[Federal Register Volume 87, Number 233 (Tuesday, December 6, 2022)]
[Proposed Rules]
[Pages 74577-74588]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-26504]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R08-OAR-2021-0003; FRL-10454-01-R8]


Approval and Promulgation of Implementation Plans; Montana; Libby 
1997 Annual PM2.5 Limited Maintenance Plan and Redesignation Request

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA or the Agency) is 
proposing to take three separate but related actions. First, EPA is 
proposing to determine that the Libby fine particulate matter 
(PM2.5) nonattainment area (Libby Area) is attaining the 
1997 annual PM2.5 national ambient air quality standards 
(NAAQS or standard) based on 2014-2021 data. The Agency is also 
proposing to approve Montana's plan for maintaining the 1997 annual 
PM2.5 NAAQS (limited maintenance plan) and to redesignate 
the Libby Area to attainment for the 1997 annual PM2.5 
NAAQS, submitted by the State of Montana on June 24, 2020.

DATES: Written comments must be received on or before January 5, 2023.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2021-0003, to the Federal Rulemaking Portal at https://www.regulations.gov. Follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
www.regulations.gov. EPA may publish any comment received to its public 
docket. Do not submit electronically any information you consider to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Multimedia submissions (audio, 
video, etc.) must be accompanied by a written comment. The written 
comment is considered the official comment and should include 
discussion of all points you wish to make. EPA will generally not 
consider comments or comment contents located outside of the primary 
submission (i.e., on the web, cloud, or other file sharing system). For 
additional submission methods, the full EPA public comment policy, 
information about CBI or multimedia submissions, and general guidance 
on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
    Docket: All documents in the docket are listed in the 
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available electronically in 
www.regulations.gov. To reduce the risk of COVID-19 transmission, for 
this action we do not plan to offer hard copy review of the docket. 
Please email or call the person listed in the FOR FURTHER INFORMATION 
CONTACT section if you need to make alternative arrangements for access 
to the docket.

FOR FURTHER INFORMATION CONTACT: Amrita Singh, Air and Radiation 
Division, U.S. Environmental Protection Agency (EPA), Region 8, Mail 
Code ARD-QP, 1595 Wynkoop Street, Denver, Colorado 80202-1129, 
telephone number: (303) 312-6103, email address: [email protected].

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

Table of Contents

I. What are the actions EPA is proposing to take?

[[Page 74578]]

II. What is the background for EPA's proposed actions?
    A. The PM2.5 NAAQS
    B. Designation of PM2.5 NAAQS Nonattainment Areas
    C. PM2.5 NAAQS Nonattainment Area Planning 
Requirements
    D. Limited Maintenance Plans
III. Why is EPA proposing these actions?
IV. What is EPA's analysis of the request?
    A. Has the State met all applicable requirements under section 
110 and part D of the Clean Air Act (CAA) and have those 
requirements been fully approved? (CAA sections 107(d)(3)(E)(ii) and 
(v))
    B. Has the State demonstrated that air quality improvement is 
due to permanent and enforceable reductions?
    C. Does the area have a fully approved maintenance plan pursuant 
to section 175A of the CAA?
    D. Transportation and General Conformity
V. What are the effects of EPA's proposed actions?
VI. Proposed Actions
VII. Statutory and Executive Order Reviews

I. What are the actions EPA is proposing to take?

    EPA is proposing to take the following separate but related 
actions: (1) to determine that the Libby Area is attaining the 1997 
annual PM2.5 NAAQS based on 2014-2021 data; (2) to approve 
Montana's plan for maintaining the 1997 annual PM2.5 NAAQS 
(limited maintenance plan); and (3) to redesignate the Libby Area to 
attainment for the 1997 annual PM2.5 NAAQS.
    Libby, Montana is a small rural community located in Lincoln County 
in the northwestern part of the State. Libby sits in the narrow, 
triangular Kootenai valley at an elevation of 2,100 feet. The Libby 
Area is dominated by three major mountain ranges that limit the air-
shed: (1) the Rocky Mountain and Flathead Ranges on the eastern 
boundary; (2) the Purcell Range, which roughly bisects the area from 
north to south; and (3) the Selkirk and Cabinet Ranges on the western 
boundary. Most of the area surrounding Libby, Montana is national 
forest land managed by the U.S. Forest Service.
    These proposed actions are summarized and described in greater 
detail throughout this proposed rulemaking. EPA's 1997 annual 
PM2.5 nonattainment designation for the Libby Area triggered 
an obligation for Montana to develop a nonattainment state 
implementation plan (SIP) revision addressing certain Clean Air Act 
(CAA) requirements under title I, part D, subpart 1 (hereinafter 
``Subpart 1'') and title I, part D, subpart 4 (hereinafter ``Subpart 
4''). Subpart 1 contains the general requirements for nonattainment 
areas for criteria pollutants, including requirements to develop a SIP 
that provides for the implementation of reasonably available control 
measures (RACM) under section 172(c)(1), reasonable further progress 
(RFP), includes base-year and attainment-year emissions inventories, 
and for the implementation of contingency measures. As discussed in 
greater detail later in this document, Subpart 4 contains specific 
planning and scheduling requirements for coarse particulate matter 
(PM10) nonattainment areas, including requirements for new 
source review (NSR), RACM (under CAA section 189(a)(1)(C)), and RFP. 
EPA's longstanding general guidance interpreting the 1990 CAA 
Amendments, known as the General Preamble, EPA discussed the 
relationship of Subpart 1 and Subpart 4 SIP requirements and pointed 
out that Subpart 1 requirements were to an extent ``subsumed by, or 
integrally related to, the more specific PM-10 requirements.'' See 57 
FR 13538 (April 16, 1992). In addition, under the United States Court 
of Appeals for the District of Columbia Circuit's (D.C. Circuit's) 
January 4, 2013, decision in Natural Resources Defense Council (NRDC) 
v. EPA, 706 F.3d 428 (D.C. Cir. 2013), Subpart 4 requirements apply to 
PM2.5 nonattainment areas.\1\
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    \1\ In explaining its decision, the Court reasoned that the 
plain meaning of the CAA requires implementation of the 1997 
PM2.5 NAAQS under Subpart 4 because PM2.5 
particles fall within the statutory definition of PM10 
and are thus subject to the same statutory requirements. EPA 
finalized its interpretation of Subpart 4 requirements as applied to 
the PM2.5 NAAQS in its final rule entitled ``Fine 
Particulate Matter National Ambient Air Quality Standards: State 
Implementation Plan Requirements; Final Rule'' (81 FR 58010, August 
24, 2016).
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    On June 2, 2014 (79 FR 31566), EPA published a rule entitled 
``Identification of Nonattainment Classification and Deadlines for 
Submission of State Implementation Plan (SIP) Provisions for the 1997 
Fine Particle (PM2.5) National Ambient Air Quality Standard 
(NAAQS) and 2006 PM2.5 NAAQS'' (``Classification and 
Deadlines Rule''). In that rule, the Agency responded to the D.C. 
Circuit's January 2013 decision by identifying all PM2.5 
nonattainment areas for the 1997 and 2006 PM2.5 NAAQS as 
``Moderate'' nonattainment areas under Subpart 4, and by establishing a 
new SIP submission date of December 31, 2014, for Moderate area 
attainment plans and for any additional attainment-related or 
nonattainment new source review plans necessary for areas to comply 
with the requirements applicable under Subpart 4. Id. at 31567-70.
    EPA is proposing to determine that the Libby Area is attaining the 
1997 annual PM2.5 NAAQS based on recent air quality data. 
EPA is also proposing to approve Montana's limited maintenance plan 
(LMP) for the Libby Area as meeting the requirements of section 175A of 
the CAA.
    EPA also proposes to determine that the Libby Area has met the 
requirements for redesignation under section 107(d)(3)(E) of the CAA. 
This proposed rulemaking is in response to Montana's June 24, 2020 
redesignation request and associated SIP submission that address the 
requirements described in section 107(d)(3)(E) of the CAA for the 
redesignation of the Libby Area from nonattainment to attainment for 
the 1997 annual PM2.5 NAAQS.\2\
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    \2\ See Libby Area SIP submission, available in the docket for 
this proposed rulemaking.
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II. What is the background for EPA's proposed actions?

A. The PM2.5 NAAQS

    Particulate matter includes particles with diameters that are 
generally 2.5 microns or smaller (PM2.5) and particles with 
diameters that are generally 10 microns or smaller (PM10). 
PM2.5 contributes to effects that are harmful to human 
health and the environment, including premature mortality, aggravation 
of respiratory and cardiovascular disease, decreased lung function, 
visibility impairment, and damage to vegetation and ecosystems. 
Individuals particularly sensitive to PM2.5 exposure include 
older adults, people with heart and lung disease, and children. See 78 
FR 3086 at 3088 (January 15, 2013). PM2.5 can be emitted 
directly into the atmosphere as a solid or liquid particle (``primary 
PM2.5'' or ``direct PM2.5'') or can be formed in 
the atmosphere (``secondary PM2.5'') as a result of various 
chemical reactions among precursor pollutants such as nitrogen oxides 
(NOX), sulfur oxides (SOX), volatile organic 
compounds (VOCs), and ammonia (NH3).\3\
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    \3\ EPA, Air Quality Criteria for Particulate Matter, No. EPA/
600/P-99/002aF and EPA/600/P-99/002bF, October 2004.
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    Under section 109 of the CAA, EPA has established national ambient 
air quality standards for certain pervasive air pollutants (referred to 
as ``criteria pollutants'') and conducts periodic reviews of the NAAQS 
to determine whether they should be revised or whether new NAAQS should 
be established. EPA sets the NAAQS for criteria pollutants at levels 
required to protect public health and welfare.\4\

[[Page 74579]]

PM2.5 is one of the ambient pollutants for which EPA has 
established health-based standards.
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    \4\ For a given air pollutant, ``primary'' national ambient air 
quality standards are those determined by EPA as requisite to 
protect the public health. ``Secondary'' standards are those 
determined by EPA as requisite to protect the public welfare from 
any known or anticipated adverse effects associated with the 
presence of such air pollutant in the ambient air. CAA section 
109(b).
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    On July 18, 1997 (62 FR 38652), EPA revised the NAAQS for 
particulate matter to add new standards for PM2.5. The 
Agency established primary and secondary annual and 24-hour standards 
for PM2.5. The annual standard was set at 15.0 micrograms 
per meter cubed ([micro]g/m\3\) based on a 3-year average of annual 
mean PM2.5 concentrations, and the 24-hour (daily) standard 
was set at 65 [micro]g/m\3\ based on the 3-year average of the annual 
98th percentile values of 24-hour PM2.5 concentrations at 
each population-oriented monitor within an area.\5\
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    \5\ The primary and secondary standards were set at the same 
level for both the 24-hour and the annual PM2.5 
standards.
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    On October 17, 2006 (71 FR 61144), EPA retained the annual average 
NAAQS at 15.0 [micro]g/m\3\ but revised the level of the 24-hour 
PM2.5 NAAQS to 35 [micro]g/m\3\ based on a 3-year average of 
the annual 98th percentile values of 24-hour concentrations.\6\
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    \6\ Under EPA regulations at 40 CFR part 50, the primary and 
secondary 2006 24-hour PM2.5 NAAQS are attained when the 
annual arithmetic mean concentration, as determined in accordance 
with 40 CFR part 50, appendix N, is less than or equal to 35 
[micro]g/m\3\ at all relevant monitoring sites in the subject area, 
averaged over a 3-year period.
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    On December 14, 2012, EPA promulgated the 2012 PM2.5 
NAAQS, including a revision of the annual standard to 12.0 [micro]g/
m\3\ based on a 3-year average of annual mean PM2.5 
concentrations. The Agency maintained the 24-hour standard of 35 
[micro]g/m\3\ based on a 3-year average of the 98th percentile of 24-
hour concentrations. See 78 FR 3086 (January 15, 2013).

B. Designation of PM2.5 NAAQS Nonattainment Areas

    Following promulgation of a new or revised NAAQS, EPA is required 
by CAA section 107(d) to designate areas throughout the nation as 
attaining or not attaining the NAAQS. On January 5, 2005 (70 FR 944), 
EPA published area designations for the 1997 PM2.5 NAAQS 
based on air quality data for the calendar years 2001-2003. In that 
rulemaking, EPA designated Libby, Montana as nonattainment for the 1997 
annual PM2.5 NAAQS. These designations became effective on 
April 5, 2005.
    On March 17, 2011 (76 FR 14584), EPA approved Montana's attainment 
plan which included an attainment demonstration, an analysis of 
reasonable available control technology/reasonable available control 
measure (RACT/RACM), base-year and projection year inventories, and 
contingency measures for the 1997 PM2.5 NAAQS for the Libby 
Area. On July 14, 2015 (80 FR 40911), EPA finalized its determination 
that the Libby Area attained the 1997 annual PM2.5 NAAQS by 
the Area's statutory attainment date of December 31, 2011. This 
determination was based upon quality-assured and certified ambient air 
monitoring data for the 2007-2009 monitoring period that demonstrated 
that the Libby Area attained the 1997 annual PM2.5 NAAQS by 
the attainment date. In the same rulemaking, EPA also issued a clean 
data determination under the Agency's Clean Data Policy \7\ based upon 
quality-assured and certified ambient air monitoring data that 
demonstrated the Libby Area continued to attain the 1997 annual 
PM2.5 NAAQS based on 2012-2014 monitoring data.\8\
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    \7\ See e.g., 70 FR 71612 (November 29, 2005) and 72 FR 20586 
(April 25, 2007).
    \8\ See 71 FR 19935 (April 14, 2015) that addresses the final 
clean data determination and a final determination of attainment by 
the attainment date for the Libby nonattainment area. As part of its 
clean data determination submission to EPA, Montana submitted the 
clean data determination to address the national ambient air 
requirements under Subpart 4.
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    On July 29, 2016, EPA issued a rule entitled ``Fine Particulate 
Matter National Ambient Air Quality Standards: State Implementation 
Plan Requirements'' (``PM2.5 SIP Requirements Rule''). See 
81 FR 58010 (August 24, 2016). This rule clarifies how states should 
meet the statutory SIP requirements that apply to areas designated 
nonattainment for any PM2.5 NAAQS under Subparts 1 and 4. It 
does so by establishing regulatory requirements and by providing 
guidance that is applicable to areas that are currently designated 
nonattainment for existing PM2.5 NAAQS and areas that are 
designated nonattainment for any PM2.5 NAAQS in the future. 
In addition, the rule responds to the D.C. Circuit's remand of the 1997 
PM2.5 Implementation Rules. As a result, the requirements of 
the rule also govern future actions associated with states' ongoing 
implementation efforts for the 1997 and 2006 PM2.5 NAAQS. In 
the PM2.5 SIP Requirements Rule, EPA revoked the 1997 
primary annual PM2.5 NAAQS in areas that had always been 
attainment for that NAAQS, and in areas that had been designated as 
nonattainment but that were redesignated to attainment before October 
24, 2016, the PM2.5 SIP Requirements Rule effective date. 
See 81 FR 58010 (August 24, 2016).
    In the August 24, 2016 final rule, EPA also finalized a provision 
to revoke the 1997 primary annual PM2.5 NAAQS in areas 
redesignated to attainment after October 24, 2016, on the effective 
date of an area's redesignation. See 40 CFR 50.13(d). If this proposal 
is finalized, the 1997 primary annual PM2.5 NAAQS will be 
revoked for the Libby Area on the effective date of the redesignation. 
Beginning on that date, the Area will no longer be subject to 
transportation or general conformity requirements for the 1997 annual 
PM2.5 NAAQS due to revocation of the primary NAAQS. See 81 
FR 58125-6. If redesignated, the Libby Area will be required to 
implement the maintenance plan requirements under section 175A for the 
1997 annual PM2.5 NAAQS, and the prevention of significant 
deterioration (PSD) program for the 1997 annual PM2.5 NAAQS. 
Once approved, the maintenance plan can only be revised if the revision 
meets the requirements of CAA section 110(l) and, if applicable, CAA 
section 193. As described in the PM2.5 SIP Requirements 
Rule, those 1997 annual PM2.5 maintenance areas with a 
revoked NAAQS are no longer required to submit a second 10-year 
maintenance plan for the 1997 annual PM2.5 NAAQS. See 81 FR 
58144.

C. PM2.5 NAAQS Nonattainment Area Planning Requirements

    The CAA establishes the requirements for redesignation of an area 
from nonattainment to attainment. Specifically, section 107(d)(3)(E) 
allows for redesignation of areas from nonattainment to attainment 
provided that the following criteria are met:
    (1) The Administrator has determined that the area has attained the 
applicable NAAQS;
    (2) The Administrator has fully approved the applicable SIP for the 
area under section 110(k) of the CAA;
    (3) The Administrator has determined that the improvement in air 
quality is due to permanent and enforceable reductions in emissions;
    (4) The Administrator has fully approved a maintenance plan for the 
area as meeting the requirements of section 175A of the CAA; and
    (5) The state containing the area has met all requirements 
applicable to the area under section 110 and part D of the CAA.
    Section 110 of the CAA identifies a comprehensive list of elements 
that SIPs must include, and part D establishes the SIP requirements for 
nonattainment areas. The generally applicable nonattainment SIP 
requirements are found in part D, subpart 1, and the particulate 
matter-specific SIP

[[Page 74580]]

requirements are found in part D, subpart 4.
    On April 16, 1992 (57 FR 13498), EPA provided guidance on 
redesignation in the General Preamble for the Implementation of Title I 
of the CAA Amendments of 1990, and the Agency supplemented this 
guidance on April 28, 1992 (57 FR 18070). EPA has provided further 
guidance on processing redesignation requests in the following 
documents:

    1. ``Procedures for Processing Requests to Redesignate Areas to 
Attainment,'' Memorandum from John Calcagni, Director, Air Quality 
Management Division, September 4, 1992 (hereinafter referred to as 
the ``Calcagni Memorandum'');
    2. ``State Implementation Plan (SIP) Actions Submitted in 
Response to Clean Air Act (CAA) Deadlines,'' Memorandum from John 
Calcagni, Director, Air Quality Management Division, October 28, 
1992; and
    3. ``Part D New Source Review (Part D NSR) Requirements for 
Areas Requesting Redesignation to Attainment,'' Memorandum from Mary 
D. Nichols, Assistant Administrator for Air and Radiation, October 
14, 1994 (hereinafter referred to as the ``Nichols Memorandum'').

D. Limited Maintenance Plans

    CAA section 175A(a) requires that nonattainment areas seeking 
redesignation to attainment submit ``a revision of the applicable state 
implementation plan to provide for the maintenance of the [NAAQS] for 
such air pollutant in the area concerned for at least 10 years after 
the redesignation.'' EPA explained in the Calcagni Memorandum that 
states may meet this requirement to ``provide for the maintenance of 
the NAAQS'' by using projected emissions inventories or air quality 
modeling showing continued maintenance until the end of the relevant 
maintenance period. See Calcagni Memorandum at 9-11. EPA clarified in 
three subsequent guidance memos that certain areas could meet the CAA 
section 175A requirement to provide for maintenance by demonstrating 
that the area's design value was well below the NAAQS and that the 
historical stability of the area's air quality levels showed that the 
area was unlikely to violate the NAAQS in the future.\9\ The Agency 
refers to this streamlined demonstration of maintenance as a limited 
maintenance plan.
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    \9\ See ``Limited Maintenance Plan Option for Nonclassifiable 
Ozone Nonattainment Areas'' from Sally L. Shaver, Office of Air 
Quality Planning and Standards (OAQPS), dated November 16, 1994; 
``Limited Maintenance Plan Option for Nonclassifiable CO 
Nonattainment Areas'' from Joseph Paisie, OAQPS, dated October 6, 
1995; Copies of these guidance memoranda can be found in the docket 
for this proposed rulemaking.
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    EPA has interpreted CAA section 175A as permitting this option 
because section 175A does not define how areas may demonstrate 
maintenance, and in EPA's experience with implementing the various 
NAAQS, areas that qualify for an LMP and have approved LMPs, have 
rarely, if ever, experienced subsequent violations of the NAAQS. As 
noted in the LMP guidance memoranda, states seeking an LMP must still 
submit the other maintenance plan elements outlined in the Calcagni 
Memorandum, including an attainment emissions inventory, provisions for 
the continued operation of the ambient air quality monitoring network, 
verification of continued attainment, and a contingency plan in the 
event of a future violation of the NAAQS. Moreover, states seeking to 
do an LMP must still submit a CAA section 175A maintenance plan as a 
revision to the SIP, with all attendant notice and comment procedures. 
While the LMP guidance memoranda were originally written with respect 
to certain NAAQS,\10\ EPA has extended the LMP interpretation of 
section 175A to other NAAQS and pollutants not specifically covered by 
the previous guidance memos.\11\
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    \10\ The prior memos addressed unclassifiable areas under the 1-
hour ozone NAAQS, nonattainment areas for the PM10 NAAQS, 
and nonattainment areas for the carbon monoxide NAAQS.
    \11\ See, e.g., 79 FR 41900 (July 18, 2014) (approval of second 
ten-year LMP for Grant County 1971 sulfur dioxide maintenance area).
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    To determine the LMP eligibility criteria for the Libby Area, EPA 
is interpreting the requirements as described in the 2001 memorandum 
from Lydia Wegman \12\ regarding LMPs for PM10 areas as 
applying to PM2.5. This memorandum states that one way for a 
PM10 area to qualify for an LMP is to show that the area's 
average design value (ADV) (based upon the most recent 5 years of 
monitoring data) is at or below the critical design value (CDV). The 
memorandum defines the CDV as an indicator of the likelihood of future 
violations of the NAAQS in an area given the area's current ADV and its 
historical variability and provides a means for calculating the CDV for 
an area (or monitoring site) (Attachment A of the 2001 Wegman 
Memorandum). The CDV is the highest average design value an area could 
have before it may experience a future violation of the NAAQS with a 
certain probability--in the case of the Wegman Memorandum, a 
probability of 1 in 10. Therefore, if an area's current ADV is less 
than the area's CDV, that area has a less than 1 in 10 chances of 
violating the NAAQS in the future. As noted in Attachment A of the 
Wegman Memorandum, the CDV calculation was designed to apply for any 
NAAQS pollutant and is not specific to PM10. Montana 
employed this methodology to demonstrate that the Libby Area is 
eligible for an LMP and that the plan therefore provides for 
maintenance of the NAAQS for 10 years following redesignation. We agree 
that the State's demonstration meets the requirements of CAA section 
175A and shows that the Area will continue to maintain the annual 
PM2.5 NAAQS following redesignation through 2031. In its SIP 
submission, Montana used a site-specific CDV calculated with 
PM2.5 data from the one ambient design value monitor in the 
Libby Area.
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    \12\ ``Limited Maintenance Plan Option for Moderate 
PM10 Nonattainment Areas'' from Lydia Wegman, OAQPS, 
dated August 9, 2001 (hereinafter referred to as the ``Wegman 
Memorandum''). A copy of this guidance memorandum can be found in 
the docket for this proposed rulemaking.
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    The 2001 Wegman Memorandum also provided that an LMP was 
appropriate only for those PM10 areas that were expecting 
limited growth of on-road motor vehicle emissions (including fugitive 
dust), and therefore included a motor vehicle regional emissions 
analysis demonstration that states seeking a PM10 LMP should 
perform (Attachment B to the Wegman Memorandum). According to the 
Wegman Memorandum, the demonstration should show that the ADV remains 
below the margin of safety provided for in the memorandum, even after 
the growth of on-road motor vehicle emissions is considered. This 
proposed rulemaking uses the site-specific CDV instead of the margin of 
safety described in the Wegman Memorandum for this analysis as EPA has 
not recommended a margin of safety for the 1997 annual PM2.5 
NAAQS.

III. Why is EPA proposing these actions?

    On June 24, 2020, the State of Montana requested that EPA 
redesignate the Libby Area to attainment for the 1997 annual 
PM2.5 NAAQS and submitted an associated SIP revision 
containing an LMP. EPA's evaluation of the plan and air quality data 
indicates that the Libby Area meets the requirements for redesignation 
set forth in section 107(d)(3)(E) of the CAA, including that the LMP 
fulfills the maintenance plan requirements under section 175A of the 
CAA. As a result of these findings, EPA is proposing to take the 
separate but related actions to approve the LMP and redesignate the

[[Page 74581]]

Libby Area from nonattainment to attainment.

IV. What is EPA's analysis of the request?

    To redesignate an area from nonattainment to attainment, the CAA 
requires EPA to determine that the area has attained the applicable 
NAAQS (CAA section 107(d)(3)(E)(i)). The criteria for determining if an 
area is attaining the 1997 annual PM2.5 NAAQS is set out in 
40 CFR 50.13 and 40 CFR part 50, appendix N. The 1997 annual 
PM2.5 primary and secondary standards are met when the 
annual design value \13\ at each eligible monitoring site within the 
area is less than or equal to 15.0 [micro]g/m\3\.
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    \13\ The Annual PM2.5 NAAQS design value is the 3-
year average of PM2.5 annual mean mass concentrations. 
These annual means are calculated as the weighted arithmetic mean of 
the four quarters of valid data at the site and the annual means are 
only considered valid when they meet data completeness requirements 
detailed in 40 CFR 50.13. Once three valid annual means are 
available, they can be averaged together to determine the annual 
design value for that site.
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    Based on data from 2007-2009, EPA determined that the Libby Area 
attained the 1997 annual PM2.5 standard by December 31, 
2011, well before its attainment date of July 14, 2015.\14\ In 
addition, EPA issued a final clean data determination under the Clean 
Data Policy that the Libby Area was attaining the 1997 annual 
PM2.5 NAAQS, based on quality-assured and certified ambient 
air quality data for the 2012-2014 monitoring period. The Libby Area 
has continued to attain the 1997 annual PM2.5 NAAQS since 
EPA's earlier determinations that the Area attained the NAAQS.
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    \14\ See 80 FR 40911.
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    The Libby Area has one State and Local Air Monitoring Station 
(SLAMS) monitor operated by the Montana Department of Environmental 
Quality (MDEQ). This monitor (Air Quality System (AQS) Site ID 30-53-
0018) has complete data for 2014-2021, which is the period of data 
utilized for this proposed redesignation.\15\
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    \15\ The criteria for determining if an area is attaining the 
1997 Annual PM2.5 NAAQS are set out in the 40 CFR 50.13 
and 40 CFR part 50, appendix N. Three years of valid annual means 
are required to produce a valid annual standard design value. A year 
meets data completeness requirements when at least 75 percent of the 
scheduled sampling days for each quarter have valid data.
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    Table 1 summarizes the annual mean PM2.5 data collected 
from 2014-2021 for the Libby Area.\16\ Table 2 shows the annual design 
values for 2016-2021. The data presented in the tables were calculated 
from all data available in AQS, including those data flagged by the 
State of Montana as potentially influenced by exceptional events. EPA 
deems these data valid as they are complete and have been certified by 
MDEQ.
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    \16\ The annual averages in Table 1 are calculated by averaging 
the four quarters of data.
    \17\ Annual mean concentration is the averaging of four complete 
quarters of data for each year. See 40 CFR part 50, appendix N.
    \18\ The Annual PM2.5 NAAQS design value is the 3-
year average of PM2.5 annual mean mass concentrations. 
See 40 CFR 50.13.
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    None of the annual design values from 2016-2021 from the Libby Area 
monitoring site exceed the 1997 annual PM2.5 NAAQS of 15.0 
[micro]g/m\3\, and as such, EPA proposes to determine that the Libby 
Area has attained the 1997 annual PM2.5 NAAQS, and therefore 
meets the requirement of CAA section 107(d)(3)(E)(i).

                             Table 1--PM2.5 One-Year Annual Mean Concentrations \17\
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              Year:                 2014      2015      2016      2017      2018      2019      2020      2021
----------------------------------------------------------------------------------------------------------------
Concentration ([micro]g/m\3\)...      9.3      14.9       9.8      14.3      14.6      11.4      13.8      14.6
----------------------------------------------------------------------------------------------------------------


                                     Table 2--PM2.5 Annual Design Value \18\
----------------------------------------------------------------------------------------------------------------
       3-Year Period:           2014-2016     2015-2017     2016-2018     2017-2019     2018-2020     2019-2021
----------------------------------------------------------------------------------------------------------------
Design Value ([micro]g/m\3\)         11.4          13.0          12.9          13.4          13.3          13.3
----------------------------------------------------------------------------------------------------------------

A. Has the State met all applicable requirements under section 110 and 
part D of the Clean Air Act (CAA) and have those requirements been 
fully approved? (CAA sections 107(d)(3)(E)(ii) and (v))

    Sections 107 (d)(3)(E)(ii) and (v) require EPA to determine that 
the area has a fully approved applicable SIP under section 110(k) that 
meets all the basic applicable requirements under section 110 and part 
D for purposes for redesignation. The following is a summary of how 
Montana meets these requirements.
1. CAA Section 110 Requirements
    Section 110(a)(2) of title I of the CAA delineates the general 
requirements for a SIP, which include enforceable emissions limitations 
and other control measures, means or techniques, provisions for the 
establishment and operation of appropriate devices necessary to collect 
data on ambient air quality, and programs to enforce limitations. The 
general SIP elements and requirements set forth in CAA section 
110(a)(2) include, but are not limited to the following:
     Submittal of a SIP that has been adopted by the state 
after reasonable public notice and hearing;
     Provisions for establishment and operation of appropriate 
procedures needed to monitor ambient air quality;
     Implementation of a source permit program;
     Provisions for the implementation of part C requirements 
(PSD);
     Provisions for the implementation of part D requirements 
for NSR permit programs;
     Provisions for air pollution modeling; and
     Provisions for public and local air agency participation 
in planning and emission control rule development.
    CAA section 110(a)(2)(D) requires that SIPs contain certain 
measures to prevent sources in a state from significantly contributing 
to air quality problems in another state; the portion of a state's SIP 
that include these measures is known as an interstate transport SIP. 
However, these CAA section 110(a)(2)(D) requirements apply to a state 
and are not linked with a particular nonattainment area's designation 
and classification in that state. The interstate transport SIP 
submittal requirements, where applicable, continue to apply to a state 
regardless of the designation of any one area in the state. Thus, EPA 
has determined that these requirements are not applicable requirements 
for purposes of redesignation. Instead, EPA has determined that the 
requirements

[[Page 74582]]

linked with a particular nonattainment area's designation and 
classifications are the relevant measures, i.e., the requirements that 
must be met, for EPA to redesignate an area.
    In addition, EPA has determined that the other CAA section 
110(a)(2) elements not connected with nonattainment plan submissions 
and not linked with an area's attainment status are not applicable 
requirements for purposes of redesignation because the area will still 
be subject to these requirements after it is redesignated. EPA 
concludes that the CAA section 110(a)(2) and part D requirements, which 
are linked with a particular area's designation and classification, are 
the relevant measures to evaluate in reviewing a redesignation request, 
and that section 110(a)(2) elements not linked to the area's 
nonattainment status are not applicable for purposes of redesignation. 
EPA has applied this interpretation consistently in many 
redesignations.\19\
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    \19\ See, e.g., 81 FR 4420 (July 17, 2006) (final redesignation 
for the Sullivan County, Tennessee area); 79 FR 43655 (July 28, 
2014) (final redesignation for Bellefontaine, Ohio lead 
nonattainment area); 61 FR 53174-53176 (October 10, 1996) and 62 FR 
24826 (May 7 1997) (proposed and final redesignation of Reading, 
Pennsylvania ozone nonattainment area); 61 FR 20458 (May 7 1996) 
(final redesignation for Cleveland-Akron-Lorain, Ohio ozone 
nonattainment area); 60 FR 62748 (December 7, 1995) (final 
redesignation of Tampa, Florida ozone nonattainment area); See also 
65 FR 37879, 37890, (June 19, 2000) (discussing this issue in final 
redesignation of Cincinnati, Ohio 1-hour ozone nonattainment area); 
and 66 FR 50399 (October 19, 2001) (final redesignation of 
Pittsburg, Pennsylvania 1-hour ozone nonattainment area).
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    EPA's review of the Montana SIP shows that the State has satisfied 
the general SIP requirements under section 110(a)(2) of the CAA, to the 
extent they are applicable for the purposes of redesignation. Moreover, 
EPA has previously approved provisions of Montana's SIP as 
demonstrating compliance with the CAA section 110(a)(2) requirements 
for the 1997 annual PM2.5 NAAQS. See 78 FR 45864 (July 30, 
2013). Therefore, EPA proposes to determine that MDEQ has met all 
general SIP requirements for the Libby Area that are applicable for 
purposes of redesignation under section 110 of the CAA.
2. Part D Requirements
    Subparts 1 and 4 of part D, title 1 of the CAA contain air quality 
planning requirements for PM2.5 nonattainment areas. Subpart 
1 contains general requirements for all nonattainment areas of any 
pollutant, including PM2.5, governed by a NAAQS. Subpart 1 
requirements include, among other things, provisions for RACM, RFP, 
emissions inventories, contingency measures, transportation conformity 
and general conformity. Subpart 4 contains specific planning and 
scheduling requirements for PM2.5 nonattainment areas. 
Sections 189(a), (c), (e) requirements apply specifically to Moderate 
PM2.5 nonattainment areas and include an approved permit 
program for construction of new and modified major stationary sources, 
provisions for RACM, an attainment demonstration, quantitative 
milestones demonstrating RFP toward attainment by the applicable 
attainment date, and provisions to ensure that the control requirements 
applicable to major stationary sources of PM2.5 precursors, 
except where the Administrator has determined that such sources do not 
contribute significantly to PM2.5 levels that exceed the 
NAAQS in the area.
    We address the applicability of these requirements to this action 
in the following sections.
3. Subpart 1, Section 172 Requirements
    Section 172(c) contains general requirements for nonattainment area 
plan provisions. A thorough discussion of these requirements may be 
found in the General Preamble. See 57 FR 13538 (April 16, 1992). EPA's 
longstanding interpretation is that certain planning requirements 
designed to get a nonattainment area to attainment of the NAAQS are not 
``applicable'' for purposes of CAA section 107(d)(3)(E)(ii) and (v) and 
therefore need not be approved into the SIP before EPA can redesignate 
the area. In the General Preamble, EPA set forth its interpretation of 
applicable requirements for purposes of evaluating redesignation 
requests when an area is attaining the standard. See 57 FR 13564. EPA 
noted that requirements for RFP and other measures designed to provide 
for an area's attainment do not apply in evaluating redesignation 
because those nonattainment planning requirements ``have no meaning'' 
for an area that is attaining the standard. Id. This interpretation is 
also set forth in the Calcagni Memorandum.
    EPA's understanding of CAA section 172 also forms its basis on its 
Clean Data Policy. Under the Clean Data Policy, EPA promulgates a 
determination of attainment, published in the Federal Register, which 
is subject to notice-and-comment rulemaking, and this determination 
formally suspends a state's obligation to submit most of the attainment 
planning requirements that would otherwise apply, including an 
attainment demonstration and planning SIPs to provide for RFP, RACM, 
and contingency measures under CAA section 179(c)(9). The Clean Data 
Policy has been codified in regulations regarding the implementation of 
the ozone and PM2.5 NAAQS. See e.g., 70 FR 71612 (November 
29, 2005) and 72 FR 20586 (April 25, 2007).
    Because the Libby Area is attaining the 1997 annual 
PM2.5 NAAQS, the attainment planning obligations in CAA 
section 172, including the requirement to submit an attainment 
demonstration and RACM (172(c)(1)), RFP (172(c)(2)), and contingency 
measures (172(c)(9)) are not considered ``applicable'' requirements for 
redesignation purposes under CAA section 107(d)(3)(E)(ii) and (v). In 
any case, Montana submitted these elements as part of the Moderate SIP 
requirements on March 26, 2008, and EPA approved them on March 17, 
2011.\20\
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    \20\ See 76 FR 14584.
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    Section 172(c)(3) of the CAA requires a comprehensive, accurate, 
current inventory of actual emissions from all sources of relevant 
pollutant(s) in nonattainment areas. EPA's March 17, 2011 approval of 
Montana's March 26, 2008 SIP submission included a 2005 base-year 
emissions inventory for the Libby Area. Montana also included an 
emissions inventory for calendar year 2014 with the June 24, 2020 SIP 
submittal of the LMP for the Libby Area. The 2001 Wegman Memorandum 
states that an attainment inventory should represent emissions during 
the same 5-year period associated with the air quality data used to 
determine that the area meets the requirements of the LMP option. In 
addition, EPA reviewed an updated 2017 emissions inventory \21\ in its 
analysis for the Libby PM2.5 LMP.
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    \21\ Available in the docket for this proposed rulemaking.
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    Section 172(c)(4) requires the identification and quantification of 
allowable emissions for major new and modified stationary sources in an 
area, and section 172(c)(5) and 189(a)(1)(A) requires source permits 
for the construction and operation of new and modified major stationary 
sources anywhere in the nonattainment area. EPA approved the current 
Montana NSR program for PM2.5 on July 18, 1995. See 60 FR 
36715. Having a fully approved nonattainment NSR program is not an 
applicable requirement for this action; nonetheless we have approved 
the State's program.\22\
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    \22\ A detailed rationale for this view is described in the 
memorandum from Mary Nichols, Assistant Administrative for Air and 
Radiation, dated October 14, 1994, entitled, ``Part D New Source 
Review Requirements for Areas Requesting Redesignation to 
Attainment.''
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    Section 172(c)(7) requires the SIP meet the applicable provisions 
of CAA

[[Page 74583]]

section 110(a)(2). EPA believes Montana's June 24, 2020 SIP submission 
pertaining to the Libby Area meets the requirements of section 
110(a)(2).
4. Subpart 1, Section 176 Conformity Requirements
    Section 176(c) of the CAA requires states to establish the criteria 
and procedures to ensure that federally supported or funded projects 
conform to the air quality planning goals in the applicable SIP. The 
requirement to determine conformity applies to transportation plans, 
programs and projects that are developed, funded, or approved under 
title 23 of the United States Code (U.S.C.) and the Federal Transit Act 
(transportation conformity) as well as to other federally supported or 
funded projects (general conformity). State transportation conformity 
SIP revisions must be consistent with federal conformity regulations 
relating to consultation, enforcement, and enforceability that EPA 
promulgated pursuant to its authority under the CAA.
    Although EPA interprets the conformity SIP requirements \23\ as not 
applying for purposes of evaluating the redesignation request under 
section 107(d)(3) \24\ we note that Montana has an approved conformity 
SIP. See 66 FR 48561 (September 21, 2001).
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    \23\ CAA section 176(c)(4)(E) requires states to submit 
revisions to their SIPs to reflect certain federal criteria and 
procedures for determining transportation conformity.
    \24\ EPA believes that this interpretation is reasonable because 
state conformity rules are still required after redesignation and 
federal conformity rules apply where states rules have not been 
approved. See Wall v. EPA, 265 F.3d 426 (6th Cir., 2001) (upholding 
this interpretation); 60 FR 62748 (December 7, 1995).
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5. Subpart 4 Requirements
    As discussed in Section I of this document, in NRDC v. EPA, the 
D.C. Circuit held that EPA should have implemented the 1997 
PM2.5 annual NAAQS pursuant to the particulate matter-
specific provisions of Subpart 4. On remand, EPA identified all areas 
designated nonattainment for either the 1997 or the 2006 
PM2.5 NAAQS, including the Libby Area, as Moderate 
nonattainment for purposes of Subpart 4 in the Classifications and 
Deadlines Rule. Moderate nonattainment areas are subject to the 
requirements of CAA sections 189(a), (c), and (e), including: (1) an 
approved permit program for construction of new and modified major 
stationary sources (section 189(a)(1)(A)); (2) an attainment 
demonstration, (section 189(a)(1)(B)); (3) provisions for RACM (section 
189(a)(1)(C)); (4) quantitative milestones demonstrating RFP toward 
attainment by the applicable attainment date (section 189(c)); and (5) 
precursor control (section 189(e)).
    With respect to the specific attainment planning requirements under 
Subpart 4,\25\ EPA applies the same interpretation that it applies to 
attainment planning requirements under Subpart 1 or any other 
pollutant-specific subparts. That is, under its long-standing 
interpretation of the CAA, where an area is already attaining the 
standard, EPA does not consider those attainment planning requirements 
to be applicable for purposes of evaluating a request for 
redesignation, that is, CAA section 107(d)(3)(E)(ii) or (v), because 
requirements that are designed to help an area achieve attainment no 
longer have meaning where an area is already meeting the standard. EPA 
is therefore proposing to determine that the specific attainment 
planning requirements under Subpart 4 are not applicable for evaluating 
Montana's redesignation request.
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    \25\ These planning requirements include the attainment 
demonstration, qualitative milestone requirements, and RACM 
analysis.
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    CAA section 189(e) provides that control requirements for major 
stationary sources of direct PM10 (including 
PM2.5) shall also apply to particulate matter precursors 
from those sources, except where EPA determines that major stationary 
sources of such precursors do not contribute significantly to 
PM10 levels that exceed the standard in the area. The CAA 
does not explicitly address whether it would be appropriate to include 
a potential exemption from precursor controls for all source categories 
under certain circumstances. In implementing Subpart 4 with regard to 
controlling PM10, EPA permitted states to determine that a 
precursor was ``insignificant'' where the state could show in its 
attainment plan that it would expeditiously attain without adoption of 
emission reduction measures aimed at that precursor. This approach was 
upheld in the Association of Irritated Residents v. EPA, 423 F.3d 989 
(9th Cir. 2005) and extended to PM2.5 implementation in the 
PM2.5 SIP Requirements Rule. A state may develop its 
attainment plan and adopt RACM that target only those precursors that 
are necessary to control for purposes of timely attainment. See 81 FR 
58010 at 58020 (August 24, 2016).
    For the Libby Area, a precursor exemption analysis under section 
189(e) and EPA's implementing regulations is not an applicable 
requirement that needs to be fully approved in the context of a 
redesignation under CAA section 107(d)(3)(E)(ii) since the Area is 
already in attainment which demonstrates that precursors contribution 
is insignificant. Therefore, measures aimed at the precursors are not 
needed.
    As discussed previously in this document, for areas that are 
attaining the standard, EPA does not interpret attainment planning 
requirements of Subparts 1 and 4 to be applicable requirements for 
purposes of redesignating an area to attainment. On July 14, 2015, EPA 
approved that the Libby Area had attained the 1997 annual 
PM2.5 NAAQS by the Area's statutory attainment date. The 
Libby Area has expeditiously attained the 1997 annual PM2.5 
NAAQS, and therefore, no additional controls of any pollutant, 
including any PM2.5 precursor, are necessary to bring it 
into attainment. In section V of this document, we find that the Libby 
Area continues to attain the NAAQS. EPA has determined that the Libby 
Area has attained the standard due to permanent and enforceable 
emissions reductions. Further, as set forth in section IV.C of this 
document, we believe that the Libby PM2.5 LMP demonstrates 
continued maintenance of the 1997 annual PM2.5 NAAQS 
standard through 2031 which also demonstrates that the PM2.5 
precursors are insignificant. Taken together, these factors support our 
conclusion that PM2.5 precursors are adequately 
controllable.

B. Has the state demonstrated that air quality improvement is due to 
permanent and enforceable reductions?

    In order to approve a redesignation from nonattainment to 
attainment, section 107(d)(3)(E)(iii) of the CAA requires EPA to 
determine that the improvement in air quality is due to emission 
reductions that are permanent and enforceable, and that the improvement 
results from the implementation of the applicable SIP and applicable 
federal air pollution control regulations and other permanent and 
enforceable regulations. Under this criterion, a state must be able to 
reasonably attribute the improvement in air quality to emissions 
reductions that are permanent and enforceable. Attainment resulting 
from temporary reductions in emission rates (e.g., reduced production 
or shutdown due to temporary adverse economic conditions) or unusually 
favorable meteorology would not qualify as an air quality improvement 
due to permanent and enforceable emission reductions. See Calcagni 
Memorandum at 4. In its demonstration that improvements in air quality 
are reasonably attributable to emissions reductions that are permanent

[[Page 74584]]

and enforceable, Montana evaluated several factors: \26\ the 
composition of PM2.5 in the nonattainment area; control 
measures that have been implemented since the area was redesignated to 
nonattainment; changes to the emissions inventory over time; and 
meteorological and economic trends. In its evaluation, Montana 
identified two fugitive area sources contributing to PM2.5 
concentrations in the nonattainment area: wood combustion and tailpipe 
emissions. Eighty-two percent of the PM2.5 concentrations 
during the baseline study year of 2005 was attributed to wood 
combustion. Wood combustion impacts represented both residential and 
small commercial space heating, and outdoor burns. The State identified 
emission reductions from only the wood combustion category in the 
attainment plan; the plan did not take credit for reductions from 
mobile source tailpipe emissions due to federal tailpipe standards or 
fleet turnover.
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    \26\ See Montana's attainment plan for the Libby Area, approved 
on March 17, 2011 (76 FR 14584).
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    In its approved Moderate nonattainment plan, Montana adopted 
permanent and enforceable rules from the Lincoln County Air Pollution 
Control Program. This program includes rules that reduce 
PM2.5 impacts in the nonattainment area resulting in 
attainment of PM2.5 NAAQS.\27\ The air pollution control 
rules in Chapter 1, Subchapters 1 through 4 of the Lincoln County Air 
Pollution Control Program, address solid fuel burning devices, re-
entrained road dust control, and outdoor burning regulations. These 
rules are part of the Lincoln County Health Department's Health and 
Environmental Rules in Chapter 1. The rules contain the following 
subchapters, all designed to help Lincoln County attain the 
PM2.5 NAAQS:
---------------------------------------------------------------------------

    \27\ See Section 1.3 in the Libby Area SIP submission. Available 
in the docket for this proposed rulemaking.
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     Subchapter 1--(75.1.100-106)--General Provisions;
     Subchapter 2--(75.1.200-206,208)--Solid Fuel Burning 
Device Regulations;
     Subchapter 3--(75.1.301-308)--Dust Control Regulations; 
and
     Subchapter 4--(75.1.401-408)--Outdoor Burning Regulations.
    The regulations in Lincoln County's Subchapter 2 require that solid 
fuel burning devices be permitted by the Lincoln County Environmental 
Health Department. The regulations restrict the material allowed for 
combustion and prohibit visible emissions greater than 20 percent 
opacity. Lincoln County will call Air Pollution Alerts \28\ when 
particulate matter concentrations are more than 80 percent of the 24-
hour standard and at that time, solid fuel burning devices are not 
allowed to operate unless the device has received an exemption. A 
provision allows exempt devices to be operated during an alert, but 
only with an opacity of 10 percent or less.
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    \28\ See 75.1.206, Lincoln County Air Pollution Control Program.
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    Although re-entrained road dust is not an identified emission 
source category, Subchapter 3 of the Lincoln County rules address re-
entrained dust from roads, parking lots and commercial lots by 
requiring dust abatement and control. These road dust regulations apply 
within the regulated road sanding and sweeping district as defined in 
the regulation. Vehicular operations within the district are only 
allowed on paved surfaces within the district. To control ice on the 
roads, liquid de-icing agents and de-icing salts should be used. 
Sanding material is not allowed unless the Lincoln County Environmental 
Health Department declares an emergency and then only sanding material 
that meets specific durability, abrasion, and fine concentrations are 
allowed. Roads are to be maintained using a schedule of prioritized 
street sweeping and flushing to remove carry-on or applied materials. 
Commercial operations shall also implement measures to prevent 
depositing material on yards/lots, suppress dust, and clean adjoining 
roadways.
    Lincoln County's Subchapter 4 addresses outdoor burning and 
restricts non-essential outdoor burning, promoting alternative disposal 
methods and recycling, and setting standards to minimize emissions when 
outdoor burning is necessary. These rules apply to both the air 
pollution control district which is the same area as the Libby 
nonattainment area, and the Impact Zone L, which extends beyond the 
nonattainment area. The rules specify which materials and activities 
are prohibited for outdoor burning. Residential outdoor burning is only 
allowed in the month of April while management burns are allowed from 
April through October. Burning outside these months requires additional 
approval from the Lincoln County Health Department. Burners must obtain 
a burn permit from the Department and may only conduct their burn if 
meteorological conditions have good air dispersion characteristics, as 
determined by the Department.
    Montana has determined that most of the emissions reductions from 
the wood combustion source category are attributed to the Lincoln 
County residential wood combustion rules. These rules control 
residential and small commercial wood combustion used for space heating 
through a wood stove permit program. The rules restrict the 
installation and operation of wood stoves to times with good air 
quality dispersion. Lincoln County also has outdoor open burning rules 
that require burns to be permitted and approved to ensure the burns 
occur during favorable meteorological conditions.
    Montana evaluated emissions from residential wood burning 
contributing to PM2.5 in Libby, Montana. Table 2.3 in the 
June 24, 2020 Libby Area SIP submission displays the 2005 actual annual 
emissions, which are considered the annual baseline emissions for 
Libby. Additionally, the table shows the annual emissions from the 2014 
National Emissions Inventory (NEI). As shown in the Table 2.3, 
emissions for residential wood burning in 2014 have decreased more than 
85 percent compared to the baseline emissions in 2005. The total 
emissions for area source categories for 2014 total emissions have 
decreased more than 62 percent compared to the 2005 baseline emissions.
    In addition, Montana has adopted permitting requirements for major 
stationary sources or major modifications located in the nonattainment 
areas including Libby, Montana. They are located in the Administrative 
Rules of Montana (ARM) 17.8.901 through 17.8.906. These rules require 
all new sources or modifications to use the lowest achievable emission 
rate (LAER). Sources must obtain emission reduction offsets in tons per 
year (tpy) which provide a positive net air quality benefit in the 
nonattainment area using a one to one offset and must be from the same 
source or another emissions source within the same nonattainment area. 
There must be demonstrated improvement to the PM2.5 
nonattainment with permanent, quantifiable, and federally enforceable 
reductions. A reduction of actual emissions, not potential emissions, 
must occur before a new source can be permitted to operate.
    In addition, Montana has a federally enforceable permitting program 
for minor sources in ARM, Title 17 Chapter 8, Subpart 7 that addresses 
PM2.5 emissions. These rules require sources that emit 25 
tpy or more of PM2.5 to ensure the nonattainment area is not 
negatively affected. Beginning in May 2019, Montana began requiring 
registration of all sized asphalt plants, concrete plants, mineral 
crushers, and

[[Page 74585]]

mineral screens. The registration program establishes conservative 
operational restrictions on these portable sources to prevent 
degradation of the air quality in nonattainment areas and elsewhere.
    Not only has air quality in the Libby Area benefited from the local 
district and State rules discussed previously, but the Area has also 
benefitted from emission reductions from federal measures including 
federal tailpipe standards and the Federal Motor Vehicle Control 
Program. Federal tailpipe standards were designed to reduce vehicle 
emissions, including PM2.5. The previous control plan did 
not take credit for the PM2.5 reductions resulting from 
lower federal vehicle emissions standards and vehicle fleet turnover in 
the nonattainment area. The federal tailpipe standards and vehicle 
turnover will continue to reduce future impacts and meet the 
requirements of the 1990 CAA Amendments. The Federal Motor Vehicle 
Control Program controls tailpipe emissions and evaporative emission 
standards for new vehicles. Tailpipe impacts were less than one percent 
of the Libby Area during the 2005 baseline year.\29\ The 
PM2.5 impact reductions are supported by lower fleet vehicle 
fleet emissions as fleet turnover continues.
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    \29\ See Table 2.3 in the Libby Area SIP submission. Available 
in the docket for this proposed rulemaking.
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    Based upon the previously listed actions by Montana in the 
submitted maintenance plan, EPA finds that the improvement in air 
quality in the Libby Area is the result of permanent and enforceable 
emissions reductions from a combination of EPA-approved local and State 
control measures and federal control measures. As such, we believe the 
criterion for redesignation set forth in CAA section 107(d)(3)(E)(iii) 
is satisfied.

C. Does the Area have a fully approved maintenance plan pursuant to 
section 175A of the CAA?

    For redesignating a nonattainment area to attainment, the CAA 
requires EPA to determine that the area has a fully approved 
maintenance plan pursuant to section 175A of the CAA (CAA section 
107(d)(3)(E)(iv)). In conjunction with its request to redesignate the 
Libby Area to attainment for the 1997 annual PM2.5 NAAQS, 
Montana submitted a SIP revision to provide for the maintenance of the 
1997 annual PM2.5 NAAQS for at least 10 years after the 
effective date of redesignation to attainment. EPA believes that this 
maintenance plan meets the requirements for approval under section 175A 
of the CAA for the reasons discussed in this section.
    Section 175A of the CAA sets forth the elements of a maintenance 
plan for areas seeking redesignation from nonattainment to attainment. 
Under section 175A, the plan must demonstrate continued attainment of 
the applicable NAAQS for at least 10 years after the Administrator 
approves a redesignation to attainment. Because the 1997 primary annual 
PM2.5 NAAQS will be revoked for the Libby Area if it is 
redesignated to attainment, Montana is not required to submit a second 
10-year maintenance plan for the 1997 primary annual PM2.5 
NAAQS. See 81 FR 58010, 58144. To address the possibility of future 
NAAQS violations, the maintenance plan must contain such contingency 
measures, as EPA deems necessary, to assure prompt correction of any 
future 1997 annual PM2.5 NAAQS violations. The Calcagni 
Memorandum provides further guidance on the content of a maintenance 
plan, explaining that a maintenance plan should address five 
requirements: the attainment emissions inventory; maintenance 
demonstration; monitoring; verification of continued attainment; and a 
contingency plan. As is discussed here, EPA finds that Montana's 
maintenance plan includes all the necessary components and is thus 
proposing to approve it as a revision to the Montana SIP.
1. Attainment Emissions Inventory
    As discussed previously, EPA is proposing to determine that the 
Libby Area is attaining the 1997 annual PM2.5 NAAQS based on 
a monitoring data for the time period from 2014-2021. Montana selected 
2014 as the attainment emission inventory year. The attainment 
inventory identifies the level of emissions in the Area that is 
sufficient to attain the 1997 annual PM2.5 NAAQS. Montana 
began development of the attainment inventory by first generating a 
baseline emissions inventory for the Libby Area. Montana selected 2005 
as the base year for developing a comprehensive emissions inventory for 
direct PM2.5 and the PM2.5 precursors 
SO2, NOX, VOCs, and ammonia. See 76 FR 14584 
(March 17, 2011). The Wegman Memorandum states that an attainment 
inventory should represent emissions during the same 5-year period 
associated with the air quality data used to determine that the area 
meets the applicability requirements of the LMP option. The Libby LMP, 
provided in Montana's June 24, 2020 SIP submission, includes an 
emission inventory from 2014, representative of the 2014-2021 time 
period which served as the 5-year period relied upon in limited 
maintenance plans as meeting the air quality data requirements of the 
Wegman Memorandum.\30\
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    \30\ The emissions inventory included in the Libby Area SIP 
submission is the 2014 NEI. The NEI is a composite of data from many 
different sources, with PM data coming primarily from EPA models as 
well as from state, tribal, and local air quality management 
agencies. Different data sources use different data collection 
methods, and many of the emissions data are based on estimates 
rather than actual measurements. EPA considers the 2014 NEI 
representative of the period from 2014-2021 because Montana provided 
comparable vehicle miles traveled (VMT) data in their submission. 
See Libby Area SIP submission, Appendix A, Montana Department of 
Transportation Future VMT Projections, p. A-1 in docket for this 
proposed rulemaking.
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2. Maintenance Demonstration
    Montana's SIP submission for the Libby Area employs the CDV method 
laid out in the 2001 Wegman Memorandum to demonstrate that the Area is 
eligible for an LMP. As noted previously, the CDV calculation from the 
Wegman Memorandum represents the highest design value an area could 
have before it would violate the NAAQS given a 1 in 10 probability--
that is, if the area's current ADV (based on the most recent five years 
of data) is less than the CDV, there is a less than 1 in 10 
probabilities that the area will violate in the future. The State's 
submission calculates the ADV as 10.9 [micro]g/m\3\ and calculates the 
site-specific CDV as 14.1 [micro]g/m\3\ using the Libby Area monitor 
data from 2014-2018. Therefore, the State's submission showed the Libby 
ADV is less than the CDV, but because of the time that has elapsed 
since the State's submission, EPA has also analyzed more recent data 
that are available in AQS and have been certified by the MDEQ.
    To calculate the ADV we averaged the most recent five design values 
for the PM2.5 annual standard. Since each design value is 
calculated by averaging three years of valid annual means, the average 
of the last five design values includes data from the most recent 7-
year period (2014-2021). Table 3 presents the most recent annual 
PM2.5 NAAQS design values for 2017-2021 and presents the 
resulting ADV of 13.2 [micro]g/m\3\.
    To calculate the CDV we use the most recent five years of design 
values and their variability with the equation presented in the Wegman 
Memorandum (Table 3). The resulting site-specific CDV is calculated to 
be 14.6 [micro]g/m\3\ (Table 5). Therefore, the ADV (13.2 [micro]g/
m\3\) falls below the site-specific CDV of

[[Page 74586]]

14.6 [micro]g/m\3\ and thus meets the first criterion for LMP 
eligibility.\31\
---------------------------------------------------------------------------

    \31\ See Libby PM2.5 CDV Calculations in docket for 
this proposed rulemaking.

                                             Table 3--Annual PM2.5 NAAQS Design Values ([micro]g/m\3\) \32\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                 Average of most  recent
2017 Design value  (2015- 2018 Design value  (2016- 2019 Design value  (2017- 2020 Design value  (2018-    2021 Design value       3-year design values
         2017) *                   2018) *                   2019) *                   2020) *               (2019-2021) *                (ADV)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                 13.0                      12.9                      13.4                      13.3                     13.3                     13.2
--------------------------------------------------------------------------------------------------------------------------------------------------------


               Table 4--Eligibility Calculation Equations
------------------------------------------------------------------------
 
------------------------------------------------------------------------
Critical Design Value..................  CDV = NAAQS/(1 + (tc x CV))
Coefficient of Variation...............  CV = [sigma]/ADV
Projected DV due to Motor Vehicle        Projected DV = ADV + (VMTpi x
 Growth over 10 years.                    DVmv)]
------------------------------------------------------------------------
ADV = Average of 3-year design values.
DV = Design value.
DVmv = motor vehicle design value based on on-road mobile portion of the
  attainment year inventory.
NAAQS = Applicable standard (15 [mu]g/m\3\).
[sigma] = standard deviation of design values.
tc = Critical t-value (based on the one-tail student's t-distribution,
  at a significance level of 0.10).
VMTpi = Projected percent increase in vehicle miles traveled (VMT) over
  the next 10 years.


      Table 5--Calculation of the CDV Using 2017-2021 Design Values
------------------------------------------------------------------------
 
------------------------------------------------------------------------
NAAQS..................................  15.0 [mu]g/m\3\
Tc.....................................  1.533
ADV (2017-2021)........................  13.2 [mu]g/m\3\
[Sigma]................................  0.2168 [mu]g/m\3\
CV.....................................  0.0164
CDV = [NAAQS/(1 + tc x CV)]............  14.6 [mu]g/m\3\
------------------------------------------------------------------------

    In addition to having an ADV that is at or below the site-specific 
CDV, the 2001 Wegman Memorandum also provides a methodology for 
calculating a margin of safety factor based on expected growth in 
mobile source emissions. The memo lays out in Attachment B a motor 
vehicle regional emissions analysis test, which is designed to account 
for an area's expected change in vehicle miles traveled, to determine 
whether increased emissions from on-road mobile sources could, in the 
next 10 years, increase concentrations in the area and threaten the 
assumption of maintenance that underlies LMP policy. In its June 24, 
2020 SIP submission, Montana employed the motor vehicle regional 
emissions analysis test outlined in Attachment B of the Wegman 
Memorandum to demonstrate that the Libby Area's expected growth in 
mobile source emissions would not threaten maintenance of the NAAQS. 
Using data from 2014-2018 the State calculated that due to growth in 
mobile source emissions the ADV may increase from 10.9 [micro]g/m\3\ to 
11.1 [micro]g/m\3\ in the next 10 years, but that 11.1 [micro]g/m\3\ is 
still below the margin of safety as defined by the site-specific CDV 
(14.1 [micro]g/m\3\). EPA has also examined more recent data to confirm 
that even with updated information, the test continues to show that 
anticipated growth in mobile source emissions should not interfere with 
the Libby Area's maintenance of the 1997 annual PM2.5 NAAQS. 
Using design values from 2017-2021, we calculated that due to expected 
growth in mobile source emissions, the ADV may increase from 13.2 
[micro]g/m\3\ to 13.5 [micro]g/m\3\ in the next 10 years, but that 13.5 
[micro]g/m\3\ is still below the margin of safety as defined by the 
site-specific CDV (14.6 [micro]g/m\3\). For the calculations used to 
determine how the Libby Area passed the motor vehicle regional analysis 
test, see Table 6.\33\
---------------------------------------------------------------------------

    \32\ In Table 3, (years)* is referring to what data was included 
in the calculation for each 3-year design value.
    \33\ See Memo to File, Libby MT Motor Vehicle Regional Emission 
Analysis in docket for this proposed rulemaking.

  Table 6--Motor Vehicle Regional Emissions Analysis Test Calculations
------------------------------------------------------------------------
 
------------------------------------------------------------------------
ADV (2017-2021)........................  13.2 [micro]g/m\3\
VMTpi..................................  11.56%
DVmv...................................  2.5 [micro]g/m\3\
Calculated [ADV + (VMTpi x DVmv)]......  13.5 [micro]g/m\3\
------------------------------------------------------------------------

    The 2001 Wegman Memorandum also indicates that once a state has an 
approved LMP, the state will be expected to determine, on an annual 
basis, that the LMP criteria are still being met. If the state 
determines that the LMP criteria are not being met, it should take 
action to reduce PM2.5 concentrations enough to requalify 
for the LMP. One possible approach a state could take is to implement 
contingency measures. For a description of contingency provisions 
included in the Libby LMP, see section 3.6 of Montana's June 24, 2020 
SIP submission.
    Although the State flagged some PM2.5 values as 
potentially affected by exceptional events, such as wildfire

[[Page 74587]]

smoke, this action utilizes all quality-assured monitoring data from 
Libby. A 2019 memo from Richard Wayland and Anna Wood regarding 
additional methods, determinations, and analyses to modify air quality 
data beyond exceptional events,\34\ indicates that monitoring data 
could qualify for exclusion for use in calculating air quality design 
values in support of a NAAQS LMP submission and any subsequent yearly 
design value calculations for areas with approved LMPs. The memorandum 
states that such data exclusion requests will be treated in a manner 
analogous to the treatment of exceedance data under the Exceptional 
Events Rule (EER). Since the Libby Area qualifies for the LMP option 
without the removal of any demonstrated values, the flagged data have 
no regulatory significance and therefore the demonstrated values are 
included in the calculations and remain in AQS. Additional information 
on the EER can be found in 40 CFR 50.14 and 40 CFR 51.930.
---------------------------------------------------------------------------

    \34\ See the memorandum from Richard Wayland, Director of Air 
Quality Assessment Division and Anna Marie Wood, Director of Air 
Quality Policy Division, dated April 4, 2019, entitled, ``Additional 
Methods, Determinations, and Analyses to Modify Air Quality Data 
Beyond Exceptional Events.''
---------------------------------------------------------------------------

    Pursuant to the Wegman Memorandum, the State's approved maintenance 
plan should include an emissions inventory (attainment inventory) which 
can be used to demonstrate attainment of the NAAQS. The inventory 
should represent emissions during the same 5-year period associated 
with air quality data used to determine whether the area meets the 
applicability requirements of the LMP option. The state should review 
its inventory every three years to ensure emissions growth is 
incorporated in the attainment inventory, if necessary. In this 
instance, Montana completed an attainment year inventory for 2014 for 
the Libby Area. EPA has reviewed the 2014 emissions inventories and 
determined that they are appropriate for this plan.
3. Monitoring Network
    The PM2.5 monitoring network for the Libby Area has been 
developed and maintained in accordance with federal siting and design 
criteria in 40 CFR part 58, appendices D and E and in consultation with 
EPA Region 8. In section 3.5 of the Libby LMP, located within Montana's 
June 24, 2020 SIP submission, Montana states that it will continue to 
operate its monitoring network to meet EPA requirements at 40 CFR part 
58 and identify any issues or adjustments via the annual Ambient Air 
Monitoring Network Plan or formal communication. EPA approved Montana's 
2021 monitoring plan on November 16, 2021.\35\
---------------------------------------------------------------------------

    \35\ See MT AMNP Approval Letter 2021 in docket for the proposed 
rulemaking.
---------------------------------------------------------------------------

4. Verification of Continued Attainment
    Montana, through MDEQ, has the legal authority to enforce and 
implement the requirements of the Libby LMP. This includes the 
authority to adopt, implement, and enforce any subsequent emissions 
control contingency measures determined to be necessary to correct 
future PM2.5 attainment problems.
    In demonstrating maintenance, continued attainment of the NAAQS can 
be verified through operation of an appropriate air quality monitoring 
network. The Calcagni Memorandum (p.11) states that the maintenance 
plan should contain provisions for continued operation of air quality 
monitors that will provide such verification. As discussed in section V 
of this document, PM2.5 is currently monitored by MDEQ 
within the Libby Area. In section 3.5 of Montana's submitted 
maintenance plan, MDEQ intends to maintain an appropriate 
PM2.5 monitoring network and review monitoring and emissions 
data through the maintenance period.
    MDEQ will track the progress of the maintenance plan by performing 
future reviews of triennial emission inventories for the Libby Area as 
required in the Air Emissions Reporting Rule (AERR). Emissions 
information will be compared to the attainment year to assure continued 
compliance with the annual PM2.5 standard.
5. Contingency Provisions
    Section 175A(d) of the CAA requires that the maintenance plan 
contains contingency provisions to assure that the state will promptly 
correct any violation of the relevant PM2.5 NAAQS that may 
occur after the redesignation of the area to attainment. Such 
provisions must include a requirement that the state will implement all 
measures with respect to the control of the air pollutant concerned 
that were contained in the SIP for the area before redesignation of the 
area as an attainment area. EPA's redesignation guidance notes that the 
state is not required to have fully adopted contingency measures that 
will take effect without further action by the state. As such, the 
contingency plan should ensure that the state has the capacity to adopt 
the contingency measures expediently if the need were triggered. 
Therefore, the primary elements of this contingency plan involve the 
tracking and triggering mechanisms to determine when contingency 
measures would be necessary and a process for implementing appropriate 
control measures.
    Montana will continue to monitor and analyze PM2.5 
concentrations to determine continued maintenance of the relevant 
PM2.5 NAAQS. In accordance with 40 CFR part 58, MDEQ will 
continue to operate the Libby monitor (Site ID 30-053-0018).
    If the State determines the Libby Area has exceeded the 1997 annual 
PM2.5 NAAQS, the triggering of the contingency plan does not 
automatically require a revision of the SIP, nor is the Area 
necessarily redesignated once again to nonattainment. Instead, MDEQ 
will have an appropriate timeframe to correct the violation with 
implementation of one or more adopted contingency measures. If 
violations continue to occur, additional contingency measures may need 
to be adopted until the violations are corrected.
    Montana has adopted a contingency provision to address future 
PM2.5 air quality problems. The contingency provisions in 
the Libby PM2.5 LMP are contained in section 3.6. of 
Montana's June 24, 2020, SIP submission. MDEQ identifies the following 
steps if a violation occurs, and the State triggers the contingency 
plan:
    1. Within 12 months of an exceedance notification, MDEQ and the 
local government in the Libby Area will commence an analysis to review 
information about historical exceedances of the standard, the 
meteorological conditions related to recent exceedance(s), most recent 
growth, and emissions, and if the possibility of an exceptional event 
occurred. MDEQ will develop appropriate contingency measure(s) to 
correct the violation of the PM2.5 standard.
    2. Under the 2016 revisions to the Treatment of Data Influenced by 
Exceptional Events Rule (81 FR 68216), MDEQ will confer with EPA Region 
8 regarding whether any flagged exceptional events would meet the 
criteria of a regulatory decision, and if so, a determination would be 
made on whether to move forward with producing a demonstration and if 
that would trigger contingency measures.
    3. If MDEQ and the local government in the Libby Area finds locally 
adopted control measures to be inadequate, MDEQ and the local 
government will adopt state-enforceable measures as deemed necessary by 
MDEQ to prevent additional exceedances or violations.

[[Page 74588]]

Measures to be considered include implementation of Libby's Contingency 
Rules 75.1.208 and 75.1.307, as spelled out in Montana's Libby 
PM2.5 attainment plan, the use of deciphers, additional 
street cleaning, etc.
    Upon our review, we find that the contingency provisions of the 
Libby PM2.5 LMP satisfy the pertinent requirements of 
section 175A of the CAA.

D. Transportation and General Conformity

    The requirements for transportation and general conformity are 
found in CAA section 176(c). Conformity to the SIP means that 
transportation-related actions (transportation conformity) and other 
federal actions (general conformity) will not cause or contribute to 
any new violation of any standard in any area, increase the frequency 
or severity of any existing violation of any standard in any area or 
delay timely attainment of any standard or any required interim 
emission reductions or other milestones in any area (CAA section 
176(c)(1)(B)).
    As discussed in section II.B, if the proposal is finalized, the 
1997 primary annual PM2.5 NAAQS will be revoked in the Libby 
Area on the effective date of the redesignation. Beginning on that 
date, the Area will no longer be subject to transportation conformity 
or general conformity requirements for the 1997 annual PM2.5 
NAAQS due to the revocation of the 1997 primary annual PM2.5 
NAAQS. See 81 FR 58125-6.

V. What are the effects of EPA's proposed actions?

    EPA's proposed actions establish the basis upon which EPA may take 
final action on the issues being proposed for approval. Approval of 
Montana's redesignation request would change the legal designation of 
Lincoln County for the 1997 annual PM2.5 NAAQS, found at 40 
CFR part 81, from nonattainment to attainment. The limited maintenance 
plan includes contingency measures to remedy any future violations of 
the 1997 annual PM2.5 NAAQS and procedures for evaluation of 
potential violations.

VI. Proposed Actions

    EPA is proposing to: (1) determine that the Libby Area is attaining 
the 1997 annual PM2.5 NAAQS based on 2014-2021 data; (2) 
approve Montana's plan for maintaining the 1997 annual PM2.5 
NAAQS (limited maintenance plan); and (3) redesignate the Libby Area to 
attainment for the 1997 annual PM2.5 NAAQS. If finalized, 
approval of the redesignation request would change the official 
designation of Lincoln County for the 1997 annual PM2.5 
NAAQS, found at 40 CFR part 81 from nonattainment to attainment, as 
found at 40 CFR part 81.

VII. Statutory and Executive Order Reviews

    Under the CAA, redesignation of an area to attainment and the 
accompanying approval of a maintenance plan are actions that affect the 
status of a geographical area and do not impose any additional 
regulatory requirements on sources beyond those imposed by state law. A 
redesignation to attainment does not in and of itself create any new 
requirements, but rather results in the applicability of requirements 
contained in the CAA for areas that have been redesignated to 
attainment. Moreover, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act 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 these reasons, 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 13563 (76 FR 3821, January 21, 
2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Public Law 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     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; and
     Executive Order 12898 (59 FR 7629, February 16, 1994, 
directs federal agencies, to the greatest extent practicable and 
permitted by law, to make environmental justice part of their mission 
by identifying and addressing, as appropriate disproportionately high 
and adverse human health or environmental effects of their program, 
policies, and activities on minority populations (people of color/
Indigenous people) and low-income populations.
    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 proposed 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).

List of Subjects

40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide, 
Greenhouse gases, Incorporation by reference, Intergovernmental 
relations, Lead, Nitrogen dioxide, Ozone, Particulate matter, Reporting 
and recordkeeping requirements, Sulfur oxides, Volatile organic 
compounds.

40 CFR Part 81

    Environmental protection, Air pollution control, National parks, 
and Wilderness areas.

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

    Dated: December 1, 2022.
KC Becker,
Regional Administrator, Region 8.
[FR Doc. 2022-26504 Filed 12-5-22; 8:45 am]
BILLING CODE 6560-50-P