80480 Federal Register / Vol. 88, No. 221 / Friday, November 17, 2023 / Rules and Regulations 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 60 

[EPA–HQ–OAR–2021–0527; FRL–8606–01– 

OAR] 

RIN 2060–AV48 

Adoption and Submittal of State Plans 

for Designated Facilities: Implementing 

Regulations Under Clean Air Act 

Section 111(d) 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is finalizing amendments 

to the regulations that govern the 

processes and timelines for state and 

Federal plans to implement emission 

guidelines under Clean Air Act (CAA) 

New Source Performance Standards for 

existing sources (the ‘‘implementing 

regulations’’). The amendments include 

revisions to the timing requirements for 

state and the EPA actions related to 

plans; the addition of mechanisms to 

improve flexibility and efficiency in 

plan processes; and new requirements 

for demonstration of timely meaningful 

engagement with pertinent 

stakeholders—including, but not limited 

to, industry, small businesses, and 

communities most affected by and 

vulnerable to the impacts of the plan. 

This action additionally provides a 

process for states’ consideration of 

‘remaining useful life and other factors’ 

(RULOF) in applying a standard of 

performance; amends the definition of 

standard of performance in the 

implementing regulations; and clarifies 

compliance flexibilities that states may 

choose to incorporate into state plans, 

including trading or averaging. Finally, 

this action adds requirements for the 

electronic submission of state plans and 

provides several other clarifications and 

minor revisions to the implementing 

regulations. 

DATES: This final rule is effective on 

December 18, 2023. 

ADDRESSES: The EPA has established a 

docket for this action under Docket ID 

No. EPA–HQ–OAR–2021–0527. All 

documents in the docket are listed on 

the https://www.regulations.gov/ 

website. Although listed, 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: For 

questions about this action contact Dr. 

Michelle Bergin, Sector Policies and 

Programs Division (Mail Code D205– 

01), Office of Air Quality Planning and 

Standards, U.S. Environmental 

Protection Agency, 109 T.W. Alexander 

Drive, P.O. Box 12055, Research 

Triangle Park, North Carolina 27711; 

telephone number: (919) 541–2726; 

email address: bergin.michelle@epa.gov. 

SUPPLEMENTARY INFORMATION: Preamble 

acronyms and abbreviations. We use 

multiple acronyms and terms in this 

preamble. While this list may not be 

exhaustive, to ease the reading of this 

preamble and for reference purposes, 

the EPA defines the following terms and 

acronyms here: 

ACE Affordable Clean Energy Rule 

ALA American Lung Association 

BSER Best System of Emission Reduction 

CAA Clean Air Act 

CBI confidential business information 

CDX Central Data Exchange 

CFR Code of Federal Regulations 

EG Emission Guideline 

EGU electric generating unit 

EJ environmental justice 

EPA Environmental Protection Agency 

FIP Federal Implementation Plan 

ICR Information Collection Request 

IoP Increments of Progress 

NAAQS National Ambient Air Quality 

Standards 

OAQPS Office of Air Quality Planning and 

Standards 

OMB Office of Management and Budget 

PRA Paperwork Reduction Act 

PM2.5 fine particulate matter (2.5 microns 

and less) 

RTC Response to Comments document 

RFA Regulatory Flexibility Act 

RIN Regulatory Information Number 

RULOF remaining useful life and other 

factors 

SIP State Implementation Plan 

SpeCS State Planning Electronic 

Collaboration System 

TAR Tribal Authority Rule 

TAS Treatment as a State 

TIP Tribal Implementation Plan 

UMRA Unfunded Mandates Reform Act 

U.S.C. United States Code 

Organization of this document. The 

information in this preamble is 

organized as follows: 

I. General Information 

A. Does this action apply to me? 

B. Where can I get a copy of this document 

and other related information? 

C. Judicial Review and Administrative 

Review 

II. Background 

A. What is the statutory authority for this 

action? 

B. What is the background for this action? 

C. What changes did we propose? 

D. What outreach and engagement did the 

EPA conduct? 

III. What actions are we finalizing and what 

is our rationale for such decisions? 

A. Revised Implementing Timelines 

B. Federal Plan Authority and Timeline 

Upon Failure to Submit a Plan 

C. Outreach and Meaningful Engagement 

D. Regulatory Mechanisms for State Plan 

Implementation 

E. Remaining Useful Life and Other Factors 

(RULOF) Provisions 

F. Provision for Electronic Submission of 

State Plans 

G. Other Proposed Modifications and 

Clarifications 

IV. Summary of Cost, Environmental, and 

Economic Impacts 

V. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review; Executive Order 

13563: Improving Regulation and 

Regulatory Review; and Executive Order 

14094: Modernizing Regulatory Review 

B. Paperwork Reduction Act (PRA) 

C. Regulatory Flexibility Act (RFA) 

D. Unfunded Mandates Reform Act 

(UMRA) 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and 

Advancement Act (NTTAA) 

J. Executive Order 12898: Federal Actions 

To Address Environmental Justice in 

Minority Populations and Low-Income 

Populations 

K. Congressional Review Act (CRA) 

I. General Information 

A. Does this action apply to me? 

This action applies for the 

development and adoption of plans for 

implementation of CAA section 111(d) 

final emission guidelines (EGs) 

published in the Federal Register after 

July 8, 2019. In particular, this action 

applies to states in the development and 

submittal of state plans and to the EPA 

in processing state plan submissions 

and to the EPA in promulgating Federal 

plans. After the EPA promulgates a final 

EG, each state that has one or more 

designated facilities must develop, 

adopt, and submit to the EPA a state 

plan under CAA section 111(d). The 

term ‘‘designated facility’’ means ‘‘any 

existing facility . . . which emits a 

designated pollutant and which would 

be subject to a standard of performance 

for that pollutant if the existing facility 

were an affected facility [i.e., a new 

source].’’ See 40 CFR 60.21a(b). If a state 

fails to submit a plan or if the EPA 

determines that a state plan is not 


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1See the EPA website, https://www.epa.gov/ 

tribal/tribes-approved-treatment-state-tas, for 

information on those tribes that have treatment as 

a state for specific environmental regulatory 

programs, administrative functions, and grant 

programs. 

2Sierra Club v. EPA, 47 F.4th 738, 745 (D.C. Cir. 

2022) (‘‘EPA’s decision whether to make and 

publish a finding of nationwide scope or effect is 

committed to the agency’s discretion and thus is 

unreviewable’’); Texas v. EPA, 983 F.3d 826, 834– 

35 (5th Cir. 2020). 

3See, e.g., Nat’l Waste & Recyling Ass’n v. EPA, 

No. 16–1371 (D.C. Cir. 2016) (consolidated 

challenges to the CAA section 111(d) emissions 

guidelines for municipal solid waste landfills in the 

D.C. Circuit); Am. Lung Ass’n v. EPA, 985 F.3d 914 

(D.C. Cir. 2021) (consolidated challenges to, among 

other things, the CAA section 111(d) emission 

guidelines for fossil fuel-fired electric generating 

units known as the Affordable Clean Energy Rule). 

4 In deciding whether to invoke the exception by 

making and publishing a finding that an action is 

based on a determination of nationwide scope or 

effect, the Administrator takes into account a 

number of policy considerations, including his 

judgment balancing the benefit of obtaining the D.C. 

Circuit’s authoritative centralized review versus 

allowing development of the issue in other contexts 

and the best use of agency resources. 

satisfactory, the EPA has the authority 

to establish a Federal CAA section 

111(d) plan for designated facilities 

located in the state. 

Under the Tribal Authority Rule 

(TAR), eligible tribes may seek approval 

to implement a plan under CAA section 

111(d) in a manner similar to a state. 

See 40 CFR part 49, subpart A. Tribes 

may, but are not required to, seek 

approval for treatment in a manner 

similar to a state (treatment as a state; 

TAS) for purposes of developing a 

Tribal Implementation Plan (TIP) 

implementing an EG. If a tribe obtains 

approval and submits a TIP, the EPA 

will use similar timelines and criteria 

and will follow similar procedures as 

those for state plans. Tribes that choose 

to develop plans will have the same 

flexibilities available to states in this 

process. The TAR authorizes tribes to 

develop and implement one or more of 

its own air quality programs, or portions 

thereof, under the CAA; however, it 

does not require tribes to develop a CAA 

program. Tribes may implement 

programs that are most relevant to their 

air quality needs. A tribe with an 

approved TAS under TAR for CAA 

111(d) is not required to resubmit TAS 

approval to implement an EG subject to 

subpart Ba.1 If a tribe does not seek and 

obtain the authority from the EPA to 

establish a TIP, the EPA has the 

authority to establish a Federal CAA 

section 111(d) plan for designated 

facilities that are located in areas of 

Indian country. A Federal plan would 

apply to all designated facilities located 

in the areas of Indian country covered 

by the Federal plan unless and until the 

EPA approves a TIP applicable to those 

facilities. 

B. Where can I get a copy of this 

document and other related 

information? 

In addition to being available in the 

docket, an electronic copy of this action 

is available on the internet. Following 

signature by the EPA Administrator, the 

EPA will post a copy of this final action 

at https://www.epa.gov/stationarysources-air-pollution/adoption-andsubmittal-state-plans-designatedfacilities-40-cfr. Following publication 

in the Federal Register, the EPA will 

post the Federal Register version of the 

final rule, a memorandum showing the 

rule edits finalized in this action, and 

key supporting documents at this same 

website. 

C. Judicial Review and Administrative 

Review 

Section 307(b)(1) of the CAA governs 

judicial review of final actions by the 

EPA. This section provides, in part, that 

petitions for review must be filed in the 

D.C. Circuit: (i) when the agency action 

consists of ‘‘nationally applicable 

regulations promulgated, or final actions 

taken, by the Administrator,’’ or (ii) 

when such action is locally or regionally 

applicable, but ‘‘such action is based on 

a determination of nationwide scope or 

effect and if in taking such action the 

Administrator finds and publishes that 

such action is based on such a 

determination.’’ For locally or regionally 

applicable final actions, the CAA 

reserves to the EPA complete discretion 

whether to invoke the exception in (ii) 

described in the preceding sentence.2

This action is ‘‘nationally applicable’’ 

within the meaning of CAA section 

307(b)(1). The final rule governs the 

EPA’s promulgation of emission 

guidelines under CAA section 111(d), 

which are nationally applicable 

regulations for which judicial review is 

available only in the U.S. Court of 

Appeals for the District of Columbia 

(D.C. Circuit) pursuant to CAA section 

307(b)(1).3 Moreover, it revises the 

generally applicable, nationally 

consistent implementing regulations 

that govern the development and 

submission for all states of state plans 

and the EPA’s development of Federal 

plans pursuant to EGs under CAA 

section 111(d), as well as the EPA’s 

review of states’ plans. 

In the alternative, to the extent a court 

finds this final action to be locally or 

regionally applicable, the Administrator 

is exercising the complete discretion 

afforded to him under the CAA to make 

and publish a finding that this action is 

based on a determination of 

‘‘nationwide scope or effect’’ within the 

meaning of CAA section 307(b)(1).4 As 

explained above, this final action is 

revising a single set of nationally 

consistent implementing regulations 

that apply to every state that must 

develop a state plan submission 

pursuant to CAA section 111(d) and an 

EPA-issued EG, as well as apply to the 

EPA when it reviews state plan 

submissions. The regulations also 

govern the EPA’s development of EGs 

pursuant to CAA section 111(d), which 

apply to every state that contains 

designated facilities. 

The Administrator finds that this is a 

matter on which national uniformity in 

judicial resolution of any petitions for 

review is desirable, to take advantage of 

the D.C. Circuit’s administrative law 

expertise, and to facilitate the orderly 

development of the law under the Act. 

The Administrator also finds that 

consolidated review of this action in the 

D.C. Circuit will avoid piecemeal 

litigation in the regional circuits, further 

judicial economy, and eliminate the risk 

of inconsistent results, and that a 

nationally consistent approach to 

implementation of EGs pursuant to CAA 

section 111(d) constitutes the best use of 

agency resources. 

For these reasons, this final action is 

nationally applicable or, alternatively, 

the Administrator is exercising the 

complete discretion afforded to him by 

the CAA and finds that this final action 

is based on a determination of 

nationwide scope or effect for purposes 

of CAA section 307(b)(1) and is 

publishing that finding in the Federal 

Register. Under section 307(b)(1) of the 

CAA, petitions for judicial review of 

this action must be filed in the United 

States Court of Appeals for the District 

of Columbia Circuit by January 16, 2024. 

Under CAA section 307(b)(2), the 

requirements established by this final 

rule may not be challenged separately in 

any civil or criminal proceedings 

brought by the EPA to enforce the 

requirements. 

Additionally, pursuant to CAA 

section 307(d)(1)(V), the Administrator 

determines that this action is subject to 

the provisions of CAA section 307(d). 

The EPA made this determination at 

proposal and has complied with the 

applicable procedural requirements in 

the course of this rulemaking. Section 

307(d)(1)(V) of the CAA provides that 

the provisions of CAA section 307(d) 

apply to ‘‘such other actions as the 

Administrator may determine.’’ Section 

307(d)(7)(B) of the CAA further provides 

that ‘‘[o]nly an objection to a rule or 

procedure which was raised with 

reasonable specificity during the period 


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80482 Federal Register / Vol. 88, No. 221 / Friday, November 17, 2023 / Rules and Regulations 

5 In accordance with CAA section 111(d), states 

are required to submit plans to establish standards 

of performance for existing sources for any air 

pollutant: (1) the emission of which is subject to a 

Federal New Source Performance Standard; and (2) 

which is neither a pollutant regulated under CAA 

section 108(a) (i.e., criteria air pollutants such as 

ground-level ozone and particulate matter, and their 

precursors, like volatile organic compound) or a 

hazardous air pollutant regulated from the same 

source category under CAA section 112. See also 

definition of ‘‘designated pollutant’’ in 40 CFR 

60.21a(a). 

6The EPA has also issued several EGs that have 

subsequently been repealed or vacated by the 

courts. The EPA regulated mercury from coal-fired 

electric power plants in a 2005 rule that was 

vacated by the D.C. Circuit, ‘‘Standards of 

Performance for New and Existing Stationary 

Sources: Electric Utility Steam Generating Units; 

Final Rule,’’ 70 FR 28606 (May 18, 2005) (Clean Air 

Mercury Rule), vacated by New Jersey v. EPA, 517 

F.3d 574 (D.C. Cir. 2008). The EPA also issued CAA 

section 111(d) EGs regulating GHG emissions from 

fossil fuel-fired electric power plants in a 2015 rule, 

‘‘Carbon Pollution Emission Guidelines for Existing 

Stationary Sources: Electric Utility Generating 

Units; Final Rule,’’ 80 FR 64662 (October 23, 2015) 

for public comment (including any 

public hearing) may be raised during 

judicial review.’’ This section also 

provides a mechanism for the EPA to 

convene a proceeding for 

reconsideration, ‘‘[i]f the person raising 

an objection can demonstrate to the 

Administrator that it was impracticable 

to raise such objection within [the 

period for public comment] or if the 

grounds for such objection arose after 

the period for public comment (but 

within the time specified for judicial 

review) and if such objection is of 

central relevance to the outcome of the 

rule.’’ Any person seeking to make such 

a demonstration should submit a 

Petition for Reconsideration to the 

Office of the Administrator, U.S. 

Environmental Protection Agency, 

Room 3000, WJC South Building, 1200 

Pennsylvania Ave. NW, Washington, DC 

20460, with a copy to both the person 

listed in the preceding FOR FURTHER

INFORMATION CONTACT section, and the 

Associate General Counsel for the Air 

and Radiation Law Office, Office of 

General Counsel (Mail Code 2344A), 

U.S. Environmental Protection Agency, 

1200 Pennsylvania Ave. NW, 

Washington, DC 20460. 

The EPA notes that the individual 

regulatory provisions it is revising or 

finalizing in this action are severable 

from one another because each is 

supported by an independent rationale. 

That is, the individual subsections 

within each of the sections of subpart Ba 

are generally justified independently 

and are therefore severable for purposes 

of judicial review. 

II. Background 

A. What is the statutory authority for 

this action? 

The statutory authority for this action 

is provided by CAA section 111 (42 

U.S.C. 7411). As described further in the 

next section, CAA section 111 requires 

the EPA to establish standards of 

performance for certain categories of 

stationary sources that, in the 

Administrator’s judgment, ‘‘cause[ ], or 

contribute[] significantly to, air 

pollution which may reasonably be 

anticipated to endanger public health or 

welfare.’’ CAA section 111(b) provides 

the EPA’s authority to regulate new and 

modified sources, while CAA section 

111(d) directs the EPA to ‘‘prescribe 

regulations which shall establish a 

procedure’’ for states to submit plans to 

the EPA that establish standards of 

performance for existing sources of 

certain air pollutants to which a 

standard would apply if such existing 

source were a new source. The EPA 

addresses its obligation under CAA 

section 111(d) to establish a procedure 

for states to submit plans both through 

its promulgation of general 

implementing regulations, including 

those addressed by this action, and 

through promulgation of EGs for 

specific source categories. Additional 

statutory authority for this action is 

provided by section 301 of the CAA (42 

U.S.C. 7601), which contains general 

provisions for the administration of the 

CAA, including the authority for the 

Administrator to ‘‘prescribe such 

regulations as are necessary to carry out 

[the] functions’’ of the CAA under 

section 301(a)(1). 

B. What is the background for this 

action? 

Clean Air Act section 111(d) governs 

the establishment of standards of 

performance for existing stationary 

sources. CAA section 111(d) directs the 

EPA to ‘‘prescribe regulations which 

shall establish a procedure similar to 

that provided by [CAA section 110]’’ for 

states to submit state plans that 

establish standards of performance for 

existing sources of certain air pollutants 

to which a standard of performance 

would apply if such an existing source 

were a new source under CAA section 

111(b). Therefore, an existing source can 

only be regulated under CAA section 

111(d) if it belongs to a source category 

that is regulated under CAA section 

111(b). The EPA’s implementing 

regulations use the term ‘‘designated 

facility’’ to identify those existing 

sources. See 40 CFR 60.21a(b). 

CAA section 111(b)(1)(A) requires that 

a source category be included on the list 

for regulation if, ‘‘in [the EPA 

Administrator’s] judgment it causes, or 

contributes significantly to, air pollution 

which may reasonably be anticipated to 

endanger public health or welfare.’’ 

Once a source category is listed, CAA 

section 111(b)(1)(B) requires that the 

EPA propose and then promulgate 

‘‘standards of performance’’ for new 

sources in such source category. CAA 

section 111(a)(1) defines a ‘‘standard of 

performance’’ as ‘‘a standard for 

emissions of air pollutants which 

reflects the degree of emission 

limitation achievable through the 

application of the best system of 

emission reduction which (taking into 

account the cost of achieving such 

reduction and any nonair quality health 

and environmental impact and energy 

requirements) the Administrator 

determines has been adequately 

demonstrated.’’ This provision requires 

the EPA to determine both the best 

system of emission reduction (BSER) for 

the regulated source category and the 

degree of emission limitation achievable 

through application of the BSER. The 

EPA must then, under CAA section 

111(b)(1)(B), promulgate standards of 

performance for new sources that reflect 

that level of stringency. 

Once the EPA promulgates standards 

of performance for new sources within 

a particular source category, the EPA is 

required, in certain circumstances, to 

regulate emissions from existing sources 

in that same source category.5 Under 

CAA section 111(d), the Agency has, to 

date, issued EGs regulating five 

pollutants from six source categories 

that are currently in effect (i.e., sulfuric 

acid plants (acid mist), phosphate 

fertilizer plants (fluorides), primary 

aluminum plants (fluorides), kraft pulp 

plants (total reduced sulfur), municipal 

solid waste landfills (landfill gases)), 

and fossil fuel-fired electric generating 

units (greenhouse gases [GHGs]). See 

‘‘Phosphate Fertilizer Plants; Final 

Guideline Document Availability,’’ 42 

FR 12022 (March 1, 1977); ‘‘Standards 

of Performance for New Stationary 

Sources; Emission Guideline for 

Sulfuric Acid Mist,’’ 42 FR 55796 

(October 18, 1977); ‘‘Kraft Pulp Mills, 

Notice of Availability of Final Guideline 

Document,’’ 44 FR 29828 (May 22, 

1979); ‘‘Primary Aluminum Plants; 

Availability of Final Guideline 

Document,’’ 45 FR 26294 (April 17, 

1980); ‘‘Emission Guidelines and 

Compliance Times for Municipal Solid 

Waste Landfills,’’ 81 FR 59276 (August 

29, 2016); ‘‘Repeal of the Clean Power 

Plan; Emission Guidelines for 

Greenhouse Gas Emissions From 

Existing Electric Utility Generating 

Units; Revisions to Emission Guidelines 

Implementing Regulations,’’ 84 FR 

32520 (July 8, 2019) (Affordable Clean 

Energy (ACE) Rule).6 7 Additionally, the 


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(Clean Power Plan). The EPA subsequently repealed 

and replaced the 2015 rule with the ACE Rule. 

7The ACE Rule was initially vacated by Am. Lung 

Ass’n v. EPA, 985 F.3d 914 (D.C. Cir. 2021). The 

Supreme Court subsequently reversed and 

remanded the D.C. Circuit’s opinion, West Virginia 

v. EPA, 142 S. Ct. 2587 (June 30, 2022). On October 

27, 2022, the D.C. Circuit amended its judgement 

and recalled the partial mandate vacating the ACE 

Rule, effectively reinstating ACE. Order, ALA v. 

EPA, No. 19–1140, ECF No. 1970895. 

8CAA section 129 directs the EPA Administrator 

to develop regulations under CAA section 111 

limiting emissions of nine air pollutants from four 

categories of solid waste incineration units. 

9A ‘‘designated facility’’ is any existing facility 

which emits an air pollutant, the emissions of 

which are subject to a standard of performance for 

new stationary sources but for which air quality 

criteria have not been issues and that is not 

included on a list published under CAA section 

108(a) or 112, and which would be subject to a 

standard of performance for that pollutant if the 

existing facility were a new facility. See 40 CFR 

60.21a. 

10 In 2012, the EPA revised several provisions of 

subpart B, mainly to include allowance systems as 

a form of standard of performance. 77 FR 9303 

(February 16, 2012). 

EPA recently proposed EGs addressing 

GHG emissions from two different 

source categories. On November 15, 

2021, the EPA proposed EGs to regulate 

GHG emissions (in the form of methane 

limitations) from sources in the oil and 

natural gas source category (86 FR 

63110) and provided a supplemental 

proposal for that sector on December 6, 

2022 (87 FR 74702). On May 23, 2023, 

the EPA proposed to repeal the existing 

EG for GHG emissions from certain 

fossil fuel-fired electric generating units 

(the ACE Rule) and to promulgate a new 

EG in order to regulate GHG emissions 

(in the form of carbon dioxide 

limitations) from existing fossil fuelfired electric generating units. 88 FR 

33240. Finally, the Agency has 

regulated additional pollutants from 

solid waste incineration units under 

CAA section 129 and in accordance 

with CAA section 111(d).8

The mechanism for regulating 

designated facilities 9 under CAA 

section 111(d) differs from the 

mechanism for regulating new facilities 

under CAA section 111(b). Pursuant to 

CAA section 111(b), the EPA 

promulgates standards of performance 

that are directly applicable to new, 

modified, and reconstructed facilities in 

a specified source category. In contrast, 

CAA section 111(d) operates together 

with CAA section 111(a)(1) to 

collectively establish and define roles 

and responsibilities for both the EPA 

and the states in the regulation of 

designated facilities. Under the statutory 

framework, the EPA has the 

responsibility to determine the BSER for 

designated facilities, as well as the 

degree of emission limitation achievable 

through application of that BSER. The 

EPA identifies both the BSER and the 

degree of emission limitation as part of 

an EG, which it may typically reflect as 

a presumptive standard of performance 

or methodology for calculating a 

presumptive standard of performance 

for designated facilities. States use the 

EPA’s presumptive standards of 

performance as the basis for establishing 

requirements for designated facilities in 

their state plans. In addition to 

standards of performance, CAA section 

111(d)(1) requires state plans to include 

provisions for the implementation and 

enforcement of such standards. CAA 

section 111(d)(1) also requires the EPA’s 

regulations to permit states, in applying 

a standard of performance to particular 

sources, to take into account the 

source’s remaining useful life and other 

factors, a process addressed in more 

detail in section III.E of this preamble. 

CAA section 111(d) directs the EPA to 

establish a procedure for the submission 

of state plans, which the EPA addresses 

both through its promulgation of general 

implementing regulations for section 

111(d) and through promulgation of EGs 

for specific source categories. While 

CAA section 111(d)(1) authorizes states 

to develop state plans that establish 

standards of performance and provides 

states with certain discretion in 

determining the appropriate standards, 

CAA section 111(d)(2) provides the EPA 

a specific oversight role with respect to 

such state plans. The states must submit 

their plans to the EPA, and the EPA 

must evaluate each state plan to 

determine whether each plan is 

‘‘satisfactory.’’ If a state fails to submit 

a plan or the EPA determines that a state 

plan is not satisfactory, the EPA has the 

‘‘same authority’’ to prescribe a Federal 

plan as it has to promulgate a Federal 

Implementation Plan (FIP) under CAA 

section 110(c). 

In 1975, the EPA issued the first 

general implementing regulations to 

prescribe the process for the adoption 

and submittal of state plans for 

designated facilities under CAA section 

111(d) (codified at 40 CFR part 60, 

subpart B (subpart B)). 40 FR 53340 

(November 17, 1975). Responding to the 

direction to ‘‘establish a procedure 

similar to that provided by’’ CAA 

section 110, in promulgating subpart B, 

the EPA aligned the timing 

requirements for state and Federal plans 

under CAA section 111(d) with the 

then-applicable timeframes for State 

Implementation Plans (SIPs) and FIPs 

prescribed in CAA section 110, as 

established by the 1970 CAA 

Amendments. The implementing 

regulations were not significantly 

revised after their original promulgation 

in 1975 10 until 2019, when the EPA 

promulgated a new set of implementing 

regulations codified at 40 CFR part 60, 

subpart Ba (subpart Ba). 84 FR 32520 

(July 8, 2019). 

In promulgating subpart Ba in 2019, 

the EPA intended to update and 

modernize the implementing 

regulations to align the procedures for 

CAA section 111(d) state and Federal 

plans with CAA amendments made after 

subpart B was first promulgated in 1975. 

Notably, subpart B did not align either 

with CAA section 111(d) as amended by 

Congress in 1977 or with the timelines 

in CAA section 110 as amended by 

Congress in 1990. The EPA therefore 

considered it appropriate to update the 

implementing regulations for CAA 

section 111(d) to make changes similar 

to CAA section 110, given that section 

111(d)(1) of the CAA directs the EPA to 

‘‘prescribe regulations which shall 

establish a procedure similar to that 

provided by section 110’’ of the CAA for 

states to submit plans to the EPA. In 

promulgating subpart Ba, the EPA 

directly aligned the timing requirements 

for CAA section 111(d) state and Federal 

plans (40 CFR 60.23a(a)(1) and 

60.27a(c), respectively) with the timing 

requirements for SIPs and FIPs under 

CAA section 110 (see CAA section 

110(a)(1) and 110(c)(1), respectively). 

In promulgating subpart Ba, the EPA 

also added the definition of ‘‘standard of 

performance’’ (40 CFR 60.21a(f)) 

(defined under subpart B as ‘‘emission 

standard’’ (40 CFR 60.21(f))) and the 

‘‘remaining useful life’’ provision (40 

CFR 60.24a(e)) (referred under subpart B 

as the ‘‘variance’’ provision (40 CFR 

60.24(f))). The EPA further added 

required minimum administrative and 

technical criteria for inclusion in state 

plans (40 CFR 60.27a(g)). Applying 

these criteria, the EPA determines 

whether a state plan or portion of a plan 

submitted is complete (referred to as a 

completeness review). Once a state plan 

or portion of a plan is determined to be 

complete, the EPA must approve or 

disapprove the plan or portions of the 

plan. For details on the EPA’s rationale 

for the promulgation of these 

provisions, see 84 FR 32520 (July 8, 

2019). 

The EPA proposed minor revisions to 

the subpart Ba applicability provision 

and is finalizing those revisions largely 

as proposed (see section III.G.2.a. of this 

preamble). As finalized in 2019, subpart 

Ba was applicable to any final 111(d) EG 

published, or the implementation of 

which was ongoing, after July 8, 2019. 

The EPA proposed revisions to this 

provision for clarity, including to 


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11 87 FR 79176, 79208–09 (Dec. 23, 2022). As 

explained in section III.G.2.a. of this preamble, the 

EPA is finalizing the removal of this phrase from 

40 CFR 60.20a(a). 

12 84 FR 32520 (July 8, 2019). 

13 ‘‘New source Performance Standards for 

Greenhouse Gas Emissions From New, Modified, 

and Reconstructed Fossil Fuel-Fired Electric 

Generating Units; Emission Guidelines for 

Greenhouse Gas Emissions From Existing Fossil 

Fuel-Fired Electric Generating Units; and Repeal of 

the Affordable Clean Energy Rule,’’ 88 FR 33240 

(May 23, 2023). 

14The Supreme Court subsequently reversed and 

remanded the D.C. Circuit’s opinion. West Virginia 

v. EPA, 142 S.Ct. 2587 (June 30, 2022). However, 

no Petitioner sought certiorari on, and the Supreme 

Court’s West Virginia decision did not implicate, 

the D.C. Circuit’s vacatur of portions of subpart Ba. 

See Amended Judgment, ALA v. EPA, No. 19–1140 

(D.C. Cir. October 27, 2022), ECF No. 1970898 

(ordering that petitions for review challenging the 

timing portion of implementing regulations be 

granted). 

remove the phrase ‘‘if implementation 

of such final guideline is ongoing.’’ 11 It 

did not propose to change the alreadyestablished applicability date. At the 

time of promulgation of this rule, there 

are no final EGs that have been 

published after July 8, 2019, so subpart 

Ba will not retroactively apply to the 

implementation of any EG. Specifically, 

the final EG for greenhouse gas 

emissions from existing electric utility 

generating units that was included in 

the ACE Rule was published on July 8, 

2019; 12 thus, subpart Ba as revised will 

not apply to that EG. Regardless, the 

EPA proposed to repeal the ACE Rule 

on May 23, 2023,13 and intends to 

finalize its repeal, at which point 

neither states nor the EPA will have any 

obligations under the ACE Rule and the 

potential applicability of subpart Ba to 

this EG will be moot. In contrast, the 

EPA has recently proposed two EGs that 

would regulate GHG emissions from 

designated facilities in the oil and 

natural gas industry (86 FR 63110, 

November 15, 2021; 87 FR 74702, 

December 6, 2022) and in the power 

sector (88 FR 33240, May 23, 2023). If 

those EGs are finalized and to the extent 

that the final EGs do not contain EGspecific requirements superseding 

subpart Ba provisions, subpart Ba as 

revised in this action will apply. 

Subpart B continues to apply to CAA 

section 111 EGs promulgated on or prior 

to July 8, 2019, and to EGs issued 

pursuant to CAA section 129. 

In January 2021, the D.C. Circuit 

vacated several provisions of subpart Ba 

related to timelines for state plans and 

Federal plans. Am. Lung Ass’n v. EPA, 

985 F.3d 914, 991. (D.C. Cir. 2021) 

(ALA).14 In this vacatur, the court 

identified several flaws in the EPA’s 

rationale for extending CAA section 

111(d) state and Federal plan timelines. 

First, the court found that the EPA erred 

in adopting the timelines for SIPs and 

FIPs in CAA section 110 without 

meaningfully addressing the differences 

in the scale of effort required for 

development and evaluation of CAA 

section 110 SIPs, as compared with the 

scale of effort needed for CAA section 

111(d) state plans. Id. at 992–93. The 

court also concluded that in 

promulgating the timelines in subpart 

Ba, the EPA failed to justify why the 

shorter deadlines under subpart B were 

unworkable. Id. at 993. Further, the 

court held that the EPA was required to 

consider the effect of its subpart Ba 

timelines on public health and welfare, 

consistent with the statutory purpose of 

CAA section 111(d). In the court’s view, 

the EPA’s ‘‘complete failure to say 

anything at all about the public health 

and welfare implications of the 

extended timeframes’’ meant that the 

EPA failed to consider an important 

aspect of the problem. Id. at 992 (citing 

Motor Vehicle Mfrs. Ass’n of U.S., Inc. 

v. State Farm Mut. Auto. Ins. Co. 463 

U.S. 29, 43 (1983)). 

Based on these reasons, the court 

vacated the timeline for state plan 

submissions after publication of a final 

EG (40 CFR 60.23a(a)(1)), the EPA’s 

deadline for taking action on state plan 

submissions (40 CFR 60.27a(b)), the 

EPA’s deadline for promulgating a 

Federal plan (40 CFR 60.27a(c)), and the 

timeline associated with requirements 

for increments of progress (IoPs; 40 CFR 

60.24 (a(d)). Because of the vacatur, 

subpart Ba currently does not provide 

generally applicable timelines for state 

plan submissions, a deadline for the 

EPA’s action on state plan submissions, 

a deadline for the EPA’s promulgation 

of a Federal plan, or a timeline 

associated with requirements for IoPs. 

The EPA notes that while it is finalizing 

generally applicable timelines for the 

implementing regulations, a particular 

EG may supersede those generally 

applicable timelines with its own 

specific timelines. 40 CFR 60.20a(a)(1). 

This may be appropriate, for example, 

based on the complexity of regulating a 

particular source category, such as a 

category with a large number of 

disparate facilities to be regulated. 

C. What changes did we propose? 

On December 23, 2022, the EPA 

proposed several revisions to subpart Ba 

both to address the vacatur of the timing 

provisions by the D.C. Circuit in ALA 

and to further improve the state and 

Federal plan development and 

implementation process. See 87 FR 

79176 (December 23, 2022). In response 

to the ALA decision, the EPA proposed 

timeframes for (1) state plan submittal, 

(2) the timeline for the EPA to 

determine completeness of state plans, 

(3) the EPA’s action on state plan 

submissions, (4) the EPA’s promulgation 

of a Federal plan, and (5) requirements 

to establish IoPs. Additionally, the EPA 

proposed to remove the publication in 

the Federal Register of a ‘‘finding of 

failure to submit’’ as the starting point 

for the clock to promulgate a Federal 

plan. 

In addition, the EPA proposed 

revisions to subpart Ba that would 

enhance the provision of reasonable 

notice and opportunity for public 

participation by requiring that states, as 

part of the state plan development or 

revision process, undertake outreach 

and meaningful engagement with a 

broad range of pertinent stakeholders. 

The EPA proposed to define pertinent 

stakeholders as including communities 

most affected by and vulnerable to the 

impacts of the plan or plan revision. 

Increased vulnerability, as described in 

the proposal, may be attributable, 

among other reasons, to both an 

accumulation of negative and lack of 

positive environmental, health, 

economic, or social conditions within 

these populations or communities. 

To improve flexibility and efficiency 

in the submission, review, approval, 

and implementation of state plans, the 

EPA proposed to include the following 

mechanisms in subpart Ba, all of which 

currently exist under CAA section 110: 

(1) partial approval/disapproval, (2) 

conditional approval, (3) allowance for 

parallel processing, (4) a mechanism for 

the EPA to call for plan revisions, and 

(5) an error correction mechanism. 

The EPA also proposed revisions to 

the existing regulations governing the 

‘‘remaining useful life and other factors’’ 

(RULOF) provision of the statute. These 

proposed revisions were intended to 

promote clarity and increase 

consistency in situations where states or 

the EPA consider RULOF when 

applying standards of performance to 

individual sources and to ensure that 

such standards fulfill the statutory 

requirements of CAA section 111(d). 

Finally, the EPA proposed to require 

electronic submissions of state plans, as 

well as additional modifications and 

clarifications to subpart Ba. In 

particular, the EPA proposed clarifying 

amendments to the subpart Ba 

definition of standard of performance, 

along with a revised interpretation of 

CAA section 111(d) with respect to 

permissible compliance flexibilities. 

The EPA proposed to determine that, 

under appropriate circumstances, the 

Agency may approve state plans that 

authorize sources to meet their emission 

limits in the aggregate, such as through 

standards that permit compliance via 


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15See, e.g., 88 FR 33240, 33402–03 (May 23, 

2023) (proposing a 24-month state plan submission 

deadline for the EG for GHG emissions from fossil 

fuel-fired electric generating units). 16See 87 FR 79176, 79181–90 (Dec. 23, 2022). 

trading or averaging. In doing so, the 

EPA also proposed to conclude that 

CAA section 111 does not limit the 

BSER to controls that can be applied at 

and to the source. 

The EPA did not reopen any subpart 

Ba requirements other than the specific 

provisions that the EPA explicitly 

proposed to revise in the December 

2022 notice of proposed rulemaking. 

Any comments received on the proposal 

that did not relate to the proposed 

revisions or additions are considered 

out of the scope of this action. 

D. What outreach and engagement did 

the EPA conduct? 

The EPA conducted both pre- and 

post-proposal outreach and meaningful 

engagement events with environmental 

justice (EJ) communities, small 

businesses, states, and Tribes. On July 7 

and July 11, 2022, the EPA conducted 

two pre-proposal webinars for states 

addressing meaningful engagement for 

pertinent stakeholders, and on July 26, 

2022, the Agency conducted a preproposal webinar for EJ communities 

and other key stakeholders about 

potential requirements for states to 

conduct meaningful engagement in 

developing their state plans. The EPA 

emailed an announcement of the 

subpart Ba proposal to Tribal nations 

and environmental justice communities 

via existing listservs on December 15, 

2022. Post-proposal outreach during the 

public comment period with 

environmental justice communities 

included participation on the January 

24, 2023 Environmental Justice National 

call and the January 26, 2023 National 

Tribal Air Association call. The EPA 

also conducted a public training 

webinar on January 31, 2023, for 

environmental justice community 

members and their representatives. 

Additionally, the EPA conducted postproposal outreach with small businesses 

through the Small Business 

Environmental Assistance Program call 

on February 21, 2023, and with state 

environmental protection associations 

including the Association of Air 

Pollution Control Agencies on January 

10, 2023, and the National Association 

of Clean Air Agencies on February 8, 

2023. 

III. What actions are we finalizing and 

what is our rationale for such 

decisions? 

This action finalizes amendments to 

subpart Ba, including the timing 

requirements for state plan submittal, 

the EPA’s action on state plan 

submissions, the EPA’s promulgation of 

a Federal plan, and the establishment of 

IoPs; the addition of five regulatory 

mechanisms to improve state plan 

processing: (1) partial approval/ 

disapproval, (2) conditional approval, 

(3) allowance for parallel processing, (4) 

a mechanism for the EPA to call for plan 

revisions, and (5) an error correction 

mechanism; new requirements for 

meaningful engagement with pertinent 

stakeholders; and amended 

requirements for states’ and the EPA’s 

consideration of RULOF in applying a 

standard of performance in certain 

circumstances. This action also finalizes 

amendments to the subpart Ba 

definition of ‘‘standard of performance’’ 

and finalizes clarifications associated 

with CAA section 111(d) compliance 

flexibilities. Finally, this action finalizes 

requirements for the electronic 

submission of state plans and several 

other clarifications and minor revisions 

to the implementing regulations. While 

the EPA is finalizing most amendments 

as proposed, in response to comments 

submitted on the proposal, the EPA is 

extending the state plan submittal 

timeline and the timeline for 

requirement of IoPs; providing for 

additional flexibility and guidance for 

meaningful engagement; as well as 

revising and streamlining the 

requirements for accounting for RULOF 

in applying a less-stringent standard. 

There are also other provisions that we 

are finalizing with slight revisions 

relative to proposal. Further detail is 

provided in the following sections of 

this preamble and additional detailed 

responses to comments are located in 

the response to comment document 

(RTC). 

While this action amends the 

generally applicable requirements of 

subpart Ba, the EPA has recognized that, 

under certain circumstances, some 

provisions of the implementing 

regulations may not fit the needs of a 

specific EG. Therefore, the existing 

implementing regulations provide that 

each EG may include specific 

implementing provisions in addition to 

or that supersede the requirements of 

subpart Ba. 40 CFR 60.20a(a)(1). The 

EPA will address source categoryspecific circumstances or facts that are 

not accommodated by the general 

provisions of subpart Ba through a 

specific EG, as the time and processes 

needed for development and adoption 

of state plans to implement the EG may 

be affected by unique characteristics of 

a source category. For example, if a 

proposed EG addresses a particularly 

large and complex source category that 

necessitates a relatively long timeframe 

for state planning, the EPA may provide 

a state plan submission deadline that is 

longer than the 18 months being 

finalized for subpart Ba.15

A. Revised Implementing Timelines 

As described in section II.A. of this 

preamble, the subpart Ba timing 

requirements were vacated by the D.C. 

Circuit in the ALA decision. These 

vacated timing requirements include: 

the timeline for state plan submissions, 

the timeline for the EPA to act on a state 

plan, the timeline for the EPA to 

promulgate a Federal plan, and the 

timeline that dictates when state plans 

must include IoPs. These timelines are 

all critical to ensuring that the emission 

reductions anticipated by the EPA when 

promulgating an EG become federally 

enforceable measures that are timely 

implemented by the designated 

facilities. 

The EPA proposed the following 

timelines to replace those vacated in 

ALA (87 FR 79176, Dec. 23, 2022): 15 

months for state plan submissions after 

publication of a final EG; 60 days after 

submission for the EPA to determine if 

a plan is complete; 12 months for the 

EPA to take final action on a complete 

state plan (i.e., approve, disapprove); 12 

months for the EPA to promulgate a 

Federal plan either after the state plan 

submission deadline if a state has failed 

to submit a complete plan, or after the 

EPA’s disapproval of a state plan 

submission; and requiring state plans to 

include IoPs if the plan requires final 

compliance with standards of 

performance later than 16 months after 

the plan submission deadline.16

The EPA received numerous 

comments on these proposed timelines, 

most of which expressed support for 

timelines longer than those proposed. 

Some commenters asserted that the ALA 

decision does not direct the EPA to 

necessarily reduce timelines from those 

vacated, only to justify the timelines 

more fully. In particular, most 

commenters expressed the need for a 

longer state plan submittal timeline in 

order to accommodate state regulatory 

processes associated with plan 

submittals (i.e., legislative and/or 

administrative state processes), as well 

as to accommodate technical 

development of the plans and to 

implement the proposed meaningful 

engagement requirements. However, a 

few commenters noted that the EPA 

should not accommodate all lengthy 

state administrative processes that 

would unnecessarily postpone 

emission-reduction obligations. Some 


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17Under each of these EGs the EPA proposed to 

supersede the 15-month state plan submittal 

timeline in proposed subpart Ba based on the size 

and complexity of the source sectors at issue. 

commenters asserted that if the EPA 

were to finalize the state plan submittal 

timeline as proposed, the EPA should 

include a mechanism in the rule for 

states to request for extensions for state 

plan submittals. 

While some commenters also asserted 

the need for longer timelines associated 

with the EPA’s obligations to take action 

on a state plan submittal and to 

promulgate a Federal plan when 

required, as well as allowing a longer 

timeline before IoPs are required in the 

state plans, other commenters supported 

the proposed timelines for these 

milestones based, among other 

concerns, on the need for timely 

protection of health and welfare and in 

consideration of the EPA’s ability to 

extend timelines if warranted in a 

particular EG. 

In consideration of these comments 

and for the reasons described in detail 

in the sections that follow, the EPA is 

finalizing extended timelines from those 

proposed for submission of state plans, 

for significant state plan revisions, and 

for when IoPs must be considered for 

inclusion in state plans. The EPA is 

finalizing the remaining timelines as 

proposed. The EPA determined that 

these timelines will appropriately 

balance the need to reasonably 

accommodate the processes generally 

required by states and the EPA to 

develop, evaluate, and adopt plans to 

effectuate the EG with the need to 

ensure that designated facilities control 

emissions of dangerous pollutants as 

expeditiously as reasonably possible, 

consistent with the health and welfarebased objectives of CAA section 111(d). 

A summary of the timelines finalized in 

this action is shown in Table 1. 

The final subpart Ba timelines are 

applicable to any final EG published 

pursuant to CAA section 111(d) after 

July 8, 2019, including, if finalized, 

those recently proposed to regulate GHG 

emissions from sources in the oil and 

natural gas industry (86 FR 63110, 

November 15, 202187 and FR 74702, 

December 6, 2022) and those proposed 

to regulate GHG emissions from fossil 

fuel-fired electric generating units (88 

FR 33240, May 23, 2023), to the extent 

that the final EGs do not contain 

provisions superseding any of these 

timelines in subpart Ba.17

TABLE 1—FINAL 40 CFR PART 60, SUBPART Ba, TIMELINE COMPARED WITH THOSE INITIALLY PROPOSED, VACATED

FROM SUBPART Ba, AND FROM SUBPART B 

Process step 2023 Subpart Ba final 2022 Subpart Ba proposal Subpart Ba (2019) vacated 

timelines 

Subpart B 

(1975) 

State Plan submittal after 

publication of EG in the 

Federal Register.

18 months ......................... 15 months ......................... 36 months ......................... 9 months. 

State Plan completeness 

determination.

60 days after State Plan 

submission.

60 days after State Plan 

submission.

*6 months after State Plan 

submission.

N/A. 

State Plan evaluation ........ 12 months after completeness.12 months after completeness.12 months after completeness.4 months after State Plan 

submittal deadline. 

EPA Federal Plan promulgation.12 months after failure to 

submit or disapproval.

12 months after failure to 

submit or disapproval.

24 months after finding of 

failure to submit or disapproval.

6 months after State Plan 

submittal deadline. 

Requirements for Increments of Progress after 

submittal deadline.

If compliance is >20 

months.

If compliance is >16 

months.

If compliance is >24 

months.

If compliance is >12 

months. 

* Although the timeline for the state plan completeness determinations was not vacated, the EPA has evaluated this timeline light of the court 

vacatur of the related timelines. 

As described in greater detail in 

section II. of this preamble, the D.C. 

Circuit’s vacatur of the extended 

timelines in subpart Ba was based both 

on the EPA’s failure to substantiate the 

necessity for the additional time at each 

step of the administrative process, and 

the EPA’s failure to address how those 

extended implementation timelines 

would impact public health and 

welfare. Accordingly, the EPA has 

evaluated these factors and is finalizing 

timelines, as described in the following 

sections, based on the minimum 

administrative time reasonably 

necessary for each step in the 

implementation process, thus 

minimizing impacts on public health 

and welfare by proceeding as 

expeditiously as reasonably possible 

while accommodating the time needed 

for states or the EPA to develop an 

effective plan. This approach addresses 

both aspects of the ALA decision 

because the EPA and states will take no 

longer than necessary to develop and 

adopt plans that impose requirements 

consistent with the overall objectives of 

CAA section 111(d). 

The EPA acknowledges these 

timelines are not identical to those for 

SIPs under CAA section 110. This is 

consistent with the requirement of CAA 

section 111(d) that the EPA promulgate 

a procedure ‘‘similar’’ to that of CAA 

section 110, rather than an identical 

procedure. This is also consistent with 

the ALA decision, which requires the 

EPA to ‘‘engage meaningfully with the 

different scale’’ of CAA section 111(d) 

and 110 plans. 985 F.3d at 993. In 

proposing the revised timelines, the 

EPA evaluated each step of the state 

plan implementation process to 

independently determine the 

appropriate duration needed to 

accomplish a given step as part of the 

overall process. After receiving 

comments on the proposed timelines, 

the EPA again evaluated each step in 

light of the new information; the 

timelines being finalized in this action 

represent the Agency’s revised 

assessment of the most reasonably 

expeditious timelines that are 

appropriate to provide as a default for 

EGs under these generally applicable 

implementing regulations. 

The EPA recognizes that, under 

certain circumstances, the timelines 

being finalized in this action may not fit 

the needs of a specific EG because of the 

specific characteristics of an EG. The 

EPA will address source categoryspecific circumstances or facts that are 

not accommodated by the timelines of 

subpart Ba through a specific EG. 

Examples of circumstances that may 

require consideration for different 


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18 In many states, the agency must submit its rule 

to a particular independent commission or the 

legislature for review and approval before the rule 

is finally adopted. Generally, adopted rules are filed 

with a state entity, such as the secretary of state, 

and eventually published in a register and placed 

into the state’s administrative code. State law 

establishes when an adopted rule is effective. 

19The EPA reviewed the information available in 

40 CFR part 62. The supporting information 

reviewed is available at Docket ID No. EPA–HQ– 

OAR–2021–0527. Part 62 codifies the 

Administrator’s approval and disapproval of state 

plans for the control of pollutants and facilities 

under CAA section 111(d), and under CAA section 

129 as applicable, and the Administrator’s 

promulgation of such plans or portions of plans 

thereof. 

20The EPA reviewed the information available in 

40 CFR part 62. The supporting information 

reviewed is available at Docket ID No. EPA–HQ– 

OAR–2021–0527. Part 62 codifies the 

Administrator’s approval and disapproval of state 

plans for the control of pollutants and facilities 

under CAA section 111(d), and under CAA section 

129 as applicable. 

timelines could include EGs that require 

states to perform extensive engineering 

and/or economic analyses before 

submitting their plans; EGs with an 

exceptional need to expedite 

implementation (e.g., in order to address 

immediate health and welfare impacts); 

EGs that apply to an extraordinary 

number of disparate designated 

facilities; or EGs that are novel and/or 

unusually complex. For situations like 

these, 40 CFR 60.20a(a)(1) provides that 

an EG may supersede any aspect of the 

implementing regulations, including the 

implementation timelines. It is within 

the EPA’s discretion to determine 

whether a proposed change in 

implementation time may be justified 

within an individual EG based on these 

or other appropriate factors. For EGs 

that supersede implementation 

timelines, the EPA will, in the EG, both 

provide a justification for the differing 

timelines and address how the change 

in timeline will impact health and 

welfare. 

1. State Plan Submission Timelines 

This section discusses the amount of 

time states will have to submit plans 

and plan revisions to the EPA following 

the publication of a final or revised EG 

in the Federal Register. As described in 

further detail in section III.E of this 

preamble, under CAA section 111(d), 

the EPA first determines a BSER and the 

degree of emission limitation for 

designated facilities and promulgates 

these determinations in an EG. CAA 

section 111(a)(1), 40 CFR 60.22a(b)(5). It 

is then each state’s obligation to submit 

a plan to the EPA which establishes 

standards of performance based on the 

EG for each designated facility. See CAA 

section 111(d)(1), 40 CFR 60.24a(c). The 

implementing regulations promulgated 

in 1975 under subpart B provide that 

states have 9 months to submit a state 

plan after publication of a final EG. 40 

CFR 60.23(a)(1). In 2019, the EPA 

promulgated subpart Ba and provided 3 

years for states to submit plans or plan 

revisions for subsequently promulgated 

or revised EGs, consistent with the 

timelines provided for submission of 

SIPs pursuant to CAA section 110(a)(1). 

This 3-year timeframe was vacated by 

the D.C. Circuit in the ALA decision, 

and thus currently there is no applicable 

deadline for state plan submissions and 

revisions required under EGs subject to 

subpart Ba. 

As laid out in the notice of proposed 

rulemaking and summarized below, in 

evaluating the appropriate timeline for 

plan submittal to replace the vacated 

provisions in subpart Ba, the EPA 

reviewed steps that states need to carry 

out to develop, adopt, and submit a state 

plan to the EPA, and its history in 

implementing EGs under the timing 

provisions of subpart B. The EPA 

further evaluated the statutory deadlines 

and processes for relatively comparable 

state plans under CAA section 129, and 

attainment planning SIPs submitted 

pursuant CAA sections 189(a)(2)(B) and 

189(b)(2) for the 2012 National Ambient 

Air Quality Standards (NAAQS) for fine 

particulate matter (PM2.5). 78 FR 3085 

(January 15, 2013). Finally, the EPA 

incorporated consideration of the ALA 

decision addressing expediency in 

implementation of EGs for protection of 

public health and welfare. 

To develop a CAA section 111(d) state 

plan, a state must complete a series of 

steps to ensure that the plan will meet 

all applicable requirements. Subpart Ba 

specifies the elements that must be 

included in a state plan submission (see 

40 CFR 60.24a, 60.25a, 60.26a) as well 

as certain processes that a state must 

undertake in adopting and submitting a 

plan (see 40 CFR 60.23a). In addition to 

the requirements of these implementing 

regulations, there are also state-specific 

processes applicable to the development 

and adoption of a state plan, including 

the administrative processes (e.g., 

permitting processes, regulatory 

development, legislative approval) 

necessary to develop and adopt 

enforceable standards of performance. 

State plan development generally 

involves several phases, including 

providing notice that the state agency is 

considering adopting a rule; taking 

public comment; and approving or 

adopting a final rule. The process 

required to formally adopt a rule at the 

state level differs from state to states.18

As previously mentioned, subpart B 

provides 9 months for states to submit 

plans after publication of a final EG. The 

EPA’s review of state’s timeliness for 

submitting CAA section 111(d) plans 

under the 9-month timeline indicated 

that most states either did not submit 

plans or submitted plans that were 

substantially late.19 The EPA also noted 

that the plans submitted under subpart 

B were not subject to additional 

requirements for meaningful 

engagement and consideration of 

RULOF, which may add time to the 

state development process relative to 

plans developed and submitted under 

subpart B. For these reasons, the EPA 

found that 9 months is not a reasonable 

amount of time for most states to 

adequately develop a plan for an EG. 

To help inform the proposal for the 

state plan submission deadline, the EPA 

also reviewed CAA section 129’s 

statutory deadline and requirements for 

state plans, and the timeliness and 

responsiveness of states under CAA 

section 129 EGs. CAA section 129 

references CAA section 111(d) in many 

instances, creating considerable overlap 

in the functionality of the programs. The 

processes for CAA sections 111(d) and 

129 are similar in that states are 

required to submit plans to implement 

and enforce the EPA’s EGs. However, 

there are some key distinctions between 

the two programs, most notably that 

CAA section 129(b)(2) specifies that 

state plans be submitted no later than 1 

year from the promulgation of a 

corresponding EG, whereas the statute 

does not specify a particular timeline for 

state plan submissions under CAA 

section 111(d). Moreover, CAA section 

129 plans are required by statute to be 

at least as protective as the EPA’s EGs, 

without exception. CAA section 

129(b)(2). While CAA section 111(d) 

permits states to take into account 

remaining useful life and other factors 

to set less stringent standards for 

particular sources. This suggests that the 

development of a CAA section 111(d) 

plan could involve more complicated 

analyses than a CAA section 129 plan 

and that a longer timeframe is likely 

reasonable for state plans under CAA 

section 111(d) than the 1-year timeframe 

the statute provides under CAA section 

129. 

Additionally, the EPA found that a 

considerable number of states have not 

made timely state plan submissions in 

response to previous CAA section 129 

EGs. In instances where states submitted 

CAA section 129 plans, a significant 

number of states submitted plans 

between 14 to 17 months after the 

promulgated EG.20 This again suggests 

that states will typically need more than 


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21See, e.g., CAA sections 110(k)(5); 129; 

179(d)(1); 189. 

one year to develop a state plan to 

implement an EG. 

In the 2019 promulgation of subpart 

Ba, the EPA mirrored CAA section 110 

by giving states 3 years to submit plans. 

As previously described, the D.C. 

Circuit faulted the EPA for adopting the 

CAA section 110 timelines without 

accounting for the differences in scale 

and scope between CAA section 110 

and 111(d) plans. Therefore, in 

proposing the revised timelines the EPA 

closely evaluated other statutory 

deadlines and requirements for state 

implementation plans to determine 

what is feasible for a CAA section 

111(d) state plan submission timeline. 

The EPA specifically focused on 

statutory SIP submission deadlines and 

requirements in the context of 

attainment plans for the 2012 PM2.5.

NAAQS under CAA section 189 because 

it provided a comparable process. CAA 

section 189(a)(2)(B) requires states to 

submit attainment planning SIPs within 

18 months after an area is designated 

nonattainment and there is a record of 

successful state submittals pursuant to 

this timeline. The 2012 PM2.5. NAAQS 

attainment plans were, in most cases, 

more complicated for states to develop 

when compared to a typical plan that 

may be required under CAA sections 

111(d). For example, attainment plans 

require states to determine how to 

control a variety of sources, based on 

extensive modeling and analyses, in 

order to bring a nonattainment area into 

attainment of the PM2.5 NAAQS by a 

specified date. Identification of 

contributing emission sources and the 

development of effective control 

strategies can be challenging because 

particulate matter pollution is 

comprised of both primary emissions 

and secondary particle formation. By 

contrast, under CAA section 111(d), it is 

clear which designated facilities are 

subject to a state plan, in general what 

control methods are available for the 

designated pollutant from that facility, 

and that the standards of performance 

for these sources must reflect the level 

of stringency for the facility as 

determined by the EG unless a state 

chooses to account for RULOF. 

Informed by these analyses, the EPA 

proposed to require that each state 

adopt and submit to the Administrator 

a plan for the control of the designated 

pollutant(s) to which the EG applies 

within 15 months of publication of a 

final EG. Some commenters supported 

the proposed timeline based on the need 

for urgency in achieving the emission 

reductions targeted by an EG. 

Additionally, some commenters noted 

that, in comparison with NAAQS SIP 

requirements, states are generally wellpositioned to address the source sectors 

historically regulated under CAA 

section 111(d) and have access to 

information about control strategies and 

regulatory approaches for controlling 

emissions. Most commenters on this 

issue were state agencies or other staterelated entities that generally expressed 

the need for a longer state plan 

submittal timeline in order to 

accommodate state regulatory processes 

associated with plan submittals (i.e., 

legislative and/or administrative state 

processes), as well as to accommodate 

technical development of the plans and 

to implement the proposed meaningful 

engagement requirements. 

Approximately 10 states responded to 

the EPA’s request with information 

about their state processes. The 

information received indicates that 

states argued that they need anywhere 

from 15 months to 36 months to adopt 

and submit state plans. As discussed 

further below, the EPA is finalizing a 

state plan submittal timeline of 18 

months. It is doing so after 

consideration of comments received on 

the proposal and recognizing the need 

to protect public health and welfare. 

The EPA has determined that 18 months 

is the appropriate timeline for these 

general implementing regulations; for a 

generic EG, this represents a reasonable 

balance between providing states 

sufficient time to develop and submit a 

plan that satisfies the applicable 

requirements and ensuring that the 

emission reductions contemplated in an 

EG are achieved as expeditiously as 

practicable. Consistent with the existing 

regulations of subpart Ba, 40 CFR 

60.20a(a)(1), the EPA may supersede 

this 18-month state plan submittal 

timeline in an individual EG. 

The proposed 15-month submittal 

timeline was based on the EPA’s 

proposed determination that this was a 

reasonably expeditious deadline that 

would provide states and stakeholders 

sufficient time to develop and submit an 

approvable state plan. However, based 

on public comments received, we no 

longer believe that 15 months will 

provide sufficient time to complete the 

substantive and procedural 

requirements under subpart Ba. For 

example, the EPA is revising subpart Ba 

to require that states demonstrate 

meaningful engagement as part of their 

state plan development. While the time 

needed to conduct meaningful 

engagement will depend highly on the 

source category, the designated 

pollutant, and the types of impacts 

associated with designated facilities and 

potential controls, as well as on the 

pertinent stakeholders under a given EG 

within each state, it is very likely to 

require additional time relative to the 

existing public notice and hearing 

requirements under CAA section 110 

and subpart Ba. We received comments 

that 15 months would be insufficient 

time to identify pertinent stakeholders, 

develop public participation strategies, 

and conduct outreach and engagement. 

Some commenters also pointed out that 

adding requirements, such as 

meaningful engagement and RULOF, 

without a corresponding extension of 

time to develop plans may undermine 

states’ abilities to submit timely, 

approvable plans. While some 

commenters requested 36 months to 

submit state plans, several indicated 

that a minimum timeframe of 18 months 

would be appropriate for a state plan 

under a generic EG. Given the 

preponderance of comments suggesting 

that 15 months was not a reasonable 

amount of time to develop an 

approvable state plan and in recognition 

of the need to promulgate a timeline 

that achieves emission reductions as 

expeditiously as practicable, the EPA 

believes 18 months is the most 

reasonable timeline to include in these 

generally applicable implementing 

regulations. 

The EPA acknowledges that, as 

commenters asserted, state regulatory 

and legislative processes and resources 

can vary significantly and influence the 

time needed to develop and submit state 

plans (e.g., legislative procedures and 

timelines vary by state). Some 

commenters opposed to a shorter state 

plan submission timeline asserted that 

they need 36 months to complete their 

administrative and legislative processes. 

However, because the CAA contains 

numerous, long-standing requirements 

under other programs for states to 

develop and submit plans within 18 

months (or fewer),21 the EPA believes 

that states should be well positioned to 

accommodate an 18-month submittal 

timeline for plans under section 111(d). 

In designing a submittal deadline for 

state plans, it is reasonable to look to 

what Congress has determined are 

appropriate timelines for SIPs and to 

assume that states should be able to 

accommodate comparable timelines 

under CAA section 111(d). Indeed, some 

commenters recommend that the EPA 

not defer to lengthy state administrative 

processes, and expressed concern that 

some states have adopted, or may adopt, 

procedures that are longer than 

necessary and that will unnecessarily 

postpone Federal emission-reduction 

obligations. To this point, extending 


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22See, e.g., 80 FR 64510, 64530 (Oct. 23, 2015). 

23 88 FR 33240, 33252 (May 23, 2023). 

state plan submittal timelines to account 

for any and all unique state procedures 

would inappropriately delay reductions 

in emissions that have been found 

under CAA section 111 to endanger 

health or the environment. 

Some commenters asserted that the 

ALA decision does not preclude the 

EPA from adopting a 36-month time 

frame for state plan submittals and that 

the Agency need only justify a longer 

timelines more fully. However, the EPA 

recognizes that the D.C. Circuit, in ALA, 

faulted the Agency for failing to 

consider the potential impacts to public 

health and welfare associated with 

extending planning deadlines. In 

response, the EPA is promulgating a 

state plan submittal timeline that 

reflects the generally expeditious period 

of time for states to develop and submit 

a plan per the corresponding emission 

guidelines that is both comprehensive 

and legally sound. The EPA does not 

interpret the court’s direction to require 

a quantitative measure of impact, but 

rather consideration of the importance 

of meeting the public health and welfare 

goals when determining appropriate 

deadlines for implementation of 

regulations under CAA section 111(d). 

Based on EPA’s assessment of the time 

it will take for states to develop and 

submit plans under these general 

implementing regulations, both in the 

notice of proposed rulemaking and this 

preamble and after consideration of 

comments received, the EPA has 

determined that 18 months represents 

the generally expeditious period of time. 

Some commenters stated that 

reduction of the designated pollutants 

addressed by currently proposed 

emission guidelines (i.e., GHG) is not 

urgent based on the fraction of global 

GHG reduced by currently proposed 

emission guidelines, so a longer state 

plan timeline would be justified. The 

EPA disagrees with the commenters’ 

characterizations of the threat posed by 

elevated concentrations of greenhouse 

gases in the atmosphere. The EPA has 

determined that greenhouse gas air 

pollution may reasonably be anticipated 

to endanger public health or welfare 22

and has explained that ‘‘scientific 

assessments, EPA analyses, and 

documented observed changes in the 

climate of the planet and of the U.S. 

present clear support regarding the 

current and future dangers of climate 

change and the importance of GHG 

emissions mitigation.’’ 23 Moreover, 

subpart Ba applies to any EG 

promulgated after July 8, 2019, not only 

to the recently proposed EGs addressing 

GHG emissions from two source 

categories. The EPA regulates source 

categories, through EGs, that emit 

pollutants the Agency has determined 

under CAA section 111(d) to cause or 

significantly contribute to an 

endangerment of public health or 

welfare. Accordingly, consistent with 

ALA, it is appropriate for the EPA to set 

an expeditious but reasonable schedule 

in these general provisions for state plan 

development and submission to ensure 

that emission reductions occur in a 

timely manner. 

Finally, some commenters asserted 

that if the EPA were to finalize the state 

plan submittal timeline as proposed, the 

EPA should include a mechanism in 

subpart Ba for states to ask for 

extensions of the state plan submittal 

deadline. However, as we are providing 

additional time for state plan submittals 

relative to proposal, we are not 

providing a mechanism for states to 

request deadline extensions in subpart 

Ba. Additionally, the EPA has the ability 

to supersede the timelines in subpart Ba 

in individual EGs and will take into 

account any unique considerations that 

may result in the need for longer or 

shorter timelines on an EG-by-EG basis. 

In summary, while the EPA proposed 

a 15-month state plan submittal 

timeline, after consideration of 

comments, the EPA is finalizing 40 CFR 

60.23a(a)(1) to provide an 18-month 

timeline for the submission of state 

plans following publication in the 

Federal Register of a final EG. The EPA 

has determined that this is the generally 

expeditious period in which states can 

create and submit a plan per the EPA’s 

corresponding EGs that is both 

comprehensive and legally sound. In 

considering the appropriate timeline, 

the EPA has evaluated data from 

previously implemented EGs and the 

statutory deadlines and data from 

analogous programs (e.g., CAA sections 

129 and 189). We have also considered 

comments that some of the requirements 

the EPA had proposed for subpart Ba 

would require additional time to 

implement, as well as comments 

asserting that certain states need up to 

36 months to complete their 

administrative and legislative processes. 

While a reasonable state plan submittal 

timeline must provide states sufficient 

time to develop and submit plans that 

comport with the applicable 

requirements, the EPA also believes that 

state processes should be able to 

accommodate an 18-month timeline 

because the CAA already contains 

numerous deadlines that require SIP 

submissions to be developed and 

submitted to the Agency within 18 or 

fewer months. Thus, this finalized 

timeline should provide states 

reasonable time to adopt and submit 

approvable plans, and is also 

sufficiently expeditious to protect 

against significant adverse impacts to 

health and welfare resulting from 

foregone emission reductions during the 

state planning process. Providing states 

sufficient time to develop feasible 

implementation plans for their 

designated facilities that adequately 

address public health and 

environmental objectives also ultimately 

helps ensure more timely 

implementation of an EG, and therefore 

achievement in actual emission 

reductions, than would an unattainable 

deadline. Because 18 months is an 

expeditious time period, it follows that 

the EPA has appropriately considered 

the potential impacts to public health 

and welfare associated with this 

extension of time by providing no more 

time than the states reasonably need to 

ensure a plan is comprehensive and 

timely. 

The EPA is also finalizing the 

proposed amendment to 40 CFR 

60.27a(a) replacing the word ‘‘shorten’’ 

with ‘‘amend’’. The applicability 

provision at 40 CFR 60.20a(a)(1) states 

that ‘‘each emission guideline may 

include specific provisions in addition 

to or that supersede requirements of this 

subpart.’’ However, the existing 

provision in 40 CFR 60.27a(a) only 

provides for the Administrator to 

‘‘shorten the period for submission of 

any plan or plan revision or portion 

thereof.’’ To make these two provisions 

consistent in light of the timelines for 

plan submission finalized in this action, 

the EPA is replacing the word ‘‘shorten’’ 

with ‘‘amend.’’ One commenter opposed 

the amendment stating there is no 

regulatory certainty for the state in state 

plan submittal if the Administrator can 

simply change the timeline as he deems 

necessary. However, the appropriate 

timeline would undergo notice and 

comment rulemaking as the EG is 

proposed and finalized so that states 

would have sufficient notice of the 

timeline. To the extent the EPA 

considers deviating from this 18-month 

timeframe in promulgating an EG in the 

future, the EPA will consider the public 

health and welfare impacts associated 

with extending the state plan 

submission timeline, consistent with the 

D.C. Circuit’s direction in ALA. 

The EPA is also finalizing two 

amendments to 40 CFR 60.28a(a), which 

addresses plan revisions by the state. 

First, the EPA is finalizing the proposed 

clarification that meaningful 

engagement requirements apply to any 

significant plan revision by the state. 

Second, the EPA is finalizing revisions 


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24 ‘‘Docket_memo_outlining_proposed_changes_

to_regulatory_text.pdf,’’ available at https://

www.epa.gov/stationary-sources-air-pollution/ 

adoption-and-submittal-state-plans-designatedfacilities-40-cfr, as well as Docket ID No. EPA–HQ– 

OAR–2021–0527–0002. 25The EPA’s response to comments that the state 

plan submission timelines should accommodate 

every state’s unique administrative and legislative 

processes is also relevant here and is provided 

elsewhere in this section of the preamble. 

to the timeline for state plan revisions 

required in response to a revised 

emission guideline. At proposal, the 

EPA indicated in the revised regulatory 

text that it was proposing to shorten the 

timeline for state plan revisions in this 

specific circumstance from three years 

to 12 months.24 The EPA received 

comments on this proposed revision 

asserting that the same process-related 

challenges that apply to initial state 

plan submissions, including conducting 

meaningful engagement and RULOF 

procedures and working through states’ 

administrative and legislative processes, 

also apply to state plan revisions. 

Commenters requested that the EPA 

extend the timeline for state plan 

revisions in response to revised 

emission guidelines; one commenter 

specifically requested that the EPA 

leave it at 36 months. However, the EPA 

anticipates that, in most instances, plan 

revisions required in response to a 

revised emission guideline would be 

narrower in scope than the initial state 

plan and would not require states to 

reevaluate standards of performance or 

conduct significant new analysis. For 

example, the EPA may revise an 

emission guideline to provide for 

additional or updated monitoring or 

compliance protocols or to clarify 

applicability provisions. In such 

instances, the full period of time 

provided for initial state plan 

development and submission would not 

be necessary.25 Thus, the EPA believes 

it is reasonable to set a default timeline 

for the submission of state plan 

revisions in these general implementing 

guidelines that is shorter than the 

timeline for initial state plan 

submission. Because the EPA is 

providing an additional three months 

for state plan submission in this final 

rule relative to the proposed timeline 

(18 months versus 15 months), it is 

finalizing a timeline for the submission 

of state plan revisions in response to a 

revised emission guideline of fifteen 

months, which is also three months 

longer than the twelve months 

proposed. Additionally, in recognition 

that some state plan revisions in 

response to a revised emission guideline 

may in fact be more complex or 

necessitate additional analysis or 

rulemaking, the EPA is finalizing the 

provision at 40 CFR 60.28a(a) to allow 

the Agency to determine a different 

timeline for the submission of revised 

state plans, which it will provide in the 

revised emission guideline. 

2. Timeline for the EPA To Determine 

Completeness of State Plans 

Once a state plan has been submitted 

to the EPA, the EPA reviews the plan for 

‘‘completeness’’ to determine whether it 

includes certain elements necessary to 

ensure that the EPA can substantively 

evaluate the plan. The EPA determines 

completeness by comparing the state’s 

submission against the administrative 

and technical criteria specified in 

subpart Ba to determine whether the 

submission contains the specified 

elements (see 40 CFR 60.27a(g)(2) for 

completeness criteria). The timeline to 

make completeness determinations in 

the version of subpart Ba the EPA 

promulgated in 2019 mirrored the 

language for SIPs in CAA section 

110(k)(1)(B): ‘‘Within 60 days of the 

Administrator’s receipt of a plan or plan 

revision, but no later than 6 months 

after the date, if any, by which a State 

is required to submit the plan or 

revision, the Administrator shall 

determine whether the minimum 

criteria [for completeness] have been 

met.’’ Like CAA section 110(k)(1)(B), 

subpart Ba also provided that a state 

plan would be deemed complete by 

operation of law if the EPA had not 

made an affirmative determination by 

the date 6 months after receipt of the 

plan submission. 40 CFR 60.27a(g)(1). 

After a state plan is deemed complete 

through either an affirmative 

determination or by operation of law, 

the EPA will act on the state plan 

submission through notice-andcomment rulemaking. The timeline for 

the EPA to act on a state plan 

submission runs from the date a 

submission is deemed complete; more 

on this timeline can be found in section 

III.A.3. of this preamble. 

If a state plan submission does not 

contain the elements required by the 

completeness criteria, the EPA would 

find that the state has failed to submit 

a complete plan and notify the state 

through a letter. The determination of 

incompleteness treats the state as if the 

state has made no submission at all. The 

determination that a submission is 

incomplete and that the state has failed 

to submit a plan is ministerial in nature. 

As part of the EPA’s overall effort to 

set implementation timelines under 

CAA section 111(d) that are as 

expeditious as possible, the EPA 

proposed to revise the timing element of 

the completeness review at 40 CFR 

60.27a(g)(1). In light of the ministerial 

nature of the completeness 

determination, the EPA proposed a 

maximum of 60 days from receipt of the 

state plan submission for the EPA to 

make a determination of completeness. 

The EPA additionally proposed that any 

state plan or plan revision submitted to 

the EPA that has not received a 

completeness determination within 60 

days of receipt, shall on that date be 

deemed, by operation of law, to meet 

the completeness criteria, which will 

trigger the EPA’s obligation to take 

substantive action on the state plan. 

Sixty days provides an expeditious 

timeframe for the EPA to evaluate state 

plans for completeness and to notify the 

states of the determination. Because the 

EPA may be required to evaluate up to 

50 state plans during this period, in 

addition to plans submitted by 

territories and tribes, the EPA explained 

at proposal that it did not find that this 

timeframe could reasonably be 

shortened any further. 

While most commenters supported 

the 60-day completeness period, some 

commenters expressed concern that a 

state plan that is automatically deemed 

complete by operation of law as of the 

allotted 60 days could cause 

unnecessary turbulence in state plan 

implementation if the plan is later 

disapproved by the EPA due to missing 

information. Other commenters noted 

that if a plan is determined to be 

incomplete, a 60-day period will not 

allow states sufficient time to correct the 

deficiency and submit a complete plan. 

First, the EPA notes that the 

completeness determination is 

ministerial in nature and does not affect 

the Agency’s subsequent responsibility 

and authority to substantively review a 

state plan submission against the 

requirements of the Act and applicable 

regulations, including this subpart Ba 

and the relevant EG. That is, a 

determination that a state plan is 

complete does not signify that it 

necessarily satisfies the substantive 

requirements. The commenters fail to 

explain how deeming a state plan 

submission complete by operation of 

law, in this case after 60 days, and later 

finding it does not satisfy an applicable 

requirement is a new phenomenon or 

would cause unnecessary turbulence in 

state plan implementation. Rather, a 

shorter period for deeming plans 

complete by operation of law would be 

less disruptive than a longer period in 

this instance because the EPA will 

complete its substantive evaluation of 

the plan sooner and the state will have 

notice earlier on of any deficiencies. 

Additionally, because states may submit 

plan revisions at any time, states may 


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26The deadlines for the EPA action under subpart 

Ba would apply to any state plan submission 

regardless of when it is submitted. 

work collaboratively with the EPA on 

any portions of a plan identified as 

being deficient during both the 

completeness determination period and 

the period for the EPA’s substantive 

review of the plan. Thus, again, a 

shorter completeness determination 

period that includes a cutoff for 

deeming submissions complete by 

operation of law merely keeps the state 

plan review process moving 

expeditiously and does not foreclose 

any state opportunities to correct or 

supplement submissions at any point in 

the EPA’s review process. 

Moreover, the EPA intends to review 

for completeness as soon as possible 

after submittal. Although the EPA 

believes that it will be able to provide 

a timely completeness determination for 

most if not all state plan submissions, 

providing for completeness through 

operation of the law will help ensure 

that the EPA’s action on state plans does 

not significantly delay plan processing 

or implementation. 

The EPA is therefore finalizing the 

completeness provision at 40 CFR 

60.27a(g)(1) as proposed. The EPA notes 

that if the EPA determines a plan is 

incomplete, the EPA is required to 

promulgate, through notice-andcomment rulemaking, a Federal plan. 

See sections III.A.4. and III.B. for the 

discussion and final amendments 

associated with the timeline and triggers 

of the Federal Plan respectively. If a 

state submits a plan prior to the state 

plan submission deadline and the EPA 

also makes a determination that the plan 

is incomplete prior to that deadline, the 

EPA will treat the state as if the state has 

made no submission at all, but this 

determination does not yet trigger 

further action by the EPA. Instead, 

because the state still has an 

opportunity to submit a complete plan 

before the state plan submission 

deadline, the EPA’s authority to 

promulgate a Federal plan is only 

triggered if the state fails to timely 

submit a new plan to replace the 

incomplete plan by the state plan 

deadline. 

3. Timeline for the EPA’s Action on 

State Plans 

After a state plan has been determined 

to be complete or is deemed complete 

by operation of law, CAA section 111(d) 

provides that the EPA must evaluate 

whether the plan is ‘‘satisfactory’’; that 

is, whether the components of the plan 

meet all the requirements of the statute, 

these implementing regulations, and the 

corresponding EG. The EPA does so by 

evaluating a plan (or plan revision) to 

determine whether the plan or plan 

revision is approvable, in part or in 

whole (see section III.D.1. of this 

preamble for discussion on partial plan 

approvals), through a notice-andcomment rulemaking process. After the 

EPA proposes an action on a state plan 

submission (e.g., approval, partial 

approval/partial disapproval, 

disapproval) and reviews comments on 

the proposed action, the EPA will 

finalize its action on the plan. If the EPA 

approves a state plan, the standards of 

performance and other components of 

that state plan become federally 

enforceable. If the state plan is 

disapproved, in part or in whole, the 

EPA is obligated to promulgate a 

Federal plan for designated facilities 

within the state that were covered by 

the disapproved portions of the plan 

(see section III.A.4. of this preamble 

below for the EPA’s timeline to publish 

a Federal plan). 

Subpart B requires the EPA to take 

action on applicable state plans (e.g., 

approve or disapprove) within 4 months 

after the date required for submission. 

40 CFR 60.27(b). In the development of 

subpart Ba, the EPA contended that 4 

months was an inadequate time to 

review and take action on state plans 

and therefore instead provided a 

deadline of 12 months for final action 

on a state plan (mirroring the maximum 

time permitted under CAA section 

110(k)(1)(2) for the EPA’s action on 

complete SIPs). 84 FR 32520, July 8, 

2019. In the ALA decision, the D.C. 

Circuit vacated this revised timeline in 

subpart Ba on the basis that the EPA did 

not adequately justify the extended 

timeframes and did not consider the 

public health and welfare impacts of 

extending the implementation times. As 

is discussed below, the EPA has in this 

rulemaking closely evaluated the 

process, steps, and timeframes for the 

EPA to substantively review and act 

upon each state plan submission 

through a public notice-and-comment 

rulemaking process. After considering 

the time anticipated to be necessary for 

generally expeditious EPA action on 

state plans, the EPA again proposed that 

it must take final action on a state plan 

or plan revision submission within 12 

months after a plan is determined to be 

complete or becomes complete by 

operation of law.26

In the notice of proposed rulemaking, 

the EPA explained that the first step it 

takes once a state plan submittal has 

been deemed ‘‘complete’’ under 40 CFR 

60.27a(g) is for an intra-agency 

workgroup to review the plan 

components to determine whether they 

conform to the applicable regulatory 

requirements. The workgroup may 

require a broad range of expertise in 

legal, technical, and policy areas, 

potentially including attorneys, 

engineers, scientists, economists, air 

monitoring experts, health and welfare 

analysts, and/or policy analysts from 

across a variety of the EPA programs. 

After review and coordination, the 

workgroup then develops 

recommendations for approval or 

disapproval of each plan component 

and presents them to Agency decisionmakers for review. Once the Agency 

completes its internal decision-making 

process, the workgroup proceeds to 

prepare a written notice of proposed 

rulemaking. The notice of proposed 

rulemaking contains the EPA’s legal, 

policy, and technical bases for its 

proposed action on a state plan 

submission, which must be thoroughly 

developed and explained in writing to 

provide clear and concise information 

and reasoning to support the public in 

understanding the Agency’s decision 

and the justification for that decision, 

and so that the public may provide 

informed comments on the proposal. 

The EPA may further develop technical 

support documents as record support 

for the proposal. The draft proposed 

rulemaking and any record support then 

undergo a multi-layered review process 

across the EPA offices and levels of 

management before being processed for 

signature. The process to evaluate the 

state plan, draft a proposed action on a 

CAA section 111(d) state plan, and get 

the proposed action edited, reviewed, 

and signed typically requires a 

minimum of between 6 to 8 months to 

complete. The signed notice of proposed 

rulemaking is then submitted for 

publication in the Federal Register, 

which may require several weeks of 

review and processing prior to 

publication. 

The publication of the proposed 

rulemaking triggers the start of a public 

comment period of at least 30 days with 

possible extension, if requested by 

commenters. Because of the types of 

sources and pollutants regulated under 

CAA section 111(d), the EPA reasonably 

anticipates that many of its proposed 

actions on state plans will garner 

significant public interest from 

individuals, industry, states, and 

environmental and public health 

advocates. After completion of the 

comment period, the EPA then reviews 

all comments and determines whether, 

based on any information provided by 

the comments, it should alter its 

proposed action or further augment the 

legal, policy, and technical rationales 


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27While the EPA would have the discretion to act 

on a state’s submission more quickly than 12 

months where specific circumstances allow (e.g., 

where there are no public comments on the 

proposed action), the EPA does not believe that it 

would be reasonably possible to act significantly 

more quickly than 12 months in most cases. 

supporting that action. Comments 

received on a proposed action may 

include technical information that was 

not available to the EPA at the time of 

proposal. In the event technical data are 

received as part of comments on the 

proposed action, the EPA would then be 

required to review the new data and 

evaluate whether and how it should 

affect the EPA’s proposed conclusions 

regarding the state plan. If a substantive 

comment is raised that merits 

reconsideration of the EPA’s proposed 

action, the EPA may determine that it is 

necessary to revise and repropose its 

action on the state plan or it may go to 

the state for more information to help 

the Agency determine how to proceed. 

Once this review of comments is 

complete, the workgroup drafts and 

presents updated recommendations for 

action for internal review and 

consideration by Agency decisionmakers. Once the Agency completes its 

internal decision-making process, the 

workgroup then drafts a notice of final 

rulemaking on the plan submission, 

which includes responses to comments, 

any necessary record support, and may 

also include final regulatory text. The 

draft final action is then reviewed by 

senior management and other interested 

EPA offices within the Agency prior to 

signature of the final rulemaking 

approving or disapproving, in whole or 

in part, a state plan. It is reasonable to 

permit at least 4 to 7 months for 

evaluation of the comments received, 

any necessary technical analysis, 

decision-making, and drafting and 

review of the final action. 

The duration of each step in this 

deliberative process varies. The amount 

of time the EPA needs to review a state 

plan submission and the time it needs 

to finalize a notice of proposed 

rulemaking depends in part on the 

plan’s complexity and the nature of the 

technical, policy, and legal issues that it 

implicates. For example, a state plan 

submission that includes standards of 

performance for dozens of facilities on 

different compliance schedules would 

be more complex and time consuming 

to review than a plan that simply 

establishes standards of performance 

reflecting the presumptive level of 

stringency for all sources. Similarly, the 

amount of time needed to respond to 

comments and issue a final rulemaking 

depends in part on the number and type 

of comments received on the EPA’s 

proposed rulemaking. Additionally, the 

EPA reasonably anticipates that it will 

be required to review multiple plan 

submissions at a given time, and these 

phases of review for a given plan are 

impacted by the EPA’s review of other 

state plan submissions, as the EPA will 

need to assure its review across multiple 

plans and regional offices is consistent 

from a legal, technical, and policy 

perspective. 

While some commenters supported 12 

months as an expeditious timeframe for 

the EPA review and action on state plan 

submittals, several noted that 12 months 

may be insufficient. These commenters 

asserted that the EPA must 

meaningfully evaluate and take action 

on a state plan and a 12-month 

timeframe may be too short for this 

process. However, as detailed in the 

discussion above, the EPA has a 

mapped out the time necessary to take 

action on a generic plan submission and 

believes that 12 months is the most 

expeditious and therefore the most 

appropriate period to provide for these 

generally applicable implementing 

regulations. Additionally, the EPA has 

completed hundreds of actions on CAA 

section 110 SIPs within 12 months over 

the past 4 years. Given that the EPA may 

choose to supersede the requirements of 

subpart Ba as necessary in an individual 

EG, we believe that providing the 

shortest period here is consistent with 

considering health and welfare impacts 

by designing timelines to achieve state 

plan implementation as expeditiously as 

reasonably possible. 

The EPA is therefore finalizing as 

proposed 40 CFR 60.23a(b) to provide 

that it will take action on a state plan 

or plan revision within 12 months of a 

determination of a complete plan 

pursuant to 40 CFR 60.27a(g). This is a 

reasonably expeditious timeframe to 

accommodate the EPA action on a state 

plan or plan revision submission and 

the considerations described above, 

while ensuring that an EG is 

expeditiously implemented. The 

process and steps described in this 

action highlight the fact that it would be 

unreasonable, if not impossible, to 

accomplish all of the steps in a legally 

and technically sound manner within a 

4-month timeframe as required under 

subpart B. Particularly, any proposed 

action by the EPA has to be open for 

public comment for at least 30 days, and 

therefore the 4-month timeline provided 

in subpart B only gave the EPA 3 

months to do the substantive work of 

both the proposed and final actions, 

including evaluating the state plan 

submission, drafting preamble notices, 

responding to comments, and 

developing record support at both the 

proposed and final action stages. A 12- 

month timeframe after a plan is 

determined to be complete more 

reasonably accommodates the process 

and steps described in this action.27

As explained at proposal, the EPA 

recognizes that the court in ALA faulted 

the Agency for failing to consider the 

potential impacts to public health and 

welfare associated with extending 

planning deadlines. The EPA does not 

interpret the court’s direction to require 

a quantitative measure of impact, but 

rather consideration of the importance 

of the public health and welfare goals of 

CAA section 111(d) when determining 

appropriate deadlines. Because 12 

months is an adequate period of time in 

which the EPA can both expeditiously 

act on a plan submission and ensure 

that its action is technically and legally 

sound, it follows that the EPA has 

appropriately considered the potential 

impacts to public health and welfare 

associated with this extension of time 

by providing no more time than the EPA 

reasonably needs to ensure a plan 

submission contains appropriate and 

protective emission reduction measures. 

If the EPA does not have adequate time 

to evaluate a state plan submission, its 

ability to ensure the plan contains 

appropriate measures to satisfactorily 

implement and enforce the standards 

necessary to comply with the EG may be 

compromised, which would in turn 

compromise the EPA’s ability to ensure 

that the public health and welfare 

objectives of the EG are satisfied. 

Although several commenters noted that 

the review of some plans may require a 

more in depth analysis, the EPA 

believes 12 months is a both reasonable 

and expeditious timeframe to evaluate 

and act on most state plans. 

Accordingly, in order to ensure that the 

public health and welfare objectives of 

CAA section 111 are timely realized, 

and consistent with the direction in 

ALA, the EPA does not believe it would 

be appropriate to finalize a timeframe 

longer than 12 months for the EPA 

action on state plans. 

4. Timeline for the EPA To Promulgate 

a Federal Plan 

CAA section 111(d)(2) provides that 

the EPA has the same authority to 

prescribe a Federal plan for a state that 

fails to submit a satisfactory plan as it 

does for promulgating a FIP under CAA 

section 110(c). Accordingly, the EPA’s 

obligation to promulgate a Federal plan 

is triggered in three situations: where a 

state does not submit a plan by the plan 


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28The EPA has discretion to address its obligation 

to promulgate a Federal plan in a variety of ways 

for states that do not have an approved state plan. 

For example the EPA may initially promulgate a 

single Federal plan that applies to all appropriate 

states and then update that Federal plan as 

necessary to accommodate the inclusion of other 

states that trigger the need for a Federal plan in the 

future (e.g., a Federal plan that applies to states that 

fail to submit a plan can be updated to include 

applicability for states that later have a plan 

disapproved); or the EPA may promulgate separate 

Federal plans each time its authority to do so has 

been triggered (e.g., the EPA will promulgate a 

Federal plan for all states that fail to submit a plan 

and another Federal plan for all states that have 

their plan disapproved). 

29CAA section 179 provides that sanctions 

should be applied in states that fail to submit 

approvable SIPs for certain specified requirements 

for NAAQS implementation. The EPA has not 

promulgated any similar sanctions provisions 

governing the submission of state plans pursuant to 

section 111(d). 

30The EPA reviewed the information available in 

40 CFR part 62 associated with the promulgation of 

Federal Plans under CAA section 111(d). The 

supporting information reviewed is available at 

Docket ID No. EPA–HQ–OAR–2021–0527. Under 

the provisions of CAA section 111 and subpart B, 

the EPA promulgated Federal plans for municipal 

solid waste landfills EG 40 CFR part 60, subpart Cc 

(Federal plan codified at 40 CFR part 62, subpart 

GGG) and municipal solid waste landfills EG 40 

CFR part 60, subpart Cf (Federal plan codified at 40 

CFR part 62, subpart OOO). 

The EPA also reviewed information available in 

40 CFR part 62 associated with the promulgation of 

Federal Plans under CAA 129. The supporting 

information reviewed is available at Docket ID No. 

EPA–HQ–OAR–2021–0527. Under the provisions of 

CAA sections 111 and 129 and subpart B, the EPA 

has promulgated Federal plans for large municipal 

waste combustors EG 40 CFR part 60, subpart Cb 

(Federal plan codified at 40 CFR part 62, subpart 

FFF); small municipal waste combustors EG 40 CFR 

part 60, subpart BBBB (Federal plan codified at 40 

CFR part 62, subpart JJJ); hospital, medical, and 

infectious waste incinerators EG 40 CFR part 60, 

subpart Ce (Federal plan codified at 40 CFR part 62, 

subpart HHH); commercial and industrial solid 

waste incinerators EG 40 CFR part 60, subpart 

DDDD (Federal plan codified at 40 CFR part 62, 

subpart III) and sewage sludge incinerators EG 40 

CFR part 60, subpart MMMM (Federal plan codified 

at 40 CFR part 62, subpart LLL). 

submission deadline; where the EPA 

determines a portion or all of a state 

plan submission did not meet the 

completeness criteria and the time 

period for state plan submission has 

elapsed and, therefore, the state is 

treated as having not submitted a 

required plan; and where the EPA 

disapproves a state’s plan. 40 CFR 

60.27a(c). The EPA is finalizing as 

proposed the revisions to 40 CFR 

60.27a(c) providing that the Agency will 

promulgate a Federal plan at any time 

within 12 months of any of the triggers 

in § 60.27a(c)(1) and (2) (see section 

III.B. of this preamble for discussion).28

The EPA is obligated to promulgate a 

Federal plan for states that have not 

submitted a plan by the submission 

deadline. Once the obligation to 

promulgate a Federal plan is triggered, 

it can only be tolled by the EPA’s 

approval of a state plan. If a Federal 

plan is promulgated, a state may still 

submit a plan to replace the Federal 

plan. A Federal plan under CAA section 

111(d) is a means to ensure timely 

implementation of EGs, and a state may 

choose to accept a Federal plan for their 

sources rather than submit a state plan. 

While the EPA encourages states to 

timely submit plans for EGs, there are 

no sanctions associated with failing to 

timely submit an approvable plan or 

with the implementation of a Federal 

plan.29

The original implementing 

regulations in subpart B provided the 

EPA with 6 months to promulgate a 

Federal plan once its obligation to do so 

was triggered. 40 CFR 60.27(d). When 

the EPA promulgated subpart Ba in 

2019, it concluded that this amount of 

time was insufficient and consequently 

extended the time for the EPA to 

promulgate a Federal plan to 24 months, 

mirroring the timeframe permitted for 

promulgation of a FIP under CAA 

section 110. 84 FR 32520, July 8, 2019. 

In the ALA decision, the D.C. Circuit 

vacated this revised timeline in subpart 

Ba on the basis that the EPA did not 

adequately justify the extended 

timeframe and did not consider the 

health and welfare impacts of extending 

the implementation timeframe. 

At proposal, the EPA reevaluated the 

process, steps, and timeframes for the 

EPA to promulgate a Federal plan 

through a public notice-and-comment 

rulemaking process and proposed a 12- 

month timeframe to promulgate a 

Federal plan once its obligation to do so 

is triggered.30 As explained in the notice 

of proposed rulemaking, a Federal plan 

must meet the requirements of CAA 

section 111(d) and therefore contain the 

same components as a state plan, 

namely standards of performance for 

designated facilities and measures that 

provide for the implementation and 

enforcement of such standards. CAA 

section 111(d)(2)(B) also explicitly 

requires the EPA to consider RULOF in 

promulgating a standard of performance 

under a Federal plan. Additionally, 

Federal plans containing standards of 

performance are subject to the 

procedural requirements of CAA section 

307(d), such as the requirements for 

proposed rulemaking and opportunity 

for public hearing. CAA section 

307(d)(1)(C). The EPA’s regulations at 

40 CFR 60.27a implement these various 

statutory requirements and contain 

general regulatory requirements for the 

EPA’s promulgation of a Federal plan. 

The process, and steps for the EPA to 

promulgate a Federal plan consistent 

with these applicable requirements is 

described in the following paragraphs. 

Once the EPA’s obligation to 

promulgate a Federal plan is triggered, 

the EPA establishes an intra-agency 

workgroup to develop the rulemaking 

action to address that obligation. The 

workgroup first develops 

recommendations for the components of 

the Federal plan to be proposed, and on 

legal, policy, and technical rationales 

that support the recommendations. 

These components are identified in 

subpart Ba as well as in the 

corresponding EG and are generally the 

same as those required for a state plan. 

One of these fundamental components 

is the determination of standards of 

performance for designated facilities. 

Based on the requirements of CAA 

sections 111(d) and 111(a)(1), these 

standards must generally reflect the 

degree of emission limitation achievable 

through application of the BSER as 

determined by the EPA as part of the 

EG. Depending on the form of the BSER 

and the degree of emission limitation in 

a particular EG, the EPA may need to do 

additional work to calculate standards 

of performance that reflect this level of 

stringency. For example, an EG may 

translate the degree of emission 

limitation into a presumptive standard 

in the form of numerical emission rates, 

which a Federal plan could simply 

adopt as the requisite standards of 

performance. However, if an EG 

provides the degree of emission 

limitation in a form other than 

presumptive numerical standards, and 

the EPA may need to calculate 

appropriate standards of performance in 

the context of a Federal plan. Further, 

CAA section 111(d)(2) requires the EPA 

to consider RULOF for sources in the 

source category in setting standards of 

performance as part of a Federal plan 

which requires the EPA to identify 

whether the remaining useful lives of 

relevant designated facilities, among 

other appropriate factors, merit the EPA 

establishing different standards of 

performance for those facilities. The 

development of a Federal plan may also 

necessitate that the EPA determine 

appropriate testing, monitoring, 

reporting, and recordkeeping 

requirements to implement the standard 

if the EG does not provide presumptive 

requirements to address those aspects of 

implementation. Further, the EPA will 

need to consider associated compliance 

times for designated facilities in 

circumstances where they are not 

provided by an EG, or in cases where a 

standard of performance is adjusted to 

account for RULOF. There may also be 

situations where IoPs are warranted, 


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and the EPA will correspondingly need 

to identify and determine the 

appropriate IoPs. The development of a 

Federal plan with these components, or 

of significant revision to a Federal plan, 

will also include elements of 

meaningful engagement, as finalized in 

this action including revision to section 

40 CFR 60.29a and as further described 

in section III.C. of this preamble. 

Once the recommendations for each 

component are developed, the 

workgroup presents them to Agency 

decision-makers for review. After the 

Agency completes its internal decisionmaking process, the workgroup 

proceeds to prepare a written notice of 

proposed rulemaking. The proposal 

must include the following elements, as 

required by CAA section 307(d)(3): the 

factual data on which the proposed 

rulemaking is based; the methodology 

used in obtaining the data and in 

analyzing the data; and the major legal 

interpretations and policy 

considerations underlying the proposed 

rulemaking. These elements must be 

thoroughly developed and explained in 

the proposal to meaningfully provide 

the public adequate information to 

comment on the proposal. The EPA may 

further develop a technical support 

document as record support for the 

proposal. 

The draft proposed rulemaking and 

any record support are then reviewed by 

the relevant EPA offices and processed 

for signature. The signed notice of 

proposed rulemaking is then submitted 

for publication in the Federal Register. 

To develop the proposed Federal plan 

rulemaking, establish unique standards 

for RULOF, allow review of materials by 

senior management, go through an 

interagency review process and have the 

package signed typically requires a 

minimum of between six to nine months 

to complete. 

As previously noted, the EPA’s 

promulgation of a Federal plan is 

subject to the requirements of CAA 

section 307(d), which includes 

providing the public with an 

opportunity to provide an oral 

presentation at a public hearing. CAA 

section 307(d)(5). The Federal Register 

Act requires the EPA to provide 

sufficient notice of a public hearing, 

which (in the absence of a different time 

specifically prescribed by the relevant 

Act of Congress) is satisfied if the EPA 

provides at least 15 days’ notice. 44 

U.S.C. 1508. Section 307(d)(5) of the 

CAA further provides that the EPA must 

keep the record for the proposed action 

open for public comment for 30 days 

after any public hearing for the 

submission of rebuttal and 

supplemental information. Because the 

EPA reasonably expects to provide 

notice of the required public hearing at 

the time its proposed action is 

published in the Federal Register, in 

order to allow for both a 15-day notice 

of the public hearing and a subsequent 

30-day comment period on the open 

record, the EPA should allow for at least 

45 days for public comment on the 

notice of proposed action. 

As with state plans, because of the 

types of sources and pollutants 

regulated under CAA section 111(d), the 

EPA reasonably anticipates that many of 

its proposed actions on a Federal plan 

will garner significant public interest 

from individuals, industry, states, and 

environmental and public health 

advocates. After completion of the 

comment period, the EPA then reviews 

all comments and determines whether, 

based on any comment, it should alter 

any components of the proposed 

Federal plan, or further augment the 

legal, policy, and technical rationales 

supporting that proposed action. 

Additionally, in the EPA’s experience, 

comments may include technical 

information that was not in front of the 

Agency at the time of proposal. In the 

event technical data are received as part 

of comments on the proposed action, 

the EPA would then be required to 

review the new data and evaluate 

whether and how it should affect the 

EPA’s proposed Federal plan. If a 

substantive comment is raised that 

merits reconsideration of any 

component in the proposed Federal 

plan, the EPA would need to repropose 

the plan. 

Once this review of comments is 

complete, the workgroup drafts and 

presents updated recommendations for 

internal review and decision making. 

Once the Agency completes its internal 

decision-making process, the workgroup 

then drafts a notice of final rulemaking, 

which includes responses to comments 

and any necessary record support, and 

final regulatory text as the Federal plan 

directly regulates certain designated 

facilities. The draft final action is then 

reviewed by relevant offices within the 

Agency prior to signature of the final 

rule promulgating the Federal plan. The 

EPA typically anticipates that the 

process of reviewing comments 

received, making corresponding changes 

to the rulemaking, and promulgating the 

final Federal plan to be between 4 and 

8 months. 

The duration of each step in this 

deliberative process varies. The amount 

of time the EPA needs to develop, 

propose, and finalize a Federal plan 

depends in part of the plan’s complexity 

and the nature of the technical, policy, 

and legal issues that it implicates. For 

example, some states needing a Federal 

plan may have thousands, if not 

hundreds of thousands, of designated 

facilities for which the EPA will need to 

establish standards of performance and 

implementation measures, while other 

Federal plans may be significantly 

smaller in scale. Similarly, the amount 

of time needed to respond to comments 

and issue a final rule depends in part on 

the number and type of comments 

received on the EPA’s proposed 

rulemaking. Additionally, the EPA 

reasonably anticipates that it may need 

to promulgate a Federal plan for 

multiple states at a given time, which 

can amplify the amount of time and 

work needed. 

In response to this proposed timeline, 

several commenters asserted that the 

EPA should provide itself more than the 

proposed 12 months to promulgate a 

Federal plan, with some commenters 

noting additional time needed for the 

EPA to provide for meaningful 

engagement and consideration of 

RULOF. However, based on the 

assessment as presented in the 

preceding paragraphs, recognizing that 

much of the evaluation needed for 

promulgating a Federal plan will be 

performed by the EPA during 

development of the EG, considering the 

need for expeditious implementation of 

EGs, and noting that RULOF is expected 

to only be needed for certain limited 

circumstances, the EPA is finalizing the 

requirement that it promulgate a Federal 

plan within 12 months once its 

obligation to do so is triggered, i.e., 

either the date required for submission 

of a state plan (for states that fail to 

submit a complete plan) or the date the 

EPA disapproves a state’s plan. As with 

the other timelines in subpart Ba, the 

EPA may supersede the 12 month 

timeline for a Federal plan as 

appropriate depending on the 

circumstances of the applicable EG. 

The EPA also recognizes that some 

commenters stated that the EPA need 

not and should not wait for its Federal 

plan obligation to be ‘‘triggered’’ to 

begin developing such a plan. The EPA 

agrees that early development of the 

Federal plan, where possible before the 

EPA’s obligation is formally triggered, 

could provide the EPA with additional 

time to meet this deadline. The EPA 

notes that to further streamline the 

timeline associated to the issuance of a 

Federal plan, the EPA is also finalizing 

the proposed change to the trigger for 

the EPA’s obligation and timeline to 

provide a Federal plan for states that do 

not submit a timely plan. That 

discussion is found in section III.B. of 

this preamble. 


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31While the EPA would have the discretion to 

promulgate a Federal plan more quickly than 12 

months where specific circumstances allow (e.g., 

where there are no public comments on the 

proposed action), the EPA does not believe that 

would be reasonably possible to act significantly 

more quickly than 12 months in most cases. 

32 ‘‘Each plan shall include standards of 

performance and compliance schedules.’’ 40 CFR 

60.24a(a). 

33 65 FR 76380 (Dec 6, 2000). 

34 In promulgating Ba in 2019, the EPA specified 

that for ‘‘For those provisions that are being carried 

over from the existing implementing regulations 

into the new implementing regulations, the EPA is 

not intending to substantively change those 

provisions from their original promulgation and 

continues to rely on the record under which they 

were promulgated.’’ 84 FR 32520 (July 8, 2019). 

35Petitioners did not challenge, and the court did 

not vacate in ALA, the substantive requirement for 

or definition of increments of progress. 

Thus, the EPA is finalizing as 

proposed the revisions to 40 CFR 

60.27a(c) providing that the Agency will 

promulgate a Federal plan at any time 

within 12 months of any of the triggers 

in § 60.27a(c)(1) and (2). While retaining 

the authority to supersede this timeline 

in an EG if appropriate, the EPA has 

determined that 12 months reasonably 

accommodates the amount of time that 

the EPA needs to undertake the process, 

steps, and the considerations described 

above, while ensuring that an EG is 

expeditiously implemented. The 

process and steps described earlier that 

the EPA must be taken in promulgating 

a Federal plan highlight the fact that it 

would be unreasonable, if not an 

impossibility, to accomplish all of the 

steps in a legally and technically sound 

manner within a 6-month timeframe as 

required under subpart B.31

As with the EPA’s finalized timeline 

to act on state plan submissions, 12 

months is generally the period of time 

in which the EPA can both 

expeditiously complete a Federal plan 

and ensure it is technically and legally 

sound. Therefore, this time period 

considers potential impacts to public 

health and welfare by giving the EPA a 

reasonably expeditious timeframe to 

promulgate a Federal plan that contains 

appropriate and protective emission 

reduction measures. This is especially 

true in the context of a Federal plan, 

where there is otherwise no state plan 

in place that is adequately protective of 

public health and welfare. If the EPA 

does not have adequate time to 

promulgate a Federal plan, its ability to 

ensure the plan contains appropriate 

measures to satisfactorily implement 

and enforce the standards necessary to 

comply with the EG may be 

compromised, which would in turn 

compromise the EPA’s ability to ensure 

that the public health and welfare 

objectives of the EG are satisfied. 

The EPA notes that a state may submit 

a plan to replace a Federal plan, even 

after the state plan submission deadline. 

However, once the EPA’s authority and 

obligation to promulgate a Federal plan 

has been triggered, the act of a state 

submitting a plan alone does not 

abrogate the EPA’s authority or 

obligatory timeline to promulgate a 

Federal plan. Only an approved state 

plan can supplant an already 

promulgated Federal plan or abrogate 

the EPA’s responsibility to timely 

promulgate a Federal plan. Where a 

state submits a late plan, that may have 

the practical effect of concurrent 

timelines for promulgation of the 

Federal plan and the EPA’s action on 

that late state plan; the EPA is not 

obligated to act on a late state plan prior 

to promulgating a Federal plan (40 CFR 

60.27a(d)). 

5. Timeline for Increments of Progress 

(IoPs) 

As part of the EPA’s statutory 

responsibility to determine the degree of 

emission limitation achievable through 

application of the BSER and to include 

it in an EG, the EPA also determines in 

an EG ‘‘the time within which 

compliance with standards of 

performance can be achieved.’’ 40 CFR 

60.22a(b)(5). Accordingly, state plans 

must include both standards of 

performance for designated facilities 

and compliance schedules for achieving 

those standards of performance.32

In 1975, the EPA defined in subpart 

B ‘‘compliance schedule’’ as ‘‘a legally 

enforceable schedule specifying a date 

or dates by which a source or category 

of sources must comply with specific 

standards of performance contained in a 

plan or with any increments of progress 

to achieve such compliance.’’ In subpart 

B the EPA also defined ‘‘increments of 

progress’’ as steps to achieve 

compliance which must be taken by an 

owner or operator of a designated 

facility including: (1) submittal of a final 

control plan for the designated facility 

to the appropriate air pollution control 

agency; (2) awarding of contracts for 

emission control systems or for process 

modifications, or issuance of orders for 

the purchase of component parts to 

accomplish emission control or process 

modification; (3) initiation of on-site 

construction or installation of emission 

control equipment or process change; 

(4) completion of on-site construction or 

installation of emission control 

equipment or process change; and (5) 

final compliance. The EPA adopted 

these definitions without change when 

it promulgated subpart Ba in 2019. 

Subpart B requires that each state 

plan include emission standards and 

compliance schedules. 40 CFR 60.24a. 

In addition, subpart B specifies in 40 

CFR 60.24(e)(1) that any compliance 

schedule extending more than 12 

months from the date required for 

submittal of the plan must include 

legally enforceable increments of 

progress to achieve compliance for each 

designated facility or category of 

facilities. Unless otherwise specified in 

the applicable subpart, increments of 

progress must include, where 

practicable, each increment of progress 

specified in § 60.21(h) and must include 

such additional increments of progress 

as may be necessary to permit close and 

effective supervision of progress toward 

final compliance. The provision in 40 

CFR 60.24(e)(1) was amended in 2000.33

The 2000 amendments to 40 CFR 

60.24(e)(1) added the words ‘‘Unless 

otherwise specified in the applicable 

subpart’’ to the requirements associated 

with IoPs. The EPA described in the 

1999 proposal that the purpose of this 

amendment was to allow the EPA, in a 

specific subpart, discretion in the 

number of IoPs that a designated facility 

must meet. Without this amendment 

subpart B required designated facilities 

to meet all five IoPs specified in the IoP 

definition. In the 1999 proposal the EPA 

recognized that while for some 

categories of designated facilities the 

five increments are appropriate, all five 

IoPs may not be necessary to ensure 

compliance for other categories of 

designated facilities. Therefore, EPA 

proposed and finalized amendments to 

40 CFR 60.24(e) to allow discretion and 

flexibility in establishing IoPs for a 

particular subpart. 

In promulgating subpart Ba in 2019, 

the EPA largely carried over the 

requirement of subpart B at 40 CFR 

60.24(e)(1) in a new provision 40 CFR 

60.24a(d).34 However, to align the 

trigger of IoPs in 40 CFR 60.24a(d) to the 

updated timelines it was finalizing in 

subpart Ba, in 2019 the EPA adopted a 

timeframe trigger for IoPs of 24-months 

instead of the 12-months as in subpart 

B. Per the finalized 2019 subpart Ba 

provision at 40 CFR 60.24a(d), unless 

otherwise specified in the applicable 

subpart, any compliance schedule 

extending more than 24 months from 

the date required for submittal of the 

plan must include legally enforceable 

IoPs to achieve compliance for each 

designated facility or category of 

facilities. As discussed previously, the 

D.C. Circuit vacated the extended 

implementation timelines in subpart Ba, 

including the 24-months timeline trigger 

for IoPs in 40 CFR 60.24a(d).35


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To address the vacated timeline 

trigger of IoPs in 40 CFR 60.24a(d), the 

EPA proposed in 2022 that, unless 

otherwise specified in the applicable 

subpart, any compliance schedule 

extending more than 16 months from 

the date required for submittal of the 

plan must include legally enforceable 

IoPs to achieve compliance for each 

designated facility or category of 

facilities. The proposed 16-month 

trigger for IoPs overlapped with the 

EPA’s proposed 60-day completeness 

review following a state plan submittal 

and the proposed 12-month period for 

the EPA to review and take action on 

the state’s plan and would have further 

provided a 2-month buffer after the 

timeline for the EPA’s action on a state 

plan (occurring no later than 14 months 

after the plan submission deadline 

under these general implementing 

regulations). In the 2022 proposal the 

EPA recognized the proposed 16-month 

timeframe trigger for IoPs provided a 2- 

month time buffer between the EPA’s 

action on a state plan and the trigger of 

IoPs. As proposed, this 2-months buffer 

was less than both the 8 months 

previously provided by subpart B and 

the 6-month buffer provided by the 

vacated subpart Ba timeline. 

In response to the proposed 16-month 

IoPs timeframe trigger, several 

commenters asserted the proposed 2- 

month buffer from the time of the EPA’s 

action on a state plan to the trigger of 

IoPs is not practically workable. Some 

commenters argued that, assuming that 

there could be a required increment of 

progress right after the 16-months 

trigger and the EPA has 14 months to 

take final action on a state plan, the 

designated facilities would have only 

two months to comply with the 

requirement after it becomes federally 

enforceable. Other commenters 

similarly noted that if final compliance 

was required just after the 16-month 

trigger, designated facilities would 

similarly have only two months to 

complete any IoPs. The commenters 

explained that it is unduly burdensome 

for sources to expend resources on 

developing hypothetical final control 

plans and committing resources to 

construction projects that may 

ultimately be inconsistent with the 

EPA’s action on a state plan. Several 

commenters that opposed the 16- 

months proposed timeframe trigger for 

IoPs suggested that the EPA extend the 

trigger to more than 24-months, 

consistent with the previously vacated 

subpart Ba. Some commenters argued 

that 24 months is the minimum time 

necessary to develop control strategies, 

design plans, procure construction 

materials and/or equipment, and 

complete the installations often 

necessary for compliance. Other 

commenters suggested that a 10-month 

buffer from the EPA action on a state 

plan to the trigger for IoPs would also 

be acceptable and even preferred, 

should the EPA miss its approval 

deadlines. 

After consideration of comments and 

accounting for the discretion that EPA 

has in establishing IoPs in a particular 

EG, the EPA is extending the buffer 

associated with the trigger of IoPs from 

2 months to 6 months, so that, unless 

otherwise specified in the applicable 

subpart, any compliance schedule 

extending more than 20 months from 

the date required for submittal of the 

plan must include legally enforceable 

IoPs to achieve compliance for each 

designated facility or category of 

facilities. 

The EPA emphasizes that the timeline 

for the trigger for IoPs merely signals 

when the gap between state plan 

submission and final compliance is long 

enough that the EPA must consider 

whether IoPs are necessary. It is not the 

case that any EG with a final 

compliance date after the trigger for 

consideration of IoPs will necessarily 

require all of the increments listed in 40 

CFR 60.21a(h). The EPA is required, per 

40 CFR 60.22a(b)(4), to include within 

an EG ‘‘[i]ncremental periods of time 

normally expected to be necessary for 

the design, installation, and startup of 

identified control systems.’’ These 

incremental periods are determined 

within an EG through notice and 

comment rulemaking, providing an 

opportunity for appropriate 

consideration of the reasonable time 

needed for the designated facilities to 

meet the requirements associated with 

the pertinent standards of performance. 

As provided by subpart Ba, the EPA will 

determine in an individual EG whether 

IoPs are needed to achieve final 

compliance with the standards of 

performance and, if increments are 

needed, how many and the timeframes 

associated with compliance of such 

IoPs. However, the EPA also believes 

that the trigger requirement for IoPs 

should attach to plans that contain 

compliance periods that are longer than 

the period provided for the EPA’s 

review of such plans and in addition 

provide a reasonable buffer after the 

EPA has acted on such plans so that 

designated facilities could reasonably 

comply with required increments. After 

further consideration, the EPA believes 

that a default 2-month buffer between 

an EPA action on a state plan and a 

hypothetical compliance deadline for a 

full set of IoPs is not generally 

sufficient. 

In 2019, the EPA promulgated a 

trigger for IoPs of 24-months given that 

it was finalizing a period of up to 18 

months for its action on state plans (i.e., 

12 months from the determination that 

a state plan submission is complete, 

which could occur up to six months 

after receipt of the state plan). The 24- 

month period would have provided a 6- 

month buffer for designated sources to 

comply with any IoPs after the EPA 

acted on state plans. In this action, the 

EPA is finalizing a trigger for 

consideration of IoPs that provides the 

same buffer provided by the EPA in the 

2019 vacated increment of progress 

timeline trigger. The EPA believes a 6- 

month buffer is generally needed to 

appropriately balance ensuring 

designated facilities control emissions 

of harmful pollutants as expeditiously 

as reasonably possible with the need for 

designated facilities to have reasonable 

certainty regarding their federally 

enforceable regulatory compliance 

obligations with sufficient time before 

those obligations are due. In addition, 

the EPA determines that the 6-months 

buffer provides a reasonable time to 

come into compliance with any 

potential increment of progress when 

compliance date that extends more than 

20 months from the date required for 

submittal of the plan. Per the EPA’s 

assessment of the comments and in light 

of the ALA court decision, the EPA 

determines that a 6-month timeframe 

buffer before the trigger for requirements 

associated with IoPs provides is the 

most reasonable expeditious period of 

time associated with the requirements 

for IoPs in 40 CFR 60.24a(d). While 

some commenters argued more time is 

necessary to develop control strategies, 

design plans, procure construction 

materials and/or equipment, and 

complete the installations often 

necessary for compliance, the final 

requirements in subpart Ba does not 

express the EPA’s intent to require that 

states require designated facilities to 

complete all potential IoPs in a 6-month 

period. 

Several commenters also urged the 

EPA to link the timelines for IoPs to the 

date on which the EPA takes final action 

on a state plan, instead of with the state 

plan submittal deadline. However, given 

that there will typically be a single final 

compliance date specified in an EG but 

the dates on which the EPA takes final 

action on individual states plans are 

likely to be many and varied based on, 

inter alia, when each state plan was 

submitted to the Agency, such an 

approach would create unnecessary 

confusion about whether IoPs must be 


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36Note that this procedure does not address 

circumstances when the EPA promulgates a Federal 

plan for states whose plan is disapproved. In these 

circumstances, the state has submitted a plan so no 

finding of failure to submit is issued. The EPA’s 

obligation and timeline to promulgate a Federal 

plan in this instance arises from the EPA’s 

disapproval based on its conclusion that the state 

plan submission was unsatisfactory. 

implemented and potentially uneven 

application of the requirement for state 

plans to include IoPs. It could also 

create a perverse incentive for states to 

delay submission of their state plans. 

Additionally, the timeline for IoPs 

initiates from the state plan submittal 

deadline because it is the earliest 

instance when all standards of 

performance in all timely state plans 

will be enforceable. It is a requirement 

of state plans, when submitted, to be 

enforceable at the state level and thus 

all designated facilities subject to a 

standard of performance in a state plan 

will have assurance of their 

requirements at the state level and can 

start planning for compliance while the 

EPA reviews and acts on the state plan. 

The timeline for IoPs finalized in this 

action will ensure standards of 

performance are implemented as 

expeditiously as possible so that the 

intended emission reductions are 

achieved, and the public health and 

welfare are protected. 

B. Federal Plan Authority and Timeline 

Upon Failure To Submit a Plan 

CAA section 111(d)(2)(A) provides 

that the EPA has the same authority ‘‘to 

prescribe a plan for a State in cases 

where the State fails to submit a 

satisfactory plan as he would have 

under section 7410(c) of this title in the 

case of failure to submit an 

implementation plan.’’ The original 

implementing regulations in subpart B 

provide that the EPA is to ‘‘promptly 

prepare and publish proposed 

regulations setting for a plan, or portion 

thereof, for a State if:’’ a state fails to 

submit a plan within the time 

prescribed, the state fails to submit a 

plan revision within the time prescribed 

or the Administrator disapproves a state 

plan or plan revision or any portion 

thereof. 40 CFR 60.27(c). Subpart B 

further requires the EPA to promulgate 

the plan proposed under paragraph (c) 

‘‘within six months after the date 

required for submission of a plan or 

plan revision . . . unless, prior to such 

promulgation, the State has adopted and 

submitted a plan or plan revision which 

the Administrator determines to be 

approvable.’’ 40 CFR 60.27(d). 

In promulgating subpart Ba in 2019, 

the EPA incorporated language in the 

provisions associated with the Actions 

by the Administrator in 40 CFR 

60.27a(c) from CAA sections 

110(c)(1)(A) and 110(k)(1)(B) addressing 

the circumstances which trigger the 

EPA’s authority under CAA section 

111(d)(2) for promulgating a Federal 

plan. Specifically, in 2019 the EPA 

adopted language at 40 CFR 60.27a(c)(1) 

that requires the EPA to promulgate a 

Federal plan after it ‘‘[f]inds that a state 

fails to submit a required plan or plan 

revision or finds that the plan or plan 

revision does not satisfy the minimum 

criteria under’’ 40 CFR 60.27a(g), i.e., 

the completeness criteria (emphasis 

added). Pursuant to the amendments 

being finalized in this action, the EPA 

will be required, under 40 CFR 

60.27a(g), to determine whether 

completeness criteria have been met no 

later than 60 days after the date by 

which a state is required to submit a 

plan (see section III.A.2. of this 

preamble). These provisions under 

subpart Ba taken together would mean 

that, no later than 60 days after the state 

plan submission deadline has passed, 

the EPA must make a finding (often 

referred to as a ‘‘finding of failure to 

submit’’) as to whether any states have 

failed to submit a plan that meets the 

completeness criteria, and such finding 

is what triggers the EPA’s obligation and 

timeline to promulgate a Federal plan.36

At proposal, the EPA acknowledged 

that in the CAA section 110 context, it 

has not always timely met its obligation 

to issue a finding of failure to submit, 

which in turn delays the timing for 

when the EPA promulgates a FIP to 

achieve the necessary emission 

reductions. Accordingly, the EPA 

proposed to streamline the process in 

the subpart Ba context to ensure that the 

emission reductions anticipated by the 

EG are realized in a timely way through 

the promulgation of any necessary 

Federal plan. In particular, the EPA 

proposed revisions to 40 CFR 

60.27a(c)(1) consistent with the 

framework and requirements that have 

been effective in subpart B since 1975. 

As proposed the Administrator would 

issue a Federal plan if a state fails to 

submit a plan within the time 

prescribed without requiring the EPA to 

affirmatively issue a finding of failure to 

submit before the EPA’s obligation to 

issue a Federal plan is triggered. 

As explained in the notice of 

proposed rulemaking, as part of 

evaluating ways to streamline the steps 

leading to promulgation of a final 

Federal plan, the EPA considered the 

value and role of issuing findings of 

failure to submit in this process. A 

finding of failure to submit was 

intended to serve three purposes under 

subpart Ba, consistent with its purpose 

under CAA section 110: to notify the 

public of the status of state plan 

submissions (i.e., providing 

transparency to the process); to notify 

states that the EPA has not received a 

plan; and to formally start the clock for 

the EPA to promulgate a Federal plan. 

While these concepts may have some 

utility as part of the overall Federal plan 

development and implementation 

process, the EPA finds that in the CAA 

section 111(d) context there is minimal 

value in coupling the notification 

aspects of a finding of failure with the 

initiation of the clock for the EPA to 

promulgate a Federal plan. These 

aspects are not inextricably linked to 

one another in that nothing about a 

formal finding of failure to submit 

substantively informs the development 

of a Federal plan; the EPA has the 

information it needs to know which 

states have and have not submitted 

complete plans. By decoupling the 

timeline from the finding of failure to 

submit, the EPA’s obligation to 

promulgate a Federal plan can be 

triggered without the interim step and 

potential lag associated with issuing a 

formal finding of failure to submit 

notification. By removing this interim 

process, the EPA will be required to 

promulgate the Federal plan more 

expeditiously, and, in turn, overall 

implementation of the corresponding 

EG will be timelier. Finalizing this 

amendment is also consistent with the 

spirit of the ALA decision, where the 

D.C. Circuit emphasized the need for 

implementation timelines that consider 

potential impacts on public health and 

welfare. By expeditiously and efficiently 

promulgating a Federal plan and by 

removing an interim step of a finding of 

failure, the EPA is further addressing 

the potential impacts of implementation 

times on health and welfare. 

Some commenters requested that the 

EPA retain a separate ‘‘finding of failure 

to submit’’ action as the trigger for 

starting the timeline on a Federal plan. 

They note that the ‘‘finding of failure’’ 

provides notification to the states, 

regulated community, and public of the 

failure, as state submissions can be 

difficult to track. Commenters also note 

that the need to first provide the finding 

also provides additional time for the 

states to submit plans or revisions. One 

commenter noted that the EPA should 

retain the ‘‘finding of failure to submit’’ 

procedure and avoid establishing 

automatic deadlines for itself on a 

schedule that, based on past experience, 

it is almost certain to miss. 

First, the EPA notes that where a state 

has failed to timely submit a state plan, 

the absence of a state plan submission 

should be easy to track for the state, 


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37As discussed in section III.A.2., if a state 

submits a plan but that submission does not contain 

the elements required by the completeness criteria, 

the EPA would find that the state has failed to 

submit a complete plan and notify the state through 

a letter. That letter is for notification only and, 

although the EPA intends to issue such letters 

expeditiously, it does not start the clock for a 

Federal plan. 

38A significant state plan revision includes, but 

is not limited to, any revision to standards of 

performance or to measures that provide for the 

implementation or enforcement of such standards. 

regulated community, and public; 

many, if not all, states maintain public 

websites on which they document their 

submissions to the EPA. The EPA 

expects that notification and tracking 

capabilities will also generally be much 

improved through the use of electronic 

submittal (see section III.F. of this 

preamble) and increasing public access 

to online information. 

Second, the EPA stresses that the 

purpose of using a finding of failure to 

submit as the trigger for Federal plan 

development was not to give states time 

to develop and submit their state plans 

in excess of the regulatorily allotted 

timeframes. In this action, the Agency is 

finalizing timeframes for state plan 

submissions that are reasonably 

achievable and that may be superseded 

where necessary. Decoupling the 

finding of failure to submit and the 

trigger of state plan development should 

therefore not impact states’ abilities to 

develop and submit satisfactory state 

plans. States always have the ability to 

submit state plans and state plan 

revisions at any time. Additionally, 

while the EPA recognizes that it has not 

always provided timely Federal plans, 

the Agency does not believe that 

changing the starting point for its 

Federal plan clock from a finding of 

failure to submit to the day after state 

plan submission are due will have an 

appreciable impact on its ability to do 

so. Notably, the trigger for its timeline 

will not change the length of time the 

EPA has to promulgate a plan. While the 

commenter implies that the EPA would 

use the time before it has made a finding 

of failure to submit to start working on 

a Federal plan, it is not reasonable to 

assume that the Agency is in a position 

to start developing such a plan before it 

has had a chance to determine if a state 

plan is incomplete. Therefore, the EPA 

is finalizing its proposed approach of 

removing from subpart Ba a finding of 

failure to submit as the trigger for 

starting the timeline for a Federal plan. 

The approach being finalized in subpart 

Ba is consistent with the framework and 

requirements that have been effective in 

subpart B since 1975. The regulatory 

text at 40 CFR 60.27a(c)(1) is being 

revised slightly relative to proposal to 

clarify that the 12-month clock starts 

running the day after the state plan 

submission deadline for instances in 

which a state fails to submit a plan or 

plan revision by that deadline, and the 

day after state plan submissions would 

be deemed complete by operation of law 

(i.e., 60 days after the state plan 

submission deadline) for instances in 

which a state plan has been submitted 

but deemed incomplete.37 These 

revisions merely clarify the EPA’s intent 

at proposal to ensure that all states and 

stakeholders have a clear understanding 

of the timeline for promulgation of a 

Federal plan. As discussed in section 

III.A.4. of this preamble, the EPA is 

finalizing the requirement that it will 

have 12 months from the state plan 

deadline to promulgate a Federal plan 

for states that do not submit a plan. 

Note, the EPA is also finalizing a 

deadline of 12 months to promulgate a 

Federal plan for states whose plans are 

disapproved, but in those instances the 

EPA’s obligation and timeline to 

provide a Federal plan are triggered off 

of its disapproval of a state plan. 

The EPA notes that this amendment 

to subpart Ba does not affect the EPA’s 

obligation under CAA section 110(c) to 

promulgate a FIP within 2 years of 

making a finding that a state has failed 

to submit a complete SIP. In the case of 

the CAA section 110, the obligation for 

the EPA to first make a finding of failure 

to submit is derived from the statute, 

whereas nothing in CAA section 111(d) 

obligates the EPA to make such a 

finding before promulgating a Federal 

plan. CAA section 111(d)(1) directs the 

EPA to promulgate a process ‘‘similar’’ 

to that of CAA section 110, rather than 

a process that is identical. Therefore, the 

fact that a finding of failure to submit 

serves as the legal predicate for the 

EPA’s obligation to issue a FIP under 

CAA section 110 does not mean that the 

EPA is also required to treat such a 

finding as a legal predicate for a Federal 

plan under CAA section 111(d). 

In summary, while recognizing that a 

finding of failure to submit can have 

value in notifying states and the public 

of the status of plans, the EPA does not 

find that it is integral to the process of 

promulgating a Federal plan for states 

that do not submit plans. Further, the 

requirement for the EPA to issue a 

finding of failure can result in 

significant unwarranted delays in EG 

implementation. The EPA is therefore 

finalizing the proposed amendment that 

this finding will no longer be the event 

that triggers the timeline for the EPA’s 

issuance of a Federal plan. 40 CFR 

60.27a(c)(1). While the EPA will not 

publish a formal finding of failure to 

submit in the Federal Register, the 

Agency will notify the states and the 

public of a failure to submit 

expeditiously following the state plan 

submission deadline or deadline for 

EPA determinations of completeness, as 

applicable. Additionally, the EPA notes 

that the completeness criteria in 40 CFR 

60.27a(g) were promulgated in 2019, 84 

FR 32520, 32578 (July 8, 2019), and, 

while the EPA is removing finding of 

failure to submit as the trigger for 

promulgation of a Federal rule, it 

emphasizes that states may have 

discussions with the EPA and submit 

revised state plans at any point. That is, 

there remains within this framework 

ample opportunity for iterative state 

plan development. 

The regulatory provision at 40 CFR 

60.27a(c)(1), as finalized, is consistent 

with the requirement that applies 

regarding the EPA’s issuance of a 

Federal plan under subpart B. In subpart 

B (i.e., applicable to implementing 

regulations for CAA section 111(d) EGs 

promulgated on or prior to July 8, 2019, 

and currently applicable implementing 

regulations for CAA section 129 EGs), 

the EPA’s obligation to promulgate a 

Federal plan is triggered by the state 

plan submission deadline. 

C. Outreach and Meaningful 

Engagement 

The fundamental purpose of CAA 

section 111 is to reduce emissions from 

certain stationary sources that cause or 

significantly contribute to air pollution 

which may reasonably be anticipated to 

endanger public health or welfare. 

Therefore, a key consideration in the 

state’s development of a state plan, in 

any significant plan revision,38 and in 

the EPA’s development of a Federal 

plan or significant plan revision, 

pursuant to an EG promulgated under 

CAA section 111(d) is the potential 

impact of the proposed plan 

requirements on public health and 

welfare. A robust and meaningful public 

participation process is critical to 

ensuring that the full range of these 

impacts are understood and considered. 

States often rely primarily on public 

hearings as the foundation of their 

public engagement in their state plan 

development process because a public 

hearing has always been explicitly 

required pursuant to the applicable 

regulations. The existing provisions in 

subpart Ba (40 CFR 60.23a(c) through 

(f)) detail the public participation 

requirements associated with the 

development of a state plan. Per these 

implementing regulations, states must 


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39States may cancel a public hearing if no request 

for one is received during the required notification 

period. 40 CFR 60.23a(e). 

40 87 FR 79176, 79190–92 (Dec. 23, 2022). 

provide certain notice of, and conduct 

one or more public hearings on, their 

state plan before such plan is adopted 

and submitted to the EPA for review 

and action.39 The EPA is not reopening 

these basic and long-standing public 

hearing requirements in this 

rulemaking. However, as explained in 

the notice of proposed rulemaking,40

robust and meaningful public 

involvement in the development of a 

plan should sometimes go beyond the 

minimum requirement to hold a public 

hearing depending on who may be most 

affected by and vulnerable to the 

impacts being addressed by the plan. 

Because the CAA section 111(d) 

program addresses existing facilities, 

some of which may be decades old, it 

is possible that impacted communities 

may not have had a voice in the process 

when the source was originally 

constructed, or previous outreach may 

have focused largely on engaging the 

industry. The EPA proposed 

amendments to 40 CFR part 60, subpart 

Ba, were intended to strengthen the 

public participation provisions and 

ensure that all affected members of the 

public, not just a particular subset, have 

an opportunity to participate in the 

pollution control planning process by 

requiring meaningful engagement with 

pertinent stakeholders in the state’s 

development of a state plan, in any 

significant plan revision, and in the 

EPA’s development of a Federal plan 

pursuant to an EG promulgated under 

CAA section 111(d). 

The EPA proposed to add meaningful 

engagement with pertinent stakeholders 

in 40 CFR 60.23a(i) and 60.27a(f) and 

add the definition of meaningful 

engagement and of pertinent 

stakeholders in 40 CFR 60.21a. The EPA 

proposed to define meaningful 

engagement as it applies to this subpart 

as timely engagement with pertinent 

stakeholder representation in the plan 

development or plan revision process. 

Such engagement must not be 

disproportionate nor favor certain 

stakeholders. It must include the 

development of public participation 

strategies to overcome linguistic, 

cultural, institutional, geographic, and 

other barriers to participation to assure 

pertinent stakeholder representation, 

recognizing that diverse constituencies 

may be present within any particular 

stakeholder community. It must include 

early outreach, sharing information, and 

soliciting input on the state plan. The 

EPA also proposed to evaluate the 

approvability of state plans based on the 

components of the meaningful 

engagement definition. 

The EPA proposed that pertinent 

stakeholders ‘‘. . . include, but are not 

limited to, industry, small businesses, 

and communities most affected by and 

vulnerable to the impacts of the plan or 

plan revision.’’ Additionally, to ensure 

that a robust and meaningful public 

engagement process occurs as the states 

develop their CAA section 111(d) plans, 

the EPA proposed to amend the 

requirements in 40 CFR 60.27a(g) to 

include, as part of the completeness 

criteria, the requirement for states to 

demonstrate in their plan submittal how 

they provided meaningful engagement 

with the pertinent stakeholders. The 

state would be required to provide, in 

their plan submittal: (1) a list of the 

pertinent stakeholders identified by the 

state; (2) a summary of engagement 

conducted; and (3) a summary of the 

stakeholder input received. 

Most of the comments received on the 

proposed meaningful engagement 

requirements and proposed definitions 

were supportive of including 

meaningful engagement in the 

development of the state plans. Several 

commenters stated that they supported 

the inclusion of environmental justice 

considerations in Federal programs, 

including requirements for meaningful 

engagement. In particular, one 

commenter stated that outreach and 

meaningful engagement with 

stakeholders, specifically including 

communities most affected by and 

vulnerable to the pollution that would 

be reduced by a state plan, is an 

important and overdue step to ensuring 

that impacted communities have a voice 

in a process that directly impacts their 

health and welfare. While several 

commentors affirmed the EPA’s 

authority to require meaningful 

engagement, some commenters said that 

the EPA lacks such authority. One of the 

commenters argued that the EPA lacks 

authority to require consideration of 

public health and welfare under CAA 

section 111(d) because CAA section 111 

was devised as a technology-based 

approach to controlling emissions from 

stationary sources, not one predicated 

on the setting of standards directly and 

exclusively based on public health and 

welfare needs. One of the commenters 

stated the EPA lacks the authority to 

pass judgment on state plans submitted 

pursuant to CAA section 111(d) based 

on public engagement and argued that 

the only statutory requirement in CAA 

section 110 (which 111(d) crossreferences) is the requirement that states 

provide ‘‘reasonable notice and public 

hearings’’ prior to adoption of a state 

plan. 

Several commenters supported the 

EPA’s definition of meaningful 

engagement and the proposed 

meaningful engagement requirement. 

Additionally, some comments 

supported the state plan approvability 

requirements for meaningful 

engagement and recommended that the 

EPA also require an accounting of what 

states have done with stakeholder input 

and how that input was used or not 

used in their state plan. 

Several commenters expressed the 

need for additional resources in order to 

conduct meaningful engagement, both 

for states and communities. Some of the 

comments stated that the EPA needs to 

consider how these increased 

requirements may strain already limited 

state resources. One commenter said 

that resources needed to fulfill the 

requirements for meaningful 

engagement, including costs associated 

with identifying and contacting 

stakeholders, renting of rooms or spaces 

for multiple public meetings, travel, and 

associated staff time, will be significant 

and burdensome to states. 

There were several comments 

requesting clarification on the definition 

of meaningful engagement, and on the 

proposed approvability requirements for 

meaningful engagement. Some 

commenters requested that the rule 

provide more clarity on what states 

need to do for meaningful engagement 

and provide a clear path for states to 

develop an approvable meaningful 

engagement demonstration. Similarly, 

other commenters recommended the 

EPA establish a more detailed definition 

and provide examples of best practices 

for states to follow in implementing 

meaningful engagement, particularly 

with vulnerable communities, and 

further clarify what is meant by 

meaningful engagement with pertinent 

stakeholders. Some commenters cited 

lack of clarity in expressing their 

concern with meaningful engagement 

being a requirement for state plan 

approvability. 

Based on comments received, the EPA 

has revised the proposed definition of 

meaningful engagement and is finalizing 

revisions that are flexible enough to 

serve the unique needs of states and 

their stakeholders, rather than relying 

on the more prescriptive approach of 

the proposal. The EPA recognizes that 

states will generally be in the best 

position to understand how to 

meaningfully engage pertinent 

stakeholders within their borders as 

they develop state plans. The EPA also 

believes that states and the Federal 

Government may learn from each 


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other’s efforts to meaningfully engage 

pertinent stakeholders. The EPA further 

recognizes that appropriate approaches 

to meaningful engagement, as well as 

the time and resources needed, will be 

highly dependent on characteristics of 

the source category—such as the 

number and location of designated 

facilities—as well as on the type of 

health or environmental impacts of the 

emissions addressed by an EG. 

Additionally, as noted by a number of 

commenters, states are highly diverse 

in, among other things, their local 

conditions, resources, and established 

practices of engagement. Also as noted 

by commenters, vulnerable 

communities are highly diverse in, 

among other things, their technical 

capacities, access to resources for 

meaningful participation (e.g., 

geographic distribution, transportation, 

childcare), languages, and available 

representation. 

For these reasons, rather than 

finalizing prescriptive substantive 

requirements for how states should 

conduct meaningful engagement, the 

EPA is requiring in subpart Ba that 

states, in their state plan submissions or 

significant plan revisions, describe the 

efforts they undertook to meaningfully 

engage pertinent stakeholders, what 

input they received from stakeholders, 

and how that input was used or not 

used in their state plan. The EPA will 

also include this information when 

promulgating Federal plans or 

significant plan revisions. In addition, 

the EPA is describing some current best 

practices for meaningful engagement in 

this preamble that states may consider, 

that and which the Agency expects will 

continue to develop as states 

experiment with different types of 

meaningful engagement and share their 

experiences through state plans. 

Consistent with these changes, the 

EPA is finalizing the definition of 

meaningful engagement, as it applies to 

subpart Ba, as follows: ‘‘. . . timely 

engagement with pertinent stakeholders 

and/or their representatives in the plan 

development or plan revision process. 

Such engagement should not be 

disproportionate in favor of certain 

stakeholders and should be informed by 

available best practices.’’ States should 

therefore make a good faith effort to 

ensure that they are engaging in a 

proportionate manner with all pertinent 

stakeholders. The EPA is also finalizing, 

as proposed, a definition of ‘‘pertinent 

stakeholders.’’ Pertinent stakeholders 

‘‘include, but are not limited to, 

industry, small business, and 

communities most affected by and/or 

vulnerable to the impacts of the plan or 

plan revision.’’ Finally, the EPA is 

including in subpart Ba the three 

proposed completeness criteria 

requirements for meaningful 

engagement at 40 CFR 60.27a(g)(2)(ix) 

and adding a fourth completeness 

criterion, which will require state to 

include in their plans a description of 

how stakeholder input was considered 

in the development of the state plan or 

plan revisions. 

The EPA expects that the finalized 

approach to meaningful engagement in 

state plans will provide the flexibility 

needed to allow states to address 

specific and unique issues in their states 

and to appropriately communicate with 

and respond to their stakeholders 

during the notice and comment process. 

As revised, the meaningful engagement 

component finalized here strengthens 

the framework for public participation 

in state plan development, a longstanding cornerstone of the cooperative 

federalism structures of CAA sections 

110 and 111(d). The meaningful 

engagement component finalized here is 

intended to promote equitable 

opportunities to participate in the 

planning process for all stakeholders, as 

opposed to dictating a specific approach 

or set of practices that constitute 

meaningful engagement. 

To support the goals outlined above, 

and in response to comments received, 

the EPA is finalizing the proposed 

completeness criteria that require 

documentation of meaningful 

engagement, including adding a fourth 

completeness criterion, but the EPA is 

not finalizing specific requirements for 

what types of outreach meaningful 

engagement must include in subpart Ba. 

The fourth completeness criterion will 

require states to include a description of 

how stakeholder input from the 

meaningful engagement process was 

considered in the development of the 

plan, which the EPA expects will both 

bolster accountability to stakeholders 

and assist states in ensuring that their 

meaningful engagement processes are 

additive to the public hearing and 

notification processes which has always 

been required under subpart Ba. See 40 

CFR 60.27a(g)(1)(ix). While the EPA 

finds that the requirements finalized in 

this action are sufficient and 

appropriate for the general CAA section 

111(d) implementing regulations, the 

EPA may provide additional guidance 

pertaining to meaningful engagement in 

specific EGs. 

While the EPA is revising the 

definition of meaningful engagement 

relative to proposal, the definition of 

pertinent stakeholders is being finalized 

as proposed. Pertinent stakeholders 

include, among other stakeholders, 

industry, small business, and 

communities—in particular, 

communities who are most affected by 

and vulnerable to the health or 

environmental impacts of pollution 

from the designated facilities addressed 

by the plan or plan revision. Increased 

vulnerability of communities may be 

attributable to, among other reasons, an 

accumulation of negative 

environmental, health, economic, or 

social conditions within these 

populations or communities, and a lack 

of positive conditions. Examples of such 

communities have historically included, 

but are not limited to, communities of 

color (often referred to as ‘‘minority’’ 

communities), low-income 

communities, Tribal and indigenous 

populations, and communities in the 

United States that potentially 

experience disproportionate health or 

environmental harms and risks as a 

result of greater vulnerability and/or 

exposure to environmental hazards. For 

example, populations lacking the 

resources and representation to combat 

the effects of climate change—which 

could include populations exposed to 

greater drought or flooding, or damaged 

crops, food, and water supplies— 

experience greater vulnerability to 

environmental hazards. Sensitive 

populations (e.g., infants and children, 

pregnant women, the elderly, and 

individuals with disabilities 

exacerbated by environmental hazards) 

may also be most affected by and 

vulnerable to the impacts of the plan or 

plan revision depending on the 

pollutants or other factors addressed by 

an EG. 

Communities in neighboring states or 

neighboring Tribal nations may also be 

impacted by a state plan and, if so, are 

pertinent stakeholders. In addition, to 

the extent a designated facility would 

qualify for a less stringent standard 

through consideration of RULOF as 

described in section III.E. of this 

preamble, the pertinent stakeholders 

would include the communities most 

affected by and vulnerable to the health 

and environmental impacts from the 

designated facility considered in a state 

plan for RULOF provisions. 

The EPA has determined that the 

definitions of meaningful engagement 

and pertinent stakeholders in subpart Ba 

provide the states sufficient specificity 

while allowing for flexibility in the 

implementation of meaningful 

engagement. Meaningful engagement is 

an enhancement of the existing public 

notice and comment requirements and 

is intended to promote the sharing of 

relevant information with, and the 

soliciting of input from, pertinent 

stakeholders at critical junctures during 

plan development. In particular, the 


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41 42 U.S.C. 7410(a)(1). 

42See 40 CFR 51.102; 40 CFR part 51, appendix 

V, section 2.1. 

43Consistent with this principle of providing 

reasonable notice under the CAA, under programs 

other than CAA section 111(d), current regulations 

governing other CAA programs similarly require 

states to provide specific notice to an area affected 

by a particular proposed action. See e.g., 40 CFR 

51.161(b)(1) (requiring specific notice for an area 

affected by a state or local agency’s analysis of the 

effect on air quality in the context of the New 

Source Review program (40 CFR 51.102(d)(2), (4), 

and (5) (requiring specific notice for an area affected 

by a CAA section 110 SIP submission). 

44FACT SHEET: Biden-Harris Administration 

Mobilizes Resources to Connect Tribal Nations to 

Reliable, High-Speed Internet (December 22, 2021). 

https://www.whitehouse.gov/briefing-room/ 

statements-releases/2021/12/22/fact-sheet-bidenharris-administration-mobilizes-resources-toconnect-tribal-nations-to-reliable-high-speedinternet/; 7 percent of Americans don’t use the 

internet. Who are they? Pew Research Center (April 

2, 2021), https://www.pewresearch.org/fact-tank/ 

2021/04/02/7-of-americans-dont-use-the-internetwho-are-they/. 

processes for meaningful engagement 

should allow for fair and balanced 

participation, including opportunities 

for communities most affected by and 

vulnerable to the impacts of a plan an 

opportunity to be informed of and 

weigh in on that plan. These procedural 

requirements, in turn, help ensure that 

a plan will adequately address the 

potential impacts to public health and 

welfare that are the core concern of CAA 

section 111. Meaningful engagement can 

provide valuable information regarding 

health and welfare impacts experienced 

by the public (e.g., recurring respiratory 

illness, missed work or school days due 

to illness associated with pollution, and 

other impacts) and allow regulatory 

authorities to explore additional options 

to improve public health and welfare. 

Because the CAA section 111(d) 

program is designed to address widely 

varying types of air pollutants that may 

have very different types of impacts, 

from highly localized to regional or 

global, what constitutes fair and 

balanced participation among a broad 

set of pertinent stakeholders will be 

highly dependent on which 

stakeholders are directly impacted by a 

particular state plan. 

The EPA’s authority for finalizing 

procedural requirements to strengthen 

the public participation provisions of 

the implementing regulations is 

provided by the authority of both CAA 

sections 111(d) and 301(a)(1). Under 

CAA section 111(d), one of the EPA’s 

obligations is to ‘‘establish a procedure 

similar to that provided by’’ CAA 

section 110, under which states submit 

plans that implement emission 

reductions consistent with the BSER. 

CAA section 110(a)(1) requires states to 

adopt and submit SIPs after ‘‘reasonable 

notice and public hearings.’’ 41 The Act 

does not define what constitutes 

‘‘reasonable notice and public hearings’’ 

under CAA section 110, and the EPA 

has reasonably interpreted this 

requirement in promulgating a process 

under which states submit state plans.42

Subpart Ba currently includes certain 

requirements for notice and public 

hearing in 40 CFR 60.23a(c) through (f). 

The notice requirements include 

prominent advertisement to the public 

of the date, time, and place of the public 

hearing, 30 days prior to the date of 

such hearing, and the advertisement 

requirement may be satisfied through 

publication to the internet. Id. at 

paragraph (d). A state may choose to 

cancel a public hearing if no request for 

one is received during the required 

notification period. Id. at paragraph (e). 

A fundamental purpose of the Act’s 

notice and public hearing requirements 

is to ensure that all affected members of 

the public are able to participate in 

pollution control planning processes 

that impact their health and welfare.43

In order to effectuate this purpose of the 

Act’s notice and public hearing 

requirements, the notice of the proposed 

plans and of the public hearings should 

be reasonably adequate in its ability to 

reach affected members of the public. 

While many states provide for 

notification of public engagement 

through the internet consistent with the 

current requirements under the CAA 

section 111(d) implementing 

regulations, such notification may not 

be adequate to reach all those who are 

impacted by a CAA section 111(d) state 

plan and would benefit the most from 

participating in the state planning 

process. For example, data shows that as 

many as 30 million Americans do not 

have access to broadband infrastructure 

that delivers even minimally sufficient 

speeds, and that 25 percent of adults 

ages 65 and older report never going 

online.44 Accordingly, the EPA has 

determined that it is appropriate to 

improve the procedural public 

engagement requirements under CAA 

section 111(d) to ensure the statutory 

objectives are met. 

Given the public health and welfare 

objectives of CAA section 111(d) in 

regulating specific existing sources, it is 

reasonable to include a meaningful 

engagement component as part of the 

state plan development public 

participation process in order to further 

these objectives. Additionally, CAA 

section 301(a)(1) provides that the EPA 

is authorized to prescribe such 

regulations ‘‘as are necessary to carry 

out [its] functions under [the CAA].’’ As 

finalized, the meaningful engagement 

components of this rule would 

effectuate the EPA’s function under 

CAA section 111(d) in prescribing a 

process under which states submit plans 

to implement the statutory directives of 

this section and promote the statutory 

objective that all pertinent stakeholders 

have reasonable notice of relevant 

information and the opportunity to 

participate in the state plan 

development throughout the process. 

Ongoing engagement between states and 

pertinent stakeholders will help ensure 

that plans achieve the appropriate level 

of emission reductions, that 

communities most affected by and 

vulnerable to the health and 

environmental impacts from the 

designated facilities share in the 

benefits of the state plan, and that these 

communities are protected from being 

adversely impacted by the plan. 

To promote meaningful engagement, 

the EPA is finalizing as part of the 

completeness criteria in 40 CFR 

60.27a(g) procedural requirements for 

states to describe in their plan 

submittals how they engaged with 

pertinent stakeholders. As proposed, the 

state will be required to describe, in its 

plan submittal, (1) a list of the pertinent 

stakeholders identified by the state; (2) 

a summary of engagement conducted; 

and (3) a summary of the stakeholder 

input received. The EPA is also 

finalizing a fourth component as part of 

the procedural completeness 

demonstration—that the state also 

includes (4) a description of how 

stakeholder input was considered in the 

development of the plan or plan 

revisions. The EPA will review the state 

plan to ensure it includes these required 

descriptions regarding meaningful 

public engagement as part of its 

completeness evaluation of a state plan 

submittal. If a state plan submission 

does not include the required elements 

for notice and opportunity for public 

participation, including the procedural 

requirements at 40 CFR 60.23a(i) and 

60.27a(g)(2)(ix) for meaningful 

engagement, this may be grounds for the 

EPA to find the submission incomplete 

or (where a plan has become complete 

by operation of law) to disapprove the 

plan. 

While the EPA is finalizing 

procedural requirements for meaningful 

engagement as completeness criteria 

and is not prescribing how states 

proceed with such engagement, we 

understand states would find it useful to 

consider guidance as to how such 

engagement could be meaningfully 

conducted. In light of this interest, the 

following paragraphs provide examples 

and guidance which the EPA 


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45The EPA emphasizes that the appropriateness 

of any meaningful engagement strategy will depend 

on the specific context, including the sources and 

pollutants addressed by the EG, the scope and scale 

of the proposed regulation or plan, and the 

pertinent stakeholders. The activities and processes 

included in the examples of meaningful 

engagement in this preamble were tailored to the 

specific circumstances of EPA’s EG development. 

46See 86 FR 63110, 63140. 

47See 86 FR 63110, 63145. 

48See Docket ID No. EPA–HQ–OAR–2023–0072– 

0002. 

49https://archive.epa.gov/publicinvolvement/ 

web/pdf/policy2003.pdf. 50https://www.epa.gov/system/files/documents/ 

2023-09/epa-capacity-building-through-effectivemeaningful-engagement-booklet_0.pdf. 51See U.S. EPA Office of Air and Radiation 

‘‘Climate Pollution Reduction Grants Program: 

Formula Grants for Planning Program Guidance for 

States, Municipalities, and Air Pollution Control 

Agencies’’ (March 1, 2023), https://www.epa.gov/

system/files/documents/2023-02/

EPA%20CPRG%20Planning%20Grants

%20Program%20Guidance%20for%20StatesMunicipalities-Air%20Agencies%2003-01-2023.pdf 

(overview of the CPRG). See also U.S. EPA, ‘‘Status 

of Notice of Intent to Participate (NOIP) Submittals 

by States (March 31, 2023), https://www.epa.gov/

system/files/documents/2023-04/NOIP

%20Status%20Lists.pdf (list of states who have 

opted in to the CPRG as of March 31, 2023). 

52 Inflation Reduction Act section 60114. 

encourages states to consider in 

designing their own meaningful 

engagement programs. 

In considering approaches for 

meaningful engagement, states should 

consider the identification of pertinent 

stakeholders; developing a strategy for 

engagement with the identified 

pertinent stakeholders; making 

information available in a transparent 

manner; and providing adequate and 

accessible notice. First, it would be 

reasonable for states to identify 

pertinent stakeholders considering 

information specific to the applicable 

EG, including the nature of the 

designated pollutants at issue and the 

communities likely to be impacted by 

facilities in the source category. The 

EPA intends to specifically provide 

information on impacts of designated 

pollutant emissions to assist states in 

the identification of their pertinent 

stakeholders, in addition to any other 

guidance that EPA may find it 

reasonable to provide in the applicable 

EG. Moreover, in developing a strategy 

for engagement, it would be reasonable 

for states to share information and 

solicit input on plan development and 

on any accompanying assessments. 

Finally, in providing transparent and 

adequate notice of plan development, 

states should consider that internet 

notice alone may not be adequate for all 

stakeholders, given lack of access to 

broadband infrastructure in many 

communities. Thus, in addition to 

internet notice, examples of prominent 

advertisement for engagement and 

public hearing may include notice 

through newspapers, libraries, schools, 

hospitals, travel centers, community 

centers, places of worship, gas stations, 

convenience stores, casinos, smoke 

shops, Tribal Assistance for Needy 

Families offices, Indian Health Services, 

clinics, and/or other community health 

and social services as appropriate for 

the emission guideline addressed. 

The EPA believes the following 

example, while not tailored to specific 

designated facilities but to a source 

category for recent EG development, 

provides states with ideas for how they 

can structure their own meaningful 

engagement activities.45 Prior to the 

November 2021 proposal for the 

‘‘Standards of Performance for New, 

Reconstructed, and Modified Sources 

and Emissions Guidelines for Existing 

Sources: Oil and Natural Gas Sector 

Climate Review’’ (86 FR 63110), the 

EPA conducted meaningful engagement 

with pertinent stakeholders. For the preproposal stakeholder outreach, the EPA 

engaged with stakeholders through 

information posted on the internet, 

meetings, training webinars, and public 

listening sessions to disseminate 

information regarding this action, 

communicate how to submit comments 

on the proposed rule, and receive 

stakeholder input about the industry 

and its impact. In addition to the preproposal stakeholder engagement, the 

EPA conducted additional post-proposal 

training during the comment period on 

the proposed rule and held a public 

hearing. The EPA conducted three halfday post-proposal trainings to provide 

background information, an overview of 

the proposed rule, stakeholder panel 

discussions, and information on how to 

effectively engage in the regulatory 

process. The trainings were open to the 

public, focusing on individuals from 

and representatives of communities 

with EJ concerns, Tribes, and small 

businesses. Further considerations, 

analyses, and outreach relevant to 

meaningful engagement are presented in 

sections VI.46 and VII.47 of the preamble 

for that action and could help states in 

designing, planning, and developing 

their own outreach and engagement 

plans associated with the development 

and implementation of their state plans. 

An additional resource is the 

memorandum on stakeholder 

outreach 48 for the ‘‘New Source 

Performance Standards for Greenhouse 

Gas Emissions from New, Modified, and 

Reconstructed Fossil Fuel-Fired Electric 

Generating Units; Emission Guidelines 

for Greenhouse Gas Emissions from 

Existing Fossil Fuel-Fired Electric 

Generating Units; and Repeal of the 

Affordable Clean Energy Rule’’ 

proposed rule (88 FR 33240, May 23, 

2023). This memorandum provides 

states with another example of the types 

of activities and processes that the EPA 

has found appropriate for meaningfully 

engaging with stakeholders in the 

particular context of EG development. 

The EPA recognizes that the state 

planning process is different than a 

national rulemaking and may benefit 

from different types of engagement. 

Nonetheless, the information and 

examples the EPA has provided on 

meaningful engagement can serve as an 

example of what types of engagement 

states should consider for their 

meaningful engagement processes. In 

addition, to further assist states in the 

meaningful engagement efforts, the EPA 

expects to develop resources to aid 

states in establishing meaningful 

engagement best practices, while 

recognizing that states have differing 

situations and that best practices will 

not be ‘‘one size fits all.’’ One resource 

that states may find helpful in 

developing their own best practices is 

the ‘‘Public Involvement Policy of the 

US Environmental Protection 

Agency,’’ 49 which is currently under 

revision. Another helpful resource the 

EPA has developed is the ‘‘Capacity 

Building Through Effective Meaningful 

Engagement’’ booklet.50 The booklet is 

also available in the docket for this rule. 

Additionally, most states have opted 

into the EPA Climate Pollution 

Reduction Grant Program (CPRG),51

developed under the Inflation 

Reduction Act.52 To assist states that are 

participating in the CPRG, the EPA is 

conducting training for states on 

meaningful engagement, sharing case 

studies, best practices, and lessons 

learned through ongoing EPA-led CPRG 

forums. The EPA expects that, with 

experience and shared access to 

information on best practices, 

approaches to address challenges and 

barriers, and other resources and 

collaborative opportunities, meaningful 

engagement practices at the state and 

Federal level will continue to improve. 

D. Regulatory Mechanisms for State 

Plan Implementation 

CAA section 111(d)(1) requires the 

EPA to promulgate regulations that 

establish a procedure ‘‘similar’’ to that 

provided by CAA section 110 for each 

state to ‘‘submit to [the EPA] a state plan 

which . . . establishes standards of 

performance . . . and . . . provides for 

the implementation and enforcement of 

such standards.’’ The EPA reasonably 

interprets this provision, particularly 


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53These regulatory mechanisms were also 

previously proposed to be added to subpart B in 

2015 and largely received support from states, the 

public, and stakeholders, but were never finalized. 

80 FR 64965 (October 23, 2015). 

54Compare CAA section 111(d)(1) (requiring 

states to submit state plans that include specified 

types of measures that, in turn, meet minimum EPA 

requirements) and section 111(d)(2) (indicating that 

the EPA must review and approve or disapprove 

state plans, requiring the EPA to promulgate a 

Federal plan if the state does not submit a 

satisfactory plan, authorizing the EPA to enforce 

state plan measures) with section 110(a)(1)–(2) 

(requiring states to submit SIPs that include 

specified types of measures that in turn meet 

minimum EPA requirements), section 110(k) 

(requiring the EPA to review and approve or 

disapprove SIPs), section 110(c) (requiring the EPA 

to promulgate a FIP if the state does not submit a 

plan or the EPA disapproves the state plan) and 

113(a)(1) (authorizing the EPA to enforce SIP 

measures). 

55See Merriam Webster’s Dictionary, defining 

‘‘Similar’’ as ‘‘having characteristics in common’’ or 

‘‘alike in substance and essentials.’’ https://

www.merriam-webster.com/dictionary/similar. 

the ‘‘similar’’ clause, as referring to all 

the procedural provisions provided in 

CAA section 110 which serve the same 

purposes of providing useful 

flexibilities for states and EPA actions 

that help ensure emission reductions are 

appropriately and timely implemented. 

The EPA proposed to incorporate 5 

regulatory mechanisms as amendments 

to the implementing regulations under 

40 CFR part 60, subpart Ba, governing 

the processes under which states submit 

plans and the EPA acts on those plans. 

87 FR 79176, 79193–96 (Dec. 23, 2022). 

The proposed additional regulatory 

mechanisms include: (1) partial 

approval and disapproval of state plans 

by the EPA; (2) conditional approval of 

state plans by the EPA; (3) parallel 

processing of plans by the EPA and 

states; (4) a mechanism that allows the 

EPA to call for revision of a previously 

approved state plan; and (5) an error 

correction mechanism for the EPA to 

revise its prior action on a state plan.53

These mechanisms were proposed to 

update the implementing regulations to 

better align with the flexible procedural 

tools that Congress added into section 

110 of the CAA in the 1990 

Amendments. The EPA is finalizing the 

adoption and incorporation of these 

mechanisms into subpart Ba as the EPA 

has interpreted and applied them in the 

context of CAA section 110. 

As explained in the notice of 

proposed rulemaking, the interpretation 

that CAA section 111(d)(1) authorizes 

the EPA to adopt procedures ‘‘similar’’ 

to those under CAA section 110 for the 

entire state plan process, and not just 

the initial plan submission process, is 

strengthened by the provisions in CAA 

section 111(d)(2), which provide that 

the EPA has the ‘‘same’’ authority to 

promulgate a Federal plan for a state 

that has failed to submit a satisfactory 

plan as under CAA section 110(c), and 

to enforce state plan requirements as it 

does for SIPs under CAA sections 113 

and 114. This is because, read together, 

CAA section 111(d)(1) and (2) call for 

the set of essential procedural 

requirements for state and Federal plan 

development and implementation and 

enforcement that generally reflect the 

essential procedural requirements for 

SIPs and FIPs in section 110.54 In that 

context, it is reasonable to read CAA 

section 111(d)(1) as authorizing the EPA 

to promulgate procedures for section 

111(d) that are comparable to CAA 

section 110 procedures for the overall 

state plan process. Moreover, the EPA 

believes that it is reasonable, in 

promulgating the regulations required 

under CAA section 111(d)(1), to look to 

the mechanisms and flexibilities that 

Congress has deemed appropriate for 

states and the EPA to use in the highly 

analogous context of state and Federal 

implementation plans. 

The availability of these 5 regulatory 

mechanisms will streamline the state 

plan review and approval process, 

accommodate variable state processes, 

facilitate cooperative federalism, further 

protect public health and welfare, and 

generally enhance the implementation 

of the CAA section 111(d) program. 

Together, these mechanisms provide 

greater flexibility, may reduce 

processing time, and have proven to be 

very useful tools for the review and 

processing of CAA section 110 SIPs. 

Overall, the comments received for 

incorporating the 5 regulatory 

mechanisms were favorable, in 

particular noting that the mechanisms 

would offer not only procedural 

improvements long sought by state 

agencies but also reflect the flexibility 

offered in section 111 of the CAA, 

consistent with the Act’s cooperative 

approach, and would expand state 

planning options while conserving state 

resources. However, one commenter 

noted generally that for 111(d) plans, 

the CAA directs the EPA to establish a 

procedure similar to CAA section 110 

for SIP submittals but does not require 

those procedures to be identical. This 

commenter contended that while the 

CAA specifically authorized various 

flexible mechanisms in sections 

110(k)(2)–(6), the plain language of CAA 

section 111 does not provide for these 

options for 111(d) plans. 

The EPA agrees that procedures 

adopted under CAA section 111(d)(1) 

need not be identical to CAA section 

110 procedures, but interprets section 

111(d)(1) to authorize the EPA to adopt 

procedures under 111(d)(1) which are 

substantially the same as those outlined 

under section 110, including section 

110 procedural mechanisms.55

Additionally, as explained above, while 

CAA section 111(d)(1) directs EPA to 

establish ‘‘a procedure . . . under 

which each State shall submit to the 

Administrator a plan,’’ section 111(d)(2) 

further provides that EPA also has 

authority to prescribe a Federal plan 

where states fail to submit a satisfactory 

plan and to enforce the provisions of 

state plans in cases where states fail to 

do so. Congress saw fit to provide 

mechanisms such as conditional 

approval and SIP calls under CAA 

section 110 for the purpose of EPA 

evaluation and action on, and 

enforcement of, SIPs, and the Agency 

believes it is reasonable to look to 

section 110 as evidence of the types of 

mechanisms that are reasonable for EPA 

to provide for the same purposes under 

section 111(d). 

These regulatory mechanisms will 

provide flexibility and support 

efficiency to the states and the EPA in 

the submission and processing of state 

plans. For the reasons discussed in the 

following sections, the EPA is finalizing 

these provisions. 

1. Partial Approval and Disapproval 

The EPA proposed a provision similar 

to that under CAA section 110(k)(3) for 

the EPA to partially approve and 

partially disapprove severable portions 

of a state plan submitted under CAA 

section 111(d). Under CAA section 

110(k)(3), ‘‘[i]f a portion of the plan 

revision meets all the applicable 

requirements of this chapter, the 

Administrator may approve the plan 

revision in part and disapprove the plan 

revision in part. The plan revision shall 

not be treated as meeting the 

requirements of this chapter until the 

Administrator approves the entire plan 

revision as complying with the 

applicable requirements of this 

chapter.’’ Subpart Ba currently 

authorizes the EPA to ‘‘approve or 

disapprove [the state] plan or revision or 

each portion thereof’’ (40 CFR 60.27a(b)) 

but does not explicitly specify whether 

such actions may be partial. 

One commenter stated that the partial 

approval and disapproval mechanisms 

the EPA proposed appear to be aimed at 

providing a way for the EPA to approve 

model rule provisions and disapprove 

RULOF provisions. The EPA disagrees 

with this comment. The EPA reviews 

each provision of a state plan, regardless 

of the type of provision, to determine 

whether it meets the applicable 


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statutory and regulatory requirements. If 

it meets the applicable requirements, 

the EPA must approve it. It is entirely 

possible, and in fact common, for some 

state plan provisions to comport with 

the applicable requirements and others 

not to. Pursuant to this mechanism, the 

EPA may partially approve or partially 

disapprove a state plan when portions 

of the plan are approvable, but other 

discrete and severable portions are not. 

In such cases, the purposes of a CAA 

section 111(d) EG, as well as section 

111(d)’s framework of cooperative 

federalism, would be better served by 

allowing the state to move forward with 

implementing those portions of the plan 

that are approvable, rather than to 

disapproving the full plan and 

potentially delaying implementation of 

beneficial emission reductions. This 

mechanism is consistent with the ALA 

decision’s emphasis on ensuring timely 

mitigation of harms to public health and 

welfare, as problematic parts of a state 

plan submission would not stall the 

implementation of emission reductions 

at designated facilities for which a 

portion of a plan could be approved, 

thus efficiently reducing the time from 

EG promulgation to implementation of 

emission reductions at those facilities. 

The EPA is finalizing this provision 

so that it is similar to CAA section 

110(k)(3), providing clarity on the EPA’s 

authority to partially approve plans and 

the circumstances under which it may 

be used. As explained at proposal, the 

portion of a state plan that the EPA may 

partially approve must be ‘‘severable.’’ 

A portion is severable when: (1) the 

approvable portion of the plan does not 

depend on or affect the portion of the 

plan that cannot be approved, and (2) 

approving a portion of the plan without 

approving the remainder does not alter 

the approved portion of a state plan in 

any way that renders it more stringent 

than the state’s intent. See Bethlehem 

Steel v. Gorsuch, 742 F.2d 1028, 1034 

(7th Cir. 1984). The EPA’s decision to 

partially approve and partially 

disapprove a plan must go through 

notice and comment rulemaking. As a 

result, the public will have an 

opportunity to submit comment on the 

appropriateness and legal application of 

this mechanism on a particular state 

plan submission. A partial disapproval 

of a plan submission would have the 

same legal effect as a full disapproval 

for purposes of the EPA’s authority 

under CAA section 111(d)(2)(A) to 

promulgate, for the partially 

disapproved portion of the plan, a 

Federal plan for the state to fill the gap. 

See section III.A.4 of this preamble for 

finalized timelines for promulgation of 

a Federal plan. If the EPA does 

promulgate a Federal plan for a partially 

disapproved portion, the state may, at 

any time, submit a revised plan to 

replace that portion. If the state does so, 

and the EPA approves the revised plan, 

then the EPA would withdraw the 

Federal plan for that state. 

This partial approval/disapproval 

mechanism also enables states to 

submit, and authorizes the EPA to 

approve or disapprove, state plans that 

are partial in nature and to address only 

certain elements of a broader program. 

For example, with this mechanism, 

states will be able to submit partial 

plans intended to replace discrete 

portions of a Federal plan, where 

appropriate. Partial submittals must 

meet all completeness criteria. 

2. Conditional Approval 

The EPA proposed a mechanism 

analogous to the authority under CAA 

section 110(k)(4) to grant the EPA the 

ability to conditionally approve a state 

plan under CAA section 111(d). Under 

CAA section 110(k)(4), ‘‘[t]he 

Administrator may approve a plan 

revision based on a commitment of the 

state to adopt specific enforceable 

measures by a date certain, but not later 

than 1 year after the date of approval of 

the plan revision. Any such conditional 

approval shall be treated as a 

disapproval if the state fails to comply 

with such commitment.’’ The proposed 

provision would authorize the EPA to 

conditionally approve a plan 

submission that substantially meets the 

requirements of an EG but that requires 

some additional, specified revisions to 

be fully approvable. For the EPA to 

conditionally approve a submission, the 

state Governor or their designee must 

commit to adopt and submit specific 

enforceable provisions to remedy the 

stipulated plan deficiency. The 

provisions required to be submitted by 

the state pursuant to a conditional 

approval would be treated as an 

obligation to submit a plan revision and 

be subject to the same processes and 

timeframes for the EPA action as other 

plan revisions (e.g., completeness 

determination, approval and/or 

disapproval). 

Comments were generally supportive 

of including the mechanism in subpart 

Ba for use by the EPA in acting on CAA 

111(d) state plans. One commenter 

submitted that the EPA should limit 

conditional approvals to plans either 

with only procedural deficiencies or 

with substantive deficiencies that (1) 

apply to few designated facilities (e.g., 

no more than 5); (2) do not lead to 

impacts on vulnerable communities; 

and (3) are likely to be remedied by the 

state within one year. Comments were 

received both supporting and opposing 

the proposed 12-month time period for 

adopting and submitting the necessary 

revisions associated with a conditional 

approval. In particular, one commenter 

recommended allowing more than 12 

months for submission of subsequent 

revisions that are required as part of 

conditional approvals that relate to 

RULOF provisions. After considering 

the comments received, the EPA is 

declining to explicitly limit the 

circumstances in which conditional 

approval may be used and is finalizing 

the 12-month period for submission of 

a plan revision pursuant to a 

conditional approval as proposed. First, 

the EPA views the conditional approval 

mechanism as a beneficial flexibility for 

states in instances in which partial 

disapproval may be appropriate because 

a discrete portion of a state plan does 

not meet the applicable requirements, 

but that deficiency is not so significant 

that it affects the substantial adequacy 

of the plan. CAA section 110(k)(4) 

supports this view, as Congress 

provided only 12 months for states 

correct the deficiency; 12 months is 

likely not sufficient for states to remedy 

significant substantive deficiencies in a 

plan. Thus, the EPA believes both that 

structure of the conditional approval 

mechanism already appropriately 

circumscribes its use and that extending 

the timeline for states to submit plan 

revisions pursuant to conditional 

approval would abrogate its utility as a 

way to address minor issues in a plan 

and encroach on circumstances in 

which partial disapproval is more 

appropriate. Second, under the 

provisions being finalized in this 

rulemaking, in the event that EPA did 

partially disapprove a state plan in lieu 

of conditionally approving it, the 

Agency would have 12 months to 

promulgate a Federal plan to fill the 

gap. See 40 CFR 60.27a(c)(2). It would 

be inappropriate to provide states a 

longer period of time in the same 

circumstances to remedy a deficiency. 

As finalized, if the state fails to meet 

its commitment to submit the measures 

within 12 months, the conditional 

approval automatically converts to a 

disapproval. If a conditionally approved 

state plan converts to a disapproval due 

to either the failure of the state to timely 

submit the required measures or if the 

EPA finds the submitted measures to be 

unsatisfactory, such disapproval would 

be grounds for implementation of a 

Federal plan under CAA section 

111(d)(2)(A). The EPA will publish a 

notice in the Federal Register and, if 

appropriate, on the public website 


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established for the EG notifying the 

public that the conditional approval is 

converted to a disapproval. As 

described in section III.A.4. of this 

preamble, the EPA would be required to 

promulgate a Federal plan within 12 

months of state’s failure to submit the 

required measures or the EPA’s 

disapproval of measures submitted to 

address the conditional approval. 

Commenters asserted that the EPA 

should take action to develop a Federal 

plan immediately upon issuing a 

conditional approval, and further 

asserted that the EPA should not allow 

the conditional approval mechanism to 

toll the Federal plan clock and thereby 

delay needed public health and welfare 

protections. A conditional approval is 

not a disapproval and therefore there 

has been no failure on the part of the 

state and thus will not trigger a 

corresponding Federal plan for the 

given state nor initiate a timeline for the 

EPA to provide a Federal plan. 

Conditional approvals will be evaluated 

and designed on a case-by-case basis, 

with consideration of public health and 

welfare, and are expected to result in 

approved state plans and therefore not 

require the development of a Federal 

plan. The commenters also noted the 

EPA proposed to allow 12 months in 

which to impose a Federal plan 

following disapproval of a previously 

conditionally approved plan and stated 

instead the EPA should start the clock 

for developing a Federal plan as soon as 

a state plan submission is conditionally 

approved if the EPA has determined 

that there is a significant possibility that 

the deficiencies will not be corrected. 

The EPA disagrees with this comment 

because the Agency would not 

conditionally approve a plan if the 

deficiencies were not expected to be 

corrected; in this instance, a partial 

disapproval of the plan would be 

appropriate. 

Another commenter requested that 

the EPA clarify the applicable 

compliance deadline for a state plan 

that is conditionally approved by the 

Agency. The commenter contended that 

the proposed rule did not specify the 

‘‘trigger’’ date for compliance deadlines 

when the EPA conditionally approves a 

state plan, and recommended that, in 

this scenario, compliance deadlines 

should begin to run when the state 

satisfies the condition(s) established by 

the EPA. However, the EPA notes that 

compliance timeframes for designated 

facilities are specified in the applicable 

EGs. To the extent that the 

Administrator conditionally approves a 

plan, the compliance timeframes must 

still meet the requirements in the EG. A 

conditional approval may not be an 

appropriate action if the result would be 

a significant delay in compliance, as 

that is inconsistent with the intention of 

adding this flexibility for state plan 

processing. 

Incorporating this mechanism under 

the subpart Ba will have the benefit of 

allowing a state with a substantially 

complete and approvable program to 

begin implementing it, while also 

promptly making specific changes that 

ensure it fully meets the requirements of 

CAA section 111(d) and of the 

applicable EGs. The EPA is therefore 

finalizing this provision as proposed at 

40 CFR 60.27a(b)(2). 

3. Parallel Processing 

The EPA proposed to include a 

mechanism similar to that for SIPs 

under 40 CFR part 51 appendix V, 

section 2.3.1., for parallel processing a 

plan that does not yet meet all of the 

administrative completeness criteria 

under 40 CFR 60.27a(g)(2). This 

streamlined process allows the EPA to 

propose approval of such a plan in 

parallel with the state completing its 

process to fully adopt the plan in 

accordance with the required 

administrative completeness criteria, 

and then allows the EPA to finalize 

approval once those criteria have been 

fully satisfied and a final plan has been 

submitted. 

At proposal, the EPA explained that 

parallel processing under subpart Ba 

would be subject to certain conditions. 

In lieu of the letter required under 40 

CFR 60.27a(g)(2)(i), the state must 

submit the proposed plan with a letter 

requesting the EPA propose approval 

through parallel processing. Under the 

parallel processing procedures, a state 

will be temporarily exempt from the 

administrative completeness criteria as 

defined by 40 CFR 60.27a(g)(2) 

regarding legal adoption of the plan (40 

CFR 60.27a(g)(2)(ii) and (v)) and from 

some of the public participation criteria 

(40 CFR 60.27a(g)(2)(vi), (vii), and 

(viii)). However, as with parallel 

processing for SIPs under 40 CFR part 

51, appendix V, in lieu of these 

administrative criteria, the state must 

include a schedule for final adoption or 

issuance of the plan and a copy of the 

proposed/draft regulation or the 

document indicating the proposed 

changes to be made, where applicable. 

Note that a proposed plan submitted for 

parallel processing must still meet all 

the criteria for technical completeness 

as defined by 40 CFR 60.27a(g)(3) and 

meet all other administrative 

completeness criteria as defined by 40 

CFR 60.27a(g)(2). If these conditions are 

met, the submitted plan may be 

considered for purposes of the EPA’s 

initial plan evaluation and proposed 

rulemaking action. 

The exceptions to the administrative 

criteria described above only apply to 

the EPA proposing action on the state 

plan. If the EPA has proposed approval 

through parallel processing, the state 

must still submit a fully adopted and 

final plan that meets all of the 

completeness criteria under 40 CFR 

60.27a(g), including the requirements 

for legal adoption and public 

engagement, before the EPA can finalize 

its approval. If the state finalizes and 

submits to the EPA a plan that includes 

changes relative the plan that the EPA 

proposed to approve, the EPA will 

evaluate those changes for significance. 

If any such changes are found by the 

EPA to be significant (e.g., changes to 

the stringency or applicability of a 

particular standard of performance), 

then the state submittal would be 

treated as an initial submission and the 

EPA would be required to re-propose its 

action on the final plan and to provide 

an opportunity for public comment. 

Note further that once the state plan 

submission deadline passes, the EPA 

retains the authority to initiate 

development of a Federal plan at any 

time for a state that has not submitted 

a complete plan, even if a state has 

requested parallel processing and the 

EPA has proposed an action. The EPA 

intends to continue working 

collaboratively with states who are in 

the process of adopting and submitting 

state plans but notes that states must 

remain mindful of regulatory deadlines 

for CAA section 111(d) plan 

submissions even when seeking to use 

the parallel processing mechanism. 

While comments were generally 

supportive of the EPA adopting parallel 

processing for CAA section 111(d) 

plans, some commenters expressed 

concern that the purpose and benefits of 

meaningful engagement would not be 

realized in the state plan development 

process if this mechanism were 

finalized as proposed. One commenter 

noted that the proposed parallel 

processing provision appeared to 

indicate that the state can submit its 

plan to the EPA prior to conducting 

meaningful engagement, and that the 

EPA is expecting an informational 

meeting rather than actual engagement 

from the public during the meaningful 

engagement process. Another 

commenter remarked that if a state does 

not include meaningful engagement 

before submitting its initial plan to the 

EPA, the proposed parallel processing 

mechanism creates an inherent 

disincentive for the state to modify a 

plan under this mechanism in response 

to any public engagement which occurs 


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56An example of this circumstance in the context 

of CAA section 110 is the 2015 ‘‘SSM SIP Call’’, 

which required states to correct previously 

approved SIP provisions based on subsequent court 

decisions regarding startup, shutdown, and 

malfunctions (SSM) operations. 80 FR 33840, June 

12, 2015. 

57For example, the 1998 ‘‘NOX SIP call’’ required 

states to submit SIP revisions addressing NOX

emissions found, after SIP approvals, to 

significantly impact the attainment of air quality 

standards in other states due to atmospheric 

transport. 63 FR 57356, October 27, 1998. 

subsequent to submittal, and further 

stated this would increase the disparity 

between the feedback received from the 

individuals the EPA designed the 

meaningful engagement provisions to 

protect and feedback from individuals 

or organizations with plentiful resources 

for proactive engagement. The 

commenters also asserted that members 

of the public, knowing that a version of 

the plan is already under Federal 

review, would be more likely to doubt 

that their feedback would have an 

impact on the final product. 

The EPA agrees with these 

commenters that, as proposed, 

exempting meaningful engagement from 

completeness criteria requirements 

under parallel processing would be a 

disincentive to meeting to the goals of 

meaningful engagement. In fact, as 

defined in this action, meaningful 

engagement is the ‘‘timely engagement 

with pertinent stakeholders and/or their 

representatives in the plan development 

or plan revision . . .’’ (emphasis 

added). Thus, meaningful engagement 

should occur well in advance of a state 

being ready to submit a plan to the EPA 

for parallel processing. The EPA is 

therefore excluding the meaningful 

engagement completeness criteria 

defined at 40 CFR 60.27a(g)(2)(ix) from 

the completeness criteria exceptions 

provided under the finalized parallel 

processing provision at § 60.27a(h)(4). 

That is, states must include the 

information required under 

§ 60.27a(g)(2)(ix) in any proposed state 

plans submitted to the EPA for parallel 

processing. Meaningful engagement is 

integral in early state plan development 

and should be included as part of the 

completeness criteria for parallel 

processing. 

The EPA is finalizing as part of the 

completeness criteria in 40 CFR 

60.27a(g) procedural requirements for 

states to describe in their plan 

submittals how they engaged with 

pertinent stakeholders. The state will be 

required to describe, in its plan 

submittal, (1) a list of pertinent 

stakeholders identified by the state; (2) 

a summary of engagement conducted; 

(3) a summary of the stakeholder input 

received; and (4) a description of how 

stakeholder input was considered in the 

development of the plan or plan 

revisions. 

4. State Plan Call 

Under CAA section 110(k)(5), the EPA 

may call for a revision of a state 

implementation plan ‘‘[w]henever the 

Administrator finds that the applicable 

implementation plan . . . is 

substantially inadequate to . . . comply 

with any requirement of [the Act].’’ The 

EPA proposed to add a mechanism 

analogous to this ‘‘SIP call’’ provision to 

subpart Ba at 40 CFR 60.27a(i) under 

CAA section 111(d), which would 

authorize the EPA to find that a 

previously approved state plan does not 

meet the applicable requirements of the 

CAA or of the relevant EG and to call 

for a plan revision. This mechanism is 

a useful tool for ensuring that approved 

state plans continue to meet the 

requirements of the EGs and of the CAA 

over time. This may be particularly 

important because EGs that achieve 

emission reductions from specific 

source categories may be implemented 

over many years. 

As proposed, the state plan call 

provision stated that, whenever the 

Administrator finds that the applicable 

plan is substantially inadequate to meet 

the requirements of the applicable EG, 

to provide for the implementation of 

such plan or to otherwise comply with 

any applicable requirement of subpart 

Ba or the CAA, the Administrator shall 

require the state to revise the plan as 

necessary to correct such inadequacies. 

The EPA explained that a plan call 

would be generally appropriate under 

two circumstances: when legal or 

technical conditions arise after the EPA 

approves a state plan that undermine 

the basis for the approval and when a 

state fails to adequately implement an 

approved state plan. In the first 

circumstance, a change in conditions or 

circumstances could render an 

approved plan inconsistent with the EG, 

subpart Ba, and/or the CAA, 

necessitating a plan revision to realign 

it with the applicable requirements. For 

example, a court decision subsequent to 

the approval of a plan may render that 

plan substantially inadequate to meet 

applicable CAA requirements resulting 

from the change in law.56 Or, the EPA 

may determine that technical 

conditions, such as design assumptions, 

about control measures that were the 

basis for a state plan approval later 

prove to be inaccurate, meaning that the 

plan would be substantially inadequate 

to achieve the emission reductions 

required by the EG and therefore the 

plan should be revised.57

The second circumstance in which a 

state plan call may be appropriate is 

when a state fails to adequately 

implement an approved state plan. In 

this case, the approved state plan may 

facially meet all applicable 

requirements, but a failure in 

implementation (e.g., due to changes in 

available funding, resources, or legal 

authority at the state level) renders the 

plan substantially inadequate to meet 

the requirements of the EG and CAA 

section 111(d). In this circumstance, a 

state, in response to a plan call, would 

either be required to submit a plan 

revision that provides for 

implementation of the plan’s 

requirements given the state’s actual 

circumstances or to provide 

demonstration that the plan is being 

adequately implemented as approved. 

Consistent with the SIP call process 

under CAA section 110(k)(5), the EPA 

proposed that, after it finds that a state’s 

approved plan is substantially 

inadequate to comply with applicable 

requirements, it would require the state 

to revise the plan as necessary to correct 

inadequacies. The EPA proposed that 

such finding and notice must be public. 

The plan call notice would identify the 

plan inadequacies leading to the plan 

call and establish a reasonable deadline 

(not to exceed 12 months after the date 

for such notice) for submission of a plan 

revision and/or demonstration of 

appropriate implementation of the 

approved plan. 

A number of commenters asserted 

that the EPA is not authorized to issue 

a call for state plans under CAA section 

111(d) because Congress did not provide 

this explicit authority in CAA section 

111. Some commenters also expressed 

concern that this mechanism 

undermines the regulatory certainty 

approved plans provide to facilities. 

Additionally, some commenters 

contended that CAA sections 113 and 

114 address the condition of states not 

properly implementing approved state 

plans such that a state plan call 

mechanism is unnecessary. 

As explained at the start of this 

section of the preamble (section III.D.), 

the EPA interprets CAA section 

111(d)(1)’s direction to prescribe 

regulations establishing a procedure 

similar to that provided by CAA section 

110 for the submission of state plans to 

authorize the EPA to adopt the section 

110 procedural mechanisms. 

Additionally, CAA section 111(d)(2) 

provides that EPA shall have the same 

authority as under CAA section 110(c) 

to prescribe a Federal plan where a state 

fails to submit a satisfactory plan, as 

well as the same authority as under 

CAA sections 113 and 114 to enforce the 


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58The regulations being finalized at § 60.27a(i)(1) 

further provided that if the Administrator makes the 

finding in § 60.27a(i) on the basis that a State is 

failing to implement an approved plan, or part of 

an approved plan, the State may submit a 

demonstration to the Administrator it is adequately 

implementing the requirements of the approved 

state plan in lieu of a plan revision. Such 

demonstration must be submitted by the deadline 

established under § 60.27a(i). 

59See, e.g., CAA sections 110(k)(4), 129(b)(2), and 

179(d). 

provisions of a state plan where the 

state fails to enforce them. Congress did 

not specify how the EPA is to exercise 

its authority to approve or disapprove 

state plans, promulgate Federal plans, 

and oversee and enforce state plan 

implementation on an ongoing basis, 

and the EPA finds it reasonable to look 

to other mechanisms under the CAA 

that Congress has provided for 

substantially the same purpose. That is, 

the EPA believes CAA sections 111(d)(1) 

and 111(d)(2), taken together, provide 

the legal basis for incorporating 

mechanisms into subpart Ba that ensure 

the ongoing compliance of state plans 

with the applicable requirements, 

including the state plan call mechanism 

of CAA section 111(k)(5). 

While CAA sections 113 and 114 

provide the EPA authority to enforce the 

provisions of state plans through, inter 

alia, issuance of administrative orders 

and penalties, civil actions in the case 

of violations, and use of monitoring, 

reporting, recordkeeping, and 

compliance certifications, the EPA 

believes it is also reasonable and helpful 

to provide a mechanism for states to 

bring their state plans into compliance 

with the applicable requirements. A 

state’s failure to implement its approved 

plan may result if that plan’s 

implementation or enforcement 

measures, e.g., monitoring, reporting, 

and verification requirements, prove 

inadequate to enable a state to ensure 

that a designated facility is meeting its 

standards of performance. A failure to 

implement may also arise, as described 

above, where an approved state plan 

contains the appropriate 

implementation and enforcement 

measures but changes in, e.g., available 

funding, resources, or legal authority at 

the state level render the plan, as it is 

being implemented, substantially 

inadequate to meet the requirements of 

subpart Ba, the EG, or CAA section 

111(d). In either instance, a reasonable 

alternative to EPA enforcement may be 

for the Agency to issue a state plan call 

in order to give the state an opportunity 

to remedy the deficiency or to provide 

demonstration that the plan is being or 

will be adequately implemented as 

approved. As with all of the regulatory 

mechanisms being incorporated into 

subpart Ba in this rulemaking, the EPA 

interprets CAA sections 111(d)(1) and 

(2) as collectively providing the 

authority to provide for procedures for 

ensuring that state plans remain 

‘‘satisfactory’’ over the long time periods 

over which they are implemented, given 

that subsequent findings or conditions 

may affect the basis for a previous plan 

approval. 

The EPA acknowledges that a call for 

revision of a state plan may result in a 

change in the requirements to which 

regulated entities are subject under than 

plan. However, as explained above, state 

plan calls are appropriate in two general 

circumstances: when legal or technical 

conditions arise that abrogate the basis 

of the initial state plan approval and 

when a state fails to adequately 

implement an approved state plan. In 

either of these two instances, the plan 

as it is currently being implemented 

fails to meet the applicable 

requirements. The EPA believes it 

would be neither consistent with the 

statute nor reasonable to fail to correct 

a state plan under these circumstances 

and that the state plan call mechanism, 

which provides for notice to the state 

and the public and a process for revising 

the state plan that is intended to cause 

as little disruption to the original plan 

as possible, is appropriate. The state 

plan call provisions state that ‘‘[a]ny 

finding under this paragraph shall, to 

the extent the Administrator deems 

appropriate, subject the State to the 

requirements of this part to which the 

State was subject when it developed and 

submitted the plan for which such 

finding was made, except that the 

Administrator may adjust any dates 

applicable under such requirements as 

appropriate.’’ 58

Several commenters noted that the 

proposed ‘‘not to exceed 12 months’’ 

timeline associated with the state call 

revision provision may be inadequate 

for states to respond to a state plan call 

and noted that this time is shorter than 

that provided for plan development. 

However, because a state plan call 

would represent that a plan is 

substantially inadequate to meet an EG 

after implementation of the plan was 

supposed to be underway, and 

compliance deadlines may have already 

passed, a more expeditions timeline to 

fix the problem than the deadline for 

initial plan development is imperative 

to the public health concerns. 

Additionally, the EPA anticipates that 

in many instances a state plan call 

would impact a discrete portion or 

element of a plan that will not require 

the same amount of time the EPA is 

allotting for initial state plan 

development and submission, i.e., 18 

months, to correct. The EPA believes 12 

months is a reasonable timeframe and 

allows for public outreach and state 

processes while ensuring the deficiency 

is expeditiously corrected to address 

any outstanding public health and 

welfare concerns associated with a 

deficient plan, consistent with the ALA 

decision. However, the Agency also 

acknowledges that this may not be true 

in every instance. The EPA is therefore 

finalizing the state plan call mechanism 

with a change relative to proposal to 

provide that plan revisions associated to 

a state plan call shall be submitted to 

the Administrator within 12 months or 

within a period as determined by the 

Administrator, instead of ‘‘not to exceed 

12 months.’’ Because the CAA contains 

numerous deadlines requiring states to 

submit various state implementation 

plans within 12 months of a triggering 

event,59 the EPA believes it is 

reasonable to expect states to be able to 

submit state plan revisions pursuant to 

a state plan call within this timeframe 

as well. The final language provides 

more flexibility and allows that the EPA 

may supersede this 12-month timeframe 

in appropriate circumstances. 

While this period is less than the time 

allotted for the submission of a full state 

plan (finalized in section III.A.1. of this 

preamble above as 18 months), it can 

provide a reasonable timeframe for 

public outreach and state processes 

while ensuring the deficiency is 

expeditiously corrected to address any 

outstanding public health and welfare 

concerns associated with a deficient 

plan, consistent with the ALA decision. 

With the exception of this revision to 

the timeline for states to submit revised 

state plans, the EPA is finalizing the 

state plan call mechanism at 40 CFR 

60.27a(i) as proposed. As explained at 

proposal, any failure of a state to submit 

necessary revisions by the date set in 

the call for state plan revisions 

constitutes a failure to submit a required 

plan submission. Therefore, pursuant to 

CAA section 111(d)(2)(A), the EPA 

would have the authority to promulgate 

a Federal plan for the state within 12 

months after the necessary revisions are 

due. If the state fails to submit a plan 

revision, to make an adequate 

demonstration within the prescribed 

time pursuant to 40 CFR 60.27a(i)(1), or 

if the EPA disapproves a submission, 

then the EPA would be required to 

promulgate a Federal plan addressing 

the deficiency for sources within that 

state. 


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60For example, see 74 FR 57051, November 3, 

2009, for correction of clerical and typographical 

errors in a portion of an Arizona SIP. 

61For example, see 86 FR 24505 (May 7, 2021) 

(removal of asbestos requirements from a Kentucky 

SIP). 62For example, see 86 FR 23054, April 30, 2021, 

for error correction with respect to Kentucky’s 

‘‘good neighbor obligations’’ and SIP disapproval. 

63As explained in section III.E.1. of this 

preamble, any discussion and requirements that 

apply to states’ consideration of RULOF in state 

plans also apply to the EPA’s consideration of 

RULOF in the context of a Federal plan. 

64The D.C. Circuit’s vacatur of certain provisions 

of subpart Ba in ALA did not impact the existing 

RULOF provision at 40 CFR 60.24a(e). 

5. Error Correction 

Under CAA section 110(k)(6), the EPA 

may, on its own accord, revise its prior 

action on a state implementation plan 

under certain circumstances: 

‘‘[w]henever the Administrator 

determines that the Administrator’s 

action approving, disapproving, or 

promulgating any plan or plan revision 

(or part thereof) . . . was in error, the 

Administrator may in the same manner 

as the approval, disapproval, or 

promulgation revise such action as 

appropriate without requiring any 

further submission from the State.’’ The 

EPA proposed to add a mechanism 

analogous to this ‘‘error correction’’ 

provision to subpart Ba at 40 CFR 

60.27a(j) under CAA section 111(d) and 

is finalizing that mechanism as 

proposed. 

As explained in the notice of 

proposed rulemaking, this error 

correction provision would authorize 

the EPA to revise its prior action when 

the EPA determines its own action on 

the state plan was in error. Specifically, 

this provision allows the EPA to revise 

its prior action in the same manner as 

used for the original action (e.g., 

through rulemaking) without requiring 

any further submissions from the state. 

In this manner, the error correction 

mechanism does away with unnecessary 

burdens on states based solely on an 

error made by the EPA, such as 

submitting a plan revision and the 

public participation related 

requirements under 40 CFR 60.23a (e.g., 

providing notice and holding a public 

hearing). 

CAA section 110(k)(6) is phrased 

broadly, and its legislative history 

makes clear that it ‘‘explicitly authorizes 

EPA on its own motion to make a 

determination to correct any errors it 

may make in taking any action, such as 

. . . approving or disapproving any 

plan.’’ See House Report No. 101–490 at 

220. The circumstances that may give 

rise to an error that the EPA may correct 

with this mechanism depend on the 

specific facts and plan at issue, and the 

use of the mechanism is justified on a 

case-by-case basis. The EPA has 

previously used CAA section 110(k)(6) 

for correction of technical or clerical 

errors,60 for removal of substantive 

provisions from an EPA-approved state 

plan that did not relate to 

implementation, enforcement, or 

maintenance of the NAAQS or is 

otherwise permissible under the CAA 

for inclusion in the plan,61 and when 

the EPA in error approved a SIP that did 

not meet applicable requirements.62

These examples are not the only 

circumstances when the EPA has used 

CAA section 110(k)(6) in the past and 

do not limit the EPA for circumstances 

of error correction under section 111(d) 

in the future. 

One commenter, while not objecting 

to the inclusion of this mechanism, 

suggested the EPA should make clear in 

the regulations that this provision 

cannot be used to effect a change in 

policy because of a change in 

perspective on implementation that may 

arise from an administration transition, 

citing the need for designated facilities 

to have regulatory certainty and to avoid 

unexpected changes in regulatory 

requirements. Other commenters also 

noted that the proposed regulatory text 

does not place any limitations on the 

EPA’s ability to use the error correction 

provision and that the EPA should 

impose meaningful limits on its ability 

to use this mechanism to effectuate 

significant changes to a prior action or 

to implement new policy perspectives. 

The EPA acknowledges the concern 

expressed by the commenters. The 

Agency intends the same intrinsic limits 

on its error correction authority that 

exist under CAA section 110(k)(6) to 

apply to its use under subpart Ba: the 

EPA must determine that its action on 

a state plan submission was ‘‘in error.’’ 

The EPA reviews state plan submissions 

against the applicable requirements of 

the statute, general implementing 

regulations, and specific EG. If the 

submission meets those requirements, it 

is ‘‘satisfactory’’ and the EPA must 

approve it. A subsequent change in 

Agency policy alone does not constitute 

an error that the EPA committed in 

acting on the state plan. The EPA’s 

history of using error correction 

mechanisms under CAA section 

110(k)(6), including to correct clerical or 

typographic errors and remove 

provisions from SIPs that it was without 

authority to approve in the first instance 

(as described earlier), gives good 

indication of how the EPA intends to 

use this mechanism under subpart Ba. 

The EPA also notes that use of error 

correction is fact- and context-specific, 

and a determination that a previous 

action was in error is subject to scrutiny 

and review by the state and public. 

Additionally, due to the complex facts 

and circumstances that frequently 

characterize state plans and state plan 

implementation, the EPA believes that 

any attempt to further define the 

circumstances in which use of error 

correction may or may not be 

permissible is likely to inadvertently 

limit its use where otherwise 

appropriate. Thus, the Agency does not 

find it necessary to prescribe further 

limits on its use of error correction 

under these CAA section 111 

implementing regulations. The EPA is 

therefore finalizing use of error 

correction for state plan actions at 40 

CFR 60.27a(j) as proposed. While the 

EPA maintains that this error correction 

mechanism would be available for 

acting on state plans when appropriate, 

it also expects that it will work with 

states, as it has done previously in the 

SIP context, to correct any deficiencies 

in their plans. 

E. Remaining Useful Life and Other 

Factors (RULOF) Provisions 

The EPA is finalizing revisions to 

certain provisions of 40 CFR 60.24a to 

clarify the framework for applying 

standards of performance based on 

RULOF in state plans 63 under CAA 

section 111(d). Consistent with 

Congress’s mandate in CAA section 

111(d), the EPA’s implementing 

regulations have guided the 

implementation of RULOF for decades. 

See 40 CFR 60.24(d), (f). The existing 

subpart Ba regulations 64 contain 

provisions at 40 CFR 60.24a(e) 

governing the circumstances under 

which states may take RULOF into 

consideration when applying standards 

of performance to particular sources in 

state plans. The EPA proposed revisions 

to these existing provisions as well as 

additional RULOF-related requirements 

to ensure consistency with the statute 

and to enhance clarity and equitable 

treatment for states. The EPA is 

finalizing some of these provisions as 

proposed, is finalizing other provisions 

with changes relative to proposal in 

response to public comments, and is 

choosing not to finalize yet other 

provisions. 

Section III.E.1. of this preamble 

describes the statutory and regulatory 

background of RULOF under CAA 

section 111 and section III.E.2. of this 

preamble explains the authority and 

rationale for the collective regulatory 

revisions. Section III.E.3. of this 


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65 142 S. Ct. 2587, 2601–02 (2022). 66 Id. The part of the rule preamble cited by the 

Court states, in part: ‘‘Under CAA section 111(a)(1) 

and (d), the EPA is authorized to determine the 

BSER and to calculate the amount of emission 

reduction achievable through applying the BSER. 

The state is authorized to identify the emission 

standard or standards that reflect that amount of 

emission reduction.’’ 80 FR 64662, 64664 n. 1 (Oct. 

23, 2015). 

67See Public Law 91–604, section 111(d)(1) (Dec. 

31, 1970), 84 Stat. 1684. 

68 40 FR 53340, 53344 (Nov. 17, 1975). 

69 39 FR 36102, 36102 (Oct. 7, 1974). 

70 40 FR 53343. 

71 Id. 

72See id. 

preamble describes in detail the 

proposed RULOF provisions and the 

EPA’s approach to each provision in 

this final rule. 

1. Statutory and Regulatory Background 

Under CAA section 111(d), the EPA is 

required to ‘‘establish a procedure . . . 

under which each State shall submit to 

the Administrator a plan which (A) 

establishes standards of performance 

for’’ designated facilities and ‘‘(B) 

provides for the implementation and 

enforcement of such standards of 

performance.’’ As the Supreme Court 

explained in West Virginia v. EPA (in 

the context of an EG addressing existing 

power plants): ‘‘Although the States set 

the actual rules governing existing 

power plans, EPA itself still retains the 

primary regulatory role in Section 

111(d).’’ 65 The Court elaborated that the 

‘‘[t]he Agency, not the States, decides 

the amount of pollution reduction that 

must ultimately be achieved. It does so 

by again determining, as when setting 

the new source rules, ‘the best system of 

emission reduction . . . that has been 

adequately demonstrated for [existing 

covered] facilities.’ 40 CFR part 

60.22(b)(5) (2021); see also 80 FR 64664, 

and n. 1. The States then submit plans 

containing the emissions restrictions 

that they intend to adopt and enforce in 

order not to exceed the permissible level 

of pollution established by EPA. See 

parts 60.23, 60.24; 42 U.S.C. part 

7411(d)(1).’’ 66

Accordingly, while states establish 

the standards of performance for 

individual sources, EPA must ensure 

that such standards reflect the degree of 

emission limitation achievable through 

the application of the BSER. This 

obligation derives from the definition of 

‘‘standard of performance’’ under CAA 

section 111(a)(1), which is ‘‘a standard 

for emissions of air pollutants which 

reflects the degree of emission 

limitation achievable through the 

application of the best system of 

emission reduction which . . . the 

Administrator determines has been 

adequately demonstrated.’’ Consistent 

with this definition, the EPA identifies 

the degree of emission limitation 

achievable through application of the 

BSER for a category (or sub-category) of 

existing sources as part of its EG. 40 

CFR 60.22a(b)(5). States must then 

establish standards of performance for 

existing sources in their state plans that 

reflect the EPA’s degree of emission 

limitation. 

CAA section 111(d)(1) also requires 

that the ‘‘regulations which establish a 

procedure’’ for submission of state plans 

must ‘‘permit’’ states, ‘‘in applying a 

standard of performance to any 

particular source under a plan,’’ to 

consider, ‘‘among other factors, the 

remaining useful life of the existing 

source.’’ Thus, while standards of 

performance must generally reflect the 

degree of emission limitation achievable 

through application of the BSER 

determined by the EPA pursuant to 

CAA section 111(a)(1), see 40 CFR 

60.24a(c), CAA section 111(d)(1) also 

contemplates circumstances in which 

states would be permitted to deviate 

from the degree of emission limitation 

in the applicable EG based on 

consideration of RULOF for particular 

sources. 

The 1970 version of CAA section 

111(d) made no reference to the 

consideration of RULOF in the context 

of standards for existing sources.67 In 

the 1975 regulations promulgating 

subpart B to implement the 1970 CAA 

section 111(d), however, the EPA 

included a provision that would allow 

states to provide ‘‘variances’’ from the 

EPA’s emission guideline on a case-bycase basis.68 For health-based 

pollutants, the regulations provided that 

states could apply a standard of 

performance less stringent than the 

EPA’s EGs based on cost, physical 

impossibility, and other factors specific 

to a designated facility that would make 

the application of a less stringent 

standard significantly more reasonable. 

40 CFR 60.24(f). For welfare-based 

pollutants, the regulations provided that 

states could apply a less stringent 

standard by balancing the requirements 

of an EG ‘‘against other factors of public 

concern.’’ 40 CFR 60.24(d). 

In proposing this variance provision, 

the EPA explained that the application 

of less stringent emission standards on 

a case-by-case basis is allowed, 

provided that sufficient economic 

justification is demonstrated in each 

case. Such justification must be 

presented for each case in the plan and 

may include, for example, unreasonable 

cost of control resulting from plant age, 

location, or basic process design or 

physical impossibility of installing 

specified control systems.69 In response 

to a comment received on its proposal 

arguing that the EPA did not have 

authority to promulgate a variance 

provision, the Agency explained that, 

although section 111(d) does not 

explicitly provide for variances, it does 

require consideration of the cost of 

applying standards to existing facilities. 

Such a consideration is inherently 

different than for new sources, 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. For these reasons, EPA 

believes the provision (§ 60.24(f)) 

allowing States to grant relief in cases of 

economic hardship (where healthrelated pollutants are involved) is 

permissible under section 111(d).70

The Agency further explained in the 

1975 rulemaking that the ‘‘EPA’s 

emission guidelines will reflect its 

judgment of the degree of control that 

can be attained by various classes of 

existing sources without unreasonable 

costs.’’ 71 States were required to 

establish emission standards for existing 

sources that are equivalent to the EPA’s 

emission guidelines; states would also 

be free to apply more stringent 

standards for particular sources within 

a class of sources that can achieve 

greater control without unreasonable 

costs, or where they otherwise believe 

that additional control is necessary or 

desirable.72

As part of the 1977 CAA amendments, 

Congress amended CAA section 

111(d)(1) in a way that codified the 

provision of a variance as contained in 

the EPA’s 1975 regulations. Specifically, 

Congress amended CAA section 

111(d)(1) to require that the EPA’s 

regulations under this section ‘‘shall 

permit the State in applying a standard 

of performance to any particular source 

under a plan submitted under this 

paragraph to take into consideration, 

among other factors, the remaining 

useful life of the existing source to 

which such standard applies.’’ The EPA 

considered the variance provision under 

subpart B to meet this requirement and 

did not revise the provision subsequent 

to the 1977 CAA amendments until the 

Agency promulgated new implementing 

regulations in 2019 under subpart Ba. 

As part of the 2019 revisions, the EPA 

removed the health- and welfare-based 

pollutants distinction and collapsed the 

associated requirements of the previous 

variance provision into a single, thenVerDate Sep<11>2014 22:37 Nov 16, 2023 Jkt 262001 PO 00000 Frm 00031 Fmt 4701 Sfmt 4700 E:\FR\FM\17NOR4.SGM 17NOR4

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73 84 FR 32520, 32577 (July 8, 2019). 

74Public Law 91–604, section 110(c) (Dec. 31, 

1970), 84 Stat. 1681–82. 

75See also 40 CFR 60.27(c) (‘‘The Administrator 

will, after consideration of any State hearing record, 

promptly prepare and publish proposed regulations 

setting forth a plan, or portion thereof, for a State 

if: (1) The State fails to submit a plan within the 

time prescribed; . . . (3) The Administrator 

disapproves the State plan or plan revision or any 

portion thereof, as unsatisfactory because the 

requirements of this subpart have not been met.’’); 

60.27(d) (providing for promulgation of a proposed 

Federal plan). 

76Congress subsequently updated CAA section 

110(c) in 1977 and again in 1990. The current 

version of CAA section 110 splits the EPA’s Federal 

implementation plan authority and the criteria for 

disapproval of State implantation plans across 

subsections 110(c) and 110(k)(3). CAA section 

110(c)(1) provides that ‘‘[t]he Administrator shall 

promulgate a Federal implementation plan at any 

time within 2 years after the Administrator—’’ (A) 

finds that a State has failed to make a complete plan 

submission, or ‘‘(B) disapproves a State 

implementation plan submission in whole or in 

part, unless the State corrects the deficiency, and 

the Administrator approves the plan or plan 

revision, before the Administrator promulgates such 

Federal plan.’’ CAA section 110(k)(3), which 

addresses ‘‘[f]ull and partial approval and 

disapproval,’’ states that the Administrator shall 

approve all or certain portions of the plan that 

‘‘meet[] the applicable requirements of this 

chapter.’’ Thus, a plan, or any portion thereof, that 

fails to meet the applicable CAA requirements must 

be disapproved. 

77Black’s Law Dictionary (11th ed. 2019); see also 

The American College Dictionary (1970) (‘‘to let 

(something) be done or occur’’); Oxford English 

Dictionary Online (‘‘to allow or give consent to (a 

person or thing) to do or undergo something’’), 

https://www.oed.com/search/dictionary/ 

?scope=Entries&q=permit, page accessed Sept. 1, 

2023. 

78See, e.g., U.S. v. Chau, 293 F.3d 96, 101 (3d 

Cir., 2002) (a provision requiring an entity to 

provide notice to the EPA prior to acting is not a 

‘‘permit’’ because ‘‘[a] requirement that someone 

provide written notice of an intention to perform an 

act is not the same at the EPA’s granting of a 

license, or other permission, to the person to 

perform the act in question . . . .’’). 

79This contrasts with other provisions of the 

Clean Air Act where Congress granted states 

unbounded discretion. See, e.g., CAA section 116 

(‘‘nothing in this chapter shall preclude or deny the 

right of any State or political subdivision thereof to 

adopt or enforce’’ more stringent requirements). 

80 564 U.S. 410 (2011). 

81 Id. at 427. 

new RULOF provision.73 As did subpart 

B before it, this subsection provides 

that, in applying a standard of 

performance to a particular source, the 

state may take into consideration factors 

including the remaining useful life of 

such source, provided that the state 

demonstrates one or more of three 

circumstances: unreasonable cost of 

control resulting from plant age, 

location, or basic process design; 

physical impossibility of installing 

necessary control equipment; or other 

factors specific to the facility that make 

application of a less stringent standard 

or compliance time significantly more 

reasonable. The 2019 RULOF provision 

also allows, as did the 1975 version, for 

the variance to be provided for a 

particular facility or class of such 

facilities. 

CAA section 111(d)(2) provides that 

‘‘[t]he Administrator shall have the 

same authority . . . to prescribe a plan 

for a State in cases where the State fails 

to submit a satisfactory plan as he 

would have under section 7410(c) of 

this title [i.e., CAA section 110(c)] in the 

case of failure to submit an 

implementation plan.’’ When CAA 

section 111(d)(2) was enacted in 1970, 

CAA section 110(c) stated that the 

Administrator shall promptly propose a 

Federal implementation plan for a state 

if ‘‘(1) the State fails to submit an 

implementation plan . . . within the 

time prescribed, (2) the plan, or any 

portion thereof, submitted for such State 

is determined by the Administrator not 

to be in accordance with the 

requirements of this section, or (3) the 

State fails, within 60 days after 

notification by the Administrator or 

such longer period as he may prescribe, 

to revise an implementation plan as 

required pursuant to a provision of its 

plan . . . .’’ 74

Thus, CAA section 111(d)(2), through 

its reference to CAA section 110(c), 

provides the EPA the authority and the 

obligation to review state plans for 

compliance with CAA requirements.75 76

If a state has not submitted a state plan 

or if the EPA determines that a state 

plan is not ‘‘satisfactory,’’ i.e., not in 

accordance with the requirements of 

CAA section 111, the EPA must 

promulgate a Federal plan. 

Congress further provided in CAA 

section 111(d)(2) that the EPA shall, in 

promulgating a standard of performance 

under a Federal plan, ‘‘take into 

consideration, among other factors, 

remaining useful lives of the sources in 

the category of sources to which such 

standard applies.’’ Thus, the RULOF 

regulations the EPA has previously 

promulgated in subparts B and Ba, and 

the revisions to the RULOF regulations 

in subpart Ba being finalized in this 

action, apply not only to states when 

promulgating state plans, but also to the 

EPA when promulgating a Federal plan. 

Throughout this section III.E. of the 

preamble, discussion of provisions and 

requirements that apply to states’ 

consideration of RULOF in state plans 

also apply to the EPA’s consideration of 

RULOF in the context of a Federal plan. 

2. Authority and Rationale for the 

Revisions 

The primary authority for these 

revisions is in CAA section 111(d)(1). 

The rationale for the revisions finalized 

here is to more fully align the 

implementing regulations with the 

statute and to enhance clarity for states 

as well as the equitable treatment of 

states and sources. 

CAA section 111(d)(1) directs the EPA 

to ‘‘prescribe regulations which 

establish a procedure’’ under which 

states submit state plans. These 

regulations must ‘‘permit’’ states, in 

applying a standard of performance to 

any particular source, to consider 

RULOF. That is, Congress gave the EPA 

the authority and the obligation to 

establish procedures that permit states 

to consider RULOF. 

The EPA has been guiding 

consideration of RULOF for over fifty 

years, consistent with Congress’s 

direction. ‘‘Permit’’ means ‘‘to consent 

to formally; to allow (something) to 

happen, esp[ecially] by an official 

ruling, decision, or law.’’ 77 It is well 

understood that there may be 

parameters or rules as a condition of 

someone consenting to or allowing 

something to be done. For example, a 

building permit generally does not 

allow a person to build in any way they 

like, but contains conditions and 

requirements such as compliance with 

safety codes and limitations on height. 

In general, ‘‘permit,’’ whether a verb or 

noun, carries with it an expectation of 

rules and parameters designed to ensure 

consistency with the applicable 

framework, as opposed to open-ended 

discretion.78 CAA section 111(d)(1) 

provides that ‘‘regulations of the 

Administrator . . . shall permit the 

State’’ to consider RULOF (emphasis 

added). The natural reading of this 

provision is that Congress intended the 

EPA to set out parameters and 

conditions that govern states’ 

consideration of RULOF..

79

The EPA’s role in implementing 

RULOF finds further support in the 

Supreme Court’s understanding of this 

provision as laid out in American 

Electric Power v. Connecticut.80 In 

describing the statutory framework of 

CAA section 111, the Court explained 

that the EPA sets standards of 

performance based on CAA section 

111(a)(1). It further recognized that, 

pursuant to the EPA’s subpart B general 

implementing regulations for state 

plans, 40 CFR 60.24(f), ‘‘EPA may 

permit state plans to deviate from 

generally applicable emissions 

standards upon demonstration that costs 

are ‘[u]n-reasonable.’ ’’ 81

At the same time that Congress clearly 

directed the EPA to prescribe rules 

governing states’ consideration of 

RULOF, it also provided that those rules 

establish a procedure under which 


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82CAA section 111(d)(2)(A) authorizes the EPA to 

promulgate a Federal plan for any state that ‘‘fails 

to submit a satisfactory plan’’ under section 

111(d)(1). Accordingly, the EPA interprets 

‘‘satisfactory’’ as the standard by which the EPA 

reviews state plan submissions. The EPA discusses 

the ‘‘satisfactory’’ standard of review in greater 

detail in section III.E.3.b of this preamble. 

83The EPA, in different contexts, uses the phrase 

‘‘degree of emission limitation’’ to refer to both the 

degree of emission limitation achievable through 

application of the BSER at the level of an individual 

source, e.g., the best system can achieve an 85% 

reduction in end-of-stack emissions when applied 

to a designated facility, and to the overall level of 

stringency that results from applying the BSER to 

the source category as a whole. In this section of 

the preamble, this phrase refers to the emission 

reductions that are achievable at an individual 

source. 

84See 40 CFR 60.22a(b)(5) (EPA may specify 

different degrees of emission limitation and 

compliance times for different subcategories of 

designated facilities). 

85 40 FR 53343. 

86 Id. 

87See id. 

88 Id. at 53344. Similarly, in the 1974 notice of 

proposed rulemaking for the subpart B regulations, 

the EPA explained that ‘‘it is the Administrator’s 

judgment that section 111(d) permits him to 

approve State emission standards only if they 

reflect application of the best systems of emission 

reduction (considering the cost of such reduction) 

that are available.’’ The EPA further stated: ‘‘It is 

recognized, however, that application of such 

standards may be unreasonable in some situations. 

For example, to require that existing controls be 

upgraded by a small margin at a relatively high cost 

may be unreasonable in some cases. The proposed 

regulations, therefore, provide that States may 

establish less stringent emission standards on a 

case-by-case basis provided that sufficient 

justification is demonstrated in each case.’’ 39 FR 

36102, 36102 (Oct. 7, 1974). 

89 39 FR 36102; see also 40 CFR 60.24(c), (f) 

(EPA’s longstanding regulations in subpart B 

require standards of performance in state plans to 

be no less stringent than the corresponding EG 

except where a state has satisfied the regulatory 

requirements for invoking RULOF). 

states submit state plans, including any 

standards of performance pursuant to 

consideration of RULOF. CAA section 

111(d)(1) states, ‘‘The Administrator 

shall prescribe regulations which shall 

establish a procedure . . . . Regulations 

of the Administrator under this 

paragraph shall permit the State in 

applying a standard of performance to 

any particular source . . . to take into 

consideration, among other factors, the 

remaining useful life of the existing 

source to which such standard applies.’’ 

Consistent with this statutory direction, 

the EPA’s RULOF provisions, both the 

existing provisions and those being 

finalized in this action, are 

fundamentally procedural in nature. 

They prescribe the series of steps and 

considerations states must undertake to 

apply a less stringent standard of 

performance that is consistent with 

CAA section 111(d). 

As discussed in section III.E.1. of this 

preamble, Congress also granted the 

EPA a role in ensuring that states 

applying standards of performance 

based on RULOF do so in an 

appropriate manner. CAA section 

111(d)(2) requires the EPA to evaluate 

standards of performance in state plans 

and approve them only if they are 

‘‘satisfactory,’’ i.e., if they meet the 

applicable requirements.82 Thus, while 

states have responsibility for 

establishing, implementing, and 

enforcing standards of performance for 

designated facilities, the EPA has an 

obligation to ensure that those standards 

of performance—including any 

standards of performance based on 

consideration of RULOF—are consistent 

with the statute. The regulations the 

EPA is promulgating in this final rule 

provide greater clarity and thus enable 

states to apply less stringent standards 

of performance that are consistent with 

CAA section 111(d). Having clear, 

detailed regulations also aids the EPA in 

evaluating less stringent standards of 

performance included in state plans, 

which maximizes the Agency’s ability to 

provide for fair and equitable treatment 

across the states and sources that use 

the RULOF provision. 

In addition, the parameters for 

considering RULOF set out in this final 

rule are consistent with the role of 

RULOF as an important tool for states in 

the unusual circumstance in which the 

EPA’s BSER determination is 

unreasonable for a particular source. As 

explained in detail in section III.E.3.b. 

of this preamble, the EPA’s longstanding 

interpretation is that RULOF provision 

in CAA section 111(d)(1) allows the 

Agency to permit states to provide 

variances for existing facilities in certain 

circumstances. These circumstances are 

limited to when a state can demonstrate 

that it is unreasonable for a particular 

facility to achieve the degree of 

emission limitation determined by the 

EPA in the applicable EG. 

Under CAA section 111, EPA must 

provide BSER and degree of emission 

limitation determinations that are, to the 

extent reasonably practicable, 

applicable to all designated facilities in 

the source category. In many cases, this 

requires the EPA to create subcategories 

of designated facilities, each of which 

has a BSER and degree of emission 

limitation 83 tailored to its 

circumstances.84 Thus, the EPA 

endeavors, to the extent practicable, to 

promulgate BSER and degree of 

emission limitation determinations that 

are achievable for all designated 

facilities covered by an EG. However, as 

Congress recognized, this may not be 

possible in every instance because, e.g., 

it is not be feasible for the Agency to 

know and consider the idiosyncrasies of 

every designated facility in a source 

category or because the circumstances of 

individual facilities change after the 

EPA determined the BSER. The EPA 

believes Congress intended RULOF to 

allow the EPA to permit the use of 

variances for states to adjust a standard 

of performance in unusual 

circumstances in which the EPA’s 

determination regarding the degree of 

emission limitation achievable through 

the BSER is not reasonable for a 

particular designated facility. 

This view of the RULOF provision as 

a limited variance from the EPA’s 

determinations in an EG has a long 

history. The EPA’s description of how it 

develops EGs in the preamble to the 

1975 subpart B implementing 

regulations stated that ‘‘emission 

guidelines will reflect subcategorization 

within source categories where 

appropriate, taking into account 

differences in sizes and types of 

facilities and similar con- . . . 

siderations [sic], including differences 

in control costs that may be involved for 

sources located in different parts of the 

country.’’ 85 As a result, emission 

guidelines ‘‘will in effect be tailored to 

what is reasonably achievable by 

particular classes of existing sources, 

and States will be free to vary from the 

levels of control represented by the 

emission guidelines in the ways 

mentioned above.’’ 86 The ‘‘ways 

mentioned above’’ included establishing 

more stringent standards under CAA 

section 116 where states believe 

additional control is necessary or 

desirable, as well as setting more lenient 

standards, subject to EPA review, in 

cases of economic hardship.87 The EPA 

subsequently explained that such cases 

could arise because controls were not 

included in the design of existing 

sources or because physical limitations 

may make installation of particular 

control systems impossible or 

unreasonably expensive in some 

cases.88

Thus, the EPA’s long-standing 

interpretation is that the standards of 

performance established by states must 

generally reflect the degree of emission 

limitation determined by the Agency, 

except where, based on RULOF, states 

provide ‘‘sufficient justification’’ that 

the EPA’s determination is 

‘‘unreasonable’’ for a particular 

source.89 Although the EPA endeavors 

to address the circumstances of all 

designated facilities in its EG, there may 

remain instances in which the 

circumstances of a particular facility 

justify application of a less stringent 

standard of performance. 


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90 49 FR 35771 (Sept. 12, 1984), 47 FR 50868 

(Nov. 10, 1982), 47 FR 28099 (June 29, 1982). See, 

e.g., Emission Guideline Document for Kraft 

Pulping: Control of TRS Emissions from Existing 

Mills, EPA–450/2–78–003b (March 1979) at 1–3 

(‘‘For Welfare-related pollutants, states may balance 

the emission guidelines, times for compliance, and 

other information in a guideline document against 

other factors of public concern in establishing 

emission standards, compliance schedules, and 

variances provided that appropriate consideration 

is given to the information presented in the 

guideline document and at public hearing(s) 

required by Subpart B and that all other 

requirements of Subpart B are met. . . . Thus, 

states will have substantial flexibility to consider 

factors other than technology and costs in 

establishing plans for the control of welfare-related 

pollutants if they wish.’’). 

91See 40 CFR 62.8860(a) (‘‘The requirements of 

§ 60.24(f) of this chapter are not met because the 

State failed to justify the application of emission 

standards less stringent than the Federal emission 

standards.’’); see also 55 FR 19883, 19884 (May 14, 

1990) (explaining the proposed less-stringent limits 

were not approvable because the state had not 

demonstrated sufficient justification). The RULOF 

provision that governed that action in subpart B 

was substantively identical to the version 

promulgated in 2019 in subpart Ba. 

92Proposed Rule: ‘‘Standards of Performance for 

New, Reconstructed, and Modified Sources and 

Emissions Guidelines for Existing Sources: Oil and 

Natural Gas Sector Climate Review,’’ 86 FR 63110 

(Nov. 15, 2021); Supplemental Proposal: Standards 

of Performance for New, Reconstructed, and 

Modified Sources and Emissions Guidelines for 

Existing Sources: Oil and Natural Gas Sector 

Climate Review,’’ 87 FR 74702 (Dec. 6, 2022); 

Proposed Rule: New Source Performance Standards 

for Greenhouse Gas Emissions From New, 

Modified, and Reconstructed Fossil Fuel-Fired 

Electric Generating Units; Emission Guidelines for 

Greenhouse Gas Emissions From Existing Fossil 

Fuel-Fired Electric Generating Units; and Repeal of 

the Affordable Clean Energy Rule,’’ 88 FR 33240 

(May 23, 2023). 

93See, e.g., Comment Letter of Pioneer Natural 

Resources USA, Inc. on Supplemental Notice of 

Proposed Rulemaking for Standards of Performance 

for New, Reconstructed, and Modified Sources and 

Emissions Guidelines for Existing Sources: Oil and 

Natural Gas Sector (‘‘Oil and Gas Proposed Rule’’), 

EPA–HQ–OAR–2021–0317–2298 at 20–21; 

Comment Letter of American Petroleum Institute on 

Oil and Gas Proposed Rule, EPA–HQ–OAR–2021– 

0317–2428 at 93–95, 102–104; Comment Letter of 

Power Generators Air Coalition on New Source 

Performance Standards for Greenhouse Gas 

Emissions from New, Modified, and Reconstructed 

Fossil Fuel-Fired Electric Generating Units; 

Emission Guidelines for Greenhouse Gas Emissions 

from Existing Fossil Fuel Fired Electric Generating 

Units; and Repeal of the Affordable Clean Energy 

Rule (‘‘EGU Proposed Rule’’), EPA–HQ–OAR–2023– 

0072–0710 at 75–78; Comment Letter of Wisconsin 

Department of Natural Resources and Public 

Service Commission of Wisconsin on EGU 

Proposed Rule, EPA–HQ–OAR–2023–0072–0538 at 

1–2, 10–11. 

Finally, and relatedly, to be consistent 

with the statutory purpose of reducing 

dangerous air pollution under CAA 

section 111; the statutory framework 

under which to achieve that purpose the 

EPA is directed to set the degree of 

emission limitation achievable through 

application of the best system of 

emission reduction; and the history of 

the statutory RULOF provision as a 

limited variance from that degree of 

emission limitation to address unusual 

circumstances at particular facilities, the 

EPA’s regulations must ensure that 

application of less stringent standards of 

performance pursuant to consideration 

of RULOF does not undermine the 

degree of emission limitation achievable 

through application of the BSER. 

Thus, for the reasons explained above, 

the EPA has the authority to promulgate 

the regulatory updates included in this 

final rule, which flow from the statute’s 

direction for the Agency to ‘‘establish 

procedures’’ that, among other things, 

‘‘permit’’ states to consider RULOF. The 

EPA believes these updates are 

warranted to provide additional clarity 

to the states (when developing state 

plans) and the EPA (when issuing 

Federal plans and reviewing state plans) 

regarding the appropriate procedures for 

considering RULOF and to ensure the 

predictable and equitable treatment of 

states and sources in implementing EGs 

under CAA section 111(d). Furthermore, 

the updates to the framework are 

needed to ensure that consideration of 

RULOF adheres to statutory purpose, 

structure, and historical context 

discussed above. 

Critically, the regulatory revisions 

also provide a framework for how states 

and the EPA calculate and apply lessstringent standards of performance. 

Neither the RULOF provision in subpart 

B nor the 2019 update to that provision 

in subpart Ba clearly delineate the 

process for states or the EPA after they 

have determined that a source cannot 

reasonably achieve the degree of 

emission limitation in the applicable 

emission guideline. As such, the 

existing regulations are not adequate to 

ensure that standards of performance 

pursuant to RULOF are no less stringent 

than required to address the basis for 

providing a variance from the EPA’s 

degree of emission limitation in the first 

instance. 

Consistent with the long-held 

interpretation of the RULOF provision 

as a limited variance, the EPA is aware 

of only a small handful of instances in 

which a state has used this provision to 

apply a less-stringent standard of 

performance to a designated facility in 

a state plan. In three of these instances, 

the Agency approved less stringent 

standards of performance for welfarerelated designated pollutants for which, 

under subpart B (40 CFR 60.24(d)), there 

was a lower bar for doing so.90 In the 

fourth instance, the state invoked 

RULOF to apply a less-stringent 

standard for a health-related designated 

pollutant and the EPA disapproved the 

less-stringent standard for failing to 

satisfy the requirements of 40 CFR 

60.24(f).91 At the time of this 

rulemaking, however, there are two new 

EGs for which rulemaking is ongoing; 

each of these EGs would address large, 

complex, and highly diverse source 

categories.92 Commenters on these 

proposed EGs have suggested that there 

may be more of a role for RULOF than 

in past EGs.93 The revisions to the 

RULOF provisions are thus timely to 

give states greater clarity on and 

predictability for applying less stringent 

standards of performance consistent 

with CAA section 111. 

Note that the RULOF provisions are 

distinct from the flexible compliance 

mechanisms such as trading and 

averaging, discussed in section III.G.1. 

of this preamble. The RULOF provisions 

apply where a state intends to depart 

from the degree of emission limitation 

in the EG and propose a less stringent 

standard for a designated facility (or 

class of facilities). That is, the RULOF 

provisions are relevant to a state’s 

process of applying a standard of 

performance to a designated facility in 

the first instance. In contrast, trading 

and averaging are mechanisms that, 

when permitted in an EG, states may 

use to demonstrate compliance with the 

standards of performance that are 

contained within their state plans. 

3. Proposed and Finalized RULOF 

Provisions 

The EPA proposed revisions to the 

existing RULOF provision at 40 CFR 

60.24a(e), which details the 

circumstances under which states or the 

EPA may apply a less stringent standard 

of performance. The EPA also proposed 

to add new provisions: a procedure for 

determining less stringent standards 

when a state has properly invoked 

RULOF (proposed and finalized at 40 

CFR 60.24a(f)); a clarification that state 

plans may not apply less stringent 

standards if a designated facility can 

reasonably achieve the presumptive 

standard of performance using a 

technology other than the BSER 

(proposed at 40 CFR 60.24a(g)); a 

clarification that any less stringent 

standards must meet all other applicable 

requirements (proposed at 40 CFR 

60.24a(l), finalized at 60.24a(h)); 

requirements related to when operating 

conditions that are relied on for a less 

stringent standard must be included as 

enforceable requirements in state plans 

(proposed at 40 CFR 60.24a(h), finalized 

at 40 CFR 60.24a(g)); requirements 

related to the consideration of 

remaining useful life (proposed 40 CFR 

60.24a(i)); a clarification regarding the 

burden of proof and information on 

which RULOF demonstrations are based 

(proposed 40 CFR 60.24a(j)); 


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94See also 40 CFR 60.24a(b). 

requirements to consider potential 

impacts and benefits of control to 

communities most affected by and 

vulnerable to emissions from a 

designated facility for which a state is 

proposed a less stringent standard 

(proposed 40 CFR 60.24a(k)); and a 

clarification that states may account for 

other factors in applying a more 

stringent standard of performance 

(proposed 40 CFR 60.24a(m)). In 

addition, the EPA proposed changes to 

the existing 40 CFR 60.24a(f) (proposed 

at 40 CFR 60.24a(n), finalized at 

§ 60.24(i)) reflecting the Agency’s 

revised interpretation that CAA sections 

111(d) and 116 authorize states to 

include standards of performance more 

stringent than the EPA’s presumptive 

standards in their state plans as 

enforceable requirements. 

The EPA received a wide range of 

comments on its proposed RULOF 

provisions. Some commenters expressed 

support for the proposed revisions, 

noting that the EPA has the authority to 

specify how RULOF is implemented 

and the obligation to ensure that its use 

does not undermine the emission 

reductions that are achievable through 

application of the BSER. Supportive 

commenters also noted that providing a 

regulatory structure is important to 

ensure that RULOF is applied in a 

reliable, consistent, and appropriate 

manner. Commenters opposed to the 

proposed RULOF revisions stated that 

there is no basis in the statute for the 

EPA to restrict states’ authority to 

consider RULOF and apply lessstringent standards of performance. 

Some commenters also argued that the 

EPA’s proposed regulations were too 

prescriptive and burdensome. Other 

commenters generally supported the 

EPA’s proposed revisions but had 

questions or concerns regarding specific 

provisions, including the requirements 

around source-specific standards of 

performance and consideration of 

impacted communities. One commenter 

requested that the EPA clarify that the 

revised RULOF provisions would apply 

to design, equipment, work practice, or 

operational standards issued under CAA 

sections 111(d) and 111(h)(1). 

After consideration of these 

comments, the EPA is finalizing a subset 

of the requirements that it proposed. As 

a general matter, the EPA is finalizing as 

requirements the provisions that must 

apply under any EG to provide 

necessary clarity to both the states and 

the EPA in applying or approving less 

stringent standards of performance. This 

clarity and predictability with regard to 

what constitutes a satisfactory, and 

therefore approvable, less stringent 

standard is crucial to ensuring the 

equitable treatment of states and sources 

that are considering RULOF in state 

plans. The requirements the EPA is 

finalizing are additionally necessary to 

ensure that use of RULOF is consistent 

with the statutory purpose of reducing 

emissions of dangerous air pollutants, 

the framework under which the EPA is 

directed to achieve that purpose through 

determining the degree of emission 

limitation, and history of RULOF as a 

limited variance to address unusual 

circumstances when it is not possible 

for a particular facility to achieve the 

EPA’s degree of emission limitation. 

The proposed RULOF provisions that 

are not being included as regulatory 

requirements remain important 

considerations when applying RULOF; 

however, the EPA is not finalizing them 

in these general implementing 

regulations. 

The EPA recognizes that in finalizing 

these updates it is imposing certain 

requirements on states’ use of RULOF. 

Consistent with the framework of 

cooperative federalism under which 

CAA section 111(d) operates, states 

apply standards of performance 

pursuant to consideration of RULOF, as 

well as provide the compliance 

measures for implementing such 

standards, subject to the applicable 

statutory requirements. The Agency 

again notes that it has placed 

requirements on states’ ability to apply 

less stringent standards of performance 

since it first created a variance provision 

in subpart B in 1975. See 40 CFR 

60.24(c) through (e). When Congress 

later adopted the RULOF provision into 

the statute, it directed the EPA in CAA 

section 111(d)(1) to establish a 

procedure permitting states to consider 

RULOF. Moreover, as discussed further 

in section III.E.3.b, these updates are 

consistent with the historical 

interpretation of RULOF as a variance 

from the EPA’s degree of emission 

limitation. The EPA also notes that the 

requirements being finalized in this 

action establish a process for states in 

applying less stringent standards of 

performance. These final regulations 

ensure, consistent with the statutory 

purpose, that any less stringent 

standards are no less stringent than 

necessary to address the reason that the 

variance is needed in the first place. 

Finally, the EPA confirms that the 

RULOF provisions, including those 

being finalized in this action, apply to 

standards of performance promulgated 

pursuant to CAA sections 111(d) and 

111(h)(1). The existing definition of 

‘‘standard of performance’’ in 40 CFR 

60.21a(f) includes ‘‘a legally enforceable 

regulation . . . prescribing a design, 

equipment, work practice, or 

operational standard, or combination 

thereof.’’ Therefore, the RULOF 

provisions in 40 CFR 60.24a, which may 

be invoked to apply a ‘‘standard of 

performance’’ to a particular designated 

facility, also apply to standards of 

performance applied under CAA section 

111(h)(1).94

a. Threshold Requirements for 

Considering Remaining Useful Life and 

Other Factors 

The existing RULOF provision at 40 

CFR 60.24a(e) addresses the 

circumstances in which states may 

invoke RULOF to deviate from the BSER 

and degree of emission limitation 

determinations the EPA has made 

pursuant to CAA section 111(a)(1). It 

allows states to consider RULOF to 

apply a less stringent standard of 

performance for a designated facility or 

class of facilities if they demonstrate 

one of the three following 

circumstances: (1) unreasonable cost of 

control resulting from plant age, 

location, or basic process design; (2) 

physical impossibility of installing 

necessary control equipment; or (3) 

other factors specific to the facility (or 

class of facilities) that make application 

of a less stringent standard or final 

compliance time significantly more 

reasonable. 

As discussed in the notice of 

proposed rulemaking, the proposed 

amendments largely retained this 

provision, including the three 

circumstances under which a less 

stringent standard of performance may 

be applied, and provided further 

clarification of what a state must 

demonstrate in order to invoke RULOF 

in a state plan. Specifically, the 

proposed amendments required the 

state to demonstrate that a particular 

facility cannot reasonably apply the 

BSER to achieve the degree of emission 

limitation determined by the EPA, based 

on one or more of the three 

circumstances. The EPA’s proposal 

retained the first circumstance in whole 

and revised the second circumstance to 

add the ‘‘technical infeasibility’’ of 

installing a control as another situation 

in which application of RULOF may be 

appropriate. The proposal further 

clarified the third circumstance for 

invoking RULOF, the existing version of 

which provides that states may invoke 

RULOF when other factors specific to 

the facility make a less stringent 

standard of performance ‘‘significantly 

more reasonable.’’ The EPA proposed to 

revise this circumstance, under which 

the first two circumstances also fall, to 

specify that states may consider RULOF 


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95Although CAA section 111(a)(1) may be read to 

state that the factors enumerated in the 

parenthetical are part of the ‘‘adequately 

demonstrated’’ determination, the D.C. Circuit’s 

case law may be read to treat them as part of the 

‘‘best’’ determination. See Sierra Club v. Costle, 657 

F.2d 298, 330 (D.C. Cir. 1981). Under either 

approach, the EPA’s analysis and ultimate 

determination as to the BSER would be the same. 

In determining the ‘‘best’’ system of emission 

reduction, the EPA also considers the advancement 

of technology, consistent with D.C. Circuit caselaw. 

See id. at 347. 

96See Lignite Energy Council v. EPA, 198 F.3d 

930, 933 (D.C. Cir. 1999), Sierra Club v. Costle, 657 

F.2d 298, 343 (D.C. Cir. 1981), Portland Cement 

Ass’n v. EPA, 513 F.2d 506, 508 (D.C. Cir. 1975). 97 87 FR 79199. 

to apply a less stringent standard if 

circumstances specific to a facility are 

fundamentally different from the 

information the EPA considered in 

determining the BSER. This proposed 

clarification was intended to provide 

clear parameters for developing and 

assessing state plans, as the existing 

third circumstance is vague and 

potentially open-ended. 

The EPA explained at proposal that 

the revisions clarified the RULOF 

provision by tethering a state’s RULOF 

demonstration to the statutory factors 

the EPA considered in the BSER 

determination. As discussed in section 

III.E.1. of this preamble, CAA section 

111(a)(1) gives the EPA the 

responsibility of determining the BSER 

and degree of emission limitation that is 

required of designated facilities in the 

source category; the EPA endeavors, to 

the extent reasonably practicable based 

on the information before it, to 

promulgate determinations that are 

achievable for every designated facility 

covered by an EG. Per the statutory 

requirements, the EPA determines the 

BSER by first identifying control 

methods that it considers to be 

adequately demonstrated and then 

determining which is the best system of 

emission reduction by evaluating the 

statutory factors: (1) the cost of 

achieving such reduction, (2) nonair 

quality health and environmental 

impacts, (3) energy requirements, and 

(4) the amount of emission reductions.95

The EPA’s BSER determination thus 

represents a system that is ‘‘adequately 

demonstrated’’ and reasonable for 

sources broadly within the source 

category; CAA section 111(a)(1) requires 

that standards of performance must 

reflect the degree of emission limitation 

that is achievable through application of 

the BSER. 

In considering the BSER, the D.C. 

Circuit has stated that to be ‘‘adequately 

demonstrated,’’ the system must be 

‘‘reasonably reliable, reasonably 

efficient, and . . . reasonably expected 

to serve the interests of pollution 

control without becoming exorbitantly 

costly in an economic or environmental 

way.’’ Essex Chem. Corp. v. 

Ruckelshaus, 486 F.2d 427, 433 (D.C. 

Cir. 1973). Thus, in making the BSER 

determination, the EPA must evaluate 

whether a system of emission reduction 

is ‘‘adequately demonstrated’’ for the 

source category or sub-category based 

on the physical possibility and technical 

feasibility of control. Similarly, the 

court has interpreted CAA section 

111(a)(1) as using reasonableness in 

light of the statutory factors as the 

standard in evaluating cost, so that a 

control technology may be considered 

the ‘‘best system of emission reduction 

. . . adequately demonstrated’’ if its 

costs are reasonable (i.e., not exorbitant, 

excessive, or greater than the industry 

can bear), but cannot be considered the 

BSER if its costs are unreasonable.96 In 

light of the statutory factors the EPA is 

required to consider, it follows that 

most designated facilities within the 

source category or subcategory should 

be able to implement the BSER at a 

reasonable cost to achieve the degree of 

emission limitation determined by the 

EPA. Consideration of RULOF is 

appropriate only for particular sources 

for which implementing the BSER to 

achieve that degree of emission 

limitation would impose unreasonable 

costs or would otherwise not be feasible 

due to facility-specific circumstances 

that are not applicable to the broader 

source category (or subcategories) and 

that the EPA did not consider in 

determining the BSER. 

For example, if the EPA applied a 

specific cost threshold in determining 

the BSER, application of RULOF based 

on cost would only be appropriate 

where the cost of achieving the 

associated degree of emission limitation 

at a particular designated facility is 

unreasonably high relative to the costs 

the EPA considered for the BSER. Or, by 

way of further example, if the EPA were 

to determine that a specific back-end 

control technology is adequately 

demonstrated and the BSER for a source 

category, a state may need to evaluate 

whether it would be physically possible 

to install that control technology at a 

designated facility given the particular 

size and physical constraints of that 

facility. Application of RULOF to 

deviate from the EPA’s determinations 

pursuant to CAA section 111(a)(1) may 

be appropriate, e.g., where the state 

could show that the cost of achieving 

the degree of emission limitation would 

be significantly higher at a specific 

designated facility than the cost-per-ton 

EPA considered in setting the BSER, or 

that a specific designated facility does 

not have adequate space to reasonably 

accommodate the installation of the 

BSER and the facility cannot reasonably 

achieve the degree of emission 

limitation using a different control 

technology. The EPA proposed to 

require states to hew to the same types 

of factors and analyses the EPA’s 

considered in its BSER determination 

when demonstrating that the EPA’s 

determinations are not reasonable for a 

particular designated facility; the 

Agency explained that this would be 

consistent with the statutory framework 

under which RULOF is a limited 

exception to the level of stringency 

otherwise required by the BSER.97

Related to the proposed revisions at 

40 CFR 60.24a(e), the EPA also 

proposed to add new § 60.24a(g) to the 

regulations, which would explicitly 

provide that a state plan may not apply 

a less stringent standard of performance 

in cases where a designated facility 

cannot reasonably apply the BSER to 

achieve the degree of emission 

limitation determined by the EPA, but 

can reasonably implement a different 

technology or other system to achieve 

that same degree of emission limitation. 

This is consistent with the statutory 

framework, which does not require 

sources to implement the EPA’s BSER 

but rather permits states to allow their 

sources to comply with their standards 

of performance using systems of their 

choosing. 

The EPA received a range of 

comments on the proposed revisions to 

the threshold circumstances for 

invoking RULOF to apply a lessstringent standard of performance. Some 

commenters agreed with the EPA that 

the existing criteria are not specific or 

clear enough to ensure that RULOF is 

invoked only when a designated facility 

cannot achieve the degree of emission 

limitation that the EPA has determined 

pursuant to section 111(a)(1). Several 

commenters supported the EPA’s 

proposal that application of RULOF is 

only appropriate where a facility cannot 

reasonably apply the BSER to achieve 

the degree of emission limitation 

determined by the EPA based on 

fundamental differences between that 

facility and the factors the EPA 

considered in the BSER determination. 

Some commenters also urged the EPA to 

explicitly apply the ‘‘fundamentally 

different’’ standard to all three 

circumstances under 40 CFR 60.24a(e). 

However, other commenters argued 

that the EPA cannot preclude states 

from considering factors specific to 

particular facilities on the basis that the 

EPA did not consider those factors in 


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98The circumstances for invoking RULOF in the 

existing subpart Ba provision at 40 CFR 60.24a(e) 

are identical to those in the original variance 

provision of subpart B at 40 CFR 60.24(f). 

99See the discussion in section III.E.3.b. of this 

preamble. 

100 590 F.2d 1011 (D.C. Cir. 1978). 

101 Id. at 1039. 

102 Id. at 1035. 

determining the BSER, and that the 

‘‘fundamentally different’’ standard 

unlawfully narrows states’ 

consideration of site-specific factors 

under the third RULOF criterion. Some 

commenters further contended that 

states should have wide latitude and 

flexibility to consider RULOF and that 

the EPA lacks authority to restrict states’ 

abilities to apply RULOF in 

circumstances they deem appropriate. 

The EPA also received a request from 

one commenter asking the Agency to 

clarify how the proposed provisions at 

40 CFR 60.24a(e) and (g) interact with 

each other. 

The EPA is finalizing the provisions 

for invoking RULOF at 40 CFR 60.24a(e) 

with clarifying revisions relative to 

proposal. Based on these changes, the 

proposed addition of 40 CFR 60.24a(g) 

is redundant; the EPA is therefore not 

finalizing this provision. 

These revisions to 40 CFR 60.24a(e) 

are necessary to ensure that state plans 

comply with CAA section 111(d). As 

explained above, the EPA’s 

determination of the degree of emission 

limitation achievable through 

application of the BSER is the level of 

stringency required by CAA section 

111(d), unless it can be demonstrated 

that something about the EPA’s 

determination does not hold true for a 

particular designated facility. The 

enumerated circumstances for invoking 

RULOF in 40 CFR 60.24a(e) mirror the 

information the EPA considers in 

making its BSER and degree of emission 

limitation determination pursuant to 

CAA section 111(a)(1): information 

related to determining that a system is 

adequately demonstrated (including 

physical possibility and technical 

feasibility), the cost of achieving 

emission reductions, and other factors, 

which include nonair quality health and 

environmental impacts and energy 

requirements. Thus, the long-standing 

RULOF provision 98 is formulated for 

states to examine, at a minimum, the 

same factors the EPA considered in 

determining the BSER in order to 

determine the reasonableness of the 

EPA’s BSER and degree of emission 

limitation as it applies to a particular 

designated facility. In this action, the 

EPA is clarifying the circumstances in 

40 CFR 60.24a(e) for invoking RULOF in 

order to provide more objective and 

consistent criteria that will aid both 

states and the EPA in developing and 

reviewing standards of performance 

consistent with CAA section 111(d), as 

well as ensure the equitable treatment of 

states and sources that avail themselves 

of the RULOF provision. 

The EPA disagrees with commenters 

who argued that the proposed revisions 

to the third circumstance unlawfully 

constrain states’ authority to invoke 

RULOF. On the contrary, the EPA 

believes these revisions provide 

necessary clarity to ensure that states 

invoke RULOF in appropriate 

circumstances. First, as discussed more 

fully in section III.E.2. of this preamble, 

Congress directed the EPA to 

promulgate regulations for the 

submission of state plans that ‘‘permit’’ 

states to consider RULOF. Rather than 

granting states unfettered discretion to 

consider RULOF in applying standards 

of performance, the statute directs the 

EPA to establish regulations describing 

the ‘‘permissible’’ use of such 

consideration. Thus, the EPA has the 

authority and obligation to guide states’ 

consideration of RULOF. 

Second, the revisions to 40 CFR 

60.24a(e) provide a clear and easily 

replicable standard for when it is 

appropriate to apply a less stringent 

standard of performance: when there are 

fundamental differences between the 

information the EPA considered in 

determining the degree of emission 

limitation and the information specific 

to a facility that make the EPA’s degree 

of emission limitation unreasonable for 

the facility. In addition to clarifying the 

circumstances under which 

consideration of RULOF is appropriate, 

this standard also provides greater 

specificity that will aid both states and 

the EPA in implementing the provision. 

This standard is further consistent with 

statutory purpose, structure, and history 

of CAA section 111(d), under which the 

generally applicable requirement is the 

degree of emission limitation 

determined by the EPA and RULOF 

serves as a variance to that 

requirement.99 Moreover, the revisions 

to 40 CFR 60.24a(e) will provide a 

framework for the EPA to use when 

considering any requests for less 

stringent standards of performance 

when the Agency is promulgating a 

Federal plan, which is again critical to 

ensuring both the equitable treatment of 

states and sources and the integrity of 

an EG’s emission reduction purpose. 

This revision will additionally 

provide the EPA with clear criteria to 

use when evaluating any invocation of 

RULOF in state plans to determine 

whether providing a less-stringent 

standard of performance is consistent 

with the statutory framework and 

therefore approvable as ‘‘satisfactory.’’ 

As noted above, it provides an objective, 

replicable benchmark against which to 

assess states’ plans, which can be 

further elaborated on in individual EGs. 

The ‘‘fundamentally different’’ 

standard ensures that RULOF is invoked 

for circumstances where application of 

the statutory factors would lead to a 

result that is outside the realm of what 

the EPA considered reasonable in 

determining the BSER. The EPA makes 

BSER determinations on a source 

category, or sub-category, basis. 

Necessarily, therefore, the Agency 

considers information relevant to 

potential BSERs for representative, 

average units or as average values for 

the set of designated facilities. Implicit 

in an EPA determination that a system 

is the BSER based on average, 

representative information is a 

determination that values around those 

average representative values are also 

reasonable, including some portion of 

unit-specific values that will deviate 

from but are not significantly different 

than the average representative values. 

Therefore, in order to justify deviating 

from the EPA-determined degree of 

emission limitation, the circumstances 

of a particular source must be not just 

different but fundamentally different 

from those the Agency considered in 

determining the BSER. 

Furthermore, as explained at 

proposal, the ‘‘fundamentally different’’ 

standard is also consistent with other 

variance provisions that courts have 

upheld for environmental statutes. For 

example, in Weyerhaeuser Co. v. 

Costle,100 the court considered a 

regulatory provision promulgated under 

the Clean Water Act (CWA) that 

permitted owners to seek a variance 

from the EPA’s national effluent 

limitation guidelines under CWA 

sections 301(b)(1)(A) and 304(b)(1). The 

EPA’s regulation permitted a variance 

where an individual operator 

demonstrates a ‘‘fundamental 

difference’’ between a CWA section 

304(b)(1)(B) factor at its facility and the 

EPA’s regulatory findings about the 

factor ‘‘on a national basis.’’ 101 The 

court upheld this standard as ensuring 

a meaningful opportunity for an 

operator to seek dispensation from a 

limitation that would demand more of 

the individual facility than of the 

industry generally, but also noted that 

such a provision is not a license for 

avoidance of the Act’s strict pollution 

control requirements.102


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103 87 FR 79199. 

104 84 FR 32520, 32577 (July 8, 2019). 

105Memorandum, ‘‘Redline/Strikeout for 

proposed amendments to 40 CFR 60 Subpart Ba: 

Adoption and Submittal of State Plans for 

Designated Facilities,’’ Docket ID No, EPA–HQ– 

OAR–2021–0527–0035. 

106See 40 CFR 60.24(f). 107 87 FR 79199. 

The EPA is revising the regulatory 

text of 40 CFR 60.24a(e) relative to 

proposal to explicitly provide that the 

‘‘fundamentally different’’ standard 

applies to all three categories of 

circumstances for invoking RULOF. 

This change is consistent with the stated 

intent at proposal; for example, the EPA 

proposed ‘‘to require that, in order to 

demonstrate that a designated facility 

cannot reasonably meet the presumptive 

level of stringency based on one of these 

three criteria, the state must show that 

implementing the BSER is not 

reasonable for the designated facility 

due to fundamental differences between 

the factors the EPA considered in 

determining the BSER, such as cost and 

technical feasibility of control and 

circumstances at the designated 

facility.’’ 103 As explained above, in 

order to be consistent with the statutory 

framework, the fundamentally different 

standard necessarily applies to any 

consideration that may be cause to 

invoke RULOF to provide a lessstringent standard of performance. 

There may be instances in which the 

EPA has not considered, in making its 

BSER determination, a circumstance 

that makes the BSER unreasonable for a 

particular facility because that 

circumstance is not applicable to the 

average or typical designated facility in 

the source category. Where the EPA did 

not consider a circumstance that is 

relevant to a particular designated 

facility and that circumstance causes the 

BSER to be unreasonable for that facility 

due to one or more of the reasons 

enumerated in 40 CFR 60.24a(e), a state 

may find there is a fundamental 

difference from the information the EPA 

considered in determining the degree of 

emission limitation achievable through 

application of the BSER. That is, if the 

EPA did not consider any information 

pertaining to a certain circumstance in 

making its determination, facilityspecific information relevant to that 

circumstance that demonstrates that 

achieving the degree of emission 

limitation is unreasonable pursuant to 

40 CFR 60.24a(e) may be 

‘‘fundamentally different’’ from the 

information the EPA considered. The 

EPA notes that, in many cases, facilityspecific circumstances can be 

considered in terms of differences in 

cost. For example, an issue of the 

technical feasibility of implementing a 

control to achieve a certain degree of 

emission limitation may, at its root, be 

an issue of being able to achieve that 

degree of emission limitation at a 

reasonable cost. Because cost is 

generally a more quantifiable and 

replicable metric, where possible the 

EPA expects states to include the 

impacts of any facility-specific 

circumstances in the cost calculation, 

rather than evaluating those 

circumstances under a different factor or 

consideration. 

The EPA is also finalizing its 

proposed clarifying revisions to 40 CFR 

60.24a(e) with further updates. The 

existing provision in subpart Ba was not 

clear, unless it was read directly in 

conjunction with 40 CFR 60.24a(c), that 

its specific purpose is application of less 

stringent standards of performance 

pursuant to consideration of RULOF; it 

did not mention less stringent standards 

until 40 CFR 60.24a(e)(3).104 The EPA 

therefore proposed and is finalizing 

revisions so that the provision’s purpose 

is now clearly stated at the outset. The 

EPA is also making two further 

revisions relative to the proposed 40 

CFR 60.24a(e). First, it is adding back in 

language allowing the RULOF provision 

to be used to provide a compliance 

schedule longer than otherwise required 

by an applicable emission guideline. In 

proposing to revise 40 CFR 60.24a(e), 

the EPA inadvertently deleted the 

phrase ‘‘that make application of a less 

stringent . . . final compliance time 

significantly more reasonable’’ in the 

document containing redline/strikeout 

of the subpart Ba regulations.105 It was 

not the EPA’s intent to preclude the use 

of RULOF to provide a longer 

compliance schedule; this has been part 

of the provision since the original 

variance in 1975.106 However, as the 

language pertinent to providing a longer 

compliance time no longer fits in its 

original sub-paragraph, the EPA is 

adding this allowance back elsewhere in 

40 CFR 60.24a(e). 

Second, the EPA is revising this 

provision relative to proposal to change 

the circumstances under which 

invoking RULOF is appropriate from the 

state demonstrating that ‘‘the facility 

cannot reasonably apply the best system 

of emission reduction to achieve the 

degree of emission limitation 

determined by the EPA . . .’’ to the 

state demonstrating that ‘‘the facility 

cannot reasonably achieve the degree of 

emission limitation determined by the 

EPA. . . .’’ At proposal, the EPA 

explained that ‘‘the state must show that 

implementing the BSER is not 

reasonable for the designated facility 

due to fundamental differences between 

the factors the EPA considered in 

determining the BSER, such as cost and 

technical feasibility of control and 

circumstances at the designated 

facility.’’ 107 However, it is not sufficient 

that a facility not be able to implement 

the BSER; the state must demonstrate 

that the facility cannot otherwise 

reasonably achieve the EPA’s degree of 

emission limitation (for example, 

through a different system of emission 

reduction) in order for a facility to be 

eligible for a less stringent standard of 

performance. This is consistent with the 

definition of ‘‘standard of performance’’ 

in CAA section 111(a)(1), which is a 

‘‘standard for emissions of air 

pollutants’’ that ‘‘reflects the degree of 

emission limitation achievable through 

application of the [BSER],’’ as opposed 

to a standard requiring the application 

of the BSER. That is, the statute requires 

a certain degree of emission limitation, 

not the use of a particular technology. 

Therefore, the fact that a facility cannot 

apply the BSER on its own is not 

sufficient to invoke RULOF. 

The EPA believes that simplifying the 

language in 40 CFR 60.24a(e) will 

reduce confusion about the ultimate 

circumstances under which invoking 

RULOF is appropriate: where a 

particular facility cannot meet the 

degree of emission limitation 

determined by the EPA. Because the 

degree of emission limitation is based 

on the EPA’s BSER determination, the 

information the EPA considered in 

determining the BSER remains the 

touchstone for determining when a 

particular facility cannot reasonably 

achieve the degree of emission 

limitation in the applicable emission 

guideline. Furthermore, given that the 

BSER presumptively reflects a system 

that is adequately demonstrated and 

reasonable for all designated facilities 

within a source category or subcategory, 

the EPA anticipates that in many if not 

most instances a state considering 

RULOF will in fact be evaluating the 

reasonableness of applying the BSER to 

achieve the degree of emission 

limitation. However, even if the state is 

evaluating the use of a different system 

to achieve the degree of emission 

limitation determined by the EPA, the 

factors and information the EPA 

considered in the EG, e.g., cost 

effectiveness, will remain relevant to 

this inquiry. 

As a corollary to this change, the EPA 

is not finalizing the provision proposed 

at 40 CFR 60.24a(g), which would have 

provided that a state could not apply a 

less stringent standard of performance 

where a facility could reasonably 


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108 87 FR 79200 n.46. 

109States intending to apply a less-stringent 

standard of performance pursuant to RULOF would 

include all information, demonstrations, etc. 

necessary to satisfy 40 CFR 60.24a(e) through (h) in 

their state plan submissions. The EPA will first 

review a state’s demonstration that invocation of 

RULOF pursuant to 40 CFR 60.24a(e) is appropriate 

for a particular designated facility against the 

applicable requirements. If the EPA finds that 

demonstration satisfactory, it will proceed to 

evaluate the standard of performance for that 

facility applied pursuant to 40 CFR 60.24a(f). 

implement a system of emission 

reduction other than the BSER to 

achieve the degree of emission 

reduction determined by the EPA. This 

provision is redundant now that the 

EPA is clarifying in 40 CFR 60.24a(e) 

that states may apply less stringent 

standards of performance only when 

they demonstrate that a facility cannot 

reasonably achieve the degree of 

emission limitation determined by the 

EPA. 

Both subpart B at 40 CFR 60.24(f) and 

the existing regulations of subpart Ba at 

40 CFR 60.24a(e) provide that use of 

RULOF is appropriate if a state 

demonstrates that one of the three 

circumstances is met ‘‘with respect to 

each facility (or class of such facilities).’’ 

In the notice of proposed rulemaking for 

this action, the EPA stated that, ‘‘[t]o the 

extent that a state seeks to apply RULOF 

to a class of facilities that the state can 

demonstrate are similarly situated in all 

meaningful ways, the EPA proposes to 

permit the state to conduct an aggregate 

analysis of [the five BSER factors] for 

the entire class.’’ 108 The EPA is 

reiterating in this final rule that 

invoking RULOF and providing a lessstringent standard or performance or 

longer compliance schedule for a class 

of facilities is only appropriate where all 

the facilities in that class are similarly 

situated in all meaningful ways. That is, 

they must not only share the 

circumstance that is the basis for 

invoking RULOF, they must also share 

all other characteristics that are relevant 

to determining whether they can 

reasonably achieve the degree of 

emission limitation determined by the 

EPA in the applicable EG. For example, 

it would not be reasonable to create a 

class of facilities for the purpose of 

RULOF on the basis that the facilities do 

not have space to install the EPA’s BSER 

control technology if some of them are 

able to install a different control 

technology to achieve the degree of 

emission limitation in the EG. Similarly, 

it would not be appropriate for a state 

to conduct a single evaluation pursuant 

to 40 CFR 60.24a(f) to apply the same 

less stringent standard of performance 

to a class of facilities if individual 

facilities within that class have different 

characteristics that could result in 

different standards of performance. The 

evaluation of when it is appropriate to 

create a class of facilities is extremely 

source-sector and EG-specific; the EPA 

will address circumstances in which it 

may or may not be permissible to group 

facilities for purposes of RULOF in 

individual EGs. 

In summary, the EPA is finalizing its 

proposed revisions to 40 CFR 60.24a(e) 

with additional clarifications. The first 

is to reflect that the ‘‘fundamentally 

different’’ standard applies to all three 

circumstances for invoking RULOF. 

This clarification reinforces that 

invocation of RULOF is appropriate 

when the circumstances of a particular 

designated facility are fundamentally 

different from those the EPA considered 

such that the facility cannot reasonably 

achieve the degree of emission 

limitation the EPA determined pursuant 

to CAA section 111(a)(1). Second, the 

EPA is revising the circumstances under 

which invoking RULOF is appropriate 

from a demonstration that a facility 

cannot reasonably apply the BSER to 

achieve the degree of emission 

limitation determined by the EPA to a 

demonstration that the facility cannot 

reasonably achieve the degree of 

emission limitation determined by the 

EPA. This change is intended to 

simplify and clarify the provision as it 

is the degree of emission limitation 

determined by the EPA, not the system 

used to achieve it, that has always been 

the relevant consideration under CAA 

sections 111(d) and 111(a)(1). Third, the 

EPA is clarifying the provision that 

states may use RULOF to provide for a 

longer compliance timeline as well as 

less-stringent standards of performance, 

which was inadvertently omitted from 

the proposed regulatory text. In general, 

the EPA is revising 40 CFR 60.24a(e) to 

provide more objective and consistent 

criteria for when it is appropriate to 

invoke RULOF in order to guide states 

in applying standards of performance to 

particular designated facilities and the 

EPA in evaluating state plans. The EPA 

is not finalizing proposed 40 CFR 

60.24a(g), as this provision is now 

superfluous given the updates to 40 CFR 

60.24a(e). 

The EPA acknowledges that what is 

considered reasonable in light of the 

statutory factors is a fact-specific 

inquiry based on the source category 

and pollutant that is being regulated 

pursuant to a particular EG, and that the 

EPA cannot anticipate and address all 

circumstances that may arise in these 

general implementing regulations. Thus, 

the EPA may consider additional factors 

and establish additional parameters 

governing the consideration of RULOF, 

including what deviations from the 

EPA’s determinations may be within the 

range of reasonable versus deviations 

that constitute fundamental differences 

between facility-specific circumstances 

and the EPA’s degree of emission 

limitation determination, in a particular 

EG. 

b. Calculation of a Standard Which 

Accounts for Remaining Useful Life and 

Other Factors 

If a state has demonstrated, pursuant 

to 40 CFR 60.24a(e), that there is a 

fundamental difference between the 

information the EPA considered in the 

applicable EG and the information 

specific to a particular source that 

makes it unreasonable for that source to 

achieve the degree of emission 

limitation, the state may then apply a 

less stringent standard of 

performance.109 The current RULOF 

provision, 40 CFR 60.24a(e), does not 

specify how a less stringent standard is 

to be calculated and applied. While this 

provision stands on its own and permits 

states to consider RULOF to apply a less 

stringent standard of performance, the 

lack of a process for determining any 

such standards makes it difficult for 

states to know whether the result will be 

approvable and additionally makes it 

difficult for the EPA to review less 

stringent standards in a consistent and 

equitable manner. In order to provide 

clarity and ensure the integrity of the 

emission reduction purpose of CAA 

section 111(d), as well as to ensure the 

equitable treatment of designated 

facilities across states, the EPA is 

promulgating a framework in 40 CFR 

60.24a(f) for the calculation of a 

standard of performance that accounts 

for RULOF. As explained in this section 

of the preamble, the process the EPA is 

finalizing differs from the proposed 

framework, but the material components 

of calculating and applying a less 

stringent standard of performance, and 

the underlying purpose and direction of 

the EPA’s framework, remain the same. 

The EPA proposed to require that 

states determine a source-specific BSER 

for each designated facility for which 

RULOF has been invoked pursuant to 40 

CFR 60.24a(e) and include a standard of 

performance that reflects the degree of 

emission limitation achievable through 

application of that BSER in their state 

plans. The notice of proposed 

rulemaking explained that the statute 

requires the EPA to determine the BSER 

by considering emission control 

methods that it finds to be adequately 

demonstrated, and then determining 

which is the best system of emission 


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110The D.C. Circuit has stated that in determining 

the ‘‘best’’ system, the EPA must take into account 

‘‘the amount of air pollution’’ reduced, see Sierra 

Club v. Costle, 657 F.2d 298, 326 (D.C. Cir. 1981), 

and the role of ‘‘technological innovation.’’ Id. at 

347. 

111See section III.E.3.a. of this preamble. The EPA 

expects to address the appropriateness of invoking 

RULOF and applying less-stringent standards to a 

class of facilities in individual EGs. 

112Oxford English Dictionary, https://

www.oed.com/search/advanced/

Meanings?textTermText0=apply&text

TermOpt0=WordPhrase, last accessed Nov. 1, 2023. 

113 Id., https://www.oed.com/search/advanced/

Meanings?textTermText0=consideration&

textTermOpt0=WordPhrase, last accessed Nov. 1, 

2023. 

reduction by evaluating (1) the cost of 

achieving such reduction, (2) nonair 

quality health and environmental 

impacts, (3) energy requirements, and 

(4) the amount of reductions.110 To be 

consistent with this statutory construct, 

the EPA proposed to require that in 

determining a source specific BSER for 

a designated facility (or class of such 

facilities 111), a state must also consider 

all these factors in applying RULOF for 

that source. 

Specifically, the EPA proposed that a 

state in its plan submission would 

identify all control technologies 

available for the source and evaluate the 

BSER factors for each technology, using 

the same factors and evaluation metrics 

as the EPA did in developing the EG. 

For example, if the EPA evaluated the 

cost factor using the evaluation metric 

of capital costs in determining the 

BSER, the EPA proposed that the state 

must do the same in evaluating a control 

technology for an individual designated 

facility, rather than selecting a different 

evaluation metric for cost. The state 

would then calculate the emission 

reductions that applying the sourcespecific BSER would achieve and select 

the standard of performance which 

reflects this degree of emission 

limitation. This standard would be in 

the form or forms (e.g., numerical ratebased emission standard) as required by 

the specific EG. 

While the EPA proposed to require 

that states identify all control 

technologies or other systems of 

emission reduction available for the 

source and evaluate each system using 

the same factors and evaluation metrics 

as the EPA did in determining the 

BSER, it also solicited comment on 

whether there are additional factors, not 

already accounted for in the BSER 

analysis, that the EPA should permit 

states to consider in determining a less 

stringent standard of performance. The 

EPA further solicited comment on 

whether it should provide that the 

manner in which the EPA conducted 

the BSER analysis would be a 

presumptively approvable framework 

for applying a less-stringent standard 

rather than requirements and, if so, 

what different approaches states might 

use to evaluate and identify less 

stringent standards of performance. 

The EPA also noted at proposal that 

CAA section 111(d) requires that state 

plans include measures that provide for 

the implementation and enforcement of 

a standard of performance. This 

requirement applies to any standard of 

performance established by a state, 

including one that accounts for RULOF. 

Such measures include monitoring, 

reporting, and recordkeeping 

requirements, as required by 40 CFR 

60.25a, as well as any additional 

measures specified under an applicable 

EG. In particular, any standard of 

performance that accounts for RULOF is 

also subject to the requirement under 

subpart Ba that the state plan 

submission include a demonstration 

that each standard is quantifiable, nonduplicative, permanent, verifiable, and 

enforceable. 40 CFR 60.27a(g)(3)(vi). 

The EPA did not reopen these existing 

requirements of subpart Ba in this 

rulemaking. 

The EPA received both comments in 

support of and comments opposed to 

the proposed requirements for 

calculating facility-specific standards of 

performance under RULOF. Some 

commenters supported the addition of a 

regulatory framework for facilityspecific BSER analysis and stated that 

the BSER factors encompass all relevant 

information to a state’s determination of 

an appropriate standard for a facility. 

Other commenters opposed the 

proposed framework. Comments in 

opposition largely fell into two 

categories: Some commenters asserted 

there is no basis in the statute for 

requiring states to conduct facilityspecific BSER analyses pursuant to 

RULOF and, relatedly, that the EPA 

should not put restrictions on what 

states may consider in applying a less 

stringent standard of performance for a 

particular source but should rather 

maintain the wide latitude afforded to 

states under CAA section 111. Others 

stated that the EPA’s proposed 

requirements would constitute a heavy 

lift for state agencies and would require 

substantial work for states to 

implement. In this vein, one commenter 

requested that the EPA not require states 

to evaluate, as part of their facilityspecific BSER analyses, control 

technologies that the Agency has 

previously excluded from the BSER on 

the basis of technological or economic 

feasibility. Rather, the only control 

technologies that states should be 

required to evaluate are technologies 

that result in less emission reduction 

than the technology the EPA determined 

to be the BSER. 

As explained below, the EPA 

disagrees with comments that there is 

no basis for putting a framework in 

place for states and the Agency to use 

in applying and evaluating less stringent 

standards of performance. The EPA 

believes that such a framework is well 

supported by the statutory purpose, text, 

and context of the RULOF provision. In 

particular, after considering the 

comments, the EPA believes that the 

purpose, text, and context support a 

requirement that states (or the EPA in 

the case of a Federal plan) calculate and 

apply a standard of performance that 

varies from the EPA’s degree of 

emission limitation in the applicable 

emission guideline only to the extent 

necessary to address the fundamental 

difference that is the basis for invoking 

RULOF. 

First, providing a framework for 

calculating less stringent standards of 

performance is consistent with the text 

of CAA section 111(d) and is responsive 

to Congress’s directive in that provision 

that the Agency prescribe regulations 

establishing a procedure for state plans, 

including regulations that ‘‘permit’’ 

states ‘‘in applying’’ a standard of 

performance to a particular source to 

‘‘take into consideration’’ RULOF. The 

provisions the EPA is promulgating in 

this action set out a procedure—the 

series of steps and considerations states 

must undertake to apply a less stringent 

standard of performance. As described 

in section III.E.2. of this preamble, to 

‘‘permit’’ something means to allow or 

give consent for that thing to occur. In 

this case, the EPA is prescribing the 

procedures that allow for states to apply 

less stringent standards of performance. 

To ‘‘apply’’ means ‘‘to put to a special 

use or purpose’’ or ‘‘put into practical 

operation,’’ 112 and ‘‘consideration’’ 

means ‘‘the action of taking into 

account.’’ 113 Thus, the state’s 

authorization to ‘‘apply[]’’ a standard of 

performance to any particular source, 

‘‘tak[ing] into consideration’’ RULOF, 

means the state may particularize a 

standard of performance for a given 

source by accounting for remaining 

useful life and other factors where there 

are fundamental differences between the 

information specific to a facility and the 

information the EPA considered in 

determining the degree of emission 

limitation achievable through 

application of the BSER. In doing so, the 

state must remain as consistent as 

possible with that degree of emission 

limitation in light of what the Supreme 


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114West Virginia v. EPA, 142 S. Ct. at 2601. 

115 40 CFR 60.24(c); 40 CFR 60.24a(c); see 39 FR 

36102. 

116 40 CFR 60.24(f); 40 FR 53344. 

117 40 FR 53344. 

118See Lorillard v. Pons, 434 U.S. 575, 580 (1978) 

(‘‘Congress is presumed to be aware of an 

administrative or judicial interpretation of a statute 

and to adopt that interpretation when in re-enacts 

a statute without change.’’). 

119 In the notice of proposed rulemaking for this 

rule, the EPA stated that ‘‘[t]here are noticeable 

differences between the subpart B variance 

provision and the CAA section 111(d) RULOF 

provision that indicate Congress did not intend to 

incorporate and ratify all aspects of the EPA’s 

regulatory approach when amending CAA section 

111(d) in 1977.’’ The EPA thus proposed to 

conclude that it could not ‘‘clearly ascertain 

whether the statutory RULOF provision ratified the 

variance provision under subpart B . . . .’’ 87 FR 

79176, 79205 (Dec. 23, 2022). Upon further 

consideration, however, the EPA believes the most 

reasonable interpretation of the statutory RULOF 

provision, given its history and context, is that 

Congress intended it to authorize the EPA to 

provide variances from the required degree of 

emission limitation on a case-by-case basis. 

However, the EPA agrees with its assessment at 

proposal that Congress did not necessarily 

incorporate or ratify specific aspects of the Agency’s 

1975 variance provision; it is reasonable that 

Congress would not have codified the precise 

regulations that the EPA promulgated in 1975 and 

instead leave the Agency space to revise those 

regulations as needed, as it is did in 2019 and is 

doing in the present rule. 

120The ACE rule, in which the EPA promulgated 

subpart Ba in 2019, declined to refer to the RULOF 

provision as a ‘‘variance,’’ apparently because the 

term conflicted with that rule’s view that RULOF 

would be used to establish standards of 

performance as a general matter. 84 FR 32520,32570 

n. 291 (July 8, 2019). The ACE rule misunderstood 

the RULOF provision. As explained throughout 

section III.E. of this preamble, this provision 

authorizes a state to depart from the degree of 

emission limitation the EPA determines under CAA 

section 111(a)(1) when applying a standard of 

performance to a particular source pursuant to 

consideration of RULOF. As the 1975 regulations 

indicated, 40 FR 53332, 53344 (Nov. 17, 1975), it 

is appropriate to call this type of departure or 

exception a ‘‘variance.’’ 

121The EPA explains the reasons it believes it is 

now necessary to provide the second part of the 

process for this variance—how to calculate a less 

stringent standard of performance—in section 

III.E.2. of this preamble. 

122As another example, CWA section 301(c) 

provides that the EPA may modify the best 

available technology requirements for particular 

sources if a facility can demonstrate that a modified 

standard will (1) represent the maximum use of 

technology within the economic capability of the 

owner or operator and (2) will result in reasonable 

further progress toward the elimination of the 

discharge pollutants. 

Court has recognized as the EPA’s 

‘‘primary regulatory role in section 

111(d)’’ 114 and the emission reduction 

purpose of CAA section 111. 

Second, the history and context of 

CAA section 111(d) supports the EPA’s 

authority to provide a framework for 

states’ consideration of RULOF. As 

explained in section III.E.2. of this 

preamble, the standards of performance 

that states establish in state plans must 

generally be no less stringent than the 

degree of emission limitation that 

Congress required, which is the degree 

of emission limitation that EPA 

determines in the applicable EG.115

However, in the original 1975 subpart B 

implementing regulations, the EPA 

allowed states to grant variances from 

this degree of emission limitation in 

cases of economic hardship based on 

the age of the plant and other factors, as 

long as the states could justify the 

variances.116 Congress then, in the 1977 

CAA Amendments, included the 

RULOF provision in CAA section 

111(d)(1), which similarly allows states 

to deviate from the EPA’s degree of 

emission limitation based on 

consideration of an existing source’s age 

(i.e., remaining useful life) and other 

factors. 

Congress’s inclusion of the RULOF 

provision in CAA section 111(d)(1) 

should be interpreted as expressing its 

intent to confirm that the EPA has 

authority to promulgate a regulatory 

variance provision, including the 

provision the EPA had, at that time, 

recently promulgated. The EPA, 

following its 1974 proposal of the 

subpart B implementing regulations, 

had received a comment arguing that it 

did not have authority to promulgate 

such a variance provision, to which it 

responded by asserting that it did have 

the authority and explaining that such 

a provision is consistent with CAA 

section 111(d).117 The Courts have held 

that Congress is presumed to be aware 

of an administrative interpretation 

under certain circumstances.118

Accordingly, Congress’s adoption of the 

RULOF provision in the 1977 CAA 

Amendments should be interpreted as 

expressing its intent to make explicit 

under CAA section 111(d) the EPA’s 

authority to promulgate regulations that 

include a variance provision.119

It is also clear that the EPA 

understood the RULOF provision in 

CAA section 111(d)(1) to be a variance 

in the same way it had provided a 

variance in subpart B. This is evidenced 

by the fact that following the 1977 CAA 

Amendments the EPA did not revise its 

1975 regulations, which were premised 

on this understanding, for over forty 

more years.120 This indicates that the 

EPA viewed its 1975 regulations 

granting a variance as authorized under 

the RULOF provision enacted in 1977. 

The regulations the EPA is 

promulgating at 40 CFR 60.24a(f) are 

consistent with the long-held view that 

the Agency’s implementing regulations 

provide a variance. While 40 CFR 

60.24a(e) provides the process for 

invoking this variance, to date the 

regulations have not included the 

second part: how to address a source 

that has qualified for the variance.121

Although variances may operate in 

different ways in the context of different 

statutory and regulatory schemes, it is 

clear from both the language and the 

context of the RULOF provision that 

Congress intended it to provide for 

alternative compliance with CAA 

section 111(d), i.e., a less stringent 

standard of performance, to the extent 

necessary to address the fundamental 

differences between the EPA’s EG and 

the circumstances of a particular 

facility. Such variances are common 

throughout environmental statutes and, 

for the environmental protection aim to 

be achieved, must be crafted so that the 

alternative is as close as possible to the 

statutory standard, even as it departs 

from the generally applicable 

requirement. 

For example, Clean Water Act (CWA) 

section 301(b)(2) requires, in part, 

certain sources to achieve effluent 

limitations consistent with application 

of the best available technology 

economically achievable, which will 

result in reasonable further progress 

toward eliminating the discharge of all 

pollutants. These limitations must be 

determined in accordance with factors 

specified in the statute and are provided 

by either effluent limitation guidelines 

issued by the EPA or the permitting 

authority on a best professional 

judgment basis where no such national 

effluent limitation guidelines exist. 

CWA section 301(n) authorizes the EPA 

to grant variances for existing sources 

from the best available technology 

requirements of its effluent limitation 

guidelines where a facility can 

demonstrate that it is fundamentally 

different with respect to the factors 

(other than cost) specified in the statute 

and considered by the EPA in 

establishing those requirements. CWA 

section 301(n) further requires that, 

where a variance is warranted, the EPA 

must provide an alternative requirement 

that (1) is no less stringent than justified 

by the fundamental difference, and (2) 

will not result in a non-water quality 

environmental impact which is 

markedly more adverse than the impact 

considered in establishing the rule.122

Similarly, section 3004(m)(1) of the 

Resource Conservation and Recovery 

Act (RCRA) requires the EPA to 

promulgate regulations specifying the 

levels or methods of treatment of 

hazardous waste, if any, that 

‘‘substantially diminish the toxicity of 

the waste or substantially reduce the 


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123 40 CFR 268.44. 

124See CAA section 111(d)(1) (requiring that 

states considering RULOF for a particular source 

nonetheless apply a standard of performance to that 

source); 39 FR 36102, 36102 (Oct. 7, 1974) 

(proposed regulations ‘‘provide that States may 

establish less stringent emission standards on a 

case-by-case basis provided that sufficient 

justification is demonstrated in each case’’). 

125Cf. Weyerhauser Co. v. Costle, F.2d 1011, 1035 

(D.C. Cir. 1978) (Clean Water Act variance provision 

‘‘authorizes the Agency to relieve a particular point 

source operator from any demands that the Act does 

not allow the Agency to make of the industry 

generally.’’ However, the point source operator 

must still, consistent with the general statutory 

requirement for the industry, use the best available 

technology economically available and ‘‘the 

variance may not halt progress toward eliminating 

pollution.’’). 

126See 40 CFR 60.22a(b)(2). 

127Cf. Weyerhauser Co. v. Costle, F.2d 1011, 1035 

(D.C. Cir. 1978) (CWA section 304(b)(2)(B) lays out 

likelihood of migration of hazardous 

constituents from the waste so that 

short-term and long-term threats to 

human health and the environment are 

minimized.’’ The EPA has set generally 

applicable regulatory standards for the 

treatment of hazardous waste under 

RCRA section 3004(m)(1). The Agency 

has also has provided regulatorily for 

waste-specific variances in instances in 

which it is not physically possible, or it 

is inappropriate, to treat waste to the 

level specified in the Agency’s 

treatment standard or to treat waste 

using the method the Agency specified 

as the treatment standard.123 In order for 

the EPA to grant a variance, the party 

requesting it must provide an alternative 

waste treatment requirement that is 

sufficient to minimize threats to human 

health and the environment posed by 

disposal of the waste, i.e., that is 

sufficient to satisfy the underlying 

statutory requirement, even though it 

differs from the generally applicable 

treatment standard prescribed by the 

EPA. 

The discussion above highlights 

examples of environmental statutes that 

require adherence to a generally 

applicable standard, but under which 

either Congress or the EPA has 

authorized variances when it is 

impossible or unreasonable for a 

particular regulated entity to achieve 

that standard. For a general statutory 

standard requiring the ‘‘best’’ 

technology or ‘‘substantial’’ progress, 

the variances are an alternative way of 

achieving the statutory standard, as 

opposed to an exemption from that 

standard. In the case of the CWA 

variances, in particular, this means that 

the alternative requirement pursuant to 

the variance constitutes a degree of 

pollutant limitation that deviates as 

little as possible from the EPA’s 

regulation pursuant to that statutory 

standard. That is, the alternative 

requirement constitutes a particular 

regulated entity’s best effort to achieve 

the generally applicable standard. 

The EPA has crafted 40 CFR 60.24a(e) 

and (f) to be a variance in the same vein 

as the CWA and RCRA statutory and 

regulatory provisions discussed above. 

It is clear from both the history and 

plain language of CAA section 111(d)(1) 

that Congress did not provide an 

exemption from regulation, but rather a 

method for providing alternative 

compliance with the general statutory 

requirement of that section.124 CAA 

section 111(d) provides that states must 

submit plans that include ‘‘standards of 

performance,’’ and CAA section 

111(a)(1) defines ‘‘standard of 

performance’’ as ‘‘a standard for 

emissions of air pollutants which 

reflects the degree of emission 

limitation achievable through the 

application of the best system of 

emission reduction which . . . the 

Administrator determines has been 

adequately demonstrated.’’ Thus, the 

underlying statutory standard is the 

degree of emission limitation 

determined by the EPA in the applicable 

EG. A variance from this statutory 

standard is not available if a source can 

reasonably achieve the EPA’s degree of 

emission limitation. If a variance is 

warranted, the alternative requirement, 

i.e., a standard of performance pursuant 

to consideration of RULOF, must be a 

standard for emissions of air pollutants 

that is no less stringent than necessary 

to address the fundamental differences 

identified under 40 CFR 60.24a(e). That 

is, the degree of emission limitation of 

a standard of performance pursuant to 

RULOF must deviate as little as possible 

from the degree of emission limitation 

in the applicable EG.125 Consistent with 

the structure of CAA section 111(d) 

generally, the RULOF provision does 

not prescribe the use of any particular 

system of emission reduction in 

conjunction with a less stringent 

standard of performance but instead 

focuses on ensuring that the degree of 

emission limitation deviates no more 

than necessary; anything less would be 

inconsistent with the general statutory 

framework. 

Thus, 40 CFR 60.24a(f)(1) requires 

that a less stringent standard of 

performance be no less stringent (or 

have a compliance schedule no longer) 

than necessary to address the 

fundamental differences identified 

under 40 CFR 60.24a(e). It also contains 

a framework that states must use, to the 

extent necessary to satisfy that criterion, 

to determine the less stringent standard 

of performance. In some instances, 

determining the standard of 

performance that is no less stringent 

than necessary to address the 

fundamental differences will be 

straightforward and the state will not 

need to undertake the analysis of 

additional systems of emission 

reduction that is laid out in the second 

and third sentences of 40 CFR 

60.24a(f)(1). For example, where the 

BSER the EPA has identified in the 

applicable EG may be implemented at 

the source at either a lower stringency 

or with a longer compliance schedule 

and it is clear that no other system of 

emission reduction will result in greater 

stringency or a shorter schedule, it is 

unnecessary for a state to evaluate other 

systems in order to satisfy the first 

sentence of paragraph (f)(1). In this case, 

the state would simply justify the degree 

of emission limitation or compliance 

schedule as the most stringent or 

shortest reasonably possible. 

However, where a particular source 

cannot implement the types of controls 

that comprise the BSER or where it is 

not apparent that implementation of the 

BSER at lower stringency or with a 

longer compliance schedule will result 

in a standard of performance that is no 

less stringent than necessary, evaluation 

of additional systems of emission 

reduction will be necessary under 40 

CFR 60.24a(f)(1). In this situation, the 

EPA does not believe it is reasonably 

possible to determine a standard of 

performance that satisfies the criterion 

of § 60.24a(f)(1) without considering the 

systems of emission reduction that the 

EPA determined, in the applicable EG, 

have been adequately demonstrated.126

As discussed below, however, it may 

not be necessary for a state to evaluate 

every system of emission reduction that 

the EPA considered. Thus, the EPA is 

requiring that, to the extent necessary to 

determine a standard of performance 

that is no less stringent than necessary, 

states must evaluate the systems of 

emission reduction in the applicable 

EG. As further discussed below, the EPA 

expects states will leverage the 

information and analysis the Agency 

has provided in that EG for their 

evaluations, particularizing that 

information to the circumstances of the 

particular facility as needed. 

Similarly, it is not reasonably possible 

to craft a standard of performance that 

is no less stringent than necessary to 

address a fundamental difference 

between a particular facility’s 

circumstances and the information the 

EPA considered in determining the 

degree of emission limitation without 

engaging with that information.127 In 


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the minimum factors the EPA must consider in 

determining the best available technology 

economically achievable on a source-category basis. 

In deciding whether a variance sought by a 

particular point source owner represents the 

‘‘maximum use of technology within the economic 

capability of (that) owner, the permit-granting 

agency, and the EPA in supervising that agency, 

must consider the factors laid out in section 

304(b)(2)(B).’’). 

128The D.C. Circuit has stated that in determining 

the ‘‘best’’ system of emission reduction, the EPA 

must also take into account the role of 

‘‘technological innovation.’’ See Sierra Club v. 

Costle, 657 F.2d 298, 347 (D.C. Cir. 1981). However, 

because technological innovation is less likely to be 

relevant at the scale of a single facility than it is 

on a source-category basis, the EPA is not explicitly 

requiring states to consider it under 40 CFR 

60.24a(f)(1). 

129Under 40 CFR 60.24a(f)(1), as finalized in this 

action, states must evaluate the systems of emission 

reduction identified in the applicable EG. The 

EPA’s EGs include systems of emission reduction 

that have been ‘‘adequately demonstrated.’’ There is 

therefore no need for states to revisit the 

‘‘adequately demonstrated’’ consideration. 

However, ‘‘adequately demonstrated’’ includes 

‘‘technical feasibility’’ and the EPA acknowledges 

that systems of emission reduction that are 

adequately demonstrated for the source category 

may not be technically feasible for a particular 

source. The EPA is thus adding ‘‘technical 

feasibility’’ to the list of factors states must consider 

in determining a less stringent standard of 

performance. 

130An ‘‘evaluation metric’’ includes both the form 

of the EPA’s consideration of a factor and any 

threshold or level of reasonableness the EPA 

considered in the applicable EG. 

determining the degree of emission 

limitation in an EG, the EPA considers 

whether available systems of emission 

reduction have been adequately 

demonstrated, the amount of emissions 

they reduce, the cost of achieving such 

reduction, any nonair quality health and 

environmental impacts, and energy 

requirements.128 To evaluate whether a 

state’s less stringent standard of 

performance is no less stringent than 

necessary, both states and the EPA need 

to be able to compare the information 

relevant to the source category (or 

subcategory) with the facility-specific 

information. Additionally, to ensure 

equitable consideration and treatment of 

sources in different states that have 

invoked RULOF to apply less stringent 

standards of performance, it is necessary 

that each state is using a common set of 

factors and metrics as the bases for their 

decisions. Using the factors 129 and 

evaluation metrics 130 that the EPA 

considered in determining the degree of 

emission limitation ensures ‘‘apples-toapples’’ comparisons, both between the 

EPA’s degree of emission limitation and 

a state’s less stringent standard of 

performance and between different 

sources in different states. Thus, to the 

extent that states are evaluating systems 

of emission reduction to determine a 

less stringent standard of performance 

under 40 CFR 60.24a(f)(1), they must 

use the same factors the EPA 

considered, and the evaluation metrics 

the EPA used to consider the factors, in 

doing so. 

For example, assume the EPA 

considered cost using the evaluation 

metric dollars per ton of pollutant 

reduced and concluded that costs of up 

to $500/ton of pollutant reduced are 

reasonable. A state has invoked RULOF 

for a particular source under 40 CFR 

60.24a(e) because, based on that 

source’s shortened remaining useful life, 

the cost, in dollars per ton of pollutant 

reduced, of achieving the degree of 

emission limitation in the applicable EG 

is fundamentally different from $500/ 

ton. The state, in determining a less 

stringent standard of performance 

pursuant to 40 CFR 60.24a(f), must 

evaluate the systems of emission 

reduction in the EG using the cost 

evaluation metric dollars per ton of 

pollutant reduced. In doing so, the state 

would consider the reasonableness of 

the costs of those systems against the 

benchmark of $500/ton. 

The regulations at 40 CFR 60.24a(e) 

also allow states to invoke RULOF based 

on a fundamental difference unrelated 

to cost, e.g., physical impossibility of 

implementing control equipment 

necessary to achieve the EPA’s degree of 

emission limitation. In this instance, a 

state may find that a particular facility’s 

footprint is such that there are no 

systems of emission reduction that 

could be installed at the facility to 

achieve the degree of emission 

limitation in the applicable EG. Under 

40 CFR 60.24a(f)(1), the state would 

evaluate the systems of emission 

reduction in the EG using the factors— 

technical feasibility, amount of emission 

reductions, cost of achieving such 

reductions, nonair quality health and 

environmental impacts, and energy 

requirements—and evaluation metrics 

the EPA considered in order to 

determine the standard of performance 

that is both physically possible for the 

source to achieve and that is no less 

stringent than necessary. 

As explained in section III.E.3.a., 

there may be facility-specific 

circumstances and factors that the EPA 

did not anticipate and consider in the 

applicable EG that make achieving the 

EPA’s degree of emission limitation 

unreasonable for that facility. Such 

facility-specific information may 

constitute an ‘‘other factor specific to 

the facility’’ under 40 CFR 60.24a(e) and 

could potentially represent a 

fundamental difference between the 

information the EPA considered in 

determining the degree of emission 

limitation and the information specific 

to a facility. Such facility-specific ‘‘other 

factors’’ may also be relevant in 

determining and applying a less 

stringent standard of performance. 

Thus, pursuant to the process the EPA 

is finalizing in 40 CFR 60.24a(f)(1), 

states may consider ‘‘other factors 

specific to the facility’’ that were the 

basis of the demonstration under 

paragraph (e) in determining and 

applying a less stringent standard of 

performance. 

In some instances, the fundamental 

difference between the information the 

EPA considered in the applicable EG 

and the information specific to a facility 

will manifest as a difference in whether 

or how an enumerated factor applies to 

a particular facility. For example, 

parasitic load may be an appropriate 

evaluation metric for considering energy 

requirements for some systems of 

emission reduction but not for others, or 

water availability may not have been 

important to the EPA’s consideration of 

nonair quality environmental impacts 

but may be relevant for a source located 

in a particularly water-scarce region. If 

such information represents a 

fundamental difference that make the 

EPA’s degree of emission limitation 

determination unreasonable for a 

particular facility pursuant to 40 CFR 

60.24a(e), it would be reasonable and 

permissible for a state to consider such 

information in applying a less stringent 

standard of performance under 40 CFR 

60.24a(f)(1). 

In addition to ‘‘other factors’’ that the 

EPA did not necessarily consider, there 

may be circumstances in which a 

system of emission reduction that the 

EPA did not consider in the applicable 

EG or that the EPA concluded was not 

adequately demonstrated because, e.g., 

it is not available on a source-category 

wide basis, is available, technically 

feasible, and potentially reasonable for a 

particular facility. 

The EPA is therefore providing in 40 

CFR 60.24a(f)(1) that states may 

consider, in determining a less stringent 

standard of performance, ‘‘other factors 

specific to a facility’’ that were the basis 

for the fundamental difference and 

invoking RULOF under 40 CFR 

60.24a(e), as well as systems of emission 

reduction in addition to those the EPA 

considered in the applicable EG. At the 

same time, however, the EPA in a 

particular EG makes certain judgments 

about which systems are available and 

adequately demonstrated, as well as 

how the factors are reasonably 

considered when evaluating those 

systems for designated facilities within 

the source category. To ensure that any 

additional considerations do not result 

in a standard of performance that 

deviates more than necessary from the 


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131West Virginia v. EPA, 142 S. Ct. at 2601. 

132See 40 FR 53342 (CAA section 111(d)’s 

references to CAA section 110 suggest that Congress 

intended the Administrator to apply some 

substantive criterion to his review of State plans). 

133See 40 CFR 60.24a(c). 

134CAA section 169A(g)(1) and (2). The statutory 

factors that states must use to determine reasonable 

progress are ‘‘costs of compliance, the time 

necessary for compliance, and the energy and 

nonair quality environmental impacts of 

compliance, and the remaining useful life of any 

existing source subject to such requirements.’’ The 

statutory factors for best available retrofit 

technology analysis are: ‘‘costs of compliance, the 

energy and nonair quality environmental impacts of 

compliance, any existing pollution control 

technology in use at the source, the remaining 

useful life of the source, and the degree of 

improvement in visibility which may reasonably be 

anticipated to result from the use of such 

technology.’’ 

135The EPA has also issued extensive and 

detailed guidance for states in conducting 

reasonable progress analyses for sources of visibility 

impairing pollutants. See Guidance on Regional 

Haze State Implementation Plans for the Second 

Implementation Period (2019), available at https:// 

www.epa.gov/visibility/guidance-regional-hazestate-implementation-plans-secondimplementation-period; Clarifications Regarding 

Regional Haze State Implementation Plans for the 

Second Implementation Period (2021), available at 

https://www.epa.gov/visibility/clarificationsregarding-regional-haze-state-implementationplans-second-implementation. 

EPA’s degree of emission limitation, the 

state must justify how any additional 

consideration results in a standard of 

performance that is no less stringent 

than necessary to address the 

fundamental differences identified 

under paragraph (e). 

In addition to being consistent with 

statutory and regulatory precedent on 

variances, the procedure the EPA is 

promulgating in 40 CFR 60.24a(f)(1) for 

determining standards of performance 

that are no less stringent than necessary 

is also consistent with CAA section 111. 

As explained throughout this section of 

the preamble, CAA section 111(a)(1) 

defines a standard of performance as a 

standard for emissions of air pollutants 

that reflects a certain degree of emission 

limitation and gives the EPA the 

‘‘primary regulatory role’’ 131 of 

determining that degree of emission 

limitation. Congress required that, in 

doing so, the EPA evaluate systems of 

emission reduction that have been 

adequately demonstrated and determine 

which is best based on the amount of 

emission reductions, cost of achieving 

such reduction, nonair quality health 

and environmental impacts, and energy 

requirements. As also explained in this 

section of the preamble, CAA section 

111(d) directs the EPA to prescribe 

regulations that ‘‘permit’’ states ‘‘in 

applying’’ a standard of performance to 

a particular source to ‘‘take into 

consideration’’ RULOF. The 

requirements the EPA is promulgating 

in 40 CFR 60.24a(f)(1) ‘‘permit’’ a state 

to particularize a standard of 

performance for any given source by 

accounting for RULOF where there are 

fundamental differences between the 

information specific to a facility and the 

information the EPA considered in 

determining the degree of emission 

limitation in the applicable EG. In doing 

so, the state must remain as consistent 

as possible with that degree of emission 

limitation in light of what the Supreme 

Court has recognized as the EPA’s 

primary regulatory role in CAA section 

111(d) and the emission reduction 

purpose of CAA section 111. Because 

Congress has identified the factors noted 

above as relevant considerations for the 

EPA in determining a standard of 

performance, the Agency believes it is 

also reasonable to require states to 

consider these systems, factors, and 

evaluation metrics in the manner that 

the EPA did in applying standards of 

performance pursuant to 40 CFR 

60.24a(f). 

Furthermore, the EPA’s authority to 

promulgate 40 CFR 60.24a(f) is 

buttressed by CAA section 111(d)(2). As 

discussed in sections III.E.1. and 2. of 

this preamble, CAA section 111(d)(2) 

provides that the EPA shall have the 

same authority as under CAA section 

110(c) to prescribe a Federal plan where 

a state fails to submit a satisfactory plan. 

The EPA’s long-standing interpretation 

of this subsection is that it provides the 

Agency authority to substantively 

review states’ standards of 

performance.132 The existing regulations 

of subpart Ba and the EPA’s emission 

guidelines provide the substantive 

criteria for the Agency’s evaluation of 

standards of performance generally; 133

the regulations the EPA is promulgating 

at 40 CFR 60.24a(f) constitute the 

substantive criteria for evaluating 

standards of performance states have 

applied pursuant to RULOF. 

Some commenters on proposed 40 

CFR 60.24a(f) dislike the EPA’s 

approach to determining what 

constitutes a ‘‘satisfactory’’ less 

stringent standard of performance but 

offer no alternatives, other than states 

should have complete discretion to 

apply standards pursuant to RULOF. 

This cannot be correct. If this was the 

case, the EPA would have no choice but 

to approve plans in which states have 

applied business-as-usual standards, or 

standards that allows designated 

facilities’ emissions to increase, even if 

more stringent standards of performance 

are reasonable for that facility. Such an 

outcome would be inconsistent with the 

text, context, and purpose of CAA 

section 111. The EPA believes the 

criteria it is providing for the Agency’s 

substantive review of less stringent 

standards of performance are a 

reasonable approach to fulfilling its 

statutory obligation under CAA section 

111(d)(2) to substantively review 

standards of performance in state plans. 

Moreover, it is not uncommon for the 

EPA to promulgate regulatory 

frameworks to guide states in areas in 

which Congress has granted them 

discretion. For example, under the 

visibility protection provisions of CAA 

section 169A, Congress directed the 

EPA to promulgate regulations to assure 

that reasonable progress towards 

meeting the national goal for visibility 

improvement in mandatory class I 

Federal areas, as well as to assure 

compliance with the requirements of 

CAA section 169A. Section 169A further 

provides that states implement the 

visibility protection requirements 

through state implementation plans, in 

which they must include emission 

limitations for sources of visibility 

impairing pollutants. The statute 

provides two types of control analyses 

for states to use in determining the 

applicable emission limitations: 

reasonable progress and best available 

retrofit technology.134 Although 

Congress directed states to determine 

the best available retrofit technology for 

their existing sources, the EPA, in 

promulgating its implementing 

regulations, provided a detailed 

methodology and requirements for 

doing so in 40 CFR 51.308(e) and 40 

CFR part 51, appendix Y. The EPA has 

similarly prescribed requirements for 

states to determine the emission 

reduction measures that are necessary to 

make reasonable progress in 40 CFR 

51.308(f).135 These requirements create 

procedural and substantive frameworks 

within which states exercise their 

discretion in order to ensure the 

outcomes of their control analyses are 

consistent with the statutory 

requirements and purpose. The 

regulatory framework and associated 

guidance also provide states useful 

clarity as to how the EPA will fulfill its 

statutory obligation to review and 

approve or disapprove state plans, and 

how the EPA will promulgate Federal 

plans. 

The EPA is not providing that states 

can forgo analyzing control technologies 

or other systems of emission reduction 

that the EPA has excluded from being 

the BSER on the basis of technological 

or economic feasibility, as suggested by 

commenters. The EPA conducts BSER 

analyses on a source-category basis. It 

may be that a system of emission 


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reduction is generally adequately 

demonstrated but is not the BSER 

because it cannot be applied to 

designated facilities across the category 

at a reasonable cost or because it is 

technically infeasible for a certain 

portion of the category. However, 

designated facilities that are eligible to 

receive a less-stringent standard of 

performance are in demonstrably 

different circumstances than facilities in 

the source category generally. Therefore, 

control technologies or other systems 

that may not be the BSER for the source 

category may be reasonable for a source 

that has invoked RULOF. Similarly, to 

avoid inadvertently precluding 

consideration of a system that could 

allow a state to apply a standard of 

performance that is no less stringent 

than necessary, the EPA is not providing 

that states must consider only control 

technologies or systems that result in 

less emission reductions than the EPA’s 

BSER. While it is true that states should 

only be in the position of applying less 

stringent standards of performance if 

they have demonstrated that a 

designated facility cannot achieve the 

degree of emission limitation, there may 

be situations in which it is not practical 

or feasible to ascertain a priori what 

degree of emission limitation a 

technology or system could achieve 

when applied to a particular source. 

Thus, the EPA does not believe it is 

reasonable to narrow the scope of 

control technologies or other systems of 

emission reduction that states must 

consider under these general 

implementing regulations. The Agency 

may find it appropriate to do so in the 

context of an individual EG. 

Some commenters noted the resources 

and potential burden associated with 

conducting the proposed source-specific 

BSER analyses. While the EPA is not 

finalizing a requirement for states to 

conduct source-specific BSER analyses, 

it acknowledges that stakeholders could 

have similar concerns in the context of 

the provision being promulgated at 40 

CFR 60.24a(f). However, the EPA does 

not believe the RULOF provisions will 

significantly add to states’ planning 

processes. First, as explained in section 

III.E.2. of this preamble, consistent with 

the statutory framework the EPA 

believes that use of RULOF should be an 

exception to the general rule that the 

EPA’s degree of emission limitation is 

reasonable for designated facilities 

within the applicable source category. 

Given the EPA’s ability to subcategorize 

source categories and to tailor its EG to 

the circumstances of each subcategory, 

using RULOF to apply a less stringent 

standard of performance should be 

appropriate in only very limited 

circumstances. 

Second, as explained above, the EPA 

is providing in 40 CFR 60.24a(f)(1) that 

states must evaluate the systems of 

emission reduction in the applicable EG 

using the factors and evaluation metrics 

the EPA considered ‘‘[t]o the extent 

necessary to determine a standard of 

performance’’ that is no less stringent 

than necessary to address the 

fundamental differences identified 

under paragraph (e). As noted above, the 

EPA anticipates that in some if not 

many cases, states will be able to 

demonstrate that the less stringent 

standard of performance they are 

applying is no less stringent than 

necessary without evaluating all of the 

systems of emission reduction in the 

applicable EG. For example, if the EPA’s 

degree of emission limitation is 95% 

reduction in emissions and a state 

applies a less stringent standard of 

performance that results in 90% 

reduction, the state may reasonably 

forgo evaluating additional systems of 

emission reduction if, based on the 

information in the EG, it is clear that 

none is able to achieve comparable 

reductions. Similarly, a state may not 

need to consider every system of 

emission reduction in an applicable EG 

if it starts by evaluating the system or 

systems that achieve the greatest 

emission reductions and applies a 

standard of performance corresponding 

to one of those systems. 

Third, the EPA anticipates states 

applying less stringent standards of 

performance would leverage the 

information and analyses the Agency 

has provided in the applicable EG. In 

promulgating an EG, the EPA is required 

to provide the elements listed in 40 CFR 

60.22a(b), which include ‘‘[a] 

description of systems of emission 

reduction which, in the judgment of the 

Administrator, have been adequately 

demonstrated,’’ and ‘‘[i]nformation on 

the degree of emission limitation which 

is achievable with each system, together 

with information on the costs, nonair 

quality health environmental [sic] 

effects, and energy requirements of 

applying each system to designated 

facilities,’’ as well as ‘‘[s]uch other 

available information as the 

Administrator determines may 

contribute to the formulation of State 

plans.’’ In many cases, the EPA provides 

extensive technical support documents 

including feasibility and cost analyses. 

The Agency also typically discusses the 

types of nonair quality health and 

environmental effects and energy 

requirements that might be expected in 

conjunction with various systems of 

emission reduction applicable to the 

source category. Although designated 

facilities for which RULOF has been 

invoked are in fundamentally different 

circumstances that the average or 

typical facilities that EPA considers in 

the context of its own analysis, the 

information provided in an EG will 

provide a starting point and, in at least 

some cases, much of the analytical basis 

for states’ evaluations. 

Fourth, in the event the state needs to 

analyze different systems of emission 

reduction to determine a less stringent 

standard of performance, the EPA 

believes it would be in this position 

regardless of any requirements the 

Agency does or does not provide. That 

is, because CAA section 111(d)(1) 

requires a standard of performance for 

each existing source, the EPA does not 

believe the framework being provided in 

40 CFR 60.24a(f) will significantly alter 

states’ workload if and when invoking 

RULOF. Rather, it is intended to provide 

clarity for states in developing standards 

of performance consistent with the 

statutory requirements. The EPA 

intends for these requirements to in fact 

reduce planning burdens overall, as 

they provide a framework for states to 

submit approvable standards of 

performance for sources invoking 

RULOF, thereby obviating the need for 

subsequent plan revisions to address 

any disapproved standards. 

As noted above, the EPA requested 

comment on whether to provide 

consideration of the five BSER factors as 

part of a source-specific BSER analysis 

as a presumptively approvable 

framework for applying a less stringent 

standard of performance, as opposed to 

requirements. The framework the EPA is 

finalizing in this action differs from the 

proposed approach under which states 

would conduct source-specific BSER 

analyses; the process the EPA is 

finalizing at 40 CFR 60.24a(f) is 

premised on determining the 

appropriate variance from the EPA’s 

degree of emission limitation. The EPA 

is providing this framework as 

requirements for states applying a less 

stringent standard of performance. As 

explained elsewhere in this section of 

the preamble, the EPA does not believe 

it is possible, as a practical matter, to 

determine a standard of performance 

that is no less stringent than necessary 

without evaluating the systems of 

emission reduction that the EPA 

determined are adequately 

demonstrated and engaging with the 

factors and evaluation metrics that the 

EPA used to evaluate those systems in 

the applicable EG. Therefore, the EPA 

believes that states must use the 

framework laid out in 40 CFR 60.24a(f) 

in order for the resulting variance to be 


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136 ‘‘Form’’ of the less stringent standard of 

performance refers to a numerical emissions 

standard versus a work practice standard, the units 

in which a standard is expressed, or both. 

consistent with CAA section 111(d). As 

laid out in the § 60.24a(f)(1), states may 

also consider additional systems and 

other factors specific to the facility that 

were the basis of the fundamental 

difference identified under 40 CFR 

60.24a(e), so long as they justify that any 

such consideration is consistent with 

applying a standard of performance that 

is no less stringent than necessary. 

In sum, the EPA is not finalizing its 

proposed requirement under 40 CFR 

60.24a(f)(1) that states that have invoked 

RULOF for a particular facility 

determine a source-specific BSER. As a 

result, it is also not finalizing the 

provision proposed at 40 CFR 

60.24a(f)(2) that would have required 

states to calculate the emission 

reductions a source-specific BSER 

would achieve and apply the standard 

of performance that reflects this degree 

of emission reduction. However, 

consistent with its proposal, the EPA 

continues to believe it is necessary for 

the Agency to provide a process for 

states that have invoked RULOF for a 

particular facility to follow in applying 

a less stringent standard of performance. 

The EPA is therefore promulgating 

requirements at 40 CFR 60.24a(f) to 

ensure that states that have invoked 

RULOF for a particular designated 

facility apply a standard of performance 

that is no less stringent than necessary 

to address the fundamental differences 

identified under 40 CFR 60.24a(e). 

These provisions are necessary to 

ensure consistency with the purpose, 

text, and context of CAA section 111(d), 

including an understanding of RULOF 

as a limited variance from the degree of 

emission limitation in the applicable 

EG. The provisions at 40 CFR 

60.24a(f)(1) as finalized will require 

states to determine a less stringent 

standard of performance that is no less 

stringent than necessary. In doing so, 

states must, to the extent necessary, 

evaluate the systems of emission 

reduction in that EPA using the factors 

and evaluation metrics that the EPA 

considered. States may also consider, as 

justified, other factors specific to the 

facility that were the basis for invoking 

RULOF under 40 CFR 60.24a(e), as well 

as additional systems of emission 

reduction. The EPA is finalizing the 

provision proposed at 40 CFR 

60.24a(f)(3), requiring that a less 

stringent standard of performance 

pursuant to RULOF be in the form 136

required by the applicable EG, at 

paragraph (f)(2). 

c. Contingency Requirements 

The EPA recognizes that a source’s 

operations may change over time in 

ways that cannot always be anticipated 

or foreseen by the EPA, state, or 

designated facility. This is particularly 

true where the basis of the application 

of RULOF is a designated facility’s 

operational conditions, such as the 

source’s remaining useful life or 

restricted capacity. If the designated 

facility subsequently changes its 

operating conditions after the state or 

EPA applies a less stringent standard of 

performance, the basis for the variance 

may be abrogated and the standard of 

performance may no longer be no less 

stringent than necessary. For example, a 

state may seek to invoke RULOF for an 

EGU on the basis that it is running at 

lower utilization than the EPA 

considered in determining the degree of 

emission limitation and intends to do so 

for the duration of the compliance 

period required by an EG. Under this 

scenario, the state may be able to 

demonstrate that it is not reasonably 

cost-effective for the designated facility 

to achieve the degree of emission 

limitation and the state could set a less 

stringent standard of performance for 

this EGU. However, because reduced 

utilization is not a physical constraint 

on the designated facility’s operations, it 

is possible that the source’s utilization 

could increase in the future without any 

other legal constraint. 

The EPA proposed to address this 

potential scenario by adding a 

contingency requirement to the RULOF 

provision at 40 CFR 60.24a(h) that 

would require a state to include in its 

state plan an instrument making a 

source’s operating condition, such as 

remaining useful life or restricted 

capacity, enforceable whenever the state 

seeks to rely on that operating condition 

as the basis for a less stringent standard. 

This requirement would not extend to 

instances where a state applies a less 

stringent standard on the basis of an 

unalterable condition that is not within 

the designated source’s control, such as 

technical infeasibility, space limitations, 

water access, or geologic sequestration 

access. Rather, this requirement 

addresses operating conditions such as 

operation times, operational frequency, 

process temperature and/or pressure, 

fuel parameters, and other conditions 

that are subject to the discretion and 

control of the designated facility. 

Many commenters on this subject 

supported the EPA’s proposed approach 

to operating conditions that are within 

a designated facility’s control. They 

noted that, in the absence of an 

enforceable requirement, a designated 

facility could change its operations with 

the result being foregone emission 

reductions and undermining of the level 

of stringency in the EG. One commenter 

stated that the EPA should not permit a 

source that has legally committed to a 

retirement date as a condition of 

invoking RULOF to receive a lessstringent standard to postpone that date 

because, even if it committed to meet 

the emission limitation in the EG from 

that point forward, it could not make up 

for its excess emissions before that time. 

Other commenters opposed the EPA’s 

proposed requirement and asserted that 

the EPA had cited no legal authority or 

record basis for a need to require states 

to make operational conditions that are 

the basis of less stringent standards into 

enforceable requirements in state plans. 

One commenter noted that states should 

have latitude in their regulatory and 

permit processes to determine what 

additional restrictions or contingencies 

are necessary to ensure that the less 

stringent standard remains appropriate 

over time. 

The EPA continues to believe the 

requirement proposed at 40 CFR 

60.24a(h) is a necessary and reasonable 

safeguard to ensure that designated 

facilities’ standards of performance are 

consistent with the level of stringency 

Congress required. Where are particular 

facility’s operating conditions are the 

basis for a variance from the EPA’s 

degree of emission limitation, that 

variance is warranted only so long as 

the operating condition remains a 

fundamental difference between that 

facility’s circumstances and the 

information the EPA considered in the 

applicable EG. Therefore, in order for a 

state plan to include satisfactory 

standards of performance as well as 

measures for the implementation and 

enforcement of those standards 

pursuant to CAA section 111(d)(1), the 

contingency must be an enforceable 

requirement in that plan; upon EPA 

approval of the plan the contingency 

becomes a federally enforceable 

requirement (in addition to being 

enforceable through the state-law 

instrument that was included in the 

plan). Inclusion in a state permit, rule, 

or other instrument alone is not 

sufficient to satisfy CAA section 

111(d)(1). A state-only instrument can 

additionally be changed outside the 

state plan revision process, which could 

result in the lifting of the operational 

condition without a corresponding 

adjustment to the designated facility’s 

less stringent standard of performance. 

The EPA notes that it has a practice 

of requiring operational conditions that 


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137 84 FR 32520, 32558 (July 8, 2019). The EPA 

has proposed to repeal the ACE Rule on other 

grounds. See 88 FR 33240 (May 23, 2023). 

138See, e.g., 76 FR 12651, 12660–63 (March 8, 

2011) (best available retrofit technology 

requirements for Oregon source based on 

enforceable retirement that were to be made 

federally enforceable in state implementation plan); 

Guidance on Regional Haze State Implementation 

Plans for the Second Implementation Period at 34, 

EPA–457/B–19–003, August 2019 (to the extent a 

state relies on an enforceable shutdown date for a 

reasonable progress determination, that measure 

would need to be included in the SIP and/or be 

federally enforceable). 

are the basis of less stringent emission 

limitations to be included in state plans 

or state implementation plans under 

CAA section 111 or 110, respectively, 

including in the Affordable Clean 

Energy Rule 137 and under the CAA’s 

regional haze program.138

States may revise their state plans to 

allow a designated facility that has 

committed to retiring as the basis for 

invoking RULOF to postpone its 

retirement date. There could be many 

reasons a designated facility that 

previously agreed to a federally 

enforceable commitment to cease 

operations by a certain date might need 

to extend that date. The EPA is unable 

to assess, in the context of these general 

implementing regulations, an 

appropriate approach for all possible 

circumstances to ensure that the level of 

stringency of the EG is not undermined. 

The EPA anticipates addressing this 

consideration in individual EGs. 

As previously discussed, the state 

plan submission must also include 

measures for the implementation and 

enforcement of a standard that accounts 

for RULOF. For standards that are based 

on operating conditions that a facility 

has discretion over and can control, the 

operating condition and any other 

measure that provides for the 

implementation and enforcement of the 

less stringent standard must be included 

in the plan submission and as a 

component of the standard of 

performance. For example, if a state 

applies a less stringent standard for a 

designated facility on the basis of a 

lower capacity factor, the plan 

submission must include an enforceable 

requirement for the source to operate at 

or below that capacity factor, and 

include monitoring, reporting, and 

recordkeeping requirements that will 

allow the state, the EPA, and the public 

to ensure that the source is in fact 

operating at that lower capacity. A 

specific EG may detail supplemental or 

different requirements on implementing 

the proposed general requirement that a 

state plan submission include both the 

operating condition that is the basis for 

a less stringent standard, and measures 

to provide for the implementation and 

enforcement of such standard. 

The EPA notes there may be 

circumstances under which a 

designated facility’s operating 

conditions change permanently so that 

there may be a potential violation of the 

contingency requirements approved as 

federally enforceable components of the 

state plan. For example, a designated 

facility that was previously running at 

lower capacity now plans to run at a 

higher capacity full time, which 

conflicts with the federally enforceable 

state plan requirement that the facility 

operate at the lower capacity. To 

address this concern, a state may submit 

a plan revision to reflect the change in 

operating conditions. Such a plan 

revision must include a new standard of 

performance that accounts for the 

change in operating conditions. The 

plan revision would need to include a 

standard of performance that reflects the 

degree of emision limitation required by 

the EG and meet all applicable 

requirements, or if a less stringent 

standard is still warranted for other 

reasons, the plan revision would need to 

meet all of the applicable requirements 

for considering RULOF. The new 

standard of performance would only 

become effective upon the EPA’s 

determination that the plan revision is 

satisfactory. 

The EPA is finalizing as proposed the 

requirement that, where a plan applies 

a less stringent standard of performance 

on the basis of an operating condition 

within the designated facility’s control, 

such as remaining useful life or 

restricted capacity, the plan must also 

include such operation condition or 

conditions as an enforceable 

requirement (this requirement was 

proposed at 40 CFR 60.24a(h) and is 

being finalized at 40 CFR 60.24a(g)). The 

plan must also include requirements to 

provide for the implementation and 

enforcement of the operating condition, 

such as monitoring, reporting, and 

recordkeeping requirements. 

d. Requirements Specific to Remaining 

Useful Life 

CAA section 111(d) explicitly requires 

that the EPA permit states to consider 

remaining useful life in applying a 

standard of performance. While the EPA 

may consider the age of designated 

facilities within a source category as a 

general matter in determining the BSER, 

it is a factor that can have considerable 

variability from facility to facility. The 

annualized costs can change 

considerably based on the applied 

technology at any particular designated 

facility given the amortization period. 

When the EPA determines a BSER, it 

considers cost and, in many instances, 

specifically considers annualized costs 

associated with payment of the 

technology associated with the BSER. 

The shorter that payback period is (i.e., 

shorter remaining useful life), the less 

cost-effective that BSER may become. 

The current RULOF provision in 

subpart Ba generally allows for a state 

to account for remaining useful life to 

set a less stringent standard. However, 

the provision does not provide guidance 

or parameters on when and how a state 

may do so. 

Consistent with the principles 

described previously in section III.E., 

the EPA proposed requirements for 

when a state seeks to apply a less 

stringent standard on grounds that a 

designated facility will retire in the near 

future. Specifically, the EPA proposed 

that the Agency would be required to 

identify in an EG the outermost 

retirement date for designated facilities 

that could qualify for consideration of 

remaining useful life, or a methodology 

and considerations for states to use in 

determining such an outermost date. 

The proposed regulations would have 

also allowed states to apply a routine 

maintenance standard of performance to 

designated facilities with ‘‘imminent’’ 

retirement dates and additionally 

provided that the EPA may define the 

timeframe for imminent retirements in 

an EG. Finally, consistent with the 

proposed provisions regarding 

contingency requirements, the EPA 

proposed that any state plan that applies 

a standard of performance that is based 

on a particular designated facility’s 

remaining useful life must include the 

retirement date as an enforceable 

commitment and provide measures for 

its implementation and enforcement. 

Several commenters supported the 

EPA’s proposal to identify in an EG an 

outermost and imminent retirement date 

to guide states’ consideration of 

remaining useful life in setting less 

stringent standards. Some supportive 

commenters also urged the EPA to 

prescribe further requirements for 

designated facilities that rely on a 

shorter remaining useful life, including 

prohibiting them from extending their 

retirement dates and defining an 

imminent retirement as one that occurs 

within two years of state plan 

submission. Other commenters opposed 

the EPA’s proposed requirements 

around the consideration of remaining 

useful life. Some argued that the 

requirements would foreclose states 

from considering remaining useful life 

when a designated facility’s retirement 

date falls outside the prescribed range 

and that, although states must 

reasonably exercise their discretion, the 


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139See, e.g., 84 FR 32558 (ACE Rule explained 

that state plans must adequately document and 

demonstrate the process and underlying data used 

to establish standards of performance so that EPA 

can adequately and appropriately review the plan 

to determine whether it is satisfactory). 

140See 40 CFR 60.24(c), 60.24a(c). 

CAA puts no limits on their 

consideration of this factor. Adverse 

commenters also noted that the 

remaining useful life consideration is 

very source-specific and that there may 

be relevant factors that the EPA would 

not necessarily take into account when 

determining the outermost and 

imminent dates in an EG. 

After consideration of the comments 

received, the EPA has decided not to 

finalize the provisions proposed at 40 

CFR 60.24a(i) regarding remaining 

useful life. As a general matter, the 

proposed requirement for the EPA to 

identify an outermost and imminent 

retirement date for the consideration of 

remaining useful life was intended to 

assist states in developing their state 

plans and to provide transparency and 

consistency in states’ application of, and 

the EPA’s review of, standards of 

performance based on this factor. As 

explained in the preamble to the 

proposed rule, a designated facility’s 

remaining useful life generally impacts 

a cost analysis by changing the 

amortization period, or the period of 

time over which a facility pays the 

capital costs for a system of emission 

reduction. The shorter the period, the 

higher the annualized costs. The EPA 

generally assumes a certain amortization 

period in its BSER determination based 

on, e.g., the lifespan of the system under 

consideration and the characteristics of 

facilities within the source category. A 

designated facility that has a shorter 

remaining useful life than the 

amortization period the EPA assumed in 

its BSER determination will likely find 

that achieving the degree of emission 

based on application of the BSER has 

higher annualized costs; the larger the 

difference between a particular facility’s 

remaining useful life and the EPA’s 

assumed amortization period, the larger 

the difference in annualized costs. 

However, as a factual matter, there is a 

point at which a designated facility’s 

remaining useful life is long enough so 

that the difference in annualized costs 

for that facility and the costs the EPA 

considered reasonable in the applicable 

EG are not fundamentally different. At 

this point, it would be unreasonable for 

a state to use remaining useful life as the 

basis for a less-stringent standard for 

that facility because it could achieve the 

EPA’s degree of emission limitation at a 

reasonable cost. 

Similarly, an imminent retirement 

date could serve to streamline states’ 

planning for sources with remaining 

useful lives that are so short that, as a 

factual matter, no available system of 

emission reduction could have 

reasonable costs. What constitutes a 

reasonable cost in the context of a 

specific EG could depend on, inter alia, 

the source category, the emission 

reductions available, and the designated 

pollutant. 

However, the EPA agrees with 

commenters that states’ consideration of 

remaining useful life and what 

constitutes reasonable consideration of 

this factor will necessarily depend on 

the source category, the variability of 

the individual designated facilities 

within the source category, and the 

structure of the applicable EG. In some 

instances, the nature of the designated 

facilities and structure of the EG may 

render a designated facility’s remaining 

useful life of little relevance. For 

example, where a BSER is based on 

operational changes or activities that 

entail little to no capital cost, the 

remaining useful life of a designated 

facility should not change the 

reasonableness of the system and there 

would be no need for the EPA to 

prescribe imminent and outermost 

retirement dates in an EG. Alternatively, 

designated facilities within the source 

category may, by virtue of how an 

industry developed, fall into discrete 

age classes based on their remaining 

useful lives such that the EPA considers 

this characteristic in creating 

subcategories and determining 

appropriate BSERs for each subcategory. 

In this case, too, there might be little 

utility in the EPA defining imminent 

and outermost dates for consideration of 

remaining useful life in an EG. 

The EPA is therefore choosing not to 

finalize the provisions proposed at 40 

CFR 60.24a(i), although it may be 

appropriate to include outermost and 

imminent retirement dates for the 

consideration of remaining useful life in 

individual EGs. The proposed 

provisions included a requirement that 

any plan that applies a less-stringent 

standard based on remaining useful life 

must include the retirement date for the 

designated facility as an enforceable 

commitment, including any measures 

that provide for the implementation and 

enforcement of such a commitment. The 

EPA notes that although it is not 

finalizing the proposed 40 CFR 

60.24a(i)(3), as discussed in section 

III.E.3.c. of this preamble plans that 

include less-stringent standards based 

on remaining useful life will still be 

required to include the relevant 

designated facilities’ retirement dates as 

enforceable commitments and include 

any measures necessary to provide for 

the implementation and enforcement of 

those commitments pursuant to the 

requirement being finalized at 40 CFR 

60.24a(g). 

The EPA also reiterates that the 

obligation to include a standard of 

performance in a state plan applies to 

any designated facility that meets the 

applicability requirements of an EG as 

of that EG’s compliance date. That is, a 

state plan must include a standard of 

performance for a designated facility 

that is retiring after the compliance date, 

even if the facility has an enforceable 

commitment to retire imminently 

following that date. In the case of an 

imminently retiring designated facility, 

it may be reasonable for a state to apply 

a standard reflecting that facility’s 

business as usual; the EPA will address 

this and other potential considerations, 

including how such a standard would 

be calculated, in individual EGs. 

e. Reasoned Decision Making and the 

EPA’s Review of State Plans Invoking 

RULOF 

As discussed previously in section 

III.E. of this preamble, under CAA 

section 111(d)(2), the EPA has the 

obligation to determine whether a state 

plan submission is ‘‘satisfactory.’’ This 

obligation extends to all aspects of a 

state plan, including the application of 

a less stringent standard of performance 

that accounts for RULOF. States carry 

the primary responsibility to develop 

plans that meet the requirements of 

CAA section 111(d) and therefore have 

the obligation to justify any 

consideration of RULOF in applying 

standards less stringent than the degree 

of emission limitation provided by the 

EG. That states must provide a reasoned 

basis including, where applicable, 

technical analyses and other 

documentation to support the decisions 

they make in their plans is fundamental 

to the structure of CAA section 

111(d).139 As explained in section 

III.E.3.a. of this preamble, consistent 

with the statutory framework of CAA 

section 111(d), state plans must ensure 

that designated facilities achieve the 

degree of emission limitation achievable 

through application of the BSER as 

determined by the EPA unless doing so 

would be unreasonable for a particular 

facility. The fundamental tenet has been 

reflected in the EPA’s regulations since 

1975.140 Thus, a ‘‘satisfactory’’ plan is 

one that, inter alia, applies lessstringent standards only where the state 

has demonstrated that achieving the 

EPA’s degree of emission limitation 

would be unreasonable pursuant to 40 

CFR 60.24a(e). A demonstration that a 

particular designated facility cannot 


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141Where a state has relied on information or 

analyses the EPA provided in an applicable EG as 

part of its source specific BSER determination, a 

state would explain why such reliance is reasonable 

and cite or otherwise incorporate that information 

or analyses in its state plan submission. 142See 87 FR 79176, 79202–03 (Dec. 23, 2022). 

reasonably achieve the degree of 

emission limitation determined by the 

EPA will, in most cases, necessarily be 

supported by technical analysis that 

assesses a particular designated facility 

and compares its circumstances to those 

the EPA considered in its EG. 

While it is within states’ discretion to 

apply a less stringent standard of 

performance where the state has 

identified fundamental differences for a 

particular facility (or class of facilities), 

the state must support its decision 

making and demonstrate that it results 

in a standard of performance that is no 

less stringent than necessary to address 

the fundamental differences and that 

meet the applicable requirements. When 

a state invokes RULOF and applies a 

less-stringent standard, it must 

demonstrate that the standard is no less 

stringent than necessary to address the 

fundamental difference identified by the 

state. Absent such a demonstration, the 

EPA cannot ascertain that a lessstringent standard meets the 

requirements of CAA section 111; that 

is, it cannot determine that a lessstringent standard is ‘‘satisfactory.’’ 

The requirements proposed at 40 CFR 

60.24a(j) were intended to explicitly 

clarify states’ responsibilities when 

invoking RULOF and to assist them in 

developing standards in a manner that 

enables the Agency to determine 

whether such standards are 

‘‘satisfactory.’’ The proposed 

requirements provided that states would 

carry the burden of making any 

demonstrations in support of lessstringent standards pursuant to the 

RULOF provisions. States would carry 

the primary responsibility to develop 

plans that meet the requirements of 

CAA section 111(d) and therefore have 

the obligation to justify any accounting 

for RULOF in support of standards less 

stringent than those provided by the EG. 

While the EPA has discretion to 

supplement a state’s demonstration, the 

Agency may also find that a state plan’s 

failure to include a sufficient RULOF 

demonstration is a basis for concluding 

the plan is not ‘‘satisfactory’’ and 

therefore disapprove the plan. The EPA 

further proposed that for the required 

demonstrations, states must use 

information that is applicable to and 

appropriate for the specific designated 

facility, and must show how 

information is applicable and 

appropriate. As RULOF is a sourcespecific determination, it is appropriate 

to require that the information used to 

justify a less stringent standard for a 

particular designated facility be 

applicable to and appropriate for that 

source. Finally, the EPA proposed to 

require that the information used for 

states’ demonstrations under the new 

RULOF provisions must come from 

reliable and adequately documented 

sources, such as EPA sources and 

publications, permits, environmental 

consultants, control technology vendors, 

and inspection reports. 

Comments received on the proposed 

requirements regarding states’ burden of 

demonstration and the use of sitespecific information were generally 

supportive while also requesting further 

clarification of and flexibility in the 

types of information that the EPA would 

consider acceptable. One commenter 

suggested that the EPA allow states to 

use historical data even if not published 

or documented by third parties, as this 

constitutes site-specific information, 

while another suggested allowing 

verified industry information, even if it 

is not site-specific. 

Despite the generally supportive 

commenters received, the EPA is not 

finalizing the requirements proposed at 

40 CFR 60.24a(j). While the EPA 

continues to find that states carry the 

burden of making any demonstrations in 

support of less-stringent standards 

pursuant to RULOF in developing their 

plans, we have determined that it is not 

necessary to promulgate this 

expectation as a standalone regulatory 

requirement. States always bear the 

responsibility of reasonably 

documenting and justifying the 

standards of performance in their 

plans.141 If the EPA cannot ascertain, 

based on the information and analysis 

included in a state plan submission, 

whether a standard of performance 

meets the statutory requirements, it 

cannot find that standard satisfactory. 

Additionally, it is de facto necessary to 

use information that is applicable to and 

appropriate for the designated facility 

when analyzing systems of emission 

reduction for that particular facility. For 

example, for a designated facility 

invoking RULOF based on its unique 

design features, the state plan must 

provide information corroborating the 

uniqueness of those features and 

analysis demonstrating how they result 

in the facility being unable to 

reasonably achieve the degree of 

emission limitation determined by the 

EPA. It would not be reasonable in this 

instance for a state to use generic 

industry data, whether verified or not, 

as the basis of demonstrations pursuant 

to 40 CFR 60.24a(e) and (f). 

While the proposed requirements 

would have simply codified generally 

applicable tenets of reasoned decision 

making, the EPA recognizes that the 

specific types and provenances of 

information needed to justify a lessstringent standard can vary significantly 

between not only source categories, but 

between individual designated facilities 

within a source category. As a result, the 

proposed provisions had the potential to 

be both over- and underinclusive. While 

we are not finalizing these provisions as 

generally applicable requirements for 

state plans, they and the accompanying 

discussion in the notice of proposed 

rulemaking 142 remain important 

guidance for plan development. The 

EPA may also choose to promulgate 

requirements for RULOF 

demonstrations in individual EGs. 

f. Consideration of Impacted 

Communities 

While the consideration of RULOF 

can be warranted to apply a less 

stringent standard of performance to a 

particular facility, such standards have 

the potential to result in disparate 

health and environmental impacts to 

communities most affected by and 

vulnerable to those impacts from the 

designated facilities being addressed by 

the state plan. These communities could 

be put in the position of bearing the 

brunt of the greater health or 

environmental impacts resulting from 

that source implementing less stringent 

emission controls than would otherwise 

have been required pursuant to the EG. 

The EPA considers that a lack of 

attention to such potential outcomes 

would be antithetical to the public 

health and welfare goals of CAA section 

111(d) and the CAA generally. Because 

of CAA section 111(d)(2)’s requirement 

that the EPA determine whether a state 

plan is ‘‘satisfactory’’ applies to such 

plan’s consideration of RULOF in 

applying a standard of performance to a 

particular facility, the EPA must 

determine whether a plan’s 

consideration of RULOF is consistent 

with CAA section 111(d)’s overall 

health and welfare objectives. 

In order to address the potential 

exacerbation of health and 

environmental impacts to these 

communities as a result of applying a 

less stringent standard, the EPA 

proposed to require states to consider 

such impacts when applying the RULOF 

provision to establish those standards. 

Under the proposed provisions at 40 

CFR 60.24a(k), to the extent a 

designated facility would qualify for a 

less stringent standard through 


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143 In the notice of proposed rulemaking, the EPA 

‘‘recognize[d] that the consideration of communities 

in the standard setting process, such as what 

constitutes a benefit to a vulnerable community and 

what is a reasonable level of control, is highly 

dependent on the designated pollutant and source 

category subject to an EG.’’ 87 FR 79203. 

144The EPA is also finalizing the proposed 

definition of ‘‘pertinent stakeholders’’ to include 

those who are most affected by and vulnerable to 

the health or environmental impacts of pollution 

from the designated facilities addressed by the plan 

or plan revision. 

consideration of RULOF, the state, in 

calculating such standard, would have 

been required to demonstrate 

consideration of the potential health 

and environmental impacts and 

potential benefits of control to 

communities most affected by and 

vulnerable to the impacts from the 

designated facility considered in a state 

plan for RULOF provisions. These 

communities will be identified by the 

state as pertinent stakeholders under the 

finalized meaningful engagement 

completeness requirements described in 

section III.C. of this preamble. 

The notice of proposed rulemaking 

further explained that state plan 

submissions seeking to invoke RULOF 

for a source would be required to 

identify where and how a less stringent 

standard impacts these communities. In 

evaluating a RULOF option for a facility, 

states should describe the health and 

environmental impacts anticipated from 

the application of RULOF for such 

communities, along with any feedback 

the state received during meaningful 

engagement regarding its draft state plan 

submission, including on any standards 

of performance that consider RULOF. 

Additionally, to the extent there is a 

range of options for reasonably 

controlling a source based on RULOF, 

the EPA proposed that in determining 

the appropriate standard of 

performance, states should consider the 

health and environmental impacts to the 

communities most affected by and 

vulnerable to the impacts from the 

designated facility considered in a state 

plan for RULOF provisions and provide 

in the state plan submission a summary 

of the results that depicts potential 

impacts for those communities for that 

range of reasonable control options. 

The EPA received a wide range of 

comments on the proposed 

requirements for state plans to consider 

the potential pollution impacts and 

benefits of control to communities most 

affected by and vulnerable to emissions 

from a designated facility that is 

invoking RULOF. Several commenters 

supported the proposal and agreed that, 

given that the purpose of regulating 

stationary source pollution under CAA 

section 111 is to address emissions that 

endanger public health and welfare, 

requiring states that are applying lessstringent standards to take into account 

how air pollution above the level 

reflected by application of the BSER 

may impact the health and welfare of 

local communities furthers the statutory 

design. Other commenters agreed that 

the EPA has authority to require states 

to consider the impacts of less-stringent 

standards of performance on vulnerable 

communities but expressed concern that 

the lack of specificity of and guidance 

for implementing the proposed 

requirements would cause uncertainty 

among state regulators and impacted 

communities and lead to unequal 

application across states. Similarly, one 

commenter noted the differences 

between community impacts when 

considering localized pollutants versus 

regional or global pollutants and that 

impacts of the latter are more diffuse 

and difficult to assess. Some 

commenters, however, disagreed that 

the EPA has authority to require states 

to consider potential health and 

environmental impacts of less-stringent 

standards on vulnerable communities. 

These commenters generally asserted 

that the state-focused language of the 

RULOF provision in CAA section 

111(d)(1) does not mandate an analysis 

of vulnerable communities and does not 

give the EPA power to force states to 

consider ‘‘other factors’’ that it deems 

relevant. 

The EPA is not finalizing the 

proposed provisions at 40 CFR 60.24a(k) 

as requirements under the general 

implementing regulations. We agree 

with commenters that additional 

specificity and guidance with regard to 

how states should consider the potential 

pollution impacts and benefits of 

control to communities most affected by 

and vulnerable to emissions from a 

designated facility invoking RULOF 

would be key to ensuring meaningful 

implementation of this provision. 

However, given the diversity of source 

categories, designated facilities, and 

designated pollutants that are regulated 

and could be regulated in CAA section 

111(d), as well as the wide range of 

potential impacts on vulnerable 

communities that may result from lessstringent standards of performance 

under any given EG,143 the EPA does 

not believe it is either feasible or 

appropriate to prescribe a universally 

applicable approach or standard for 

approvability for this consideration. 

Instead, to protect all communities, 

including the most vulnerable ones, the 

EPA is finalizing a provision that will 

ensure that any less stringent standards 

of performance applied by states are no 

less stringent than necessary. Moreover, 

because consideration of health and 

environmental impacts is inherent in 

consideration of both the nonair quality 

health and environmental impacts and 

amount of emission reduction factors 

the EPA considers under CAA section 

111(a)(1), when a state considers the 

systems of emission reduction identified 

in the applicable emission guideline 

using the factors and evaluation metrics 

the EPA considered in assessing those 

systems pursuant to RULOF, the state 

will necessarily consider the potential 

impacts and benefits of control to 

communities affected by a designated 

facility that is receiving a less-stringent 

standard of performance. 

Thus, while the EPA is not 

promulgating a regulatory requirement 

in subpart Ba for states to consider the 

impacts of applying a less-stringent 

standard of performance on the 

communities most affected by and 

vulnerable to emissions from a 

designated facility invoking RULOF, the 

EPA anticipates that states will consider 

these impacts. To this end, states may 

look to the EPA’s emission guideline 

and its consideration of nonair quality 

health and environmental impacts and 

the amount of emission reductions 

available in determining the degree of 

emission limitation for guidance on 

considering the health and 

environmental impacts on communities 

affected by a designated facility for 

which RULOF has been invoked. 

Additionally, the procedural 

requirements under subpart Ba for 

meaningful engagement with pertinent 

stakeholders on state plan development 

that the EPA is finalizing will play an 

important role in RULOF. Meaningful 

engagement, which the EPA is defining 

as ‘‘timely engagement with pertinent 

stakeholder representation in the plan 

development or plan revision 

process,’’ 144 and providing that ‘‘[s]uch 

engagement should not be 

disproportionate in favor of certain 

stakeholders and should be informed by 

available best practices,’’ should 

address, inter alia, the application of 

any less-stringent standards of 

performance pursuant to RULOF. Thus, 

the EPA intends for communities most 

affected by and vulnerable to the health 

and environmental impacts of pollution 

from a designated facility invoking 

RULOF to have an opportunity to 

participate in the process of determining 

how that facility is addressed in the 

relevant state plan. The EPA may also 

consider whether to promulgate 

requirements pertaining to 

consideration of impacts on vulnerable 

communities as part of an individual EG 

in the future, at which point it would 


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145 87 FR 79204–06. 

146 427 U.S. 246, 263–64 (1976). 

147The existing provision at 40 CFR 60.24a(f) 

provides that ‘‘[n]othing in this subpart shall be 

construed to preclude any State or political 

subdivision thereof from adopting or enforcing,’’ (1) 

standards of performance more stringent than an 

EG, or (2) compliance schedules requiring final 

compliance at earlier times than specified in an EG. 

In the proposed rulemaking, the EPA added several 

proposed provisions to 40 CFR 60.24a, which 

resulted in § 60.24a(f), in addition to being 

amended, being renumbered as § 60.24a(n). 

However, the EPA is not finalizing all the new 

provisions it proposed; as a result, erstwhile 

§ 60.24a(f) is now being finalized, with 

amendments, at § 60.24a(i). 

148 84 FR 32559–61. 

149 In the 1975 CAA section 111(d) implementing 

regulations the Agency explained that EPA’s 

emission guidelines will reflect its judgment of the 

degree of control that can be attained by various 

classes of existing source without unreasonable 

costs. Particular sources within a class may be able 

to achieve greater control without unreasonable 

costs. Moreover, States that believe additional 

Continued 

provide guidance on how to do so 

specific to the designated facilities and 

designated pollutant at issue. 

g. Authority To Apply More Stringent 

Standards as Part of the State Plan 

The EPA, in the notice of proposed 

rulemaking, addressed two different 

sources of authority that would allow 

the Agency to approve state plans that 

include standards of performance that 

are more stringent than the degree of 

emission limitation determined by the 

EPA in the applicable EG. First, the EPA 

explained that allowing states to apply 

a more stringent standard of 

performance as part of their CAA 

section 111(d) plans is consistent with 

CAA section 116, which generally 

authorizes states to include more 

stringent standards of performance or 

requirements regarding control or 

abatement of air pollution in their plans. 

Second, the EPA proposed to 

interpretation the RULOF provision in 

CAA section 111(d)(1), and specifically 

the ‘‘other factors’’ consideration, as 

allowing states to adopt more stringent 

standards of performance.145 As 

explained below, the EPA is not 

finalizing its proposed interpretation 

that states can use the RULOF provision 

in CAA section 111(d)(1) to adopt, and 

have the EPA approve, more stringent 

standards of performance in their state 

plans because, inter alia, states already 

have the authority and ability to do so 

under CAA section 116. 

As explained in the notice of 

proposed rulemaking, the antipreemption requirements of CAA 

section 116 provide that nothing in the 

statute shall preclude or deny the right 

of states to adopt or enforce ‘‘any 

standard or limitation respecting 

emissions of air pollutants.’’ While CAA 

section 116 clearly extends to a state 

adopting or enforcing a standard of 

performance more stringent than 

required under CAA section 111(d), the 

subpart Ba implementing regulations 

did not explicitly speak to whether the 

EPA can approve a state plan that 

includes such standard of performance. 

However, the EPA proposed to find that 

CAA section 116, as interpreted through 

the Supreme Court in Union Electric Co. 

v. EPA,146 requires the EPA to approve 

a state plan that includes more stringent 

standards of performance under CAA 

section 111(d). The EPA therefore 

proposed to modify the existing 40 CFR 

60.24a(f),147 clarifying that to the extent 

a state chooses to submit a plan that 

includes standards of performance that 

are more stringent or compliance 

schedules that are more rapid than the 

requirements of an EG, states have the 

authority to do so under this provision 

and CAA section 116. Further, the EPA 

proposed to clarify that it has the 

obligation, and therefore the authority, 

to review and approve such plans and 

render the more stringent requirements 

federally enforceable if all applicable 

requirements are met. 

The EPA is finalizing the proposed 

changes to the provision currently at 40 

CFR 60.24a(f) which, as renumbered 

pursuant to this final rule, is now 40 

CFR 60.24a(i). The Agency 

acknowledges that it previously took the 

position in the ACE Rule that Union 

Electric does not control the question of 

whether CAA section 111(d) state plans 

may be more stringent than Federal 

requirements. The EPA took this 

position in the ACE Rule on the basis 

that Union Electric on its face applies 

only to CAA section 110, and that it is 

‘‘potentially salient’’ that CAA section 

111(d) is predicated on specific 

technologies whereas CAA section 110 

gives states broad latitude in the 

measures used for attaining the 

NAAQS.148 The EPA no longer takes 

this position. Upon further evaluation, 

the EPA finds that, because of the 

structural similarities between CAA 

sections 110 and 111(d), CAA section 

116 as interpreted by Union Electric 

requires the EPA to approve CAA 

section 111(d) state plans that are more 

stringent than required by the EG. 

The Court in Union Electric rejected 

a construction of CAA sections 110 and 

116 that measures more stringent than 

those required to attain the NAAQS 

cannot be approved into a federally 

enforceable SIP but can be adopted and 

enforced only as a matter of state law. 

The Court found that such an 

interpretation of CAA section 116 

‘‘would not only require the 

Administrator to expend considerable 

time and energy determining whether a 

state plan was precisely tailored to meet 

the Federal standards but would 

simultaneously require States desiring 

stricter standards to enact and enforce 

two sets of emission standards, one 

federally approved plan and one stricter 

state plan.’’ 427 U.S. at 263–64. The 

Court concluded there was no basis ‘‘for 

visiting such wasteful burdens upon the 

States and the Administrator.’’ Id. CAA 

sections 111(d) and 110 are structurally 

similar in that both require the EPA to 

establish targets to meet the objectives 

of the respective sections (i.e., the 

degree of emission limitation set by an 

EG under CAA section 111(d), and 

attainment and maintenance of the 

NAAQS under CAA section 110), and 

states must adopt and submit to the EPA 

plans which include requirements to 

meet these targets. Specifically, the EPA 

establishes a presumptive standard of 

performance corresponding to the 

degree of emission limitation it has 

determined in an EG, and state plans 

under CAA section 111(d) must 

establish standards of performance that 

generally reflect this degree of emission 

limitation. Because CAA section 116 

applies to ‘‘any standard or limitation,’’ 

this provision clearly applies to 

standards of performance adopted under 

CAA section 111(d). Therefore, the 

Court’s rationale in Union Electric as it 

pertains to the application of CAA 

section 116 in the context of the 

cooperative federalism structure of CAA 

section 110 also applies to CAA section 

111(d). That is, the assessment of CAA 

section 116 in the context of 

requirements that states develop and 

submit to the EPA for evaluation against 

nationally applicable standards or 

criteria applies equally to CAA sections 

110 and 111(d). On that basis, the EPA 

is finding that the Court’s holding 

applies and controls the outcome here, 

as well. Requiring states to enact and 

enforce two sets of standards of 

performance, one that is exactly equal to 

the EPA’s presumptive standard of 

performance that is federally approved 

as part of the CAA section 111(d) plan 

and one that is stricter and is only 

adopted and enforced as a matter state 

requirements, runs directly afoul of 

Union Electric’s holding that there is no 

basis for interpreting CAA section 116 

in such manner. 

Moreover, there is nothing in CAA 

section 111(d) that precludes states from 

adopting, and EPA from approving, 

more stringent standards of 

performance.149 In fact, permitting 


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80530 Federal Register / Vol. 88, No. 221 / Friday, November 17, 2023 / Rules and Regulations 

control is necessary or desirable will be free under 

section 116 of the Act to require more expensive 

controls, which might have the effect of closing 

otherwise marginal facilities, or to ban particular 

categories of sources outright. 40 FR 53343. 

Congress did nothing to disturb the understanding 

that states can use CAA section 116 to adopt more 

stringent standards of performance when it enacted 

the 1977 CAA Amendments shortly thereafter. 

150See EPA’s Responses to Public Comments on 

the EPA’s Proposed Revisions to Emission 

Guideline Implementing Regulations at 56 (Docket 

ID No. EPA–HQ–OAR–2017–0355–26740) (July 8, 

2019). 

states to adopt more stringent standards 

of performance and include such 

standards in their state plans is entirely 

consistent with the purpose and 

structure of CAA section 111(d). States 

bear the obligation pursuant to CAA 

section 111(d)(1) to establish standards 

of performance. Nothing in CAA section 

111(d) suggests that Congress intended 

to preclude states from determining that 

it is appropriate to regulate certain 

sources within their jurisdiction more 

strictly than otherwise required by 

Federal requirements. For the EPA to do 

so would be arbitrary and capricious in 

light of the overarching purpose of CAA 

section 111(d), which is to require 

emission reductions from existing 

sources for certain pollutants that 

endanger public health or welfare. It is 

inconsistent with the purpose of CAA 

section 111(d) and the role it confers 

upon states for the EPA to constrain 

them from further reducing emissions 

that harm their citizens, and the EPA 

does not see a reasonable basis for doing 

so. 

The EPA also included a second 

rationale for permitting more stringent 

standards of performance in the notice 

of proposed rulemaking. The Agency 

explained that CAA section 111(d)(1) 

provides that states are permitted to 

consider remaining useful life and other 

factors ‘‘in applying a standard of 

performance to any particular source 

under a plan,’’ but does not specify that 

the source-specific standard must be a 

less stringent standard of performance. 

Aside from the explicit reference to 

remaining useful life, the statute is 

silent as to what the ‘‘other factors’’ are 

that states may consider in applying a 

standard of performance and whether 

such factors can be used only to weaken 

the stringency of a standard of 

performance for a particular designated 

facility. Therefore, in addition to 

proposing that states may include, and 

the EPA must approve, more stringent 

standards of performance in state plans 

pursuant to CAA sections 111(d) and 

116, the EPA also proposed to interpret 

CAA section 111(d)(1) as allowing states 

to consider ‘‘other factors’’ in exercising 

their discretion to apply a more 

stringent standard to a particular source. 

The Agency acknowledged that it had 

previously, in promulgating subpart Ba 

in 2019, taken the position that the 

statutory RULOF provision authorizes 

only standards of performance that are 

less stringent than the presumptive level 

of stringency required by a particular 

EG,150 and explained why it was 

proposing to change course. To codify 

its revised interpretation of the RULOF 

provision, the EPA proposed explicit 

regulatory text that would have allowed 

states to use RULOF, and specifically, 

‘‘other factors,’’ to apply a more 

stringent standard of performance. The 

new provision at 40 CFR 60.24a(m) 

would have also required that state 

plans include an adequate 

demonstration that the standard of 

performance is more stringent than 

required by an application EG and meet 

all other applicable requirements. 

The EPA received comments both in 

support of and opposed to its proposed 

interpretation that states may apply 

more stringent standards of performance 

and that EPA has an obligation to 

approve such standards in state plans. 

Several commenters stated the Agency 

has appropriately interpreted CAA 

section 116 and 111(d), as well as Union 

Electric Co. v. EPA, as allowing states to 

submit, and the EPA to approve, more 

stringent standards. One commenter 

also agreed that the statutory phrase 

‘‘remaining useful life and other factors’’ 

does not foreclose a state plan from 

applying a more stringent standard of 

performance to a particular source; 

while ‘‘remaining useful life’’ implies a 

less stringent standard, ‘‘other factors’’ 

does not. Another commenter asserted 

that the EPA need not rely on ‘‘other 

factors’’ to permit states to apply more 

stringent standards because states 

already have the ability to do so in light 

of the Supreme Court’s ruling in Union 

Electric. Commenters that disagreed 

with the EPA’s proposed interpretation 

generally recognized that states can 

adopt more stringent rules than those 

required by the EPA but asserted that 

the CAA does not authorize the EPA to 

approve them into state plans and thus 

make them federally enforceable. One 

commenter argued that the EPA’s BSER 

determination defines the extent of both 

EPA and state authority under CAA 

section 111 and that the RULOF 

provision does not authorize states to 

select a different, more stringent BSER 

under the guise of RULOF. Another 

commenter stated that the EPA’s 

position that RULOF is a variance 

provision for sources that cannot meet 

the BSER due to limited remaining 

useful life or other factors is in tension 

with its interpretation that the same 

provision provides a broad grant of 

authority for states to impose more 

stringent standards on sources. The 

same commenter pointed out the 

difference in proposed requirements for 

states invoking RULOF to apply a less 

stringent standard and those for 

applying a more stringent standard. 

The EPA agrees with commenters that 

it need not rely on ‘‘other factors’’ for 

authority to permit states to submit, and 

the EPA to approve, more stringent 

standards of performance in state plans. 

As explained above, CAA sections 116 

and 111(d), and the Court’s 

interpretation in Union Electric of 

section 116 as it relates to CAA section 

110’s analogous statutory framework, 

provide a sufficient basis this position. 

Moreover, upon further consideration of 

the history of the RULOF provision and 

the EPA’s interpretation of that 

provision as a variance for states to use 

when a source cannot reasonably 

achieve the degree of emission 

limitation determined by the EPA, the 

Agency is not finalizing its proposed 

interpretation that the RULOF provision 

allows states to adopt more stringent 

standards of performance in their plans. 

The EPA is therefore not finalizing the 

provision it proposed at 40 CFR 

60.24a(m) that would have explicitly 

allowed a state to ‘‘account for other 

factors in applying a standard of 

performance that is more stringent than 

required by an applicable emission 

guideline, or the proposed provision 

that ‘‘[t]he plan must include an 

adequate demonstration that the 

standard of performance is more 

stringent than required by an applicable 

emission guideline, and must meet all 

other applicable requirements, such as 

those that provide for the 

implementation and enforceable of the 

more stringent standard of 

performance.’’ As a general matter, 

states already bear the burden of 

demonstrating that their standards of 

performance are no less stringent than 

the corresponding EG. See 40 CFR 

60.24a(c). 

The EPA disagrees with comments 

suggesting that the EPA’s BSER 

determination is the ceiling—that the 

EPA is constrained from approving 

more stringent standards of performance 

into state plans. As explained above, 

there is no support for this position in 

the statutory language or structure of 

CAA section 111(d). It is also 

inconsistent with CAA section 116 and 

would run counter to the purpose of 

section 111—reducing emissions of 

dangerous air pollutants from 

designated facilities. 


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151 40 CFR 62.1100(b)(7); 85 FR 1121 (Jan. 9, 

2020); see also ‘‘Appendix E: Comparison of the 

Major Provisions of the Emission Guidelines and 

California’s Landfill Methane Regulation,’’ EPA– 

R09–OAR–2019–0393–0008 (technical support 

document for EPA action on California’s CAA 

section 111(d) state plan to implement the EG for 

landfill gas from municipal solid waste landfills). 

152 87 FR 79206. 

The EPA anticipates that, in many 

cases, more stringent standards of 

performance would entail marginal 

differences in stringency between the 

degree of emission limitation in the 

applicable EG and the state plan 

requirement. For example, the EPA may 

determine that, for the source category 

in general, a control technology can 

reasonably achieve an 80% reduction in 

emissions, while a state finds that at a 

particular designated facility, that same 

control technology can reasonably 

achieve a 90% reduction. Or a state may 

decide that a particular designated 

facility can install a control technology 

that has already been demonstrated to 

reasonably achieve greater emission 

reductions than the BSER the EPA 

determined for the source category 

generally. The EPA also notes that 

approving more stringent standards of 

performance in state plans is not a new 

practice under subpart Ba; for example, 

in 2020 the EPA approved more 

stringent standards of performance that 

California submitted as part of its CAA 

section 111(d) state plan to implement 

the emission guidelines for landfill gas 

emissions from municipal solid waste 

landfills. These more stringent 

standards of performance were 

incorporated into the Code of Federal 

Regulations and thus became federally 

enforceable.151

In summary, the EPA is finalizing, at 

40 CFR 60.24a(i), the proposed revisions 

to the existing provision (currently at 40 

CFR 60.24a(f)) stating that nothing in 

subpart Ba shall be construed to 

preclude any state from adopting or 

enforcing, as part of a state plan, (1) 

standards of performance more stringent 

that the applicable EG, or (2) 

compliance schedules requiring final 

compliance at earlier times than 

specified in the applicable EG. The EPA 

is not finalizing the regulatory text 

provision proposed at 40 CFR 60.24a(m) 

stating that a state may account for other 

factors in applying a more stringent 

standard of performance. 

F. Provision for Electronic Submission 

of State Plans 

The EPA proposed to revise subpart 

Ba to require electronic submission of 

state plans instead of paper copies.152

As explained in the notice of proposed 

rulemaking, the regulations 

promulgated in 2019 require state plan 

submissions to be made in accordance 

with 40 CFR 60.4. Pursuant to 40 CFR 

60.4(a), all requests, reports, 

applications, submittals, and other 

communications to the Administrator 

pursuant to 40 CFR part 60 shall be 

submitted in duplicate to the 

appropriate regional office of the EPA. 

The provision in 40 CFR 60.4(a) then 

proceeds to list the corresponding 

addresses for each regional office. The 

EPA proposed that, rather than 

requiring paper copies of state plan 

submissions to be sent to the 

appropriate regional office, states would 

submit their state plans electronically 

via the use of its State Planning 

Electronic Collaboration System 

(SPeCS). 

As previously described, CAA section 

111(d) requires the EPA to promulgate 

a ‘‘procedure’’ similar to that of CAA 

section 110 under which states submit 

plans. The statute does not prescribe a 

specific platform for plan submissions, 

and the EPA reasonably interprets the 

procedure it must promulgate under the 

statute as allowing it to require 

electronic submission. Requiring 

electronic submission is reasonable for 

the following reasons. Providing for 

electronic submittal of CAA section 

111(d) state plans in subpart Ba in place 

of paper submittals aligns with current 

trends in electronic data management 

and as implemented in the individual 

EGs will result in less burden on the 

states. It is the EPA’s experience that the 

electronic submittal of information 

increases the ease and efficiency of data 

submittal and data accessibility. The 

EPA’s experience with the electronic 

submittal process for SIPs under CAA 

section 110 has been successful as all 

the states are now using the SPeCS, 

which is a user-friendly, web-based 

system that enables state air agencies to 

officially submit SIPs and associated 

information electronically for review 

and approval to meet their CAA 

obligations related to attaining and 

maintaining the NAAQS. SPeCS for SIPs 

is the EPA’s preferred method for 

receiving such SIPs submissions. The 

EPA has worked extensively with state 

air agency representatives and partnered 

with E-Enterprise for the Environment 

and the Environmental Council of the 

States to develop this integrated 

electronic submission, review, and 

tracking system for SIPs. SPeCS can be 

accessed by the states through the EPA’s 

Central Data Exchange (CDX) (https://

cdx.epa.gov/). The CDX is the Agency’s 

electronic reporting site and performs 

functions for receiving acceptable data 

in various formats. The CDX registration 

site supports the requirements and 

procedures set forth under the EPA’s 

Cross-Media Electronic Reporting 

Regulation, 40 CFR part 3. 

Most of the commenters were 

supportive of the proposed amendments 

for electronically submitting state plans. 

However, a few commenters expressed 

that EPA should provide an option to 

submit state plans in paper format. The 

EPA has determined that submitting 

state plans electronically is more 

efficient and less burdensome than 

paper submittals. States already submit 

state implementation plans 

electronically via SPeCS so there should 

be little to no additional burden 

associated with using it for state plans. 

Additionally, having some states submit 

state plans via SPeCS and other states 

mail hard-copy plans to regional offices 

would undermine many of the 

efficiencies provided to the EPA 

through the use of electronic submission 

and could result in confusion. One 

commenter recommended adding 

language to clarify that a Negative 

Declaration letter submitted in 

accordance with 40 CFR 60.23a(b) can 

also be submitted via SPeCS. The EPA 

agrees with the need to add the 

electronic submittal language to 40 CFR 

60.23a(b) identified by the commenter 

and has added the language in the final 

rule so that the states submit the 

Negative Declaration letter using the 

SPeCS, or through an analogous 

electronic reporting tool provided by the 

EPA for the submission of any plan 

required by this subpart. 

The EPA is therefore finalizing the 

requirements for electronic submittal of 

state plans in 40 CFR 60.23a(a)(1) and 

(3). As finalized, 40 CFR 60.23a(a)(1) 

provides: ‘‘The submission of such plan 

shall be made in electronic format 

according with § 60.23a(a)(3) or as 

specified in an applicable emission 

guideline.’’ The regulation at 40 CFR 

60.23a(a)(3) in turn contains the general 

requirements associated with the 

electronic submittal of a state plan in 

subpart Ba via the use of SPeCS or 

through an analogous electronic 

reporting tool provided by the EPA for 

the submission of any plan required by 

subpart Ba. The EPA is also including 

at 40 CFR 60.23a(a)(3) language to 

specify that states are not to transmit 

confidential business information (CBI) 

through SPeCS. Even though state plans 

submitted to the EPA for review and 

approval pursuant to CAA section 

111(d) through SPeCS are not to contain 

CBI, the language at 40 CFR 60.23a(a)(3) 

also addresses the submittal of CBI in 

the event there is a need for such 

information to be submitted to the EPA. 


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153 87 FR 79176, 79206–07 (Dec. 23, 2022). 

154 87 FR 79176, 79207–08 (Dec. 23, 2022). 

155 80 FR 64662, 64720 (October 23, 2015). 

156See, e.g., id. at 64887. 

157 Id. at 64707. 

158 Id. at 64840. 

Any other specific requirements 

associated with the electronic submittal 

of a particular state plan will be 

provided within the corresponding EG. 

The requirements for electronic 

submission of CAA section 111(d) state 

plans in EGs will ensure that these 

Federal records are created, retained, 

and maintained in electronic format. 

Electronic submittal will also improve 

the Agency’s efficiency and 

effectiveness in the receipt and review 

of state plans. The electronic submittal 

of state plans may also provide 

continuity in the event of a disaster like 

the one our nation experienced with 

COVID–19. 

G. Other Proposed Modifications and 

Clarifications 

1. Standard of Performance and 

Compliance Flexibility 

a. Definition of Standard of Performance 

The EPA proposed amendments to 40 

CFR 60.21a(f) and 60.24a(b) to clarify 

that the definition of ‘‘standard of 

performance’’ allows for state plans to 

include standards in the form of an 

allowable mass limit of emissions. As 

explained in the notice of proposed 

rulemaking,153 the amendments were 

intended to harmonize these regulatory 

definitions with the definitions of 

‘‘emission limitation’’ and ‘‘emission 

standard’’ in CAA section 302(k), which 

is ‘‘a requirement established by the 

State or the Administrator which limits 

the quantity, rate, or concentration of 

emissions of air pollutants on a 

continuous basis, including any 

requirement relating to the operation or 

maintenance of a source to assure 

continuous emission reduction, and any 

design, equipment, work practice, or 

operational standard promulgated under 

this chapter.’’ While the EPA had 

intended the phrase ‘‘allowable rate or 

limit of emissions’’ in the existing 

regulatory definitions to encompass the 

full range of forms included in the 

statute, to eliminate any potential 

confusion the Agency proposed to make 

this explicit. 

Most comments received on the 

proposed revision to the definition of 

‘‘standard of performance’’ were in 

support of these amendments. Some 

commenters pointed out that the 

revision would be consistent with the 

statutory definition in CAA section 

302(k) and many expressed approval 

that the revised definition would clearly 

allow for standards of performance to 

take the form of mass-based emission 

limits. Several commenters stressed 

that, while they supported the proposed 

definition of standard of performance 

for subpart Ba, the appropriate form of 

the standard of performance in any 

particular EG must be determined in the 

context of that EG. Some commenters 

expressed concern that the proposed 

revision would allow the EPA to define 

the BSER as a trading program for any 

source sector, or for states and the EPA 

to impose emissions averaging and 

trading programs in CAA section 111(d) 

plans. 

The EPA is finalizing amendments to 

40 CFR 60.21a(f) and 60.24a(b) as 

proposed. The Agency’s interpretation 

of CAA section 111 with regard to 

emissions trading or averaging is a 

separate matter that is discussed in 

section III.G.1.b. of this preamble; it is 

reiterated that the revisions to the 

definition of standard of performance 

are being made to align it with the 

statutory definition of emission 

limitation and emission standard in 

CAA section 302(k) for the purpose of 

these general implementing regulations. 

The EPA agrees with commenters that 

the appropriate form of the standard of 

performance in any particular EG must 

be determined in the context of that EG, 

and the EPA may choose to prescribe 

the acceptable form or forms of the 

standard of performance in an 

individual EG. In addition to finalizing 

the proposed amendments to 40 CFR 

60.21a(f) to clarify that the term ‘‘an 

allowable rate or limit of emissions’’ 

means ‘‘an allowable rate, quantity, or 

concentration of emissions’’ of air 

pollutants, the EPA is also finalizing its 

proposed removal of the phrase ‘‘but not 

limited to’’ from 40 CFR 60.21a(f) as 

unnecessary and potentially confusing 

verbiage that is redundant of the word 

‘‘including,’’ particularly where the 

definition already identifies a wide 

breadth of potential standards that may 

be included in a state plan. Moreover, 

the EPA is finalizing amendments to the 

definition of standard of performance 

under 40 CFR 60.24a(b) to read ‘‘. . . in 

the form of an allowable rate, quantity, 

or concentration of emissions’’ rather 

than ‘‘. . . either be based on allowable 

rate or limit of emission.’’ 

b. Compliance Flexibilities, Including 

Trading or Averaging 

The EPA is finalizing its proposal that 

CAA section 111(a) and (d) cannot be 

interpreted, by their terms, to limit the 

types of controls that states, in their 

state plans, may authorize their sources 

to adopt to at-the-source, and thereby 

preclude states from authorizing their 

sources flexibilities such as trading or 

averaging. Under the provisions of CAA 

section 111(a) and (d), and consistent 

with the federalism principles that 

underlie the CAA, states have broad 

authority to determine the types of 

control measures for their sources, 

including trading or averaging, although 

the EPA may establish constraints to 

protect the integrity of particular EGs. 

The EPA is also finalizing its proposal 

that CAA section 111 cannot be 

interpreted, by its terms, to limit the 

‘‘best system of emission reduction . . . 

adequately demonstrated’’ (BSER) to atthe-source measures. As the EPA 

explains, many control measures that 

the EPA has determined to be the BSER 

in prior rules have outside-the-source 

components. The EPA is finalizing its 

repeal of the ACE Rule’s contrary 

interpretations of CAA section 111. 

In the proposal, the EPA provided a 

brief summary of the applicable CAA 

provisions, the ACE Rule, the D.C. 

Circuit’s decision reversing the ACE 

Rule, and the U.S. Supreme Court’s 

decision vacating the D.C. Circuit’s 

vacatur of the ACE Rule.154 For 

convenience, parts of that summary are 

reproduced here. 

i. CAA section 111. Under CAA 

section 111(d)(1), each state is required 

to submit to the EPA ‘‘a plan which . . . 

establishes standards of performance for 

any existing source’’ that emits certain 

types of air pollutants, and which 

‘‘provides for the implementation and 

enforcement of such standards of 

performance.’’ Under CAA section 

111(a)(1), a ‘‘standard of performance’’ 

is defined as ‘‘a standard for emissions 

of air pollutants which reflects the 

degree of emission limitation achievable 

through the application of the best 

system of emission reduction . . . 

adequately demonstrated.’’ 

ii. Rulemaking and caselaw. In the 

Clean Power Plan (CPP), the EPA 

interpreted the term ‘‘system’’ in CAA 

section 111(a)(1) to be broad and 

therefore to authorize the EPA to 

consider a wide range of measures from 

which to select the BSER.155 Similarly, 

the CPP took the position that states had 

broad flexibility in choosing compliance 

measures for their state plans.156 The 

CPP went on to determine that 

generation shifting qualified as the 

BSER,157 and that states could include 

trading or averaging programs in their 

state plans for compliance.158

The ACE Rule included the repeal of 

the CPP. It interpreted CAA section 111 

so that the type of ‘‘system’’ that the 

EPA may select as the BSER is limited 

to a control measure that could be 


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159 84 FR 32520, 32523–24 (July 8, 2019). 

160 Id. at 32556. 

161 Id. at 32556–57. 

162American Lung Ass’n v. EPA, 985 F.3d 914 

(D.C. Cir. 2021). 

163 Id. at 944–51 

164 Id. at 957–58. 

165West Virginia v. EPA, 142 S. Ct. 2587 (2022). 

166 Id. at 2601–02. 

167 Id. at 2614–16 (internal quotation marks 

omitted). 

168See id. at 2615 (‘‘We have no occasion to 

decide whether the statutory phrase ‘system of 

emission reduction’ refers exclusively to measures 

that improve the pollution performance of 

individual sources, such that all other actions are 

ineligible to qualify as the BSER.’’ (emphasis 

omitted)). 

169With respect to averaging, the ACE Rule noted 

that the D.C. Circuit has recognized that the EPA 

may have statutory authority under CAA section 

111 to allow plant-wide emissions averaging, See 

U.S. Sugar v. EPA, 830 F.3d 579, 627 n.18 (D.C. Cir. 

2016) (pointing to the definition of ‘‘stationary 

source’’), but stated that the Agency’s determination 

that individual EGUs are subject to regulation under 

ACE precludes the Agency from attempting to 

change the basic unit from an EGU to a combination 

of EGUs for purposes of ACE implementation. 

170 87 FR 79208. 

171 84 FR 32556. 

172 985 F.3d at 944–51. 

173 142 S. Ct. at 2615–16. 

174 87 FR 79208. 

175 Id. 

176 985 F.3d at 957–58. 

applied at each source (that is, inside 

the fenceline of each source) to reduce 

emissions at each source.159 The ACE 

Rule also concluded that the 

compliance measures the states include 

in their plans must ‘‘correspond with 

the approach used to set the standard in 

the first place,’’ 160 and therefore must 

also be limited to inside-the-fenceline 

measures that reduce the emissions of 

each source. For these reasons, the ACE 

Rule invalidated the CPP’s generationshifting system as the BSER, on grounds 

that it was an outside the source 

measure, and precluded states from 

allowing their sources to trade or 

average to demonstrate compliance with 

their emission standards.161

In 2021, the D.C. Circuit vacated the 

ACE Rule.162 The court held, among 

other things, that CAA section 111(d) 

does not limit the EPA, in determining 

the BSER, to at-the- source measures.163

The court further held that the ACE 

Rule’s premise for viewing compliance 

measures as limited to at the source 

measures, which is that BSER measures 

are so limited, was invalid for the same 

reason. The court indicated that while 

requiring symmetry between the nature 

of the BSER and compliance measures 

‘‘would be reasonable’’ where necessary 

to preserve the environmental outcomes 

a particular BSER was designed to 

achieve, a universal restriction on 

compliance measures could not be 

sustained by policy concerns that were 

not similarly universal.164

In 2022, the U.S. Supreme Court 

reversed the D.C. Circuit’s vacatur of the 

ACE Rule’s embedded repeal of the 

Clean Power Plan.165 The Supreme 

Court made clear that CAA section 111 

authorizes the EPA to determine the 

BSER and the amount of emission 

limitation that state plans must 

achieve.166 However, the Supreme Court 

invalidated the CPP’s generationshifting BSER under the major question 

doctrine, explaining that the term 

‘‘system’’ does not provide the ‘‘clear 

congressional authorization’’ needed to 

support a BSER ‘‘of such magnitude and 

consequence.’’ 167 The Court declined to 

address the D.C. Circuit’s decision that 

the text of CAA section 111 did not 

limit the type of ‘‘system’’ the EPA 

could consider as the BSER to at-thesource measures.168 Nor did the Court 

rule on the scope of the states’ 

compliance flexibilities. 

iii. Proposal. In the proposal, the EPA 

stated that it has reconsidered the ACE 

Rule’s interpretation of the compliance 

flexibilities available to states under 

CAA section 111 and that it was 

proposing to disagree with the rule’s 

view that trading or averaging are 

universally precluded 169 and that state 

plan compliance measures must always 

correspond with the approach the EPA 

uses to set the BSER. The EPA added, 

however, that the flexibility that CAA 

section 111(d) grants to states in 

adopting measures for their state plans 

is not unfettered; rather, CAA section 

111(d)(2) requires the EPA to review 

state plans to ensure that they are 

‘‘satisfactory,’’ and the EPA may 

conclude in particular emission 

guidelines that limiting the types of 

control measures states may authorize 

their sources to adopt, including 

precluding trading or averaging, are 

necessary to protect the environmental 

outcomes of the emission guidelines.170

In addition, the EPA also proposed to 

reject the ACE Rule’s interpretation that 

various provisions in CAA section 111 

limit the type of ‘‘system’’ that may 

qualify as the BSER to at-the-source 

measures.171 The EPA explained that it 

proposed to agree with the part of the 

D.C. Circuit’s decision in American 

Lung Ass’n,172 that rejected the ACE 

Rule’s at-the-source statutory 

interpretation. The EPA added that it 

recognized that the Supreme Court, in 

West Virginia, did impose limits, 

through the application of the major 

question doctrine, on the type of 

‘‘system’’ that may qualify as the 

BSER.173 The EPA made clear that it 

was not proposing to address the scope 

of the limits that may result from 

application of the major question 

doctrine, and thus was not proposing to 

address whether it could include 

trading or averaging as part of the BSER, 

or to identify any particular control 

mechanism that could or could not be 

part of a specific BSER, in light of those 

limits. Instead, the EPA stated that it 

may address further those limits, and 

their implications for the legality of 

particular systems of emission reduction 

and state compliance measures, in 

future emission guidelines.174

iv. The EPA’s finalized interpretation 

of state authority to grant compliance 

flexibilities. The EPA is finalizing its 

proposal that, contrary to the position of 

the ACE Rule, CAA section 111 does not 

preclude states from including 

compliance flexibilities such as trading 

or averaging for their sources in their 

state plans, although in particular 

emission guidelines the EPA may limit 

those flexibilities if necessary to protect 

the environmental outcomes of the 

guidelines. The EPA is also rescinding 

the related ACE Rule interpretation that 

CAA section 111 requires that state plan 

measures be symmetrical to the types of 

measures the EPA included in the 

BSER. 

Most commenters agreed with the 

proposal that CAA section 111 does not 

preclude states from including 

compliance flexibilities in their state 

plans. However, several commenters 

disagreed and submitted adverse 

comments. Some commenters stated 

that West Virginia is clear that the EPA 

cannot include generation-shifting as 

the BSER, and then argued that the EPA 

cannot include trading as part of the 

BSER because trading entails generation 

shifting, and then further argued that for 

emission guidelines applicable to 

electric generating units, the EPA 

cannot authorize trading as a 

compliance mechanism because trading 

incentivizes generation shifting to occur 

and only works if generation shifting 

does occur. As explained further below, 

the EPA does not believe that these 

adverse comments cast doubt on the 

rationale that it gave in the proposal for 

why states have the authority to allow 

compliance flexibilities such as trading 

or averaging.175 The EPA continues to 

agree with the reasoning in American 

Lung Ass’n,176 in rejecting the ACE 

Rule’s limitations on those measures. 

To review the reasons that the ACE 

Rule gave for asserting that trading or 

averaging across designated facilities is 

inconsistent with CAA section 111: The 

ACE Rule stated that those options 

would not necessarily require any 

emission reductions from designated 


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177This paraphrasing by the ACE Rule of the CAA 

section 111(a)(1) definition of ‘‘standard of 

performance’’ is incomplete—a ‘‘standard of 

performance’’ ‘‘reflects the degree of emission 

limitation achievable through the application of the 

best system of emission reduction.’’ 

178 84 FR 32557. 

179This overall level of emissions reduction is the 

level that would be achieved if each source were 

to apply the BSER. 

180 84 FR 32556 (ACE Rule states that one reason 

why CAA section 111 precludes states from 

authorizing trading or averaging is that ‘‘[a]pplying 

an implementation approach that differs from 

standard-setting would result in asymmetrical 

regulation’’). 

181See CAA section 111(d)(2)(A) (referring to 

CAA section 110(c)), 111(d)(2)(B) (referring to 

enforcement of state implementation plans (SIPs)). 

182Alaska Dep’t of Envtl. Conservation v. EPA, 

540 U.S. 461, 470 (2004) (citation omitted); see 

Union Elec. Co. v. EPA, 427 U.S. 246, 269 (1976) 

(‘‘Congress plainly left with the States, so long as 

the national standards were met, the power to 

determine which sources would be burdened by 

regulation and to what extent.’’); Train v. Natural 

Res. Def. Council, Inc., 421 U.S. 60, 79 (1975) (‘‘[S]o 

long as the ultimate effect of a State’s choice of 

emission limitations is compliance with the 

national standards for ambient air, the State is at 

liberty to adopt whatever mix of emission 

limitations it deems best suited to its particular 

situation.’’). 

183The ACE Rule stated that the reference in CAA 

section 111(d)(1) to CAA section 110 was limited 

to the procedure under which states shall submit 

plans to the EPA, and asserted that it does not 

imply anything about implementation mechanisms 

available under CAA section 111(d). 84 FR 32557. 

The EPA believes that the several references to CAA 

section 110 in CAA section 111(d)(1) and (2), as 

noted in the accompanying text, support the view 

that Congress intended that state plans under CAA 

section 111(d) would be similar to state plans under 

CAA section 110, including retaining the authority 

to grant sources compliance flexibility in 

appropriate circumstances. 

184American Elec. Power Co. v. Connecticut, 564 

U.S. 410, 428 (2011) (citations omitted). 

185 70 FR 28606, 28617 (May 18, 2005), vacated 

on other grounds, New Jersey v. EPA, 517 F.3d 574 

(D.C. Cir. 2008), see 40 CFR 60.24(b)(1) (2005) 

(providing that a state’s ‘‘[e]mission standards [may] 

be based on an allowance system), repealed in the 

ACE Rule. 

186 80 FR 64662, 64840 (October 23, 2015), 

repealed by the ACE Rule. 87 FR 79208. 

187 142 S. Ct. at 2602. 

188 Id. 

facilities and may not actually reflect 

application of the BSER. The ACE Rule 

explained that ‘‘state plans must 

establish standards of performance— 

which by definition ‘reflects . . . the 

application of the best system of 

emission reduction,’ ’’ 177 and then 

asserted that implementation and 

enforcement of such standards should 

be based on improving the emissions 

performance of sources to which a 

standard of performance applies. The 

ACE Rule added that trading or 

averaging would effectively allow a state 

to establish standards of performance 

that do not reflect application of the 

BSER, and gave, as an example, the 

possibility that under a trading program, 

a single source could potentially shut 

down or reduce utilization to such an 

extent that its reduced or eliminated 

operation generates sufficient 

allowances for a state’s remaining 

sources to meet their standards of 

performance without themselves 

making any emission reductions from 

any other source. The ACE Rule asserted 

that this compliance strategy would 

undermine the EPA’s determination of 

the BSER.178

This interpretation of CAA section 

111 is unduly strained and the EPA 

rejects it. The provisions of CAA section 

111(d) by their terms do not 

affirmatively bar states from considering 

trading or averaging as a compliance 

measure where appropriate for a 

particular emission guideline. Under 

CAA section 111(d)(1), each state must 

‘‘establish[ ],’’ ‘‘implement[ ],’’ and 

‘‘enforce[ ]’’ ‘‘standards of performance 

for any existing source.’’ A state plan 

may ‘‘establish[ ]’’ a standard of 

performance for each source that 

constitutes an emissions standard that 

reflects the amount of emission 

reduction that the source could achieve 

by applying the BSER, but the state may 

also allow measures like trading or 

averaging as potential means of 

compliance. Nothing in the text of CAA 

section 111 precludes states from 

considering a source’s acquisition of 

allowances as part of a trading program 

in ‘‘implement[ing]’’ and ‘‘enforce[ing]’’ 

a standard of performance for that 

particular source, so long as the state 

plan achieves the required overall level 

of emission reductions.179 CAA section 

111(d)(1) requires only that each source 

comply with its standard, not that each 

source do so through applying the 

BSER. By the same token, contrary to 

the ACE Rule,180 CAA section 111(d)(1) 

does not limit the states to compliance 

measures that are symmetrical to what 

the EPA determined to be the BSER 

unless necessary to preserve the 

environmental outcomes a particular 

system was designed to achieve. 

For further support for the 

interpretation that CAA section 111 

does not preclude states from 

authorizing compliance flexibilities 

such as trading or averaging, the EPA 

notes that CAA section 111(d)(1) 

requires a ‘‘procedure similar to that 

provided by [CAA section 110].’’ 181

Consideration of the CAA section 110 

framework reinforces the absence of any 

mandate that states consider only 

compliance measures that apply at and 

to an individual source. ‘‘States have 

‘wide discretion’ in formulating their 

plans’’ under section 110.182 The EPA 

has authorized trading programs in CAA 

section 110 SIPs for decades. See 

Economic Incentive guidance.183

Such flexibility is consistent with the 

framework of cooperative federalism 

that CAA section 111(d) establishes, 

which vests states with substantial 

discretion in establishing control 

requirements for their sources. As the 

U.S. Supreme Court has explained, CAA 

section 111(d) ‘‘envisions extensive 

cooperation between Federal and state 

authorities, generally permitting each 

State to take the first cut at determining 

how best to achieve EPA emissions 

standards within its domain.’’ 184

This interpretation is also consistent 

with the EPA’s consistent views prior to 

the ACE Rule. The EPA authorized 

trading or averaging as compliance 

methods in the 2005 Clean Air Mercury 

Rule for coal-fired EGUs,185 and the 

2015 Clean Power Plan (CPP).186

It must be emphasized that the EPA 

retains an important role in reviewing 

state plans for adequacy. Under CAA 

section 111(d)(2)(A), the EPA must 

determine that the state plan is 

‘‘satisfactory’’ and, if the state plan is 

not satisfactory or if the state does not 

submit a state plan, the EPA must 

promulgate a plan that establishes 

Federal standards of performance for the 

State’s existing sources. Thus, the 

flexibility that CAA section 111(d)(1) 

grants to states in adopting measures for 

their state plans is not unfettered. As the 

Supreme Court stated in West Virginia, 

‘‘The Agency, not the States, decides the 

amount of pollution reduction that must 

ultimately be achieved.’’ 187 The Court 

further stated that state plans must 

contain ‘‘emissions restrictions that they 

intend to adopt and enforce in order not 

to exceed the permissible level of 

pollution established by EPA.’’ 188 Thus, 

the EPA retains the authority to ensure 

that the permissible level of pollution is 

not exceeded by any state plan. If the 

EPA considers that compliance 

flexibility measures would compromise 

the ability of the state plan to achieve 

the environmental outcomes the best 

system could achieve, the EPA may, in 

the emission guidelines, preclude such 

measures or otherwise conclude that the 

state plan is not satisfactory. 

In West Virginia v. EPA, the Supreme 

Court did not directly address the state’s 

authority to determine their sources’ 

control measures. Although the Court 

did hold that constraints apply to the 

EPA’s authority in determining the 

BSER, the Court’s discussion of CAA 

section 111 is consistent with the EPA’s 

interpretation that the provision does 

not preclude states from granting 

sources compliance flexibility. 

At the outset of the decision, the 

Court made clear CAA section 111 


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189West Virginia v. EPA, 142 S.Ct. at 2601–02 

(citations omitted). 

190 Id. at 2600 (‘‘The question before us is whether 

this broad[ ] conception of EPA’s authority [to 

determine the BSER] is within the power granted 

to it by the Clean Air Act.’’). 

191 Id. at 2609. 

192 Id. at 2601. 

193 Id. at 2613 n.4. 194Comment Letter from Energy Strategy 

Coalition on ‘‘Adoption and Submittal of State 

Plans for Designated Facilities: Implementing 

Regulations Under Clean Air Act Section 111(d), 

EPA–HQ–OAR–2021–0527–0088 at 6. 

195 142 S.Ct. at 2615–16. 

196 84 FR 32523–24. 

197 Id. at 32556–57. 

provides different roles for the EPA and 

the States: 

Although the States set the actual rules 

governing existing power plants, EPA itself 

still retains the primary regulatory role in 

Section 111(d). The Agency, not the States, 

decides the amount of pollution reduction 

that must ultimately be achieved. It does so 

by again determining, as when setting the 

new source rules, ‘‘the [BSER]. . . . The 

States then submit plans containing the 

emissions restrictions that they intend to 

adopt and enforce in order not to exceed the 

permissible level of pollution established by 

EPA.189

The Court was clear that the focus of 

the case was exclusively on the EPA’s 

role, that is, whether the EPA acted 

within the scope of its authority in 

establishing the BSER.190 The Court 

applied the major question doctrine to 

hold that the generation-shifting BSER 

that the EPA promulgated in the CPP 

exceeded the constraints of the CAA 

section 111 BSER provisions, in light of 

‘‘separation of powers principles and a 

practical understanding of legislative 

intent.’’ 191 The Court did not identify 

any constraints on the states in 

establishing standards of performance to 

their sources, and its holding and 

reasoning cannot be extended to apply 

such constraints. In fact, the Supreme 

Court at least implicitly recognized that 

CAA section 111(d) does not preclude 

states from authorizing sources 

compliance flexibility when the Court 

observed that a new or modified source 

‘‘may achieve [the EPA-determined] 

emissions [standard] any way it 

chooses.’’ 192 There is no reason why 

existing sources should have less 

flexibility. 

It should also be noted that the 

adverse commenters described above 

are incorrect in their view that trading 

necessarily results in generation shifting 

and that the logic of the West Virginia 

decision precludes any such generation 

shifting. As just noted, the reasons why 

the Court held that the CPP’s 

generation-shifting BSER violated the 

major question doctrine and thus was 

invalid have no application to states in 

developing state plans. In addition, the 

Court was clear that a BSER that has the 

incidental effect of resulting in 

generation shifting would not, on those 

grounds, violate the major question 

doctrine. The Court emphasized that 

‘‘there is an obvious difference between 

(1) issuing a rule that may end up 

causing an incidental loss of coal’s 

market share, and (2) simply 

announcing what the market share of 

coal, natural gas, wind, and solar must 

be, and then requiring plants to reduce 

operations or subsidize their 

competitors to get there.’’ 193 The second 

option is what the Court viewed the 

CPP’s generation-shifting BSER as 

attempting to do, which thereby triggers 

the major question doctrine. But, as a 

coalition of companies that operate 

electricity generation as well as 

transmission and distribution systems 

commented, the Court ‘‘evinced no 

general concern about option 1, which 

is an inevitable consequence of 

regulation within the power sector, in 

which all sources of emissions are 

interconnected and increase or decrease 

their generation based upon demand for 

electricity and other sources’ 

availability.’’ 194 If the Court in West 

Virginia had little concern with the EPA 

determining a BSER that has the 

incidental effect of shifting generation, 

there is no basis for reading the case to 

preclude a state from adopting trading 

measures in its state plan on grounds 

that those measures may have the 

incidental effect of shifting generation. 

In any event, in many instances, trading 

simply apportions the cost of controls 

between the sources engaged in the 

transaction, and does not result in 

generation shifting. To illustrate, 

assume that the EPA promulgates an 

emissions guideline that determines as 

the BSER the installation by a source of 

control equipment that captures 40 

percent of its emissions of a pollutant. 

Assume further that a state allows two 

of its designated facilities of comparable 

size and emissions to engage in an 

emission trade, so that one source 

installs control equipment that captures 

80 percent of its emissions, and the 

other one does not put on control 

equipment but purchases allowances 

from the first one that fund half the 

costs of the first one’s control 

equipment. This type of emissions trade 

would not necessarily give rise to 

generation shifting. 

For the reasons noted above, the EPA 

is rescinding the ACE Rule’s 

interpretation that state plans may not 

include trading or averaging or other 

compliance flexibilities. 

v. The EPA’s finalized interpretation 

of BSER. The EPA is also finalizing its 

proposal to rescind the ACE Rule’s 

interpretation that CAA section 111, by 

its plain meaning, limits the BSER to atthe-source measures. The ACE Rule’s 

interpretation is incorrect. In addition, 

as a practical matter, it could call into 

question many of the EPA’s 

determinations in prior CAA section 

111 rules that well-established control 

measures, including clean fuels and 

add-on control technology, qualified as 

the BSER. This is because many of these 

traditional measures are not entirely atthe-source controls, but also include 

outside-the-source components. West 

Virginia does not preclude the EPA from 

rescinding the ACE Rule interpretation 

because although the Supreme Court 

held that the CPP’s generation-shifting 

BSER violated the major question 

doctrine, Court declined to address the 

ACE Rule’s interpretation of CAA 

section 111.195

To repeat for convenience the key 

requirements for determining the BSER 

under CAA section 111: each state must 

establish ‘‘standards of performance for 

any existing source’’ of certain types of 

air pollutants, under CAA section 

111(d)(1); a ‘‘standard of performance’’ 

is defined as ‘‘a standard for emissions 

of air pollutants which reflects the 

degree of emission limitation achievable 

through the application of the best 

system of emission reduction . . . 

adequately demonstrated, under CAA 

section 111(a)(1);’’ and ‘‘existing 

source’’ is defined as a ‘‘stationary 

source,’’ which, in turn, is defined, in 

relevant part, as ‘‘any building, 

structure, facility or installation,’’ under 

CAA section 111(a)(6) and (a)(3). 

The ACE Rule interpreted CAA 

section 111 to limit, by its plain 

language, the type of ‘‘system’’ that the 

EPA may select as the BSER to control 

measures that can be applied at each 

source to reduce that source’s 

emissions.196 Specifically, the ACE Rule 

argued that the requirements in CAA 

section 111(d)(1), (a)(3), and (a)(6) that 

each state establish a standard of 

performance ‘‘for’’ ‘‘any existing source’’ 

(in the singular), defined, in general, as 

any ‘‘building . . . [or] facility,’’ and the 

requirements in CAA section 111(a)(1) 

that the standard of performance reflect 

a degree of emission limitation that is 

‘‘achievable’’ through the ‘‘application’’ 

of the BSER, by their terms, impose this 

limitation.197

Upon reconsideration, the EPA 

concludes that, contrary to the ACE 

Rule, CAA section 111(d) does not limit 

the EPA to at-the-source measures in 

determining the BSER. The CAA section 


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198 Id. at 32524. 

199 985 F.3d at 948 (citations omitted). 

200 Id. 

201The ACE Rule stated that the CAA provisions 

concerning the ‘‘best available control technology’’ 

(BACT) provide a CAA structural argument that 

supports its interpretation that CAA section 111 

limits BSER to at-the-source measures. CAA section 

165(a)(4) provides that construction and 

modification of major stationary sources of a 

pollutant are subject to BACT, as defined under 

CAA section 169(3), for each pollutant subject to 

regulation under the CAA. The definition of BACT 

provides, ‘‘In no event shall application of [BACT] 

result in emissions of any pollutants which will 

exceed the emissions allowed by any applicable 

standard established pursuant to [CAA] section 

[111] or [112].’’ The ACE Rule pointed to the EPA’s 

reading of this sentence to mean that section 111 

standards of performance ‘‘operate as a floor to 

BACT.’’ The ACE Rule asserted that, under the 

definition of BACT, control measures are limited to 

at-the-source measures. The ACE Rule reasoned that 

section 111 standards of performance must, by 

operation of the structure of the CAA, also be 

interpreted to be limited to at-the-source measures. 

84 FR 32525. Upon further review, the EPA rejects 

this argument. The EPA considers whether CAA 

section 169(3) should be interpreted to limit BACT 

to at-the-source measures to be an open question, 

and is not addressing it at this time. Even if BACT 

were so limited, the ACE Rule did not demonstrate 

that any BACT requirement that a particular source 

would be subject to would be incompatible with 

any standard of performance that source would also 

be subject to. Section 169(3) by its plain language 

provides that the application of BACT may not 

result in exceedances of any applicable standard of 

performance. 

The ACE Rule also focused on statements in the 

CPP that it asserted conflated the terms 

‘‘application’’ and implementation, as well as 

‘‘source’’ and owner/operator; and that defined 

‘‘system’’ broadly. The rule asserted that the CPP 

strained the interpretation of CAA section 111 in 

those ways to justify determining generationshifting as the BSER. 84 FR 32526–29. Regardless 

of whether those arguments have merit with respect 

to the generation-shifting, they are not relevant to 

the position that the EPA is taking in the present 

action that the ACE Rule erred in interpreting CAA 

section 111 by its terms to limit the BSER to at-thesource measures. It should also be noted that the 

CPP’s recognition that as a practical matter, it is the 

owner/operator who takes actions to apply control 

measures and assure that the source’s emissions 

meet the standard is a matter of common sense and 

applies as well to all control measures, whether at 

the source or outside the source. The ACE Rule 

itself referred to the ‘‘owner or operator’’ as the 

entity that ‘‘must be able to achieve an applicable 

standard by applying the BSER . . . .’’ 84 FR 

32524. 

202 84 FR 32534 n.152 (referring to application of 

‘‘energy requirements’’). 

203 84 FR 32525–26. 

204 Id. at 32526. 

205 Id. at 32526 n.61. The ACE Rule argued that 

the canon of ejusdem generis required that those 

broader terms be interpreted to denote at-the-source 

measures but ejusdem generis is an aid in statutory 

construction and should not be used to narrow the 

meaning of a statute beyond its intention. Karl N. 

Llwellyn, Remarks on the Theory of Appellate 

Decision and the Rules or Canons about how 

Statutes are to be Construed, 3 Vanderbilt L. Rev. 

395, 405 & n.46 (1950). 

206 Id. at 32526 n.61. 

111 requirement that each state 

establish a standard of performance 

‘‘for’’ any existing ‘‘building . . . [or] 

facility,’’’ means simply that the state 

must establish standards applicable to 

each regulated stationary source; and 

the requirement that the standard reflect 

a degree of emission limitation 

‘‘achievable’’ through the ‘‘application’’ 

of the BSER means that the source must 

be able to apply the system to meet the 

standard. None of these requirements by 

their plain language mandate that the 

BSER is limited to some measure that 

each source can apply to its own facility 

to reduce its own emissions in a 

specified amount. That the standards 

must be ‘‘for’’ a source does not mean 

that the control measures that form the 

basis for the standard are limited to 

measures that apply at the source or that 

all emission reductions from the control 

measures must occur at the source. 

The ACE Rule also argued that as a 

matter of grammar, the term 

‘‘application,’’ which is derived from 

the verb, ‘‘to apply,’’ requires an 

indirect object, and, further, that the 

phrase ‘‘application of the best system 

of emission reduction’’ has, as the 

unstated indirect object, an existing 

source. From this premise, the ACE Rule 

concluded that the phrase must be read 

to refer to the application of the best 

system of emission reduction at or to the 

existing source itself.198 But this 

premise is incorrect. As the D.C. Circuit 

explained in American Lung Ass’n, 

‘‘application’’ is a noun, and ‘‘the 

phrase ‘application of the best system of 

emission reduction’ is what is called a 

nominalization, a ‘result of forming a 

noun or noun phrase from a clause or 

a verb.’ ’’ 199 The court further explained 

that ‘‘[g]rammar assigns direct or 

indirect objects only to verbs—not 

nouns. No objects are needed to 

grammatically complete the actual 

statutory phrase.’’ 200 In any event, the 

fact that any such indirect object is 

unstated itself contradicts the ACE 

Rule’s conclusion that CAA section 111 

by its plain language mandates that the 

BSER must be limited to at-the-source 

measures.201

It should also be noted that CAA 

section 111(a)(1) provides that when the 

EPA determines the BSER, it must 

‘‘tak[e] into account’’ ‘‘cost’’ and ‘‘any 

nonair quality health and environmental 

impact and energy requirements.’’ As 

the ACE Rule itself recognized, the EPA 

may consider the application of these 

requirements on a ‘‘sector-wide, regionwide or nationwide basis.’’ 202 As 

discussed below, the reference to 

‘‘nonair quality health and 

environmental impact’’ may encompass 

to offsite impacts of control measures. 

Thus, these provisions contradict the 

ACE Rule’s argument that CAA section 

111(d)(1) and (a), by its plain language, 

limits the BSER to at-the-source 

measures. By the same token, the term 

‘‘achievable’’ refers to the ‘‘degree of 

emission limitation’’ that must be 

‘‘reflect[ed]’’ in the standards of 

performance ‘‘through the application of 

the [BSER].’’ This term does not, by its 

plain language, limit the BSER to at-thesource measures. 

Importantly, it should be emphasized 

that the ACE Rule’s interpretation that 

the provisions of CAA section 111(d)(1) 

and (a) by their plain language require 

that the EPA identify as the BSER 

control measures that apply at-thesource would also impose the same 

limit on the state, that is, limit the state 

to authorizing its sources to comply 

with their standards only through atthe-source measures. As a result, this 

interpretation would preclude the state 

from allowing its sources compliance 

flexibilities such as trading or averaging. 

In fact, the ACE Rule argued that states 

were limited in that manner. For the 

reasons noted above, limiting the states 

in that manner is contrary to the 

provisions of CAA section 111(d) and 

the framework of cooperative federalism 

that CAA section 111(d) establishes. 

The ACE Rule also argued that the 

legislative history of the 1970 CAA 

Amendments confirms the rule’s at-thesource interpretation for BSER.203 The 

rule read the legislative history to 

indicate that the House and Senate bills 

that led to the adoption of CAA section 

111 ‘‘contemplated only control 

measures that would lead to better 

design, construction, operation, and 

maintenance of an individual 

source. . . .’’ 204 The EPA disagrees 

with this interpretation of the legislative 

history. The ACE Rule itself 

acknowledged that the 1970 CAA 

Amendments legislative history also 

included broader language in describing 

the types of measures that were to 

provide the basis for the standards of 

performance.205 In addition, the ACE 

Rule went on to narrow its argument 

about legislative history to saying that 

the 1990 CAA Amendments made clear 

only that generation-shifting was 

precluded.206 Id. at 32526 n.62. Thus, 

the EPA finds that the legislative history 

cannot be read to confirm the 

interpretation that section 111(d) and 

(a)(1), by their plain language, limit the 

BSER to at-the-source measures. 

There is another reason why the ACE 

Rule’s interpretation is incorrect: it 

appears to be inconsistent with many 

EPA determinations in previous CAA 

section 111 rulemakings that certain 

control measures qualified as the BSER. 

This is because although those measures 

apply at the source and reduce 


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207 142 S.Ct.at 2611 (citing 80 FR 64662, 64784 

(Oct. 23, 2015)). 

208 Id. (citing 80 FR 64784). 

209 142 S.Ct. at 2610. 

210 Id. (quoting 80 FR 64738). 

211 Id. at 2611. 

212 Id. 

213EPA considered fuel cleaning to be within the 

scope of the best system of emission reduction 

beginning immediately after the adoption of the 

1970 CAA Amendments. See U.S. EPA, Background 

Information for Proposed New-Source Performance 

Standards: Steam Generators, Incinerators, 

Portland Cement Plants, Nitric Acid Plants, Sulfuric 

Acid Plants, Office of Air Programs Tech. Rep. No. 

APTD–0711, p. 7 (Aug. 1971) (indicating the 

‘‘desirability of setting sulfur dioxide standards that 

would allow the use of low-sulfur fuels as well as 

fuel cleaning, stack-gas cleaning, and equipment 

modifications’’ (emphasis added)). 

214 1977 CAA Amendments, section 109, 91 Stat. 

700; see also CAA section 111(a)(7). 

215H.R. Rep. No. 95–294 (May 12, 1977), 1977 

CAA Legis. Hist. at 2655 (emphasis added). 

216 Id. EPA recognized in a regulatory analysis of 

new source performance standards for industrialcommercial-institutional steam generating units 

that the technology ‘‘requires too much space and 

is too expensive to be employed at individual 

industrial-commercial-institutional steam 

generating units.’’ U.S. EPA, Summary of 

Regulatory Analysis for New Source Performance 

Standards: Industrial-Commercial-lnstitutional 

Steam Generating Units of Greater than 100 Million 

Btu/hrHeat Input, EPA–450/3–86–005, p. 4–4 (June 

1986). 

217 40 CFR 60.49b(n)(4); see also Amendments to 

New Source Performance Standards (NSPS) for 

Electric Utility Steam Generating Units and 

Industrial-Commercial-Institutional Steam 

Generating Units; Final Rule, 72 FR 32742 (June 13, 

2007). 

218 142 S.Ct. at 2611. 

219See Sierra Club v. Costle, 657 F.2d 298, 375 

(D.C. Cir. 1981). 

220See id. at 323–24 n.69; see also 80 FR 21303, 

21340 (April 17, 2015) (governing off-site disposal 

of solid wastes captured by air pollution controls 

at steam units). 

221 80 FR 64549, 64555 (describing CCS and 

comparing CCS pollutant disposition to particulate 

or wet scrubber pollutant disposition). 

222See, e.g., 80 FR 64582–90 (requiring that an 

EGU that captures CO2 assure that it is transferred 

to an entity that will dispose of it appropriately; 

generally describing oversight of CO2 storage; 

detailing Department of Transportation pipeline 

regulations; detailing requirements for monitoring, 

reporting, and verification plans; detailing injection 

well requirements under the Safe Drinking Water 

Act; and detailing how existing regulations prevent, 

monitor, and address potential leakage); 75 FR 

54970, 55022–23 (Sept. 9, 2010) (disposal of 

wastewater and solid waste from CAA section 111 

standard for Portland cement plants); 54 FR 34008, 

34015 (Aug. 17, 1989) (waste disposal impacts of 

standard of performance for sulfur oxide emissions 

for fluid catalytic cracking unit regenerators). 

223See 80 FR 64549, 64555 (describing CCS and 

comparing CCS pollutant disposition to particulate 

or wet scrubber pollutant disposition). 

224Pub. L. 95–95, section 109(c)(1)(A) (Aug. 7, 

1977), 91 Stat. 699–700. 

225H.R. Rep. No. 95–294 at 190 (May 12, 1977). 

226 Id. 

emissions at the source, they also have 

components that are outside the source. 

In West Virginia, the Supreme Court 

recognized that the EPA had, in prior 

rules, identified as the BSER these 

‘‘‘more traditional air pollution control 

measures.’ ’’207 The Court made this 

point as part of its reasoning that the 

CPP’s generation-shifting BSER—which 

the Court stated differed from these 

traditional measures—raised a major 

question. The Court quoted the CPP as 

describing these traditional measures as 

‘‘‘efficiency improvements, fuelswitching,’’ and ‘add-on controls.’ ’’ 208

The Court noted that these types of 

controls have several characteristics: 

they ‘‘reduce pollution by causing the 

regulated source to operate more 

cleanly.’’ 209 They ‘‘ ‘allow[ ] regulated 

entities to produce as much of a 

particular good as they desire provided 

that they do so through an appropriately 

clean (or low-emitting) process.’ ’’ ’210

They are ‘‘technology-based . . . [and] 

focuse[d] on improving the emissions 

performance of individual sources.’’ 211

However, many of these traditional 

controls also have components that are 

outside the source. One example 

includes what the Court, quoting the 

CPP, identified as ‘‘fuel-switching.’’ 212

Fuel-switching entails the use of loweremitting fuels. These include fuels that 

have been cleaned, or processed, to 

reduce their level of pollutants,213 such 

as coal or oil that has been desulfurized. 

Desulfurization reduces the amount of 

sulfur in the fuel, which means that the 

fuel can be combusted with fewer SO2

emissions. Importantly, the process of 

desulfurization typically occurs off-site 

and is undertaken by third parties. 

Congress itself recognized this in the 

1977 CAA Amendments. Specifically, 

Congress revised CAA section 111(a)(1) 

to identify the basis for standards of 

performance for new fossil fuel-fired 

stationary sources as a ‘‘technological 

system of continuous emission 

reduction,’’ including ‘‘precombustion 

cleaning or treatment of fuels.’’ 214 The 

1977 House Committee report stated 

that fuel cleaning includes ‘‘oil 

desulfurization at the refinery.’’ 215 The 

report added that fuel cleaning includes 

‘‘various coal-cleaning technologies,’’ 

which generally are also conducted offsite by third parties.216 As noted above, 

in the 1990 CAA Amendments, 

Congress eliminated many of the 

restrictions and other provisions added 

in the 1977 CAA Amendments by 

largely reinstating the 1970 CAA 

Amendments’ definition of ‘‘standard of 

performance.’’ Nevertheless, there is no 

indication that in doing so, Congress 

intended to preclude the EPA from 

considering fuel cleaning off-site by 

third parties. In fact, the EPA’s 

regulations promulgated after the 1990 

CAA Amendments continue to impose 

standards of performance that are based 

on coal cleaning off-site by third 

parties.217

A second example includes what the 

Court, again quoting the CPP, identified 

as ‘‘add-on controls.’’ 218 These controls 

include air pollution control devices 

that are installed at the unit. They 

routinely operate by removing air 

pollutants from a unit’s emission stream 

and capturing them as a liquid or solid. 

For example, a baghouse is an add-on 

control device that captures particulate 

matter by trapping particles as a dust, 

which must then be disposed of.219

Another add-on control device, flue-gas 

desulfurization, ‘‘scrubs’’ acid gases like 

sulfur dioxide from emissions using a 

chemical sorbent that reacts with the 

pollutant to generate a liquid slurry (wet 

scrubbing) or solid residue (dry 

scrubbing). These captured pollutants 

must then be disposed as solid wastes, 

discharged as wastewater, or otherwise 

managed or reused.220 The same is true 

for carbon capture and sequestration 

(CCS): the carbon capture control device 

scrubs CO2 from the flue gas stream 

using a solvent; and the CO2 must then 

be stored underground.221 Downstream 

management of captured pollutants is 

thus a commonplace feature of CAA 

section 111 standards.222 Downstream 

management of captured pollutants is 

thus a commonplace feature of CAA 

section 111 standards.223

Indeed, CAA section 111(a)(1) by its 

terms recognizes that ‘‘system[s] of 

emission reduction’’ may entail off-site 

disposition of pollutants. The provision 

states that the EPA must consider 

‘‘nonair quality health and 

environmental impact’’ when 

determining the BSER. Congress 

adopted this phrase in the 1977 CAA 

Amendments.224 As the legislative 

history stated, Congress added this 

phrase so that ‘‘environmental impacts 

would be required to be considered in 

determining best technology which has 

been adequately demonstrated.’’ 225 In 

making this addition, Congress codified 

the D.C. Circuit’s holding in Essex 

Chem. Corp. v. Ruckelshaus, 486 F.2d 

427, 438–39 (D.C. Cir. 1973), cert. 

denied, 416 U.S. 969 (1974).226 In Essex 

Chem. Corp., the D.C. Circuit required 

that EPA ‘‘take into account counterproductive environmental effects’’ when 

determining whether a control measure 

qualifies as the BSER, including 

‘‘disposal problems’’ related to the 

control measure’s captured pollutants. 

The Court remanded the NSPS at issue 

because there was no evidence that the 

EPA had considered ‘‘the significant 

land or water pollution potential 


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227 Id. See Portland Cement Ass’n v. Ruckelshaus, 

486 F.2d 375, 385 n.42 (D.C. Cir. 1973) (‘‘The 

standard of the ‘‘best system’’ is comprehensive, 

and we cannot imagine that Congress intended that 

‘best’ could apply to a system which did more 

damage to water than it prevented to air.’’). 

228 985 F.3d 914, 955–41 (D.C. Cir. 2021). 

229 142 S.Ct. at 2610, 2614, 2615–16. 

230 Id. at 2615–16. 

231API Comment Letter on ‘‘Adoption and 

Submittal of State Plans for Designated Facilities; 

Implementing Regulations Under Clean Air Act 

Section 111(d)’’ (‘‘Subpart Ba’’), EPA–HQ–OAR– 

2021–0527–0074 at 8; Lignite Energy Council 

Comment Letter on Subpart Ba, EPA–HQ–OAR– 

2021–0527–0100 at 8–9. 

232Energy Strategy Coalition Comment Letter on 

Subpart Ba, EPA–HQ–OAR–2021–0527–0088 at 6 

(noting that West Virginia distinguished the trading 

program in the Clean Air Mercury Rule, which was 

based on technological controls, from the trading 

program in the CPP). 

233The Municipal Solid Waste Landfills EG, 

which is currently being implemented, has its own 

applicability provisions and is subject to subpart B. 

resulting from disposal of the [scrubber 

system’s] liquid purge byproduct.’’ 227

That the ACE Rule’s interpretation that 

CAA section 111 limits the BSER to atthe-source measures may be 

inconsistent with the EPA’s prior 

determinations that traditional control 

measures like clean fuels and add-on 

controls qualified as the BSER provides 

another reason to reject that 

interpretation. 

It should be noted that many of the 

reasons noted above are comparable to 

the reasoning by the D.C. Circuit to 

support its decision in ALA that the 

ACE Rule was incorrect in interpreting 

CAA section 111 to restrict the BSER to 

at-the-source measures.228 The EPA 

agrees with the D.C. Circuit’s reasoning. 

In West Virginia, the Supreme Court 

held that the CPP’s generation-shifting 

BSER violated the major question 

doctrine, and the Court vacated ALA on 

the basis of that holding.229 However, 

the Court declined to address the ACE 

Rule’s interpretation of CAA section 

111.230 Thus, its opinion does not cast 

doubt on the EPA’s reasons for rejecting 

the ACE Rule’s interpretation, as noted 

above and in ALA. Several commenters 

argued that West Virginia indicates that 

control measures that the commenters 

considered comparable to the 

generation-shifting BSER of the CPP, 

including trading programs and other 

measures that controlled designated 

facilities in the aggregate, were also 

precluded from inclusion as the BSER 

under the major question doctrine.231

Other commenters disagreed, arguing 

that West Virginia identifies distinctions 

among those programs, so that the major 

question doctrine would not necessarily 

apply.232 However, as noted in the 

proposal, in this action, the EPA is not 

addressing what types of controls, in 

addition to the generation-shifting BSER 

of the CPP, would be precluded under 

CAA section 111 by the major question 

doctrine. Instead, the EPA will evaluate 

particular controls against the doctrine, 

as appropriate, when the EPA considers 

those controls in future rulemakings 

under CAA section 111. 

2. Minor Amendments or Clarifications 

The EPA proposed to amend the 

regulatory text in subpart Ba to address 

several editorial and other minor 

clarifications and is finalizing the 

amendments as described below. Except 

as noted specifically below, commenters 

supported these revisions to the 

regulatory text. 

a. The EPA is finalizing amendments 

to the applicability provision for subpart 

Ba under 40 CFR 60.20a, with slight 

revision from as proposed. As discussed 

in section II.B. of this preamble, the 

revised applicability provision clarifies 

that the provisions of subpart Ba are 

applicable to an EG published after July 

8, 2019. The EPA is finalizing the 

proposed removal of text that included 

‘‘if implementation of such final 

guideline is ongoing’’ because there are 

no EGs the implementation of which is 

ongoing; 233 thus, leaving this language 

in the regulation would be needlessly 

confusing. Emission guidelines issued 

on and prior to July 8, 2019, and 

pursuant to CAA section 129 are subject 

to the provisions of subpart B. Also, in 

response to comment that the term 

‘‘final emission guideline’’ is unclear, 

the EPA is adding the term ‘‘in the 

Federal Register’’ to 40 CFR 60.20a(a) to 

clarify the publication in the Federal 

Register determines the applicability 

date. Further clarification of the term 

‘‘final emission guideline’’ is available 

in 40 CFR 60.22a(a). A commenter also 

noted that the proposed rule text 

deleted all references to ‘‘subpart C of 

this part’’ and removing this language 

means that it would apply to all EGs in 

40 CFR part 60 (that are published after 

July 8, 2019), including those for 

incinerators addressed by CAA section 

129. This was not the EPA’s intent. 

Therefore, as noted in section III.G.2.b. 

of this preamble, the EPA is amending 

the definition of EG within subpart Ba 

to clarify that subpart Ba does not apply 

to EGs promulgated under CAA section 

129. 

b. The EPA is finalizing revisions to 

40 CFR 60.21a(e), 60.22a(c), and 

60.24a(c) and (f)(1) and (2), largely as 

proposed, at 40 CFR 60.21a(e), 

60.22a(c), and 60.24a(c) and (i)(1) and 

(2) respectively (differences in 

numbering are due to provisions 

changing location in the final 

regulations relative to proposal). These 

revisions delete ‘‘subpart C’’ from these 

provisions because EGs can be codified 

in other subparts of this part and not 

only in subpart C of this part. In 

response to a comment requesting 

clarification, 40 CFR 60.21a(e) is also 

amended clarify that the definition of 

emission guidelines for purposes of 

subpart Ba excludes guidelines 

promulgated pursuant to CAA section 

129. As discussed above, EGs under 

CAA section 129 are subject to the 

provisions of subpart B. 

c. The EPA is finalizing as proposed 

an editorial amendment to 40 CFR part 

60, subpart A, at § 60.1(a) to add a 

reference to subpart Ba. The 

applicability provision in 40 CFR 

60.1(a) states that ‘‘[e]xcept as provided 

in subparts B and C, the provisions of 

this part apply to the owner or operator 

of any stationary source which contains 

an affected facility, the construction or 

modification of which is commenced 

after the date of publication in this part 

of any standard (or, if earlier, the date 

of publication of any proposed 

standard) applicable to that facility.’’ 

We are amending this provision to 

include reference to subpart Ba in 

addition to subparts B and C. 

d. A minor editorial correction at 40 

CFR 60.22a(b)(3) amends the term 

‘‘nonair quality health environmental 

effects’’ to ‘‘nonair quality health and 

environmental effects’’. 

3. Submission of Emissions Data and 

Related Information 

The EPA is finalizing as proposed 

amendments to 40 CFR 60.25a(a) that 

delete reference to 40 CFR part 60, 

appendix D, because the system 

specified for information submittal by 

the appendix is no longer in use and 

clarify that the applicable EG will 

specify the system for submission of the 

inventory of designated facilities, 

including emission data for the 

designated pollutants and any 

additional required information related 

to emissions. The EPA also proposed to 

delete the term ‘‘related to emissions’’ in 

40 CFR 60.25a(a). A commenter noted as 

proposed this deletion caused the 

provision to be too vague. The EPA 

agrees that the term ‘‘related to 

emissions’’ should be retained to 

maintain the original and proper context 

of this provision. The term is retained 

by this final action. 

4. State Permit and Enforcement 

Authority 

Questions have previously arisen as to 

whether states may establish standards 

of performance and other plan 

requirements as part of state permits 


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234Am. Lung Ass’n v. EPA, 985 F.3d 914, 991 

(D.C. Cir. 2021). 

and administrative orders. The EPA is 

confirming with this final action that 

subpart Ba allows for standards of 

performance and other state plan 

requirements to be established as part of 

state permits and administrative orders, 

which then must be incorporated into 

the state plan. See 40 CFR 

60.27a(g)(2)(ii). 

However, the EPA notes that the 

permit or administrative order alone 

may not be sufficient to meet the 

requirements of an EG or the 

implementing regulations, including the 

completeness criteria under 40 CFR 

60.27a(g). For instance, a plan submittal 

must include supporting material 

demonstrating the state’s legal authority 

to implement and enforce each 

component of its plan, including the 

standards of performance, 40 CFR 

60.27a(g)(2)(iii), as well as a 

demonstration that each emission 

standard is quantifiable, nonduplicative, permanent, verifiable, and 

enforceable. Id. at § 60.27a(a)(2)(vi). In 

addition, the specific EGs may also 

require demonstrations that may not be 

satisfied by terms of a permit or 

administrative order. To the extent that 

these and other requirements are not 

met by the terms of the incorporated 

permits and administrative orders, 

states will need to include materials in 

a state plan submission demonstrating 

how the plan meets those requirements. 

If a state does choose to use permits or 

administrative orders to establish 

standards of performance, it needs to 

demonstrate that it has the legal 

authority to do so. These implementing 

regulations do not themselves provide 

any independent or additional authority 

to issue permits and administrative 

orders under states’ EPA approved title 

I and title V permitting programs. 

IV. Summary of Cost, Environmental, 

and Economic Impacts 

In amending general implementing 

regulations, this final action does not 

independently impose any requirements 

and therefore does not directly incur 

any costs or benefits. However, the 

amendments finalized in this action can 

impact the costs and benefits of future 

EGs subject to subpart Ba. The potential 

impacts of these amendments as 

reflected in an EG will vary greatly 

depending on the source category, 

number and location of designated 

facilities, and the designated pollutant 

and potential controls addressed by the 

EG. Of note, the EPA may propose to 

supersede these general provisions in an 

EG as needed and with appropriate 

justification. Individual EGs are subject 

to notice and comment rulemaking, 

providing the opportunity for 

stakeholders, including the public, to 

consider the impacts of implementing or 

superseding these general implementing 

regulations in the course of those 

rulemaking actions. 

As described in detail in section III.A. 

of this preamble, the EPA is finalizing 

amendments to subpart Ba to replace 

timelines vacated by the D.C. Circuit in 

ALA 234 and to improve and update 

other provisions within subpart Ba. This 

section considers general impacts that 

could result from the amendments 

finalized in this action as adopted by an 

EG. 

As discussed in section III.A. of this 

preamble, the EPA does not interpret 

the D.C. Circuit’s direction to require 

the Agency to quantitatively evaluate 

the impacts of potential subpart Ba 

framework timelines, but rather to 

consider the balance between the public 

health and welfare benefits resulting 

from appropriate and reasonable 

deadlines for the implementation of EGs 

and the time needed for the technical, 

administrative, and legislative actions 

needed to develop and adopt 

approvable state or Federal plans. The 

EPA expects that the amendments to 

subpart Ba finalized in this action will 

improve the implementation of EGs 

under CAA section 111(d). In particular, 

the EPA expects that the timelines 

finalized both appropriately 

accommodate state and EPA processes 

to develop and evaluate plans to 

effectuate an EG and are consistent with 

the objective of CAA section 111(d) to 

ensure that designated facilities 

expeditiously control emissions of 

pollutants that the EPA has determined 

may be reasonably anticipated to 

endanger public health or welfare. 

While the EPA initially proposed a 

15-month deadline for state plan 

submissions following the promulgation 

of an EG (87 FR 79176, Dec. 23, 2022), 

most commenters, including states and 

state organizations, indicated that 15 

months could not accommodate the 

technical, administrative, and legal 

steps necessary to develop and adopt an 

approvable state plan. Based on the 

comments and additional information 

received, the EPA is finalizing 18 

months for state plan submissions after 

promulgation of a final EG, and finds 

that the additional time, compared with 

the 9 months provided in subpart B, 

will better accommodate states’ 

processes to develop and adopt 

approvable plans and will most 

efficiently effectuate the applicable EG. 

Under an 18-month state plan 

submission timeframe, the costs of 

developing a state plan under an 

applicable EG subject to subpart Ba, 

compared with the 9 months provided 

by subpart B, may be spread over 9 

additional months. With this state plan 

submittal timeline, the EPA is providing 

states sufficient time to develop 

approvable implementation plans for 

their designated facilities that 

adequately address public health and 

environmental objectives. A timeline 

that is insufficient for states to conduct, 

inter alia, the appropriate technical 

analysis and public engagement may 

preclude them from timely adopting and 

submitting approvable state plans, 

which could ultimately delay the 

implementation of emission reductions. 

In addition, a successful submittal of 

approvable state plans will avoid an 

attendant expenditure of Federal 

resources associated with the 

development of a Federal plan. 

After receiving a state plan, the EPA 

first must determine if the plan is 

complete. The EPA is finalizing 

amendments to its determination of 

completeness so the timeframe for such 

determination is streamlined from six 

months to 60 days from receipt of the 

state plan submission (see section 

III.A.2. of this preamble). If the EPA 

determines a state plan submission is 

complete, it then evaluates the plan to 

determine whether it satisfies the 

applicable requirements. The Agency 

proposes an action (e.g., plan approval 

or plan disapproval) and then finalizes 

its action pursuant to a notice-andcomment rulemaking process. As 

described in detail in sections III.A.3. 

and III.A.4. of this preamble, the EPA is 

finalizing a 12-month period for the 

EPA to take final action on a state plan 

after a submission is found to be 

complete. The EPA is also finalizing a 

12-month timeline for the EPA to 

promulgate a Federal plan, which runs 

from either the state plan deadline if a 

state has failed to submit a state plan, 

60 days following the state plan 

deadline if a state has submitted a plan 

by the deadline and the EPA determines 

it is incomplete, or from the date the 

EPA finalizes disapproval of a state plan 

submission. As described in detail in 

section III. of this preamble, because 

these timeframes provide for the 

minimum time reasonably necessary for 

the EPA to accomplish propose and 

finalize a Federal plan, the EPA expects 

these timeframes will minimize the 

impacts on public health and welfare to 

the extent possible while ensuring that 

an EG is expeditiously implemented. 

As described in detail in section 

III.A.5. of this preamble, the EPA is 

finalizing a requirement that state plans 

include IoPs if the plan requires final 


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compliance with standards of 

performance later than 20 months after 

the plan submission deadline. The 

compliance schedule, as defined in 

subpart Ba (40 CFR 60.21a(g)) is a 

legally enforceable schedule specifying 

a date or dates by which a source or 

category of sources must comply with 

specific standards of performance 

contained in a plan. If final compliance 

for a source to meet their standards of 

performance is more than 20 months 

after the state plan submittal deadline, 

the plan must include IoPs, which are 

defined steps to achieve compliance 

(e.g., submittal of a control plan, 

awarding of contracts for emission 

control systems or process modification, 

etc.). This 20 month timeline is the 

trigger for when IoPs must be included 

in a state plan. An EG will specify what 

the IoPs are and associated compliance 

schedules. The EPA considers this 

slightly longer timeline than is required 

under subpart B reasonable given that 

the EPA is also, in this action, extending 

the timelines for state plan submission 

under subpart Ba. The EPA notes that 

IoPs do not, on their own, govern how 

expeditiously emission reductions are 

achieved: this is dictated by the final 

compliance date, which is established 

in an individual EG. Additionally, any 

specific requirements associated with 

IoPs, including extended or truncated 

timelines, would be included in the EG, 

as these are dependent on the source 

type, pollutant, and control strategy 

addressed. 

The EPA is also finalizing amending 

subpart Ba to enhance requirements for 

reasonable notice and opportunity for 

public participation. In particular, the 

EPA is requiring that states, as part of 

the state plan development or revision 

process, provide documentation that 

they have conducted meaningful 

engagement with a broad range of 

pertinent stakeholders and/or their 

representatives. Pertinent stakeholders 

include communities most affected by 

and vulnerable to the impacts of the 

plan or plan revision (see section III.C. 

of this preamble). 

Overall, the EPA expects the 

amendments being finalized in this 

action will benefit the states in the 

development of approvable state plans. 

The EPA expects that the amendments 

associated with meaningful engagement 

with pertinent stakeholders will 

potentially increase the amount of 

information the states can use in 

designing state plans, which may 

increase both the level of resources 

states will need to employ in the 

development of an approvable plan, as 

well as the resulting health and welfare 

benefits of the plan. In addition to 

health and welfare benefits, there are 

also administrative benefits of engaging 

with stakeholders and receiving 

pertinent information as a state plan is 

being developed. Such engagement may 

improve the record for the state’s plan 

and reduce the amount of comments 

received when the state plan is 

proposed to the public, which would 

reduce the amount of effort employed 

after proposal to address issues raised 

by the public and stakeholders. 

There is variation and uncertainty in 

determining the magnitude of impacts, 

both to states and the public, resulting 

from amendments associated with 

meaningful engagement. First, the EPA 

notes that the meaningful engagement 

provisions being finalized in this action 

are largely procedural in nature and do 

not prescribe any particular set of 

actions or activities that states must 

undertake. The potential costs and 

benefits will therefore be determined in 

significant part by choices that are 

within states’ discretion. Second, the 

impacts of conducting meaningful 

engagement will be highly dependent 

on the number and location of 

designated facilities addressed by an 

EG, as well as on the type of health or 

environmental impacts of the associated 

emissions. If stakeholder and public 

involvement pursuant to the meaningful 

engagement provisions does not 

generate a large number of specific and 

unique comments, data, or other 

considerations, then the level of effort 

states will employ to review them will 

be lower in comparison to when 

meaningful engagement comments are 

voluminous. It might also be expected 

that less input and fewer comments 

might, in certain cases, have an adverse 

impact on the ability of a state plan to 

fulfill its health and welfare objectives. 

To the extent that states already 

conduct significant engagement with 

pertinent stakeholders, the meaningful 

engagement amendments will most 

likely not result in additional costs. 

Conversely, states that do not have 

engagement procedures already in place 

may be required to increase their level 

of effort to engage with pertinent 

stakeholders. The burden and benefits 

of meaningful engagement for the 

pertinent stakeholders will also be 

highly dependent on the EG and 

associated variables such as, but not 

limited to, the geographical distribution 

of the facilities and communities 

impacted, available modes of 

participation for those areas, the 

pollutants addressed, and the range of 

options available to the state and 

facilities for meeting the EG standards. 

The burden and benefits to pertinent 

stakeholders may be difficult to 

quantify, but overall their engagement 

will be voluntary and is anticipated to 

result in feedback that may improve the 

resulting health and welfare benefits of 

the state plan as perceived and 

experienced, particularly by those in 

communities most affected by and 

vulnerable to the impacts of the plan. 

The EPA is also finalizing revisions to 

the RULOF provisions in subpart Ba. 

The amendments included in this final 

action are intended to provide clarity for 

states to ensure that less-stringent 

standards of performance for particular 

designated facilities are consistent with 

the statutory requirements, as well as a 

consistent framework for EPA to 

evaluate such standards across EGs and 

states (see section III.E. of this 

preamble). 

The magnitude of impacts, both to 

states and the public, resulting from the 

final RULOF amendments will vary 

depending on the particular EG to 

which the final provisions would apply. 

As explained in section III.E.2. of this 

preamble, the EPA believes Congress 

intended RULOF as a mechanism for 

states to apply a less-stringent standard 

of performance in the unusual 

circumstances in which the degree of 

emission limitation determined by the 

EPA is not reasonable for a particular 

designated facility. Additionally, states 

are not required to invoke the RULOF 

provision in any particular instance and 

may choose not to do so, even if a 

particular designated facility’s 

circumstances meet the threshold 

specified in the regulations. If a state 

does not invoke RULOF in their state 

plan, then the amendments will not 

result in any additional costs. If a state 

does invoke RULOF in their state plan, 

then the amendments could, in certain 

circumstances, result in an increased 

level of effort to develop standards of 

performance for certain sources. As 

such, the RULOF amendments could 

potentially increase the level of 

resources states will need to employ in 

the development of an approvable plan. 

However, because the amendments 

clarify is required in order for a lessstringent standard pursuant to RULOF 

to satisfy the statutory requirements, the 

amendments reduce the uncertainty of 

states and designated facilities in the 

development of such standards. This in 

turn could result in a decrease in the 

amount of time that a state that wished 

to invoke RULOF would need, relative 

to a situation where the requirements 

were less defined, by avoiding 

significant back and forth with the EPA 

and the sources in the state during state 

plan development. Overall, the EPA 

expects the RULOF amendments will 

benefit the states in the development of 


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approvable state plans and therefore 

result in benefits to public health and 

welfare. 

Finally, the EPA expects that the 

requirements for electronic submittal 

and that the availability of the optional 

regulatory mechanisms being finalized 

in this action will improve flexibility 

and efficiency in the call for and 

submission, review, approval, and 

implementation of state plans, and thus 

will overall result in benefits to the 

states, the EPA, designated facilities, 

and public health and welfare. In 

addition, the EPA expects the 

requirements for electronic submittal 

will increase the ease and efficiency of 

data submittal and data accessibility 

and benefit the states and the EPA. 

Electronic submittal will also improve 

the Agency’s efficiency and 

effectiveness in the receipt and review 

of state plans. 

The EPA expects that the overall 

impacts of the implementation of the 

amendments to subpart Ba finalized in 

this action will improve the 

implementation of EGs under CAA 

section 111(d). 

V. Statutory and Executive Order 

Reviews 

Additional information about these 

Statutory and Executive orders can be 

found at https://www.epa.gov/lawsregulations/laws-and-executive-orders. 

A. Executive Order 12866: Regulatory 

Planning and Review; Executive Order 

13563: Improving Regulation and 

Regulatory Review; and Executive Order 

14094: Modernizing Regulatory Review 

This action is a ‘‘significant regulatory 

action’’ as defined in Executive Order 

12866, as amended by Executive Order 

14094. Accordingly, the EPA submitted 

this action to the Office of Management 

and Budget (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. Paperwork Reduction Act (PRA) 

This action does not impose an 

information collection burden under the 

Paperwork Reduction Act. The 

requirements in subpart Ba do not 

themselves require any reporting and 

recordkeeping activities, and no 

Information Collection Request (ICR) 

was submitted in connection with the 

original promulgation of subpart Ba or 

the amendments we are finalizing at this 

time. Any recordkeeping and reporting 

requirements are imposed only through 

the incorporation of specific elements of 

subpart Ba in the individual emission 

guidelines, which have their own ICRs. 

C. Regulatory Flexibility Act (RFA) 

I certify that this action will not have 

a significant economic impact on a 

substantial number of small entities. 

This final rule will not impose any 

requirements on small entities. 

Specifically, this action addresses 

processes related to state plans for 

implementation of EGs established 

under CAA section 111(d). 

D. Unfunded Mandates Reform Act 

(UMRA) 

This action does not contain an 

unfunded mandate of $100 million or 

more as described in UMRA, 2 U.S.C. 

1531–1538, and does not significantly or 

uniquely affect small governments. This 

final action does not contain a Federal 

mandate that may result in expenditures 

of $100 million or more for state, local, 

and Tribal governments, in the aggregate 

or the private sector in any 1 year. 

This final action is also not subject to 

the requirements of section 203 of 

UMRA because, as described in 2 U.S.C. 

1531–38, it contains no regulatory 

requirements that might significantly or 

uniquely affect small governments. This 

action imposes no enforceable duty on 

any local, or Tribal governments or the 

private sector. However, this action 

imposes enforceable duties on states. 

This action does not meaningfully 

require additional mandates on states 

beyond what is already required of them 

and will not impose a burden in excess 

of $100 million. 

E. Executive Order 13132: Federalism 

This action does not have federalism 

implications. It will not have substantial 

direct effects on the states, on the 

relationship between the National 

Government and the states, or on the 

distribution of power and 

responsibilities among the various 

levels of government. The EPA believes, 

however, that this action may be of 

significant interest to state governments. 

Subpart Ba requirements apply to 

states in the development and submittal 

of state plans pursuant to emission 

guidelines promulgated under CAA 

section 111(d) after July 8, 2019, to the 

extent that an EG does not supersede the 

requirements of subpart Ba. This action 

finalizes amendments to certain 

requirements for development, 

submission, and approval processes of 

state plans under CAA section 111(d). In 

particular, the amendments associated 

with state plan submission deadlines, 

RULOF provisions, meaningful 

engagement, and regulatory mechanisms 

may be of significant interest to state 

governments. In section IV of this 

preamble, the EPA summarizes the 

potential cost, environmental, and 

economic impacts of the 

implementation (through individual 

emission guidelines) of the amendments 

to subpart Ba being finalized in this 

action. Overall, the EPA expects these 

amendments will benefit the states in 

the development of approvable state 

plans. 

The EPA notes that notice and 

comment procedures required for the 

promulgation of individual EGs will 

provide opportunity for states to address 

issues related to federalism based on 

specific application of subpart Ba 

requirements to that particular EG. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

This action does not have Tribal 

implications as specified in Executive 

Order 13175. It would not impose 

substantial direct compliance costs on 

Tribal governments that have designated 

facilities located in their area of Indian 

country. Tribes are not required to 

develop plans to implement the 

guidelines under CAA section 111(d) for 

designated facilities. A tribe with an 

approved TAS under TAR for CAA 

111(d) is not required to resubmit TAS 

approval to implement an EG subject to 

subpart Ba. This action also will not 

have substantial direct costs or impacts 

on the relationship between the Federal 

Government and Indian tribes or on the 

distribution of power and 

responsibilities between the Federal 

Government and Indian tribes, as 

specified in Executive Order 13175. 

Thus, Executive Order 13175 does not 

apply to the action. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

The EPA interprets Executive Order 

13045 as applying only to those 

regulatory actions that concern 

environmental health or safety risks that 

the EPA has reason to believe may 

disproportionately affect children, per 

the definition of ‘‘covered regulatory 

action’’ in section 2–202 of the 

Executive order. This action is not 

subject to Executive Order 13045 

because it does not concern an 

environmental health risk or safety risk. 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This action is not a ‘‘significant 

energy action’’ because it will not have 

a significant adverse effect on the 

supply, distribution or use of energy. 

Specifically, this action addresses the 


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submission and adoption of state plans 

for implementation of EGs established 

under CAA section 111(d). 

I. National Technology Transfer and 

Advancement Act (NTTAA) 

This rulemaking does not involve 

technical standards. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

Executive Order 12898 (59 FR 7629, 

February 16, 1994) directs Federal 

agencies, to the greatest extent 

practicable and permitted by law, to 

make environmental justice part of their 

mission by identifying and addressing, 

as appropriate, disproportionately high 

and adverse human health or 

environmental effects of their programs, 

policies, and activities on minority 

populations (people of color and/or 

indigenous peoples) and low-income 

populations. 

The EPA believes that it is not 

practicable to assess whether the human 

health or environmental conditions that 

exist prior to this action result in 

disproportionate and adverse effects on 

people of color, low-income populations 

and/or indigenous peoples. The 40 CFR 

part 60, subpart Ba, provisions are the 

implementing regulations for states to 

plan in response to individual EGs, and 

these individual EGs are applicable to 

specific pollutants from specified 

categories of existing sources. It is not 

possible to identify or assess human 

health and environmental conditions 

that will be impacted by this rule 

because this rule does not address a 

particular set of sources or a particular 

pollutant. This action is revising the 

implementing regulations and does not 

directly impact environmental justice 

communities or result in new 

disproportionate and adverse effects. 

The EPA identified and addressed 

environmental justice concerns by 

specifying new requirements for 

meaningful engagement with pertinent 

stakeholders, which includes 

communities most affected by and/or 

vulnerable to the impacts of a state plan. 

The information supporting this 

Executive order review is contained in 

section III.C. and section III.E.3.f. of this 

action. 

K. Congressional Review Act (CRA) 

This action is subject to the CRA, and 

the EPA will submit a rule report to 

each House of the Congress and to the 

Comptroller General of the United 

States. This action is not a ‘‘major rule’’ 

as defined by 5 U.S.C. 804(2). 

List of Subjects in 40 CFR Part 60 

Environmental protection, 

Administrative practice and procedures, 

Air pollution control, Intergovernmental 

relations, Reporting and recordkeeping 

requirements. 

Michael S. Regan, 

Administrator. 

For the reasons set out in the 

preamble, title 40, chapter I of the Code 

of Federal Regulations is amended as 

follows: 

PART 60—STANDARDS OF 

PERFORMANCE FOR NEW 

STATIONARY SOURCES 

■ 1. The authority citation for part 60 

continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

■ 2. Amend § 60.1 by revising paragraph 

(a) to read as follows: 

§ 60.1 Applicability. 

(a) Except as provided in subparts B, 

Ba, and C of this part, the provisions of 

this part apply to the owner or operator 

of any stationary source which contains 

an affected facility, the construction or 

modification of which is commenced 

after the date of publication in this part 

of any standard (or, if earlier, the date 

of publication of any proposed 

standard) applicable to that facility. 

* * * * * 

■ 3. Amend § 60.20a by revising 

paragraph (a) introductory text to read 

as follows: 

§ 60.20a Applicability. 

(a) The provisions of this subpart 

apply upon publication of a final 

emission guideline under § 60.22a(a) if 

the guideline is published in the 

Federal Register after July 8, 2019. 

* * * * * 

■ 4. Amend § 60.21a by: 

■ a. Revising paragraphs (e) and (f); and 

■ b. Adding paragraphs (k) and (l). 

The revisions and additions read as 

follows: 

§ 60.21a Definitions. 

* * * * * 

(e) Emission guideline means a 

guideline set forth in this part, with the 

exception of guidelines set forth 

pursuant to section 129 of the Clean Air 

Act, or in a final guideline document 

published under § 60.22a(a), which 

reflects the degree of emission 

limitation achievable through the 

application of the best system of 

emission reduction which (taking into 

account the cost of achieving such 

reduction and any non-air quality health 

and environmental impact and energy 

requirements) the Administrator has 

determined has been adequately 

demonstrated for designated facilities. 

(f) Standard of performance means a 

standard for emissions of air pollutants 

which reflects the degree of emission 

limitation achievable through the 

application of the best system of 

emission reduction which (taking into 

account the cost of achieving such 

reduction and any nonair quality health 

and environmental impact and energy 

requirements) the Administrator 

determines has been adequately 

demonstrated, including a legally 

enforceable regulation setting forth an 

allowable rate, quantity, or 

concentration of emissions into the 

atmosphere, or prescribing a design, 

equipment, work practice, or 

operational standard, or combination 

thereof. 

* * * * * 

(k) Meaningful engagement means the 

timely engagement with pertinent 

stakeholders and/or their 

representatives in the plan development 

or plan revision process. Such 

engagement should not be 

disproportionate in favor of certain 

stakeholders and should be informed by 

available best practices. 

(l) Pertinent stakeholders include, but 

are not limited to, industry, small 

businesses, and communities most 

affected by and/or vulnerable to the 

impacts of the plan or plan revision. 

■ 5. Amend § 60.22a by revising 

paragraphs (b)(3) and (c) to read as 

follows: 

§ 60.22a Publication of emission 

guidelines. 

* * * * * 

(b) * * * 

(3) Information on the degree of 

emission limitation which is achievable 

with each system, together with 

information on the costs, nonair quality 

health and environmental effects, and 

energy requirements of applying each 

system to designated facilities. 

* * * * * 

(c) The emission guidelines and 

compliance times referred to in 

paragraph (b)(5) of this section will be 

proposed for comment upon publication 

of the draft guideline document, and 

after consideration of comments will be 

promulgated in this part with such 

modifications as may be appropriate. 

■ 6. Amend § 60.23a by: 

■ a. Revising paragraph (a)(1); 

■ b. Adding paragraph (a)(3); 

■ c. Revising paragraph (b); and 

■ d. Adding paragraph (i). 

The revisions and additions read as 

follows: 


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§ 60.23a Adoption and submittal of State 

plans; public hearings. 

(a)(1) Unless otherwise specified in 

the applicable subpart in this part, 

within eighteen months after 

publication in the Federal Register of a 

final emission guideline under 

§ 60.22a(a), each State shall adopt and 

submit to the Administrator a plan for 

the control of the designated pollutant 

to which the emission guideline applies. 

The submission of such plan shall be 

made in electronic format according to 

paragraph (a)(3) of this section or as 

specified in an applicable emission 

guideline. 

* * * * * 

(3) States must submit to the 

Administrator any plan or plan revision 

using the State Planning Electronic 

Collaboration System (SPeCS), which 

can be accessed through the EPA’s 

Central Data Exchange (CDX) (https://

cdx.epa.gov/) or through an analogous 

electronic reporting tool provided by the 

EPA for the submission of any plan 

required by this subpart. Do not use 

SPeCS to submit confidential business 

information (CBI). Anything submitted 

using SPeCS cannot later be claimed to 

be CBI. The State must confer with the 

Regional Office for the procedures to 

submit CBI information. All CBI must be 

clearly marked as CBI. 

(b) If no designated facility is located 

within a State, the State shall submit a 

letter of certification to that effect to the 

Administrator within the time specified 

in paragraph (a) of this section. Such 

certification shall exempt the State from 

the requirements of this subpart for that 

designated pollutant. The State must 

submit the letter using the SPeCS, or 

through an analogous electronic 

reporting tool provided by the EPA for 

the submission of any plan required by 

this subpart. 

* * * * * 

(i) The State must submit, with the 

plan or revision, documentation of 

meaningful engagement including a list 

of identified pertinent stakeholders and/ 

or their representatives, a summary of 

the engagement conducted, a summary 

of stakeholder input received, and a 

description of how stakeholder input 

was considered in the development of 

the plan or plan revisions. 

■ 7. Amend § 60.24a by: 

■ a. Revising paragraphs (b) 

introductory text, (c), (d), (e), and (f); 

and 

■ b. Adding paragraphs (g), (h), and (i). 

The revisions and additions read as 

follows: 

§ 60.24a Standards of performance and 

compliance schedules. 

* * * * * 

(b) Standards of performance shall be 

in the form of an allowable rate, 

quantity, or concentration of emissions, 

except when it is not feasible to 

prescribe or enforce such a standard of 

performance. The EPA shall identify 

such cases in the emission guidelines 

issued under § 60.22a. Where standards 

of performance prescribing design, 

equipment, work practice, or 

operational standards, or combination 

thereof are established, the plan shall, to 

the degree possible, set forth the 

emission reductions achievable by 

implementation of such standards, and 

may permit compliance by the use of 

equipment determined by the State to be 

equivalent to that prescribed. 

* * * * * 

(c) Except as provided in paragraph 

(e) of this section, standards of 

performance shall be no less stringent 

than the corresponding emission 

guideline(s) specified in this part, and 

final compliance shall be required as 

expeditiously as practicable, but no later 

than the compliance times specified in 

an applicable subpart of this part. 

(d) Any compliance schedule 

extending more than twenty months 

from the date required for submittal of 

the plan must include legally 

enforceable increments of progress to 

achieve compliance for each designated 

facility or category of facilities. Unless 

otherwise specified in the applicable 

emission guideline, increments of 

progress must include, where 

practicable, each increment of progress 

specified in § 60.21a(h) and must 

include such additional increments of 

progress as may be necessary to permit 

close and effective supervision of 

progress toward final compliance. 

(e)(1) The State may apply a standard 

of performance to a particular 

designated facility that is less stringent 

than or has a compliance schedule 

longer than otherwise required by an 

applicable emission guideline taking 

into consideration that facility’s 

remaining useful life and other factors, 

provided that the State demonstrates 

with respect to each such facility (or 

class of such facilities) that the facility 

cannot reasonably achieve the degree of 

emission limitation determined by the 

EPA based on: 

(i) Unreasonable cost of control 

resulting from plant age, location, or 

basic process design; 

(ii) Physical impossibility or technical 

infeasibility of installing necessary 

control equipment; or 

(iii) Other circumstances specific to 

the facility. 

(2) For the purpose of this paragraph 

(e), the State must demonstrate that 

there are fundamental differences 

between the information specific to a 

facility (or class of such facilities) and 

the information EPA considered in 

determining the degree of emission 

limitation achievable through 

application of the best system of 

emission reduction or the compliance 

schedule that make achieving such 

degree of emission limitation or meeting 

such compliance schedule unreasonable 

for that facility. 

(f) If the State makes the required 

demonstration in paragraph (e) of this 

section, the plan may apply a standard 

of performance that is less stringent 

than required by an applicable emission 

guideline. 

(1) The standard of performance 

applied under this paragraph (f) must be 

no less stringent (or have a compliance 

schedule no longer) than is necessary to 

address the fundamental differences 

identified under paragraph (e) of this 

section. To the extent necessary to 

determine a standard of performance 

satisfying that criteria, the State must 

evaluate the systems of emission 

reduction identified in the applicable 

emission guideline using the factors and 

evaluation metrics EPA considered in 

assessing those systems, including 

technical feasibility, the amount of 

emission reductions, the cost of 

achieving such reductions, any nonair 

quality health and environmental 

impacts, and energy requirements. The 

States may also consider, as justified, 

other factors specific to the facility that 

were the basis of the demonstration 

under paragraph (e) as well as other 

systems of emission reduction in 

addition to those EPA considered in the 

applicable emission guideline. 

(2) A standard of performance under 

this paragraph (f) must be in the form as 

required by the applicable emission 

guideline. 

(g) Where a State applies a standard 

of performance pursuant to paragraph (f) 

of this section on the basis of an 

operating condition(s) within the 

designated facility’s control, such as 

remaining useful life or restricted 

capacity, the plan must also include 

such operating condition(s) as an 

enforceable requirement. The plan must 

also include requirements to provide for 

the implementation and enforcement of 

the operating condition(s), such as 

requirements for monitoring, reporting, 

and recordkeeping. 

(h) A less stringent standard of 

performance must meet all other 

applicable requirements, including in 

this subpart and in any applicable 

emission guideline. 


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80544 Federal Register / Vol. 88, No. 221 / Friday, November 17, 2023 / Rules and Regulations 

(i) Nothing in this subpart shall be 

construed to preclude any State or 

political subdivision thereof from 

adopting or enforcing, as part of the 

plan: 

(1) Standards of performance more 

stringent than emission guidelines 

specified in this part; or 

(2) Compliance schedules requiring 

final compliance at earlier times than 

those specified in applicable emission 

guidelines. 

(ii) [Reserved] 

■ 8. Amend § 60.25a by revising 

paragraph (a) to read as follows: 

§ 60.25a Emission inventories, source 

surveillance, reports. 

(a) Each plan shall include an 

inventory of all designated facilities, 

including emission data for the 

designated pollutants and any 

additional information related to 

emissions as specified in the applicable 

emission guideline. Such data shall be 

summarized in the plan, and emission 

rates of designated pollutants from 

designated facilities shall be correlated 

with applicable standards of 

performance. As used in this subpart, 

correlated means presented in such a 

manner as to show the relationship 

between measured or estimated 

amounts of emissions and the amounts 

of such emissions allowable under 

applicable standards of performance. 

* * * * * 

■ 9. Amend § 60.27a by: 

■ a. Revising paragraph (a); 

■ b. Adding paragraphs (b)(1) and (2); 

■ c. Revising paragraphs (c), (d), (f) 

introductory text, and (g)(1); 

■ d. Removing the word ‘‘and’’ from the 

end of paragraph (g)(2)(viii); 

■ e. Redesignating paragraph (g)(2)(ix) 

as paragraph (g)(2)(x); and 

■ f. Adding new paragraph (g)(2)(ix) and 

paragraphs (h), (i) and (j). 

The revisions and additions read as 

follows: 

§ 60.27a Actions by the Administrator. 

(a) The Administrator may, whenever 

he determines necessary, amend the 

period for submission of any plan or 

plan revision or portion thereof. 

(b) * * * 

(1) Full and partial approval and 

disapproval. In the case of any plan or 

plan revision on which the 

Administrator is required to act under 

this paragraph (b), the Administrator 

shall approve such plan or plan revision 

as a whole if it meets all of the 

applicable requirements of this subpart. 

If a portion of the plan or plan revision 

meets all the applicable requirements of 

this subpart, the Administrator may 

approve the plan or plan revision in part 

and disapprove in part. The plan or plan 

revision shall not be treated as meeting 

the requirements of this chapter until 

the Administrator approves the entire 

plan or revision as complying with the 

applicable requirements of this subpart. 

(2) Conditional approval. The 

Administrator may approve a plan or 

plan revision based on a commitment of 

the State to adopt and submit to the 

Administrator specific enforceable 

measures by a date certain, but not later 

than twelve months after the date of 

conditional approval of the plan or plan 

revision. Any such conditional approval 

shall be treated as a disapproval if the 

State fails to comply with such 

commitment. 

(c) The Administrator will 

promulgate, through notice-andcomment rulemaking, a Federal plan, or 

portion thereof, at any time within 

twelve months after: 

(1) The State fails to submit a plan or 

plan revision within the time prescribed 

or the State has failed to satisfy the 

minimum criteria under paragraph (g) of 

this section as of the time prescribed in 

paragraph (g)(1) of this section; or 

(2) The Administrator disapproves the 

required State plan or plan revision or 

any portion thereof, as unsatisfactory 

because the applicable requirements of 

this subpart or an applicable emission 

guideline under this part have not been 

met. 

(d) The Administrator will 

promulgate a final Federal plan, or 

portion thereof, as described in 

paragraph (c) of this section unless the 

State corrects the deficiency, and the 

Administrator approves the plan or plan 

revision, before the Administrator 

promulgates such Federal plan. 

* * * * * 

(f) Prior to promulgation of a Federal 

plan under paragraph (d) of this section, 

the Administrator will conduct 

meaningful engagement with pertinent 

stakeholders and/or their 

representatives and provide the 

opportunity for at least one public 

hearing in either: 

* * * * * 

(g) * * * 

(1) General. Within 60 days of the 

Administrator’s receipt of a State 

submission, the Administrator shall 

determine whether the minimum 

criteria for completeness have been met 

for a plan submission or revision. Any 

plan or plan revision that a State 

submits to the EPA, and that has not 

been determined by the EPA within 60 

days after the Administrator’s receipt of 

a State submission to have failed to 

meet the minimum criteria, shall on that 

date be deemed by operation of law to 

meet such minimum criteria. Where the 

Administrator determines that a plan 

submission does not meet the minimum 

criteria of this paragraph (g), the State 

will be treated as not having made the 

submission and the requirements of this 

section regarding promulgation of a 

Federal plan shall apply. 

(2) * * * 

(ix) Documentation of meaningful 

engagement, including a list of pertinent 

stakeholders or their representatives, a 

summary of the engagement conducted, 

and a summary of stakeholder input 

received, and a description of how 

stakeholder input was considered in the 

development of the plan or plan 

revisions; and 

* * * * * 

(h) The requirements of this 

paragraph (h) apply to parallel 

processing. A State may submit a plan 

requesting parallel processing prior to 

adoption and to completion of public 

outreach and engagement by the State in 

order to expedite review and to provide 

an opportunity for the State to consider 

EPA comments prior to submission of a 

final plan for final review and action. 

Under these circumstances and at the 

discretion of the EPA, the following 

exceptions to the completeness criteria 

under paragraph (g)(2) of this section 

apply to plans submitted explicitly for 

parallel processing: 

(1) The letter required by paragraph 

(g)(2)(i) of this section must request that 

EPA propose approval of the proposed 

plan by parallel processing; 

(2) In lieu of paragraph (g)(2)(ii) of 

this section, the State must submit a 

schedule for final adoption or issuance 

of the plan; 

(3) In lieu of paragraph (g)(2)(iv) of 

this section, the plan must include a 

copy of the proposed/draft regulation or 

document, including indication of the 

proposed changes to be made to the 

existing approved plan, where 

applicable; 

(4) In lieu of paragraph (g)(2)(ix) of 

this section, the plan must include 

documentation of the engagement 

conducted prior to the parallel 

processing submittal and of any planned 

additional meaningful engagement to be 

conducted prior to adoption of the final 

plan; and 

(5) The requirements of paragraphs 

(g)(2)(v) through (viii) of this section do 

not apply to plans submitted for parallel 

processing. The exceptions granted in 

the preceding sentence apply only to 

EPA’s determination of proposed action 

and all requirements of paragraph (g)(2) 

of this section must be met prior to 

publication of EPA’s final determination 

of plan approvability. 


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Federal Register / Vol. 88, No. 221 / Friday, November 17, 2023 / Rules and Regulations 80545 

(i) The requirements of this paragraph 

(i) apply to calls for plan revisions. 

Whenever the Administrator finds that 

the applicable plan is substantially 

inadequate to meet the requirements of 

the applicable emission guidelines in 

this part, to provide for the 

implementation of the applicable 

requirements, or to otherwise comply 

with any applicable requirement of this 

subpart or the Clean Air Act, the 

Administrator shall require the State to 

revise the plan as necessary to correct 

such inadequacies. The Administrator 

must notify the State of the 

inadequacies and such plan revisions 

shall be submitted to the Administrator 

within twelve months or as determined 

by the Administrator. Such findings and 

notice must be public. 

(1) Any finding under this paragraph 

(i) shall, to the extent the Administrator 

deems appropriate, subject the State to 

the requirements of this part to which 

the State was subject when it developed 

and submitted the plan for which such 

finding was made, except that the 

Administrator may adjust any dates 

applicable under such requirements as 

appropriate. 

(2) If the Administrator makes this 

finding on the basis that a State is 

failing to implement an approved plan, 

or part of an approved plan, the State 

may submit a demonstration to the 

Administrator it is adequately 

implementing the requirements of the 

approved State plan in lieu of 

submitting a plan revision. Such 

demonstration must be submitted by the 

deadline established under this 

paragraph (i). 

(j) The requirements of this paragraph 

(j) apply to error corrections. Whenever 

the Administrator determines that the 

Administrator’s action approving, 

disapproving, or promulgating any plan 

or plan revision (or portion thereof) was 

in error, the Administrator may in the 

same manner as the approval, 

disapproval, or promulgation revise 

such action as appropriate without 

requiring any further submission from 

the State. Such determination and the 

basis thereof shall be provided to the 

State and public. 

■ 10. Amend § 60.28a by revising 

paragraph (a) to read as follows: 

§ 60.28a Plan revisions by the State. 

(a) Any significant revision to a State 

plan shall be adopted by such State after 

reasonable notice, public hearing, and 

meaningful engagement. For plan 

revisions required in response to a 

revised emission guideline, such plan 

revisions shall be submitted to the 

Administrator within fifteen months, or 

as determined by the Administrator, 

after publication in the Federal Register 

of a final revised emission guideline 

under § 60.22a. All plan revisions must 

be submitted in accordance with the 

procedures and requirements applicable 

to development and submission of the 

original plan. 

* * * * * 

■ 11. Amend § 60.29a by revising the 

introductory text to read as follows: 

§ 60.29a Plan revisions by the 

Administrator. 

After notice and opportunity for 

public hearing in each affected State, 

and meaningful engagement for any 

significant revision, the Administrator 

may revise any provision of an 

applicable Federal plan if: 

* * * * * 

[FR Doc. 2023–25269 Filed 11–16–23; 8:45 am] 

BILLING CODE 6560–50–P 


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