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Demolition of Rainbow Dam powerhouse continues

Demolition begins on Rainbow Dam powerhouse
Rainbow Dam
Jo Dee Black
Posted at 2:38 PM, May 13, 2021
and last updated 2021-05-13 17:04:31-04

After starting in the fall of 2020, work to demolish the old Rainbow Dam powerhouse in Great Falls was finally becoming visible Wednesday as work was being done on the outside.

From the hills on the north side of the river, heavy equipment could be heard Wednesday, and from the road across the river, that heavy equipment could be seen.

In 2014, NorthWestern Energy bought Rainbow Dam, built between 1908 and 1910, with the hope of finding a new use for the historic powerhouse since a new one had already been constructed.

"NorthWestern Eneregy worked with the Cascade County Historical Preservation Old Rainbow Powerhouse Repurposing Committee to look for alternative uses. Northwestern Energy provided $50,000 for a feasibility study,” explained Jo Dee Black, spokesperson for NorthWestern Energy.

Rainbow Dam

Great Falls business owner Peter Jennings chaired the committee and said preserving the powerhouse is important. "I think the story is what's most important, about hydroelectric in this area and the development of the west,” Jennings said.

A company in 2019 expressed interest in opening a data center in the facility, but changed its mind in 2020, at which point the decision was made to raze the building.

"Some of the artifacts and pieces of it are being stored and NorthWestern Energy is working with the historical committee to decide the future of those pieces, how they'll be used in an interpretive display for the community,” said Black.

Demolition of the building is expected to be complete in late spring or early summer.

Text from A Centennial Celebration, 1984, Clifford D. Yuill and Ellan R. Yuill:

“Before the dams, Great Falls had electric power derived from a steam generating plant. Ill-fated and short-lived, the plant was replaced by the more economical method of deriving electricity from water power.
“The initial dam development on the Missouri was begun in 1890 by the Great Falls Water Power and Townsite Company who built a timber crib at the Black Eagle Falls. […]
“With a fall of over 400 feet in less than ten miles, the Missouri River at Great Falls was idea for further electric power development and in 1910 the second hydroelectric plant was built, encompassing both Rainbow and Crooked Falls.
“Located about 2 ½ miles below Black Eagle Falls, Rainbow Dam was a timber crib structure filled with concrete and rocks, 1145 feet long and 36 ft high. It developed a water head of 112 feet. Power developed at this site was transmitted to Butte, Anaconda, Lewistown, Havre, the upper Sun River, and Cascade. In 1913 the heigh of the dam was increased, affording it even more generating power.”
The Washoe Copper Smelter (the “largest smelter in the world” and home of the tallest masonry structure, the Anaconda Smelter Stack) was powered by the Rainbow

From April 2020: