earthquake illustration
Credit: Illustration by Cecily Mireles

While scientists are still researching connections between water, climate change and seismic activity, the threat of earthquakes looms large in California. Damage to water sources and systems can reverberate from hundreds of miles away.

All it would take to inflict widespread damage on water systems is an earthquake of 6.0 magnitude or greater centered in the “right” place. Quakes of that magnitude can crack pipes, damage storage systems or release natural gas or oil into aquifers. 

Southern California’s reliance on water imported from outside the region puts its supplies at great risk from quakes. Parts of the Los Angeles Aqueduct, the California Aqueduct and the Colorado River Aqueduct — all of which bring water to Los Angeles — traverse the San Andreas Fault. A 7.8-magnitude quake on the fault would put the three aqueducts out of commission, cutting off some of the city’s water deliveries for as long as two years, according to a scenario evaluated by the city. Repairs could stretch out years. Because these aqueducts supply most of Southern California’s water, officials would have little choice but to impose mandatory water reductions.

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