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California Water Science Center

California Water Use


The U.S. Geological Survey's National Water-Use Information Program compiles the nation's water-use data at the county, state, and national levels. USGS five-year reports on national and state water-use estimates between 1950-2010 are posted on the web at: USGS water-use data for states and counties for 1985-2010 are available at:

As part of the USGS National Water Use Compilation, the California Water Science Center works in cooperation with local, State, and Federal agencies as well as academic and private organizations to collect and report total water withdrawals for California.

The 2010 California water use data are aggregated here, in this website, for the first time. The California Water Science Center released these data ahead of the online USGS National Water Use Compilation circular report, in response to increased interest associated with current drought conditions. The national report was released in November of 2014. The data on this website represents the most current California water use data available in the USGS National Water Use Compilation. It contains a section on water use in California for 2010.

Water-use estimates are compiled by withdrawal source type, use category, and county.

  • Withdrawal source types include groundwater, both fresh and saline,
  • and surface water, both fresh and saline;
  • Eight water-use categories include thermoelectric, public, domestic, livestock, mining, industrial, irrigation, and aquaculture.

For California, population data used to estimate public water-supply use comes from Urban Water Management Plans, California Department of Water Resources, California Department of Public Health, and U.S. Environmental Protection Agency data. Population data used to estimate domestic, self-supplied water use came from the difference between the Census population and the public-supply population.

The terms and units used in this report are similar to those used in previous USGS National Water-Use Reports and are defined in the Glossary. Water-use data are expressed in units of gallons per day.

Withdrawal estimates for each category represent the total amount of water removed from the water source, regardless of how much of that total is consumptively used. In most cases, some fraction of the total withdrawal will be returned to the same or a different water source after use and is available for other withdrawals.

The California water-use summary presented here is based on estimates compiled from a variety of sources. There is significant uncertainty associated with many of these estimates.

Withdrawals for crop irrigation are among the least accurate of the estimates because withdrawals are generally not measured directly, and must be calculated based on crop acreage, crop coefficients, stage ratios, irrigation-system efficiency, and precipitation. Data on withdrawals for public supply are more accurate because those estimates are based primarily on site-specific information. Powerplant water use and mining information are considered the most accurate data.


The authors gratefully acknowledge the assistance provided by the many State and local agencies that shared data and expertise with the USGS. Cooperators include State agencies that manage water resources, operate data-collection programs, and administer regulations on water use and natural resources.

For More Information...

Justin Brandt
Geophysicist, California Water Science Center, 916-278-3159

Or visit the USGS water-use website at:

The recommended citation for this web page is:
Water Use in California, 2014, Brandt, Justin; Sneed, Michelle; Rogers, Laurel Lynn; Metzger, Loren F.; Diane Rewis; House, Sally
USGS Data Website, doi:10.5066/F7KD1VXV

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