Marion County Lake Dam

About Marion County Lake Dam

The primary purpose of Marion County Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Marion County (local government). It impounds the Cottonwood River-tr near Florence.

The dam stands 62 feet tall and stretches 1,290 feet across, creates a reservoir covering 150 acres, has a maximum storage capacity of 4,063 acre-feet, and collects water from a drainage area of 7 square miles. Completed in 1937, the structure is well-established, with more than 75 years of service.

This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. An emergency action plan is in place for this dam. The most recent inspection on record was 08/11/2021.

At 62 feet, this dam is taller than 95% of all dams in the United States.

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