MORGAN HILL (KCBS) – Concerns over the ability of the Anderson Dam to withstand a major quake has forced officials to open an outlet pipe, dumping thousands of gallons of fresh water into the Coyote Creeks and out into the San Francisco Bay.
Santa Clara Valley Water District Board of Directors Chair John Varela sent out a public letter Thursday, informing local residents that Anderson Reservoir was on the verge of reaching its full capacity due to recent and coming storms.
In a region once ravaged by a severe drought, the announcement would seem to be good news. The problem is that the Anderson Dam needs to be retrofitted for seismic safety.
The state Division of the Safety of Dams, the agency that oversees the safety of California’s dams, has had a restriction in place since 2009 that limits the Anderson Dam to 68 percent of its capacity.
Currently, the dam is at 90 percent.
“What would happen if a massive quake did occur?” Varela said in his public letter. “There’s a chance that the dam could be damaged, but the chance of immediate dam failure is exceedingly remote.”
“It is possible that we would have several days or weeks to reduce the water level with emergency pumps before any further damage could compromise the integrity of the dam.”
According to the Morgan Hill Times, the water district state officials have warned residents that if a 7.25 magnitude earthquake were to hit near the dam, it could at least partially collapse.
A wall of water up to 35 feet high could be released depending on the level of collapse, potentially flooding Morgan Hill, Gilroy and San Martin.
The district has a seismic retrofit project set to begin in 2020. The retrofit will take four years to complete.