California's Anderson Dam Seismic Retrofit Project Moves Forward with Major Construction Contract Awarded

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The Santa Clara Valley Water District has awarded a $1.88 billion contract for the Anderson Dam Seismic Retrofit Project, a crucial infrastructure initiative aimed at enhancing safety and water supply reliability.

After extensive planning, engineering, regulatory reviews, and preliminary construction work, California's Anderson Dam Seismic Retrofit Project is set to advance significantly. The Santa Clara Valley Water District, also known as Valley Water, has awarded a substantial construction contract valued at $1.88 billion to the Flatiron Dragados Sukut ADSRP Joint Venture. This agreement paves the way for the commencement of construction activities in early 2027 on this vital water infrastructure project, which has a total estimated cost of $2.8 billion.
The project has reached a pivotal milestone following the approval from key federal regulators, marking a new chapter in the effort to restore the Anderson Reservoir, the largest in the region, to full operation. The reservoir, located in eastern Santa Clara County, has faced seismic safety concerns for many years. Built in 1950, it is so large that it could contain all nine of Valley Water's other reservoirs within its confines. Due to worries regarding the dam's ability to withstand a significant earthquake, the reservoir has been restricted to only a fraction of its capacity.
With the recent regulatory approvals in place and the supporting infrastructure nearing completion, construction crews are now poised to undertake a comprehensive overhaul of the dam. Valley Water's board chair, Tony Estremera, emphasized the importance of this project, stating, "Rebuilding Anderson Dam is our top priority. This milestone reflects years of hard work, collaboration, and perseverance by our staff, contractors, regulators, and community partners."
The project gained crucial momentum earlier this year when federal regulators granted the necessary approvals. In spring 2026, the Federal Energy Regulatory Commission authorized the retrofit project and the decommissioning of the hydroelectric generating facility that had operated at the site for nearly three decades but ceased operations in 2018. A further significant regulatory milestone was achieved in June when the U.S. Army Corps of Engineers issued a vital water resources permit. These approvals have kept the project on its timeline and have allowed Valley Water to move forward towards construction.
The approved retrofit plan involves reconstructing major portions of the existing dam and spillway to align with modern seismic and safety standards. This comprehensive work will include rebuilding parts of the dam embankment and spillway, installing new outlet pipes, and implementing a series of critical safety upgrades designed to mitigate earthquake risks while enhancing long-term operations.
Once completed, the retrofitted facility will restore the Anderson Reservoir to its normal operating levels. However, the benefits of this project extend beyond just dam safety improvements. Valley Water indicates that the rebuilt facility will enhance water supply reliability, support groundwater recharge, bolster flood protection, and restore recreational opportunities at the reservoir and along the nearby Coyote Creek corridor. For the two million residents who rely on Valley Water's integrated water management system, these improvements are expected to be instrumental in securing future water supplies while safeguarding downstream communities.
Before the main retrofit can commence, several supporting projects mandated by regulators must be completed to ensure safe water flow management during construction. Most of this preparatory work is nearly finished, with the centerpiece being the Anderson Dam Tunnel Project, which is currently in its final stages and anticipated to be completed later this year. This tunnel will replace the existing four-foot-diameter outlet pipe with a significantly larger 13-foot-diameter outlet, which is deemed critical for the success of the overall dam reconstruction effort.
The upgraded tunnel will enable Valley Water to release larger volumes of water into Coyote Creek while the reservoir remains empty throughout the construction phase. Additionally, it will provide enhanced flexibility to manage reservoir levels during future storms and emergency situations. Valley Water aims to have the new tunnel operational before the upcoming winter season to handle any significant rainfall effectively.
This tunnel is one of five supporting projects launched by Valley Water to prepare for the seismic retrofit. Agency officials have confirmed that all five projects are on track for completion prior to the start of the new dam construction, allowing Valley Water to maintain an empty reservoir during the reconstruction period while minimizing impacts on surrounding waterways and communities. The financial commitment for the dam rebuild has been substantial, with Valley Water securing over $114 million in state and federal grants for essential water infrastructure initiatives since 2023. Besides managing the ten dams and surface water reservoirs, Valley Water oversees three water treatment plants, an advanced recycled water purification center, a water quality laboratory, nearly 280 acres of groundwater recharge ponds, and 350 miles of waterways.

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