Document ID: EPA-HQ-OAR-2020-0310-0001
Agency: epa
Document Type: Proposed Rule
Title: Response to Clean Air Act Section 176A Petition From Maine
Posted Date: 2021-05-03T04:00Z

[Federal Register Volume 86, Number 83 (Monday, May 3, 2021)]
[Proposed Rules]
[Pages 23309-23323]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-08825]

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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OAR-2020-0310; FRL-10019-11-OAR]

40 CFR Part 81

Response to Clean Air Act Section 176A Petition From Maine

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of proposed action on petition.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
grant a Clean Air Act (CAA) section 176A petition submitted by the 
state of Maine on February 24, 2020. The petition requests that the EPA 
remove a large portion of Maine from the Ozone Transport Region (OTR) 
based on that area's continued attainment with ozone National Ambient 
Air Quality Standards (NAAQS) and technical analyses demonstrating that 
the additional control of emissions from that portion of the state will 
not significantly contribute to ozone attainment in any area in the 
OTR. The OTR was established by the 1990 Clean Air Act (CAA or Act) 
Amendments and includes the states of Connecticut, Delaware, Maine, 
Maryland, Massachusetts, New Hampshire, New Jersey, New York, 
Pennsylvania, Rhode Island, Vermont, the District of Columbia, and 
portions of northern Virginia.

DATES: Comments. Comments must be received on or before June 17, 2021. 
Public Hearing. A virtual public hearing will be held upon request. To 
request a public hearing, please notify Ms. Pamela Long, U.S. 
Environmental Protection Agency, Office of Air Quality Planning and 
Standards, Air Quality Policy Division, (C504-01), Research Triangle 
Park, NC 27711, telephone (919) 541-0641, fax number (919) 541-5509, 
email address long.pam@epa.gov, no later than May 13, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2020-0310, at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from Regulations.gov. The EPA may publish any 
comment received to its public docket. Do not submit electronically any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e., on the Web, Cloud, or other 
file sharing system). For additional submission methods, the full EPA 
public comment policy, information about CBI or multimedia submissions, 
and general guidance on making effective comments, please visit https://www2.epa.gov/dockets/commenting-epa-dockets.
    Out of an abundance of caution, the EPA Docket Center and Reading 
Room was closed to public visitors on March 31, 2020, to reduce the 
risk of transmitting COVID-19. The EPA Docket Center and Reading Room 
has since started the reopening process. Visitors will be considered on 
an exception basis and allowed entrance by appointment only. Docket 
Center staff will continue to provide remote customer service via 
email, phone, and webform. For further information on EPA Docket Center 
services and the current status, please visit https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: Questions concerning this proposed 
notice should be directed to Holly DeJong, U.S. Environmental 
Protection Agency, Office of Air Quality Planning and Standards, Air 
Quality Policy Division, Mail code C539-01, Research Triangle Park, NC 
27711, telephone (919) 541-4353; email at dejong.holly@epa.gov.
    For more information pertaining to a public hearing on this 
document, contact Pamela Long, U.S. Environmental Protection Agency, 
Office of Air Quality Planning and Standards, Air Quality Policy 
Division, (C504-01), Research Triangle Park, NC 27711; telephone number 
(919) 541-0641; fax number (919) 541-5509; email at long.pam@epa.gov 
(preferred method of contact).

SUPPLEMENTARY INFORMATION:

I. General Information

    Throughout this document wherever ``we,'' ``us,'' or ``our'' is 
used, we mean the U.S. EPA.
    The information in this Supplementary Information section of this 
preamble is organized as follows:

I. General Information
    A. Where can I get a copy of this document and other related 
information?
    B. What acronyms, abbreviations and units are used in this 
preamble?
II. Executive Summary of the EPA's Proposed Decision on the Maine 
CAA Section 176A Petition
III. Background and Legal Authority

[[Page 23310]]

    A. Ozone Formation and Impacts
    B. Sections 176A and 184 of the CAA and the OTR Process
    C. Legal Standard for this Action
    D. Previous Actions
IV. Maine CAA Section 176A Petition
    A. Summary of the Maine CAA Section 176A Petition
    B. Provisions Impacted by the Maine CAA Section 176A Petition
V. The EPA's Technical Assessment of the Maine CAA Section 176A 
Petition
    A. Description of the Technical Analysis Included in the Maine 
CAA Section 176A Petition
    B. The EPA's Technical Assessment of the Maine Section 176A 
Petition
VI. The EPA's Proposed Action on the Maine CAA Section 176A Petition
VII. Judicial Review and Determinations Under Section 307(b)(1) of 
the CAA

A. 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 document will be posted at https://www.epa.gov/ozone-pollution/ozone-national-ambient-air-quality-standards-section-176a-petition-maine.

B. What acronyms, abbreviations and units are used in this preamble?

APA Administrative Procedures Act
BACT Best Available Control Technology
CAA or Act Clean Air Act
CAIR Clean Air Interstate Rule
CSAPR Cross State Air Pollution Rule
CFR Code of Federal Regulations
CMR Code of Maine Regulations
CTG Control Techniques Guideline
D.C. Circuit United States Court of Appeals for the District of 
Columbia Circuit
DEP Department of Environmental Protection
EGU Electric Generating Unit
EPA U.S. Environmental Protection Agency
FIP Federal Implementation Plan
FR Federal Register
HYSPLIT Hybrid Single Particle Lagrangian Integrated Trajectory
I/M program Inspection and Maintenance Program
LAER Lowest Achievable Emission Rate
NAAQS National Ambient Air Quality Standard
NEI National Emissions Inventory
NNSR Nonattainment New Source Review
NOX Nitrogen Oxides
NSPS New Source Performance Standard
NSR New Source Review
ORVR Systems Onboard Refueling Vapor Recovery Systems
OTAG Ozone Transport Assessment Group
OTC Ozone Transport Commissio
OTR Ozone Transport Region
PM Particulate Matter
PTE Potential to Emit
RACT Reasonably Available Control Technology
SIP State Implementation Plan
SO2 Sulfur Dioxide
VOC Volatile Organic Compound

II. Executive Summary of the EPA's Proposed Decision on the Maine CAA 
Section 176A Petition

    On February 24, 2020, the state of Maine petitioned the EPA 
pursuant to Clean Air Act (CAA) section 176A(a)(2) for the removal of 
the state of Maine from the OTR except for 111 towns and cities 
comprising the Androscoggin Valley,\1\ Down East \2\ and Metropolitan 
Portland \3\ Air Quality Control Regions, commonly referred to as the 
``Portland and Midcoast Ozone Areas.'' Maine contends that emissions 
from northern and eastern Maine are not significant contributors to 
ozone nonattainment in other states nor do they interfere with 
maintenance of the ozone NAAQS in those Maine municipalities that would 
remain in the OTR. Therefore, removing these areas from the OTR would 
not degrade the air quality in Maine or in any other state. The 
petition includes monitoring data and technical analyses to support a 
demonstration that the areas requested to be removed from the OTR are 
in attainment with the ozone NAAQS and that emissions from these areas 
do not significantly contribute to ozone nonattainment in any area of 
the OTR. For the reasons described in this notice, the EPA is proposing 
to grant the petition on the basis that removing the areas of the state 
requested to be removed from the OTR would not result in emissions 
changes that would significantly contribute to nonattainment or 
interfere with maintenance in any area of the OTR.
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    \1\ 40 CFR 81.90 defines the Androscoggin Valley Interstate Air 
Quality Control Region as Androscoggin County, Kennebec County, Knox 
County, Lincoln County, Waldo County and parts of Franklin County, 
Oxford County, Somerset County.
    \2\ 40 CFR 81.181 defines the Down East Intrastate Air Quality 
Control Region as Hancock County, Washington County and parts of 
Penobscot County and Piscataquis County.
    \3\ 40 CFR 81.78 defines the Metropolitan Portland Intrastate 
Air Quality Control Region as Cumberland County, Sagadahoc County, 
York County, and the towns of Brownfield, Denmark, Fryburg, Hiram, 
and Porter.
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    Section 176A(a) of the CAA provides the Administrator with the 
authority to develop interstate transport regions for particular 
pollutants where the Administrator determines that interstate transport 
of air pollutants from one or more states contributes significantly to 
violations of air quality standards in other states. In the 1990 CAA 
Amendments, Congress created the OTR by statute under CAA section 
184(a) to address the interstate transport of ozone pollution in the 
Northeast and Mid-Atlantic regions of the United States (U.S.).
    The creation of an interstate transport region requires 
establishing a transport commission with representatives from each 
state who make recommendations to mitigate interstate pollution. Model 
rules and programs designed through the OTC (Ozone Transport 
Commission) may be adopted by the individual states through their own 
rulemaking processes. Under CAA section 184(c), the OTC may petition 
the EPA to approve additional control measures to be applied within all 
or part of the transport region. Maine seeks to remove portions of the 
state from the OTR, thereby releasing those areas from OTC 
recommendations and applicable control requirements established under 
CAA section 184.
    Section 176A(a)(1) of the CAA provides the Administrator with 
authority to ``add any state or portion of a state to any [transport] 
region . . . whenever the Administrator has reason to believe that the 
interstate transport of air pollutants from such state significantly 
contributes to a violation of the standard in the transport region.'' 
Conversely, CAA section 176A(a)(2) allows the Administrator to ``remove 
any state or portion of a state from [a transport] region whenever the 
Administrator has reason to believe that the control of emissions in 
that state or portion of the state . . . will not significantly 
contribute to the attainment of the standard in any area in the 
region.''
    For the reasons fully described in this notice, and in 
consideration of monitoring data, technical demonstrations, and impacts 
to air quality control regimes in the areas to be removed, the EPA 
believes that the portion of Maine requested for removal from the OTR 
does not contribute to a violation of any ozone standard in any area of 
the OTR, and that further control of emissions from that portion of 
Maine will not significantly contribute to attainment of any ozone 
standard in any area of the OTR. Accordingly, the EPA is proposing to 
grant the CAA section 176A petition filed by the state of Maine to 
remove a portion of Maine from the OTR.

III. Background and Legal Authority

A. Ozone Formation and Impacts

    Ground-level ozone causes a variety of negative effects on human 
health, vegetation, and ecosystems. In humans, acute and chronic 
exposure to ozone is associated with premature mortality and several 
morbidity effects, such as asthma exacerbation. In ecosystems, ozone 
exposure may cause visible foliar

[[Page 23311]]

injury, decrease plant growth, and affect ecological community 
composition.
    Ground-level ozone is predominantly a secondary air pollutant 
created by chemical reactions between ozone precursors including 
nitrogen oxides (NOX) and volatile organic compounds (VOCs) 
in the presence of sunlight. Emissions from electric generating 
utilities (EGUs), industrial facilities, motor vehicles, non-road 
equipment, gasoline vapors, and chemical solvents are some of the major 
anthropogenic sources of ozone precursors. The potential for ground-
level ozone formation tends to be highest during months with warmer 
temperatures and stagnant air masses; therefore, ozone levels are 
generally higher during the summer months.\4\ Increased temperatures 
may also increase emissions of anthropogenic and biogenic VOC emissions 
and can indirectly increase anthropogenic NOX emissions as 
well (e.g., through increased electricity generation to power air 
conditioning).
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    \4\ Rasmussen, D.J. et. al. (2011) Ground-level ozone-
temperature relationship in the eastern US: A monthly climatology 
for evaluating chemistry-climate models. Atmospheric Environment 47: 
142-153.
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    The EPA has regulated ozone pollution and the precursor emissions 
that contribute to ozone for the last five decades.\5\ Currently, there 
are two NAAQS in effect for ozone.\6\ On March 12, 2008, the EPA 
promulgated a revision to the ozone NAAQS, lowering both the primary 
and secondary standards to 75 ppb.\7\ On October 1, 2015, the EPA 
lowered the primary and secondary standards to 70 ppb.\8\
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    \5\ Primary and secondary NAAQS were first established for 
photochemical oxidants in 1971. 36 FR 8186 (April 30, 1971). In 
1979, the EPA revised the NAAQS to change the indicator from 
photochemical oxidants to O3 and to revise the primary 
and secondary standards. 44 FR 8202 (February 8, 1979). In 1997, the 
EPA once again revised the primary and secondary standards for ozone 
NAAQS. 62 FR 38856 (July 18, 1997). In 2015, the 1997 ozone NAAQS 
were revoked. 80 FR 12264 (March 6, 2015).
    \6\ The 1997 ozone NAAQS were revoked in 2015. 80 FR 12264 
(March 6, 2015).
    \7\ See National Ambient Air Quality Standards for Ozone, Final 
Rule, 73 FR 16436 (March 27, 2008).
    \8\ See National Ambient Air Quality Standards for Ozone, Final 
Rule, 80 FR 65292 (October 26, 2015).
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    In accordance with CAA section 107(d), the EPA designates areas as 
``attainment'' (meeting the standard), ``nonattainment'' (not meeting 
the standard) or ``unclassifiable'' (insufficient data to classify). 
States with areas designated as nonattainment must develop and submit 
State Implementation Plans (SIPs) to the EPA with the goal of attaining 
and maintaining the level of the NAAQS by the applicable attainment 
deadline. In this way, the EPA and states work collaboratively to 
establish and implement nonattainment area planning requirements that 
are designed to bring areas into attainment of the NAAQS by the 
applicable attainment deadline. A key step in ensuring that areas 
attain and maintain ozone NAAQS is to assess and understand the 
potential for ozone source formation in a given area, including the 
potential for upwind states' emissions to impact ozone formation in 
downwind states.
    Precursor emissions can be transported downwind directly or, after 
transformation in the atmosphere, as ozone or secondary ozone 
precursors. Studies have established that ozone formation, atmospheric 
residence, and transport can occur on a regional scale (i.e., hundreds 
of miles) over much of the eastern U.S., with elevated concentrations 
occurring in rural as well as metropolitan areas.\9\ Additionally, 
observational studies have demonstrated the presence of ozone and ozone 
precursor transport, and documented the impact that upwind emissions 
have on high concentrations of ozone pollution.\10\ As a result of 
ozone transport, ozone pollution levels in a given location are 
impacted by a combination of local emissions and emissions from upwind 
sources. The transport of ozone across state borders compounds the 
difficulty for downwind states to be in attainment with ozone NAAQS. 
While substantial progress has been made in reducing ozone in many 
urban areas, regional-scale ozone transport is still a major component 
of peak ozone concentrations during the summer ozone season.
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    \9\ National Research Council. 1991. Rethinking the Ozone 
Problem in Urban and Regional Air Pollution. Washington, DC: The 
National Academies Press. https://doi.org/10.17226/1889.
    \10\ Downs, T., R. Fields, R. Hudson, I. Kheirbek, G. Kleiman, 
P. Miller, and L. Weiss. 2010. The Nature of the Ozone Air Quality 
Problem in the Ozone Transport Region: A Conceptual Description. 
Northeast States for Coordinated Air Use Management.
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B. Sections 176A and 184 of the CAA and the OTR Process

    Subpart 1 of part D of title I of the CAA provides the general plan 
requirements for designated nonattainment areas. This subpart includes 
provisions governing the development of transport regions to address 
the interstate transport of pollutants that contribute to NAAQS 
violations. In particular, section 176A(a) of the CAA provides that, on 
the EPA's own motion or by a petition from the Governor of any state, 
whenever the EPA has reason to believe that the interstate transport of 
air pollutants from one or more states contributes significantly to a 
violation of the NAAQS in one or more other states, the EPA may 
establish, by rule, a transport region for such pollutant that includes 
such states. The provision further provides that the EPA may add any 
state or portion of a state to any transport region whenever the 
Administrator has reason to believe that the interstate transport of 
air pollutants from such state significantly contributes to a violation 
of the standard in the transport region.
    Section 176A(b) of the CAA provides that when the EPA establishes a 
transport region, the Administrator shall establish an associated 
transport commission, comprised of (at a minimum) the following: The 
Governor or her or his designee of each covered state, the EPA 
Administrator or a designee, the Regional EPA Administrator or a 
designee, and an air pollution control official appointed by the 
Governor of each state. The purpose of the transport commission is to 
assess the degree of interstate transport throughout the transport 
region and assess and recommend control strategies to the EPA to 
mitigate such interstate transport.
    Subpart 2 of part D of title I of the CAA provides plan 
requirements specific to the ozone NAAQS. Consistent with CAA section 
176A, found in subpart 1, subpart 2 includes specific provisions 
focused on the interstate transport of ozone. CAA section 184(a) 
establishes a single transport region for ozone--the OTR--comprising 
the states of Connecticut, Delaware, Maine, Maryland, Massachusetts, 
New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, 
Vermont, and the Consolidated Metropolitan Statistical Area for the 
District of Columbia, which includes certain portions of northern 
Virginia. The Virginia counties and cities included in the OTR are 
Arlington County, Fairfax County, Loudoun County, Prince William 
County, Stafford County, Alexandria City, Fairfax City, Falls Church 
City, Manassas City, and Manassas Park City.
    Section 184(b) of the CAA establishes specific control requirements 
that each state in the OTR is required to implement within the state, 
including certain controls on sources of NOX and VOCs. These 
control requirements are required to be implemented statewide in any 
state included within the OTR, regardless of ozone attainment 
status.\11\

[[Page 23312]]

Under CAA section 184(b)(1)(A), OTR states must include enhanced 
vehicle emissions inspection and maintenance (I/M) programs in their 
SIPs.\12\ Under CAA section 184(b)(2), major stationary sources of VOCs 
in OTR states are subject to the same requirements that apply to major 
sources in designated ozone nonattainment areas classified as 
Moderate.\13\ Thus, the state must adopt rules to apply nonattainment 
new source review (NNSR) and reasonably available control technology 
(RACT) (pursuant to CAA section 182(b)(2)) provisions for major VOC 
sources statewide. Under CAA section 184(b)(2) states must also 
implement Stage II gasoline refueling vapor recovery programs, 
incremental to vehicle Onboard Refueling Vapor Recovery achievements, 
or measures that achieve comparable emissions reductions for both 
attainment and nonattainment areas.\14\
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    \11\ We note that one exception to the statewide applicability 
of these control requirements applies to Virginia, as only a portion 
of that state is included within the OTR.
    \12\ In the OTR, enhanced vehicle inspection and maintenance 
programs are required in metropolitan statistical areas in the OTR 
with a 1990 Census population of 100,000 or more.
    \13\ Section 184(b)(2) of the CAA provides that, for purposes of 
implementing these requirements, a major stationary source shall be 
defined as any source that emits or has the potential to emit at 
least 50 tons per year of VOCs.
    \14\ See 72 FR 28772, May 16, 2012, Air Quality: Widespread Use 
for Onboard Refueling Vapor Recovery and Stage II Waiver.
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    Section 182(f) of the CAA requires states to apply the same 
requirements to major stationary sources of NOX as are 
applied to major stationary sources of VOCs under subpart 2. Thus, the 
same NNSR and RACT requirements that apply to major stationary sources 
of VOC in the OTR also apply to major stationary sources of 
NOX.\15\ CAA section 182(f) provides for a NOX 
waiver, or an exemption to the NOX requirements, where the 
Administrator determines that such NOX reductions would not 
contribute to the attainment of the NAAQS in an area. Areas granted a 
NOX waiver under CAA section 182(f) may be exempt from 
certain requirements of the EPA's motor vehicle I/M program regulations 
and from certain federal requirements of general and transportation 
conformity.\16\
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    \15\ See 57 FR 55622 (Nitrogen Oxides Supplement to the General 
Preamble, published November 25, 1992).
    \16\ As stated in the EPA's I/M (November 5, 1992; 57 FR 52950) 
and conformity rules (60 FR 57179 for transportation rules and 58 FR 
63214 for general rules), certain NOX requirements in 
those rules do not apply where the EPA grants an areawide exemption 
under CAA section 182(f).
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C. Legal Standard for This Action

    Section 176A(a)(2) of the CAA states that the Administrator may 
remove any state or portion of a state from the Ozone Transport Region 
whenever the Administrator has reason to believe that the control of 
emissions in that state or portion of that state pursuant to its 
inclusion in the transport region will not significantly contribute to 
the attainment of the standard in any area in the region. The provision 
does not provide further methodology or criteria for the Administrator 
to apply other than this language when determining whether to remove a 
state or portion of a state from the OTR. Therefore, the meaning of 
this language is ambiguous, and the EPA has the authority to exercise 
discretion in its expertise to interpret this language and identify 
relevant criteria and develop a reasonable methodology in doing so. 
See, e.g., Chevron, U.S.A., Inc. v. NRDC, 467 U.S. 837, 842-43 (1984); 
Smiley v. Citibank, 517 U.S. 735, 744-45 (1996). As explained in this 
action, in determining whether to grant the state of Maine's petition 
the EPA intends to draw upon its interpretations of the CAA's suite of 
interstate pollution transport provisions, taking into account any 
legal precedents established by prior EPA actions and associated court 
decisions.
    The EPA has never taken final action to remove any state or portion 
of a state from the OTR under section 176A(a)(2) of the CAA.\17\ The 
Agency has in recent years acted pursuant to CAA section 176A(a)(1) to 
deny a request to expand the OTR,\18\ but did not in that action have 
cause to interpret the operative language in CAA section 176A.\19\
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    \17\ On August 5, 2013, the EPA issued a proposed rule, 
``Approval and Promulgation of Air Quality Implementation Plans; 
Maine; Oxides of Nitrogen Exemption and Ozone Transport 
Restructuring'' (78 FR 47253). In this notice, the EPA proposed to 
approve Maine's request for a limited ``restructuring'' to remove 
the OTR-related VOC nonattainment new source requirements (NNSR), 
but the EPA did not take final action on this proposal.
    \18\ 82 FR 51238 (November 3, 2017).
    \19\ The EPA denied the request from several states in the OTR 
to add an additional nine states to the transport region on the 
basis that Congress' use of the term ``may'' in CAA section 176A(a) 
granted the Administrator reasonable discretion in determining 
whether or not to grant the petition, and that other statutory 
authorities the EPA had historically relied upon to address 
interstate transport provided advantages over expanding the OTR. The 
D.C. Circuit upheld the EPA's denial of the section 176A petition to 
expand the OTR, noting that its review of the EPA's denial was 
``extremely limited and highly deferential,'' and that even if 
petitioners had met CAA section 176A(a)(1)'s criterion for expanding 
the OTR, ``the statute provides only that EPA `may' expand the 
region, not that it `shall' or `must' do so.'' New York v. EPA, 921 
F.3d 257, 261-62 (D.C. Cir. 2019).
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    Section 176A(a)(2) of the CAA does not expressly reference other 
statutory provisions, but the EPA believes it is appropriate to 
interpret the key terms in the section (i.e., ``control of emissions . 
. . will not significantly contribute to the attainment of the 
standard'' and ``in any area in the region'') within the context of and 
consistently with other parts of the CAA that govern the interstate 
transport of ozone pollution, taking into account relevant facts and 
circumstances and the EPA's past approaches to addressing interstate 
ozone transport.
    The CAA provision that states and the EPA have primarily relied 
upon to address interstate pollution transport is section 
110(a)(2)(D)(i)(I) of the CAA, often referred to as the ``good 
neighbor'' provision. The provision requires all states to submit SIPs 
that contain adequate provisions prohibiting any source or other type 
of emissions activity within the state from emitting any air pollutant 
in amounts which ``will contribute significantly'' to nonattainment in, 
or interfere with maintenance by, any other state with respect to any 
NAAQS. Thus, each state is required to submit a SIP that demonstrates 
the state is adequately controlling sources of emissions that would 
impact another states' air quality relative to the NAAQS in violation 
of the good neighbor provision. However, if a state does not adequately 
address the good neighbor provision requirements in a SIP submission, 
the CAA requires that the EPA must address the requirements of the good 
neighbor provision in the state's stead. Specifically, if the EPA 
disapproves a state's SIP submission or if the EPA finds that a state 
has failed to submit a required SIP, then the EPA must promulgate a 
federal implementation plan (FIP) within two years, unless the state 
corrects the deficiency, and the EPA approves the plan or plan revision 
before the EPA promulgates a FIP.\20\
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    \20\ CAA section 110(c)(1).
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    To address the regional transport of ozone pursuant to the CAA's 
good neighbor provision, the EPA has promulgated four regional 
interstate transport rules focusing on the reduction of NOX 
emissions, as the primary meaningful precursor to address regional 
ozone transport across state boundaries, from certain sources located 
in states in the eastern half of the U.S.21 22 The four 
interstate transport

[[Page 23313]]

rulemakings are the NOX SIP Call,\23\ Clean Air Interstate 
Rule (CAIR),\24\ the Cross-State Air Pollution Rule (CSAPR),\25\ and 
the Cross-State Air Pollution Rule Update (CSAPR 
Update).26 27
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    \21\ For purposes of these rulemakings, the western U.S. (or the 
West) consists of the 11 western contiguous states of Arizona, 
California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, 
Utah, Washington, and Wyoming.
    \22\ Two of these rulemakings also addressed the reduction of 
annual NOX and sulfur dioxide (SO2) emissions 
for the purposes of addressing the interstate transport of 
particulate matter pollution pursuant to the good neighbor 
provision.
    \23\ 62 FR 57356 (October 27, 1998).
    \24\ 70 FR 25162 (May 12, 2005).
    \25\ 76 FR 48208 (August 8, 2011).
    \26\ 81 FR 74504 (October 26, 2016).
    \27\ In December of 2018, the EPA also promulgated a 
determination regarding remaining good neighbor obligations under 
the 2008 ozone NAAQS for the CSAPR region (referred to as the 
``CSAPR Close Out'') at 83 FR 65878, but that determination was 
vacated by the D.C. Circuit. New York v. EPA, No. 19-1019, Judgement 
at 4 (D.C. Circuit October 1, 2019).
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    Through the development and implementation of CSAPR and the CSAPR 
Update, the EPA, working in partnership with the states, developed a 
four-step interstate transport framework to interpret and address the 
requirements of the good neighbor provision. The four steps are: (1) 
Identifying downwind air quality monitors (known as ``receptors'') that 
are expected to have problems attaining or maintaining clean air 
standards (i.e., NAAQS); (2) identifying upwind states that impact 
those downwind air quality problems sufficiently such that they are 
considered ``linked'' and therefore warrant further review and 
analysis; (3) identifying the emissions reductions necessary (if any), 
considering cost and air quality factors, to prevent linked upwind 
states identified in step 2 from contributing significantly to 
nonattainment or interfering with maintenance of the NAAQS at the 
locations of the downwind air quality problems; and (4) adopting 
permanent and enforceable measures needed to achieve those emissions 
reductions.
    Given the use of the phrase ``significantly contribute to [ ] 
attainment'' in CAA section 176A(a)(2), the EPA believes it is 
reasonable to look to the 4-step interstate transport framework to 
guide its analysis of whether a state or portion of a state has met the 
necessary condition for removal from the OTR in CAA section 176A(a)(2). 
Under Step 1 of the interstate transport framework, the EPA has 
interpreted the term ``will'' in the phrase ``will significantly 
contribute'' in section 110(a)(2)(D)(i)(I) by looking at current 
downwind air quality problems and whether those air quality problems 
will persist in a future year, i.e., by focusing its analysis regarding 
downwind interstate transport impacts on an analytic year in the 
future. In its transport rulemakings, the EPA has considered current 
monitored air quality data in addition to future projections ``because 
`will' can mean either certainty or indicate the future tense,'' and 
considering present-day data to inform the projected identification of 
downwind air quality problems ``give[s] effect to both interpretations 
of the word.'' North Carolina v. EPA, 531 F.3d 896, 913-14 (D.C. Cir. 
2008). See 63 FR 57356, 57375 (Oct. 27, 1998) (NOX SIP Call) 
(relying on both monitored and modeled data); 70 FR 25162, 25241 (May 
12, 2005) (CAIR); 81 FR 74504, 74517 (October 26, 2016) (CSAPR 
Update).\28\ Specifically, in those rules, the EPA explained that it 
had the most confidence in its projections of nonattainment for those 
counties that also measure nonattainment for the most recent period of 
available ambient data. 81 FR 74517, 74531. In the CSAPR Update, 
receptors that had clean measured data but were projected to have 
nonattainment problems in the future-year modeling were denoted by the 
EPA as maintenance-only receptors, acknowledging that while currently 
attaining the NAAQS, such areas could violate the standard in the 
future under certain meteorological conditions. The D.C. Circuit has 
upheld this balance struck by the EPA in considering historical 
monitored data as well as future projected modeled data as a method for 
identifying downwind air quality problems at Step 1. See, e.g., 
Wisconsin v. EPA, 938 F.3d 303, 326 (D.C. Cir. 2019).
---------------------------------------------------------------------------

    \28\ The EPA did not consider current monitored data in 
conjunction with modeled projections of air quality in a future year 
in CSAPR because the most recent monitoring data prior to CSAPR's 
promulgation reflected effects of the unlawful CAIR. 76 FR 48208, 
48230 (August 8, 2011).
---------------------------------------------------------------------------

    In CSAPR and the CSAPR Update, the EPA used a threshold of one 
percent of the NAAQS to determine whether a given upwind state was 
``linked'' at step 2 of the four-step interstate transport framework 
and would, therefore, contribute to downwind nonattainment and 
maintenance sites identified in step 1. If a state's impact did not 
equal or exceed the one percent threshold, the upwind state was not 
``linked'' to a downwind air quality problem, and the EPA therefore 
concluded that the state will not significantly contribute to 
nonattainment or interfere with maintenance of the NAAQS in the 
downwind states. However, if a state's impact equaled or exceeded the 
one percent threshold, the state's emissions were further evaluated in 
step 3, taking into account both air quality and cost considerations, 
to determine what, if any, emissions reductions might be necessary to 
address the good neighbor provision.
    In this action, these first two steps of the 4-step interstate 
transport framework are particularly informative to analyze the 
standard for removal of areas from the OTR established by CAA section 
176A(a)(2). We acknowledge that the specific inquiry posed by the OTR 
removal provision does not perfectly align with the inquiry in the CAA 
section 110 good neighbor provision or in CAA section 176A(a)(1). Read 
literally, rather than identify significant contribution of emissions 
to nonattainment or maintenance receptors--that is, determining whether 
a state's emissions are large enough that they negatively impact air 
quality in another state and thus may warrant the imposition of control 
measures--CAA section 176A(a)(2) presents a different but related 
question: Whether OTR controls in a state will not significantly 
contribute to attainment anywhere in the OTR. Despite the framing of 
CAA section 176A(a)(2) as significant contribution to attainment rather 
than significant contribution to nonattainment, we think CAA section 
176A(a)(2) is best read within the context of the statutory section as 
a whole, and in conjunction with the other CAA provisions addressing 
interstate pollution transport, and therefore focused on impacts to 
areas that are struggling with attaining or maintaining the NAAQS. We 
acknowledge that one could read CAA section 176A(a)(2) as asking the 
EPA to only analyze OTR areas that are already in attainment and 
determine whether such areas would remain so after the removal of a 
state or portion of a state from the OTR per CAA section 
176A(a)(2).\29\
---------------------------------------------------------------------------

    \29\ We note that this interpretation would not address whether 
the reductions achieved by OTR controls in a state are also 
effective at ameliorating air quality in areas that are in 
nonattainment. In addition, it would require the EPA to establish an 
entirely new framework to analyze how emissions control measures 
``significantly contribute'' to attainment--a standard that would 
not necessarily be equivalent to or in harmony with the 
``significant contribution'' standard of CAA section 
110(a)(2)(D)(i)(I).
---------------------------------------------------------------------------

    However, we think a better interpretation of CAA section 176A(a)(2) 
is that it is establishing a standard that is the inverse of the 
question presented in CAA section 176A(a)(1). At base, CAA section 
176A(a) presents two authorities--the Administrator may add a state or 
a portion of a state to the transport region whenever the Administrator 
has reason to believe that pollutants from that state significantly 
contribute to a violation of the NAAQS in the transport region and may 
remove a state or a portion of a state whenever the Administrator has 
reason to believe

[[Page 23314]]

that the state's continued inclusion in the OTR will not be required 
for attainment in the transport region, i.e., that the petitioning 
state is not significantly contributing to air quality problems in the 
region and will not so contribute if the state is removed from the OTR. 
Interpreting the statute in this way means that under CAA section 
176A(a)(2), although there is no explicit reference to significant 
contribution to nonattainment or maintenance, the EPA's inquiry focuses 
on whether the state, or portion of the state, to be removed is 
significantly contributing or will contribute to nonattainment of the 
standard in the OTR. This inquiry, therefore, does not solely focus on 
consequences to areas that are already in attainment.
    In determining whether removal is warranted under section 
176A(a)(2), the EPA must also interpret the phrase ``control of 
emissions in that state or portion of that state pursuant to this 
section.'' The EPA proposes that ``controls'' refers to new controls 
that would be required under CAA section 184(b) if the state or portion 
of the state were to remain in the OTR, as opposed to controls that the 
state has already adopted as required by the CAA due to its inclusion 
in the OTR. We believe interpreting ``controls'' in this manner gives 
effect to the forward-looking nature of the provision, which asks the 
Administrator to analyze whether removal of the state or portion of the 
state from the OTR ``will'' have the effect of contributing to air 
quality problems in any area in the OTR. In undertaking that forward-
looking analysis, we think it is reasonable to assume that existing, 
SIP-approved controls that were adopted by the state due to its 
inclusion in the OTR will remain in place. Under the CAA, a state 
seeking to revise its SIP must undergo a section 110(l) demonstration. 
Section 110(l) of the CAA states that the Administrator cannot approve 
a SIP revision if the revision would interfere with any applicable 
requirement concerning attainment and reasonable further progress 
(RFP), or any other applicable requirement of the CAA. Therefore, the 
EPA will only approve a SIP revision that removes or modifies control 
measures after the state has demonstrated that such removal or 
modification will not interfere with attainment of the NAAQS, Rate of 
Progress (ROP), RFP or any other applicable requirement of the CAA.
    States may demonstrate a revision's noninterference with NAAQS-
related requirements by substituting one measure with another that 
achieves equivalent or greater emissions reductions or air quality 
benefit or by preparing an air quality analysis showing that removing 
the measure will not interfere with other applicable requirements 
(i.e., without a substitute measure).\30\ Additionally, for areas that 
do not have an attainment demonstration, the EPA would consider 
alternative analyses to demonstrate noninterference on a case-by-case 
basis. The level of rigor in the alternative demonstration would vary 
depending on the nature of the requirement, its potential impact on air 
quality in the area, and the air quality of the area in which the 
requirement applies.
---------------------------------------------------------------------------

    \30\ 78 FR 68378, 68382 (November 14, 2013).
---------------------------------------------------------------------------

    Moreover, this interpretation of CAA section 176A(a)(2) is 
consistent with the EPA's treatment of nonattainment areas seeking 
redesignation to attainment under CAA section 107(d)(3). States seeking 
redesignation of a nonattainment area to attainment are required to 
demonstrate that the area will maintain the NAAQS, per CAA section 
107(d)(3)(E)(iv) and CAA section 175A. In making demonstrations of 
maintenance, states perform air quality modeling or emissions 
projections showing that existing control requirements are sufficient 
to maintain the NAAQS in question. However, once redesignated, a state 
may seek revision of its SIP to remove nonattainment SIP measures that 
are not necessary to maintain the NAAQS, subject to a section 110(l) 
demonstration.\31\ We, therefore, think the analysis under CAA section 
176A(a)(2) should, like a CAA section 175A maintenance demonstration, 
assume continued implementation of existing OTR-control measures even 
though such measures would no longer be statutorily mandated once the 
EPA removes a state or portion of the state from the OTR. As in the 
case of an area redesignated to attainment, a state could only stop 
actively implementing those measures and remove them from its SIP after 
satisfying its obligation under section 110(l), as discussed earlier. 
We note that in submitting its petition to the EPA to remove portions 
of the state from the OTR, Maine committed to retaining all existing 
OTR control measures in its SIP.
---------------------------------------------------------------------------

    \31\ Per CAA section 175A(d) and the EPA's longstanding 
guidance, control measures that the state shows are no longer 
necessary for maintenance of the NAAQS must be retained as 
contingency provisions in the maintenance plan, to be implemented in 
the event of a subsequent violation of the NAAQS. See Procedures for 
Processing Requests to Redesignate Areas to Attainment, September 4, 
1992.
---------------------------------------------------------------------------

    To establish the proper geographic scope of the EPA's CAA section 
176A(a)(2) ``significant contribution'' analysis, another phrase in the 
provision must be interpreted: ``any area in the region.'' The EPA 
proposes to interpret the phrase ``any area in the region'' to mean all 
existing areas in the OTR, including areas within the petitioning 
state. Here, this would include all areas of Maine, because the entire 
state is included in the OTR as established under section 184. However, 
we recognize that it is possible that Congress intended the EPA to 
focus primarily on interstate impacts within the OTR, rather than 
impacts within the petitioning state. Therefore, the Agency is 
requesting comment on this alternative interpretation, as set forth in 
more detail below.
    Read literally, ``any'' is a broad term that, in this context, 
encompasses areas within the petitioning state because they are 
currently in the OTR. However, case law recognizes that `` `any' means 
different things depending upon the setting.'' Nixon v. Missouri 
Municipal League, 541 U.S. 125, 132 (2004); see also Small v. U.S., 544 
U.S. 385, 388 (2005) (``The word `any' considered alone cannot answer 
[the] question''). Here, aspects of the statutory structure and context 
indicate that ``any'' may reasonably be interpreted to have a narrower 
scope than all areas of the current OTR. For instance, it could be 
relevant that the provision at issue is part of CAA section 176A, which 
is titled, ``Interstate Transport Commissions,'' and the provision at 
issue is located within the subsection entitled ``Authority to 
Establish Interstate Transport Regions.'' The basis under CAA section 
176A(a) for creating or expanding a transport region is the interstate 
effects of air pollution. Further, under the CAA's cooperative 
federalism scheme, states retain the primary regulatory role in 
developing and implementing the necessary emissions reductions within 
their borders to meet the air quality standards established by the EPA. 
See CAA section 101(a)(3). If a state's removal from the OTR were 
projected to have negative impacts on other areas within the state, 
under the CAA that state would retain jurisdiction, authority, and 
responsibility to address such air quality problems in the first 
instance. See, e.g., CAA sections 110, 172, 181, and 182. Rejecting a 
state's petition to be removed from the OTR solely on the basis of 
intrastate impacts could be seen as going beyond the purpose of CAA 
section 176A, which was promulgated to address the interstate effects 
of air pollution, i.e., a problem in which

[[Page 23315]]

affected states might otherwise have no recourse.
    Nonetheless, it is also possible that Congress envisioned that the 
grounds for removing an area from the OTR should require a different 
bar (i.e., a demonstration that removal would not cause air quality 
problems in other states and in one's own state) than the conditions 
for adding a new area to a transport region (which are limited to out-
of-state impacts). This broader reading of the term ``any'' in this 
context also comports with the overall public health and welfare 
purposes of the CAA. In this action, as explained below, under either 
interpretation, the EPA proposes that Maine's petition may be granted, 
because its own emissions' impact on itself do not--and are not 
expected to if the petition is granted--contribute to ozone NAAQS 
attainment problems within the state. Therefore, we propose to apply 
the broader interpretation, wherein ``any area of the region'' 
encompasses all current areas of the OTR, including the state of Maine. 
We request comment on both interpretations of the phrase ``any area of 
the region.''
    Turning back to the provision as a whole, informed by the backdrop 
and context of other CAA provisions addressing interstate pollution 
transport and the states' and the EPA's actions addressing those 
provisions, we think it is reasonable to interpret CAA section 
176A(a)(2) in a manner consistent with EPA's 4-step interstate 
transport framework, and in particular here, Steps 1 and 2. Under this 
interpretation, the EPA determines whether air quality problems exist 
in the transport region (including the state or area of a state 
petitioned to be removed) based on projected air quality modeling and 
also current monitored data. If so, the EPA then determines whether the 
state (or portion of a state) to be removed from the OTR is 
contributing less than one percent of the NAAQS to those problems, 
indicating that the state (or portion of a state) is not significantly 
contributing to air quality problems in the OTR, and that additional 
OTR controls in that state (or portion of that state) and continued OTR 
membership are, therefore, unnecessary for attainment of the NAAQS in 
the OTR. Applying that framework to the question presented by CAA 
section 176A(a)(2), we think a reasonable interpretation requires the 
Administrator to identify whether there are ambient air monitoring 
sites in the OTR that either are projected to be in nonattainment based 
on modeling data, or potentially struggle with maintenance or are 
currently violating the NAAQS based on monitored data, and whether the 
area petitioned to be removed from the transport region contributes 
below one percent of the NAAQS to those monitors.

D. Previous Actions

    Consistent with the 1990 CAA Amendments, nine Maine counties were 
designated as nonattainment of the now-revoked 1979 1-hour NAAQS (0.12 
parts per million (ppm)). York, Cumberland, Sagadahoc, Androscoggin, 
Kennebec, Knox, and Lincoln Counties were classified as Moderate 
nonattainment areas. Waldo and Hancock Counties were classified as 
Marginal nonattainment areas.
    Maine had two nonattainment areas under the now-revoked 1997 8-hour 
ozone standard. The Portland Ozone Nonattainment area consisted of 56 
cities and towns in York, Cumberland, and Sagadahoc Counties, along 
with the town of Durham in Androscoggin County, and was classified as 
Marginal for the 1997 ozone standard. The Hancock, Knox, Lincoln, and 
Waldo Counties Ozone Nonattainment Area (also known as the Midcoast 
area) consisted of 55 coastal towns and islands in Hancock, Knox, 
Lincoln, and Waldo counties and was designated as nonattainment under 
Subpart 1 for the 8-hour ozone standard. Maine was designated 
``Attainment/Unclassifiable'' statewide for both the 2008 and 2015 8-
hour ozone standards of 0.075 ppm and 0.070 ppm, respectively.
    As previously discussed, Section 184(b) of the CAA established 
certain control requirements that each state in the OTR is required to 
implement within the state. Section 182(f) of the CAA Amendments allows 
for the suspension of the OTR stationary source NOX 
requirements based on a demonstration that additional NOX 
reductions would not produce net ozone air quality benefits in the OTR. 
Maine has petitioned for and has been granted the following CAA section 
182(f) NOX waivers.
    On December 26, 1995 (60 FR 66748), the EPA approved an exemption 
request for the Northern Maine area from CAA section 182(f) 
NOX requirements. This action exempted the Oxford, Franklin, 
Somerset, Piscataquis, Penobscot, Washington, Aroostook, Hancock and 
Waldo counties from the requirements to implement NOX 
control measures for existing stationary sources, NNSR for new sources 
and modifications that are major for NOX, NOX 
RACT requirements, the NOX-related general conformity 
provisions, and the NOX-related transportation conformity 
provisions now contained in 40 CFR 93.119.\32\
---------------------------------------------------------------------------

    \32\ Transportation and general conformity requirements only 
apply in nonattainment areas and areas redesignated to attainment 
with an approved CAA section 175A maintenance plan. See CAA section 
176(c)(5). Transportation and general conformity do not apply in 
attainment areas in the OTR.
---------------------------------------------------------------------------

    On February 3, 2006 (71 FR 5791), the EPA approved a request for an 
exemption for a similar area in northern Maine (specifically Aroostook, 
Franklin, Oxford, Penobscot, Piscataquis, Somerset, Washington, and 
portions of Hancock and Waldo Counties) under the 1997 ozone standard.
    On July 29, 2014 (78 FR 43945), the EPA approved the state of 
Maine's request for an exemption from the NOX requirements 
contained in section 182(f) of the CAA for the entire state of Maine 
for the 2008 ozone standard. The CAA does not provide a similar VOC 
waiver process, and major stationary sources of VOC remain subject to 
NNSR and RACT requirements throughout the entire state of Maine.
    In addition to the NOX waivers under CAA section 182(f), 
Maine requested and was granted an OTR restructuring with respect to 
enhanced I/M requirements.\33\ (66 FR 1873; January 10, 2001). While 
the Maine I/M rule did not meet all requirements of the EPA's final 
rule for enhanced I/M, the EPA determined that the implementation of an 
enhanced I/M program in Maine in place of the approved Maine I/M rule 
would not significantly contribute to attainment in any other state in 
the OTR.
---------------------------------------------------------------------------

    \33\ The EPA's I/M rule was established on November 5, 1992 (57 
FR 52950). The EPA made significant revisions to the I/M rule on 
September 18, 1995 (60 FR 48035) and on July 25, 1996 (61 FR 39036). 
Maine is subject to the requirements of the Act for an I/M program 
in the Portland, Maine area.
---------------------------------------------------------------------------

IV. Maine CAA Section 176A Petition

A. Summary of the Maine CAA Section 176A Petition

    On February 24, 2020, the state of Maine petitioned the EPA 
pursuant to CAA section 176A(a)(2) for the removal of the state of 
Maine from the OTR with the exception of the 111 towns and cities 
listed in Table 1 comprising the Portland and Midcoast Ozone Areas.

[[Page 23316]]

 Table 1--Maine Towns and Cities To Remain in the Ozone Transport Region
------------------------------------------------------------------------
 
-------------------------------------------------------------------------
Androscoggin County (includes only the following town): Durham.
Cumberland County (includes only the following towns and cities):
 Brunswick, Cape Elizabeth, Casco, Cumberland, Falmouth, Freeport, Frye
 Island, Gorham, Gray, Harpswell, Long Island, New Gloucester, North
 Yarmouth, Portland, Pownal, Raymond, Scarborough, South Portland,
 Standish, Westbrook, Windham, and Yarmouth.
Hancock County (includes only the following towns and cities): Bar
 Harbor, Blue Hill, Brooklin, Brooksville, Cranberry Isles, Deer Isle,
 Frenchboro, Gouldsboro, Hancock, Lamoine, Mount Desert, Sedwick,
 Sorrento, Southwest Harbor, Stonington, Sullivan, Surry, Swans Island,
 Tremont, Trenton, and Winter Harbor.
Knox County (includes only the following towns and cities): Camden,
 Criehaven, Cushing, Friendship, Isle au Haut, Matinicus Isle, Muscle
 Ridge Shoals, North Haven, Owls Head, Rockland, Rockport, St. George,
 South Thomaston, Thomaston, Vinalhaven, and Warren.
Lincoln County (includes only the following towns and cities): Alna,
 Boothbay, Boothbay Harbor, Breman, Bristol, Damariscotta, Dresden,
 Edgecomb, Monhegan, Newcastle, Nobleboro, South Bristol, Southport,
 Waldoboro, Westport, and Wiscasset.
Sagadahoc County (includes all towns and cities).
Waldo County (includes only the following town): Islesboro.
York County (includes only the following towns and cities): Alfred,
 Arundel, Berwick, Biddeford, Buxton, Dayton, Eliot, Hollis, Kennebunk,
 Kennebunkport, Kittery, Limington, Lyman, North Berwick, Ogunquit, Old
 Orchard Beach, Saco, Sanford, South Berwick, Wells, and York.
------------------------------------------------------------------------

    The Maine Department of Environmental Protection (Maine DEP) 
provided an analysis purporting to demonstrate that Maine's emissions 
are an insignificant contributor to the nonattainment for the 8-hour 
ozone NAAQS in other states and in those areas in Maine that will 
remain in the OTR. Maine's analysis consists of modeling ``back 
trajectories'' for ozone exceedance days in the 2016-2018 period 
recorded at monitoring locations in southern New England and in Maine, 
EPA source-apportionment modeling results, and emissions-inventory data 
for Maine and the OTR.\34\ The EPA's assessment of the CAA section 176A 
petition is discussed in Section V.
---------------------------------------------------------------------------

    \34\ Back trajectory analyses use interpolated measured or 
modeled meteorological fields to estimate the most likely central 
path over geographical areas that an air parcel travels before 
reaching a specific location at a given time.
---------------------------------------------------------------------------

B. Provisions Impacted by the Maine CAA Section 176A Petition

    If the EPA takes final action granting Maine's petition, the 
following consequences would result. First, for areas to be removed 
from the OTR, different requirements would become applicable under the 
New Source Review (NSR) construction permitting program. In these 
areas, Maine's minor NSR and Prevention of Significant Deterioration 
(PSD) permitting programs would apply to ozone (NOX and VOC) 
in lieu of the Nonattainment New Source Review (NNSR) permitting 
requirements that currently apply. However, the areas remaining in the 
OTR would continue to be subject to the NNSR permitting requirements. 
In addition, Maine could alter the geographic applicability of its 
motor vehicle I/M program through a SIP revision. Such a change would 
only have a minimal impact as the majority of the counties will remain 
within the OTR.\35\ Regarding stage II refueling vapor recovery 
programs for motor vehicles, granting Maine's petition would not impact 
emissions because the EPA previously approved the state's request to 
decommission the program, under the reasoning that emissions reductions 
resulting from the program are now accomplished with on-board vapor 
recovery equipment installed at the time of vehicle manufacture.\36\ 
Finally, upon approval of Maine's petition, only the portion of the 
state remaining in the OTR would be required to adopt ozone RACT 
requirements. However, RACT requirements already adopted in Maine's SIP 
could only be removed if the state submitted a SIP revision and 
satisfies the CAA's anti-backsliding provisions of section 110(l).
---------------------------------------------------------------------------

    \35\ The six towns within Cumberland county that are part of the 
petition contain only five percent of the county's population.
    \36\ See FR 82 32480 (July 14, 2017).
---------------------------------------------------------------------------

    In the February 24, 2020, petition to remove areas of the state 
from the OTR, Maine confirmed that no current control requirements in 
the SIP will be relaxed as a result of the petition request. To date, 
Maine has not submitted any SIP revisions to modify current OTR control 
requirements and should the EPA grant final approval of Maine's 
petition, this would not in itself have the effect of revising Maine's 
existing SIP requirements. A more detailed discussion of the changes 
follows.
i. NSR
    The NSR provisions of the CAA are a combination of air quality 
planning and air pollution control technology provisions that require 
stationary sources of air pollution to obtain permits before they are 
first constructed or engage in a modification of an existing facility. 
Part C of title I of the CAA contains the PSD program, which reflects 
the requirements for the preconstruction review and permitting of new 
and modified major stationary sources of air pollution (specifically, 
sources emitting specific amounts of regulated NSR pollutants) located 
in areas meeting the NAAQS (``attainment'' areas) and, areas for which 
there is insufficient information to classify an area as either 
attainment or nonattainment (``unclassifiable'' areas). Under the PSD 
program, new major stationary sources and major modifications of 
existing sources must apply best available control technology (BACT) 
for each regulated NSR pollutant emitted above specific thresholds and 
conduct an air quality analysis to demonstrate that the proposed source 
will not cause or contribute to a violation of any NAAQS or PSD 
increment.\37\
---------------------------------------------------------------------------

    \37\ See CAA section 165(a).
---------------------------------------------------------------------------

    Part D of title I of the CAA contains the NNSR program, reflecting 
the requirements for the preconstruction review and permitting of new 
and modified major stationary sources of air pollution locating in 
areas designated as not meeting the NAAQS (``nonattainment'' areas). 
Under the NNSR program, new major sources and major modifications of 
existing sources in a nonattainment area must apply control technology 
that meets the statutory definition of Lowest Achievable Emissions Rate 
(LAER) and must obtain emissions reductions from existing sources to 
offset the emissions increase from the new or modified source and 
ensure that the emissions increase will not interfere with a state's 
reasonable further progress toward attainment of the NAAQS.\38\
---------------------------------------------------------------------------

    \38\ See CAA section 173(a) and (c).
---------------------------------------------------------------------------

    The permit program for non-major sources and minor modifications to 
major and non-major sources is known as the minor NSR program. CAA 
section 110(a)(2)(C) requires states to develop a permitting program to 
regulate the

[[Page 23317]]

construction and modification of any stationary source ``as necessary 
to assure that [NAAQS] are achieved.''
    To comply with the requirements of the CAA and the NSR implementing 
regulations at 40 CFR 51.160 through 51.166, most states have EPA-
approved SIPs in place to implement the PSD, NNSR, and minor NSR 
preconstruction permit programs. The state of Maine implements its NSR 
program requirements through 06-096 Code of Maine Regulations (CMR) in 
Chapter 100 (Definitions Regulation), Chapter 113 (Growth Offset 
Regulation), and Chapter 115 (Major and Minor Source Air Emission 
License Regulations). The EPA first approved Maine's NSR program 
regulations as part of the state's SIP on January 30, 1980 (45 FR 
6784).\39\ Together, Maine's PSD, NNSR, and minor NSR permitting 
programs ensure that construction of new and modified stationary 
sources of air pollutant emissions do not significantly deteriorate air 
quality in ``clean areas,'' impede reasonable further progress in 
nonattainment areas, or interfere with maintenance of any NAAQS.
---------------------------------------------------------------------------

    \39\ The EPA last approved revisions to the program on August 1, 
2016 (81 FR 50353).
---------------------------------------------------------------------------

    The applicability of the PSD, NNSR or minor NSR programs to a 
stationary source must be determined in advance of construction and is 
a pollutant-specific determination. Thus, a stationary source may be 
subject to PSD for certain pollutants, NNSR for some pollutants and 
minor NSR for others after assessing the quantity of emissions, the 
regulated NSR pollutants emitted and the area's attainment status.
    Pursuant to Maine's NNSR program, sources with a potential to emit 
equal to or greater than 100 tons per year of NOX or 50 tons 
per year of VOC qualify as major stationary sources.\40\ New major 
stationary sources are subject to NNSR permitting requirements, 
including LAER and emissions offsets, for any pollutant (i.e., 
NOX or VOC) which the source has the a potential to emit in 
amounts equal to or greater than the respective major source threshold. 
For existing major stationary sources in Maine, NNSR permitting 
requirements apply to construction projects that would result in a 
significant net emissions increase of NOX or VOC, defined as 
an increase equal to or greater than 40 tons per year for either 
NOX or VOC. Such projects qualify as a major modification at 
an existing major stationary source.
---------------------------------------------------------------------------

    \40\ Lower applicability thresholds apply for NOX and 
VOC in areas designated as Serious, Severe, and extreme 
nonattainment for a particular ozone standard. However, currently, 
no areas in Maine are classified as such, nor are any areas subject 
to lower thresholds as a result of prior NAAQS nonattainment status.
---------------------------------------------------------------------------

    The CAA requires PSD programs to apply to any major emitting 
facility, defined as a stationary source that emits, or has a potential 
to emit, at least 100 tpy of a regulated NSR pollutant, if the source 
is in one of 28 listed source categories, or, if the source is not, 
then at least 250 tpy of a regulated NSR pollutant. See 42 U.S.C. 
7479(1); 40 CFR 51.166(b)(1); and 40 CFR 52.21(b)(1). Maine's PSD 
program is more stringent than the federal program in that it sets the 
major stationary source threshold (for purposes of determining 
applicability to PSD permit requirements) at 100 tpy of a regulated NSR 
pollutant regardless of source category. See Chapter 100 (125)(B). New 
major stationary sources are subject to PSD permitting requirements, 
including BACT and air quality impacts analysis, for any regulated NSR 
pollutant that the source has the potential to emit in an amount equal 
to or greater than pollutant-specific significant emissions rates 
contained in the regulations. For both NOX and VOC, the 
significant emissions rate under PSD is 40 tons per year. Because the 
OTR is treated as moderate nonattainment for ozone, the precursors 
NOX and VOC are not currently subject to PSD permitting 
requirements in Maine.\41\ See 40 CFR 51.166(i)(2).
---------------------------------------------------------------------------

    \41\ Because NOX is also a regulated NSR pollutant 
corresponding to the NO2 NAAQS, under the current OTR 
status in Maine, new major sources and major modifications can be 
subject to both NNSR (for NOX as an ozone precursor) and 
PSD (for NO2, measured as total NOx for applicability 
purposes). In general, this means that in addition to LAER and 
emission offsets, the source would also be required to demonstrate 
that their significant emissions of NOx would not cause or 
contribute to a violation of the NO2 NAAQS or PSD 
increments.
---------------------------------------------------------------------------

    Maine's minor NSR program regulates construction activities and 
resulting emissions at some new and existing sources not subject to 
NNSR or PSD. The emissions threshold for minor NSR applicability is 10 
pounds per hour or 100 pounds per day.\42\ The applicable control 
technology standard under Maine's minor NSR program is BACT, which uses 
the same definition of BACT as the state's PSD-program regulations. 
Thus, in Maine, BACT must be applied by all new major stationary 
sources and major modifications under the PSD program and to new non-
major sources and minor modifications at both major and non-major 
sources under the state's minor NSR program. Under the definition in 
both programs, BACT is an emissions limitation based on the maximum 
degree of control that can be achieved for a particular pollutant 
taking into account energy, environmental, and economic impacts. BACT 
can be add[hyphen]on control equipment or a design, equipment, work 
practice, or operational standard if imposition of an emissions 
standard is infeasible.
---------------------------------------------------------------------------

    \42\ Maine's minor NSR program also contains applicability 
thresholds for fuel burning devices, i.e., boilers and engines, and 
applicability of the minor source program for these devices is 
determined based on maximum heat input.
---------------------------------------------------------------------------

    The applicable control technology standard under Maine's NNSR 
program is the Lowest Achievable Emissions Rate (LAER). With regard to 
NOX and VOC, LAER is applicable to new major stationary 
sources and major modifications because of the state's current 
inclusion in the OTR (even though all areas in Maine are designated 
attainment or unclassifiable for ozone). Maine defines LAER within 
Chapter 100 as meaning the more stringent rate of emissions based on 
the following:

    The most stringent emission limitation which is contained in the 
implementation plan of any State for that class or category of 
source, unless the owner or operator of the proposed source 
demonstrates that those limitations are not achievable; or
    The most stringent emission limitation which is achieved in 
practice by that class or category of source, whichever is more 
stringent. In no event may LAER result in emission of any pollutant 
in excess of those standards and limitations promulgated pursuant to 
CAA section 111 or 112, or any emission standard established by the 
Maine Department of Environmental Protection.\43\
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    \43\ See Chapter 100 section (78), definition of LAER.

    Because of Maine's location in the OTR, LAER is currently required 
if emissions of NOX or VOC from a project at a major source 
exceed Maine's NNSR applicability thresholds, and BACT is required if 
project emissions are below those thresholds but above the state's 
minor NSR thresholds. One result of granting Maine's petition to remove 
some portions of the state from the OTR is that PSD will apply to major 
sources and BACT will be required for NOX and VOC emissions 
in all NSR permitting actions (major and minor) for sources located in 
those areas removed from the OTR. However, existing LAER requirements 
contained in existing permits located in areas that would no longer be 
part of the OTR (i.e., in final permits issued prior to the effective 
date of Maine's petition, should it be granted) would remain in effect. 
In addition to LAER, another requirement that is unique to NNSR is the 
requirement for new major sources and major modifications at existing 
sources to secure offsetting emissions reductions. Such emissions 
offsets must be obtained from ``the same source or

[[Page 23318]]

other sources in the same nonattainment area,'' except that the state 
may allow emissions offsets derived from another nonattainment area if 
``(A) the other area has an equal or higher nonattainment 
classification than the area in which the source is located and (B) 
emissions from such other area contribute to a violation of the 
national ambient air quality standard in the nonattainment area in 
which the source is located.'' 42 U.S.C. 7502(c). For ozone, the CAA 
requires that the amount of emissions offsets obtained increase with 
the severity of the area's nonattainment status. Areas within the OTR 
are treated as ``moderate.'' Thus, the emissions offsets that must be 
obtained in Maine is calculated by applying a ratio of 1.15 to 1 for 
NOX and VOC.\44\
---------------------------------------------------------------------------

    \44\ Chapter 113 section (3)(E)(1)(c)(ii).
---------------------------------------------------------------------------

    If the EPA grants Maine's petition to remove parts of the state 
from the OTR, new stationary sources locating in the affected area 
would be subject to PSD for NOX and VOC if the source is 
major under Maine's definition by virtue of it having a potential to 
emit 100 tons per year or more of any regulated NSR pollutant and 40 
tons per year or more of NOX and VOCs. If triggered, PSD 
permitting requirements for NOX and/or VOC would include the 
application of BACT and a demonstration that the allowable emissions 
increase(s) would not cause or contribute to a violation of the ozone 
NAAQS. Modifications at existing major stationary sources that result 
in an increase of 40 tons per year or more of NOX or VOC by 
itself and on a net basis would be subject to the same PSD permitting 
requirements. New non-major sources and minor modifications at existing 
sources (major and non-major) would be subject to the minor NSR 
permitting requirements for NOX and/or VOC, including BACT, 
if emissions exceed the applicable minor NSR thresholds discussed 
previously.
    Based on the foregoing, if the EPA finalizes its proposal to grant 
Maine's petition, some sources and modifications located in the part of 
the state no longer in the OTR would be subject to BACT instead of LAER 
for NOX and VOC. While there are not always significant 
differences between the level of control determined under BACT and 
LAER, BACT determinations must consider factors, such as energy, 
environmental, and economic impacts and other costs, that are not 
considered for LAER determinations. Because of differences between BACT 
and LAER, in individual determinations, it is not necessarily the case 
that LAER is always more stringent than BACT.
    Some sources previously required to obtain emissions offsets under 
the NNSR program would not be required to do so under the PSD or minor 
NSR program. While the NNSR emissions offsets requirement would no 
longer apply in the portion of the state to be removed from the OTR, 
under PSD, new major stationary sources and major modifications would 
be required to demonstrate that proposed emissions increases will not 
cause or contribute to a violation of the ozone NAAQS. For projects 
subject to minor NSR, Maine's minor NSR program also requires at 
Chapter 115 section (7)(C)(1) air quality impact analyses of 
NOX for new minor sources and minor modifications at 
existing sources if emissions exceed 50 tons per year of 
NOX. Maine also has discretionary authority to require an 
ambient air quality analysis for sources that emit less 50 tons per 
year of NOX (see Chapter 115 subsection (7)(B)(3)).
    Procedurally, granting Maine's petition would not materially alter 
opportunities for public involvement, as Maine's PSD and NNSR pre-
construction regulations contain procedures for the opportunity for 
public participation in the permitting process whether a stationary 
source is subject to minor NSR, PSD, or NNSR permitting regulations.
ii. Maine I/M Program
    Section 184(b)(1)(A) of the Act requires certain areas in the OTR 
to adopt and implement an inspection and maintenance program meeting 
EPA's enhanced I/M performance standard. The EPA's I/M rule was 
established on November 5, 1992 (57 FR 52950). The EPA made significant 
revisions to the I/M rule on September 18, 1995 (60 FR 48035) and on 
July 25, 1996 (61 FR 39036). The I/M regulation was codified at 40 CFR 
part 51, subpart S, and requires States subject to the I/M requirement 
to submit an I/M SIP revision that includes all necessary legal 
authority and the items specified in 40 CFR 51.350 through 51.373. 
Maine is subject to the OTR requirements for a vehicle I/M program in 
the Portland, Maine area.
    Maine's I/M program provides for the implementation of I/M in 
Maine's Cumberland County, which includes the Portland area, beginning 
on January 1, 1999. Maine implemented an annual, test and repair I/M 
program, which the state designed to meet the requirements of the EPA's 
performance standard and other requirements contained in the federal I/
M rule. Testing is overseen by the Department of Public Safety (DPS) 
and implemented by individual garages in the existing safety inspection 
network. Aspects of the Maine I/M program include: Antitampering 
testing for catalytic converters on 1983 and newer light duty vehicles 
and trucks, gas cap pressure testing on 1974 and newer vehicles, and 
On-Board Diagnostic (OBD2) checks (beginning in January 2000), 
enforcement by the existing windshield safety inspection stickers, 
requirements for testing convenience, quality assurance, data 
collection, no cost waivers, reporting, test equipment and test 
procedure specifications, public information and consumer protection, 
inspector training and certification, penalties against inspectors 
which perform faulty inspections, and emissions recall enforcement. 
However, Maine did not meet the enhanced I/M requirements due to the 
lack of a required registration-based enforcement program. The EPA 
determined that even though Maine's I/M program did not meet the 
requirements for the EPA's enhanced I/M program, the program 
contributes to air quality improvement. The EPA also determined that an 
enhanced I/M program in Maine would not significantly contribute to the 
attainment of the 1-hour ozone standard anywhere in the OTR. (66 FR 
1871, January 10, 2001). If the EPA grants Maine's 176A petition, the 
impacts on Maine's I/M program would likely be minimal. Cumberland 
County is the only county in Maine with an I/M program, and, as noted 
previously, only six towns in Cumberland County are included in the 
portion of the state requesting to opt out of the OTR, and those six 
towns contain only five percent of the county's population. Even if the 
state were to request to remove I/M requirements for those six towns in 
the future, subject to CAA section 110(l), the majority of Cumberland 
County would remain in the OTR and will continue to implement Maine's 
existing I/M program.
iii. Stage II Refueling Vapor Recovery
    Stage II refueling vapor recovery systems and vehicle onboard 
refueling vapor recovery (ORVR) systems were initially both required by 
the 1990 Amendments to the CAA. Section 182(b)(3) requires ozone 
nonattainment areas classified Moderate and above to implement Stage II 
refueling vapor recovery programs. Under CAA section 184(b)(2), states 
in the OTR were also required to implement Stage II or comparable 
measures. CAA section 202(a)(6) required EPA to promulgate

[[Page 23319]]

regulations for ORVR for light duty vehicles (passenger cars).\45\
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    \45\ The EPA adopted these requirements in 1994. ORVR equipment 
has been phased in for new passenger vehicles beginning with model 
year 1998 and starting with model year 2001 for light-duty trucks 
and most heavy-duty gasoline powered vehicles. ORVR equipment has 
been installed on nearly all new gasoline- powered light-duty 
vehicles, light-duty trucks, and heavy-duty vehicles since 2006. 
During the phase-in of ORVR controls, Stage II provided volatile 
organic compound (VOC) reductions in ozone nonattainment areas and 
certain attainment areas of the OTR. Congress recognized that ORVR 
systems and Stage II vapor recovery systems would eventually become 
largely redundant technologies and provided authority to the EPA to 
allow states to remove Stage II vapor recovery programs from their 
SIPs after the EPA finds that ORVR is in ``widespread use.''
---------------------------------------------------------------------------

    Maine's SIP approved Stage II program requirements were codified in 
Maine's Chapter 118, Gasoline Dispensing Facilities Vapor Control.\46\ 
Maine's rule required gasoline dispensing facilities located in the 
counties of York, Cumberland, and Sagadahoc to install Stage II vapor 
recovery systems. With the widespread use of ORVR, Maine's revised 
Chapter 118 decommissioning Stage II vapor recovery requirements was 
approved into the SIP. (82 FR 32480, July 14, 2017). EPA's proposed 
grant of Maine's 176A petition would have no impact on Stage II 
requirements due to the decommissioning of the program in Maine.
---------------------------------------------------------------------------

    \46\ 61 FR 53636 October 15, 1996
---------------------------------------------------------------------------

iv. RACT
    Sections 182(b)(2) and 184(b)(1)(B) of the CAA require states with 
ozone nonattainment areas that are classified as Moderate or above, as 
well as areas in the OTR, to submit a SIP revision requiring the 
implementation of RACT for sources covered by a control techniques 
guideline (CTG) and for all major sources of VOCs and NOX. A 
CTG is a document issued by the EPA which establishes a ``presumptive 
norm'' for RACT for a specific VOC source category. RACT is defined as 
the lowest emissions limitation that a particular source is capable of 
meeting by the application of control technology that is reasonably 
available considering technological and economic feasibility. The CTGs 
usually identify a particular control level, which the EPA recommends 
as being RACT. States in the OTR are required to address RACT for the 
source categories covered by CTGs through adoption of rules as part of 
the SIP, and they are also required to adopt RACT for major sources of 
VOCs (50 tpy) and major sources of NOX (100 tpy) even if a 
CTG does not apply.
    The EPA has approved: The Maine VOC RACT for the 1-hour ozone 
standard (65 FR 20753, April 18, 2000) and (67 FR 35441, May 20, 2002); 
the Maine NOX RACT for the 1-hour ozone standard (60 FR 
66755, December 26, 1995, and 67 FR 57154, September 9, 2002); the 
Maine VOC and NOX RACT for the 1997 8-hour ozone standard 
(77 FR 30216, May 22, 2012); and the Maine VOC RACT for the 2008 8-hour 
ozone standard (84 FR 38558, August 7, 2019). We note that Maine's 
petition includes a commitment to implement existing RACT and to adopt 
future RACT requirements statewide, for both the 2015 ozone NAAQS and 
any future ozone NAAQS. The state's deadline to submit a RACT SIP for 
the 2015 ozone standard was August 3, 2020 (83 FR 62998, 63001, 
December 6, 2018).
    Notwithstanding the stated intention in Maine's petition to adopt 
statewide RACT for the 2015 ozone standard and to adopt statewide RACT 
for future ozone NAAQS, in this case the EPA does not believe it is 
necessary for the state to adopt such additional RACT to meet the test 
set forth in CAA section 176A(a)(2). The state's technical 
demonstration submitted with its petition, which shows that Maine does 
not and will not contribute to nonattainment or interfere with 
maintenance anywhere in the OTR, does not reflect the adoption of 
statewide RACT to address the 2015 ozone NAAQS (or additional RACT 
controls for future standards). As stated in CAA section 176A(a)(2), 
and discussed in Section III.C of this notice, the Administrator may 
exercise the OTR removal provision ``whenever the Administrator has 
reason to believe'' that additional OTR controls will not contribute 
significantly to attainment in the OTR. The EPA interprets this 
language to permit the Administrator to consider whether to approve a 
state's petition even if the state has not met, and the EPA has not 
fully approved, all applicable OTR requirements to date.
    If finalized, the EPA's grant of Maine's petition would terminate 
Maine's federal obligation under CAA section 184 to adopt further RACT 
requirements for the portion of the state no longer in the OTR, 
including for the 2015 ozone NAAQS. The portion of the state remaining 
in the OTR, however, remains obligated under CAA section 184 to submit 
a SIP revision to address both NOX and VOC RACT for the 2015 
ozone NAAQS, and for any future ozone NAAQS so long as the area remains 
in the OTR. Of course, the state could still elect to adopt SIP-
strengthening control measures (either at the state level or as SIP-
strengthening measures) for sources in the portion of the state that is 
no longer in the OTR, even if that portion of the state is not 
obligated to meet RACT under section 184(b). In addition, if the EPA's 
grant is finalized, the state could seek to relax or remove RACT 
requirements in its SIP for the portion of the state no longer in the 
OTR, but as noted in section III.C, any such revision would be required 
to satisfy a demonstration of noninterference under section 110(l).

V. The EPA's Technical Assessment of the Maine CAA Section 176A 
Petition

A. Description of the Technical Analysis Included in the Maine CAA 
Section 176A Petition

    As noted previously, the Maine petition included detailed technical 
analyses for VOC and NOX emissions in the state, including 
an analysis of whether emissions from Maine impact other areas in the 
OTR. The state uses the following techniques to analyze those emissions 
and their impacts: Back trajectories using the National Oceanic and 
Atmospheric Administration (NOAA) Air Resources Laboratory's Hybrid 
Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model \47\ 
and photochemical source apportionment modeling. These analyses are in 
keeping with steps 1 and 2 of the interstate transport framework 
described in Section III.C of this document. In both the trajectory and 
modeling analyses, air quality monitors that either measured elevated 
ozone concentrations or were projected to have design values that 
violated the NAAQS or struggled to maintain the NAAQS were identified 
(step 1). Maine then used HYSPLIT trajectory model and photochemical 
source apportionment modeling to identify whether Maine contributed to 
those problem monitors (step 2). Further inspection of Maine's 
emissions trends supports the conclusions made using the HYSPLIT and 
source apportionment modeling analyses.
---------------------------------------------------------------------------

    \47\ For more information about HYSPLIT please refer to the 
following document by Roland R. Draxler and G.D. Hess: Description 
of the HYSPLIT 4 Modeling System. (See http://www.arl.noaa.gov/documents/reports/arl-224.pdf.)
---------------------------------------------------------------------------

    The air trajectories used by Maine DEP are four-dimensional 
representations of the path an air parcel follows, in time, based on 
surface and upper-level meteorological data during the day of and days 
prior to the measured exceedances. A back trajectory, as used by Maine 
DEP in this case, represents the path an air parcel takes to reach a 
specific point in time and space. Using the HYSPLIT back trajectory 
model, Maine DEP air quality meteorologists analyzed back

[[Page 23320]]

trajectories for 989 days from the 2016 through 2018 ozone seasons at 
monitoring locations in the OTR with current 8-hour ozone design values 
exceeding the 2015 ozone NAAQS of 70 ppb. For each such exceedance day 
at each monitoring site, 48-hour back trajectories originating from 10 
and 500 meters above ground level were created for the hour of the 
maximum hourly ozone. As noted above in Section IV.A of this document, 
for this analysis, the ``NAM 12 km pressure'' gridded meteorological 
data was used, except for August 27, 2016, when no meteorological data 
was available so the ``NAM 12 km hybrid'' meteorology was used for that 
day. The trajectories were then plotted to determine the origin of the 
air on high-ozone days. The Maine petition included maps showing that 
none of the 989 10m back trajectories traveled over the state of Maine 
(Figure 7 of Maine petition) and that 2 out of the 989 back 
trajectories at 500 meters traversed the far western edge of Maine 
(Figure 9 of Maine petition). Maine asserted that the fact that air 
parcels at violating monitors on days greater than 70 ppb did not 
originate from or traverse the state of Maine in the preceding 48 hours 
provided support for the conclusion that Maine did not contribute 
significantly to ozone nonattainment at those violating monitors.
    In addition, Maine provided similar HYSPLIT back trajectory 
analyses for Maine monitors (none of which recorded design values above 
the NAAQS) on days when maximum daily 8-hour average ozone 
concentrations exceeded 70 ppb. These back trajectories showed that 
most of the air parcels traveling to the Maine monitors on those high-
ozone days were transported from the south and southwest direction 
along the coast of Maine and primarily traversed either offshore 
locations or portions of the state that will remain in the OTR.
    In addition to the trajectory analysis discussed above, Maine's 
petition referenced the EPA's photochemical modeling for the CSAPR 
Update for the 2008 ozone NAAQS and results from the interstate 
transport modeling for the 2015 ozone NAAQS.48 49 The EPA's 
CSAPR Update modeling projected ozone design values in 2017 and modeled 
each state's total contribution to that value for the 2008 8-hr ozone 
NAAQS of 75 ppb. The same was done for the 2015 8-hour ozone NAAQS of 
70 ppb interstate transport assessment for the year 2023. The maximum 
contribution from the entire state of Maine to any monitoring site in 
any other state in the OTR is 0.47 ppb in New Hampshire, based on the 
EPA's contribution modeling for 2017, and 0.13 ppb in Massachusetts 
based on the EPA's contribution modeling for 2023. The modeling further 
estimated that the maximum total contribution of the state of Maine to 
any monitors projected to have nonattainment or maintenance problems 
within the OTR was 0.01 ppb for both 2017 and 2023.
---------------------------------------------------------------------------

    \48\ See Air Quality Modeling Technical Support Document for the 
Final CSAPR Update, available in the docket for this action or at 
https://www.epa.gov/airmarkets/air-quality-modeling-technical-support-document-final-cross-state-air-pollution-rule.
    \49\ See Information on the Interstate Transport State 
Implementation Plan Submissions for the 2015 Ozone National Ambient 
Air Quality Standards under Clean Air Act Section 
110(a)(2)(D)(i)(I), March 27, 2018, available in the docket for this 
action or at https://www.epa.gov/interstate-air-pollution-transport/interstate-air-pollution-transport-memos-and-notices.
---------------------------------------------------------------------------

    Finally, Maine provided graphical figures showing NOX 
and VOC historical emissions trends as well as projected emissions 
trends out to 2028. These data include statewide emissions inventories 
as well as a break-out of emissions for the Portland and Midcoast Ozone 
areas. Furthermore, the petition provides emissions data broken out 
into four source types (on-road vehicles, non-road equipment, point 
sources and nonpoint sources), and shows that emissions of on-road 
vehicles, which were the largest source of anthropogenic NOX 
emissions in the state of Maine between 2005 and 2014, are expected to 
continue to decline. Maine's emissions analysis also shows that 
nonpoint and non-road sectors were the largest sources of VOC emissions 
in the state of Maine in 2005 and 2014.

B. The EPA's Technical Assessment of the Maine Section 176A Petition

    As noted in Section III.C of this document, the EPA views the 
inquiry under CAA section 176A(a)(2) as necessitating the 
identification of current and future air quality problems in the OTR, 
determining whether the petitioning area is significantly contributing 
to those problems, and examining whether removal of the petitioning 
area from the OTR will significantly contribute to nonattainment or 
maintenance problems in the future. The EPA proposes to find that the 
technical analyses submitted by Maine in its CAA section 176A petition, 
in conjunction with additional analysis performed by the EPA, support 
Maine's petition to remove a portion of the state from the OTR.
    The HYSPLIT analyses performed by Maine and summarized in Section 
V.A. are a technically sound and appropriate method to support showing 
the potential (or lack of potential) of an area to contribute to high-
ozone values at a downwind location. This type of trajectory analysis 
is a commonly used method to examine potential source-receptor 
relationships based on air transport patterns. In this case, we agree 
that the analysis provided by Maine showed that in 2016-2018 air 
parcels containing high-ozone concentrations at violating monitors in 
the OTR rarely if ever originated from Maine.
    The EPA's ozone source apportionment air quality modeling conducted 
for the CSAPR Update, and the EPA's interstate transport modeling for 
the 2015 ozone NAAQS both further support the conclusions that (1) 
Maine has historically contributed below the one percent threshold of 
0.70 ppb to all other states and contributes well below that threshold 
to any receptors currently \50\ identified as having a potential 
nonattainment or maintenance problem, and that (2) the state will 
continue to contribute below that threshold to all other states in the 
OTR in the future. Further, EPA's analysis demonstrates that there are 
no ozone nonattainment or maintenance receptors in Maine, either now, 
or going forward, even if the petition is granted. The EPA's source 
apportionment modeling employs enhanced techniques that track the 
formation and transport of ozone from specific emissions sources and 
calculates the contribution of sources and precursors to ozone for 
individual receptor locations. The strength of the photochemical model 
source apportionment technique is that all modeled ozone at a given 
receptor location in the modeling domain is tracked back to specific 
sources of emissions and boundary conditions to fully characterize 
culpable sources.
---------------------------------------------------------------------------

    \50\ Based on official 2019 ozone design values (https://www.epa.gov/air-trends/air-quality-design-values).
---------------------------------------------------------------------------

    Data from the contribution analysis are summarized within Table 2 
of the state's submittal, showing the maximum modeled ozone 
contribution from Maine's emissions in other OTR states. The data 
indicate a maximum modeled impact of only 0.47 ppb in 2017 in New 
Hampshire, which is well below the one percent threshold of 0.70 ppb 
used to establish significant contribution linkages, and, additionally, 
occurs in a state, New Hampshire, that is attaining and projected to 
continue to attain both the 2008 and 2015 ozone NAAQS. The EPA also 
examined its 2023 contribution modeling to identify the highest 
contribution from Maine to any

[[Page 23321]]

projected nonattainment or maintenance receptor in another state. The 
data show that the highest contribution from Maine to a nonattainment 
or maintenance receptor in another state based on modeling is 0.01 ppb 
in 2017 at the receptor in Greenwich, Fairfield County, CT and 0.01 ppb 
in 2023 at the receptor in Babylon, Suffolk County, NY (site 
361030002). This amount (i.e., 0.01 ppb) is well below a 0.70 ppb 
(i.e., one percent of the 2015 NAAQS) contribution threshold.
    Second, Maine's HYSPLIT back trajectory analyses included an 
evaluation of Maine monitors that indicates that high-ozone 
concentrations in the state are largely due to out-of-state 
contributions. Maine's petition provides back trajectory air parcel 
paths from monitors in the state on days when those monitors recorded 
maximum daily 8-hour average ozone concentrations that exceeded the 
2015 NAAQS. The air parcels traveling to these Maine monitors on those 
high-ozone days did not typically traverse the portions of Maine 
proposed to be removed from the OTR. Rather, the air parcels were 
carried by winds from the south and southwest and, on most days 
traversed either marine locations or the portion of the state that will 
remain in the OTR (i.e., the Portland and Midcoast areas).
    We also propose to find that the NOX and VOC historical 
emissions trends and projected future emissions trends information to 
2023 and 2028 provided in Maine's submittal further support removal of 
the petitioning area from the OTR. VOC and NOX emissions in 
Maine have declined since 2005 and are expected to continue to decline 
into the future. The historical and projected downward trend is driven, 
in large part, by emissions reductions from the point source and on-
road mobile source categories.
    Maine's documentation shows that statewide point source emissions 
of NOX and VOC decreased 51 and 45 percent, respectively 
from 2005 to 2016. Maine's projections predict that NOX and 
VOC emissions will continue to decrease into the future. For example, 
Maine's analysis of statewide emissions shows NOX and VOC 
reductions of 46 and 34 percent respectively between 2011 and 2023. 
These reductions are primarily coming from on-road vehicles, EGU point 
sources, and non-road equipment. The reduction in emissions from on-
road vehicles is largely the result of several mobile source programs 
such as the Tier 3 emissions and gasoline standards for light-duty 
vehicles, the mobile source air toxics rule and the heavy-duty highway 
vehicle rule \51\ which have resulted in newer vehicles having lower 
emissions than vehicles previously sold in the U.S. As more of those 
newer, lower-emitting vehicles replace older, higher-emitting vehicles, 
mobile source emissions are expected to further decline. It should be 
noted that none of these regulations were affected by the recent 
finalization of ``The Safer Affordable Fuel-Efficient (SAFE) Vehicles 
Rule Part One: One National Program'' \52\ or ``The Safer Affordable 
Fuel-Efficient (SAFE) Vehicles Rule for Model Years 2021-2026 Passenger 
Cars and Light Trucks,'' \53\ which addressed greenhouse gas emissions 
standards, corporate average fuel economy standards and the ability of 
states to adopt greenhouse gas standards and related regulations for 
light-duty vehicles.
---------------------------------------------------------------------------

    \51\ E.g., Control of Air Pollution From Motor Vehicles: Tier 3 
Motor Vehicle Emission and Fuel Standards, 79 FR 23414 (April 28, 
2014); Control of Hazardous Air Pollutants From Mobile Sources, 72 
FR 8428 (February 26, 2007); and Control of Air Pollution from New 
Motor Vehicles: Heavy-Duty Engine and Vehicle Standards and Highway 
Diesel Fuel Sulfur Control Requirements, 66 FR 5002 (January 18, 
2001).
    \52\ 84 FR 51310 (September 27, 2019).
    \53\ 85 FR 24174 (April 30, 2020).
---------------------------------------------------------------------------

    We note that the source apportionment air quality modeling cited by 
Maine has been at issue in various legal challenges to EPA actions. See 
Wisconsin v. EPA, 938 F.3d 303 (D.C. Cir. 2019); Maryland v. EPA, 958 
F.3d 1185 (D.C. Cir. 2020). In both of those cases, the D.C. Circuit 
remanded the EPA's final actions to the extent that those actions 
failed to require upwind states to eliminate their significant 
contributions in accordance with the attainment dates found in CAA 
section 181 by which downwind states must come into compliance with the 
relevant NAAQS. Wisconsin, 938 F.3d at 313; Maryland, at 958 F.3d at 
1203-04. The two statutory provisions at issue in Wisconsin and 
Maryland--i.e., CAA section 110(a)(2)(D)(i)(I) (the good neighbor 
provision), and CAA section 126, which by its terms incorporates the 
substantive requirements of the good neighbor provision--require that 
the states and the EPA consider statutory downwind attainment dates in 
determining the deadline by which upwind significant contribution must 
be eliminated. See CAA section 110(a)(2)(D)(i)(I) (State plans must 
``contain adequate provisions prohibiting, consistent with the 
provisions of this subchapter,'' emissions which will contribute 
significantly to nonattainment in, or interfere with maintenance by, 
any other state with respect to any such NAAQS) (emphasis added). By 
contrast, CAA section 176A has no reference to other provisions of the 
CAA, the attainment dates in title I, or a defined timeframe for 
analysis. See CAA section 176A(a)(1) and (2) (the Administrator may add 
any state whenever he has reason to believe that the interstate 
transport of air pollutants . . . ``significantly contributes to a 
violation of the standard in the transport region''; and the 
Administrator may remove any state from the region whenever he has 
reason to believe that the OTR control of emissions in the state will 
not ``significantly contribute to the attainment of the standard in any 
area in the region'') (emphasis added). In addition, while the selected 
analytic year for the EPA's air quality modeling can in some instances 
have a material impact on determining whether receptors are in 
attainment and/or whether areas are linked to those receptors, this is 
not the case for Maine. Maine has not been linked as contributing above 
the one percent of the NAAQS threshold to downwind nonattainment or 
maintenance based on air quality contribution modeling performed by the 
EPA for either the 2008 or 2015 ozone NAAQS. We, therefore, do not 
think that the legal issues identified with the EPA's air quality 
modeling in Wisconsin and Maryland, which were solely concerned with 
the relationship of that modeling to the statutory attainment dates, 
undermines Maine's use of that modeling in its petition. Moreover, we 
note that the D.C. Circuit upheld the EPA's air quality modeling with 
respect to the many technical challenges raised by petitioners in the 
Wisconsin case. 938 F.3d at 323-331.
    The EPA, therefore, proposes to find that granting Maine's petition 
to remove portions of the state from the OTR, and the resulting changes 
in the extent of emissions controls that would result (discussed in 
detail in section IV), will not significantly contribute to 
nonattainment or maintenance problems for any area in the OTR. As 
noted, the emissions trends in Maine indicate continued declines in 
emissions of ozone precursors associated with on-the-books emissions 
controls, and do not depend on any new emissions limitations that would 
be driven by OTR control requirements under CAA section 184(b). In 
addition, Maine's highest modeled contribution to any receptor in the 
OTR that is expected to struggle with attainment or maintenance of the 
2015 ozone NAAQS is only 0.01 ppb. This suggests that the ozone 
contribution from anthropogenic ozone precursor emissions in Maine 
would

[[Page 23322]]

have to increase by a factor of 70 for Maine to potentially contribute 
above the one percent threshold to an existing or projected 
nonattainment or maintenance problem in the OTR. This observation is 
made merely to provide an indication of the general magnitude of 
emissions increases from Maine that would be needed in order for 
existing trends in improving air quality to be halted and reversed to 
the extent that such an increase may create new air quality problems 
closer to, or within, Maine. The EPA believes that granting the 
petition would not result in such a change in emissions resulting from 
either removal of existing emissions controls or unchecked growth in 
new source emissions. The historic emissions trends in Maine, the CAA's 
section 110(l) anti-backsliding provisions for SIP revisions and the 
new source PSD permitting provisions that would apply in the removed 
portion of the state provide assurances that a substantial increase in 
emissions is highly unlikely, and would represent an unprecedented 
reversal in overall emissions reductions for any state, whether in the 
OTR or not.
    Further, as discussed in Section IV of this document, the primary 
change in the ozone control regime that will result from granting the 
petition is to switch from NNSR requirements for new sources of 
emissions to PSD NSR requirements, in the areas of the state to be 
removed. This change would mean the application of BACT rather than 
LAER controls for new sources and removal of the requirement to obtain 
emissions offsets. This change would be primarily impactful for VOCs 
rather than NOX emissions. This is because Maine has, in the 
past, obtained NOX waivers under CAA section 182(f), which 
suspended NNSR requirements (and RACT requirements) for major 
NOX emissions sources. During the periods when Maine was 
under NOX waivers, its NOX emissions and ozone 
levels generally continued to decline. Thus, while Maine has not 
obtained a NOX waiver for the 2015 ozone NAAQS, this does 
not affect the EPA's overall assessment that the switch to PSD NSR from 
NNSR would not be expected to result in a substantial change from 
historical levels of NOX emissions. With respect to VOC 
emissions, any new source growth under PSD NSR rather than NNSR cannot 
be reasonably anticipated to cause such a dramatic increase in 
emissions as to result in new air quality problems where none currently 
exist--where such improvements in Maine's air quality have primarily 
been driven by reductions in out-of-state emissions and non-OTR related 
control strategies such as federal mobile source standards.
    Additionally, Maine's petition shows that a substantial portion of 
Maine's anthropogenic VOC and NOX emissions occur in the 
Portland and Midcoast ozone areas, which Maine is not proposing to 
remove from the OTR.\54\ The fact that the petition shows contributions 
from the entire state to be insignificant, while a substantial portion 
of those emissions originate from areas that will remain in the OTR 
makes an even stronger case that there is reason to believe that 
granting Maine's petition will not result in significant contributions 
to ozone violations anywhere in the OTR.
---------------------------------------------------------------------------

    \54\ While Maine's petition does not provide precise emissions 
for the Portland and Midcoast ozone areas, comparing Figures 14 and 
15 in the petition with the state's overall emissions in Figures 12 
and 13 shows that in 2005, NOX emissions in the Portland 
and Midcoast areas accounted for over half of the state's overall 
NOX emissions and VOC emissions from those areas 
comprised about half of the state's overall VOC emissions. 
Similarly, in 2014, NOX emissions from the Portland and 
Midcoast ozone areas accounted for about half of the state's overall 
NOX emissions, and the areas' VOC emissions accounted for 
a little under half of the state's overall VOC emissions. We note 
that the figures in the petition provide Maine's total emissions in 
tons/day while the figures regarding the Portland and Midcoast areas 
provide emissions in summer tons/day, but the EPA believes the 
overall state emissions are likely summer tons/day because such 
reporting would be in line with the EPA's longstanding guidance to 
states on how to prepare emission inventories for ozone NAAQS.
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VI. The EPA's Proposed Action on the Maine CAA Section 176A Petition

    Based on the information discussed in this notice, the EPA is 
proposing to grant Maine's CAA section 176A petition. In consideration 
of monitoring data, emissions data, technical demonstrations (including 
air quality monitoring and trajectory analyses), and the potential 
impact to air quality control regimes, the EPA proposes to find that 
additional OTR controls under CAA section 184(b) for the portion of the 
state that Maine is seeking to remove from the OTR will not 
significantly contribute to attainment of any ozone NAAQS in any area 
of the OTR. In support of this proposed conclusion, the EPA finds that 
removing the requested areas from the OTR will not result in emissions 
changes that would significantly contribute to nonattainment or 
interfere with maintenance of any ozone NAAQS in any area of the OTR. 
All areas of the state proposed for removal from the OTR have been 
designated in attainment of the ozone NAAQS since 2004, and the entire 
state of Maine has been designated as in attainment with the ozone 
NAAQS since 2007. Technical demonstrations from Maine's HYSPLIT back 
trajectory analysis, the EPA's ozone source apportionment modeling, and 
emissions trends all support the assertion that emissions from the 
areas requested to be removed from the OTR will not significantly 
contribute to nonattainment or maintenance problems in any area in the 
OTR, either within or outside the state of Maine, in the foreseeable 
future. Furthermore, removing those areas from the OTR will not result 
in unchecked relaxation of existing NOX and VOC controls 
included in Maine's SIP or revoke permitted emissions limits at 
existing facilities. Any future revisions to Maine's SIP would be 
subject to CAA section 110(l) anti-backsliding demonstrations. 
Accordingly, the EPA proposes to grant the CAA section 176A petition 
filed by the state of Maine.

VII. Judicial Review and Determinations Under Sections 307(b)(1) and 
307(d) of the CAA

    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action, if finalized, must be filed in the 
United States Court of Appeals for the appropriate circuit within 60 
days of publication of any final action. Filing a petition for 
reconsideration by the Administrator of this rule, if finalized, will 
not affect the finality of the rule for the purposes of judicial review 
nor will it extend the time within which a petition for judicial review 
may be filed, and shall not postpone the effectiveness of such rule or 
action. The Administrator of the EPA hereby determines that this action 
is subject to CAA section 307(d), as authorized by section 
307(d)(1)(V).

List of Subjects in 40 CFR Part 81

    Environmental protection, Air pollution control, Particulate 
matter.

    Statutory Authority: 42 U.S.C. 7401 et seq.

Michael S. Regan,
Administrator.

    For the reasons stated in the preamble, title 40, chapter I of the 
Code of Federal Regulations is proposed to be amended as follows:

PART 81--DESIGNATIONS OF AREAS FOR AIR QUALITY PLANNING PURPOSES

0
1. The authority citation for part 81 continues to read as follows:

    Authority: 42 U.S.C. 7401, et. seq.

0
2. Part 81 is amended by adding new Subpart E to read as follows:

[[Page 23323]]

Subpart E--Identification of Interstate Transport Regions

Sec.
81.455 Scope.
81.457 Ozone Transport Region.

Sec.  81.455  Scope.

    This subpart identifies interstate transport regions established 
for national ambient air quality standards pursuant to section 184 or 
section 176A of the Clean Air Act.

Sec.  81.457  Ozone Transport Region.

    Except as provided in paragraph (a), the Ozone Transport Region is 
comprised of the areas identified by Congress under 42 U.S.C. 7511c(a). 
The EPA Administrator removed a portion of Maine from the Ozone 
Transport Region, by rule, in response to a petition submitted by Maine 
under section 176A(a).

(a) Ozone Transport Region Boundary

    As of [30 DAYS AFTER PUBLICATION OF FINAL ACTION IN FEDERAL 
REGISTER], the boundary for the Ozone Transport Region consists of the 
entire states of Connecticut, Delaware, Maryland, Massachusetts, New 
Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and 
Vermont; [PORTIONS OF MAINE INCLUDED IN OTR AS IDENTIFIED AT [CITATION 
xxx]]; and the Consolidated Metropolitan Statistical Area 
[DOCUMENTATION DATE] that includes the District of Columbia and the 
following counties and cities in Virginia: Arlington County, Fairfax 
County, Loudoun County, Prince William County, Strafford County, 
Alexandria City, Fairfax City, Falls Church City, Manassas City, and 
Manassas Park City.

(b) Applicability

    As of [30 DAYS AFTER PUBLICATION OF FINAL ACTION IN FEDERAL 
REGISTER], the provisions of 42 U.S.C. 7511c will no longer be 
applicable in the following areas of Maine: [PORTIONS OF MAINE TO BE 
REMOVED FROM OTR AS IDENTIFIED AT [CITATION xxx]].

[FR Doc. 2021-08825 Filed 4-30-21; 8:45 am]
BILLING CODE 6560-50-P