California Water Briefing APRIL 2006 Department of Water Resources

Overview Most populous state in U.S. – represents about 12% of national population Estimated 2005 population of 37 million Projected 2020 population of 44 million Top agricultural production state in the nation for more than 50 years. About 9 million acres of irrigated cropland

Physical Setting Majority of population is located within 100 miles from the Pacific Ocean, from the San Francisco Bay Area south to the Mexican border The Central Valley represents about 80% of the irrigated agricultural acreage Largely Mediterranean- type climate

Economic Setting 8 TH largest economy in the world 2004 Gross State Product (GSP) of $1.6 trillion Percentage contribution to GSP by economic sector shown at right

Hydrology Overview Average annual runoff from precipitation falling on California is 71 MAF Average annual surface water supplies are the 71 MAF of in-state runoff plus 7 MAF from flows in interstate rivers, for a total of 78 MAF More than 70% of the surface runoff occurs in Northern California, while more than 70% of the needs for water occur in Southern California

Importance of Sierra Snowpack Sierra Nevada runoff supplies – directly or indirectly (through groundwater recharge) a majority of California’s urban and agricultural water needs Relies on complicated system of operating Sierran reservoirs to provide both water storage and flood control capacity

Mean Annual Precipitation in California, 1961 to 1990

Distribution of Average Annual Precipitation and Runoff

Groundwater Statewide, in an average year groundwater supplies about 30% of urban and agricultural water uses. There are 431 delineated groundwater basins in California

Agricultural and Urban Demand Supplied by Groundwater in Each Hydrologic Region

Groundwater Basins and Subbasins