Regulatory Tracker

Clean Air Act Section 126 Petitions

NOTE: this page is no longer being updated. For major new state actions please see our page Air Transport – Cross-State Air Pollution Rule / Good Neighbor Rule, Section 126 Petitions, and Section 184 Ozone Transportation Commission Petition. You can click here to return to our Regulatory Tracker or here to sign up for our monthly Tracker email updates.  

Why it Matters

The Clean Air Act’s “good neighbor” provision requires upwind states to ensure that the air pollution they create does not affect downwind states’ ability to meet the National Ambient Air Quality Standards (NAAQS). A downwind state can file a Clean Air Act section 126 petition asking EPA to regulate pollution from sources in another state when that pollution is moving across state lines and impairing interstate air quality. States rely on the “good neighbor” provision to protect their residents’ health and ensure that each state is doing its fair share to reduce pollution.

EPA created the Cross-State Air Pollution Rule to implement the good neighbor provision. This rule requires emissions reductions from many upwind states. For more information on that rule and related litigation see our page, Cross-State Air Pollution Rule.


After a section 126 petition is filed, EPA has 60 days to respond to the petition. If EPA determines action is necessary, the polluting state must address the emissions in their State Implementation Plan (SIP). Otherwise, EPA will issue a Federal Implementation Plan (FIP) that assigns emissions limits.

June 1, 2016 Connecticut files a section 126 petition, asking EPA to curb emissions from the Brunner Island coal plant in Pennsylvania.

July 7, 2016 Delaware files its first section 126 petition, asking EPA to curb emissions from the Brunner Island coal plant.

July 25, 2016 EPA extends the timeline for responding to Connecticut’s petition to Jan. 25, 2017.

Aug. 9, 2016 Delaware files its second section 126 petition, asking EPA to curb emissions from the Harrison coal plant in West Virginia.

Aug. 23, 2016 EPA extends its timeline for responding to the first Delaware petition to March 5, 2017.

Sept. 27, 2016 EPA extends its timeline for responding to the second Delaware petition to April 7, 2017.

Nov. 10, 2016 Delaware files a third section 126 petition, asking EPA to address pollution drifting into that state from the Homer City coal plant in Pennsylvania.

Nov. 16, 2016 Maryland files a section 126 petition, asking EPA to address pollution drifting into that state from 36 coal plants located in Indiana, Kentucky, Ohio, Pennsylvania, and West Virginia.

Nov. 28, 2016 Delaware files a fourth petition, asking EPA to address pollution from the Conemaugh coal plant in Pennsylvania.

Dec. 16, 2016 EPA extends its timeline for responding to Delaware’s third (Homer City) petition and Maryland’s petition by six months, to July 9, 2017 (DE) and July 15, 2017 (MD).

Trump Era

Jan. 23, 2017 EPA extends the deadline on Delaware’s fourth (Conemaugh) petition to August 3, 2017.

March 24, 2017 Delaware sues EPA over the extension of the deadline to respond to its petition regarding the Conemaugh coal plant. Delaware v. EPA, No. 2:17-1099 (D.C. Cir.).

April 25, 2017 Environmental groups write to Administrator Pruitt, requesting that he grant the pending section 126 petitions.

May 17, 2017 Connecticut sues EPA for failure to respond to its petition on the Brunner coal plant in Pennsylvania. Connecticut v. Pruitt et al., No.3:17-00796.

July 20, 2017 Maryland’s Department of the Environment sends a 60-day notice letter to EPA, announcing it intends to sue for EPA’s failure to respond to its section 126 petition by the July 15, 2017 deadline.

Sep. 27, 2017 Maryland sues EPA for failure to respond to its petition. State of Maryland v. EPA, No. 18-1285 (consolidated with Nos. 18-1287 and 18-1301) (D.C. Cir.).

Jan. 2, 2018 Delaware notifies EPA that it intends to sue EPA over its failure to address Delaware’s four section 126 petitions.

March 12, 2018 New York submits a section 126 petition requesting that EPA make a finding that emissions from sources in nine states (Illinois, Indiana, Kentucky, Maryland, Michigan, Ohio, Pennsylvania, Virginia and West Virginia) significantly contribute to nonattainment and interfere with maintenance of the 2008 and 2015 ozone air quality standards in Chautauqua County and the New York Metropolitan Area in violation of the Clean Air Act.

April 9, 2018 EPA issues a Notice of Final action rejecting Connecticut’s Brunner coal plant petition, saying it is “denying the petition based on the conclusion that Connecticut has not demonstrated and the EPA has not determined that the Brunner Island facility emits or would emit pollution in violation of the good neighbor provision with respect to the 2008 ozone NAAQS.” EPA had issued a proposed rejection in February.

May 22, 2018 The District Court for the District of Connecticut rules that EPA failed to justify its request for another year-long extension and grants Connecticut’s motion for summary judgment. The court requires EPA to hold a public hearing on a proposed decision in 30 days, and take final action on Connecticut’s petition in 60 days. Connecticut v. Pruitt et al., No. 3:17-cv-00796.

Aug. 31, 2018 EPA releases a memo to its regional offices with guidance on setting pollution thresholds for ozone levels in State Implementation Plans. The memo states that it may be appropriate to allocate a higher amount of ozone pollution to upwind states when evaluating downwind states’ SIPs. Specifically, the memo suggests using a 1-part-per-billion (ppb) contribution, which is higher than the 1 percent of the NAAQS threshold (0.70 ppb) set under the Obama administration in 2015. This change allows upwind states to contribute more ozone pollution to downwind states.

Oct. 5, 2018 EPA finalizes its denial of Delaware and Maryland’s section 126 petitions.

Oct. 12, 2018 Maryland files a petition for review in the DC Circuit of EPA’s denial of the state’s section 126 petition. Maryland v. EPA, No. 18-1285 (D.C. Cir.)

Nov. 5, 2018 Delaware files a petition for review with the DC Circuit for EPA’s denial of its four section 126 petitions. The case is later consolidated with Maryland’s case as Maryland v. EPA, No. 18-1285 (D.C. Cir.).

March 29, 2019 In their briefs, Maryland and Delaware ask the court to vacate the agency denial and to tell EPA to impose additional emissions limitations on the upwind sources. Maryland v. EPA, No. 18-1285 (D.C. Cir.).

April 12, 2019 New York sues EPA for failing to act on its section 126 petition requesting limits on emissions from 120 facilities across nine upwind states that affect its ability to comply with the 2008 and 2015 ozone NAAQS. New York alleges that EPA “has failed to hold a public hearing or take final action” on its petition filed in March 2018. New York v. EPA, No.: 1:19-cv-3287 (S.D.N.Y.).

May 20, 2019 EPA proposes to deny New York’s section 126 petition. The comment period for this decision is open until July 15, 2019.

Oct. 18, 2019 EPA formally denies New York’s section 126 Petition, finding no violation of the Good Neighbor Provision.

Oct. 29, 2019 New York and New Jersey sue EPA for its denial of New York’s Good Neighbor Petition. New York v. EPA, No. 19-01231 (D.C. Cir.)

May 19, 2020 The DC Circuit denies Delaware’s petition for review but grants, in part, Maryland’s petition. The court finds that, in light of an earlier D.C. Circuit decision, EPA too quickly dismissed Maryland’s argument that the agency should require four upwind power plants to operate non-catalytic controls. Maryland v. EPA, No. 18-1285 (D.C. Cir.).

July 14, 2020 A three-judge panel for the D.C. Circuit rules that EPA acted unlawfully by failing to provide a reasoned explanation for denying New York’s 126 petition. The court voids (vacates) EPA’s denial and sends the petition back to EPA to reconsider. The court does not give EPA a deadline by which it must issue a final decision on the petition but urges the agency to act promptly. New York v. EPA, No. 19-01231 (D.C. Cir.)

Sep. 15, 2020 The Ozone Transportation Commission (OTC), a group of twelve eastern states and DC, urges EPA to respond to its earlier petition asking EPA to require Pennsylvania to include additional control measures for coal-fired power plants in its State Implementation Plan. EPA was supposed to hold a hearing on the request by Sep. 4, but announced it was postponing the hearing “until after a notice with additional information is published in the Federal Register.”  

Jan. 5, 2021 The Tenth Circuit grants EPA’s request to revisit its approval of Colorado’s plan to limit excessive ozone pollution from traveling to downwind states. EPA submitted its request after the DC Circuit issued a decision in Maryland v. EPA, finding that the agency improperly estimated Maryland’s pollution contributions by using a compliance date that was too far in the future. Center for Biological Diversity v. EPA et al., No. 20-9560 (10th Cir.).