Swift Dam (National ID # MT00581) is a dam in Pondera County, Montana, on the southern end of the Blackfeet Indian Reservation.
The original dam at this location was originally constructed around 1910, with a height of 157 feet. The embankment structure gave way on June 10, 1964, after heavy rains caused flooding on Birch Creek. The dam collapsed and sent a 30-foot wall of water down the creekbed. The nearby dam at Lower Two Medicine Lake also failed, and at least 28 people were killed.
The current concrete-arch structure was completed in 1967, with a height of 205 feet, and a length at its crest of 573 feet. The reservoir is also contained by a secondary earthen dike (National ID # MT00580) with a height of 53 feet and a length of 457 feet, also completed in 1967. The dams and reservoir are owned and operated by the local Pondera Canal & Reservoir Company.
The reservoir, Swift Reservoir, has a maximum storage capacity of 34,000 acre-feet, and normal storage of 30,000 acre-feet. Recreation is restricted to hiking in the area, with a parking area that requires Blackfeet Nation permission.