By early December, the utility had placed two units at its Laskin plant in Hoyt Lakes, Minnesota, and two units at its Taconite Harbor facility in Taconite Harbor, Minnesota, back in operation following improvements in rail shipments by BNSF Railway, according to Minnesota Power spokeswoman Amy Rutledge.

“We feel that our strategy to preserve our stockpiles or to help build those up has been working,” she said. “We’ve entered winter. It’s here, so part of our strategy was to get these four units back on line before winter.”

Rutledge made it clear the utility still was not receiving all of the coal it needed, but hoped deliveries would continue to pick up in the coming weeks and months. “We started seeing improvements in the last couple of weeks,” Rutledge said. “We feel comfortable enough to restart these units, to bring them back on, but we continue to work closely with BNSF as we hit the harsh winter months.”

Many coal-burning electric utilities in the U.S., particularly in the Midwest, have complained about inadequate rail deliveries of coal for much of 2014. The delays have been blamed in part on a record grain harvest in the upper Midwest. But Minnesota Power’s idling of the four units, a decision the utility said was “unprecedented,” has been among the most dramatic actions taken by utilities thus far.

Together, the four units can generate up to 250 megawatts. Minnesota Power’s largest power plant is the 1,000-megawatt Boswell coal facility near Cohasset, Minnesota.