The Sacramento-San Joaquin Delta is a regional, state and national treasure.

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.

The Sacramento–San Joaquin Delta, created by the confluence of those two major California rivers, is a vitally important ecosystem that also connects directly to San Francisco Bay.  Fresh water reaching the Delta is the core of California’s water system, which conveys at least a portion of the water supply needs for two-thirds of all Californians – about 25 million people. Delta-conveyed water supports farms and ranches from the north Delta to the Mexican border, which are a source of financial stability for the state and which produce roughly half of the nation’s domestically grown fresh produce.

In addition, 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.

The Delta’s Decline

However, 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. 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.

One of the best-known issues related to these challenges is the plight of the Delta smelt, a small fish having a big impact on Delta management. In 2007, a California judge protected the endangered Delta smelt by curtailing water export deliveries from the Delta.

It is for these reasons that California agencies, interests, and the legislature have created the CALFED Bay Delta Program, the Delta Stewardship Council, and the Bay Delta Conservation Plan.