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- 1336 ---- .._-............-._-~--~-- .~~- - HOW MUCH WATER DOES CALIFORNIA USE? . Water is a curious and unique nuid-withoul it Jile on eanh would not exisl as we know it. Water nour- ishes agricuhural produce and live- stock. provides habitat for wildlife. birds and fish. and powers turbines which pro\'ide energy. Industry uses il for cooling and landscapes need it 10 survive. We swim in it, ice skate on it. and wash thmgs with it. And. we drink it. A family of five uses about one acre-foot of water per year for all its domeslic needs. including landscaping and washing cars. (An acre-foot of water is enough to cover an acre of land to a depth of one fOOl, approxi- malely 326.000 gallons.) Additionally, . -~- an estimated 25 acre.feet of waler is needed to grow food for thai family. according to a study done al the University of California, Berkeley. The Califomia Department of Water Resources estimates the state's net water use in 1985 was 3.U mil. lion acre. feet. This is expected to increase to 35.6 million acre-feet by the year 2010. California's population is now 28,OI9.000-by 2010 it will swell to over 36.000,000. California is the nation's leader in agricuhural production, with an esti- mated 9.7 million aCres of land pro- ducing at least 200 commercial crops adding SI5 billion per year to Califor- nia's economy. 75 .'Jillion Acrt'-FI'l'1 An'rage \i-ad\" Runoff For Califc.roia "........ ... ~"......" J~. h_._ ..- ~ ,,",4~___ '. ,..~ ~._ . . .,>~ ,'1'" r"i'-. . ....,. ,.......... HOW MUCH WATER IS AVAILABLE? In a normal year, California receives nearly 200 million acre-feet of precipi- Ution. About 65 percent is lost to evaporation, transpiration by plants and deep percolation. Of the remain. ing 75 million acre-feet of state.....ide runoff, 32 percent flows into rivers and ultimately the ocean; 31 percent (85 percent of the state's developed water supply) is used by agriculture; 29 per- cent is protected under the .....ild and scenic river system or used for Sacramento-San Joaquin Delta fresh water and fISh flow requirements; 2 percent flows into Nevada; and a mere 6 percent is used by cities and industries. This supply is unpredictable because of changes in the weather-runoff has ranged from as liule as 15 million acre-feet in 1967-77 to more than 135 million acre. feet in 1982-83. There is about 250 million acre.feet of accessible water in the Slate's 350 groundwater basins. In some basins, water is being used more rapidly than it is being recharged. About 40 percent of California's Water supply comes from groundwater, but this proponion increa.~s .... hen drought conditions limit available surface waler, such as dutlng 1976-77 and 1987-88. , Normal water storage in California's major reservoirs is about 28 million acre.feet. But the seasonal distribution of precipitation makes getting the water into the reservoirs tricky, The greatest water needs for agriculture and landscape irrigation occur in the dry! summer months. But most rainfall occurs from October through April- flood season. Many of the Stale's water supply reservoirs function abo as flood control reservoirs, and .....aler managers face a )'earl)' dilemma. Enough storage must be reserved for fl~ control, should it be needed, but once the need for flood cOOlrol ends, runoff mUSI be captured in the reservoirs for use in California's long, dry summers.