Proposed Rule2026-17501
Air Plan Approval; Kentucky; Louisville Area Limited Maintenance Plan for the 1997 8-Hour Ozone NAAQS
Primary source
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Published
August 27, 2026
Issuing agencies
Environmental Protection Agency
Abstract
The U.S. Environmental Protection Agency (EPA or Agency) is proposing to approve a State Implementation Plan (SIP) revision submitted by the Commonwealth of Kentucky through the Energy and Environment Cabinet (Cabinet) on behalf of the Louisville Metro Air Pollution Control District (District) via a letter dated June 3, 2024. The SIP revision consists of a Limited Maintenance Plan (LMP) for the Kentucky portion of the bi-state Louisville, Kentucky-Indiana 1997 8- hour ozone maintenance area (the "bi-state Louisville Area"). The Kentucky portion of the bi-state Louisville Area includes the Bullitt, Jefferson, and Oldham Counties of Kentucky (the "Louisville Area"). The EPA is proposing to approve the Louisville Area's LMP because it provides for the maintenance of the 1997 8-hour ozone National Ambient Air Quality Standards (NAAQS) within the bi-state Louisville Area through the end of the second 10-year portion of the maintenance period. The effect of this proposed action would be to make certain commitments related to maintenance of the 1997 8-hour ozone NAAQS in the Louisville Area federally enforceable as part of the Kentucky SIP.
Full Text
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<title>Federal Register, Volume 91 Issue 165 (Thursday, August 27, 2026)</title>
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[Federal Register Volume 91, Number 165 (Thursday, August 27, 2026)]
[Proposed Rules]
[Pages 55294-55299]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-17501]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R04-OAR-2024-0295; FRL-13322-01-R4]
Air Plan Approval; Kentucky; Louisville Area Limited Maintenance
Plan for the 1997 8-Hour Ozone NAAQS
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The U.S. Environmental Protection Agency (EPA or Agency) is
proposing to approve a State Implementation Plan (SIP) revision
submitted by the Commonwealth of Kentucky through the Energy and
Environment Cabinet (Cabinet) on behalf of the Louisville Metro Air
Pollution Control District (District) via a letter dated June 3, 2024.
The SIP revision consists of a Limited Maintenance Plan (LMP) for the
Kentucky portion of the bi-state Louisville, Kentucky-Indiana 1997 8-
hour ozone maintenance area (the ``bi-state Louisville Area''). The
Kentucky portion of the bi-state Louisville Area includes the Bullitt,
Jefferson, and Oldham Counties of Kentucky (the ``Louisville Area'').
The EPA is proposing to approve the Louisville Area's LMP because it
provides for the maintenance of the 1997 8-hour ozone National Ambient
Air Quality Standards (NAAQS) within the bi-state Louisville Area
through the end of the second 10-year portion of the maintenance
period. The effect of this proposed action would be to make certain
commitments related to maintenance of the 1997 8-hour ozone NAAQS in
the Louisville Area federally enforceable as part of the Kentucky SIP.
DATES: Comments must be received on or before September 17, 2026.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R04-
OAR-2024-0295 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from <a href="http://Regulations.gov">Regulations.gov</a>. The 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. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e., on the web, cloud, or other
file sharing system). For additional submission methods, the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
FOR FURTHER INFORMATION CONTACT: Nelsha Athauda, Multi-Air Pollutant
Coordination Section, Air Planning and Implementation Branch, Air and
Radiation Division, U.S. Environmental Protection Agency, Region 4, 61
Forsyth Street SW, Atlanta, Georgia 30303-8960. The telephone number is
(404)-562-9360. Ms. Athauda can also be reached via electronic mail at
<a href="/cdn-cgi/l/email-protection#7514011d140011145b1b1019061d14351005145b121a03"><span class="__cf_email__" data-cfemail="e9889d81889c8d88c7878c859a8188a98c9988c78e869f">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this proposed rule, the use of
``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We use
multiple abbreviations and terms in this proposed rule. While this list
may not be exhaustive, for ease of reading and for reference purposes,
the EPA defines the following terms and acronyms here:
AQS Air Quality System
CAA Clean Air Act
CBI Confidential Business Information
CFR Code of Federal Regulations
CO Carbon Monoxide
DV Design Value
EPA Environmental Protection Agency
FR Federal Register
KIPDA Kentuckiana Regional Planning and Development Agency
LMP Limited Maintenance Plan
MOVES EPA's MOtor Vehicle Emission Simulator
NAAQS National Ambient Air Quality Standard
NEI National Emissions Inventory
NO<INF>X</INF> Nitrogen Oxides
PM<INF>10</INF> Particulate Matter with an aerodynamic diameter less
than 10 microns
ppm Parts per million
RACT Reasonably Available Control Technology
SIP State Implementation Plan
TDM Travel Demand Model
tpsd tons per summer day
VOC Volatile Organic Compounds
Table of Contents
I. Executive Summary
II. Background
III. Kentucky's SIP Submittal
IV. The EPA's Evaluation of Kentucky's SIP Submittal
A. Attainment Emissions Inventory
B. Maintenance Demonstration
C. Monitoring Network and Verification of Continued Attainment
D. Contingency Plan
[[Page 55295]]
V. Transportation Conformity
VI. Proposed Action
VII. Statutory and Executive Order Reviews
I. Executive Summary
In accordance with the Clean Air Act (CAA or Act), the EPA is
proposing to approve the Louisville Area's second 10-year LMP for the
1997 8-hour ozone NAAQS, adopted on June 3, 2024, and submitted to the
Agency as a revision to the Kentucky SIP under a letter dated June 3,
2024.
On April 30, 2004, the bi-state Louisville Area, which is composed
of Bullitt, Jefferson, and Oldham Counties in Kentucky and Clark and
Floyd Counties in Indiana, was designated as nonattainment for the 1997
8-hour ozone NAAQS.\1\ Subsequently, on September 29, 2006, the Cabinet
submitted a redesignation request and the first 10-year maintenance
plan for the Louisville Area. In 2007, the EPA approved the maintenance
plan and redesignated the Louisville Area to attainment for the 1997 8-
hour ozone NAAQS.\2\
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\1\ See 69 FR 23857 (Apr. 30, 2004).
\2\ See 72 FR 36601 (July 5, 2007).
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The Louisville Area LMP for the 1997 8-hour ozone NAAQS, submitted
by the Cabinet on June 3, 2024, is designed to maintain the 1997 8-hour
ozone NAAQS within the Louisville Area through the end of the second
10-year portion of the maintenance period beyond redesignation (through
2027). The EPA is proposing to approve the plan because it meets all
applicable requirements under CAA sections 110 and 175A.
II. Background
In 1979, under CAA section 109, the EPA established primary and
secondary NAAQS for ozone at 0.12 parts per million (ppm), averaged
over a 1-hour period.\3\ On July 18, 1997, the EPA revised the primary
and secondary NAAQS for ozone \4\ to set the acceptable level of ozone
in the ambient air at 0.08 ppm, averaged over an 8-hour period.\5\
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\3\ See 44 FR 8202 (Feb. 8, 1979).
\4\ See 62 FR 38856 (July 18, 1997).
\5\ In March 2008, the EPA completed another review of the
primary and secondary ozone NAAQS and lowered the level for both to
0.075 ppm. See 73 FR 16436 (Mar. 27, 2008). Additionally, in October
2015, the EPA completed another review of the primary and secondary
ozone NAAQS and further lowered the level for both to 0.070 ppm. See
80 FR 65292 (Oct. 26, 2015).
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Following promulgation of a new or revised NAAQS, the EPA is
required by the CAA to designate areas throughout the nation as
attaining or not attaining the NAAQS. On April 30, 2004, the EPA
designated the bi-state Louisville Area, which consists of the Kentucky
counties of Bullitt, Jefferson, and Oldham and the Indiana counties of
Clark and Floyd, as nonattainment for the 1997 8-hour ozone NAAQS.
Those designations became effective on June 15, 2004.\6\
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\6\ See 69 FR 23858 (Apr. 30, 2004).
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The EPA has revised the ozone NAAQS twice since the 1997 standards
were finalized. On July 20, 2012, the EPA designated areas as
unclassifiable/attainment or nonattainment for the 2008 8-hour ozone
NAAQS. The Louisville Area was designated as attainment for that
standard with an effective date of July 20, 2012.\7\ On November 16,
2017, the EPA designated areas for the 2015 8-hour ozone NAAQS. The bi-
state Louisville Area was designated as nonattainment for the 2015 8-
hour ozone NAAQS with an effective date of August 3, 2018.\8\ The EPA
redesignated the Indiana portion of the bi-state Louisville Area to
attainment for the 2015 8-hour ozone NAAQS with an effective date of
July 5, 2022.\9\
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\7\ See 77 FR 30088 (May 21, 2012).
\8\ See 83 FR 25776 (June 4, 2018).
\9\ See 87 FR 39750 (July 5, 2022).
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A State may submit a request that the EPA redesignate a
nonattainment area that is attaining a NAAQS to attainment, and, if the
area has met the criteria described in CAA section 107(d)(3)(E), the
Agency may approve the redesignation request.\10\ One of the criteria
for redesignation is for the area to have an approved maintenance plan
under CAA section 175A. The maintenance plan must demonstrate that the
area will continue to maintain the NAAQS for the period extending ten
years after redesignation, and it must contain such additional measures
as necessary to ensure maintenance and such contingency provisions as
necessary to assure that violations of the NAAQS will be promptly
corrected. Eight years after the effective date of redesignation, the
State must also submit a second maintenance plan to ensure ongoing
maintenance of the NAAQS for an additional ten years pursuant to CAA
section 175A(b) (i.e., ensuring maintenance for 20 years after
redesignation).
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\10\ CAA section 107(d)(3)(E) sets out the requirements for
redesignating a nonattainment area to attainment. They include
attainment of the NAAQS, full approval of the applicable SIP
pursuant to CAA section 110(k), determination that improvement in
air quality is a result of permanent and enforceable reductions in
emissions, demonstration that the State has met all applicable
section 110 and part D requirements, and a fully approved
maintenance plan under CAA section 175A.
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The EPA has published long-standing guidance for States on
developing maintenance plans. The Calcagni memo \11\ provides that
States may generally demonstrate maintenance by 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
projected 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).\12\ The EPA clarified in
three subsequent guidance memos that certain areas can meet the CAA
section 175A requirement to provide for maintenance by showing that
they are unlikely to violate the NAAQS in the future, using information
such as the area design values \13\ when the design values are well
below the standard and have been historically stable.\14\ The EPA
refers to a maintenance plan containing this streamlined demonstration
as an LMP.
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\11\ John Calcagni, Director, Air Quality Management Division,
EPA Office of Air Quality Planning and Standards (OAQPS),
``Procedures for Processing Requests to Redesignate Areas to
Attainment,'' September 4, 1992 (Calcagni memo).
\12\ See Calcagni memo at page 9.
\13\ The ozone design value for a monitoring site is the 3-year
average of the annual fourth-highest daily maximum 8-hour average
ozone concentrations. The design value for an ozone area is the
highest design value of any monitoring site in the area.
\14\ See ``Limited Maintenance Plan Option for Nonclassifiable
Ozone Nonattainment Areas'' from Sally L. Shaver, 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 PM<INF>10</INF> Nonattainment Areas'' 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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The EPA has interpreted CAA section 175A as permitting the LMP
option because CAA section 175A does not define how areas may
demonstrate maintenance, and in the Agency's experience implementing
the various NAAQS, areas that qualify for an LMP and have approved LMPs
have rarely, if ever, experienced subsequent violations of the NAAQS.
As noted in the LMP guidance memoranda, States seeking an LMP must
still submit the 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, a State seeking an
LMP must still submit its section 175A maintenance plan as a revision
to its SIP, with all attendant notice and comment procedures. While the
LMP guidance memoranda were originally written with respect to certain
[[Page 55296]]
NAAQS,\15\ the EPA has extended the LMP interpretation of section 175A
to other NAAQS and pollutants not specifically covered by the previous
guidance memos.\16\
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\15\ The prior memos addressed: unclassifiable areas under the
1-hour ozone NAAQS, nonattainment areas for the PM<INF>10</INF>
(particulate matter with an aerodynamic diameter less than 10
microns) NAAQS, and nonattainment areas for the carbon monoxide (CO)
NAAQS.
\16\ See, e.g., 79 FR 41900 (July 18, 2014) (approval of the
second ten-year LMP for the Grant County 1971 sulfur dioxide
maintenance area).
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In this case, the EPA is proposing to approve the Louisville Area's
LMP because the Commonwealth has shown that ozone concentrations in the
bi-state Louisville Area are well below the 1997 8-hour ozone NAAQS,
have been historically stable, and that the Commonwealth has met the
other maintenance plan requirements. The Cabinet submitted the LMP for
the Louisville Area to fulfill the CAA's second maintenance plan
requirement. The EPA's evaluation of the Louisville Area's LMP is
presented in section IV of this notice of proposed rulemaking, below.
On September 29, 2006, the Cabinet submitted a request to the EPA
to redesignate the Louisville Area, to attainment for the 1997 8-hour
ozone NAAQS. This submittal included a plan, for inclusion in the
Kentucky SIP, to provide for maintenance of the 1997 8-hour ozone NAAQS
in the bi-state Louisville Area through 2017. The EPA approved the
Louisville Area maintenance plan and the Commonwealth's request to
redesignate the Kentucky portion of the bi-state Louisville Area to
attainment for the 1997 8-hour ozone NAAQS, effective August 6,
2007.\17\ Kentucky's June 3, 2024, submittal contains the second 10-
year maintenance plan for the 20-year maintenance period of the 1997 8-
hour ozone NAAQS to ensure continued maintenance for the bi-state
Louisville Area.
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\17\ See 72 FR 36601 (July 5, 2007).
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CAA section 175A(b) requires States to submit a revision to the
first maintenance plan eight years after redesignation to provide for
maintenance of the NAAQS for ten additional years following the end of
the first 10-year period. However, the EPA's final implementation rule
for the 2008 8-hour ozone NAAQS revoked the 1997 8-hour ozone NAAQS and
stated that one consequence of revocation was that areas that had been
redesignated to attainment (i.e., maintenance areas) for the 1997 NAAQS
no longer needed to submit second 10-year maintenance plans under CAA
section 175A(b).\18\
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\18\ See 80 FR 12264, 12315 (Mar. 6, 2015).
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In South Coast Air Quality Management District v. EPA, the United
States Court of Appeals for the District of Columbia Circuit vacated
the EPA's interpretation that, because of the revocation of the 1997 8-
hour ozone NAAQS, second maintenance plans were not required for
``orphan maintenance areas,'' i.e., areas that had been redesignated to
attainment for the 1997 8-hour ozone NAAQS maintenance areas and were
designated attainment for the 2008 ozone NAAQS.\19\ Thus, States with
these ``orphan maintenance areas'' under the 1997 8-hour ozone NAAQS
must submit maintenance plans for the second maintenance period.
Accordingly, on June 3, 2024, Kentucky submitted a second 10-year
maintenance plan for the Louisville Area that shows that the Area is
expected to remain in attainment of the 1997 8-hour ozone NAAQS through
2027.
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\19\ South Coast II, 882 F.3d 1138 (D.C. Cir. 2018).
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In recognition of the continuing record of relatively stable air
quality monitoring data showing ambient 8-hour ozone concentrations in
the Louisville Area well below the 1997 8-hour ozone NAAQS, the Cabinet
chose the LMP option for the development of the second 1997 8-hour
ozone NAAQS maintenance plan.
III. Kentucky's SIP Submittal
As mentioned above, on June 3, 2024, KDAQ submitted the Louisville
Area LMP for the 1997 8-hour ozone NAAQS to the EPA as a revision to
the Kentucky SIP. The submittal includes the LMP, air quality data,
emissions inventory information, and appendices. Appendices to the plan
include monitoring data; documentation of public notice and statement
of consideration; and public hearing minutes.
IV. The EPA's Evaluation of Kentucky's SIP Submittal
The EPA has reviewed the Louisville Area's LMP, which is designed
to maintain the 1997 8-hour ozone NAAQS within the Louisville Area
through the end of the 20-year period beyond redesignation, as required
under CAA section 175A(b). The following is a summary of the EPA's
interpretation of the section 175A requirements \20\ and the Agency's
evaluation of how each requirement is met for the Louisville Area.
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\20\ See Calcagni memo.
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A. Attainment Emissions Inventory
The June 3, 2024, submittal includes an ozone attainment inventory
for the Louisville Area that reflects typical summer day emissions in
2019. The submittal also includes a comparison of the 2019 attainment
emissions inventory to the 2003 attainment inventory developed for the
first 10-year maintenance plan.\21\ Comparing these inventories shows
an overall decrease in emissions. Table 1 presents a summary of these
inventories.
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\21\ For more information on the development of the 2003
emissions inventory, see 72 FR 20966 (Apr. 27, 2007).
Table 1--Attainment Emissions Inventory for 2003 and 2019 in Tons Per Summer Day (tpsd) for the Louisville Area
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NOX VOC
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2003 2019 2003 2019
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Bullitt Total: 10.04 5.77 16.95 19.74
Nonpoint.................................................... 0.11 0.33 3.34 5.03
Nonroad..................................................... 1.81 0.26 1.77 0.55
Onroad...................................................... 7.52 3.67 3.74 1.26
Point....................................................... 0.60 1.51 8.10 12.90
Jefferson Total: 170.76 62.59 80.61 63.05
Nonpoint.................................................... 0.75 6.88 17.33 30.53
Nonroad..................................................... 31.94 3.39 14.31 3.66
Onroad...................................................... 63.29 19.97 25.34 8.41
Point....................................................... 74.78 32.35 23.63 20.45
Oldham Total: 6.22 2.61 7.01 2.80
[[Page 55297]]
Nonpoint.................................................... 0.07 0.41 2.46 1.56
Nonroad..................................................... 1.63 0.35 1.54 0.51
Onroad...................................................... 4.43 1.67 2.29 0.61
Point....................................................... 0.09 0.18 0.72 0.12
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Kentucky Total 187.02 70.97 104.57 85.59
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The Attainment Inventory portion of the June 3, 2024, submittal
describes the methods, models, and assumptions used to develop the 2019
attainment inventory and indicates that this inventory was developed
using the following combination of sources: (1) Data from the 2017
National Emissions Inventory (NEI); \22\ (2) Data required to be
submitted by sources to the District \23\ and the Division; \24\ (3)
Mobile source modeling, using the Kentuckiana Regional Planning and
Development Agency's (KIPDA's) most recent travel demand model (TDM)
along with EPA's MOtor Vehicle Emission Simulator (MOVES) version
3.0.3, which was conducted by KIPDA and the District for the Area; and
(4) EPA's 2016v2 modeling platform.\25\
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\22\ Documentation and data for the 2017 NEI is available at:
<a href="https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data">https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data</a>.
\23\ District Regulation 1.06, available at <a href="https://louisvilleky.gov/air-pollution-control-district/document/regulation106-version-11">https://louisvilleky.gov/air-pollution-control-district/document/regulation106-version-11</a>.
\24\ 401 KAR 52:020, available at <a href="https://apps.legislature.ky.gov/law/kar/401/052/020.pdf">https://apps.legislature.ky.gov/law/kar/401/052/020.pdf</a> and 401 KAR 52:030,
available at <a href="https://apps.legislature.ky.gov/law/kar/401/052/030.pdf">https://apps.legislature.ky.gov/law/kar/401/052/030.pdf</a>.
\25\ Documentation and data for EPA's 2016v2 modeling platform
available at: <a href="https://www.epa.gov/air-emissions-modeling/2016v2-platform">https://www.epa.gov/air-emissions-modeling/2016v2-platform</a>.
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Based on the review of the methods, models, and assumptions used by
Kentucky to develop the volatile organic compounds (VOC) and oxides of
nitrogen (NO<INF>X</INF>) estimates, the EPA proposes to find that the
June 3, 2024, submittal includes a comprehensive, reasonably accurate
inventory of actual ozone precursor emissions in attainment year 2019
and proposes to conclude that the plan's inventories are acceptable for
the purposes of a subsequent maintenance plan under CAA section
175A(b).
B. Maintenance Demonstration
The maintenance demonstration requirement is considered to be
satisfied in an LMP if the air monitoring data for the area that is
well below the level of the NAAQS, that past air quality trends have
been shown to be stable, and that the probability of the area
experiencing a violation over the second 10-year maintenance period is
low.\26\ These criteria are evaluated below.
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\26\ See ``Limited Maintenance Plan Option for Nonclassifiable
Ozone Nonattainment Areas'' from Sally L. Shaver, 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 PM<INF>10</INF> Nonattainment Areas'' from Lydia Wegman,
OAQPS, dated August 9, 2001.
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1. Evaluation of Ozone Concentrations
To attain the 1997 8-hour ozone NAAQS, the three-year average of
the fourth-highest daily maximum 8-hour average ozone concentrations
(design value) at each monitor within an area must not exceed 0.08 ppm.
Based on the rounding convention described in 40 CFR part 50, Appendix
I, the 1997 8-hour ozone NAAQS is attained if the design value is 0.084
ppm or below.
There are currently seven ozone monitors in the bi-state Louisville
Area, one in Bullitt County, Kentucky; one in Oldham County, Kentucky;
three in Jefferson County, Kentucky; one in Clark County, Indiana; and
one in Floyd County, Indiana. Data for four air monitoring sites in
Jefferson County are reported in the table below due to the relocation
of a monitor from Bates Elementary (Air Quality System (AQS) ID: 21-
111-0027) to Carrithers Middle School (AQS ID: 21-111-0080) in
2018.\27\ Table 2 presents the design values (in ppm) for each monitor
in the bi-state Louisville Area over the 2012-2025 period.
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\27\ Page 66 of the 2024 Kentucky Annual Ambient Air Monitoring
Network Plan describes the purpose and details behind the relocation
of the monitor.
Table 2--1997 8-Hour Ozone NAAQS Design Values (DV) (ppm) for Monitors in the Bi-State Louisville Area for the 2012-2025 Time Period
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2010-2012 2011-2013 2012-2014 2013-2015 2014-2016 2015-2017 2016-2018 2017-2019 2018-2020 2019-2021 2020-2022 2021-2023 2022-2024 2023-2025
County AQS Site ID DV DV DV DV DV DV DV DV DV DV DV DV DV DV
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Clark, IN....................................................... 18-019-0008 0.081 0.078 0.072 0.069 0.070 0.071 0.070 0.067 0.065 0.063 0.063 0.066 0.069 0.071
Bullitt, KY..................................................... 21-029-0006 0.075 0.072 0.069 0.065 0.066 0.065 0.066 0.064 0.065 0.064 0.064 0.067 0.067 0.068
Jefferson, KY................................................... 21-111-0027 0.080 0.077 0.071 0.066 0.069 0.069 (*) (*) ......... ......... ......... ......... ......... .........
Jefferson, KY................................................... 21-111-0051 0.079 (* *) (* *) (* *) 0.069 0.068 0.068 0.066 0.065 0.065 0.065 0.068 0.067 0.067
Jefferson, KY................................................... 21-111-0067 0.085 (* *) (* *) (* *) 0.074 0.074 0.073 0.071 0.070 0.069 0.070 0.072 0.075 0.075
Oldham, KY...................................................... 21-185-0004 0.086 0.082 0.074 0.068 0.07 0.068 0.067 0.066 0.065 0.063 0.063 0.065 0.067 0.069
Jefferson, KY................................................... 21-111-0080 ......... ......... ......... ......... ......... ......... (*) (*) 0.067 0.068 0.069 0.070 0.070 0.070
Floyd, IN....................................................... 18-043-0008 0.079 0.078 0.073 0.066 0.068 0.070 0.073 0.070 0.067 0.064 0.064 * * * * * * 0.070
0.066 0.066
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* The Jefferson County, Kentucky, monitor (AQS Site ID: 21-111-0027) was relocated to a new site (AQS ID: 21-111-0080) before the ozone monitoring season in 2018. As a result, neither site had a valid three-year design value during
2016-2018 and 2017-2019.
** Two Jefferson County, Kentucky, monitors (AQS Site ID: 21-111-0051 and AQS Site ID: 21-111-0067) did not meet completeness criteria in 2013. As a result, neither site had a valid three-year design value during 2011-2013, 2012-
2014, and 2013-2015.
*** The Floyd County, Indiana, monitor (formerly AQS Site ID: 18-043-1004) was relocated to a new site (AQS Site ID: 18-043-0008) before the ozone monitoring season in 2023. The EPA approved the combination of data from both sites
into a single site data record for the purpose of calculating design values. The design values shown include data from both monitoring sites before and after the relocation.
[[Page 55298]]
In the bi-state Louisville Area, all current design values are
below 85 percent of the ozone NAAQS,\28\ with the exception of one
Jefferson County monitor (AQS ID: 21-111-0067). The Jefferson County
monitor's 2025 design value is 0.075 ppm, which is 89 percent of the
exceedance levels of the ozone NAAQS. All other monitors in the bi-
state Louisville Area are below this 85 percent threshold. Based on the
weight of evidence in support of Kentucky's submittal, the EPA is
proposing to approve this LMP. No design values in the bi-state
Louisville Area have exceeded the 1997 ozone NAAQS during the 2013-2025
time period depicted in Table 2. The design value data shown in Table 2
illustrates an overall downward trend in ozone levels at each monitor
over this timeframe, and the 20-year maintenance period beyond
redesignation ends in 2027, which leaves only a relatively short amount
of remaining time during which significant increases in ozone levels
are unlikely based on the data in Table 2. Thus, the probability of the
area experiencing a violation during this second maintenance period is
low. These aspects of the EPA's proposed approval are discussed in more
detail below.
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\28\ See ``Limited Maintenance Plan Option for Nonclassifiable
Ozone Nonattainment Areas'' from Sally L. Shaver, OAQPS, dated
November 16, 1994.
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2. Stability of Ozone Levels
As discussed above, the bi-state Louisville Area has maintained
ozone concentrations below the 1997 8-hour ozone NAAQS over the past
twelve 3-year design value periods. Additionally, the design value data
shown in Table 2 illustrates an overall downward trend in ozone levels
at each monitor over this timeframe. Over the past eight years, the
maximum design value increase was 0.008 ppm, which occurred at the
Clark, Indiana, ozone monitor (AQS ID: 18-019-0008) from 0.063 ppm in
the 2019-2021 DV and 2020-2022 DV, to 0.071 in the 2023-2025 DV. After
adding the maximum design value increase of 0.008 ppm to the maximum
most recent design value (0.075 ppm), the resulting 0.083 ppm remains
below the 0.084 ppm threshold to attain the 1997 8-hour ozone NAAQS.
Additionally, the 20-year maintenance period beyond redesignation ends
in 2027, which leaves only a short amount of remaining time during
which significant increases in ozone levels are unlikely based on the
data in Table 2. As a result, the EPA finds that there is a low
probability of the Area violating the 1997 8-hour ozone NAAQS during
this second maintenance period.
C. Monitoring Network and Verification of Continued Attainment
The EPA annually reviews the ozone monitoring network that the
Cabinet operates and maintains in accordance with 40 CFR part 58. This
network is described in the ambient air monitoring network plan that is
developed by the Cabinet and submitted to the EPA annually, following a
public notification and comment process. For further details on
monitoring, the reader is referred to Kentucky's 2025 Ambient Air
Monitoring Network Plan. The Cabinet submitted the 2025 Network Plan on
July 1, 2025, and it received approval from the EPA on October 28,
2025.\29\
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\29\ Kentucky's 2025 Annual Ambient Air Monitoring Network Plan
(submitted to the EPA on July 1, 2025) and the EPA's Approval Letter
(transmitted by October 28, 2025) are both available in the docket
for this proposed action.
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As noted above, the Cabinet's monitoring network in the Louisville
Area has been approved by the EPA in accordance with 40 CFR part 58,
and the Cabinet has committed to continue to maintain a network in
accordance with the EPA requirements. The EPA proposes to find that the
Cabinet's monitoring network is adequate to verify continued attainment
of the 1997 ozone NAAQS in the bi-state Louisville Area.
D. Contingency Plan
CAA section 175A(d) requires that a maintenance plan include
contingency provisions. The purpose of such contingency provisions is
to prevent future violations of the NAAQS or to promptly remedy any
NAAQS violations that might occur during the maintenance period.
The Louisville Area LMP contingency plan includes tracking and
triggering mechanisms to determine when control measures are needed,
and a process for developing and adopting appropriate control measures.
Specifically, any 8-hour ozone monitoring reading of 0.085 ppm or
greater in the bi-state Louisville Area or periodic emissions inventory
updates \30\ that reveal excessive or unanticipated growth greater than
10 percent in either NO<INF>X</INF> or VOC emissions over the
attainment inventory for the bi-state Louisville Area will cause the
Division to evaluate existing control measures to see if any further
emission reduction measures should be implemented at that time.
Implementation of necessary controls in response to an initial
``indicator'' will take place as expeditiously as possible, but no
later than twelve months from the conclusion of the most recent ozone
season (October 31) in which the annual fourth-highest monitored value
of 0.085 ppm or greater occurred.
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\30\ The Air Emissions Reporting Rule requires State and local
agencies to collect and submit criteria pollutant emissions data to
EPA's Emissions Inventory System according to the schedule in 40 CFR
51.30.
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If a three-year average of annual fourth-highest monitored values
of 0.085 ppm or greater (i.e., a violation of the standard) occurs
within the bi-state Louisville Area, an action level response will take
effect. The Division and the District, in conjunction with the
metropolitan planning organization or regional council of governments,
will determine additional control measures needed to ensure future
attainment of the NAAQS for ozone. Appropriate contingency measures
will be selected to be in place within twenty-four months of a
monitored violation.
The contingency measures chosen will be selected based on their
ability to bring the bi-state Louisville Area back into attainment. The
LMP contains the following list of potential contingency measures.
<bullet> Implementation of a program to require additional emission
reductions on stationary sources, including Reasonably Available
Control Technology (RACT) for point sources of VOC and NO<INF>X</INF>,
and, specifically, the adoption of new and revised RACT rules based on
Groups II, III, and IV Control Techniques Guidelines;
<bullet> Implementation of a program to enhance inspection of
stationary sources;
<bullet> Implementation of fuel programs, including incentives for
alternative fuels;
<bullet> Restriction of certain roads or lanes to, or construction
of such roads or lanes for use by, passenger buses or high-occupancy
vehicles;
<bullet> Trip-reduction ordinances;
<bullet> Employer-based transportation management plans, including
incentives;
<bullet> Programs for new construction and major reconstructions of
paths or tracks for use by pedestrians or by non-motorized vehicles
when economically feasible and in the public interest;
<bullet> Implementation of a modern vehicle inspection/maintenance
program;
<bullet> Implementation of diesel retrofit programs, including
incentives for performing retrofits for fleet vehicle operations;
<bullet> Additional engine idling reduction programs.
The Louisville Area's LMP includes updates to the list of potential
contingency measures in the first 10-year maintenance plan. New
potential
[[Page 55299]]
contingency measures include additional engine idling reduction
programs and the implementation of diesel retrofit programs with
incentives for retrofitting fleet vehicles. The second 10-year LMP no
longer identifies programs to limit or restrict vehicle use in downtown
areas or other high-emission zones during peak periods as potential
contingency measures.
The EPA proposes to find that the contingency provisions in
Kentucky's second maintenance plan for the Louisville Area for the 1997
8-hour ozone NAAQS meet the requirements of the CAA section 175A(d).
V. Transportation Conformity
Transportation conformity is required by CAA section 176(c).
Conformity to a SIP means that transportation activities will not
produce new air quality violations, worsen existing violations, or
delay timely attainment of the NAAQS.\31\ The EPA's transportation
conformity rule at 40 CFR part 93, subpart A, requires that
transportation plans, programs, and projects conform to SIPs and
establishes the criteria and procedures for determining whether they
conform.
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\31\ See CAA 176(c)(1)(A) and (B).
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Due to the decision in South Coast Air Quality Management v. EPA,
transportation conformity is not required for the Louisville Area for
the 1997 NAAQS as the entire 1997 Area is encompassed by the
nonattainment area for the 2015 8-hour ozone NAAQS. Therefore, a
demonstration for the less stringent 1997 ozone NAAQS is unnecessary.
The Louisville 2015 NAAQS Area needs to continue to meet all
applicable requirements of the transportation conformity regulations,
including the need for a regional emissions analysis and comparison of
the results of the regional emissions analysis to the applicable motor
vehicle emissions budgets for the 2015 ozone NAAQS. The approved 1997
ozone NAAQS budgets will be used to demonstrate conformity for the 2015
ozone NAAQS until budgets for the 2015 ozone NAAQS are deemed adequate
or approved for the Kentucky portion of the Louisville
Area.<SUP>32 33</SUP>
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\32\ Budgets for the 2015 8-hour ozone NAAQS were deemed
adequate and approved for the Indiana portion of the Louisville
Area. See 87 FR 39750.
\33\ See 40 CFR 93.109(c)(2).
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VI. Proposed Action
Under CAA sections 110(k) and 175A and for the reasons set forth
above, the EPA is proposing to approve the Louisville Area LMP for the
1997 8-hour ozone NAAQS, submitted by the Cabinet on June 3, 2024, as a
revision to the Kentucky SIP. The EPA is proposing to approve the
Louisville Area LMP because it includes an acceptable update of the
various elements of the 1997 8-hour ozone NAAQS maintenance plan
approved by the Agency for the first 10-year period (including
emissions inventory, assurance of adequate monitoring and verification
of continued attainment, and contingency provisions).
The EPA also finds that the Louisville Area qualifies for the LMP
option and that, therefore, the Louisville Area LMP adequately
demonstrates maintenance of the 1997 8-hour ozone NAAQS through
documentation of monitoring data showing design values well below the
NAAQS and continuation of existing control measures. The EPA believes
that the Louisville Area LMP is sufficient to provide for maintenance
of the 1997 8-hour ozone NAAQS in the bi-state Louisville Area over the
remainder of the second 10-year maintenance period, through 2027, and
thereby satisfies the requirements for such a plan under CAA section
175A(b).
VII. 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.\34\ Thus, in reviewing SIP submissions, the EPA's
role is to approve State choices, provided that they meet the criteria
of the CAA. Accordingly, this proposed action merely proposes to
approve State law as meeting Federal requirements and does not impose
additional requirements beyond those imposed by State law. For that
reason, this proposed action:
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\34\ See 42 U.S.C. 7410(k); 40 CFR 52.02(a).
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<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 an Executive Order 14192 (90 FR 9065, February 6,
2025) regulatory action because this action is not significant 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 the 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, Nitrogen dioxide, Ozone,
Reporting and recordkeeping requirements, Volatile organic compounds.
Authority: 42 U.S.C. 7401 et seq.
Dated: August 20, 2026.
Kristy Eubanks,
Deputy Regional Administrator performing the functions and duties of
the Regional Administrator, Region 4.
[FR Doc. 2026-17501 Filed 8-26-26; 8:45 am]
BILLING CODE 6560-50-P
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</html>Indexed from Federal Register on August 27, 2026.
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.