Developed water is water that is controlled and managed for a variety of uses. These uses include water stored in dams and reservoirs, or pumped, diverted or channeled in aqueducts.

In a normal precipitation year, about half of California’s available surface water is collected in over 1,300 local, state and federal reservoirs and becomes developed water. As part of this, the federal Central Valley Project annually delivers about 20 percent of the state’s developed water. The water is used to irrigate crops and for other purposes.

The remaining water tapped to become developed water stems from the State Water Project, the Colorado River (for use in Southern California), and a number of rivers and streams in the Sierra Nevada mountains. This water is developed by local entities such as San Francisco, Los Angeles, and local water districts including the Modesto Irrigation District and the Yolo County Water Agency.