Record ice cover on Lake Superior continues to cause severe shipping delays.
Three heavy ice breakers are escorting ships in convoys of five across the lake, where stacks of wind-blown ice are still 8 feet thick in places.
About 60 ships are waiting to enter Lake Superior, said Mark Gill, director of vessel traffic services for the Coast Guard at the Soo Locks between Lakes Superior and the lower lakes.
The season's first trip from Duluth to lower Lake Michigan took two weeks. It normally takes less than three days. Some steel mills and power plants around the Great Lakes have run low on their supplies of iron ore and coal.
The ships are "certainly not delivering the raw material at the frequency that the facilities need," Gill said. "That's put a drain universally on steel production, power production, grain shipments, and many other industries that suffer as a result of that."
Gill says Lake Superior is still about 60 percent ice covered. He hopes convoys will only be needed for another week to 10 days.