As reported in the last issue of the “Dinsmore Air Quality Letter,” EPA has issued a final supplemental appropriate and necessary finding for regulating emissions of air toxics from power plants. The supplemental finding was in response to the United States Supreme Court decision in Michigan v. EPA that found EPA unreasonably interpreted the CAA when it failed to consider cost in determining whether the Mercury Air Toxics Standards (MATS) was appropriate and necessary, a finding required by CAAt §112. The final finding was published in the “Federal Register” on April 25, 2016. 81 Fed. Reg. 24420 (April 25, 2016). On June 13, 2016, the Supreme Court denied a petition by 20 states, including Kentucky, Ohio, and West Virginia, to review a ruling by the U.S. Court of Appeals for the D.C. Circuit to leave MATS in place while EPA completed the supplemental finding. The states had asked the Supreme Court to review the process of remanding regulatory rules while leaving the rule in place arguing a remand without vacatur leaves in place provisions that a court has found unlawful. EPA argued that its revised finding, that included costs, addressed the deficiency in the rule rendering the states’ case moot. The Supreme Court’s denial was issued with no explanation provided.

While the Supreme Court’s denial ends litigation concerning continuation of MATS during remand, appeals concerning the supplemental finding will proceed. Meanwhile, EPA’s April 6, 2016 final technical revisions to MATS have been challenged by both environmental and utility groups. These lawsuits are in the early stages, and we will continue to track the litigation as it progresses.

Finally, EPA has proposed to amend MATS to revise and streamline electronic data reporting for owners and operators who use either performance testing or continuous monitoring to demonstrate compliance. 81 Fed. Reg.67062 (September 29, 2016). According to EPA, the revisions would “ease burden, increase MATS data flow and usage, make it easier for inspectors and auditors to assess compliance and encourage wider use of continuous emissions monitoring (CEMS) for MATS compliance.” Comments will be accepted on the proposal on or before October 31, 2016.