Anderson Reservoir Is So Full Of Water That It's Seismically Unsafe

MORGAN HILL (KPIX 5) -- South Bay water officials are urgently trying to lower a reservoir to reduce pressure on a shaky dam.

The Anderson Reservoir in Morgan Hill is just a couple of miles east of U.S. Highway 101.

The dam is especially vulnerable right now if an earthquake happens to strike.

Water gushes from the bottom of the Anderson Dam. The release valve is wide open and crowds are coming to see what looks like a water show.

Sean Barragan, of Morgan Hill, said, "It's pretty awesome. It's not a thing you see every day."

But it's not just for show.

The water district is trying to quickly lower the level of the reservoir, because it's not seismically safe to be as full as it is now.

A 2009 study found a large earthquake next to the dam could cause a failure.

Since then state regulators placed a cap on the dam at 68 percent of capacity.

But the recent rains have boosted the level to 91 percent of capacity.

In the drought it was never an issue, but it is now.

Marty Grimes, with the Santa Clara Valley Water District said, "It's a very remote possibility that we would have an earthquake of such a magnitude that close to the reservoir. That's what we're hoping against. That's what we're planning for and that's why we have a project to rehabilitate the reservoir."

Monitors have been placed around the dam to monitor any movement. But retrofitting the dam is still years away.

Morgan Hill residents have been marveling about how quickly water levels rose, but they worry about a quake and what could happen.

Neighbor Janey Pedrizetti said, "They say that Morgan Hill will be under two feet of water. So let's hope that never happens."