Valley Water sends first water through new Anderson Dam tunnel, clearing way for $1.88 billion rebuild
About 4 million gallons flowed into Coyote Creek Oct. 30. The tunnel helps hold the reservoir near 3% through the rainy season.
Valley Water sent water from Anderson Reservoir through its new 1,736-foot tunnel for the first time Oct. 30, the agency said in a Nov. 9 news release. About 4 million gallons, enough to fill about six Olympic pools, flowed into Coyote Creek near Morgan Hill.
The reservoir has been held near 3% of its capacity since December 2020 because of earthquake risk under a federal dam-safety order, the project page shows. Valley Water will use the tunnel to keep it there during construction, which the agency says matters more if a strong El Niño brings heavy rain this winter.
Board Chair Tony Estremera called the release “a big moment and a major milestone for Valley Water and our community.”
The test clears the way to rebuild the dam. Valley Water awarded the $1.88 billion construction contract to the Flatiron Dragados Sukut ADSRP Joint Venture in July. Haul roads, temporary bridges and more tunneling come in 2027. Crews rebuild the dam and spillway from 2028 through 2032, with site restoration through 2033. Anderson will then again be the county's largest reservoir at full capacity. The Valley Water board meets today; see our meeting preview.
Source: Valley Water news release, Nov. 9, 2026; Anderson Dam Seismic Retrofit project page