Los Angeles water supply impacts from a M7.8 San Andreas Fault earthquake scenario

The City of Los Angeles, as well as the entire Southern California population of over 22 million people, is highly dependent on water imported through the Los Angeles, California and Colorado River Aqueducts. The San Andreas Fault poses one of the greatest risks to these critical water supply lines; all three aqueducts cross the San Andreas Fault. A preliminary review of potential damage to these three major aqueducts in response to a magnitude 7.8 earthquake scenario on the San Andreas Fault was performed. The results indicate repairs to restore flow into each aqueduct may take a year or more. Local storage is estimated to last approximately 6 months with significant rationing. As a result, there may be inadequate storage to supply the local population during the length of time it takes to repair the aqueducts. Inadequate water storage has significant health, safety and economic impacts on the Southern California region. This investigation identifies the need for a more thorough evaluation of aqueduct restoration times. In addition, mitigation measures for additional local storage and more rapid aqueduct restoration must be implemented.