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California Water Today 77 Water Sources: Local,Imported, Mined,and Reused California supplements water supplies available from in-state precipitation with imports from other states, groundwater mining, and some recovery of wastewater and brackish water following intensive treatment. In addition, available water supplies exceed the amounts flowing into the state because of natural reuse, as excess irrigation water (the amount not consumed by crops) and treated urban wastewater become available for use by others after being returned to streams(Box 2.1). Figure 2.4 shows the relative importance of these sources in total usable sup- plies for agricultural,environmental,and urban uses.Overall,more than 80 per- cent of the initial total(before reuse)is derived from local and out-of-state streams: Three-quarters of these surface flows are from local projects and diversions and roughly one-quarter are from the state and federal projects.About 18 per- cent of the initial total is supplied by groundwater. Natural reuse constitutes roughly one-quarter of gross supplies(almost half of all groundwater pumping Figure 2.4 California employs a diverse portfolio of water sources for agricultural, environmental,and urban water uses Groundwater recharge (8%) Recycled water Net groundwater (0.3%) withdrawal (10%) Reused Local surface surface water water deliveries (17%) (45%) SWP deliveries (3%) Other )Localmported federal CVP Colorado deliveries deliveries deliveries River 0%) (1%) (9%) deliveries (6%) SOURCE:California Department of Water Resources(2009). NOTES:The figure shows sources ofgross water supplies,1998-2005 average.Total water supply is 83 maf per year.Total does not sum to 100 percent because of rounding.SWP=State Water Project. CVP=Central Valley Project.