Four-Year Study of Searsville Dam Completed

The 120-year-old, Stanford-owned Searsville Dam and Reservoir has been the subject of an extensive study focused on establishing a plan for it that both preserves the water supply and enhances local ecology.

Built in 1892, the dam now has upwards of 2.7 million cubic yards of sediment accumulated in its reservoir. Over the course of the four-year study, a steering committee of 12 faculty and staff who specialize in engineering, environmental science, history, and law examined various alternative actions with regard to the dam, sediment, fish passage, water supply/storage, and flood management. The results provide direction for the Searsville team to work collaboratively with the various federal, state, and local agencies to derive a project that best addresses all of these aspects.

The committee made three recommendations. The first is to provide fish passage—primarily for the threatened steelhead—preferably by constructing an opening through the base of the dam that would allow the creek to flow through it. This opening would also serve a storm water detention (check dam) function to reduce peak flow rate downstream. This option is contingent upon the ability to safely flush the accumulated sediment downstream. If this cannot be done, the dam will remain as is and the reservoir will be allowed to fill with sediment, which will then be stabilized; fish passage will be provided by a new stream channel constructed through the sediment and either a fish ladder or a rerouted creek bypass around the dam. The second recommendation is to convey all future incoming sediment past the dam and cease trapping sediment at Searsville. The third is to relocate the water diversion and storage functions to other locations and cease diverting water at Searsville.

The Searsville effort has now moved on to refining the analyses and engineering efforts and collaborating with the various agencies to develop the project’s specific actions.