Big Sandy Dam is on Big Sandy Creek 10 miles north of Farson, Wyoming. It is a zoned earthfill dam 85 feet high, having a crest length of 2,350 feet and containing about 840,000 cubic yards of material. The uncontrolled open side-channel spillway has a capacity of 7,350 cubic feet per second.
The outlet works, consisting of a concrete conduit through the base of the dam controlled by two high-pressure slide gates, has a capacity of 620 cubic feet per second. An earthfill dike with a maximum height of 18 feet, 8,300 feet long, and containing 107,000 cubic yards of material lies north of the left abutment of the dam along the eastern rim of the reservoir basin.