Statistics (Cubic Feet per Second = CFS; Mean Sea Level = MSL; Kilowatts = Kw; Revolutions per Minute = RPM)
- Significant Dates:
- Operating Since: 1955
- Construction Start: 1946
- Closure: April 15, 1953
- Reservoir filling initiated: December 1953
- Reservoir first reached minimum operating pool: August 7, 1955
- Initial Power Generation – First and Last Units: January 1956 – October 1960
- Powerplant
- Number of turbines: 5 Francis, 90 rpm
- Max power generation capability: 583,300 Kw
- Size
- Ranking: 42nd largest reservoir in the world, 3rd largest reservoir in the United States
- Length of Dam: 11,300 feet (excluding spillway)
- Damming Height: 180 feet (low water to maximum operating pool)
- Maximum Height: 210 feet
- Maximum width at base: 3,400 feet (total)
- Maximum width at base: 2,050 feet (without berms)
- Elevation at crest: 1,854 feet msl
- Construction
- Abutment formations (under dam & embankment): Fort Union clay shale
- Type of Fill: Rolled-earth fill
- Amount of Fill: 66,500,000 cubic yards of fill
- Amount of Concrete: 1,500,000 cubic yards
- Spillway
- Location: Left bank - adjacent
- Width: 1,336 feet gated
- Number of gates: 28
- Dimension of gates: 40-foot x 25-foot tainter gates
- Design discharge capacity: 827,000 cfs at 1,858.5 feet msl pool elevation
- Discharge capacity at maximum operating pool: 660,000 cfs at 1,854 feet msl
- Top of Spillway Gates (closed): 1,854 feet msl
- Intake structures
- Number: 1
- Size: 170 feet wide, 249 feet high
- Length: 540 feet long
- Outlet works
- Number: 5 power generation tunnels, 3 regulating tunnels
- Size: Tunnels 1-5 24-foot dia., Tunnel 6 26-foot dia., Tunnels 7 & 8 22-foot dia.
- Length: Approximately 1,465.5 feet
- Release capacity: Tunnel 6 - 34,400 cfs at elevation 1854 msl, Tunnels 7 & 8 - 29,040 cfs (each) at elevation 1854 msl
- Lake/Reservoir
- Upstream Drainage: 123,900 square miles
- Tributaries: Missouri River, Milk River, Little Missouri River, Yellowstone River
- Shoreline length: 1,340 miles at 1,837.5 feet msl
- Length of full reservoir: 178 miles
- Surface acres: 382,000 acres
- Storage capacity: 23,821,000 acre-feet
- Maximum depth: 180 feet
- Annual Flood Ctrl & Multi-Use Zone (Elevation): 1,837.5 feet msl – 1,850 feet msl
- Exclusive Flood Ctrl Zone (Elevation): 1,850 feet msl – 1,854 feet msl
- Record Pool Elevation (Date): 1,854.8 feet msl (1975); 1,854.6 feet msl (July 1, 2011)
- Record Flow Prior to 2011 (Year): 65,000 cfs (1975)
- Record Flow (2011): 150,600 cfs (Mid June)