The Sacramento-San Joaquin Delta is a regional, state and national treasure that supplies the drinking water of about 25 million Californians.
More than 515,000 people in dozens of communities call the Delta home. It is also home to more than 750 animal and plant species, some of them threatened or endangered. It supports California’s $27 billion agricultural industry with an average annual gross value of more than $500 million in corn, grain, hay, sugar beets, alfalfa, pasture, tomatoes, asparagus, safflower, a range of fruits and more. More than 1,800 agricultural users draw water from the Delta.
It is also the hub of state, federal and local water systems that provide at least a portion of the water supply needs for two-thirds of all Californians. Diversions directly from the Delta include the State Water Project, the federal Central Valley Project, the Contra Costa Canal, the North Bay Aqueduct, the City of Vallejo and the Western Delta Industry.
The Delta is also a world-class recreational destination, attracting about 12 million visitors per year, who take advantage of its 290 shoreline recreational areas, 300 marinas, 57,000 navigable waterways and more than 20 species of sport fish.
But for all its significant attributes, the Delta also faces significant challenges. Over several decades, the competing demands for the Delta to provide both habitat and water supply have impaired the Delta’s ability to meet either need. The needs of the ecosystem and water users particularly clash during dry years, when there is simply less water to go around.
Many factors have contributed to the Delta’s decline. Agricultural, industrial and urban runoff has polluted its waters. Invasive, non-native species have adversely impacted the food chain and, as a result, native fish and wildlife populations suffer.
Gradual changes, such as sea level rise, rising water temperatures due to climate change, or additional invasions of exotic species, could also transform the current ecosystem in ways that are difficult to anticipate or manage. Some climate change projections indicate a likelihood of more frequent and intense storms. These conditions, combined with the aging levees, increase the risk of levee failure. Massive levee failures could be difficult to repair and cause saltwater intrusion into the Delta that could only be reversed over a long period of time using high volumes of fresh water from upstream reservoirs or storms. Increased salinity would substantially degrade the Delta aquatic habitat, Delta water supplies, Delta agriculture and recreation.