Antilon Lake Dam

About Antilon Lake Dam

The primary purpose of Antilon Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Lake Chelan Reclamation Dist (public utility). It impounds the Tr-johnson Creek near Manson.

The dam stands 62 feet tall and stretches 300 feet across, creates a reservoir covering 118 acres, has a maximum storage capacity of 2,475 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1913, 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 08/17/2023.

At 62 feet, this dam is taller than 95% 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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