Big Sky Dam

About Big Sky Dam

The primary purpose of Big Sky Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Big Sky Of Montana Inc (private). It impounds the Middle Fk West Fk Gallatin Ri near Gallatin Gateway.

The dam stands 52 feet tall and stretches 400 feet across, creates a reservoir covering 9 acres, has a maximum storage capacity of 225 acre-feet, and collects water from a drainage area of 5 square miles. Completed in 1973, 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 08/28/2020.

At 52 feet, this dam is taller than 93% of dams nationwide.

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

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