New state report card finds some local dams vulnerable

California safety regulators for the first time publicly posted safety ratings for the hundreds of dams under state jurisdiction on Friday, bowing to public pressure for more transparency after the failure of the Oroville Dam spillway in Feburary.

Eight percent of dams under jurisdiction of the Division of Safety of Dams have deficiencies that keep them from being rated satisfactory, which is state’s the highest rating. Eleven of 229 dams in Los Angeles and five surrounding counties show up on the state’s list with a rating of fair or poor.

The largest two of those — Castaic Dam and Lake Perris Dam — were rated “fair” because they are vulnerable to earthquakes, said Erin Mellon, spokeswoman for the Department of Water Resources, which owns the two dams.

“Fair” means the dam can hold the amount of water it was built to hold under normal circumstances, but that it could have problems under stresses like an extra load of water, or an earthquake.

The Perris and Castaic dams are located near populated areas that could be inundated if the dams failed, so they are described as posing extremely high downstream hazards.

Perris Dam near Hemet in Riverside County is undergoing repairs, and its capacity been restricted by the state until the work is finished. The water level was lowered in 2005.

At Castaic Dam, north of Santa Clarita, the outlet towers and bridge could suffer damage in an earthquake, according to a recently-completed structural analysis by DWR.

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