Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99105 

(6) UL 60079–28, Standard for Safety 

for Explosive Atmospheres—Part 28: 

Protection of Equipment and 

Transmission Systems Using Optical 

Radiation, Second Edition, Dated 

September 15, 2017, including revisions 

through December 7, 2021 (ANSI/UL 

60079–28); into § 18.101. 

Note 1 to § 18.102: The voluntary 

consensus standards listed in this section 

may also be obtained from the American 

National Standards Institute (ANSI), 1899 L 

Street NW, 11th Floor, Washington, DC 

20036, phone: (202) 293–8020; website: 

www.ansi.org. 

§ 18.103 Review and update of applicable 

voluntary consensus standards. 

(a) MSHA will review more recent 

editions of voluntary consensus 

standards listed in § 18.102 to 

determine whether they can be used in 

their entirety and without modification, 

in lieu of the requirements in subparts 

B through E of this part. 

(b) MSHA may review voluntary 

consensus standards not approved for 

incorporation by reference (IBR) in 

§ 18.102 to determine whether such 

standards are suitable for gassy mining 

environments and whether they provide 

protection against fire or explosion, if 

substituted in their entirety and without 

modification, in lieu of the requirements 

in subparts B through E of this part. 

(c) Following such review and 

determination, MSHA will use the 

appropriate rulemaking process to 

amend the list of voluntary consensus 

standards approved for IBR in lieu of 

the requirements in subparts B through 

E of this part. 

PART 740—COAL MINE DUST 

SAMPLING DEVICES 

■ 6. The authority citation for part 74 

continues to read as follows: 

Authority: 30 U.S.C. 957. 

§ § 74.5 and 74.11 [Amended] 

■ 7. In §§ 74.5(b) and 74.11(d), remove 

‘‘30 CFR 18.68’’ and add in its place the 

term ‘‘30 CFR part 18.’’ 

[FR Doc. 2024–28315 Filed 12–9–24; 8:45 am] 

BILLING CODE 4520–43–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 52, 75, 78, and 97 

[EPA–HQ–OAR–2021–0668; FRL–8670.5– 

02–OAR] 

RIN 2060–AW47 

Federal ‘‘Good Neighbor Plan’’ for the 

2015 Ozone National Ambient Air 

Quality Standards; Notice on Remand 

of the Record of the Good Neighbor 

Plan To Respond to Certain Comments 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Notice; supplemental response 

to comments. 

SUMMARY: The Environmental Protection 

Agency (EPA) is addressing certain 

comments that were submitted on the 

proposed Good Neighbor Plan that the 

Supreme Court of the United States 

concluded the EPA had likely not 

sufficiently addressed in the final Good 

Neighbor Plan. The EPA is providing a 

fuller explanation of its reasoning at the 

time of its action in response to these 

comments. The Good Neighbor Plan 

addressed 23 states’ obligations to 

eliminate significant contribution to 

nonattainment or interference with 

maintenance of the 2015 ozone national 

ambient air quality standards (NAAQS), 

pursuant to the ‘‘good neighbor’’ 

provision of the Clean Air Act (CAA or 

Act). On September 12, 2024, the D.C. 

Circuit Court of Appeals remanded the 

record of the Good Neighbor Plan to the 

EPA to permit the Agency to further 

respond to comments related to the 

Good Neighbor Plan’s operation if one 

or more upwind States were no longer 

participating. In this document, the EPA 

responds to the comments by more fully 

explaining why the Good Neighbor Plan 

appropriately defines each state’s 

obligations, regardless of the status of 

the rule in other states, and can be 

implemented without modification in 

any individual state or combination of 

states covered by the rule. 

DATES: December 10, 2024. 

ADDRESSES: The EPA has established a 

docket for this document under Docket 

ID No. EPA–HQ–OAR–2021–0668. All 

documents in the docket are listed on 

the https://www.regulations.gov 

website. Although listed in the index, 

some information is not publicly 

available, e.g., Confidential Business 

Information (CBI) or other information 

whose disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available electronically through https:// 

www.regulations.gov. 

FOR FURTHER INFORMATION CONTACT: 

Gwyndolyn Sofka, OAQPS–AQPD 

(C541–04), Environmental Protection 

Agency, 109 TW Alexander Dr, 

Research Triangle Park, NC 27711; 

telephone number: (919)–541–5121; 

email address: sofka.gwyndolyn@

epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document ‘‘we,’’ 

‘‘us,’’ and ‘‘our’’ refer to the EPA. 

I. General Information 

The EPA is responding to a set of 

comments that together raise a question 

regarding the method by which the 

Agency developed the Good Neighbor 

Plan (88 FR 36654; June 5, 2023). 

Namely: would the conclusions the EPA 

reached regarding states’ obligations 

under CAA section 110(a)(2)(D)(i)(I) for 

the 2015 ozone NAAQS have been 

different, had the rule been promulgated 

for, or if it covered, a smaller or 

different group of states than the 23 

states that were included in that the 

rule? In short, for reasons that are 

provided in the record of the Good 

Neighbor Plan itself and elaborated 

upon in this document, the answer to 

that question is no. The EPA applied its 

4-step interstate transport analytical 

framework in the Good Neighbor Plan to 

determine each included state’s 

obligations. That framework, which 

accounts for the multistate ‘‘collective 

contribution’’ nature of ozone problems 

throughout the United States, 

nonetheless defines the amount of 

emissions from each state that 

constitutes ‘‘significant contribution to 

nonattainment or interference with 

maintenance’’ of the NAAQS in other 

states and implements programs to 

prohibit those emissions through federal 

implementation plans (FIPs) 

promulgated for each state accordingly. 

As the Good Neighbor Plan itself 

indicated, the EPA’s methodology is 

designed to be applicable in any state 

that may become subject to a federal 

plan to address its ‘‘significant 

contribution’’ to other states’ ozone 

problems for the 2015 ozone NAAQS; it 

provides an equitable and efficient 

solution to a ‘‘thorny causation 

problem,’’ EME Homer City, 572 U.S. 

489, 514 (2014), by holding any linked 

state’s largest industrial NOX-emitting 

sources to widely achievable emissions 

levels, and ensures fairness among 

states by not being dependent on the 

order in which they are addressed. 

By issuing this document, the Agency 

is addressing a particular issue that the 


khammond on DSK9W7S144PROD with RULES
99106 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

1Federal ‘‘Good Neighbor Plan’’ for the 2015 

Ozone National Ambient Air Quality Standards, 88 

FR 36654 (June 5, 2023). 

2Air Plan Disapprovals; Interstate Transport of 

Air Pollution for the 2015 8-Hour Ozone National 

Ambient Air Quality Standards, 88 FR 9336 

(February 13, 2023) (‘‘SIP Disapproval’’); Findings 

of Failure to Submit a Clean Air Act Section 110 

State Implementation Plan for Interstate Transport 

for the 2015 Ozone National Ambient Air Quality 

Standards (NAAQS), 84 FR 66612 (December 5, 

2019) (including Pennsylvania, Utah, and Virginia). 

3Federal ‘‘Good Neighbor Plan’’ for the 2015 

Ozone National Ambient Air Quality Standards; 

Response to Judicial Stays of SIP Disapproval 

Action for Certain States, 88 FR 49295 (July 31, 

2023); Federal ‘‘Good Neighbor Plan’’ for the 2015 

Ozone National Ambient Air Quality Standards; 

Response to Additional Judicial Stays of SIP 

Disapproval Action for Certain States, 88 FR 67102 

(September 29, 2023). 

4The Good Neighbor Plan’s emissions reduction 

requirements apply to all emissions sources 

meeting the Good Neighbor Plan’s applicability 

criteria within the borders of each covered state, 

including sources in Indian country within the 

borders of the state. See 88 FR 36690. 

5Orders, Utah v. EPA, No. 23–1157 (D.C. Cir. 

September 25, 2023, and October 11, 2023); see also 

Order, Utah v. EPA, No. 23–1157 (D.C. Cir. 

December 4, 2023) (denying additional stay 

motions). 

6Ohio v. EPA, No. 23A349 (U.S. docketed 

October 18, 2023) (other named applicants are 

Indiana and West Virginia); Kinder Morgan, Inc. v. 

EPA, No. 23A350 (U.S. docketed October 18, 2023) 

(other named applicants are Enbridge (U.S.) Inc., 

TransCanada PipeLine USA Ltd., Interstate Natural 

Gas Association of America, and American 

Petroleum Institute); American Forest & Paper 

Association v. EPA, No. 23A351 (U.S. docketed 

October 18, 2023) (other named applicants are 

America’s Power, Associated Electric Cooperative, 

Inc., Deseret Power Electric Cooperative, Midwest 

Ozone Group, National Mining Association, 

National Rural Electric Cooperative Association, 

U.S. Supreme Court preliminarily found 

had been raised by commenters with 

reasonable specificity, but which the 

Court considered the Agency had likely 

failed to adequately address when it 

originally promulgated the rule. See 

Ohio v. EPA, 144 S. Ct. 2040 (2024) 

(granting applications to stay 

enforcement of the Good Neighbor Plan 

pending judicial review). This 

document summarizes the relevant 

comments identified by the Supreme 

Court and, after summarizing our initial 

responses to these comments in section 

II.B., provides a fuller response in 

section III. of this document concerning 

how these comments relate or could be 

read as relating to the question of the 

Good Neighbor Plan’s application and 

severability on a state-by-state basis, 

consolidating material and discussions 

from the existing administrative record 

at the time the EPA issued the action. 

To provide the most complete possible 

response to the issues identified by the 

Supreme Court, the Agency has 

considered these comments from all 

angles, even considering arguments that 

are not evident on the face of the 

comments themselves. For this reason, 

we do not concede that each of the 

topics discussed in this document was 

in fact raised with ‘‘reasonable 

specificity’’ by the commenters 

themselves, as required by CAA section 

307(d)(7)(B), but the Agency views it to 

be appropriate in light of the Court’s 

preliminary findings in Ohio to address 

all of the issues commenters potentially 

could be seen to have raised, to ensure 

a thorough and complete response to the 

commenters’ concerns. 

In responding to these comments, the 

Agency is relying solely on the 

information and data available in the 

record at the time the Good Neighbor 

Plan was signed by the EPA 

Administrator and promulgated on 

March 15, 2023 (88 FR 36654; June 5, 

2023). See CAA section 307(d)(6)(C) 

(limiting the basis for CAA rules issued 

under section 307(d) to ‘‘information 

[and] data . . . placed in the docket as 

of the date of [ ] promulgation’’). The 

purpose of this document is not to 

supplement the record of the Good 

Neighbor Plan with new findings, 

information, data, or new record 

support, but rather only to consolidate 

the existing material in the record to 

more fully respond to the relevant 

comments received during the public 

comment period following proposal of 

the Good Neighbor Plan. In this 

document, we provide an ‘‘amplified 

articulation’’ of the methodology 

underlying the design of the Good 

Neighbor Plan to more fully explain 

why, at the time the EPA issued the 

Good Neighbor Plan, it understood the 

Good Neighbor Plan’s requirements to 

reasonably function on a state-by-state 

basis and therefore to be severable by 

state. See Dep’t of Homeland Sec. v. 

Regents of the Univ. of Cal., 591 U.S. 1, 

20–21 (2020) (quoting Alpharma, Inc. v. 

Leavitt, 460 F. 3d 1, 5–6 (D.C. Cir. 

2006)). 

Thus, in this document, we compile 

and present together discussions and 

components of the analysis that are 

already in the record and explain how 

they relate to one another and together 

demonstrate that the Good Neighbor 

Plan fulfills the statutory mandate for 

each state regardless of the number of 

states included in the rule at any given 

time. 

As described in more detail in section 

II.A. of this document, following the 

Supreme Court’s opinion in Ohio, the 

EPA sought a voluntary partial remand 

of the Good Neighbor Plan from the D.C. 

Circuit to provide the explanation that 

the Supreme Court concluded was 

likely lacking in the Good Neighbor 

Plan. The D.C. Circuit ordered ‘‘that the 

record be remanded to permit the 

Environmental Protection Agency to 

further respond to comments in the 

record.’’ State of Utah et al. v. EPA, No. 

23–1157 (D.C. Cir. September 12, 2024). 

The statutory authority for the Good 

Neighbor Plan is provided by the CAA 

as amended (42 U.S.C. 7401 et seq.). The 

most relevant portions of CAA section 

110 are subsections 110(a)(1), 110(a)(2) 

(including 110(a)(2)(D)(i)(I)), and 

110(c)(1). For further information, see 

section II.C. of the preamble for the 

Good Neighbor Plan, 88 FR 36667–68. 

II. Background 

A. Procedural History 

On March 15, 2023, in accordance 

with CAA sections 110(a)(2)(D)(i)(I) and 

110(c)(1), the EPA promulgated the 

Good Neighbor Plan, a rule determining 

the good neighbor obligations of 23 

states with respect to the 2015 ozone 

NAAQS and establishing for these states 

federal implementation plans (FIPs) for 

emissions sources in these states to 

address each state’s obligations by 

reducing emissions of nitrogen oxides 

(NOX), an ozone precursor.1 Prior to 

promulgating the Good Neighbor Plan, 

the EPA had disapproved state 

implementation plans for 21 of those 

states and had found that several states 

had failed to submit complete plans— 

predicates to EPA’s authority to 

promulgate FIPs for those states.2

Following the Good Neighbor Plan’s 

promulgation, in response to judicial 

orders partially staying the SIP 

Disapproval as to several states, the EPA 

issued two sets of interim amendments 

(referred to here as the First and Second 

Interim Final Rules) staying the Good 

Neighbor Plan’s effectiveness for 

emissions sources in those states 

pending the resolution of judicial 

review of that action and further EPA 

rulemaking.3 As modified by the First 

and Second Interim Final Rules, the 

Good Neighbor Plan’s FIPs applied to 

electric generating units (EGUs) within 

the borders of Illinois, Indiana, 

Maryland, Michigan, New Jersey, New 

York, Ohio, Pennsylvania, Virginia, and 

Wisconsin and to non-EGU sources 

within the borders of nine of the same 

ten states (all except Wisconsin) as well 

as California.4

In October 2023, after the United 

States Court of Appeals for the District 

of Columbia Circuit (D.C. Circuit) 

denied motions to stay the Good 

Neighbor Plan pending judicial review,5

four sets of parties submitted emergency 

applications to the United States 

Supreme Court seeking a stay of some 

or all of the Good Neighbor Plan’s 

requirements.6 In an opinion issued on 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99107 

Ohio Valley Electric Corporation, Portland Cement 

Association, and Wabash Valley Power Alliance); 

United States Steel Corporation v. EPA, No. 23A384 

(U.S. docketed October 31, 2023). 

7Ohio v. EPA, 144 S. Ct. 2040, 2058 (2024). 

8See also ‘‘Letter Enclosure: The EPA’s Basis for 

Partially Denying Petitions for Reconsideration of 

the Good Neighbor Plan on Ground Related to 

Judicial Stays of the SIP Disapproval Act as to 12 

States,’’ available at https://www.epa.gov/CrossState-Air-Pollution/response-four-petitionsreconsideration and at https://www.regulations.gov/ 

document/EPA-HQ-OAR-2021-0668-1255. 

9We have focused specifically on the comments 

that the Supreme Court identified in Ohio v. EPA. 

While other commenters raised issues similar to 

these comments, these comments present a 

representative set of perspectives on those issues 

that the Supreme Court viewed as most closely 

related to the question of the Good Neighbor Plan’s 

severability by state. 

June 27, 2024 (referred to here as the 

Stay Order), the Supreme Court granted 

the emergency applications and ordered 

that ‘‘[e]nforcement of EPA’s rule 

against the applicants shall be stayed’’ 

while judicial review of the Good 

Neighbor Plan on the merits proceeds, 

first in the D.C. Circuit and then 

potentially in the Supreme Court.7

The Court found that, with respect to 

the ‘‘explanation why the number and 

identity of participating States does not 

affect what measures maximize costeffective downwind air-quality 

improvements,’’ the stay applicants ‘‘are 

likely to prevail on their argument that 

EPA’s final rule was not ‘reasonably 

explained,’ that the agency failed to 

supply ‘a satisfactory explanation for its 

action[,]’ and that it instead ignored ‘an 

important aspect of the problem’ before 

it’’. Ohio v. EPA, 144 S. Ct. 2040, 2054 

(2024) (citations omitted). The Court 

focused in particular on the fact that the 

Good Neighbor Plan’s FIPs had been 

stayed in several states pending judicial 

review of the EPA’s disapproval of those 

states’ state implementation plan (SIP) 

submissions. 144 S. Ct. at 2051–52. Stay 

applicants had argued that the ‘‘EPA’s 

plan rested on an assumption that all 23 

upwind States would adopt emissionsreduction tools up to a ‘uniform’ level 

of ‘costs’ to the point of diminishing 

returns’’ and the EPA had not explained 

how the rule was substantiated for a 

smaller number of states. Id. at 2053 

(citations omitted). The Court 

preliminarily interpreted several 

comments filed on the proposed Good 

Neighbor Plan as raising this concern, 

i.e., that if a different number or 

grouping of states were subject to the 

EPA’s FIPs promulgated in the Good 

Neighbor Plan rulemaking, then the 

EPA’s cost-effectiveness analysis would 

have changed, and therefore the 

obligations would or could be different 

for the remaining states. Id. at 2050–51. 

The Court did not conclude that the 

EPA’s methodology was unlawful, or 

that petitioners were correct in their 

assessment that the Good Neighbor 

Plan’s obligations could change 

depending on the number or group of 

states subject to it. Rather, the Court 

preliminarily found that the EPA had 

failed to adequately respond to the 

relevant comments and thus the rule 

was likely not ‘‘reasonably explained.’’ 

Id. at 2054. The Court noted that the 

rule’s ‘‘severability’’ discussion did not 

adequately address the issue, since that 

discussion, in itself, contained no 

supporting analysis. Id. at 2054–55. 

On March 27, 2024, several months 

before the Supreme Court issued this 

ruling, the EPA partially denied several 

petitions for reconsideration of the Good 

Neighbor Plan objecting to the rule on 

the basis that it had been stayed in 

certain states and was no longer lawful 

or workable in the remaining states, as 

well as objecting that the rule should 

not have been published at all following 

judicial stays of the SIP Disapproval as 

to certain states. The EPA’s ‘‘basis for 

denial’’ addressed both issues and 

determined that these objections were 

not ‘‘centrally relevant’’ because, after 

examining the objections in detail, the 

EPA concluded they failed to establish 

that the rule should be revised. See 89 

FR 23526 (April 4, 2024) (providing 

notice of issuance of the partial denial).8

The Supreme Court declined to consider 

the EPA’s Denial in evaluating the 

applications for stay. See 144 S. Ct. at 

2068 n.11. 

Following the Supreme Court’s 

decision granting the applications to 

stay enforcement of the Good Neighbor 

Plan, the EPA implemented the Court’s 

stay of the effectiveness of the Good 

Neighbor Plan’s requirements for the 

sources that would have been subject to 

the rule pursuant to the 23 states’ FIPs 

originally promulgated, pending judicial 

review. See 89 FR 87960 (November 6, 

2024). In addition, the EPA sought a 

voluntary partial remand of the Good 

Neighbor Plan. The D.C. Circuit granted 

a remand of the record of the rule so 

that the EPA might respond to the 

comments related to the rule’s 

appropriateness for each state and 

operation. State of Utah et al. v. EPA, 

No. 23–1157 (D.C. Cir. September 12, 

2024). The D.C. Circuit retains 

jurisdiction of the case, has placed the 

case in abeyance pending further order 

of the court, and has directed the parties 

to file motions to govern future 

proceedings in the case within 30 days 

after completion of this remand or 

December 30, 2024, whichever is earlier. 

Id. 

The following section, II.B. of this 

document, summarizes the comments 

identified by the Supreme Court as 

relevant to the issue of the Good 

Neighbor Plan’s operation if one or more 

upwind States were no longer 

participating and provides a summary of 

the EPA’s responses to these comments 

in the Good Neighbor Plan with 

citations to the record.9 The EPA does 

not intend to reopen its prior response 

to those comments through this 

document by summarizing those prior 

responses. Section III. of this document 

provides a fuller explanation in 

response to a specific issue identified by 

the Supreme Court derived from these 

comments: whether the Good Neighbor 

Plan would lawfully define and 

implement good neighbor obligations 

for any particular state if it were not in 

effect for some other state or states. As 

the EPA originally concluded based on 

the information in the record at the time 

of promulgation, the Good Neighbor 

Plan appropriately defines each state’s 

obligations on an individual basis and is 

severable on a state-by-state basis. See 

88 FR 36693. 

B. Summary of Comments Identified by 

the Supreme Court and Citation to Prior 

Responses to Comments 

Comment category 1 (SIP/FIP 

sequencing): Multiple commenters (the 

Missouri Department of Natural 

Resources (MO DNR), the Louisiana 

Department of Environmental Quality 

(LA DEQ), and the Texas Commission 

on Environmental Quality (TX CEQ)) 

expressed concern that the EPA had 

proposed FIPs prior to finalization of 

the SIP disapprovals for states included 

in the FIP rulemaking, without knowing 

which states would ultimately be 

covered by a FIP. Commenters state that 

this kept the EPA from being able to 

receive and consider the technical, 

procedural, and legal issues that they 

identified in their comments. 

Commenters state that the proposed 

FIPs presume the result of the proposed 

disapproval of SIPs even though the 

comment period for the SIP Disapproval 

action was ongoing at the time of the 

proposed FIPs. 

Commenters (LA DEQ and TX CEQ) 

requested that the EPA withdraw both 

the proposed FIPs for their states and 

the proposed SIP disapproval so that 

both states could have a further 

opportunity to show that their 

respective SIPs address their supposed 

significant contribution to 

nonattainment or interference with 

maintenance in downwind states. One 

commenter (MO DNR) requested that 

the EPA withdraw the proposed FIP for 


khammond on DSK9W7S144PROD with RULES
99108 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

10See the Missouri Department of Natural 

Resources June 17, 2022, comment letter Docket Id 

No. EPA–HQ–OAR–2021–0668–0289, at 4. 

11See id. at 3. 

12See the Louisiana Department of 

Environmental Quality June 21, 2022, comment 

letter Docket Id No. EPA–HQ–OAR–2021–0668– 

0365, at 2. 

13See the Texas Commission on Environmental 

Quality June 21, 2022, comment letter Docket Id No. 

EPA–HQ–OAR–2021–0668–0505, at 1. 

14 Id. at 2. 

15See, e.g., 87 FR 20036, 20038, 20039, 20040 

n.8, 20041, 20044, 20045, 20051 n.39, 20051–2–52, 

20058, 20067 n.115, 20073, and 20140 (April 6, 

2022); 88 FR 36654, 36656, 36657, 36658, 36659 

n.9, 36659, 36662, 36664, 36668 n.41 & 44, 36668/ 

3, 36669, 36673/2, 36688 n.99, and 36689 (June 5, 

2023). 

16Available in the docket at https://

www.regulations.gov/document/EPA-HQ-OAR2021-0668-1127. 

Missouri and other states so that the 

EPA can consider and respond to all 

comments received on the SIP 

Disapproval action. The commenter 

goes on to request that the EPA respond 

to all comments on the proposed 

disapproval of the Missouri SIP in the 

final action for the Good Neighbor Plan 

if it does not withdraw the proposed 

FIP, as the SIP Disapproval action and 

the proposed FIP are ‘‘inextricably 

linked.’’ 10 Relevant portions of the 

comment are included immediately 

below. 

Missouri Department of Natural 

Resources 

EPA is now proposing good neighbor FIPs, 

which are the subject of this comment letter, 

before even finalizing the SIP disapprovals 

for Missouri and numerous other states. The 

Air Program and several other entities 

submitted adverse comments on EPA’s 

proposed SIP disapproval for Missouri’s 2019 

Good Neighbor SIP. Those comments were 

all submitted after the publication of EPA’s 

proposed good neighbor FIP in the Federal 

Register. Therefore, EPA did not even give 

itself a chance to receive, and much less, 

consider all the technical, legal, and 

procedural issues for the proposed 

disapproval that were identified in those 

comments before it moved forward with the 

proposed FIP. It follows then, that EPA’s 

proposed FIP is extremely premature, and 

EPA should withdraw the proposal and be 

obligated to consider and respond to all of 

the comments it received on the proposed 

disapprovals before it can propose FIPs for 

these states.11

Louisiana Department of Environmental 

Quality 

The EPA’s proposed FIP presumed the 

result of its proposed disapproval of 

Louisiana’s SIP submission, even though 

public notice and comment were ongoing. 

EPA must consider comments received on its 

proposed actions. The EPA cannot consider 

LDEQ’s comment on the proposed 

disapproval of the SIP in good faith, when it 

has already proposed a FIP prior to the close 

of the comment period . . . 

Louisiana requests that this proposed FIP 

be withdrawn, allowing the state to either 

prove its original SIP submittal through 

modeling or to provide specific enforceable 

measures to adequately prohibit the 

contribution of pollution to downwind 

states.12

Texas Commission on Environmental 

Quality 

Based on the numerous technical and legal 

errors discussed in our comments, the TCEQ 

respectfully requests that the EPA withdraw 

its proposed FIP, either in whole, or in part 

as it pertains to Texas. In the alternative, the 

TCEQ respectfully requests that the EPA 

address and remedy the numerous technical 

and legal errors identified by the TCEQ 

...13 The inclusion of Texas in the 

proposed FIP is dependent on the EPA 

finalizing its proposed disapproval of the 

transport SIP that Texas timely submitted for 

the 2015 ozone NAAQS.14

Citations to previous responses: The 

EPA explained that FIPs can be 

proposed before final action is taken on 

SIP disapprovals, because the statute 

provides that the EPA is required to 

promulgate a FIP ‘‘at any time within 2 

years’’ of a SIP disapproval or a finding 

of failure to submit. This statutory 

sequence necessarily permits the 

proposal of a FIP before the finalization 

of a SIP disapproval. See 88 FR 36689 

(citing CAA section 110(c)(1); EME 

Homer City, 572 U.S. 489, 509). The 

EPA was clear in both the proposed and 

final rulemaking documents that it was 

issuing FIPs on a state-by-state basis, 

with adjustments in the scope of states 

covered by the Good Neighbor Plan’s 

uniform regulatory programs occurring 

from proposal to final based on changes 

in the underlying analytics, similar to 

changes in state coverage that had 

occurred under prior good neighbor 

rulemakings.15 The EPA explained that 

it had predicate FIP authority for each 

of the 23 covered states at the time of 

signature and promulgation of the Good 

Neighbor Plan. See 88 FR 36688–89 and 

the Good Neighbor Plan Response to 

Comments (RTC) Document at 6–8.16

The EPA explained the timing of its 

action to promulgate FIPs in relation to 

the need to address good neighbor 

obligations as expeditiously as 

practicable, and to the extent possible 

by the 2023 ozone season, 88 FR 36690, 

and explained why we would not delay 

our action to afford states additional 

opportunities to develop new 

submissions or instead issue a call for 

SIP revisions, though we noted that 

states remain free to develop and submit 

SIP revisions at any time. See Good 

Neighbor Plan RTC at 12–15. The EPA 

further explained its reasoning 

concerning the sequencing of its actions 

and that this sequencing did not 

prejudice the Agency’s evaluation of 

states’ SIP submissions in the separate 

SIP Disapproval action. See Good 

Neighbor Plan RTC at 149–51. The EPA 

noted that it was not finalizing its 

proposed FIPs for several states, and the 

EPA acknowledged that several states 

remained to be addressed for which it 

either lacked predicate authority to 

issue a FIP or because further 

rulemaking proceedings were 

appropriate. 88 FR 36658. The EPA 

explained that specific technical or legal 

objections to the SIP Disapproval were 

addressed in that action and were out of 

scope of the Good Neighbor Plan. Id. at 

144–45, 155. 

Comment category 2 (potential for 

new modeling at Steps 1 and 2): 

Comments from the Air Stewardship 

Coalition (ASC) and the Portland 

Cement Association (PCA) asserted that 

if the EPA took different action on SIPs 

than contemplated in the FIP 

rulemaking proposal, the EPA would be 

required to conduct a new assessment 

and modeling of contribution and 

subject those findings to public 

comment. In a section titled ‘‘EPA Step 

Two Screening is Premised on the 

Premature Disapproval of 19 Upwind 

States Good Neighbor SIPs’’ (sections 

III.C. and II.C. of their respective 

comments) the ASC and the PCA stated 

that the EPA’s screening at Step 2 of the 

4-step interstate transport framework for 

the Proposed Good Neighbor Plan 

included states that already had good 

neighbor SIPs for the 2015 ozone 

NAAQS. Commenters state the EPA 

should not have included these states in 

this proposed rule’s screening as the 

final disapproval of said SIPs was not 

issued prior to the proposed FIP. The 

commenters claim that the EPA rushed 

to take final action on its good neighbor 

SIPs when the EPA proposed to 

disapprove 19 good neighbor SIP 

submissions and four findings of failure 

to issue a complete SIP on February 22, 

2022. Commenters state that in doing so 

the EPA prejudged the outcome of the 

pending SIP actions in their separate 

FIP action and did not account for the 

possibility that the EPA may take a 

different course of action at final than 

what was proposed in the SIP 

Disapproval action. 

Commenters indicate that as a 

consequence of this prejudgment the 

EPA may need to conduct a new 

assessment and modeling of 

contribution at Step 2 of the 4-step 

interstate transport framework if the 

EPA chooses to take a different action 

on any of the SIPs they have proposed 

to disapprove or found as having failed 

to issue a complete SIP. As such, 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99109 

17See Portland Cement Association’s June 21, 

2022, comment letter Docket Id No. EPA–HQ–OAR– 

2021–0668–0516, at 7, for section II.C. of the PCA 

comment as referenced. 

18See Air Stewardship Coalition’s June 21, 2022, 

comment letter Docket Id No. EPA–HQ–OAR2021–0668–0518, at 13–14. 

19The EPA has conducted or is in the process of 

conducting additional notice-and-comment 

rulemaking to address the obligations of those 

states. See 88 FR 87720 (December 19, 2023) 

(Wyoming); 89 FR 12666 (February 16, 2024) 

Supplemental Air Plan Actions: Interstate Transport 

of Air Pollution for the 2015 8-Hour Ozone National 

Ambient Air Quality Standards and Supplemental 

Federal ‘‘Good Neighbor Plan’’ Requirements for the 

2015 8- Hour Ozone National Ambient Air Quality 

Standards (‘‘Supplemental Rulemaking’’) 

(proposing action for Arizona, Iowa, Kansas, New 

Mexico, and Tennessee). 

20The Portland Cement Association’s comment 

on this topic is nearly identical and can be found 

at Docket Id No. EPA–HQ–OAR–2021–0668–0516, 

at 22. 

21See Air Stewardship Coalition’s June 21, 2022, 

comment letter Docket Id No. EPA–HQ–OAR–2021– 

0668–0518, at 27. 

22See Lower Colorado River Authority’s June 21, 

2022, comment letter Docket Id No. EPA–HQ–OAR– 

2021–0668–0395, at 21. 

commenters urged the EPA to stay 

action on the proposals and coordinate 

with states to ensure the appropriate 

sequence of actions is taken. The 

relevant text of the ASC’s comment is 

included immediately below.17

Yet, it appears EPA is rushing to take final 

action as EPA on February 22, 2022, 

proposed to disapprove 19 Good Neighbor 

SIP submissions. EPA also issued proposed 

findings of failure to issue a complete SIP for 

NM, PA, UT, and VA. The proposed FIP 

essentially prejudges the outcome of those 

pending SIP actions and, in the event EPA 

takes a different action on those SIPs than 

contemplated in this proposal, it would be 

required to conduct a new assessment and 

modeling of contribution and subject those 

findings to public comment.18

Citations to previous responses: The 

EPA explained that, partially in 

response to comments concerning 

technical issues with the modeling used 

at proposal for Steps 1 and 2, it 

conducted a new round of modeling and 

air quality analysis at Steps 1 and 2 in 

taking final action on the SIP 

Disapproval and the Good Neighbor 

Plan. 88 FR 36673–74; 88 FR 9339. The 

EPA explained that it also reviewed 

recent ozone monitoring data indicating 

persistent elevated ozone levels at many 

locations throughout the country. Id. at 

36704–05. The EPA explained that for 

most states its updated air quality 

analysis for the final rule was 

confirmatory of its proposed findings 

concerning which states contribute to 

downwind receptors at Step 2, and even 

its older 2011-based modeling. Id. at 

36674, 36707. The EPA explained that 

where its updated analysis at Steps 1 

and 2 indicated that a state was not 

contributing or that the basis for finding 

contribution had changed, it was not 

finalizing a FIP for that state in the Good 

Neighbor Plan; the EPA indicated its 

intent to address these and other states 

in subsequent actions. Id. at 36656, 

36658, 36689; see also SIP Disapproval, 

88 FR 9354.19

Comment category 3 (costeffectiveness at Step 3): Comments from 

ASC, PCA, the Indiana Municipal Power 

Agency (IMPA), the Lower Colorado 

River Authority (LCRA), and the 

Wisconsin Paper Council (WPC) 

question the methodology by which the 

EPA identified a cost-threshold used to 

establish the cost-effectiveness of the 

proposed controls. 

Commenters (ASC and PCA) both ask 

the EPA to reconsider the $7,500/ton 

average marginal cost-effectiveness 

threshold used for non-EGUs stating 

that it is too high and a departure from 

past practices. Both commenters state 

the EPA has failed to explain why the 

EPA relied on a ‘‘knee in the curve’’ 

approach instead of the past ‘‘clear 

breakpoint’’ approach to determine the 

$7,500/ton number. Commenters state 

that there is no noticeable break at that 

point for Tier 1 industries but there is 

a break at $1,600/ton mark; however, 

commenters concede there is a 

difference at $7,500/ton in Tier 2 

industries and the combined Tier 1 and 

2 industries line. In addition, 

commenters question why the EPA 

departed from the cost-effectiveness 

threshold used in the 2021 Revised 

CSAPR Update Rule ($2,000/ton in 

$2016) as it appears to commenters that 

the EPA had not collected any new 

information on costs or technologies or 

used different implementation timelines 

since the Revised CSAPR Update Rule. 

The relevant text of the Air Stewardship 

Coalition’s comment is included 

immediately below.20

The Agency’s sole analysis is that there 

was a ‘‘knee in the curve’’ that identified 

$7,500 per ton, but that is not obvious to a 

reviewer. There is no noticeable difference 

around $7,500 in the plotted line for Tier 1 

industries, instead the Tier 1 line reflects a 

break around the $1,600 mark. While the Tier 

2 and combined Tier 1 and 2 lines show 

some difference around $7,500 mark, there is 

no explanation for EPA’s reliance on a ‘‘knee 

in the curve’’ as opposed to past transport 

rules that have relied upon a ‘‘clear break 

point’’ at this step. Further, EPA has 

provided no explanation for why the Tier 1 

and 2 industries were subject to different 

contribution thresholds, as described above, 

yet they were combined when developing the 

cost-effective control threshold. 

In addition, EPA fails to explain why the 

threshold departs from prior transport rule 

cost-effectiveness thresholds for non-EGUs. 

In particular, less than one year before EPA 

released the Proposed Rule, in the 2021 

Revised CSAPR Update Rule, EPA said the 

non-EGU data demonstrated ‘‘a clear break 

point’’ (versus a ‘‘knee in the curve’’) at 

approximately $2,000 (in $2016) per ton. 

According to EPA, EPA adopted ‘‘that 

analysis using the best available current 

data,’’ including the ‘‘identified available 

control technologies,’’ their ‘‘costs and 

potential emissions reductions,’’ and ‘‘the 

information it has regarding control 

technology implementation timeframes, 

including information on such timeframes 

provided by commenters on the proposed 

rule.’’ Further, to identify levels of control for 

non-EGUs, EPA used the Control Strategy 

Tool (CoST) and the projected 2023 

inventory from the 2016v1 modeling 

platform, just as EPA has done in this 

Proposed Rule. Indeed, there is no indication 

in the Proposed Rule that EPA collected any 

new information on costs or technologies or 

implementation timelines that differed in any 

material way from the information it 

analyzed in the Revised CSAPR Update 

Rule.21

Other commenters (IMPA, LCRA, and 

the WPC) state that cost-effectiveness 

varies based on operational 

characteristics of the unit in question, 

that installing controls on existing EGUs 

may not be cost-effective, and that 

emissions from certain industries 

(specifically pulp and paper mills) 

would have a negligible effect on air 

quality. 

One commenter (IMPA) objected that 

requiring a specific type of emissions 

control will result in a lack of flexibility. 

They state that the cost-effectiveness of 

employing selective non-catalytic 

reduction (SNCR) will be highly 

variable, and that units employed at 

peak timeframes will not see similar 

emissions reductions to those that are 

used as base load generation. The 

commenter then states that technology 

specific dictates are not the best means 

of emissions control but would prefer 

controls that maintain flexibility. 

To support their claim that the EPA’s 

EGU controls are unlawful because they 

are not cost-effective, another 

commenter (LCRA) states that the 

installation of controls on existing 

sources (as compared to new sources) is 

not ‘‘per se reasonable or costeffective.’’ 22 The commenter goes on to 

state that EGUs that have already 

invested in state-of-the-art combustion 

controls have already undertaken 

significant costs and will have less to 

gain from additional controls such as an 

selective catalytic reduction (SCR) 

retrofit. 

Finally, one commenter (WPC) states 

that the emissions reductions coming 

from adding controls to pulp and paper 

mills ‘‘would have a negligible effect on 


khammond on DSK9W7S144PROD with RULES
99110 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

23See Wisconsin Paper Council’s June 21, 2022, 

comment letter Docket Id No. EPA–HQ–OAR–2021– 

0668–0338, at 2. 

24See Indiana Municipal Power Agency’s June 

20, 2022, comment letter Docket Id No. EPA–HQ– 

OAR–2021–0668–0361, at 9. 

25See Lower Colorado River Authority’s June 21, 

2022, comment letter Docket Id No. EPA–HQ–OAR– 

2021–0668–0395, at 2 (footnotes omitted). 

26See Wisconsin Paper Council’s June 21, 2022, 

comment letter Docket Id No. EPA–HQ–OAR–2021– 

0668–0338, at 2. 

air quality.’’ 23 The commenter states 

that this, coupled with a continued 

decreasing trend of Wisconsin-based 

stationary source NOX emissions, 

anticipated mobile source NOX

reductions, and additional reductions 

that they assert were not accounted for 

in the EPA’s analysis, indicates that 

inclusion of Wisconsin pulp and paper 

mills are not needed to achieve 

downwind air quality improvement. 

The relevant text of the various 

commenters is included immediately 

below. 

Indiana Municipal Power Agency 

Not every unit can install or activate SNCR 

in a way that is cost effective, relative to the 

actual emissions reductions that the units 

will experience. Inflated assumptions as to 

achievable emissions reductions, and 

underestimated implementation costs have 

led EPA to presume that compelling the use 

of SNCR with no regard for the individual 

circumstances of the EGU in question will be 

a cost effective means of reducing NOX

emissions. This is not always the case. In 

IMPA’s experience, the effectiveness of SNCR 

system is highly variable depending on the 

operational characteristics of the unit, and 

the level and consistency of its load. Units 

deployed during peak timeframes, such as 

IMPA’s WWVS units, will not see the same 

emissions reductions as base load generation. 

The cost effectiveness of the requirement to 

employ SNCR will be highly variable, and is 

unlikely to meet EPA expectations in even 

the most optimistic case.24

Lower Colorado River Authority 

It is clear that Congress believed existing 

source standards would never exceed new 

source standards: ‘‘[m]ore stringent 

requirements are imposed on new sources 

because engineering considerations allow for 

cheaper and more effective pollution control 

when the effort is incorporated in the design 

and construction of the facility.’’ In fact, EPA 

has previously recognized that less (not 

more) stringent standards are appropriate for 

existing units because ‘‘controls cannot be 

included in the design of an existing facility 

and because physical limitations may make 

installation of particular control systems 

impossible or unreasonably expensive in 

some cases.’’ Controls identified as part of a 

transport plan should take into account the 

difficulties of installing controls at existing 

facilities, but EPA does not do so in this 

Proposal. 

While installing selective catalytic 

reduction may be the common practice for a 

new fossil-fueled EGU, that does not mean 

that it is per se reasonable or cost-effective 

for existing plants, especially those that have 

already invested in other controls to lower 

their NOX emissions. Due to the lower 

emission rate starting point, plants that have 

already invested in state-of-the-art 

combustion controls, such as low-NOX

burners and overfire air, have already 

undertaken significant costs to achieve NOX

reductions and have less to gain from 

additional control installation, such as SCR 

and SNCR.25

Wisconsin Paper Council 

Furthermore, pulp and paper mill boilers 

contribute a small amount of the overall NOX

emissions from sources in the 23 states 

identified by EPA for emission reductions. 

Based upon the 2017 National Emissions 

Inventory, point sources in those states 

emitted approximately 1.5 million tons of 

NOX, while pulp and paper mill boilers 

emitted only about 35,000 tons in those states 

(2% of point source emissions). In addition, 

those states also have mobile source 

emissions of approximately 3.3 million tons 

per year of NOX, and another 1 million tons 

of NOX emissions from biogenic sources, 

wildfires and prescribed burns. 

It is also important to note that the 

reduction in emissions from pulp and paper 

mills would have a negligible effect on air 

quality. For example, the maximum 

estimated improvement at any receptor for 

emission controls on 25 pulp and paper mills 

is 0.0117 ppb, which is significantly below 

the detection limit of ambient air quality 

monitors. Thus, the benefit in air quality is 

too small to even measure.26

Citations to previous responses: The 

EPA explained that, as it had in all prior 

good neighbor rulemakings for ozone, it 

was establishing uniform emissions 

control levels for all covered states, 

using a comparative analysis of the costeffectiveness of different emissions 

control technologies as a key metric to 

establish the appropriate degree of 

stringency to define ‘‘significant 

contribution.’’ 88 FR 36675–77, 36678– 

79, 36683, 36718–19, 36741. The EPA 

explained that it determined in the final 

Good Neighbor Plan it would require 

controls up to the $11,000/ton 

representative cost threshold identified 

for EGUs associated with retrofit of SCR 

post-combustion control technology and 

that non-EGU costs on a per ton basis 

were generally commensurate with this 

level of control stringency. 88 FR 

36746–47. The EPA explained there 

could be variation in costs for particular 

units depending on their configurations 

or level of operation but that this 

variation did not impact its selection of 

the overall appropriate level of 

stringency. Id.; id. at 36740–41. The 

EPA explained it was not relying on the 

$7,500/ton preliminary threshold 

identified in the Non-EGU Screening 

Assessment, recognizing costs were 

more heterogeneous than that single 

figure, and that nonetheless, the 

Screening Assessment adequately 

served its function of helping the EPA 

target the most impactful non-EGU 

emissions control strategies in defining 

‘‘significant contribution.’’ Id.; Good 

Neighbor Plan RTC at 113–15. The EPA 

explained that for EGUs, the trading 

program would allow for cost-efficient 

compliance planning for all sources and 

adjusted its proposed trading program 

‘‘enhancements’’ to preserve greater 

flexibility for EGUs through the 2020s, 

id. at 36729–30, 36684, while for nonEGUs, the EPA made available 

flexibilities such as alternative 

emissions limits for any units facing 

excessively high costs or technical 

infeasibility, id. at 36818–19. The EPA 

explained that it believed its selected 

level of stringency as compared to prior 

transport rules was appropriate in light 

of the more protective 2015 ozone 

NAAQS and its projections of persistent 

elevated ozone levels. Id. at 36660. It 

explained how its analysis compared 

and was consistent with the 

determinations in the Revised CSAPR 

Update and other previous rulemakings 

taken pursuant to CAA section 

110(a)(2)(D)(i)(I). 88 FR 36660; Good 

Neighbor Plan RTC at 37–39, 92–93. The 

EPA explained how it had derived its 

estimates of representative costs for both 

EGUs and non-EGUs, which accounted 

for a range of costs associated with 

retrofit of controls on existing sources. 

88 FR at 36720–31, 36738–40. The EPA 

explained how its selected level of 

control was also roughly commensurate 

with the level of control required of 

existing sources in downwind states. 

Good Neighbor Plan RTC at 62–63. 

The EPA explained how it evaluated 

the air quality factor in its Step 3 

analysis, viewing it as serving a 

confirmatory role that an appropriate 

level of emissions control stringency 

would be achieved overall, that (based 

on available information) no costeffective strategies had been overlooked, 

and that if the identified cost-effective 

level of control stringency were applied 

uniformly across the linked upwind 

states, there would be, on average and 

in the aggregate, widespread reductions 

in ozone levels at downwind receptors. 

Id. at 36683, 36741, 36748–50. 

The EPA explained that it generally 

focused on large stationary sources of 

NOX emissions in upwind states, 

consistent with the science of regionalscale ozone transport and all of its prior 

good neighbor rulemakings for ozone. 

Id. at 36660, 36671, 36719. The EPA 

explained it recognized that air quality 

improvement from any particular source 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99111 

27See 63 FR 57356, 57361 (October 27, 1998). 

28 In addition to CSAPR rulemakings, other 

regional rulemakings addressing ozone transport 

include the ‘‘NOX SIP Call,’’ 63 FR 57356 (October 

27, 1998), and the ‘‘Clean Air Interstate Rule’’ 

(CAIR), 70 FR 25162 (May 12, 2005). 

or group of sources may appear 

relatively small, but this is simply an 

expression of the ‘‘collective 

contribution’’ problem that ozone 

presents. Good Neighbor Plan RTC at 

98, 103–04. The EPA explained why, 

given this problem and the need to 

control many sources over a wide area, 

it makes sense to define obligations for 

each state subject to a FIP through the 

application of a uniform level of 

emissions control across the linked 

states and to regulate on an industry-byindustry basis across those states, as a 

matter of both efficiency and equity. 88 

FR 36673, 36675–76, 36677, 36680, 

36683, 36691, 36719, 36741; Good 

Neighbor Plan RTC at 8, 48, 56–58, 83, 

92–93, 118. 

The EPA explained that it considered 

boilers in several industries to be 

impactful and controllable non-EGU 

types and that boilers in the pulp and 

paper industry were among those 

sources with well-demonstrated, costeffective NOX-emissions control 

options. 88 FR 36681–82, 36736, 36739– 

40; Good Neighbor Plan RTC at 93, 97, 

99–100, 107, 119–21. The EPA 

explained that it was nevertheless not 

including non-EGU requirements for 

Wisconsin in the final rule because 

based on the updated modeling used for 

the final rule, Wisconsin was no longer 

projected to be linked to downwind 

receptors in the 2026 analytic year. Id. 

at 118. 

The EPA addressed SNCR operating 

characteristics and effectiveness for 

existing EGUs, both in terms of 

optimizing SNCR controls that had 

already been installed, and in terms of 

installing new SNCRs on existing EGUs. 

88 FR 36725–26. The EPA evaluated 

comments concerning SNCR 

performance where specifically raised, 

see, e.g., Good Neighbor Plan RTC at 

229. The EPA also gave consideration to 

certain EGUs that have widely varying 

operating levels because they serve a 

‘‘peaking’’ function rather than 

supplying baseload power to the grid 

and did not include them in setting the 

stringency of the rule for EGUs at Step 

3. 88 FR 36732. 

III. Analysis of Severability in 

Response to Comments 

In this section, the EPA provides a 

fuller explanation why the Good 

Neighbor Plan can and should apply on 

a state-by-state basis for any state for 

which the EPA has a responsibility to 

promulgate a FIP, regardless of the 

number of states covered at any given 

time. Drawing together the Agency’s 

legal and technical reasoning, based on 

the information and data available at the 

time, provided in the record when the 

Good Neighbor Plan was signed and 

promulgated, the EPA provides a more 

thorough response to the relevant 

comments that together can be read to 

have raised that issue. 

A. Summary of Response 

As the EPA stated in the final rule, the 

Good Neighbor Plan by design is 

severable by state. 88 FR 36693. The 

rule implements the statute’s 

prohibition on ‘‘significant 

contribution’’ under CAA section 

110(a)(2)(D)(i)(I) for the 2015 ozone 

NAAQS by promulgating state-level 

FIPs that require the industries in each 

contributing upwind state to achieve at 

least minimum levels of emissions 

performance deemed to be costeffective. Id. at 36741. So long as they 

meet that level of performance, the 

industries in any state regulated under 

the Good Neighbor Plan are understood 

to have lawfully addressed good 

neighbor obligations and eliminated that 

portion of a state’s significant 

contribution to downwind air pollution. 

While the EPA must necessarily account 

for the multi-state nature of the 

interstate-ozone problem, consistent 

with the statute and case law, the Good 

Neighbor Plan imposes obligations on 

sources in each individual state that are 

appropriate for those sources and are 

achievable. 

Those requirements result from the 

application of a longstanding analytical 

framework that the EPA has applied 

when evaluating interstate transport 

obligations for multiple prior ozone 

NAAQS. 88 FR 36660, 36668–69. 

Shaped through the years by input from 

state air agencies 27 and other 

stakeholders on the EPA’s prior 

interstate transport rulemakings and SIP 

submission actions,28 as well as court 

decisions, the EPA has developed and 

used a ‘‘4-step interstate transport 

framework’’ to evaluate states’ 

obligations to eliminate interstate 

transport emissions under the interstate 

transport provision for each prior ozone 

NAAQS: (Step 1) identify monitoring 

sites that are projected to have problems 

attaining and/or maintaining the 

NAAQS (i.e., nonattainment and/or 

maintenance receptors); (Step 2) 

identify states that impact those air 

quality problems in other (i.e., 

downwind) states sufficiently such that 

the states are considered to ‘‘contribute’’ 

(i.e., are considered ‘‘linked’’) to those 

receptors and whose emissions therefore 

warrant further review and analysis; 

(Step 3) identify the emissions 

reductions necessary (if any), applying a 

multifactor analysis, to eliminate each 

linked upwind State’s significant 

contribution to nonattainment or 

interference with maintenance of the 

NAAQS at the locations identified in 

Step 1; and (Step 4) adopt permanent 

and enforceable measures needed to 

achieve those emissions reductions. The 

EPA does not require states to use the 

4-step interstate transport framework in 

good neighbor SIP submissions, nor has 

the EPA ever maintained that this is the 

only way states could satisfy their 

obligations under CAA section 

110(a)(2)(D)(i)(I). However, it is a useful 

organizational tool and evaluation 

framework that comports with the 

statutory text and structure of the Act. 

The application of uniform levels of 

emissions control stringency at Step 3 

across all linked states has been upheld 

by the Supreme Court as ‘‘permissible, 

workable, and equitable.’’ EPA v. EME 

Homer City Generation, L.P., 572 U.S. 

489, 524 (2014). The Supreme Court 

there expressly rejected that the Act 

mandates a definition of ‘‘significance’’ 

that is directly proportional to each 

state’s contribution, finding that reading 

‘‘appears to work neither 

mathematically nor in practical 

application.’’ Id. at 516. As the EPA 

explained in the Good Neighbor Plan, 

the 4-step interstate transport 

framework, including the application of 

uniform minimum control stringency, 

remains a particularly fair and equitable 

approach to apply in the case of a 

multistate pollution problem like ozone, 

characterized by ‘‘collective 

contribution’’ and in which widespread 

emissions reductions of a single 

precursor pollutant (nitrogen oxides or 

NOX) over a wide geographic area are 

known to be effective in improving 

ozone levels downwind. 88 FR 36719. 

Because the methodology for defining 

those obligations ultimately relies on a 

determination regarding what level of 

widely available emissions performance 

each type of regulated source can costeffectively achieve, the obligations set 

for sources in each state are 

independent of the number of states 

included in the Good Neighbor Plan. 

Accordingly, the fact that obligations 

may be suspended or not yet operative 

with regard to some states does not 

impact the Good Neighbor Plan’s 

conclusions as they apply in other 

states. Rather, as the EPA explained, the 

framework yields an ‘‘amount’’ of 

pollution for ‘‘each State’’ that the EPA 

is authorized to ‘‘prohibit,’’ CAA section 

110(a)(2)(D)(i), standing in the shoes of 


khammond on DSK9W7S144PROD with RULES
99112 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

29These states are now included in a 

supplemental rulemaking to address their 

obligations. See supra note 19. 

a state, CAA section 110(c)(1), based on 

the amounts of pollution that would be 

avoided in that state by applying the 

control technologies the EPA 

determined were cost-effective for the 

covered industries. 88 FR 36675. The 

amounts to be prohibited are thus 

premised on reasonable levels of 

pollution control upwind rather than on 

a specific, aggregate quantum of ozone 

reduction that must be achieved 

downwind. Michigan v. EPA, 213 F.3d 

663, 674–80 (D.C. Cir. 2000). 

Under this framework, while the 

emissions-control requirements are 

uniform across the same types of 

sources in each state, the size of each 

state’s total incremental emissionsreductions obligation under the Good 

Neighbor Plan, and the resulting 

improvement in air quality downwind, 

depends on the particular sources 

present in that state and the level of 

pollution reduction those sources are 

already achieving. 88 FR 36683. If a 

state’s sources are already wellcontrolled, they will have less to do to 

meet the EPA’s defined level of control 

stringency; if the state’s sources are not 

already well-controlled, they will have 

to do more. But these state-specific 

obligations derive from the application 

of common, uniform levels of emissions 

control stringency calculated for each 

type of source based on the 

demonstrated performance of pollution 

control technologies that can be 

replicated in any linked upwind state. 

EME Homer City, 572 U.S. at 519–20. 

Calculating ‘‘significance’’ according to 

source type and concluding that the 

good neighbor provision can be 

reasonably implemented by bringing all 

covered sources up to a common level 

of control ensures the EPA can fairly 

administer the program in any state that 

becomes subject to a need for federal 

regulation, while avoiding inequities 

that could arise if state plans (and 

relevant sources) were addressed 

seriatim. See 88 FR 36749 (explaining 

the need to avoid a ‘‘which state goes 

first’’ problem). The achievement of that 

level of performance for any particular 

state is not dependent on the number of 

states in the Good Neighbor Plan, nor on 

the order in which the states are 

addressed. In this way, the Good 

Neighbor Plan prohibits each covered 

state’s ‘‘significant contribution’’ to 

downwind ozone problems in a 

‘‘permissible, workable, and equitable’’ 

manner. 572 U.S. at 524. 

Given this statutory structure and 

regulatory framework, the Good 

Neighbor Plan is ‘‘modular’’ by nature, 

defining and implementing the 

obligations for each state. 

First, in line with the statutory text, 

structure, and case law, the EPA 

determines the ‘‘significant 

contribution’’ that must be prohibited at 

the individual state level. See 88 FR 

36687 (citing North Carolina v. EPA, 

531 F.3d 896, 906–08, 921 (D.C. Cir. 

2008)). None of the steps in the 4-step 

interstate transport framework differ 

based on the number of states included 

in the Good Neighbor Plan. For 

example, the control technologies and 

cost-effectiveness figures the EPA 

considers at Step 3 do not depend on 

the number of states included. Instead, 

the Good Neighbor Plan regulates 

certain relatively large emitting sources 

in each included state (including both 

new and existing sources meeting the 

relevant criteria), up to a uniform level 

of pollution control that is common 

across sources of that type in all 

potentially contributing states. Once the 

‘‘amount’’ of pollution for each state is 

determined, whether the 4-step 

interstate transport framework is 

applied to one state or fifty, it would 

yield the same emissions control 

obligations for the included states. That 

means that when the number of states 

whose sources are included in the Good 

Neighbor Plan’s regulatory programs for 

EGUs or non-EGUs changes from the 

number included at promulgation, 

which is historically common in 

interstate transport rules and consistent 

with states’ authority under the Act to 

replace federal plans with state plans, 

the emissions reduction obligations of 

the states remaining in the Good 

Neighbor Plan’s programs stay the same, 

and the obligations of states joining the 

Good Neighbor Plan’s programs are the 

same as those that were applied to the 

states already included. 

Second, given the state-specific 

statutory mandate, for those 

components of the Good Neighbor Plan 

that necessitate consideration of multistate effects, the EPA is careful to avoid 

creating any interdependency among 

the particular states included, both in 

the Agency’s analytical methodology 

and in the Good Neighbor Plan’s 

regulatory requirements. As the EPA 

explained in the rule, interstate ozone 

pollution continues to present a 

‘‘collective contribution’’ challenge 

wherein many sources of emissions over 

a wide geographic area comprise a 

substantial portion of the ozone 

problems downwind. 88 FR 36678, 

36712. Where the EPA is called upon to 

fill a gap in state planning efforts, it 

must therefore develop solutions for the 

relevant state(s) that reasonably account 

for the efforts other states may 

undertake, even in the face of 

uncertainty concerning what those 

states may do. Id. at 36695–96. For 

example, when evaluating the Good 

Neighbor Plan to ensure it did not 

‘‘overcontrol’’ (i.e., yield more 

reductions than necessary), the EPA did 

not just look at the states included in 

the original Good Neighbor Plan, but 

also looked at all of the other states the 

modeling showed were potentially 

affecting downwind air quality above 

the ‘‘contribution’’ threshold (as well as 

each receptor’s ‘‘home’’ state), even if 

those states were not included in the 

Good Neighbor Plan.29 See infra note 47 

supra and accompanying text (providing 

record citations). Taking this broad 

view, the EPA found that even making 

all cost-effective reductions available in 

all linked upwind states, and assuming 

equivalent emissions reductions from 

the two downwind states not included 

in the Good Neighbor Plan, the rule 

would not constitute overcontrol. 88 FR 

36749–50. Accordingly, because the 

overcontrol analysis already assumes 

the emissions reductions that can 

reasonably be anticipated from the 

implementation of the good neighbor 

provision for a given NAAQS, requiring 

available emissions reductions in any 

subset of those states does not constitute 

overcontrol of those upwind states. See 

section III.B.2.c. of this document 

(providing record citations). Finally, the 

Good Neighbor Plan’s regulatory 

requirements, including the emissions 

trading program for power plants, are 

designed to be fully implementable in 

each individual state and do not depend 

on participation from a minimum 

number of states. See section III.B.3. of 

this document (providing record 

citations). In these ways, the EPA’s 

methodological approach to devising 

good neighbor FIPs for ozone ensures 

against inter-dependency among states, 

through accounting for the effects of 

emissions reductions within a web of 

‘‘overlapping and interwoven’’ linkages 

among many states, EME Homer City, 

572 U.S. at 496–97, while at the same 

time setting technology-based emissions 

limits and other control measures that 

the sources in each state can meet. 88 

FR 36741, 36749. 

Third, while equity and consistency 

in obligations among states are at the 

core of the statute and the EPA’s 4-step 

interstate transport framework, the 

suspension or removal of the Good 

Neighbor Plan’s requirements in some 

states does not provide a lawful basis to 

suspend them in others. Just as each 

state has an individual obligation to 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99113 

30See also, e.g., 86 FR 23054, 23163–64 (April 30, 

2021); 84 FR 56058, 56093 (October 18, 2019); 83 

FR 65878, 65923–24 (December 21, 2018); 83 FR 

50444, 50472 (October 5, 2018); 81 FR 74504, 

74585–86 (October 26, 2016); 76 FR 80760, 80773– 

74 (December 27, 2011); 76 FR 48208, 48352 

(August 8, 2011); 71 FR 25328, 25329 (April 28, 

2006); 70 FR 25162, 25316 (May 12, 2005); 65 FR 

2674, 2725 (January 18, 2000); 63 FR 57356, 57480 

(October 27, 1998). 

31 ‘‘Significant contribution’’ is often used as a 

shorthand to refer to the identification of those 

amounts of emissions that significantly contribute 

to nonattainment or interfere with maintenance of 

the NAAQS in other states and therefore must be 

prohibited under the good neighbor provision. See 

CAA section 110(a)(2)(D)(i)(I). 

satisfy the good neighbor requirements 

of CAA section 110(a)(2)(D), regardless 

of whether other states have done so, 

the EPA has a statutory obligation to 

address the good neighbor obligations of 

‘‘each State’’ where it has a federal 

responsibility to act. CAA section 

110(c)(1). Indeed, the goals of equity 

and consistency extend to the 

downwind states for whom the good 

neighbor provision was enacted. The 

good neighbor provision’s requirement 

of consistency with the rest of the CAA, 

see CAA section 110(a)(2)(D)(i), 

including the air quality attainment 

schedules that are the ‘‘heart’’ of the 

Act, Train v. NRDC, 421 U.S. 60, 66 

(1975), means that each downwind state 

with identified air quality problems has 

a statutory right to timely relief from the 

public health and regulatory burdens of 

upwind pollution. See 88 FR 36694 

(discussing case law). It would be 

contrary to this statutory purpose to 

revise or suspend the Good Neighbor 

Plan as to upwind states for which the 

EPA is under a statutory requirement to 

act because the Good Neighbor Plan’s 

requirements were suspended for other 

states. 

These principles are applicable in a 

variety of circumstances where the EPA 

may approve a state’s SIP as sufficiently 

meeting its good neighbor obligations 

even if the state’s approach is different 

than the EPA’s approach, for that state 

or for other states. The EPA’s interstate 

ozone transport actions are typically 

taken on a national basis and with the 

goal of ensuring consistency, including 

in terms of alignment of the timing of 

obligations, because doing so ensures 

equitable treatment of all states and is 

administratively efficient given the 

commonality in analysis and obligations 

across many states, particularly in the 

case of interstate ozone transport. In 

addition, the establishment of interstate 

emissions trading programs has allowed 

for more cost-efficient compliance 

activities, and it is far more efficient to 

establish these programs through a 

consolidated, multistate rulemaking 

action. Historically, this has also been 

coupled with the EPA’s practice of 

seeking consolidated judicial review of 

such actions in the D.C. Circuit to 

ensure that a consistent caselaw regime 

applies across the entire country on 

matters of interstate ozone pollution and 

is not varied by which federal judicial 

circuit a state happens to be located in. 

88 FR 36859–60.30

Nonetheless, the EPA acknowledged 

states’ ability to develop alternative, 

potentially approvable approaches to 

meeting their good neighbor obligations. 

See 88 FR 36838–43. In evaluating 

alternative approaches, the EPA must 

consider interstate consistency, 88 FR 

36839–40; id. n.405; 87 FR 9338, 9380– 

81, but it has never been the Agency’s 

view that its methodology for defining 

one state’s obligations would have to be 

redone simply because it found an 

approach in another state also 

approvable. 

Thus, as explained in more detail in 

section III.B., the comments asserting 

that the EPA should stay, revise, or 

withdraw the Good Neighbor Plan for 

any particular state depending on the 

status of implementation of good 

neighbor obligations of other upwind 

states cannot be squared with the statespecific mandate of the Act, nor would 

this be compelled as a result of any 

element of the EPA’s 4-step interstate 

transport framework. For those states 

where the Good Neighbor Plan may be 

currently suspended, good neighbor 

obligations will ultimately be met, 

either through an approved state plan or 

a federal plan as necessary. Meanwhile, 

sources in upwind states regulated by 

the Good Neighbor Plan would be under 

the same legal obligation to control their 

pollution even if the EPA developed a 

federal plan containing just those states 

or some subset of them or separate 

federal plans for each state. 

B. Step-by-Step Review of the 4-Step 

Interstate Transport Framework 

A review of the EPA’s methodology 

demonstrates why each upwind state 

would bear the same emissions 

reduction obligations, regardless of how 

many states were included in a 

particular rulemaking. The EPA’s 

method for defining good neighbor 

obligations, while applied consistently 

across the nation and respectful of the 

multistate ‘‘collective contribution’’ 

nature of the interstate ozone problem, 

produces a definition of ‘‘significant 

contribution’’ 31 for the sources in each 

individual state, and provides for the 

prohibition of such emissions in a 

manner that is not dependent on the 

inclusion of any particular number or 

grouping of states. As tested and refined 

through case law over the past quartercentury, the EPA’s methodology is 

consistent with the state-specific 

structure of the Act and the 

fundamental statutory obligation to 

define and prohibit each state’s own 

significant contribution. See CAA 

section 110(a)(1) and 110(a)(2)(D); 

Wisconsin v. EPA, 938 F.3d 303, 324– 

25 (D.C. Cir. 2019); North Carolina, 531 

F.3d at 906–08, 920–21. 

Consistent with the statutory text and 

structure and judicial precedent, the 

EPA’s 4-step interstate transport 

framework was designed to be 

independent of the number or scope of 

included states. Because the statute 

allows states to replace a FIP with a 

SIP—and because as a practical matter 

the EPA does not necessarily receive or 

act on each state’s SIP submission at the 

same time—the Good Neighbor Plan is 

expressly designed to allow states to be 

added to or removed from the federal 

emissions control program over time, as 

circumstances require (including where 

a state submits an approvable SIP to 

replace their FIP, see 88 FR 36838–39). 

The Good Neighbor Plan does so 

primarily by setting good neighbor 

obligations based on the available, costeffective technologies that can be 

applied to each type of high-emitting 

source—a technology-focused definition 

of ‘‘significant contribution’’ that the 

Supreme Court upheld in EME Homer 

City and that can be evenhandedly 

applied to existing sources and those 

that may be newly located in any 

contributing State in the future. 88 FR 

36675–77, 36678–79, 36683, 36718–19, 

36741. This ensures fairness and 

consistency across all states when the 

EPA must act pursuant to its FIP 

authority to implement CAA section 

110(a)(2)(D)(i)(I), regardless of when any 

particular state is addressed—it avoids 

the problem of ‘‘which state goes first’’; 

that is, it avoids producing unfairly 

varying levels of emissions-control 

stringency depending on the order in 

which states’ obligations are addressed. 

88 FR 36749. As the Supreme Court 

aptly illustrated in EME Homer City, 

where multiple states contribute to 

multiple other states (as remains the 

case across the contiguous U.S. for the 

2015 ozone NAAQS), addressing each 

state’s obligations in proportion to its 

contribution to each receptor in seriatim 

fashion becomes mathematically 

unworkable and economically 

inefficient. 572 U.S. at 516. The EPA’s 

approach to developing ozone good 

neighbor FIPs avoids these pitfalls, 

avoids interdependence, and avoids 

unfairness—it works for each state that 

may need federal regulation of its 


khammond on DSK9W7S144PROD with RULES
99114 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

32Both the EPA and States can use air quality 

modeling and monitoring information on ozone 

concentrations and contribution levels to make 

individual determinations for each state concerning 

whether it is contributing to any out-of-state 

receptors. See, e.g., 88 FR 9365 n.286 (identifying 

individualized approvals of SIPs using modeling at 

Steps 1 and 2). 

33See 2015 Ozone NAAQS Interstate Transport 

SIP Disapprovals—Response to Comments (RTC) 

Document at 296, available at https://

www.regulations.gov/document/EPA-HQ-OAR2021-0663-0083. 

34The commenter also asserted that the EPA had 

‘‘proposed’’ findings of failure to submit for four 

states, New Mexico, Pennsylvania, Utah, and 

Virginia. That statement was incorrect insofar as the 

EPA issued a final finding of failure to submit for 

these states in December of 2019, effective January 

6, 2020, had an obligation to promulgate FIPs for 

these states pursuant to CAA section 110(c)(1) by 

January 6, 2022, and was subject to a consent decree 

deadline to promulgate FIPs for these states 

(excluding New Mexico) by March 15, 2023. See 88 

FR 36689 n.106. 

sources. Accordingly, under each step of 

the 4-step interstate transport 

framework discussed further later, a 

change in the number of states covered 

does not impact the obligations of the 

states or sources that remain covered. 

1. Steps 1 and 2 

The EPA identifies receptors based on 

nationwide modeling and monitoring 

data and evaluates each state’s 

contribution to receptors in downwind 

states on an individual-state basis to 

identify upwind-state-to-downwindstate linkages. The air quality modeling 

and the monitoring data the EPA 

considered for Steps 1 and 2 cover the 

contiguous United States. See 88 FR 

36696. 

At Step 1, the EPA identified 

downwind receptors that are expected 

to have problems attaining or 

maintaining the NAAQS. For a detailed 

explanation of what receptors are and 

how the EPA identified them, see 88 FR 

36703–08. At Step 2, the EPA identified 

which upwind states contribute to the 

identified receptors in amounts that 

would be sufficient in the EPA’s 

interpretation of ‘‘contribution’’ to 

‘‘link’’ the individual upwind states to 

downwind air quality problems. For a 

detailed explanation of how the EPA 

identified these linkages, see 88 FR 

36708–12. 

The nationwide identification of 

receptors expected to have problems 

attaining or maintaining the NAAQS 

and of states ‘‘contributing’’ to those 

receptors does not rely upon nor 

necessarily dictate the number of states 

included in a particular rulemaking. 

The EPA historically has applied a 

common numerical threshold for 

determining which states ‘‘contribute’’ 

to downwind air quality problems, and 

the contributions from each state are 

evaluated independently with respect to 

this threshold. 88 FR 36677–78. The 

modeling of baseline conditions did not 

contain or rely on the emissions 

reductions in the Good Neighbor Plan, 

and the monitoring data were based on 

measurements during years prior to 

when the Good Neighbor Plan was final 

and thus these data do not reflect the 

impacts of emissions reductions from 

the Good Neighbor Plan.32 This 

approach creates a level playing field 

from which to assess each state’s level 

of contribution. 88 FR 36713. 

In addition to promoting national 

consistency, the EPA has explained that 

using a single contribution threshold 

avoids creating potential interdependencies among states. When the 

EPA had previously considered whether 

to approve individual states’ use of a 

higher contribution threshold, it had 

proposed (for the State of Iowa) to 

consider the effects of other states’ 

efforts to reduce their pollution at 

shared receptors. See 88 FR 36715. On 

further consideration, however, the EPA 

found this would have introduced an 

interdependency. Id. When the EPA 

gave consideration to this approach in 

its SIP Disapproval action disapproving 

21 state implementation plans (88 FR 

9336; February 13, 2023), in response to 

comments, it explained that this factor 

would inappropriately introduce an 

inequity in which some states could 

evade obligations through reliance on 

the incidental effects of other states’ 

efforts.33 See also 88 FR at 36713 

(explaining that ‘‘use of alternative 

thresholds would allow certain states to 

avoid further evaluation of potential 

emissions controls while other states 

must proceed to a Step 3 analysis. This 

could create significant equity and 

consistency problems among states.’’). 

The EPA’s analytical methodology at 

Steps 1 and 2 ensures the EPA can 

impose FIP obligations, where they may 

be needed, according to a common 

rubric that maintains equity and 

consistency between the potentially 

subject states. Thus, the analytic 

methods in both Step 1 and Step 2 to 

determine ‘‘contributing’’ states rely on 

emissions and air quality data that are 

independent of which or how many 

states are covered by the Good Neighbor 

Plan. 

We note that comments from ASC and 

PCA in Comment Category 2 

summarized in section II.B. of this 

document contained several statements 

the meaning of which the EPA could not 

clearly ascertain. Those comments said 

the EPA’s Step 2 screening analysis 

included states that ‘‘already had Good 

Neighbor SIPs for the 2015 ozone 

NAAQS.’’ See ASC Comment Letter at 

13. The meaning of this statement is 

unclear. States may have made SIP 

submissions for these obligations, but at 

the time of this comment, the EPA had 

not approved all of those submissions 

and was in the process of disapproving 

many of them, and so the statement read 

that way (i.e., to suggest that the States 

already had approved SIPs) is factually 

incorrect.34 The sentence in the ASC 

comment letter goes on to state that the 

EPA ‘‘prematurely disapproved’’ these 

SIPs, but the disapprovals had only 

been proposed at the time the comment 

was submitted. The commenter did not 

explain what made the EPA’s proposed 

disapprovals ‘‘premature.’’ 

This comment might be read as in 

relation to the previous approvals of 

SIPs for certain states, and thus an 

argument that these states’ emissions 

should be excluded from modeling 

analyses. Or the comment might be read 

in relation to a subsequent statement in 

the comment, that states should not be 

included in the Good Neighbor Plan’s 

‘‘screening’’ at Step 2 if final action on 

the SIP submission had not yet been 

taken. In either of these cases, the 

comment would be misplaced, in that 

our analysis of the Steps 1 and 2 

modeling looks at the transport of 

pollution as a factual matter and does 

not remove from consideration the 

emissions of states based on the 

procedural status of their SIP 

submissions. In addition, as explained 

in section III.B.1., the EPA’s baseline air 

quality and contribution modeling for 

Steps 1 and 2 is conducted for a 

modeling domain that includes the 

entire contiguous United States and 

accounts for all emissions sources. 88 

FR 36696. Removing emissions from 

certain states from this modeling would 

produce erroneous, unrealistic, and 

counterfactual results. 

These comments also stated that the 

EPA may need to conduct a new 

analysis at Step 2 in the event the EPA 

takes a different action on those SIPs 

than contemplated in the proposed 

Good Neighbor Plan. In that case, 

according to commenter, the EPA 

‘‘would need to conduct a new 

assessment and modeling of 

contribution and subject those findings 

to public comment.’’ ASC Comment 

Letter at 14. On the one hand, the EPA 

agrees with the commenter to the extent 

they are suggesting that if updated 

modeling the EPA conducted (e.g., the 

2016v3 modeling used in the final Good 

Neighbor Plan) showed a state was no 

longer contributing at Step 2, and the 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99115 

35See also supra note 19. 

EPA approved that state’s SIP 

submission or had deferred taking 

action, then the EPA would not 

promulgate a FIP for that state given that 

disapproval (or a finding of failure to 

submit) is a necessary predicate to FIP 

authority. This is precisely how the EPA 

proceeded in the final SIP Disapproval 

and Good Neighbor Plan and in taking 

subsequent rulemaking actions for states 

where its final analysis at Steps 1 and 

2 had materially changed from its 

proposed SIP and FIP actions. See 88 FR 

36656, 36658, 36689; see also SIP 

Disapproval, 88 FR 9354.35 On the other 

hand, the comment might be read to 

suggest that if the EPA’s analysis 

changed for any particular state at Steps 

1 or 2, then it would have to conduct 

a whole new analysis of every other 

state at Steps 1 or 2. If so, that comment 

is in error because the EPA’s baseline air 

quality and contribution analysis at 

Steps 1 and 2 already accounts for 

emissions across all states regardless of 

their inclusion in the rule, and the 

results of that analysis would not 

change for one state simply because the 

results indicated that another state had 

fallen below the Step 2 contribution 

threshold. 

Taken as a whole, this set of 

comments appears to be primarily about 

the need for the EPA to ensure 

consistency in how it analyzed each 

state’s obligations between the separate 

SIP and FIP rulemakings (a consistency 

that the EPA agrees is important and 

abided by). The commenter did not state 

that the EPA’s analysis must be redone 

if for reasons beyond the Agency’s 

control the Good Neighbor Plan were 

stayed or not in effect for any particular 

state; rather, the commenter emphasized 

the need for consistency in the EPA’s 

own, substantive analytical 

determinations. If the commenter 

intended to argue that a change in 

analysis at Steps 1 or 2 for one state 

would necessarily alter the EPA’s 

substantive assessment for other states 

and would need to be subjected to 

additional notice and comment, the 

commenter did not state that, nor 

provide a theory or reasoning as to why 

that would be the case, and for the 

reasons explained in this section 

(III.B.1.), such an assertion would reflect 

a misunderstanding of how baseline air 

quality and contribution analysis is 

conducted at Steps 1 and 2. 

2. Step 3 

The Act requires each state to 

eliminate its ‘‘significant contribution’’ 

to downwind nonattainment or 

interference with maintenance of air 

quality standards. To determine which 

emissions from contributing states are 

‘‘significant’’ at Step 3, the EPA 

analyzes available emissions control 

strategies and their costs. Based on that 

analysis, the EPA then identifies a 

uniform degree of emissions control 

stringency that is reasonable to require 

from upwind sources, calculated based 

on the emissions performance those 

sources would achieve through the 

application of the technologies the EPA 

found were most cost-effective. Step 3 is 

a multi-factor analysis, with its primary 

focus on technology availability and 

associated cost, the level of emissions 

reductions that are thereby achieved, 

and the associated air quality benefits 

delivered to downwind receptors. The 

approach applies uniform levels of 

emissions control stringency across all 

upwind states, with the objective of 

bringing the covered sources in each 

state up to a minimum level of 

emissions performance to reduce ozoneprecursor emissions. See 88 FR 36675– 

77, 36678–79, 36683, 36718–19, 36741. 

This approach is tailored to a pollution 

problem characterized by collective 

contribution from many similar sources 

all emitting a similar precursor 

pollutant (NOX) over a wide geographic 

area; it ensures an efficient and 

equitable solution that avoids 

interdependency. Id. at 36719, 36741, 

36749. 

Thus, when the EPA uses the term 

‘‘uniform’’ in the context of Step 3, it is 

not referring to the division of a specific 

‘‘pie’’ of air pollution, total emissions, 

or total cost divided proportionally 

among the upwind states; rather it is 

referring to application of a pollution 

technology applied equally across all 

applicable units of a common size and 

type. 88 FR at 36746–47. One example 

of a uniform control stringency level is 

the assumption that all EGU units with 

already-installed selective catalytic 

reduction (SCR) technology operate and 

optimize the performance of these 

controls. Id. at 36720–21. The EPA 

estimated that this would be realized 

through emissions rates (on average 

across the fleet) of 0.08 pounds per 

million British thermal units at costs of 

about $1,600 per ton of NOx removed. 

Id. The translation of this technology 

stringency into the definition of 

significant contribution is specific to 

each state’s unique group of sources and 

the operating characteristics of the 

affected units at those sources. Id. at 

36683. In no way is the amount of 

emissions mitigation required of sources 

in each state interdependent on another 

state’s mitigation responsibility. The 

‘‘amount’’ of pollution that is identified 

for elimination at Step 3 of the 4-step 

interstate transport framework is 

therefore that amount of emissions that 

is above the level of emissions 

remaining after the cost-effective 

emissions control strategies are 

implemented. Id. at 36676. Because it is 

possible that a uniform level of 

stringency may produce more emissions 

reductions than is necessary to fully 

resolve a particular upwind state’s 

linkages to all downwind receptors, the 

EPA tests its identified level of 

stringency for ‘‘overcontrol.’’ For a 

detailed explanation of how the EPA 

applies Step 3, see 88 FR 36718–54. 

Acknowledging that some of the 

factors considered in the Step 3 analysis 

are considered at a national scale while 

certain components of that analysis 

account for state-level or linkagespecific data, the EPA here explains in 

more detail why the selected levels of 

control stringency for particular 

industries, and therefore the particular 

obligations of individual states, do not 

vary depending on the number of states 

subject to FIPs under the Good Neighbor 

Plan. 

The EPA identified potential levels of 

emissions control stringency that could 

be applied for each industry, and thus 

for the set of sources found in each 

state, regardless of the number of States 

covered by an approved SIP or a FIP or 

not yet covered by either. In evaluating 

those potential levels of stringency, the 

EPA conducted a wide-ranging survey 

of emissions control technologies (and 

associated cost data) used throughout 

the United States and even 

internationally. Then, the EPA 

conducted the air-quality-improvement 

and overcontrol analyses considering 

the effects of the potential uniform 

stringency levels at each identified 

receptor. The primary way in which the 

EPA conducts that assessment is to 

apply the potential stringency levels 

across all of the states linked to each 

particular receptor as well as the 

downwind, ‘‘home’’ state for that 

receptor. The EPA then assesses the 

average resulting improvements across 

all receptors as well as tabulates the 

aggregate effects. This allowed the EPA 

to ascertain whether a selected level of 

stringency was effective at achieving 

improvements in the air quality 

downwind that were reasonable in 

relation to the identified costs, while 

also ensuring a selected stringency level 

is not more stringent than necessary to 

bring any given receptor into 

attainment. 88 FR 36741, 36749–50. But 

given the overlapping linkages among 

multiple upwind and downwind states, 

as well as varying levels of baseline 

emissions control in each state, further 


khammond on DSK9W7S144PROD with RULES
99116 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

36 Just as the EPA’s analytical approach allows for 

it to develop a good neighbor FIP for any state that 

may require one that reasonably establishes 

emissions control obligations in the face of 

uncertainty regarding what other states will do, it 

also allows states themselves to conduct a similar 

analysis of their own obligations in the context of 

developing a SIP without definitive knowledge of 

what other states will do to fulfill their own 

obligations. At Step 3 of the EPA’s 4-step interstate 

transport framework, each state found to be 

contributing to one or more receptors can conduct 

an analysis of emissions control technologies or 

measures that would be cost-effective within the 

state. If each state linked to a given receptor (and 

the downwind state where that receptor is located, 

to account for that state’s own fair share), made 

pollution-control efforts at these levels, a state 

could demonstrate that ozone levels at the 

downwind receptors would be measurably 

improved (without undertaking more emissions 

reductions than necessary). In the context of a FIP, 

this approach to evaluating air quality 

improvements at downwind receptors is necessary, 

because to avoid overcontrol, the EPA must 

consider whether applying a given control 

stringency level to other states would achieve more 

emissions reductions than necessary to bring a 

receptor into attainment. 

37 In response to comments, the EPA conducted 

a sensitivity analysis for EGUs to see if looking at 

control costs on a regional basis would change the 

results and found that it would not. EGU NOX

Mitigation Strategies Final Rule TSD at 49–50. The 

fact that the EPA conducted this as a sensitivity 

analysis to address a comment further illustrates 

that the primary technology and cost analysis the 

EPA conducted, as described earlier, was not 

limited to a 23-state geography and would not be 

altered if that geography were different. 

38Available in the docket at https://

www.regulations.gov/document/EPA-HQ-OAR2021-0668-1110. 

39Available in the docket at https://

www.regulations.gov/document/EPA-HQ-OAR2021-0668-1092. 

40See Summary of Final Rule Applicability 

Criteria and Emissions Limits for Non-EGU 

Emissions Units, Assumed Control Technologies for 

Meeting the Final Emissions Limits, and Estimated 

Emissions Units, Emissions Reductions, and Costs 

at 5–7 (Non-EGU Memorandum), available in the 

docket at https://www.regulations.gov/document/ 

EPA-HQ-OAR-2021-0668-0956. 

complicated by the year-to-year 

variability in ozone levels due to 

meteorology, id. at 36750, the EPA’s 

methodology, going back to the original 

NOX SIP Call in 1998, has never 

attempted to pinpoint a precise level of 

emissions control for each state that 

maximizes cost-effectiveness in relation 

to each specific linkage. See 88 FR 

36748 (finding the aggregate and average 

air quality effects of the combined EGU 

and non-EGU strategies across all 

receptors would achieve ‘‘meaningful 

downwind air quality improvements’’). 

Expressed in simpler terms, the EPA’s 

long-standing interpretation of CAA 

section 110(a)(2)(D)(i)(I)—an approach 

that the Supreme Court expressly 

upheld in EME Homer City—is that a 

state may satisfy its good neighbor 

obligations by ensuring that its 

emissions do not exceed what would 

result from the application of costeffective emissions controls. The 

purpose of Step 3 is to identify a set of 

widely available and well-established, 

cost-effective emissions controls that 

can be applied in any upwind state, 

while checking to ensure that those 

emissions controls will achieve 

downwind improvements in air quality 

without overcontrol. 

As described in more detail in 

sections III.B.2.a.–III.B.2.c., none of the 

determinations that underlie Step 3 are 

contingent on a particular state or set of 

states being covered by the Good 

Neighbor Plan. Accordingly, the EPA’s 

Step 3 analysis can be extended to states 

not covered by the Good Neighbor Plan 

either because the state is covered by an 

approved SIP or prior FIP or because the 

EPA has not yet taken action to review 

a SIP or impose a FIP. By identifying 

cost-effective approaches to reducing 

multi-state ozone pollution in a manner 

that does not depend on the 

participation of any particular state or 

set of states, the EPA’s approach 

reasonably fulfills Congress’s direction 

in CAA section 110(a)(2)(D)(i)(I) to 

address the multi-state ozone problem 

in a way that defines each state’s 

obligations on an individualized basis.36

Specifically, the EPA took the 

following steps in conducting its Step 3 

analysis in the Good Neighbor Plan: 

a. Technology, Cost, and Emissions 

Reduction Analyses 

The EPA’s analysis started by 

examining emissions control 

technologies (sometimes also referred to 

as ‘‘strategies’’) and their associated 

costs and emissions reductions. The 

Good Neighbor Plan identified 

conventional, at-the-source, NOX

emissions control technologies that have 

been available in the covered industries 

for many years. See, e.g., 88 FR 36738 

(identifying control technologies for 

EGUs); id. at 36739 (identifying control 

technologies for non-EGUs). These 

analyses were not specific to the 

particular group of upwind states whose 

inclusion the EPA had proposed or 

finalized in the Good Neighbor Plan but 

looked instead at demonstrated 

technologies and associated estimated 

costs across each industry and 

technology type as a whole, without any 

geographic limitation. The EPA 

reasonably considered a wide range of 

technology and cost information 

(including information from examples 

and technical literature throughout the 

U.S. or even internationally) rather than 

just the data available in any particular 

state or regional grouping, since this 

allows for a more comprehensive 

assessment of the technologies available 

and associated costs for each source 

type.37

For EGUs, the EPA conducted an 

inquiry nearly identical to prior good 

neighbor rules, looking at several widely 

available and well-understood NOX

control strategies that can be and have 

been applied to EGUs for decades 

throughout the United States. See 88 FR 

36720. For non-EGUs, the EPA similarly 

consulted a wide range of sources of 

information, starting with national 

databases like the National Emissions 

Inventory and the Control Measures 

Database (CMDB), and proceeding from 

there to additional national and 

international technical literature, as 

well as a variety of existing state and 

federal NOX control requirements. See 

id. at 36732–33; see generally Non-EGU 

Sectors Final Rule Technical Support 

Document (TSD); 38 EGU NOX

Mitigation Strategies Final Rule TSD.39

These included trade association 

literature; academic studies; multi-state 

regional organization publications; state 

rules and publications; contractor 

studies; EPA rules, publications, and 

databases like the RACT/BACT/LAER 

Clearinghouse; European Commission 

publications; operating permits; and 

data on what emissions limits specific 

facilities or companies were achieving. 

See, e.g., Non-EGU Sectors Final Rule 

TSD at 9–11 (reciprocating internal 

combustion engines (RICE)), 27–29 

(cement kilns), 35–39 (reheat furnaces), 

42–43, 45–47 (glass furnaces), 62–65, 

68–84 (boilers), 92–94 (Municipal Waste 

Combustors (MWCs)). 

The EPA derived estimated 

‘‘representative’’ costs for particular 

control strategies for EGUs through a 

wide-ranging analysis of the likely costs 

associated with capital, material, 

equipment, and labor. See generally 

EGU NOX Mitigation Strategies Final 

Rule TSD. The EPA derived its cost 

estimates for non-EGUs primarily from 

the CMDB, which contains a 

compilation of a variety of sources of 

technical literature and examples.40 The 

‘‘representative’’ costs that the EPA 

identified for different levels of control 

stringency and for different industries 

were derived from this nationwide 

analysis and were not specific to the 

particular states included in the 

proposed or final Good Neighbor Plan. 

See 88 FR 36727 (explaining derivation 

of $11,000/ton estimate). The EPA 

reasonably considered a wider range of 

cost information than the data that 

might be available in any particular 

state since it allows for a more 

comprehensive assessment of the costs 

each source type might be expected to 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99117 

41 In response to comments, the EPA conducted 

a sensitivity analysis for EGUs to see if looking at 

control costs on a regional basis would change the 

results and found that it would not. EGU NOX

Mitigation Strategies Final Rule TSD at 49–50. The 

fact that the EPA conducted this as a sensitivity 

analysis to address a comment further illustrates 

that the primary technology and cost analysis the 

EPA conducted, as described in section III.B.2.a., 

was not limited to a 23-state geography and would 

not be altered if that geography were different. 

face.41 While the EPA provided for more 

individualized consideration of the 

costs particular facilities might bear and 

made available alternative emissions 

limits through its implementing 

regulations that could be justified on the 

basis of excessive cost, see 88 FR 

36818–19, the EPA explained that cost 

in the Step 3 analysis ‘‘is not intended 

to represent the maximum cost any 

facility may need to expend but is rather 

intended to be a representative figure for 

evaluating technologies to allow for a 

relative comparison between different 

levels of control stringency.’’ 88 FR 

36740. 

The EPA also used its technology 

analysis to calculate the anticipated 

emissions reductions that could be 

achieved if those strategies were applied 

to the population of sources in each 

state potentially contributing to at least 

one downwind receptor. 88 FR 36737– 

40. At this stage of the analysis, the 

EPA’s assessment of the emissions 

reductions expected from particular 

control strategies under consideration 

again did not depend on the number or 

identity of the states included in the 

Good Neighbor Plan rulemaking itself. 

Rather, these estimates provided the 

inputs by which air quality benefits and 

overcontrol could then be assessed in 

the next stages of the Step 3 analysis 

(discussed next). 

b. Air Quality Benefits 

After compiling the data on available 

technologies, their relative cost-per-ton, 

and the expected emissions reductions 

that would result from each state, the 

EPA’s Step 3 methodology then 

proceeded to evaluate the effect those 

emissions control strategies would have 

on downwind ozone levels. 88 FR 

36741–42. This component of the EPA’s 

analysis looked at the incremental 

ozone improvement that would be 

accomplished at each receptor from the 

reductions accruing from the upwind 

states linked to that particular receptor 

(whether included in a particular rule or 

not) at each of the assessed stringency 

levels. The analysis of air quality 

improvement as the EPA has conducted 

it (in the Good Neighbor Plan and in the 

prior CSAPR rulemakings) displays the 

improvements that are incremental to an 

uneven baseline in which states have 

imposed differing levels of control 

stringency. Another way to think about 

the level of air quality benefit achieved 

would be to assume an uncontrolled 

baseline across all states and then apply 

the different levels of control stringency 

that were evaluated. This would 

illustrate far higher levels of air quality 

benefit as the uniform stringency levels 

are increased but would not credit the 

achievements in emissions control that 

some states have already adopted 

compared to others. 

To calculate air quality change for any 

given upwind state-receptor linkage, the 

relevant group of states assumed to 

make comparable emissions reductions 

will vary, and in the EPA’s primary 

method of analysis, it does not matter 

whether the other upwind states or the 

downwind state are in fact subject to the 

same emissions control requirements. 

Rather the purpose of the analytical 

exercise is to isolate, for comparative 

purposes, the effects of the potential 

stringency levels just to the states that 

are linked to a receptor while also 

assuming that the ‘‘home’’ state 

undertakes an equivalent level of 

stringency with respect to its own 

sources. See 88 FR 36742, 36748–50. 

Thus, the total number of states where 

the EPA has assumed emissions control 

stringencies as part of its Step 3 air 

quality assessment for purposes of the 

Good Neighbor Plan is 30 states. That is, 

the total of the 23 states included in the 

Good Neighbor Plan, the five other 

states that the EPA’s analysis identified 

as potentially or likely to be linked at 

Step 2, plus, for their own receptors, 

Colorado and Connecticut as home 

states, even though they are not linked 

to other states’ receptors. 

The EPA’s conclusions in the Good 

Neighbor Plan did not depend on a 

particular improvement at each 

individual receptor, but rather on an 

assessment that there would be 

widespread improvement in ozone 

levels across receptors in the aggregate 

and on average when the selected level 

of control stringency is applied 

uniformly across upwind states. See 88 

FR 36742–43, 36747–48. In the Good 

Neighbor Plan, as relevant metrics, the 

EPA displayed how ozone levels would 

be expected to change at each receptor, 

what the average effect of the potential 

stringency levels would be across all 

receptors, and what the aggregated effect 

of the potential stringency levels would 

be across all receptors. Id. at 36742–43, 

36747–48. This analytical exercise 

allowed the EPA to evaluate what level 

of stringency was appropriate in terms 

of delivering an acceptable level of air 

quality benefit to downwind receptors 

considering associated costs. 

The role of the air-quality factor in the 

Good Neighbor Plan is essentially no 

different than in CSAPR. 88 FR 36678. 

The CSAPR analysis was conducted on 

a nationwide scale and focused on costbreakpoints of different technologies, 

while also accounting for multiple 

factors other than a singular ‘‘knee-inthe-curve;’’ CSAPR looked holistically 

at both the ‘‘pattern’’ of linkages and the 

‘‘average’’ air quality benefits that could 

be realized at representative cost/ton 

thresholds if those technologies were 

applied uniformly; CSAPR selected 

stringency levels that appeared to 

deliver the greatest air quality 

improvement on average, not state- or 

linkage-specific. See id.; 76 FR 48255– 

59. Likewise, in the Good Neighbor 

Plan, the Agency focused on mandating 

those NOX reduction strategies across 

contributing states that were found to be 

relatively widely-adopted and costeffective on a per-ton basis, with the 

understanding that if these strategies 

were implemented uniformly across the 

upwind-state region, widespread air 

quality improvement would be 

achieved—without tethering that 

conclusion to some precise knee-in-thecurve specific to each linkage or 

receptor. See 88 FR 36741. 

Commenters allege that this analysis 

necessarily depends on the specific 

group of states for which it is 

conducted, since different groups of 

states would have different sets of 

sources, with varying levels of 

emissions control already installed, and 

the application of emissions control 

strategies will have varying effects on 

downwind air quality. Effectively, these 

commenters seem to assert, for its 

methodology to function on an 

individual basis for each state, the EPA 

must determine for each state what level 

of emissions control applied only to its 

own sources would maximize costeffectiveness relative to reducing ozone 

levels at a given downwind receptor. 

Under this theory, if the EPA conducted 

such an analysis, the appropriate level 

of stringency would vary for any 

particular state from what the EPA 

determined was appropriate in the Good 

Neighbor Plan on a uniform basis across 

states—and perhaps a lesser degree of 

stringency would be warranted for 

particular states. 

Fundamentally, these comments 

misapprehend the role of air quality 

improvement in the EPA’s Step 3 

analysis and are, in effect, at odds with 

the EPA’s historical approach that the 

Supreme Court’s opinion in EME Homer 

City upheld, i.e., the use of uniform 

control stringency (using cost as a proxy 

for technology type and compliance 

burden) to allocate responsibility across 


khammond on DSK9W7S144PROD with RULES
99118 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

42See Air Quality Modeling Final Rule TSD, 2015 

ozone NAAQS Good Neighbor Plan, appendix E, 

available in the docket at https://

www.regulations.gov/document/EPA-HQ-OAR2021-0668-1157. 

43Even here, however, caution is in order. A 

highly cost-effective strategy may not deliver 

incremental air quality improvement from a given 

baseline because that strategy has already been 

adopted by sources in a particular state or states. 

In that case, a rule imposing that strategy would not 

create new emissions reduction obligations but 

would be appropriate to prevent backsliding. Cf. 

EME Homer, 572 U.S. at 519–20 (noting the uniform 

approach appropriately treats states where sources 

have already invested in pollution control). 

Likewise, the EPA’s good neighbor rules have 

always applied to both new and existing sources. 

See 88 FR 36685. If a particular industry is not 

currently present in a particular state but could 

have high uncontrolled emissions if it located there, 

good neighbor rules serve as a backstop to ensure 

a minimum level of emissions performance will be 

maintained from those sources, in those states that 

have been deemed to contribute to another state’s 

nonattainment or maintenance issues. Nonetheless, 

the basic emissions-performance requirements of a 

good neighbor rule in those cases should not be 

onerous for a new source. 

multiple upwind states despite varying 

effects of that stringency to downwind 

receptors. 572 U.S. at 518–19. 

Consistent with the same statutory 

interpretation and methodology the EPA 

has applied throughout each of its prior 

good neighbor rulemakings for ozone, 

the Good Neighbor Plan is not premised 

on accomplishing a precise, aggregate 

air quality result at each receptor, such 

that the omission of some states (even 

if they were legally exempted from 

obligations rather than simply under a 

temporary stay order or did not yet have 

their obligations addressed through a 

SIP or FIP) would increase the ‘‘share’’ 

of the problem that must be addressed 

by the remaining states. Rather, the 

Good Neighbor Plan holds the 

industries in each contributing upwind 

state subject to a federal plan to a 

uniform, minimum level of emissions 

performance deemed to be costeffective. So long as they meet that level 

of performance, the industries in any 

state regulated under the Good Neighbor 

Plan are understood to have lawfully 

addressed good neighbor obligations 

and eliminated that portion of a state’s 

significant contribution to downwind 

air pollution. 

Even though this methodology does 

not purport to achieve attainment at all 

downwind receptors, it is consistent 

with the EPA’s and the courts’ 

understanding of the good neighbor 

provision. Under that provision, it is not 

upwind states’ responsibility to ensure 

that downwind receptors are brought 

into attainment; each state must only 

eliminate its own significant 

contribution to nonattainment or 

interference with maintenance of the 

NAAQS in other states. CAA section 

110(a)(2)(D)(i)(I). In reviewing the 

division of responsibility under this 

contribution standard, courts have 

upheld the EPA’s approach as a 

reasonable way to allocate good 

neighbor obligations among multiple 

states for regional-scale pollutants like 

ozone, even though the air quality 

benefits resulting from a particular 

degree of control stringency will 

necessarily vary by state and receptor. 

This variation in effect is the 

consequence of an approach that 

respects several well-understood 

characteristics of the interstate ozone 

problem: the ‘‘overlapping and 

interwoven linkages between upwind 

and downwind States,’’ ‘‘the vagaries of 

the wind’’ (i.e., the variability in 

meteorological conditions that makes 

precise ozone projections impossible), 

and the wide variation in the degree of 

baseline levels of emissions control that 

different states have already achieved. 

EME Homer City, 572 U.S. at 496–97, 

519–20; see also Wisconsin, 938 F.3d at 

322; Michigan, 213 F.3d at 679–80. 

Commenters may believe that the EPA 

could at least establish different levels 

of cost-effective control stringency for 

each group of states linked to a 

particular receptor, rather than 

considering air quality improvement in 

the aggregate across all receptors—i.e., 

to pick a knee in the curve that is 

specific to each particular receptor. 

Setting aside the problem of 

meteorological variability, this still 

presents the same problem the EPA 

faced in CSAPR, as recognized in EME 

Homer City: each set of states for one 

receptor has overlap with a different set 

of states for a different receptor.42 Thus, 

for any given state, there cannot 

mathematically be a single, ‘‘correct’’ 

‘‘knee-in-the-curve’’ that defines a 

maximally cost-effective stringency. 

EME Homer City, 572 U.S. at 514–18. 

Thus, as was the case in CSAPR, an 

approach that requires high-emitting 

sources in each state to come up to a 

uniform level of cost-effective emissions 

control, so long as it does not 

overcontrol, functions as a reasonable 

definition of each covered state’s 

‘‘significant contribution,’’ and fulfills 

those covered upwind states’ legal 

obligations under the good neighbor 

provision. 88 FR 36675–76, 36741. 

Both the Supreme Court and the D.C. 

Circuit have recognized that variation in 

what a good neighbor rule will achieve 

at any particular receptor is a logical 

consequence of defining ‘‘significance’’ 

through identifying a uniform level of 

emissions control based on costeffectiveness. As the Supreme Court 

explained in EME Homer City, ‘‘by 

imposing uniform cost thresholds on 

regulated States, EPA’s rule subjects to 

stricter regulation those States that have 

done relatively less in the past to 

control their pollution’’ and ensures that 

‘‘[u]pwind States that have not yet 

implemented pollution controls of the 

same stringency as their neighbors will 

be stopped from free riding on their 

neighbors’ efforts to reduce pollution.’’ 

EME Homer City, 572 U.S. at 519. The 

fact that a particular state may have a 

very small emissions reduction 

obligation, and so improve downwind 

air quality by a very small amount, does 

not call the approach into question. The 

fact that a state may have less to do to 

meet the EPA’s selected levels of 

emissions control may reflect that its 

sources are already well controlled. But 

whether a state’s required reductions 

under a FIP applying this methodology 

are large or small, the approach allows 

for a fair alignment of investments in 

pollution control across all of the 

contributing states, which is at the heart 

of the methodological construct the 

Court approved in EME Homer City. See 

Wisconsin, 938 F.3d at 322 (concluding 

that the EPA reasonably regulated 

sources in Wisconsin, a contributing 

upwind state whose available costeffective reductions would only benefit 

downwind air quality ‘‘by just two tenthousandths of a part per billion’’). 

This is not to say that delivering air 

quality improvement to the downwind 

receptors is not important—indeed, it is, 

as the EPA described in the Good 

Neighbor Plan, a ‘‘central component’’ 

of the EPA’s analysis. 88 FR 36741. If 

the identified control strategies that 

were cost-effective on a cost-per-ton 

basis did not have any effect on 

downwind air quality at any receptors, 

this may call into question whether 

requiring those strategies was worth it.43

Thus, the Good Neighbor Plan explains 

that the purpose of the EPA’s air quality 

analysis at Step 3 is to check on whether 

a level of emissions reduction that 

appeared cost-effective on a cost-per-ton 

basis would in fact deliver measurable 

progress toward attainment of the 2015 

ozone NAAQS at the downwind 

receptors. ‘‘These analytical findings 

cement EPA’s identification of the 

selected EGU and non-EGU mitigation 

measures as the appropriate control 

stringency . . . .’’ 88 FR 36741. 

The EPA’s analysis in the Good 

Neighbor Plan demonstrates that with 

each incremental increase in the 

stringency of the assessed control 

strategies, there is also incremental 

improvement in air quality at the 

receptors. See, e.g., 88 FR 36743, 36747– 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99119 

44Available in the docket at https://

www.regulations.gov/document/EPA-HQ-OAR2021-0668-1080. 

45As always, states remain free to identify 

different emissions control measures through a SIP 

than the EPA has included in a FIP, and it may be 

possible for a state to demonstrate that it can 

control other sources to obtain equivalent or greater 

air quality results at its receptors. A SIP submission 

to the EPA obtaining those emissions reductions 

through permanent and enforceable measures 

applied to its in-state emissions sources 

accompanied by the appropriate analytical and 

technical justifications would likely be approvable 

to replace a good neighbor FIP. 

46The EPA has previously evaluated Step 3 

alternatives to the ‘‘uniform approach’’ taken in the 

Good Neighbor Plan and prior ozone transport 

rules, including an evaluation of methods such as 

a receptor-specific proportionality approach. The 

alternative methods, as well as potential issues that 

the Agency identified can be found in the 

‘‘Alternative Significant Contribution Approaches 

Evaluated TSD’’ included in the CSAPR rulemaking 

docket (Docket ID No. EPA–HQ–OAR–2009–0491– 

0077). In responding to comments in that 

rulemaking about ‘‘proportionality’’ approaches, the 

Agency identified concerns that included, but were 

not limited to, requirements of an ‘‘extremely high 

level of accuracy in both the emissions modeling 

. . . and the air quality modeling’’ and that ‘‘finerscale emissions data from all sectors . . . . and 

fine-scale air quality modeling could be needed to 

resolve differences in cost per air quality impact.’’ 

The EPA explained that ‘‘these data and modeling 

techniques do not exist and/or are too 

computationally demanding to be operationally 

implemented.’’ The EPA continued, ‘‘A second 

challenge for this approach was to identify a single 

reduction requirement for a particular upwind 

State, since the reduction requirements relevant to 

different downwind receptors would vary 

significantly.’’ See CSAPR ‘‘Transport Rule Primary 

RTC’’ document 743 (Docket ID No. EPA–HQ– 

OAR–2009–0491–0077). 

48 (tables showing air quality 

improvement at each receptor); Ozone 

Transport Policy Analysis Final Rule 

TSD at 70 (table C–12) (Ozone Policy 

TSD) (showing reductions in the 

maximum contribution of each upwind 

State to receptors in 2026).44 Further, 

the Agency explained that it could not 

identify a point of diminishing returns 

within the suite of emissions control 

strategies that it ultimately selected. 88 

FR 36741. The Agency also cautioned 

that the purpose of this exercise was not 

to pinpoint a precise ‘‘knee-in-thecurve’’ but to serve as ‘‘a useful 

indicator for informing potential 

stopping points.’’ Id. Thus, the EPA’s 

review of the effects of different 

emissions-reduction strategies on air 

quality primarily helps the Agency 

ensure that no impactful emissions 

reduction strategies have been 

overlooked and that those selected can 

be anticipated to deliver reductions in 

ozone at the identified receptors if 

applied consistently across all of the 

upwind states linked to each receptor 

(including each receptor’s home state). 

Commenters have not put forward an 

alternative, more cost-effective 

methodology or set of emissions-control 

strategies for reducing ozone at the 

downwind receptors; rather, they seek 

to avoid emissions control obligations in 

one state on the basis that the Good 

Neighbor Plan may not be operative in 

another. However, the EPA has an 

ongoing statutory obligation to issue 

FIPs for those states where it has issued 

a SIP disapproval or made a finding of 

failure to submit. In the absence of 

information detailing that cost-effective 

emissions reduction opportunities have 

been overlooked that would have an 

even greater benefit on ozone levels at 

downwind receptors, the EPA 

reasonably concluded that its 

identification of emissions limitations 

consistent with the cost-effective 

emissions control technologies that it 

has identified to be widely available at 

the new and existing EGU and non-EGU 

sources in the states covered by the 

Good Neighbor Plan passed its Step 3 

air quality check, and these measures 

would constitute a sufficient and 

appropriate definition of ‘‘significant 

contribution’’ for these states.45

Although the air quality benefits to 

downwind receptors anticipated in the 

Good Neighbor Plan would not be fully 

realized so long as certain states have 

not yet fulfilled their obligations, this 

does not serve as a justification for 

allowing these obligations for those 

states where the EPA has a 

responsibility to act to go unaddressed 

or to be altered. Simply put, the CAA 

requires each state to address its own 

contributions to downwind air quality 

problems, regardless of whether other 

states have taken action to do so under 

a SIP or a FIP. That other states 

contributing to downwind receptors 

may have their good neighbor 

obligations stayed or not yet addressed 

does not relieve other states covered by 

the Good Neighbor Plan of their own 

good neighbor obligations under CAA 

section 110. Given the state-by-state 

procedural framework of the Act and 

the need for the EPA to develop 

equitable and consistent FIPs, it cannot 

be the case that the EPA must 

successfully simultaneously resolve all 

states’ good neighbor obligations at once 

or lose the authority to act. Though the 

EPA has done its best to achieve 

consistent, timely, and concordant 

implementation of these obligations, 

like the construction of a jigsaw puzzle, 

each individual piece (i.e., each 

individual state’s obligations) is 

necessary to complete the whole 

picture, and not every piece may be 

connected at once. 

Commenters attempt to fault the EPA 

for developing a methodology that they 

claim necessarily depends on the 

inclusion of other states. Setting aside 

that for the reasons explained here the 

methodology does not depend on 

simultaneous inclusion (or even full 

inclusion, if states address their good 

neighbor obligations in some other 

adequate way through a SIP), the 

problem commenters identify is not in 

the particular methodology that the EPA 

uses but in the science of ozone 

transport as a multistate problem 

characterized by meteorological 

variability and overlapping linkages, 

coupled with the state-by-state 

implementation structure of the Act. 

Under these constraints, any 

methodology would need to take into 

account the relative contributions of and 

the effects of air pollution control 

technologies in other states. 

To perform the air quality check for 

any particular receptor, it makes sense 

to consider the effect of emissions 

reductions from all of the states linked 

to that receptor, not just those covered 

by a particular FIP rulemaking, because 

all states must ultimately discharge their 

good neighbor obligations whether 

through an approved SIP or a FIP. Thus, 

the Step 3 air quality analysis is a ‘‘test’’ 

that serves to confirm that an 

appropriate degree of emissions-control 

stringency has been reached for any 

given state without overcontrolling. It 

does not depend on the actual, 

simultaneous inclusion of a certain 

number of states in a given rulemaking; 

however, it appropriately accounts for 

the reality that multiple states are linked 

to multiple other states and that the 

amount of emissions reduction 

necessary to achieve attainment varies 

among receptors. This complexity, 

recognized for years by the EPA and by 

the Supreme Court in EME Homer City, 

572 U.S. at 514–17, makes it analytically 

inappropriate if not impossible to assign 

an obligation to each state that is simply 

proportional to its contribution to a 

particular receptor. See 88 FR 36683.46

Nonetheless, that does not prevent the 

EPA (or for that matter an individual 

upwind State) from being able to 

conduct a Step 3 test looking at the 

effects of uniform control stringencies 

using a publicly available tool such as 

the Air Quality Assessment Tool 

(AQAT). Given the multistate nature of 

the interstate ozone pollution problem, 

analysis of the air quality benefit 

produced by regulating sources in any 

particular upwind state assumes that 

other states linked to a common 

receptor and the home state of that 

receptor make emissions reductions at a 

comparable level of emissions control 


khammond on DSK9W7S144PROD with RULES
99120 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

47Notably, the EPA highlighted that its forwardlooking air quality projections are subject to 

inherent uncertainty given the many factors that 

influence ozone formation. 88 FR 36750. And the 

EPA acknowledged that states in the future may 

conduct updated air quality analysis that may differ 

from its own analytics in the rule. Id. at 36839–40; 

id. n. 405. Still, in the absence of particularized 

evidence of overcontrol and faced with a 

concomitant duty to avoid under-control, id. at 

36684 (citing 572 U.S. at 523), the EPA’s approach 

yields a set of emissions reduction obligations that 

would be reasonable in a robust way across all 

covered large-emitting sources in any contributing 

state that may eventually become subject to a good 

neighbor FIP for the ozone NAAQS. 

48 Due to data limitations at the time of finalizing 

the Good Neighbor Plan, the analysis did not 

include an assessment of the effects from non-EGUs 

in Arizona, even though Arizona is linked through 

the 2026 analytic year. Otherwise, in the AQAT 

analysis of the Good Neighbor Plan, data informing 

the EPA’s Step 3 air quality evaluation included 

every monitor in the contiguous United States, with 

contributions adjusted for each state that was either 

linked above 1 percent of the NAAQS in the 

relevant analytic year or was a home state for the 

receptor. 

49The EPA acknowledges that certain language in 

the Ozone Policy TSD for the Final Good Neighbor 

Plan may have been inartful or unclear on this 

point. For example, that document stated at page 3 

that it was focused on the ‘‘23 upwind States that 

were linked’’ and included in that rule. This was 

true in a sense, because the TSD was done in 

support of that rule, which covered 23 states. 

However, the underlying data and evaluation of the 

effects of emissions change on air quality 

encompassed the entire contiguous U.S., and the 

TSD displayed anticipated air quality improvement 

at identified receptors by reference to all upwind 

states (and ‘‘home’’ states) and was not limited only 

to the 23 states included in that rule. Results for 

Kansas and Tennessee were not displayed in the 

TSD because a final determination had not been 

made to consider these states linked based solely 

on violating-monitor receptors. See 88 FR 36707. 

However, the underlying AQAT spreadsheets used 

for the Ozone Policy TSD analysis included the 

reductions from these states in the data made 

available to understand the effects of the evaluated 

emissions control strategies. See, e.g., Ozone AQAT 

Results, tab: ‘‘2023_step3_newSCR_wIRA’’, cols. I– 

BF, available in the docket at https://

www.regulations.gov/document/EPA-HQ-OAR2021-0668-1116. 

regardless of whether they are covered 

by the Good Neighbor Plan. 

It is true that the EPA’s analysis of air 

quality change at Step 3 uses statespecific data and calibration factors. See 

Ozone Transport Policy Analysis Final 

Rule TSD at 43. Commenters may have 

had uncertainty concerning the 

respective roles of state-level versus 

national-level analytical determinations 

within the air quality analysis at Step 3, 

with a potential concern being that if 

the EPA was relying on state-level 

determinations, then the stringency of 

the Good Neighbor Plan would be 

dependent on particular state groupings. 

But this would over-interpret the role of 

these particular datapoints in the larger 

analysis. State-level emissions data and 

calibration factors ensure an accurate 

representation of the effects of 

emissions reductions across the 

different States. However, this does not 

imply the Good Neighbor Plan fails to 

define obligations on a reasonable basis 

for each state. To the contrary, it 

confirms that the EPA’s analysis already 

accounts for the emissions reductions 

and air quality change that can be 

anticipated from each state individually, 

rather than merely treating them as an 

undifferentiated regional mass specific 

to the group of states included in a 

particular rulemaking. More 

importantly, as described above, the 

regulatory conclusions the EPA drew 

from the AQAT analysis focused not on 

the individualized outcomes of each 

linkage but rather on the averaged and 

aggregated data drawn from that 

analysis for the entire country, which 

‘‘cemented’’ the EPA’s finding that an 

overall appropriate level of stringency 

was obtained, without overcontrolling. 

88 FR 36741, 36747–48.47

Illustrating that the Good Neighbor 

Plan’s regulatory conclusions were 

drawn from this nationwide assessment 

of air quality effects of different control 

stringencies, rather than from the 

particulars of the 23-state grouping 

included in the Good Neighbor Plan, the 

EPA’s primary Step 3 air quality and 

overcontrol analysis in the Good 

Neighbor Plan included any other 

linked upwind states found at Steps 1 

and 2 of the EPA’s framework, 

regardless of whether or not they were 

included in the Good Neighbor Plan, on 

the view that this was the most 

appropriate way to analyze the 

collective effects of identified stringency 

levels at Step 3. See Ozone Policy TSD 

at 46, 55 (explaining that the EPA 

included all upwind states modeled to 

be contributing in this assessment, i.e., 

including states that were not presently 

included in the Good Neighbor Plan but 

might be through a future rule, such as 

Iowa, New Mexico, and Arizona 48). 

Accordingly, the EPA’s Step 3 air 

quality analysis did not rely on a 23- 

state scope of coverage, and nowhere in 

the record for the Good Neighbor Plan 

did the EPA state or imply that its 

methodology relied on a 23-state scope 

of coverage.49 For any particular 

receptor, the EPA’s analysis looked at 

the group of upwind states linked to 

that receptor in the modeling (the 

numbers of which vary), and also 

assigned the home state for that receptor 

a ‘‘fair share’’ (i.e., the same stringency 

that would be imposed in the upwind 

states for that receptor). 88 FR 36742 

n.238. The analysis did not depend on 

the actual inclusion of those particular 

states in the Good Neighbor Plan; it 

simply looked at what the effect would 

be if, for any given upwind state and 

any given receptor, the other upwind 

linked states and the downwind state 

were held to the same stringency level. 

Stated differently, the EPA’s analysis 

identified a total of 28 states as 

contributing at Step 2. 88 FR 36709–12. 

As such, subject to the caveats in notes 

48 and 49 supra concerning certain 

limitations in the data, the EPA 

appropriately assessed the effect of 

applying the uniform levels of 

emissions control stringency across all 

contributing States to any given receptor 

(i.e., varying combinations of the 28 

states plus home state for each 

receptor)—regardless of their inclusion 

in the Good Neighbor Plan—in 

evaluating whether the Good Neighbor 

Plan reasonably addresses the 

‘‘significant contribution’’ of any 

particular state. 

The emissions control measures 

identified at Step 3 do not depend on 

which particular states adopt costeffective controls as part of the EPA’s 

analysis of air quality benefits. The role 

of the air quality analysis is simply to 

verify that the cost-effective controls 

identified by the EPA for any particular 

state would, in fact, have an impact on 

downwind receptors if they were 

uniformly adopted in all states 

contributing to that receptor (and the 

home state), without overcontrolling. 

Whether all of those states ultimately 

adopt those emissions controls, or do so 

simultaneously, or adopt equivalent 

controls but on different sources, or may 

otherwise develop an alternative 

approach that is approvable for that 

particular state, does not affect the 

EPA’s determination at Step 3 that those 

controls, as to the state(s) where the 

EPA applies them through FIP(s), are 

cost-effective—and that the sets of 

sources within any individual state 

must achieve performance consistent 

with those controls to satisfy the state’s 

good neighbor obligations. 

Thus, the EPA’s analysis of air quality 

benefits at Step 3 was not limited to the 

specific set of states expected to be 

covered by a FIP, but appropriately 

considered the cost-effective emissions 

reductions available from all upwind 

states linked to each downwind receptor 

(as well as the receptor’s home state). 

Consistent with the Act, that 

methodology functions as an 

appropriate analytical method to define 

any particular state’s good neighbor 

obligations for ozone and does so 

without requiring, or possessing 

definitive knowledge, that the same 

methodology would be applied in other 

states. 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99121 

50As explained in section III.B.2.b., the primary 

air quality assessment at Step 3, including for 

purposes of evaluating overcontrol, looks at the 

effects on ozone levels of different levels of 

emissions control across all upwind states found to 

be contributing to a particular receptor (plus the 

home state), not just the states included in a 

particular rulemaking. In the Good Neighbor Plan, 

the EPA ran the AQAT analysis for a total of 28 

linked upwind states, not just the 23 states included 

in the rule. See note 49 supra. 

51Screening Assessment of Potential Emissions 

Reductions, Air Quality Impacts, and Costs from 

Non-EGU Emissions Units for 2026, available in the 

docket at https://www.regulations.gov/document/ 

EPA-HQ-OAR-2021-0668-0150. 52We developed the Screening Assessment using 

inputs from the air quality modeling for the Revised 

CSAPR Update for 2023 (2016v1), as well as the 

projected 2023 annual emissions inventory from the 

2016v2 emissions platform that was used for the air 

quality modeling for the proposed Good Neighbor 

Plan. Screening Assessment at 1–2. 

53The differences in states identified in the 

2016v1 modeling compared to the states the EPA 

identified as linked for the 2023 analytic year using 

2016v3 modeling and the violating-monitor 

receptor identification methodology are as follows: 

Delaware and Wyoming were linked in 2016v1 and 

Arizona, Kansas, and New Mexico were not. The 

linkages used in the Screening Assessment (for 

2023) also reflected a slightly different set of states 

than the EPA expected, at the time of proposal, to 

be linked in 2026. Compare Screening Assessment 

at 2 with 87 FR 20036, 20041 (proposing to apply 

non-EGU measures in 23 states, not including 

Alabama, Delaware, Iowa, or Tennessee). 

c. Overcontrol Assessment 

Finally, at Step 3, the EPA ‘‘tests’’ 

whether its selected uniform emissionscontrol stringency levels result in any 

‘‘overcontrol.’’ 88 FR 36749–50. In EME 

Homer City, the Supreme Court held 

that the EPA cannot ‘‘require[] an 

upwind State to reduce emissions by 

more than the amount necessary to 

achieve attainment in every downwind 

State to which it is linked.’’ 572 U.S. at 

521. To find overcontrol, the EPA must 

conclude that the uniform control 

stringencies the EPA selected produced 

more emissions reductions and resulting 

air quality improvements than necessary 

to resolve all of any state’s linkages to 

downwind receptors, or more than 

necessary to bring receptors into 

attainment. In that case, under the 

overcontrol holding in EME Homer City, 

the EPA would need to adjust the 

requirements of the rule to avoid 

overcontrol. This overcontrol 

assessment is conducted using the same 

air quality effects analysis derived from 

AQAT, described in section III.B.2.b. 

If the Good Neighbor Plan were to be 

suspended from operation in some 

number of upwind states, this could not 

result in overcontrol, because the 

analysis (presented in the Ozone Policy 

TSD) demonstrates no overcontrol even 

when all upwind states found to be 

contributing are included—much less 

the 23 states included in the originally 

promulgated Good Neighbor Plan 

itself.50 As long as fewer states are 

making fewer emissions reductions, the 

downwind receptors cannot be cleaner 

than they were under the Good 

Neighbor Plan’s original scope. See 88 

FR 36749–50. 

d. Other Elements of the Non-EGU Step 

3 Analysis 

To ensure a complete response to the 

commenters, the EPA has reviewed in 

greater detail all elements of the Step 3 

methodology of the Good Neighbor Plan 

to evaluate whether any components of 

its analysis pose a concern that the 

EPA’s analytical findings are not 

severable among the various states. Two 

elements of the EPA’s technology and 

cost analysis for non-EGUs in the Good 

Neighbor Plan incorporate analytical 

methodologies related to some extent to 

the upwind region covered by the rule 

and warrant further discussion here. 

These are: (1) the identification of 

potentially impactful industries in the 

‘‘Screening Assessment’’ used in the 

Good Neighbor Plan to assist the EPA in 

narrowing the scope of industries to be 

included in its non-EGU regulations; 

and (2) the ‘‘weighting’’ of average costs 

for two non-EGU industries and a 

specific emissions unit type (boilers) 

where multiple control technologies 

were identified at Step 3. The EPA has 

reviewed, based on the record for the 

Good Neighbor Plan, whether either of 

those elements materially influenced 

the determination of each state’s 

‘‘significant contribution.’’ As explained 

in the ‘‘Use of Screening Assessment to 

Identify Potentially Impactful 

Industries’’ and ‘‘Weighted Averaging 

Costs’’ below, they did not. Neither of 

these aspects of the analysis suggest that 

the EPA should reach different 

conclusions as to each covered state’s 

‘‘significant contribution’’ while the 

Good Neighbor Plan applies in a 

different group of States. 

Use of Screening Assessment To 

Identify Potentially Impactful Industries 

For non-EGUs, the EPA elected to 

screen for industries and emissions-unit 

types appropriate for analysis of costeffective NOX reductions. While power 

plants have consistently been 

understood to have high levels of 

controllable NOX emissions and have 

been included in each good neighbor 

rulemaking, non-EGUs have not been 

consistently addressed. See 88 FR 

36720. Certain non-EGU industries and 

emissions units/sources were included 

in the 1998 NOX SIP Call, but not in 

subsequent rules, although the EPA had 

acknowledged that such sources may 

necessitate regulation to prohibit 

significant contribution and had in the 

past analyzed such sources on a 

‘‘parallel track’’ to its EGU analysis at 

Step 3. See 88 FR 36719. For the 2015 

ozone NAAQS, the EPA concluded that 

it could not determine it could 

eliminate the entirety of the covered 

states’ ‘‘significant contributions’’ to 

downwind nonattainment by addressing 

power plants alone. 88 FR 36680–82. To 

that end, the EPA was required to look 

beyond the power sector, and when it 

did so, the EPA determined that certain 

large industrial sources have substantial 

amounts of ozone-precursor emissions 

that could be cost-effectively controlled 

and therefore, consistent with its 

longstanding methodology, should be 

obligated to reduce those emissions, so 

long as such measures would not result 

in ‘‘overcontrol.’’ Id. at 36660–61. 

Because the potential number of 

industries and source types is large, the 

EPA used a screening methodology to 

assist in narrowing the scope of 

industries to be potentially regulated to 

those with potential cost-effective NOX

reductions. 

To screen for industries and 

emissions-unit types to further assess 

for cost-effective NOX emissions 

reductions, the EPA prepared a 

‘‘Screening Assessment.’’ 51 In the 

Screening Assessment, the EPA used 

emissions and control technology 

information to screen for industries and 

emissions unit types where emissions 

reductions were more likely to be costeffective and to screen out industries 

where emissions reductions were less 

likely to be cost-effective. As part of this 

analysis, the EPA used air quality 

criteria to identify how emissions 

reductions from industries and 

emissions units would likely benefit 

downwind areas. See Screening 

Assessment at 1–3. This analysis used 

modeled nonattainment and 

maintenance receptors in 2023 and an 

inventory of sources in those upwind 

states that were identified using the air 

quality modeling that was available at 

the time the EPA was developing the 

assessment.52 See Screening Assessment, 

appendix A (table A–3). This modeling 

had identified 27 states as upwind 

contributors to at least one downwind 

receptor. In conducting its screening 

analysis, the EPA took these states to be 

broadly representative and appropriate 

for the purpose of screening non-EGU 

NOX sources by industry across a large 

set of upwind states, as identified by the 

then-available modeling.53

The EPA concluded in finalizing the 

Good Neighbor Plan that this portion of 

the non-EGU analysis did not need to be 

redone on the basis of changes in the 

scope of coverage of the rule. See Good 


khammond on DSK9W7S144PROD with RULES
99122 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

54Had the EPA approached the identification of 

‘‘significant contribution’’ from non-EGU emissions 

sources differently, it still would have needed to 

assess overcontrol and would have excluded 

emissions reduction measures falling outside the 

range of technologies deemed cost-effective. 

55Again, illustrating the EPA’s consistent 

understanding of this comparative purpose, the 

Agency rejected other comments calling for the 

Screening Assessment to be redone on the basis of 

updated information concerning specific non-EGU 

facilities, which various commenters attempted to 

use to argue the EPA’s data were out-of-date. ‘‘Even 

if some amount of the emissions identified as 

potentially controllable in the Screening 

Assessment are already being achieved, or such 

potentially controllable emissions cannot be 

feasibly controlled and are not being required in 

this final rule, that does not undermine the 

Agency’s conclusions in the Screening Assessment 

regarding the potential impact of a given industry.’’ 

Good Neighbor Plan RTC at 120 (emphasis added). 

Neighbor Plan RTC at 104 (‘‘The 

purpose [of the Screening Assessment] 

is not a precise replication of exactly 

which sources contributed exactly how 

much to any particular receptor during 

a particular high-ozone event. The 

purpose is to identify those industries 

with relatively large emissions sufficient 

to have interstate effects on ozone 

levels, and to analyze emissions units 

within those industries further for costeffective emissions reduction 

opportunities.’’). Thus, the EPA was 

clear in the record of the Good Neighbor 

Plan that the Screening Assessment 

served an important but limited 

purpose: to screen for industries and 

emissions-unit types where further 

analysis was likely to identify more 

impactful and less costly emissions 

reduction opportunities. See also 88 FR 

36740; Good Neighbor Plan RTC at 90– 

92. 

Consistent with the statutory language 

of the good neighbor provision, the EPA 

could have chosen to forgo this analysis, 

which assisted the Agency in narrowing 

the set of non-EGU industries and 

emissions source types it considered for 

inclusion in the Good Neighbor Plan, 

and include more stationary industrial 

sources of NOX. See CAA section 

110(a)(2)(D) (authorizing regulation of 

‘‘any source or other type of emissions 

activity’’ for significant contribution); 

see also 88 FR 36680–81.54 However the 

EPA might have proceeded, in the rule 

the Agency was appropriately informed 

by a longstanding understanding of 

regional-scale ozone transport, which is 

that the control of any large sources of 

NOX emissions in linked upwind states 

will generally beneficially affect 

downwind ozone levels. 88 FR 36719. 

While states are afforded discretion 

under the Act to select the control 

measures they would prefer to use to 

meet the Act’s requirements, such 

discretion devolves to the EPA when it 

steps into the shoes of a state under 

CAA section 110(c). Id. at 36675 

(collecting case law). Within the 

exercise of that discretion, the EPA’s 

method of proceeding made sense. The 

EPA’s approach provided a technically 

rigorous method for narrowing the 

industries in a manner that treated each 

industry similarly. As the EPA 

explained in rejecting comments that its 

modeling projections in the Screening 

Assessment were too imprecise, the 

Assessment was done not for the 

purpose of ‘‘project[ing] changes in air 

quality in an absolute sense,’’ but rather 

to ‘‘conduct a comparative analysis 

among different industries,’’ where the 

EPA’s modeling techniques ‘‘would 

apply consistently and equally to each 

industry the EPA evaluated.’’ Good 

Neighbor Plan RTC at 105.55

This approach of identifying uniform 

emissions control opportunities at the 

industry-level rather than based on a 

state-by-state or unit-by-unit impact 

analysis accords with the way the EPA 

has analyzed emissions control 

opportunities from both EGUs and nonEGUs throughout the history of 

implementation of the good neighbor 

provision. See id. at 92 (quoting 63 FR 

57399 (uniformity at industry level 

‘‘assure[s] equity among the various 

source categories and the industries 

they represent’’)); 88 FR 36683 

(explaining that the EPA’s analysis of 

non-EGUs sources ‘‘parallels the 

analysis previously conducted only for 

EGUs’’ and ‘‘relies on evaluation of 

uniform levels of control stringency 

across all upwind states’’). When 

commenters argued that the EPA had 

not adequately established that their 

particular facilities were sufficiently 

impactful to be worth regulating, the 

EPA rejected this mode of analysis: 

[I]t was entirely reasonable, and consistent 

with prior transport rulemakings to focus the 

analysis at the industry-level rather than 

attempt to identify air quality impact 

thresholds at the unit- or source-specific 

level. To build on the response above, it is 

important to keep in mind that regional 

interstate ozone transport is a ‘‘collective 

contribution’’ problem, in which the ozoneprecursor emissions of many sources 

combine to create ozone nonattainment and 

maintenance problems at potentially great 

distances from individual source emissions 

points. Attribution of responsibility for this 

problem is complicated by varying 

meteorological conditions from year to year 

and even from day to day. The EPA’s Step 

1 and Step 2 analysis within the 4-step 

interstate transport framework is designed to 

robustly identify where ozone problems are 

located and which states’ anthropogenic 

emissions contribute to those problems. At 

Step 3, the analysis shifts to an evaluation of 

which emissions reductions from those 

contributing states would be most costeffective to achieve to eliminate that portion 

of the states’ emissions that are deemed 

‘‘significant’’ and thus must be eliminated. 

Focusing on entire industries (as the EPA has 

done in prior rules with its focus on EGUs 

(e.g., CAIR and CSAPR)) and other industry 

categories in addition to EGUs (as we did in 

the NOX SIP Call) presents an efficient and 

equitable methodology for identifying where 

the most cost-effective emissions reductions 

can be identified at the regional scale. 

Good Neighbor Plan RTC at 98 (citing 

63 FR 57386); see also 88 FR 36685 

(similar reasoning supports including 

new sources of the same type as existing 

sources in good neighbor 

implementation plans); id. at 36746–47 

(explaining that uniform control by unit 

type avoids risk of production and 

emissions shifting). In short, when the 

EPA must devise a federal solution to 

interstate ozone transport for one or 

more states, its objective is to 

implement measures that are 

comprehensive, durable, and robust, not 

to engage in a never-ending game of 

whack-a-mole at each emissions point. 

The Screening Assessment was one 

step along the way of focusing the 

Agency’s limited resources and 

narrowing the scope of the regulation of 

NOX emissions ‘‘sources’’ and 

‘‘activities’’; it was not intended to 

dictate final determinations regarding 

‘‘significant contribution.’’ See, e.g., 

Good Neighbor Plan RTC at 97–99, 101. 

The EPA concluded when finalizing the 

Good Neighbor Plan that its initial 

Screening Assessment—although based 

on a slightly different group of states 

than at final (and the use of other data 

regarding baseline emissions levels and 

air quality conditions that was subject to 

change)—had served its purpose in 

helping to identify a reasonable starting 

point for further analysis of non-EGU 

emissions-control opportunities and did 

not need to be redone. See 88 FR 36685, 

36719. 

The Screening Assessment served that 

purpose for each state where it had a 

responsibility to regulate non-EGU 

emissions, and the Good Neighbor 

Plan’s ultimate identification of nonEGU emissions control strategies to 

eliminate ‘‘significant contribution’’ is 

likewise sound for any state or grouping 

of states that may necessitate such 

federal regulation. Nonetheless, as is 

always the case with regard to meeting 

the CAA’s requirements, states remain 

free to address a different set of sources 

than the EPA identified in the Good 

Neighbor Plan if they prefer to regulate 

through a SIP in a manner different than 

the EPA proceeded in the FIP. Id. at 

36842. 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99123 

‘‘Weighted’’ Averaging of Costs 

In the EPA’s final analysis of nonEGU representative costs in the Good 

Neighbor Plan, for two industries 

(Pipeline Transportation of Natural Gas 

and Solid Waste Combustors and 

Incinerators) and a specific emissions 

unit type (boilers), the Agency 

identified a weighted average of costs to 

address multiple control technologies 

identified in the Step 3 analysis, rather 

than a single control technology. 88 FR 

36739–40 (table V.C.2–3). For those 

industries and for boilers, the analysis 

weighted the average cost according to 

the control technologies that certain 

sources, anticipated to be subject to the 

Good Neighbor Plan across the 20 states 

with non-EGU requirements, might 

select as their method of compliance. 

Representative costs for these sources 

were calculated by weighting the 

average costs derived from national data 

sources by estimated emissions 

reductions for the applicable control 

technologies. Non-EGU Memorandum at 

5–7. For these industries and for boilers, 

looking at different groupings of states 

could result in a different 

‘‘representative’’ cost (as displayed in 

the Non-EGU Memorandum at 10 (table 

6)). 

However, any differences in the 

identified ‘‘representative’’ costs for 

these sources would not affect the 

outcome of the analysis. For each of 

these types of sources, the record shows 

that the costs associated with each of 

the different control technologies falls 

within the range of costs that the EPA 

had concluded were reasonable to 

impose. See 88 FR 36746–47. In other 

words, even if a different group of states 

produces a higher representative cost 

when weighted by those states’ 

population of sources, the results still 

fall within the upper bound of the costper-ton that the EPA found appropriate. 

The EPA’s conclusion—that the 

representative cost was reasonable— 

would be the same. 

For example, for RICE, the following 

table shows the data sources and costper-ton estimates the EPA adapted from 

the CMDB to inform its determination of 

representative cost for these sources. 

These were the figures, adjusted to 2016 

dollars, that informed the EPA’s average 

cost derived from national data sources 

used in the weighting to generate a 

representative cost figure of $4,981/ton 

for RICE. 

TABLE I—DATA SOURCES AND COST ESTIMATES FOR RICE CONTROLS

Control technology/engine type Original reference $/Ton value 

SCR, 4 Stroke Natural Gas Engines, Lean Burn 17% (of engines in 

analysis population).

2003, cost information from CARB 

2001 report.

$2,900 (2001 dollars). 

Non-Selective Catalytic Reduction or Layered Combustion, for SCCs 

where the firing technology is not specified as to Rich Burn or Lean 

Burn 36%.

2009/2000 (from 2009 ERLE study 

and 2000 Pechan Phase II NOX

SIP call report).

4,538 (2013 dollars). 

Layered Combustion, 2 Stroke Natural Gas, Lean Burn 44% ............... 2009 (ERLE study) ........................ 4,900 (2010 dollars). 

Non-Selective Catalytic Reduction, 4 Cycle Natural Gas, Rich Burn 

3%.

2000 (Pechan, Phase II NOX SIP 

call report).

422 (1999 dollars). 

Likewise, for MWCs in the Solid 

Waste Combustors and Incinerators 

industry, the EPA provided the cost 

assumptions used for the different 

control types in appendix B of the NonEGU Memorandum. 

For boilers, the EPA explained that its 

cost estimates were derived from the 

CMDB, and the EPA identified a number 

of assumptions used in developing 

representative cost figures, which the 

EPA was clear may not be reflective of 

all sources’ circumstances. Non-EGU 

Memorandum at 7. Noting that boilers 

have the highest representative costs 

among the non-EGU source types, the 

EPA explained in the Good Neighbor 

Plan that for individual sources, costs 

on a per-ton basis could well be higher 

than the estimated $14,595/ton 

representative cost, but still be 

commensurate with the range of costs 

that informed the identification of the 

most stringent control strategy selected 

in the Good Neighbor Plan for EGUs (for 

which costs at the 90th percentile ran as 

high as $20,900/ton). 88 FR 36746. 

The EPA also emphasized that costper-ton figures are only one factor in the 

Step 3 multi-factor analysis, can vary 

widely depending on the assumptions 

used, and the conclusions in the Good 

Neighbor Plan regarding appropriate 

stringency levels were informed by a 

broader review of how widely adopted 

and proven various control strategies 

had become. Id. at 36746–47. Because of 

this, the determinations in the Good 

Neighbor Plan regarding the appropriate 

level of emissions control that could be 

expected of a particular type of source 

considered not just cost-per-ton 

estimates, but analysis of which 

technologies were already in wide use 

or on which existing standards had been 

based. Good Neighbor Plan RTC at 62– 

63. Still, recognizing that individual 

sources may face circumstances of 

extreme economic hardship or 

infeasibility, the EPA also provided a 

mechanism for sources to obtain 

alternative emissions limits, among 

other mechanisms for flexibility in the 

Good Neighbor Plan, to address outlier 

cases. See 40 CFR 52.40(e). These 

provisions are adequate to cover any 

potential gap in the Good Neighbor 

Plan’s estimate of representative costs. 

Accordingly, recalculating the 

weighted average representative cost for 

these particular non-EGU sources for 

any particular state or state grouping 

would not produce a representative cost 

falling outside the acceptable range. 

Thus, any change in the weighted 

average used to derive ‘‘representative’’ 

costs for these industries and emissions 

unit types resulting from looking at 

some subset of states would not 

materially affect the analysis. 

3. Step 4 

At Step 4, the EPA establishes 

regulatory requirements to achieve the 

‘‘prohibition’’ of significant contribution 

identified at Step 3. CAA section 

110(a)(2)(D)(i). Under the Good 

Neighbor Plan, implementation of these 

requirements occurs through 

compliance activities at the source level, 

for both EGUs and for non-EGUs. 

Contrary to commenters’ allegations, 

and as explained in more detail here, in 

section III.B.3., the trading program for 

EGUs, which is a compliance flexibility, 

does not depend on an interstate trading 

region for viability. Because all of the 

obligations of the Good Neighbor Plan 

can be met by the sources in each state 

regardless of the application of the Good 

Neighbor Plan in any other state, the 

implementation framework at Step 4 is 

severable on a state-by-state basis. 

This can be seen in the structure of 

the regulations themselves. The Good 

Neighbor Plan determines on a state-bystate basis which of the EGU and the 

non-EGU emissions-control programs 

(or both) should be applied through 


khammond on DSK9W7S144PROD with RULES
99124 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

56This is identical in structure to how the EPA 

has promulgated federal good neighbor 

requirements through multiple prior rulemakings. 

See 40 CFR 52.38–39 (identifying the enrollment of 

states into emissions trading programs for ozone 

season NOX, annual NOX, and annual sulfur 

dioxide promulgated as subparts to 40 CFR part 97, 

as necessary to address good neighbor obligations 

for other ozone and particulate matter NAAQS). 

state-specific FIPs. See 40 CFR 

52.38(b)(2) (as amended by 88 FR 

36862–63) (identifying states subject to 

the Good Neighbor Plan’s ‘‘Group 3’’ 

EGU emissions trading program 

promulgated at 40 CFR part 97, subpart 

GGGGG); 40 CFR 52.40(c)(2) (as 

promulgated at 88 FR 36869) 

(identifying states subject to non-EGU 

emissions control requirements 

promulgated at id. 52.41–46). The 

regulations at 40 CFR part 97, subpart 

GGGGG and 40 CFR 52.41–46 are 

uniform in nature. But states are 

‘‘enrolled’’ via FIPs into these 

requirements based on state-specific 

findings regarding the level of their 

contribution to other states’ ozone 

problems and how long that 

contribution is projected to continue 

into the future.56

It is through the application of those 

uniform programs, as appropriate, in 

each state, via FIPs, that the Good 

Neighbor Plan eliminates each covered 

state’s significant contribution, as 

required by CAA section 

110(a)(2)(D)(i)(I). The state-specific 

coverage of the Good Neighbor Plan (for 

the 23 states for which originally 

promulgated), by regulatory program, is 

as follows: 

• EGUs in all covered states except 

California (22 States total) are required 

to participate in the Group 3 EGU 

emissions trading program at the level 

of stringency associated with near term 

emissions-control strategies that the 

EPA found can be implemented in 2023 

and 2024. 

• EGUs in Alabama, Minnesota, and 

Wisconsin are only subject to this ‘‘nearterm’’ stringency level within the Group 

3 Trading Program, and no more, 

because the EPA found these states are 

no longer linked to downwind ozone 

problems in the 2026 analytic year. 

• EGUs in 19 States (excluding the 

three states listed in the preceding 

bullet) that are covered by the Group 3 

trading program, are subject to the 

enhanced stringency in the budgets that 

takes effect over 2026 and 2027 because 

these states are linked through the 2026 

analytic year. 

• The EPA found California has no 

cost-effective fossil-fuel fired EGU 

emissions reductions available at the 

stringency levels determined in the 

Good Neighbor Plan and so is not 

subject to the Group 3 Trading Program 

at all. 

• Non-EGUs in 20 states are subject to 

the uniform emissions control 

regulations. Because the EPA found 

these requirements may take up to three 

years to be implemented (i.e., until 

2026), this number excludes Alabama, 

Minnesota, and Wisconsin, for the same 

reason as above: these states are not 

‘‘linked’’ in 2026. 

TABLE II—COVERAGE OF THE GOOD NEIGHBOR PLAN REGULATORY PROGRAMS

State 

EGU program— 

near term 

stringency 

EGU program— 

long term 

stringency 

Non-EGU 

Alabama ............................................................................................................................... X ............................ ........................

Arkansas .............................................................................................................................. X X X 

California .............................................................................................................................. ............................ ............................ X 

Illinois ................................................................................................................................... X X X 

Indiana ................................................................................................................................. X X X 

Kentucky .............................................................................................................................. X X X 

Louisiana .............................................................................................................................. X X X 

Maryland .............................................................................................................................. X X X 

Michigan ............................................................................................................................... X X X 

Minnesota ............................................................................................................................ X ............................ ........................

Mississippi ............................................................................................................................ X X X 

Missouri ................................................................................................................................ X X X 

Nevada ................................................................................................................................. X X X 

New Jersey .......................................................................................................................... X X X 

New York ............................................................................................................................. X X X 

Ohio ..................................................................................................................................... X X X 

Oklahoma ............................................................................................................................. X X X 

Pennsylvania ........................................................................................................................ X X X 

Texas ................................................................................................................................... X X X 

Utah ..................................................................................................................................... X X X 

Virginia ................................................................................................................................. X X X 

West Virginia ........................................................................................................................ X X X 

Wisconsin ............................................................................................................................. X ............................ ........................

These state groupings illustrate how 

the application of each set of regulatory 

requirements promulgated in the Good 

Neighbor Plan depends on the 

circumstances of each state, as 

determined through the analytical 

application of the 4-step interstate 

transport framework on a nationwide 

basis. No particular requirement is 

applicable in all 23 states, and the 

workability of the Good Neighbor Plan 

is not premised on an assumption that 

it must be applicable in specifically 23 

states or any particular number of states. 

As a practical matter, compliance is 

achievable through the at-the-source 

control technologies on which the EPA’s 

determination of ‘‘significant 

contribution’’ at Step 3 rested (or their 

equivalents, because the Good Neighbor 

Plan does not mandate the use of 

particular control technologies). For 

non-EGUs, all requirements are 

established at the source-specific level. 

See 88 FR 36675. The same is true of 

EGUs: the stringency of the Good 

Neighbor Plan is premised on at-thesource, conventional control 

technologies. See 88 FR 36737–39 

(tables identifying technology types). 

The EPA also designed a market-based, 

interstate emissions trading program to 

allow EGU sources to achieve their 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99125 

57Even before the Good Neighbor Plan, following 

North Carolina, the EPA took measures to ensure 

that interstate trading does not undermine the 

obligation to eliminate each state’s significant 

contribution. See North Carolina, 531 F.3d at 921, 

modified on reh’g, 550 F.3d 1176. See, e.g., CrossState Air Pollution Rule (CSAPR), 76 FR 48208, 

48268–71 (August 8, 2011); 88 FR 36752–53. 

58The size of the trading region is not the only 

determinant of liquidity; the relative magnitude of 

demand for allowances compared to supply is an 

important factor. For example, inclusion in the 

program of states with sources that are not wellcontrolled for NOX would tend to put upward 

pressure on allowance prices (and potentially 

reduce liquidity). If states with such sources are 

removed from that program (e.g., due to stays), this 

may put downward pressure on allowance prices 

(and potentially increase liquidity). 

required emissions reductions as 

efficiently and cost-effectively as 

possible, but that trading program is 

merely a more flexible means of 

implementing the source-specific 

requirements that otherwise apply 

under the Good Neighbor Plan. Indeed, 

the enhancements the EPA established 

for the Good Neighbor Plan’s trading 

program (as compared to prior good 

neighbor trading programs) were meant 

to ensure the flexibility of the trading 

program did not undermine the benefits 

of defining source-specific emissions 

controls in the first place, which helps 

assure that EGU sources in each state 

have eliminated their own significant 

contribution and thus provided 

improvements in air quality to the 

downwind receptors to which their 

home states are linked. See 88 FR at 

36657, 36684, 36752.57

Commenters may be concerned that 

without the participation of all states 

originally included in the Good 

Neighbor Plan, market liquidity will be 

affected, allowance prices will increase, 

and/or there will not be sufficient 

allowances available for compliance. 

But the record of the Good Neighbor 

Plan shows that these concerns are 

unjustified. 

While interstate trading—especially 

among sources in a large group of 

states—would generally increase the 

size of the allowance trading market and 

thus may increase market liquidity in 

ways that can improve market 

efficiency, the use of a trading program 

does not render implementation of a 

good neighbor rule in a smaller group of 

states, or even a single state, 

unreasonable. That is because, in the 

first instance, the good neighbor 

provision regulates EGU sources, not 

states. Even within a single state, there 

would be multiple participating sources 

to populate and benefit from an 

emissions trading program. Moreover, 

the history of the EPA’s good neighbor 

rulemakings shows that these trading 

programs have continued to provide 

valuable, effective compliance 

flexibility even where they cover a 

smaller group of states.58 Indeed, each 

state’s budget is set in the Good 

Neighbor Plan at levels that provide 

sufficient allowances for each state, 

assuming EGUs achieve a level of 

reduction equivalent to what can be 

achieved by the at-the-source 

technologies identified to eliminate 

significant contribution. 88 FR 36680. 

And as explained further in section 

III.C., all of the EPA’s good neighbor 

rules, including the Good Neighbor 

Plan, are designed with the 

understanding that states have the 

option to develop SIPs that remove their 

sources from a trading program, which 

necessarily changes the number of states 

subject to the FIP, and that the number 

of states covered by FIPs may otherwise 

change. 

As a consequence, the size of the 

trading regions used to implement the 

good neighbor provision has both varied 

between rules and regularly changed 

within trading programs over time. This 

has never posed a challenge to 

compliance feasibility, nor does the EPA 

have any evidence of allowance 

shortages occurring in any of these 

programs. See 88 FR 36687 (noting 

opposite problem of banked-allowance 

surpluses). For example: 

• Currently, Georgia is the only state 

whose EGUs remain in the original 

CSAPR ‘‘Group 1’’ ozone season NOX

trading program, which originally 

included 25 states. 

• In 2021, the Revised CSAPR Update 

created a 12-state trading region to 

complete the remedy to significant 

contribution for the 2008 ozone NAAQS 

(i.e., the original ‘‘Group 3’’ program). 

• With the Revised CSAPR Update in 

place, the 2016 CSAPR Update ‘‘Group 

2’’ program trading region was reduced 

from 22 states to 10 states. 

See 88 FR 36668–69 (reviewing 

regulatory history). 

In light of these successful 

implementation experiences and given 

the at-the-source technologies on which 

the Good Neighbor Plan’s EGU budgets 

are premised, coupled with other 

flexibilities, even individual-state 

trading programs would not be expected 

to unduly affect market liquidity or 

make allowances either scarce or 

unaffordable. To the extent the 

comments may be read as asserting that 

smaller trading regions would 

undermine grid reliability, the EPA 

disagrees for the same reasons. These 

comments did not present any data or 

analysis in support of that contention. 

The EPA thoroughly explained how the 

Good Neighbor Plan’s regulatory 

program for EGUs is designed to avoid 

interfering with resource adequacy and 

grid reliability, see 88 FR 36771–75. 

In short, under the Good Neighbor 

Plan, the sources in each individual 

state are fully able to comply without 

regard to what sources in other states 

are doing—and even where cooperative 

market-based mechanisms are available 

to aid in that compliance, those 

mechanisms remain sound for smaller 

state groupings or even at the 

individual-state level despite a smaller 

marketplace. 88 FR 36760–61, 36817. 

Commenters may also be concerned 

that the application of the Good 

Neighbor Plan in some upwind states if 

not operative in others may create a 

dynamic of competitive disadvantage. 

However, even if this were the case (and 

commenters supplied no evidence that 

it would be), this would not be 

sufficient justification to suspend the 

operation of the rule in states where it 

lawfully could be in effect. As an initial 

matter, because the good neighbor 

provision imposes legal obligations on 

each state individually, it does not 

allow individual states to defer 

compliance with their legal obligations 

based on circumstances in other upwind 

states. That is consistent with the 

provision’s purpose, which is intended 

to ensure equity and fairness among 

states by prohibiting harmful upwind 

state emissions that impose regulatory, 

economic, and health burdens on 

downwind states. See 88 FR 36658, 

36687, 36741; see also 64 FR 28250, 

28258–62 (May 25, 1999) (reviewing 

legislative history of the good neighbor 

provision and related statutory 

provisions, which reflects an intent to 

‘‘equalize the positions of the States 

with respect to interstate pollution by 

making a source at least as responsible 

for polluting another State as it would 

be for polluting its own State’’). The 

inaction of some upwind states is not an 

appropriate justification for further 

relaxing all upwind states’ obligations, 

when it is downwind states who will 

suffer. That burden will fall not just on 

downwind communities, but on 

industries in downwind states with 

ozone nonattainment problems, who 

will likely bear greater competitive 

disadvantages vis-a`-vis their 

competitors in upwind states whose 

pollution is contributing to the 

enhanced regulatory burdens they 

already face under the Act. See EME 

Homer City, 489 U.S. at 519; Maryland, 

958 F.3d at 1200–01, 1203–04. This 

consideration is particularly acute given 

the August 3, 2024, attainment date for 

compliance with the 2015 ozone 

NAAQS for Moderate nonattainment 


khammond on DSK9W7S144PROD with RULES
99126 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

59This is also consistent with the EPA’s 

determination that it is necessary and appropriate 

to extend the Good Neighbor Plan’s requirements to 

CAA section 301(d) FIP areas located within the 

borders of states whose sources were found to be 

significantly contributing. The EPA explained in 

the Good Neighbor Plan that not doing so would 

pose a risk that such areas would then be targeted 

for the siting of polluting facilities to avoid the 

Good Neighbor Plan’s requirements, frustrating the 

purpose of the Good Neighbor Plan and the statute. 

88 FR 36691. This concern exists at the ‘‘intraState’’ level. Second, while it is generally 

appropriate that equity and consistency should be 

maintained across all similarly situated 

jurisdictions, that does not extend to excusing one 

upwind state of its statutory obligations simply on 

the basis that the obligations of another upwind 

state are still pending or unresolved. 

60Likewise, in the Good Neighbor Plan, we 

observed a receptor projected to resolve using an 

emissions control stringency level not requiring 

non-EGU emissions controls. The Larimer County, 

Colorado, receptor’s maximum design value drops 

below 71 ppb when the highest EGU stringency is 

applied (but before non-EGU controls are applied). 

Thus, if any state were linked only to this receptor, 

the EGU-only level of stringency would have been 

the stopping point. However, all states linked to 

this receptor were also linked to other receptors for 

which application of both the EGU and non-EGU 

emissions control stringency did not produce 

overcontrol. See Ozone Policy TSD, appendix H, at 

115. 

areas located throughout the country, 

and the Good Neighbor Plan’s objective 

of further assisting downwind states in 

time for the 2027 Serious area 

attainment date. 88 FR 36690, 36695.59

In any case, in light of the unique ability 

of the power sector to shift generation 

among sources in supplying electricity 

to the power grid, the EPA conducted an 

analysis in the Good Neighbor Plan of 

the potential for power generators to 

shift production and emissions from 

EGUs in states covered by the Good 

Neighbor Plan to states not covered by 

the Good Neighbor Plan and found that 

the risk, while not zero, was relatively 

small. Good Neighbor Plan RTC at 604– 

05. Further, that risk is attendant and 

unavoidable at the boundaries of any 

multistate or regional program, 

regardless of its size and regardless of 

whether that program uses emissions 

trading or is based on source-specific 

emissions limitations, and so not 

particular to the circumstances here. 

In short, the implementation of the 

regulatory requirements of the Good 

Neighbor Plan, at Step 4, is achievable 

by the sources in each state and is 

therefore severable by state. 

C. Other Features of the Statute and 

Good Neighbor Plan Supporting 

Severability 

In light of the statutory text and 

context, the Good Neighbor Plan, like 

prior interstate transport rules, is 

designed to be modular—i.e., to apply 

on a state-by-state basis and to 

whichever states are presently subject to 

the EPA’s responsibility to issue a FIP. 

That the Good Neighbor Plan functions 

to appropriately define and prohibit 

significant contribution on a state-bystate basis, regardless of the number of 

states covered, can be seen in a number 

of other features and elements of the 

Good Neighbor Plan and by reviewing 

the history of implementation of the 

good neighbor provision for ozone 

across prior rulemakings and case law. 

First, as directed by the statute and 

relevant precedent, the EPA must define 

significant contribution in such a way 

that sources in ‘‘each State’’ are held 

responsible for the elimination of their 

own significant contribution. CAA 

section 110(a)(2)(D); see 88 FR 36687– 

88, 36762. The D.C. Circuit’s review of 

a good neighbor rule invalidated in 

North Carolina v. EPA, and the EPA’s 

subsequent action to address a specific 

holding in North Carolina concerning 

regional- versus state-level compliance, 

helpfully illustrates why, and how, the 

EPA’s current approach avoids any 

inter-dependency among states’ 

obligations. 

In an earlier good neighbor rule, the 

Clean Air Interstate Rule (CAIR), the 

EPA quantified emissions reduction 

requirements at the regional level based 

on a regional analysis, and then 

apportioned the responsibility for 

reducing each pollutant among the 

contributing states based on either the 

total allowance allocations for the states’ 

EGUs under the Acid Rain Program 

(ARP) (in the case of required sulfur 

dioxide reductions) or the total 

historical heat input amounts for the 

states’ EGUs, adjusted for the types of 

fuels used (in the case of required NOX

reductions). See 70 FR 25162, 25176 

(May 12, 2005); see also 88 FR 36668. 

In North Carolina, the D.C. Circuit 

found that CAIR had unlawfully defined 

‘‘significant contribution’’ at a regional 

level rather than on a state-specific 

basis. 531 F.3d at 906–08, 919–21. After 

this ruling, the EPA took care to ensure 

the successor rule to CAIR, CSAPR, 

defined and prohibited significant 

contribution for each State. See 76 FR 

48271. It did this by evaluating and 

selecting appropriate uniform levels of 

control stringency for the set of upwind 

states linked to identified downwind 

receptors and then quantifying and 

implementing the required emissions 

reductions resulting from the selected 

control stringencies independently for 

each upwind state. See id. In other 

words, at this point in the analysis, the 

EPA removed from CSAPR (and all 

subsequent good neighbor rules) the 

interdependency of a regional solution 

that North Carolina had found in CAIR, 

as this interdependency resulted in a 

failure to identify each state’s own 

obligations. In CSAPR, each receptor 

and the states linked to that receptor 

were evaluated independently, which 

led the EPA to establish different 

regional groupings of states with 

different levels of emissions control 

stringency (e.g., in that case, the Group 

1 and Group 2 SO2 control programs). 

See 76 FR 48252. The courts reviewing 

CSAPR in EME Homer City further 

required that the EPA evaluate each 

state to ensure an otherwise permissible 

uniform emissions control stringency 

does not overcontrol the emissions of 

any particular upwind state. 572 U.S. 

489, 521. Taken together, these 

refinements from CAIR opened up the 

potential that individual states could be 

assigned different cost/stringency levels 

based on whether their receptors (or 

their linkages to those receptors) would 

fully resolve at different cost/stringency 

levels or would fully resolve before 

additional emissions control measures 

could be implemented. This statespecific treatment can be seen in the 

Good Neighbor Plan’s recognition that 

control strategies only available by the 

2026 analytic year are not required in 

Alabama, Minnesota, or Wisconsin, 

given that their specific linkages were 

projected to resolve by that year. For the 

remaining 20 states in the Good 

Neighbor Plan, no overcontrol was 

observed in the 2026 analytic year and 

so no adjustments in the program’s 

stringency were needed. 88 FR 36749.60

At Step 4, CSAPR maintained an 

interstate EGU trading program, but the 

EPA took steps to ensure that this too 

complied with North Carolina and the 

statutory obligation to define and 

prohibit each state’s significant 

contribution. To ensure that each state 

would eliminate its own significant 

contribution within the flexible 

compliance mechanism of an interstate 

trading program for EGUs, the EPA 

imposed a constraint on interstate 

trading within the trading program, 

through ‘‘assurance provisions’’ that 

imposed a 3-to-1 allowance-surrender 

ratio for emissions in excess of a certain 

percentage of each state’s budget. As 

explained in the Good Neighbor Plan, 

‘‘The establishment [in CSAPR] of 

assurance levels with associated extra 

allowance surrender requirements was 

intended to respond to the D.C. Circuit’s 

holding in North Carolina requiring the 

EPA to ensure within the context of an 

interstate trading program that sources 

in each State are required to address 

their good neighbor obligations within 

the State and may not simply shift those 

obligations to other States by failing to 

reduce their own emissions and instead 

surrendering surplus allowances 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99127 

61For example, by strengthening incentives for 

individual units to optimize operation of their 

emissions controls, the backstop daily NOX

emissions rate provisions and the secondary 

emissions limitation provisions also both increase 

assurance that each State’s significant contribution 

will be eliminated within that State. See, e.g., 88 FR 

36767–68 and 36799–800. 

62See supra note 19. 

63The D.C. Circuit has in fact emphasized that the 

important public health benefits of the EPA’s 

interstate transport rules, as well as the potential 

disruption to emissions trading markets, counsel 

against vacatur even when some aspect of the rules 

may be found unlawful or necessitate re-analysis. 

See North Carolina, 550 F.3d 1176, 1178 (D.C. Cir. 

2008); Wisconsin, 938 F.3d at 336–37; EME Homer 

City, 795 F.3d at 132. 

64To the extent any discussions in the Good 

Neighbor Plan’s preamble or its technical support 

documents suggested that some particular 

substantive component of the methodology was 

dependent on a specific 23-state coverage, the 

Agency clarifies here that such statements were 

inartful or incorrect. For example, the Agency has 

reviewed the methodology underlying the graphs 

displayed in appendix I of the Ozone Policy TSD. 

We have confirmed that despite headings 

describing the graphs as being for 22 or for 19 

states, respectively, in fact Figures 1 and 2 were 

compiled using the ‘‘Step 3 Configuration’’ in 

AQAT that compiled the reductions of all linked 

states and the home state for each receptor. Figure 

3 likewise reflected a compilation of data that was 

not limited to the states subject to the original Good 

Neighbor Plan. The references to 22 and 19 states 

(for 2023 and 2026 EGU stringency, respectively) 

were simply intended to indicate the number of 

states in the Good Neighbor Plan for which the data 

informed obligations being finalized in that rule. 

See 88 FR 36744–45 (explaining that Figures 1 and 

2 reflected the AQAT data used to inform the Step 

3 determinations concerning EGUs, while Figure 3 

was intended to illustrate why further EGU 

emissions-reduction strategies not included in that 

analysis appeared to be well beyond a notable 

breakpoint in cost-effectiveness and thus not worth 

pursuing in the context of defining good neighbor 

obligations for the 2015 ozone NAAQS). 

purchased from sources in other States.’’ 

88 FR 36786. 

The features of CSAPR included to 

address the North Carolina decision 

have been retained in the Good 

Neighbor Plan and enhanced to further 

ensure that each state remains 

responsible for elimination of its own 

significant contribution.61 See id. at 

36687–88, 36762 (citing North Carolina, 

at 906–08, 921; see also Good Neighbor 

Plan RTC at 42 (‘‘[T]he D.C. Circuit has 

held that the EPA may not implement 

an emissions reduction program under 

the good neighbor provision that fails to 

ensure that each State has eliminated its 

own significant contribution. North 

Carolina, 531 F.3d at 921.’’); id. at 48 

(same). 

Second, also consistent with the stateby-state structure of CAA section 110, as 

recognized in North Carolina, the EPA 

made specific findings regarding its 

authority to promulgate a FIP for each 

individual state covered by the Good 

Neighbor Plan. 88 FR 36689 n.109. 

Notably, the EPA had originally 

proposed that the Good Neighbor Plan 

rulemaking would promulgate FIPs for 

26 states, not 23. See 87 FR 20036, 

20038 (April 6, 2022). The modeling 

that informed the final rule indicated 

that Delaware and Wyoming were not 

linked to any out-of-state receptors, and 

that Tennessee would only be linked to 

a new class of ‘‘violating monitor’’ 

receptors. Thus, these three states were 

excluded from the final Good Neighbor 

Plan. Including fewer states in the final 

rule than were included in the proposal 

did not alter the approach to defining 

each remaining states’ significant 

contribution, nor cause any change in 

each covered state’s obligations or the 

requirements imposed on emitting 

sources in those covered states. The 

final modeling also indicated that 

several additional states were 

potentially linked and may ‘‘contribute 

significantly,’’ and thus the EPA 

acknowledged in the final Good 

Neighbor Plan that these states’ 

obligations still needed to be addressed. 

See 88 FR 36658 (identifying Arizona, 

Iowa, Kansas, New Mexico, Tennessee, 

and Wyoming as needing to be further 

addressed in a subsequent action).62

Critically, under the EPA’s analytical 

approach to the Good Neighbor Plan, 

the absence of these states from the final 

Good Neighbor Plan did not, in the 

Agency’s view at the time, pose any 

challenge to finalizing and moving 

forward with implementing the Good 

Neighbor Plan for the states included. 

Third, the Good Neighbor Plan, 

consistent with the statute and like all 

prior good neighbor federal 

rulemakings, recognizes that states may 

choose to replace their FIP with a SIP. 

See, e.g., 88 FR 36838–42 (discussing in 

detail various options states have for 

developing SIPs). When the EPA 

approves a replacement SIP, that state is 

withdrawn from the FIP, thus changing 

the number of states subject to Good 

Neighbor Plan FIPs. In developing SIPs, 

states may opt to leave the interstate 

trading program for EGUs in favor of an 

adequate, alternative approach to 

addressing their good neighbor 

obligations. Id. at 36841–42. This echoes 

nearly identical discussions included in 

prior good neighbor rules, see, e.g., 

CSAPR, 76 FR 48328. Both the proposed 

and final Good Neighbor Plan contained 

an extended discussion of how states 

could exit the Good Neighbor Plan 

through several options for submitting 

approvable SIPs. 87 FR 20149–51; see 

also id. at 20040 (‘‘[T]his proposal will 

provide States with as much 

information as the EPA can supply at 

this time to support their ability to 

submit SIP revisions to achieve the 

emissions reductions the EPA believes 

necessary to eliminate significant 

contribution.’’). In the final Good 

Neighbor Plan, the EPA explained that 

it encouraged states to replace their FIP 

with an approvable SIP, specifically 

identifying that states could choose to 

exit the trading program, regulate 

different sources, or devise adequate 

alternative methodologies to defining 

‘‘significant contribution.’’ See 88 FR 

36839. 

Fourth, the EPA’s experience with 

prior good neighbor rules informs its 

determinations concerning the ability of 

the Good Neighbor Plan to function 

sensibly regardless of the number of 

states included. The EPA has removed 

states from coverage of prior good 

neighbor rules (including from interstate 

trading programs) in the past without 

any loss of program viability. See 88 FR 

36669. In addition, at times the EPA has 

been required to remove specific states 

from a good neighbor program as a 

result of adverse court decisions. For 

example, CSAPR was remanded as to 

multiple states based on overcontrol 

concerns in the aftermath of the 

Supreme Court’s decision in EME 

Homer City, but the D.C. Circuit 

expressly declined to vacate CSAPR, 

even as to those states. See EME Homer 

City Generation, LP v. EPA, 795 F.3d 

118, 132 (D.C. Cir. 2015). Subsequent 

rulemakings moved several states out of 

the original CSAPR programs, without 

any issues concerning the feasibility or 

propriety of the remaining states’ 

obligations. See, e.g., 81 FR 74504, 

74506–07 (October 26, 2016); see also 

86 FR 23056–57. Similarly, in Michigan, 

213 F.3d at 695, the D.C. Circuit vacated 

the NOX SIP Call as to Wisconsin, 

Missouri, and Georgia, but left the rule 

in place and remanded without vacatur 

as to certain issues as to other states.63

The modular nature of past good 

neighbor rules has functioned well and 

ensured that when the scope of a rule 

might change based on issues specific to 

particular states, the rule can continue 

to function properly for the states that 

remain covered by the rule. 

Finally, there are no statements in the 

record of the Good Neighbor Plan that 

suggest the EPA considered the Good 

Neighbor Plan interdependent among 

states or dependent on exactly 23 states 

or any other minimum number of states’ 

participation.64 To the contrary, the 

severability section in the Good 

Neighbor Plan preamble indicated the 

Agency’s expectation that the Good 

Neighbor Plan could be implemented in 

individual states as necessary. 88 FR 

36693. While in one instance, the Good 

Neighbor Plan did refer to the 

‘‘interdependent nature of interstate 


khammond on DSK9W7S144PROD with RULES
99128 Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 

pollution transport,’’ see 88 FR 36860, 

this was in reference to the nature of the 

pollution problem, not the nature of the 

EPA’s solution. While the variable, 

interstate nature of ozone transport 

certainly presents a ‘‘thorny causation 

problem,’’ EME Homer City, 489 U.S. at 

514, the EPA’s solution to that problem 

when promulgating FIPs, through a 

consistent application of the 4-step 

interstate transport framework to each 

state, is expressly designed to avoid the 

creation of unworkable 

interdependencies. 

By contrast, commenters’ apparent 

view that the analysis underlying the 

Good Neighbor Plan would change 

depending on its scope of coverage at 

any given moment misapprehends how 

the Good Neighbor Plan is designed and 

operates. If commenters were correct 

that the EPA had designed a good 

neighbor rule that was contingent for 

any particular state on whether the rule 

covered other states, this would 

seemingly introduce an 

interdependency problem and render 

the rule invalid under North Carolina. It 

could also require that the EPA revise a 

good neighbor rule every time a state 

opted to impose a SIP to exit its FIP or 

was moved into a new FIP for a revised 

NAAQS or to fully address its 

obligations. The practical problems of 

such an approach reinforce why this 

would be an unreasonable way to define 

states’ obligations. It would render good 

neighbor obligations an ever-shifting 

target, undermining regulatory certainty 

for sources and states. The Good 

Neighbor Plan is designed to avoid such 

complications. 

D. Whether Judicial Stays Would Justify 

Re-Analysis of the Good Neighbor Plan 

The comments discussed in section 

II.B. may be interpreted to argue that the 

Good Neighbor Plan must be reanalyzed where a court stays, as to a 

particular state or states, either the rule 

itself or an antecedent action such as the 

SIP Disapproval that is a predicate to 

the exercise of FIP authority under CAA 

section 110(c)(1). Courts may enter 

temporary stays of agency actions 

pending judicial review to preserve the 

status quo. A stay order is not a final 

judgment and in itself does not alter or 

force a change in the substantive 

analysis an agency has applied in taking 

the action under review. Thus, stay 

orders would not alter the analysis of 

good neighbor obligations for the 2015 

ozone NAAQS for any particular state, 

and the EPA would come to the same 

result as was already reached, because 

the analytical underpinnings and the 

implementation of the Good Neighbor 

Plan do not depend on the specific 

number of states that it covers. 

The comments may also be 

interpreted as an assertion that the Good 

Neighbor Plan would not function or 

would be unreasonable because stays 

may be put in place, or because a large 

amount of the emissions reductions that 

the Good Neighbor Plan calls for would 

become unenforceable pending judicial 

review. However, this does not serve to 

identify what technical and analytical 

conclusions the Agency reached 

through its notice-and-comment 

rulemaking were flawed or must be 

changed. The obligations as defined for 

each state remain promulgated even if 

they are stayed pending judicial review. 

Similarly, the effects of merits 

holdings in the SIP Disapproval 

litigation or a vacatur of the SIP 

Disapproval as to a particular state 

would not necessarily require a change 

in the way the EPA may lawfully define 

that state’s good neighbor obligations in 

a FIP, much less those of other states. To 

be sure, in general a vacatur of a SIP 

disapproval would at a minimum 

require that the FIP remain stayed as to 

that state, pending action on remand (if 

that disapproval had been the only basis 

for the exercise of FIP authority). And 

the EPA will always comply with the 

final judgments of the courts. However, 

the degree to which a change in analysis 

for a particular state, with respect to the 

EPA’s action on its SIP submission, 

would be required following any merits 

holdings in the various cases 

challenging the SIP Disapproval would 

depend on the nature of those holdings, 

as to that state, which is speculative at 

this time. Whether such holdings would 

in turn require a change in the EPA’s 

analysis or outcomes concerning other 

states’ SIP submissions is still more 

speculative, and whether any such 

changes could then separately impact 

the EPA’s approach to defining the 

obligations of the state in question 

through a FIP, much less the obligations 

of other states via FIPs, is more 

speculative still. 

Several commenters urge that the EPA 

must simply accept their view, or the 

view of commenters on the SIP 

Disapproval, that either or both of the 

rules are legally or procedurally flawed 

and will not survive judicial review. 

The EPA has addressed the substantive 

arguments raised in such comments 

elsewhere in the record of the Good 

Neighbor Plan, or it has indicated that 

it had addressed those issues in the SIP 

Disapproval and those matters are not 

within scope of the rule. See Good 

Neighbor Plan RTC at 6–8, 149–51, 155; 

see also section II.B. supra 

(summarizing responses to comments in 

the original Good Neighbor Plan record). 

Where the Agency has reviewed such 

comments and is satisfied that it is 

acting lawfully, mere speculation that a 

reviewing court may disagree cannot 

supply a reasoned basis for the Agency 

to stay, modify, or withdraw its rule. 

Thus, the methodology and regulatory 

programs of the Good Neighbor Plan are 

reasonably designed and operate to 

define the obligations of each state, in 

a manner that is severable on a state-bystate basis. While the analytical 

methods, technical analyses, and policy 

judgments that informed the Good 

Neighbor Plan were developed and 

conducted consistently across the 

nation, they ultimately produced a 

determination of significant 

contribution at the state level. The 

implementation of the measures 

necessary to eliminate significant 

contribution is achievable by the 

sources within each state, irrespective of 

other states’ participation. It would not 

matter if there were one state or 50 

states in the Good Neighbor Plan—the 

methodology and the result for any 

particular state—i.e., the definition of 

‘‘significant contribution to 

nonattainment and interference with 

maintenance’’ under CAA section 

110(a)(2)(D)(i)(I) for the 2015 ozone 

NAAQS—would remain the same. 

The EPA acknowledges that although 

the substantive circumstances of the 

states remain constant, the 

circumstances of the rulemaking and 

litigation are likely to remain in flux in 

the short-to-near term. Courts that may 

grant stays pending judicial review may 

later affirm the SIP Disapproval or may 

remand the SIP Disapproval as to 

particular states, with or without 

vacatur. Indeed, both the NOX SIP Call 

and CSAPR were ultimately 

implemented despite initial stay orders, 

and notwithstanding that some elements 

of each rule were remanded without 

vacatur. See, e.g., EME Homer City, 795 

F.3d at 138; Michigan, 213 F.3d at 695. 

Should there be any remand of the SIP 

Disapproval, the EPA will have to act on 

that state’s SIP submission again, in 

accordance with the court’s holdings. 

See Calcutt v. Federal Deposit Ins. 

Corp., 598 U.S. 623, 629 (2023). And, at 

any point, any state may submit a new 

SIP to the EPA, and the EPA will review 

that SIP. Ultimately, under the statute, 

every state will need to be covered by 

either an approved SIP or a FIP that 

meets the requirements of the good 

neighbor provision—with the number 

subject to each potentially changing at 

any point. 

Finally, the EPA’s conclusion that the 

Good Neighbor Plan is severable also 

reflected the important public health 


khammond on DSK9W7S144PROD with RULES
Federal Register / Vol. 89, No. 237 / Tuesday, December 10, 2024 / Rules and Regulations 99129 

and environmental benefits of the rule 

in eliminating significant contribution 

and to ensure to the greatest extent 

possible the ability of both upwind 

states and downwind states and other 

relevant stakeholders to be able to rely 

on the rule in their planning. 88 FR 

36693. Cf. Wisconsin, 938 F.3d at 336– 

37 (‘‘As a general rule, we do not vacate 

regulations when doing so would risk 

significant harm to the public health or 

the environment.’’); North Carolina v. 

EPA, 550 F.3d 1176, 1178 (D.C. Cir. 

2008) (noting the need to preserve 

public health benefits). 

IV. Statutory and Executive Orders 

Reviews 

The EPA’s determinations under the 

relevant statutory and Executive Order 

reviews for the Good Neighbor Plan can 

be found at 88 FR 36856–60. This 

document provides further explanation 

in response to comments concerning a 

particular aspect of the Good Neighbor 

Plan and does not alter or amend any of 

the requirements of the rule. Additional 

information about the relevant statutes 

and Executive Orders can be found at 

https://www.epa.gov/laws-regulations/ 

laws-and-executive-orders. 

A. Executive Order 12866: Regulatory 

Planning and Review and Executive 

Order 14094: Modernizing Regulatory 

Review 

The Office of Management and Budget 

(OMB) has determined that this 

document is significant for purposes of 

review under Executive Order 12866, as 

amended by Executive Order 14094. 

Accordingly, the EPA submitted this 

document to the OMB for Executive 

Order 12866 review. Documentation of 

any changes made in response to the 

Executive Order 12866 review is 

available in the docket. 

B. Judicial Review 

Judicial review of the Good Neighbor 

Plan is in the United States Court of 

Appeals for the District of Columbia 

Circuit for the reasons stated in the final 

rulemaking document. See 88 FR 

36859–60. Petitions for review of the 

Good Neighbor Plan are currently 

pending in that court, and this 

document completes proceedings on 

remand of the record as ordered by that 

court. State of Utah et al. v. EPA, No. 

23–1157 (D.C. Cir. September 12, 2024). 

The D.C. Circuit retains jurisdiction 

over the case. 

Michael S. Regan, 

Administrator. 

[FR Doc. 2024–28739 Filed 12–9–24; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[Docket No. FWS–HQ–ES–2023–0067; 

FXES1111090FEDR–256–FF09E21000] 

RIN 1018–BG69 

Endangered and Threatened Wildlife 

and Plants; Endangered Species 

Status for the Fluminense Swallowtail 

Butterfly, Harris’ Mimic Swallowtail 

Butterfly, and Hahnel’s Amazonian 

Swallowtail Butterfly 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Final rule. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), determine 

endangered species status under the 

Endangered Species Act of 1973 (Act), 

as amended, for three butterflies 

endemic to Brazil: the Fluminense 

swallowtail (Parides ascanius), Harris’ 

mimic swallowtail (Eurytides 

(=Mimoides) lysithous harrisianus), and 

Hahnel’s Amazonian swallowtail 

(Parides hahneli). This rule extends the 

Act’s protections to these species. 

DATES: This rule is effective January 9, 

2025. 

ADDRESSES: This final rule, comments 

and materials we received on the 

proposed rule, and supporting materials 

that we used in preparing this rule, such 

as the species status assessment report, 

are available at https://

www.regulations.gov at Docket No. 

FWS–HQ–ES–2023–0067. 

FOR FURTHER INFORMATION CONTACT: 

Rachel London, Manager, Branch of 

Delisting and Foreign Species, 

Ecological Services Program, U.S. Fish 

and Wildlife Service, MS: ES, 5275 

Leesburg Pike, Falls Church, VA 22041– 

3803; telephone 703–358–2171. 

Individuals in the United States who are 

deaf, deafblind, hard of hearing, or have 

a speech disability may dial 711 (TTY, 

TDD, or TeleBraille) to access 

telecommunications relay services. 

Individuals outside the United States 

should use the relay services offered 

within their country to make 

international calls to the point-ofcontact in the United States. 

SUPPLEMENTARY INFORMATION: 

Previous Federal Actions 

Please refer to the proposed listing 

rule (88 FR 48414, July 27, 2023) for the 

Fluminense swallowtail butterfly, 

Harris’ mimic swallowtail butterfly, and 

Hahnel’s Amazonian swallowtail 

butterfly for a detailed description of 

previous Federal actions concerning 

these species. Hereafter in this 

document, we will abbreviate their 

common names by removing the word 

‘‘butterfly’’ and referring to these 

species as ‘‘swallowtails.’’ 

Peer Review 

A species status assessment (SSA) 

team prepared an SSA report for the 

Fluminense swallowtail, Harris’ mimic 

swallowtail, and Hahnel’s Amazonian 

swallowtail. The SSA team was 

composed of Service biologists, in 

consultation with other species experts. 

The SSA report represents a 

compilation of the best scientific and 

commercial data available concerning 

the status of the species, including the 

impacts of past, present, and future 

factors (both negative and beneficial) 

affecting the species. 

In accordance with our joint policy on 

peer review published in the Federal 

Register on July 1, 1994 (59 FR 34270), 

and our August 22, 2016, memorandum 

updating and clarifying the role of peer 

review in listing actions under the Act, 

we solicited independent scientific 

review of the information contained in 

the Fluminense swallowtail, Harris’ 

mimic swallowtail, and Hahnel’s 

Amazonian swallowtail SSA report. As 

discussed in the proposed rule, we sent 

the SSA report to seven independent 

peer reviewers and received four 

responses. The peer reviews can be 

found at https://www.regulations.gov. In 

preparing the proposed rule, we 

incorporated the results of these 

reviews, as appropriate, into the SSA 

report, which was the foundation for the 

proposed rule and this final rule. A 

summary of the peer review comments 

and our responses can be found in the 

proposed rule (88 FR 48414). 

Summary of Changes From the 

Proposed Rule 

In preparing this final rule, we 

reviewed and fully considered all public 

comments received during the comment 

period, and we make no substantive 

changes from the July 27, 2023, 

proposed rule (88 FR 48414). We 

considered all relevant references 

provided by commenters in our final 

determination and incorporated them 

into this final rule (see Habitat Loss and 

Degradation and Capture, below). 

Summary of Comments and 

Recommendations 

In the proposed rule published on 

July 27, 2023 (88 FR 48414), we 

requested that all interested parties 

submit written comments on the 

proposal by September 25, 2023. We 

also contacted appropriate Federal 


khammond on DSK9W7S144PROD with RULES