U.S. Coast Guard, Chief Petty Officer Alan Haraf, Associated Press
In this Feb. 12, 2014 photo provided by the U.S. Coast Guard the icebreaker Biscayne Bay passes Chicago's Navy Pier, left, as it through the ice covered waters of Lake Michigan on it's way to Indiana.

TRAVERSE CITY, Mich. — An organization representing U.S. cargo shippers on the Great Lakes says last year's deep freeze cost the economy an estimated $705 million and shows the need for another heavy icebreaking vessel.

The Lake Carriers' Association said Tuesday the volume of freight that U.S.-flagged ships hauled on the lakes between Dec. 1, 2013, and May 30, 2014, was about 7 million tons lower than the same period a year earlier.

The Cleveland-based group says at least two steelmakers had to cut production and some power plants ran low on coal as Coast Guard vessels struggled to keep shipping lanes open during the brutally cold winter. About 3,800 jobs were lost.

The group is pushing for construction of a second heavy icebreaker like the Coast Guard's Mackinaw.

Online:

Lake Carrier's Association: http://www.lcaships.com