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Why it Matters
The Cross-State Air Pollution Rule (CSAPR) implements the Clean Air Act’s “good neighbor” provision and requires upwind states to reduce interstate pollution of soot and smog contributors, sulfur dioxide (SO2) and oxides of nitrogen (NOx). The rule ensures downwind states can meet the National Ambient Air Quality Standards (NAAQS) for particulate matter and ozone.
Downwind states rely on this provision to protect their residents’ health. States are already required to address interstate pollution in their State Implementation Plans for implementing the NAAQS. CSAPR makes states pay attention to pollution that will significantly contribute to problems for downwind states in meeting the NAAQS.
A state may also file a petition with EPA under Clean Air Act section 126 asking EPA to step in and regulate pollution from sources in another state when that pollution is impairing interstate air quality. For more information, see our page on Clean Air Act 126 Petitions.
During the Trump administration, coalitions of environmental groups and states repeatedly (and often successfully) sued EPA for either failing to adopt federal Good Neighbor plans for upwind states in violation of the Clean Air Act’s Good Neighbor Provisions, or for approving state implementation plans that underestimate the effects of pollution on downwind states.
Groups also successfully sued the Trump EPA for failing to adopt sufficiently stringent standards updating the CSAPR. On Dec. 6, 2018, the Trump EPA published a final rule, called the “Close Out” Rule, in which EPA decided not to require further emissions reductions from upwind states beyond those required under the 2016 CSAPR Update. EPA made this determination despite acknowledging that downwind states would not be able to meet the 2008 ozone NAAQS requirements until 2023 – two years after the NAAQS deadline. The DC Circuit ultimately rejected the Close-Out Rule, finding EPA did not implement stringent enough rules to deal with cross-state air pollution affecting downwind states. On March 15, 2021, the Biden EPA issued a final rule updating the CSAPR for the 2008 ozone NAAQS.
May 12, 2005 EPA promulgates the Clean Air Interstate Rule to address interstate pollution that impairs downwind states’ ability to meet the NAAQS. Under the rule, affected states must reduce their emissions. They may choose to require facilities in their state to participate in EPA-administered cap and trade programs to meet the emissions reduction targets.
July 11, 2008 The D.C. Circuit invalidates the Clean Air Interstate Rule, finding that it did not adequately address interstate pollution’s impact on downwind air quality.
Aug. 8, 2011 EPA promulgates the Cross-State Air Pollution Rule (CSAPR) to address the deficiencies in the Clean Air Interstate Rule that the D.C. Circuit identified in 2008. In CSAPR, EPA allocates emissions budgets for sulfur dioxide (SO2) and oxides of nitrogen (NOx) to each state. EPA then uses Federal Implementation Plans to implement the emissions reductions, again including regional trading programs.
April 29, 2014 The Supreme Court upholds CSAPR in EPA v. EME Homer City Generation.
Jan. 1, 2015 EPA begins implementing Phase 1 of CSAPR. Phase 2 is scheduled to begin Jan. 1, 2017. Emissions limits become stricter for some states in Phase 2.
Oct. 26, 2016 EPA publishes the 2016 CSAPR Update, which goes into effect Dec. 26, 2016. This rule promulgates Federal Implementation Plans (FIPs) for states that have not incorporated CSAPR into their State Implementation Plans (SIPs). It requires emissions reductions from power plants in the affected states. EPA also adjusts some of the Phase 2 NOx limits.
Nov. 22, 2016 Sixteen lawsuits are filed to challenge the Oct. 2016 CSAPR Update. The consolidated case is Wisconsin v. EPA, No. 16-406 (D.C. Cir.).
Jan. 19, 2017 New York, Rhode Island, New Hampshire, Vermont, Massachusetts, and Maryland file a motion to intervene in Wisconsin v. EPA in support of the 2016 CSAPR Update.
Feb. 24, 2017 President Trump signs the Regulatory Reform Executive Order directing EPA to “evaluate existing regulations… and make recommendations to the agency head regarding their repeal, replacement, or modification…). EPA may review CSAPR under that broad directive.
July 10, 2018 EPA issues a proposed determination that the CSAPR Update fully addresses upwind states’ “good neighbor” obligations for the 2008 NAAQS.
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.
Dec. 6, 2018 EPA publishes a final rule announcing its determination that the 2016 CSAPR Update fully satisfies “good neighbor” obligations for the 2008 ground-level ozone NAAQS. This is known as the “Close-Out” Rule, because EPA will not require further emissions reductions from upwind states. EPA acknowledges that downwind states will not be able to meet the 2008 ozone NAAQS requirements until 2023 – two years after the NAAQS deadline.
January 30, 2019 A coalition of six states asks the DC Circuit to review the CSAPR Close-Out Rule. New York v. EPA, No. 19-1019 (D.C. Cir.). The lawsuit is brought by New York, Maryland, Connecticut, New Jersey, Massachusetts and Delaware, all downwind states to coal plants such as Homer City Generation in Pennsylvania. A coalition of environmental groups also file a petition for review. Downwinders at Risk v. EPA, No. 19-1020 (D.C. Cir).
Sep. 13, 2019 The D.C. Circuit largely upholds the 2016 CSAPR Update, except for a provision that allows upwind states to continue to pollute downwind states past the statutory deadline for downwind states to comply with the NAAQS. This portion of the rule is sent back to EPA for review. Wisconsin v. EPA, No. 16-1406 (D.C. Cir.).
Oct. 1, 2019 The DC Circuit rejects EPA’s CSAPR Close-Out Rule, finding that EPA has not implemented stringent enough rules to deal with cross-state air pollution affecting downwind states. New York v. EPA, No. 19-1019 (D.C. Cir.).
Oct. 28, 2019 The deadline passes for EPA to appeal the two D.C. Circuit decisions from Sep. and Oct. 2019 ordering the agency to revisit its Cross-State Air Pollution Rule update and the Close-Out Rule. This means EPA is accepting the decisions and will need to make changes to those rules. New York v. EPA, No. 19-1019 and Wisconsin v. EPA, No. 16-1406 (D.C. Cir.).
Oct. 29, 2019 New Jersey and Connecticut sue EPA for failing to meet its April 1, 2019 deadline to take action on Pennsylvania and Virginia for their failure to file Good Neighbor State Implementation Plans. Pennsylvania and Virginia are both upwind of New Jersey and Connecticut. New Jersey v. Wheeler, No. 1:19-cv-03247 (D.D.C).
Nov. 22, 2019 EPA releases a final rule finding that seven states (Maine, New Mexico, Pennsylvania, Rhode Island, South Dakota, Utah, and Virginia) failed to submit complete state implementation plans to limit interstate pollution that affects downwind states’ ability to meet the 2015 ozone NAAQS. If EPA does not approve interstate transport state implementation plans for these states within two years of making this determination, EPA will be required to promulgate federal implementation plans.
Jan. 3, 2020 Following EPA’s actions in November, New Jersey, Connecticut, and New York voluntarily dismiss their lawsuit seeking to compel EPA to find that Pennsylvania and Virginia failed to submit Good Neighbor State Implementation Plans.
Jan. 16, 2020 New York and Connecticut sue EPA seeking to compel the agency to promulgate federal implementation plans for sources in five upwind states (Illinois, Michigan, Pennsylvania, Virginia, and West Virginia) whose state plans failed to fully comply with the Good Neighbor provision. New York v. Wheeler, No. 1:20-cv-00419 (S.D.N.Y).
Feb. 7, 2020 A coalition of environmental groups sues EPA seeking to compel the agency to adopt federal Good Neighbor plans for twenty upwind states. Downwinders at Risk v. Wheeler, No. 1:20-cv-00349 (D.D.C.).
Feb. 14, 202 New York and Connecticut voluntarily dismiss their Jan. 16, 2020 lawsuit. New York v. Wheeler, No. 1:20-cv-00419 (S.D.N.Y).
Feb. 19, 2020 New Jersey, Connecticut, Delaware, New York, Massachusetts, and New York City file a lawsuit seeking to compel EPA to adopt federal Good Neighbor plans for seven upwind states (Illinois, Indiana, Michigan, Ohio, Pennsylvania, Virginia, and West Virginia). New Jersey v. Wheeler, No. 20-cv-1425 (S.D.N.Y.). The lawsuit is similar to New York v. Wheeler, No. 1:20-cv-00419 (S.D.N.Y).
July 28, 2020 Judge Koeltl rules in favor of the states in New Jersey v. Wheeler, No. 20-cv-1425 (S.D.N.Y.). The court sets a March 15, 2021 deadline for EPA to finalize plans for upwind states that meet the Clean Air Act’s “good neighbor” requirements.
Sept. 15, 2020 EPA sends the proposed revisions to the CSAPR update rule to the White House Office of Information and Regulatory Affairs for review. This proposal is in response to the D.C. Circuit’s ruling in Wisconsin v. EPA, No. 16-1406.
Oct. 30, 2020 EPA issues a proposed rule in response to the D.C. Circuit’s remand in Wisconsin v. EPA, No. 16-1406, to resolve 21 states’ outstanding interstate ozone transport obligations under the 2008 ozone NAAQS.
Oct. 30, 2020 The Center for Biological Diversity (CBD) files an opening brief in its suit to vacate EPA’s approval of Colorado’s ozone SIP, arguing that the plan underestimates pollution effects on downwind states Utah and Mexico. CBD also argues that EPA arbitrarily included emissions reductions from rules EPA has repealed or is attempting to repeal, including the Clean Power Plan. Center for Biological Diversity v. EPA, No. 20-09560 (10th Cir.).
Jan. 12, 2021 A coalition of northeastern states sues EPA over the agency’s failure to “timely act” within the required 12-month timeframe on upwind states’ plans to comply with the 2015 ozone NAAQS under the Clean Air Act’s Good Neighbor Provision. State of New York et al. v. Wheeler, No. 1:21-cv-252 (S.D.N.Y.).
Early Biden Actions
Jan. 20, 2021 In his Public Health & Environment Executive Order, President Biden directs EPA to consider promulgating a Federal Implementation Plan for states that have failed to submit state implementation plans satsifying the 2008 ozone NAAQS, specifically California, Connecticut, New York, Pennsylvania, and Texas.
April 8, 2021 WildEarth Guardians sue EPA for not making a determination that Colorado failed to submit a plan to address air pollution in the Denver Metro/North Front Range area by an August 2020 deadline. The area is in “serious” nonattainment with the 2008 ozone NAAQS. WildEarth Guardians v. Regan, No. 21-994 (D. Colo.).
April 30, 2021 EPA publishes a final rule updating the CSAPR for the 2008 ozone NAAQS. The rule regulates the release of nitrogen oxides in twelve states, and allows emissions credit trading. The rule issues new or amended FIPs for New York and Pennsylvania, and accepts Texas’ FIP promulgated under the CSAPR Update as satisfying the 2008 ozone NAAQS requirements.
June 4, 2021 EPA publishes a final rule correcting the preamble to the CSAPR Update for the 2008 ozone NAAQS.
June 25, 2021 The Midwest Ozone Group files a petition for review of EPA’s 2021 CSAPR Update with the D.C. Circuit. Midwest Ozone Group v. EPA, No. 21-01146 (D.C. Cir.).