"Lake Superior is likely going to ice over completely. In all probability, that means it's going to be a very tough breakout in March," said Glen Nekvasil, vice president of the Lake Carriers' Association.
Lake Superior was estimated to be 93.5 percent ice bound as of Friday. If it freezes over completely, it would be the first time that has happened since 1996, the (Minneapolis) Star-Tribune reported Saturday.
The Great Lakes Environmental Research Laboratory, which monitors lake conditions, said 79.6 percent of the five Great Lakes were iced over. A record 94.7 percent of the lakes were frozen over in 1979.
The Soo Locks at St. Marie, Minn., are scheduled to open March 25, signaling the start of the Great Lakes shipping season.
"But right now we're not getting any relief ... it's a good, old-fashioned winter," said Mark Barker, president of the Interlake Steamship Co., which ships raw materials such as coal and limestone.
At some point, the Coast Guard will try to plow a path with ice-breakers, but a prolonged deep freeze means that, come spring thaw, the Coast Guard will be challenged to keep up.
"In this case, we have heavy ice over multiple locations. That takes those [Coast Guard] assets and spreads them thin," Barker said.