Valley Water has awarded a US$1.88bn construction contract for the Anderson Dam Seismic Retrofit Project, marking the start of the next phase in rebuilding the dam in Santa Clara County, California, US.
The contract was awarded by Valley Water’s Board of Directors on 24 July to the Flatiron Dragados Sukut ADSRP Joint Venture. Construction is scheduled to begin in early 2027 and is expected to take around seven years.
The project involves rebuilding most of the dam and spillway, installing new outlet pipes and completing a series of safety upgrades. Once complete, Anderson Reservoir will be able to return to full operating capacity, improving water supply reliability, supporting groundwater recharge, reducing flood risk and restoring recreation at the reservoir and along the Coyote Creek corridor.
Built in 1950, Anderson Reservoir is the largest of Valley Water’s 10 reservoirs.
“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 Anderson Dam Seismic Retrofit Project has a total estimated cost of approximately US$2.8bn, making it one of the largest infrastructure projects undertaken by Valley Water.
Since 2023, the agency has secured more than US$114m in state and federal grants for critical water infrastructure projects across Santa Clara County. Valley Water said it continues to pursue additional state and federal funding for the Anderson Dam project to help limit the impact on water rates.
The contract award follows several years of planning, engineering, environmental review and regulatory approvals. Valley Water said most of the supporting projects required to prepare the site and meet regulatory requirements have now been completed.
Among these is the Anderson Dam Tunnel Project, which is in its final stages and is expected to be completed later this year. The project replaces the dam’s existing 4ft diameter outlet pipe with a new 13ft diameter outlet tunnel, enabling larger controlled releases into Coyote Creek during construction and improving reservoir management during future storms and emergency events. Valley Water said the new tunnel is expected to be operational this winter.
The agency expects to complete all five supporting projects before construction of the new dam begins, allowing Anderson Reservoir to remain safely empty while the seismic retrofit is carried out.
