Once the tunnel is complete, Valley Water will begin retrofitting the dam embankment and spillway.

By John Varela

John Varela

As the drought endures, Valley Water has been making steady progress on work at Anderson Dam. About one year ago, officials broke ground on a project to build a new outlet tunnel next to the dam. Since then, a dedicated crew of staff, contractors and consultants have worked tirelessly on this vital public safety and water supply project.

During the past few months, Valley Water has worked to reinforce the hillside, a necessary step before tunneling begins. To achieve this, Valley Water contractors inserted 244 steel bars into the hillside. Each steel bar is 120 feet long, up to 2-1/4 inches in diameter and weighs about 1,600 pounds. Crews then covered these rows of bars with a 12-inch concrete layer. This work was necessary to reinforce the hill where the tunnel will be drilled into it.

This summer, Valley Water will begin digging a tunnel reaching 24.5 feet in diameter through the reinforced hillside. Completing this work is a significant step in getting Anderson Dam back online as a stronger facility so it can protect public safety and do its original job of storing the most water of all of Santa Clara County’s 10 drinking water reservoirs.

This larger outlet tunnel will increase Valley Water’s ability to release water from the reservoir during an emergency or major storm by five times, increasing to 12 times once the entire retrofit project is complete. This will allow our agency to better manage water levels in the reservoir and protect the community.

Once the tunnel is complete, Valley Water will begin retrofitting the dam embankment and spillway. That project is estimated to start in 2025 and will last about seven years. Once finished, Valley Water will again be able to fill Anderson Reservoir.

In the meantime, we face challenges ahead. While much of the state is contending with the current drought emergency, our situation in Santa Clara County is worsened because Anderson Reservoir will be out of service as we build the new tunnel and dam.

While construction is happening at Anderson Dam during the next 10 years, Valley Water will rely more on water imported from outside the county. However, during droughts, the amount of imported water we receive can be drastically reduced. This makes water conservation more important than ever.

That’s why we’re asking everyone to say yes to saving water. The easiest way to reduce water use is by cutting back on outdoor watering, which is responsible for about 50 percent of residential water use.

Please consider letting your lawn go brown this summer or replacing it with a drought-resistant landscape. Valley Water offers rebates through our Landscape Rebate Program. Residents and businesses can take advantage of our robust conservation programs by visiting watersavings.org.

I want to thank everyone who has taken steps to reduce water use. Please continue your water conservation efforts.

Valley Water’s priority is the health and well-being of our community. Having enough clean water is crucial for our region, particularly as we face this drought. Strengthening Anderson Dam will help us protect our regional water supply, ensure public safety, and provide environmental benefits.

John Varela is the chair pro-tem of the Valley Water Board of Trustees. He represents District 1, which includes the South Valley region. For further information, contact him at [email protected], or visit www.valleywater.org/anderson-dam-project.