HELENA, Mont. -

A Public Service Commission member says NorthWestern Energy has filed a formal application for its proposed purchase of 11 hydroelectric dams from PPL Montana for $900 million.
Commissioner Travis Kavulla says NorthWestern filed its preapproval application Friday afternoon.
Kavulla says that starts the clock ticking on the commission's decision to approve the sale.
Commissioners will have 45 days to determine whether the application is adequate and nine months to approve or reject the purchase.
The sale also must be approved by the Federal Energy Regulatory Commission and anti-trust regulators in the U.S. Department of Justice.
NorthWestern officials have said the purchase will mean an initial rate increase of about 5 percent followed by stable customer rates.