Iron Mountain Lake Dam

About Iron Mountain Lake Dam

The primary purpose of Iron Mountain Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Iron Mtn Lake Ownr Assoc (private). It impounds the Middlebrook Cr near Bismarck.

The dam stands 16 feet tall, creates a reservoir covering 70 acres, has a maximum storage capacity of 599 acre-feet, and collects water from a drainage area of 3,775 square miles. Completed in 1847, the structure is one of the older dams in the region, with over a century and a half 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. The most recent inspection on record was 02/23/1981. That was 45 years ago — unusually long for a high-hazard dam, which typically requires more frequent inspections.

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

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