Smokestacks at Big Bend Power Station. Photo credit: Mrs. Gemstone/Flickr

This story was updated at 5:18 p.m.

EPA will reconsider a rule that restricts mercury and toxic air emissions from power plants, the agency confirmed to E&E News today.

Agency spokeswoman Molly Block said it will initiate a federal review of a draft proposal to determine whether the Mercury and Air Toxics Standards, or MATS, were "appropriate and necessary." It also will evaluate the overall standards.

"EPA knows these issues are of importance to the regulated community and the public at large and is committed to a thoughtful and transparent regulatory process in addressing them," Block said in an email.


Bloomberg BNA first reported the news.

Most power plants have already complied with the regulation, which required the installation of pollution control technology. Others have shuttered. Several power companies now want the regulation to remain in place.

"If EPA recklessly disrupts the legal obligations to meet the Mercury & Air Toxics Standards, across the country coal plant owners will face legal challenges to prior utility commission approvals of pollution control costs incurred to meet those obligations," John Walke, director of the federal clean air, climate and clean energy program with the Natural Resources Defense Council, said in an email. "Worse, EPA could let coal plant owners turn off installed pollution control equipment whose costs are being charged to consumers. Americans will suffer, needlessly."

Conservatives, though, have argued reassessing — and potentially ditching — the rule is necessary. They noted the Supreme Court in 2015 said the Obama EPA needed to assess industry's compliance costs in its analysis before determining whether the regulation was appropriate and necessary.

EPA later updated its calculations and found the regulation was still warranted. But opponents contend the agency relied on "co-benefits" — basically, counting reduction in pollutants outside of those directly regulated by the standards as a potential boon to public health.

The Trump administration is considering eliminating counting co-benefits of environmental regulations. Environmental groups and more liberal states, however, have charged that such a change would kneecap environmental regulations.

"One of a number of issues EPA is assessing in the context of the appropriate and necessary analysis is whether and how to account for co-benefits," Block said.

It's not surprising that the EPA is reconsidering the rule, said Jeff Holmstead, a former EPA air chief under President George W. Bush who is now an attorney at Bracewell LLP. He said several Supreme Court justices were less than convinced about the case the Obama EPA made for the revision to its first finding, which the Trump EPA is reviewing.

Still, that doesn't mean much would change in a material sense, he said.

"Even if EPA does ultimately reverse the Obama 'appropriate and necessary' finding, this doesn’t mean that the MATS rule will go away," he said in an email. "EPA would have to go through another, separate rulemaking process to eliminate the MATS rule, and I don’t think that anyone is talking about doing that. It would serve no purpose because the power sector has already spent billions of dollars to bring all their plants into compliance."

Reporter Maxine Joselow contributed.