50% of Santa Clara County’s water comes from the Delta - It’s an issue that deserves attention

The Bay Area is highly dependent upon drinking water that is conveyed through the Sacramento–San Joaquin River Delta.

Without this valuable water source the entire Bay Area would face severe consequences—to our ecosystem, to our water supplies, to our economic stability and to our quality of life.

Water flows through the Delta from sources throughout the Sierra Nevada and Central Valley, and is then conveyed to Bay Area water agencies via the South Bay Aqueduct, San Luis Reservoir, Contra Costa Canal and North Bay Aqueduct. Delta water is also conveyed to the Central Coast, Central Valley and Southern California through other facilities.

Water is the lifeblood of the Bay Area— critical to our families, farms, environment and businesses. It is our responsibility to protect the Bay Area’s water supplies, including those that come from the Delta.

Facts About the Importance of the Delta to Bay Area Residents, Businesses, and Farms

• Fragile Levees and Sinking Islands - Failure of the Delta levees would lead to flooding and seawater intrusion. The central Delta islands are up to 25 feet below sea level, subsiding at a rate of about two inches per year. The levees protecting these islands are old and weak, and are highly vulnerable to catastrophic events such as earthquakes and fl ooding, as well as daily ongoing threats such as animal burrows and wear and tear caused by age.

• Earthquakes and Levee Failure - The Delta lies in close proximity to at least fi ve major faults and it has been estimated that there is a two-in-three probability that the Bay Area will experience a large magnitude earthquake in the next 30 years. A recent state study predicts that a 6.5 magnitude earthquake near the Delta would cause 30 levee breaches resulting in the fl ooding of 16 islands. The infl ux of seawater would make the Delta an unusable drinking water supply for a prolonged period of time. It would likely be three to fi ve years before a signifi cant water supply could be delivered from the Delta.

• Loss of Drought Supply - The loss of the Bay Area’s water supplies due to Delta levee failures would be magnifi ed during a drought. Without Delta conveyance, Bay Area agencies would not be able to access the dry year reserves stored in Central Valley groundwater banks, meaning dry year shortages would be more severe and longer in duration.

• Global Warming and Rising Sea Levels - Scientists estimate that global warming will increase the mean sea level between one and three feet over the next 100 years, placing greater pressure on the levee system and increasing the likelihood and impacts of levee failures. Regional climate changes may also result in an increase in the magnitude and frequency of extreme rainfall events, further stressing the stability of the Delta levee system.

What is at Risk?

• Water supplies for nearly 3 million people could be cut by as much as 50 percent.

• Business development could be hampered by unstable water supplies.

• Local municipalities and park districts could have insuffi cient supplies available to maintain their investments in landscaping.

• Residents and businesses alike could face signifi cant cost increases for scarce water supplies.

What's Next?

In addition to raising public awareness about the Delta’s importance to the Bay Area, Santa Clara Valley Water District, Alameda County Water District and Zone 7 Water Agency are working with other Delta interests to develop a long-term vision to protect Bay Area water supplies and the Delta ecosystem, and to ensure that all alternatives are explored.