Rainbow Dam

Rainbow Dam is a hydroelectric dam on the Missouri River, 29 feet (8.8 m) high and 1,055 feet (322 m) long, located six miles northeast of Great Falls in the U.S. state of Montana.^[2]

Rainbow Dam
Rainbow Dam and Rainbow Falls in 2000
Official name	Rainbow Dam
Location	Cascade County, Montana, US
Coordinates	47°32′04″N 111°12′18″W / 47.53444°N 111.20500°W / 47.53444; -111.20500
Opening date	1910
Operator(s)	NorthWestern Corporation
Dam and spillways
Impounds	Missouri River
Height	29 ft (8.8 m)
Length	1,055 ft (321.6 m)
Power Station
Installed capacity	36 MW
Annual generation	268,070,000 KWh (2009)^[1]

History

The dam is named for the downstream Rainbow Falls, a 45 ft (14 m) waterfall that is the third of the five Great Falls of the Missouri. Built in 1910, the dam furnishes water to an eight-unit hydroelectric plant with a capacity of 36 megawatts.^[3][4] As the dam's power plant is located over a half-mile downstream, the flow of water over Rainbow Falls and downstream Crooked Falls is significantly reduced during the dry season. The water from the penstocks re-enters the river a few hundred yards east of Crooked Falls. Montana Power Company acquired the dam when it was founded in 1912, PPL Corporation purchased it in 1997 and sold it to NorthWestern Corporation in 2014.

See also

• Ryan Dam

References

1. "Rainbow". Carbon Monitoring for Action. Retrieved 2018-04-26.
2. "Rainbow Dam". PPL Montana. Retrieved 2009-03-28.
3. "The Falls". Visit Great Falls Montana. Retrieved 2021-01-12.
4. Drake, Phil. "NorthWestern plans to raze Rainbow Dam powerhouse". Great Falls Tribune. Retrieved 2021-01-12.

External links

• Historic American Engineering Record (HAER) documentation, filed under End of Rainbow Dam Road, Great Falls, Cascade County, MT:
  • HAER No. MT-95, "Rainbow Hydroelectric Facility", 8 photos, 11 data pages, 1 photo caption page
  • HAER No. MT-95-A, "Rainbow Hydroelectric Facility, Foreman's House", 4 photos, 5 data pages, 1 photo caption page
  • HAER No. MT-95-B, "Rainbow Hydroelectric Facility, Ten Stall Garage", 4 photos, 3 data pages, 1 photo caption page
  • HAER No. MT-95-C, "Rainbow Hydroelectric Facility, Two Stall Garage", 3 photos, 3 data pages, 1 photo caption page
  • HAER No. MT-95-D, "Rainbow Hydroelectric Facility, House No. 16", 4 photos, 5 data pages, 1 photo caption page
  • HAER No. MT-95-E, "Rainbow Hydroelectric Facility, Swimming Pool", 3 photos, 3 data pages, 1 photo caption page
  • HAER No. MT-95-F, "Rainbow Hydroelectric Facility, Tool House", 4 photos, 4 data pages, 1 photo caption page
  • HAER No. MT-95-G, "Rainbow Hydroelectric Facility, Three Stall Garage", 3 photos, 3 data pages, 1 photo caption page
  • HAER No. MT-95-H, "Rainbow Hydroelectric Facility, Clubhouse", 7 photos, 12 data pages, 1 photo caption page
  • HAER No. MT-95-I, "Rainbow Hydroelectric Facility, Arbor", 1 photo, 3 data pages, 1 photo caption page
  • HAER No. MT-95-J, "Rainbow Hydroelectric Facility, Fountain", 1 photo, 3 data pages, 1 photo caption page
  • HAER No. MT-95-K, "Rainbow Hydroelectric Facility, Terraced Gardens", 6 photos, 5 data pages, 1 photo caption page
  • HAER No. MT-95-L, "Rainbow Hydroelectric Facility, Stone Culvert", 5 photos, 5 data pages, 1 photo caption page
  • HAER No. MT-95-M, "Rainbow Hydroelectric Facility, Plank Bridge", 4 photos, 4 data pages, 1 photo caption page
  • HAER No. MT-95-N, "Rainbow Hydroelectric Facility, Powder Magazine", 4 photos, 6 data pages, 1 photo caption page