Lake Mendota Dam

About Lake Mendota Dam

The primary purpose of Lake Mendota Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by City Of Mendota (local government). It impounds the Mendota Creek near Mendota.

The dam stands 17 feet tall and stretches 2,430 feet across, creates a reservoir covering 17 acres, has a maximum storage capacity of 246 acre-feet, and collects water from a drainage area of 221 square miles. Completed in 1890, 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. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 04/29/2025.

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

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