Amrith Srinath Gunasekara

Data for water distribution by the urban sector, environment, and agriculture across the world is not readily available, publicly accessible, or quantitatively evaluated. It is critical for any society to define and transparently account for regional water distribution in a state or country to facilitate accurate information sharing with the public. Water use in California has been criticized for the past two decades, especially during the historic 2012-2016 drought, with agriculture labeled as the largest water user. Various media sources state that California agriculture uses 80% of the region's water. This study, using publicly available data, reveals that agricultural water use in California constitutes only 12% of the total water the state receives in a wet year,  a year in which the precipitation exceeded the historic average total precipitation.  In a dry year, with precipitation less than that of the historical average total precipitation, agriculture water use is only 29% of total water. Agriculture water use in California was found to be four times that of the urban/domestic sector. Additionally, the study shows that the environment, not agriculture, receives 80% or more of all the water that arrives in the state. Continued and increased water allocations and increased storage for agriculture could be facilitated and should be considered since California leads the nation in food production and plays a fundamental role in regional and global food security. Other states and regions must work to quantify their total precipitation and water distribution to the different sectors to realize the value of water for food production and security.