Valley Water officials shared progress updates and timeline revisions for the Anderson Dam Seismic Retrofit Project during a community meeting Feb. 20, announcing the release of the final Environmental Impact Report for the project, as well as giving a general update on the project timeline.
“We’ll break ground in early 2027 and work through the construction phase,” Ryan McCarter, Deputy Operating Officer for Valley Water’s Dam Safety and Capital Delivery division, said at the meeting at the Morgan Hill Community & Cultural Center. “The safety of this dam is very crucial for your area.”
The project has completed significant preliminary work with their progress on the new bypass tunnel, which must be finished before the main construction phase can start. According to officials, the timeline shift from the original 2026 start date was necessary to coordinate state and federal environmental compliance processes.
“In order to combine those processes, it bumped our schedule out where we couldn’t get enough work done in 2026,” said Wendy Young, Environmental Services Manager. “The original timeline that we had depended on everything going perfect and a whole bunch of documents being approved very quickly. This refined schedule is still aggressive, but gives us the time to go through the process more efficiently and make sure that we’re checking all the boxes that we need to in the best way that we can.”
The project underwent significant restructuring in 2020 following a federal order, which added several additional compliance projects to the scope of the ADSRP.
“In 2020 we had a major shift in our work, when we had that FERC order come in five years ago, which broke out all of these additional compliance projects,” McCarter said. “That’s when we pulled the Anderson Dam Tunnel project out of the dam project and made it its own project, which came with a lot of challenges.”
The construction timeline stretches over six years largely due to seasonal constraints.
“The reason this project takes six-plus years to complete is because there is only so much work we can do in a single year, as we can’t work through the winter,” McCarter explained. “So we have to divert all the rain flows that come in each winter while we have an interim dam in place.”
The tunnel itself incorporates innovative engineering features such as articulated segments, 10-foot-long sections of the reinforced concrete lining that can move independently of one another.
“This is a really novel idea being used here to protect the tunnel in the case of a seismic offset,” McCarter said. “If there was a seismic event that shifted the ground and impacted the tunnel, the segments can kind of move like sliced bread as the ground moves around it. It’s a really good way to protect the tunnel for seismic resiliency.”
Valley Water officials emphasized that construction impacts to surrounding communities would be minimized.
“We will keep all of the work, as much as possible, inside the reservoir area and not out in the greater Morgan Hill area down below the dam,” McCarter assured residents.
The material excavated from the dam will be stored in stockpile areas within the reservoir itself. This approach means that minimal material will need to be transported away from the construction site by way of nearby neighborhood roads, addressing potential traffic concerns.
Environmental considerations remain central to the project. Young detailed multiple conservation measures, including restoration of Coyote Creek habitat.
“The conservation measures include the maintenance of the Live Oak Restoration Reach, that’s the south channel of Coyote Creek right downstream of the dam,” she explained. “There’s maintenance of the north channel reach—that’s where the outlet structure will be that comes from the tunnel. Both of those will be monitored throughout the construction of the dam to ensure they are able to continue to provide adequate capacity as we’re doing construction activities.”
A major ecological restoration component involves restoring a six-mile segment of Coyote Creek back to its original course in an effort to improve habitat for steelhead trout, as well as other species.
“In 1997, Coyote Creek jumped out of its historic alignment and went into mining ponds, so we’re going to pull the creek back out of those mining ponds,” Young said. “There’s a lot of invasive species, temperature issues and fish passage issues there. Restoring that restores six miles of habitat for fish but also other species because it will include an enhanced riparian corridor.”
The Final EIR addresses several public concerns through eight “master responses” to frequently raised issues. These include alternative designs for Ogier Ponds, steelhead impacts, Valley Habitat Plan integration, Rosendin Park access during construction, feral pig management, wildfire risks and a health risk assessment for Holiday Lakes Estates residents.
“Rosendin Park is really close to Anderson Dam, and different parts of Rosendin have to be closed during construction, especially during our blasting activities,” Young said. “Initially with our EIR we had a much more conservative estimate, but now we are a lot more clear.
“There are only parts of the park that need to be closed in years four through six, and that narrowed-down timeframe for closing different parts of the park is explained in that master response.”
Valley Water has also partnered with the USDA on a five-year program to manage the regional feral pig population, with implementation near Anderson Reservoir beginning soon.
The Final Environmental Impact Report has been released and is scheduled for certification and project approval at the Valley Water board meeting Feb. 25. The Final EIR can be found on Valley Water’s website at www.valleywater.org/public-review-documents.
