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Statistics (Cubic Feet per Second = CFS; Mean Sea Level = MSL; Kilowatts = Kw; Revolutions per Minute = RPM)

Significant Dates:

  • Operating Since: 1962
  • Construction Start: 1948
  • Closure: August 3, 1958
  • Reservoir filling initiated: August 1958
  • Reservoir first reached minimum operating pool: April 3, 1962
  • Initial Power Generation – First and Last Units: April 1962 – June 1963

Powerplant

  • Number of turbines: 7 Francis, 100 rpm
  • Max power generation capability: 118,200  Kw

Size

  • Ranking: 45th largest reservoir in the world, 4th largest reservoir in the United States
  • Length of Dam: 9,300 feet (excluding spillway)
  • Damming Height: 200 feet (low water to maximum operating pool)
  • Maximum Height: 245 feet
  • Maximum width at base: 3,500 feet (total)
  • Maximum width at base: 1,500 feet (without berms)
  • Elevation at crest of dam: 1,660 feet msl
  • Spillway crest: 1,620 ft msl

Construction

  • Abutment formations (under dam & embankment): Pierre shale
  • Type of Fill: Rolled-earth fill & shale berms
  • Amount of Fill: 55,500,000 cubic yards of fill & 37,000,000 cubic yards of fill
  • Amount of Concrete: 1,045,000 cubic yards

Spillway

  • Location: Right bank - remote
  • Width: 456 feet gated
  • Number of gates: 8
  • Dimension of gates: 50-foot x 23.5-foot tainter gates
  • Design discharge capacity: 304,000 cfs at 1,644.4 feet msl pool elevation
  • Discharge capacity at maximum operating pool: 80,000 cfs at 1,620 feet msl
  • Top of Spillway Gates (closed): 1,620 feet msl

Intake structures

  • Number: 7 power intake structures
  • Size:  24-foot diameter
  • Length: 3,280 to 4,005 feet long

Outlet works

  • Number: 6
  • Size: 19.75-foot diameter
  • Length: 3,496 to 3,659 feet long
  • Release capacity:  18,500 CFS/conduit or total 111,000 CFS

Lake/Reservoir

  • Upstream Drainage: 62,090 square miles
  • Tributaries: Missouri River, Cheyenne River, Moreau River, Grand River
  • Shoreline length: 2,250 miles at 1,607.5 feet msl
  • Length of full reservoir: 231 miles
  • Surface acres: 206,100 acres
  • Storage capacity: 23,137,000 acre-feet
  • Maximum depth: 205 feet
  • Annual Flood Ctrl & Multi-Use Zone (Elevation): 1,607.5 feet msl – 1,617 feet msl
  • Exclusive Flood Ctrl Zone (Elevation): 1,617 feet msl – 1,620 feet msl
  • Record Pool Elevation (Date): 1,618.7 feet msl (1995 and 1996); 1,619.7.6 feet msl (June 26, 2011)
  • Record Flow Prior to 2011 (Year): 59,000 cfs (1997)
  • Record Flow (2011): 160,300 cfs (Mid June)