Capitol Lake Dam

About Capitol Lake Dam

The primary purpose of Capitol Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by S&pl (state). It impounds the Hilgers Gulch near Pierre.

The dam stands 27 feet tall and stretches 600 feet across, creates a reservoir covering 6 acres, has a maximum storage capacity of 127 acre-feet, and collects water from a drainage area of 6 square miles. Completed in 1921, the structure is over a century 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 fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 07/27/2022.

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 South Dakota dam safety program can provide more specific information about emergency planning for this structure.

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