Nwitimes reported that US Steel has temporarily idled its blast furnaces and steelmaker operations at the massive steel mill, the largest in the nation because ice on the Great Lakes has choked off access to vital raw materials.

The Company said that we are writing to inform you that US Steel has temporarily curtailed its blast furnaces and steelmaking operations at our Gary Works due to unforeseen and unprecedented ice conditions on the Great Lakes that is delaying the transportation of critical raw materials. These severe ice conditions have not occurred on the Great Lakes for more than three decades.

More than 5,800 employees work at the mill, which can produce 7.5 million net tonnes of steel a year and also includes finishing facilities. They continue to report to work.

In the letter, US Steel warned customers that it might not be able to fulfill their orders and will try to identify alternative supply paths. The letter said that “We are working closely and are in continual contact with the United States and Canadian governmental authorities in an effort to expedite and obtain priority passage of our raw materials vessels on the Great Lakes. Unfortunately, passage has been prevented due to the ice conditions on the Great Lakes, which we hope will quickly improve as a result of recent warming temperatures. As result of this contingency, it is possible that our ability to timely fulfill your orders will be temporarily impacted. Please consider this letter notice of that possibility.”

Gary Works which stretches along seven miles of Lake Michigan's south shoreline, gets iron ore an essential ingredient in steelmaking from lake freighters that have not been able to navigate treacherous conditions that include 40 inch thick shelf ice and stacks of ice chunks that reach as high as 14 feet tall.

Great Lakes ice cover had hit the highest point in 35 years this winter, and is currently at 65.7%. Most problematically, Lake Superior is more than 80% frozen over, which is preventing ships from hauling ore from Minnesota's Iron Range to Northwest Indiana steel mills.