Pactola Lake is the largest and deepest reservoir in the Black Hills, located 15 miles west of Rapid City, South Dakota, United States. Constructed in 1952, the dam and waters are managed by the Bureau of Reclamation, with the surrounding land managed by the US Forest Service as part of Black Hills National Forest, which operates a visitor center located o…Pactola Lake is the largest and deepest reservoir in the Black Hills, located 15 miles west of Rapid City, South Dakota, United States. Constructed in 1952, the dam and waters are managed by the Bureau of Reclamation, with the surrounding land managed by the US Forest Service as part of Black Hills National Forest, which operates a visitor center located on the south side of the dam. Facilities include campgrounds, hiking trails, picnic areas, cliffs, and a beach.