John Ballentine Dam

About John Ballentine Dam

The primary purpose of John Ballentine Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Willson Llc Of Berkeley County (private). It impounds the Tr-wassamassa Swamp.

The dam stands 11 feet tall, creates a reservoir covering 28 acres, and has a maximum storage capacity of 252 acre-feet. Completed in 1970, 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. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 10/24/2023.

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

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