Water Use Estimates
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 each year. Data are estimated from 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. Applied water (AW) estimates reflect irrigation efficiencies as well as the water required for cultural practices such as the ponding of water in rice fields or the leaching of accumulated salts from the soil.
Data compiled by study area and year are available for download in spreadsheet (xls) format.
To Download Data: Expand the menu under Statewide, County, Hydrologic Region (HR), or Detailed Analysis Unit (DAU), click on a year and select "Save As...".
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 are the Planning Areas (PA), which in turn are composed of multiple Detailed Analysis Units (DAU). The DAUs are often split by county boundaries, 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.