Deadwood Reservoir is a reservoir in the western United States, in Valley County, Idaho. Located in the mountains of the Boise National Forest about 25 miles (40 km) southeast of Cascade, the 3,000-acre (12 km²) body on the Deadwood River is created by Deadwood Dam. The river flow south from the dam and is a tributary of the South Fork of the Payette River. The reservoir and vicinity is commonly used for camping, water skiing, fishing, canoeing, and other outdoor recreation.