The U.S. and Canadian Coast Guards have begun icebreaking operations to keep shipping lanes open in the Great Lakes.
Work began Thursday in southern Lake Huron, Lake St. Clair, the Detroit River, Lake Erie and Lake Ontario.
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Crews are breaking ice jams that can delay shipping and cause flooding along the shore. The two Coast Guards say they'll monitor potentially hazardous ice conditions and conduct icebreaking as needed across the Great Lakes system.
Ships haul iron ore, coal, salt, limestone, oil and cement.
Last winter produced some of the most widespread ice cover on record. In early March, about 92 percent of the lakes were frozen over, the highest percentage since 1979.