Mercury and Air Toxics Standards

Oct. 4, 2024 the Supreme Court denied industry and state petitioners’ applications for stay.

Aug. 16, 2024 State and industry petitioners filed in the Supreme Court for a stay pending review.

Aug. 6, 2024 The D.C. Circuit denied the motions for stay. (Order for denying the motion for stay pending review, at page 5)

June 21, 2024 Industry challengers joined the State Petitioners’ motion for stay, including: National Rural Electric Cooperative Association, Lignite Energy Council, National Mining Association, Minnkota Power Cooperative, East Kentucky Power Cooperative, Associated Electric Cooperative, Basin Electric Power Cooperative, and Rainbow Energy Center. State of North Dakota v. EPA, Docket No. 24-01119 (D.C. Cir. May 8, 2024).

June 7, 2024 State petitioners filed a motion to stay the final MATS rule, including: ND, WV, AK, AR, GA, ID, IN, IA, KS, KY, LA, MS, MO, MT, NE, OK, SC, SD, TN, TX, UT, VA, and WY.

May/June 2024 North Dakota and 23 states filed a petition in the D.C. Circuit challenging the new MATS. Several additional industry organizations filed challenges. States and environmental and public health organizations intervened in support of EPA’s final rule. North Dakota, et al v. EPA, Docket No. 24-1119 (May 8, 2024).

May 7, 2024 EPA finalized its Residual Risk and Technology Review (RTR) for coal- and oil-fired EGUs. The rule set new limits for filterable particulate matter (fPM) for coal- and lignite-fired power plants and mandates that sources use PM Continuous Emissions Monitoring Systems (PM CEMS) to demonstrate compliance. 

July 13, 2023 EPA issued a final rule revoking the Trump Administration’s Clean Air Act Cost-Benefit Rule that limited the scope of benefits that EPA could consider in its Clean Air Act rulemakings. To learn more about the Trump rule, read our analysis: New Cost-Benefit Rule Hampers EPA’s Ability to Regulate Harmful Air Pollutants.

Apr. 24, 2023 EPA released its proposed residual risk and technology review. For certain emissions standards, EPA proposes more stringent emission limits for existing coal-fired and lignite-fired electric generating units (EGUs) and proposes to update some of compliance requirements. EPA proposed that the more stringent emission limits would apply within three years of the rule’s effective date. Comments will be due 60 days after publication in the Federal Register.

Mar. 6, 2023 EPA published the final rule finding it is “appropriate and necessary” to regulate HAP emissions from coal- and oil-fired power plants in the Federal Register. The rule did not get challenged in court.

Jan. 31, 2022 The Biden Administration proposed to reaffirm its 2016 finding that it remains “appropriate and necessary” to regulate HAP emissions from coal-fired power plants and revoke its 2020 finding. EPA also requested comment on specific questions as part of its review of the residual risk and technology review.

Feb. 12, 2021 EPA filed motions to hold in abeyance several cases challenging EPA’s reversal of the appropriate and necessary finding. The D.C. Circuit granted those motions on Feb. 16, directing EPA to file an abeyance status report on June 16, 2021, and at 120-day intervals thereafter. American Academy of Pediatrics v. Andrew Wheeler, No. 20-01221 (D.C. Cir.); Massachusetts v. EPA, No. 20-01265 (D.C. Cir.); Advanced Emissions Solutions v. EPA, No. 20-01266 (D.C. Cir.); Puget Sound Energy v. EPA, No. 20-1271 (D.C. Cir.).

Jan. 20, 2021 President Biden issued an Executive Order directing the EPA Administrator to consider suspending, revising, or rescinding the May 2020 rule reversing the appropriate and necessary finding. EPA had to complete that review by August 2021.

Sep. 28, 2020 The D.C. Circuit granted Westmoreland’s request to sever and put on hold its case challenging the legality of MATS. Westmoreland Mining Holdings v. EPA, No. 20-1160 (D.C. Cir.).

Aug. 28, 2020 Westmoreland Mining Holdings LLC requested that the D.C. Circuit sever and put on hold its case challenging the legality of MATS. This would allow the cases challenging the reversal of the appropriate and necessary finding to advance separately. The public health and environmental organizations that intervened in the case supported this motion. Westmoreland Mining Holdings v. EPA, No. 20-1160 (D.C. Cir.).

 July 31, 2020 The D.C. Circuit suspended (held in abeyance) for 90 days the challenge to EPA’s less stringent acid gases and SO2 limits for power plants burning eastern bituminous coal refuse. The environmental groups requested this hold to give EPA time to respond to their request that the agency reconsider the final rule. Citizens for Pennsylvania’s Future v. EPA, No. 20-1207 (D.C. Cir.).

May/June 2020 Westmoreland Mining Holdings LLC filed a petition for review in the D.C. Circuit challenging the legality of MATS. Many of the parties also moved to intervene in the lawsuit to defend EPA’s decision to not rescind MATS, including power companies, coalitions of states, and coalition of advocacy organizations. Westmoreland Mining Holdings v. EPA, No. 20-1160 (D.C. Cir.). American Academy of Pediatrics v. Andrew Wheeler, No. 20-01221 (D.C. Cir.); Massachusetts v. EPA, No. 20-01265 (D.C. Cir.); Advanced Emissions Solutions v. EPA, No. 20-01266 (D.C. Cir.); Puget Sound Energy v. EPA, No. 20-1271 (D.C. Cir.).

May 22, 2020 EPA finalized rule withdrawing the appropriate and necessary finding. EPA also finalizes the residual risk and technology review and determines that after compliance with MATS, the residual risks from power plant hazardous air pollutant emissions are acceptable and the standards should not be tightened. 

Apr. 9, 2020 EPA’s Science Advisory Board critiqued EPA’s assessment of the residual risks to human health from pollutants regulated by MATS. The results of EPA’s final assessment (known as the Residual Risk Assessment) will determine whether EPA must set more stringent pollution control requirements for power plants.

Apr. 9, 2020 EPA finalized a rule adjusting emissions limits for four power plants that burn eastern bituminous coal refuse (a form of coal mining waste). The new standards allow the affected plants to release higher amounts of acid gases and SO2 emissions.

Dec. 31, 2019 EPA’s Science Advisory Board released a draft report that recommends a new risk assessment be completed for the revised Supplemental Cost Finding and Residual Risk and Technology Review and any future mercury regulation. The new risk assessment should include the mercury-related health effects of consuming all fish, going beyond recreationally caught freshwater fish.

Apr. 17, 2019 The attorneys general of 21 states submitted comments to EPA opposing its proposal to withdraw the appropriate and necessary finding.

Mar. 26, 2019 Several industry trade groups and labor unions sent a letter to EPA air chief Bill Wehrum urging EPA to maintain its 2012 regulations and “…take no action that would jeopardize these investments or the underlying rule.” The letter also suggested that “…EPA should consider the impacts such an action would have on these costs already borne by industry and how the recovery of these sunk costs could be put in jeopardy….”

Mar. 18, 2019 A bipartisan group of six senators sent a letter to EPA Administrator Wheeler, urging him to withdraw the proposal to revise the appropriate and necessary finding and voicing their opposition to any action that could lead to undoing the Mercury and Air Toxics Standards.

Dec. 28, 2018 EPA released a proposal to revise the 2016 Supplemental Cost Finding and Residual Risk and Technology Review for MATS. The proposal would limit consideration of health benefits in regulation. For more information, refer to our discussion of the impacts of the issues in this proposal. 

Aug. 24, 2018 Senators Tom Carper (D-Del.) and Lamar Alexander (R-Tenn.) sent a letter to acting EPA Administrator Andrew Wheeler urging EPA to retain MATS. The senators explain, “Keeping the current rule in place will provide much-needed certainty for the electric power industry and help protect the health of all Americans.”

July 10, 2018 The Edison Electric Institute and several other industry trade groups and unions sent a letter to EPA air chief Bill Wehrum asking him to leave the MATS in place and finish the residual risk and technology review “as expeditiously as possible.” The letter also emphasized that “…all covered plants have implemented the regulations and that pollution controls — where needed — are installed and operating.”

Apr. 27, 2017 The D.C. Circuit removed the argument from its calendar, suspending the case indefinitely, and directed EPA to file 90-day status reports.

Apr. 18, 2017 EPA asked the Court to delay oral arguments, scheduled for May 18, 2017.

Feb. 9, 2017 The D.C. Circuit denied the extension.

Jan. 31, 2017 Petitioners sought a 45-day extension in the briefing schedule.

Apr. 25, 2016 EPA published its Supplemental Finding on the costs and benefits of MATS and finds them to be justified in light of the enormous anticipated health benefits. Within hours, opponents sue. Murray Energy v. EPA, No. 16-1127 (D.C. Cir.).

Dec. 15 2015 The D.C. Circuit ordered that the rule to be remanded to EPA without vacatur.

June 29, 2015 The Supreme Court held in Michigan v. EPA, 576 U.S. 743 (2015) that EPA interpreted §7412(n)(1)(A) of the Clean Air Act unreasonably when it “deemed cost irrelevant to the decision to regulate [HAP emissions from] power plants” and remands the rule to the D.C. Circuit to assess how EPA should proceed with additional cost-benefit analyses. The D.C. Circuit sends the MATS back to EPA to determine if the standards are “appropriate and necessary.”

Apr. 15, 2014 The D.C. Circuit upheld the rule on all questions presented to the court by the industry and state petitioners who challenged the rule. White Stallion Energy Center v. EPA, 748 F.3d, 1222 (D.C. Cir. 2014).

Feb. 16, 2012 EPA finalized the Mercury and Air Toxics Standards requiring coal- and oil-fired power plants to achieve the standards by Spring 2016. Industry groups and several states challenge the rule.