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Key Links
Sacramento-San Joaquin Delta Summary: Policies & Principles, October, 2007 (15KB pdf)*
Overview: In Search of a Permanent Solution
As the largest river delta on the West Coast, the Sacramento-San Joaquin Delta spans a watershed that captures more than half of California's surface water. It is where the rivers of the Sierra Nevada meet the tidal influences of San Francisco Bay. Two of every three Californians depend on the Delta as a key water source, from Solano County to the north of the Delta to hundreds of miles southward in San Diego. Millions of acres of farmland in the Central Valley depend on the Delta as well. So do millions of birds that use the estuary for migration patterns, and numerous fish species including salmon and steelhead.
The Delta is as key to the California economy as it is to the environment. But today the Delta struggles to fulfill these vital missions. The Delta environment is struggling under numerous stresses. Non-native species such as Asian clams have taken hold and consume much of a key food supply for other fish. Islands that have been transformed from marshlands to farmlands produce less food for Delta fish as well. Pesticide runoff harms the fisheries. And operations of water pumps can alter flows in the Delta as well.
The pumps of the Central Valley Project and State Water Project (the source for Metropolitan via the California Aqueduct) are in the southern part of the Delta, while most of the water originates from the north, on the Sacramento River. Moving these water supplies through the Delta can create conflicts with natural flow patterns. All told, the mounting stresses have prompted court actions to curtail as much as 25 percent of traditional water supplies.
The Delta is also on borrowed time because of its levee system. Hundreds of miles of substandard levees protect islands that have receded to below the Delta water level. Were the levees to fail, Delta islands would quickly find themselves submerged. Seismologists have grown increasingly concerned about the potential for an earthquake to collapse numerous levees and cause salty water from San Francisco Bay to take hold in the Delta. Were this to happen, the Delta would no longer be a drinkable water supply. Seismologists predict that there is a two-thirds chance in the coming decades that a large enough earthquake to cause such a scenario is likely to happen.
For Metropolitan, the challenges in the Delta mean that in an average rain year, the district can no longer replenish groundwater supplies and set aside reserves for dry years, absent dramatic new conservation by 18 million residents or the purchases of additional supplies.
Efforts are under way to address the many problems of the Delta. In 2006 Governor Arnold Schwarzenegger signed an executive order to establish a “Delta Vision” Blue Ribbon Task Force that would provide comprehensive recommendations for management of the Delta “We must address the health of the delta because our current practices are not sustainable,” he said. Wildlife agencies responsible for regulating the Delta, meanwhile are at work on a Bay-Delta Conservation Plan (BDCP). With the participation of water districts and interested stakeholders, the Conservation Plan is reviewing new and better ways to move water supplies through and around the Delta. The goal is to come up with new habitat and water delivery improvements that can create a more resilient ecosystem and more reliable water supplies.
Seismologists predict that there is a two-thirds chance in the coming decades that an earthquake large enough to cause such a scenario is likely to happen. Floods, particularly floods accompanied by high tides and strong winds, are threats to the levee system as well. As an illustration of the threat, the following link shows video footage of a severe storm event battering the Delta’s Twitchell Island.
Video of storm on levees at Twitchell Island (2.87MB WMV)
Bay Delta Conservation Plan
Public Scoping Meeting Schedule
Delta Vision
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