The expansion project that spanned over a period of three-and-a-half years included replacement of smaller units with combined capacity of 35MW with a single 60MW unit. It increased the power generation capacity of Rainbow Dam by 70%.

PPL Montana vice president and chief operating officer Pete Simonich noted that the company is proud to have invested in the state making responsible use of its valuable natural resources.

"We thank everyone who was involved in the design and construction of this project, and appreciate the outstanding support we have received at every step along the way," added Simonich.

Besides the expansion of Rainbow hydro project, PPL Montana has completed a $38m Great Falls 100kV interconnection project to improve the efficiency of the electrical systems connecting its five Great Falls hydro plants to NorthWestern Energy grid.

Under this project, the company has installed a new Crooked Falls switchyard improving the reliability of transmission system and a new generation control center to provide remote operation to its Great Falls plants.