When I think about Anderson Dam, I think about what it means for the people of Santa Clara County. It is not just a structure holding water, it is a lifeline for our families, businesses, farms and our future. That’s why the seismic retrofit of Anderson Dam is Valley Water’s top priority.
One of the most exciting improvements is the addition of a labyrinth weir. This may sound technical, but the idea is simple: a zigzag-shaped wall that helps water flow more safely and efficiently from the reservoir into the North Channel of Coyote Creek. By folding the weir into a zigzag pattern, engineers increase its length without widening the creek.
This allows more water to pass at lower levels, which reduces erosion, improves habitat and most importantly, helps protect nearby communities during major storms. In short, this new weir will make Anderson Reservoir safer and more resilient for decades to come.
Our progress has been steady. Since construction on the Anderson Dam Tunnel Project began in June 2022, we’ve reached several major milestones. In September 2024, crews completed excavation of a 1,736-foot-long tunnel, which will allow us to release larger volumes of water quickly in an emergency.
We’ve also released updated environmental reports—an essential step in securing the permits that allow us to move forward with construction of the larger seismic retrofit project.
But like any large infrastructure project, we have faced challenges. Earlier this year, the Federal Energy Regulatory Commission set a new schedule for a required environmental document. This means the reconstruction of the dam will begin in January 2027 instead of April 2026. While the delay is disappointing, it’s also a reminder that safety must come first. The work at the base of the dam can only be done during dry months, and we cannot rush something this important.
We know delays come with costs. Inflation tied to the new schedule is expected to add about $100 million to the project. This is not unusual for projects of this size, but Valley Water is working hard to offset those costs by pursuing grant funding and exploring more cost-effective technical solutions with our partners.
I’m encouraged by our progress, and the safety improvements are vital to the project and worthy of the investment. Once completed, Anderson Reservoir will be able to store nearly 90,000 acre-feet of water—enough to supply almost 1 million people for a year.
This project will help ensure public safety, protect our regional water supply and provide environmental benefits for generations to come.
Valley Water Director John L. Varela represents District 1 on the local water district’s board of directors.
