Grand Coulee Dam

About Grand Coulee Dam

The primary purpose of Grand Coulee 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 Columbia River near Coulee Dam City.

The dam stands 550 feet tall and stretches 5,375 feet across, creates a reservoir covering 82,300 acres, has a maximum storage capacity of 9,715,346 acre-feet, and collects water from a drainage area of 75,117 square miles. Completed in 1941, the structure is well-established, with more than 75 years of service.

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 09/17/2021.

At 550 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 Washington dam safety program can provide more specific information about emergency planning for this structure.

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