Article published Feb 27, 2008

PPL to flow $175 million into Rainbow Dam upgrade

By JO DEE BLACK

Tribune Business Editor

PPL Montana will spend approximately $175 million to update its Rainbow Dam hydroelectric plant northeast of Great Falls, a project that will almost double the electricity generated there.

The Rainbow powerhouse, which was built in 1910 and houses eight turbines, will be replaced with a new powerhouse 200 feet downstream. The new plant will have a single turbine and produce 60 megawatts of electricity, enough to power about 45,000 homes. The existing powerhouse has a capacity of 35 megawatts.

"We'll almost double the amount of power being generated using the same amount of water," said David Hoffman, a PPL Montana spokesman.

The single turbine is more fish-friendly, with wider flow passages, fewer rotating parts and improved intake screens, according to PPL.

Work will begin next spring and take about two years to complete.

"We don't know the number of construction jobs this will create, but I think it will be significant for the community," Hoffman said.

The upgrade is required by the Federal Energy Regulatory Commission as part of PPL Montana's licensing agreement. The timeline is contingent on project approval from federal, state and local entities.

After doing some preliminary calculations, Cascade County Treasurer Jess Anderson estimated the upgrade could generate about $5 million annually in additional property taxes for the county.

PPL Montana is working with NorthWestern Energy, which owns the transmission lines used to deliver power generated by the Rainbow Dam powerhouse, to determine if the system needs to be upgraded to handle the additional load, said Claudia Rapkoch, a NorthWestern Energy spokeswoman.

PPL Montana bought the former Montana Power Co.'s electricity plants in December 1999. The purchase included four other hydropower plants along the Missouri River in Great Falls: Black Eagle Dam, which generates 24 megawatts of electricity; Ryan Dam, which generates 48 megawatts; Cochrane Dam, which generates 48 megawatts; and Morony Dam, which generates 44 megawatts.