Windy Knoll Dam

About Windy Knoll Dam

The primary purpose of Windy Knoll Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Willmarjim Company (private). It impounds the Trib-charrette Creek near Marthasville.

The dam stands 31 feet tall and stretches 432 feet across, creates a reservoir covering 5 acres, has a maximum storage capacity of 83 acre-feet, and collects water from a drainage area of 45 square miles. Completed in 1969, 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 06/09/1980. 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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