Anderson Dam

Inside the Anderson Dam Reconstruction Project in South Bay

For the first time since construction finally began at the Anderson Dam last month, NBC Bay Area got a close look at how the project is going.

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The Santa Clara Valley Water District shut down its largest reservoir, Anderson Dam in 2020 as the state was slipping into a deepening drought.

Anderson Dam is in Morgan Hill and was built in 1950, which was part of the problem. Anderson also did not meet state seismic safety standards and needed a major retrofit.

In 2009, the state reported the old dam could break during a major earthquake and flood the valley.

After years of studies and wrangling over regulations, Anderson was drained to 3% capacity.

Then, last month, the actual retrofit began.

For the first time since construction began, NBC Bay Area had a up and close look at how the project is going.

“This is stage one of the Anderson Dam Retrofit Project. What we’re doing here is building a tunnel that goes beneath the dam on the right side here. And what that will do is allow us to get the rest of the water out of the reservoir currently, and also act as a diversion during the dam construction,” said SCVWD Dam Safety Officer Ryan McCarter.

At ground level, there's a wide, gaping tunnel, which will ultimately span 1,700 feet and can house something much bigger than the current four-foot pipe.

“And in the end, we will have a 13-foot diameter pipe there, with much larger capability of releasing flows during any emergency event that may come up,” McCarter said.

Water officials said the $1 billion-plus project is necessary for future planning.

“Well, it’s extremely critical. Our Valley is growing. We have more people coming in. You see more houses going up throughout the Valley. And, so water supply is of immense importance to everybody,” said John Varela, SCVWD Board President.

It will be about two years before the part of the project is finished and then, it will be another eight years before the overall Anderson retrofit project is complete.

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