Lake Marian Dam

About Lake Marian Dam

The primary purpose of Lake Marian Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Lake Forest Estates (private). It impounds the Tr-big Bottom Creek near Ste Genevieve.

The dam stands 34 feet tall and stretches 540 feet across, creates a reservoir covering 13 acres, has a maximum storage capacity of 195 acre-feet, and collects water from a drainage area of 177 square miles. Completed in 1974, 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. The most recent inspection on record was 07/26/1988. That was 37 years ago — unusually long for a high-hazard dam, which typically requires more frequent inspections.

At 34 feet, this dam is taller than 80% 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 Missouri dam safety program can provide more specific information about emergency planning for this structure.

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