[Federal Register Volume 89, Number 154 (Friday, August 9, 2024)]
[Proposed Rules]
[Pages 65492-65514]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-17279]



[[Page 65491]]

Vol. 89

Friday,

No. 154

August 9, 2024

Part II





Environmental Protection Agency





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40 CFR Part 52





Air Plan Approval; Wisconsin; Second Period Regional Haze Plan; 
Proposed Rule

  Federal Register / Vol. 89, No. 154 / Friday, August 9, 2024 / 
Proposed Rules  

[[Page 65492]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R05-OAR-2021-0545; FRL-12100-01-R5]


Air Plan Approval; Wisconsin; 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 
partially approve and partially disapprove the Wisconsin regional haze 
state implementation plan (SIP) revision submitted by the Wisconsin 
Department of Natural Resources (Wisconsin or WDNR) on July 30, 2021. 
In the alternative, EPA is proposing to approve the Wisconsin regional 
haze SIP in its entirety so long as WDNR provides evidence to EPA that 
operation of coal-fired cyclone Boiler B26 at the Ahlstrom-
Munksj[ouml]--Rhinelander Mill has permanently ceased. In the event 
evidence is provided confirming the federally enforceable and permanent 
shutdown of the Ahlstrom-Munksj[ouml]--Rhinelander Mill Boiler B26, EPA 
proposes to find that Wisconsin'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, and 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 Clean Air 
Act (CAA).

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

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2021-0545 at https://www.regulations.gov or via email to 
[email protected]. For comments submitted at https://www.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: Charles Hatten, Air and Radiation 
Division (AR-18J), Environmental Protection Agency, Region 5, 77 West 
Jackson Boulevard, Chicago, Illinois 60604, (312) 886-6031, 
[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 Wisconsin's Regional Haze Submission for the 
Second Implementation Period
    A. Background on Wisconsin's First Implementation Period SIP 
Submission
    B. Wisconsin'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. Selection of Sources for Analysis
    2. Emission Measures Necessary To Make Reasonable Progress
    3. Wisconsin's Long-Term Strategy
    4. EPA's Evaluation of Wisconsin's Compliance With 40 CFR 
51.308(f)(2)(i)
    5. Consultation With States
    6. Five Additional Factors
    F. Reasonable Progress Goals
    G. Monitoring Strategy and Other Implementation Plan 
Requirements
    H. Requirements for Periodic Reports Describing Progress Towards 
the Reasonable Progress Goals
    I. Requirements for State and Federal Land Manager Coordination
V. Proposed Action
VI. Statutory and Executive Order Reviews

I. What action is EPA proposing?

    On July 30, 2021, WDNR submitted a revision to its SIP to address 
regional haze for the second implementation period. WDNR made this SIP 
submission to satisfy the requirements of the CAA's regional haze 
program pursuant to CAA sections 169A and 169B and the Regional Haze 
Rule (RHR) at 40 CFR 51.308(f). EPA is proposing to partially approve 
and partially disapprove the Wisconsin regional haze SIP. In the 
alternative, EPA is proposing to approve the Wisconsin regional haze 
SIP in its entirety in the event that WDNR provides sufficient evidence 
to EPA, before final action in this rulemaking, that coal-fired cyclone 
Boiler B26 at the Ahlstrom-Munksj[ouml]--Rhinelander Mill has 
permanently ceased operating, which typically includes evidence that 
Boiler B26 is being dismantled and/or decommissioned. In the event that 
WDNR is able to provide sufficient evidence of the federally 
enforceable and permanent shutdown of the Ahlstrom-Munksj[ouml]--
Rhinelander Mill Boiler B26, EPA is proposing to find that the 
Wisconsin regional haze SIP submission for the second implementation 
period meets the applicable statutory and regulatory requirements and 
thus proposes to approve Wisconsin's submission into its SIP. However, 
without evidence that the Ahlstrom-Munksj[ouml]--Rhinelander Mill has 
permanently ceased operation of Boiler B26, EPA proposes to partially 
approve and partially disapprove the Wisconsin regional haze SIP for 
the second implementation period. In the event that WDNR does not 
provide sufficient evidence of the federally enforceable and permanent 
shutdown of Boiler B26 at the Ahlstrom-Munksj[ouml]--Rhinelander Mill, 
EPA is proposing, for the reasons described in this document, to 
approve the elements of Wisconsin's regional haze SIP related to 
requirements contained in 40 CFR 51.308(f)(1), (f)(3) through (6), 
(g)(1)

[[Page 65493]]

through (5), and (i)(2) through (4), and disapprove the elements of 
Wisconsin's SIP related to the requirements of 40 CFR 51.308(f)(2) due 
to insufficient information regarding cessation of operations at Boiler 
B26.

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 to address visibility impairment in mandatory 
Class I Federal areas (hereinafter referred to as ``Class I areas'') 
that is ``reasonably attributable'' to a single source or small group 
of sources. 45 FR 80084, December 2, 1980. These regulations, codified 
at 40 CFR 51.300 through 51.307, represented the first phase of 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 visibility impairment that is produced by a 
multitude of anthropogenic sources and activities which are located 
across a broad geographic area and that emit pollutants that impair 
visibility. Visibility impairing pollutants include fine and coarse 
particulate matter (PM) (e.g., sulfates, nitrates, organic carbon, 
elemental carbon, and soil dust) and their precursors (e.g., sulfur 
dioxide (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 deciview, 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 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 35714 at 35768, July 1, 1999). Under the 
CAA, each SIP submission must contain ``a long-term (ten to fifteen 
years) strategy for making reasonable progress toward meeting the 
national goal,'' CAA 169A(b)(2)(B); the initial round of SIP 
submissions also had to address the statutory requirement that certain 
older, larger sources of visibility impairing pollutants install and 
operate the best available retrofit technology (BART). CAA 
169A(b)(2)(A); 40 CFR 51.308(d), (e). States' first regional haze SIPs 
were due by December 17, 2007, 40 CFR 51.308(b), with subsequent SIP 
submissions containing updated long-term strategies originally due July 
31, 2018, and every ten years thereafter. 64 FR 35714 at 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 
35714 at 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 implementation 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

[[Page 65494]]

baseline visibility conditions in 2004 and ending with natural 
conditions in 2064. This linear interpolation is known as the uniform 
rate of progress (URP) and is used as a tracking metric to help states 
assess the amount of progress they are making towards the national 
visibility goal over time in each Class I area.\6\ 40 CFR 
51.308(d)(1)(i)(B), (d)(2). The 1999 RHR also provided that states' 
long-term strategies must include the ``enforceable emissions 
limitations, compliance, schedules, and other measures as necessary to 
achieve the reasonable progress goals.'' 40 CFR 51.308(d)(3). In 
establishing their long-term strategies, states are required to consult 
with other states that also contribute to visibility impairment in a 
given Class I area and include all measures necessary to obtain their 
shares of the emission reductions needed to meet the RPGs. 40 CFR 
51.308(d)(3)(i), (ii). Section 51.308(d) also contains seven additional 
factors states must consider in formulating their long-term strategies, 
40 CFR 51.308(d)(3)(v), as well as provisions governing monitoring and 
other implementation plan requirements. 40 CFR 51.308(d)(4). Finally, 
the 1999 RHR required states to submit periodic progress reports--SIP 
revisions due every five years that contain information on states' 
implementation of their regional haze plans and an assessment of 
whether anything additional is needed to make reasonable progress, see 
40 CFR 51.308(g),(h), and to consult with the Federal Land Manager(s) 
\7\ (FLMs) responsible for each Class I area according to the 
requirements in CAA 169A(d) and 40 CFR 51.308(i).
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    \6\ EPA established the URP framework in the 1999 RHR to provide 
``an equitable analytical approach'' to assessing the rate of 
visibility improvement at Class I areas across the country. The 
start point for the URP analysis is 2004 and the endpoint was 
calculated based on the amount of visibility improvement that was 
anticipated to result from implementation of existing CAA programs 
over the period from the mid-1990s to approximately 2005. Assuming 
this rate of progress would continue into the future, EPA determined 
that natural visibility conditions would be reached in 60 years, or 
2064 (60 years from the baseline starting point of 2004). However, 
EPA did not establish 2064 as the year by which the national goal 
must be reached. 64 FR 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 states' SIPs contain long-term 
strategies for making reasonable progress towards the national 
visibility goal. The reasonable progress requirements as revised in the 
2017 rulemaking (referred to here as the 2017 RHR Revisions) are 
codified at 40 CFR 51.308(f). Among other changes, the 2017 RHR 
Revisions adjusted the deadline for states to submit their second 
implementation period SIPs from July 31, 2018 to July 31, 2021, 
clarified the order of analysis and the relationship between RPGs and 
the long-term strategy, and focused on making visibility improvements 
on the days with the most anthropogenic visibility impairment, as 
opposed to the days with the most visibility impairment overall. 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/sites/default/files/2021-03/documents/tracking.pdf 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. EPA also 
recognizes that analyses regarding reasonable progress are state-
specific and that, based on states' and sources' individual 
circumstances, what constitutes reasonable reductions in visibility 
impairing pollutants will vary from state-to-state. While there exist 
many opportunities for states to leverage both ongoing and upcoming 
emission reductions under other CAA programs, EPA 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 (PSD) 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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[[Page 65495]]

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 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) is the Midwest 
RPO, and includes the states of Illinois, Indiana, Michigan, Minnesota, 
Ohio, and Wisconsin. LADCO's work 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 corridor of the United States. The Federal partner 
members of LADCO are 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 must then 
develop a long-term strategy that includes the enforceable emission 
limitations, compliance schedules, and other measures that are 
necessary to make reasonable progress in such areas. A reasonable 
progress determination is based on applying the four factors in CAA 
section 169A(g)(1) to sources of visibility-impairing pollutants that 
the state has selected to assess for controls for the second 
implementation period. Additionally, as further explained below, the 
RHR at 40 CFR 51.3108(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 the Agency was 
adopting new regulatory language in 40 CFR 51.308(f) that, unlike 
the structure in 51.308(d), ``tracked the actual planning 
sequence.'' (82 FR 3078 at 3091, January 10, 2017).
    \15\ The five ``additional factors'' for consideration in 
section 51.308(f)(2)(iv) are distinct from the four factors listed 
in CAA section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states 
must consider and apply to sources in determining reasonable 
progress.
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    In addition to satisfying the requirements at 40 CFR 51.308(f) 
related to reasonable progress, the regional haze SIP revisions for the 
second implementation period must address the requirements in 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 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

[[Page 65496]]

does not require this evaluation to be conducted in any particular 
manner, EPA's 2019 Guidance provides recommendations for how such an 
assessment might be accomplished, including by, where appropriate, 
using the determinations previously made for the first implementation 
period. 2019 Guidance at 8-9. In addition, the determination of which 
Class I areas may be affected by a state's emissions is subject to the 
requirement in 40 CFR 51.308(f)(2)(iii) to ``document the technical 
basis, including modeling, monitoring, cost, engineering, and emissions 
information, on which the state is relying to determine the emission 
reduction measures that are necessary to make reasonable progress in 
each mandatory Class I Federal area it affects.''

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

    As part of assessing whether a SIP submission for the second 
implementation period is providing for reasonable progress towards the 
national visibility goal, the RHR contains requirements in 40 CFR 
51.308(f)(1) related to tracking visibility improvement over time. The 
requirements of this section apply only to states having Class I areas 
within their borders; the required calculations must be made for each 
such Class I area. EPA's 2018 Visibility Tracking Guidance \16\ 
provides recommendations to assist states in satisfying their 
obligations under 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% 
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.''
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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).
    Section 51.308(f)(2)(i) provides the requirements for the four-
factor

[[Page 65497]]

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 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\
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

    Thus, while states have discretion to choose any source selection 
methodology that is reasonable, whatever choices they make should be 
reasonably explained. To this end, 40 CFR 51.308(f)(2)(i) requires that 
a state's SIP submission include ``a description of the criteria it 
used to determine which sources or groups of sources it evaluated.'' 
The technical basis for source selection, which may include methods for 
quantifying potential visibility impacts such as emissions divided by 
distance metrics, trajectory analyses, residence time analyses, and/or 
photochemical modeling, must also be appropriately documented, as 
required by 40 CFR 51.308(f)(2)(iii).
    Once a state has selected the set of sources, the next step is to 
determine the emissions reduction measures for those sources that are 
necessary to make reasonable progress for the second implementation 
period.\21\ This is accomplished by considering the four factors: ``the 
costs of compliance, the time necessary for compliance, and the energy 
and non-air quality environmental impacts of compliance, and the 
remaining useful life of any existing source subject to such 
requirements.'' CAA 169A(g)(1). 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

[[Page 65498]]

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 
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.
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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; (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

[[Page 65499]]

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 implementation 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.
---------------------------------------------------------------------------

    \26\ The five ``additional factors'' for consideration in 
section 51.308(f)(2)(iv) are distinct from the four factors listed 
in CAA section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states 
must consider and apply to sources in determining reasonable 
progress.
---------------------------------------------------------------------------

    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. 
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

    RPGs ``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.
---------------------------------------------------------------------------

    \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, control 
determinations by other states, and 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. 
RPGs 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

[[Page 65500]]

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

    40 CFR 51.308(f)(6) requires states to have certain strategies and 
elements in place for assessing and reporting on visibility. Individual 
requirements under this section 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 percent 
most anthropogenically impaired and 20 percent clearest sets of days 
every year at each Class I area and tracks visibility impairment over 
time.
    All states' SIPs must provide for procedures by which monitoring 
data and other information are used to determine the contribution of 
emissions from within the state to regional haze visibility impairment 
in affected Class I areas. 40 CFR 51.308(f)(6)(ii), (iii). Section 
51.308(f)(6)(v) further requires that all states' SIPs provide for a 
statewide inventory of emissions of pollutants that are reasonably 
anticipated to cause or contribute to visibility impairment in any 
Class I area; the inventory must include emissions for the most recent 
year for which data are available and estimates of future projected 
emissions. States must also include commitments to update their 
inventories periodically. The inventories themselves do not need to be 
included as elements in the SIP and are not subject to EPA review as 
part of the Agency's evaluation of a SIP revision.\28\ All states' SIPs 
must also provide for any other elements, including reporting, 
recordkeeping, and other measures, that are necessary for states to 
assess and report on visibility. 40 CFR 51.308(f)(6)(vi). Per the 2019 
Guidance, a state may note in its regional haze SIP that its compliance 
with the Air Emissions Reporting Rule (AERR) in 40 CFR part 51, subpart 
A satisfies the requirement to provide for an emissions inventory for 
the most recent year for which data are available. To satisfy the 
requirement to provide estimates of future projected emissions, a state 
may explain in its SIP how projected emissions were developed for use 
in establishing RPGs for its own and nearby Class I areas.\29\
---------------------------------------------------------------------------

    \28\ See ``Step 8: Additional requirements for regional haze 
SIPs'' in 2019 Guidance at 55.
    \29\ Id.
---------------------------------------------------------------------------

    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 reasonably 
attributable visibility impairment, the state must include in its SIP 
revision for the second implementation period an appropriate strategy 
for evaluating such impairment.
---------------------------------------------------------------------------

    \30\ EPA's visibility protection regulations define ``reasonably 
attributable visibility impairment'' as ``visibility impairment that 
is caused by the emission of air pollutants from one, or a small 
number of sources.'' 40 CFR 51.301.
---------------------------------------------------------------------------

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

    Section 51.308(f)(5) requires a state's regional haze SIP revision 
to address the requirements of paragraphs 40 CFR 51.308(g)(1) through 
(5) so that the plan revision due in 2021 will serve also as a progress 
report addressing the period since submission of the progress report 
for the first implementation period. The regional haze progress report 
requirement is designed to inform the public and 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

[[Page 65501]]

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 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 Wisconsin's Regional Haze Submission for the 
Second Implementation Period

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

    Wisconsin submitted its regional haze SIP for the first 
implementation period for 2009 through 2018 to EPA on January 18, 2012. 
EPA approved Wisconsin's first implementation period regional haze SIP 
submission on August 7, 2012 (77 FR 46952, August 7, 2012). EPA's 
approval included, but was not limited to, the portions of the plan 
that address the reasonable progress requirements, Wisconsin's 
implementation of BART on eligible sources, and adoption of limitations 
as necessary to implement a long-term strategy for reducing visibility 
impairment. The requirements for regional haze SIPs for the first 
implementation period are contained in 40 CFR 51.308(d) and (e). See 40 
CFR 51.308(b). WDNR met the requirements of 40 CFR 51.308(g) by 
submitting its five-year progress report for the first implementation 
period on March 17, 2017. EPA approved this progress report as a 
revision to the Wisconsin SIP on June 15, 2018 (83 FR 27910, June 15, 
2018).

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

    In accordance with CAA sections 169A and the RHR at 40 CFR 
51.308(f), on July 30, 2021, WDNR submitted a revision to the Wisconsin 
SIP to address its regional haze obligations for the second 
implementation period, which runs through 2028. Wisconsin provided a 
public comment period on the regional haze SIP for the second 
implementation period from April 29 through June 2, 2021. Wisconsin 
received and responded to public comments and included the comments and 
responses to those comments in appendix 8 of its submission. 
Subsequently, Wisconsin provided additional information regarding the 
likely permanent cessation of coal-fired cyclone Boiler B26 at the 
Ahlstrom-Munksj[ouml]--Rhinelander Mill.
    The following sections describe Wisconsin's SIP submission, 
including Wisconsin's assessment of progress made since the first 
implementation period in reducing emissions of visibility impairing 
pollutants, and the visibility improvement progress at nearby Class I 
areas. Also described is the additional information which Wisconsin 
provided on November 10, 2023, and January 3, 2024, regarding the newly 
planned retirement of two sources evaluated under the four-factor 
analysis and the current retirement plan for a third source. The 
following section also contains EPA's evaluation of Wisconsin's 
submission against the requirements of the CAA and the 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 51.308(f)(2), which requires each state's plan to include 
a long-term strategy that addresses regional haze in such Class I 
areas.
    Wisconsin has no Class I areas within its borders that are among 
the 156 mandatory Class I Federal areas where EPA deemed visibility to 
be an important value.\31\ See 40 CFR part 81, subpart D. Thus, WDNR 
only considered out-of-state mandatory Class I areas covered under the 
RHR.
---------------------------------------------------------------------------

    \31\ Rainbow Lake Wilderness Area is a mandatory Class I Federal 
area located in Wisconsin but has not been identified by the 
Secretary of the Interior in consultation with other FLMs as an area 
where visibility is an important value. 44 FR 69122, November 30, 
1979. Therefore, Rainbow Lake Wilderness Area is not among the list 
of areas to which the requirements of the visibility protection 
program apply in 40 CFR part 81, subpart D.
---------------------------------------------------------------------------

    Wisconsin is a member of LADCO and participated in LADCO's regional 
approach for developing a strategy for making reasonable progress 
towards national visibility in the northern Midwest Class I areas. WDNR 
reviewed technical analyses conducted by LADCO to determine which Class 
I areas outside the state are affected by Wisconsin emission sources. 
For the second regional haze implementation period, to determine LADCO 
member state contributions to impaired visibility in all Class I areas, 
LADCO used the Comprehensive Air quality Model with extensions 
Particulate Matter Source Apportionment tool (PSAT). LADCO tagged 
states and regions as well as individual point sources and inventory 
source groups to apportion emissions to states and regions. LADCO 
assessed

[[Page 65502]]

relative visibility impacts in 2028 by projecting representative 
emissions inventories and known emission controls from 2016.\32\ For 
modeling purposes, 2016 was chosen as the base year. A group of RPOs, 
states, and EPA established 2016 as the base year for a national air 
quality modeling platform for future ozone, PM2.5 and 
regional haze SIP development because of fairly typical ozone 
conditions and wildfire conditions.\33\ LADCO relied upon EPA's 
inventory estimates from the 2016 modeling platform for most emission 
sectors. For Electric Generating Units (EGUs), LADCO used forecasts 
from the Eastern Regional Technical Advisory Committee (ERTAC) based on 
continuous emissions monitoring data from 2016 instead of the 
Integrated Planning Model used in EPA's 2016 modeling platform. LADCO 
also incorporated state-reported changes to EGUs received through 
September 2020 to estimate 2028 EGU emissions, which was considered by 
LADCO to be the best available information on EGU forecasts for the 
Midwest and Eastern U.S. available at the time.
---------------------------------------------------------------------------

    \32\ See appendix 2 of WDNR's SIP submittal. Details of the 
analysis and source-apportioned visibility contributions at Class I 
areas within the LADCO region for regional haze second 
implementation period are documented in LADCO's modeling technical 
support document (TSD), dated June 17, 2021.
    \33\ See ``Base Year Selection Workgroup Final Report,'' April 
5, 2017.
---------------------------------------------------------------------------

    Wisconsin identified affected Class I areas where progress toward 
natural visibility conditions may be impacted by emissions from sources 
in Wisconsin. Wisconsin used LADCO's modeled emissions projections for 
2028 as a framework to assess the potential for future growth in 
visibility-impairing emissions. Like the metrics used in the first 
implementation period, WDNR retained the 2 percent light extinction 
threshold for determining Wisconsin's contribution to visibility at 
Class I areas for the second regional haze implementation period. 
LADCO's modeling results showed that a 2 percent light extinction 
threshold applied to all six LADCO states as well as seven other states 
would account for 92 percent or more of the total light extinction at 
the Class I areas located in the LADCO states on the most impaired 
days. Using a 2 percent total light extinction threshold, WDNR 
determined that Wisconsin emissions continue to impact visibility 
impairment at Isle Royale National Park (Isle Royale) and Seney 
Wilderness Area (Seney) in Michigan and Boundary Waters Canoe 
Wilderness Area (Boundary Waters) in Minnesota. Although Wisconsin's 
contribution to total light extinction at Voyageurs National Park 
(Voyageurs) in Minnesota is 1 percent based on LADCO's 2016-based PSAT 
projections for 2028, Wisconsin included Voyageurs because it met the 2 
percent threshold during the first regional haze implementation period. 
These four Class I areas in Michigan and Minnesota are collectively 
referred to as the ``LADCO Class I Areas.'' During the first 
implementation period, LADCO estimated Wisconsin's average annual 
impact on visibility in the LADCO Class I Areas ranged from 6 to 16 
percent, whereas LADCO's 2028 projections forecast a reduction in 
Wisconsin's average annual impact on visibility of 1 to 6.2 percent for 
the second implementation period.

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. Section 51.308(f)(1) 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).
    Wisconsin has no mandatory Federal Class I areas identified in 40 
CFR part 81, subpart D, located within the state to which the 
requirements of the visibility protection program apply. Therefore, 40 
CFR 51.308(f)(1) and its requirements do not apply.

E. Long-Term Strategy for Regional Haze

    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 
preamble, 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).
1. Selection of Sources for Analysis
    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.
    This section summarizes how Wisconsin's SIP submission addresses 
the requirements of 40 CFR 51.308(f)(2)(i) of the RHR. Specifically, it 
describes the criteria WDNR used to determine the selection of sources 
or groups of sources it evaluated for an analysis of potential emission 
control measures.
    WDNR considered NOX, SO2, PM2.5, 
and NH3 in selecting sources to determine possible 
additional control measures during the second

[[Page 65503]]

implementation period. To assist states with their source selection, 
using the 2016 base year emissions, LADCO generated source lists based 
on total process-level emissions (Q) divided by distance (d) to the 
nearest Class I area, where Q/d is used as a quantitative metric of 
visibility impact. Total emissions of Q refer to the sum of 
NOX, SO2, PM2.5, and NH3. 
The National Emissions Inventory (NEI) Collaborative 2016 alpha 
inventory was selected by participants in the LADCO Regional Haze 
Technical Workgroup for the Q/d analysis in 2018 as the best available 
inventory at that time. LADCO identified unit level sources above Q/d 
thresholds of 1, 4, and 10, providing key information the states could 
use to select potential sources to be subject to the four-factor 
analysis. For details on the data and methods used in the Q/d analysis, 
see section 5 of LADCO's Technical Support Document ``Modeling and 
Analysis for Demonstrating Reasonable Progress for the Regional Haze 
Rule 2018--2028 Planning Period,'' contained in appendix 2 of 
Wisconsin's SIP submission.
    WDNR used the Q/d information developed by LADCO to select emission 
units with a Q/d threshold greater than a value of 10 for a four-factor 
analysis. WDNR set the Q/d threshold of 10 to capture the significant 
point source emissions in Wisconsin for analysis. WDNR identified units 
with a Q/d threshold greater than a value of 10 at three facilities: 
Alliant Energy--Edgewater Generating Station; Ahlstrom-Munksj[ouml] NA 
Specialty Solutions, LLC--Kaukauna Kraft Pulp and Paper Mill (Ahlstrom-
Munksj[ouml] Kaukauna Mill); and the Ahlstrom-Munksj[ouml] NA Specialty 
Solutions, LLC--Rhinelander Paper Mill (Ahlstrom-Munksj[ouml]--
Rhinelander Mill). The emission units selected at each facility meeting 
WDNR's threshold for four-factor analysis are described below. 
Consistent with the first regional haze implementation period, WDNR 
focused on NOX and SO2 emissions in considering 
potential additional control measures at these facilities since they 
lead to the formation of the particulate species of nitrate and sulfate 
that currently contribute more to visibility impairment in the LADCO 
Class I Areas than PM2.5, NH3, and VOC as 
demonstrated by the analysis in LADCO's Technical Support Document of 
the IMPROVE monitoring data. As shown in Tables 6, 12 and A2-2 of its 
submittal, WDNR's selected sources represent more than 38 percent of 
the total SO2 emissions and 13 percent of the total NOx 
emissions for Wisconsin point sources with a Q/d greater than 1 based 
on 2016 emissions, with the Ahlstrom-Munksj[ouml]--Kaukauna and 
Rhinelander Mills representing 23 percent and 6 percent of the 
SO2 emissions, respectively, and 1 percent of the NOx 
emissions each.
Alliant Energy--Edgewater
    Alliant Energy is a coal-fired electric generating facility located 
in Sheboygan, Wisconsin. WDNR selected coal-fired Boilers B24 and B25 
for the control analysis. Boiler B25 has a nameplate capacity of 380 
MW. Boiler B24 was retired in 2018.
Ahlstrom-Munksj[ouml]--Kaukauna Mill
    The Ahlstrom-Munksj[ouml]--Kaukauna Mill is a kraft pulp and paper 
mill located in Kaukauna, Wisconsin that manufactures unbleached pulp. 
For the control analysis, WDNR selected single cyclone steam Boiler 
B09, which has a fuel capacity of 192 million British Thermal Units per 
hour (MMBtu/hr), and twin cyclone Boiler B11, which has a fuel capacity 
of 379 MMBtu/hr. Boilers B09 and B11 operate in tandem and share a 
common stack S09. Boilers B11 and B09 are used to produce steam for the 
mill production process and electricity generation, and both are 
capable of combusting multiple fuels that include bituminous coal, pet 
coke, natural gas, #6 fuel oil, paper broke, or tire derived fuel.
Ahlstrom-Munksj[ouml]--Rhinelander Mill
    The Ahlstrom-Munksj[ouml]--Rhinelander Mill is a paper mill located 
in Rhinelander, Wisconsin producing a variety of specialty papers 
including greaseproof, label backing, and wet strength papers. For the 
control analysis, WDNR selected coal-fired cyclone Boiler B26 which has 
a fuel capacity of 300 MMBtu/hr. Boiler B26 is used to produce steam 
for the manufacturing operations.
Other Sources
    During the FLM consultation period, the USFS and NPS encouraged 
WDNR to lower the Q/d source selection threshold to 4 on a facility-
wide basis, thereby identifying the following additional facilities for 
further analysis: WE Energies--Oak Creek Power Plant, Wisconsin Public 
Service Corporation--Weston Power Plant, Wisconsin Rapids Paper Mill, 
Catalyst Paper--Biron Mill, Graymont Superior, Ahlstrom-Munksj[ouml]--
Mosinee Mill, and Calumet Superior Refinery.\34\
---------------------------------------------------------------------------

    \34\ Comments from USFS and NPS referenced by WDNR with a 
provided link in the Regional Haze SIP submittal are provided in the 
docket.
---------------------------------------------------------------------------

    The USFS and NPS recognized that the Wisconsin Rapids Paper Mill 
has been idled and that the Wisconsin Public Service Corporation--
Weston Power Plant and the WE Energies--Oak Creek Power Plant are 
effectively controlled. However, USFS and NPS recommended that WDNR 
perform a four-factor analysis for Catalyst Paper--Biron Mill, Graymont 
Superior, Ahlstrom-Munksj[ouml]--Mosinee Mill, and Calumet Superior 
Refinery.\35\
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    \35\ Wisconsin provided a link to WDNR's website with comments 
from USFS and NPS, which are included in the docket.
---------------------------------------------------------------------------

    WDNR provided information in appendices 2 and 3 demonstrating that 
while the additional sources identified by the FLMs exhibited Q/d 
values greater than 4 on a facility-wide basis, none of the Q/d values 
on a unit basis were greater than 4.3 for the EGUs or 4 for the non-
EGUs except Catalyst Paper--Biron Mill Boiler B23 with a Q/d of 7. 
Although WDNR's source selection threshold based on unit Q/d greater 
than 10 did not identify these sources for further analysis, WDNR 
provided information in appendix 3 as summarized below, describing that 
these sources flagged by the FLMs are already well-controlled and have 
federally enforceable limits in title V operating permits.
    The Wisconsin Public Service Corporation--Weston Power Plant is 
subject to limits of 0.10 pounds per million British thermal units 
(lbs/MMBtu) NOX and 0.08 lbs/MMBtu SO2. The WE 
Energies--Oak Creek Power Plant utilizes selective catalytic reduction 
(SCR) and wet flue gas desulfurization (FGD), is subject to limits of 
0.07 lbs/MMBtu NOX and 0.03 lbs/MMBtu SO2 and 
will retire four of its six boilers in 2025. The Wisconsin Rapids Paper 
Mill has been idled since 2020, but in the event the facility resumes 
operation, the units are subject to permit limits of 1.2 lbs/MMBtu 
SO2 and 0.80 lbs/MMBtu NOX, low sulfur coal 
requirements, and SO2 modeling to demonstrate compliance 
with the 2010 1-hour SO2 NAAQS. For Catalyst Paper--Biron 
Mill, Boiler B23 switched to natural gas in 2017. For Graymont 
Superior, units are subject to Best Available Control Technology (BACT) 
for NOX as well as permit requirements based on 
SO2 modeling to demonstrate compliance with the 2010 1-hour 
SO2 NAAQS. For the Ahlstrom-Munksj[ouml]--Mosinee Mill, 
Boiler B20 is subject to a permit limit of 3.2 lbs-SO2/MMBtu 
as well as permit requirements based on SO2 modeling to 
demonstrate compliance with the 2010 1-hour SO2 NAAQS. 
Calumet Superior Refinery is

[[Page 65504]]

subject to a Federal consent decree with limits that were incorporated 
into its title I construction permit 11-DCF-138 and title V operating 
permit to achieve NOX and SO2 reductions from 
boilers, fluid catalytic cracking units, and heaters.
    Additionally, Wisconsin noted that the Alliant Energy--Columbia 
Power Plant has two units, B21 and B22, each with a Q/d of 6, that are 
also well-controlled and scheduled to shut down in 2025. Although not 
selected for further analysis, Wisconsin indicated that for 
NOX, B21 has low NOX burners (LNB) and over-fire 
air (OFA) with a 0.15 lbs/MMBtu limit, and B22 has SCR/LNB/OFA with a 
0.07 lbs/MMBtu limit. For SO2, both B21 and B22 have dry FGD 
with a 0.075 lbs/MMBtu limit, well below the SO2 limit of 
0.2 lbs/MMBtu in the Mercury and Air Toxics Standards (MATS) rule for 
coal-fired EGUs. Wisconsin also pointed out that the planned shutdown 
of Alliant Energy--Columbia was not relied upon in assessing visibility 
impacts in the LADCO modeling.

2. Emission Measures Necessary To Make Reasonable Progress

    Section 51.308(f)(2)(i) requires states to evaluate and determine 
the emission reduction measures that are necessary to make reasonable 
progress by applying the four statutory factors to sources in a control 
analysis. 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).
    Wisconsin's plan initially relied on four-factor analyses compiled 
by LADCO in 2015 for the second implementation period, which evaluated 
potential control scenarios for various types of coal-fired industrial 
boilers at pulp and paper mills that could be implemented by LADCO 
states to reduce emissions from large sources of NOX and 
SO2 to make reasonable progress toward visibility goals. 
LADCO evaluated control options for NOX that included 
combustion modifications consisting of boiler tuning, LNB, ultra-low 
NOX burners (ULNB), LNB and flue gas recirculation, and LNB 
and OFA, as well as post-combustion controls consisting of SCR, 
selective noncatalytic reduction, and regenerative selective catalytic 
reduction (RSCR). For SO2, LADCO evaluated control options 
for conventional dry FGD and dry sorbent injection (DSI), conventional 
dry FGD and spray dryer, advanced FGD, and wet FGD. LADCO's four-factor 
analyses included ranges in values for removal efficiencies and cost 
effectiveness based on retrofitting controls on boilers from various 
sources, noting that the actual costs depend on utilization and size of 
the boiler as well as capital costs. LADCO also provided analyses for 
the other statutory factors: time necessary for compliance, energy and 
non-air impacts, and remaining useful life.
    To build upon the 2015 LADCO four-factor analyses with site 
specific data, WDNR conducted four-factor analyses specifically for the 
sources selected during the second implementation period: the Ahlstrom-
Munksj[ouml]--Kaukauna and Rhinelander Mills.\36\ The four-factor 
analyses examined control options and costs for SO2 and 
NOX by drawing on a BART analysis that WDNR performed during 
the first implementation period for the Georgia Pacific--Broadway Mill 
in Green Bay, another Wisconsin paper mill with a boiler of similar 
design and configuration to those at the Ahlstrom-Munksj[ouml]--
Kaukauna and Rhinelander Mills. WDNR examined control options for 
SO2 that included DSI, dry FGD, and wet FGD as well as 
options for NOX that included OFA, RSCR, and OFA/RSCR. WDNR 
scaled the boiler size and associated costs from the Georgia Pacific--
Broadway Mill to fit the Ahlstrom-Munksj[ouml]--Kaukauna and 
Rhinelander Mills. WDNR also adjusted the cost figures from 2007 to 
2019 using the 2020 Chemical Engineering Plant Cost Index as 
recommended by EPA's Control Cost Manual.\37\
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    \36\ Details derived from the 2015 LADCO four-factor analysis 
and BART analysis can be found in appendices 2 and 4 of Wisconsin's 
plan.
    \37\ See ``EPA Air Pollution Control Cost Manual, section 1, 
Chapter 2, Cost Estimation: Concepts and Methodology,'' November 
2017, available at: https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution.
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    After submitting its plan on July 30, 2021, WDNR indicated on 
November 10, 2023, and January 3, 2024, updates on the delayed 
retirement of a boiler at Alliant Energy--Edgewater and the newly 
planned retirements of boilers at the Ahlstrom-Munksj[ouml]--
Rhinelander and Kaukauna Mills. As described below, WDNR's additional 
information documented existing effective measures for Alliant Energy--
Edgewater and the enforceable retirement of Boiler B11 at the Ahlstrom-
Munksj[ouml]--Kaukauna Mill, and described WDNR's plans to issue a 
title V permit with the enforceable retirement of Boiler B26 at the 
Ahlstrom-Munksj[ouml]--Rhinelander Mill in 2024.
Alliant Energy--Edgewater
    Of the two coal-fired boilers selected for further analysis by WDNR 
at Alliant Energy--Edgewater, Boiler B24 was retired in 2018. Then WDNR 
noted that in 2020, Alliant Energy publicly announced plans to close 
the Edgewater electrical generation facility and retire the remaining 
coal-fired boiler, Boiler B25, by the end of 2022. Since Boiler B25 was 
expected to retire in 2022, WDNR initially determined no further 
analysis of additional or new emission control measures was necessary. 
However, in June 2022, Alliant Energy announced the retirement of 
Boiler B25 would be delayed until June 2025. Therefore, on November 10, 
2023, WDNR updated EPA with additional information, described below, 
explaining its decision to forgo a full four-factor analysis on the 
basis that the existing controls for Boiler B25 are effective and not 
necessary for reasonable progress.
    The coal-fired Boiler B25 has operated a dry flue gas 
desulfurization scrubber for SO2 control since 2016 and an 
SCR system for NOX control since 2014. Based on Clean Air 
Markets Program Data for Boiler B25 in 2022, SO2 control 
performance of 0.0515 lbs/MMBtu is among the top 20 percent nationally, 
and NOX control performance of 0.0499 lbs/MMBtu is among the 
top 10 percent nationally for dry bottom wall-fired boilers with FGDs 
and SCRs. In addition, as part of a Federal consent decree, the 
SO2 and NOX emissions for Boiler B25 are both 
subject to permanent and enforceable plant-wide tonnage limitations as 
well as a 30-day rolling average limit of 0.075 lbs/MMBtu of 
SO2 and 0.080 lbs/MMBtu of NOX and a 12-month 
rolling average limit of 0.070 lbs/MMBtu of SO2 and 0.070 
lbs/MMBtu of NOX. See 85 FR 28550 (May 13, 2020). The 
conditions of this consent decree were made permanent by inclusion in 
the title I construction permit No. 13-POY-154-R1 and are also 
contained in the facility's current title V Federal operating permit 
No. 460033090-P31. With SO2 limits below those in the 2012 
MATS rule for power plants, and controls that were recently installed, 
including an FGD for SO2 control that has been operating 
since 2016 and an SCR for NOX control that has been 
operating since 2014, an analysis of control measures would be unlikely 
to conclude that more stringent controls are necessary for reasonable 
progress. As such, even with the delay in retirement, WDNR determined 
that no further analysis of additional or new emission control measures 
was necessary and reiterated in the additional information that WDNR 
considers Boiler B25 effectively controlled.

[[Page 65505]]

    As explained in EPA's July 8, 2021, Clarifications Memo (section 
4.1), a source's existing measures are generally needed to prevent 
future visibility impairment (i.e., to prevent future emission 
increases) and are thus necessary to make reasonable progress. Measures 
that are necessary to make reasonable progress must be included in the 
SIP. However, if a state can demonstrate that a source will continue to 
implement its existing measures and will not increase its emission 
rate, it may not be necessary to require those measures under the 
regional haze program in its long-term strategy or SIP in order to 
prevent future emission increases.
    WDNR provided a weight-of-evidence demonstration as described in 
the 2021 Clarifications Memo to demonstrate that the source has 
consistently implemented its existing measures and has achieved, using 
those measures, a reasonably consistent emission rate. This 
demonstration included heat input and emission rates for Boiler B25 
from 2017 through 2022, ranging from 0.0435 to 0.0557 lbs/MMBtu for 
SO2 and from 0.0336 to 0.0499 lbs/MMBtu for NOX, 
while remaining below the limits in the Federal consent decree across a 
range of heat inputs from 12,373,316 to 25,629,492 MMBtu. With 
historical data from 2016 through 2022 showing reasonably consistent 
emission rates, WDNR demonstrated that NOX and 
SO2 emission rates for Boiler B25 are not expected to 
increase in the future since consent decree emission limits and 
associated control technologies will remain in place and compliance 
with the emission rate limits have already been demonstrated under a 
wide range of heat input conditions.\38\ With the combination of 
recently installed SO2 and NOX controls along 
with limits in the Federal consent decree that ensure emission rates 
will not increase, including an SO2 limit well below the 
SO2 limit of 0.2 lbs/MMBtu in the MATS rule for coal-fired 
EGUs, WDNR determined the existing measures are not necessary to make 
reasonable progress or prevent future emission increases and, thus, do 
not need to be included in the regulatory portion of the SIP.
---------------------------------------------------------------------------

    \38\ See November 10, 2023, supplemental information.
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Ahlstrom-Munksj[ouml]--Rhinelander Mill
    At the Ahlstrom-Munksj[ouml]--Rhinelander Mill, coal-fired Boiler 
B26 is equipped with an electrostatic precipitator (ESP) for control of 
particulate matter and a DSI system for hydrochloric acid control to 
achieve Boiler Maximum Achievable Control Technology (MACT) limits and 
some SO2 control as a co-benefit. The SO2 
emissions from Boiler B26 were previously limited during the first 
implementation period to 3.50 lbs/MMBtu under a consent order issued by 
WDNR and then later to 3.00 lbs/MMBtu, averaged over 24 hours, included 
in title V Federal operating permit No. 744008100-P21, which became 
effective in 2017.
    In December 2020, the Ahlstrom-Munksj[ouml]--Rhinelander Mill was 
identified as a primary source of SO2 emissions in the 
Rhinelander area, and EPA designated a portion of Oneida County as 
nonattainment for the 2010 1-hour SO2 NAAQS. The Ahlstrom-
Munksj[ouml]--Rhinelander Mill was subject to SO2 modeling 
requirements to demonstrate compliance with the SO2 NAAQS in 
the Rhinelander area pursuant to Wisconsin's air pollution control rule 
Chapter NR 404 of the Wisconsin Administrative Code. On March 29, 2021, 
Wisconsin submitted a SIP and an attainment plan for the 2010 
SO2 NAAQS. On July 28, 2021, WDNR submitted a request for 
EPA to redesignate the Rhinelander nonattainment area to attainment of 
the 2010 SO2 NAAQS. On October 22, 2021, EPA approved 
Wisconsin's attainment plan for the Rhinelander area, which relied on 
federally enforceable and permanent emissions limits specified in title 
I Air Pollution Control Construction Permit Revision 15-DMM-128-R1 \39\ 
with a more stringent SO2 limit (2.38 lbs/MMBtu on a 24-hour 
average basis) than the previously permitted limit (3.00 lbs/MMBtu on a 
24-hour average basis) as well as a heat input limit of 260 MMBtu/hr. 
WDNR's Preliminary Determination for permit 15-DMM-128-R1 demonstrated 
that the new limits for SO2 and heat input reduce the 
potential to emit NOX by 13 percent and SO2 by 31 
percent. These limits were incorporated into Wisconsin's SIP at 40 CFR 
52.2570(144)(i). 86 FR 58577 (October 22, 2021). Effective January 12, 
2022, EPA redesignated the Rhinelander area to attainment. 87 FR 1685 
(January 12, 2022).
---------------------------------------------------------------------------

    \39\ Documents referenced by WDNR for the title I Construction 
Permit 15-DMM-128-R1 are provided in the docket.
---------------------------------------------------------------------------

    For Boiler B26 at the Ahlstrom-Munksj[ouml]--Rhinelander Mill, 
WDNR's four-factor analysis compiled information from the 2015 LADCO 
four-factor analysis and previous BART analysis on boilers with similar 
design and configuration that assessed cost-effectiveness of 
retrofitting controls onto industrial coal boilers at paper mills. For 
SO2, WDNR found the analysis indicated that operating 
existing DSI equipment at full capacity or installing wet or dry flue 
gas desulfurization (FGD) could be cost-effective for addressing 
visibility impairment. For NOX, WDNR found that use of OFA, 
RSCR, or OFA/RSCR could also be cost-effective for addressing 
visibility impairment. During Wisconsin's public review period of its 
regional haze SIP for the second implementation period, however, 
members of the public commented that many of the NOX and 
SO2 control technologies, the least expensive of which was 
estimated at $8,696,521 in capital costs and $2,952,350 in annual 
operating costs for SO2 controls, may not be affordable to 
facilities and could force facility closure.
    While WDNR found that additional SO2 and NOX 
controls for the Ahlstrom-Munksj[ouml]--Rhinelander Mill could be cost 
effective, WDNR did not find it necessary to determine a cost-
effectiveness threshold for point sources during the second 
implementation period. In considering the potential costs, WDNR 
evaluated potential reductions from the additional controls alongside 
those resulting from the new limits on SO2 emissions and 
heat input as well as trends in actual emissions.
    For SO2, DSI would provide a maximum reduction of 40 
percent at a cost effectiveness of $3,854/ton, while wet FGD and dry 
FGD would provide a maximum reduction of 95 percent and 93 percent at 
$5,463/ton and $3,804/ton, respectively. For NOX, OFA would 
offer 50 percent control efficiency at a cost effectiveness of $225/
ton, RSCR would provide 70 percent control efficiency at $2,389/ton, 
and OFA/RSCR would provide a control efficiency of 85 percent at 
$1,678/ton. Comparing actual emissions from 2016 to 2019 during the 
first implementation period when the SO2 limits changed from 
3.5 to 3.0 lbs/MMBtu with an allowable heat input of 300 MMBtu, WDNR 
documented a decrease in SO2 of 33 percent from 1,596 to 
1,067 tons/year with a corresponding decrease in NOX from 
1,145 to 811 tons/year. With the new lower limits for SO2 of 
2.38 lbs/MMBtu and heat input of 260 MMBtu that were incorporated into 
the SIP in 2021, WDNR expected 2028 emissions would be at or below the 
2019 actual emissions. After weighing the results of the four-factor 
analysis against the 2028 projected emissions with the new 2021 limits 
along with the five additional factors discussed below, WDNR concluded 
that the new 2021 limits provide reductions beyond those

[[Page 65506]]

included in the first implementation period and that requiring 
additional controls would be unnecessary to demonstrate reasonable 
progress in the second implementation period. Subsequently, on November 
10, 2023, WDNR provided additional information on recent significant 
operational changes that occurred at the Ahlstrom-Munksj[ouml]--
Rhinelander Mill. Specifically, the Ahlstrom-Munksj[ouml]--Rhinelander 
Mill stopped operating its coal-fired cyclone Boiler B26 in 2022 and 
decided to retire it. In its place, the facility intends to install a 
new natural gas fired Boiler B40 under title I construction permit 22-
MMC-035 that WDNR issued in May 2022.\40\ The facility's applications 
for the construction permit indicate that Boiler B26 will be retired, 
and WDNR stated that the shutdown of Boiler B26 will be reflected under 
the list of emissions units that have ceased operation in the title V 
operating permit renewal 74400810A-P30. WNDR indicated the title V 
operating permit renewal is scheduled to be issued in 2024. WDNR 
explained that when finalized, the retirement of Boiler B26 will be 
reflected in the permitting action and would serve to reduce emissions 
of NOX and SO2 from the Ahlstrom-Munksj[ouml]--
Rhinelander Mill impacted Class I areas.
---------------------------------------------------------------------------

    \40\ The title I construction permit 22-MMC-035 documents WDNR 
referenced are included in the docket.
---------------------------------------------------------------------------

    Furthermore, WDNR explained that if the Ahlstrom-Munksj[ouml]--
Rhinelander Mill were to resume the operation of Boiler B26 or replace 
it with a comparable coal-fired boiler after the title V operation 
permit 74400810A-P30 is renewed, either boiler would be considered a 
new source and the emissions would be limited by WDNR's construction 
permitting process requiring a PSD review and BACT.
Ahlstrom-Munksj[ouml]--Kaukauna Mill
    At the Ahlstrom-Munksj[ouml]--Kaukauna Mill, Boilers B09 and B11 
are equipped with a multi-cyclone and an ESP in series for control of 
particulate matter, and a DSI system for control of SO2. 
Boiler B11 shares the ESP and exhaust stack with Boiler B09, which was 
below WDNR's source selection threshold with a Q/d of 4. The combined 
SO2 emissions from each of the Boilers B09 and B11 were 
limited to 5.5 lbs/MMBtu, averaged over 30 days, in title V permit 
445031180-P22. Beginning in April of 2019, the mill has fired only 
natural gas in Boiler B09, which lowered the unit's Q/d below the FLM's 
threshold of 4 for further consideration.
    For Boiler B11 at the Ahlstrom-Munksj[ouml]--Kaukauna Mill, WDNR's 
four-factor analysis compiled information from the 2015 LADCO four-
factor analysis and applied site-specific information to the previous 
BART analysis from the Georgia Pacific--Broadway Mill. WDNR's analysis 
found that installing new controls could be cost-effective for 
addressing visibility impairment. For SO2, DSI would provide 
a maximum reduction of 40 percent at a cost effectiveness of $2,466/
ton, while wet FGD and dry FGD would provide a maximum reduction of 95 
percent and 93 percent at $3,807 and $1,968/ton, respectively. For 
NOX, OFA would offer 50 percent control efficiency at a cost 
effectiveness of $316/ton, RSCR would provide 70 percent control 
efficiency at $2,770/ton, and OFA/RSCR would provide a control 
efficiency of 85 percent at $2,130/ton. While WDNR found that 
additional SO2 and NOX controls for the Ahlstrom-
Munksj[ouml]--Kaukauna Mill could be cost effective, WDNR did not find 
it necessary to determine a cost-effectiveness threshold, similar to 
its decision for the Ahlstrom-Munksj[ouml]--Rhinelander Mill. In 
considering the potential costs, WDNR evaluated potential reductions 
from the additional controls alongside those resulting from anticipated 
new limits on SO2 emissions, which WDNR expected would 
require a commitment to lower SO2 emissions below 2016 base 
year levels. After weighing the results of the four-factor analysis 
against the potential for new lower limits for SO2, WDNR 
concluded that the anticipated SO2 limits would provide 
reductions beyond those included in the first implementation period and 
that requiring additional controls would be unnecessary to demonstrate 
reasonable progress in the second implementation period.
    In its initial SIP submission, WDNR planned to address a lower 
SO2 permit limit for Boiler B11 when EPA designated portions 
of Outagamie County, Wisconsin as a nonattainment area for the 2010 1-
hour SO2 NAAQS on December 21, 2020, but EPA withdrew the 
nonattainment designation when Wisconsin provided data showing 
attainment before the effective date of the designation. See 86 FR 
16055 (March 26, 2021), 86 FR 19576 (April 14, 2021).
    On November 10, 2023, and January 3, 2024, WDNR provided 
information on operational changes at Boiler B11. Specifically, Boiler 
B11 experienced a boiler tube failure that caused an explosion in 
August 2022, and is no longer in operation. The Ahlstrom-Munksj[ouml]--
Kaukauna Mill made the decision not to bring Boiler B11 back into 
operation and to retire the unit due to the damage.
    The Ahlstrom-Munksj[ouml]--Kaukauna Mill is replacing coal-fired 
Boiler B11 with a natural gas-fired package boiler. A title I 
construction permit 23-JAM-079 \41\ was issued on October 4, 2023, to 
construct a new natural gas-fired package boiler (Unit B84) with rated 
heat input capacity of 286 MMBtu/hour. Boiler B84 will be equipped with 
LNB and FGR to minimize NOX emissions. In addition to the 
installation of Boiler B84, WDNR issued a title I construction permit 
23-JAM-017 in 2022 to the Ahlstrom-Munksj[ouml]--Kaukauna Mill to 
replace a portion of the steam previously supplied by Boiler B11 by 
increasing the usage of two smaller natural gas-fired package boilers 
(B82 and B83).
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    \41\ The title I Construction Permit 23-JAM-079 for the new 
natural gas-fired Boiler B84 at the Ahlstrom-Munksj[ouml]--Kaukauna 
Mill and the Preliminary Determination referenced by WDNR are 
included in the docket for this rulemaking.
---------------------------------------------------------------------------

    WDNR's Analysis for Preliminary Determination for the Boiler B84 
construction permit 23-JAM-079, which was noticed for public comment on 
September 2, 2023, determined that the combined potential emissions 
from Boilers B82, B83, and B84 minus the emissions from Boiler B11 
results in a decrease of contaminants regulated under New Source Review 
(NSR). This determination was based on potential emissions from new 
Boiler B84 (0.74 tons per year (tpy) SO2, 45.1 tpy 
NOX) along with the increased use of B82 (0.257 tpy 
SO2 and 15.7 tpy NOX) and B83 (0.257 
SO2 and 15.7 NOX) minus the emissions from 
retired Boiler B11 based on 2018-2019 actual emissions (3,968 tpy 
SO2 and 965 tpy NOX).
    On January 2, 2024, WDNR issued the title V operation permit 
renewal 44503118A-P30 for the Ahlstrom-Munksj[ouml]--Kaukauna Mill, 
which lists coal-fired cyclone Boiler B11 under ``Emissions units that 
have ceased operation.'' \42\ The title I Construction Permit 23-JAM-
079 for the new natural gas-fired Boiler B84 sets forth the Ahlstrom-
Munksj[ouml]--Kaukauna Mill's reasons and intent to retire Boiler B11. 
Under Wisconsin Administrative Code NR 407.09(2)(d), operation permits 
must contain provisions consistent with any condition in a previously 
issued permit if the provisions are still applicable to the source. As 
such, when conditions in a previously issued construction permit

[[Page 65507]]

are not included in the operation permit, those conditions are no 
longer applicable. WDNR explained that this permitting action is 
federally enforceable and permanent and if Ahlstrom-Munksj[ouml]--
Kaukauna Mill seeks to resume operation of Boiler B11 or replace it 
with a comparable coal-fired boiler, either would be considered a new 
source and the emissions would be limited by WDNR's construction 
permitting process, requiring a PSD review and BACT. WDNR explained 
that this change reflected in the permitting action serves to reduce 
emissions of NOX and SO2 from the Ahlstrom-
Munksj[ouml]--Kaukauna Mill impacting Class I Areas.
---------------------------------------------------------------------------

    \42\ The title V Operation Permit 44503118A-P30 for the 
Ahlstrom-Munksj[ouml]--Kaukauna Mill referenced by WDNR is included 
in the docket for this rulemaking.
---------------------------------------------------------------------------

3. Wisconsin's Long-Term Strategy
    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). After 
considering information regarding existing effective controls, analyses 
under the four statutory factors in 40 CFR 51.308(f)(2)(i), and the 
five additional factors in 40 CFR 51.308(f)(2)(iv) in addition to other 
requirements in 40 CFR 51.308(f)(2)(ii) described below, WDNR 
determined the state's long-term strategy for the second implementation 
period is comprised of the following measures. These measures represent 
reductions beyond those planned in the first implementation period, 
changes in emissions since the first implementation period, as well as 
emission reductions due to ongoing air pollution control programs, 
source retirements, and replacements. All the following measures are 
either incorporated into the regulatory portion of Wisconsin's SIP at 
40 CFR 52.2570(c) or are otherwise federally enforceable and permanent 
except where noted.
     On-the-books retirements at Wisconsin coal-fired EGUs: 
These include retirements that go beyond those planned during the first 
implementation period. The retirements are reflected in revoked title V 
permits and title V operation permits as emissions units that have 
ceased operation: WPL--Edgewater Unit B24 (2018), WE Energies--Pleasant 
Prairie Units B20 and B21 (2018); Dairyland Power Coop Alma Site Units 
B23 and B24 (2014); Wisconsin Public Service Corp--JP Pulliam Plant 
Units B26 and B27 (2018); Dairyland Power Coop Genoa Station-Eop Unit 
B20 (2021); and E J Stoneman Station Units B21 and B22 (2015).
     On-the-books controls affecting Wisconsin mobile sources: 
These include state and Federal regulations for onroad and nonroad 
mobile sources, which continue to reduce emissions nationwide as fleets 
turn over to newer vehicles and engines. For onroad mobile sources, 
WDNR cited to Federal regulations for passenger vehicles, trucks, 
motorcycles, compression engines, ignition engines, air toxics, and 
light duty vehicle corporate average fuel economy (CAFE) standards. 
Among the controls for onroad mobile sources was the Wisconsin-
administered Federal inspection and maintenance (I/M) program, codified 
at Wisconsin Administrative Code NR 485 and Trans 131, that limits 
onroad VOC and NOX emissions for southeastern counties of 
the state and continues to provide incremental reductions as fleets 
turn over to new vehicles. For nonroad mobile sources, WDNR cited to 
Federal regulations limiting NOX emissions and fuel sulfur 
content for various aircraft, marine, locomotive, recreational, and 
hand-held engines that continue to lower emissions as equipment fleets 
turn over and older, higher-emitting equipment is removed from service.
     Permitted control requirements and shutdowns at non-EGU 
point sources: For non-EGU point sources below WDNR's Q/d source 
selection threshold listed in appendix 3 of Wisconsin's plan, permitted 
control requirements and shutdowns are not intended to be included in 
the regulatory portion of the SIP. For permitted control requirements, 
this includes an annual heat input limitation for the Ahlstrom-
Munksj[ouml]--NA Specialty Solutions LLC--DePere Boilers B23 and B24 
(2017) as well as a switch from coal to natural gas for Catalyst 
Paper--Biron Mill Boiler B23 (2017), Georgia-Pacific Green Bay Boilers 
B26 and B28 replacements (2019), Green Bay Packaging Inc Mill Division 
Boiler B26 replacement (2019), and Domtar A W LLC Nekoosa Boilers B20, 
B21, and B24 (2014). For shutdowns at non-EGU point sources, this 
includes Georgia-Pacific Green Bay Boilers B27, B29, B26, and B28 
(2015, 2018, 2019), Green Bay Packaging Inc. Mill Division Boiler B26 
(2019), Procter & Gamble Paper Products Co. B06 (2015), and Packaging 
Corporation of America--Tomahawk Boilers B24, B27, and B28 (2015). For 
shutdowns at non-EGU point sources above WDNR's Q/d source selection 
threshold, this includes the retirement of Boiler B11 at the Ahlstrom-
Munksj[ouml]--Kaukauna Mill with the issuance of the title V Operation 
Permit 44503118A-P30 on January 2, 2024. This provision of the long-
term strategy would also include the retirement of coal-fired cyclone 
Boiler B26 at the Ahlstrom-Munksj[ouml]--Rhinelander Mill when WDNR 
provides sufficient evidence that Boiler B26 has permanently ceased 
operation.
     SO2 NAAQS requirements for the Ahlstrom-
Munksj[ouml]--Kaukauna Mill, Ahlstrom-Munksj[ouml]--Rhinelander Mill, 
and other Wisconsin non-EGU point sources: Although WDNR initially 
listed the Ahlstrom-Munksj[ouml]--Kaukauna Mill Boiler B11 under this 
provision, the provision above for shutdowns at non-EGU point sources 
became applicable when it retired. For the Ahlstrom-Munksj[ouml]--
Rhinelander Mill Boiler B26, this includes limits on heat input of 260 
MMBtu/hr and SO2 of 2.38 lb/MMBtu (24-hour average), which 
are included in title I Construction Permit 15-DMM-128-R1 and are 
incorporated into Wisconsin's SIP at 40 CFR 52.2570(144)(i). For other 
Wisconsin non-EGUs, WNDR's plan at appendix 3 lists those that are 
subject to required SO2 modeling in title V permits to 
demonstrate compliance with the 2010 SO2 NAAQS pursuant to 
Wisconsin Administrative Code NR 404. However, they are below WDNR's Q/
d source selection threshold and are not intended to be made permanent 
by incorporation into the regulatory portion of the SIP. These include 
Wisconsin Rapids Paper Mill, Ahlstrom-Munksj[ouml]--Mosinee, Graymont 
LLC Superior, Domtar A W LLC--Nekoosa, Flambeau River Papers LLC, 
Appleton Coated LLC, and Ahlstrom-Munksj[ouml] NA Specialty Solutions 
LLC--DePere.
4. EPA's Evaluation of Wisconsin's Compliance With 40 CFR 
51.308(f)(2)(i)
    EPA is proposing to determine that WDNR's source selection was 
reasonable and consistent with the requirements of 40 CFR 
51.308(f)(2)(i). WDNR's source selection methodology targeted the 
sources with the highest potential to impair visibility at mandatory 
Class I areas. WDNR included a thorough description of its source 
selection methodology. Using a unit Q/d greater than 10, WDNR selected 
four units for further analysis, including three non-EGUs at the 
Ahlstrom-Munksj[ouml]--Kaukauna and Rhinelander Mills and one EGU at 
WPL--Edgewater. WDNR conducted four-factor analyses on two of the non-
EGUs for the Ahlstrom-Munksj[ouml]--Kaukauna and Rhinelander Mills. The 
sources WDNR selected for further analysis represented more than 38 
percent of the total SO2 emissions and 13 percent of the 
total NOx emissions for Wisconsin point sources with a Q/d greater than 
1 based on 2016 emissions. Of the sources with facility Q/d greater 
than 4 and less than 10,

[[Page 65508]]

Wisconsin provided adequate justification for its decision not to 
perform further analysis. For non-EGUs, all but two were below a unit 
Q/d of 4 based on 2016 emissions, and those two have since instituted 
enforceable measures for reductions: Catalyst Paper--Biron Boiler B23 
switched to natural gas in 2017, and Cardinal FG--Menomonie Boiler P01 
installed SCR in 2020. For EGUs, there are three with a unit Q/d 
between 4 and 10. Two EGUs are scheduled to shut down in 2025, at WPL--
Columbia, B21 and B22. The third EGU is located at JP Madgett where B25 
has LNB/SCR with a NOx limit of 0.14 lbs/MMBtu and DSI with an 
SO2 limit of 0.09 lbs/MMBtu. The SO2 limit is 
below the limit of 0.2 lbs/MMBtu specified in the MATS rule for coal-
fired EGUs.
    Wisconsin's plan shows that the existing measures will achieve 
SO2 and NOx emission reductions beyond those included in its 
first implementation period and LADCO's modeled 2028 projections. WDNR 
determined than no additional controls would be necessary for 
reasonable progress based on its source selection process, shutdowns, 
and consideration of existing effective controls that have achieved a 
reasonably consistent emission rate and will continue to be 
implemented.
    WDNR identified shutdowns, committed controls, and replacement or 
fuel switching for coal-fired boilers to natural gas-fired boilers for 
several units below WDNR's Q/d source selection threshold, including 
sources flagged by the FLMs, that were not relied upon in assessing 
visibility impacts included in LADCO's 2028 modeling but will 
contribute to lower emissions than those projected. In section 3.3.3 of 
its submittal, WDNR adjusted LADCO's 2028 projections lower for these 
EGUs and non-EGUs by 7,787 tpy NOx and 5,960 tpy SO2 by 
considering reductions at the following sources:
 Alliant Energy--Columbia shutdown of boilers B21 and B22 
(2025)
 WE Energies--Oak Creek Power Plant shutdown of Boilers B25, 
B26, B27, and B28 (2023-2024)
 Georgia-Pacific Green Bay Broadway Mill--retirement of coal 
Boiler B29 (2018) as well as replacement of coal Boilers B26 and B28 
with three natural gas boilers (2019-2020)
 Catalyst Paper--Biron Mill--coal Boiler B23 fuel switch to 
natural gas (2017)
 Cardinal FG--Menominee--installation of SCR (2020)
 Cardinal FG--Portage--installation of SCR (2019)
 Green Bay Packaging Inc. Mill--replacement of coal-fired 
Boiler B26 with two natural gas boilers (2019)
 Ahlstrom-Munksj[ouml]--De Pere Mill--10 percent annual heat 
input limitation for coal Boilers B23 and B24 (2017).

    The shutdowns, committed controls, replacements of coal-fired 
boilers with natural gas-fired boilers, and fuel switching from coal to 
natural gas at other boilers contribute to Wisconsin's emission 
reductions and the associated visibility improvements at the affected 
LADCO Class I Areas for the second implementation period. Except for 
Alliant Energy--Columbia, since these units were below WDNR's Q/d 
source selection threshold and not selected for a further analysis, 
WDNR did not rely on the reductions from these sources to make 
reasonable progress.
    The retirement of coal-fired Boiler B11 at the Ahlstrom-
Munksj[ouml]--Kaukauna Mill serves to minimize emissions from this 
source moving forward. Coal-fired Boiler B11 is being replaced by 
natural gas-fired boilers B82, B83, and B84. This replacement results 
in greater than a 92 percent decrease in NOX and greater 
than a 99 percent decrease in SO2 emissions, surpassing the 
reductions that would have been achieved with the addition of controls 
evaluated in the four-factor analysis that WDNR considered potentially 
cost effective. As a result, the retirement of Boiler B11 constitutes 
reasonable progress. EPA proposes to find that since B11 experienced a 
catastrophic failure, is no longer permitted to operate, has been 
replaced by natural gas units, the retirement is already federally 
enforceable and permanent, and it does not need to be included in the 
regulatory portion of the SIP.
    The pending retirement of coal-fired Boiler B26 at the Ahlstrom-
Munksj[ouml]--Rhinelander Mill will also provide federally enforceable 
and permanent emission reductions from another one of Wisconsin's 
largest sources. Ahlstrom-Munksj[ouml]--Rhinelander Mill plans to rely 
on the retirement of coal-fired Boiler B26 and replacement with a lower 
emitting natural-gas fired Boiler B40, reducing the potential to emit 
NOX by 13 percent and SO2 by 31 percent.
    While the Ahlstrom-Munksj[ouml]--Rhinelander Mill proceeds with 
retirement as the actual control measure in lieu of reliance on new 
limits or new control systems for Boiler B26, EPA finds that Wisconsin 
must provide sufficient evidence that Boiler B26 has permanently ceased 
operation and incorporate this measure into the long-term strategy to 
make reasonable progress. As such, EPA proposes to find that the 
retirement of Boiler B26 is necessary for reasonable progress and must 
be included in the SIP or made federally enforceable and permanent 
elsewhere.
    Without evidence that Boiler B26 at the Ahlstrom-Munksj[ouml]--
Rhinelander Mill has permanently ceased operation, EPA proposes to 
partially approve and partially disapprove the Wisconsin regional haze 
SIP for the second implementation period. In the event that WDNR does 
not provide sufficient evidence of the federally enforceable and 
permanent shutdown of Boiler B26 at the Ahlstrom Munksjo--Rhinelander 
Mill, EPA proposes to approve the elements of Wisconsin's regional haze 
SIP related to requirements contained in 40 CFR 51.308(f)(1), (f)(3) 
through (6), (g)(1) through (5), and (i)(2) through (4), and disapprove 
the elements of Wisconsin's SIP related to the requirements of 40 CFR 
51.308(f)(2) due to insufficient information regarding cessation of 
operations at Boiler B26. EPA proposes to find that Wisconsin has not 
satisfied the requirements of 40 CFR 51.308(f)(2) related to evaluating 
and determining the emission reduction measures that are necessary to 
make reasonable progress by applying the four statutory factors to 
sources in a control analysis, because Wisconsin's analysis determined 
that additional controls would be appropriate at Boiler 26 of the 
Ahlstrom-Munksj[ouml]--Rhinelander Mill if that boiler were to continue 
operating. At the time of this action, Boiler 26 is still permitted to 
operate.
    In the alternative, if WDNR provides sufficient evidence that the 
Ahlstrom-Munksj[ouml]--Rhinelander Mill has permanently ceased 
operation of Boiler B26 before final action of this rulemaking, EPA 
proposes to find that Wisconsin has satisfied the requirements of 40 
CFR 51.308(f)(2)(i) related to evaluating and determining the emission 
reduction measures that are necessary to make reasonable progress by 
applying the four statutory factors to sources in a control analysis. 
EPA proposes to find that Wisconsin's SIP submission, including 
sufficient evidence that Boiler 26 has ceased operation, indicates that 
WDNR reasonably applied the Q/d source selection process in relying on 
the closest Class I areas and the emissions of NOX, 
SO2, PM2.5, NH3 and VOC. EPA proposes 
to find that WDNR examined a reasonable set of sources, including 
sources flagged by FLMs. EPA proposes to find that WDNR adequately 
demonstrated that selecting additional sources below Wisconsin's 
selected threshold for four-factor analysis as

[[Page 65509]]

suggested by FLMs would not have resulted in additional emission 
reduction measures being determined to be necessary to make reasonable 
progress for the second implementation period based on information 
provided by WDNR that the sources are already well-controlled, 
currently retired, or retiring by 2025.
    EPA proposes to find that WDNR adequately explained its decision to 
focus on the two pollutants, SO2 and NOX, that 
currently drive visibility impairment within the LADCO region. In the 
event that Wisconsin provides evidence that Boiler 26 at Ahlstrom-
Munksj[ouml]--Rhinelander Mill has permanently ceased operation, EPA 
proposes to find that WDNR adequately supported its conclusions for its 
top-impacting sources in determining new controls would not be 
necessary for reasonable progress. EPA would base this proposed finding 
on the state's examination of the existing effective controls at its 
largest operating EGU Alliant Energy--Edgewater, the retirement at its 
non-EGU source Ahlstrom-Munksj[ouml]--Kaukauna Mill, which are both 
federally enforceable and permanent, as well as the pending retirement 
at the Rhinelander Mill. EPA proposes to find the state's approach 
reasonable because it demonstrated that the sources with the greatest 
modeled impacts on visibility, as well as other sources above Q/d of 4 
and below the state's Q/d threshold, either have shut down, reduced 
their emissions significantly, or are subject to stringent emission 
control measures.
5. Consultation With States
    The consultation requirements of 40 CFR 51.308(f)(2)(ii), provides 
that states must consult with other states that are reasonably 
anticipated to contribute to visibility impairment in a Class I area to 
develop coordinated emission management strategies containing the 
emission reductions measures that are necessary to make reasonable 
progress. Section 51.308(f)(2)(ii)(A) and (B) require states to 
consider the emission reduction measures identified by other states as 
necessary for reasonable progress and to include agreed upon measures 
in their SIPs, respectively. Section 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.
    WDNR consulted with other LADCO states to develop a coordinated 
emission management approach to its regional haze SIP and address 
Wisconsin's impact on nearby Class I areas. Wisconsin participated in 
the LADCO Regional Haze Technical Workgroup meetings beginning in 
January 2018. These meetings are on-going. WDNR, through LADCO, also 
participated in intra and inter-RPO informal discussions.
    No states have notified WDNR that they identified emissions from 
Wisconsin sources as contributing to visibility impairment at their 
Class I areas. There were no requests of Wisconsin from other states to 
undertake specific emissions reductions necessary to make reasonable 
progress for the second regional haze implementation period.
    WDNR has met the 40 CFR 51.308(f)(2)(ii)(A) and (B) requirements 
with its participation in the LADCO consultation process plus its 
individual consultation meetings with contributing states. There were 
no disagreements with another state, so 40 CFR 51.308(f)(2)(ii)(C) does 
not apply to Wisconsin. EPA proposes that Wisconsin has satisfied the 
consultation requirements of 40 CFR 51.308(f)(2)(ii).
    The requirements of 40 CFR 51.308(f)(2)(iii) provide that a state 
must document the technical basis for its decision making to determine 
the emission reductions measures that are necessary to make reasonable 
progress. WDNR has documented the technical basis, including the 
modeling, monitoring, cost, engineering, and emissions information that 
was relied on in determining the emission reduction measures that are 
necessary to make reasonable progress. As described in more detail 
above, WDNR documented the modeling done by LADCO to determine 
visibility projections and contributions to impairment at the Class I 
areas, including justification for the 2016 base year selection and the 
2028 emission projections based on ERTAC forecasts and state-reported 
changes. For monitoring, Wisconsin documented the statewide monitoring 
network, which is maintained by WDNR along with its Tribal partners, to 
measure various air pollutants, including those that contribute to 
visibility impairment at Class I areas, and to report data used to 
determine area attainment with the NAAQS. For emissions information, 
WDNR provided annual emissions by source category for 2005, 2011, 2016, 
2017, and 2019 plus emissions for sources selected for a four-factor 
analysis from 2005, 2016, and 2019 emissions, as well as 2028-projected 
statewide emissions by unit and source category. In addition, WDNR 
provided annual emissions data for Alliant Energy--Edgewater B25 for 
2016--2022. For costs and engineering, WDNR provided four-factor 
analyses complied by LADCO, which evaluated potential control scenarios 
and costs for coal-fired industrial boilers at pulp and paper mills as 
well as site-specific four-factor analyses for the Ahlstrom-
Munksj[ouml]--Kaukauna and Rhinelander Mills. Such documentation of the 
technical basis of the long-term strategy satisfies the requirements of 
40 CFR 51.308(f)(2)(iii).
    Section 51.308(f)(2)(iii) also requires that the emissions 
information considered to determine the measures that are necessary to 
make reasonable progress include information on emissions for the most 
recent year for which the state has submitted triennial emissions data 
to EPA (or a more recent year), with a 12-month exemption period for 
newly submitted data. As previously mentioned above, WDNR participated 
in the development of technical analyses, including emission inventory 
information, by LADCO and its member states, and is relying in part on 
those analyses to satisfy the emission inventory requirements. WDNR 
explained, in section 3.5.4 of its submission, that emissions for the 
2016 base year and the 2028 projected year used in LADCO modeling 
address elements of section 51.308(f)(6)(v) of the RHR, which requires 
that states provide recent and future year emissions inventories of 
pollutants anticipated to contribute to visibility impairment in any 
Class I areas. WDNR's SIP submission also included 2017 NEI emission 
data, as it corresponds to the year of the most recent triennial NEI, 
required under 40 CFR 51.308(f)(2)(iii) of the RHR. Based on 
Wisconsin's consideration and analysis of the 2017 emission data in its 
SIP submittal, EPA proposes to find that WDNR has satisfied the 
emissions information requirement in 40 CFR 51.308(f)(2)(iii).
6. Five Additional Factors
    In addition to the four statutory factors, states must also 
consider the five additional factors listed in 40 CFR 51.308(f)(2)(iv) 
in developing their long-term strategies.
    Pursuant to 40 CFR 51.308(f)(2)(iv)(A), WDNR noted that ongoing 
state and Federal emission control programs that have and will continue 
to contribute to Wisconsin's emission reductions through 2028 would 
impact emissions of visibility impairing pollutants from point, 
nonpoint, and mobile sources in the second implementation period. For 
point sources, this includes Federal transport rules for NOX 
and SO2, Wisconsin NOX Reasonable Available 
Control Technology (RACT) and Reasonable Available Control Measures 
(RACM), Boiler MACT, title V

[[Page 65510]]

permitting actions, and 2010 SO2 NAAQS requirements. For 
onroad mobile sources, Wisconsin cited to Federal regulations for 
passenger vehicles, trucks, motorcycles, compression engines, ignition 
engines, air toxics, and light duty vehicle CAFE standards. Among the 
controls for onroad mobile sources was the Wisconsin-administered 
Federal I/M program, codified at Wisconsin Administrative Code NR 485 
and Trans 131, that limits onroad VOC and NOX emissions for 
southeastern counties of the state and continues to provide incremental 
reductions as fleets turn over to new vehicles. For nonroad mobile 
sources, Wisconsin cited to Federal regulations for engines, including 
aircraft, locomotive, recreational vehicle, compression ignition, 
marine compression ignition, marine spark ignition, large spark 
ignition, and small spark ignition. WDNR included in their SIP 
comprehensive lists of control measures with their effective dates, 
pollutants addressed, and corresponding Wisconsin Administrative Code 
provisions.\43\
---------------------------------------------------------------------------

    \43\ See section 3.5.1 of the Wisconsin Regional Haze SIP for 
the Second Implementation Period 2018-2028 (July 30, 2021).
---------------------------------------------------------------------------

    As required by 40 CFR 51.308(f)(2)(iv)(B), Wisconsin's 
consideration of measures to mitigate the impacts of construction 
activities includes, in section 3.5.2 of its SIP submission, a list of 
measures that WDNR has implemented to mitigate the impacts from such 
activities. WDNR has implemented standards that reduce fugitive dust 
emissions from construction, including rules ensuring that permitting 
of new and modified sources through WDNR's NSR program is consistent 
with making reasonable progress toward the visibility goals of the 
second implementation period haze SIP.
    Pursuant to 40 CFR 51.308(f)(2)(iv), source retirements and 
replacement schedules are addressed in section 3.5.3 and appendix 3 of 
WDNR's SIP submission as well as the additional information WDNR 
provided on November 10, 2023, and January 3, 2024. Wisconsin point 
source EGU and non-EGU retirements and on-the-books controls as of 
September 2020 were considered in developing the 2028 emission 
projections for LADCO's modeling. However, retirements and replacements 
for several units listed in section 3.3.3 of Wisconsin's SIP submission 
along with the Ahlstrom-Munksj[ouml] Rhinelander and Kaukauna Mills 
were not listed, making the modeled 2028 projections conservative. 
These retirements and replacements contribute to Wisconsin's emission 
reductions and the associated visibility improvements at the affected 
LADCO Class I Areas for the second implementation period.
    In considering smoke management for prescribed burns as required in 
40 CFR 51.308(f)(2)(iv)(D), WDNR explained, in section 3.5.4 of its 
submission, that WDNR has worked with land managers in Wisconsin to 
prepare a plan to address controllable fire activities that can impact 
visibility locally. Appendix 6 contains the ``Wisconsin Smoke 
Management Plan: Best Management Practices for Prescribed Burns'' 
(April 2021).
    As required by 40 CFR 51.308(f)(2)(iv), WDNR considered the 
anticipated net effect on visibility improvements at the LADCO Class I 
Areas due to projected changes in emissions in section 3.5.5 of its 
plan. The visibility improvement expected during the second 
implementation period is calculated from LADCO's 2028 modeled emission 
projections (appendix 2 of WDNR's submission), which accounts for on-
the-books and on-the-way controls, including scheduled EGU shutdowns 
that were publicly announced as of September 2020. Current visibility 
conditions at the LADCO Class I Areas on the most impaired days are 
below their respective glidepaths (Figure 3 of WDNR's submission). 
LADCO's 2028 projections are similarly below the glidepath at the end 
of the second implementation period (Figure 3 of WDNR's submission). 
Also, WDNR's submission shows that current visibility conditions on the 
clearest days have resulted in continued improvement relative to 
baseline conditions (Figure 2 of WDNR's submission). Table 18 of WDNR's 
submission lists the expected improvement in visibility on the most 
impaired days over the course of the second implementation period at 
the LADCO Class I Areas. As noted in section 3.7 of WDNR's submission, 
an even larger improvement in visibility will be achieved by the end of 
the second implementation period than is presented in Table 18 of 
WDNR's submission due to the implementation of additional control 
measures in Wisconsin that are not included in LADCO's 2028 Modeled 
emissions.
    Beyond the additional controls noted in section 3.3.3 of 
Wisconsin's plan, WDNR also considered the net effect on visibility 
improvements at the LADCO Class I Areas with the hypothetical 
elimination of emissions from Boilers B26 and B11 at the Ahlstrom-
Munksj[ouml]--Rhinelander and Kaukauna Mills, two of Wisconsin's 
largest sources. Boilers B26 and B11 accounted for 6 percent and 23 
percent of Wisconsin's total 2028 modeled SO2 emissions, 
respectively. WDNR estimated that eliminating the emissions from 
boilers B26 and B11 that contribute to particulate sulfate and nitrate 
would yield a cumulative visibility improvement of 0.65Mm-1 
(~0.14 dv), accounting for approximately 9 percent of Wisconsin's total 
contribution to visibility impairment in the LADCO Class I Areas.\44\
---------------------------------------------------------------------------

    \44\ See appendix 2, Table A2-3 of the Wisconsin Regional Haze 
Plan for the Second Implementation Period 2018-2028 (July 30, 2021).
---------------------------------------------------------------------------

    WDNR concludes that, when weighing the four-factor analyses and the 
five additional required factors along with the retirement of Boiler 
B11 at Ahlstrom-Munksj[ouml]--Kaukauna and the planned retirement of 
Boiler B26 Ahlstrom-Munksj[ouml]--Rhinelander Mill both in 2024, it is 
not necessary to require any additional controls at the these 
facilities to meet second implementation period regional haze SIP 
requirements.\45\ EPA proposes to find that Wisconsin reasonably 
considered and satisfied the requirements for each of the five 
additional factors in 40 CFR 51.308(f)(2)(iv) in developing its long-
term strategy, with the exception of the control measures for Boiler 
B26 at the Ahlstrom-Munksj[ouml]--Rhinelander Mill unless WDNR meets 
the condition specified above to provide evidence of the permanent 
shutdown of Boiler B26 before final action in this rulemaking.
---------------------------------------------------------------------------

    \45\ See sections 3.2, 3.3, and 3.5 of the Wisconsin Regional 
Haze Plan for the Second Implementation Period 2018-2028 (July 30, 
2021).
---------------------------------------------------------------------------

F. Reasonable Progress Goals

    The provision 40 CFR 51.308(f)(3) contains the requirements 
pertaining to RPGs for each Class I area. Section 51.308(f)(3)(i) 
requires a state in which a mandatory 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 40 CFR 
51.308(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

[[Page 65511]]

51.308(f)(3)(ii) applies in circumstances in which a Class I area's RPG 
for the most impaired days represents a slower rate of visibility 
improvement than the URP calculated under 40 CFR 51.308(f)(1)(vi). 
Under 40 CFR 51.308(f)(3)(ii)(A), if the state in which a mandatory 
Class I area is located establishes an RPG for the most impaired days 
that provides for a slower rate of visibility improvement than the URP, 
the state must demonstrate that there are no additional emission 
reduction measures for anthropogenic sources or groups of sources in 
the state that would be reasonable to include in its long-term 
strategy. 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. Because Wisconsin has no mandatory 
Class I areas within its borders to which the requirements of the 
visibility protection program apply in 40 CFR part 81, subpart D, 
Wisconsin is subject only to 40 CFR 51.308(f)(3)(ii)(B), but not 40 CFR 
51.308(f)(3)(i) or (f)(3)(ii)(A).
    Under 40 CFR 51.308(f)(3)(ii)(B), a state that 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 under 40 CFR 51.308(f)(3)(ii)(B) must 
demonstrate that there are no additional emission reduction measures 
that would be reasonable to include in its long-term strategy. WDNR's 
SIP submission included glidepath checks for LADCO Class I Areas, which 
show that the RPG for the 20 percent most impaired days for the 
affected LADCO Class I Areas are not above the URP glidepath, and that 
the RPG for the 20 percent clearest days shows no degradation. In 
addition, LADCO's visibility projections at the LADCO Class I Areas 
show that the visibility projections for 2028 for the most impaired 
days are below the respective points for 2028 on the URPs.\46\ 
Therefore, we propose it is reasonable that the demonstration 
requirement under 40 CFR 51.308(f)(3)(ii)(B) as it pertains to these 
areas will not be triggered.
---------------------------------------------------------------------------

    \46\ See section 3.2.2, 3.7, and appendix 2 of the Wisconsin 
Regional Haze Plan for the Second Implementation Period 2018-2028 
(July 30, 2021).
---------------------------------------------------------------------------

    EPA proposes to determine that WDNR has satisfied the applicable 
requirements of 40 CFR 51.308(f)(3) relating to RPGs.

G. Monitoring Strategy and Other Implementation Plan Requirements

    40 CFR 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 section 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.
    Section 51.308(f)(6)(i) requires SIPs to provide for the 
establishment of any additional monitoring sites or equipment needed to 
assess whether RPGs to address regional haze for all mandatory Class I 
Federal areas within the state are being achieved. 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. As noted above, Wisconsin has no mandatory 
Federal Class I areas identified in 40 CFR part 81, subpart D, located 
within the state to which the requirements of the visibility protection 
program apply. Therefore, 40 CFR 51.308(f)(6)(i) and (ii) do not apply.
    Section 51.308(f)(6)(iii) requires states with no Class I areas to 
include 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 Class I areas in other 
states. States with Class I areas must establish a monitoring program 
and report data to EPA that is representative of visibility at the 
Class I Federal areas. The IMPROVE network meets this requirement. WDNR 
stated that, as a participant in LADCO, it reviewed information about 
the chemical composition of baseline monitoring data at LADCO Class I 
Areas to understand the sources of haze causing pollutants. WDNR does 
not operate any monitoring sites under the Federal IMPROVE program and, 
therefore, does not require approval of its monitoring network under 
the RHR. WDNR commits to continuing support of ongoing visibility 
monitoring in Class I Federal areas, agrees that the IMPROVE network is 
an appropriate monitoring network to track regional haze progress, and 
commits to working with neighboring states and FLMs to meet the goals 
of the IMPROVE program. WDNR also commits to using monitoring data and 
procedures consistent with EPA's guidance to review progress and trends 
in visibility at Class I Federal areas that may be affected by 
emissions from Wisconsin, both for comprehensive periodic revisions of 
this implementation plan and for periodic reports describing progress 
towards the RPGs for those areas.\47\
---------------------------------------------------------------------------

    \47\ See section 3.9 of the Wisconsin Regional Haze SIP for the 
Second Implementation Period 2018-2028 (July 30, 2021).
---------------------------------------------------------------------------

    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. As noted above, 
Wisconsin does not have any mandatory Class I Federal areas located 
within its borders to which the requirements of the visibility 
protection program apply in 40 CFR part 81, subpart D, and, therefore, 
40 CFR 51.308(f)(6)(iv) does not apply.
    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. Wisconsin provides 
for emissions inventories and estimates for future projected emissions 
by participating in the LADCO RPO and complying with EPA's AERR. In 40 
CFR part 51, subpart A, the AERR requires states to submit updated 
emissions inventories for criteria pollutants to EPA's Emissions 
Inventory System every three years. The emission inventory data is used 
to develop the NEI, which provides for, among other things, a triennial 
state-wide inventory of pollutants that are reasonably anticipated to 
cause or contribute to visibility impairment. Section 3.3.2 of 
Wisconsin's submission includes a table of NEI data. The source 
categories of the emissions inventories included are: (1) point 
sources, (2) nonpoint sources, (3) nonroad mobile sources, and (4) 
onroad mobile sources. The point source category is further divided 
into EGU point sources and non-EGU point sources. Wisconsin included 
NEI emissions inventories for 2017 for the following pollutants: 
SO2, NOX, PM2.5, VOCs, and 
NH3. Wisconsin also provided a summary of SO2, 
NOX, PM2.5, VOCs, and NH3 emissions 
for the same source categories sources for 2016 that LADCO used in 
developing the 2016 base year emissions inventory to

[[Page 65512]]

project emissions to year 2028 as well a summary of 2005 and 2019 
SO2 and NOX emissions for EGU and non-EGU point 
sources.\48\
---------------------------------------------------------------------------

    \48\ See section 3.3.3 of the Wisconsin Regional Haze SIP for 
the Second Implementation Period 2018-2028 (July 30, 2021).
---------------------------------------------------------------------------

    Section 51.308(f)(6)(v) also requires states to include estimates 
of future projected emissions and include a commitment to update the 
inventory periodically. For future projected emissions, Wisconsin 
relied on the LADCO modeling and analysis, which estimated 2028 
projected emissions of SO2 and NOX for specific 
facilities in the LADCO states to provide an assessment of expected 
future year air quality based on 2016 emissions and ERTAC forecasts. 
WDNR also adjusted the 2028 projections to account for additional 
emission reductions from retirements and committed controls for several 
units that were not included in LADCO's modeling. WDNR commits to 
periodically updating Wisconsin's emissions inventories for pollutants 
anticipated to cause or contribute to visibility impairment in Class I 
areas to support future regional haze progress reports and SIP 
revisions.
    No further elements are necessary for Wisconsin to assess and 
report on visibility pursuant to 40 CFR 51.308(f)(6)(vi).
    EPA proposes to find that Wisconsin has met the requirements of 40 
CFR 51.308(f)(6) as described above, including through its continued 
participation in LADCO, its statewide emissions inventory, and its 
emissions reporting to EPA.

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. Section 
51.308(g)(1) and (2) apply to all states and require a description of 
the status of implementation of all measures included in a state's 
first implementation period regional haze plan and a summary of the 
emission reductions achieved through implementation of those measures. 
Section 51.308(g)(3) applies only to states with Class I areas within 
their borders and requires such states to assess current visibility 
conditions, changes in visibility relative to baseline (2000-2004) 
visibility conditions, and changes in visibility conditions relative to 
the period addressed in the first implementation period progress 
report. Section 51.308(g)(4) applies to all states and requires an 
analysis tracking changes in emissions of pollutants contributing to 
visibility impairment from all sources and sectors since the period 
addressed by the first implementation period progress report. This 
provision further specifies the year or years through which the 
analysis must extend depending on the type of source and the platform 
through which its emission information is reported. Finally, 40 CFR 
51.308(g)(5), which also applies to all states, requires an assessment 
of any significant changes in anthropogenic emissions within or outside 
the state 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.
    Wisconsin's progress report for the first implementation period, 
submitted on March 17, 2017, documented emissions of SO2 and 
NOX from 2005-2015. EPA published a final rule approving the 
Wisconsin regional haze progress report as a revision to the Wisconsin 
SIP on June 15, 2018 (83 FR 27910). For the second implementation 
period SIP submittal, the 2019 Guidance recommends the progress report 
cover the first full year that was not incorporated into the previous 
progress report through a year that is as close as possible to the 
submission date of the 2021 SIP.
    To address the progress report elements of 40 CFR 51.308(g)(1) and 
(2), sections 3.3.2 and 3.3.3 of Wisconsin's SIP recounts the measures 
and emissions reductions achieved from 2016, the first year following 
its previous progress report, through 2017, the most recent NEI year 
available at the time for sector level emissions. During the first 
implementation period, measures that WDNR relied upon in developing its 
long-term strategy focused on reducing NOX and 
SO2 emissions. WDNR describes these measures in section 
3.5.1 of Wisconsin's submittal, including RACT, RACM, MACT, 2010 
SO2 NAAQS requirements, and the Cross-State Air Pollution 
Rule to satisfy certain BART requirements for EGUs. The status of each 
of these measures is ongoing, and WDNR summarizes the emissions 
reductions achieved. Table 8 of the progress report documents emissions 
changes from 2016 to 2017 for the point-EGU, point-non-EGU, area, 
onroad, and nonroad sectors, showing overall emission reductions in 
NOX and SO2 despite increases in point-EGU and 
nonroad sectors. For point-EGUs and non-EGUs, table 10 of WDNR's 
submission further demonstrates the emission reductions in 
NOX and SO2 from 2005 to 2016 to 2019. EPA 
proposes to find that WDNR has met the requirements of 40 CFR 
51.308(g)(1) and (2) because its SIP submission describes the measures 
included in the long-term strategy from the first implementation 
period, as well as the status of their implementation and the emission 
reductions achieved through such implementation.
    Section 51.308(g)(3) requires states to assess RPGs, including 
current visibility conditions and changes, for any Class I areas within 
the state. As described above, Wisconsin has no mandatory Class I 
Federal areas within its borders that are among the 156 mandatory Class 
I Federal areas where EPA deemed visibility to be an important value. 
Therefore, 40 CFR 51.308(g)(3) does not apply.
    Pursuant to 40 CFR 51.308(g)(4), in section 3.3.2 and 3.3.3 of 
their submission, WDNR provided an analysis tracking the change in 
emissions of NOX, SO2, PM2.5, 
NH3, and VOC from all sources and activities, including from 
point, nonpoint, nonroad mobile, and onroad mobile sources from 2016 
through 2017, the most recent NEI year available at the time for sector 
level emissions. As discussed above, Table 8 shows overall emission 
reductions in NOX and SO2 despite increases in 
point-EGU and nonroad sectors. While overall emissions showed increases 
in PM2.5, NH3, and VOC due primarily to point-EGU 
and nonroad sectors, WDNR notes that these pollutants contribute less 
to visibility impairment than emissions of NOX and 
SO2 and that the increases are outweighed by emission 
reductions in NOX and SO2. In further analysis 
under table 10, WDNR summarized emissions from the EGU and non-EGU 
sectors for 2005, 2016, and 2019, demonstrating reductions of 62 
percent in NOX and 86 percent in SO2 from 2005 to 
2016 and additional reductions of 18 percent in NOX and 41 
percent in SO2 from 2016 to 2019. WDNR also compared 2018 
projected emissions from the first implementation period to the 2028 
modeled emissions for the second implementation period that had been 
adjusted for shutdowns and committed controls not included in the LADCO 
modeling, showing reductions of 58 percent in NOX and 85 
percent in SO2.

[[Page 65513]]

EPA is proposing to find that Wisconsin has satisfied the requirements 
of 40 CFR 51.308(g)(4) by tracking the change in emissions of 
NOX, SO2, PM2.5, VOCs, and 
NH3 identified by type of source since the first progress 
report.
    To address 40 CFR 51.308(g)(5), WDNR assessed significant changes 
in anthropogenic emissions since the first implementation period, 
whether they were anticipated, and their impact on progress in 
improving visibility. Tables 8 and 10 of Wisconsin's plan summarize 
actual and projected emission reductions from 2016 to 2017, 2019, and 
2028. Additional information summarizing process level emissions and 
visibility improvements can be found in appendix 2 and appendix 3 of 
Wisconsin's submittal. The 2028 projected emissions modeled by LADCO 
included shutdowns and other on-the books controls for EGUs as of 
September 2020, while the non-EGU projections were primarily carried 
forward from the 2016 base year emissions. In addition, section 3.3. 
and appendix 3 of Wisconsin's submittal, WDNR lists emission reductions 
from unit shutdowns, fuel switches, and controls measures in Wisconsin 
that were not included in LADCO's 2028 modeled emissions. As such, WDNR 
developed 2028 adjusted emission projections. However, at the time, 
WDNR did not anticipate the retirement of Boilers B26 and B11 at the 
Ahlstrom-Munksj[ouml]--Rhinelander and Kaukauna Mills and the resulting 
greater reductions in SO2 and NOX as described in 
the November 10, 2023, and January 3, 2024, additional information. The 
reductions identified in LADCO's projections and WDNR's adjusted 
projections have led to improvements in visibility at the LADCO Class I 
Areas as described in section 3.5.5 of Wisconsin's submittal. Further 
improvements in visibility are anticipated with the emission reductions 
to be realized by the retirement of Boilers B26 and B11. The emissions 
trend data in Wisconsin's SIP submission and the subsequent clarifying 
information support an assessment that anthropogenic haze-causing 
pollutant emissions in Wisconsin have decreased during the reporting 
period and that changes in emissions have not limited or impeded 
progress in reducing pollutant emissions and improving visibility. EPA 
is proposing to find that Wisconsin has met the requirements of 40 CFR 
51.308(g)(5).

I. Requirements for State and Federal Land Manager Coordination

    CAA section 169A(d) 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. Section 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 February 22, 2021, WDNR 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 consultation meeting between the 
FLMs and representatives of WDNR was held on March 23, 2021. NPS sent a 
comment letter on July 11, 2021. To address 40 CFR 51.308(i)(3), 
Wisconsin's submittal summarized FLM comments and included WDNR's 
responses in appendix 7. In addition, WDNR summarized additional 
written comments from the National Park Service during the public 
comment period and provided responses in appendix 8. EPA proposes to 
find that WDNR 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.\49\
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    \49\ See section 3.8 of Wisconsin's July 30, 2021 Regional Haze 
SIP submission.
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    The public notice for WDNR's second implementation period regional 
haze SIP was scheduled following the FLM comment period to meet the 
minimum 60-day FLM consultation period required under 40 CFR 
51.308(i)(2). The public comment period was from April 28, 2021, to 
June 2, 2021. A virtual public hearing was held on June 1, 2021, at 
3:00 p.m. CDT online via Zoom and open conference call. No verbal 
comments were received at the public hearing. As noted above, appendix 
8 of Wisconsin's plan contains WDNR's responses to the written comments 
received during the public comment period from EPA, NPS, and the 
Ahlstrom-Munksj[ouml]--Rhinelander Mill. WDNR considered input from 
FLMs and the public when finalizing this SIP revision.
    Wisconsin's SIP submission includes a commitment to revise and 
submit a regional haze SIP by July 31, 2028, and every ten years 
thereafter. The state's commitment includes submitting periodic 
progress reports in accordance with 40 CFR 51.308(f) and a commitment 
to evaluate progress towards the reasonable progress goal for each 
mandatory Class I Federal area located outside the state that may be 
affected by emissions from within the state in accordance with 40 CFR 
51.308(g).

V. Proposed Action

    EPA is proposing to partially approve and partially disapprove 
Wisconsin's July 30, 2021, SIP submission. In the alternative, in the 
event that WDNR provides sufficient evidence to EPA, before final 
action in this rulemaking, that coal-fired cyclone Boiler B26 at the 
Ahlstrom-Munksj[ouml]--Rhinelander Mill has permanently ceased 
operating, EPA proposes to approve Wisconsin's SIP submission, 
including the information regarding the permanent cessation of 
operations at Boiler 26, as satisfying the regional haze requirements 
for the second implementation period contained in 40 CFR 51.308(f).

VI. 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

[[Page 65514]]

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, the SIP 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 environmental justice (EJ) as ``the fair treatment and 
meaningful involvement of all people regardless of race, color, 
national origin, or income with respect to the development, 
implementation, and enforcement of environmental laws, regulations, and 
policies.'' EPA further defines the term fair treatment to mean that 
``no group of people should bear a disproportionate burden of 
environmental harms and risks, including those resulting from the 
negative environmental consequences of industrial, governmental, and 
commercial operations or programs and policies.''
    WDNR did not evaluate EJ considerations as part of its SIP 
submittal; the CAA and applicable implementing regulations neither 
prohibit nor require such an evaluation. EPA did not perform an EJ 
analysis and did not consider EJ in this action. 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. 
Consideration of EJ is not required as part of this action, and there 
is no information in the record inconsistent with the stated goal of 
E.O. 12898 of achieving 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.

    Dated: July 31, 2024.
Debra Shore,
Regional Administrator, Region 5.
[FR Doc. 2024-17279 Filed 8-8-24; 8:45 am]
BILLING CODE 6560-50-P