6.5 earthquake could cut off California’s water supply
CA Department of Water Resources news release
November 2, 2005
Sacramento Appearing before a joint legislative committee, Department of Water Resources (DWR) Director Lester Snow today outlined the catastrophic impact a significant earthquake would have on Delta levees. He said failed levees would cause major floods, threaten public safety, damage the water supply infrastructure, and jeopardize the State’s economy.
“We need to protect Central Valley residents and businesses from the threat of flooding,” said Snow. “But we also need to recognize the Statewide impacts and staggering economic price tag for all Californians if Delta water supplies are reduced or eliminated as a result of a catastrophic failure of our levee system.”
The DWR scenario is based on a 6.5 magnitude earthquake on a fault under the west Delta. Scientific models suggest the quake could produce more than 30 levee breaches on 16 Delta islands. Snow delivered the grim projections to a Joint Hearing of the Natural Resources and Water Subcommittee on Delta Resources, the Transportation and Housing Committee, and the Joint Committee on Emergency Services and Homeland Security.
Levee damage, according to the DWR presentation, would draw salt water into the Delta from San Francisco Bay, shutting down the State Water Project and the Central Valley Project and cutting water deliveries to much of the Bay Area. Major power and gas transmission lines would be damaged, impacting power delivery to the entire State. State highways 4, 12, and 160 would be inundated, creating lengthy detours and jamming other highways and freeways. Environmental damage to the Delta ecosystem could be devastating.
DWR projects that damage to the Delta would take at least 15 months to repair and cause $30-40 billion in economic impacts in the five years following the earthquake. To reduce the risk to public safety and help prevent significant damage to our State’s economy, DWR is recommending major investments in levee maintenance and improvements, greater flood risk education for the public and local agencies, and steps to ensure that upgraded flood management systems accompany new development in flood prone areas. DWR is also helping lead a comprehensive study entitled “The Delta Risk Management Strategy,” a two-year effort to better understand risks to the Delta and develop risk reduction strategies.
In January, Governor Schwarzenegger released a flood management report to the Legislature. Earlier this year, he increased the State’s general fund flood management budget by 70% for levee maintenance and flood emergency response. The Governor also signed two bills that represent small steps to improve Sacramento-San Joaquin Delta flood control efforts. Assembly Bill 1200 (Laird) directs DWR and the Department of Fish and Game to study island subsidence, floods, earthquakes and other issues affecting the Delta. Senate Bill 264 (Machado) extends the Delta Flood Protection Fund for two years.
The DWR presentation is available at:
or by calling (916) 653-6192.