PPL Montana’s agreement to sell its hydroelectric facilities to NorthWestern Energy in a $900 million deal has received final approval from the Montana Public Service Commission (PSC).

The PSC greenlight follows prior approvals from the Federal Energy Regulatory Commission, as well as the necessary clearance from the antitrust enforcement agencies. In its actions, FERC approved the transfer of PPL Montana’s hydroelectric generating stations and its hydroelectric operating licenses to NorthWestern upon close of the transaction.

Before the transaction can close, NorthWestern must file with FERC and obtain approval of certain financing transactions. FERC review of that filing is expected to take 30-60 days.

The transaction includes PPL Montana’s 11 hydroelectric power plants and Hebgen Lake reservoir, which have a combined capacity of more than 630MW. It does not include PPL Montana’s interest in the Colstrip coal-fired facility, or its 153MW J.E. Corette coal-fired facility located near Billings, which the company intends to mothball in April 2015. It also does not include the Butte-based marketing and trading operations of PPL Montana’s affiliate, PPL EnergyPlus, LLC.

PPL Montana’s hydroelectric facilities include its Thompson Falls Dam on the Clark Fork River; Kerr Dam on the Flathead River; Madison Dam on the Madison River; Mystic Lake Dam on West Rosebud Creek; and Hauser, Holter, Black Eagle, Rainbow, Cochrane, Ryan and Morony dams along the Missouri River.