The Environmental Protection Agency dinged a North Dakota fracking company on Friday for $2.1 million for contributing to smog.
The driller, Slawson Exploration Co., agreed to pay the hefty fine in a settlement with the agency rather than contest it and go to court.
The EPA said the company, the largest oil producer in the Midwest, did not install the necessary pollution controls at its nearly 200 oil storage locations in the state.
The agency said the company will need to make about $2 million in upgrades to those facilities to comply with the EPA's smog rules.
"EPA is committed to making sure that domestic energy development grows in a responsible way that protects public health and complies with the law," said Cynthia Giles, EPA's enforcement chief.
The EPA made the announcement while President-elect Trump was expected to meet with North Dakota Democratic Sen. Heidi Heitkamp Friday for a possible position in his Cabinet, potentially head of the Energy Department or the EPA.
Heitkamp has been a critic of EPA's climate change regulations on the utilities in her state and shares many of the same views on energy development as Trump.
Trump announced Thursday that he was adding a fracking proponent to his EPA transition team. Amy Oliver Cooke, director of the Colorado-based Independence Institute's Energy Policy Center, will be adding her thoughts to the process of transitioning the EPA to one controlled by the incoming Trump administration.