In Tuesday's press conference, Hoeven pointed out that a local company, Great River Energy, was selling ash for a profit rather than taking a loss, The Bismarck Tribune reported.

"Formerly, that was a cost of $4 million a year," said Hoeven, referring to the expense involved in the disposing of coal ash from the Coal Creek Station, the largest power plant in North Dakota. "They now earn $12 million a year by selling coal ash."

Republicans in Congress have made it a priority to block or repeal EPA regulation this year as part of their job-creation agenda.