Grizzly Valley

About Grizzly Valley

The primary purpose of Grizzly Valley is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by California Department Of Water Resources (state). It impounds the Big Grizzly Cr near Portola.

The dam stands 115 feet tall and stretches 800 feet across, creates a reservoir covering 4,032 acres, has a maximum storage capacity of 83,000 acre-feet, and collects water from a drainage area of 44 square miles. Completed in 1966, the structure is well into its service life at over 50 years old.

This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 08/19/2025.

At 115 feet, this dam is taller than 98% of all dams in the United States.

Living Downstream

If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The California dam safety program can provide more specific information about emergency planning for this structure.

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