By John Dodge

CHICAGO (CBS) — Almost one month into spring, and the U.S. Coast Guard is still breaking up ice around the Great Lakes.

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According to the National Oceanic and Atmospheric Administration, more than 64 percent of Lake Superior was covered in ice as of Wednesday. Lake Michigan was 21 percent covered, Lake Huron was 31 percent covered, Lake Erie was 14 percent covered, and Lake Ontario was 2 percent covered. The entire Great Lakes system was 37 percent covered in ice.

The Coast Guard on Wednesday released video of the cutter Morro Bay carving up ice in the harbor in Marquette, Mich., nestled along the shores of Lake Superior.

The ice was preventing the delivery of coal to the area, needed to power local mining operations.

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The ice-breaking operations began after a difficult and lengthy escort from in Duluth, Minn.

During the trip, the guard used satellite imagery to find openings in the ice.

The crews’ efforts helped keep local mining operations open by allowing the commercial carriers Mesabi Miner and Kaye E. Barker to offload coal to the power plant that is the sole supplier of electricity to the mines.

Ice in Marquette harbor was reported to be up to 24 inches thick.

This winter, the Great Lakes, including Lake Michigan, were 93 percent covered in ice, which is a record.

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The Coast Guard also conducted ice breaking operations along Chicago’s shoreline after a record 25 days of temperatures at zero or below this winter.