Valley Water project in rebuilding Anderson Dam reaches milestone

Workers carve out rock to build an outlet tunnel for the new Anderson Dam. Photo courtesy Valley Water.


Click HERE to see video of tunnel construction explosion

By Staff Report

Valley Water recently reached a milestone in its work to rebuild Anderson Dam so it can protect public safety and serve as Santa Clara County’s largest drinking water reservoir. The agency is also making steady progress in its effort to construct a new, larger outlet tunnel next to the earthquake-vulnerable dam.

– Workers are halfway through digging a new 1,740-foot outlet tunnel at Anderson Dam as part of a $1.4 billion project.

– The tunnel will allow faster water release from the reservoir in emergencies like earthquakes or major storms.

– This is part of a federal project to tear down and rebuild the 240-foot earthen dam to modern seismic safety standards due to earthquake risks.

– Workers have dug 830 feet of the tunnel so far using excavators, rock-cutting machines, and explosives through sandstone and other bedrock.

– They are progressing 5-10 feet per day and expect to remove 30,000 cubic yards of rock and dirt total. The tunnel is scheduled for completion in late 2024.

– After the tunnel is done, the dam will be torn down and a new seismically sound dam and spillway constructed by 2032.

– Dam failures can have catastrophic consequences, as seen in the recent collapse of two poorly maintained dams in Libya that killed over 5,000 people.

– Valley Water released a draft environment report on the Anderson Dam rebuild and will hold a public meeting for input. It will be held at the Morgan Hill Community Center at 6:30 p.m. Monday Oct. 2. 

— To view the report, click HERE.