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Lenihan Dam Outlet Modification

Lenihan tunnel work

The Santa Clara Valley Water District's Outlet Modification Project replaced an aging outlet pipe under Lenihan Dam that had suffered repeated partial collapses and required patchwork repairs over several years.

The modified outlet consists of a 54 inch concrete lined steel pipe located inside of an approximately 2,000 foot long maintenance tunnel that runs through the eastern abutment of Lenihan Dam in St. Joseph’s Hill.

The project also included a sloping, multi-port intake structure and a shaft located in Lexington Reservoir and an outlet structure located adjacent to Los Gatos Creek.

With a total project cost of approximately $50 million, the Lenihan Dam Outlet Modifications Project received the Project of the Year award in the “Large Projects” category from the San Francisco Section of the American Society of Civil Engineers.

The project was completed safely, under budget and on schedule.

On Oct. 20, 2009, the water district held a dedication ceremony and “first release” celebration at the site with the district’s board of directors and dignitaries from Division of Safety of Dams and the town of Los Gatos attending and taking part in tours of the completed tunnel. Students from the nearby Lexington School opened the ceremony with an educational presentation about the project, which Chief Executive Officer Beau Goldie called a "shining example" of the district's commitment to dam safety.   

Project contact: Senior Project Manager Donna Collins, ext. 2572