VIDEO: Cracks discovered in spillways at 3 South Bay dams


MORGAN HILL (KRON) -- The near-catastrophe last winter at the failing Oroville Dam spillway shined a light on other dams in California's aging infrastructure.

Cracks have been discovered in the spillways at three dams in the South Bay.

The aging spillways at Anderson Dam in Morgan Hill have come under new scrutiny as a result of a recently completed study that found some worsening structural problems like cracks in the concrete.

Some of the cracks are quite visible, but others not so much. There is no immediate danger, not with the reservoir only a third full right now.

But the area downstream of the dam is densely populated. The problems with the spillway at Anderson are not unlike those that led to the failure of the spillway at the Oroville Dam back in February, leading to the emergency evacuation of tens of thousands of people in harm's way.

"Because of what happened in Oroville Dam, owners throughout the state are taking a much deeper look at their spillways and seeing if we have similar vulnerabilities and it turns out we do have some vulnerabilities that we need to take care of," Santa Clara Valley Water District Spokesman Marty Grimes said.

It isn't just Anderson Dam. The concrete spillways at Guadalupe Dam and Calero Dam in the hills south of San Jose also have extensive cracks that could someday undermine the bedrock beneath, similar to what happened in Oroville.

"It's important to recognize that our spillways performed well," Grimes said. "They performed well last winter, and they aren't used all that often, but we do have an ongoing seismic retrofit program happening which is already addressing some these same issues."

Indeed, the Anderson Dam spillway held up just fine when the reservoir overflowed last winter for the first time in 10 years, but the ensuing flood resulted in $100 million in damages.

Until those major repairs can be done, the cracks are being watched closely as part of an ongoing dam safety and maintenance program.

And until the seismic retrofits and repairs are complete, the three reservoirs will be kept well below capacity out of an abundance of caution.


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