[Federal Register Volume 89, Number 7 (Wednesday, January 10, 2024)]
[Proposed Rules]
[Pages 1482-1505]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-28573]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

EPA-R01-OAR-2023-0185; FRL-11616-01-R1]


Approval and Promulgation of Air Quality Implementation Plans; 
Massachusetts; Regional Haze State Implementation Plan for the Second 
Implementation Period

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve the Regional Haze State Implementation Plan (SIP) revision 
submitted by Massachusetts on July 22, 2021, as satisfying applicable 
requirements under the Clean Air Act (CAA) and EPA's Regional Haze Rule 
for the program's second implementation period. Massachusetts' SIP 
submission addresses the requirement that states must periodically 
revise their long-term strategies for making reasonable progress 
towards the national goal of preventing any future, and remedying any 
existing, anthropogenic impairment of visibility, including regional 
haze, in mandatory Class I Federal areas. The SIP submission also 
addresses other applicable requirements for the second implementation 
period of the regional haze program. The EPA is taking this action 
pursuant to sections 110 and 169A of the Clean Air Act.

DATES: Written comments must be received on or before February 9, 2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R01-
OAR-2023-0185 at https://www.regulations.gov. For comments submitted at 
Regulations.gov, follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
Regulations.gov. For either manner of submission, 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, please contact 
the person identified in the FOR FURTHER INFORMATION CONTACT section. 
For the full EPA public comment policy, information about CBI or 
multimedia submissions, and general guidance on making effective 
comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: David Mackintosh, U.S. Environmental 
Protection Agency, Region 1, Air Quality Branch, 5 Post Office Square--
Suite 100, (Mail code 5-MO), Boston, MA 02109-3912, at 617-918-1584, or 
by email at <a href="/cdn-cgi/l/email-protection#db96bab8b0b2b5afb4a8b3f59fbaadb2bf9bbeabbaf5bcb4ad"><span class="__cf_email__" data-cfemail="4a072b292123243e253922640e2b3c232e0a2f3a2b642d253c">[email protected]</span></a>.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. What action is the EPA proposing?
II. Background and Requirements for Regional Haze Plans
    A. Regional Haze Background
    B. Roles of Agencies in Addressing Regional Haze
III. Requirements for Regional Haze Plans for the Second 
Implementation Period
    A. Identification of Class I Areas
    B. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress
    C. Long-Term Strategy for Regional Haze
    D. Reasonable Progress Goals
    E. Monitoring Strategy and Other State Implementation Plan 
Requirements
    F. Requirements for Periodic Reports Describing Progress Towards 
the Reasonable Progress Goals
    G. Requirements for State and Federal Land Manager Coordination
IV. The EPA's Evaluation of Massachusetts' Regional Haze Submission 
for the Second Implementation Period
    A. Background on Massachusetts' First Implementation Period SIP 
Submission
    B. Massachusetts' Second Implementation Period SIP Submission 
and the EPA's Evaluation
    C. Identification of Class I Areas
    D. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress
    E. Long-Term Strategy for Regional Haze
    a. Massachusetts' Response to the Six MANE-VU Asks

[[Page 1483]]

    b. The EPA's Evaluation of Massachusetts' Response to the Six 
MANE-VU Asks and Compliance With Sec.  51.308(f)(2)(i)
    c. Additional Long-Term Strategy Requirements
    F. Reasonable Progress Goals
    G. Monitoring Strategy and Other Implementation Plan 
Requirements
    H. Requirements for Periodic Reports Describing Progress Towards 
the Reasonable Progress Goals
    I. Requirements for State and Federal Land Manager Coordination
V. Proposed Action
VI. Incorporation by Reference
VII. Statutory and Executive Order Reviews

I. What action is the EPA proposing?

    On July 22, 2021, supplemented on June 15, 2022, the Massachusetts 
Department of Environmental Protection (MassDEP) submitted a revision 
to its SIP to address regional haze for the second implementation 
period. MassDEP made this SIP submission to satisfy the requirements of 
the CAA's regional haze program pursuant to CAA sections 169A and 169B 
and 40 CFR 51.308. The EPA is proposing to find that the Massachusetts 
regional haze SIP submission for the second implementation period meets 
the applicable statutory and regulatory requirements and thus proposes 
to approve Massachusetts' submission into its SIP.

II. Background and Requirements for Regional Haze Plans

A. Regional Haze Background

    In the 1977 CAA Amendments, Congress created a program for 
protecting visibility in the nation's mandatory Class I Federal areas, 
which include certain national parks and wilderness areas.\1\ CAA 169A. 
The CAA establishes as a national goal the ``prevention of any future, 
and the remedying of any existing, impairment of visibility in 
mandatory class I Federal areas which impairment results from manmade 
air pollution.'' CAA 169A(a)(1). The CAA further directs the EPA to 
promulgate regulations to assure reasonable progress toward meeting 
this national goal. CAA 169A(a)(4). On December 2, 1980, the EPA 
promulgated regulations to address visibility impairment in mandatory 
Class I Federal areas (hereinafter referred to as ``Class I areas'') 
that is ``reasonably attributable'' to a single source or small group 
of sources. (45 FR 80084, December 2, 1980). These regulations, 
codified at 40 CFR 51.300 through 51.307, represented the first phase 
of the EPA's efforts to address visibility impairment. In 1990, 
Congress added section 169B to the CAA to further address visibility 
impairment, specifically, impairment from regional haze. CAA 169B. The 
EPA promulgated the Regional Haze Rule (RHR), codified at 40 CFR 
51.308,\2\ on July 1, 1999. (64 FR 35714, July 1, 1999). These regional 
haze regulations are a central component of the EPA's comprehensive 
visibility protection program for Class I areas.
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    \1\ Areas statutorily designated as mandatory Class I Federal 
areas consist of national parks exceeding 6,000 acres, wilderness 
areas and national memorial parks exceeding 5,000 acres, and all 
international parks that were in existence on August 7, 1977. CAA 
162(a). There are 156 mandatory Class I areas. The list of areas to 
which the requirements of the visibility protection program apply is 
in 40 CFR part 81, subpart D.
    \2\ In addition to the generally applicable regional haze 
provisions at 40 CFR 51.308, the EPA also promulgated regulations 
specific to addressing regional haze visibility impairment in Class 
I areas on the Colorado Plateau at 40 CFR 51.309. The latter 
regulations are applicable only for specific jurisdictions' regional 
haze plans submitted no later than December 17, 2007, and thus are 
not relevant here.
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    Regional haze is visibility impairment that is produced by a 
multitude of anthropogenic sources and activities which are located 
across a broad geographic area and that emit pollutants that impair 
visibility. Visibility impairing pollutants include fine and coarse 
particulate matter (PM) (e.g., sulfates, nitrates, organic carbon, 
elemental carbon, and soil dust) and their precursors (e.g., sulfur 
dioxide (SO<INF>2</INF>), nitrogen oxides (NO<INF>X</INF>), and, in 
some cases, volatile organic compounds (VOC) and ammonia 
(NH<INF>3</INF>)). Fine particle precursors react in the atmosphere to 
form fine particulate matter (PM<INF>2.5</INF>), which impairs 
visibility by scattering and absorbing light. Visibility impairment 
reduces the perception of clarity and color, as well as visible 
distance.\3\
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    \3\ There are several ways to measure the amount of visibility 
impairment, i.e., haze. One such measurement is the deciview, which 
is the principal metric used by the RHR. Under many circumstances, a 
change in one deciview will be perceived by the human eye to be the 
same on both clear and hazy days. The deciview is unitless. It is 
proportional to the logarithm of the atmospheric extinction of 
light, which is the perceived dimming of light due to its being 
scattered and absorbed as it passes through the atmosphere. 
Atmospheric light extinction (b\ext\) is a metric used to for 
expressing visibility and is measured in inverse megameters (Mm-1). 
The EPA's Guidance on Regional Haze State Implementation Plans for 
the Second Implementation Period (``2019 Guidance'') offers the 
flexibility for the use of light extinction in certain cases. Light 
extinction can be simpler to use in calculations than deciviews, 
since it is not a logarithmic function. See, e.g., 2019 Guidance at 
16, 19, https://www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period, The EPA Office of 
Air Quality Planning and Standards, Research Triangle Park (August 
20, 2019). The formula for the deciview is 10 ln (b\ext\)/10 Mm-1). 
40 CFR 51.301.
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    To address regional haze visibility impairment, the 1999 RHR 
established an iterative planning process that requires both states in 
which Class I areas are located and states ``the emissions from which 
may reasonably be anticipated to cause or contribute to any impairment 
of visibility'' in a Class I area to periodically submit SIP revisions 
to address such impairment. CAA 169A(b)(2); \4\ see also 40 CFR 
51.308(b), (f) (establishing submission dates for iterative regional 
haze SIP revisions); (64 FR at 35768, July 1, 1999). Under the CAA, 
each SIP submission must contain ``a long-term (ten to fifteen years) 
strategy for making reasonable progress toward meeting the national 
goal,'' CAA 169A(b)(2)(B); the initial round of SIP submissions also 
had to address the statutory requirement that certain older, larger 
sources of visibility impairing pollutants install and operate the best 
available retrofit technology (BART). CAA 169A(b)(2)(A); 40 CFR 
51.308(d), (e). States' first regional haze SIPs were due by December 
17, 2007, 40 CFR 51.308(b), with subsequent SIP submissions containing 
updated long-term strategies originally due July 31, 2018, and every 
ten years thereafter. (64 FR at 35768, July 1, 1999). The EPA 
established in the 1999 RHR that all states either have Class I areas 
within their borders or ``contain sources whose emissions are 
reasonably anticipated to contribute to regional haze in a Class I 
area''; therefore, all states must submit regional haze SIPs.\5\ Id. at 
35721.
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    \4\ The RHR expresses the statutory requirement for states to 
submit plans addressing out-of-state class I areas by providing that 
states must address visibility impairment ``in each mandatory Class 
I Federal area located outside the State that may be affected by 
emissions from within the State.'' 40 CFR 51.308(d), (f).
    \5\ In addition to each of the fifty states, the EPA also 
concluded that the Virgin Islands and District of Columbia must also 
submit regional haze SIPs because they either contain a Class I area 
or contain sources whose emissions are reasonably anticipated to 
contribute regional haze in a Class I area. See 40 CFR 51.300(b), 
(d)(3).
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    Much of the focus in the first implementation period of the 
regional haze program, which ran from 2007 through 2018, was on 
satisfying states' BART obligations. First implementation period SIPs 
were additionally required to contain long-term strategies for making 
reasonable progress toward the national visibility goal, of which BART 
is one component. The core required elements for the first 
implementation period SIPs (other than BART) are laid out in 40 CFR 
51.308(d). Those provisions required that states containing Class I 
areas establish reasonable progress goals (RPGs) that are measured in 
deciviews and reflect the anticipated visibility conditions at

[[Page 1484]]

the end of the implementation period including from implementation of 
states' long-term strategies. The first planning period RPGs were 
required to provide for an improvement in visibility for the most 
impaired days over the period of the implementation plan and ensure no 
degradation in visibility for the least impaired days over the same 
period. In establishing the RPGs for any Class I area in a state, the 
state was required to consider four statutory factors: the costs of 
compliance, the time necessary for compliance, the energy and non-air 
quality environmental impacts of compliance, and the remaining useful 
life of any potentially affected sources. CAA 169A(g)(1); 40 CFR 
51.308(d)(1).
    States were also required to calculate baseline (using the five-
year period of 2000-2004) and natural visibility conditions (i.e., 
visibility conditions without anthropogenic visibility impairment) for 
each Class I area, and to calculate the linear rate of progress needed 
to attain natural visibility conditions, assuming a starting point of 
baseline visibility conditions in 2004 and ending with natural 
conditions in 2064. This linear interpolation is known as the uniform 
rate of progress (URP) and is used as a tracking metric to help states 
assess the amount of progress they are making towards the national 
visibility goal over time in each Class I area.\6\ 40 CFR 
51.308(d)(1)(i)(B), (d)(2). The 1999 RHR also provided that States' 
long-term strategies must include the ``enforceable emissions 
limitations, compliance, schedules, and other measures as necessary to 
achieve the reasonable progress goals.'' 40 CFR 51.308(d)(3). In 
establishing their long-term strategies, states are required to consult 
with other states that also contribute to visibility impairment in a 
given Class I area and include all measures necessary to obtain their 
shares of the emission reductions needed to meet the RPGs. 40 CFR 
51.308(d)(3)(i), (ii). Section 51.308(d) also contains seven additional 
factors states must consider in formulating their long-term strategies, 
40 CFR 51.308(d)(3)(v), as well as provisions governing monitoring and 
other implementation plan requirements. 40 CFR 51.308(d)(4). Finally, 
the 1999 RHR required states to submit periodic progress reports--SIP 
revisions due every five years that contain information on states' 
implementation of their regional haze plans and an assessment of 
whether anything additional is needed to make reasonable progress, see 
40 CFR 51.308(g), (h)--and to consult with the Federal Land Manager(s) 
\7\ (FLMs) responsible for each Class I area according to the 
requirements in CAA 169A(d) and 40 CFR 51.308(i).
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    \6\ EPA established the URP framework in the 1999 RHR to provide 
``an equitable analytical approach'' to assessing the rate of 
visibility improvement at Class I areas across the country. The 
start point for the URP analysis is 2004 and the endpoint was 
calculated based on the amount of visibility improvement that was 
anticipated to result from implementation of existing CAA programs 
over the period from the mid-1990s to approximately 2005. Assuming 
this rate of progress would continue into the future, EPA determined 
that natural visibility conditions would be reached in 60 years, or 
2064 (60 years from the baseline starting point of 2004). However, 
EPA did not establish 2064 as the year by which the national goal 
must be reached. 64 FR at 35731-32. That is, the URP and the 2064 
date are not enforceable targets, but are rather tools that ``allow 
for analytical comparisons between the rate of progress that would 
be achieved by the state's chosen set of control measures and the 
URP.'' (82 FR 3078, 3084, January 10, 2017).
    \7\ The EPA's regulations define ``Federal Land Manager'' as 
``the Secretary of the department with authority over the Federal 
Class I area (or the Secretary's designee) or, with respect to 
Roosevelt-Campobello International Park, the Chairman of the 
Roosevelt-Campobello International Park Commission.'' 40 CFR 51.301.
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    On January 10, 2017, the EPA promulgated revisions to the RHR, (82 
FR 3078, January 10, 2017), that apply for the second and subsequent 
implementation periods. The 2017 rulemaking made several changes to the 
requirements for regional haze SIPs to clarify States' obligations and 
streamline certain regional haze requirements. The revisions to the 
regional haze program for the second and subsequent implementation 
periods focused on the requirement that States' SIPs contain long-term 
strategies for making reasonable progress towards the national 
visibility goal. The reasonable progress requirements as revised in the 
2017 rulemaking (referred to here as the 2017 RHR Revisions) are 
codified at 40 CFR 51.308(f). Among other changes, the 2017 RHR 
Revisions adjusted the deadline for States to submit their second 
implementation period SIPs from July 31, 2018, to July 31, 2021, 
clarified the order of analysis and the relationship between RPGs and 
the long-term strategy, and focused on making visibility improvements 
on the days with the most anthropogenic visibility impairment, as 
opposed to the days with the most visibility impairment overall. The 
EPA also revised requirements of the visibility protection program 
related to periodic progress reports and FLM consultation. The specific 
requirements applicable to second implementation period regional haze 
SIP submissions are addressed in detail below.
    The EPA provided guidance to the states for their second 
implementation period SIP submissions in the preamble to the 2017 RHR 
Revisions as well as in subsequent, stand-alone guidance documents. In 
August 2019, the EPA issued ``Guidance on Regional Haze State 
Implementation Plans for the Second Implementation Period'' (``2019 
Guidance'').\8\ On July 8, 2021, the EPA issued a memorandum containing 
``Clarifications Regarding Regional Haze State Implementation Plans for 
the Second Implementation Period'' (``2021 Clarifications Memo'').\9\ 
Additionally, the EPA further clarified the recommended procedures for 
processing ambient visibility data and optionally adjusting the URP to 
account for international anthropogenic and prescribed fire impacts in 
two technical guidance documents: the December 2018 ``Technical 
Guidance on Tracking Visibility Progress for the Second Implementation 
Period of the Regional Haze Program'' (``2018 Visibility Tracking 
Guidance''),\10\ and the June 2020 ``Recommendation for the Use of 
Patched and Substituted Data and Clarification of Data Completeness for 
Tracking Visibility Progress for the Second Implementation Period of 
the Regional Haze Program'' and associated Technical Addendum (``2020 
Data Completeness Memo'').\11\
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    \8\ Guidance on Regional Haze State Implementation Plans for the 
Second Implementation Period. https://www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period. The EPA Office of Air Quality Planning and 
Standards, Research Triangle Park (August 20, 2019).
    \9\ Clarifications Regarding Regional Haze State Implementation 
Plans for the Second Implementation Period. https://www.epa.gov/system/files/documents/2021-07/clarifications-regarding-regional-haze-state-implementation-plans-for-the-second-implementation-period.pdf. The EPA Office of Air Quality Planning and Standards, 
Research Triangle Park (July 8, 2021).
    \10\ Technical Guidance on Tracking Visibility Progress for the 
Second Implementation Period of the Regional Haze Program. https://www.epa.gov/visibility/technical-guidance-tracking-visibility-progress-second-implementation-period-regional. The EPA Office of 
Air Quality Planning and Standards, Research Triangle Park. 
(December 20, 2018).
    \11\ Recommendation for the Use of Patched and Substituted Data 
and Clarification of Data Completeness for Tracking Visibility 
Progress for the Second Implementation Period of the Regional Haze 
Program. https://www.epa.gov/visibility/memo-and-technical-addendum-ambient-data-usage-and-completeness-regional-haze-program. The EPA 
Office of Air Quality Planning and Standards, Research Triangle Park 
(June 3, 2020).
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    As previously explained in the 2021 Clarifications Memo, EPA 
intends the second implementation period of the regional haze program 
to secure meaningful reductions in visibility impairing pollutants that 
build on the significant progress states have achieved to date. The 
Agency also recognizes that analyses regarding reasonable progress

[[Page 1485]]

are state-specific and that, based on states' and sources' individual 
circumstances, what constitutes reasonable reductions in visibility 
impairing pollutants will vary from state-to-state. While there exist 
many opportunities for states to leverage both ongoing and upcoming 
emission reductions under other CAA programs, the Agency expects states 
to undertake rigorous reasonable progress analyses that identify 
further opportunities to advance the national visibility goal 
consistent with the statutory and regulatory requirements. See 
generally 2021 Clarifications Memo. This is consistent with Congress's 
determination that a visibility protection program is needed in 
addition to the CAA's National Ambient Air Quality Standards and 
Prevention of Significant Deterioration programs, as further emission 
reductions may be necessary to adequately protect visibility in Class I 
areas throughout the country.\12\
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    \12\ See, e.g., H.R. Rep No. 95-294 at 205 (``In determining how 
to best remedy the growing visibility problem in these areas of 
great scenic importance, the committee realizes that as a matter of 
equity, the national ambient air quality standards cannot be revised 
to adequately protect visibility in all areas of the country.''), 
(``the mandatory class I increments of [the PSD program] do not 
adequately protect visibility in class I areas'').
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B. Roles of Agencies in Addressing Regional Haze

    Because the air pollutants and pollution affecting visibility in 
Class I areas can be transported over long distances, successful 
implementation of the regional haze program requires long-term, 
regional coordination among multiple jurisdictions and agencies that 
have responsibility for Class I areas and the emissions that impact 
visibility in those areas. In order to address regional haze, states 
need to develop strategies in coordination with one another, 
considering the effect of emissions from one jurisdiction on the air 
quality in another. Five regional planning organizations (RPOs),\13\ 
which include representation from state and tribal governments, the 
EPA, and FLMs, were developed in the lead-up to the first 
implementation period to address regional haze. RPOs evaluate technical 
information to better understand how emissions from State and Tribal 
land impact Class I areas across the country, pursue the development of 
regional strategies to reduce emissions of particulate matter and other 
pollutants leading to regional haze, and help states meet the 
consultation requirements of the RHR.
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    \13\ RPOs are sometimes also referred to as ``multi-
jurisdictional organizations,'' or MJOs. For the purposes of this 
notice, the terms RPO and MJO are synonymous.
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    The Mid-Atlantic/Northeast Visibility Union (MANE-VU), one of the 
five RPOs described above, is a collaborative effort of state 
governments, tribal governments, and various Federal agencies 
established to initiate and coordinate activities associated with the 
management of regional haze, visibility, and other air quality issues 
in the Mid-Atlantic and Northeast corridor of the United States. Member 
states and tribal governments (listed alphabetically) include 
Connecticut, Delaware, the District of Columbia, Maine, Maryland, 
Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, 
Penobscot Indian Nation, Rhode Island, St. Regis Mohawk Tribe, and 
Vermont. The Federal partner members of MANE-VU are EPA, U.S. National 
Parks Service (NPS), U.S. Fish and Wildlife Service (FWS), and U.S. 
Forest Service (USFS).

III. Requirements for Regional Haze Plans for the Second Implementation 
Period

    Under the CAA and EPA's regulations, all 50 states, the District of 
Columbia, and the U.S. Virgin Islands are required to submit regional 
haze SIPs satisfying the applicable requirements for the second 
implementation period of the regional haze program by July 31, 2021. 
Each state's SIP must contain a long-term strategy for making 
reasonable progress toward meeting the national goal of remedying any 
existing and preventing any future anthropogenic visibility impairment 
in Class I areas. CAA 169A(b)(2)(B). To this end, Sec.  51.308(f) lays 
out the process by which states determine what constitutes their long-
term strategies, with the order of the requirements in Sec.  
51.308(f)(1) through (f)(3) generally mirroring the order of the steps 
in the reasonable progress analysis \14\ and (f)(4) through (f)(6) 
containing additional, related requirements. Broadly speaking, a state 
first must identify the Class I areas within the state and determine 
the Class I areas outside the state in which visibility may be affected 
by emissions from the state. These are the Class I areas that must be 
addressed in the state's long-term strategy. See 40 CFR 51.308(f), 
(f)(2). For each Class I area within its borders, a state must then 
calculate the baseline, current, and natural visibility conditions for 
that area, as well as the visibility improvement made to date and the 
URP. See 40 CFR 51.308(f)(1). Each state having a Class I area and/or 
emissions that may affect visibility in a Class I area must then 
develop a long-term strategy that includes the enforceable emission 
limitations, compliance schedules, and other measures that are 
necessary to make reasonable progress in such areas. A reasonable 
progress determination is based on applying the four factors in CAA 
section 169A(g)(1) to sources of visibility-impairing pollutants that 
the state has selected to assess for controls for the second 
implementation period. See 40 CFR 51.308(f)(2). Additionally, as 
further explained below, the RHR at 40 CFR 51.308(f)(2)(iv) separately 
provides five ``additional factors'' \15\ that states must consider in 
developing their long-term strategies. A state evaluates potential 
emission reduction measures for those selected sources and determines 
which are necessary to make reasonable progress. Those measures are 
then incorporated into the state's long-term strategy. After a state 
has developed its long-term strategy, it then establishes RPGs for each 
Class I area within its borders by modeling the visibility impacts of 
all reasonable progress controls at the end of the second 
implementation period, i.e., in 2028, as well as the impacts of other 
requirements of the CAA. The RPGs include reasonable progress controls 
not only for sources in the state in which the Class I area is located, 
but also for sources in other states that contribute to visibility 
impairment in that area. The RPGs are then compared to the baseline 
visibility conditions and the URP to ensure that progress is being made 
towards the statutory goal of preventing any future and remedying any 
existing anthropogenic visibility impairment in Class I areas. 40 CFR 
51.308(f)(2)-(3).
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    \14\ EPA explained in the 2017 RHR Revisions that we were 
adopting new regulatory language in 40 CFR 51.308(f) that, unlike 
the structure in 51.308(d), ``tracked the actual planning 
sequence.'' (82 FR 3091, January 10, 2017).
    \15\ The five ``additional factors'' for consideration in 
section 51.308(f)(2)(iv) are distinct from the four factors listed 
in CAA section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states 
must consider and apply to sources in determining reasonable 
progress.
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    In addition to satisfying the requirements at 40 CFR 51.308(f) 
related to reasonable progress, the regional haze SIP revisions for the 
second implementation period must address the requirements in Sec.  
51.308(g)(1) through (5) pertaining to periodic reports describing 
progress towards the RPGs, 40 CFR 51.308(f)(5), as well as requirements 
for FLM consultation that apply to all visibility protection SIPs and 
SIP revisions. 40 CFR 51.308(i).
    A state must submit its regional haze SIP and subsequent SIP 
revisions to the EPA according to the requirements applicable to all 
SIP revisions under the CAA and EPA's regulations. See CAA

[[Page 1486]]

169(b)(2); CAA 110(a). Upon EPA approval, a SIP is enforceable by the 
Agency and the public under the CAA. If EPA finds that a state fails to 
make a required SIP revision, or if the EPA finds that a state's SIP is 
incomplete or if disapproves the SIP, the Agency must promulgate a 
federal implementation plan (FIP) that satisfies the applicable 
requirements. CAA 110(c)(1).

A. Identification of Class I Areas

    The first step in developing a regional haze SIP is for a state to 
determine which Class I areas, in addition to those within its borders, 
``may be affected'' by emissions from within the state. In the 1999 
RHR, the EPA determined that all states contribute to visibility 
impairment in at least one Class I area, 64 FR at 35720-22, and 
explained that the statute and regulations lay out an ``extremely low 
triggering threshold'' for determining ``whether States should be 
required to engage in air quality planning and analysis as a 
prerequisite to determining the need for control of emissions from 
sources within their State.'' Id. at 35721.
    A state must determine which Class I areas must be addressed by its 
SIP by evaluating the total emissions of visibility impairing 
pollutants from all sources within the state. While the RHR does not 
require this evaluation to be conducted in any particular manner, EPA's 
2019 Guidance provides recommendations for how such an assessment might 
be accomplished, including by, where appropriate, using the 
determinations previously made for the first implementation period. 
2019 Guidance at 8-9. In addition, the determination of which Class I 
areas may be affected by a state's emissions is subject to the 
requirement in 40 CFR 51.308(f)(2)(iii) to ``document the technical 
basis, including modeling, monitoring, cost, engineering, and emissions 
information, on which the State is relying to determine the emission 
reduction measures that are necessary to make reasonable progress in 
each mandatory Class I Federal area it affects.''

B. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress

    As part of assessing whether a SIP submission for the second 
implementation period is providing for reasonable progress towards the 
national visibility goal, the RHR contains requirements in Sec.  
51.308(f)(1) related to tracking visibility improvement over time. The 
requirements of this subsection apply only to states having Class I 
areas within their borders; the required calculations must be made for 
each such Class I area. EPA's 2018 Visibility Tracking Guidance \16\ 
provides recommendations to assist states in satisfying their 
obligations under Sec.  51.308(f)(1)--specifically, in developing 
information on baseline, current, and natural visibility conditions, 
and in making optional adjustments to the URP to account for the 
impacts of international anthropogenic emissions and prescribed fires. 
See 82 FR at 3103-05.
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    \16\ The 2018 Visibility Tracking Guidance references and relies 
on parts of the 2003 Tracking Guidance: ``Guidance for Tracking 
Progress Under the Regional Haze Rule,'' which can be found at 
https://www3.epa.gov/ttnamti1/files/ambient/visible/tracking.pdf.
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    The RHR requires tracking of visibility conditions on two sets of 
days: the clearest and the most impaired days. Visibility conditions 
for both sets of days are expressed as the average deciview index for 
the relevant five-year period (the period representing baseline or 
current visibility conditions). The RHR provides that the relevant sets 
of days for visibility tracking purposes are the 20% clearest (the 20% 
of monitored days in a calendar year with the lowest values of the 
deciview index) and 20% most impaired days (the 20% of monitored days 
in a calendar year with the highest amounts of anthropogenic visibility 
impairment).\17\ 40 CFR 51.301. A state must calculate visibility 
conditions for both the 20% clearest and 20% most impaired days for the 
baseline period of 2000-2004 and the most recent five-year period for 
which visibility monitoring data are available (representing current 
visibility conditions). 40 CFR 51.308(f)(1)(i), (iii). States must also 
calculate natural visibility conditions for the clearest and most 
impaired days,\18\ by estimating the conditions that would exist on 
those two sets of days absent anthropogenic visibility impairment. 40 
CFR 51.308(f)(1)(ii). Using all these data, states must then calculate, 
for each Class I area, the amount of progress made since the baseline 
period (2000-2004) and how much improvement is left to achieve in order 
to reach natural visibility conditions.
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    \17\ This notice also refers to the 20% clearest and 20% most 
anthropogenically impaired days as the ``clearest'' and ``most 
impaired'' or ``most anthropogenically impaired'' days, 
respectively.
    \18\ The RHR at 40 CFR 51.308(f)(1)(ii) contains an error 
related to the requirement for calculating two sets of natural 
conditions values. The rule says ``most impaired days or the 
clearest days'' where it should say ``most impaired days and 
clearest days.'' This is an error that was intended to be corrected 
in the 2017 RHR Revisions but did not get corrected in the final 
rule language. This is supported by the preamble text at 82 FR 3098: 
``In the final version of 40 CFR 51.308(f)(1)(ii), an occurrence of 
``or'' has been corrected to ``and'' to indicate that natural 
visibility conditions for both the most impaired days and the 
clearest days must be based on available monitoring information.''
---------------------------------------------------------------------------

    Using the data for the set of most impaired days only, states must 
plot a line between visibility conditions in the baseline period and 
natural visibility conditions for each Class I area to determine the 
URP--the amount of visibility improvement per year, measured in 
deciviews, that would need to be achieved during each implementation 
period in order to achieve natural visibility conditions by the end of 
2064. The URP is used in later steps of the reasonable progress 
analysis for informational purposes and to provide a non-enforceable 
benchmark against which to assess a Class I area's rate of visibility 
improvement.\19\ Additionally, in the 2017 RHR Revisions, the EPA 
provided states the option of proposing to adjust the endpoint of the 
URP to account for impacts of anthropogenic sources outside the United 
States and/or impacts of certain types of wildland prescribed fires. 
These adjustments, which must be approved by the EPA, are intended to 
avoid any perception that states should compensate for impacts from 
international anthropogenic sources and to give states the flexibility 
to determine that limiting the use of wildland-prescribed fire is not 
necessary for reasonable progress. 82 FR 3107 footnote 116.
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    \19\ Being on or below the URP is not a ``safe harbor''; i.e., 
achieving the URP does not mean that a Class I area is making 
``reasonable progress'' and does not relieve a state from using the 
four statutory factors to determine what level of control is needed 
to achieve such progress. See, e.g., 82 FR at 3093.
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    EPA's 2018 Visibility Tracking Guidance can be used to help satisfy 
the 40 CFR 51.308(f)(1) requirements, including in developing 
information on baseline, current, and natural visibility conditions, 
and in making optional adjustments to the URP. In addition, the 2020 
Data Completeness Memo provides recommendations on the data 
completeness language referenced in Sec.  51.308(f)(1)(i) and provides 
updated natural conditions estimates for each Class I area.

C. Long-Term Strategy for Regional Haze

    The core component of a regional haze SIP submission is a long-term 
strategy that addresses regional haze in each Class I area within a 
state's borders and each Class I area that may be affected by emissions 
from the state. The long-term strategy ``must include the enforceable 
emissions limitations, compliance schedules, and other

[[Page 1487]]

measures that are necessary to make reasonable progress, as determined 
pursuant to (f)(2)(i) through (iv).'' 40 CFR 51.308(f)(2). The amount 
of progress that is ``reasonable progress'' is based on applying the 
four statutory factors in CAA section 169A(g)(1) in an evaluation of 
potential control options for sources of visibility impairing 
pollutants, which is referred to as a ``four-factor'' analysis. The 
outcome of that analysis is the emission reduction measures that a 
particular source or group of sources needs to implement in order to 
make reasonable progress towards the national visibility goal. See 40 
CFR 51.308(f)(2)(i). Emission reduction measures that are necessary to 
make reasonable progress may be either new, additional control measures 
for a source, or they may be the existing emission reduction measures 
that a source is already implementing. See 2019 Guidance at 43; 2021 
Clarifications Memo at 8-10. Such measures must be represented by 
``enforceable emissions limitations, compliance schedules, and other 
measures'' (i.e., any additional compliance tools) in a state's long-
term strategy in its SIP. 40 CFR 51.308(f)(2).
    Section 51.308(f)(2)(i) provides the requirements for the four-
factor analysis. The first step of this analysis entails selecting the 
sources to be evaluated for emission reduction measures; to this end, 
the RHR requires states to consider ``major and minor stationary 
sources or groups of sources, mobile sources, and area sources'' of 
visibility impairing pollutants for potential four-factor control 
analysis. 40 CFR 51.308(f)(2)(i). A threshold question at this step is 
which visibility impairing pollutants will be analyzed. As EPA 
previously explained, consistent with the first implementation period, 
EPA generally expects that each state will analyze at least 
SO<INF>2</INF> and NO<INF>X</INF> in selecting sources and determining 
control measures. See 2019 Guidance at 12, 2021 Clarifications Memo at 
4. A state that chooses not to consider at least these two pollutants 
should demonstrate why such consideration would be unreasonable. 2021 
Clarifications Memo at 4.
    While states have the option to analyze all sources, the 2019 
Guidance explains that ``an analysis of control measures is not 
required for every source in each implementation period,'' and that 
``[s]electing a set of sources for analysis of control measures in each 
implementation period is . . . consistent with the Regional Haze Rule, 
which sets up an iterative planning process and anticipates that a 
state may not need to analyze control measures for all its sources in a 
given SIP revision.'' 2019 Guidance at 9. However, given that source 
selection is the basis of all subsequent control determinations, a 
reasonable source selection process ``should be designed and conducted 
to ensure that source selection results in a set of pollutants and 
sources the evaluation of which has the potential to meaningfully 
reduce their contributions to visibility impairment.'' 2021 
Clarifications Memo at 3.
    EPA explained in the 2021 Clarifications Memo that each state has 
an obligation to submit a long-term strategy that addresses the 
regional haze visibility impairment that results from emissions from 
within that state. Thus, source selection should focus on the in-state 
contribution to visibility impairment and be designed to capture a 
meaningful portion of the state's total contribution to visibility 
impairment in Class I areas. A state should not decline to select its 
largest in-state sources on the basis that there are even larger out-
of-state contributors. 2021 Clarifications Memo at 4.\20\
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    \20\ Similarly, in responding to comments on the 2017 RHR 
Revisions EPA explained that ``[a] state should not fail to address 
its many relatively low-impact sources merely because it only has 
such sources and another state has even more low-impact sources and/
or some high impact sources.'' Responses to Comments on Protection 
of Visibility: Amendments to Requirements for State Plans; Proposed 
Rule (81 FR 26942, May 4, 2016) at 87-88.
---------------------------------------------------------------------------

    Thus, while states have discretion to choose any source selection 
methodology that is reasonable, whatever choices they make should be 
reasonably explained. To this end, 40 CFR 51.308(f)(2)(i) requires that 
a state's SIP submission include ``a description of the criteria it 
used to determine which sources or groups of sources it evaluated.'' 
The technical basis for source selection, which may include methods for 
quantifying potential visibility impacts such as emissions divided by 
distance metrics, trajectory analyses, residence time analyses, and/or 
photochemical modeling, must also be appropriately documented, as 
required by 40 CFR 51.308(f)(2)(iii).
    Once a state has selected the set of sources, the next step is to 
determine the emissions reduction measures for those sources that are 
necessary to make reasonable progress for the second implementation 
period.\21\ This is accomplished by considering the four factors--``the 
costs of compliance, the time necessary for compliance, and the energy 
and non-air quality environmental impacts of compliance, and the 
remaining useful life of any existing source subject to such 
requirements.'' CAA 169A(g)(1). The EPA has explained that the four-
factor analysis is an assessment of potential emission reduction 
measures (i.e., control options) for sources; ``use of the terms 
`compliance' and `subject to such requirements' in section 169A(g)(1) 
strongly indicates that Congress intended the relevant determination to 
be the requirements with which sources would have to comply in order to 
satisfy the CAA's reasonable progress mandate.'' 82 FR at 3091. Thus, 
for each source it has selected for four-factor analysis,\22\ a state 
must consider a ``meaningful set'' of technically feasible control 
options for reducing emissions of visibility impairing pollutants. Id. 
at 3088. The 2019 Guidance provides that ``[a] state must reasonably 
pick and justify the measures that it will consider, recognizing that 
there is no statutory or regulatory requirement to consider all 
technically feasible measures or any particular measures. A range of 
technically feasible measures available to reduce emissions would be 
one way to justify a reasonable set.'' 2019 Guidance at 29.
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    \21\ The CAA provides that, ``[i]n determining reasonable 
progress there shall be taken into consideration'' the four 
statutory factors. CAA 169A(g)(1). However, in addition to four-
factor analyses for selected sources, groups of sources, or source 
categories, a state may also consider additional emission reduction 
measures for inclusion in its long-term strategy, e.g., from other 
newly adopted, on-the-books, or on-the-way rules and measures for 
sources not selected for four-factor analysis for the second 
planning period.
    \22\ ``Each source'' or ``particular source'' is used here as 
shorthand. While a source-specific analysis is one way of applying 
the four factors, neither the statute nor the RHR requires states to 
evaluate individual sources. Rather, states have ``the flexibility 
to conduct four-factor analyses for specific sources, groups of 
sources or even entire source categories, depending on state policy 
preferences and the specific circumstances of each state.'' 82 FR at 
3088. However, not all approaches to grouping sources for four-
factor analysis are necessarily reasonable; the reasonableness of 
grouping sources in any particular instance will depend on the 
circumstances and the manner in which grouping is conducted. If it 
is feasible to establish and enforce different requirements for 
sources or subgroups of sources, and if relevant factors can be 
quantified for those sources or subgroups, then states should make a 
separate reasonable progress determination for each source or 
subgroup. 2021 Clarifications Memo at 7-8.
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    EPA's 2021 Clarifications Memo provides further guidance on what 
constitutes a reasonable set of control options for consideration: ``A 
reasonable four-factor analysis will consider the full range of 
potentially reasonable options for reducing emissions.'' 2021 
Clarifications Memo at 7. In addition to add-on controls and other 
retrofits (i.e., new emission reduction measures for sources), EPA 
explained that states should generally analyze efficiency improvements 
for sources' existing measures as control options in their four-factor 
analyses, as in many cases

[[Page 1488]]

such improvements are reasonable given that they typically involve only 
additional operation and maintenance costs. Additionally, the 2021 
Clarifications Memo provides that states that have assumed a higher 
emission rate than a source has achieved or could potentially achieve 
using its existing measures should also consider lower emission rates 
as potential control options. That is, a state should consider a 
source's recent actual and projected emission rates to determine if it 
could reasonably attain lower emission rates with its existing 
measures. If so, the state should analyze the lower emission rate as a 
control option for reducing emissions. 2021 Clarifications Memo at 7. 
The EPA's recommendations to analyze potential efficiency improvements 
and achievable lower emission rates apply to both sources that have 
been selected for four-factor analysis and those that have forgone a 
four-factor analysis on the basis of existing ``effective controls.'' 
See 2021 Clarifications Memo at 5, 10.
    After identifying a reasonable set of potential control options for 
the sources it has selected, a state then collects information on the 
four factors with regard to each option identified. The EPA has also 
explained that, in addition to the four statutory factors, states have 
flexibility under the CAA and RHR to reasonably consider visibility 
benefits as an additional factor alongside the four statutory 
factors.\23\ The 2019 Guidance provides recommendations for the types 
of information that can be used to characterize the four factors (with 
or without visibility), as well as ways in which states might 
reasonably consider and balance that information to determine which of 
the potential control options is necessary to make reasonable progress. 
See 2019 Guidance at 30-36. The 2021 Clarifications Memo contains 
further guidance on how states can reasonably consider modeled 
visibility impacts or benefits in the context of a four-factor 
analysis. 2021 Clarifications Memo at 12-13, 14-15. Specifically, EPA 
explained that while visibility can reasonably be used when comparing 
and choosing between multiple reasonable control options, it should not 
be used to summarily reject controls that are reasonable given the four 
statutory factors. 2021 Clarifications Memo at 13. Ultimately, while 
states have discretion to reasonably weigh the factors and to determine 
what level of control is needed, Sec.  51.308(f)(2)(i) provides that a 
state ``must include in its implementation plan a description of . . . 
how the four factors were taken into consideration in selecting the 
measure for inclusion in its long-term strategy.''
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    \23\ See, e.g., Responses to Comments on Protection of 
Visibility: Amendments to Requirements for State Plans; Proposed 
Rule (81 FR 26942, May 4, 2016), Docket Number EPA-HQ-OAR-2015-0531, 
U.S. Environmental Protection Agency at 186; 2019 Guidance at 36-37.
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    As explained above, Sec.  51.308(f)(2)(i) requires states to 
determine the emission reduction measures for sources that are 
necessary to make reasonable progress by considering the four factors. 
Pursuant to Sec.  51.308(f)(2), measures that are necessary to make 
reasonable progress towards the national visibility goal must be 
included in a state's long-term strategy and in its SIP.\24\ If the 
outcome of a four-factor analysis is a new, additional emission 
reduction measure for a source, that new measure is necessary to make 
reasonable progress towards remedying existing anthropogenic visibility 
impairment and must be included in the SIP. If the outcome of a four-
factor analysis is that no new measures are reasonable for a source, 
continued implementation of the source's existing measures is generally 
necessary to prevent future emission increases and thus to make 
reasonable progress towards the second part of the national visibility 
goal: preventing future anthropogenic visibility impairment. See CAA 
169A(a)(1). That is, when the result of a four-factor analysis is that 
no new measures are necessary to make reasonable progress, the source's 
existing measures are generally necessary to make reasonable progress 
and must be included in the SIP. However, there may be circumstances in 
which a state can demonstrate that a source's existing measures are not 
necessary to make reasonable progress. Specifically, if a state can 
demonstrate that a source will continue to implement its existing 
measures and will not increase its emission rate, it may not be 
necessary to have those measures in the long-term strategy in order to 
prevent future emission increases and future visibility impairment. 
EPA's 2021 Clarifications Memo provides further explanation and 
guidance on how states may demonstrate that a source's existing 
measures are not necessary to make reasonable progress. See 2021 
Clarifications Memo at 8-10. If the state can make such a 
demonstration, it need not include a source's existing measures in the 
long-term strategy or its SIP.
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    \24\ States may choose to, but are not required to, include 
measures in their long-term strategies beyond just the emission 
reduction measures that are necessary for reasonable progress. See 
2021 Clarifications Memo at 16. For example, states with smoke 
management programs may choose to submit their smoke management 
plans to EPA for inclusion in their SIPs but are not required to do 
so. See, e.g., 82 FR at 3108-09 (requirement to consider smoke 
management practices and smoke management programs under 40 CFR 
51.308(f)(2)(iv) does not require states to adopt such practices or 
programs into their SIPs, although they may elect to do so).
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    As with source selection, the characterization of information on 
each of the factors is also subject to the documentation requirement in 
Sec.  51.308(f)(2)(iii). The reasonable progress analysis, including 
source selection, information gathering, characterization of the four 
statutory factors (and potentially visibility), balancing of the four 
factors, and selection of the emission reduction measures that 
represent reasonable progress, is a technically complex exercise, but 
also a flexible one that provides states with bounded discretion to 
design and implement approaches appropriate to their circumstances. 
Given this flexibility, Sec.  51.308(f)(2)(iii) plays an important 
function in requiring a state to document the technical basis for its 
decision making so that the public and the EPA can comprehend and 
evaluate the information and analysis the state relied upon to 
determine what emission reduction measures must be in place to make 
reasonable progress. The technical documentation must include the 
modeling, monitoring, cost, engineering, and emissions information on 
which the state relied to determine the measures necessary to make 
reasonable progress. This documentation requirement can be met through 
the provision of and reliance on technical analyses developed through a 
regional planning process, so long as that process and its output has 
been approved by all state participants. In addition to the explicit 
regulatory requirement to document the technical basis of their 
reasonable progress determinations, states are also subject to the 
general principle that those determinations must be reasonably moored 
to the statute.\25\ That is, a state's decisions about the emission 
reduction measures that are necessary to make reasonable progress must 
be consistent with the statutory goal of remedying existing and 
preventing future visibility impairment.
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    \25\ See Arizona ex rel. Darwin v. U.S. EPA, 815 F.3d 519, 531 
(9th Cir. 2016); Nebraska v. U.S. EPA, 812 F.3d 662, 668 (8th Cir. 
2016); North Dakota v. EPA, 730 F.3d 750, 761 (8th Cir. 2013); 
Oklahoma v. EPA, 723 F.3d 1201, 1206, 1208-10 (10th Cir. 2013); cf. 
also Alaska Dep't of Envtl. Conservation v. EPA, 540 U.S. 461, 485, 
490 (2004); Nat'l Parks Conservation Ass'n v. EPA, 803 F.3d 151, 165 
(3d Cir. 2015).
---------------------------------------------------------------------------

    The four statutory factors (and potentially visibility) are used to 
determine what emission reduction

[[Page 1489]]

measures for selected sources must be included in a state's long-term 
strategy for making reasonable progress. Additionally, the RHR at 40 
CFR 51.3108(f)(2)(iv) separately provides five ``additional factors'' 
\26\ that states must consider in developing their long-term 
strategies: (1) Emission reductions due to ongoing air pollution 
control programs, including measures to address reasonably attributable 
visibility impairment; (2) measures to reduce the impacts of 
construction activities; (3) source retirement and replacement 
schedules; (4) basic smoke management practices for prescribed fire 
used for agricultural and wildland vegetation management purposes and 
smoke management programs; and (5) the anticipated net effect on 
visibility due to projected changes in point, area, and mobile source 
emissions over the period addressed by the long-term strategy. The 2019 
Guidance provides that a state may satisfy this requirement by 
considering these additional factors in the process of selecting 
sources for four-factor analysis, when performing that analysis, or 
both, and that not every one of the additional factors needs to be 
considered at the same stage of the process. See 2019 Guidance at 21. 
EPA provided further guidance on the five additional factors in the 
2021 Clarifications Memo, explaining that a state should generally not 
reject cost-effective and otherwise reasonable controls merely because 
there have been emission reductions since the first planning period 
owing to other ongoing air pollution control programs or merely because 
visibility is otherwise projected to improve at Class I areas. 
Additionally, states generally should not rely on these additional 
factors to summarily assert that the state has already made sufficient 
progress and, therefore, no sources need to be selected or no new 
controls are needed regardless of the outcome of four-factor analyses. 
2021 Clarifications Memo at 13.
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    \26\ The five ``additional factors'' for consideration in 
section 51.308(f)(2)(iv) are distinct from the four factors listed 
in CAA section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states 
must consider and apply to sources in determining reasonable 
progress.
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    Because the air pollution that causes regional haze crosses state 
boundaries, Sec.  51.308(f)(2)(ii) requires a state to consult with 
other states that also have emissions that are reasonably anticipated 
to contribute to visibility impairment in a given Class I area. 
Consultation allows for each state that impacts visibility in an area 
to share whatever technical information, analyses, and control 
determinations may be necessary to develop coordinated emission 
management strategies. This coordination may be managed through inter- 
and intra-RPO consultation and the development of regional emissions 
strategies; additional consultations between states outside of RPO 
processes may also occur. If a state, pursuant to consultation, agrees 
that certain measures (e.g., a certain emission limitation) are 
necessary to make reasonable progress at a Class I area, it must 
include those measures in its SIP. 40 CFR 51.308(f)(2)(ii)(A). 
Additionally, the RHR requires that states that contribute to 
visibility impairment at the same Class I area consider the emission 
reduction measures the other contributing states have identified as 
being necessary to make reasonable progress for their own sources. 40 
CFR 51.308(f)(2)(ii)(B). If a state has been asked to consider or adopt 
certain emission reduction measures, but ultimately determines those 
measures are not necessary to make reasonable progress, that state must 
document in its SIP the actions taken to resolve the disagreement. 40 
CFR 51.308(f)(2)(ii)(C). The EPA will consider the technical 
information and explanations presented by the submitting state and the 
state with which it disagrees when considering whether to approve the 
state's SIP. See id.; 2019 Guidance at 53. Under all circumstances, a 
state must document in its SIP submission all substantive consultations 
with other contributing states. 40 CFR 51.308(f)(2)(ii)(C).

D. Reasonable Progress Goals

    Reasonable progress goals ``measure the progress that is projected 
to be achieved by the control measures states have determined are 
necessary to make reasonable progress based on a four-factor 
analysis.'' 82 FR at 3091. Their primary purpose is to assist the 
public and the EPA in assessing the reasonableness of states' long-term 
strategies for making reasonable progress towards the national 
visibility goal. See 40 CFR 51.308(f)(3)(iii)-(iv). States in which 
Class I areas are located must establish two RPGs, both in deciviews--
one representing visibility conditions on the clearest days and one 
representing visibility on the most anthropogenically impaired days--
for each area within their borders. 40 CFR 51.308(f)(3)(i). The two 
RPGs are intended to reflect the projected impacts, on the two sets of 
days, of the emission reduction measures the state with the Class I 
area, as well as all other contributing states, have included in their 
long-term strategies for the second implementation period.\27\ The RPGs 
also account for the projected impacts of implementing other CAA 
requirements, including non-SIP based requirements. Because RPGs are 
the modeled result of the measures in states' long-term strategies (as 
well as other measures required under the CAA), they cannot be 
determined before states have conducted their four-factor analyses and 
determined the control measures that are necessary to make reasonable 
progress. See 2021 Clarifications Memo at 6.
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    \27\ RPGs are intended to reflect the projected impacts of the 
measures all contributing states include in their long-term 
strategies. However, due to the timing of analyses and of control 
determinations by other states, other on-going emissions changes, a 
particular state's RPGs may not reflect all control measures and 
emissions reductions that are expected to occur by the end of the 
implementation period. The 2019 Guidance provides recommendations 
for addressing the timing of RPG calculations when states are 
developing their long-term strategies on disparate schedules, as 
well as for adjusting RPGs using a post-modeling approach. 2019 
Guidance at 47-48.
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    For the second implementation period, the RPGs are set for 2028. 
Reasonable progress goals are not enforceable targets, 40 CFR 
51.308(f)(3)(iii); rather, they ``provide a way for the states to check 
the projected outcome of the [long-term strategy] against the goals for 
visibility improvement.'' 2019 Guidance at 46. While states are not 
legally obligated to achieve the visibility conditions described in 
their RPGs, Sec.  51.308(f)(3)(i) requires that ``[t]he long-term 
strategy and the reasonable progress goals must provide for an 
improvement in visibility for the most impaired days since the baseline 
period and ensure no degradation in visibility for the clearest days 
since the baseline period.'' Thus, states are required to have emission 
reduction measures in their long-term strategies that are projected to 
achieve visibility conditions on the most impaired days that are better 
than the baseline period and show no degradation on the clearest days 
compared to the clearest days from the baseline period. The baseline 
period for the purpose of this comparison is the baseline visibility 
condition--the annual average visibility condition for the period 2000-
2004. See 40 CFR 51.308(f)(1)(i), 82 FR at 3097-98.
    So that RPGs may also serve as a metric for assessing the amount of 
progress a state is making towards the national visibility goal, the 
RHR requires states with Class I areas to compare the 2028 RPG for the 
most impaired days to the corresponding point on the URP line 
(representing visibility conditions in 2028 if visibility

[[Page 1490]]

were to improve at a linear rate from conditions in the baseline period 
of 2000-2004 to natural visibility conditions in 2064). If the most 
impaired days RPG in 2028 is above the URP (i.e., if visibility 
conditions are improving more slowly than the rate described by the 
URP), each state that contributes to visibility impairment in the Class 
I area must demonstrate, based on the four-factor analysis required 
under 40 CFR 51.308(f)(2)(i), that no additional emission reduction 
measures would be reasonable to include in its long-term strategy. 40 
CFR 51.308(f)(3)(ii). To this end, 40 CFR 51.308(f)(3)(ii) requires 
that each state contributing to visibility impairment in a Class I area 
that is projected to improve more slowly than the URP provide ``a 
robust demonstration, including documenting the criteria used to 
determine which sources or groups [of] sources were evaluated and how 
the four factors required by paragraph (f)(2)(i) were taken into 
consideration in selecting the measures for inclusion in its long-term 
strategy.'' The 2019 Guidance provides suggestions about how such a 
``robust demonstration'' might be conducted. See 2019 Guidance at 50-
51.
    The 2017 RHR, 2019 Guidance, and 2021 Clarifications Memo also 
explain that projecting an RPG that is on or below the URP based on 
only on-the-books and/or on-the-way control measures (i.e., control 
measures already required or anticipated before the four-factor 
analysis is conducted) is not a ``safe harbor'' from the CAA's and 
RHR's requirement that all states must conduct a four-factor analysis 
to determine what emission reduction measures constitute reasonable 
progress. The URP is a planning metric used to gauge the amount of 
progress made thus far and the amount left before reaching natural 
visibility conditions. However, the URP is not based on consideration 
of the four statutory factors and therefore cannot answer the question 
of whether the amount of progress being made in any particular 
implementation period is ``reasonable progress.'' See 82 FR at 3093, 
3099-3100; 2019 Guidance at 22; 2021 Clarifications Memo at 15-16.

E. Monitoring Strategy and Other State Implementation Plan Requirements

    Section 51.308(f)(6) requires states to have certain strategies and 
elements in place for assessing and reporting on visibility. Individual 
requirements under this subsection apply either to states with Class I 
areas within their borders, states with no Class I areas but that are 
reasonably anticipated to cause or contribute to visibility impairment 
in any Class I area, or both. A state with Class I areas within its 
borders must submit with its SIP revision a monitoring strategy for 
measuring, characterizing, and reporting regional haze visibility 
impairment that is representative of all Class I areas within the 
state. SIP revisions for such states must also provide for the 
establishment of any additional monitoring sites or equipment needed to 
assess visibility conditions in Class I areas, as well as reporting of 
all visibility monitoring data to the EPA at least annually. Compliance 
with the monitoring strategy requirement may be met through a state's 
participation in the Interagency Monitoring of Protected Visual 
Environments (IMPROVE) monitoring network, which is used to measure 
visibility impairment caused by air pollution at the 156 Class I areas 
covered by the visibility program. 40 CFR 51.308(f)(6), (f)(6)(i), 
(f)(6)(iv). The IMPROVE monitoring data is used to determine the 20% 
most anthropogenically impaired and 20% clearest sets of days every 
year at each Class I area and tracks visibility impairment over time.
    All states' SIPs must provide for procedures by which monitoring 
data and other information are used to determine the contribution of 
emissions from within the state to regional haze visibility impairment 
in affected Class I areas. 40 CFR 51.308(f)(6)(ii), (iii). Section 
51.308(f)(6)(v) further requires that all states' SIPs provide for a 
statewide inventory of emissions of pollutants that are reasonably 
anticipated to cause or contribute to visibility impairment in any 
Class I area; the inventory must include emissions for the most recent 
year for which data are available and estimates of future projected 
emissions. States must also include commitments to update their 
inventories periodically. The inventories themselves do not need to be 
included as elements in the SIP and are not subject to EPA review as 
part of the Agency's evaluation of a SIP revision.\28\ All states' SIPs 
must also provide for any other elements, including reporting, 
recordkeeping, and other measures, that are necessary for states to 
assess and report on visibility. 40 CFR 51.308(f)(6)(vi). Per the 2019 
Guidance, a state may note in its regional haze SIP that its compliance 
with the Air Emissions Reporting Rule (AERR) in 40 CFR part 51 Subpart 
A satisfies the requirement to provide for an emissions inventory for 
the most recent year for which data are available. To satisfy the 
requirement to provide estimates of future projected emissions, a state 
may explain in its SIP how projected emissions were developed for use 
in establishing RPGs for its own and nearby Class I areas.\29\
---------------------------------------------------------------------------

    \28\ See ``Step 8: Additional requirements for regional haze 
SIPs'' in 2019 Regional Haze Guidance at 55.
    \29\ Id.
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    Separate from the requirements related to monitoring for regional 
haze purposes under 40 CFR 51.308(f)(6), the RHR also contains a 
requirement at Sec.  51.308(f)(4) related to any additional monitoring 
that may be needed to address visibility impairment in Class I areas 
from a single source or a small group of sources. This is called 
``reasonably attributable visibility impairment.'' \30\ Under this 
provision, if the EPA or the FLM of an affected Class I area has 
advised a state that additional monitoring is needed to assess 
reasonably attributable visibility impairment, the state must include 
in its SIP revision for the second implementation period an appropriate 
strategy for evaluating such impairment.
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    \30\ EPA's visibility protection regulations define ``reasonably 
attributable visibility impairment'' as ``visibility impairment that 
is caused by the emission of air pollutants from one, or a small 
number of sources.'' 40 CFR 51.301.
---------------------------------------------------------------------------

F. Requirements for Periodic Reports Describing Progress Towards the 
Reasonable Progress Goals

    Section 51.308(f)(5) requires a state's regional haze SIP revision 
to address the requirements of paragraphs 40 CFR 51.308(g)(1) through 
(5) so that the plan revision due in 2021 will serve also as a progress 
report addressing the period since submission of the progress report 
for the first implementation period. The regional haze progress report 
requirement is designed to inform the public and the EPA about a 
state's implementation of its existing long-term strategy and whether 
such implementation is in fact resulting in the expected visibility 
improvement. See 81 FR 26942, 26950 (May 4, 2016), (82 FR at 3119, 
January 10, 2017). To this end, every state's SIP revision for the 
second implementation period is required to describe the status of 
implementation of all measures included in the state's long-term 
strategy, including BART and reasonable progress emission reduction 
measures from the first implementation period, and the resulting 
emissions reductions. 40 CFR 51.308(g)(1) and (2).
    A core component of the progress report requirements is an 
assessment of changes in visibility conditions on the clearest and most 
impaired days. For second implementation period progress reports, Sec.  
51.308(g)(3) requires states

[[Page 1491]]

with Class I areas within their borders to first determine current 
visibility conditions for each area on the most impaired and clearest 
days, 40 CFR 51.308(g)(3)(i)(B), and then to calculate the difference 
between those current conditions and baseline (2000-2004) visibility 
conditions in order to assess progress made to date. See 40 CFR 
51.308(g)(3)(ii)(B). States must also assess the changes in visibility 
impairment for the most impaired and clearest days since they submitted 
their first implementation period progress reports. See 40 CFR 
51.308(g)(3)(iii)(B), (f)(5). Since different states submitted their 
first implementation period progress reports at different times, the 
starting point for this assessment will vary state by state.
    Similarly, states must provide analyses tracking the change in 
emissions of pollutants contributing to visibility impairment from all 
sources and activities within the state over the period since they 
submitted their first implementation period progress reports. See 40 
CFR 51.308(g)(4), (f)(5). Changes in emissions should be identified by 
the type of source or activity. Section 51.308(g)(5) also addresses 
changes in emissions since the period addressed by the previous 
progress report and requires states' SIP revisions to include an 
assessment of any significant changes in anthropogenic emissions within 
or outside the state. This assessment must include an explanation of 
whether these changes in emissions were anticipated and whether they 
have limited or impeded progress in reducing emissions and improving 
visibility relative to what the state projected based on its long-term 
strategy for the first implementation period.

G. Requirements for State and Federal Land Manager Coordination

    Clean Air Act section 169A(d) requires that before a state holds a 
public hearing on a proposed regional haze SIP revision, it must 
consult with the appropriate FLM or FLMs; pursuant to that 
consultation, the state must include a summary of the FLMs' conclusions 
and recommendations in the notice to the public. Consistent with this 
statutory requirement, the RHR also requires that states ``provide the 
[FLM] with an opportunity for consultation, in person and at a point 
early enough in the State's policy analyses of its long-term strategy 
emission reduction obligation so that information and recommendations 
provided by the [FLM] can meaningfully inform the State's decisions on 
the long-term strategy.'' 40 CFR 51.308(i)(2). Consultation that occurs 
120 days prior to any public hearing or public comment opportunity will 
be deemed ``early enough,'' but the RHR provides that in any event the 
opportunity for consultation must be provided at least 60 days before a 
public hearing or comment opportunity. This consultation must include 
the opportunity for the FLMs to discuss their assessment of visibility 
impairment in any Class I area and their recommendations on the 
development and implementation of strategies to address such 
impairment. 40 CFR 51.308(i)(2). In order for the EPA to evaluate 
whether FLM consultation meeting the requirements of the RHR has 
occurred, the SIP submission should include documentation of the timing 
and content of such consultation. The SIP revision submitted to the EPA 
must also describe how the state addressed any comments provided by the 
FLMs. 40 CFR 51.308(i)(3). Finally, a SIP revision must provide 
procedures for continuing consultation between the state and FLMs 
regarding the state's visibility protection program, including 
development and review of SIP revisions, five-year progress reports, 
and the implementation of other programs having the potential to 
contribute to impairment of visibility in Class I areas. 40 CFR 
51.308(i)(4).

IV. The EPA's Evaluation of Massachusetts' Regional Haze Submission for 
the Second Implementation Period

A. Background on Massachusetts' First Implementation Period SIP 
Submission

    MassDEP submitted its regional haze SIP for the first 
implementation period to the EPA on July 28, 2009, and supplemented it 
on December 9, 2010, March 2, 2011, and December 7, 2011. The EPA 
approved Massachusetts' first implementation period regional haze SIP 
submission on September 19, 2013 (78 FR 57487). EPA's approval 
included, but was not limited to, the portions of the plan that address 
the reasonable progress requirements, Massachusetts' implementation of 
Best Available Retrofit Technologies on eligible sources, and 
Massachusetts' 310 CMR 7.05 ``Fuels All Districts;'' Sulfur in Fuels 
rule. The requirements for regional haze SIPs for the first 
implementation period are contained in 40 CFR 51.308(d) and (e). 40 CFR 
51.308(b). Pursuant to 40 CFR 51.308(g), Massachusetts was also 
responsible for submitting a five-year progress report as a SIP 
revision for the first implementation period, which it did on February 
9, 2018. The EPA approved the progress report into the Massachusetts 
SIP on March 29, 2019 (84 FR 11885).

B. Massachusetts' Second Implementation Period SIP Submission and the 
EPA's Evaluation

    In accordance with CAA sections 169A and the RHR at 40 CFR 
51.308(f), on July 22, 2021,\31\ Massachusetts submitted a revision to 
the Massachusetts SIP to address its regional haze obligations for the 
second implementation period, which runs through 2028. Massachusetts 
made a draft Regional Haze SIP submission available for public comment 
on April 7, 2021. Massachusetts has included the public comments and 
its responses to those comments in the submission.
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    \31\ Massachusetts supplemented its SIP submission on June 15, 
2022.
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    The following sections describe Massachusetts' SIP submission, 
including analyses conducted by MANE-VU and Massachusetts' 
determinations based on those analyses, Massachusetts' assessment of 
progress made since the first implementation period in reducing 
emissions of visibility impairing pollutants, and the visibility 
improvement progress at nearby Class I areas. This notice also contains 
EPA's evaluation of Massachusetts' submission against the requirements 
of the CAA and RHR for the second implementation period of the regional 
haze program.

C. Identification of Class I Areas

    Section 169A(b)(2) of the CAA requires each state in which any 
Class I area is located or ``the emissions from which may reasonably be 
anticipated to cause or contribute to any impairment of visibility'' in 
a Class I area to have a plan for making reasonable progress toward the 
national visibility goal. The RHR implements this statutory requirement 
at 40 CFR 51.308(f), which provides that each state's plan ``must 
address regional haze in each mandatory Class I Federal area located 
within the State and in each mandatory Class I Federal area located 
outside the State that may be affected by emissions from within the 
State,'' and (f)(2), which requires each state's plan to include a 
long-term strategy that addresses regional haze in such Class I areas. 
Massachusetts has no mandatory Class I Federal area within its borders.
    For the second implementation period, MANE-VU performed technical 
analyses \32\ to help assess source and state-level contributions to 
visibility impairment and the need for interstate consultation. MANE-VU 
used the

[[Page 1492]]

results of these analyses to determine which states' emissions ``have a 
high likelihood of affecting visibility in MANE-VU's Class I areas.'' 
\33\ Similar to metrics used in the first implementation period,\34\ 
MANE-VU used a greater than 2 percent of sulfate plus nitrate emissions 
contribution criteria to determine whether emissions from individual 
jurisdictions within the region affected visibility in any Class I 
areas. The MANE-VU analyses for the second implementation period used a 
combination of data analysis techniques, including emissions data, 
distance from Class I areas, wind trajectories, and CALPUFF dispersion 
modeling. Although many of the analyses focused only on SO<INF>2</INF> 
emissions and resultant particulate sulfate contributions to visibility 
impairment, some also incorporated NO<INF>X</INF> emissions to estimate 
particulate nitrate contributions.
---------------------------------------------------------------------------

    \32\ The contribution assessment methodologies for MANE-VU Class 
I areas are summarized in MA RH SIP Appendix 16 of the docket. 
``Selection of States for MANE-VU Regional Haze Consultation 
(2018),'' MANE-VU TSC. September 5, 2017.
    \33\ Id.
    \34\ See docket EPA-R01-OAR-2012-0025 for MANE-VU supporting 
materials.
---------------------------------------------------------------------------

    One MANE-VU analysis used for contribution assessment was CALPUFF 
air dispersion modeling. The CALPUFF model was used to estimate sulfate 
and nitrate formation and transport in MANE-VU and nearby regions 
originating from large electric generating unit (EGU) point sources and 
other large industrial and institutional sources in the eastern and 
central United States. Information from an initial round of CALPUFF 
modeling was collated for the 444 EGUs that were determined to warrant 
further scrutiny based on their emissions of SO<INF>2</INF> and 
NO<INF>X</INF>. The list of EGUs was based on an enhanced ``Q/d'' 
analysis \35\ that considered recent SO<INF>2</INF> emissions in the 
eastern United States and an analysis that adjusted previous 2002 MANE-
VU CALPUFF modeling by applying a ratio of 2011 to 2002 SO<INF>2</INF> 
emissions. This list of sources was then enhanced by including the top 
five SO<INF>2</INF> and NO<INF>X</INF> emission sources for 2011 for 
each state included in the modeling domain. A total of 311 EGU stacks 
(as opposed to individual units) were included in the CALPUFF modeling 
analysis. Initial information was also collected on the 50 industrial 
and institutional sources that, according to 2011 Q/d analysis, 
contributed the most to visibility impact in each Class I area. The 
ultimate CALPUFF modeling run included a total of 311 EGU stacks and 82 
industrial facilities. The summary report for the CALPUFF modeling 
included the top 10 most impacting EGUs and the top 5 most impacting 
industrial/institutional sources for each Class I area and compiled 
those results into a ranked list of the most impacting EGUs and 
industrial sources at MANE-VU Class I areas.\36\ Overall, MANE-VU found 
that emission sources located close to Class I areas typically show 
higher visibility impacts than similarly sized facilities further away. 
But visibility degradation appears to be dominated by the more distant 
emission sources due to their larger emissions. Massachusetts had five 
EGUs and one industrial source that were identified in the MANE-VU 
CALPUFF modeling as having a magnitude of emissions located close 
enough to a Class I area that they could have the potential for 
visibility impacts.\37\
---------------------------------------------------------------------------

    \35\ ``Q/d'' is emissions (Q) in tons per year, typically of one 
or a combination of visibility-impairing pollutants, divided by 
distance to a class I area (d) in kilometers. The resulting ratio is 
commonly used as a metric to assess a source's potential visibility 
impacts on a particular class I area.
    \36\ See appendix 8 ``2016 MANE-VU Source Contribution Modeling 
Report--CALPUFF Modeling of
    Large Electrical Generating Units and Industrial Sources.'' 
MANE-VU TSC. April 4, 2017.
    \37\ See Section 5.4, page 68, Massachusetts Regional Haze SIP 
Revision for 2018-2028 in the docket.
---------------------------------------------------------------------------

    Of the six sources, four were units at Brayton Point Power Station, 
a coal-fired EGU facility (ORISPL 01619; MassDEP AQID 1200061). All 
four units at Brayton Point ceased operation in 2017 and the permits 
were revoked on December 6, 2017.
    Canal Station (ORISPL 1599; MassDEP AQID 1200054) operates the 
other EGU (Unit 1) identified by the modelling, and its greatest impact 
was to Acadia. Unit 1 is a Babcock & Wilcox boiler that fires No. 6 
fuel oil, with a permitted maximum sulfur content of 0.5 percent by 
weight (wt%) as the sole operational fuel, with No. 2 fuel oil as a 
startup/ignition fuel. Unit 1 has an approximate maximum heat input 
rate of 5,083 million British thermal units per hour (MMBtu/hr) and a 
generating capacity of approximately 560 (net) megawatts (MW). Unit 1 
is equipped with low-NO<INF>X</INF> burners, overfire air ports, flue 
gas recirculation (FGR), and Selective Catalytic Reduction (SCR) for 
the control of NO<INF>X</INF> emissions. PM emissions are controlled by 
an Electrostatic Precipitator (ESP).
    The emission controls installed on Unit 1 are necessary to achieve 
compliance with the applicable emission limits under 310 CMR 7.29 and 
Air Plan Approvals (i.e., state air permits) issued pursuant to 310 CMR 
7.02
    Massachusetts concludes that visibility impairing pollutants from 
Canal Unit 1 are currently well controlled; however, Canal has 
committed to purchasing 0.3 wt% No. 6 fuel oil following the depletion 
of the current fuel inventory. Therefore, Massachusetts asked the owner 
of Canal Unit 1 to submit an application to modify its plan approval to 
require use of 0.3% sulfur content oil. Massachusetts approved the plan 
application May 26, 2022, and submitted the plan approval to EPA for 
approval into the SIP as a supplement to the Regional Haze SIP Revision 
for Massachusetts on June 15, 2022. If Canal Unit 1 should operate 
above 10% capacity factor in the future, existing NO<INF>X</INF> RACT 
regulations (310 CMR 7.19) will further limit the NO<INF>X</INF> 
emissions. From 2013 through 2022, Canal Unit one capacity had a 
weighted average of 2% capacity per year, with a low of 0.1% to a high 
of 7% capacity utilization by year and emitted an average of 42 tons of 
NO<INF>X</INF> per year, ranging from a low of 2 tons to a high of 201 
tons per year. Massachusetts will evaluate any changes in the operation 
of Canal Unit 1 in the next progress report.
    The only Massachusetts industrial source deemed by MANE-VU to have 
the potential for significant impact on Class I areas in 2011 was 
Solutia, Inc., which at the time was a coal- and oil-fired chemical 
plant. Solutia's greatest impact was to Lye Brook, and it ranked 14th 
in the list of industrial/institutional sources that had potential 
impacts on Lye Brook, based primarily on its SO<INF>2</INF> emissions. 
MANE-VU estimated maximum extinction for Solutia at Lye Brook to be 
less than 1 Mm-1. As reflected in the current Title V permit for the 
facility (Permit Transmittal No.: X229245), Solutia has since repowered 
from coal/oil to natural gas and is therefore no longer a significant 
source of SO<INF>2</INF>.
    As explained above, the EPA concluded in the 1999 RHR that ``all 
[s]tates contain sources whose emissions are reasonably anticipated to 
contribute to regional haze in a Class I area,'' 64 FR at 35721, and 
this determination was not changed in the 2017 RHR. Critically, the 
statute and regulation both require that the cause-or-contribute 
assessment consider all emissions of visibility-impairing pollutants 
from a state, as opposed to emissions of a particular pollutant or 
emissions from a certain set of sources. Consistent with these 
requirements, the 2019 Guidance makes it clear that ``all types of 
anthropogenic sources are to be included in the determination'' of 
whether a state's emissions are reasonably anticipated to result in any 
visibility impairment. 2019 Guidance at 8.

[[Page 1493]]

    The screening analyses on which MANE-VU relied are useful for 
certain purposes. MANE-VU used information from its technical analysis 
to rank the largest contributing states to sulfate and nitrate 
impairment in the seven MANE-VU Class I areas and three additional, 
nearby Class I areas.\38\ The rankings were used to determine upwind 
states that were deemed important to include in state-to-state 
consultation (based on an identified impact screening threshold). 
Additionally, large individual source impacts were used to target MANE-
VU control analysis ``Asks'' \39\ of states and sources both within and 
upwind of MANE-VU.\40\ The EPA finds the nature of the analyses 
generally appropriate to support decisions on states with which to 
consult. However, we have cautioned that source selection methodologies 
that target the largest regional contributors to visibility impairment 
across multiple states may not be reasonable for a particular state if 
it results in few or no sources being selected for subsequent analysis. 
2021 Clarifications Memo at 3.
---------------------------------------------------------------------------

    \38\ The Class I areas analyzed were Acadia National Park in 
Maine, Brigantine Wilderness in New Jersey, Great Gulf Wilderness 
and Presidential Range--Dry River Wilderness in New Hampshire, Lye 
Brook Wilderness in Vermont, Moosehorn Wilderness in Maine, 
Roosevelt Campobello International Park in New Brunswick, Shenandoah 
National Park in Virginia, James River Face Wilderness in Virginia, 
and Dolly Sods/Otter Creek Wildernesses in West Virginia.
    \39\ As explained more fully in Section IV.E.a, MANE-VU refers 
to each of the components of its overall strategy as an ``Ask ``of 
its member states.
    \40\ The MANE-VU consultation report (Appendix 20) explains that 
``[t]he objective of this technical work was to identify states and 
sources from which MANE-VU will pursue further analysis. This 
screening was intended to identify which states to invite to 
consultation, not a definitive list of which states are 
contributing.''
---------------------------------------------------------------------------

    With regard to the analysis and determinations regarding 
Massachusetts' contribution to visibility impairment at out-of-state 
Class I areas, the MANE-VU technical work focuses on the magnitude of 
visibility impacts from certain Massachusetts emissions on other nearby 
Class I areas. However, the analyses did not account for all emissions 
and all components of visibility impairment (e.g., primary PM 
emissions, and impairment from fine PM, elemental carbon, and organic 
carbon). In addition, Q/d analyses with a relatively simplistic 
accounting for wind trajectories and CALPUFF applied to a very limited 
set of EGUs and major industrial sources of SO<INF>2</INF> and 
NO<INF>X</INF> are not scientifically rigorous tools capable of 
evaluating contribution to visibility impairment from all emissions in 
a state. The EPA agrees that the contribution to visibility impairment 
from Massachusetts' emissions at nearby out-of-state Class I areas is 
smaller than that from numerous other MANE-VU states.\41\ While some 
MANE-VU states noted that the contributions from several states outside 
the MANE-VU region are significantly larger than its own, we again 
clarify that each state is obligated under the CAA and RHR to address 
regional haze visibility impairment resulting from emissions from 
within the state, irrespective of whether another state's contribution 
is greater. See 2021 Clarifications Memo at 3. Additionally, we note 
that the 2 percent or greater sulfate-plus-nitrate threshold used to 
determine whether Massachusetts emissions contribute to visibility 
impairment at a particular Class I area may be higher than what EPA 
believes is an ``extremely low triggering threshold'' intended by the 
statute and regulations. In sum, based on the information provided, EPA 
generally agrees with the State's conclusions that emissions from 
Massachusetts contribute to visibility impairment in the Class I areas 
in Maine and New Brunswick and have relatively small contributions to 
the other nearby Class I areas. However, due to the low triggering 
threshold implied by the Rule and the lack of rigorous modeling 
analyses, we do not necessarily agree with the level of the State's 2% 
contribution threshold.
---------------------------------------------------------------------------

    \41\ Because MANE-VU did not include all of Massachusetts' 
emissions or contributions to visibility impairment in its analysis, 
we cannot definitively state that Massachusetts' contribution to 
visibility impairment is not the most significant. However, that is 
very likely the case.
---------------------------------------------------------------------------

    Regardless, Massachusetts did determine that sources and emissions 
within the state contribute to visibility impairment at Class I areas 
in Maine and New Brunswick. Furthermore, the state took part in the 
emission control strategy consultation process as a member of MANE-VU. 
As part of that process, MANE-VU developed a set of emissions reduction 
measures identified as being necessary to make reasonable progress in 
the seven MANE-VU Class I areas. This strategy consists of six Asks for 
states within MANE-VU and five Asks for states outside the region that 
were found to impact visibility at Class I areas within MANE-VU.\42\ 
Massachusetts' submission discusses each of the Asks and explains why 
or why not each is applicable and how it has complied with the relevant 
components of the emissions control strategy the MANE-VU states laid 
out. Massachusetts worked with MANE-VU to determine potential 
reasonable measures that could be implemented by 2028, considering the 
cost of compliance, the time necessary for compliance, the energy and 
non-air quality environmental impacts, and the remaining useful life of 
any potentially affected sources. As discussed in further detail below, 
the EPA is proposing to find that Massachusetts has submitted a 
regional haze plan that meets the requirements of 40 CFR 51.308(f)(2) 
related to the development of a long-term strategy. Thus, we propose to 
find that Massachusetts has nevertheless satisfied the applicable 
requirements for making reasonable progress towards natural visibility 
conditions in Class I areas that may be affected by emissions from the 
state.
---------------------------------------------------------------------------

    \42\ See Section 6.3 Implementing the 2017 MANE-VU Statement.
---------------------------------------------------------------------------

D. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress

    Section 51.308(f)(1) requires states to determine the following for 
``each mandatory Class I Federal area located within the State'': 
baseline visibility conditions for the most impaired and clearest days, 
natural visibility conditions for the most impaired and clearest days, 
progress to date for the most impaired and clearest days, the 
differences between current visibility conditions and natural 
visibility conditions, and the URP. This section also provides the 
option for states to propose adjustments to the URP line for a Class I 
area to account for visibility impacts from anthropogenic sources 
outside the United States and/or the impacts from wildland prescribed 
fires that were conducted for certain, specified objectives. 40 CFR 
51.308(f)(1)(vi)(B).
    Although Massachusetts has no Class I areas, emissions from 
Massachusetts sources contribute to visibility impairment in MANE-VU 
Class I areas. MANE-VU Class I areas as well as other nearby Class I 
areas that MANE-VU examined, are listed below. MANE-VU used certain 
areas (as noted below) to represent nearby Class I areas where monitors 
do not exist.\43\
---------------------------------------------------------------------------

    \43\ See Appendix 22 ``Mid-Atlantic/Northeast U.S. Visibility 
Data, 2004-2019 (2nd RH SIP Metrics). MANE-VU (prepared by Maine 
Department of Environmental Protection). January 21, 2021 
revision.''
---------------------------------------------------------------------------

    The MANE-VU Class I Areas are Lye Brook Wilderness Area (Vermont), 
Great Gulf Wilderness Area (New Hampshire) (used to represent 
Presidential Range--Dry River Wilderness Area), Presidential Range--Dry 
River Wilderness Area (New Hampshire), Acadia National Park (Maine), 
Moosehorn Wildlife Refuge (Maine) (used to represent Roosevelt

[[Page 1494]]

Campobello International Park), Roosevelt Campobello International Park 
(New Brunswick, Canada), Brigantine Wildlife Refuge (New Jersey). 
Nearby Class I Areas consist of Dolly Sods Wilderness Area (West 
Virginia) (used to represent Otter Creek Wilderness Area), Otter Creek 
Wilderness Area (West Virginia), Shenandoah National Park (Virginia), 
and James River Face Wilderness Area (Virginia).

E. Long-Term Strategy for Regional Haze

a. Massachusetts' Response to the Six MANE-VU Asks
    Each state having a Class I area within its borders or emissions 
that may affect visibility in a Class I area must develop a long-term 
strategy for making reasonable progress towards the national visibility 
goal. CAA Sec.  169A(b)(2)(B). As explained in the Background section 
of this notice, reasonable progress is achieved when all states 
contributing to visibility impairment in a Class I area are 
implementing the measures determined--through application of the four 
statutory factors to sources of visibility impairing pollutants--to be 
necessary to make reasonable progress. 40 CFR 51.308(f)(2)(i). Each 
state's long-term strategy must include the enforceable emission 
limitations, compliance schedules, and other measures that are 
necessary to make reasonable progress. 40 CFR 51.308(f)(2). All new 
(i.e., additional) measures that are the outcome of four-factor 
analyses are necessary to make reasonable progress and must be in the 
long-term strategy. If the outcome of a four-factor analysis and other 
measures necessary to make reasonable progress is that no new measures 
are reasonable for a source, that source's existing measures are 
necessary to make reasonable progress, unless the state can demonstrate 
that the source will continue to implement those measures and will not 
increase its emission rate. Existing measures that are necessary to 
make reasonable progress must also be in the long-term strategy. In 
developing its long-term strategies, a state must also consider the 
five additional factors in Sec.  51.308(f)(2)(iv). As part of its 
reasonable progress determinations, the state must describe the 
criteria used to determine which sources or group of sources were 
evaluated (i.e., subjected to four-factor analysis) for the second 
implementation period and how the four factors were taken into 
consideration in selecting the emission reduction measures for 
inclusion in the long-term strategy. 40 CFR 51.308(f)(2)(i).
    The following section summarizes how Massachusetts' SIP submission 
addressed the requirements of Sec.  51.308(f)(2)(i); specifically, it 
describes MANE-VU's development of the six Asks and how Massachusetts 
addressed each. Massachusetts considers the six Asks to comprise its 
long-term strategy for the second planning period to address regional 
haze visibility impairment for each mandatory Class I Federal area 
affected by emissions from Massachusetts. When developing the Asks with 
the other MANE-VU states and applying them to sources in Massachusetts, 
the Commonwealth considered the four statutory factors and the 
additional regulatory factors and identified emissions control measures 
necessary to make reasonable progress towards the goal of preventing of 
any future, and remedying any existing, anthropogenic visibility 
impairment in Class I areas affected by emissions from Massachusetts. 
The EPA's evaluation of Massachusetts' long-term strategy is contained 
in the following Section IV.E.b. Massachusetts' SIP submission 
describes how it plans to meet the long-term strategy requirements 
defined by the state and MANE-VU as the ``Asks.'' \44\
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    \44\ Massachusetts Regional Haze SIP submission at 74.
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    States may rely on technical information developed by the RPOs of 
which they are members to select sources for four-factor analysis and 
to conduct that analysis, as well as to satisfy the documentation 
requirements under Sec.  51.308(f). Where an RPO has performed source 
selection and/or four-factor analyses (or considered the five 
additional factors in Sec.  51.308(f)(2)(iv)) for its member states, 
those states may rely on the RPO's analyses for the purpose of 
satisfying the requirements of Sec.  51.308(f)(2)(i) so long as the 
states have a reasonable basis to do so and all state participants in 
the RPO process have approved the technical analyses. 40 CFR 
51.308(f)(2)(iii). States may also satisfy the requirement of Sec.  
51.308(f)(2)(ii) to engage in interstate consultation with other states 
that have emissions that are reasonably anticipated to contribute to 
visibility impairment in a given Class I area under the auspices of 
intra- and inter-RPO engagement.
    Massachusetts is a member of the MANE-VU RPO and participated in 
the RPO's regional approach to developing a strategy for making 
reasonable progress towards the national visibility goal in the MANE-VU 
Class I areas. MANE-VU's strategy includes a combination of: (1) 
Measures for certain source sectors and groups of sectors that the RPO 
determined were reasonable for states to pursue, and (2) a request for 
member states to conduct four-factor analyses for individual sources 
that it identified as contributing to visibility impairment. MANE-VU 
refers to each of the components of its overall strategy as an Ask of 
its member states. On August 25, 2017, the Executive Director of MANE-
VU, on behalf of the MANE-VU states and tribal nations, signed a 
statement that identifies six emission reduction measures that comprise 
the Asks for the second implementation period.\45\ The Asks were 
``designed to identify reasonable emission reduction strategies that 
must be addressed by the states and tribal nations of MANE-VU through 
their regional haze SIP updates.'' \46\ The statement explains that 
``[i]f any State cannot agree with or complete a Class I State's Asks, 
the State must describe the actions taken to resolve the disagreement 
in the Regional Haze SIP.'' \47\
---------------------------------------------------------------------------

    \45\ See appendix 15 ``MANE-VU Regional Haze Consultation Report 
and Consultation Documentation--Final.''
    \46\ Id.
    \47\ Id.
---------------------------------------------------------------------------

    MANE-VU's recommendations as to the appropriate control measures 
were based on technical analyses documented in the RPO's reports and 
included as appendices to or referenced in Massachusetts' regional haze 
SIP submission. One of the initial steps of MANE-VU's technical 
analysis was to determine which visibility-impairing pollutants should 
be the focus of its efforts for the second implementation period. In 
the first implementation period, MANE-VU determined that sulfates were 
the most significant visibility impairing pollutant at the region's 
Class I areas. To determine the impact of certain pollutants on 
visibility at Class I areas for the purpose of second implementation 
period planning, MANE-VU conducted an analysis comparing the pollutant 
contribution on the clearest and most impaired days in the baseline 
period (2000-2004) to the most recent period (2012-2016) \48\ at MANE-
VU and nearby Class I areas. MANE-VU found that while SO<INF>2</INF> 
emissions were decreasing and visibility was improving, sulfates still 
made up the most significant contribution to visibility impairment at 
MANE-VU and nearby Class I areas. According to the analysis, 
NO<INF>X</INF> emissions have begun to play a more significant role in 
visibility

[[Page 1495]]

impacts in recent years as SO<INF>2</INF> emissions have decreased. The 
technical analyses used by Massachusetts are included in their 
submission and are as follows:
---------------------------------------------------------------------------

    \48\ The period of 2012-2016 was the most recent period for 
which data were available at the time of analysis.
---------------------------------------------------------------------------

    <bullet> 2016 Updates to the Assessment of Reasonable Progress for 
Regional Haze in MANE-VU Class I Areas (MA Appendix 6);
    <bullet> Impact of Wintertime SCR/SNCR Optimization on Visibility 
Impairing Nitrate Precursor Emissions. November 2017. (MA Appendix 17);
    <bullet> High Electric Demand Days and Visibility Impairment in 
MANE-VU. December 2017. (MA Appendix 18);
    <bullet> Benefits of Combined Heat and Power Systems for Reducing 
Pollutant Emissions in MANE-VU States. March 2016. (MA Appendix 7);
    <bullet> 2016 MANE-VU Source Contribution Modeling Report--CALPUFF 
Modeling of Large Electrical Generating Units and Industrial Sources 
April 4, 2017 (MA Appendix 8);
    <bullet> Contribution Assessment Preliminary Inventory Analysis. 
October 10, 2016. (MA Appendix 11);
    <bullet> Four-Factor Data Collection Memo. March 2017. (MA Appendix 
14);
    <bullet> Status of the Top 167 Stacks from the 2008 MANE-VU Ask. 
July 2016. (MA Appendix 10).
    To support development of the Asks, MANE-VU gathered information on 
each of the four statutory factors for six source sectors it 
determined, based on an examination of annual emission inventories, 
``had emissions [of SO<INF>2</INF> and/or NO<INF>X</INF>] that were 
reasonabl[y] anticipated to contribute to visibility degradation in 
MANE-VU:'' electric generating units (EGUs), industrial/commercial/
institutional boilers (ICI boilers), cement kilns, heating oil, 
residential wood combustion, and outdoor wood combustion.\49\ MANE-VU 
also collected data on individual sources within the EGU, ICI boiler, 
and cement kiln sectors.\50\ Information for the six sectors included 
explanations of technically feasible control options for SO<INF>2</INF> 
or NO<INF>X</INF>, illustrative cost-effectiveness estimates for a 
range of model units and control options, sector-wide cost 
considerations, potential time frames for compliance with control 
options, potential energy and non-air-quality environmental impacts of 
certain control options, and how the remaining useful lives of sources 
might be considered in a control analysis.\51\ Source-specific data 
included SO<INF>2</INF> emissions \52\ and existing controls \53\ for 
certain existing EGUs, ICI boilers, and cement kilns. MANE-VU 
considered this information on the four factors as well as the analyses 
developed by the RPO's Technical Support Committee when it determined 
specific emission reduction measures that were found to be reasonable 
for certain sources within two of the sectors it had examined--EGUs and 
ICI boilers. The Asks were based on this analysis and looked to either 
optimize the use of existing controls, have states conduct further 
analysis on EGU or ICI boilers with considerable visibility impacts, 
implement low sulfur fuel standards, or lock-in lower emission rates.
---------------------------------------------------------------------------

    \49\ See appendix 14 ``MANE-VU Four Factor Data Collection 
Memo,'' at 1, March 30, 2017.
    \50\ See appendix 6 ``2016 Updates to the Assessment of 
Reasonable Progress for Regional Haze in MANE-VU Class I Areas, Jan. 
31, 2016.''
    \51\ Id.
    \52\ See appendix 14 ``Four Factor Data Collection Memo.''
    \53\ See appendix 10 ``Status of the Top 167 Stacks from the 
2008 MANE-VU Ask. July 2016.''
---------------------------------------------------------------------------

    MANE-VU Ask 1 is ``Electric Generating Units (EGUs) with a 
nameplate capacity larger than or equal to 25 MW with already installed 
NO<INF>X</INF> and/or SO<INF>2</INF> controls--ensure the most 
effective use of control technologies on a year-round basis to 
consistently minimize emissions of haze precursors or obtain equivalent 
alternative emission reductions.'' MANE-VU observed that EGUs often 
only run NO<INF>X</INF> emissions controls to comply with ozone season 
trading programs and consequently, NO<INF>X</INF> sources may be 
uncontrolled during the winter and non-peak summer days. MANE-VU found 
that: (1) running existing installed controls [selective catalytic 
reduction (SCR) and selective non-catalytic reduction (SNCR)] is one of 
the most cost-effective ways to control NO<INF>X</INF> emissions from 
EGUs; and (2) that running existing controls year round could 
substantially reduce the NO<INF>X</INF> emissions in many of the states 
upwind of Class I areas in MANE-VU that lead to visibility impairment 
during the winter from nitrates. MANE-VU included this as an emission 
management strategy because large EGUs had already been identified as 
dominant contributors to visibility impairment and the low cost of 
running already installed controls made it reasonable.
    Massachusetts identified 53 EGU units that meet the criteria of 25 
MW or larger with installed controls.\54\ Massachusetts explained that 
all of these units have NO<INF>X</INF> controls and that the permits 
for these units set short-term NO<INF>X</INF> emissions limits in lbs/
hr or concentration, which are promulgated in MA 310 CMR 7.19 and 
approved into the MA SIP on October 15, 2020 (85 FR 65236). The permits 
also require the performance of the unit and its controls to be 
verified. Therefore, Massachusetts concluded that it has met this Ask-1 
strategy and represented that it will continue to do so for new units 
that begin operation during the second planning period based on the 
rules now in effect.
---------------------------------------------------------------------------

    \54\ See appendix 23 ``Massachusetts Facilities Subject to Ask 
1: EGUs >= 25MW with Controls.''
---------------------------------------------------------------------------

    MANE-VU Ask 2 consists of a request that states ``Emission sources 
modeled by MANE-VU that have the potential for 3.0 Mm-1 or greater 
visibility impacts at any MANE-VU Class I area, as identified by MANE-
VU contribution analyses . . . perform a four-factor analysis for 
reasonable installation or upgrade to emission controls.''
    Massachusetts explained that, after examining the visibility impact 
modeling results (described in Section 5 of Massachusetts' submittal), 
MANE-VU concluded that a 3 Mm-1 cutoff captured the group of sources 
contributing the largest percentage of visibility impairing pollutants 
to Class I areas and that the determination of reasonability for 
controls on each unit was left to the individual states to allow for 
unit-specific consideration of the four factors.
    MANE-VU's analysis identified 2 units in Massachusetts with 
potential impacts of 3.0 Mm-1 or greater based on 2015 emissions: 
Brayton Point 4 and Canal Station 1. Brayton Point was a coal-fired EGU 
facility (ORISPL 01619; MassDEP AQID 1200061). Massachusetts notes that 
all units at Brayton Point ceased operation in 2017 and the permits 
were revoked on December 6, 2017. Canal Station (ORISPL 1599; MassDEP 
AQID 1200054) operates two steam electric generating units. Unit 1 is a 
Babcock & Wilcox boiler that fires No. 6 fuel oil, with a permitted 
maximum sulfur content of 0.5 percent by weight (wt%) as the sole 
operational fuel, with No. 2 fuel oil as a startup/ignition fuel. Unit 
1 has an approximate maximum heat input rate of 5,083 million British 
thermal units per hour (MMBtu/hr) and a generating capacity of 
approximately 560 (net) megawatts (MW). Unit 1 is equipped with low-
NO<INF>X</INF> burners, overfire air ports, flue gas recirculation 
(FGR), and Selective Catalytic Reduction (SCR) for the control of 
NO<INF>X</INF> emissions. PM emissions are controlled by an 
Electrostatic Precipitator (ESP). In recent years, Unit 1 has operated 
with a capacity factor well below 10%
    The emission controls installed on Unit 1 are necessary to achieve 
compliance with the applicable emission limits under 310 CMR 7.29 and 
Air Plan Approvals issued pursuant to 310 CMR 7.02. The governing 
NO<INF>X</INF>,

[[Page 1496]]

SO<INF>2</INF>, and PM emission limits for Unit 1 are summarized in 
Table 6-1 of the MA SIP submission.
    The NO<INF>X</INF> and PM emission limits are readily met through 
the use of the installed emission controls. The sulfur content of No. 6 
oil is limited to 0.5 wt% in accordance with 310 CMR 7.05 but the 
facility purchases 0.3 wt% sulfur No. 6 to meet the 6.0 lbs/MW-hr 
monthly, 3.0 lbs/MWhr rolling 12-month SO<INF>2</INF> limit applicable 
under 310 CMR 7.29.
    Table 6-2 in the State's submittal shows Canal Unit 1's actual 
emissions in 2015 along with much lower emissions MANE-VU projected for 
2028 and lower still for 2028 emissions under Ask 2.
    Massachusetts requested and received a four-factor analysis from 
the owner of the facility.\55\ Based on that analysis, Massachusetts 
concluded that visibility impairing pollutants from Canal Unit 1 are 
currently well controlled with low-NO<INF>X</INF> burners, overfire air 
ports, flue gas recirculation (FGR), Selective Catalytic Reduction 
(SCR) and an Electrostatic Precipitator (ESP). In addition to these 
existing controls, however, Canal committed to purchase only 0.3 wt% 
No. 6 fuel oil, following the depletion of the current fuel inventory, 
which has at times contained No. 6 fuel oil with a sulfur content 
greater than 0.3 wt%. EPA expects that this commitment will further 
reduce its SO<INF>2</INF> emissions. As a result, Massachusetts 
requested and received from the owner of Canal Unit 1 an application to 
modify its plan approval to require use of 0.3% sulfur content oil. 
Massachusetts approved the application and submitted the Plan approval 
to EPA as a supplement to the Massachusetts Regional Haze SIP Revision 
in a letter dated June 15, 2022.\56\ Massachusetts further notes that, 
if Canal Unit 1 should operate above 10% capacity factor in the future, 
existing SIP-approved NO<INF>X</INF> RACT regulations (310 CMR 7.19) 
will further limit the NO<INF>X</INF> emissions. Massachusetts states 
that it will evaluate any changes in the operation of Canal Unit 1 in 
future regional haze planning and reporting.
---------------------------------------------------------------------------

    \55\ See Appendix 31, ``Four Factor Analysis Canal Unit 1, Canal 
Generating Station, Sandwich, MA . . .''
    \56\ See MassDEP letter to EPA ``Subject: Regional Haze SIP 
Revision for Massachusetts--supplement'' and its attachment MassDEP 
letter to Canal Generating LLC, Air Quality Plan Approval.
---------------------------------------------------------------------------

    MANE-VU Ask 3 is: ``Each MANE-VU State that has not yet fully 
adopted an ultra-low sulfur fuel oil standard as requested by MANE-VU 
in 2007--pursue this standard as expeditiously as possible and before 
2028, depending on supply availability, where the standards are as 
follows: a. distillate oil to 0.0015% sulfur by weight (15 ppm); b. #4 
residual oil within a range of 0.25 to 0.5% sulfur by weight; and c. #6 
residual oil within a range of 0.3 to 0.5% sulfur by weight.'' MANE-VU 
included the low sulfur fuel measure in the 2017 Ask because some 
states had not implemented it yet and the justifications for it 
determined in the first implementation period remained valid. As 
described in Section 3 of the Massachusetts SIP submittal, MassDEP met 
the requirements of Ask 3 during the first implementation period by 
generally adopting low-sulfur oil regulations in the first planning 
period. Massachusetts adopted 310 CMR 7.05, ``Fuels All Districts'' 
which was approved by EPA into the Massachusetts SIP on September 19, 
2013 (78 FR 57487).
    MANE-VU Ask 4 is: ``EGUs and other large point emission sources 
larger than 250 MMBTU per hour heat input that have switched operations 
to lower emitting fuels--pursue updating permits, enforceable 
agreements, and/or rules to lock-in lower emission rates for 
SO<INF>2</INF>, NO<INF>X</INF> and PM. The permit, enforcement 
agreement, and/or rule can allow for suspension of the lower emission 
rate during natural gas curtailment.'' Massachusetts explains that 
MANE-VU chose this measure because the lower cost of natural gas had 
made switching to natural gas reasonable for many facilities resulting 
in significant visibility improvements. Also, the FLMs recommended 
during consultation that MANE-VU secure these visibility gains.
    The threshold of 250 MMBTU per hour heat input was based on prior 
BART analysis. Because there are no longer any large coal burning units 
in Massachusetts, this Ask pertains only to oil burning units. 
Massachusetts identified no dual/multi-fuel units larger than 250 
MMBTU/hr that had made a physical change to switch to a cleaner fuel. 
All such dual/multi-fuel units are either continuing to burn a mix of 
fuels or are choosing to maintain their ability to do so in the future.
    MANE-VU Ask 5 is: ``Where emission rules have not been adopted, 
control NO<INF>X</INF> emissions for peaking combustion turbines that 
have the potential to operate on high electric demand days by: a. 
Striving to meet NO<INF>X</INF> emissions standard of no greater than 
25 ppm at 15% O<INF>2</INF> for natural gas and 42 ppm at 15% 
O<INF>2</INF> for fuel oil but at a minimum meet NO<INF>X</INF> 
emissions standard of no greater than 42 ppm at 15% O<INF>2</INF> for 
natural gas and 96 ppm at 15% O<INF>2</INF> for fuel oil; b. Performing 
a four-factor analysis for reasonable installation or upgrade to 
emission controls; or c. Obtaining equivalent alternative emission 
reductions on high electric demand days.''
    Massachusetts explains that ``High electric demand days are days 
when higher than usual electrical demands bring additional generation 
units online, many of which are infrequently operated and may have 
significantly higher emission rates than the rest of the generation 
fleet. Peaking combustion turbine is defined for the purposes of this 
`Ask' as a turbine capable of generating 15 megawatts or more, that 
commenced operation prior to May 1, 2007, is used to generate 
electricity all or part of which is delivered to the electric power 
distribution grid for commercial sale and that operated less than or 
equal to an average of 1752 hours (or 20%) per year during 2014 to 
2016; MANE-VU found a correlation between high electric demand days 
(HEDDs) and the 20% most impaired days at Class I areas. Because 
smaller turbines have the ability to respond to peak electrical demand 
and some of these units are not well controlled by existing rules 
(i.e., have a higher emission rate per unit of energy), MANE-VU found 
that controlling these units (or providing equivalent reductions on 
HEDDs) was a reasonable strategy for reducing NO<INF>X</INF> emissions 
on the most impaired days.''
    Massachusetts identified 25 turbines rated at 15 MW or higher that 
were operational prior to 2007 that sold electricity to the grid and 
that operated less than an average of 1752 hours per year during 2014-
2016. These 25 turbines are listed in Table 6-3 along with their 
current emission limits. On March 9, 2018, MassDEP revised 310 CMR 7.19 
Reasonably Available Control Technology (RACT) for Sources of Oxides of 
Nitrogen (NO<INF>X</INF>) to establish more stringent emissions limits 
for stationary turbines at major sources. With these revisions 
Massachusetts RACT now meets Ask 5 ``striving'' limits for combined 
cycle turbines and ``minimum'' limits for simple cycle turbines. 
However, the 2018 RACT rule also included an exemption for units with a 
capacity factor less than 10% based on the most recent 3-year average, 
as codified in 310 CMR 7.19(1)(d).
    Almost all the turbines subject to Ask 5 fall below the 10% 
capacity factor because they all run very infrequently. If in the 
future, they exceed the 10% capacity factor limit then they will be 
subject to the SIP-approved RACT limits of 310 CMR 7.19 and will 
therefore meet Ask 5 (except for Woodland 10 and Doreen 10 which are 
not located at

[[Page 1497]]

facilities that are major sources and are therefore not subject to 310 
CMR 7.19). The turbines that are exempt from the 2018 RACT limits are 
still subject to MassDEP's 1995 RACT limits, however. Table 6-4 in 
MassDEP's submission compares the 1995 and 2018 RACT limits to Ask 5, 
showing that the 1995 RACT limits meet the Ask 5 minimum limits for 
combined cycle turbines, although not for simple cycle turbines. 
MassDEP explains that, as a result, 14 of the 25 turbines therefore 
meet the Ask 5 limits through either 1995 RACT limits for combined 
cycle turbines or through BACT permit limits. For the remaining 11 
turbines that do not meet the Ask 5 limits, Massachusetts has chosen to 
address the Ask by demonstrating emission reductions from Brayton Point 
Station (Units 1, 2, and 3) and Solutia that more than offset the 
emissions from these 11 turbines,\57\ as allowed under the Ask.
---------------------------------------------------------------------------

    \57\ See Massachusetts Regional Haze SIP Submission at 83-94.
---------------------------------------------------------------------------

    MANE-VU Ask 6 is: ``Each State should consider and report in their 
SIP measures or programs to: (a) decrease energy demand through the use 
of energy efficiency, and (b) increase the use within their state of 
Combined Heat and Power (CHP) and other clean Distributed Generation 
technologies including fuel cells, wind, and solar.''
    Massachusetts has taken numerous actions to decrease energy demand 
through energy efficiency and has been named the most energy efficient 
state in the nation by the American Council for an Energy-Efficient 
Economy (ACEEE) for nine consecutive years. Massachusetts ranks second 
in electric efficiency program spending per capita (at over four times 
the national average). Massachusetts energy efficiency efforts will 
continue through the second regional haze implementation period and 
will achieve emissions reductions beyond those required in the MANE-VU 
Statement. Key features of the Massachusetts energy efficiency strategy 
and efforts to expand non-polluting sources of energy and include 
energy efficiency, clean energy, solar carve-out, Solar Massachusetts 
Renewable Target (SMART) Program, Clean Energy Standard (310 CMR 7.75), 
Regional Greenhouse Gas Initiative (RGGI), combined heat and power 
(CHP), clean peak energy standard (CPS), offshore wind power, and 
hydroelectric power. Though not part of the SIP, these programs and 
initiatives have already achieved substantial emissions reductions and 
will continue to contribute to visibility improvements in Class I areas 
through 2028 and beyond.
b. The EPA's Evaluation of Massachusetts' Response to the Six MANE-VU 
Asks and Compliance with Sec.  51.308(f)(2)(i)
    The EPA is proposing to find that Massachusetts has satisfied the 
requirements of Sec.  51.308(f)(2)(i) related to evaluating sources and 
determining the emission reduction measures that are necessary to make 
reasonable progress by considering the four statutory factors. We are 
proposing to find that Massachusetts has satisfied the four-factor 
analysis requirement through its analysis and actions to address MANE-
VU Asks 2 and 3. We also propose to find that Massachusetts reasonably 
concluded that it satisfied all six Asks.
    As explained above, Massachusetts relied on MANE-VU's technical 
analyses and framework (i.e., the Asks) to select sources and form the 
basis of its long-term strategy. MANE-VU conducted an inventory 
analysis to identify the source sectors that produced the greatest 
amount of SO<INF>2</INF> and NO<INF>X</INF> emissions in 2011; 
inventory data were also projected to 2018. Based on this analysis, 
MANE-VU identified the top-emitting sectors for each of the two 
pollutants, which for SO<INF>2</INF> include coal-fired EGUs, 
industrial boilers, oil-fired EGUs, and oil-fired area sources 
including residential, commercial, and industrial sources. Major-
emitting sources of NO<INF>X</INF> include on-road vehicles, non-road 
vehicles, and EGUs.\58\ The RPO's documentation explains that ``[EGUs] 
emitting SO<INF>2</INF> and NO<INF>X</INF> and industrial point sources 
emitting SO<INF>2</INF> were found to be sectors with high emissions 
that warranted further scrutiny. Mobile sources were not considered in 
this analysis because any ask concerning mobile sources would be made 
to EPA and not during the intra-RPO and inter-RPO consultation process 
among the states and tribes.'' \59\ EPA proposes to find that 
Massachusetts reasonably evaluated the two pollutants--SO<INF>2</INF> 
and NO<INF>X</INF>--that currently drive visibility impairment within 
the MANE-VU region and that it adequately explained and supported its 
decision to focus on these two pollutants through its reliance on the 
MANE-VU technical analyses cited in its submission.
---------------------------------------------------------------------------

    \58\ See Appendix 2 ``Contributions to Regional Haze in the 
Northeast and Mid-Atlantic United States: Mid-Atlantic/Northeast 
Visibility Union (MANE-VU) Contribution Assessment. NESCAUM. August 
2006.''
    \59\ See Appendix 22 ``Mid-Atlantic/Northeast U.S. Visibility 
Data, 2004-2019 (2nd RH SIP Metrics). MANE-VU (prepared by Maine 
Department of Environmental Protection). January 21, 2021 
revision.''
---------------------------------------------------------------------------

    Section 51.308(f)(2)(i) requires states to evaluate and determine 
the emission reduction measures that are necessary to make reasonable 
progress by applying the four statutory factors to sources in a control 
analysis. As explained previously, the MANE-VU Asks are a mix of 
measures for sectors and groups of sources identified as reasonable for 
states to address in their regional haze plans. Several of the Asks 
include analyses of emissions controls, and Massachusetts identifies 
numerous existing controls that are in the SIP and are included in the 
long-term strategy. Additionally, Ask 2 (requesting four-factor 
analyses be conducted) and Ask 3 (requesting adoption of low-sulfur 
fuel oil) specifically demonstrate Massachusetts' consideration of the 
statutory factors and together allow the EPA to determine that 
Massachusetts' SIP is sufficient to satisfy (f)(2)(i). For example, 
Massachusetts provided information on the four statutory factors for 
the identified source that continues to operate--an oil-fired EGU and 
included new fuel sulfur limits for that source in the SIP. See ``Four 
Factor Analysis Canal Unit 1, Canal Generating Station, Sandwich, MA'' 
in Appendix 31. While MANE-VU formulated the Asks to be ``reasonable 
emission reduction strategies'' to control emissions of visibility 
impairing pollutants,\60\ EPA believes that Asks 2 and 3, in 
particular, engage with the requirement that states determine the 
emission reduction measures that are necessary to make reasonable 
progress through consideration of the four factors. As laid out in 
further detail below, the EPA is proposing to find that MANE-VU's four-
factor analysis conducted to support the emission reduction measures in 
Ask 3 (ultra-low sulfur fuel oil Ask), in conjunction with 
Massachusetts' supplemental analysis and explanation of how it has 
complied with Ask 2 (perform four-factor analysis) satisfy the 
requirement of Sec.  51.308(f)(2)(i). The emission reduction measures 
that are necessary to make reasonable progress must be included in the 
long-term strategy, i.e., in Massachusetts' SIP. 40 CFR 51.308(f)(2).
---------------------------------------------------------------------------

    \60\ Id.
---------------------------------------------------------------------------

    Massachusetts asserted that it satisfies Ask 1 because its SIP-
approved regulations applicable to EGU boilers include year-round 
emission limits and because it already requires that controls be run 
whenever technically feasible. Air Plan Approvals that MassDEP has 
issued for these units set short-term NO<INF>X</INF> emissions limits 
in lbs/hr or

[[Page 1498]]

concentration. EPA thus proposes to find that Massachusetts reasonably 
concluded that it has satisfied Ask 1.
    Ask 2 addresses the sources MANE-VU determined have the potential 
for larger than, or equal to, 3.0 Mm<SUP>-1</SUP> visibility impact at 
any MANE-VU Class I area; the Ask requests MANE-VU states to conduct 
four-factor analyses for the specified sources within their borders. 
This Ask explicitly engages with the statutory and regulatory 
requirement to determine reasonable progress based on the four factors; 
MANE-VU considered it ``reasonable to have the greatest contributors to 
visibility impairment conduct a four-factor analysis that would 
determine whether emission control measures should be pursued and what 
would be reasonable for each source.'' \61\
---------------------------------------------------------------------------

    \61\ See Appendix 20 ``MANE-VU Regional Haze Consultation Report 
and Consultation Documentation--Final.''
---------------------------------------------------------------------------

    As an initial matter, EPA does not generally agree that 3.0 
Mm<SUP>-1</SUP> visibility impact is a reasonable threshold for source 
selection. The RHR recognizes that, due to the nature of regional haze 
visibility impairment, numerous and sometimes relatively small sources 
may need to be selected and evaluated for control measures in order to 
make reasonable progress. See 2021 Clarifications Memo at 4. As 
explained in the 2021 Clarifications Memo, while states have discretion 
to choose any source selection threshold that is reasonable, ``[a] 
state that relies on a visibility (or proxy for visibility impact) 
threshold to select sources for four-factor analysis should set the 
threshold at a level that captures a meaningful portion of the state's 
total contribution to visibility impairment to Class I areas.'' 2021 
Clarifications Memo at 3. In this case, the 3.0 Mm<SUP>-1</SUP> 
threshold identified only two sources in Massachusetts (and only 22 
across the entire MANE-VU region), indicating that it may be 
unreasonably high.
    MANE-VU identified two units in Massachusetts with potential 
impacts of 3.0 Mm-1 or greater based on 2015 emissions: Brayton Point 
Unit 4 and Canal Station Unit 1. Brayton Point was a coal-fired EGU 
facility (ORISPL 01619; MassDEP AQID 1200061). All four of the coal-
fired units at Brayton Point, including Unit 4, ceased operation in 
2017 and the permits were revoked on December 6, 2017.\62\
---------------------------------------------------------------------------

    \62\ See Appendix 37, MassDEP letter from Thomas Cushing, Chief, 
Permit Section, Bureau of Air & Waste to Robert Vasconcelos, 
Director, Brayton Point Energy, LLC. December 6, 2017.
---------------------------------------------------------------------------

    Canal Station (ORISPL 1599; MassDEP AQID 1200054) operates two 
steam electric generating units. Unit 1 is a Babcock & Wilcox boiler 
that fires No. 6 fuel oil, with a permitted maximum sulfur content of 
0.5 percent by weight (wt%) as the sole operational fuel, with No. 2 
fuel oil as a startup/ignition fuel. Unit 1 has an approximate maximum 
heat input rate of 5,083 million British thermal units per hour (MMBtu/
hr) and a generating capacity of approximately 560 (net) megawatts 
(MW). Unit 1 is equipped with low-NO<INF>X</INF> burners, overfire air 
ports, flue gas recirculation (FGR), and Selective Catalytic Reduction 
(SCR) for the control of NO<INF>X</INF> emissions. PM emissions are 
controlled by an Electrostatic Precipitator (ESP). The emission 
controls installed on Unit 1 are necessary to achieve compliance with 
the applicable emission limits under 310 CMR 7.29 and Air Plan 
Approvals issued pursuant to 310 CMR 7.02. The governing 
NO<INF>X</INF>, SO<INF>2</INF>, and PM emission limits for Unit 1 are 
summarized in Table 6-1 of the Massachusetts SIP submittal.
    Pursuant to Ask 2, MassDEP requested a four-factor analysis from 
the owner of Canal Unit 1, which the owner submitted on September 19, 
2020.\63\ With respect to NO<INF>X</INF> emissions, the analysis 
concludes that Canal Unit 1's existing controls (low NO<INF>X</INF> 
burners, overfire air ports, FGR, and SCR) are the most stringent 
available and that there are no other add-on controls commercially 
available to reduce NO<INF>X</INF> emissions from Canal Unit 1. The 
analysis explains that Canal Unit 1 has operated well below 10% 
capacity factor in recent years, is subject to NO<INF>X</INF> emission 
limits pursuant to 310 CMR 7.29 when operating at this level and is not 
expected to increase its capacity factor in the future. If Canal Unit 1 
did exceed 10% capacity factor, the higher number of hours would result 
in better performance of the SCR and, thereby, reduce NO<INF>X</INF> 
emissions rates by at least 50% below the current permitted 
NO<INF>X</INF> limits. Furthermore, if Canal Unit 1 exceeded 10% 
capacity factor, it would automatically become subject to the lower 
NO<INF>X</INF> limit in MassDEP's NO<INF>X</INF> RACT regulations (310 
CMR 7.19). Infrequent operation limits the effectiveness of the 
existing controls, however. At its current and expected low capacity 
factor, meeting NO<INF>X</INF> emission limits below the existing 310 
CMR 7.29 limits would be unreasonable due to emissions that occur 
during startup prior to operation of the SCR. The analysis concludes 
that no further NO<INF>X</INF> control measures at Canal Unit 1 are 
necessary to make reasonable progress.
---------------------------------------------------------------------------

    \63\ See Appendix 31, ``Four Factor Analysis Canal Unit 1, Canal 
Generating Station, Sandwich, MA . . .''
---------------------------------------------------------------------------

    With respect to SO<INF>2</INF> emissions, the four-factor analysis 
concludes that conversion to natural gas is not technically feasible 
due to supply limitations but that use of 0.3% sulfur No.6 fuel oil 
(rather than the 0.5% sulfur allowed under Massachusetts' low sulfur 
fuel regulations at 310 CMR 7.05) is technically feasible and reduces 
SO<INF>2</INF> emissions by 40% at a cost of $10,000 per ton of 
SO<INF>2</INF> reduced. While the analysis concludes that the cost of 
using 0.3 wt% sulfur No. 6 oil would not be considered reasonable, the 
owner nonetheless committed to purchasing 0.3 wt% No. 6 fuel oil 
following the depletion of the current fuel inventory because the 
MANEVU Regional Haze Consultation Report identifies sulfates from 
SO<INF>2</INF> emissions as the primary driver behind visibility 
impairment in the region. See June 15, 2022, MassDEP Regional Haze SIP 
Revision for Massachusetts Supplement.\64\
---------------------------------------------------------------------------

    \64\ See MassDEP letter to EPA ``Subject: Regional Haze SIP 
Revision for Massachusetts--supplement'' and its attachment MassDEP 
letter to Canal Generating LLC, Air Quality Plan Approval.
---------------------------------------------------------------------------

    The four-factor analysis also evaluates the use of ultra-low sulfur 
diesel (ULSD) and retrofitting with a spray dry absorber for 
SO<INF>2</INF> control and concludes that, while technically feasible, 
the costs of compliance in each case (beginning at $21,000 per ton of 
SO<INF>2</INF> reduced) mean that neither measure is necessary for 
reasonable progress. The analysis also evaluated particulate matter 
emissions and concludes that they are well controlled with an 
electrostatic precipitator (ESP) and burning 0.3 wt% sulfur fuel. While 
adding a fabric filter and using ULSD is feasible, the costs are 
$50,000 and $170,000 per ton of SO<INF>2</INF> reduced, respectively 
and, the ESP would reduce the efficiency of the unit by 0.5% and 
generate 52 tons of waste per year.
    Based on Canal's commitment to use 0.3% sulfur content fuel oil, 
MassDEP requested that the Permittee submit a permit application to 
require its use. Subsequently, MassDEP modified Canal's Plan Approval 
to provide that the sulfur content of No. 6 fuel oil purchased for Unit 
1 shall not exceed 0.3% by weight. MassDEP has requested that EPA 
approve it into the SIP, which EPA proposes to do in today's action.
    The EPA proposes to find that Massachusetts reasonably determined 
it has satisfied Ask 2. As explained above, we do not generally agree 
that a 3.0 Mm<SUP>-</SUP>\1\ threshold for selecting sources for four-
factor analysis results in a set of sources to evaluate that will 
result in

[[Page 1499]]

potential and meaningful reduction of the state's contribution to 
visibility impairment. MANE-VU's threshold identified two sources, only 
one of which continues to operate and combust the same fuel. However, 
in this particular instance we propose to find that Massachusetts' 
additional information and explanation indicate that the state has 
conducted a reasonable examination of its sources, reasonably concluded 
that the four-factor analysis for its remaining impacting source is 
satisfactory, and accurately concluded the additional SO<INF>2</INF> 
controls further limiting fuel oil sulfur content are reasonable 
emission reductions. EPA is basing this proposed finding on the State's 
examination of its largest operating EGU and ICI sources, at the time 
of SIP submission, and on the emissions from and controls that apply to 
those sources, as well as on Massachusetts' existing SIP-approved 
NO<INF>X</INF> and SO<INF>2</INF> rules that effectively control 
emissions from the largest contributing stationary-source sectors.
    Ask 3, which addresses the sulfur content of heating oil used in 
MANE-VU states, is based on a four-factor analysis for the heating oil 
sulfur reduction regulations contained in that Ask; specifically, for 
the control strategy of reducing the sulfur content of distillate oil 
to 15 ppm. As described in Section 3 of the Massachusetts SIP 
submittal, MassDEP met the requirements of Ask 3 during the first 
implementation period by generally adopting low-sulfur oil regulations 
in the first planning period. Massachusetts adopted 310 CMR 7.05, 
``Fuels All Districts.'' The regulation limited the Statewide sulfur 
content of distillate oil to 500 parts per million (ppm) from July 1, 
2014, through June 30, 2018, and then to 15 ppm starting July 1, 2018. 
The regulation also sets the sulfur in fuel limit for No. 6 residual 
oil, starting July 1, 2018, at 0.5% by weight Statewide, except for the 
Berkshire Air Pollution Control District (APCD), which encompasses the 
Towns and Cities in Berkshire County, the westernmost county in the 
Commonwealth. The Berkshire APCD has a 1974 legislative exemption 
allowing sources in this district to burn up to 2.2% sulfur residual 
oil.\65\ Therefore, the regulation does not explicitly require lower 
sulfur residual oil in the Berkshire APCD due to the existing law. A 
legislative change would be needed for MassDEP to apply the lower 
sulfur residual oil limits for this district. Despite the existing 
legislative exemption, however, MassDEP expects that the majority of 
residual oil burned in the Berkshire APCD will have a reduced sulfur 
content because the suppliers in Massachusetts and the surrounding 
states will need to supply lower sulfur residual oil for sale in those 
other APCDs and states. See also 77 FR 30932.
---------------------------------------------------------------------------

    \65\ Massachusetts Chapter 353 of the Acts of 1974.
---------------------------------------------------------------------------

    The EPA proposes to find that Massachusetts reasonably relied on 
MANE-VU's four-factor analysis for a low-sulfur fuel oil regulation, 
which engaged with each of the statutory factors and explained how the 
information supported a conclusion that a 15 ppm-sulfur fuel oil 
standard for fuel oils is reasonable. Massachusetts' SIP-approved 
ultra-low sulfur fuel oil rule is consistent with Ask 3's sulfur 
content standards for the three types of fuel oils (distillate oil, #4 
residual oil, #6 residual oil). EPA therefore proposes to find that 
Massachusetts reasonably determined that it has satisfied Ask 3.
    Massachusetts concluded that no additional updates were needed to 
meet Ask 4, which requests that MANE-VU states pursue updating permits, 
enforceable agreements, and/or rules to lock-in lower emission rates 
for sources larger than 250 MMBtu per hour that have switched to lower 
emitting fuels. As explained above, Massachusetts has asserted that 
there are no longer any large coal burning units in Massachusetts, 
meaning that this Ask pertains only to oil burning units. MA identified 
no dual/multi-fuel units larger than 250 MMBTU/hr that had made a 
physical change to switch to a cleaner fuel. All such dual/multi-fuel 
units are either continuing to burn a mix of fuels or are choosing to 
maintain their ability to do so in the future. In addition, modified 
units in Massachusetts are required to amend their permits through the 
New Source Review (NSR) process if they plan to switch back to coal or 
a fuel that will increase emissions. A change in fuel, unless already 
allowed in the permit, would be a modification.
    Thus, given the permitting and regulatory requirements outlined 
above, including the fact that sources that have switched fuel are 
required to revise their permits to reflect the change, that state 
rules make any proposed reversion difficult by requiring permitting and 
other control analyses, including NSR, the EPA proposes to find that 
Massachusetts reasonably determined it has satisfied Ask 4.
    Ask 5 addresses NO<INF>X</INF> emissions from peaking combustion 
turbines that have the potential to operate on high electric demand 
days. Massachusetts explains that it has SIP-approved regulations to 
control peaking combustion turbines that have the potential to operate 
on high electric demand days. The Ask requests states to ``strive'' for 
NO<INF>X</INF> emission standards of no greater than 25 ppm for natural 
gas and 42 ppm for fuel oil, or at a minimum, NO<INF>X</INF> emissions 
standards of no greater than 42 ppm for natural gas and 96 ppm at for 
fuel oil. Massachusetts RACT requirements approved into the MA SIP on 
October 15, 2020 (85 FR 65236) meet Ask 5 ``striving'' limits for 
combined cycle turbines and ``minimum'' limits for simple cycle 
turbines. However, the 2018 RACT rule also included an exemption for 
units with a capacity factor less than 10% based on the most recent 3-
year average. As shown in Table 6-3 of the Massachusetts SIP submittal, 
most of the turbines subject to Ask 5 fall below the 10% capacity 
factor because they all run very infrequently. If in the future they 
exceed the 10% capacity factor limit, then they will be subject to the 
RACT limits of 310 CMR 7.19 and will therefore meet Ask 5 (except for 
Woodland 10 and Doreen 10 which are not located at facilities that are 
major sources and are therefore not subject to 310 CMR 7.19). The 
turbines that are exempt from the 2018 RACT limits are still subject to 
MassDEP's 1995 RACT limits. For combined cycle turbines, the 1995 RACT 
limits meet Ask 5 minimum required limits for oil and gas, but the 
simple cycle limits are slightly higher at 100 ppm compared to the Ask 
5 minimum of 96 ppm.
    Ask 5 included an option to achieve equivalent alternative emission 
reductions for those combustion turbines whose limits do not match the 
``minimum'' limits in the Ask. The retirement of Brayton Point 1-2-3 
and repowering of Solutia Boiler 11 each provide alternative 
SO<INF>2</INF> or NO<INF>X</INF> emission reductions, respectively, on 
HEDDs that are far larger than any NO<INF>X</INF> reductions possible 
from the turbines that do not already meet Ask 5 (156 and 128 tons/year 
vs. 25 tons/year). Furthermore, the annual SO<INF>2</INF> emission 
reductions from Brayton Point 1-2-3 (785 tons/year) and Solutia Boiler 
11 (847 tons/year combined SO<INF>2</INF> and NO<INF>X</INF>) are each 
sufficiently large to offset all the annual turbine NO<INF>X</INF> 
emissions (51 tons per year).
    Therefore, the permanent retirement of Brayton 1-2-3 and repowering 
of Solutia Boiler 11 each satisfies the Ask for the remaining 11 
turbines not covered by the most recent MassDEP RACT rule. Because the 
Solutia Boiler 11 repowering and Brayton 1-2-3 retirements offset over 
100% of the emissions from the 11 turbines on HEDDs, they exceed the 
visibility improvement requirements of Ask 5. In

[[Page 1500]]

addition, because MassDEP has permitted new units (e.g., Footprint \1/
2\, Canal 3, and West Medway \4/5\) that are much cleaner than the 11 
turbines, these new units likely will displace some of the power 
generating capacity of the older turbines units and thereby further 
reduce HEDD emissions from the turbines that do not meet Ask 5.
    For the majority of combustion turbines identified in the Ask, the 
RACT levels adopted by Massachusetts comply with the minimum requested 
by this Ask. For those turbines that do not meet the minimum limits, 
MassDEP has identified alternative emission reductions obtained through 
the retirement of Brayton 1-2-3 and the repowering of Solution Boiler 
11 that more than make up the difference. Therefore, EPA proposes to 
find that Massachusetts reasonably concluded that its existing 
regulations comply with Ask 5.
    Finally, with regard to Ask 6, Massachusetts has taken numerous 
actions to decrease energy demand through energy efficiency and has 
been named the most energy efficient state in the nation by the 
American Council for an Energy-Efficient Economy (ACEEE) for nine 
consecutive years. The EPA is proposing to find that Massachusetts has 
satisfied Ask 6's request to consider and report in its SIP measures or 
programs related to energy efficiency, cogeneration, and other clean 
distributed generation technologies.
    In sum, the EPA is proposing to find--based on Massachusetts' 
participation in the MANE-VU planning process, how it has addressed the 
Asks, and the EPA's assessment of Massachusetts' emissions and point 
sources--that Massachusetts has complied with the requirements of Sec.  
51.308(f)(2)(i). Specifically, Massachusetts's application of MANE-VU 
Asks 1 2, and 3 engages with the requirement that states evaluate and 
determine the emission reduction measures necessary to make reasonable 
progress by considering the four statutory factors.
    EPA is proposing to find the state's approach meets the regulatory 
requirements for several reasons. Massachusetts reasonably evaluated 
and explained its decision to focus on SO<INF>2</INF> and 
NO<INF>X</INF> to address visibility impairment within the MANE-VU 
region. Massachusetts also adequately supported that decision through 
reasonable reliance on the MANE-VU technical analyses cited in its 
submission. In addition, Massachusetts selected the sources with the 
greatest modeled impacts on visibility and also adequately responded to 
comments to consider sources identified by the FLMs through the 
consultation process. Massachusetts's submittal also includes four-
factor analyses and demonstrates that the sources of SO<INF>2</INF> and 
NO<INF>X</INF> within the state that would be expected to contribute to 
visibility impairment have small emissions of NO<INF>X</INF> and 
SO<INF>2</INF>, are subject to stringent SIP-approved emission control 
measures, or both. In addition, Massachusetts's SIP-approved sulfur in 
fuel rule sets stringent limits for sulfur content and SO<INF>2</INF> 
emissions for fuels. The Massachusetts SIP submittal also includes a 
plan approval for Canal Generating Station, requiring fuel oil 
purchased for EU1 be restricted to 0.3% sulfur content limit.
    EPA proposes to find that Massachusetts's SIP submittal satisfies 
the requirements that states determine the emission reduction measures 
that are necessary to make reasonable progress by considering the four 
factors, and that their long-term strategies include the enforceable 
emission limitations, compliance schedules, and other measures 
necessary to make reasonable progress.
c. Additional Long-Term Strategy Requirements
    The consultation requirements of Sec.  51.308(f)(2)(ii) provide 
that states must consult with other states that are reasonably 
anticipated to contribute to visibility impairment in a Class I area to 
develop coordinated emission management strategies containing the 
emission reductions measures that are necessary to make reasonable 
progress. Section 51.308(f)(2)(ii)(A) and (B) require states to 
consider the emission reduction measures identified by other states as 
necessary for reasonable progress and to include agreed upon measures 
in their SIPs, respectively. Section 51.308(f)(2)(ii)(C) speaks to what 
happens if states cannot agree on what measures are necessary to make 
reasonable progress.
    Massachusetts participated in and provided documentation of the 
MANE-VU intra- and inter-RPO consultation processes, which included 
consulting with both MANE-VU and non-MANE-VU states about emissions 
from Massachusetts reasonably anticipated to contribute to visibility 
impairment in Class I areas within the MANE-VU area and in adjacent 
areas. The consultations addressed developing coordinated emission 
management strategies containing the emission reductions necessary to 
make reasonable progress at the Class I areas. Massachusetts addressed 
the MANE-VU Asks by providing information on the measures it has in 
place that satisfy each Ask.\66\ While Massachusetts did not receive 
any requests from non-MANE-VU states to consider additional measures to 
address visibility impairment in Class I areas outside MANE-VU, MANE-VU 
documented disagreements that occurred during consultation. For 
instance, MANE-VU noted in its Consultation Report that upwind states 
expressed concern regarding the analyses the RPO utilized for the 
selection of states for the consultation. MANE-VU agreed that these 
tools, as all models, have their limitations, but nonetheless deemed 
them appropriate. Additionally, there were several comments regarding 
the choice of the 2011 modeling base year. MANE-VU agreed that the 
choice of base year is critical to the outcome of the study. MANE-VU 
acknowledged that there were newer versions of the emission inventories 
and the need to use the best available inventory for each analysis. 
However, MANE-VU disagreed that the choice of these inventories was not 
appropriate for the analysis. Additionally, upwind states noted that 
they would not be able to address the MANE-VU Asks until they finalize 
their SIPs. MANE-VU believed the assumption of the implementation of 
the Asks from upwind states in its 2028 control case modeling was 
reasonable, and Massachusetts included both the 2028 base case and 
control case modeling results in its SIP, representing visibility 
conditions at Acadia National Park (Maine) assuming upwind states do 
not and do implement the Asks, respectively.
---------------------------------------------------------------------------

    \66\ See Appendix 20 ``MANE-VU Regional Haze Consultation 
Report.''
---------------------------------------------------------------------------

    In sum, Massachusetts participated in the MANE-VU intra- and inter-
RPO consultation and included in its SIP submittal the measures 
identified and agreed to during those consultations, thereby satisfying 
Sec.  51.308(f)(2)(ii)(A) and (B). Massachusetts satisfied Sec.  
51.308(f)(2)(ii)(C) by participating in MANE-VU's consultation process, 
which documented the disagreements between the upwind states and MANE-
VU and explained MANE-VU's reasoning on each of the disputed issues. 
Based on the entirety of MANE-VU's intra- and inter-RPO consultation 
and MANE-VU's and Massachusetts' responses to comments on the SIP 
submission and various technical analyses therein, we propose to 
determine that Massachusetts has satisfied the consultation 
requirements of Sec.  51.308(f)(2)(ii).
    The documentation requirement of Sec.  51.308(f)(2)(iii) provides 
that states

[[Page 1501]]

may meet their obligations to document the technical bases on which 
they are relying to determine the emission reductions measures that are 
necessary to make reasonable progress through an RPO, as long as the 
process has been ``approved by all State participants.'' As explained 
above, Massachusetts chose to rely on MANE-VU's technical information, 
modeling, and analysis to support development of its long-term 
strategy. The MANE-VU technical analyses on which Massachusetts relied 
are listed in the state's SIP submission and include source 
contribution assessments, information on each of the four factors and 
visibility modeling information for certain EGUs, and evaluations of 
emission reduction strategies for specific source categories. 
Massachusetts also provided supplemental information to further 
demonstrate the technical bases and emission information on which it 
relied on to determine the emission reductions measures that are 
necessary to make reasonable progress. Based on the documentation 
provided by the state, we propose to find Massachusetts satisfies the 
requirements of Sec.  51.308(f)(2)(iii).
    Section 51.308(f)(2)(iii) also requires that the emissions 
information considered to determine the measures that are necessary to 
make reasonable progress include information on emissions for the most 
recent year for which the state has submitted triennial emissions data 
to the EPA (or a more recent year), with a 12-month exemption period 
for newly submitted data. Massachusetts' SIP submission included 2017 
National Emissions Inventory (NEI) data for NO<INF>X</INF>, 
SO<INF>2</INF>, PM, VOCs and NH<INF>3</INF> and 2017 Air Markets 
Program Data (AMPD) emissions for NO<INF>X</INF> and SO<INF>2</INF>. 
Based on Massachusetts' consideration and analysis of the 2017 and 2019 
emission data in their SIP submittal, the EPA proposes to find that 
Massachusetts has satisfied the emissions information requirement in 
51.308(f)(2)(iii).
    We also propose to find that Massachusetts reasonably considered 
the five additional factors in Sec.  51.308(f)(2)(iv) in developing its 
long-term strategy. Pursuant to Sec.  51.308(f)(2)(iv)(A), 
Massachusetts noted that existing and ongoing state and federal 
emission control programs that contribute to emission reductions 
through 2028 would impact emissions of visibility impairing pollutants 
from point and nonpoint sources in the second implementation period. 
Massachusetts included in its SIP a comprehensive lists of control 
measures identifying the source category and corresponding Code of 
Massachusetts Regulations provisions.\67\
---------------------------------------------------------------------------

    \67\ See tables 6-13 of the MassDEP Regional Haze SIP--Final 
July 2021.
---------------------------------------------------------------------------

    Massachusetts' consideration of measures to mitigate the impacts of 
construction activities as required by Sec.  51.308(f)(2)(iv)(B) 
includes, in section 6.6 of its SIP submission, measures that 
Massachusetts has implemented to mitigate the impacts from such 
activities. Massachusetts has implemented standards that reduce 
fugitive dust emissions from construction, rules to address exhaust 
emissions including rules to limit the idling of vehicles and 
equipment, rules to reduce allowable smoke from on-road diesel engines, 
and general conformity rules.
    Pursuant to Sec.  51.308(f)(2)(iv)(C), source retirements and 
replacement schedules are addressed in section 6.7 of Massachusetts' 
submission. Source retirements and replacements were considered in 
developing the 2028 emission projections, with on the books/on the way 
retirements and replacements included in the 2028 projections. The EGU 
point sources included in the inventories used in the MANE-VU 
contribution assessment and that were subsequently retired are 
described in Section 4 of the Massachusetts' submission.
    In considering smoke management as required in 40 CFR 
51.308(f)(2)(iv)(D), Massachusetts explained, in section 6.8 of its 
submission, that it addresses smoke management through its air 
regulation at 310 CMR 7.07, which bans open burning in 22 urban 
municipalities and prohibits the use of open burning to clear 
commercial or institutional land for non-agricultural purposes. 
Prescribed burning is allowed upon specific permission from MassDEP. 
Massachusetts considers these efforts to be sufficient to protect 
visibility in the Class I areas affected by emission from Massachusetts 
source, including agricultural and forestry smoke.
    Massachusetts considered the anticipated net effect of projected 
changes in emissions as required by 51.308(f)(2)(iv)(E) by discussing, 
in Section 6.9 of its submission, the photochemical modeling for the 
2018-2028 period it conducted in collaboration with MANE-VU. The two 
modeling cases run were a 2028 base case, which considered only on-the-
books controls, and a 2028 control case that considered implementation 
of the MANE-VU Ask. The results of that modeling are shown as RPGs on 
the graphs in Section 2 and detailed in the presentation of RPGs in the 
MANE-VU visibility report. The 2028 inventory projections demonstrate a 
substantial reduction in emissions. The modeling shows that projected 
visibility at all potentially impacted Class I areas will remain well 
below the URP line in 2028 for the most impaired days and that there 
will be no degradation in visibility for the least impaired days.
    Because Massachusetts has reasonably considered each of the five 
additional factors, the EPA proposes to find that Massachusetts has 
satisfied the requirements of 40 CFR 51.308(f)(2)(iv).

F. Reasonable Progress Goals

    Section 51.308(f)(3) contains the requirements pertaining to RPGs 
for each Class I area. Because Massachusetts does not host a Class I 
area, it is not subject to either Sec.  51.308(f)(3)(i) or 
51.308(f)(3)(ii)(A). Section 51.308(f)(3)(ii)(B) requires that, if a 
state contains sources that are reasonably anticipated to contribute to 
visibility impairment in a Class I area in another state and the RPG 
for the most impaired days in that Class I area is above the URP, the 
upwind state must provide the same demonstration.
    Table 2-1 of Massachusetts' SIP submittal summarizes baseline 
visibility conditions (i.e., visibility conditions during the baseline 
period) for the most impaired and clearest days and the 2028 RPG for 
the most impaired days for Class I areas in or adjacent to the MANE-VU 
Region, as well as information on natural visibility conditions, the 
rate of progress described by the URP in 2017 and 2028, and the modeled 
2028 base case (representing visibility conditions in 2028 with 
existing controls). These visibility conditions, as well as the 2028 
reasonable progress goal for the clearest days, are also included in 
Appendix 21 of Massachusetts' SIP submission. As noted in the 
submission, the RPGs for all of the Class I areas in or adjacent to the 
MANE-VU region are well below their respective URP glidepaths. 
Therefore, Sec.  51.308(f)(3)(ii)(B) is not applicable to 
Massachusetts.

G. Monitoring Strategy and Other Implementation Plan Requirements

    Section 51.308(f)(6) specifies that each comprehensive revision of 
a state's regional haze SIP must contain or provide for certain 
elements, including monitoring strategies, emissions inventories, and 
any reporting, recordkeeping and other measures needed to assess and 
report on visibility. Since Massachusetts does not contain any Class I 
areas, it is not required to submit the monitoring strategy referenced 
in 51.308(f)(6), nor

[[Page 1502]]

are the requirements in 51.308(f)(6)(i), (ii), and (iv) applicable.
    40 CFR 51.308(f)(6)(iii), however, applies to states with no Class 
I areas (such as Massachusetts) and requires them to include in their 
Regional Haze SIPs procedures by which monitoring data and other 
information are used in determining the contribution of emissions from 
within the state to visibility impairment at Class I areas in other 
states. Monitoring in Massachusetts that contributes data for assessing 
visibility is described in section 2.1 of the Massachusetts SIP 
submission. Visibility data analysis procedures are described in the 
MANE-VU visibility data report.\68\ Other procedures and data used for 
determining Massachusetts contribution to visibility impairment are 
described in section 5 of the Massachusetts SIP and the MANE-VU 
documents referenced. Two IMPROVE monitors in Massachusetts provide 
data to assess current visibility, track changes in visibility, and 
help determine the causes of visibility impairment in Class I areas in 
the region.
---------------------------------------------------------------------------

    \68\ See Appendix 22 ``Mid-Atlantic/Northeast U.S. Visibility 
Data, 2004-2019 (2nd RH SIP Metrics). MANE-VU (prepared by Maine 
Department of Environmental Protection). January 21, 2021 
revision.''
---------------------------------------------------------------------------

    Section 51.308(f)(6)(v) requires SIPs to provide for a statewide 
inventory of emissions of pollutants that are reasonably anticipated to 
cause or contribute to visibility impairment, including emissions for 
the most recent year for which data are available and estimates of 
future projected emissions. It also requires a commitment to update the 
inventory periodically. Massachusetts provides for emissions 
inventories and estimates for future projected emissions by 
participating in the MANE-VU RPO and complying with EPA's Air Emissions 
Reporting Rule (AERR). In 40 CFR part 51, subpart A, the AERR requires 
states to submit updated emissions inventories for criteria pollutants 
to EPA's Emissions Inventory System (EIS) every three years. The 
emission inventory data is used to develop the NEI, which provides for, 
among other things, a triennial state-wide inventory of pollutants that 
are reasonably anticipated to cause or contribute to visibility 
impairment.
    Section 4 of Massachusetts' submission includes tables of NEI data. 
The source categories of the emissions inventories included are: (1) 
Point sources, (2) nonpoint sources, (3) non-road mobile sources, and 
(4) on-road mobile sources. The point source category is further 
divided into AMPD point sources and non-AMPD point sources. 
Massachusetts included NEI emissions inventories for the following 
years: 2002 (one of the regional haze program baseline years), 2008, 
2011, 2014, and 2017; and for the following pollutants: SO<INF>2</INF>, 
NO<INF>X</INF>, PM<INF>10</INF>, PM<INF>2.5</INF>, VOCs, and 
NH<INF>3</INF>.
    Section 51.308(f)(6)(v) also requires states to include estimates 
of future projected emissions and include a commitment to update the 
inventory periodically. Massachusetts relied on the MANE-VU 2028 
emissions projections for MANE-VU states. MANE-VU completed two 2028 
projected emissions modeling cases--a 2028 base case that considers 
only on-the-books controls and a 2028 control case that considers 
implementation of the MANE-VU Asks.\69\
---------------------------------------------------------------------------

    \69\ See appendix 21 ``OTC MANE-VU 2011 Based Modeling Platform 
Support Document October 2018--Final.''
---------------------------------------------------------------------------

    The EPA proposes to find that Massachusetts has met the 
requirements of 40 CFR 51.308(f)(6) as described above, including 
through its continued participation in the MANE-VU RPO and its on-going 
compliance with the AERR, and that no further elements are necessary at 
this time for Massachusetts to assess and report on visibility pursuant 
to 40 CFR 51.308(f)(6)(vi). Massachusetts' SIP submittal also includes 
a commitment to update the statewide emissions inventory periodically.

H. Requirements for Periodic Reports Describing Progress Towards the 
Reasonable Progress Goals

    Section 51.308(f)(5) requires that periodic comprehensive revisions 
of states' Regional Haze plans also address the progress report 
requirements of 40 CFR 51.308(g)(1) through (5). The purpose of these 
requirements is to evaluate progress towards the applicable RPGs for 
any Class I area within the state and each Class I area outside the 
state that may be affected by emissions from within that state. 
Sections 51.308(g)(1) and (2) apply to all states and require a 
description of the status of implementation of all measures included in 
a state's first implementation period regional haze plan and a summary 
of the emission reductions achieved through implementation of those 
measures. Section 51.308(g)(3) applies only to states with Class I 
areas within their borders and requires such states to assess current 
visibility conditions, changes in visibility relative to baseline 
(2000-2004) visibility conditions, and changes in visibility conditions 
relative to the period addressed in the first implementation period 
progress report. Section 51.308(g)(4) applies to all states and 
requires an analysis tracking changes in emissions of pollutants 
contributing to visibility impairment from all sources and sectors 
since the period addressed by the first implementation period progress 
report. This provision further specifies the year or years through 
which the analysis must extend depending on the type of source and the 
platform through which its emission information is reported. Finally, 
Sec.  51.308(g)(5), which also applies to all states, requires an 
assessment of any significant changes in anthropogenic emissions within 
or outside the state that have occurred since the period addressed by 
the first implementation period progress report, including whether such 
changes were anticipated and whether they have limited or impeded 
expected progress towards reducing emissions and improving visibility.
    Massachusetts' submission describes the status of measures of the 
long-term strategy from the first implementation period. As a member of 
MANE-VU, Massachusetts considered the MANE-VU Asks and adopted 
corresponding measures into its long-term strategy for the first 
implementation period. The MANE-VU Asks were: (1) Timely implementation 
of Best Available Retrofit Technology (BART) requirements; (2) EGU 
controls including Controls at 167 Key Sources that most affect MANE-VU 
Class I areas; (3) Low sulfur fuel oil strategy; and (4) Continued 
evaluation of other control measures. Massachusetts met all the 
identified reasonable measures requested during the first 
implementation period. During the first planning period for regional 
haze, programs that were put in place focused on reducing 
SO<INF>2</INF> emissions. The reductions achieved led to vast 
improvements in visibility at the MANE-VU Federal Class I Areas due to 
reduced sulfates formed from SO<INF>2</INF> emissions. Massachusetts 
describes the control measures that help control the emissions of VOCs, 
NO<INF>X</INF>, PM and SO<INF>2</INF> from a wide range of sources in 
Section 3 of the Massachusetts' SIP submission and identifies BART and 
Alternative to BART requirements in Table 3-1. The state included 
periodic emission data that demonstrate a decrease in VOCs, 
NO<INF>X</INF>, PM and SO<INF>2</INF> emissions throughout the state.
    The EPA proposes to find that Massachusetts has met the 
requirements of 40 CFR 51.308(g)(1) and (2) because its SIP submission 
describes the measures included in the long-term

[[Page 1503]]

strategy from the first implementation period, as well as the status of 
their implementation and the emission reductions achieved through such 
implementation.
    Pursuant to Sec.  51.308(g)(4), in Section 4 of its submittal, 
Massachusetts provided a summary of emissions of NO<INF>X</INF>, 
SO<INF>2</INF>, PM<INF>10</INF>, PM<INF>2.5</INF>, VOCs, and 
NH<INF>3</INF> from all sources and activities, including from point, 
nonpoint, non-road mobile, and on-road mobile sources, for the time 
period from 2002 to 2017 in Section 4. With respect to sources that 
report directly to the EPA, Massachusetts also included AMPD state 
summary data for SO<INF>2</INF> and NO<INF>X</INF> emissions for 2018 
and 2019.
    The reductions achieved by Massachusetts emission control measures 
are seen in the emissions inventory. Based on Massachusetts' SIP 
submission, NO<INF>X</INF> emissions have continuously declined in 
Massachusetts from 2002 through 2017, especially in the point, nonroad 
and onroad mobile sectors. NO<INF>X</INF> emissions are expected to 
continue to decrease as fleet turnover occurs and the older more 
polluting vehicles and equipment are replaced by newer, cleaner ones. 
Emissions of SO<INF>2</INF> have shown a decline of 96% in 
Massachusetts over the period 2002 to 2017, particularly in the point, 
nonroad and onroad mobile sectors. Massachusetts attributes the 
reductions in point emissions to controls on EGUs that were part of the 
first implementation period, fuel switching from coal and oil to 
natural gas, MassDEP's low sulfur fuel rule, and the retirement of 
several large older coal and oil burning EGUs in the state. Since some 
components of the MANE-VU low sulfur fuel strategy were not implemented 
until 2018, and as MANE-VU states continue to adopt rules to implement 
the strategy, additional SO<INF>2</INF> emissions reductions have 
likely been obtained since 2017 and are expected to continue into the 
future.
    In Massachusetts' submission, table 4-3 shows a summary of 
PM<INF>10</INF> emissions from all NEI data categories point, nonpoint, 
non-road, and onroad for the period from 2002 to 2017 in Massachusetts. 
In Massachusetts, PM<INF>10</INF> emissions steadily decreased in the 
point, nonpoint, and nonroad categories for the period from 2002 to 
2017. The apparent increase in the onroad emissions is due to changes 
in emission inventory calculation methodologies, which resulted in 
higher particulate matter estimates. The variation in emissions in the 
nonpoint category is due to changes in calculation methodologies for 
residential wood burning and fugitive dust categories, which have 
varied significantly.
    Table 4-4 of Massachusetts' submission shows a summary of 
PM<INF>2.5</INF> emissions from all NEI data categories for the period 
from 2002 to 2017 in Massachusetts. PM<INF>2.5</INF> emissions steadily 
decreased in the nonroad category for the period from 2002 to 2014. The 
majority of reductions came from the nonpoint category, which 
Massachusetts attributes to fuel combustion switching from oil to 
natural gas. The decrease in nonroad PM<INF>2.5</INF> emissions is 
because of Federal new engine standards for nonroad vehicles and 
equipment. There is an overall decrease in onroad emissions due to 
Federal and State regulations. The increase in emissions in the onroad 
category from 2002 to 2008 is due to changes in emission inventory 
calculation methodologies and a model change, as previously explained, 
which resulted in higher fine particulate matter estimates.
    Table 4-7 of Massachusetts' submission shows VOC emissions from all 
NEI data categories for the period 2002 to 2017 in Massachusetts. VOC 
emissions have shown a steady decline in Massachusetts over this 
period. VOC decreases were achieved in all sectors due to Federal new 
engine standards for onroad and nonroad vehicles and equipment, the 
National and State low emission vehicle programs, SIP-approved area 
source rules such as consumer products, portable fuel containers, 
paints, autobody refinishing, asphalt paving applications, and solvent 
cleaning operations, and point source controls.
    Table 4-8 of Massachusetts' submission shows ammonia 
(NH<INF>3</INF>) emissions from all NEI data categories for the period 
2002 to 2017 in Massachusetts. Ammonia decreases were achieved in the 
onroad sector due to Federal new engine standards for vehicles and 
equipment. Nonpoint increases and decreases from 2002 to 2017 are due 
to reporting, grouping and methodology changes. There was little change 
to nonroad ammonia emissions. Overall, ammonia emissions have decreased 
from 2008 to 2017.
    The EPA is proposing to find that Massachusetts has satisfied the 
requirements of Sec.  51.308(g)(4) by providing emissions information 
for NO<INF>X</INF>, SO<INF>2</INF>, PM<INF>10</INF>, PM<INF>2.5</INF>, 
VOCs, and NH<INF>3</INF> broken down by type of source.
    Massachusetts uses the emissions trend data in the SIP submission 
to support the assessment that anthropogenic haze-causing pollutant 
emissions in Massachusetts have decreased during the reporting period 
and that changes in emissions have not limited or impeded progress in 
reducing pollutant emissions and improving visibility. The data 
Massachusetts presents for NO<INF>X</INF>, SO<INF>2</INF>, 
PM<INF>10</INF>, PM<INF>2.5</INF>, VOCs, and NH<INF>3</INF> show 
consistently declining emissions of those pollutants. Massachusetts 
concludes that no significant changes have occurred that have impeded 
progress in reducing emissions and improving visibility during the 
reporting period. The EPA is proposing to find that Massachusetts has 
met the requirements of Sec.  51.308(g)(5).

I. Requirements for State and Federal Land Manager Coordination

    Section 169A(d) of the Clean Air Act requires states to consult 
with FLMs before holding the public hearing on a proposed regional haze 
SIP, and to include a summary of the FLMs' conclusions and 
recommendations in the notice to the public. In addition, section 
51.308(i)(2)'s FLM consultation provision requires a state to provide 
FLMs with an opportunity for consultation that is early enough in the 
state's policy analyses of its emission reduction obligation so that 
information and recommendations provided by the FLMs can meaningfully 
inform the state's decisions on its long-term strategy. If the 
consultation has taken place at least 120 days before a public hearing 
or public comment period, the opportunity for consultation will be 
deemed early enough, but the opportunity for consultation must be 
provided at least sixty days before a public hearing or public comment 
period at the state level. Section 51.308(i)(2) also requires that the 
consultation include the opportunity for the FLMs to discuss their 
assessment of visibility impairment in any Class I area and their 
recommendations on the development and implementation of strategies to 
address visibility impairment. Section 51.308(i)(3) requires states, in 
developing their implementation plans, to include a description of how 
they addressed FLMs' comments.
    The states in the MANE-VU RPO conducted FLM consultation early in 
the planning process concurrent with the state-to-state consultation 
that formed the basis of the RPO's decision making process. As part of 
the consultation, the FLMs were given the opportunity to review and 
comment on the technical documents developed by MANE-VU. The FLMs were 
invited to attend the intra- and inter-RPO consultations calls among 
states and at least one FLM representative was documented to have 
attended seven intra-RPO meetings and all inter-RPO

[[Page 1504]]

meetings. Massachusetts participated in these consultation meetings and 
calls.\70\
---------------------------------------------------------------------------

    \70\ See Appendix 20 ``MANE-VU Regional Haze Consultation Report 
and Consultation Documentation--Final.''
---------------------------------------------------------------------------

    As part of this early engagement with the FLMs, on April 12, 2018, 
the NPS sent letters to the MANE-VU states requesting that they 
consider specific individual sources in their long-term strategies.\71\ 
NPS used an analysis of emissions divided by distance (Q/d) to estimate 
the impact of MANE-VU facilities. To select the facilities, NPS first 
summed 2014 NEI NO<INF>X</INF>, PM<INF>10</INF>, SO<INF>2</INF>, and 
SO<INF>4</INF> emissions and divided by the distance to a specified NPS 
mandatory Class I Federal area. NPS summed the Q/d values across all 
MANE-VU states relative to Acadia, Mammoth Cave and Shenandoah National 
Parks, ranked the Q/d values relative to each Class I area, created a 
running total, and identified those facilities contributing to 80% of 
the total impact at each NPS Class I area. NPS applied a similar 
process to facilities in Maine but relative to just Acadia National 
Park. NPS merged the resulting lists of facilities and sorted them by 
their states. NPS suggested that a state consider those facilities 
comprising 80% of the Q/d total, not to exceed the 25 top ranked 
facilities. The NPS identified 10 facilities in Massachusetts in this 
letter.\72\ Massachusetts included the NPS initial letter in its 
proposed SIP.\73\ In a subsequent letter dated October 22, 2018, NPS 
identified four municipal waste combustor facilities for which more 
control information was desired.\74\ Massachusetts detailed the 
emission controls and updates to the facilities to address the NPS's 
request for more information, as discussed previously.\75\
---------------------------------------------------------------------------

    \71\ Id.
    \72\ Id.
    \73\ Id.
    \74\ See Appendices 24 and 25.
    \75\ See Appendix 43, ``Summary of Public Comments and MassDEP 
Responses'' at page 6.
---------------------------------------------------------------------------

    On November 13, 2020, Massachusetts submitted a draft Regional Haze 
SIP to the U.S. Forest Service, the U.S. Fish and Wildlife Service, and 
the National Park Service for a 60-day review and comment period 
pursuant to 40 CFR 51.308(i)(2). Massachusetts received comments from 
the Forest Service and from the National Park Service by January 15, 
2021. Massachusetts responded to the FLM comments and included a 
summary of the responses in Section 7.3 of its submission to EPA, in 
accordance with Sec.  51.308(i)(3). In satisfaction of Sec.  
51.308(i)(4), Massachusetts explains that it will continue to consult 
with the FLMs through MANE-VU's planning process (including 
participation in regular Technical Support Committee meetings that 
include FLM participation in the development of progress reports and 
the regional strategy for future RH SIP revisions), MassDEP regulatory 
and permit notification emails (which provide notification of air 
quality regulation amendments, SIP revisions, major new source review 
permits, ambient air monitoring plans), and MassDEP air quality 
advisory committee meetings.
    On April 7, 2021, MassDEP issued a notice of public hearing and 
comments and the availability of the draft Regional Haze SIP revision 
for 2018-2028 on MassDEP's Public Notices and Hearings web page and on 
its SIP web page and emailed the notice to parties that have registered 
for the MassDEP public notice email list. The notice announced two 
video conference call public hearings on May 11, 2021 and the 
opportunity to submit written comments until May 14, 2021. Appendix 43 
of the Massachusetts SIP submittal contains a summary of public 
comments received and MassDEP's responses.
    For the reasons stated above, the EPA proposes to find that 
Massachusetts has satisfied the requirements under 40 CFR 51.308(i) to 
consult with the FLMs on its regional haze SIP for the second 
implementation period.

J. Other Required Commitments

    Massachusetts' July 22, 2021, SIP submission includes a commitment 
to revise and submit a regional haze SIP in 2028, and every ten years 
thereafter. The state's commitment includes submitting periodic 
progress reports in accordance with Sec.  51.308(f) and a commitment to 
evaluate progress towards the reasonable progress goal for each 
mandatory Class I Federal area located within the state and in each 
mandatory Class I Federal area located outside the state that may be 
affected by emissions from within the state in accordance with Sec.  
51.308(g).

V. Proposed Action

    The EPA is proposing to approve the ``Massachusetts Regional Haze 
State Implementation Plan Revision for the Second Planning Period 
(2018-2028)'', submitted July 22, 2021 and ``Regional Haze SIP Revision 
for Massachusetts--Supplement'' source specific requirements for Canal 
Generating Station, submitted May 26, 2022 as collectively satisfying 
the regional haze requirements for the second implementation period 
contained in 40 CFR 51.308(f), (g), and (i).

VI. Incorporation by Reference

    In this rule, the EPA is proposing to include in a final EPA rule 
regulatory text that includes incorporation by reference. In accordance 
with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by 
reference ``Regional Haze SIP Revision for Massachusetts--Supplement'' 
source specific requirements for Canal Generating Station (Permit 
number 21-AQ02F-011-APP), submitted May 26, 2022. The EPA has made, and 
will continue to make, these documents generally available through 
https://www.regulations.gov and at the EPA Region 1 Office (please 
contact the person identified in the FOR FURTHER INFORMATION CONTACT 
section of this preamble for more information).

VII. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the CAA and applicable 
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely proposes to approve state law as meeting Federal 
requirements and does not impose additional requirements beyond those 
imposed by state law. For that reason, this proposed action:
    <bullet> Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
    <bullet> Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
    <bullet> Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
    <bullet> Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
    <bullet> Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
    <bullet> Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
    <bullet> Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001); and

[[Page 1505]]

    <bullet> Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA.
    In addition, this proposed rulemaking action, pertaining to 
Massachusetts regional haze SIP submission for the second planning 
period, is not approved to apply on any Indian reservation land or in 
any other area where the EPA or an Indian tribe has demonstrated that a 
tribe has jurisdiction. In those areas of Indian country, the rule does 
not have tribal implications and will not impose substantial direct 
costs on tribal governments or preempt tribal law as specified by 
Executive Order 13175 (65 FR 67249, November 9, 2000).
    Executive Order 12898 (Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
Feb. 16, 1994) directs Federal agencies to identify and address 
``disproportionately high and adverse human health or environmental 
effects'' of their actions on minority populations and low-income 
populations to the greatest extent practicable and permitted by law. 
EPA defines environmental justice (EJ) as ``the fair treatment and 
meaningful involvement of all people regardless of race, color, 
national origin, or income with respect to the development, 
implementation, and enforcement of environmental laws, regulations, and 
policies.'' EPA further defines the term fair treatment to mean that 
``no group of people should bear a disproportionate burden of 
environmental harms and risks, including those resulting from the 
negative environmental consequences of industrial, governmental, and 
commercial operations or programs and policies.'' The air agency did 
not evaluate environmental justice considerations as part of its SIP 
submittal; the CAA and applicable implementing regulations neither 
prohibit nor require such an evaluation. EPA did not perform an EJ 
analysis and did not consider EJ in this action. Consideration of EJ is 
not required as part of this action, and there is no information in the 
record inconsistent with the stated goal of E.O. 12898 of achieving 
environmental justice for people of color, low-income populations, and 
Indigenous peoples.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Nitrogen dioxide, Ozone, Particulate matter, Sulfur oxides.

    Dated: December 20, 2023.
David Cash,
Regional Administrator, Region 1.
[FR Doc. 2023-28573 Filed 1-9-24; 8:45 am]
BILLING CODE 6560-50-P


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