[Federal Register Volume 89, Number 54 (Tuesday, March 19, 2024)]
[Proposed Rules]
[Pages 19519-19526]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-05783]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R05-OAR-2022-0369; FRL-11761-01-R5]


Air Plan Approval; Wisconsin; Milwaukee Second 10-Year 2006 24-
Hour PM2.5 Limited Maintenance Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve, under the Clean Air Act (CAA), the limited maintenance plan 
(LMP) submitted on April 8, 2022, by the Wisconsin Department of 
Natural Resources (WDNR) for the Milwaukee-Racine maintenance area 
including Milwaukee, Waukesha, and Racine counties. The plan addresses 
the second 10-year maintenance period for particulate matter with an 
aerodynamic diameter less than or equal to a nominal 2.5 micrometers 
(PM2.5). EPA is proposing to approve Wisconsin's LMP 
submission for Milwaukee-Racine because it provides for the maintenance 
of the 2006 PM2.5 national ambient air quality standard 
(NAAQS) through the end of the second 10-year portion of the 
maintenance period. In addition, EPA is initiating the process to find 
the Milwaukee-Racine PM2.5 LMP adequate for transportation 
conformity purposes.

DATES: Comments must be received on or before April 18, 2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2022-0369 at https://www.regulations.gov, or via email to 
[email protected]. For comments submitted at Regulations.gov, follow 
the online instructions for submitting comments. Once submitted, 
comments cannot be edited or removed from Regulations.gov. For either 
manner of submission, 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, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section. For the full 
EPA public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit https://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Cecilia Magos, Attainment Planning and 
Maintenance Section, Air Programs Branch (AR-18J), Environmental 
Protection Agency, Region 5, 77 West Jackson Boulevard, Chicago, 
Illinois 60604, (312) 886-7336, [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 and facility closures due to COVID-19.

SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,'' 
``us,'' or ``our'' is used, we mean EPA. This supplementary information 
section is arranged as follows:

I. Background
II. The LMP Option
III. EPA's Analysis of the State's Submittal
IV. What action is EPA taking?
V. Environmental Justice Considerations
VI. Statutory and Executive Orders Review

I. Background

A. The PM2.5 NAAQS

    PM2.5 is one of the criteria pollutants for which a 
NAAQS is established to protect human health and the environment. In 
1997, EPA established the first PM2.5 standards based on 
significant scientific evidence and health studies demonstrating the 
serious health effects associated with exposure to PM2.5. 
EPA set an annual standard of 15.0 micrograms per cubic meter ([mu]g/
m\3\) and a 24-hour (or daily) standard of 65 [mu]g/m\3\. In 2006, EPA 
strengthened the 24-hour PM2.5 NAAQS by revising it to 35 
[mu]g/m\3\ and retained the level of the annual PM2.5 
standard at 15.0 [mu]g/m\3\. Subsequently, in 2012, EPA established an 
annual primary PM2.5 NAAQS at 12 [mu]g/m\3\ and retained the 
2006 24-hour PM2.5 NAAQS at 35 [mu]g/m\3\. In 2024, EPA 
revised the annual primary PM2.5 NAAQS to 9.0 [mu]g/m\3\ and 
retained the level of the 2006 24-hour PM2.5 NAAQS at 35 
[mu]g/m\3\.

B. Regulatory Actions in Milwaukee-Racine

    On November 13, 2009 (74 FR 58688), EPA designated the Milwaukee-
Racine area as a PM2.5 nonattainment area due to measured 
violations of the 2006 PM2.5 NAAQS. On June 8, 2012, 
supplemented on May 30, 2013, WDNR submitted to EPA a request to 
redesignate the Milwaukee-Racine nonattainment area, to attainment of 
the 2006 PM2.5 NAAQS. The submission included a plan to 
provide for maintenance of the 2006 PM2.5 NAAQS in the area 
for 10 years. EPA redesignated the Milwaukee-Racine area on April 22, 
2014 (79 FR 22415),and approved the associated maintenance plan into 
the Wisconsin State Implementation Plan (SIP). The purpose of WDNR'S 
April 8, 2022, LMP submission is to fulfill the second 10-year planning 
requirement of CAA section 175A(b) to ensure PM2.5 NAAQS 
compliance through 2034.

II. The LMP Option

A. Demonstration of Maintenance Using the LMP Option

    Section 175A of the CAA sets forth the elements of a maintenance 
plan. Under section 175A, a state must submit a revision to the SIP 
that provides for maintenance of the applicable NAAQS for at least 10 
years after an area is redesignated to attainment. Section 175A also 
requires that eight years into the first maintenance period, the state 
must submit a second maintenance plan demonstrating that the area will 
continue to attain for the following 10-year period.
    EPA has published long-standing guidance for states on developing 
maintenance plans.\1\ The Calcagni memo provides that states may 
generally demonstrate maintenance by

[[Page 19520]]

either performing air quality modeling to show that the future mix of 
sources and emission rates will not cause a violation of the NAAQS or 
by showing that future emissions of a pollutant and its precursors will 
not exceed the level of emissions during a year when the area was 
attaining the NAAQS (i.e., attainment year inventory). EPA clarified in 
subsequent guidance memos that certain nonattainment 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.\2\
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    \1\ Calcagni, John, Director, Air Quality Management Division, 
EPA Office of Air Quality Planning and Standards, ``Procedures for 
Processing Requests to Redesignate Areas to Attainment,'' September 
4, 1992 (Calcagni memo).
    \2\ 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; and ``Limited Maintenance Plan Option for Moderate 
PM10 Nonattainment Areas'' (PM10 LMP Guidance) 
from Lydia Wegman, OAQPS, dated August 9, 2001. Copies of these 
guidance memoranda can be found in the docket for this proposed 
rulemaking.
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    Most recently, in October 2022, EPA released guidance extending 
this streamlined option for demonstrating maintenance under CAA section 
175A to certain PM2.5 areas, titled ``Guidance on Limited 
Maintenance Plan Option for Moderate PM2.5 Nonattainment 
Areas and PM2.5 Maintenance Areas'' (PM2.5 LMP 
Guidance).\3\
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    \3\ The guidance document developed by the Office of Air Quality 
Planning and Standards and the Office of Transportation and Air 
Quality, within the Office of Air and Radiation, titled ``Guidance 
on the Limited Maintenance Plan Option for Moderate PM2.5 
Nonattainment Areas and PM2.5 Maintenance Areas'' can be 
found at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P1015UL4.pdf.
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    EPA refers to this streamlined demonstration of maintenance as an 
LMP. EPA has interpreted CAA section 175A as permitting this option 
because CAA section 175A defines few specific content requirements for 
maintenance plans and, in EPA's experience implementing the various 
NAAQS, areas that qualify for an LMP or have approved LMPs have rarely, 
if ever, experienced subsequent violations of the NAAQS. As noted in 
the PM2.5 LMP guidance, states seeking an LMP should still 
submit the other maintenance plan elements outlined in the Calcagni 
memo, 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 an 
LMP must still submit their section 175A maintenance plan as a revision 
to their state implementation plan, with all attendant notice and 
comment procedures.
    The PM2.5 LMP Guidance, which contains requirements 
similar to those for an LMP under the PM10 LMP Guidance, 
allows states to demonstrate that areas qualify for an LMP by showing 
that, based on their recent measured air quality, they are unlikely to 
violate the NAAQS in the future.
    Specifically, the PM2.5 LMP Guidance relies on the 
critical design value (CDV) concept. The Guidance directs states to 
calculate a site-specific CDV for the monitoring site with the highest 
design value in the area, and also for all other active monitoring 
sites in the area with complete data. The Guidance states that areas 
should show that the average design value (ADV) for each monitoring 
site in the area, i.e., the average of at least the most recent 
consecutive five years of PM2.5 design values, does not 
exceed the associated CDV for each site.\4\ The CDV calculation for a 
monitoring site involves parameters including: (1) the level of the 
relevant NAAQS; (2) the co-efficient of variation of recent design 
values measured at that site; and (3) a statistical parameter 
corresponding to a 10 percent probability of exceedance, such that 
sites with historically high variability in DVs result in a lower (or 
more stringent) CDV. Evaluating if the ADV for each monitoring site in 
the area is below the CDV demonstrates that the probability of a future 
exceedance, based on the area's historical air quality and variability, 
is less than 10 percent. Per EPA's transportation conformity 
regulations, areas with LMPs must also ``demonstrate that it would be 
unreasonable to expect that such an area would experience enough motor 
vehicle emissions growth for a NAAQS violation to occur.'' \5\
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    \4\ EPA recommends that the ADV be calculated using at least 
five years of design values, each representing a three-year period, 
because this approach would rely on a more robust data set. However, 
we acknowledge that an alternative interpretation may be acceptable 
where these variables could be calculated using three years of 
design values, collectively representing five years of air quality 
data.
    \5\ 40 CFR 93.109(e).
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B. Transportation Conformity Under the LMP Option

    Transportation conformity is required by section 176(c) of the CAA. 
Under that provision, conformity to a SIP means that transportation 
activities will not cause or contribute to new air quality violations, 
worsen existing violations, or delay timely attainment of the NAAQS or 
any required interim emission reductions or other milestones in any 
area. See CAA 176(c)(1)(A) and (B). EPA's transportation conformity 
rule at 40 CFR part 93, subpart A, establishes the criteria and 
procedures to determine whether metropolitan transportation plans, 
transportation improvement programs, and federally supported highway 
and transit projects conform to the purpose of the SIP. Transportation 
conformity applies for transportation-related criteria pollutants in 
nonattainment areas and redesignated attainment areas with a CAA 
section 175A maintenance plan (i.e., maintenance areas).\6\
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    \6\ In addition to PM2.5, the criteria pollutants for 
which transportation conformity applies include ozone, carbon 
monoxide, particulate matter with an aerodynamic diameter less than 
or equal to 10 micrometers, and nitrogen dioxide. See 40 CFR 
93.102(b).
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    While qualification for the LMP option does not exempt an area from 
the need to determine conformity, in an area with an LMP, conformity 
may be demonstrated without a regional emissions analysis for the 
relevant NAAQS and pollutant (40 CFR 93.109(e)). An LMP must 
demonstrate that it is unreasonable to expect that the area would 
experience so much growth in on-road emissions during the maintenance 
period that a violation of the relevant NAAQS would occur. See 40 CFR 
93.109(e). Hence, because no such impact is expected, areas with LMPs 
are not required to do a regional emissions analysis as part of a 
transportation conformity determination. See 40 CFR 93.109(e).
    While areas with maintenance plans approved or found adequate under 
the LMP option are not required to do a regional emissions analysis 
(and are not subject to the budget test in 40 CFR 93.118), the areas 
remain subject to the other transportation conformity requirements of 
40 CFR part 93, subpart A, including fulfilling project-level 
conformity requirements and consultation requirements.
    The PM2.5 LMP Guidance notes that an LMP may be 
particularly appropriate for a second maintenance plan, as the area 
will have demonstrated attainment of the PM2.5 NAAQS for at 
least 8 years. To demonstrate that it would be unreasonable to expect 
that the area would experience enough motor vehicle growth for a NAAQS 
violation to occur, the guidance states that an LMP submission for an 
area's second maintenance plan should address the area's 
PM2.5 air quality trends and the historical and projected 
vehicle miles traveled (VMT). Further, if re-entrained road dust has 
been found to be significant for PM2.5 transportation

[[Page 19521]]

conformity purposes under 40 CFR 93.102(b)(3), the plan should include 
an on-road PM2.5 emissions analysis consistent with the 
methodology provided in Attachment B of the PM10 LMP 
Guidance, included in the appendix for the PM2.5 LMP 
Guidance, along with the discussion in the PM2.5 LMP 
Guidance itself. If the on-road PM2.5 emissions analysis is 
necessary, it would include a demonstration that for each monitoring 
site in the area, the ADV plus the expected on-road emissions growth 
estimate does not exceed the CDV.
    In addition to the proposed action, EPA is notifying the public 
that the Agency is initiating the adequacy process for the Milwaukee-
Racine LMP. See 40 CFR 93.118(e)(4). In the case of an LMP, EPA's 
adequacy review is to assess whether the demonstration required by 40 
CFR 93.109(e) is met. Any comments on the adequacy of the submitted LMP 
for the Milwaukee-Racine area should be submitted to the docket 
established for this rulemaking. If EPA approves the second 10-year 
maintenance plan as an LMP or finds the submission adequate, the 
Milwaukee-Racine maintenance area will not be required to perform 
regional emissions analyses after 2025 for the 2006 PM2.5 
NAAQS. Note that the Milwaukee area has approved motor vehicle emission 
budgets for nitrogen oxides (NOX), direct PM2.5, 
sulfur dioxide (SO2) and volatile organic compounds (VOCs) 
for the year 2025 from the first maintenance plan that must continue to 
be met in any transportation conformity determination made through the 
year 2025.\7\ In addition, project-level conformity requirements as 
well as the other transportation conformity criteria continue to apply 
with respect to the 2006 PM2.5 NAAQS for conformity 
determinations that occur through the maintenance period, i.e., through 
2034.\8\
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    \7\ See 81 FR 8656 and 79 FR 22415.
    \8\ See 40 CFR 93.102(b)(4) and Transportation Conformity 
Guidance for Areas Reaching the End of the Maintenance Period 
(October 2014, EPA-420-B-14-093).
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    We will complete the adequacy determination process either in the 
final action on this proposal or by notifying the state in writing, 
publishing a notice in the Federal Register and by posting the finding 
on EPA's adequacy web page. See 40 CFR 93.118(f).

C. General Conformity Under LMP Option

    EPA's general conformity program requirements do not distinguish 
between maintenance areas with an approved LMP and those with an 
approved ``full maintenance plan,'' which is developed and approved 
using the long-standing methods that demonstrate the area will maintain 
the NAAQS. Thus, maintenance areas with an approved LMP are subject to 
the same general conformity requirements under 40 CFR part 93, subpart 
B, as those with a ``full maintenance plan.'' Both a ``full maintenance 
plan'' and an LMP must be developed and approved per the requirements 
of CAA section 175A.

III. EPA's Analysis of the State's Submittal

A. Demonstration of Qualification for the LMP Option

    EPA redesignated the Milwaukee-Racine area from nonattainment to 
attainment of the NAAQS on April 22, 2014 (79 FR 22415). This LMP was 
developed as part of an interagency consultation process which includes 
Federal, state, and local agencies. Table 1 below shows the historical 
design values for the area since the area was redesignated in 2014.\9\ 
The 2006 PM2.5 NAAQS is attained when the 3-year average of 
the 98th percentile of 24-hour PM2.5 concentrations is equal 
to or less than 35 [micro]g/m\3\. As shown in table 1, the area has 
been measuring air quality well below the 2006 PM2.5 NAAQS 
with decreasing PM2.5 concentrations over time. The design 
values at the individual monitoring sites in the area also measure air 
quality well below the 2006 PM2.5 NAAQS as shown in table 2.
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    \9\ See https://www.epa.gov/air-trends/air-quality-design-values#map.

 Table 1--Design Values (DV) ([micro]g/m\3\) for the 2006 PM2.5 NAAQS in
       the Milwaukee-Racine Area Since Redesignation to Attainment
                               [2013-2022]
------------------------------------------------------------------------
                                                       Milwaukee-Racine
                 Design value period                  PM2.5 design value
 
------------------------------------------------------------------------
2011-2013...........................................                  27
2012-2014...........................................                  27
2013-2015...........................................                  25
2014-2016...........................................                  24
2015-2017...........................................                  22
2016-2018...........................................                  21
2017-2019...........................................                  22
2018-2020...........................................                  22
2019-2021...........................................                  23
2020-2022...........................................                  24
------------------------------------------------------------------------


                  Table 2--Design Values (DV) ([micro]g/m\3\) for the 2006 PM2.5 NAAQS at Monitoring Sites in the Milwaukee-Racine Area
                                                                       [2014-2022]
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        AQS site ID                Site name                 County          2014-2016  2015-2017  2016-2018  2017-2019  2018-2020  2019-2021  2020-2022
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550790010.................  16th St. Health Center.  Milwaukee.............        24         22         20         21         21         23         24
550790026.................  Milw SER \c\...........  Milwaukee.............        20         19         20         21         21   .........  .........
550790056.................  College Ave NR.........  Milwaukee.............  .........  .........  .........        22         21         22         22
550790058.................  College Ave P&R \b\....  Milwaukee.............        23         20         19       * 19   .........  .........  .........
550790099.................  Milw Fire Dept \a\.....  Milwaukee.............      * 23       * 23   .........  .........  .........  .........  .........

[[Page 19522]]

 
551330027.................  Cleveland Ave..........  Waukesha..............        22         21         21         22         22         23         23
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* 24-hr data did not meet completeness criteria. Associated DV's are thus invalid.
\a\ Milwaukee-Fire Dept. (550790099) shut down in 2017 and was replaced by Milwaukee-College Ave NR (550790056).
\b\ Milwaukee-College Ave P&R (550790058) was shut down in October 2019.
\c\ Milwaukee SER (550790026) was shut down in April 2021.

    We propose to find that the Milwaukee-Racine area meets the 
critical design value demonstration for a LMP. As noted above, the 
parameters of the CDV calculation, outlined in the PM2.5 LMP 
Guidance, include the level of the relevant NAAQS, the co-efficient of 
variation of recent design values, and a statistical parameter 
corresponding to a 10 percent probability of future violation. The CDV 
demonstration is designed such that if a site's ADV is lower than the 
site's CDV, the probability of a future violation of the NAAQS is less 
than 10 percent.\10\ The eligibility calculation equations for the CDV 
demonstration are shown in Table 3. Table 4 below contains the CDV and 
ADV for each monitor in the Milwaukee-Racine area, including the 
College Ave NR (monitor ID 550790056). EPA reviewed the data and 
methodology provided by the state and finds that each monitor's 5-year 
average design value is well below the corresponding site-specific 
CDV.\11\
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    \10\ See the ``Example Site Calculation'', page 7 of the October 
2022 PM2.5 LMP guidance (https://www.epa.gov/system/files/documents/2022-10/420b22044.pdf).
    \11\ Two monitors in the Milwaukee-Racine maintenance area were 
not included in the analysis below. One of these monitors (Monitor 
ID 550790099) had invalid DV's in 2016 and 2017 before being shut 
down, and one was shut down in 2019 (Monitor ID 550790058) and has 
valid DV's only through 2018.

               Table 3--Eligibility Calculation Equations
------------------------------------------------------------------------
 
------------------------------------------------------------------------
Critical Design Value..................  CDV = NAAQS/(1+(tC x CV)).
Coefficient of Variation...............  CV = [sigma]/ADV.
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NAAQS = applicable standard (PM2.5 is 35 [micro]g/m\3\).
tC = critical t-value.
[sigma] = standard deviation of design values.


      Table 4--Qualification of Monitors for LMP in the Milwaukee-Racine Maintenance Area in [micro]g/m\3\
                                                   [2016-2020]
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                                                        ADV (2016-      CDV (2016-
              Site name                   Monitor          2020)           2020)           Qualify for LMP?
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16th St. Health Center..............       550790010            21.6            31.6  Yes.
Milw SER............................       550790026            20.2            32.9  Yes.
College Ave NR......................   \1\ 550790056           21.75            33.8  Yes.
Cleveland Ave.......................       551330027            21.6            33.7  Yes.
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\1\ The ADV and CDV for this monitor were calculated using valid DV data from 2019 through 2022 due to monitor
  installation occurring in 2017 for the 2019 DV period. The monitor was installed to replace the Milwaukee-Fire
  Dept. monitor (Monitor ID 550790099) that was shut down in 2017 after two design value periods that did not
  meet data completeness criteria.

    We also propose to find that Wisconsin has adequately demonstrated 
that it is unlikely there will be an increase in motor vehicle 
emissions growth sufficient to cause a NAAQS violation in the 
Milwaukee-Racine maintenance area. In the 2022 PM2.5 LMP 
Guidance, which was released after Wisconsin submitted its SIP 
revisions, EPA clarified that an area submitting the second 10-year 
maintenance plan may be eligible for the LMP option as long as 
monitored air quality data and VMT trends support the LMP option. The 
state included both air quality data and VMT trend data of the 
maintenance area to satisfy transportation conformity regulations under 
an LMP option. The VMT projections considered by Wisconsin were based 
on transportation models provided by both the Wisconsin Department of 
Transportation (WDOT) and Southeastern Wisconsin Regional Planning 
Commission (SEWRPC). WDOT maintains a statewide travel demand model 
that projects average weekday VMT for each of the 72 counties in 
Wisconsin. WDOT provided modeled VMT for the years 2017 and 2050 for 
the Milwaukee-Racine area. WDNR linearly interpolated VMT results 
between the 2017 and 2050 values to obtain values for 2034, resulting 
in a 10.4 percent VMT growth percentage for 2017 to 2034. SEWRPC also 
has their own travel demand model that covers their seven-county 
region, which includes the Milwaukee-Racine maintenance area. Wisconsin 
also included in their submission the SEWRPC modeled projections under 
a high economic growth scenario from 2017 to 2035, showing a 13.6 
percent VMT growth percentage. Ultimately, Wisconsin relied upon the 
highest VMT growth calculated from the different transportation models, 
at a VMT growth of 13.6 percent. A LMP would have to demonstrate that 
it would be unreasonable to expect that such an area would experience 
enough motor vehicle emissions growth for a NAAQS violation to occur. 
See 40 CFR 93.109(e).

[[Page 19523]]

EPA is proposing to conclude that the higher VMT growth rate of 13.6 
percent between 2017 and 2035 would not cause an exceedance of the CDV 
at the monitors listed in table 4 and therefore, that the Milwaukee-
Racine maintenance area would qualify for the LMP option.\12\ 
Wisconsin's submission included an on-road PM2.5 emissions 
analysis consistent with the methodology provided in the 2001 
PM10 LMP Guidance, because at the time of the state's 
submission, the PM2.5 LMP Guidance had not yet been issued 
by EPA. This specific on-road PM2.5 analysis is most 
critical for areas where re-entrained road dust has been identified as 
a significant contributor to PM2.5 concentrations. Re-
entrained road dust was not determined to be a significant contributor 
to PM2.5 concentrations in the Milwaukee-Racine area. EPA 
evaluated the state's analysis as part of its consideration of whether 
increases in VMT will lead to future exceedances of the 2006 
PM2.5 NAAQS. Based on that evaluation, EPA is proposing to 
conclude that the results of the analysis provide further evidence that 
they will not. EPA is proposing to approve the LMP for the Milwaukee-
Racine area. Per 40 CFR 93.109(e) an area is not required to satisfy 
the regional emissions analysis for Sec.  93.118 and/or Sec.  93.119 
for a given pollutant and NAAQS, in this instance the 2006 
PM2.5 NAAQS. However, the first 10-year maintenance plan 
included motor vehicle emissions budgets for 2025. Therefore, if 2025 
is within the timeframe of any transportation plan or transportation 
improvement program (TIP) and transportation conformity is determined 
for that plan or TIP, a regional emissions analysis is required for 
2025.
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    \12\ See ``EPA_analysis_Milwaukee PM2.5_LMP.xlsx'' 
provided in the docket of this rulemaking.
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    In addition to the VMT trends, the air quality trends in the area 
provided in the state's submission (Table 1) also support the LMP 
option. From the time the area started attaining the NAAQS (2014) 
through 2020, ambient PM2.5 concentrations have decreased 
substantially. There has been a 19.5 percent decrease in the annual 
98th percentile PM2.5 concentrations in the Milwaukee-Racine 
area during this time period.\13\ Air quality trends from 2021 and 2022 
in table 1 also show ambient PM2.5 concentrations well below 
the 2006 PM2.5 NAAQS.
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    \13\ Where available, 2020 and 2014 monitor data was used at 
each monitoring site to compare the percent decrease, averaged 
across the area. Where 2020 data was not available, the closest year 
prior to 2020 with available data was used, and no earlier than 
2018. See ``EPA_analysis_Milwaukee PM2.5_LMP.xlsx'' 
provided in the docket of this rulemaking.
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    The PM2.5 LMP guidance further notes that, to the extent 
that the air agency is submitting a second 10-year maintenance plan for 
PM2.5, a record showing that the area design value is lower 
than the CDV, coupled with air quality data demonstrating the area has 
already been maintaining the NAAQS for at least 8 years, provides EPA 
with further confidence that the area will continue to maintain the 
relevant PM2.5 standard. Given the current PM2.5 
design values in the area and the demonstrated downward trend in 
PM2.5 concentrations over the last ten years, and the 
state's analysis of VMT trends discussed above, we propose to find that 
the state has adequately demonstrated that, consistent with 40 CFR 
93.109(e) and the PM2.5 LMP Guidance, it would be 
unreasonable to expect that the area will experience a growth in motor 
vehicle emissions sufficient to cause a violation of the 2006 
PM2.5 NAAQS. EPA therefore proposes to find that the 
Milwaukee-Racine 2006 PM2.5 maintenance area meets the 
qualification criteria set forth in the PM2.5 LMP Guidance.
    The following is a summary of EPA's interpretation of the section 
175A requirements and EPA's evaluation of how each requirement is met. 
Under the LMP option, the state will be expected to determine on a 
regular basis that the criteria are still being met. If the state 
determines that the LMP criteria are not being met, it must take action 
to reduce PM2.5 concentrations enough to requalify. One 
possible approach the state could take is to implement the contingency 
measures contained in its maintenance plan. See Section 6 of the 
state's submittal, placed in the docket for this action, for a 
description of the contingency measures. If the attempt to reduce 
PM2.5 concentrations fails, or if it succeeds but in future 
years it becomes necessary again to address increasing PM2.5 
concentrations in an area, the area will no longer qualify for the LMP 
option.

B. Attainment Inventory

    As noted above, states that qualify for an LMP must still meet the 
other elements of a maintenance plan, as articulated in the Calcagni 
Memo. This includes an attainment year emissions inventory.
    WDNR's Milwaukee-Racine PM2.5 LMP submission includes an 
emissions inventory, with a base year of 2017. This inventory was 
prepared as part of the 2017 National Emissions Inventory (NEI),\14\ 
Version 2, under EPA's Air Emissions Reporting Rule (73 FR 76539, 
December 17, 2008). The 2017 base year represents the most recent 
emissions inventory data available when the state prepared the 
submissions, is representative of the level of emissions during the 
time that the area shows monitored attainment of the NAAQS and is 
consistent with the data used to determine applicability of the LMP 
option (i.e., having no violations of the NAAQS during the 5-year 
period used to calculate the design value). Table 5 shows the 2017 
emissions of the Milwaukee-Racine maintenance area in tons per day 
included in the state's submission. EPA also considered emissions from 
the 2020 NEI as shown in table 6, as more recent emissions data was 
subsequently available since Wisconsin's submission. The 2017 NEI 
emissions from table 5 show slightly overall higher emissions of 
certain pollutants compared to the 2020 NEI emissions from table 6 in 
the Milwaukee-Racine maintenance area. Some of the differences may be 
attributed to changes and improvements in the process and methods used 
for estimating emissions while creating the 2020 NEI compared to 2017 
methods. Key process changes for the 2020 cycle includes changes in 
pollutant, source classification codes, and North American Industry 
Classification System codes, refined quality assurance checks and 
features.\15\ In summary, the 2020 NEI updated emission methods pertain 
to nonpoint solvent utilization, nonpoint agricultural silage, nonpoint 
asphalt paving, improved VOC and PM2.5 speciation models, 
improvements to residential wood combustion emission factors and 
speciation, and biogenic model updates.
---------------------------------------------------------------------------

    \14\ See https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data.
    \15\ See 2020 National Emissions Inventory Technical Support 
Document: Overview (March 2023).

[[Page 19524]]



                Table 5--2017 Emissions (Tons per Day) for the Milwaukee-Racine Maintenance Area
----------------------------------------------------------------------------------------------------------------
              Sector                  PM2.5        SO2         NOX         VOC         NH3      Total emissions
----------------------------------------------------------------------------------------------------------------
Milwaukee County Total...........        6.92        2.86       42.84       43.75        3.36              99.73
    Point........................        0.73        2.30       14.30        4.11        1.74              23.18
    Nonpoint.....................        5.22        0.47       10.98       27.62        1.10              45.39
    Onroad.......................        0.60        0.09       14.24        8.39        0.52              23.84
    Nonroad......................        0.36        0.01        3.31        3.63        0.01               7.32
    Event........................        0.00        0.00        0.00        0.00        0.00               0.00
Waukesha County Total............        7.35        0.43       19.85       32.37        1.51              61.51
    Point........................        0.09        0.00        0.26        2.14        0.01               2.50
    Nonpoint.....................        6.50        0.37        8.03       21.83        1.19              37.92
    Onroad.......................        0.32        0.05        8.13        4.80        0.29              13.59
    Nonroad......................        0.38        0.01        3.42        3.45        0.01               7.27
    Event........................        0.06        0.01        0.02        0.15        0.01               0.25
Racine County Total..............        3.52        0.64        9.03       13.74        0.98              27.91
    Point........................        0.31        0.49        0.85        1.31        0.00               2.96
    Nonpoint.....................        2.97        0.13        3.59        9.57        0.86              17.12
    Onroad.......................        0.13        0.02        3.31        1.97        0.12               5.55
    Nonroad......................        0.11        0.00        1.28        0.88        0.00               2.27
    Event........................        0.00        0.00        0.00        0.00        0.00               0.00
                                  ------------------------------------------------------------------------------
        Milwaukee-Racine                17.79        3.94       71.72       89.86        5.85             189.16
         Maintenance Area Total..
----------------------------------------------------------------------------------------------------------------


              Table 6--2020 NEI Emissions (Tons per Day) for the Milwaukee-Racine Maintenance Area
----------------------------------------------------------------------------------------------------------------
                                                                                                         Total
                 Sector                      PM2.5        SO2         NOX         VOC         NH3      emissions
----------------------------------------------------------------------------------------------------------------
Milwaukee County Total..................        8.52        2.20       34.29       44.89        2.20       92.09
    Point...............................        0.92        1.89       12.21        3.63        0.09       18.74
    Nonpoint............................        6.89        0.26        9.16       32.53        1.66       50.50
    Onroad..............................        0.39        0.05       10.08        5.23        0.44       16.19
    Nonroad.............................        0.32        0.00        2.84        3.49        0.01        6.67
Waukesha County Total...................        8.73        0.37       15.10       34.41        2.34       60.95
    Point...............................        0.12        0.04        0.48        1.85        0.01        2.50
    Nonpoint............................        8.08        0.29        6.36       26.51        2.07       43.32
    Onroad..............................        0.20        0.03        5.38        2.76        0.26        8.63
    Nonroad.............................        0.33        0.00        2.88        3.29        0.01        6.51
Racine County Total.....................        4.07        0.60        7.21       17.48        1.31       30.67
    Point...............................        0.38        0.48        0.91        1.08        0.00        2.85
    Nonpoint............................        3.52        0.11        2.91       14.37        1.20       22.10
    Onroad..............................        0.09        0.01        2.34        1.22        0.11        3.77
    Nonroad.............................        0.09        0.00        1.05        0.81        0.00        1.96
                                         -----------------------------------------------------------------------
        Milwaukee-Racine Maintenance           21.32        3.17       56.59       96.78        5.86      183.71
         Area Total.....................
----------------------------------------------------------------------------------------------------------------

C. Air Quality Monitoring Network

    Once an area is redesignated, the state must continue to operate an 
appropriate air monitoring network in accordance with 40 CFR part 58 to 
verify the attainment status of the area. WDNR continues to operate a 
PM2.5 monitoring network sited and maintained in accordance 
with Federal siting and design criteria in 40 CFR part 58, and in 
consultation with EPA Region 5. WDNR submitted the 2022-2023 Annual 
Monitoring Network Plan,\16\ which EPA approved on November 7, 
2022.\17\
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    \16\ See WDNR's Air Monitoring website containing the annual 
network plans at https://dnr.wisconsin.gov/topic/AirQuality/Monitor.html.
    \17\ See EPA'S Approval Letter for WDNR'S 2022-2023 Annual 
Network Monitoring Plan in the docket of this rulemaking.
---------------------------------------------------------------------------

    In its submission, WDNR details the four existing EPA-approved 
PM2.5 monitoring sites in the Milwaukee-Racine maintenance 
area. Consistent with the EPA-approved WDNR annual network plan, in 
order to meet the EPA requirements at appendix D of 40 CFR part 58, 
WDNR is required to maintain a minimum of two monitors in the Milwaukee 
Metropolitan Statistical Area, including Milwaukee, Waukesha, and West 
Allis counties based on population criteria. EPA proposed to find that 
the WDNR annual Air Monitoring Network Plan is adequate to verify the 
continued attainment of the 2006 PM2.5 NAAQS in the 
Milwaukee-Racine area.

D. Verification of Continued Attainment

    The level of the 2006 PM2.5 NAAQS is 35 [micro]g/m\3\. 
The NAAQS is attained when the 3-year average of the 98th percentile of 
24-hour PM2.5 concentrations is equal to or less than 35 
[micro]g/m\3\ (40 CFR 50.6). As stated previously, WDNR commits to 
continue to operate a monitoring network in accordance with 40 CFR part 
58. In addition, WDNR commits to verifying continued attainment of the 
PM2.5 standard through the maintenance plan period with the 
operation of an appropriate PM2.5 monitoring network. In 
developing the second 10-year maintenance plan, WDNR evaluated the most 
recent three years of complete, quality-assured data for the Milwaukee-
Racine maintenance area at the time the submissions were made (2018 
through 2020) to verify continued attainment of the standard. Air 
quality data from 2021, and air quality data from 2022 confirm 
continued attainment of the standard as described in Table 1.

[[Page 19525]]

E. Contingency Provisions

    CAA section 175A(d) states that a maintenance plan must include 
contingency provisions, as necessary, to ensure prompt correction of 
any violation of the relevant NAAQS which may occur after redesignation 
of the area to attainment. As explained in the Calcagni Memo, these 
contingency provisions are an enforceable part of the federally 
approved SIP. The maintenance plan should clearly identify the events 
that would ``trigger'' the adoption and implementation of a contingency 
provision, the contingency provision(s) that would be adopted and 
implemented, and the schedule indicating the time frame by which the 
state would adopt and implement the provision(s). The Calcagni Memo 
states that EPA will determine the adequacy of a contingency plan on a 
case-by-case basis. At a minimum, the plan must require that the state 
implement all measures contained in the CAA part D nonattainment plan 
for the area prior to redesignation.
    In the Milwaukee-Racine PM2.5 LMP submission, WDNR 
included maintenance plan contingency provisions to ensure the area 
will continue to meet the 2006 PM2.5 NAAQS. The submission 
describes a process and a timeline to identify, evaluate, and select 
the appropriate contingency measure(s) from a list of measures in the 
event of a violation of the PM2.5 NAAQS. Wisconsin commits 
to two levels of contingency response that may be implemented to reduce 
emissions, a ``warning level response'' and an ``action level 
response'' that are initially prompted if the 98th percentile 24-hour 
PM2.5 concentration at any monitoring site in the Milwaukee-
Racine maintenance area shows a renewed exceedance or violation, 
respectively above the 2006 PM2.5 NAAQS. A warning level 
response will initiate a study no later than 6 months following data 
certification to assess whether actual emissions have deviated 
significantly from the emission projections in the maintenance plan, 
evaluate the sectors responsible for any increases in precursor 
emissions, evaluate the sectors and states responsible for any 
increases in precursor emissions transported to the maintenance area, 
and determine if unusual meteorological conditions or exceptional 
events during the period led to high PM2.5 concentrations. 
In the event an action level response is prompted, a study will be 
initiated no later than 6 months following data certification with the 
following factors: level, distribution, and severity of ambient 
PM2.5 concentrations; weather patterns contributing to 
PM2.5 levels; potential contributing emissions sources; 
geographic applicability of possible contingency measures; emissions 
trends including impact of existing and forthcoming control measures 
not yet implemented; current and recently identified control 
technologies; and air quality contributions from outside the 
maintenance area. See Section 6 of the state's LMP submission in the 
docket for this action for further description of the contingent 
response to triggering events. The submission describes the 
consultation from interested and affected parties in the area that 
would occur after a violation in order to determine the control 
measures necessary to assure attainment of the NAAQS that can be 
implemented within 18 months from the close of the calendar year that 
prompted the violation. EPA proposes to find that the contingency 
provisions in the PM2.5 LMP for the Milwaukee-Racine 2006 
PM2.5 maintenance area meet the requirements of section 
175A(d) of the CAA.

IV. What action is EPA taking?

    EPA is proposing to approve the second 10-year PM2.5 LMP 
for the Milwaukee-Racine 2006 PM2.5 maintenance area 
submitted by WDNR. EPA's review of the air quality data for the 
maintenance area indicates that the area continues to show attainment 
well below the level of the 2006 PM2.5 NAAQS and meets all 
the LMP qualifying criteria as described in this action. If finalized, 
EPA's approval of this LMP will satisfy the CAA section 175A 
requirements for the second 10-year period for the Milwaukee-Racine 
2006 PM2.5 maintenance area. EPA is also initiating the 
process to determine if the LMP is adequate for transportation 
conformity purposes. As discussed in section II.B, EPA may complete 
that process either in its final action on the LMP or through a 
separate process provided for in the transportation conformity 
regulations. See 40 CFR 93.118(f).

V. Environmental Justice Considerations

    To identify environmental burdens and potentially susceptible 
populations in the Milwaukee-Racine maintenance area, EPA performed a 
screening-level analysis using EPA's environmental justice (EJ) 
screening and mapping tool (EJSCREEN).\18\ The results of EPA's 
screening analysis are being provided for informational and 
transparency purposes, and EPA did not rely on these findings in its 
action on Wisconsin's submissions. EPA utilized the EJSCREEN tool to 
evaluate environmental and demographic indicators within each county 
contained in the Milwaukee-Racine maintenance area including Milwaukee, 
Racine, and Waukesha counties. Each of the tool output reports are 
contained in the docket for this action. EPA's screening-level analysis 
indicates that communities affected by this action score below the 
national average for the EJSCREEN ``Demographic Index'', which is the 
average of an area's percent minority and percent low-income 
populations, i.e., the two demographic indicators explicitly named in 
Executive Order 12898 in Waukesha and Racine counties, and the 
demographic index is nine percent higher than the national average. 
Additionally, the results indicate that Racine and Waukesha counties 
score below the 80th percentile (in comparison to the Nation as a 
whole) in the twelve EJ Indices established by EPA, which include a 
combination of environmental and demographic information. Milwaukee 
county is above the 80th percentile for the Traffic Proximity, Lead 
Paint, and Hazardous Waste Proximity EJ indices.\19\
---------------------------------------------------------------------------

    \18\ See https://www.epa.gov/ejscreen.
    \19\ See EPA's EJSCREEN Technical Documentation, available at 
https://gaftp.epa.gov/EJSCREEN/2015/EJSCREEN_Technical_Document_20150505.pdf for more information on 
these select indices.
---------------------------------------------------------------------------

    This proposed action would approve the 2nd 10-year maintenance plan 
as an LMP submitted by Wisconsin for the Milwaukee-Racine area. We 
expect that this action, which would, among other things, find that the 
state has adequately provided for maintenance of the NAAQS and approve 
the state's contingency plan to address any potential violations of the 
NAAQS in the future, will be generally neutral or have a positive 
contribution to reduced environmental and health impacts on all 
populations in the Milwaukee-Racine area, including people of color and 
low-income populations. At a minimum, this action would not worsen any 
existing air quality and is expected to ensure the area is meeting 
requirements to maintain the air quality standards. Further, there is 
no information in the record indicating that this action is expected to 
have disproportionately high or adverse human health or environmental 
effects on a particular group of people.

[[Page 19526]]

VI. Statutory and Executive Orders 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 approves state law as meeting Federal requirements and 
does not impose additional requirements beyond those imposed by state 
law. For that reason, this action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 14094 (88 FR 21879, April 11, 2023);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not subject to Executive Order 13045 (62 FR 19885, 
April 23, 1997) because it approves a state program;
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001); and
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act.
    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 rulemaking 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 performed an environmental 
justice analysis, as is described above in section V. titled, 
``Environmental Justice Considerations.'' The analysis was done for the 
purpose of providing additional context and information about this 
rulemaking to the public, not as a basis of the action. Due to the 
nature of the action being taken here, this action is expected to have 
a neutral to positive impact on the air quality of the affected area. 
In addition, there is no information in the record upon which this 
decision is based inconsistent with the stated goal of E.O. 12898 of 
achieving environmental justice for people of color, low-income 
populations, and Indigenous peoples.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Particulate matter, Reporting 
and recordkeeping requirements.

    Dated: March 13, 2024.
Debra Shore,
Regional Administrator, Region 5.
[FR Doc. 2024-05783 Filed 3-18-24; 8:45 am]
BILLING CODE 6560-50-P