[Federal Register Volume 89, Number 133 (Thursday, July 11, 2024)]
[Proposed Rules]
[Pages 56827-56847]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-14851]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R05-OAR-2022-0974; FRL-12039-01-R5]


Air Plan Approval; Minnesota; Second Period Regional Haze Plan

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 the Minnesota Pollution Control Agency (Minnesota) on 
December 20, 2022, as satisfying applicable requirements under the 
Clean Air Act (CAA) and EPA's Regional Haze Rule (RHR) for the 
program's second implementation period. Minnesota's 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. EPA is taking this action pursuant to 
sections 110 and 169A of the CAA.

DATES: Written comments must be received on or before August 12, 2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2022-0974 at https://www.regulations.gov, or via email to 
[email protected]. For comments submitted at Regulations.gov, 
follow the online instructions for submitting comments. Once submitted, 
comments cannot be edited or removed from the docket. EPA may publish 
any comment received to its public docket. Do not submit to EPA's 
docket at https://www.regulations.gov any information you consider to 
be confidential business information (CBI), Proprietary Business 
Information (PBI), 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. 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, 
PBI, or multimedia submissions, and general guidance on making 
effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Matt Rau, Air and Radiation Division 
(AR-18J), Environmental Protection Agency, Region 5, 77 West Jackson 
Boulevard, Chicago, Illinois 60604, (312) 886-6524, 
[email protected]. The EPA Region 5 office is open from 8:30 a.m. to 
4:30 p.m., Monday through Friday, excluding Federal holidays.

SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,'' 
``us,'' or ``our'' is used, we mean EPA.

Table of Contents

I. What action is 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. EPA's Evaluation of Minnesota's Regional Haze Submission for the 
Second Implementation Period
    A. Background on Minnesota's First Implementation Period SIP 
Submission
    B. Minnesota's Second Implementation Period SIP Submission and 
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
    1. Emission Measures Necessary To Make Reasonable Progress
    2. EPA's Evaluation of Minnesota's Compliance With 40 CFR 
51.308(f)(2)(i)
    3. 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. Environmental Justice Considerations
VI. Proposed Action
VII. Incorporation by Reference
VIII. Statutory and Executive Order Reviews

I. What action is EPA proposing?

    On December 20, 2022, Minnesota submitted a revision to its SIP to 
address regional haze for the second implementation period. Minnesota 
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. EPA proposes to find that the Minnesota Regional Haze SIP 
submission for the second implementation period meets the applicable 
statutory and regulatory requirements. Thus, EPA proposes to approve 
Minnesota's 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 EPA to 
promulgate regulations to assure reasonable progress toward meeting 
this national goal. CAA 169A(a)(4). On December 2, 1980, EPA 
promulgated regulations addressing visibility

[[Page 56828]]

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 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. EPA promulgated the 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 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, 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 a visibility impairment that is produced by a 
multitude of anthropogenic sources and activities that 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 (SO2), nitrogen oxides (NOX), and, in 
some cases, volatile organic compounds (VOC) and ammonia 
(NH3)). Fine particle precursors react in the atmosphere to 
form fine particulate matter (PM2.5), 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). 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, 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 those 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 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 35768, July 1, 1999). 
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\ 64 FR 
35721, July 1, 1999.
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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, 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 (dv) and reflect the anticipated visibility conditions at 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

[[Page 56829]]

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 
starting 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 35714 at 35731-32, July 1, 1999. 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 at 3084, January 10, 2017).
    \7\ 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, 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 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. 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.
    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, 
EPA issued ``Guidance on Regional Haze State Implementation Plans for 
the Second Implementation Period'' (``2019 Guidance'').\8\ On July 8, 
2021, EPA issued a memorandum containing ``Clarifications Regarding 
Regional Haze State Implementation Plans for the Second Implementation 
Period'' (``2021 Clarifications Memo'').\9\ Additionally, 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 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. 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 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 EPA Office 
of Air Quality Planning and Standards, Research Triangle Park (June 
3, 2020).
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    As 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 are state-
specific and that, based on state 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 (NAAQS) 
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. 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, 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

[[Page 56830]]

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 
action, the terms RPO and MJO are synonymous.
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    The Lake Michigan Air Directors Consortium (LADCO), 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 Midwest. 
LADCO member states are Illinois, Indiana, Michigan, Minnesota, Ohio, 
and Wisconsin. The LADCO Regional Haze Technical Workgroup also 
includes Tribes, Iowa, EPA, U.S. National Park 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, 40 CFR 51.308(f) lays 
out the process by which states determine what constitutes their long-
term strategies, with the order of the requirements in 40 CFR 
51.308(f)(1) through (3) generally mirroring the order of the steps in 
the reasonable progress analysis \14\ and (f)(4) through (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 then develops 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. 
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. See 
40 CFR 51.308(f)(2). 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) and (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 40 CFR 51.308(d), ``tracked the actual planning 
sequence.'' (82 FR 3078 at 3091, January 10, 2017).
    \15\ The five ``additional factors'' for consideration in 40 CFR 
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 40 CFR 
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 EPA according to the requirements applicable to all SIP 
revisions under the CAA and EPA's regulations. See CAA 169A(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 EPA finds that a state's SIP is incomplete 
or 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, EPA determined that all states contribute to visibility impairment 
in at least one Class I area, 64 FR 35714 at 35720-22, July 1, 1999, 
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.'' 64 FR 35714 at 35721, July 1, 1999.
    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 using, where appropriate, 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 40 CFR 
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

[[Page 56831]]

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 
40 CFR 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 
3078 at 3103-05, January 10, 2017.
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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://www.epa.gov/sites/default/files/2021-03/documents/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 percent clearest 
(the 20 percent of monitored days in a calendar year with the lowest 
values of the deciview index) and 20 percent most impaired days (the 20 
percent 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 percent clearest 
and 20 percent 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 to reach natural visibility 
conditions.
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    \17\ This action also refers to the 20 percent clearest and 20 
percent 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 3078 
at 3098 January 10, 2017: ``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.''
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    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, measured in dv, that would 
need to be achieved during each implementation period 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, 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 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 3078 at 3107 footnote 116, January 10, 2017.
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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 3078 at 3093, January 10, 
2017.
---------------------------------------------------------------------------

    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 40 CFR 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 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 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).
    The regulation 40 CFR 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 
SO2 and NOX 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

[[Page 56832]]

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.
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    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 (Q/d) 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). 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 to satisfy the 
CAA's reasonable progress mandate.'' 82 FR 3078 at 3091, January 10, 
2017. 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. 82 FR 3078 at 3088, January 10, 2017. 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.
---------------------------------------------------------------------------

    \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 
3078 at 3088, January 10, 2017. 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.
---------------------------------------------------------------------------

    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 emissions 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 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 emissions rate than a source has achieved or 
could potentially achieve using its existing measures should also 
consider lower emissions 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. 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. 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

[[Page 56833]]

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, 40 CFR 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.''
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    As explained above, 40 CFR 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 40 CFR 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 emissions rate, it may not be 
necessary to have those measures in the long-term strategy to prevent 
future emissions 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 3078 at 3108-09, January 10, 2017 (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 
40 CFR 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, 40 CFR 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 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 Nat'l Parks Conservation Ass'n v. EPA, 803 F.3d 151, 165 (3d 
Cir. 2015); Alaska Dep't of Envtl. Conservation v. EPA, 540 U.S. 
461, 485, 490 (2004).
---------------------------------------------------------------------------

    The four statutory factors (and potentially visibility) are used to 
determine what emission reduction measures for selected sources must be 
included in a state's long-term strategy for making reasonable 
progress. Additionally, the RHR at 40 CFR 51.308(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 (RAVI); (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 40 CFR 
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.
---------------------------------------------------------------------------

    Because the air pollution that causes regional haze crosses state 
boundaries, 40 CFR 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.

[[Page 56834]]

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). 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 3078 at 3091, January 10, 2017. Their primary purpose 
is to assist the public and 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) and (iv). States 
in which Class I areas are located must establish two RPGs, both in 
dv--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.
---------------------------------------------------------------------------

    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, 40 CFR 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 shows 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 3078 at 3097-98, January 10, 
2017.
    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 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 3078 at 
3093, 3099-3100, January 10, 2017; 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

[[Page 56835]]

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 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), and 
(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 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 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 40 CFR 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 EPA or the FLM of an affected Class I area has advised a 
state that additional monitoring is needed to assess RAVI, 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.
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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 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 at 26950 (May 4, 2016), (82 FR 3078 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, 40 
CFR 51.308(g)(3) requires states 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), and 
then to calculate the difference between those current conditions and 
baseline (2000-2004) visibility conditions to assess progress made to 
date. See 40 CFR 51.308(g)(3)(ii). 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(f)(5) and (g)(3)(iii). 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(f)(5) and (g)(4). 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 explain 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

    CAA 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

[[Page 56836]]

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). For 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 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. EPA's Evaluation of Minnesota's Regional Haze Submission for the 
Second Implementation Period

A. Background on Minnesota's First Implementation Period SIP Submission

    Minnesota submitted its Regional Haze SIP for the first 
implementation period to EPA on December 30, 2009, and supplemented it 
on January 5, 2012, and May 8, 2012. EPA approved Minnesota's first 
implementation period Regional Haze SIP submission as satisfying the 
applicable requirements in 40 CFR 51.308, except for BART emission 
limits for the taconite facilities, on June 12, 2012 (77 FR 34801), 
effective July 12, 2012. These requirements include identifying 
affected Class I areas, calculating the baseline and natural 
visibility, establishing RPGs, mandating BART emission reductions for 
the five electric generating units (EGUs) that were subject to BART (in 
this case through participation in the Cross-State Air Pollution Rule 
(CSAPR)), adopting a long-term strategy for making reasonable progress 
toward visibility goals, providing a monitoring strategy, and 
consulting with other states and the FLMs before adopting its regional 
haze plan. EPA acted on RAVI BART for Northern States Power Company's 
Sherburne County Generating Station (Sherco) in a separate action (81 
FR 11668, March 7, 2016), but approved the Minnesota provided emission 
limitations for Sherco units 1 and 2 solely as a SIP strengthening 
measure. The requirements for regional haze SIPs for the first 
implementation period are contained in 40 CFR 51.308(d) and (e).
    EPA promulgated a FIP addressing the BART requirement for taconite 
plants in Michigan and Minnesota. This FIP was published in the Federal 
Register on February 6, 2013 (78 FR 8705). EPA revised the taconite 
plant FIP on April 12, 2016 (81 FR 21671) and on April 1, 2021 (86 FR 
12095). Most recently, EPA published two notices of proposed settlement 
agreements on April 23, 2024, setting forth final NOX BART 
emission limits for Tilden Mining Company (in Michigan), Hibbing 
Taconite Company, United Taconite, Minorca Mine, and Keetac, and final 
SO2 BART emission limits for Tilden, Minorca, and Northshore 
Mining Company. Final adoption of these limits would complete the 
limit-setting process required by the taconite plant FIP. 89 FR 30357 
and 30360, April 23, 2024. EPA also issued a FIP addressing RAVI for 
Sherco, a Minnesota source, on March 7, 2016 (81 FR 11668).
    Pursuant to 40 CFR 51.308(g), Minnesota was also responsible for 
submitting a five-year progress report as a SIP revision for the first 
implementation period, which it did on December 30, 2014. EPA approved 
the progress report and incorporated it into the Minnesota SIP on June 
28, 2018 (83 FR 30350), effective July 30, 2018.

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

    In accordance with CAA section 169A and the RHR at 40 CFR 
51.308(f), on December 20, 2022, Minnesota submitted a revision to the 
Minnesota SIP to address its regional haze obligations for the second 
implementation period that runs from 2018 to 2028. Minnesota made its 
second period Regional Haze SIP submission available for public comment 
on August 22, 2022. The public comment period lasted until October 7, 
2022. Minnesota held a public hearing on September 22, 2022. Minnesota 
received and responded to public comments. It included the comments and 
its responses in appendix H of its regional haze SIP submission.
    The following sections describe Minnesota's SIP submission, 
including analyses conducted by LADCO and Minnesota's determinations 
based on those analyses, Minnesota's assessment of progress made since 
the first implementation period in reducing emissions of visibility 
impairing pollutants, and the visibility improvement progress at its 
Class I areas and nearby Class I areas. This proposed rulemaking also 
contains EPA's evaluation of Minnesota's 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 paragraph (f)(2), which requires each state's plan to 
include a long-term strategy that addresses regional haze in such Class 
I areas.
    EPA explained in the 1999 RHR preamble that the CAA section 
169A(b)(2) requirement that states submit SIPs to address visibility 
impairment establishes ``an `extremely low triggering threshold' in 
determining which States should submit SIPs for regional haze.'' 64 FR 
35714 at 35721, July 1, 1999. In concluding that each of the contiguous 
48 states and the District of Columbia meet this threshold,\31\ EPA 
relied on ``a large body of evidence demonstrat[ing] that long-range 
transport of fine PM contributes to regional haze,'' id., including 
modeling studies that ``preliminarily demonstrated that each State not 
having a Class I area had emissions contributing to impairment in at 
least one downwind Class I area.'' 64 FR 35714 at 35722, July 1, 1999. 
In addition to the technical evidence supporting a conclusion that each 
state contributes to

[[Page 56837]]

existing visibility impairment, EPA also explained that the second half 
of the national visibility goal--preventing future visibility 
impairment--requires having a framework in place to address future 
growth in visibility-impairing emissions and makes it inappropriate to 
``establish criteria for excluding States or geographic areas from 
consideration as potential contributors to regional haze visibility 
impairment.'' 64 FR 35714 at 35721, July 1, 1999. Thus, EPA concluded 
that the agency's ``statutory authority and the scientific evidence are 
sufficient to require all States to develop regional haze SIPs to 
ensure the prevention of any future impairment of visibility, and to 
conduct further analyses to determine whether additional control 
measures are needed to ensure reasonable progress in remedying existing 
impairment in downwind Class I areas.'' 64 FR 35714 at 35722, July 1, 
1999. EPA's 2017 revisions to the RHR did not disturb this conclusion. 
See 82 FR 3078 at 3094 January 10, 2017.
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    \31\ EPA determined that ``there is more than sufficient 
evidence to support our conclusion that emissions from each of the 
48 contiguous states and the District of Columba may reasonably be 
anticipated to cause or contribute to visibility impairment in a 
Class I area.'' 64 FR 35714 at 35721, July 1, 1999. Hawaii, Alaska, 
and the U.S. Virgin Islands must also submit regional haze SIPs 
because they contain Class I areas.
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    Minnesota is home to two mandatory Class I Federal areas: Boundary 
Waters Canoe Area Wilderness (Boundary Waters) and Voyageurs National 
Park (Voyageurs). For the second implementation period, Minnesota 
performed technical analyses to help assess source and state-level 
contributions to visibility impairment at in and out of state Class I 
areas. Those results are presented in section 2.2.2 of its plan. 
Minnesota also assessed the contributions from other states and regions 
to its two Class I areas. See section 2.2.3 of the Minnesota plan.
    Based on modeling completed by the state, Minnesota was found to 
have the greatest visibility impact on the Class I areas within the 
state, Boundary Waters and Voyageurs, contributing an estimated 16.2 
and 17.6 percent of sulfate plus nitrate visibility impairment, 
respectively. Minnesota emissions also impact out-of-state Class I 
areas in Michigan, although the impacts to these out-of-state areas are 
smaller at 8.2 percent (Isle Royale) and 4.3 percent (Seney). 
Visibility impacts to the next closest six Class I areas in other 
states ranged from 0.5 percent at Lostwood Wilderness in North Dakota 
to 2.6 percent at Mammoth Cave in Kentucky.
    Minnesota also assessed the states and regions impacting 
Minnesota's Class I areas. It presented the results of its source 
apportionment modeling in section 2.2.3, including Table 13, of its 
plan. Minnesota identified itself, Canada, North Dakota, Iowa, 
Nebraska, Wisconsin, and Missouri as the largest contributors to 
visibility impairment in one or both Class I areas in Minnesota.

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

    The regulation at 40 CFR 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).
    Voyageurs has a complete set of ambient IMPROVE data for 2000 to 
2004 baseline visibility conditions. Boundary Waters also has a 
complete, but substitute, ambient dataset for this period because an 
equipment malfunction in 2002, 2003, and 2004 caused the loss of some 
PM2.5 particle mass data, elemental organic carbon mass 
data, and coarse particulate (PM10) mass data. The data loss 
invalidated three out of every seven samples for these components. To 
use the valid data, Minnesota substituted missing elements with data 
from Voyageurs. This data substitution is detailed in Minnesota's plan, 
appendix A. Minnesota included this data substitution in its first 
period Regional Haze plan, which EPA approved, effective July 12, 2012. 
77 FR 34801, June 12, 2012.
    As noted in section 2.1 of Minnesota's plan, for Boundary Waters, 
baseline visibility conditions are 6.5 dv on the 20 percent clearest 
days and 18.5 dv on the 20 percent most impaired days. For Voyageurs, 
the baseline visibility conditions are 7.2 dv on the 20 percent 
clearest days and 17.9 dv on the 20 percent most impaired days.
    As noted in section 2.1 of Minnesota's plan, Minnesota calculated 
natural conditions for Boundary Waters at 6.5 dv on the 20 percent 
clearest days and 9.1 dv on the 20 percent most impaired days. For 
Voyageurs, Minnesota calculated the natural conditions at 7.2 dv \32\ 
on the 20 percent clearest days and 9.3 dv on the 20 percent most 
impaired days.
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    \32\ EPA estimated the natural visibility conditions on the 20 
percent clearest days to be 3.48 dv at Boundary Waters and 4.27 dv 
at Voyageurs. See Technical Addendum including updated visibility 
data through 2018 for the memo titled ``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'' issued June 
2020.
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    Current conditions, based on 2015-2019 monitoring data, for the 
days of most impaired visibility, are better than the 2018 interim 
progress goals for the Boundary Waters and Voyageurs, as depicted in 
Figure 4 in section 2.1 of Minnesota's plan. Current conditions for the 
days of clearest visibility improved and did not degrade from the 
baseline. Minnesota provides the current visibility conditions for each 
year and a running five-year average for both Class I areas on Table 5 
in section 2.1.3 of its plan. The 2015 to 2019 averages are: Boundary 
Waters at 4.2 dv on the clearest days and 13.4 dv on the most impaired 
days and Voyageurs at 5.1 dv the clearest days and 13.5 dv on the most 
impaired days.
    Minnesota shows the progress to date for both its Class I areas in 
section 2.1.4, Table 6 of its plan. Table 6 has data for the five-year 
averages from 2004 to 2019. For Boundary Waters, the five-year average 
for the most impaired days decreased from 18.5 in 2004 to 13.4 in 2019 
while the five-year average for the clearest days trended from 6.5 dv 
in 2004 to 4.2 in 2019. For Voyageurs, the five-year average for the 
most impaired days decreased from 17.9 in 2004 to 13.5 in 2019 while 
the five-year average for the clearest days trended from 7.2 dv in 2004 
to 5.1 in 2019. Based on the ambient data trends, steady progress 
towards natural conditions is being made in both Boundary Waters and 
Voyageurs.
    Minnesota calculated the difference between current visibility and 
natural visibility conditions in section 2.1.5 of its plan. For 
Boundary Waters, on the most impaired days, the current visibility is 
13.4 dv, which is 4.3 dv above the 2064 end point of 9.1 dv, while the 
current 4.2 dv visibility on the clearest days is below the end point 
target of 6.5 dv. The difference is similar at Voyageurs, with the 
current visibility on the most impaired days of 13.5 dv being 4.2 dv 
above the 9.3 dv end point in 2064. The current visibility at Voyageurs 
on the clearest days, 5.1 dv, is also below the 2064 end point target 
of 7.2 dv.
    Minnesota, in section 2.1.6 of its plan, calculated the URP for the 
Class I areas

[[Page 56838]]

for each implementation period. The URP for 2018 is 16.3 dv at Boundary 
Waters and 15.9 dv at Voyageurs. The 2018 five-year average for the 
most impaired days is 13.8 dv at Boundary Waters and 14.0 dv at 
Voyageurs. The 2028 URP is 14.7 dv at Boundary Waters and 14.5 dv at 
Voyageurs. Thus, 2018 visibility is below the 2018 URP as well as the 
2028 URP. The current visibility continues the decline in visibility 
impairment seen in 2018. The 2019 five-year average, the most current 
at submission, improved to 13.4 dv at Boundary Waters and to 13.5 dv at 
Voyageurs.
    EPA proposes to find that Minnesota has submitted a regional haze 
plan that meets the requirements of 40 CFR 51.308(f)(1) related to the 
calculations of baseline, current, and natural visibility conditions; 
progress to date; and the URP for the second implementation period.

E. Long-Term Strategy for Regional Haze

1. Emission Measures Necessary To Make Reasonable Progress
    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 169A(b)(2)(B). As explained in the Background section of this 
action, 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 40 CFR 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)(iii).
    The following paragraphs detail how Minnesota's submission 
addresses the requirements of 40 CFR 51.308(f)(2)(i). Minnesota 
evaluated and determined the emission reduction measures needed to make 
reasonable progress. In its submission, Minnesota documents the 
methodology it used in its selection of sources for analysis and 
control measures necessary to make reasonable progress, which are 
discussed later in this section.
    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 40 CFR 51.308(f). States may also satisfy the 
requirement of 40 CFR 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.
    Minnesota is a member of an RPO, LADCO, and participated in the 
RPO's regional approach to developing a strategy for making reasonable 
progress towards the national visibility goal in the northern Midwest 
Class I areas.
    Minnesota performed its own technical analysis using EPA and LADCO 
provided elements. Minnesota's modeling used EPA's modeling platform 
with some portions replaced by those from LADCO.
    The technical analyses included in Minnesota's submission are as 
follows:
     Establishment of RPGs for Boundary Waters and Voyageurs 
(appendix A)
     Contributions to the 2028 RPGs for Boundary Waters and 
Voyageurs (appendix A)
     Minnesota's impact on Class I areas (appendix A)
     Assessment of states and regions impacting Minnesota's 
Class I areas (appendix A)
     Modeling analyses supporting the conclusion that the Long-
Term Strategy provides reasonable progress (appendix A)
     LADCO's Technical Support Documentation (appendix C)
     LADCO's Q/d Materials (appendix C)
     LADCO's photochemical modeling and Emissions Modeling 
results (appendix C)
    Minnesota found that the emission reduction measures necessary to 
make reasonable progress include:
     Permanent and federally enforceable current and future 
retirements at ten EGUs (Minnesota plan Table 32), Enforceable by 
permit or administrative order;
     Existing effective controls for nine other selected 
sources, two paper mills, one EGU, and six taconite facilities, which 
are required through permits and the 2013 regional haze taconite plant 
FIP (Minnesota plan Table 33); \33\
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    \33\ 78 FR 8706, February 6, 2013.
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     Additional NOX emission reductions from Hibbing 
Public Utilities Commission from its ``Hibbing Public Utilities 
Restorative Plan.'' These three EGUs will use renewable resources such 
as wood alongside natural gas as the primary fuels for its boilers. 
Minnesota established enforceable requirements, via an administrative 
order, for the proposed NOX emission limits. These 
NOX emission reductions were accounted for in Minnesota's 
modeling analysis 2028 projection. See section 2.5.1 in the Minnesota 
plan;
     Expected emission reductions from the implementation of 
the Regional Haze taconite plant FIP (Minnesota plan section 2.6.2); 
\34\
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    \34\ See 89 FR 30357 and 30360, April 23, 2024 for details on 
the April 2024 proposed settlements prefacing proposed rules that 
will include emission limitations for taconite facilities in 
Minnesota and Michigan.
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     Updated Northeast Minnesota Plan adding voluntary emission 
reduction targets of 30 percent below 2018 levels by 2025 and 40 
percent below 2018 levels by 2028, targeting taconite facilities, EGUs, 
and paper mills (Minnesota plan section 2.5.7).
    2. EPA's Evaluation of Minnesota's Compliance With 40 CFR 
51.308(f)(2)(i)
    The regulation at 40 CFR 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. The emission reduction 
measures that are necessary to make reasonable progress must be 
included in the long-term strategy. 40 CFR 51.308(f)(2).
    EPA proposes to find that Minnesota appropriately considered the 
four statutory factors: cost of compliance, time necessary for 
compliance, the

[[Page 56839]]

energy and non-air environmental impacts, and the remaining useful life 
of the source in its source evaluations.
    Minnesota detailed its source selection process in section 2.3.6. 
of its plan. Minnesota originally selected 13 facilities that accounted 
for about the top 80 percent of emissions impacting visibility at 
Boundary Waters and Voyageurs. Discussions with the FLMs resulted in 
Minnesota considering four additional facilities--American Crystal 
Sugar in Crookston and East Grand Forks, Hibbing Public Utilities, and 
Southern Minnesota Beet Sugar Cooperative. Thus, Minnesota selected the 
following 17 facilities, which account for nearly the top 85 percent of 
visibility impacts at Boundary Waters and Voyageurs and result in an 
effective Q/d of about 4.6: \35\
---------------------------------------------------------------------------

    \35\ Tables 43 and 44 of the Minnesota plan include more 
information on the Q/d, percentile, cumulative percentile, FLM 
interest, and whether Minnesota required a four-factor analysis.
---------------------------------------------------------------------------

     American Crystal Sugar--Crookston: Boilers 1, 2, and 3;
     American Crystal Sugar--East Grand Forks: Boilers 1 and 2;
     Boise White Paper: Recovery Furnace, Boilers 1 and 2;
     Cleveland Cliffs Minorca Mine: Indurating Furnace;
     Hibbing Public Utilities: Boilers 1A, 2A, 3A, and Wood 
Fired Boiler;
     Hibbing Taconite Company: Indurating Furnace Lines 1, 2, 
and 3;
     Minnesota Power--Boswell: Units 1, 2, 3, and 4;
     Minnesota Power--Taconite Harbor: Boilers 1 and 2;
     Northshore Mining--Silver Bay: Power Boilers 1 and 2 and 
Furnaces 11 and 12;
     Sappi Cloquet LLC: Power Boiler 9 and Recovery Boiler 10;
     Southern Minnesota Beet Sugar Cooperative: Boiler 1;
     United Taconite--Fairlane Plant: Pellet Induration Lines 1 
and 2;
     US Steel--Keetac: Grate Kiln;
     US Steel--Minntac: Rotary Kiln Lines 3, 4, 5, 6, and 7;
     Virginia Department of Public Utilities: Boilers 7, 9, and 
11;
     Xcel Energy--Allen S. King: Boiler 1; and
     Xcel Energy--Sherburne: Units 1, 2, and 3.
    Minnesota then contacted these selected sources and requested they 
prepare site-specific four-factor analyses. To guide facilities' 
assessment of selected sources, Minnesota suggested the facilities use 
the 2016 actual emissions data unless 2028 operations are expected to 
be significantly different than 2016 operations. In its request, 
Minnesota explained that emissions should be based on representative 
historical operations and follow the recommendations regarding 
emissions data in EPA's August 2019 Guidance. Facilities generally 
provided emissions data that were reported to the most recent Minnesota 
annual emissions inventory (typically 2018 or 2019), which was at least 
as recent as the emissions data submitted to EPA's 2017 National 
Emissions Inventory (NEI), at the time the requested four-factor 
analyses were provided to Minnesota.
    In appendix E of its plan, Minnesota reviewed the emissions data 
provided in each four-factor analysis and compared that information to 
the emissions data reported in Minnesota's annual emissions inventory 
for the years 2016 through 2020. Minnesota compared the emissions data 
to these years of reported emissions data to verify that the emissions 
used in the four-factor analyses were similar to historically reported 
emissions. Where emissions data used by facilities were not 
representative of typical emissions, Minnesota revised the emissions 
data used as part of evaluating potential control measures following 
the methods recommended by the EPA's Air Pollution Control Cost Manual 
\36\ (as of June 23, 2022). As an example, the American Crystal Sugar--
Crookston facility reports annual NOX and SO2 
emissions based on a pound per hour value determined during stack 
testing while the four-factor analysis calculated emissions in pounds 
per million British thermal units. Minnesota and the facility both 
reviewed the stack testing results leading the state to conclude the 
calculated pound per hour values are skewed high, so it used the pounds 
per million British thermal units value for the four-factor analysis.
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    \36\ Available at https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution.
---------------------------------------------------------------------------

    Minnesota also evaluated the cost of compliance as detailed in 
sections 2.4.3 and 2.5.1 of the Minnesota plan. In order to evaluate 
the reasonableness of potential control measures, Minnesota chose to 
evaluate those costs compared to available cost information from many 
sources including first period BART determinations, other states' 
regional haze plans,\37\ EPA's RACT/BACT/LAER Clearinghouse,\38\ and 
other sources. Minnesota identified the units to be analyzed along with 
the request for facilities to prepare a four-factor analysis following 
the 2019 Guidance. The 2019 Guidance provides the methods to determine 
emission control measures to consider and details how the four factors 
of section 169A(g)(1) of the CAA (cost of compliance, time necessary 
for compliance, energy and non-air environmental impacts, and remaining 
useful life of the source) can be considered. Minnesota also let 
facilities refine the cost estimate with a source-specific vendor 
quote. In order to make the cost analyses uniform and more accurate, 
Minnesota further refined the analyses by adjusting the cost 
information using consistent factors in the calculations including 
interest rates and retrofit factors. Those analyses are detailed in 
appendix E, and in Tables 52 and 54 of section 2.4.3 and in section 
2.5.1 of its plan.
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    \37\ The state plans from Arkansas, Arizona, Colorado, North 
Dakota, New Mexico, Oregon, Texas, Washington, and Wisconsin were 
available at the time, approximately October 2021, of Minnesota's 
review.
    \38\ RACT is Reasonably Available Control Technology, BACT is 
Best Available Control Technology, and LAER is Lowest Achievable 
Emission Rate; the Clearinghouse can be accessed at: https://cfpub.epa.gov/RBLC/index.cfm?action=Home.Home⟨=en.
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    Minnesota did not set a bright-line cost threshold but considered 
controls that cost less than approximately $7,600 per ton as cost 
effective for the second implementation period. Minnesota used $10,000 
per ton for an initial screening threshold. Minnesota then evaluated 
potential NOX and SO2 control measures and 
refined the costs of those controls, factoring in interest rates, 
retrofit factors, and source-specific vendor quotes. After adjustments 
and further analysis, the most expensive control measure considered to 
be potentially cost-effective by the state was less than $7,600 per 
ton.\39\ Detail on the controls considered and costs calculated for 
each facility are provided in section 2.5.1 and in Tables 55 to 60 in 
Minnesota's plan.
---------------------------------------------------------------------------

    \39\ Original calculation for selective non-catalytic reduction 
on Sappi Cloquet Boiler 9 was $7,632 per ton NOX, which 
was later revised following a vendor quote and state revision.
---------------------------------------------------------------------------

    In section 2.5.2 of the Minnesota plan, Minnesota reviewed the time 
needed for compliance with potential control measures provided by 
facilities to consider what compliance timeframe would be reasonable 
for each specific source. The state noted that in general, facilities 
provided an estimate of the time needed to install the evaluated 
control options including the time needed for design, engineering, 
procurement, and installation. Minnesota reviewed the facility's time 
needed for compliance with potential control measures provided by 
facilities to consider what compliance timeframe would be reasonable 
for each specific source. Minnesota considered the time

[[Page 56840]]

necessary for compliance as part of evaluating potential control 
measures later in the four-factor analysis process in determining if a 
control measure was needed to make reasonable progress. EPA finds this 
approach reasonable given that it is consistent with the 2019 Guidance 
at 41.
    In section 2.5.3 of the Minnesota plan, Minnesota stated that it 
considered the energy and non-air environmental impacts as part of the 
cost of compliance of potential control measures in determining whether 
a control measure was necessary to make reasonable progress. Minnesota 
considered this factor by evaluating the cost impact from the potential 
control measures such as whether adopting the control would: (1) 
increase or decrease energy use; (2) impact solid, liquid, and 
hazardous waste disposal; (3) create reagents that contaminate fly ash 
making it unsuitable for sale; and (4) require accessory systems such 
as additional fans. Minnesota considered the remaining useful life of 
each source as described in section 2.4.6 and 2.5.4 of its plan. 
Minnesota determined the remaining useful life by considering the 
remaining duration of operation and the expected lifespan of potential 
controls. Minnesota noted that facilities generally followed the 
Control Cost Manual control device recommendations in their 
calculations. In several cases, Minnesota considered enforceable 
retirement dates as the end of a source's useful life. Minnesota 
provided detail on the retirements of 10 units at Minnesota Power--
Boswell, Minnesota Power--Taconite Harbor, Virginia Department of 
Public Utilities, and Xcel Energy--Allen S. King and Sherco facilities 
on Table 32 in section 2.3.3 of its plan.
    In order to ensure that the long-term strategy contains the 
enforceable emissions limitations necessary for reasonable progress, 
Minnesota assessed emissions limitations at each of the 17 facilities 
it considered. For sources for which Minnesota determined that no 
additional control measures were needed, Minnesota relied on existing 
federally enforceable emissions limitations in the taconite plant FIP, 
and on retirement schedules at certain facilities memorialized in 
administrative orders as described in section 2.5.4 and appendix D of 
its plan and in the following paragraph. The Minnesota long-term 
strategy relies on these federally enforceable emissions limitations 
and retirement schedules as the measures necessary to make reasonable 
progress. As such, Minnesota concluded that additional control measures 
were not necessary to make reasonable progress.
    Minnesota entered into an administrative order regarding the 
Virginia Department of Public Utilities Boiler 7, including a permanent 
retirement scheduled for Boiler 7 by January 1, 2025. Minnesota also 
entered into administrative orders for the retirements of Minnesota 
Power--Taconite Harbor Boilers 1 and 2 by March 31, 2023, Xcel Energy--
Allen S. King Boiler 1 by December 31, 2028, and Xcel Energy--Sherco 
Unit 3 by December 31, 2030. Minnesota also entered into an 
administrative order requiring the Northshore Mining--Silver Bay Power 
Company's Power Boiler 1 and Power Boiler 2 units to remain idled 
through 2031. Finally, at Hibbing Public Utilities commission, 
Minnesota entered into an administrative order requiring NOX 
emission limits at Boilers 1A, 2A, and 3A effective January 1, 2023, 
that resulted in equivalent reductions that would have been achieved by 
installing controls on each boiler at the facility. EPA proposes to 
incorporate by reference these administrative orders.
    Several units at selected facilities had permanently retired. In 
section 2.3.3 of its plan, Minnesota cites the federally enforceable 
permits for Minnesota Power--Boswell Energy Center Unit 1 and Unit 2, 
Virginia Department of Public Utilities Boiler 9, and Xcel Energy--
Sherco Unit 1 and Unit 2.
    Minnesota also considered the following sources to be effectively 
controlled through federally enforceable emissions limits included in 
operating permits or in the first regional haze implementation period. 
Regarding Boise White Paper Boiler 2 and Recovery Furnace, Minnesota 
determined that the facility's emissions permit included a 
NOX limit comparable to recent BACT determinations for 
similar units. Regarding Minnesota Power's Boswell Energy Center Unit 
3, BART NOX limits were established in the first regional 
haze implementation period and the facility's emissions permit included 
BART SO2 limits established pursuant to the 2012 Mercury Air 
Toxics Standards (MATS) rule for power plants. See 77 FR 9304, February 
16, 2012. Regarding Minnesota Power's Boswell Energy Center Unit 4, 
Minnesota determined that the facility's emissions permit included a 
NOX limit comparable to recent BACT determinations for 
similar units and a SO2 limit established pursuant to the 
2012 MATS rule. Regarding Sappi Cloquet Recovery Boiler 10, the 
facility's emissions permit included a NOX BACT emissions 
limit.
    Minnesota also considered the following sources to be effectively 
controlled through federally enforceable emissions limits in the 
taconite plant FIP. Regarding US Steel Minntac Rotary Kiln Lines 3, 4, 
5, 6, and 7, EPA published a final rule on March 2, 2021, imposing a 
facility-wide BART NOX emission limit for Minntac lines 3-7. 
86 FR 12095, March 2, 2021. Regarding Minorca Mine Indurating Furnace, 
United Taconite Grate Kiln Lines 1 and 2, Hibbing Lines 1, 2, and 3, 
Northshore Mining--Silver Bay Furnace 11 and 12, and US Steel Keetac 
Grate Kiln, EPA published two notices of proposed settlement agreements 
on April 23, 2024. 89 FR 30357 and 30360, April 23, 2024. These actions 
set forth final NOX BART emission limits for Hibbing, United 
Taconite, Minorca, and Keetac, and final SO2 BART emission 
limits for Minorca and Northshore. Final adoption of these limits would 
complete the limit-setting process required by the taconite plant FIP.
    In section 2.4.1 of its plan, Minnesota provided the emission 
control measures considered in Table 45 along with noting the units 
that have or will retire and were found to be effectively controlled. 
The NOX controls generally considered were low 
NOX burners (LNB) and/or over-fire air (OFA) systems, 
selective non-catalytic reduction (SNCR), and selective catalytic 
reduction (SCR). The SO2 controls generally considered were 
wet flue gas desulfurization (FGD), dry FGD, and dry sorbent injection 
(DSI).
    Minnesota evaluated potential NOX and SO2 
controls for both American Crystal Sugar facilities. At American 
Crystal Sugar--Crookston, Minnesota considered controls for Boilers 1, 
2, and 3. The NOX controls were all over $12,000 per ton 
(Minnesota refined) with the maximum 109 tons per year (TPY) for SCR on 
Boiler 3. The SO2 controls were over $12,500 per ton for DSI 
and over $16,000 per ton for dry FGD for all three units. At American 
Crystal Sugar--East Grand Forks, Minnesota evaluated Boilers 1 and 2. 
Minnesota found that SNCR would cost about $11,366 per ton 
NOX to reduce 35 TPY on each unit, while DSI was calculated 
at $11,241 per ton SO2 to reduce 317 TPY on each unit. 
Minnesota concluded that neither NOX nor SO2 
controls appear cost-effective for either American Crystal Sugar 
facility.
    Minnesota also evaluated potential SO2 controls for 
Hibbing Public Utilities Commission Boilers 1A, 2A, and 3A and 
evaluated NOX controls on the Wood Fired Boiler unit. 
Minnesota determined

[[Page 56841]]

that none of these controls were cost effective.
    For Sappi Cloquet LLC, Minnesota considered potential 
NOX and SO2 controls for Power Boiler #9. 
Minnesota calculated controlling 11 TPY of SO2 emissions 
with DSI would cost $515,275 per ton. Minnesota calculated SNCR on 
Power Boiler #9 would cost $7,632 per ton of NOX controlled. 
Sappi Cloquet supplied a vendor quote, on which Minnesota revised the 
expected control cost down to $8,562 per ton. Minnesota concluded that 
neither NOX nor SO2 controls for Power Boiler #9 
appear cost-effective for Sappi Cloquet in the second regional haze 
implementation period.
    Minnesota also evaluated potential NOX and 
SO2 controls for Boiler 1 at Southern Minnesota Beet Sugar 
Cooperative. For SO2, Minnesota calculated a Spray Dry 
Absorber control to cost $10,097 per ton, which Minnesota found not to 
be cost effective. Minnesota also evaluated several potential 
NOX controls for Boiler 1. Minnesota revised the facility's 
calculations for SNCR control to $2,942 per ton that would reduce an 
expected 447 tons of NOX. Although Minnesota found 
NOX controls to be potentially cost effective, Southern 
Minnesota Beet Sugar Cooperative refuted Minnesota's determination to 
install NOX controls ahead of the SIP submission deadline 
and provided a technical analysis supporting its position. As a result, 
Minnesota intends to reevaluate this facility for the 2025 progress 
report and the third regional haze implementation period.
    Minnesota also evaluated potential NOX controls for 
Boiler 1 at Boise White Paper. Minnesota refined the facility's four-
factor analysis for potential control options and found that SCR is 
expected to reduce 66 TPY NOX at $13,783 per ton with the 
other option (LNB with OFA and flue gas recirculation) costing nearly 
twice that ($26,649 per ton). Minnesota concluded that NOX 
controls at Boise White Paper Boiler 1 are not cost effective.
    Minnesota evaluated potential NOX and SO2 
controls for Boiler 7 and potential NOX controls for Boiler 
11 at Virginia Department of Public Utilities. The facility suggested 
that Boiler 7 may retire during the second regional haze implementation 
period, but because the retirement was not confirmed, Minnesota 
analyzed that unit. For Boiler 7, Minnesota calculated a cost-
effectiveness of $9,534 per ton using SNCR to reduce 28 TPY 
NOX. Minnesota calculated $12,724 per ton for SCR on Boiler 
11 reducing 81 TPY NOX. Minnesota calculated $25,420 per ton 
SO2 for a dry scrubber and $42,939 per ton SO2 
for a wet scrubber on Boiler 7. On April 6, 2022, the facility informed 
Minnesota that it planned to retire Boiler 7 by January 1, 2025. 
Minnesota included an Administrative Order making the retirement of 
Boiler 7 at Virginia Department of Public Utilities permanent and 
enforceable that EPA is proposing to incorporate by reference. The 
calculated cost-effectiveness for potential NOX control for 
Boiler 11 at Virginia Department of Public Utilities exceeds 
Minnesota's screening threshold.
    EPA proposes to find that Minnesota has satisfied the requirements 
of 40 CFR 51.308(f)(2)(i) related to determining the emission reduction 
measures that are necessary to make reasonable progress by 
appropriately considering the four statutory factors and providing a 
long-term strategy that includes the enforceable emission limitations 
and compliance schedules that are necessary to make reasonable 
progress.
3. Additional Long-Term Strategy Requirements
Consultation
    The consultation requirements of 40 CFR 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. Under 40 CFR 51.308(f)(2)(ii)(C) speaks to 
what happens if states cannot agree on what measures are necessary to 
make reasonable progress.
    As noted in section 2.9.1 of its plan, Minnesota participated in 
the LADCO Regional Haze Technical Workgroup meetings beginning in 
January 2018. These meetings are ongoing.
    Minnesota also consulted with several states individually. 
Minnesota met with Iowa on June 30, 2022. Minnesota met with Michigan 
on June 24, 2022. Minnesota consulted with Missouri on June 21, 2022. 
Nebraska met with Minnesota three times on June 26, 2020, December 16, 
2020, and June 21, 2022. On June 25, 2020, Minnesota and North Carolina 
met. North Dakota and Minnesota consulted on March 22, 2021, and June 
23, 2022. Minnesota met South Dakota on September 15, 2021. Minnesota 
and Wisconsin met on June 30, 2022. More information on these meetings 
with individual states and any follow-up is provided in Minnesota's 
plan at section 2.9.1.
    No states notified Minnesota that they identified emissions from 
Minnesota sources as contributing to visibility impairment at their 
Class I areas. There are no requests from other states to analyze 
emissions controls at Minnesota sources or for Minnesota to undertake 
specific emissions reductions necessary to make reasonable progress for 
the second regional haze implementation period at out-of-state Class I 
areas.
    EPA proposes to find that Minnesota has met the 40 CFR 
51.308(f)(2)(ii)(A) and (B) consultation requirements with its 
participation in the LADCO Regional Haze Technical Workgroup 
consultation process plus its individual consultation meetings with 
contributing states. There were no disagreements with other states, so 
40 CFR 51.308(f)(2)(ii)(C) does not apply.
Technical Basis
    The regulation at 40 CFR 51.308(f)(2)(iii) requires states to 
document the technical basis of the long-term strategy. This includes 
the modeling, monitoring, cost, engineering, and emissions information 
that the state relied on in determining the emission-reduction measures 
that are necessary to make reasonable progress. As explored in further 
detail above, Minnesota specified the control measures necessary to 
make reasonable progress in section 2.5 of its plan. In summary, 
Minnesota concluded that the following control measures are necessary 
for reasonable progress:
     The realized and upcoming emission unit retirements; \40\
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    \40\ Retirements of Minnesota Power's Boswell Energy Center 
Units 1 and 2, Minnesota Power's Taconite Harbor Energy Center 
Boilers 1 and 2, the Virginia Department of Public Utilities Boilers 
7 and 9, Xcel Energy's Allen S. King Boiler 1, and Sherco's Units 1, 
2, and 3, and the idling of Northshore Mining's Silver Bay Power 
Boilers 1 and 2 through 2031.
---------------------------------------------------------------------------

     The existing effective controls for non-taconite emission 
units; \41\
---------------------------------------------------------------------------

    \41\ Existing effective measures at Boise White Paper Boiler 2 
and Recovery Furnace, Minnesota Power's Boswell Energy Center Units 
3 and 4, and Sappi Cloquet Recovery Boiler 10.
---------------------------------------------------------------------------

     Additional NOX emission reductions expected for 
Hibbing Public Utilities Commission;
     The expected emission reductions from implementation of 
the taconite plant FIP;
     The new, voluntary emission reduction targets in the 
Northeast Minnesota Plan for 2025 and 2028.
    To select these control measures, Minnesota relied on monitoring, 
as

[[Page 56842]]

required in 40 CFR 51.308(f)(2)(iii). Minnesota documented its long-
term modeling in detail in section 2.6 of its plan and its technical 
support document. Minnesota elected to follow EPA modeling guidance to 
estimate future visibility in its Class I areas to establish the RPGs 
for Boundary Waters and Voyageurs. Minnesota used an EPA modeling 
platform with some portions replaced by LADCO. The modeling platform 
consists of meteorology, emissions, and other inputs needed to run an 
air quality model.
    40 CFR 51.308(f)(2)(iii) also requires the documentation of cost 
analyses as part of the technical basis for the state's long-term 
strategy. As explained above, Minnesota satisfactorily complied with 
the requirement of 40 CFR 51.308(f)(2)(i) to consider cost as one of 
the four statutory factors to be considered when evaluating control 
options. EPA is proposing to find that Minnesota's documentation of its 
cost considerations satisfy its obligation under 40 CFR 
51.308(f)(2)(iii).
    As noted above, Minnesota considered engineering, one of the 
technical basis elements of 40 CFR 51.308(f)(2)(iii), in its selection 
of potential emission control systems and in evaluating the control 
analyses (such as evaluating reasonableness of the control efficiency 
and retrofit factor used).
    40 CFR 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 EPA (or a more recent year), with a 12-month exemption period for 
newly submitted data. In section 2.3.2 of its plan, Minnesota used 2016 
emissions inventory data to calculate Q/d in an effort to select 
industrial point sources for an analysis of emissions control measures. 
The LADCO Regional Haze Technical Workgroup selected the National 
Emissions Inventory Collaborative 2016 inventory for the Q/d analysis 
in March 2018 as the best available inventory at that time. LADCO 
compiled the Q/d analysis, which accounted for the combined emissions 
of SO2, NOX, NH3, and PM2.5 
and the distance to the nearest Class I areas.
    In section 2.4.2, Minnesota's SIP submission also provided 2028 
emission projections based on a modeling platform using the 2016 
emissions inventory. Minnesota also considered Clean Air Markets 
Program Data emissions for EGUs for NOX and SO2 
in assessing emission reductions from regional haze SIP strategies. In 
addition, in developing four-factor analyses, facilities provided 
emissions data that was reported to the most recent Minnesota annual 
emission inventory (typically 2018 or 2019), which was at least as 
recent as the emissions data submitted to EPA's 2017 NEI. Minnesota 
reviewed the emissions data provided in each four-factor analysis and 
compared that information to the emissions data reported to Minnesota's 
annual emission inventory for the years 2016 through 2020. Minnesota 
compared the emissions data to these years of reported emissions data 
to verify that the emissions used in the four-factor analysis were 
reasonably grounded in historical reported emissions. Based on 
Minnesota's consideration and analysis of the emission data in its SIP 
submission and supplemental documentation, EPA proposes to find that 
Minnesota has satisfied the emissions information requirement in 40 CFR 
51.308(f)(2)(iii).
    Finally, Minnesota also adequately documented adjustments to the 
factors impacting the RPG, which involved adjustments to reflect 
changes at facilities occurring after the modeling platform was 
developed.
    EPA proposes to find that Minnesota adequately documented its 
technical basis for calculating the 2028 RPGs for Boundary Waters and 
Voyageurs.
Five Additional Factors
    EPA also proposes to find that Minnesota reasonably considered the 
five additional factors in 40 CFR 51.308(f)(2)(iv) in developing its 
long-term strategy. Minnesota considered these five factors in section 
2.3.4 of its plan.
    Pursuant to 40 CFR 51.308(f)(2)(iv)(A), Minnesota noted that it 
considered ongoing state and Federal emission control programs that 
contribute to emission reductions through 2028 in the modeling that was 
used to develop the long-term strategy. In addition, the Sherco 
facility has an existing emissions limit to address RAVI at Minnesota 
Class I areas. EPA promulgated a RAVI FIP for Sherco on March 7, 2016 
(81 FR 11668), and the emission limitations are in 40 CFR 52.1236. 
Minnesota also provided details on the taconite plant BART FIP that 
limits visibility impairing emissions from several taconite facilities. 
Minnesota noted numerous Federal standards and other existing measures 
that result in emission reductions. In section 3.1 of its plan, 
Minnesota also noted additional emission reductions from a variety of 
programs that are not reflected in its 2028 modeling inventory. Those 
programs include the Ozone and PM Advance programs, Volkswagen 
Settlement funded projects, and the Clean Cars Minnesota rule.
    Pursuant to 40 CFR 51.308(f)(2)(iv)(B), Minnesota considered 
measures to mitigate the impacts of construction activities by 
considering EPA standards for nonroad and diesel mobile sources, as 
well as Minnesota Rule 7011.0150, which requires all reasonable 
measures to be undertaken to prevent particulate matter from becoming 
airborne. Minnesota notes the main impacts of construction activities 
include the impacts of emissions from nonroad mobile and diesel engines 
and fugitive emissions resulting from land clearing and construction.
    Pursuant to 40 CFR 51.308(f)(2)(iv)(C), Minnesota considered source 
retirement and replacement schedules memorialized in enforceable 
administrative orders, as discussed above regarding Minnesota's 
compliance with the requirement of 40 CFR 51.308(f)(2)(i) to consider 
the remaining useful life of any existing source possibly subject to 
control requirements. See section 2.3.3 and Table 32 of Minnesota's 
plan. The source retirements that had already occurred are federally 
enforceable by permit condition as given by the state.
    Pursuant to 40 CFR 51.308(f)(2)(iv)(D), Minnesota considered smoke 
management by considering the Minnesota Smoke Management Plan. The 
state noted that prescribed fire and managed wildfire have been used in 
Minnesota for many years to improve and maintain natural resources. The 
Minnesota Smoke Management Plan \42\ was created and implemented for 
three reasons: improving visibility in the Class I areas in Minnesota, 
enabling the continued use of prescribed fire as a management tool, and 
using a smoke management program to prevent violations of the 
particulate matter and ozone NAAQS due to emissions from managed 
wildland fires. Further, Minnesota highlighted the data from the 
IMPROVE monitoring sites at the Boundary Waters and Voyageurs Class I 
areas indicating that elemental and organic carbon, pollutants 
typically formed from fire, are not large

[[Page 56843]]

contributors to visibility impairment in these areas.
---------------------------------------------------------------------------

    \42\ Agricultural burning is not covered by Minnesota's Smoke 
Management Plan. However, Minnesota stated that agricultural burning 
requires an open burning permit. In general, agricultural burning in 
Minnesota is limited to grass and stubble burning, particularly of 
bluegrass and timothy grass. This light fuel type produces short-
term smoke events without a lot of combustion of biomass and 
smoldering. In addition, most agricultural burning occurs in the 
northwest area of the state, away from the Class I areas.
---------------------------------------------------------------------------

    Pursuant to 40 CFR 51.308(f)(2)(iv)(E), Minnesota considered the 
anticipated net effect on visibility due to projected changes in 
emissions in its submission, in developing the technical information 
used to support development of the regional haze SIP. Minnesota noted 
that it used conservative estimates of the visibility improvements due 
to Minnesota's long-term strategy for the second regional haze 
implementation period. Minnesota met this requirement by projecting 
emissions from all sources in Minnesota and other nearby states to the 
end of the planning period (2028) and performing a detailed modeling 
analysis of the anticipated impact of those emissions changes on 
visibility impairment at Class I areas in both Minnesota and nearby 
states. However, Minnesota did not directly rely on the 2028 modeling 
analysis to select sources and evaluate controls in developing its 
long-term strategy. Instead, Minnesota used the Q/d process presented 
in section 2.3 of its plan to select sources for an analysis of control 
measures. As detailed in section IV. E.2. of this preamble, Minnesota 
performed a well-developed analysis resulting in a reasonable selection 
of sources and performed a sufficient control analysis on the selected 
sources.
    EPA proposes to find that Minnesota's reasonable consideration of 
each of the five additional factors satisfies 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. Minnesota contains two Class I areas, making it 
subject to 40 CFR 51.308(f)(3)(i). Section 51.308(f)(3)(i) requires a 
state in which a Class I area is located to establish RPGs--one each 
for the most impaired and clearest days--reflecting the visibility 
conditions that will be achieved at the end of the implementation 
period as a result of the emission limitations, compliance schedules 
and other measures required under paragraph (f)(2) to be in states' 
long-term strategies, as well as implementation of other CAA 
requirements. The long-term strategies as reflected by the RPGs must 
provide for an improvement in visibility on the most impaired days 
relative to the baseline period and ensure no degradation on the 
clearest days relative to the baseline period. 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.
    Minnesota determined the 2028 RPGs for Boundary Waters and 
Voyageurs based on the long-term strategy and other enforceable 
measures described in its plan.
    Minnesota determined the RPGs using its modeling platform, 
consisting of EPA's 2016 modeling platform, version 1, with some parts 
replaced with those provided by LADCO. This resulted in a 2016 modeling 
platform, version 1b, as detailed in the Minnesota plan at section 
2.6.1. Minnesota used the National Emissions Inventory Collaborative's 
emissions inventory 2016 base year for the second implementation 
period. Minnesota details the meteorology inputs for its emissions 
model and its air-quality model in its plan. For the base year 
inventories, Minnesota used the LADCO prepared ``actual'' and 
``typical'' emissions inventories. Minnesota used the actual emissions 
inventory for evaluating air-quality model performance. Minnesota used 
the typical emissions inventory for establishing RPGs and for the 
contribution assessment. Minnesota notes the only difference between 
the actual and typical emissions inventories involves the 
characterization of emissions from the taconite facilities in 
Minnesota. LADCO prepared a 2028 projected ``typical'' emissions 
inventory for Minnesota by incorporating state-provided emissions 
projections for taconite facilities that apply FIP limits from the 
first implementation period. LADCO's 2028 future year inventory used 
the National Emissions Inventory Collaborative's 2016 emissions 
inventory with updates.
    According to the modeling, the 2028 RPGs for the most impaired days 
are 13.4 dv for Boundary Waters and 13.6 dv for Voyageurs. The 2028 
RPGs for the clearest days are 4.5 dv for Boundary Waters and 5.3 dv 
for Voyageurs. See Table 65 of the Minnesota plan. Minnesota's long-
term strategy and the RPGs 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, in accordance with 40 CFR 51.308(f)(3)(i).
    Section 51.308(f)(3)(i) also specifies that RPGs must reflect 
``enforceable emissions limitations, compliance schedules, and other 
measures required under paragraph (f)(2) of this section'' (emphasis 
added). EPA interprets this provision as requiring that only emission 
reduction measures that states--including upwind states--have 
determined to be necessary for reasonable progress and incorporated 
into their long-term strategies be reflected in a Class I area's RPGs. 
This ensures that RPGs include only those measures that are reasonably 
certain to be implemented. Minnesota detailed these measures in section 
2.6.2 of its plan. Minnesota used the known measures at the time when 
it developed the 2016 model platform. The measures reflected in the 
modeling for the RPGs for Boundary Waters and Voyageurs are summarized 
on Table 66 of the Minnesota plan. Emission changes that were not 
included in the RPG modeling are also noted on Table 66. In determining 
the RPGs, Minnesota also included the unit retirements at Minnesota 
Power's Boswell Energy Center Units 1 and 2, Minnesota Power's Taconite 
Harbor Energy Center, the Virginia Department of Public Utilities, Xcel 
Energy's Allen S. King, and Sherco's Units 1 and 2. Additionally, 
Minnesota factored in projected additional use of units to offset the 
generation capacity from the retiring units. Minnesota reflected 
additional use of Sherco's Unit 3, Minnesota Power's Boswell Energy 
Center Units 3 and 4, and Hibbing Public Utilities Units 1A, 2A, and 3A 
in the RPGs. Minnesota did not know about emission reductions required 
at Cleveland Cliffs Minorca facility and at Hibbing Taconite at the 
time modeling was being conducted. As a result, this is not reflected 
in the RPGs. Minnesota provides the long-term strategy measures 
reflected in the RPGs for Boundary Waters and Voyageurs in Table 66 of 
its plan.
    The RHR at 40 CFR 51.308(f)(3)(iii) notes that the RPGs are not 
directly enforceable but will be considered by the Administrator in 
evaluating the adequacy of the measures in the implementation plan in 
providing for reasonable progress towards achieving natural visibility 
conditions at that area.
    Under 40 CFR 51.308(f)(3)(ii)(A), a state with a Class I area that 
establishes an RPG for the most impaired days that provides for a 
slower rate of improvement in visibility than the URP must calculate 
the number of years required to reach natural conditions. Because 
Minnesota's RPGs are below the URP, the demonstration requirement under 
40 CFR 51.308(f)(3)(ii)(A) is not triggered.
    Under 40 CFR 51.308(f)(3)(ii)(B), if a state contains sources that 
are reasonably anticipated to contribute to visibility impairment in a 
Class I area in another state for which a demonstration by the other 
state is required, then the

[[Page 56844]]

state must demonstrate that there are no additional emission reduction 
measures that would be reasonable to include in its long-term strategy. 
The out-of-state Class I areas with the largest visibility 
contributions from Minnesota (primarily the Michigan Class I areas) are 
well below the URP. Thus, EPA proposes to conclude that the 
demonstration requirement under 40 CFR 51.308(f)(3)(ii)(B) is not 
triggered.
    In sum, EPA proposes to determine that Minnesota has satisfied the 
applicable requirements of 40 CFR 51.308(f)(3) relating to RPGs.

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. A main requirement of this subsection is for 
states with Class I areas to submit monitoring strategies for 
measuring, characterizing, and reporting on visibility impairment. 
Compliance with this requirement may be met through participation in 
the IMPROVE network.
    Minnesota uses its participation in the IMPROVE program \43\ to 
meet the 40 CFR 51.308(f)(6) monitoring strategy requirements. 
Minnesota determined that no modifications to its strategy are 
necessary at this time. See 2.8.4 of the Minnesota plan.
---------------------------------------------------------------------------

    \43\ The IMPROVE sites also provide PM2.5 speciation 
data. Therefore, these sites are a key component of EPA's national 
fine particle monitoring in addition to being critical to tracking 
progress related to regional haze regulations.
---------------------------------------------------------------------------

    Section 51.308(f)(6)(i) requires SIPs to provide for the 
establishment of any additional monitoring sites or equipment needed to 
assess whether reasonable progress goals to address regional haze for 
all mandatory Class I Federal areas within the state are being 
achieved. The IMPROVE monitoring sites are in the two Class I areas, at 
Boundary Waters (monitor BOWA1) and Voyageurs (monitor VOYA2). 
Additionally, an IMPROVE Protocol site is located in southeastern 
Minnesota near Great River Bluffs State Park (monitor GRRI1). See 2.8.4 
and Figure 16 of the Minnesota plan.
    Section 51.308(f)(6)(ii) requires SIPs to provide for procedures by 
which monitoring data and other information are used in determining the 
contribution of emissions from within the state to regional haze 
visibility impairment at mandatory Class I Federal areas both within 
and outside the state. Minnesota used its own modeling analysis to 
conduct the contribution assessment as detailed in section 2.2.1 and 
appendix A of its plan.
    In 40 CFR 51.308(f)(6)(iii) only applies to states without a Class 
I area, requiring procedures for using monitoring data in determining 
the contribution of emissions to visibility impairment at Class I areas 
in other states. Minnesota has Class I areas, therefore this 
requirement is inapplicable.
    Section 51.308(f)(6)(iv) requires the SIP to provide for the 
reporting of all visibility monitoring data to the Administrator at 
least annually for each Class I area in the state. The monitoring 
strategy for Minnesota relies upon the continued availability of the 
IMPROVE network. Minnesota supports the continued operation of the 
IMPROVE network through both state and Federal funding mechanisms.
    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. The Minnesota emissions inventory includes VOC, 
NOX, PM2.5, PM10, NH3, and 
SO2. Minnesota rules require point sources to submit reports 
of their emissions to the state each year and an annual point source 
emissions inventory is produced (Minn. R. 7019.3000). Minnesota 
compiles a full statewide emissions inventory every three years and 
submits this data to the NEI. See 2.8.5 of the Minnesota plan.
    In 40 CFR 51.308(f)(6)(v) also requires states to include estimates 
of future projected emissions and include a commitment to update the 
inventory periodically. Minnesota noted its intention to continue to 
update the full emissions inventory on the three-year NEI cycle. See 
2.8.5 of the Minnesota plan.
    In 40 CFR 51.308(f)(6)(vi) requires a state to consider other 
elements necessary to assess and report on visibility, including 
reporting and recordkeeping. Minnesota has met the other applicable 
requirements of 40 CFR 51.308(f)(6), therefore no further elements are 
necessary for Minnesota to assess and report on visibility pursuant to 
40 CFR 51.308(f)(6)(vi).
    EPA proposes to find that Minnesota has met the requirements of 40 
CFR 51.308(f)(6) through its continued participation in the IMPROVE 
network, its contribution analysis, its emissions reporting to EPA, and 
its statewide emissions inventory.

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 
each Class I area within the state and each Class I area outside the 
state that may be affected by emissions from within that state. In 40 
CFR 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. 
The regulations in 40 CFR 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. The regulations in 40 CFR 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, 40 CFR 51.308(g)(5), which also applies to all states, 
requires an assessment of whether any significant changes in 
anthropogenic emissions within or outside the state 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.
    Minnesota submitted its previous progress report on December 30, 
2014. EPA Guidance suggests covering the period approximately from the 
first full year that was not in the previous progress report through a 
year that is as close as possible to the submission date of the SIP 
revision. Thus, Minnesota's

[[Page 56845]]

progress report covers the period of 2015 to 2021.
    Minnesota's plan in section 2.10.1 describes the status of emission 
reduction measures from the first implementation period as required by 
40 CFR 51.308(g)(1). Minnesota worked on implementing BART controls 
although Minnesota taconite facilities subject to the taconite plant 
FIP have not fully implemented BART controls pending settlement 
agreements. Minnesota also implemented its Northeast Minnesota Plan as 
part of its long-term strategy in the first period. This plan 
established voluntary combined NOX and SO2 
emission reduction targets for 2012 and 2018, which have been met.
    As noted in section 2.10.2 of its plan, Minnesota met the emission 
reduction measures during the first implementation period, by 2014. 
Minnesota notes that emissions continued to fall in the second half of 
the first period, largely driven by emission reductions from EGUs. 
Minnesota cited EPA data \44\ on EGU sector emissions. The EGU 
SO2 emissions declined from 24,366 tons in 2013 to 6,068 
tons in 2021. Similarly, EGU NOX emissions went from 24,855 
tons in 2013 to 11,392 tons in 2021.
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    \44\ See U.S. EPA, Power Sector Emissions Data, CLEAN AIR 
MARKETS PROGRAM DATA.
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    EPA proposes to find that Minnesota has met the requirements of 40 
CFR 51.308(g)(1) and (2) because its submission gives the status of 
implementation of first period emission reduction measures and a 
summary of the emission reductions achieved through such 
implementation.
    States are required by 40 CFR 51.308(g)(3) to assess the visibility 
progress of its Class I areas. Section 2.10.3 of Minnesota's SIP 
submission included summaries of the visibility conditions and the 
trend of the five-year averages through 2019 at the class I areas. For 
Boundary Waters, the 2019 five-year average visibility impairment is 
13.4 dv, down from 15.4 dv in 2014 on the most impaired days. 
Visibility conditions at Boundary Waters improved from 4.9 dv in 2014 
to 4.2 dv in 2019 on the clearest days. At Voyageurs, visibility 
improved from 16.2 dv in 2014 to 13.5 dv in 2019 on the most impaired 
days. On the clearest days at Voyageurs, the visibility improved from 
5.8 dv to 5.1 dv between 2014 and 2019. EPA proposes to find that 
Minnesota has satisfied the requirements of 40 CFR 51.308(g)(3).
    Pursuant to 40 CFR 51.308(g)(4), Minnesota provided a summary of 
2014 to 2021 NH3, NOX, PM10, 
PM2.5, SO2, and VOC emissions from all sources 
and activities, including from point, nonpoint, non-road mobile, and 
on-road mobile sources. This data is presented by sector in Tables 68 
to 82 in its plan at section 2.10.4.
    EPA proposes to find that Minnesota has satisfied the requirements 
of 40 CFR 51.308(g)(4) by providing emissions information for 
NH3, NOX, PM10, PM2.5, 
SO2, and VOC emissions by source type.
    As for the requirement of 40 CFR 51.308(g)(5) to give an assessment 
of changes impeding visibility progress, Minnesota evaluated 
contributions within and outside the state. Minnesota noted in section 
2.10.5 of its plan that it has continued to make significant progress 
in reducing anthropogenic emissions within the state. On the other 
hand, one significant increase has been VOC contributions from North 
Dakota, primarily from the oil and gas sector. Minnesota states that 
this increase has not significantly impeded progress at Minnesota's 
Class I areas. Minnesota notes these contributions may need evaluation 
in future implementation periods. EPA proposes to find that Minnesota 
has met the requirements of 40 CFR 51.308(g)(5).

I. Requirements for State and Federal Land Manager Coordination

    Section 169A(d) of the CAA 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, 40 CFR 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. 
Regardless, the opportunity for consultation must be provided at least 
60 days before a public hearing or public comment period at the state 
level. In 40 CFR 51.308(i)(2) also provides two substantive topics on 
which FLMs must be provided an opportunity to discuss with states: 
assessment of visibility impairment in any Class I area and 
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.
    On May 11, 2022, Minnesota provided its draft Regional Haze plan to 
the USFS, FWS, and the NPS for a 60-day review and comment period 
pursuant to 40 CFR 51.308(i)(2). A FLM consultation meeting was held on 
June 30, 2022. NPS staff and USFS staff attended. NPS sent a comment 
letter on July 11, 2022. USFS sent a comment letter on July 12, 2022. 
Minnesota responded to the FLM comments and included the responses on 
Table 84 in its plan in accordance with 40 CFR 51.308(i)(3). EPA 
proposes to find that Minnesota 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.
    Minnesota published the public notice for the proposed update to 
Minnesota's Regional Haze SIP in the State Register on August 22, 2022. 
The public comment period was from August 22, 2022, to October 7, 2022. 
During the public notice period, a copy of the SIP revision was made 
available at Minnesota's office in St. Paul and on its website. A 
hearing was held on September 22, 2022. Minnesota received five comment 
letters during the public comment period plus two late comment letters. 
The comment letters and Minnesota's responses are included in appendix 
H of its plan.
    Further, Minnesota stated in section 3.2 of its plan that it 
performed specific outreach to Minnesota Tribes.\45\ In these efforts, 
it contacted Minnesota Tribes to notify them throughout the planning 
process of opportunities to provide input. EPA's regional office 
routinely informs the Tribes within the Region of regional haze 
developments and notifies these Tribes about EPA proposed rulemaking. 
LADCO, Minnesota's RPO, includes these Tribes on its Regional Haze 
Technical Workgroup.
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    \45\ See 2.9.3 in Minnesota's plan.
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V. Environmental Justice Considerations

    As explained in the EPA Legal Tools to Advance Environmental 
Justice 2022 document, the CAA provides states with the discretion to 
consider environmental justice (EJ) in developing rules and measures 
related to the regional haze program. In this instance, Minnesota 
exercised this discretion. In reviewing Minnesota's analysis, EPA 
defers to Minnesota's reasonable exercise of its discretion in 
considering EJ. Minnesota notes that reductions in NOX and 
SO2 can have localized health benefits near facilities. The 
state further notes its actions required during the

[[Page 56846]]

second implementation period are not expected to worsen air quality in 
any area of the state. It expects benefits will accrue to Class I areas 
as required by the program and to communities near subject facilities. 
Based on Minnesota's proposed strategies in the second implementation 
period, new controls or limits would benefit Minnesota-identified areas 
of concern for EJ. Minnesota identified the Virginia Department of 
Public Utilities, Hibbing Public Utilities Commission, and Minnesota 
Power's Taconite Harbor Energy Center as facilities impacting 
Minnesota-identified areas of concern for EJ. The state also selected 
Minnesota Power's Boswell Energy Center as near a Minnesota-identified 
areas of concern for EJ. A summary of the facilities Minnesota 
identified as impacting an area of environmental-justice concern is 
given in Table 83 of Minnesota's plan.
    In sum, EPA is proposing approval of the SIP revision because it 
meets minimum requirements pursuant to the CAA and relevant 
implementing regulations. EPA also finds that Minnesota's consideration 
of EJ analyses in this context is reasonable. EPA encourages air 
agencies generally to evaluate EJ considerations of their actions and 
carefully consider impacts to communities. EPA considers Minnesota's EJ 
analysis but that is not the basis for EPA's decision making; 
Minnesota's SIP met the minimum applicable requirements, as explained 
above.

VI. Proposed Action

    EPA is proposing to approve the Regional Haze SIP revision 
submitted by Minnesota on December 20, 2022, as satisfying the regional 
haze requirements for the second implementation period contained in 40 
CFR 51.308(f).

VII. Incorporation by Reference

    In this rule, 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, EPA is proposing to incorporate by 
reference Minnesota Administrative Orders for Hibbing Public Utilities 
Commission, effective August 19, 2022; Minnesota Power--Taconite Harbor 
Energy Center, effective May 27, 2021, and May 17, 2022; Northshore 
Mining Company, effective August 18, 2022; Virginia Department of 
Public Utilities, effective August 16, 2022; Xcel Energy--Allen S. 
King, effective July 16, 2021; and Xcel Energy--Sherburne Generating 
Plant, effective July 16, 2021, discussed in section IV.E.1. of this 
preamble. EPA has made, and will continue to make, these documents 
generally available through www.regulations.gov and at the EPA Region 5 
Office (please contact the person identified in the FOR FURTHER 
INFORMATION CONTACT section of this preamble for more information).

VIII. 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:
     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 14094 (88 FR 21879, April 11, 
2023);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     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.);
     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);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not subject to Executive Order 13045 (62 FR 19885, 
April 23, 1997) because it approves a state program;
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001); and
     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 
Minnesota 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 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, 
February 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 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.''
    Minnesota evaluated EJ considerations as part of its SIP submission 
even though the CAA and applicable implementing regulations neither 
prohibit nor require an evaluation. EPA's evaluation of Minnesota's EJ 
considerations is described above in the section titled, 
``Environmental Justice Considerations.'' The analysis was done for the 
purpose of providing additional context and information about this 
rulemaking to the public, not as a basis of the action. EPA is taking 
action under the CAA on bases independent of Minnesota's evaluation of 
EJ. Due to the nature of the action being taken here, this action is 
expected to have a neutral to positive impact on the air quality of the 
affected area. In addition, there is no information in the record upon 
which this decision is based that is inconsistent with the stated goal 
of E.O. 12898 of achieving EJ 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.


[[Page 56847]]


    Dated: July 1, 2024.
Debra Shore,
Regional Administrator, Region 5.
[FR Doc. 2024-14851 Filed 7-10-24; 8:45 am]
BILLING CODE 6560-50-P