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Fixing Anderson Dam is a priority for Valley Water

February 25, 2020
Anderson Dam

In 2019, Valley Water produced a draft of a video depicting a worst-case scenario should a filled-to-capacity Anderson Dam fail in the event of a major earthquake.

The draft video was produced to better explain to lawmakers and regulators the level of urgency needed to move the Anderson Dam Seismic Retrofit Project forward. It was created with the help of the consulting engineering firm Black and Veatch, and Trinity Animation.

Studies have shown a large earthquake could damage Anderson Dam, causing damage or failure and an uncontrolled release of water that could inundate cities and rural areas from San Francisco Bay south to Monterey Bay, including much of Silicon Valley. The draft video depicts such a scenario.

Currently Anderson Reservoir is operating below the levels required by the Federal Energy Regulatory Commission (FERC) and the state Division of Safety of Dams. FERC is now demanding Valley Water to begin a full drawdown of the reservoir by Oct. 1, 2020.


The requirement to empty Anderson Reservoir could result in unsafe consequences:

  • A top concern is the potential to damage the intake structure, which would give us no way to control water flows out of the reservoir, potentially impacting downstream communities. While Valley Water will take every precaution to make sure that does not happen, it is a potential consequence.
  • Maintaining the reservoir at a level above the currently mandated FERC requirement will provide Valley Water an additional ability to control water flows out of the reservoir.
  • A bill has been introduced in the California Legislature, Assembly Bill 3005 authored by Assemblymember Robert Rivas, to help expedite the regulatory process and move this project along as quickly as possible. Valley Water continues to look at ways to engage local, state and federal lawmakers to help deliver this project in a timely manner.

Fixing Anderson Dam is a priority for Valley Water. Project details are available at

Valley Water manages an integrated water resources system that includes the supply of clean, safe water, flood protection and stewardship of streams on behalf of Santa Clara County's 2 million residents. The district effectively manages 10 dams and surface water reservoirs, three water treatment plants, an advanced recycled water purification center, a state-of-the-art water quality laboratory, nearly 285 acres of groundwater recharge ponds and more than 294 miles of streams. We provide wholesale water and groundwater management services to local municipalities and private water retailers who deliver drinking water directly to homes and businesses in Santa Clara County.