Valley Water reaches major milestone in rebuilding Anderson Dam

July 28, 2026

Valley Water reached a major milestone on July 24, 2026, when its Board of Directors awarded the construction contract for the Anderson Dam Seismic Retrofit Project. The decision comes after years of project development and marks the start of the next chapter in rebuilding Anderson Dam.

In early 2027, crews will begin construction at the dam. They will rebuild most of the dam and spillway, install new outlet pipes, and complete other major safety upgrades. When the work is finished, Anderson Reservoir can return to its full operating capacity. The project will improve water supply reliability, support groundwater recharge, reduce flood risk, and restore recreation at Anderson Reservoir and along the Coyote Creek corridor.

Built in 1950, Anderson Reservoir is the largest of Valley Water's 10 reservoirs. It is so large that all nine of the agency's other reservoirs could fit inside it.

“Rebuilding Anderson Dam is our top priority,” said Valley Water Board Chair Tony Estremera. “This milestone reflects years of hard work, collaboration, and perseverance by our staff, contractors, regulators, and community partners. Today marks the next phase of one of Santa Clara County's most important water infrastructure projects that will benefit our community for generations to come.”

The board awarded the $1.88 billion construction contract to Flatiron Dragados Sukut ADSRP Joint Venture. At a total cost of about $2.8 billion, the Anderson Dam Seismic Retrofit Project is one of the largest and most complex infrastructure projects in Valley Water's history. Construction is expected to take about seven years.

Since 2023, the agency has received more than $114 million in state and federal grants for critical water infrastructure projects in Santa Clara County. Valley Water is working to secure both state and federal funding for the Anderson Dam Seismic Retrofit Project to help keep water rates as affordable as possible.

The contract award follows years of planning, engineering, environmental review, and regulatory approvals for the seismic retrofit project. Most of the precursor projects to meet regulatory requirements, help manage flows in Coyote Creek and prepare the site for rebuilding Anderson Dam have been completed.

The centerpiece of that effort is the Anderson Dam Tunnel Project, now in its final stages and on track to be completed later this year. The new tunnel replaces the dam's existing 4-foot-diameter outlet pipe with a new 13-foot-diameter outlet. This larger tunnel will allow Valley Water to release larger flows into Coyote Creek during construction and better manage reservoir levels during future storms and emergencies. The new tunnel will be functional this winter and could be used if our region experiences significant rain events.

Valley Water is on track to complete all five of the supporting projects before construction on the new dam begins. Together, these projects will allow Valley Water to reduce impacts and safely keep Anderson Reservoir empty while the new dam is under construction.

Valley Water manages an integrated water resources system that includes the supply of clean, safe water, flood protection and stewardship of streams on behalf of Santa Clara County's 2 million residents. Valley Water effectively manages 10 dams and surface water reservoirs, three water treatment plants, an advanced recycled water purification center, a state-of-the-art water quality laboratory, nearly 280 acres of groundwater recharge ponds and 350 miles of waterways. We provide wholesale water and groundwater management services to local municipalities and private water retailers who deliver drinking water directly to homes and businesses in Santa Clara County.