Proposed Rule2025-22607
Air Plan Approval; Michigan; Moderate Attainment Plan Elements for the Allegan County, Berrien County, and Muskegon County Areas for the 2015 Ozone Standard
Primary source
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Published
December 11, 2025
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to approve revisions to the Michigan State Implementation Plan (SIP) as meeting the reasonable further progress (RFP) requirements of the Clean Air Act (CAA) for the Allegan County (partial county), Berrien County, and Muskegon County (partial county) Moderate nonattainment areas for the 2015 ozone national ambient air quality standard (NAAQS). EPA is also proposing to approve updated 2017 base year emissions inventories and is initiating the adequacy process and proposing approval of the 2023 motor vehicle emissions budgets (budgets) associated with the Allegan County, Berrien County, and Muskegon County Moderate ozone nonattainment RFP demonstrations. EPA is proposing to approve these portions of the State's SIP submission pursuant to section 110 and part D of the CAA, and EPA's regulations.
Full Text
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<title>Federal Register, Volume 90 Issue 236 (Thursday, December 11, 2025)</title>
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[Federal Register Volume 90, Number 236 (Thursday, December 11, 2025)]
[Proposed Rules]
[Pages 57403-57409]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-22607]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R05-OAR-2023-0515; EPA-R05-OAR-2023-0516; EPA-R05-OAR-2023-0517;
FRL-12810-01-R5]
Air Plan Approval; Michigan; Moderate Attainment Plan Elements
for the Allegan County, Berrien County, and Muskegon County Areas for
the 2015 Ozone Standard
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve revisions to the Michigan State Implementation Plan (SIP) as
meeting the reasonable further progress (RFP) requirements of the Clean
Air Act (CAA) for the Allegan County (partial county), Berrien County,
and Muskegon County (partial county) Moderate nonattainment areas for
the 2015 ozone national ambient air quality standard (NAAQS). EPA is
also proposing to approve updated 2017 base year emissions inventories
and is initiating the adequacy process and proposing approval of the
2023 motor vehicle emissions budgets (budgets) associated with the
Allegan County, Berrien County, and Muskegon County Moderate ozone
nonattainment RFP demonstrations. EPA is proposing to approve these
portions of the State's SIP submission pursuant to section 110 and part
D of the CAA, and EPA's regulations.
DATES: Comments must be received on or before January 12, 2026.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2023-0515, EPA-R05-OAR-2023-0516, or EPA-R05-OAR-2023-0517 at
<a href="https://www.regulations.gov">https://www.regulations.gov</a>, or via email to <a href="/cdn-cgi/l/email-protection#8aebf8f8eba4f9ebf8ebe2caeffaeba4ede5fc"><span class="__cf_email__" data-cfemail="80e1f2f2e1aef3e1f2e1e8c0e5f0e1aee7eff6">[email protected]</span></a>. For
comments submitted at <a href="http://Regulations.gov">Regulations.gov</a>, follow the online instructions
for submitting comments. Once submitted, comments cannot be edited or
removed from the docket. EPA may publish any comment received to its
public docket. Do not submit to EPA's docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> any information you consider to be Confidential
Business Information (CBI), Proprietary Business Information (PBI), or
other information whose disclosure is restricted by statute. Multimedia
submissions (audio, video, etc.) must be accompanied by a written
comment. The written comment is considered the official comment and
should include discussion of all points you wish to make. EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e. on the web, cloud, or other file sharing
system). For additional submission methods, please contact the person
identified in the FOR FURTHER INFORMATION CONTACT section. For the full
EPA public comment policy, information about CBI, PBI, or multimedia
submissions, and general guidance on making effective comments, please
visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
FOR FURTHER INFORMATION CONTACT: Kathleen D'Agostino, Air and Radiation
Division (AR-18J), Environmental Protection Agency, Region 5, 77 West
Jackson Boulevard, Chicago, Illinois 60604, (312) 886-1767,
<a href="/cdn-cgi/l/email-protection#8ce8edebe3fff8e5e2e3a2e7edf8e4e0e9e9e2cce9fceda2ebe3fa"><span class="__cf_email__" data-cfemail="1b7f7a7c74686f72757435707a6f73777e7e755b7e6b7a357c746d">[email protected]</span></a>. The EPA Region 5 office is open from 8:30
a.m. to 4:30 p.m., Monday through Friday, excluding Federal holidays.
SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,''
``us,'' or ``our'' is used, we mean EPA.
I. Background
On December 28, 2015, EPA promulgated a revised 8-hour ozone NAAQS
of 0.070 parts per million (ppm).\1\ Promulgation of a revised NAAQS
triggers a requirement for EPA to designate all areas of the country as
nonattainment, attainment, or unclassifiable for the NAAQS. For the
ozone NAAQS, this also involves classifying any nonattainment areas at
the time of designation.\2\ Ozone nonattainment areas are classified
based on the severity of their ozone levels as
[[Page 57404]]
determined based on the area's ``design value,'' which represents air
quality in the area for the most recent 3 years. The classifications
for ozone nonattainment areas are Marginal, Moderate, Serious, Severe,
and Extreme.\3\
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\1\ 80 FR 65292, October 26, 2015, codified at 40 CFR 50.19.
\2\ CAA sections 107(d)(1) and 181(a)(1).
\3\ CAA section 181(a)(1).
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Areas that EPA designates nonattainment for the ozone NAAQS are
subject to the general nonattainment area planning requirements of CAA
section 172 and the ozone-specific planning requirements of CAA section
182. Ozone nonattainment areas in the lower classification levels have
fewer and/or less stringent mandatory air quality planning and control
requirements than those in higher classifications. In EPA's December 6,
2018 (83 FR 62998), rule, ``Implementation of the 2015 National Ambient
Air Quality Standards for Ozone: Nonattainment Area State
Implementation Plan Requirements,'' known as the ``SIP Requirements
Rule,'' EPA set forth nonattainment area requirements for the 2015
ozone NAAQS. These requirements are codified at 40 CFR part 51 subpart
CC. For Marginal areas, a State is required to submit a baseline
emissions inventory, adopt provisions into the SIP requiring emissions
statements from stationary sources, and implement a nonattainment new
source review program for the relevant ozone NAAQS.\4\ For Moderate
areas, a State needs to comply with the Marginal area requirements,
plus additional Moderate area requirements, including the requirement
to submit a modeled demonstration that the area will attain the NAAQS
as expeditiously as practicable but no later than 6 years after
designation, the requirement to submit an RFP plan, the requirement to
adopt and implement certain emissions controls, such as Reasonably
Available Control Technology (RACT) and motor vehicle inspection and
maintenance programs, and the requirement for greater emissions offsets
for new or modified major stationary sources under the State's
nonattainment new source review program.\5\
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\4\ CAA section 182(a).
\5\ CAA section 182(b).
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Effective August 3, 2018, EPA designated the Allegan County
(partial county), Berrien County, and Muskegon County (partial county)
areas as Marginal nonattainment areas for the 2015 ozone NAAQS.\6\ The
Allegan County area includes Casco Township, Cheshire Township, the
City of Douglas, the City of Holland, the City of Saugatuck, Clyde
Township, Fillmore Township, Ganges Township, Heath Township, Laketown
Township, Lee Township, Manilus Township, Overisel Township, Saugatuck
Township, and Valley Township. The Muskegon County area includes Blue
Lake Township, the City of Montague, the City of Muskegon, the City of
Muskegon Heights, the City of North Muskegon, the City of Roosevelt
Park, the City of Whitehall, Dalton Township, (incl. the Village of
Lakewood Club), Fruitland Township, Fruitport Township (incl. the
Village of Fruitport), Laketon Township, Montague Township, Muskegon
Township, Norton Shores Township, White River Township, and Whitehall
Township.
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\6\ 83 FR 25776, June 4, 2018.
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On October 7, 2022 (87 FR 60897), pursuant to section 181(b)(2) of
the CAA, EPA determined that the Allegan County, Berrien County and
Muskegon County areas failed to attain the 2015 ozone NAAQS by the
August 3, 2021, Marginal area attainment deadline and thus reclassified
the areas from Marginal to Moderate nonattainment. In that action, EPA
established January 1, 2023, as the due date for the State to submit
all Moderate area nonattainment plan SIP requirements applicable to
newly reclassified areas.
II. Evaluation of Michigan's Submittal
The Michigan Department of Environment, Great Lakes, and Energy
(EGLE) submitted a SIP revision on October 16, 2023, to address
Moderate area requirements for the Allegan County, Berrien County and
Muskegon County areas under the 2015 ozone NAAQS. The submittal
contained a number of nonattainment plan elements, including an updated
2017 base year emissions inventory for volatile organic compounds (VOC)
and oxides of nitrogen (NO<INF>X</INF>) and a 15% RFP plan with 2023
VOC and NO<INF>X</INF> motor vehicle emissions budgets. The submission
also included an attainment demonstration, a reasonably available
control measures demonstration, and contingency measures, which are not
being addressed in this action.
A. 2017 Base Year Emissions Inventory
1. Background
CAA sections 172(c)(3) and 182(a)(1), 42 U.S.C. 7502(c)(3) and
7511a(a)(1), require States to develop and submit, as SIP revisions,
comprehensive, accurate, and complete emissions inventories for all
areas designated as nonattainment for the ozone NAAQS. This requirement
is codified at 40 CFR 51.1315, and the term ``base year inventory'' is
defined at 51.1300(p). For ozone, the base year inventory is an
estimation of actual emissions of VOC and NO<INF>X</INF> from all
sources within the boundaries of the nonattainment area.
The regulation at 40 CFR 51.1315(a) requires that the inventory
year be selected consistent with the baseline year for the RFP plan as
required by 40 CFR 51.1310(b), which states that the baseline emissions
inventory shall be the emissions inventory for the most recent calendar
year for which a complete triennial inventory is required to be
submitted to EPA under the provisions of subpart A of 40 CFR part 51,
Air Emissions Reporting Requirements, 40 CFR 51.1 through 50. For areas
designated as nonattainment in 2018, the most recent triennial
inventory year conducted for the National Emissions Inventory (NEI)
pursuant to the Air Emissions Reporting Requirements (AERR) rule is
2017.\7\
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\7\ December 6, 2018, 83 FR 62998, 63005.
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Further, 40 CFR 51.1315(c) requires emissions values included in
the base year inventory to be actual ozone season day emissions as
defined by 40 CFR 51.1300(q), which states: Ozone season day emissions
means an average day's emissions for a typical ozone season work
weekday. The State shall select, subject to EPA approval, the
particular month(s) in the ozone season and the day(s) in the work week
to be represented, considering the conditions assumed in the
development of RFP plans and/or emissions budgets for transportation
conformity.
On December 18, 2020, EGLE submitted a SIP revision addressing the
emissions inventory requirement of CAA section 182(a)(1). EPA approved
Michigan's 2017 base year emissions inventories for the Allegan County,
Berrien County, and Muskegon County areas on January 18, 2023 (88 FR
2834).
2. Michigan's Emission Inventory Submittal
As part of Michigan's Moderate SIP submission, EGLE updated the
2017 base year emissions inventories to incorporate improved emissions
estimates where available. In Michigan's original base year emissions
inventory submittal, EGLE used the 2016v1 modeling platform to generate
emissions data for the point and nonpoint sectors and MOVES2014 to
generate emissions data for the onroad and nonroad sectors. EGLE
updated the 2017 base year emissions inventories for the Allegan
County, Berrien County, and Muskegon County areas using the 2016v2
modeling platform for point and nonpoint sectors and MOVES3 \8\ for
nonroad and on-road
[[Page 57405]]
sectors. EGLE did not update biogenic emissions estimates.
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\8\ MOVES3 was the most current mobile model available at the
time EGLE was developing Moderate SIPs for the Allegan County,
Berrien County, and Muskegon County areas.
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EGLE converted annual point and nonpoint values to tons/day
following the same procedure as was used when preparing the original
2017 base year emissions inventories. EGLE extracted data from the
2016v2 modeling platform to calculate the ratio of July emissions to
total annual emissions for each county by sector. These conversion
factors were then divided by 31 days in July to create final daily
scaling factors that were applied to the updated annual emissions
estimates.\9\ The Michigan Department of Transportation (MDOT) used
MOVES3 to generate nonroad and on-road July weekday emissions. Non-
point and nonroad emissions for Allegan County and Muskegon County were
scaled down based on geographic area. Allegan County is 50 percent of
full county; Muskegon is 58 percent of full county. On-road data for
Allegan County and Muskegon County was apportioned using vehicle miles
traveled and vehicle hours traveled ratios.
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\9\ EGLE determined that weekend day emissions have a large
impact on individual monitor design values and, therefore, included
weekend days in the calculation of typical ozone season day emission
values.
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Table 1, below, shows the updated 2017 ozone season day emissions
in tons per ozone season day of NO<INF>X</INF> and VOC for the Allegan
County, Berrien County, and Muskegon County areas.
Table 1--2017 Base Year Ozone Season Emissions
[Tons/day]
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Area Pollutant Point Nonpoint On-road Nonroad Total
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Allegan County............................ NOX......................... 0.98 0.89 1.86 0.69 4.42
VOC......................... 0.40 3.18 0.93 0.84 5.35
Berrien County............................ NOX......................... 1.54 1.31 5.05 1.63 9.53
VOC......................... 0.79 5.85 2.66 1.57 10.87
Muskegon County........................... NOX......................... 0.31 1.17 2.93 1.00 5.41
VOC......................... 0.30 3.09 2.26 0.71 6.36
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3. Evaluation of Michigan's 2017 Base Year Emission Inventory
EPA has reviewed Michigan's 2017 base year emissions inventory for
consistency with sections 172(c)(3) and 182(a)(1) of the CAA, and EPA's
emission inventory requirements. The selection of 2017 as the base year
comports with the RFP baseline year requirements set forth in the SIP
Requirements Rule and codified at 40 CFR 51.1310(b).
EGLE documented the procedures used to estimate the emissions for
each of the major source types. The documentation of the emission
estimation procedures is adequate to determine that Michigan followed
acceptable procedures to estimate the emissions. Accordingly, EPA
concludes that Michigan has developed inventories of NO<INF>X</INF> and
VOC emissions that are comprehensive and complete.
B. 15% RFP Plan
1. Background
The CAA requires that States with areas designated as nonattainment
for ozone achieve RFP toward attainment of the ozone NAAQS. CAA section
172(c)(2) contains a general requirement that nonattainment plans must
provide for emissions reductions that meet RFP. For areas classified
Moderate and above, section 182(b)(1) imposes a more specific RFP
requirement that a State was required to meet through a 15% reduction
in VOC emissions from the baseline anthropogenic emissions within 6
years after November 15, 1990.
The SIP Requirements Rule addressed, among other things, RFP
requirements as they apply to areas designated nonattainment and
classified as Moderate for the 2015 ozone NAAQS.\10\ RFP requirements
under the 2015 ozone NAAQS are codified at 40 CFR 51.1310. EPA
interprets the 15% VOC emission reduction requirement in CAA section
182(b)(1) such that a State that has already met the 15% requirement
for VOC for an area under either the 1-hour ozone NAAQS or a prior 8-
hour ozone NAAQS would not have to fulfill that requirement through
reductions of VOC again. Instead, EPA interprets CAA section 172(c)(2)
to require States with such areas to obtain 15% ozone precursor
emission reductions from VOC and/or NO<INF>X</INF> over the first 6
years after the baseline year for the 2015 ozone NAAQS. Michigan has
not met the 15% VOC reduction requirement of CAA section 182(b)(1) for
the Allegan County, Berrien County, or Muskegon County areas under
previous ozone NAAQS.\11\ Therefore, the State must rely upon VOC
emissions reductions to meet the RFP requirement for the 2008 ozone
NAAQS.
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\10\ 83 FR 62998 at 63004, December 6, 2018.
\11\ 74 FR 47414, September 15, 2009.
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The SIP Requirements Rule specifies that the baseline emissions
inventory for RFP plans shall be the most recent calendar year prior to
designation for which a complete triennial inventory is required to be
submitted to EPA under the provisions of subpart A of 40 CFR part 51,
Air Emissions Reporting Requirements, 40 CFR 51.1 through 50. For areas
designated as nonattainment in 2018, the most recent triennial
inventory year conducted for the NEI pursuant to the AERR rule is 2017.
The rule also allows the use of an alternative RFP baseline year that
corresponds with the year of the effective date of an area's
designation, i.e., 2018 for areas designated nonattainment in 2018.\12\
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\12\ 83 FR 62998 at 63005, December 6, 2018, codified at 40 CFR
51.1310(b).
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States may not take credit for VOC or NO<INF>X</INF> reductions
occurring from sources outside the nonattainment area for purposes of
meeting the 15% RFP requirements of CAA sections 172(c)(2), 182(b)(1)
and 182(c)(2)(B).\13\
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\13\ 40 CFR 51.1310(a)(6).
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Except as specifically provided in CAA section 182(b)(1)(C) and (D)
and CAA section 182(c)(2)(B), all emission reductions from SIP-approved
or federally promulgated measures that occur after the baseline
emissions inventory year are creditable for purposes of the RFP
requirements in this section, provided the reductions meet the
requirements for creditability, including the need to be enforceable,
permanent, quantifiable, and surplus.\14\ Further, the Administrator
has determined that the four categories of control measures listed in
CAA section 182(b)(1)(D) are no longer required to be calculated for
exclusion in RFP analyses because due to the passage of time the effect
of these exclusions would be de minimis.\15\
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\14\ 40 CFR 51.1310(a)(5).
\15\ 40 CFR 51.1310(a)(7).
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[[Page 57406]]
2. Michigan's 15% RFP Plan
Emission Inventories
To demonstrate that the Allegan County, Berrien County, and
Muskegon County areas have achieved 15% RFP over the 6-year attainment
planning period, EGLE is using a 2017 base year inventory and a 2023
RFP inventory. The procedures EGLE used to develop the 2017 base year
inventory are discussed in section I.A. of this preamble. When
developing the 2023 RFP inventory EGLE estimated onroad and nonroad
emissions using EPA's MOVES3 model. For the point and nonpoint source
categories, EGLE used the 2023v3 modeling inventory.
EGLE converted annual point and nonpoint values to tons/day
following the same procedure as was used when preparing the 2017 base
year emissions inventories. EGLE extracted data from the 2023v2
modeling platform to calculate the ratio of July emissions to total
annual emissions for each county by sector. These conversion factors
were then divided by 31 days in July to create final daily scaling
factors that were applied to the updated annual emissions estimates.
The Michigan Department of Transportation (MDOT) used MOVES3 to
generate nonroad and on-road July weekday emissions. Non-point and
nonroad emissions for Allegan County and Muskegon County were scaled
down based on geographic area. Allegan County is 50 percent of full
county; Muskegon is 58 percent of full county. On-road data for Allegan
County and Muskegon County was apportioned using vehicle miles traveled
and vehicle hours traveled ratios.
2023 ozone season day emissions of NO<INF>X</INF> and VOCs for each
county by sector are shown in Tables 3 and 4, below.
Table 2--2023 Ozone Season Emissions
[Tons/day]
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Area Pollutant Point Nonpoint Onroad Nonroad Total
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Allegan County............................ NOX......................... 1.06 0.81 0.96 0.55 3.38
VOC......................... 0.44 3.32 0.67 0.59 5.02
Berrien County............................ NOX......................... 2.07 1.23 2.48 1.33 7.11
VOC......................... 1.11 5.79 1.8 1.12 9.82
Muskegon County........................... NOX......................... 0.52 1.04 1.44 0.79 3.79
VOC......................... 0.11 3.08 1.58 0.53 5.30
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15% RFP Demonstration
EGLE demonstrated that the Allegan County, Berrien County, and
Muskegon County Areas have achieved 15% RFP over the 6-year attainment
planning period through VOC emission reductions in the onroad and
nonroad sectors attributable to EPA's existing Federal regulations,
Michigan's VOC RACT rules, Michigan's architectural and industrial
maintenance coating rule, and Michigan's consumer products rule.\16\
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\16\ EGLE also documented emission reductions from voluntary
programs that EPA is not including in RFP calculations.
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EPA onroad mobile source regulations currently being implemented
across the country include: passenger vehicle, SUV, and light duty
truck emissions and fuel standards; light-duty truck and medium duty
passenger vehicle evaporative standards; heavy-duty highway compression
engine standards; heavy-duty spark ignition engine standards;
motorcycle emission standards; mobile source air toxics fuel
formulation standards, passenger vehicle emission standards, and
portable container emission standards.\17\ EPA nonroad mobile source
regulations currently being implemented across the country include:
aircraft, compression ignition, large spark ignition, locomotive
engines, marine compression ignition, marine spark ignition,
recreational vehicle, and small spark ignition engine emission
standards and evaporative standards.\18\
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\17\ 40 CFR parts 59, 80, 85, 86, and 600.
\18\ 40 CFR parts 54, 60, 87, 89, 90, 1033, 1039, 1042, 1045,
1048, 1051, and 1054.
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Table 3 shows calculations demonstrating that Michigan's emission
reductions meet the 15% RFP requirement for the Allegan County, Berrien
County, and Muskegon County areas.
Table 3--15% RFP Calculations
[tpd]
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Area
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Description Formula Muskegon
Allegan County Berrien County County
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A. 2017 base year emission .......................... 5.35 10.87 6.36
inventories.
B. Required RFP % reductions--15%... .......................... 0.15 0.15 0.15
C. RFP emission reductions required A * B..................... 0.8 1.63 0.95
between 2017 & 2023.
D. RFP target levels for 2023....... A-C....................... 4.55 9.24 5.41
E. 2023 projected emissions .......................... 5.02 9.82 5.3
inventories.
F. Reductions between 2017 and 2023
included in 2023 projected
inventories:
Federal onroad control programs. .......................... 0.26 0.86 0.68
Federal nonroad control programs .......................... 0.25 0.44 0.18
Total....................... .......................... 0.51 1.3 0.86
G. Reductions between 2017 and 2023
NOT included in 2023 projected
inventories: *
VOC RACT........................ .......................... 0.23 0.6 0.15
[[Page 57407]]
Architectural and industrial .......................... 0.21 0.3 0.19
maintenance coatings rule.
Consumer products rule.......... .......................... 0.07 0.1 0.06
Total....................... .......................... 0.51 1 0.4
H. Emission reductions allocated to .......................... 0.03 0.05 0.16
motor vehicle emission budgets.
I. Net emission reductions between F + G-H................... 0.99 2.25 1.1
2017 and 2023.
J. Are creditable emission I >= C?................... Yes Yes Yes
reductions greater than or equal to
15% of the 2017 base year
inventory?.
K. 2023 RFP inventory: 2023 E-G + H................... 4.54 8.87 5.06
projected emissions inventories
minus reductions not included in
2023 projected inventories plus
emission reductions allocated to
motor vehicle emission budgets.
L. Has 2023 RFP target been K <= D?................... Yes Yes Yes
achieved?.
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3. Evaluation of Michigan's 15% RFP Plan
EPA has reviewed Michigan's 15% RFP plan for consistency with
sections 172(c)(2) and 182(b)(1) of the CAA, and 40 CFR 51.1310. The
selection of 2017 as the base year comports with the RFP baseline year
requirements set forth in the SIP Requirements Rule and codified at 40
CFR 51.1310(b). EPA has reviewed the techniques used by Michigan to
derive and quality assure the 2017 and 2023 emission estimates. EGLE
documented the procedures used to estimate the emissions for each of
the major source types. The documentation of the emission estimation
procedures is thorough and adequate to determine that EGLE followed
acceptable procedures to estimate the emissions. Emission reductions
attributable to Federal onroad and nonroad regulations, Michigan's VOC
RACT rules, Michigan's architectural and industrial maintenance coating
rule, and Michigan's consumer products rule are permanent and
enforceable and will result in at least 15% RFP in the Allegan County,
Berrien County, and Muskegon County areas over the 6-year attainment
planning period beginning with the 2017 base year. Thus, EPA is
proposing to approve Michigan's 15% RFP plan for the Allegan County,
Berrien County, and Muskegon County areas for the 2015 ozone NAAQS.
C. Motor Vehicle Emission Budgets
1. Background
Under section 176(c) of the CAA, transportation plans, programs, or
projects that receive Federal funding or support, such as the
construction of new highways, must ``conform'' to (i.e., be consistent
with) the SIP before they receive Federal funding or approval.
Conformity to the SIP means that transportation activities will not
cause or contribute to any new air quality violations, increase the
frequency or severity of any existing air quality problems, or delay
timely attainment or any required interim emissions reductions or any
other milestones. Regulations at 40 CFR part 93 subpart A set forth EPA
policy, criteria, and procedures for demonstrating and ensuring
conformity of transportation activities to a SIP.
Transportation conformity is a requirement for nonattainment and
maintenance areas, as defined in 40 CFR 93.101. The budget in a State's
SIP serves as a ceiling on emissions from an area's planned
transportation system (see definition of ``motor vehicle emissions
budget'' in 40 CFR 93.101 and how the term is used in 40 CFR 93.109 and
93.118).
When reviewing submitted SIPs containing budgets, EPA reviews the
budgets for adequacy. Once EPA affirmatively finds the submitted budget
is adequate for transportation conformity purposes, that budget must be
used by State and Federal agencies in determining whether proposed
transportation projects conform to the SIP as required by section
176(c) of the CAA.
EPA's substantive criteria for determining adequacy of a budget are
set out in 40 CFR 93.118(e)(4). The process for determining adequacy is
found in 40 CFR 93.118(f) and consists of three basic steps: public
notification of a SIP submission, a public comment period, and EPA's
adequacy finding. The regulations that allow EPA to begin an adequacy
review through a notice of proposed rulemaking in the Federal Register
are found in 40 CFR 93.118(f)(2). This proposal notifies the public
that EPA has received a SIP submission with budgets that EPA will
review for adequacy and begins the public comment period. Comments must
be submitted to the docket for this proposal by the close of the
comment period on this proposal.
2. VOC and NO<INF>X</INF> Budgets for the Allegan County, Berrien
County, and Muskegon County Areas
The RFP plan includes VOC and NO<INF>X</INF> budgets for the
Allegan County, Berrien County, and Muskegon County areas for 2023, the
milestone year for RFP. EPA invites the public to comment on the
adequacy of these budgets as well as on its proposed approval of the
budgets and on other actions EPA is proposing in this action.
The Michigan Department of Transportation prepared motor vehicle
emissions inventories for 2017 and 2023 for the purpose of setting
budgets for the year 2023. These inventories were developed using up-
to-date assumptions about vehicles mile traveled (VMT), vehicle age
distribution, socioeconomic variables, fuels used, weather inputs,
other planning assumptions, and the latest approved motor vehicle
emissions model at the time EGLE began to prepare the SIP submission,
which was MOVES3. Total onroad emissions in the Allegan County, Berrien
County, and Muskegon County areas are shown in Table 4.
[[Page 57408]]
Table 4--Total Onroad Emissions in the Allegan County, Berrien County, and Muskegon County Areas
----------------------------------------------------------------------------------------------------------------
Area Pollutant 2017 2023 Difference
----------------------------------------------------------------------------------------------------------------
Allegan County........................ NOX..................... 1.86 0.96 -0.9
VOC..................... 0.93 0.67 -0.26
Berrien County........................ NOX..................... 5.05 2.48 -2.57
VOC..................... 2.66 1.8 -0.86
Muskegon County....................... NOX..................... 2.93 1.44 -1.49
VOC..................... 2.26 1.58 -0.68
----------------------------------------------------------------------------------------------------------------
Table 5 identifies Michigan's 2023 budgets. The budgets, agreed
upon as part of the interagency consultation process, include the
emission estimates calculated for 2023 with an additional safety margin
allocated to those estimates to accommodate future variations in travel
demand models and VMT forecast. A State can add a safety margin to a
budget based on the transportation conformity regulation at 40 CFR
93.124(a).
Table 5--2023 Budgets for the Allegan County, Berrien County, and Muskegon County Areas
[tpd]
--------------------------------------------------------------------------------------------------------------------------------------------------------
2023 Mobile
Area Pollutant 2023 Estimated Safety margin safety margin 2023 Mobile
mobile emissions (% of 2023) allocation budget
--------------------------------------------------------------------------------------------------------------------------------------------------------
Allegan County.................................. NOX............................... 0.96 20 0.19 1.15
VOC............................... 0.67 5 0.03 0.70
Berrien County.................................. NOX............................... 2.48 20 0.50 2.98
VOC............................... 1.8 3 0.05 1.85
Muskegon County................................. NOX............................... 1.44 20 0.29 1.73
VOC............................... 1.58 10 0.16 1.74
--------------------------------------------------------------------------------------------------------------------------------------------------------
3. Evaluation of the VOC and NO<INF>X</INF> Budgets for the Allegan
County, Berrien County, and Muskegon County Areas
The VOC and NO<INF>X</INF> budgets for the Allegan County, Berrien
County, and Muskegon County areas were developed as part of an
interagency consultation process which includes Federal, State, and
local agencies. The budgets were clearly identified and precisely
quantified. Michigan has demonstrated that the Allegan County, Berrien
County, and Muskegon County areas can meet the 15% RFP requirement with
mobile source emissions of 1.15 tpd of NO<INF>X</INF> and 0.70 tpd of
VOC, 2.98 tpd of NO<INF>X</INF> and 1.85 tpd of VOC, and 1.73 tpd of
NO<INF>X</INF> and 1.74 tpd of VOC, respectively, in 2023 because, as
shown in Table 3, despite partial allocation of the RFP plan surplus
reductions, emissions will remain under 2023 RFP target levels. EPA is
thus proposing to approve the 2023 VOC and NO<INF>X</INF> budgets for
use in determining transportation conformity in the Allegan County,
Berrien County, and Muskegon County areas under the 2015 ozone NAAQS.
III. What action is EPA taking?
EPA is proposing to approve Michigan's updated 2017 base year
emissions inventory and 15% RFP demonstration, including the associated
motor vehicle emissions budgets, as revisions to Michigan's SIP
pursuant to section 110 and part D of the CAA and EPA's regulations
because EGLE's October 16, 2023, submission satisfies the base year
inventory and RFP requirements of the CAA for the Allegan County,
Berrien County and Muskegon County areas under the 2015 ozone NAAQS.
EPA is also initiating the adequacy process for the 2023 motor vehicle
emissions budgets for the Allegan County, Berrien County and Muskegon
County areas included in this SIP submission.
IV. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the CAA and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, EPA's role is to approve State choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely approves State law as meeting Federal requirements and
does not impose additional requirements beyond those imposed by State
law. For that reason, this action:
<bullet> Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Order 12866 (58
FR 51735, October 4, 1993);
<bullet> Is not subject to Executive Order 14192 (90 FR 9065,
February 6, 2025) because SIP actions are exempt from review under
Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
<bullet> Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it approves a State program;
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<bullet> Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA.
In addition, 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
[[Page 57409]]
governments or preempt Tribal law as specified by Executive Order 13175
(65 FR 67249, November 9, 2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Nitrogen oxides, Ozone,
Volatile organic compounds.
Dated: November 24, 2025.
Anne Vogel,
Regional Administrator, Region 5.
[FR Doc. 2025-22607 Filed 12-10-25; 8:45 am]
BILLING CODE 6560-50-P
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This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.