Box Canyon

About Box Canyon

The primary purpose of Box Canyon 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 County Of Siskiyou (local government). It impounds the Sacramento River near Dunsmuir.

The dam stands 220 feet tall and stretches 1,100 feet across, creates a reservoir covering 430 acres, has a maximum storage capacity of 26,000 acre-feet, and collects water from a drainage area of 126 square miles. Completed in 1970, 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 08/15/2023.

At 220 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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