The saga for regulating mercury and air toxics from coal- and oil-fired power plants continues with a final rule promulgated by the U.S. Environmental Protection Agency (“EPA”) on April 16, 2020. EPA initially determined that it was “appropriate and necessary” under Section 112 of the Clean Air Act to regulate hazardous air pollutants (“HAPs”)—including mercury—for these types of power plants, commonly referred to as electric utility steam generating units (“EGUs”). In a change of policy, EPA has now decided that the “appropriate and necessary” determination to regulate HAPs for these power plants—after two decades of additional EPA rules, and corresponding litigation—is no longer correct.
A significant part of the backstory here is related to the U.S. Supreme Court’s decision in 2015 in Michigan v. EPA. Briefly, the Court held that the EPA needed to consider costs in evaluating whether it was “appropriate and necessary” to regulate HAP emissions from coal- and oil-fired EGUs, especially the costs associated with compliance. Following the Supreme Court’s decision, EPA, under the Obama Administration, conducted a study in 2016 to evaluate these costs and concluded that it was still “appropriate and necessary” to regulate HAPs emitted from these sources. The Trump Administration has now reversed course in issuing the April 16 final rule, effectively concluding that the EPA’s decision in 2016 was wrong.
More importantly, and separate from EPA’s decision to reverse course, the Agency announced in its final rule that these power plants will remain a source category subject to regulation of HAP emissions under Section 112(c)(1) of the Clean Air Act. Thus, EPA’s April 2020 rule does not affect the existing Section 112(d) emission standards that regulate HAP emissions from these power plants, and which were issued in the 2012 Mercury and Air Toxics Standards (“MATS”) Final Rule that set numeric emission limits for mercury, acid gases, and non-mercury metallic toxic pollutants. Accordingly, the MATS Rule is still in effect and the emission standards still apply.
Those affected by this rule should note that it will inevitably be challenged in the courts. Litigation over the 2016 rule was actually stayed at the request of Trump Administration, so any newly filed litigation could potentially pick up right where it left off—albeit now with a possible reversal in litigation positions advocated by the government, industry, and environmental groups. For now, these developments should be monitored closely, and those affected should contact counsel and technical experts to ensure that your facility remains in compliance as these regulatory changes continue to occur.
 See EPA–HQ–OAR–2018–0794; FRL-10008-60-OAR (April 16, 2020), prepublication version available at epa.gov/sites/production/files/2020-04/documents/frn_mats_finding_and_rtr_2060-at99_final_rule.pdf.
 See 40 C.F.R. Parts 60 and 63, 77 FR 9304, available at govinfo.gov/content/pkg/FR-2012-02-16/pdf/2012-806.pdf.
 See Murray Energy Corp. v. EPA, No. 16-1127 (D.C. Cir.).