Science in the Truckee River Basin

Science Center Objects

The Truckee River flows for 120 miles from the outlet of Lake Tahoe in California, into Nevada, through the city of Reno, until it terminates at Pyramid Lake and is the only source of surface-water outflow from Lake Tahoe. The majority of the streamflow in the Truckee River comes from the Sierra Nevada snowpack. Contributions to the river in Nevada are small due to the Sierra Nevada’s “rain shadow effect” which limits annual precipitation in the Nevada part of the Truckee River basin to less than 10 inches per year. The Truckee River supplies water to a diverse group of water users: power generation, municipalities, industry, and agriculture as well as being the primary source of water for Pyramid Lake. The Truckee is critical to maintaining Pyramid Lake water levels and supporting the endangered cui-ui lakesucker and the threatened Lahontan cutthroat trout.

Map of the Truckee River Basin, Nevada and California
Map of the Truckee River Basin, Nevada and California. (Public domain.)

The Truckee River basin (hydrographic region 6) covers over 4,700 square miles and straddles the California-Nevada border. The Truckee River Basin includes the following hydrographic areas: Winnemucca Lake Valley, pyramid Lake Valley, Dodge Flat, Tracy Segment, Warm Springs Valley, Spanish Springs Valley, Sun Valley, Truckee Meadows, pleasant Valley, Washoe Valley, Lake Tahoe Basin, and the Truckee Canyon Segment. Major cities in the Truckee River Basin are Truckee, California, and Reno and Sparks, Nevada.

Conflicts regarding Truckee River water rights have been long-standing and intense among various economic, political, ecological, and institutional interests because the average-annual demand for water is greater than the supply. Water rights are fully or over-allocated with respect to annual water volumes. Diversions from the Truckee River, along with the arid desert enviroment, caused water levels in Pyramid Lake to drop more than 90 feet between 1891 and 1966. Water levels in Pyramid Lake have stabilized although they still fluctuate in response to hydrologic conditions.

One of the first large diversions of the Truckee River was authorized by the 1902 Reclamation Act for agricultural irrigation. Allocations of water from the Truckee River are now governed by the Truckee River Operating Agreement which is a major part of Public Law 101-618, the Truckee-Carson-Pyramid Lake Water Rights
Settlement Act of 1990.

USGS Nevada Water Science Center maintains more than 42 streamflow gages on the Truckee River.


Real-Time Streamflow :: Daily Values :: Peak-Flow:: Water Quality

Streamflow in the Truckee River compared to elevation of Pyramid Lake
Streamflow in the Truckee River compared to elevation of Pyramid Lake. (Public domain.)


Effects of Groundwater Withdrawals, Tracy Segment

For more information, contact Carl Thodal

The USGS Nevada Water Science Center began an investigation in 2010 to quantify hydrologic effects of groundwater withdrawals on Truckee River streamflow in the Tracy Segment hydrographic area, Storey, Washoe and Lyon Counties, Nevada. Groundwater gradients have been monitored at sites near pumping wells and the river. Water-level fluctuations resulting from local pumping are interpreted with flow models to estimate the transmissivity of basin fill and bedrock aquifers and quantify the volume of Truckee River water potentially captured by groundwater pumpage.

Visit the project web page: Effects of Groundwater Withdrawals, Tracy Segment


Water for the Seasons

For additional information, contact Eric Morway

Water for the Seasons (WftS) is a four year study funded by the National Science Foundation and the U.S. Department of Agriculture. WtfS uses the Truckee-Carson River System (TCRS) as a pilot study to learn how to best link science with decision-making in snow-fed arid-land river systems. By working collaboratively with stakeholders, WftS aims to create a model for improving community climate resiliency, or ability to adapt to extreme climatic conditions.

Visit the project web page: Water for the Seasons



If you would like information about completed studies, please email the NVWSC at GS-W-NVpublic-info@