Union Mill, located in Keysville, Georgia, is a federal recreational facility managed by the US Army along Sandy Run Creek. Built in 1903, this earth dam stands at 10 feet high and spans 580 feet in length, with a storage capacity of 69 acre-feet. The dam serves the primary purpose of creating a fish and wildlife pond for recreational activities, with a spillway width of 50 feet and a hazard potential rated as low.

Despite its age, Union Mill has undergone structural modifications in 1960 to ensure its continued safety and functionality. The dam's condition assessment is currently not available, with inspections conducted every four years to monitor its integrity. While the risk assessment categorizes Union Mill as having a moderate risk level, the US Army remains responsible for its regulation, inspection, operation, and overall management to ensure public safety and environmental protection at this historic site.