Department of Water Resources Home

Annual Land & Water Use Estimates


Division of Statewide Integrated Water Management

Water Use and Efficiency

901 P Street
Sacramento, CA

Mailing Address:
P.O. Box 942836
Sacramento, CA 94236

  • Agricultural Land & Water Use - The Department of Water Resources estimates irrigated crop acreages, crop evapotranspiration (ETc), evapotranspiration of applied water (ETAW), effective precipitation (EP) and applied water (AW) for 20 crop categories for each year for sub-watershed areas within each county called County/Detailed Analysis Units. The factors which are used to make these estimates include reference evapotranspiration (ETo) or evaporation pan data (Ep), crop development over time (crop coefficients), soil characteristics, rooting depths, and the quantity and timing of precipitation. Our estimates of the quantities of irrigation water applied to these crops reflect not only irrigation efficiencies but also the water required for cultural practices such as the ponding of water in rice fields or the leaching of accumulated salts from the soil. < Download Data >
  • Study Area Maps - The Department of Water Resources subdivides California into study areas for planning purposes. The largest study areas are the ten hydrologic regions (HR), corresponding to the State's major drainage basins. The next level of delineation is the planning area (PA), which in turn is composed of multiple detailed analysis units (DAU). The DAUs are often split by county, so the smallest study area used by the Department is the DAU/county. Many planning studies begin at the DAU or PA level, and the results are aggregated into hydrologic regions for presentation.

    To download the map images below, right click on the hyperlink and select "Save Target As...".