As California works to improve its official accounting of water for a range of purposes, one major area lacking widely accepted quantification is the consumptive use of water for agriculture, particularly evapotranspiration (ET) from crops.  In the Sacramento-San Joaquin Delta, such estimates are important, along with other hydrologic flows, for a variety of water rights, operational, and regulatory purposes. Consumptive use is the proportion of water removed that cannot be reused elsewhere in a basin. For crops in the Sacramento-San Joaquin Delta, this is mostly evapotranspiration.