Northwestern Energy, an electric utility serving 656,000 customers in Montana, said it will buy 13 MW from a hydroelectric project under construction near Fairfield, Mont.

The hydro plant, located on an irrigation canal in Teton County, is owned by Turnbull Hydro LLC and is expected to begin commercial operations in 2011.

The 20-year power purchase agreement will help Northwestern meet new state standards for renewable power, said John Hines, the utility’s chief supply officer. Under Montana law, 15 percent of a utility’s power must be made from renewable resources by 2015.

“This project fits nicely in our portfolio of electric resources,” Hines said. “This hydro facility will provide our customers with a stable, reliable source of cost effective electricity that has no carbon emissions.”