The producer said December 5 that it has already issued Worker Adjustment and Retraining Notification Act (WARN) notices to all employees at the Highland complex near Henderson and Dodge Hill complex in Sturgis.

Together, the mines employ 670 individuals. In 2013, the operations produced a total of 3.9 million tons.

While Patriot did not indicate its plans for the mines themselves, officials did say that management is “evaluating various strategic options” for Highland and Dodge Hill.

“Low natural gas prices, together with Environmental Protection Agency regulations designed to curtail low-cost coal-fueled energy, continue to drive down thermal coal prices, resulting in operating losses at many mines across the United States,” the company said.