| Tiber Dam | |
| Location Map: | Montana |
| Coordinates: | 48.3219°N -111.0978°W |
| Country: | United States |
| Location: | Chester, Montana |
| Status: | O |
| Construction Began: | 1952 |
| Opening: | 1956 |
| Owner: | U.S. Bureau of Reclamation |
| Dam Type: | Embankment, zoned earth-fill |
| Dam Height: | 2110NaN0 |
| Dam Length: | 43000NaN0 |
| Dam Width Crest: | 300NaN0 |
| Dam Width Base: | 25000NaN0 |
| Dam Volume: | 98000000NaN0 |
| Dam Elevation Crest: | 30260NaN0 |
| Spillway Capacity: | Main: 684670NaN0 Auxiliary: 58450NaN0 |
| Res Capacity Total: | 1515000acre.ft |
| Res Catchment: | 43750NaN0 |
| Res Elevation: | 29330NaN0 |
The Tiber Dam is a dam on the Marias River in southern Liberty County, Montana, which forms Lake Elwell (also known as Tiber Reservoir). Construction on the dam began in 1952 and was completed 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.[1] 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 43000NaN0 and height of 2110NaN0. The dike is 170000NaN0 long and 600NaN0 tall. The dam's main spillway is controlled by three gates and has a maximum discharge of 684670NaN0. The dam's auxiliary spillway can release up to 58450NaN0 and the outlet works 16050NaN0.[1]