct precipitation. Storage loss was estimated to be 

59,000 acre-ft/yr. Inflow from the Walker River, estimated as 

a residual of the water budget, was 76,000 acre-ft/yr. An error 

in the water budget was using Harding’s evaporation rate and 

including subsurface inflow, so groundwater was accounted 

for twice.

To reduce dissolved solids to 10,000 mg/L, Thomas 

(1995) estimated 700,000 acre-ft would be needed to raise the 

lake from 3,944 to 3,964 ft, then 47,000 acre-ft/yr of inflow 

in addition to average annual inflows would be needed to 

maintain the lake level. These estimates did not include water 

needed to replenish aquifer storage. Currently (2008), the lake 

level is 3,931 ft and about 1,100,000 acre-ft would be needed 

to raise the level to 3,964 ft.
Methods 13

Methods

Water budgets were based on the water year (begins 

October 1 through September 30 of the stated year). The 

period 1971–2000 was chosen for mean annual estimates 

because 30 years generally is considered long enough to 

represent the long-term average and this period has the most 

precipitation and streamflow data. In particular, high-altitude 

precipitation has been monitored at SNOwpack TELemetry 

(SNOTEL) stations since about 1980 by the Natural Resources 

Conservation Service. Also, current water use and lake-storage 

changes are best represented using the most recent 30-year 

period. 

Statistical techniques that were used included summary 

statistics, correlation, and regression analysis (Helsel and 

Hirsch, 1992). A 95-percent level of confidence was used in all 

statistical tests.

Precipitation Normals

For this study, a normal is the mean annual value for a 

30-yr period. The method of estimating precipitation normals 

in the Walker River basin and surrounding areas of westcentral Nevada was described in detail by Lopes and Medina 

(2007). Briefly, precipitation data, station locations, and station 

altitudes were obtained for 105 stations in and surrounding 

the Walker River basin. Data were used to calculate the 

precipitation normal at each station for the 1971–2000 water 

years. Only years with complete record were used in all 

calculations. A complete year is when each month in the water 

year has less than 6 days of missing data.

One station (Reno) had 30 complete years of precipitation 

data during 1971–2000 and 19 stations had from 25 to 29 

complete years. These 20 stations were called reference 

stations. It was assumed that the mean of the 25–30 wateryear totals is the precipitation normal for reference stations. 

Linear regression was used to estimate precipitation normals 

for the 85 stations with less than 25 complete years of data. 

Annual precipitation of these stations was correlated with 

annual precipitation of the 20 reference stations using all years 

with complete data through 2005. The reference station that 

had the highest significant Pearson correlation coefficient (r) 

was chosen as the independent variable and the station with 

less than 25 complete years was the dependent variable in 

linear regression. The 1971–2000 precipitation normal of the 

reference station and the regression equation were used to 

estimate the 1971–2000 precipitation normal of the station 

with less than 25 years of data. The 95-percent confidence 

limits are a measure of the uncertainty in the normal. 

Patterns in the spatial distribution of precipitation 

were identified by mapping station locations and plotting 

precipitation normals versus station altitude. Stations in the 

same geographic area were determined to have precipitation 

normals that are related linearly to land-surface altitude. 

Stations with the same linear relation were grouped manually 

to define a precipitation zone. Four precipitation zones 

were defined that cover part of east-central California and 

much of west-central Nevada (fig. 12). Hydrologic-unit 

boundaries, which define major watersheds, were used to 

define precipitation-zone boundaries where possible. Where 

hydrologic-unit boundaries and the boundary between 

precipitation zones did not coincide, the precipitation-zone 

boundary was drawn roughly equidistant between stations in 

different zones. The eastern boundaries of precipitation zones 

were not delineated because zones extend beyond the stations 

that were used in this analysis. 

Regression equations were developed for each zone to 

estimate precipitation normals from altitude at any point in 

the zone (table 2). The regression equations have adjusted 

coefficients of determination (R2) of 0.89 to 0.95, indicating 

that altitude explains 89–95 percent of the variation in 

precipitation normals within each zone. The remaining 

5–11 percent could be due to uncertainty in estimated 

precipitation normals. 

A geographic information system, 98-ft digital elevation 

model, and the four regression equations were used to 

estimate the distribution of mean annual precipitation in westcentral Nevada. The altitude of each cell was used with the 

corresponding regression equation to estimate precipitation 

of each cell within a precipitation zone to the nearest inch. 

Gradational color shading was used to show the distribution in 

mean annual precipitation (fig. 12).

Table 2. Summary of precipitation zone regression equations.

[Equations are used with land-surface elevation, in feet. Abbreviation: R2, 

coefficient of determination]

Zone Intercept Slope Adjusted 

R2

Mean absolute error

(inches) (percent)

Carson -9.2 0.00382 0.92 1.4 10

Sierra Slope -31.0 .01010 .89 3.9 17

Truckee -21.0 .00670 .95 2.0 12

Walker -2.3 .00167 .90 .8 12
14 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

tac09-4153_fig12

SIERRA

SLOPE

ZONE

TRUCKEE

ZONE

CARSON

ZONE

WALKER

Smith ZONE

Topaz

Lake

Lobdel Lake

Monitor

Pass

Bridgeport

Dam

Virginia

Lakes

Ridge

Wellington

Ranger

Stn

Bodie

Schurz

Thorne

Hawthorne

Smith 6 N Yerington

Bridgeport

Wabuska

5 SE

Topaz 

Lake 

4 N

Hawthorne 

Airport

Sonora

Pass

Leavitt 

Meadows

109

108

106

107 110A

110C

110B

120° 119° 118°

40°

39°

38° CALIFORNIA

NEVADA

Base from U.S. Geological Survey digital data, 1:100,000 and 1:24,000, 1979-2006. Projection: 

Universal Transverse Mercator, Zone 11, North American Datum of 1983. Shaded-relief 

base from 30-meter National Elevation Dataset digital data.

CALIFORNIA

NEVADA

Area

of map

EXPLANATION

79

Precipitation 

station by zone

Zone precipitation—

in inches per year

3

110A

Walker River hydrographic-area boundary—

labeled with hydrographic area number

0 20 40 MILES

0 20 40 KILOMETERS

Carson

Walker

Truckee

Sierra Slope

Data from Lopes and Medina (2007)

Figure 12. Distribution of precipitation in the Walker River basin, California and Nevada.
Methods 15

Streamflow Normals at Gaging Stations

The same approach that was used to estimate 

precipitation normals was used to estimate 1971–2000 

streamflow normals at stream gages in the Walker Basin 

(fig. 13) and at stream gages in other basins that were used 

to estimate ungaged runoff. Five gages in the Walker River 

basin, two gages in the Carson River basin, and two gages in 

the Toiyabe Range have 30 complete years (1971–2000) of 

streamflow data. Streamflow normals for these reference gages 

were the arithmetic mean of the 30 annual-streamflow values 

(table 3). Reference gages that are upstream from diversions 

have streamflow normals with uncertainties that range from 18 

to 25 percent with a mean of 20 percent. The Wabuska gage 

has an uncertainty of 37 percent due to upstream diversions 

and reservoir storage.

For gages with less than 30 years of record, annual 

streamflow was correlated with annual streamflow of reference 

gages in the same drainage basin or the closest reference 

gages. Streamflow data collected by the Army Depot were 

used for Rose, Cottonwood, and Squaw Creeks (table 4). 

The reference gage that had the highest significant Pearson 

correlation coefficient was chosen as the independent variable 

and the gage with incomplete record was the dependent 

variable in linear regression. The 1971–2000 streamflow 

normal of the reference gage and the regression equation were 

used to estimate the streamflow normal of the gage with less 

than 30 years of record (table 5). For example, the streamflow

normal ( χ ) at Virginia Creek near Bridgeport, Calif. 

(10289000) is 13,000 acre-ft/yr: 

 4, 400 0.063*138,000 ,

where

4, 400 is the intercept of the regression equation;

0.063is the slope; and

138,000 is the 1971-2000 streamflow normal, in

acre-ft/yr, of the reference station 

(10301

χ = +

500; tables 3, 5).

(2)

Regression equations for streamflow gages in the Walker 

River basin had adjusted R2 values of 0.90 to 1.0. Diversion 

gages Canal No. 1 below Little Dam (Canal No. 1 gage, 

10301755) and Canal No. 2 above Little Dam (Canal No. 2 

gage, 10301742) had adjusted R2 values of 0.79 and 0.78, 

respectively. Names of the Canal No. 1 gage and the Walker 

River above Little Dam near Schurz (Little Dam gage, 

10301745), are misleading because they indicate the wrong 

location relative to Little Dam. Both diversions are upstream 

from Little Dam, and the Little Dam gage actually measures 

discharge downstream from Little Dam.

Table 3. Streamflow normals at selected gaging stations with 30 complete years of data, Walker and Carson River basins and Toiyabe 

Range, California and Nevada, 1971–2000.

[Abbreviations: Calif., California; LCL, lower 95th-percentile confidence limit; MSL, mean sea level; Nev., Nevada; UCL, upper 95th-percentile confidence 

limit; mi2, square mile; acre-ft/yr, acre-foot per year]

Station 

name

Station 

No.

Drainage 

area 

(mi2

)

Gage elevation

(feet above MSL)

LCL

(acre-ft/yr)

Normal

(acre-ft/yr)

UCL

(acre-ft/yr)

Walker River basin

East Walker River near Bridgeport, Calif. 10293000 359 6,400 93,000 119,000 144,000

West Walker River below Little Walker River near 

Coleville, Calif.

10296000 181 6,591 164,000 200,000 236,000

West Walker River near Coleville, Calif. 10296500 250 5,520 174,000 211,000 248,000

West Walker River at Hoye Bridge near Wellington, 

Nev.

10297500 497 4,980 156,000 193,000 231,000

Walker River near Wabuska, Nev. 10301500 2,600 4,300 87,000 138,000 188,000

Carson River basin

East Carson River near Gardnerville, Nev. 10309000 356 5,000 219,000 272,000 326,000

Carson River near Carson City, Nev. 10311000 886 4,620 235,000 311,000 387,000

Toiyabe Range

Kingston Creek below Cougar Canyon near Austin, 

Nev.1

10249280 23.4 6,480 5,500 7,000 8,600

South Twin River near Round Mountain, Nev.1 10249300 20 6,400 3,900 5,200 6,400

1

 Station used to estimate streamflow from ungaged basins.
16 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

tac09-4153_fig13

West Walker River

East Walker River

Walker

River

Walker

Lake

Bridgeport

Reservoir

Mono

Lake

Artesia

Lake

Weber

Reservoir

Walker

Wabuska

Yerington

Hawthorne

Coleville

Bridgeport

Dayton

NEVADA

CALIFORNIA

Mount

Grant

Double

Spring

Schurz

Topaz

Lake

110C

110B

110A

109

108

107

106

Base from U.S. Geological Survey digital data, 1:24,000 and 1:100,000, 1978-88. Walker Lake 

average lake altitude of 3937.5 ft for November 2006; Projection: Universal Transverse 

Mercator, Zone 11, North American Datum of 1983. Shaded-relief base from 90-meter 

Shuttle Radar Topography Mission digital data, 2000.

119°40' 119°30' 119°20' 119°10' 119° 118°50' 118°40' 118°30'

39°

10'

39°

00'

38°

50'

38°

40'

38°

30'

38°

20'

38°

10'

38°

00'

Faults from U.S. Geological Survey and Nevada Bureau of Mines 

and Geology, 2006. Hydrogeology from Maurer and others, 2004 

and modified from California Division of Mines and Geology, 2000.

CALIFORNIA

NEVADA

Area

of map

EXPLANATION

Hawthorne Army Ammunition Depot

Mason Valley Wildlife Management Area

Walker River Indian Reservation

Lower Walker River study area

Walker River basin boundary

Walker River hydrographic-area boundary—

labeled with hydrographic area number

Walker Lake shoreline of 1882 (Rush, 1970)

Site

Surface-water site

110A

0 10 20 MILES

0 10 20 KILOMETERS

Cat Creek

Wabuska

Cottonwood Creek Rose Creek

Wildhorse Canyon

Reese

River

Canyon

Powerline

Lateral 2-A

Schurz

Cow Camp

Hudson

Hoye Bridge

Strosnider

Wabuska

Mason

Butte

Canal No. 1

Little

Dam

Canal No. 2

Coleville

Virginia

Creek

Below

Bridgeport

Below

Sweetwater

Desert Creek

Squaw Creek

Cottonwood

Creek

Cat Creek

Corey Creek

Little Squaw

Powell Canyon

Rough Creek

Figure 13. Locations of stream gages in the Walker River basin, California and Nevada.
Methods 17

Table 4. Streamflow data from drainages in the Wassuk Range, Nevada.

[Data were collected by the Hawthorne Army Ammunition Depot and reported by Boyle Engineering, Corp. (1976). Values in acre-feet. Abbreviations: CY, 

calendar year; WY, water year (October 1 through September 30); –, does not apply]

Year January February March April May June July

Cottonwood Creek

1971 10 22 36 51 89 119 133

1972 29 22 52 138 120 96 33

1973 3 5 16 32 57 80 107

1974 37 62 74 65 100 122 92

1975 5 15 37 41 117 270 113

Rose Creek

1971 65 55 50 50 45 90 121

1972 86 72 79 74 45 64 32

1973 50 34 29 64 135 220 135

1974 62 43 25 40 71 61 24

1975 10 13 16 17 47 117 31

Squaw Creek

1971 10 11 14 11 14 19 9

1972 9 9 7 6 8 7 3

1973 7 7 7 5 16 19 17

1974 59 59 58 65 59 58 33

1975 51 58 51 47 51 90 74

Year August September October November December CY total WY total

Cottonwood Creek

1971 84 33 44 14 5 640 –

1972 26 21 36 50 12 635 600

1973 111 113 86 19 10 639 622

1974 42 13 10 3 5 625 722

1975 103 62 37 12 12 824 781

Rose Creek

1971 41 37 41 95 80 770 –

1972 22 25 34 74 77 684 715

1973 46 37 43 54 78 925 935

1974 11 10 14 67 41 469 522

1975 25 33 21 20 18 368 431

Squaw Creek

1971 5 5 7 10 9 124 –

1972 2 3 5 7 7 73 80

1973 16 16 17 18 12 157 129

1974 29 28 37 44 52 581 495

1975 60 60 57 62 61 722 675
18 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Table 5. Estimated streamflow normals at selected gaging stations with less than 30 complete years of data, California and Nevada, 

1971–2000.

[Abbreviations: MSL, mean sea level; SEE, standard error of estimate; LCL, lower 95th-percentile confidence limit; UCL, upper 95th-percentile confidence 

limit; USGS, U.S. Geological Survey; *, station used to estimate streamflow from ungaged basins; acre-ft/yr; acre-foot per year; mi2, square mile; –, does not 

apply]

Station name

USGS 

station

No.

Drainage 

area

(mi2

)

Gage 

elevation

(feet above 

MSL)

Reference

station 

No.

Intercept Slope Adjusted

R 2

SEE LCL Estimated

normal UCL

(acre-ft/yr)

East Fork of the Walker River

Virginia Creek near Bridgeport, Calif.* 10289000 63.6 6,750 10301500 4,400 0.063 0.94 1,400 12,000 13,000 14,000

Green Creek near Bridgeport, Calif. 10289500 19.5 6,880 10296500 2,200 .095 .98 1,100 22,000 22,000 23,000

Summers Creek near Bridgeport, Calif. 10290000 8.26 7,100 10296000 92.7 .022 .94 480 3,900 4,400 5,000

Robinson Creek near Twin Lakes, Calif. 10290500 39.1 7,050 10297500 12,000 .18 .96 2,700 45,000 46,000 47,000

Buckeye Creek near Bridgeport, Calif. 10291500 44.1 6,900 10296500 2,300 .21 .96 3,300 45,000 46,000 47,000

Swauger Creek near Bridgeport, Calif.* 10292000 52.8 6,620 10301500 2,200 .058 .90 1,900 9,000 10,000 11,000

East Walker River below Sweetwater 

Creek, Calif.

10293050 467 5,760 10297500 6,200 .64 .98 8,100 120,000 129,000 137,000

East Walker River above Strosnider 

Ditch near Mason, Nev.

10293500 1,100 4,574 10293000 -17,600 1.2 .99 6,800 120,000 122,000 124,000

West Fork of the Walker River

Little Walker River near Bridgeport, 

Calif.

10295500 63.1 6,790 10296000 -2,500 0.21 0.95 3,600 38,000 39,000 40,000

West Walker River near Wellington, Nev. 10298500 521 4,850 10301500 89,700 .63 1.00 1,900 162,000 176,000 190,000

Desert Creek near Wellington, Nev.* 10299100 50.4 5,840 10301500 1,500 .049 .97 1,300 5,000 8,000 11,000

West Walker River near Hudson, Nev. 10300000 964 4,650 10297500 -19,200 .86 .96 14,400 142,000 147,000 152,000

Walker River

Walker River near Mason, Nev. 10300600 2,400 4,420 10301500 54,500 1.04 0.99 21,700 181,000 198,000 214,000

Canal No. 2 above Little Dam near 

Schurz, Nev.

10301742 – 4,160 10301500 5,700 .040 .78 1,800 9,000 11,000 13,000

Walker River above Little Dam near 

Schurz, Nev.

10301745 2,584 4,160 10301500 -8,600 .87 .98 11,300 96,000 111,000 126,000

Canal No. 1 below Little Dam near 

Schurz, Nev.

10301755 – 4,160 10297500 2,300 .020 .79 740 5,500 6,200 6,800

Walker River at Schurz, Nev. 10302000 2,850 4,120 10301500 -11,700 .91 .99 7,000 107,000 114,000 121,000

Walker River at Lateral 2-A Siphon near 

Schurz, Nev.

10302002 2,855 4,100 10301500 -21,800 .94 1.00 7,000 103,000 108,000 113,000

Wassuk and Gillis Ranges

Rose Creek near Walker Lake, Nev.1

* 10302145 2.8 6,460 10249280 150 0.060 1.00 6.0 530 570 610

Cottonwood Creek2 21.5 10301500 450 .0019 .85 30 640 720 810

Squaw Creek2 2.6 10301500 120 .0022 .78 142 110 420 730

Cat Creek 19.1 – – – – – – 3

270 –

Corey Creek 20.8 – – – – – – 4

100 –

Wildhorse Canyon near Walker Lake* 10302030 63 4,400 – – – – – – 5

50 –

Carson River basin

Bryant Creek near Gardnerville, Nev.* 10308800 31.5 5,450 10309000 -3,300 0.031 0.89 1,200 4,500 5,100 5,600

Pine Nut Creek near Gardnerville, Nev.* 10309050 10.14 6,340 10311000 120 .0024 .63 500 600 900 1,100

Fredericksburg Canyon Creek near 

Fredericksburg, Calif.*

10310300 3.71 5,520 10311000 700 .0081 .62 1,300 2,400 3,200 4,100

Daggett Creek near Genoa, Nev.* 10310400 3.82 5,100 10311000 700 .0019 .52 400 1,200 1,300 1,400

Clear Creek near Carson City, Nev.* 10310500 16.5 5,000 10311000 1,200 .0099 .69 1,100 3,900 4,300 4,700

North Fork Kings Canyon Creek near 

Carson City, Nev.*

10311090 1.83 5,500 10311000 230 .00071 .58 100 400 400 500
Methods 19

Streamflow Normals at Ungaged Drainages

Streamflow is gaged at multiple locations in large, 

perennial drainages but relatively few small- and intermediatesized drainages have been gaged in Nevada. Runoff-altitude 

relations (Everett and Rush, 1967; Glancy, 1971), regression 

equations (Maurer and others, 2004b), and modeling (Jeton 

and Maurer, 2007) have been used to estimate ungaged 

streamflow in the Walker and Carson River basins. For 

this study, a regression equation was developed that relates 

1971–2000 streamflow normals to precipitation normals in 19 

small- and intermediate-sized gaged drainages in and around 

the Walker River basin.

Eighteen gaged basins in the Walker and Carson River 

basins, White and Desatoya Mountains, and the Toiyabe 

Range were used in the regression analysis (fig. 14; tables 3, 

5). All gages are upstream from diversions and near the 

consolidated rock-unconsolidated sediment contact. In 

addition, a streamflow normal of 50 acre-ft/yr was assumed 

for Wildhorse Canyon east of Walker Lake to constrain the 

regression for intermediate-sized, ephemeral drainages receive 

less than 10 in/yr of precipitation.

The 19 drainage basins range in area from about 2 to 

64 mi2 and generally are underlain by intrusive and volcanic 

rocks with low hydraulic conductivities (Maurer and others, 

2004a). Precipitation normals range from 5 to 45 in/yr and 

streamflow normals range from 50 to 13,000 acre-ft/yr. 

Wide ranges in drainage area, precipitation, streamflow, and 

geographic distribution help characterize runoff from smalland intermediate-sized drainages in west-central Nevada. 

Streamflow normals had significant Spearman rank 

correlations with drainage area (0.90) and total precipitation 

volume (0.90) but were not significantly correlated with 

average basin slope, soil permeability, or soil thickness. The 

Pearson correlation between total precipitation volume and 

drainage area was 0.87, so only precipitation was used in the 

regression analysis. 

The volume of precipitation at 1-in. intervals was 

calculated for each drainage basin. Regressing streamflow 

normals with volumes at 1-in. intervals would create a 

cumbersome equation so volumes were summed for ranges 

in precipitation, such as 11–14 in/yr. A similar approach was 

used to estimate groundwater recharge from mean annual 

precipitation in unmonitored basins (Maxey and Eakin, 1949; 

Nichols, 2000). Maxey and Eakin (1949) and Nichols (2000) 

constrained their regression equations to have intercepts equal 

to zero and coefficients that are positive and increase in value 

with increasing precipitation. Constraining the regression 

makes physical sense because the percent of precipitation 

that becomes recharge and runoff presumably increases 

with increasing precipitation rates. However, a constrained 

regression may not perform as well as an unforced regression. 

Unconstrained and constrained regressions for estimating 

ungaged runoff were compared for this study.

Station name

USGS 

station

No.

Drainage 

area

(mi2

)

Gage 

elevation

(feet above 

MSL)

Reference

station 

No.

Intercept Slope Adjusted

R 2

SEE LCL Estimated

normal UCL

(acre-ft/yr)

Carson River basin—Continued

Kings Canyon Creek near Carson City, 

Nev.*

10311100 4.06 5,180 10311000 130 0.0027 0.51 600 800 1,000 1,200

Ash Canyon Creek near Carson City, 

Nev.*

10311200 5.2 5,080 10311000 900 .0054 .76 600 2,300 2,600 2,800

Vicee Canyon Creek near Sagebrush 

Ranch near Carson City, Nev.*

10311260 1.83 5,155 10311000 .0 .00050 .88 40 100 200 200

Toiyabe Range, Desatoya and White Mountains

Reese River near Ione, Nev.* 10325500 53 7,100 10249300 -3,000 2.84 0.93 1,800 10,000 11,000 12,000

Campbell Creek near Eastgate, Nev.* 10249411 2.14 6,950 10249300 -36 .017 .54 30 30 50 60

Chiatovich Creek near Dyer, Nev.* 10249900 37.3 6,350 10293000 1,900 .041 .74 1,200 6,300 6,800 7,400

1

 Regression equation computed using 1972–75 data collected by Hawthorne Army Ammunition Depot (Boyle Engineering, Corp., 1976) and 2005–07 data 

collected by USGS. 

2

 Regression equation computed using 1972–75 data collected by Hawthorne Army Ammunition Depot (Boyle Engineering Corp., 1976).

3

 1970–75 average (Boyle Engineering Corp., 1976).

4

 Estimated average from Boyle Engineering Corp. (1976).

5

 Assumed value. 

Table 5. Estimated streamflow normals at selected gaging stations with less than 30 complete years of data, California and Nevada, 

1971–2000.—Continued

[Abbreviations: MSL, mean sea level; SEE, standard error of estimate; LCL, lower 95th-percentile confidence limit; UCL, upper 95th-percentile confidence 

limit; USGS, U.S. Geological Survey; *, station used to estimate streamflow from ungaged basins; acre-ft/yr; acre-foot per year; mi2, square mile; –, does not 

apply]
20 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

tac09-4153_fig14a

Mono

Lake

Lake

Tahoe

West Walker RiverWest Walker River

East Walker RiverEast Walker River

Walker

Carson

River

River

Walker

Lake

Topaz

Lake

Bridgeport

Reservoir

Artesia

Lake

Weber

Reservoir

CALIFORNIA

NEVADA

Area

of map

CARSON

CITY

CALIFORNIA

NEVADA

0 20 40 MILES

0 20 40 KILOMETERS

EXPLANATION

Gaged runoff used in regression

Regression used to estimate ungaged runoff

Walker River basin boundary

Estimated runoff used in regression

Drainages—labeled with unique number

(fig. 14B)

4

43

19

Desatoya

Mountains

Toiyabe Range

White Mountains

A.

9

13

10

16

12

11

14

15 17

33

34

37

23

22

21 20

35

36

38

39

40

18 41

42

43

4445

46

47 48

6

7

8

2

3

1

5

4

19

24

25

26 27

28

29

30

31

32

Base from U.S. Geological Survey digital data, 1:100,000 and 1:24,000, 1979-2006. 

Projection: Universal Transverse Mercator, Zone 11, North American Datum of 1983. 

Shaded-relief base from 30-meter National Elevation Dataset digital data.

120° 119°30' 119° 118°30' 118° 117°30'

39°

30'

39°

00'

38°

30'

38°

00'

37°

30'

Figure 14. Locations of drainages in California and Nevada that were used to estimate runoff from ungaged 

drainages in the Walker River basin.
Methods 21

B. Gaged, estimated, and ungaged drainages

Drainage 

No. Drainage name Station No. Drainage No. Drainage name Station No.

Gaged drainages

1 Campbell Creek near Eastgate, Nev. 10249411 10 Pine Nut Creek near Gardnerville, Nev. 10309050

2 Kingston Creek below Cougar Canyon near 

Austin, Nev.

10249280 11 Fredericksburg Canyon Creek near 

Fredericksburg, Calif

10310300

3 South Twin River near Round Mountain, 

Nev.

10249300 12 Daggett Creek near Genoa, Nev. 10310400

4 Reese River near Ione, Nev. 10325500 13 Clear Creek near Carson City, Nev. 10310500

5 Chiatovich Creek near Dyer, Nev. 10249900 14 Kings Canyon Creek near Carson City, 

Nev.

10311100

6 Viginia Creek near Bridgeport, Calif. 10289000 15 North Fork Kings Canyon Creek near 

Carson City, Nev.

10311090

7 Swauger Creek near Bridgeport, Calif. 10292000 16 Ash Canyon Creek near Carson City, 

Nev.

10311200

8 Desert Creek near Wellington, Nev. 10299100 17 Vicee Canyon Creek near Sagebrush 

Ranch near Carson City, Nev.

10311260

9 Bryant Creek near Gardnerville, Nev. 10308800 18 Rose Creek –

Estimated drainage

19 Wildhorse Canyon near Walker Lake, Nev. 10302030 –

Ungaged drainages

20 Nevada Creek – 35 Reese River Canyon –

21 California Creek – 36 Deadman Canyon –

22 Slinkard Creek – 37 Unnamed south of Deadman –

23 Mill Creek – 38 Copper Canyon –

24 Unnamed #1 – 39 Dry Creek –

25 Unnamed #2 – 40 Dutch Creek –

26 Sweetwater Creek – 41 House Creek –

27 Quaking Aspen Canyon – 42 Little Squaw Creek –

28 Cottonwood Canyon – 43 North Canyon Creek –

29 Silverado Canyon – 44 Alum Creek –

30 Ferris Canyon – 45 Willow Creek –

31 Green Creek – 46 Cottonwood Creek (south) –

32 Fryingpan Creek – 47 Johnston Creek –

33 By-Day Creek – 48 Powell Canyon –

34 Log Cabin Creek –

Figure 14.—Continued.
22 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

In most of the 19 drainages precipitation ranges from 11 

to 38 in/yr so less than or equal to 10 in/yr and greater than 

38 in/yr were the initial bounding intervals. Precipitation 

volumes were summed at 4-, 6-, and 8-inch intervals between 

the initial bounding intervals and varying bounding intervals, 

such as less than or equal to 12 in/yr and greater than 36 in/yr. 

The adjusted R2, p-value of regression coefficients, standard 

error of estimate (SEE), and homoscedasticity of residuals 

were used to determine which intervals and regressions 

performed best. For comparison, the same procedure was done 

using PRISM 1971–2000 precipitation estimates.

The regression equation that performed best was for an 

unconstrained regression using precipitation estimates from 

Lopes and Medina (2007) and 6-inch intervals between less 

than or equal to 10 in/yr and greater than 28 in/yr:

10 11 16 17 22

23 28 28

11 16

0.0034* 0.3732* 0.0747*

 0.3348* 0.2713* ,

where

is the streamflow normal, in acre-ft/yr, and

is the precipitation volume from 11

to 16 in./yr, in acre-ft/y

PV PV PV

PV PV

PV

≤ − −

− >

−

= + −

+ +

χ

χ

r.

(3)

The adjusted R2 was 0.98, the mean absolute error (MAE) 

was 35 percent, and the SEE was 710 acre‐ft/yr (76 percent), 

indicating equation 3 performs fairly well (fig. 15A). 

Figure 15. (A) predicted compared to observed 1971–2000 streamflow normals and (B) constrained regressions 

compared to observed streamflow normals. Solid lines are the regression of predictions or residuals from the 

unconstrained regression with observed streamflow normals. Dashed lines are the 95th-percentile confidence intervals 

of the regression.

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

-4,000

-2,000

0

2,000

4,000

6,000

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000

OBSERVED STREAMFLOW NORMAL, IN ACRE-FEET PER YEAR

OBSERVED-PREDICTED STREAMFLOW NORMALS,

IN ACRE-FEET PER YEAR

OBSERVED-PREDICTED STREAMFLOW NORMAL,

IN ACRE-FEET PER YEAR

A.

B.

95th-percentile confidence intervals

Unconstrained regression line and predicted normal

Constrained predicted normal
Methods 23

Regression of residuals with observed values indicates no bias 

in the estimates for the entire range in streamflow normals, 

but the lowest values (less than 1,300 acre-ft/yr) tend to be 

overestimated (fig. 15B). 

Constraining the regression resulted in increasing 

errors with increasing streamflow normals and a SEE 

of 2,300 acre-ft/yr (fig. 15). The best unconstrained 

regression using PRISM precipitation estimates had a SEE 

of 2,180 acre-ft/yr. The negative coefficient for PV17-22 in 

equation 3 makes no physical sense. However, the purpose of 

the regression was to calculate an equation that best predicts 

runoff, so equation 3 and the precipitation distribution (fig. 12) 

were used to estimate ungaged runoff in the Walker River 

basin (table 6). Negative estimates were assumed to be equal 

to zero. Equation 3 should be used only with precipitation 

estimates from Lopes and Medina (2007) and not be applied 

to drainages that have carbonate rocks and basalt, which likely 

have different runoff characteristics.

Equation 3 seems to overestimate ungaged runoff 

for certain drainages in the Wassuk Range. Estimates for 

Cottonwood, Cat, and Corey Creeks were from 4 to 22 

times more than estimates based on gaged discharge 

(table 5). Ungaged runoff estimated for Squaw Creek 

(300 acre-ft/yr) compared fairly well to the estimate based 

on gaged data (420 acre-ft/yr). Rose Creek was used in the 

regression, so a comparison of ungaged and gaged runoff 

would not be valid. Cottonwood, Cat, and Corey Creeks have 

large areas with relatively gentle slopes in the drainage area, 

which seem to decrease runoff. Little Squaw Creek and Powell 

Canyon also have large areas with gentle slopes. Ungaged 

runoff for these drainages was assumed to be overestimated by 

four times, which is the low end of the comparison to gaged 

basins, so estimates were reduced 75 percent.

Correction to Evapotranspiration Rates

During the computation of water budgets, it became 

apparent that ET rates reported by Allander and others (2009) 

were too high. The open-water evaporation rate of 5.0 ft/yr for 

Walker Lake estimated a larger volume of outflow than could 

be accounted for by the estimated inflow and storage change. 

The Walker River and precipitation account for 92 percent of 

all inflow and are known with a high level of certainty. Storage 

change also is known to a high level of certainty so the 

imbalance in the water budget had to be due to the evaporation 

rate. Water budgets for the rest of the Walker River basin also 

had too much outflow using land-based ET rates.

A different approach of estimating open-water 

evaporation was possible because inflow from the Walker 

River was negligible during a recent, unprecedented drought. 

The drought began in 1987 when annual streamflow at 

the Wabuska gage was about 50 percent of the 1971–2000 

streamflow normal of 138,000 acre-ft. Annual streamflow at 

the Wabuska gage from 1988–94 was 18,400–31,400 acre-ft, 

which was 13–23 percent of the 1971–2000 streamflow 

normal. When annual streamflow at the Wabuska gage is less 

than 35,000 acre-ft, diversions, ET, and infiltration reduce flow 

to less than 1,000 acre-ft/yr at the Lateral 2‐A gage. This small 

amount of streamflow is lost to stream infiltration and ET 

before reaching Walker Lake.

When inflow from the Walker River is negligible, the 

evaporation rate (E) is simply the annual decline in lake 

altitude (ΔLA) plus the annual precipitation rate (Ippt) and 

subsurface-discharge rate (Isbsfc):

 . E I I = ∆ + + LA ppt sbsfc (4)

Equation 4 is analogous to a pan-evaporation 

measurement but without the need for a correcting coefficient. 

Lake altitude has been measured monthly to the nearest 0.01 ft 

since 1928 so ΔLA is known accurately. Ippt during 2005 and 

2006 were within 0.7 in/yr of precipitation rates at Hawthorne, 

Nev., so Ippt also is known accurately. Independent estimates 

of subsurface discharge range from 8,500 to 23,400 acre-ft/yr 

(Lopes and Allander, 2009), but the lower value is consistent 

with other water-budget estimates (this report). Isbsfc was 

estimated by dividing 8,500 acre-ft/yr, which was assumed to 

be constant, by the annual mean lake surface area.

E ranged from 4.1 to 4.7 ft/yr during 1988–94 (table 7). 

The average of 4.3 ft/yr is 14 percent less than the 5.0 ft/yr 

of evaporation calculated by Allander and others (2009). A 

total of 34,000 acre-ft/yr of subsurface discharge would be 

needed for the two estimates to be equal, which is 40 percent 

more than the maximum estimate. No errors were found 

in computations of ET data. The error could be because 

the Bowen ratio method used to measure lake evaporation 

assumes closure in the energy budget. However, energy 

budgets typically do not close and have residuals of about 10 

to 30 percent (Foken, 2008). 

Harding (1965) and Milne (1987) estimated evaporation 

less subsurface inflow as a residual of a water budget. 

Assuming constant discharge, subsurface inflow would 

add about 0.2 ft/yr to their estimate based on the mean lake 

surface area from 1928 to 1986. Harding’s (1965) evaporation 

rate corrected for subsurface inflow is 4.3 ft/yr and Milne’s 

(1987) is 4.6 ft/yr. These rates are consistent with the 4.3 ft/yr 

estimated from equation 4, so an evaporation rate of 4.3 ft/yr 

was used for Walker Lake in this report. Land-based ET rates 

also were reduced by 14 percent.
24 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Table 6. Estimated streamflow normals from ungaged drainages in the Walker River basin, California and Nevada, 

1971–2000.

[Drainage numbers are shown in figure 14. Equation 3 was used to make estimates unless noted otherwise. Abbreviations: LCL, lower 

95th-percentile confidence limit; Normal, 1971–2000 average annual runoff; UCL, upper 95th-percentile confidence limit; acre-ft/yr, acre-foot 

per year; mi2, square mile; –, not estimated]

Drainage 

No. Drainage Drainage area (mi2

)

LCL

(acre-ft/yr)

Normal 

(acre-ft/yr)

UCL 

(acre-ft/yr)

Antelope Valley

20 Nevada Creek 1.1 0 10 100

21 California Creek 1.4 0 20 120

22 Slinkard Creek 30.1 2,600 3,900 5,100

23 Mill Creek 22.8 5,400 6,000 6,600

 Subtotal (rounded) 8,000 10,000 12,000

Sweetwater Range

24 Unnamed #1 1.3 90 140 180

25 Unnamed #2 .8 0 20 70

26 Sweetwater Creek 8.0 2,400 3,000 3,600

27 Quaking Aspen Creek .8 100 120 150

28 Cottonwood Creek .6 110 130 150

29 Silverado Creek 1.7 470 540 620

30 Ferris Creek 4.5 1,300 1,800 2,200

31 Green Creek 1.6 320 360 400

32 Fryingpan Creek 11.5 2,300 2,600 3,000

Subtotal (rounded) 7,000 9,000 10,000

Bridgeport Valley

33 By-Day Creek 4.2 600 700 800

34 Log Cabin Creek 1.6 0 0 100

Subtotal (rounded) 600 700 900

East Wassuk Range north of Walker Lake

35 Reese River Canyon 12.8 0 180 490

36 Deadman Canyon 3.1 170 220 280

 Subtotal (rounded) 200 400 800

East Wassuk Range adjacent to Walker Lake

37 Unnamed creek south of Deadman 6.0 310 430 540

38 Copper Canyon 4.7 0 60 180

39 Dry Creek 11.7 0 100 400

40 Dutch Creek 4.6 590 670 750

 Subtotal (rounded) 900 1,300 1,900

East Wassuk Range south of Walker Lake

41 House Creek 2.4 260 300 340

42 Little Squaw Creek 12.2 1,200 1350 1,600

43 North Canyon Creek 6.6 380 510 640

44 Alum Creek 6.2 260 390 520

45 Willow Creek 3.4 10 100 180

46 Cottonwood Creek (south) 7.0 520 650 780

47 Johnston Creek 3.6 390 450 510

48 Powell Canyon 16.4 2,400 1650 2,900

Subtotal (rounded) – 3,400 –

1

 Original estimate reduced by 75 percent.
Upper Walker River Basin Surface-Water Budgets 25

Upper Walker River Basin 

Surface-Water Budgets

The Walker River basin upstream from the Wabuska 

gage has alluvial valleys separated by mountains comprised 

of consolidated rock with low hydraulic conductivity. The 

alluvial aquifer in each valley thins or pinches out at the 

downstream end, forcing most groundwater to discharge 

into the river. Streamflow is gaged where the river enters 

and exits the valleys. Subsurface flow between valleys is a 

small percentage of the streamflow. Estimating groundwater 

recharge, pumpage, and storage change in each valley is 

beyond the scope of this study, but the gaged streamflow 

makes estimating the surface-water budget within each valley 

an easy task. 

Total surface-water inflow to the upper Walker River 

basin was estimated to be 387,000 acre-ft/yr (rounded to the 

nearest 1,000 acre-ft/yr) This is 60,000 acre-ft/yr (18 percent) 

more than estimated by Thomas (1995; table 8). The larger 

estimate partly is because Thomas (1995) did not estimate 

ungaged runoff or precipitation on Topaz Lake and Bridgeport 

Reservoir. About 223,000 acre-ft/yr (58 percent) is from the 

West Fork of the Walker River; 145,000 acre-ft/yr (37 percent) 

is from the East Fork of the Walker River; 17,000 acre-ft/yr 

(4 percent) is from the Sweetwater Range; and 2,000 acre-ft/yr 

(less than 1 percent) is from the Bodie Mountains, Pine Grove 

Hills, and western Wassuk Range. Outflow from the upper 

Walker River basin is 138,000 acre-ft/yr at the Wabuska gage. 

About 249,000 acre-ft/yr (64 percent) of inflow is diverted for 

irrigation, transpired by riparian vegetation, evaporates from 

reservoirs, and recharges alluvial aquifers.

Antelope Valley

Streamflow entering Antelope Valley prior to diversions 

is gaged at West Walker River near Coleville, Calif. (Coleville 

gage, 10296500), which has a 1971–2000 streamflow 

normal of 211,000 acre-ft/yr (fig. 13 and table 8). Ungaged 

runoff is about 10,000 acre-ft/yr and total stream inflow is 

221,000 acre-ft/yr (tables 8 and 9).

Topaz Lake is at an altitude of 5,000 ft in the Carson 

precipitation zone (table 2) and receives about 0.8 ft/yr of 

precipitation. Reservoir storage has been measured daily at 

Topaz Lake since 1922. The 1971–2000 mean daily releasable 

storage volume is 28,500 acre-ft, which corresponds to a 

surface area of 1,900 acres (Rush and Hill, 1972). Direct 

precipitation on Topaz Lake is about 2,000 acre-ft/yr and total 

surface-water inflow to Antelope Valley is 223,000 acre-ft/yr.

Outflow from Antelope Valley, gaged at West Walker 

River at Hoye Bridge near Wellington (Hoye Bridge gage, 

10297500), is 193,000 acre-ft/yr (fig. 13 and table 9). Total 

stream loss in Antelope Valley is about 30,000 acre-ft/yr 

(13 percent). Most stream loss is due to agricultural diversions 

and evaporation from Topaz Lake. 

Topaz Lake is about 1,000 ft higher than Walker Lake 

so evaporation must be less than the 4.3 ft/yr at Walker Lake. 

Myrup and others (1979) used the energy-balance method to 

estimate 3.6 ft/yr of evaporation from Lake Tahoe (6,225 ft). 

This estimate compares well with Vorster (1985) who used 

pan-evaporation data and an evaporation-altitude relation to 

estimate a freshwater-evaporation rate of 3.8 ft/yr at Mono 

Lake (6,370 ft). Assuming a linear relation in the Walker, 

Mono, and Tahoe Basins, evaporation (E) decreases 0.3 ft/yr 

per 1,000-ft increase in altitude from Walker Lake (ΔAltitude):

4.3 *0.3 . E = − ∆Altitude (5)

Table 7. Estimated evaporation from Walker Lake, Nevada, during the 1987–94 drought.

[Groundwater discharge is assumed to be constant at 8,500 acre-feet during each year, and streamflow at Walker River near Wabuska, Nevada (10301500), was 

less than 23 percent of the 1971–2000 average and assumed to be lost before reaching the lake]

Water 

year

Decrease in lake 

elevation 

(feet)

Precipitation 

(feet)

Ground-water 

discharge 

(feet)

Evaporation 

(feet per year)

Walker River near 

Wabuska 

(acre-feet)

1988 3.4 0.4 0.26 4.1 26,900

1989 4.2 .3 .27 4.7 24,000

1990 3.5 .3 .27 4.1 21,400

1991 3.5 1.3 .28 4.1 18,400

1992 4.0 1.4 .28 4.7 20,200

1993 3.8 .3 .29 4.3 22,800

1994 3.7 .4 .30 4.4 31,400

Mean 3.7 .3 .3 4.3 24,000

1

 Precipitation data from Mina, Nevada, used due to incomplete data at Hawthorne, Nevada.
26 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

This rate compares well to Harding (1965), who estimated 

evaporation decreases about 0.4 ft/yr per 1,000-ft increase in 

altitude. Using equation 5, an altitude difference of 1,000 ft, 

and an average surface area of 1,900 acres, the evaporation 

rate is 4.0 ft/yr and about 8,000 acre-ft/yr of stream loss is 

evaporation from Topaz Lake.

The remaining 22,000 acre-ft/yr of stream loss is due 

mostly to diversions. During 2000, a total of 7,700 acres 

were irrigated in Antelope Valley. Mapping of circular fields 

indicated 500 acres were irrigated by wells and center pivots. 

Groundwater is pumped to flood irrigate fields in Smith and 

Mason Valleys (Lopes and Allander, 2009), but the 2006 and 

2007 pumpage inventories for Antelope Valley1 do not indicate 

groundwater is used for flood irrigation. The diversion rate is 

about 3.0 acre-ft/acre (22,000 acre-ft/7,200 acres). Antelope 

Valley receives about 0.8 ft/yr of precipitation so the total 

applied-water rate is about 3.8 ft/yr. Corrected ET rates for 

two alfalfa fields in Mason Valley were 2.8 ft/yr and 3.5 ft/yr 

with an average of 3.2 ft/yr (Allander and others, 2009), 

so about 0.6 ft/yr (15 percent) flushes salts from the soil. 

Uncorrected ET rates average 3.8 ft/yr. Fields need more water 

than the ET rate to flush salts from the soil, so the corrected 

ET rate compares well to the applied-water rate of 3.8 ft/yr 

but the uncorrected ET rate is too high. Some of the difference 

between total applied-water and corrected ET rates could be 

due to riparian ET and infiltration along the river, but these 

losses likely are minimal.

Smith Valley

Streamflow into Smith Valley is 201,000 acre-ft/yr and 

is the sum of 193,000 acre-ft/yr at the Hoye Bridge gage and 

8,000 acre-ft/yr from Desert Creek near Wellington, Nev. 

(Desert Creek gage, 10299100; fig. 13 and tables 8 and 9). 

Most ungaged runoff from the Pine Nut Range drains toward 

Artesia Lake and was assumed to contribute negligible flow. 

Outflow from Smith Valley, measured at West Walker River 

near Hudson (Hudson gage, 10300000), is 147,000 acre-ft/yr 

(fig. 13 and table 9). Total stream loss in Smith Valley is about 

54,000 acre-ft/yr (27 percent). 1

http://images.water.nv.gov/images/Pumpage%20Inventories/default.aspx

Table 8. Summary of surface-water inflows in the upper Walker River basin, California and Nevada.

[Abbreviations: LCL, lower 95th-percentile confidence limit; Normal, 1971–2000 average annual runoff; UCL, upper 

95th-percentile confidence limit; USGS, U.S. Geological Survey; acre-ft/yr, acre-foot per year; –, does not apply]

Drainage USGS 

station No.

LCL 

(acre-ft/yr)

Normal 

(acre-ft/yr)

UCL 

(acre-ft/yr)

West Fork of the Walker River

West Walker River near Coleville, Calif. 10296500 174,000 211,000 248,000

Ungaged runoff – 8,000 10,000 12,000

Precipitation on Topaz Lake – 2,000 2,000 2,000

Subtotal – 184,000 223,000 262,000

East Fork of the Walker River

Virginia Creek near Bridgeport, Calif. 10289000 12,000 13,000 14,000

Green Creek near Bridgeport, Calif. 10289500 22,000 22,000 23,000

Summers Creek near Bridgeport, Calif. 10290000 3,900 4,400 5,000

Robinson Creek near Twin Lakes, Calif. 10290500 45,000 46,000 47,000

Buckeye Creek near Bridgeport, Calif. 10291500 45,000 46,000 47,000

Swauger Creek near Bridgeport, Calif. 10292000 9,000 10,000 11,000

Ungaged runoff – 600 700 800

Precipitation on Bridgeport Reservoir – 3,000 3,000 3,000

Subtotal (rounded) – 141,000 145,000 151,000

Sweetwater Range

Desert Creek near Wellington, Nev. 10299100 5,000 8,000 11,000

Ungaged runoff – 7,000 9,000 10,000

Subtotal – 12,000 17,000 21,000

Bodie Mountains, Pine Grove Hills, and Western Wassuk Range

Ungaged runoff – 0 12,000 4,000

Grand total (rounded) – 336,000 387,000 438,000

1

Assumed value with a range of 100 percent.
Upper Walker River Basin Surface-Water Budgets 27

During 2000, a total of 18,900 acres were irrigated in 

Smith Valley. Mapping of circular fields indicated 933 acres 

were irrigated by wells and center pivots. The diversion rate in 

Smith Valley is about 3.0 ft/yr (54,000 acre-ft/17,967 acres). 

Lopes and Allander (2009) estimated 6,000 acre-ft/yr of 

groundwater is pumped to flood irrigate fields in Smith Valley, 

so about 0.3 ft (6,000 acre-ft/17,967 acres) of groundwater 

also is applied. Smith Valley is at an altitude of about 4,800 ft 

in the Walker precipitation zone (table 2) and receives about 

0.5 ft/yr of precipitation. The total applied-water rate of 

3.8 ft/yr is the same as the rate estimated for Antelope Valley. 

This rate compares well to Rush (1976) who measured a total 

applied-water rate of 3.5 ft in Smith Valley during the 1973 

growing season. Precipitation during the nongrowing season 

was not included in Rush’s estimate. The same applied-water 

rate in Antelope and Smith Valleys and the gaining river 

through Smith Valley (Lopes and Allander, 2009) indicate 

riparian ET and infiltration along the river are minimal.

Bridgeport Valley

Streamflow entering Bridgeport Valley has been gaged at 

6 creeks with a total streamflow normal of 141,400 acre-ft/yr 

(table 8). Ungaged runoff from By-Day Creek was estimated 

to be 700 acre-ft/yr for a total of 142,000 acre-ft/yr (tables 8

and 9). Negligible ungaged runoff was estimated for Log 

Cabin Creek just south of By-Day Creek.

Bridgeport Valley is at an altitude of about 6,400 ft in 

the Carson precipitation zone (table 2) and receives about 

1.3 ft/yr of precipitation. The storage volume of Bridgeport 

Reservoir has been measured daily since April 1971. Because 

the first 3 months of the 1971 water year are missing, the 

1972–2000 mean annual storage volume of 22,800 acre-ft was 

assumed to be the 1971–2000 normal. Altitude/surface-area/

storage volume relations do not exist for Bridgeport Reservoir 

so surface area was estimated from a National Agricultural 

Imagery Program 1-meter resolution digital orthophotograph. 

On September 20, 2006, storage in Bridgeport Reservoir was 

20,220 acre-ft and the surface area was about 2,500 acres. 

Direct precipitation on Bridgeport Reservoir is about 

3,000 acre-ft/yr and total surface-water inflow to Bridgeport 

Valley is 145,000 acre-ft/yr (table 9).

Outflow from Bridgeport Valley, measured at East 

Walker River near Bridgeport, Calif. (below Bridgeport 

gage, 10293000), is 119,000 acre-ft/yr (fig. 13 and table 9). 

Total stream loss in Bridgeport Valley is 26,000 acre-ft/yr 

(18 percent). Most stream loss is due to agricultural diversions 

and evaporation from Bridgeport Reservoir. Using equation 5 

and an altitude difference of 2,400 ft, the evaporation rate at 

Bridgeport Reservoir is 3.6 ft/yr. About 9,000 acre-ft/yr of the 

26,000 acre-ft/yr of stream loss is evaporation from Bridgeport 

Reservoir.

The remaining 17,000 acre-ft/yr of stream loss in 

Bridgeport Valley is due to diversions. During 2000, there 

were 15,900 acres of pasture grass for a diversion rate of 1.1 ft 

(17,000 acre-ft/15,900 acres). Bridgeport Valley receives 

about 1.3 ft/yr of precipitation so the applied-water rate is 

about 2.4 ft/yr. The California Department of Water Resources 

and USGS databases indicate no irrigation wells in the valley 

so this likely is the total applied-water rate. The rate of 

2.4 ft/yr is less than the 2.8–4.4 ft/yr of total ET from floodirrigated pasture in Carson Valley (Maurer and others, 2006). 

Many fields in Bridgeport Valley have standing water, and low 

stream banks indicate a thin unsaturated zone and the water 

table is 2–3 ft below land surface. Some water transpired by 

pasture grass could be shallow groundwater.

Table 9. Summary of surface-water budgets for the upper Walker River basin, California and Nevada, 1971–2000.

[Mean annual flows in acre-feet, 1971–2000. Abbreviations: TSTE, too small to estimate; –, does not apply]

Water-budget component Antelope Valley Smith Valley Bridgeport 

Valley

East Fork 

Walker River Mason Valley

Surface-water inflow

Stream inflow 221,000 201,000 142,000 131,000 269,000

Open-water precipitation 2,000 – 3,000 – –

Total surface-water inflow 223,000 201,000 145,000 131,000 269,000

Surface-water outflow

Open-water evaporation 8,000 – 9,000 – –

Diversions 22,000 54,000 17,000 6,000 117,000

Stream infiltration and riparian evapotranspiration TSTE TSTE TSTE 3,000 14,000

Stream outflow 193,000 147,000 119,000 122,000 138,000
28 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

East Fork of the Walker River

Streamflow into the East Fork of the Walker 

River, measured at the below Bridgeport gage, is 

119,000 acre-ft/yr (fig.13 and table 9). Streamflow is 

129,000 acre-ft/yr at the East Walker River below Sweetwater 

Creek, Nev. (below Sweetwater gage, 10293050). The 

additional 10,000 acre-ft/yr between these gages is nearly 

equal to the 9,000 acre-ft/yr of ungaged runoff from the 

Sweetwater Range (table 6). However, ungaged runoff should 

be more than 10,000 acre-ft/yr because of diversion for 

1,400 acres of agriculture along Sweetwater Creek. Assuming 

a diversion rate of 3.0 ft/yr, an addition 4,000 acre-ft/yr 

of ungaged runoff could flow from the Sweetwater Creek 

drainage, which includes all ungaged drainages in the 

Sweetwater Range except Fryingpan Creek. Estimated 

streamflow in tables 8 and 9 do not include this possible 

4,000 acre-ft/yr of ungaged runoff.

Rough Creek drains a large part of the Bodie Mountains 

but estimated ungaged runoff was unreasonably high, which 

likely is because of the large area with gentle slopes in the 

drainage. The estimate of 27,300 acre-ft/yr is equivalent to a 

daily average discharge of 38 ft3/s. Discharge measurements 

along Rough Creek ranged from 1.86 to 3.5 ft3/s during 

October and November 1952 (Glancy, 1971). Discharge at the 

below Bridgeport gage during 1952 was 60 percent more than 

the 1971–2000 streamflow normal, so these measurements 

could be higher than typical for this time of the year. It 

was assumed that total runoff from the Bodie Mountains, 

Pine Grove Hills, and the west side of the Wassuk Range is 

2,000 acre-ft/yr, which is a daily average discharge of 3 ft3/s. 

Total streamflow along the East Fork of the Walker River is 

131,000 acre-ft/yr.

Outflow, measured at East Walker River above Strosnider 

Ditch near Mason, Nev. (Strosnider gage, 10293500), is 

122,000 acre-ft/yr. Stream loss along the East Fork of the 

Walker River is about 9,000 acre-ft/yr (7 percent). During 

2000, there were 2,100 acres of irrigated land along the East 

Fork of the Walker River below Sweetwater Creek for a 

diversion rate of 4.3 ft/yr (9,000 acre-ft/2,100 acres). The East 

Fork of the Walker River is at an altitude of about 5,000 ft 

in the Walker precipitation zone (table 2) and receives about 

0.5 ft/yr of precipitation, so the total applied-water rate is 

about 4.8 ft/yr, which is 1.0 ft more than rates for Antelope 

and Smith Valleys. 

The total applied-water rate likely is high because all 

loses were attributed to agricultural diversions. However, 

cottonwood trees grow along the river banks and the East 

Fork of the Walker River could be a losing reach. Assuming 

the diversion rate is the same as for Antelope and Smith 

Valleys (3.0 ft/yr), about 6,000 acre-ft/yr is diverted. The 

remaining 3,000 acre-ft/yr is assumed to be lost to riparian ET, 

infiltration, or both.

Mason Valley

Streamflow into Mason Valley is 269,000 acre-ft/yr 

and is the sum of streamflow at the Hudson and Strosnider 

gages (fig. 13 and table 9). Ungaged streamflow from hills 

surrounding Mason Valley was assumed to be negligible. 

Outflow from Mason Valley, measured at the Wabuska gage, 

is 138,000 acre-ft/yr. Total stream loss in Mason Valley is 

131,000 acre-ft/yr (49 percent).

During 2000, there were 39,100 acres of irrigated land in 

Mason Valley. Mapping of circular fields indicated 136 acres 

were irrigated by wells and center pivots. The diversion rate in 

Mason Valley is about 3.4 ft/yr (131,000 acre-ft/38,964 acres). 

Lopes and Allander (2009) estimated 40,000 acre-ft/yr of 

groundwater is pumped to flood irrigate fields in Mason 

Valley, so about 1.0 ft (40,000 acre-ft/38,964 acres) of 

groundwater also is applied. Pumpage has caused groundwater 

levels to decline as much as 60 ft in Mason Valley, indicating 

aquifer storage is being depleted (Lopes and Allander, 2009). 

Mason Valley is at an altitude of about 4,400 ft in the Walker 

precipitation zone and receives about 0.4 ft/yr of precipitation. 

The total applied-water rate of 4.8 ft/yr is 1.0 ft/yr more than 

rates estimated for Antelope and Smith Valleys. 

The total applied-water rate likely is high because all 

loses were attributed to agricultural diversions. However, 

cottonwood trees grow along the river banks and much of 

fhe Walker River is losing through Mason Valley (Lopes 

and Allander, 2009). Assuming the diversion rate is the 

same as for Antelope and Smith Valleys (3.0 ft/yr), About 

117,000 acre-ft/yr is diverted and 14,000 acre-ft/yr of riparian 

ET, infiltration, or both.

Lower Walker River Basin 

Water Budgets

Water budgets were calculated for two reaches of 

the lower Walker River basin between the Wabuska gage 

and Walker Lake. The Walker River at Lateral 2‐A Siphon 

near Schurz, Nev. (Lateral 2‐A gage, 10302002), is the last 

continuous gage on the Walker River and separates the 

Wabuska–Schurz reach from the Schurz–Lake reach. Overall 

and groundwater budgets were calculated for each of these 

reaches and an overall water budget was calculated for the 

combined reaches. An overall water budget was calculated for 

the Walker Lake area.

Figure 16 is a schematic showing the water budget 

components for the Wabuska–Schurz reach, Schurz–Lake 

reach, and Walker Lake. The Walker River is the main 

source of inflow. Subsurface inflow, recharge, runoff, and 

precipitation are small sources of inflow compared to the 

Walker River. As water flows down the river, losses occur 

from ET, diversions, stream infiltration, and pumpage. 
Lower Walker River Basin Water Budgets 

29

Figure 16. Water budget components for the lower Walker River basin, Nevada. The length of the arrow indicates the relative amount of flow. The Walker Lake 

reach includes surrounding riparian and phreatophytic vegetation and the town of Walker Lake.

tac09-4153_fig16

Pumpage Diversions

Precipitation

Evaporation

Pumpage

Walker Lake Reach

Riparian ET

Recharge

Evaporation

Precipitation

Subsurface

inflow

Subsurface

flow

Pumpage

Diversions

Return

flow

Local

runoff

Walker Lake

ET by other than

riparian vegetation

ET by other than

riparian vegetation

Riparian,

other ET

Walker River inflow

Stream

infiltration Stream

infiltration

Subsurface

discharge

Subsurface

discharge

Induced

recharge

Induced

recharge

Subsurface outflow

to Double Spring

Subsurface outflow to

Wabuska lineament

Wabuska–Schurz Reach Schurz–Lake Reach

Weber

Reservoir

Walker River outflow

Riparian and

saltcedar ET
30 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Diversions not used in the Wabuska–Schurz reach is inflow to 

the Schurz–Lake reach. Diversions in excess of agricultural 

ET either return to the river or become induced recharge, 

which is irrigation water that infiltrates to the water table. 

Riparian ET lowers groundwater levels along the river and 

causes streamflow to infiltrate, as indicated by seasonal 

variations in low-flow discharge (Lopes and Allander, 2009). 

Induced recharge and stream infiltration is lost to ET by 

riparian and phreatophytic vegetation, pumpage, subsurface 

outflow from the basin, and subsurface discharge to the river 

and Walker Lake. Evaporation from Walker Lake is the largest 

source of outflow. 

Wabuska to Schurz Reach

Overall Water Budget

Streamflow into the Wabuska–Schurz reach at the 

Wabuska gage is 138,000 acre-ft/yr (table 10). Ungaged runoff 

from the northern Wassuk Range and Desert Mountains was 

assumed to be negligible.

Weber Reservoir is at an altitude of 4,200 ft in the Walker 

precipitation zone (table 2) and receives about 0.4 ft/yr of 

precipitation. Reservoir altitude and storage only have been 

monitored daily since 1995. The 1971–2000 mean annual 

water-surface area was estimated by comparing the annual 

mean reservoir storage during 1996–2006 to the annual mean 

streamflow at the Wabuska gage and reservoir storage of 

Bridgeport Reservoir and Topaz Lake. The strongest Pearson 

correlation was between storage of Weber (SW) and Bridgeport 

Reservoirs (SB). Linear regression resulted in an adjusted R2 of 

0.77:

W 0.2013* 523. B S = − S (6)

Using equation 6 and the mean annual storage of 

22,800 acre-ft for Bridgeport Reservoir, the 1971–2000 mean 

annual storage of Weber Reservoir is about 4,100 acre-ft. 

This volume corresponds to a surface area of 530 acres 

(Katzer and Harmsen, 1973). Inflow from precipitation 

is about 200 acre-ft/yr and total surface-water inflow is 

138,200 acre-ft/yr.

Subsurface inflow through Walker and Parker Gaps 

(fig. 17) was estimated by Huxel and Harris (1969). Since this 

estimate, wells drilled in Walker Gap indicate that alluvial 

sediments are only 50 ft thick and that the average hydraulic 

conductivity of fluvial sediments along the Walker River is 

about 70 ft/d (Lopes and Allander, 2009). The transmissivity in 

the Walker Gap area is about 3,500 compared to 20,000 ft2/d 

estimated by Huxel and Harris (1969), and subsurface inflow 

is about 100 compared to 700 acre-ft/yr (table 11).

Alluvial sediments likely are shallow in narrow gaps 

between bedrock outcrops like Walker and Parker Gaps. 

Parker Gap is about 50 percent wider than Walker Gap and 

was assumed to have sediments five times thicker (250 ft) with 

a hydraulic conductivity of 10 ft/d, the average conductivity 

of sediments away from the river (Lopes and Allander, 

2009). The transmissivity in the Parker Gap area is about 

2,500 ft2/d compared to 6,700 ft2/d estimated by Huxel and 

Harris (1969). However, the hydraulic gradient estimated 

from groundwater contours (Lopes and Allander, 2009) is 

2.3 times steeper than estimated by Huxel and Harris (1969). 

The estimate of 700 acre-ft/yr is the same rate estimated by 

Huxel and Harris (1969). Total subsurface inflow is about 

800 acre-ft/yr and total inflow to the Wabuska–Schurz reach is 

139,000 acre-ft/yr.

Outflow from the Walker River at Schurz has been 

measured at two gages. From 1913 to 1933, outflow was 

measured at the Walker River at Schurz, Nev. (Schurz gage, 

10302000), which has a 1971–2000 streamflow normal of 

114,000 acre-ft/yr. Since 1994, outflow has been measured 

at the Lateral 2‐A gage, which has a streamflow normal of 

108,000 acre-ft/yr. The locations of the Schurz and Lateral 2‐A 

gages are within 0.6 mi of each other and downstream from 

diversions and return flows on the Reservation.

Table 10. Overall water budget for the Wabuska–Schurz reach, 

lower Walker River basin, Nevada.

[Percent is of total inflow or outflow, imbalance is percent of total inflow. 

Abbreviations: acre-ft/yr, acre-foot per year; <, less than]

Water-budget component Flow 

(acre-ft/yr) Percent

Inflow

Walker River at Wabuska 138,000 99

Weber Reservoir precipitation 200 <1

Subsurface inflow 800 <1

Total inflow (rounded) 139,000 100

Outflow

Walker River at Lateral 2-A 108,000 74

Weber Reservoir evaporation 2,200 1

Riparian and phreatophytic 

evapotranspiration

12,500 9

Agricultural evapotranspiration 2,300 2

Net diversions1 14,400 10

Pumpage 200 <1

Subsurface outflow to Double Spring 2,700 2

Subsurface outflow to Schurz–Lake reach 2,700 2

Subsurface outflow to Wabuska lineament 100 <1

Total outflow (rounded) 145,000 100

Imbalance -6,000 -4

1 Total diversions minus estimated return flow.
Lower Walker River Basin Water Budgets 31

tac09-4153_fig18

West Walker River

East Walker River

East Walker River

Walker

Walker

Lake

Weber

Reservoir

Mount

Grant

Double

Spring

110B

110A

108

River

Schurz

Walker

Lake

MASON

VALLEY

AGAI PAH

HILLS

CALICO HILLS

DESERT MOUNTAINS

TERRILL

MOUNTAINS

GILLIS

RANGE

WASSUK RANGE

95

95

95

Parker

Butte

WALKER

GAP

PARKER

GAP

110C

109

CALIFORNIA

NEVADA

Area

of map

Base from U.S. Geological Survey digital data, 1:24,000 and 1:100,000, 1978-88. Walker 

Lake average lake altitude of 3937.5 ft for November 2006; Projection: Universal 

Transverse Mercator, Zone 11, North American Datum of 1983. Shaded-relief base 

from 90-meter Shuttle Radar Topography Mission digital data, 2000.

Soil permeability from Maurer and others, 2004.

119°00' 118°50' 118°40'

39°

10'

39°

00'

38°

50'

38°

40'

0 5 10 MILES

0 5 10 KILOMETERS

Walker River basin boundary

110A Walker River hydrographic-area boundary—

labeled with hydrographic area number

Walker Lake shoreline of 1882 (Rush, 1970)

EXPLANATION

6 Areas where net evapotranspiration was 

quantified—labeled with area number

6

4a

4b

5

3

2

1

Figure 17. Selected areas of the lower Walker River basin, Nevada, where net evapotranspiration was 

quantified. Results are summarized in table 12.
32 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Annual streamflow at Schurz decreased after Weber 

Reservoir was constructed in 1934, especially during droughts 

(fig. 18B). Prior to construction of the reservoir, a minimum 

of 5,000 acre-ft/yr flowed past Schurz even when streamflow 

at the Wabuska gage was less than 20,000 acre-ft/yr (fig. 18). 

After construction, less than 1,000 acre-ft/yr flowed past 

Schurz when streamflow at the Wabuska gage was less than 

35,000 acre-ft/yr. The regression equation for the Schurz 

gage (table 5) was used to predict annual flow at the Lateral 

2‐A gage for each year from 1995 through 2006 to measure 

the change in streamflow. Predicted flows were an average of 

6,000 acre-ft/yr more than measured streamflows, which is 

the difference in 1971–2000 streamflow normals between the 

Schurz and Lateral 2‐A gages. The difference also is equal to 

the sum of mean annual storage and evaporation from Weber 

Reservoir (discussed below).

The Lateral 2‐A streamflow normal of 108,000 acre-ft/yr 

was used for Walker River outflow from the reach. Total 

stream loss in the Wabuska–Schurz reach is 30,200 acre-ft/yr 

(22 percent). Stream losses include evaporation from Weber 

Reservoir, diversions for irrigation, riparian ET upstream and 

downstream from Weber Reservoir, and stream infiltration in 

excess of riparian ET.

Weber Reservoir is about 200 ft higher than Walker Lake. 

The evaporation rate estimated from equation 5 is 4.2 ft/yr 

from the mean annual surface area of 530 acres. Mean annual 

evaporation is about 2,200 acre-ft/yr.

Net ET is ET in excess of precipitation and occurs where 

vegetation derives water from infiltrated streamflow and 

groundwater. The map of ET units by Allander and others 

(2009) was used to estimate corrected net ET from certain 

areas of the lower Walker River basin (fig. 17; table 12). A 

total of 12,500 acre-ft/yr of corrected net ET by riparian and 

phreatophytic vegetation was estimated for the Wabuska–

Schurz reach. Net ET was negligible for the Double Spring 

area east of Schurz.

Diversions on the Reservation have been gaged at the 

Canal No. 1 and No. 2 gages since 1995. The 1971–2000 

normal diverted at the Canal No. 1 gage is 6,200 acre-ft/yr 

and 11,000 acre-ft/yr at Canal No. 2 gage for a total of 

17,200 acre-ft/yr. This value compares well to Schaefer (1980) 

who estimated 18,000 acre-ft was diverted during 1977.

During 2000, 3,000 acres of the Reservation were 

irrigated. Mapping of circular areas indicated 387 acres 

were irrigated by wells and center pivots in the Schurz–Lake 

reach. Groundwater is not used to flood irrigate fields as is 

done in Smith and Mason Valleys. The diversion rate on the 

Reservation is 6.6 ft/yr (17,200 acre-ft/2,613 acres). The 

Reservation is in the Walker precipitation zone and receives 

about 0.4 ft/yr of precipitation. The total applied-water rate is 

7.0 ft/yr, which is almost twice the rate in upstream valleys. 

Diversions in excess of net agricultural ET either return to the 

river or become induced recharge. The Lateral 2‐A gage is 

downstream from return flows and measures total stream loss. 

Return flows were subtracted from diversions so this outflow 

was not accounted for twice in the water budget.

Alfalfa fields in Mason Valley are lush and have an 

average corrected total ET rate of 3.2 ft/yr. Alfalfa fields 

on the Reservation are not as lush, which partly could be 

due to alkaline soils that were once submerged by Lake 

Lahontan. Canal No. 1 is used to irrigate 1,078 acres that 

have a corrected net ET of 1,800 acre-ft/yr. The net ET 

rate is 1.7 ft/yr (1,800 acre-ft/yr/1,078 acres) and the total 

ET rate including precipitation is 2.1 ft/yr. Diversion of 

6,200 acre-ft/yr is in excess of net ET by about 4,400 acre-ft/yr 

(240 percent). Return flows were not measured so 50 percent 

(2,200 acre-ft/yr) of the excess diversion was assumed to 

return to the river and 50 percent was assumed to be induced 

recharge. Net diversion from Canal No. 1 is 4,000 acre-ft/yr. 

Table 11. Estimates of subsurface flow through Walker and Parker Gaps, lower Walker River basin, Nevada.

[Abbreviations: H&H, values from Huxel and Harris, 1969; ft, foot; ft/d, foot per day; ft2/d, foot squared per day; ft/mi, foot per mile; mi, mile; acre-ft/yr, 

acre foot per year; –, not determined]

Subsurface 

flow section

Aquifer 

thickness 

(ft)

Hydraulic 

conductivity 

(ft/d)

Transmissivity 

(ft2

/d)

Hydraulic 

gradient 

(ft/mi)

Width 

(mi)

Subsurface 

inflow

(acre-ft/yr)

Walker Gap (this study) 50 170 3,500 5 0.7 100

Walker Gap (H&H) – – 20,000 6 .7 700

Parker Gap (this study) 2250 110 2,500 28 1.1 700

Parker Gap (H&H) – – 6,700 12 1.1 700

Total subsurface inflow (this study) 800

Total subsurface inflow (H&H) 1,400

1

 Average of measured values from Lopes and Allander (2009).

2

 Assumed value.
Lower Walker River Basin Water Budgets 33

tac09-4153_fig17

1,000 10,000 100,000

ANNUAL DISCHARGE AT WABUSKA, IN ACRE-FEET PER YEAR

100

1,000

10,000

100,000

500

5,000

5,000

50.000

50,000

ANNUAL DISCHARGE AT SCHURZ, IN ACRE-FEET PER YEAR

1:1 Line

0 100,000 200,000 300,000 400,000 0

100,000

200,000

300,000

400,000

1:1 Line

Figure 18B inset

A.

B.

Post-Weber Reservoir

Pre-Weber Reservoir

Figure 18. Annual stream discharge at Schurz, Nevada, compared to annual discharge at the Wabuska gage (A) prior 

to and after construction of Weber Reservoir in 1934 and (B) subset of data plotted on log scale to show differences at 

low discharge.

Canal No. 2 is used to irrigate 330 acres of alfalfa in the 

Wabuska–Schurz reach. Corrected net ET is 500 acre-ft/yr, the 

corrected net ET rate is 1.5 ft/yr (500 acre-ft/yr/330 acres), and 

the corrected total ET rate is 1.9 ft/yr. Diversion to these fields 

is unknown, so the diversion rate was assumed to be the same 

as for Canal No. 1. Total diversion is about 1,700 acre-ft/yr, 

which is 240 percent (1,200 acre-ft/yr) in excess of corrected 

net ET. Fifty percent (600 acre-ft/yr) of the excess diversion 

was assumed to be return flow and 50 percent was assumed 

to be induced recharge. Net diversion from Canal No. 2 is 

10,400 acre-ft/yr and 9,300 acre-ft/yr flows into the Schurz–

Lake reach. Total induced recharge in the Wabuska–Schurz 

reach is 2,800 acre-ft/yr.

Schurz has a population of 720, most of who live in the 

Wabuska–Schurz reach and use groundwater for their water 

supply. Schurz has no industrial and negligible commercial 

water use. Lopes and Evetts (2004) estimated 0.23 acre-ft/yr 

of pumpage per capita for domestic use. Using this rate, about 

200 acre-ft/yr of groundwater is pumped for domestic supply 

in the Schurz area. 

Induced recharge and infiltration of streamflow along the 

Walker River has created a groundwater mound in the Schurz 

area that separates subsurface flow towards Walker Lake from 

flow towards Double Spring and out of the Walker River basin 

(Lopes and Allander, 2009). Lopes and Allander estimated 

subsurface outflow through Double Spring ranges from 1,000 

to 5,000 acre-ft/yr with an average of 2,700 acre-ft/yr. In 

comparison, Schaefer (1980) estimated 4,500 acre-ft/yr of 

subsurface outflow. Subsurface flow into the Schurz–Lake 

reach was assumed to be the same as outflow through Double 

Spring.
34 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Lopes and Allander (2009) hypothesized that the 

Wabuska lineament could be a pathway through the Desert 

Mountains for subsurface outflow into southern Churchill 

Valley. If this hypothesis is correct, then most of the outflow 

is from northern Mason Valley. Groundwater altitudes 

indicate outflow also occurs from the upper part of the 

Wabuska–Schurz reach. Discharge measurements indicated 

less than 1 ft3/s of stream loss between the Wabuska and 

Cow Camp gages (Lopes and Allander, 2009). Infiltration in 

the upper part of the reach flows north towards the Wabuska 

lineament or flows downstream towards Weber Reservoir. 

Subsurface outflow through the Wabuska lineament is small 

and was assumed to be 100 acre-ft/yr (0.14 ft3/s). Total 

subsurface outflow from the Wabuska–Schurz reach is about 

5,500 acre-ft/yr.

Average annual inflow to the Wabuska–Schurz reach is 

139,000 acre-ft and average annual outflow is 145,000 acre-ft. 

The imbalance of 6,000 acre-ft/yr is 4 percent of the inflow. 

The small imbalance is insignificant statistically so the water 

budget balances. This assumes no change in groundwater 

storage, which is indicated by no change in water levels in 

the Schurz area during the past 50 years (Lopes and Allander, 

2009).

Groundwater Budget

Inflow to the Wabuska–Schurz groundwater system 

occurs from subsurface inflow through Parker and Walker 

Gaps, induced recharge, and infiltration along the Walker 

River. Subsurface inflow was estimated to be 800 acre-ft/yr 

and induced recharge was estimated to be 2,800 acre-ft/yr 

(table 13).

Stream infiltration between the Wabuska gage and Weber 

Reservoir was less than 1 ft3/s (Lopes and Allander, 2009), so 

infiltration was assumed to be equal to riparian ET (table 13). 

Virtually all stream infiltration in excess of riparian ET occurs 

along the 8.5 river miles between the Little Dam and Lateral 

2‐A gages. Stream infiltration between the Little Dam and 

Lateral 2‐A gages averages about 6,000 acre-ft/yr (Lopes and 

Allander, 2009). Corrected net ET by riparian vegetation along 

the Little Dam–Lateral 2‐A reach is about 3,500 acre-ft/yr. 

Infiltration in excess of riparian ET is about 2,500 acre-ft/yr. 

Groundwater outflow occurs from pumpage, 

subsurface outflow, and net ET. Pumpage was estimated to 

be 200 acre-ft/yr and total subsurface outflow through the 

Wabuska lineament, Double Spring, and to Walker Lake was 

estimated to be 5,500 acre-ft/yr. Total corrected net ET by 

riparian and phreatophytic vegetation is 10,300 acre-ft/yr.

Table 12. Net evapotranspiration from selected areas of the lower Walker River basin, Nevada.

[Areas are shown in figure 17. Net evapotranspiration is total evapotranspiration minus precipitation. Values, in acre-feet per year, have been reduced 14 percent 

from estimates by Allander and others (2009)]

Area No. Area name Irrigated 

land Riparian Phreatophytes Saltcedar Water Total

Wabuska–Schurz reach

1 Wabuska gage to Weber Reservoir 1200 5,800 1,400 0 0 7,400

2 Weber Reservoir 0 100 0 0 2,200 2,300

3 Weber Reservoir to Little Dam 0 600 100 0 0 700

4a Little Dam to Lateral 2-A gage and west of Walker River 1,800 1,900 800 0 0 4,500

4b Little Dam to Lateral 2-A gage and east of Walker River 500 1,600 200 0 0 2,300

Reach total 2,500 10,000 2,500 0 2,200 17,200

Double Spring

5 Double Spring 0 0 0 0 0 0

Schurz–Lake reach

6 Lateral 2-A gage to Walker Lake 1,700 1,000 4,600 1,800 0 9,100

Grand total 4,200 11,000 7,100 1,800 2,200 26,300

1

 Irrigated by streamflow from above the Wabuska gage.
Lower Walker River Basin Water Budgets 35

Table 13. Ground-water budget for the Wabuska–Schurz reach, 

lower Walker River basin, Nevada. 

[Percent is of total inflow or outflow, imbalance is percent of inflow. 

Abbreviation: acre-ft/yr, acre-foot per year]

Water-budget component Flow 

(acre-ft/yr) Percent

Inflow

Subsurface inflow 800 5

Induced recharge 2,800 18

Stream infiltration Wabuksa gage–Weber 

Reservoir1

5,800 38

Stream infiltration Little Dam–Lateral 2-A 

gages

6,000 39

Total inflow (rounded) 15,000 100

Outflow

Pumpage 200 1

Wabuska lineament outflow 100 1

Subsurface outflow to Double Spring 2,700 17

Subsurface outflow to Walker Lake 2,700 17

Riparian evapotranspiration Wabuksa gage–

Weber Reservoir

5,800 36

Riparian evapotranspiration Little Dam– 

Lateral 2-A gages

3,500 22

Phreatophytic evapotranspiration 1,000 6

Total outflow (rounded) 16,000 100

Imbalance -1,000 -7

1

Assumed to be equal to riparian evapotranspiration in this reach.

Total groundwater inflow was estimated to be 

15,000 acre-ft/yr and total outflow was estimated to be 

16,000 acre-ft/yr. The imbalance of 1,000 acre-ft/yr is 

7 percent of the inflow. The small imbalance is insignificant 

statistically so the water budget balances.

Schurz to Walker Lake Reach

Overall Water Budget

Streamflow into the Schurz–Lake reach is 

108,000 acre-ft/yr at the Lateral 2‐A gage (table 14). Ungaged 

runoff from the northern Wassuk Range and Gillis Range 

was assumed to be negligible. Diversions from Canal No. 2 

that are not applied in the Wabuska–Schurz reach is inflow to 

the Schurz–Lake reach. About 11,000 acre-ft/yr is diverted 

into Canal No. 2, 1,700 acre-ft/yr is applied to fields in the 

Wabuska–Schurz reach, and about 9,300 acre-ft/yr is inflow 

to the Schurz–Lake reach. Total surface-water inflow is 

117,300 acre-ft/yr.

Table 14. Overall water budget for the Schurz–Lake reach, 

lower Walker River basin, Nevada.

[Percent is of total inflow or outflow, imbalance is percent of inflow. 

Abbreviation: acre-ft/yr; acre-foot per year. Symbol: <, less than]

Water-budget 

component

Flow 

(acre-ft/yr) Percent

Inflow

Walker River at Lateral 2-A 108,000 90

Canal 2 diversions 9,300 8

Subsurface inflow 2,700 2

Recharge 500 <1

Total inflow (rounded) 120,000 100

Outflow

Walker River at Walker Lake 105,000 88

Riparian evapotranspiration 1,000 1

Phreatophytic evapotranspiration 4,600 4

Saltcedar evapotranspiration 1,800 2

Agricultural evapotranspiration 1,700 1

Subsurface outflow 5,000 4

Total outflow (rounded) 119,000 100

Imbalance 1,000 1

Subsurface inflow to the Schurz–Lake reach was assumed 

to be equal to outflow at Double Spring (2,700 acre-ft/yr). 

Everett and Rush (1967) estimated 500 acre-ft/yr of recharge 

from altitudes between 6,000 ft and 8,000 ft in HA 110A, 

which is the northern Wassuk Range in the Schurz–Lake 

reach. Total subsurface inflow is 3,200 acre-ft/yr. Total surface 

and subsurface inflow is about 120,000 acre-ft/yr. 

Outflow includes streamflow and subsurface discharge 

into Walker Lake and net ET. Although most of the reach is 

gaining, stream losses occur between the Lateral 2‐A gage 

and Walker Lake (Lopes and Allander, 2009). From 2000 to 

May 2005, little streamflow was measured at the Lateral 2‐A 

gage and Walker Lake declined about 21 ft. The maximum 

amount of infiltration possible along this reach likely occurred 

during the 2005 spring runoff. Maximum infiltration was 

estimated to be 8,000 acre-ft/yr (Lopes and Allander, 2009).

Huffman and Carpenter, Inc. (2007), estimated 

1,129 acre-ft of stream loss in the Lateral 2‐A–Walker Lake 

reach from March 14 to September 27, 2007. Most of the loss 

was estimated during March and April. Monthly discharge 

volumes at the Lateral 2‐A gage were about the same from 

March through May, but essentially no loss occurred during 

May. Aquifer storage apparently had reached a maximum even 

though the reach had a small amount of flow since August 

2006. Almost 3,000 acre-ft/yr of net ET by saltcedar and 

riparian vegetation occurs along this reach (table 12), which 

is assumed to be the minimum stream loss except when less 

discharge flows into the reach.
36 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Streamflow into the Schurz–Lake reach has been 

measured only since 1995. However, annual discharge at the 

Wabuska gage indicates most years had sufficient discharge to 

maintain aquifer storage near its maximum volume (fig. 19). 

From 1971 to 2000, discharge less than 35,000 acre-ft/yr 

(48 ft3/s) flowed into the lower Walker River basin during 

1977–78 and 1988–93. Low discharge also occurred during 

2002–03 when less than 1,000 acre-ft/yr was measured at 

the Lateral 2‐A gage. To estimate average stream loss in the 

reach during 1971–2000, it was assumed that all streamflow 

(1,000 acre-ft/yr) infiltrated during low discharge years, a 

maximum of 8,000 acre-ft/yr occurred during 1979 and 1995 

following low discharge years, and 3,000 acre-ft/yr infiltrated 

during all other years. The average stream loss is about 

3,000 acre-ft/yr (3 percent), and average streamflow reaching 

Walker Lake is about 105,000 acre-ft/yr.

A total of 7,400 acre-ft/yr of corrected net ET by 

nonagricultural vegetation occurs in the Schurz–Lake reach 

(table 14). Most of the ET is from phreatophytic vegetation 

including saltcedar. In addition, agricultural ET consumes 

1,700 acre-ft/yr of Canal No. 2 diversions and groundwater 

pumpage. Canal No. 2 is used to flood irrigate 1,000 acres 

of alfalfa and wells are used to irrigate 387 acres in the 

Schurz–Lake reach. The corrected net ET rate is about 

1.2 ft/yr (1,700 acre-ft/yr/1,387 acres) and the corrected total 

ET rate is 1.6 ft/yr. No return flows exist to the Walker River 

downstream from the Lateral 2‐A gage, so excess diversions 

become induced recharge.

Lopes and Allander (2009) used Darcy’s Law and 

estimated subsurface outflow to Walker Lake ranges from 

5,000 to 16,000 acre-ft/yr with an average of 10,000 acre-ft/yr. 

Figure 19. Discharge at streamflow gaging stations Walker River near Wabuska, Nevada (USGS station number 

10301500), and Walker River at Lateral 2-A Siphon near Schurz, Nevada (10302002). Periods are indicated when 

discharge was low (less than 35,000 acre-ft/yr) and when losses were measured between the Lateral 2-A gage and 

Walker Lake.

Losses measured between

Lateral 2-A and near Mouth gages

1971 1975 1980 1985 1990 1995 2000 2005 2007

0

1,000

2,000

3,000

DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

WATER YEAR (1990 = OCTOBER 1, 1989, TO SEPTEMBER 30, 1990) 

Discharge at Wabuska gage

less than 35,000 acre-feet per year

Wabuska gage (10301500)

Lateral 2-A gage (10302002)
Lower Walker River Basin Water Budgets 37

To check this estimate, subsurface outflow was estimated 

as a residual of an overall water budget for the entire reach 

from Wabuska to Walker Lake (table 15). Total inflow 

from the Walker River, subsurface inflow, and recharge is 

140,000 acre-ft/yr. Total outflow from the Walker River, 

corrected net ET, pumpage, and subsurface outflow 

through Double Spring and the Wabuska lineament is 

134,000 acre-ft/yr. The residual of 6,000 acre-ft/yr compares 

well to the minimum estimate of subsurface flow using 

Darcy’s Law, so 5,000 acre-ft/yr was used in the water 

budget. Land-based ET rates would have to be corrected by 

about 30–45 percent for the residual to equal the average 

or maximum estimates of subsurface discharge, which is 

unsupported by independent estimates of lake evaporation.

Total inflow to the Schurz–Lake reach was estimated 

to be 120,000 acre-ft/yr and total outflow was estimated to 

be 119,000 acre-ft/yr. The imbalance of 1,000 acre-ft/yr is 

1 percent of the inflow. The small imbalance is insignificant 

statistically so the water budget balances. This assumes no 

change in groundwater storage, which is indicated by no 

change in water levels during the past 50 years (Lopes and 

Allander, 2009).

Groundwater Budget

Groundwater inflow to the Schurz–Lake reach includes 

subsurface inflow from the Wabuska–Schurz reach, stream 

infiltration, groundwater recharge, and induced recharge. 

Subsurface inflow was assumed to be 2,700 acre-ft/yr, 

stream infiltration was estimated to be 3,000 acre-ft/yr, and 

groundwater recharge was estimated to be 500 acre-ft/yr 

(Everett and Rush, 1967; table 16). Induced recharge occurs 

from the 9,300 acre-ft/yr from Canal No. 2 that is applied 

to 1,000 acres. Excess diversions do not return to the river, 

so induced recharge is the inflow less 1,200 acre-ft/yr of 

corrected agricultural ET (8,100 acre-ft/yr). Total inflow to the 

groundwater system is 14,000 acre-ft/yr,

Groundwater outflow is from subsurface outflow 

and net ET. Subsurface outflow was estimated to be 5,000 

acre-ft/yr. Pumpage was assumed to be equal to corrected 

net ET from 387 acres of alfalfa irrigated with groundwater. 

Total corrected net ET from nonagricultural vegetation is 

7,400 acre-ft/yr. Total outflow from the groundwater system 

is 13,000 acre-ft/yr. The imbalance of 1,000 acre-ft/yr is 

7 percent of the inflow. The small imbalance is insignificant 

statistically so the water budget balances.

Table 15. Overall water budget from Wabuska to Walker Lake, 

lower Walker River basin, Nevada.

[Percent is of total inflow or outflow, percent subsurface outflow is percent of 

inflow. Abbreviations: acre-ft/yr, acre-foot per year. Symbol: <, less than]

Water-budget 

component

Flow 

(acre-ft/yr) Percent

Inflow

Walker River at Wabuska 138,000 99

Subsurface inflow 800 <1

Weber Reservoir precipitation 200 <1

Recharge 500 <1

Total inflow (rounded) 140,000 100

Outflow

Walker River at Walker Lake 105,000 78

Pumpage 200 <1

Riparian evapotranspiration 11,000 8

Phreatophytic evapotranspiration 7,100 6

Saltcedar evapotranspiration 1,800 1

Agricultural evapotranspiration 4,000 3

Weber Reservoir evaporation 2,200 2

Subsurface outflow to Double Spring, 

Wabuska lineament

2,800 2

Total outflow – subsurface outflow to lake 134,000 100

Subsurface outflow to lake (residual) 6,000 4

Table 16. Ground-water budget for the Schurz–Lake reach, 

lower Walker River basin, Nevada.

[Percent is of total inflow or outflow, percent subsurface outflow is percent of 

inflow. Abbreviations: acre-ft/yr, acre-foot per year]

Water-budget 

component

Flow 

(acre-ft/yr) Percent

Inflow

Subsurface inflow 2,700 19

Stream infiltration 3,000 21

Recharge 500 3

Induced recharge 8,100 57

Total inflow (rounded) 14,000 100

Outflow

Riparian evapotranspiration 1,000 8

Saltcedar evapotranspiration 1,800 14

Phreatophytic evapotranspiration 4,600 36

Agricultural evapotranspiration 500 4

Subsurface outflow 5,000 38

Total outflow (rounded) 13,000 100

Imbalance 1,000 7
38 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Walker Lake

Surface-water inflow to Walker Lake includes 

105,000 acre-ft/yr of streamflow from the Walker River 

(table 17). Runoff from the Gillis Range was assumed to 

be negligible. Drainages along the Wassuk Range that are 

adjacent to Walker Lake include Rose Creek at the south 

to an unnamed creek south of Deadman Creek at the north 

(tables 5 and 6). Local runoff is about 3,000 acre-ft/yr. About 

2,000 acre-ft/yr is diverted to the Army Depot (Everett and 

Rush, 1967), so about 1,000 acre-ft/yr discharges into the lake 

as surface or subsurface flow.

Rose Creek Reservoir has a storage capacity of 

92 acre-ft2. Cat Creek Reservoir is south of Walker Lake and 

has a storage capacity of 120 acre-ft, so reservoir storage 

is a small percentage of the runoff. A concrete catchment 

intercepts much of the runoff from Cottonwood Creek before 

it reaches the alluvial fan. The catchment runs along the base 

of the Wassuk Range and also intercepts runoff from Dutch, 

Squaw, and Rose Creeks. Excess flow from Cottonwood 

and Dutch Creeks is released to Walker Lake at Cottonwood 

Line Valve Box 14 outlet near Hawthorne, Nev. (10302170). 

Releases were 242 acre-ft during 2006 and 357 acre-ft during 

2007. The average release was assumed to be 300 acre-ft/yr 

and about 700 acre-ft/yr is subsurface discharge along the west 

side of Walker Lake.

Walker Lake is in the Walker precipitation zone and 

receives about 0.4 ft/yr of precipitation. The average lake 

altitude during 1971–2000 was 3,959.3 ft, which corresponds 

to a water-surface area of 36,620 acres (Lopes and Smith, 

2007). Total inflow from precipitation is 14,600 acre-ft/yr. 

Total surface-water inflow is 122,600 acre-ft/yr, which is 

94 percent of all inflow.

Subsurface inflow from north of Walker Lake was 

estimated to be 5,000 acre-ft/yr (table 17). Lopes and 

Allander (2009) estimated subsurface inflow from south of 

Walker Lake ranges from 2,200 to 6,600 acre-ft/yr with 

an average of 4,400 acre-ft/yr. In comparison, Everett 

and Rush (1967) estimated subsurface inflow south of 

Walker Lake is 2,000 acre-ft/yr. Everett and Rush (1967) 

estimated 2,000 acre-ft/yr of recharge in Whisky Flat 

and 3,500 acre-ft/yr of recharge around Hawthorne. Total 

runoff from the Wassuk Range south of Walker Lake is 

about 3,800 acre-ft/yr, so recharge estimates likely are 

overestimated. About 1,600 acre-ft/yr of groundwater is 

pumped to irrigate 500 acres in Whisky Flat and the city of 

Hawthorne has municipal wells in Whisky Flat, so some 

recharge is intercepted before reaching Walker Lake. Pumpage 

in Whisky Flat has decreased groundwater levels 70 ft since 

1956 (Lopes and Allander, 2009), indicating pumpage exceeds 

recharge. Therefore, the minimum value of 2,200 acre-ft/yr of 

subsurface inflow was used in the water budget.

The estimate of 600 acre-ft/yr of recharge along the 

Gillis Range by Everett and Rush (1967) was used for 

subsurface inflow along the east side of Walker Lake. Total 

subsurface discharge from all sources around Walker Lake is 

8,500 acre-ft/yr. Subsurface discharge includes regional flow 

through the aquifers towards Walker Lake and drainage from 

the aquifers induced by the decline in lake level. Stabilizing 

the lake level eventually will reduce aquifer drainage, but 

drainage likely has been only a few percent of the overall 

water budget. However, water managers should be aware of 

the transient nature of the water budget.

Virtually all outflow is evaporation from Walker Lake. 

The evaporation rate estimated from equation 4 is 4.3 ft/yr. 

The 1971–2000 mean annual surface area is 36,620 acres 

and mean annual evaporation is about 157,400 acre-ft/yr 

(table 17). Corrected net ET by vegetation surrounding 

Walker Lake is about 2,200 acre-ft/yr and 2,000 acre-ft/yr 

of local runoff is diverted to the Army Depot. The town of 

Walker Lake has a population of 391 that uses groundwater 

for their water supply. Using a per capita pumpage rate of 

0.23 acre-ft/yr (Lopes and Evetts, 2004), about 100 acre-ft/yr 

of groundwater is pumped for domestic supply. Total outflow 

is about 162,000 acre-ft/yr.

Table 17. Overall water budget for Walker Lake, Nevada.

[Percent is of total inflow or outflow, storage decrease and imbalance is 

percent of outflow. Abbreviation: acre-ft/yr; acre-foot per year. Symbol: <, 

less than]

Water-budget 

component

Flow 

(acre-ft/yr) Percent

Inflow

Walker River 105,000 81

Local runoff 1 3,000 2

Precipitation 14,600 11

Subsurface inflow-north 5,000 4

Subsurface inflow-south 2,200 2

Subsurface inflow-east 600 <1

Total inflow (rounded) 130,000 100

Outflow

Lake evaporation 157,400 97

Evapotranspiration 2,200 1

Diverted local runoff 2,000 1

Pumpage 100 <1

Total outflow (rounded) 162,000 100

Storage

Storage decrease -29,000 18

Imbalance -3,000 2

1

300 acre-ft/yr of local runoff is surface flow and 700 acre-ft/yr is 

subsurface flow to the west side of Walker Lake.

2

http://water.nv.gov/Engineering/Dams/Dam_Query.cfm
Lower Walker River Basin Water Budgets 39

Average annual storage change is the difference in the 

volume of Walker Lake between 1971 and 2000 divided by 

30. The beginning storage volume was 3,173,000 acre-ft and 

the ending storage volume was 2,299,000 acre-ft. Total storage 

loss was 874,000 acre-ft and the average annual loss was 

29,000 acre-ft. The range is storage loss was estimated using 

an error of 0.5 ft in the bathymetry of Walker Lake (Lopes and 

Smith, 2007). Minimum storage loss is 28,000 acre-ft/yr and 

maximum storage loss is 30,000 acre-ft/yr.

The water budget for Walker Lake is:

 ,

where

is the annual total inflow to the lake;

is the annual total outflow from the lake; and

is the annual change in lake storage (negative for

a declining lake)

s

s

I O

I

O

− = ∆

∆

.

(7)

Total inflow was estimated to be 130,000 acre-ft/yr, 

total outflow is 162,000 acre-ft/yr, and the difference is 

‐32,000 acre-ft/yr. Storage change estimated directly is 

‐29,000 acre-ft/yr. The imbalance in the water budget is 

‐3,000 acre-ft/yr, which is 2 percent of the total outflow 

(table 17). The small imbalance is insignificant statistically so 

the water budget balances.

Dissolved-solids concentrations of 8,000, 10,000, and 

12,000 mg/L have been proposed to maintain a healthy 

population of Lahanton cutthroat trout in Walker Lake. These 

concentrations represent long-term average concentrations, 

but during prolonged droughts dissolved solids could reach 

concentrations that threaten the fishery. Water budgets were 

calculated to provide managers a range in supplemental 

inflows needed to maintain dissolved-solids concentrations in 

Walker Lake at 8,000, 10,000, and 12,000 mg/L. 

Years of supplemental inflow, above average inflow, 

or both will be needed to raise the lake-surface altitude and 

dilute salts to these concentrations. Then, supplemental inflow 

will need to be sustained to maintain the lake-surface altitude 

and dissolved-solids concentrations. The relation between 

lake-surface altitude and dissolved-solids concentrations is 

nonlinear, so a polynomial regression equation was used to 

estimate dissolved-solids concentrations (DS) at lake-surface 

altitudes (AltLake) ranging between 3,931 ft, the altitude in 

October 2008, and 4,000 ft:

7

2

2.9872521*10 14,931.8144*

 1.8664*( ) .

Lake

Lake

DS Alt

Alt

= −

+

(8)

Equation 8 has an adjusted R2 of 0.96 (fig. 20). Rounding 

regression coefficients or extrapolation of the equation 

outside the altitude range may lead to erroneous estimates. 

Measured value

3,920 3,930 3,940 3,950 3,960 3,970 3,980 3,990 4,000

LAKE ALTITUDE, IN FEET ABOVE MEAN SEA LEVEL, NATIONAL GEODETIC VERTICAL DATUM OF 1929

6,000

7,000

8,000

9,000

10,000

11,000

12,000

13,000

14,000

15,000

16,000

17,000

DISSOLVED SOLIDS, IN MILLIGRAMS PER LITER

2.9872521 * 107 - 14,931.8144 * Altitude

 + 1.8664 * Altitude2

Figure 20. Dissolved-solids concentrations versus lake altitude, Walker Lake, Nevada.
40 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

The dissolved-solids concentration is about 8,000 mg/L when 

the lake-surface altitude is 3,986 ft, 10,000 mg/L at 3,965 

ft, and 12,000 mg/L at 3,952 ft (table 18). Thomas (1995) 

estimated dissolved solids would be 10,000 mg/L at 3,964 ft, 

which compares well to equation 8. Seven-hundred thousand, 

1.2 million, and 2 million acre-ft of additional water is 

needed to raise Walker Lake from 3,931 ft to 3,952, 3965, and 

3,986 ft, respectively.

Water budgets were calculated assuming that increases 

in lake-surface altitude only affect the amount of precipitation 

and evaporation. However, groundwater inflow and 

phreatophytic discharge could decrease as surrounding areas 

become submerged. Supplemental inflows range from 26,000 

to 53,000 acre-ft/yr depending on the lake-surface altitude. 

At 3,964 ft, supplemental inflow is 35,000 acre-ft/yr, which is 

12,000 acre-ft/yr less than estimated by Thomas (1995). The 

difference partly is due to Thomas (1995) estimating Walker 

River inflow as a residual, which combined errors from the 

water budget and resulted in a lower estimate of inflow from 

the river than this study.

Table 18. Water budget to maintain lake-surface altitudes between 3,952 and 3,986 feet at Walker Lake, Nevada.

[Altitude is feet above National Geodetic Vertical Datum of 1929. Water budgets are based on 1971–2000 average annual flows. Supplemental volume is 

volume needed to raise lake-surface altitude from 3,931 feet. Supplemental inflow is inflow in addition to average annual inflows needed to maintain altitude. 

Abbreviations: acre-ft, acre-foot; acre-ft/yr, acre-foot per year; ft; foot; mg/L, milligram per liter]

Lake-surface altitude (ft)

3,952 3,964 3,965 3,986

Dissolved-solids concentration (mg/L) 12,000 10,200 10,000 8,000

Supplemental volume (acre-ft) 700,000 1,100,000 1,200,000 2,000,000

Inflow (acre-ft/yr)

Water-budget component

Walker River 105,000 105,000 105,000 105,000

Local runoff1 3,000 3,000 3,000 3,000

Precipitation 14,100 15,000 15,100 16,800

Subsurface inflow-north 5,000 5,000 5,000 5,000

Subsurface inflow-south 2,200 2,200 2,200 2,200

Subsurface inflow-east 600 600 600 600

Subsurface inflow-drainage 300 300 300 300

Total inflow (rounded) 130,000 131,000 131,000 133,000

Outflow (acre-ft/yr)

Water-budget component

Lake evaporation 151,700 161,700 162,500 181,200

Evapotranspiration 2,200 2,200 2,200 2,200

Diverted local runoff 2,000 2,000 2,000 2,000

Pumpage 100 100 100 100

Total outflow (rounded) 156,000 166,000 167,000 186,000

Supplemental inflow (acre-ft/yr, rounded) 26,000 35,000 36,000 53,000

1

300 acre-ft/yr of local runoff is surface flow and 700 acre-ft/yr is subsurface flow to the west side of Walker Lake.
Summary 41

Summary

The Walker River is the main source of inflow to Walker 

Lake, a closed-basin lake in west-central Nevada. The only 

outflow from Walker Lake is evaporation from the lake 

surface. Between 1882 and 2008, agricultural diversions 

resulted in a lake-level decline of more than 150 ft and storage 

loss of 7,400,000 acre-ft. Evaporative concentration increased 

dissolved solids from 2,500 to 17,000 mg/L. The increase in 

salinity threatens the survival of the Lahontan cutthroat trout, 

a native species listed as threatened under the Endangered 

Species Act.

This report describes streamflow in the Walker River 

basin and an updated water budget of Walker Lake. The report 

emphasizes the lower Walker River basin, which is the area 

downstream from the Wabuska gage. Surface-water budgets 

in the upper Walker River basin upstream from the Wabuska 

gage also are described. Water budgets are based on average 

flows for a 30-year period (1971–2000).

The Walker River basin is about 3,950 square miles and 

straddles the California–Nevada border. Most streamflow in 

the basin originates as snowmelt in the Sierra Nevada that 

flows down the East and West Forks of the Walker River, 

which merge in southern Mason Valley. Outflow from Mason 

Valley and inflow to the lower Walker River basin is measured 

at the Wabuska gage. Three reservoirs in the basin store 

water that is used to irrigate fields in Smith Valley, Mason 

Valley, and the Reservation. In 2000, a total of 88,600 acres 

of irrigated land was mapped in the Walker River basin. The 

primary crop in the basin is alfalfa.

Walker Lake is bounded on the west by the Wassuk 

Range and on the east by the Gillis Range. The Wassuk Range 

rises abruptly from the lake by more than 7,000 ft and has 

a maximum altitude of 11,239 ft at Mount Grant. The Gillis 

Range is not as steep and has a maximum altitude of 7,887 ft. 

The lowest altitude is 3,849 ft at the deepest part of Walker 

Lake. Mean annual precipitation ranges from about 4 in. at 

Walker Lake to 56 in. along the crest of the Sierra Nevada. 

Mean precipitation at Mount Grant, the highest mountain 

adjacent to Walker Lake, is about 16 in/yr.

Total surface-water inflow to the upper Walker 

River basin was estimated to be 387,000 acre-ft/yr. About 

223,000 acre-ft/yr (58 percent) is from the West Fork of the 

Walker River; 145,000 acre-ft/yr (37 percent) is from the 

East Fork of the Walker River; 17,000 acre-ft/yr (4 percent) 

is from the Sweetwater Range; and 2,000 acre-ft/yr (less than 

1 percent) is from the Bodie Mountains, Pine Grove Hills, 

and western Wassuk Range. Outflow from the upper Walker 

River basin is 138,000 acre-ft/yr at the Wabuska gage. About 

249,000 acre-ft/yr (64 percent) of inflow is diverted for 

irrigation, transpired by riparian vegetation, evaporates from 

lakes and reservoirs, and recharges alluvial aquifers.

Stream losses in Antelope, Smith, and Bridgeport Valleys 

are due to evaporation from reservoirs and agricultural 

diversions with negligible stream infiltration or riparian 

evapotranspiration (ET). The diversion rate in Antelope and 

Smith Valleys was estimated to be 3.0 ft/yr in each valley. 

Irrigated fields receive an additional 0.8 ft/yr of precipitation, 

groundwater pumpage, or both for a total applied-water rate 

of 3.8 ft/yr. The corrected total ET rate for alfalfa is about 

3.2 ft/yr, so about 0.6 ft/yr (15 percent) flushes salts from the 

soil. The diversion rate in Bridgeport Valley was estimated 

to be 1.1 ft/yr and precipitation is 1.3 ft/yr. The total appliedwater rate of 2.4 ft/yr is used to irrigate pasture grass.

The total applied-water rate in East Fork of the Walker 

River and Mason Valley was estimated to be 4.8 ft/yr in each 

valley. The higher rate likely is due to appreciable infiltration, 

riparian ET, or both. Stream loss from infiltration and riparian 

ET is about 3,000 acre-ft/yr along the East Fork of the Walker 

River and about 14,000 acre-ft/yr in Mason Valley.

Overall and groundwater budgets were calculated for 

the Wabuska–Schurz reach and Schurz–Lake reach. Overall 

water budgets were calculated for the combined reaches and 

Walker Lake. Imbalances in the water budgets range from 1 

to 7 percent, which is insignificant statistically, so the water 

budgets balance. Total inflow from Wabuska to Walker Lake 

is 140,000 acre-ft/yr. Stream and subsurface discharge into the 

northern end of Walker Lake totals 110,000 acre-ft/yr. About 

30,000 acre-ft/yr is lost on the Reservation from agricultural 

ET, ET by native and invasive vegetation, domestic pumpage, 

and subsurface outflow through Double Spring and the 

Wabuska lineament. 

Alfalfa fields in the upper Walker River basin are lush 

and have a corrected total ET rate of 3.2 ft/yr. Alfalfa fields on 

the Reservation are not as lush and have a corrected total ET 

rate of 1.6–2.1 ft/yr, but the total applied-water rate is about 

7.0 ft/yr. Most excess diversions become induced recharge, 

which was estimated to total almost 11,000 acre-ft/yr.

Surface and subsurface inflow to Walker Lake totals 

130,000 acre-ft/yr. Virtually all outflow is evaporation from 

the lake and totals 162,000 acre-ft/yr. The difference between 

inflow and outflow is ‐32,000 acre-ft/yr. Storage change 

is -29,000 acre-ft/yr for an imbalance of 3,000 acre-ft/yr 

(2 percent). The small imbalance is insignificant statistically 

so the water budget balances. 

Water budgets were calculated to provide managers a 

range in supplemental inflows needed to maintain dissolvedsolids concentrations at 8,000, 10,000, and 12,000 mg/L. From 

about 700,000 to 2,000,000 acre-ft is needed to dilute the lake 

to these concentrations and from 26,000 to 53,000 acre-ft/yr 

of supplemental inflow is needed to maintain concentrations 

at 8,000 to 12,000 mg/L. Years of supplemental inflow, above 

average inflow, or both, will be needed to raise the lakesurface altitude and dilute salts.
42 Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

Acknowledgments

This study would not have been possible without access 

to lands and wells granted by numerous private land owners 

in the basin. The authors also appreciate the cooperation, 

assistance, and information provided by: Jon McMasters 

and Gina Wachsmuth, Walker River Paiute Tribe; Kenneth 

Spooner, Walker River Irrigation District; James Shaw, 

Walker River Federal Watermaster; John Peterson and David 

Musselman, Hawthorne Army Ammunition Depot; and Elmer 

Bull, Nevada Department of Wildlife.

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Lopes and others—Water Budgets of the Walker River Basin and Walker Lake, California and Nevada—Scientific Investigations Report 2009–5157