Proposed Rule2025-19278
Air Plan Approval; Ohio; Muskingum River 2010 Sulfur Dioxide Redesignation and Maintenance Plan
Primary source
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Published
October 2, 2025
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to redesignate the Muskingum River sulfur dioxide (SO<INF>2</INF>) nonattainment area, located in Center Township in Morgan County and Waterford Township in Washington County, Ohio, to attainment for the 2010 SO<INF>2</INF> National Ambient Air Quality Standard (NAAQS). EPA is also proposing to approve Ohio's maintenance plan for the area and Ohio's Director's Final Findings and Orders (DFFOs), issued March 26, 2025. Ohio submitted the request for approval on March 31, 2025.
Full Text
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<title>Federal Register, Volume 90 Issue 189 (Thursday, October 2, 2025)</title>
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[Federal Register Volume 90, Number 189 (Thursday, October 2, 2025)]
[Proposed Rules]
[Pages 47686-47693]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-19278]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 52 and 81
[EPA-R05-OAR-2025-0165; FRL-12974-01-R5]
Air Plan Approval; Ohio; Muskingum River 2010 Sulfur Dioxide
Redesignation and Maintenance Plan
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
redesignate the Muskingum River sulfur dioxide (SO<INF>2</INF>)
nonattainment area, located in Center Township in Morgan County and
Waterford Township in Washington County, Ohio, to attainment for the
2010 SO<INF>2</INF> National Ambient Air Quality Standard (NAAQS). EPA
is also proposing to approve Ohio's maintenance plan for the area and
Ohio's Director's Final Findings and Orders (DFFOs), issued March 26,
2025. Ohio submitted the request for approval on March 31, 2025.
DATES: Comments must be received on or before November 3, 2025.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2025-0165 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>, or via email to
<a href="/cdn-cgi/l/email-protection#7d1c0f0f1c530e1c0f1c153d180d1c531a120b"><span class="__cf_email__" data-cfemail="45243737246b362437242d052035246b222a33">[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 electronically
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: Gina Harrison, Air and Radiation
Division (AR18J), Environmental Protection Agency, Region 5, 77 West
Jackson Boulevard, Chicago, Illinois 60604, (312) 353-6956,
<a href="/cdn-cgi/l/email-protection#7c141d0e0e150f1312521b15121d3c190c1d521b130a"><span class="__cf_email__" data-cfemail="513930232338223e3f7f36383f30113421307f363e27">[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 and
facility closures.
SUPPLEMENTARY INFORMATION:
I. What is EPA proposing?
EPA is proposing to determine that the Muskingum River
SO<INF>2</INF> nonattainment area, located in Center Township in Morgan
County and Waterford Township in Washington County, Ohio, is attaining
the 2010 SO<INF>2</INF> NAAQS, based on quality-assured and certified
monitoring data for the period 2015-2024, in accordance with Ohio's
March 31, 2025, request. EPA has determined that the area is attaining
the 2010 SO<INF>2</INF> NAAQS and that the improvement in air quality
is due to permanent and enforceable SO<INF>2</INF> emission reductions
in the area. Therefore, EPA is proposing to change the legal
designation of the Muskingum River SO<INF>2</INF> nonattainment area to
attainment for the 2010 SO<INF>2</INF> NAAQS. EPA is also proposing to
approve Ohio's maintenance plan into the Ohio State Implementation Plan
(SIP), which is designed to ensure that the area will continue to meet
the SO<INF>2</INF> NAAQS. Finally, EPA is proposing to approve the
site-specific DFFOs which were issued on March 26, 2025, into the SIP.
Ohio's submittal, which includes the maintenance plan and DFFOs, will
be available for public review as part of the rulemaking docket for
this action.
II. What is the background for these actions?
On June 22, 2010 (75 FR 35520), EPA revised the primary
SO<INF>2</INF> NAAQS, establishing a new 1-hour standard of 75 parts
per billion (ppb), which is met at an ambient air quality monitoring
site when the 3-year average of the annual 99th percentile of daily
maximum 1-hour average concentrations is less than or equal to 75 ppb,
as determined in accordance with appendix T of 40 CFR part 50. 40 CFR
50.17(a)-(b). EPA promulgated designations for this standard in four
rounds.
On June 3, 2011, Ohio submitted its recommendations to EPA to
designate certain areas of the State as attaining, not attaining, or
unclassifiable for attaining the SO<INF>2</INF> NAAQS. Ohio recommended
that the area located in southeastern Ohio that includes Center
Township in Morgan County and Waterford Township in Washington County
be designated as nonattainment for the 2010 SO<INF>2</INF> NAAQS. EPA
concurred with Ohio's analysis and, on August 15, 2013, published a
final action designating the area as nonattainment of the 2010
SO<INF>2</INF> NAAQS, effective October 4, 2013 (78 FR 47191).
Under section 192(a) of the Clean Air Act (CAA), States are also
required to submit attainment plans to demonstrate that the respective
areas will attain the NAAQS as expeditiously as practicable, but no
later than five years from the effective date of designation. Ohio
submitted statewide nonattainment area SIPs to EPA on April 3, 2015,
and October 13, 2015, and submitted supplemental attainment plans for
the Muskingum River SO<INF>2</INF> nonattainment area on June 24, 2020,
July 28, 2022, and May 23, 2023.
Ohio's fully approved attainment plan included modeling for the
Globe Metallurgical, Inc., facility (Globe) and the State's DFFOs,
which set forth emission limits at Globe and monitoring and testing
requirements to confirm the source modeling characterization (September
8, 2023, 88 FR 61969). Ohio's modeled emissions for this area showed
the DFFO-required emission limits for Globe, in conjunction with the
SO<INF>2</INF> reductions from the permanent retirement of the
Muskingum River Power Plant in 2015, provide for attainment of the
SO<INF>2</INF> standard throughout the area. In addition, the DFFOs
required the installation and operation of an ambient air monitor
downwind of Globe for a period of three years.
On March 31, 2025, Ohio submitted a redesignation request and
maintenance plan to EPA for the Muskingum River SO<INF>2</INF>
nonattainment area for the 2010 SO<INF>2</INF> NAAQS. The submitted
redesignation request and maintenance plan include complete quality-
assured ambient air quality monitoring data meeting the 2010
SO<INF>2</INF> standard from 2015 to 2024. These NAAQS attainment
monitoring demonstrations, in addition to decreases in emission levels
attributable to the shutdown of the
[[Page 47687]]
Muskingum River Power Plant and the promulgation of emission limits and
other measures set forth in Ohio's DFFOs to Globe, provide the
framework for Ohio's request for redesignation to attainment for the
Muskingum River SO<INF>2</INF> nonattainment area. In addition, Ohio is
requesting that EPA approve the March 26, 2025, revised DFFOs that
replace emission limits established in the 2020 DFFOs for Globe to
provide for maintenance in the area. The 2020 DFFOs contain emission
limits that are currently in Ohio's approved SIP. Ohio is also
requesting that EPA approve the new emission limits from the March 26,
2025, revised DFFOs into the SIP.
Under section 107(d)(3)(E) of the CAA, EPA may not promulgate a
redesignation of a nonattainment area (or portion thereof) unless:
1. EPA has determined that the area has attained the NAAQS;
2. EPA has fully approved the applicable implementation plan for
the area under section 110(k) of the CAA;
3. EPA has determined that improvement in air quality is due to
permanent and enforceable reductions in emissions resulting from
implementation of the applicable implementation plan and applicable
Federal air pollution control regulations and other permanent and
enforceable reductions;
4. EPA has fully approved a maintenance plan for the area under
section 175A of the CAA; and
5. The State containing such area has met all requirements
applicable to the area under section 110 of the CAA and part D.
On April 16, 1992 (57 FR 13498), EPA provided guidance on
redesignations in the ``General Preamble for the Implementation of
Title I of the CAA Amendments of 1990'' and supplemented this guidance
on April 28, 1992 (57 FR 18070). EPA has provided further guidance on
processing redesignation requests in policy memoranda.
III. What is EPA's analysis of Ohio's redesignation request and
maintenance plan?
On October 2, 2023, Ohio submitted a request that EPA redesignate
the Muskingum River SO<INF>2</INF> nonattainment area to attainment and
a SIP revision containing a maintenance plan for the area. EPA's
evaluation of Ohio's redesignation request and maintenance plan was
based on consideration of the five redesignation criteria provided
under CAA section 107(d)(3)(E).
Criterion (1)--The Muskingum River SO<INF>2</INF> Nonattainment
Area has Attained the 2010 SO<INF>2</INF> NAAQS.
In accordance with CAA section 107(d)(3)(E)(i), for redesignation
of a nonattainment area to attainment, the CAA requires EPA to
determine that the area has attained the applicable NAAQS. In
accordance with 40 CFR 50.17 and appendix T of part 50, an area is
attaining the 1-hour primary SO<INF>2</INF> standard at an ambient air
quality monitoring site when the three-year average of the annual (99th
percentile) of the daily maximum 1-hour average concentrations is less
than or equal to 75 ppb. As stated in EPA's April 23, 2014 ``Guidance
for 1-Hour SO<INF>2</INF> Nonattainment Area SIP Submissions'' (April
2014 SO<INF>2</INF> Guidance), there are two components needed to
support an attainment determination: (1) a review of representative air
quality monitoring data located in the area of maximum concentration;
and (2) a further analysis, where there are no monitors, using air
quality dispersion modeling, which will generally be needed to estimate
SO<INF>2</INF> concentrations throughout the nonattainment area to
demonstrate that the entire area is attaining the applicable NAAQS,
based on current actual emissions or the fully implemented control
strategy.\1\ The April 2014 SO<INF>2</INF> Guidance further states that
dispersion modeling should be conducted to estimate SO<INF>2</INF>
concentrations throughout the nonattainment area using actual emissions
and meteorological information for the most recent three calendar
years.
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\1\ EPA's ``Guidance for 1-Hour Sulfur Dioxide (SO<INF>2</INF>)
Nonattainment Area State Implementation Plans (SIP) Submissions''
can be found at <a href="https://www.epa.gov/so2-pollution/guidance-1-hour-sulfur-dioxide-so2-nonattainment-area-state-implementation-plans-sip">https://www.epa.gov/so2-pollution/guidance-1-hour-sulfur-dioxide-so2-nonattainment-area-state-implementation-plans-sip</a>.
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EPA has reviewed the available SO<INF>2</INF> monitoring data from
Ohio's two monitoring sites in the Muskingum River SO<INF>2</INF>
nonattainment area for the 2015-2024 period--the Hackney monitor (site
39-115-004), and the Globe monitor (site 39-167-0011). On December 18,
2023, Ohio EPA requested to discontinue the Hackney monitor (39-115-
0004) due to the consistently low SO<INF>2</INF> values following the
permanent shutdown of the Muskingum River Power Plant in 2015. On
January 1, 2021, Ohio began operating the Globe monitor near the Globe
Metallurgical facility in an area of maximum concentration to monitor
emissions from this facility. These data have been quality assured in
accordance with 40 CFR 58.10, are recorded in the EPA Air Quality
System (AQS), and were certified in advance of EPA's publication of
this proposal. Data from both monitors demonstrate that the Muskingum
River SO<INF>2</INF> nonattainment area is attaining the 2010
SO<INF>2</INF> NAAQS. Since 2011, the highest three-year average of the
annual 99th percentile of 1-hour daily maximum concentrations was 42
ppb for the Hackney monitor and 24 ppb for the Globe monitor. Data for
all monitoring sites and three-year design values are summarized in
Tables 1 and 2, respectively.
Table 1--Annual 99th Percentile Monitoring Data for the Muskingum River Nonattainment Area (Site 39-115-004, Hackney, and Site 39-167-0011, Globe) for 2011-2024
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Year (ppb)
Site County -----------------------------------------------------------------------------------------------------------------------------
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024
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Hackney................................ Morgan................... 175 142 124 148 91 17 17 * 18 15 13 * 18 13 24 N/A
Globe.................................. Morgan................... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... * 17 24 26 22
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* Less than 75% data capture in at least one quarter.
[[Page 47688]]
Table 2--Three-Year Design Values for the Muskingum River Nonattainment Area (Site 39-115-004, Hackney, and Site 39-167-0011, Globe) for 2011-2024
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Year (ppb)
Site County -----------------------------------------------------------------------------------------------------------------------------------
2011-2013 2012-2014 2013-2015 2014-2016 2015-2017 2016-2018 2017-2019 2018-2020 2019-2021 2020-2022 2021-2023 2022-2024
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Hackney............................. Morgan................ 147 138 121 85 42 * 17 * 17 * 15 15 15 18 N/A
Globe............................... Morgan................ ......... ......... ......... ......... ......... ......... ......... ......... ......... ......... * 22 24
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* Less than 75% data capture in at least one quarter.
The Muskingum River SO<INF>2</INF> nonattainment area's 3-year
SO<INF>2</INF> design value at the Hackney monitor \2\ first began
attaining in the 2015-2017 design period with a value of 42 ppb,\3\
which meets the 2010 SO<INF>2</INF> NAAQS. In addition, the highest 3-
year design value at the Globe monitor is 24 ppb. Therefore, EPA
proposes to determine that the Muskingum River SO<INF>2</INF>
nonattainment area is attaining the 2010 SO<INF>2</INF> NAAQS.
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\2\ On December 8, 2023, Ohio requested to discontinue the
Hackney monitor due to the shutdown of the Muskingum River Power
Plant and the subsequent low levels of SO<INF>2</INF> measured at
that monitor.
\3\ The SO<INF>2</INF> design value for the Hackney monitor with
the highest 3-year averaged concentration following the 2015
shutdown of the Muskingum River Power Plant.
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EPA also considered Ohio's air quality modeling analyses submitted
in the State's attainment plan SIP revision. On June 23, 2020, Ohio
submitted a supplement to the attainment demonstration and control
strategy for the Muskingum River SO<INF>2</INF> nonattainment area,
which included twenty-six sets of SO<INF>2</INF> emission limits for
Globe along with air quality modeling. These emission limit sets were
based on modeled values demonstrating attainment and maintenance of the
standard. Ohio's air quality modeling submitted in its attainment
demonstration used the emission limit sets and yielded design values
below the 2010 SO<INF>2</INF> NAAQS for the Muskingum River area. The
April 2014 SO<INF>2</INF> Guidance provides an extensive discussion of
EPA's view that appropriately set comparably stringent limits based on
averaging times as long as 30 days can be found to provide for
attainment of the 2010 SO<INF>2</INF> NAAQS. The April 2014
SO<INF>2</INF> Guidance also offers specific recommendations for
determining an appropriate longer-term average limit.
Based on the limits and other information submitted in the June 23,
2020, supplement, Ohio EPA issued DFFOs that set forth the 26 sets of
1-hour emission limits, monitoring requirements, and testing and
compliance plans for the Globe facility. EPA approved the emission
limits on January 18, 2022 (87 FR 2555), and on September 8, 2023 (88
FR 61969), as a part of Ohio's attainment demonstration SIP. Ohio's
plan applies 1-hour emission rate combination emission limits as a 24-
hour average to Globe's two baghouses. More detail on EPA's analysis of
the attainment plan for the Muskingum River SO<INF>2</INF>
nonattainment area can be found in the September 8, 2023 (88 FR 61969),
attainment plan approval.
The attainment plan required that Globe perform further source
testing to verify the accuracy of the previously modeled parameters.
Globe performed these additional tests in June 2024 and updated the
attainment strategy modeling to revise two of the emission limit sets--
specifically, to revise one and remove one of the sets. These changes
better align the limits with expected production scenarios. On March
26, 2025, Ohio revised its DFFOs and issued new DFFOs reflecting these
changes. The final emission limit sets are summarized in Table 3 with
the modeled rate and adjusted limit with a 24-hour averaging rate. For
more information on the modeling, emission limit sets, and averaging
rate, see EPA's proposed attainment plan for this area.\4\
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\4\ See EPA's proposed attainment plan approval for the
Muskingum River SO<INF>2</INF> nonattainment area. 88 FR 40726 (June
22, 2023).
Table 3--Globe's Modeled Attainment Rates and Final Attainment SO2 Emission Limits Included in Ohio's March 26,
2025, DFFOs
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Modeled 1-hour emission rate Final attainment 24-hour average
combinations (lb/hr) SO2 emission limit combinations
---------------------------------- (lb/hr)
Modeled design ---------------------------------
Emission limit set Shop 1 Shop 2 value Shop 1
Baghouse: P902 Baghouse: P907 ([micro]g/m3) Baghouse: P902 Shop 2
(EAF 1) P903 (EAF 5) P908 * (EAF 1) P903 Baghouse: P907
(EAF 2) P904 (EAF 7) (EAF 2) P904 (EAF 5) P908
(EAF 3) (EAF 3) (EAF 7)
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1........................... 210.0 0.0 149.6 195.3 0.0
2........................... 205.0 60.0 150 190.6 55.8
3........................... 200.0 80.0 146.8 186.0 74.4
4........................... 195.0 110.0 149.5 181.3 102.3
5........................... 190.0 125.0 150.6 176.7 116.2
6........................... 185.0 140.0 152.2 172.0 130.2
7........................... 180.0 155.0 153.8 167.4 144.1
8........................... 175.0 170.0 155.6 162.7 158.1
9........................... 170.0 180.0 157.9 158.1 167.4
10.......................... 165.0 190.0 159.2 153.4 176.7
11.......................... 160.0 200.0 162.8 148.8 186.0
12.......................... 155.0 205.0 163.8 144.1 190.6
13.......................... 150.0 210.0 165.4 139.5 195.3
[[Page 47689]]
14.......................... 145.0 215.0 168.5 134.8 199.9
15.......................... 140.0 220.0 171.6 130.2 204.6
16.......................... 135.0 230.0 178.2 125.5 213.9
17.......................... 130.0 235.0 181.3 120.9 218.5
18.......................... 125.0 240.0 183.9 116.2 223.2
19.......................... 120.0 240.0 184.4 111.6 223.2
20.......................... 115.0 245.0 187 106.9 227.8
21.......................... 95.0 250.0 188.9 88.3 232.5
22.......................... 80.0 255.0 191.1 74.4 237.1
23.......................... 65.0 260.0 193.4 60.4 241.8
24.......................... 45.0 265.0 195.2 41.8 246.4
25.......................... 0.0 270.0 194.7 0.0 251.1
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* Converting from [micro]g/m\3\ to ppb into Concentration (ppb) = 24.45 x concentration ([micro]g/m\3\) /
molecular weight of SO2 (64.07 g/mol). The 75 ppb standard is equivalent to 196.5 [micro]g/m\3\.
Ohio's modeled demonstration of attainment for EPA's modeling
demonstrated a maximum design value of 194.7 [micro]g/m3, or 74.3 ppb,
with the revised SO<INF>2</INF> emission limits that will provide for
attainment based on the new requirements for Globe, which are both
permanently and federally enforceable. EPA concluded that Ohio's
modeling is a suitable demonstration that its requirements in the DFFOs
for Globe were properly addressed in the attainment plan. EPA's
supplemental modeling demonstrated that the updated limits for Globe
provide for attainment and, along with monitoring data showing the area
is attaining the standard, is the secondary basis to conclude that the
area is attaining the 2010 SO<INF>2</INF> NAAQS. Ohio's redesignation
request for the Muskingum River SO<INF>2</INF> nonattainment area
relied upon the demonstration of attainment based on the permanent
shutdown of the Muskingum River Power Plant, the revised emission
limits for Globe, and monitoring data from the nearest AQS monitors.
In this action, EPA is proposing to find that the Muskingum River
SO<INF>2</INF> nonattainment area has attained and will continue to
attain the 2010 SO<INF>2</INF> NAAQS with respect to the redesignation
criteria under CAA section 107(d)(3)(E)(i).
Criterion (2) and Criterion (5)--Ohio has met all applicable
requirements under CAA section 110 and part D of the CAA, and EPA has
fully approved the applicable implementation plan under CAA section
110(k).
For redesignation of an area from nonattainment to attainment of a
NAAQS, the CAA requires EPA to determine that the State has met all
applicable requirements under section 110 and part D of title I of the
CAA (see section 107(d)(3)(E)(v) of the CAA) and that the State has a
fully approved SIP under section 110(k) of the CAA (see section
107(d)(3)(E)(ii) of the CAA). Part D is comprised of the general
nonattainment area plan requirements in subpart 1 (section 172) as well
as pollutant specific subparts, including section 191 (or subpart 5),
which applies to areas designated nonattainment for SO<INF>2,</INF>
nitrogen dioxide, or lead. While some nonattainment planning
requirements are not applicable for purposes of CAA section
107(d)(3)(E)(ii) and (v) for areas that are attaining the NAAQS, Ohio
has in any case submitted a complete attainment plan and EPA has fully
approved that plan, including emissions inventories, Reasonably
Available Control Technology/Reasonably Available Control Measures,
Reasonable Further Progress, and contingency measures.
On April 3, 2015, and supplemented on October 13, 2015, March 13,
2017, June 25, 2019, June 23, 2020, June 24, 2022, and May 24, 2023,
Ohio submitted its attainment demonstration SIP for the Muskingum River
SO<INF>2</INF> nonattainment area. EPA approved Ohio's attainment plan
SIP effective October 10, 2023 (88 FR 61969). EPA has reviewed Ohio's
SIP submittals and proposes to find that that by these submittals Ohio
meets the general SIP requirements under section 110 of the CAA for the
2010 SO<INF>2</INF> standard. Therefore, EPA proposes to find that Ohio
has satisfied the requirements in section 110 and part D, and that Ohio
has met all applicable SIP requirements for purposes of redesignation
under section 119 and part D of title I of the CAA (requirements
specific to nonattainment areas for the 2010 SO<INF>2</INF> NAAQS).
Additionally, EPA proposes to find that Ohio has a fully approved
SIP under section 110(k) of the CAA. Section 110(a)(2) of the CAA
delineates the general requirements for a SIP. Section 110(a)(2)
provides that the SIP must have been adopted by the State after
reasonable public notice and hearing, and that, among other things, it
must: (1) include enforceable emission limitations and other control
measures, means or techniques necessary to meet the requirements of the
CAA; (2) provide for establishment and operation of appropriate
devices, methods, systems and procedures necessary to monitor ambient
air quality; (3) provide for implementation of a source permit program
to regulate the modification and construction of stationary sources
within the areas covered by the plan; (4) include provisions for the
implementation of part C prevention of significant deterioration (PSD)
and part D new source review permit programs; (5) include provisions
for stationary source emission control measures, monitoring, and
reporting; (6) include provisions for air quality modeling; and (7)
provide for public and local agency participation in planning and
emission control rule development.
[[Page 47690]]
In Ohio's June 7, 2013, infrastructure SIP submission, Ohio
verified that the State fulfills the requirements of section 110(a)(1)
and section 110(a)(2) of the CAA with respect to the 2010
SO<INF>2</INF> NAAQS. Ohio's June 7, 2013, infrastructure SIP for the
2010 SO<INF>2</INF> standard contains SIP approved Ohio Administrative
Code Chapter 3745-18, through which SO<INF>2</INF> emissions are
directly regulated. As discussed in ``Criterion 4,'' below, EPA already
approved Ohio's base year emissions inventory and emission statement
program as meeting the requirements of sections 110 and part D, and
section 110(k), respectively, as they relate to the 2010 SO<INF>2</INF>
NAAQS.\5\ EPA has determined which requirements are applicable for
purposes of redesignation, and whether the required Ohio SIP elements
are fully approved under section 110(k) and part D of the CAA.
Therefore, EPA proposes to find that Ohio has met all applicable
requirements under CAA section 110 and part D, including CAA section
110(k).
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\5\ Ohio submitted its 2011 base year inventory and 2018 future
year inventory as a part of Ohio's October 13, 2015, attainment
demonstration SIP, which was approved by EPA on October 11, 2018 (83
FR 51361).
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Criterion (3)--The Air Quality Improvement in the Muskingum River
SO2 Nonattainment Area Is Due to Permanent and Enforceable Emission
Reductions.
To redesignate an area from nonattainment to attainment, section
107(d)(3)(E)(iii) of the CAA requires EPA to determine that the air
quality improvement in the area is due to permanent and enforceable
reductions in emissions resulting from the implementation of the SIP
and applicable Federal air pollution control regulations and other
permanent and enforceable emission reductions.
Ohio's attainment plan incorporates confirmation of the permanent
shutdown of the Muskingum River Power Plant. In 2011, Muskingum River
Power Plant accounted for approximately 99% of SO<INF>2</INF> emissions
in the area--emitting 104,138.03 tons of SO<INF>2</INF> of the entire
2011 EGU and non-EGU inventory of 105,341.03 tons of SO<INF>2</INF>.
The last coal fired boiler at the Muskingum River Power Plant ceased
operations on May 15, 2015, and all coal fired boilers at the facility
were permanently retired on May 31, 2015. Emissions of SO<INF>2</INF>,
by unit and for the entire facility, from 2011 through 2016 are shown
in Table 4 below.
Table 4--Muskingum River Power Plant SO2 Emissions 2011-2016
[tpy]
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Unit 2011 2012 2013 2014 2015 2016
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B001.................................................... 16.33 0.28 0.25 0.38 0.00 0.00
B002.................................................... 18190.00 2644.61 0.00 0.00 0.00 0.00
B003.................................................... 17420.30 2887.61 0.00 0.00 0.00 0.00
B004.................................................... 24684.50 15309.30 16273.40 13961.90 0.00 0.00
B005.................................................... 24314.00 9431.73 3831.13 4337.55 1927.51 0.00
B006.................................................... 19512.90 5864.48 12919.80 31276.80 13734.30 0.00
Facility................................................ 104138.03 36138.01 33024.58 49576.63 15661.81 0.00
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As explained in further detail under ``Criterion 1,'' above, EPA
approved Globe's limits into Ohio's SIP on January 18, 2022 (87 FR
2555), and on September 8, 2023 (88 FR 61969), which renders them
federally enforceable. Any new sources of SO<INF>2</INF> are limited by
new source performance standards under sections 111 and 129 of the CAA;
and the national emission standards for hazardous air pollutants under
section 112 of the CAA.
EPA is proposing to find, consistent with its approval of Ohio's
attainment plan, that the combination of the Globe emission modeling
results and the lack of emissions from other sources in the area
demonstrates attainment and continued maintenance of the 2010
SO<INF>2</INF> NAAQS, and that the air quality improvement in the
Muskingum River SO<INF>2</INF> nonattainment area is due to permanent
and enforceable reductions in emissions.
Criterion (4)--The Muskingum River SO2 Nonattainment Area Has a
Fully Approved Maintenance Plan Pursuant to Section 175A.
Section 175A of the CAA sets forth the elements of a maintenance
plan for areas seeking redesignation from nonattainment to attainment.
Under section 175A, the plan must demonstrate continued attainment of
the applicable NAAQS for at least ten years after the nonattainment
area is redesignated to attainment. Eight years after the
redesignation, the State must submit a revised maintenance plan
demonstrating that attainment will continue to be maintained for the
ten years following the initial ten-year period. To address the
possibility of future NAAQS violations, the maintenance plan must
contain contingency measures as EPA deems necessary to ensure prompt
correction of any future one-hour violations.
Specifically, the maintenance plan should address five
requirements: the attainment emissions inventory, maintenance
demonstration, monitoring, verification of continued attainment, and a
contingency plan. EPA is proposing to determine that Ohio's March 31,
2025, redesignation request contains its maintenance plan and all the
necessary components, which Ohio has committed to review eight years
after the redesignation.
1. Attainment Emissions Inventory
As a part of a State's maintenance plan, the air agency should
develop an attainment emissions inventory to identify the level of
emissions in the affected area which is sufficient to attain and
maintain the SO<INF>2</INF> NAAQS.\6\ Ohio submitted its 2011 base year
inventory and 2018 future year inventory as a part of Ohio's October
13, 2015, attainment demonstration SIP. In its redesignation request,
Ohio provided an emissions inventory for SO<INF>2</INF> in the
nonattainment area for 2015, which is one of the years in the design
value where attainment was first achieved. See Table 5, below.
---------------------------------------------------------------------------
\6\ See April 2014 SO<INF>2</INF> Guidance, page 66.
[[Page 47691]]
Table 5--Muskingum River, Ohio (Waterford Township, Washington County, Plus Center Township, Morgan County) SO2
Emission Inventory Totals for 2011 Base, 2015 Attainment, 2026 Projected Interim, and 2038 Projected Maintenance
(tpy), and Safety Margin Comparing 2015 Attainment to 2038 Projected Maintenance
----------------------------------------------------------------------------------------------------------------
2015 2026 Projected 2038 Projected
Sector 2011 Base Attainment interim maintenance Safety margin
----------------------------------------------------------------------------------------------------------------
EGU Point........................ 104148.62 15687.43 22.98 0.01 15687.42
Non-EGU.......................... 1192.41 1013.74 1842.84 1752.14 -738.40
Non-road......................... 0.06 0.05 0.01 0.01 0.04
On-road.......................... 0.26 0.27 0.07 0.05 0.22
Other............................ 4.66 4.33 2.53 2.55 1.78
------------------------------------------------------------------------------
Total........................ 105346.01 16705.82 1868.43 1754.76 17951.06
----------------------------------------------------------------------------------------------------------------
Total actual emissions in the Muskingum River SO<INF>2</INF>
nonattainment area for the 2015 attainment year were 16,705.82 tons.
This level of emissions, in combination with emission limits set forth
at the Globe facility, are sufficient to maintain the NAAQS. In its
redesignation request, Ohio reported that total actual SO<INF>2</INF>
emissions for the Muskingum River SO<INF>2</INF> nonattainment area
from 2011, a year during which the area was not attaining the NAAQS,
were 105,346.01 tons. The permanent shutdown of the Muskingum River
Power Plant in 2015 led to decreases in actual SO<INF>2</INF> emissions
by over 88,641 tons in the Muskingum River SO<INF>2</INF> nonattainment
area when comparing the years 2011 and 2015. These data satisfy the
attainment emissions inventory requirement for the Muskingum River
SO<INF>2</INF> nonattainment area maintenance plan.
2. Maintenance Demonstration
EPA's ``Procedures for Processing Requests to Redesignate Areas to
Attainment'' (Calcagni Memo) \7\ describes two ways for a State to
demonstrate maintenance of the NAAQS following the redesignation of the
area: (1) the State can show that future emissions of a pollutant will
not exceed the level of the attainment inventory, or (2) the State can
model to show that the future mix of sources and emission rate will not
cause a violation of the standard. In both instances, the demonstration
should be for a period of 10 years following the redesignation.
Furthermore, the plan should contain a summary of air quality
concentrations resulting from control measures implemented where
modeling is relied upon to demonstrate maintenance. Ohio's maintenance
demonstration consists of the attainment SIP air quality modeling
analysis showing that the emission reductions now in effect in the
Muskingum River SO<INF>2</INF> nonattainment area will provide for
attainment of the 2010 SO<INF>2</INF> NAAQS for the 2026 projected
interim date and will also be below the 2015 attainment year totals by
the year 2038 projected maintenance date. The permanent and enforceable
SO<INF>2</INF> emission reductions described above ensure that the area
emissions will be equal to or less than the emission levels that were
evaluated in the air quality modeling analysis, and Ohio's enforceable
emission requirements will ensure that the Muskingum River area
SO<INF>2</INF> emission limits are met continuously.
---------------------------------------------------------------------------
\7\ 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.
Table 6--Muskingum River, Ohio (Waterford Township, Washington County, Plus Center Township, Morgan County) Emission Estimates (tpy) Comparing the 2015
Attainment Year to Projected Maintenance Dates
--------------------------------------------------------------------------------------------------------------------------------------------------------
2015 2026 Projected 2026 Projected 2038 Projected 2038 Projected
Attainment interim interim decrease maintenance maintenance decrease
--------------------------------------------------------------------------------------------------------------------------------------------------------
SO2................................................. 16705.82 1868.43 14837.69 1754.76 14951.06
--------------------------------------------------------------------------------------------------------------------------------------------------------
As demonstrated in Table 6, SO<INF>2</INF> emissions in the area
are projected to decrease by almost 15,000 tpy in 2026 and 2038 from
2015 attainment levels, which demonstrates maintenance.
3. Monitoring
By providing actual monitoring data from the national emissions
inventory and State inventory databases (e.g., Ohio's Emission
Inventory System), for non-road EGU and non-EGU point sources of
SO<INF>2</INF>, from time periods including when the area was not
meeting the NAAQS (2011) and when the area was attaining the NAAQS
(2015), Ohio has demonstrated a 99 percent reduction in actual annual
SO<INF>2</INF> emissions in the area. Ohio's monitoring, described
above, shows the combination of the 2015 Muskingum River Power Plant
shutdown and the newly imposed and federally enforceable DFFOs
SO<INF>2</INF> limits for Globe result in the area maintaining
attainment of the SO<INF>2</INF> NAAQS.
4. Verification of Continued Attainment
For continuing verification, Ohio will track the emissions and
compliance status of the Globe facility in the Muskingum River
SO<INF>2</INF> nonattainment area so that future emissions will not
exceed the allowable emissions-based attainment inventory. All major
sources in Ohio are required to submit annual emissions data, which the
State uses to update its emission inventories as required by the CAA.
The Globe facility must submit annual compliance certifications to
ensure the facility is meeting its SIP limits and the facility must
submit a semi-annual Monitoring Report to Ohio, summarizing required
monitoring results and identifying all instances of deviation from the
permit and other regulations.
Ohio will also continue operating its air quality monitoring
network to verify maintenance of the attainment status of the Muskingum
River SO<INF>2</INF>
[[Page 47692]]
nonattainment area. The closest monitor to the Muskingum River
SO<INF>2</INF> nonattainment area is the Globe monitor (AQS ID: 39-167-
0011). Ohio will provide EPA with annual emissions reports as part of
Ohio's annual network plan submittal to provide ongoing verification of
attainment and will consult with EPA prior to discontinuing
5. Contingency Plan
Section 175A(d) of the CAA provides that a maintenance plan must
contain contingency provisions that will promptly correct any violation
of the SO<INF>2</INF> NAAQS after the area is redesignated to
attainment.\8\ The maintenance plan should identify the contingency
measures to be adopted, a schedule and procedure for adoption and
implementation, and a time limit for action by the State.
---------------------------------------------------------------------------
\8\ See also Calcagni Memo.
---------------------------------------------------------------------------
A State should also identify specific indicators to be used to
determine when the contingency measures need to be implemented. The
maintenance plan must also include a requirement that a State will
implement all measures with respect to control of the pollutant that
were contained in the SIP before redesignation of the area to
attainment in accordance with section 175A(d). Unlike CAA section
172(c)(9), section l75A of the CAA does not explicitly require that
contingency measures must take effect without further action by the air
agency in order for the maintenance plan to be approved. However, the
maintenance plan's contingency plan would become an enforceable part of
the SIP and should ensure that contingency measures are adopted and
implemented as expeditiously as practicable once they are triggered.\9\
In the ``General Preamble for the Implementation of Title I of the
Clean Air Act Amendments of 1990,'' published on April 16, 1992 (57 FR
13498), EPA provides further discussion of contingency measures for
SO<INF>2</INF>. This guidance states that in many cases, attainment
revolves around compliance of a single source or a small set of sources
with emission limits shown to provide for attainment. Although this
guidance applies to contingency measures under section 172(c)(9), EPA
applies a similar policy with respect to contingency measures for
SO<INF>2</INF> required in maintenance plans under section 175A(d). The
requirement to submit contingency measures in accordance with section
175A of the CAA can be adequately addressed for SO<INF>2</INF> by the
operation of a comprehensive enforcement program,\10\ which can quickly
identify and address sources that might be causing exceedances of the
NAAQS.
---------------------------------------------------------------------------
\9\ See April 2014 SO<INF>2</INF> Guidance, page 74.
\10\ See April 2014 SO<INF>2</INF> Guidance, page 41-42
---------------------------------------------------------------------------
Ohio's enforcement program is active and capable of prompt action
to remedy compliance issues. Ohio commits to ongoing compliance and
enforcement of the control measures contained in the DFFOs issued to
Globe that were approved and incorporated into the Ohio SIP (88 FR
61969), and the newly issued March 26, 2025, DFFOs proposed for
approval in this action. In its redesignation request, Ohio commits to
review its maintenance plan eight years after redesignation, as
required by section 175A of the CAA. Ohio also has the necessary
resources in the event of violations to enforce its permit provisions
and rules. Ohio has the authority to expeditiously adopt, implement,
and enforce any subsequent emission control measures deemed necessary
to correct any future SO<INF>2</INF> violations. Ohio commits to
adopting and implementing such corrective actions as necessary to
address violations of the SO<INF>2</INF> NAAQS. Another contingency
measure option is the implementation of a PSD program for new or
modified existing sources of SO<INF>2</INF>, which includes
requirements for Best Available Control Technology, in the Muskingum
River SO<INF>2</INF> nonattainment area once redesignated to
attainment. The Globe DFFOs have been adopted into the Ohio SIP and
include emission limits, monitoring, recordkeeping, compliance testing
and reporting requirements that will be used to confirm ongoing
compliance. Based on the foregoing, EPA proposes to find that Ohio has
addressed the contingency measure requirement.
EPA is proposing to find that Ohio's maintenance plan adequately
addresses the five basic components of a maintenance plan necessary to
maintain the SO<INF>2</INF> NAAQS in the Muskingum River SO<INF>2</INF>
nonattainment area. Therefore, EPA proposes to find that the
redesignation and maintenance plan SIP revision submitted by Ohio for
the Muskingum River SO<INF>2</INF> nonattainment area meets the
requirements of section 175A of the CAA and proposes to approve this
plan.
IV. What action is EPA taking?
EPA is proposing to redesignate the Muskingum River SO<INF>2</INF>
nonattainment area from nonattainment to attainment for the 2010
SO<INF>2</INF> NAAQS in accordance with Ohio's March 31, 2025, request.
EPA has determined that the area is attaining the 2010 SO<INF>2</INF>
NAAQS and that the improvement in air quality is due to permanent and
enforceable SO<INF>2</INF> emission reductions in the area. EPA is also
proposing to approve Ohio's maintenance plan, which is designed to
ensure that the area will continue to maintain attainment of the 2010
SO<INF>2</INF> NAAQS. Finally, EPA is proposing to approve Ohio's DFFOs
issued to Globe on March 26, 2025, which set forth emission limits and
other requirements that will provide for attainment of the 2010
SO<INF>2</INF> NAAQS in this area.
V. Incorporation by Reference
In this rule, EPA is proposing to include in a final EPA rule
regulatory text that includes incorporation by reference. In accordance
with requirements of 1 CFR 51.5, EPA is proposing to incorporate by
reference Ohio's DFFOs issued to Globe, effective March 26, 2025,
discussed in section II. of this preamble. EPA has made, and will
continue to make, these documents generally available through
<a href="http://www.regulations.gov">www.regulations.gov</a> and at the EPA Region 5 Office (please contact the
person identified in the FOR FURTHER INFORMATION CONTACT section of
this preamble for more information).
VI. Statutory and Executive Order Reviews
Under the CAA, redesignation of an area to attainment and the
accompanying approval of a maintenance plan are actions that affect the
status of a geographical area and do not impose any additional
regulatory requirements on sources beyond those imposed by State law. A
redesignation to attainment does not in and of itself create any new
requirements, but rather results in the applicability of requirements
contained in the CAA for areas that have been redesignated to
attainment. Moreover, the Administrator is required to approve a SIP
submission that complies with the provisions of the 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 these reasons, 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
[[Page 47693]]
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 rule does not have Tribal implications and will not impose
substantial direct costs on Tribal governments or preempt Tribal law as
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Reporting and recordkeeping
requirements, Sulfur oxides.
Dated: September 23, 2025.
Cheryl Newton,
Acting Regional Administrator, Region 5.
[FR Doc. 2025-19278 Filed 10-1-25; 8:45 am]
BILLING CODE 6560-50-P
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