CALFED Bay-Delta Program heading
  • Governor Brown
  • John Laird, Resources Secretary
  • Joe Grindstaff, CALFED Director

Delta Flood Risk

Delta Flood Risk PhotoFailure of Delta levees could have a devastating effect, not only on the region, but statewide. The quality of the Delta’s water could be severely compromised as salt water rushes in from the Bay to equalize water pressure. Resulting harm to plant and animal species may be devastating. Additionally, the supply of water would be immediately affected as pumps that move Delta water southward to the Central Valley and Southern California, would be shut down to contain the saltwater intrusion.

It has been estimated that the loss to California’s economy could be $30 to $40 billion in the event of massive levee failures caused by a 6.5 magnitude earthquake in the Delta region.

Levee failures have not been uncommon in the Delta. Over the past century, 140 levee failures have been recorded. However, as levees age and subside, while community development increasingly encroaches on the Delta, concern heightens for not only the economic and ecological issues associated with levee failures, but risk to public safety as well.

Learn more about risks associated with Delta levees:


New Video on Levee Failures

Levee FailureThe Department of Water Resources has produced this comprehensive view of the consequences of a major levee break in the Central Valley or Delta.

 view video (13.78 MB)


Twitchell Island Flood Flight

Twitchell Island Flood FightOn New Year’s Day 2006, during a storm that brought strong rains and winds up to 60 mph, Delta levees and state fllood fighters were put to the test throughout the Delta. This video highlights the fight to prevent the central Delta’s Twitchell Island from flooding.

 view video (7.44 MB)


Jones Tract Flooding

Photo of Jones Tract Levee BreakIn the summer of 2004, a levee along the Jones Tract in the southeastern Delta suddenly collapsed without warning, causing the largely agricultural island to flood. Pumping to drain and restore the island was completed at a cost of more than $90 million.

 view video (2.94 MB)