Tiber Dam, located in southern Liberty County in northern Montana, USA, is a dam on the Marias River which forms Lake Elwell, also known as Tiber Reservoir. Construction on the dam began in 1952 and it was complete in 1956. Between 1967 and 1969, a dike was added to the southern rim of the reservoir near the dam due to difficulties with the spillway settling. From 1976 to 1989, the spillway was rehabilitated. The dam is also considered one of the biggest earth-fill dams in the world, along with Fort Peck Dam. The dam is an earth-fill type with a length of and height of . The dike is long and tall. The dam's main spillway is controlled by three gates and has a maximum discharge of . The dam's auxiliary spillway can release up to and the outlet works . References Dams in Montana Buildings and structures in Liberty County, Montana Earth-filled dams United States Bureau of Reclamation dams Dams completed in 1956