Science to Sustain Terminal Lakes: 

The Walker River Basin Study

Section 2507 of Public Law 107−171 (2002 Farm Bill) provided $200,000,000 to be used by the Secretary of the 

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 language “Restoration of fish, wildlife, 

and associated habitats in watersheds of certain lakes”. The amendment specified that only Pyramid, Summit, 

and Walker Lakes in the State of Nevada were to be considered under Section 2507, Public Law 107−171.

Terminal lakes are the end points for surface-water drainage in topographically enclosed basins. Terminal lakes 

can provide a habitat for aquatic life and migratory birds 

and an area for recreational activities such as fishing and 

boating. These lakes are sensitive to changes in climate 

and upstream water use such as streamflow diversions and 

exportation for agriculture and urban use. Since the early 

1900s, as upstream agricultural diversions have increased, 

the fresh-water ecosystem of Walker Lake has become atrisk due to increased salinity.

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

Survey (USGS), in cooperation with the Bureau of Reclamation, identified the following objectives to help sustain 

Walker Lake:

• Quantify the volume of streamflow in the Walker 

River Basin, and determine the percentage of that 

streamflow from each valley; 

• Determine evapotranspiration (ET) losses from 

vegetation and evaporation from the lake surface;

• Develop an improved water budget for Walker 

Lake; and

• Develop the capability to determine how changes 

in water use in the Walker River Basin will affect 

streamflows to Walker Lake.

To accomplish these objectives, the USGS will study the 

Walker River Basin from near Wabuska in the northern part 

of the Basin to Walker Lake. The lower portion of the Basin 

was selected for study because (1) surface-water/groundwater interactions are complex and poorly understood, (2) 

few data are available, and (3) it is the terminal portion of 

the Basin and includes Walker Lake. The study will include 

the following tasks:

USGS Fact Sheet 2005-3124 

Last updated: November 2005

U.S. Department of the Interior

U.S. Geological Survey
March 2005U

�����

�����

�����

�����

�����

�����

�����

�����

�����

����������������������������������������������

�����

�����

�����

�����

�����

������

������

������

������

������

�������������������������������

������������������������

���������������������

������������������������������

������������������������������������

���� ���� ���� ���� ���� ���� ���� ���� ���� ���� ���� ���� ���� ����

�����������

�����

�������

Task 1—New and Improved Surface-Water Stations

The USGS currently operates 14 continuous-record 

streamgaging stations in the basin. Data from these stations 

help form the basis for water management decisions and 

irrigation operations, as well as the surface-water component of the water-budget analysis. However, analysis of the 

station network identified a number of important locations 

where additional streamflow data and upgrades to existing 

stations were needed. Six streamgaging stations have been, 

or will be, added; three stations have been upgraded; and 

one station has been reactivated. Data from these stations 

is available from the Walker River Basin study web site at

http://nevada.usgs.gov/walker/data.htm.

Task 2—ET Measurements

Loss of water in the Walker River Basin is mainly attributed to evaporation from open water and soils, and 

transpiration of water from plants (the combination of 

evaporation and transpiration known as ET). Sophisticated sensors in alfalfa fields, natural vegetation areas, and 

on the lake measure parameters such as solar radiation, 

air and ground temperatures, relative humidity, and wind 

speed and direction. These data are used to calculate daily 

values of ET. These values, and vegetation mapping from 

satellite and aerial imagery, will be used to estimate ET 

for the basin. 

Task 3—Water Budget for Walker Lake

Surface water, ET, and additional data acquired during 

this study will be used to refine the water budget for Walker Lake. Additional data collection includes estimates of 

ground-water discharge to Walker Lake and a new bathymetric map of Walker Lake to refine the relation between 

lake elevation, volume, and surface area. A more precise 

water budget will allow agencies to predict the effects of 

water management alternatives on the elevation and salinity of Walker Lake with greater accuracy. 

Task 4—Surface- and Ground-Water Relations

During the first few years of this study, data will be collected to identify parts of the Walker River where streamflow 

infiltrates into the aquifer and where ground water discharges into the river. The USGS also plans to develop a 

computer model to simulate flows between the river and 

aquifer from Wabuska to Walker Lake. This model could 

be used to depict possible changes in the flow of the river 

resulting from changes in water use in, and above, the 

modeled area.

This study, started in 2004, will be completed in 2008. 

Results of the study will be published in USGS Scientific Investigations Reports and available on the internet. 

Federal, State, Tribal, and local agencies that are trying 

to preserve the ecosystems, agricultural economy, and 

lifestyle of residents in the basin may benefit from a better understanding of the hydrology of the Walker River 

Basin. Additional information and progress of the study 

is available on the Walker River Basin study web site at 

http://nevada.usgs.gov/walker/index.htm.

For more information about this study, please contact:

Thomas J. Lopes, Hydrologist

USGS Nevada Water Science Center

333 W. Nye Lane, Room 203

Carson City, NV 89706-0866

Tel: (775) 887-7688 Email: tjlopes@usgs.gov 

Fax: (775) 887-7629 URL: http://nevada.usgs.gov

USGS Fact Sheet 2005-3124

Last updated: November 2005 

U.S. Department of the Interior

U.S. Geological Survey