Anderson Dam, Reservoir by Morgan Hill Set to Close for Decade-Long Upgrade

MORGAN HILL (KPIX) -- Anderson Reservoir above Morgan Hill is about to close to the public for an upgrade. And while there is clearly a need for it some are shocked by how long it will be off-limits.

In 2009, the earthen Anderson Dam was found to be seismically unsound. So, beginning Oct. 1, the public will no longer be allowed anywhere near the lake as the water level is drawn down to almost nothing.

"As early as January 2021, we could have a very different kind of view of Anderson Reservoir," said John Varela with the Santa Clara Valley Water District. "And it will be that way a long time."

A very long time. Valley Water officials predict the work won't be finished before 2031.

First, they'll dig a new outlet tunnel that will quadruple the amount of water that can be released under control. They couldn't release water fast enough in 2017 so it spilled over, flooding Coyote Creek and parts of San Jose.

Thanks to the lessons learned following the Oroville Dam failure, they are also required to replace the concrete spillway entirely.

When that project is finished they will begin a seismic retrofit, removing soil that could liquefy in a major earthquake. If that happened, it could wipe out part of the city of Morgan Hill.

Brian Le will miss hiking the area for the next decade but his home id directly below the dam.

"Yeah, I get it," Le said, "They need to drain the dam because, in case an earthquake happens, it'll flood the area and my house will get destroyed. So, I understand that."

There will be no fishing, boating or hiking in fact the public won't be allowed in at all because of all the heavy equipment deployed there. And, while the reasons may be easy to understand, it's still hard to wrap your mind around that timeframe.

"Ten years?" said visitor Kiabet Vivanco. "That's just -- I don't have an idea about that one!"

Currently the reservoir is down to 18 percent of capacity and the place already feels deserted. Someday, the lake will reopen and officials say it will be better and safer than ever. It's just a little hard to picture that right now.

"I just like to imagine people are out there playing," said seven-year-old Malachai Mendoza on his first visit to Anderson Lake. "I just like to imagine stuff."

The upgrades will take a decade to complete.

It only took about a year to build the original dam back in 1950.