Federal regulators are ordering Santa Clara Valley Water District to start draining the entire Anderson Reservoir by October as experts worry that if a major earthquake hits, the dam will fail.
“Anderson lake is more or less on the fault,” said San Jose State University Geology professor Dr. Kimberly Blisniuk.
That Calaveras fault is due for a major quake, and if the dam fails, it would flood the valley down to Monterey Bay and north to San Jose.
Since 2009, the dam’s water level has been kept at a maximum of 74% of capacity because of an assessment that it could fail in a 7.2 quake. On Monday, amid the threat of another drought in California, Anderson Reservoir was just 29% full.
A long-delayed construction project to make the dam seismically safe is set to break ground next year.
“Today, if we were looking for a site to build the dam, then we would definitely not put it here,” said Blisniuk.
Some people living below the dam worry about closing down the popular boating spot for several years but agree with the feds’ assessment.
“I think that it’s time we take care of it,” said Morgan Hill resident Kyra Foley. “If it’s a safety issue then it must be done. Safety is paramount.”
More than 14,000 residents had to be evacuated in 2017 as water from swollen Coyote Creek, downstream of the Anderson Reservoir, flooded homes and temporarily shut down a portion of a freeway.
The water in the reservoir will be used or drained out through Coyote Creek. Valley Water said it won’t lead to flooding.
As for the water we drink, much of it is already imported from the Sacramento River Delta and that will likely increase.
The Associated Press contributed to this report.