Twitchell Dam

About Twitchell Dam

The primary purpose of Twitchell Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Bureau Of Reclamation (federal). It impounds the Cuyama River near Santa Maria.

The dam stands 241 feet tall and stretches 1,804 feet across, creates a reservoir covering 9,448 acres, has a maximum storage capacity of 398,120 acre-feet, and collects water from a drainage area of 1,121 square miles. Completed in 1958, 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. An emergency action plan is in place for this dam. The most recent inspection on record was 08/24/2020.

At 241 feet, this dam is taller than 99% 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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