Unionville Old City Lake Dam

About Unionville Old City Lake Dam

The primary purpose of Unionville Old City Lake Dam is debris control. The dam is designed to catch sediment, rocks, and debris carried by flowing water — particularly important in areas prone to mudslides or heavy erosion. The dam is owned by Unionville,mo (local government). It impounds the Tr-blackbird Creek near Unionville.

The dam stands 28 feet tall, creates a reservoir covering 12 acres, has a maximum storage capacity of 180 acre-feet, and collects water from a drainage area of 245 square miles. Completed in 1914, 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.

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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