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"'-.;,.....~ fil'a c:IIl!;I -'-'9l__ ~._~ ill ~ ---~=::. ::: =- ~ c c:::::::! l:::I i:::I .;::; ... 80 c~ ~ ~ ... ;;;:~ --",,- ..... .f"" .. . .......~ ~ Aerial view of the Della, a I1lafHl1ade collection of waterways and reclaimed islands that serves as a \'Ilal em'ironment forfish and wildlife and the switching yard for the CVP and SWP {Jumps. 16 .(~~.... "'- ,)/ ~ :.;..~ ~ .... .. - ~-- .- ~ 'II ... .~ ,.. "",.,.,.::0 "~", ..,:---::~ iT "j!,,'fiI ';'.~='t' ,.., .'", ~ .~ ...- . ~ .~ 'i;J. ... ~ d. ..........-. ..g Probably the single most important aspect of California's complicated water picture is the Sacramento-San Joaquin Delta. The Delta is located south of Sacramento at the confluence of California's two greatest rivers, the Sacramento River flowing from the north and the San Joaquin River flowing from the south. The Delta has 57 major reclaimed islands. Today it is the most modified estuary on the west coast of North America. Before the Delta was extensively altered by human actiVity it was an immense wetlands that supported an abundant array of birds, tish and wildlife. One early explorer described the area as "nothing more than a wide and extended lawn, exuberant in wild oats and a place tor wild beasts to lie down in - the deer. antelope and noble elk... The wild geese. and every species of waterfowl darkened the surface of every bay and firth." About 42 percent of the state's annual runoff flows through the Delta's maze of channels and sloughs and out to the San Francisco Bay. The Bay-Delta Estuary is a mixing zone of fresh and salt water and its unique environment supports diverse plant, fish and animal life. With construction of the CVP and SWP, the Delta became a critical link in the state's complex water distribution system. Its channels are used to transport water from upstream reservoirs to the south Delta, where state and federal facilities (the Harvey O. Banks Delta Pumping Plant and the Tracy Pumping Plant) pump water into the California Aqueduct and CVP canals. The Delta provides drinking water for two-thirds of the state. The CVP and SWP and local projects also supply about 60 percent of the water used in the San Francisco Bay area. ~ ~ ~-= r:=' ='irl'1!:I ~ The Delta is the state's most important fishery habitat. An estimated 25 percent of all warm water and anadromous sport fish and 80 percent of the state's commercial fishery live or migrate through the Delta. Several at these species - striped bass, chinook salmon and Delta smelt - are in decline because of a combination of factors including water diversions, entrainment in water pumps, poor water quality and the presence of non.native species that compete tor food. Measures to protect the endangered winter~run chinook salmon and the threatened 3-inch Delta smelt, which lives only in the Delta, have impacted water exports - both the volume and timing of diversions. In May 1999, Delta exports were severely curtailed after more than 80.000 juvenile Delta smelt were killed by state and federal pumping facilities. An estimated half-million acre-feet of water that normally would have been consumed by agricultural and urban entities south of the Delta flowed out to sea because of pumping restrictions during the period. The Delta levee system, which turned what was once a marshland into productive farmland, is unstable and in constant need of repair. Numerous studies have shown that their repair and maintenance will cost hundreds of millions of dollars. Since 1980, 17 Delta islands have been partially or completely flooded. In addition. earthquakes pose a potential threat to levee stability. A sound. well-maintained levee system is essential both to the integrity of the islands and protection of the tresh water supply moving through the Delta. In some instances, local efforts to repair and maintain levees have come in conflict with state laws protecting riparian vegeta- tion. To reduce levee failure and minimize the