The U.S. Department of Homeland Security’s Office of Cyber and Infrastructure Analysis (DHS-OCIA) released a report assessing the possible impacts of a 7.0 magnitude earthquake on the Hayward Fault. The report outlines possible impacts to water and wastewater infrastructure including delivery of the Hetch Hetchy Aqueduct water specifically. Sunnyvale receives approximately 50 percent of its water from the Hetch Hetchy Reservoir through San Francisco Public Utilities Commission (SFPUC). Hetch Hetchy water is supplied to the area via pipelines that all cross the Hayward Fault. Should these pipelines become inoperable, water deliveries to the area will all but cease for some time. It is not clear if the report takes into account the recent investment by the SFPUC and wholesale customers of $4.6 billion to upgrade the Regional Water System to minimize any impact from a seismic event on the Hayward Fault. Sunnyvale gets its water not only from SFPUC, but from the Santa Clara Valley Water District which also could be vulnerable in an earthquake. The City has seven operating groundwater wells that it could utilize in an emergency. View the DHS-OCIA report here.
