Stateline Dam, on the East Fork of Smiths Fork within the Wasatch National Forest in Utah, is about 0.5 mile south of the Utah-Wyoming state line. The dam has a height of 148 feet above streambed and a crest length of 2,800 feet. The spillway has a discharge capacity of 5,850 cubic feet per second, an uncontrolled concrete morning glory drop inlet at elevation 9163.2 feet, and a 14.5 foot diameter concrete conduit through the dam along the right abutment with a stilling basin at river level. The outlet works is located under the center of the dam along the stream channel and has a discharge capacity of approximately 400 cubic feet per second at the maximum water surface of 9169.6 feet. Structures along the outlet works include an intake structure, a gate chamber, control house, and stilling basin. Two small earthfill dikes, constructed along the west side of the reservoir basin, have crest lengths of 70 and 130 feet. Each dike is about 10 feet high. Stateline Reservoir has a capacity of 14,000 acre-feet. At maximum water surface elevation, it extends about 1.8 miles upstream from the dam and covers an area of about 300 acres.
The dam, dikes and reservoir are located on unconsolidated glacial, alluvial, and slough deposits in the East Fork of Smith Fork Valley near the Utah-Wyoming border state line. Bedrock was not encountered by drill holes or excavations and is not exposed in the dam area. Postglacial alluvial stream deposits are confined to a narrow strip along East Fork of Smith Fork. The character and thickness of these deposits are unknown, however, physiographic relationships suggest alluvial deposits are thin at both the dam axis and within the reservoir area.