[Federal Register Volume 90, Number 88 (Thursday, May 8, 2025)]
[Proposed Rules]
[Pages 19447-19459]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-07937]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2024-0622; FRL-12746-01-R8]


Air Plan Approval; Colorado; Serious Attainment Plan Contingency 
Measures for the 2008 8-Hour Ozone National Ambient Air Quality 
Standards for the Denver Metro/North Front Range Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve state implementation plan (SIP) submittals under the Clean Air 
Act (CAA) that address contingency measures requirements for the 2008 
ozone National Ambient Air Quality Standards (NAAQS) for the Denver 
Metro/North Front Range (DMNFR) ozone nonattainment area. The 
requirements at issue relate to the area's previous Serious 
nonattainment classification. The EPA is proposing to find that the 
State has met the applicable CAA requirements for Serious area 
contingency measures and is proposing approval of the contingency 
measures SIP submittals, except that we are not taking action on one of 
the two identified contingency measures included in the submittals. In 
addition, the EPA is proposing to approve regulatory revisions that 
Colorado adopted to implement the submitted motor vehicle coating 
contingency measure. The EPA is taking this action pursuant to the CAA.

DATES: Written comments must be received on or before June 9, 2025.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2024-0622 to the Federal Rulemaking Portal: https://www.regulations.gov. Follow the online instructions for submitting 
comments. Once submitted, comments cannot be

[[Page 19448]]

edited or removed from https://www.regulations.gov. 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 https://www.epa.gov/dockets/commenting-epa-dockets.
    Docket: All documents in the docket are listed in the https://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available electronically in 
https://www.regulations.gov. Please email or call the person listed in 
the FOR FURTHER INFORMATION CONTACT section if you need to make 
alternative arrangements for access to the docket.

FOR FURTHER INFORMATION CONTACT: Matthew Lang, Air and Radiation 
Division, EPA, Region 8, Mailcode 8ARD-AQ-R, 1595 Wynkoop Street, 
Denver, Colorado, 80202-1129, telephone number: (303) 312-6709, email 
address: [email protected].

SUPPLEMENTARY INFORMATION: In this document, ``we,'' ``us,'' and 
``our'' refer to the EPA.

Table of Contents

I. What action is the EPA proposing to take?
II. Background
    A. 2008 8-Hour Ozone NAAQS Nonattainment Area
    B. The EPA's November 7, 2023 Final Rule
III. Contingency Measures Requirements
IV. Summary of State's SIP Submittals
    A. Revisions to Regulation 7, Parts A and C and Reorganization 
Into Regulation 25, Parts A and B
    B. 2024 DMNFR Contingency Measures Plan
    1. One Year's Worth of Progress
    2. Contingency Measures Infeasibility Justification
    3. Adopted Contingency Measures
V. Procedural Requirements
VI. The EPA's Evaluation of Colorado's SIP Submittals
    A. Revisions to Regulation 7, Parts A and C and Reorganization 
Into Regulation 25, Parts A and B
    B. 2024 DMNFR Contingency Measures Plan
    1. One Year's Worth of Progress
    2. Contingency Measures Infeasibility Justification
    3. Adopted Contingency Measures
    4. Conclusion
VII. Proposed Action
VIII. Consideration of Section 110(l) of the CAA
IX. Incorporation by Reference
X. Statutory and Executive Order Reviews

I. What action is the EPA proposing to take?

    The EPA is proposing to approve Colorado SIP revisions for three 
submittals related to the Serious area contingency measures requirement 
for the DMNFR area for the 2008 ozone NAAQS. These submittals also 
address certain organizational revisions affecting the submitted 
regulations, including the relocation of existing portions of 
Colorado's Regulation Number 7 (``Reg. 7'') into new standalone 
regulations and renumbering of existing regulatory provisions. On June 
26, 2023, Colorado submitted SIP revisions to address certain Moderate 
and Severe nonattainment requirements for the 2015 and 2008 ozone 
NAAQS, respectively, which included revisions to Reg. 7.\1\ Of 
relevance to this proposed rulemaking, the June 26, 2023 SIP submittal 
identifies motor vehicle coatings emission control requirements as a 
contingency measure for the Moderate ozone nonattainment area plan for 
the DMNFR area for the 2015 ozone NAAQS, but as described below, this 
measure was not triggered by a failure to attain with respect to the 
2015 ozone NAAQS Moderate nonattainment plan requirements in the DMNFR 
area. The State is now repurposing the requirement as a contingency 
measure for the Serious ozone nonattainment area plan requirements for 
the 2008 ozone NAAQS.
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    \1\ June 2023 SIP Submittal, Document Set 1 of 7, ``Submittal 
Letter to EPA_Ozone SIP.'' The letter is dated June 22, 2023, but 
the SIP was submitted to EPA on June 26, 2023.The June 2023 SIP 
Submittal was deemed complete on September 7, 2023.
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    On May 23, 2024, Colorado submitted SIP revisions to the existing 
approved Reg. 7 to separate out certain components of Reg. 7 and create 
Regulation Number 24 (``Reg. 24''), Regulation Number 25 (``Reg. 25''), 
and Regulation Number 26 (``Reg. 26'') as new standalone 
regulations.\2\ On April 2, 2025, Colorado submitted SIP revisions to 
address the contingency measures requirement for Serious ozone 
nonattainment areas for the 2008 ozone NAAQS, which includes associated 
revisions to Reg. 25.\3\ The EPA had finalized a disapproval of a prior 
Colorado SIP submittal with respect to the 2008 ozone NAAQS Serious 
area contingency measures requirement in November 2023.\4\ In this 
rulemaking, we are proposing action only on the portions of the June 
26, 2023, May 23, 2024, and April 2, 2025 submittals related to 
contingency measures, including associated revisions to Reg. 7, parts A 
and C as well as Reg. 25, parts A and B. The relevant portions of these 
submittals implement motor vehicle coatings emission control 
requirements, including provisions that function as a contingency 
measure for the Serious nonattainment classification of the DMNFR area 
for the 2008 ozone NAAQS.
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    \2\ May 2024 SIP Submittal, ``Submittal Letter to EPA_Regs 7, 
24, 25, 26_signed.'' The letter is dated May 21, 2024, but the SIP 
was submitted to EPA on May 23, 2024. The May 2024 SIP Submittal was 
deemed complete by operation of law on November 23, 2024.
    \3\ April 2025 SIP Submittal, Document Set 1 of 2, ``Signed 
Submittal Letter to EPA.''
    \4\ Final Rule, Air Plan Approval and Disapproval; Colorado; 
Serious Attainment Plan Elements and Related Revisions for the 2008 
8-Hour Ozone Standard for the Denver Metro/North Front Range 
Nonattainment Area; 88 FR 76676 (Nov. 7, 2023).
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    More specifically, the EPA is also proposing to approve the June 
26, 2023 revisions to Reg. 7, Part A that define new and existing 
sources and the applicability of requirements based on the 
nonattainment area in which they are located; revisions to Reg. 7, Part 
C, section I.P. regarding motor vehicle coating requirements that 
include provisions for those requirements to function as a contingency 
measure; and revisions to Reg. 7, Part C, section I.A. that update 
reference dates to the Code of Federal Regulations (CFR). In addition, 
the EPA is proposing to approve the May 23, 2024 revisions reorganizing 
Reg. 7, parts A and C into Reg. 25, parts A and B as well as the April 
2, 2025 revisions to Reg. 25, parts A and B concerning motor vehicle 
coating provisions. The remaining revisions from the June 26, 2023, May 
23, 2024 and April 2, 2025 submittals not described above, and not 
identified in table 3 of this preamble, will be addressed by the EPA in 
future rulemakings.
    If the EPA finalizes this rulemaking as proposed, Colorado will 
have corrected the deficiency identified in the EPA's November 7, 2023 
disapproval with respect to the Serious area contingency measures 
requirement for the 2008 ozone NAAQS. Consistent with

[[Page 19449]]

applicable sanctions regulations,\5\ in this issue of the Federal 
Register the EPA is concurrently making an interim final determination 
to defer application of CAA section 179 sanctions associated with the 
November 7, 2023 action. The deferral is based on this proposal to 
approve SIP revisions from Colorado to resolve the contingency measures 
requirement deficiency that was the basis for the November 7, 2023 
disapproval. If the EPA does not finalize this approval as proposed and 
instead disapproves or proposes to disapprove these SIP revisions, then 
the offset sanction under CAA section 179(b)(2) for permitting of new 
or modified sources would apply in the DMNFR area on the later of: (1) 
the date the EPA issues such a proposed or final disapproval; or (2) 
June 7, 2025 (i.e., 18 months from the effective date of the finding 
that started the original sanctions clock).\6\ Subsequently, highway 
sanctions under section 179(b)(1) would apply in the DMNFR area six 
months after the date the offset sanction applies.\7\
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    \5\ 40 CFR 52.31(d)(2)(i).
    \6\ See id. In this case, the finding that started the original 
sanctions clock was the disapproval issued on November 7, 2023, 
which was effective on December 7, 2023.
    \7\ See id.
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    The basis for our proposed action is discussed in more detail 
below. Technical information that the EPA is relying on is contained in 
the docket, available at https://www.regulations.gov, Docket ID No. 
EPA-R08-OAR-2024-0622.

II. Background

A. 2008 8-Hour Ozone NAAQS Nonattainment Area

    On March 12, 2008, the EPA revised both the primary and secondary 
NAAQS for ozone to a level of 0.075 parts per million (ppm) (based on 
the annual fourth-highest daily maximum 8-hour average concentration, 
averaged over 3 years).\8\ The 2008 ozone NAAQS retains the same 
general form and averaging time as the 0.08 ppm NAAQS set in 1997, but 
is set at a more protective level. Specifically, the 2008 8-hour ozone 
NAAQS is met when the 3-year average of the annual fourth-highest daily 
maximum 8-hour average ambient air quality ozone concentrations is less 
than or equal to 0.075 ppm.\9\ Effective July 20, 2012, the EPA 
designated any area as nonattainment that was violating the 2008 8-hour 
ozone NAAQS based on the three most recent years (2008-2010) of air 
monitoring data.\10\
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    \8\ Final rule, National Ambient Air Quality Standards for 
Ozone, 73 FR 16436 (March 27, 2008). The EPA has since further 
strengthened the ozone NAAQS, but the 2008 8-hour standard remains 
in effect. See Final Rule, National Ambient Air Quality Standards 
for Ozone, 80 FR 65292 (Oct. 26, 2015).
    \9\ 40 CFR 50.15(b).
    \10\ Final rule, Air Quality Designations for the 2008 Ozone 
National Ambient Air Quality Standards, 77 FR 30088 (May 21, 2012).
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    Ozone nonattainment areas are classified based on the severity of 
their ambient ozone levels, as determined using the area's design 
value. The design value is the 3-year average of the annual fourth-
highest daily maximum 8-hour average ozone concentration at a 
monitoring site.\11\ In our July 20, 2012 action, the EPA designated 
the DMNFR area as nonattainment and classified the area as 
Marginal.\12\ The DMNFR area did not attain the 2008 8-hour ozone NAAQS 
by the applicable Marginal area attainment deadline, and accordingly 
was reclassified as Moderate.\13\ After not attaining the 2008 ozone 
NAAQS for subsequent attainment dates, the area was reclassified to 
Serious, and then to Severe nonattainment status.\14\
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    \11\ 40 CFR part 50, appendix I.
    \12\ Final rule, Air Quality Designations for the 2008 Ozone 
National Ambient Air Quality Standards, 77 FR 30088 (May 21, 2012) 
at 30110. The nonattainment area includes Adams, Arapahoe, Boulder, 
Broomfield, Denver, Douglas and Jefferson Counties, and portions of 
Larimer and Weld Counties. See 40 CFR 81.306.
    \13\ Final rule, Determinations of Attainment by the Attainment 
Date, Extensions of the Attainment Date, and Reclassification of 
Several Areas for the 2008 Ozone National Ambient Air Quality 
Standards, 81 FR 26697 (May 4, 2016).
    \14\ Final rule, Finding of Failure to Attain and 
Reclassification of Denver Area for the 2008 Ozone National Ambient 
Air Quality Standard, 84 FR 70897 (Dec. 26, 2019); Final rule, 
Determinations of Attainment by the Attainment Date, Extensions of 
the Attainment Date, and Reclassification of Areas Classified as 
Serious for the 2008 Ozone National Ambient Air Quality Standards, 
87 FR 60926 (Oct. 7, 2022); see 40 CFR 81.306.
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B. The EPA's November 7, 2023 Final Rule

    Although the DMNFR area is currently classified as Severe 
nonattainment for the 2008 ozone NAAQS, the present action pertains 
only to the contingency measures requirement for the prior Serious 
nonattainment classification. Among the requirements for Serious ozone 
nonattainment area plans, states must submit SIP provisions that 
constitute contingency measures that would go into effect and result in 
additional emission reductions in the event that the EPA determines the 
area fails to attain the applicable standard by the attainment date (in 
this case, the 2008 ozone NAAQS), make Reasonable Further Progress 
(RFP) toward attainment, or meet any applicable RFP milestone. As 
described above, the EPA disapproved a Colorado SIP submittal intended 
to meet the Serious area contingency measures requirement for the 2008 
ozone NAAQS on November 7, 2023. The EPA has previously taken action to 
approve or conditionally approve SIP submittals to address the State's 
other Serious ozone nonattainment area requirements for the 2008 ozone 
NAAQS.\15\
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    \15\ See 88 FR 29827, 88 FR 76676, and 88 FR 85511.
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III. Contingency Measures Requirements

    Under CAA section 172(c)(9), states are required to submit an 
attainment plan SIP that includes contingency measures to be 
implemented if the area fails to meet RFP or to attain the NAAQS by the 
applicable attainment date. For ozone nonattainment areas classified 
Serious or above, CAA section 182(c)(9) further specifies that states 
must include contingency measures to be implemented if the area fails 
to meet any applicable milestone. An EPA determination that a state 
failed to meet an RFP milestone or to attain the NAAQS by the 
applicable attainment date is referred to as a ``triggering event'' 
because it triggers the requirement to implement the contingency 
measures specified in the SIP.
    The information provided below is explained in greater detail in 
EPA's ``Guidance on the Preparation of State Implementation Plan 
Provisions that Address the Nonattainment Area Contingency Measure 
Requirements for Ozone and Particulate Matter'' \16\ (``2024 
Contingency Measures Guidance''). The purpose of contingency measures 
is to continue progress in reducing emissions while a state revises its 
SIP to meet a missed RFP requirement or to correct a failure to attain 
a NAAQS.\17\ As part of a contingency measures SIP submittal, states 
should estimate the amount of anticipated emission reductions that the 
contingency measures would achieve if triggered. If a state is unable 
to identify and adopt contingency measures that would provide for 
approximately one year's worth of emission reductions, then the state 
may provide an

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``infeasibility justification'' that demonstrates that a lesser amount 
of emission reductions is appropriate because additional contingency 
measures are infeasible in the area.\18\ The EPA does not read the 
statute to require contingency measures that are not feasible, i.e., to 
require the imposition of control measures regardless of technological 
or cost constraints.
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    \16\ ``Guidance on the Preparation of State Implementation Plan 
Provisions that Address the Nonattainment Area Contingency Measure 
Requirements for Ozone and Particulate Matter'' (Dec. 3, 2024), 
available at https://www.epa.gov/air-quality-implementation-plans/final-contingency-measures-guidance.
    \17\ See Proposed Rule, Conditional Approval; Contingency 
Measure State Implementation Plan for the 2008 Ozone Standard; San 
Joaquin Valley, California, 89 FR 85119, 85122 (Oct. 25, 2024); 
Proposed Rule, Air Plan Approval; AK, Fairbanks North Star Borough; 
2006 24-Hour PM 2.5 Serious Area and 189(d) Plan, 90 FR 1600, 1623 
(Jan. 8, 2025); see also 2024 Contingency Measures Guidance at 9.
    \18\ 2024 Contingency Measures Guidance at 29-40.
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    To satisfy the requirements of CAA sections 172(c)(9) and 
182(c)(9), contingency measures should be fully adopted rules or 
control measures that are ready to be implemented upon a triggering 
event.\19\ They consist of control measures for the area that are not 
otherwise required to meet other attainment plan requirements (e.g., to 
meet reasonably available control measure or reasonably available 
control technology (RACT) requirements). To comply with CAA sections 
172(c)(9) and 182(c)(9), contingency measures must be both conditional 
and prospective. That is, they must be measures that go into effect and 
achieve emission reductions in the event of a future triggering event, 
but not before the triggering event. The EPA cannot approve already 
implemented measures, i.e., measures that have already achieved 
emission reductions or that are already adopted into law and will 
achieve reductions regardless of whether there is a future triggering 
event, as contingency measures, even if already implemented measures 
would achieve surplus emission reductions beyond those necessary to 
meet other applicable CAA requirements.\20\
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    \19\ See Sierra Club v. EPA, 21 F.4th 815, 827 (D.C. Cir. 2021) 
(``The Act's plain text expressly provides that valid contingency 
measures become operative only when the triggering conditions set 
forth in the statute occur, and not any earlier.'').
    \20\ See Sierra Club, 21 F.4th at 827-28 (holding that the 
specific wording of sections 172(c)(9) and 182(c)(9) unambiguously 
requires that contingency measures be ``conditional and 
prospective,'' and that already implemented measures are not 
measures ``to take effect'' only if and when the contingency 
occurs).
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    The EPA recommends that contingency measures achieve emissions 
reductions equivalent to one year's worth of ``progress.'' \21\ The EPA 
recommends that one year's worth of ``progress'' be calculated by 
determining the average annual reductions between the base year 
emissions inventory and the projected attainment year emissions 
inventory, determining what percentage of the base year emissions 
inventory this amount represents, and then applying that percentage to 
the projected attainment year emissions inventory to determine the 
amount of reductions needed to ensure ongoing progress.
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    \21\ See 89 FR at 85123-85124 (explaining one year's worth of 
progress in connection with proposed approval of San Joaquin Valley 
contingency measures); 90 FR at 1624-1625 (explaining one year's 
worth of progress in connection with proposed approval of Fairbanks 
contingency measures); 2024 Contingency Measures Guidance at 28-29.
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    As to the time within which emission reductions from contingency 
measures should occur, the EPA recommends that emission reductions 
should occur within one year of the triggering event or up to two years 
of the triggering event if there are insufficient contingency measures 
available to achieve the recommended amount of emission reductions 
within one year.\22\ The EPA's longstanding recommendation is that 
contingency measures take effect within 60 days of the triggering 
event.
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    \22\ 2024 Contingency Measures Guidance at 10.
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    As explained previously, if after an adequate evaluation a state is 
unable to identify contingency measures that would provide emission 
reductions achieving approximately one year's worth of progress, then 
the EPA recommends that the state provide an infeasibility 
justification for a lesser amount, which the state should support with 
an infeasibility justification. This infeasibility justification should 
explain and document the state's evaluation of existing and potential 
control measures relevant to the appropriate source categories and 
pollutants in the nonattainment area, and the state's conclusions 
regarding whether such measures are feasible as contingency measures in 
the area.
    The statutory scheme contemplates that a state will have approved 
contingency measures in place in the SIP and ready to be implemented in 
the event of a triggering event before the triggering event occurs. 
That is, contingency measures that are conditional and prospective upon 
a triggering event. In this case, the State did not have such approved 
contingency measures in place at the time of the relevant triggering 
event, which was EPA's determination that the State failed to attain 
the 2008 ozone NAAQS in the DMNFR area by the Serious attainment 
deadline.\23\ But the State is still required to provide such 
contingency measures to the EPA. As discussed further below, when the 
State is developing and submitting required contingency measures for a 
triggering event that has already occurred, the timeframe for achieving 
reductions should be evaluated based on the adoption date of the 
measure rather than the now-passed trigger date.
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    \23\ See 87 FR 60926.
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IV. Summary of State's SIP Submittals

    On June 26, 2023, Colorado submitted SIP submittals related to 
Moderate and Severe nonattainment plan requirements for the 2015 and 
2008 ozone NAAQS, respectively, which included revisions to Reg. 7 
establishing a motor vehicle coating contingency measure for the DMNFR 
nonattainment area for the 2015 ozone NAAQS. On June 8, 2024, before 
the EPA proposed action on this submitted contingency measure and 
before the Moderate area attainment date for the 2015 NAAQS, Colorado 
requested voluntary reclassification from Moderate to Serious 
nonattainment for the 2015 ozone NAAQS for this area. On July 24, 2024, 
the EPA granted the voluntary reclassification request.\24\ Prior to 
the voluntary reclassification, EPA did not take action on the 2023 
contingency measures submittal and Colorado was not required to 
implement the motor vehicle coating control measure as a contingency 
measure. In the April 2, 2025 submittal, Colorado has included 
regulatory revisions to repurpose the motor vehicle coatings measure as 
a Serious area contingency measure with respect to the 2008 ozone NAAQS 
contingency measures requirement. Because the EPA has not yet approved 
the original motor vehicle coating measure as a contingency measure, 
the Agency must act on both the initial regulatory language for the 
motor vehicle coatings requirements from the June 26, 2023 SIP 
submittal and subsequent revisions as described in Colorado's April 
2025 SIP Submittal.
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    \24\ See 89 FR 59832.
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    On May 23, 2024, Colorado submitted revisions to Reg. 7 to separate 
out certain components of Reg. 7 to create Reg. 24, Reg. 25, and Reg. 
26 as new standalone regulations. On April 2, 2025, Colorado submitted 
the 2024 DMNFR Contingency Measures Plan as a revision to the Colorado 
SIP.\25\ The State developed the 2024 DMNFR Contingency Measures Plan 
to address the EPA's November 7, 2023 disapproval of the State's 
submittal intended to meet the 2008 ozone NAAQS Serious area 
contingency measures requirements.\26\ In this rulemaking, we are 
proposing approval of only the portions of the June 26, 2023, May 23, 
2024, and April 2, 2025 SIP submittals related to contingency

[[Page 19451]]

measures requirements for the 2008 ozone NAAQS, and of associated 
revisions to Reg. 7, Part A; Reg. 7, Part C, sections I.A. and I.P.; 
Reg. 25, Part A; and Reg. 25, Part B, sections I.A. and I.P. The EPA 
will address the remaining revisions from the June 26, 2023, May 23, 
2024, and April 2, 2025 SIP submittals in future rulemakings.
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    \25\ April 2025 SIP Submittal, Document Set 1 of 2, ``Technical 
Support Documents'' at 490-561 (``2024 DMNFR Contingency Measures 
Plan'').
    \26\ See 88 FR 76676.
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A. Revisions to Regulation 7, Parts A and C and Reorganization Into 
Regulation 25, Parts A and B

    In the June 26, 2023 submittal, among other revisions, Reg. 7, Part 
C, section I.P. was added and Reg. 7, Part C, section I.A.3.a. was 
updated to reflect the applicable EPA reference method used to 
demonstrate compliance, as revised in the CFR on March 23, 2021.\27\ 
Reg. 7, Part C, section I.P. established surface coating requirements 
for motor vehicle materials, including provisions that would function 
as a contingency measure that would be triggered within 60 days after 
the effective date of a finding by the EPA of failure to attain by the 
2015 ozone NAAQS Moderate ozone attainment date of August 3, 2024.
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    \27\ June 2023 SIP Submittal, Document Set 5 of 7, ``Reg Lang & 
SBAP Adopted_R7'' at 25-31.
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    Distinct from the aforementioned motor vehicle coating 
requirements, the June 26, 2023 submittal included revisions to the 
applicability and general provisions found in Reg. 7, Part A that are 
relevant to requirements across Reg. 7. These revisions are not 
specific to the contingency measures requirement that the EPA is 
addressing in this rulemaking, but the EPA is proposing approval of 
these revisions because the revised sections are included in the 
reorganization of Reg. 7 parts A and C into Reg. 25, parts A and B. 
This includes revisions expanding the general applicability of 
provisions in Reg. 7 to sources in the portion of northern Weld County 
within the DMNFR ozone nonattainment area for the 2015 ozone NAAQS that 
are not included in the DMNFR ozone nonattainment area for the 2008 
ozone NAAQS, revisions clarifying the dates defining new and existing 
sources for respective ozone standards, and revisions updating the 
regulation to refer to a newer version of applicable EPA reference 
methods used to demonstrate compliance.
    The June 26, 2023 submittal includes revisions to Reg. 7 in 
addition to those identified above, but the EPA is not proposing action 
on those revisions in this rulemaking. They will instead be addressed 
by the EPA in separate rulemakings at a later date. As described 
previously, the rule provisions of the June 26, 2023 submittal for 
motor vehicle coating materials, and which were structured as a 
contingency measure for the DMNFR nonattainment area for the 2015 ozone 
NAAQS, were no longer required with respect to the Moderate area 
classification for that NAAQS following the EPA granting Colorado's 
voluntary reclassification request. Included with its April 2, 2025 
submittal, the State adopted revisions described below to repurpose 
these emission control requirements as a Serious nonattainment area 
contingency measure for the 2008 ozone NAAQS.
    In the State's May 23, 2024 submittal, Reg. 7 was retitled from 
``Control of Ozone via Ozone Precursors and Control of Hydrocarbons via 
Oil and Gas Emissions (Emissions of Volatile Organic Compounds (VOC) & 
Nitrogen Oxides (NOX))'' to ``Control of Emissions from Oil 
and Gas Emissions Operations.'' In addition, the State moved Reg. 7, 
Part C, sections I.A. and I.P.; copied over portions of Reg. 7, Part A 
concerning applicability/general provisions; and relocated other rule 
sections from Reg. 7 to the newly established Reg. 25 for the ``Control 
of Emissions from Surface Coating, Solvents, Asphalt, Graphic Arts and 
Printing, and Pharmaceuticals.'' \28\ The State intended these 
revisions to narrow Reg. 7 to be primarily focused on oil and gas 
emission controls, and to relocate provisions addressing other source 
categories from Reg. 7, including coatings, solvents, and similar 
sources, to Reg. 25.
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    \28\ May 2024 SIP Submittal, ``Adopted Language_R7'' at 71-77, 
``Adopted Language_R25'' at 40-46. As part of the May 23, 2024, 
submittal, other provisions, apart from Reg. 7, Part C, section 
I.P., were removed from Reg. 7, but the relocation of those 
revisions are not being addressed in this action.
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    After adopting Reg. 25, on April 2, 2025, the State submitted a 
third SIP submittal to the EPA, which included revisions to parts A and 
B of Reg. 25. This includes revisions to Reg. 25, Part A at section 
II.C.2. concerning general emission limitations for all new sources, 
and which are clerical in nature and reflect that the listed 
regulations are not applicable to all emission sources. The revisions 
to Reg. 25, Part B, section I.P. included: (1) in section I.P.7., 
correcting the numbering, with references in several subsections 
changed from I.P.6. to I.P.7.; (2) in sections I.P.1.b., I.P.3., 
I.P.4.b. and I.P.7., changing ``sixty days'' to ``May 1, 2026''; 
changing ``moderate'' to ``serious''; changing ``2015'' to ``2008'' in 
relation to the relevant ozone NAAQS; and (3) adding section I.P.8., 
which is related to reporting requirements.\29\ The revisions to 
Regulation 25, Part B, section I.P. from Colorado's April 2, 2025 
submittal were made, in part, to require that the motor vehicle 
coatings contingency measure contained therein be repurposed as a 
contingency measure for the State's 2008 ozone NAAQS Serious area plan 
for the DMNFR nonattainment area. The motor vehicle coatings 
contingency measure was originally adopted for the purposes of the 
State's 2015 ozone NAAQS Moderate nonattainment area plan. The April 2, 
2025 SIP submittal included revisions to Reg. 7, Part B, section 
III.C.4. identifying requirements for pneumatic controllers as a 
contingency measure, but the EPA is not acting on this portion of the 
SIP submittal in this rulemaking. Several additional revisions 
unrelated to the contingency measures requirement are included in 
Colorado's June 26, 2023, May 23, 2024, and April 2, 2025 SIP 
submittals, but the EPA is not addressing these revisions in this 
rulemaking and will act on them in a separate action.
---------------------------------------------------------------------------

    \29\ April 2025 SIP Submittal, Document Set 1 of 2, ``Reg 
Language Adopted R25 (redline)'' at 4-11.
---------------------------------------------------------------------------

B. 2024 DMNFR Contingency Measures Plan

    The 2024 DMNFR Contingency Measures Plan submitted to the EPA 
identifies two contingency measures that Colorado deemed feasible for 
the Serious area attainment plan for the 2008 ozone NAAQS.\30\ 
Additionally, Colorado's contingency measures submission includes an 
infeasibility justification to justify its submission of contingency 
measures that achieve less than one year's worth of progress. The 
State's evaluation of the feasibility of specific measures is presented 
in greater detail in the ``Strategy Summary'' included as a part of the 
supporting technical information in the State's April 2, 2025 SIP 
Submittal.\31\
---------------------------------------------------------------------------

    \30\ 2024 DMNFR Contingency Measures Plan at 20-22.
    \31\ April 2025 SIP Submittal, Document Set 1 of 2, ``Technical 
Support Documents'' at 562-584 (``Strategy Summary''). Subsequent 
citations to the Strategy Summary use the page numbers within that 
document; so, for example, ``Strategy Summary at 1'' refers to the 
562nd page of the Technical Support Documents file.

---------------------------------------------------------------------------

[[Page 19452]]

1. One Year's Worth of Progress
    Section 3.1 of the 2024 DMNFR Contingency Measures Plan includes 
the State's calculations for determining emission reductions 
representing ``one year's worth'' of progress for the area.\32\ The 
emission reductions representing one year's worth of emission 
reductions progress as determined by Colorado are 8.9 tons per day of 
NOX and 14.2 tons per day of VOC.
---------------------------------------------------------------------------

    \32\ 2024 DMNFR Contingency Measures Plan at 18-19.
---------------------------------------------------------------------------

2. Contingency Measures Infeasibility Justification
    Colorado reviewed each source category in the 2026 emissions 
inventory for NOX and VOC that the State developed for other 
attainment planning requirements, in order to identify feasible control 
measures that could serve as contingency measures.\33\ Table 1 provides 
the major categories from the 2026 emissions inventory; the inventory 
is provided in greater detail in appendix C of the 2024 DMNFR 
Contingency Measures Plan. The State's submittal explains that ``[e]ach 
category was vetted for any potential strategies that are regulatory, 
non-regulatory, and tax or grant funded that may be SIP-eligible.'' 
\34\ The State identified potential and current emission reduction 
measures as part of their analysis. (Current emission reduction 
measures have already been implemented, and therefore need not be 
evaluated as a part of an infeasibility justification. But the 
evaluation should consider whether additional requirements are feasible 
for a given source category.)
---------------------------------------------------------------------------

    \33\ Id. at 43-49.
    \34\ Id. at 27.
---------------------------------------------------------------------------

    After Colorado disqualified already adopted measures and measures 
that the State lacked authority to adopt, the State evaluated the 
feasibility of candidate measures (control measures that may be 
appropriate as contingency measures if they are determined to be 
technologically and economically feasible) based on the time required 
to implement the measure, technological/economic feasibility, and 
whether a measure met legal criteria for adoption. Based on this 
analysis, the 2024 DMNFR Contingency Measures Plan identifies two 
control strategies for EPA evaluation as contingency measures, as 
described in section IV.B.3. of this preamble, and provides an 
infeasibility justification to show that its 2024 DMNFR Contingency 
Measures Plan is approvable despite providing less than the recommended 
amount of emission reductions, due to a lack of feasible measures in 
the DMNFR nonattainment area.

         Table 1--DMNFR 2026 Emissions Inventory of NOX and VOC
                             [Tons per day]
------------------------------------------------------------------------
               Source type                      NOX             VOC
------------------------------------------------------------------------
Point...................................            19.6            21.5
Area/Nonpoint...........................             0.3            66.3
On-road Mobile..........................            21.7            27.0
Nonroad Mobile..........................            34.6            47.4
Oil & Gas...............................            68.4            90.4
                                         -------------------------------
    Total...............................           144.5           252.7
------------------------------------------------------------------------

    The 2024 DMNFR Contingency Measures Plan describes various measures 
that the State has already implemented (referred to as ``on-the-books'' 
measures), several of which are state-only requirements, but which are 
not candidate contingency measures because ``they are already 
implemented.'' \35\ Colorado's 2024 Contingency Measures Plan further 
evaluates candidate measures for feasibility with respect to the 
appropriate time within which a contingency measure should achieve 
emission reductions.
---------------------------------------------------------------------------

    \35\ Id. at 31.
---------------------------------------------------------------------------

    The State also evaluated whether the potential contingency measures 
that it identified are subject to technological or economic factors 
that would render a candidate measure infeasible as a contingency 
measure.\36\ Finally, Colorado evaluated the feasibility of potential 
measures as contingency measures by considering whether they would be 
``permanent, enforceable, quantifiable, and surplus,'' including 
whether a measure ``is otherwise ineligible because of federal 
preemption.'' \37\
---------------------------------------------------------------------------

    \36\ Id. at 34-35.
    \37\ Id. at 36-39.
---------------------------------------------------------------------------

Feasibility Analysis
    Colorado evaluated potential contingency measures for feasibility 
and summarized the measures the State deemed infeasible.\38\ The State 
evaluated measures across the five major source categories within the 
State's emission inventory in the DMNFR nonattainment area for the 2008 
ozone NAAQS: point, area, on-road mobile, nonroad mobile, and oil and 
gas sources.
---------------------------------------------------------------------------

    \38\ See Strategy Summary.
---------------------------------------------------------------------------

    With respect to point sources, Colorado considered non-oil and gas 
point sources (the State evaluated oil and gas point sources 
separately) through evaluation of existing stationary source 
regulations.\39\ Colorado identified the existing stationary source 
regulations in Regs. 3, 6, 7, 8, 23, 24, 25, and 26, including both 
state-only and SIP-approved control requirements. The 2024 DMNFR 
Contingency Measures Plan identifies these existing requirements as not 
being candidates to satisfy the contingency measures requirement for 
several reasons, principally because they are already adopted, 
implemented, and achieving emission reductions (whether approved into 
the SIP or on a state-only basis). These control measures may also be 
required to meet other nonattainment SIP requirements or present 
difficulties in meeting SIP creditability requirements.
---------------------------------------------------------------------------

    \39\ 2024 DMNFR Contingency Measures Plan at 43-45.
---------------------------------------------------------------------------

    Among other specific contingency measures considered for the 
stationary point source sector, Colorado evaluated the feasibility of 
implementing a minor source emission offset program, but determined 
that it would be infeasible to implement and achieve emission 
reductions within two years, given the volume of stationary sources 
that would be affected.\40\ The State also considered the feasibility 
of establishing boiler emission limitations such as those established 
by rules in neighboring Utah, but found that it has already effectively 
implemented requirements

[[Page 19453]]

comparable to the Utah boiler rules.\41\ Colorado also examined the 
scope of existing rules in the SIP to meet RACT requirements, and 
determined that it has already adopted requirements for ``minor source 
RACT'' \42\ as part of its construction permit program.\43\ A more 
detailed accounting of the specific measures for the point source 
category that the State considered is included in appendix D to the 
2024 DMNFR Contingency Measures Plan as well as in the Strategy Summary 
technical support document.
---------------------------------------------------------------------------

    \40\ Strategy Summary at 6.
    \41\ Id. at 21.
    \42\ CAA ozone RACT requirements only apply to major sources of 
NOX or VOC, as well as sources covered by a Control 
Techniques Guideline, see CAA secs. 182(b)(2), 182(f). Minor source 
RACT is therefore generally not required under the CAA, but 
Colorado's SIP-approved minor source RACT program establishes 
control requirements for permitting non-exempt minor sources. This 
``minor source RACT'' should not be confused with RACT 
determinations made by a state to meet CAA requirements, which the 
EPA must evaluate and take a regulatory action on.
    \43\ 2024 DMNFR Contingency Measures Plan at 30.
---------------------------------------------------------------------------

    Colorado also evaluated potential contingency measures for oil and 
gas sources. This evaluation included the potential for prohibiting 
venting of gas associated with blowdowns during the ozone season as 
well as implementing best management practices in response to ozone 
advisories that request that operators take voluntary measures to 
reduce emissions on days with forecasted high ozone. The State deemed 
these two measures infeasible as contingency measures based on the 
economic feasibility on a cost per ton basis of prohibiting venting to 
the atmosphere associated with blowdowns,\44\ and challenges concerning 
enforceability with respect to quantifying emission reductions from 
voluntary best management practices.\45\
---------------------------------------------------------------------------

    \44\ See Regional Air Quality Council's Blowdowns Control 
Strategy Overview available at https://raqc.org/episodic-emissions-venting-and-blowdowns/ and in the docket for this proposed 
rulemaking.
    \45\ Strategy Summary at 4, 6, and 13.
---------------------------------------------------------------------------

    In the 2024 DMNFR Contingency Measures Plan, the State further 
described the existing requirements for oil and gas sources that could 
not be candidate contingency measures because they are already adopted, 
which include requirements for leak detection and repair, hydrocarbon 
liquid loadout from storage tanks, flowback vessels, and natural-gas 
reciprocating internal combustion engines (RICE).
    Colorado included an evaluation of area source measures, including 
for cannabis cultivation operations, asphalt formulation restrictions, 
non-fumigant pesticide requirements, and emission reductions from 
livestock waste, as well as an evaluation of existing rules in other 
states. In the 2024 DMNFR Contingency Measures Plan and Strategy 
Summary, the State justifies its finding of infeasibility as to 
emission control requirements for cannabis cultivation operations and 
hot mix asphalt plants on the basis that the State could not feasibly 
achieve further emission reductions within two years.\46\ Colorado 
explains that cultivation operations involve a large number of small 
operators with limited experience with the regulatory process. There is 
an incomplete data record concerning asphalt plants, of which there are 
no major sources in the nonattainment area. These factors contribute to 
the inability of the State to develop rules for these categories to be 
adopted and achieve emission reductions within two years. Colorado's 
submittal characterizes potential emission control requirements for 
livestock waste emissions and non-fumigant pesticide requirements as 
being infeasible due to legal constraints, including the lack of 
statutory authority for the State to impose such measures on 
agricultural sources.\47\ Regarding asphalt formulation restrictions, 
Colorado justifies infeasibility based on technological considerations 
due to the impact of regional altitude on paving operations.\48\
---------------------------------------------------------------------------

    \46\ Strategy Summary at 1 and 14.
    \47\ Id. at 14.
    \48\ Id.
---------------------------------------------------------------------------

    The State also evaluated mobile source control measures, including 
for both on-road and nonroad mobile sources, as potential contingency 
measures.\49\ The State's 2024 DMNFR Contingency Measures Plan 
describes the difficulty in identifying potential contingency measures 
for nonroad sources, in particular given Colorado's lack of authority 
to impose regulatory requirements on certain sources due to federal 
preemption, which limits the pool of candidate measures from the mobile 
source category. In addition to measures that are non-regulatory in 
nature and for which it would be difficult to quantify anticipated 
emission reductions, and measures implemented in other areas that the 
State deemed infeasible due to timing constraints, the State evaluated 
the feasibility of indirect source rule requirements, including those 
that would apply to sources that drive significant mobile source 
activity, as well as potential emission control requirements for lawn 
and garden equipment. Colorado determined the indirect source rules it 
considered to be infeasible as contingency measures due to the State's 
inability to accelerate ongoing research and data collection with 
respect to developing such rules, which would not be completed in time 
for the measure to be implemented and achieve emission reductions 
within two years.\50\ The State also explains in the 2024 DMNFR 
Contingency Measures Plan that prohibitions on gasoline-powered lawn 
and garden equipment sales have already been adopted, with emission 
reductions to be achieved in 2025, and therefore this measure is 
already implemented and disqualified as a candidate contingency 
measure.\51\
---------------------------------------------------------------------------

    \49\ 2024 DMNFR Contingency Measures Plan at 46-48.
    \50\ Strategy Summary at 3.
    \51\ Id.
---------------------------------------------------------------------------

3. Adopted Contingency Measures
    Colorado identified two control measures as contingency measures 
for purposes of the 2008 ozone NAAQS in the DMNFR Serious nonattainment 
area, and submitted these to the EPA for evaluation and inclusion into 
the SIP: (1) an existing state-only requirement for retrofitting 
pneumatic controllers at upstream oil and gas facilities which the EPA 
is not proposing action on in this rulemaking, and (2) a rule for 
control of VOC emissions from motor vehicle coating facilities 
including VOC content limitations, control efficiency requirements, and 
periodic reporting. A summary of the two measures identified by 
Colorado is below. Colorado also determined the expected emission 
reductions from these measures, which are presented in table 2.

[[Page 19454]]



         Table 2--Emissions Reductions From Identified Measures
                           [Tons per day] \a\
------------------------------------------------------------------------
           Contingency measure                  NOX             VOC
------------------------------------------------------------------------
Pneumatic Controller Retrofit...........            0.00            4.37
Motor Vehicle Coatings..................            0.00            0.54
                                         -------------------------------
    Total...............................            0.00            4.91
------------------------------------------------------------------------
\a\ 2024 DMNFR Contingency Measures Plan, section 4., table 3.

    As stated previously, the EPA is not acting on the pneumatic 
controller retrofit contingency measure in this action and therefore is 
not evaluating the measure further as part of this rulemaking. Our 
proposed approval of Colorado's 2024 DMNFR Contingency Measures Plan is 
based solely on the motor vehicle coatings measure described below and 
the infeasibility justification.
Motor Vehicle Coatings
    Colorado's June 26, 2023 SIP submittal included requirements to 
reduce VOC emissions from motor vehicle coating facilities, which the 
State initially intended for use as a contingency measure for the 
Moderate nonattainment area plan for the DMNFR area for the 2015 ozone 
NAAQS.\52\ The measure was not triggered with respect to the 2015 ozone 
NAAQS.\53\ With Colorado's April 2, 2025 SIP submittal, the State 
adopted revisions to require that the motor vehicle coating control 
measure be repurposed as a contingency measure for the DMNFR Serious 
nonattainment area for the 2008 ozone NAAQS.\54\ Under Reg. 25, Part B, 
section I.P.3., this contingency measure would require the State to 
implement VOC content limitations for motor vehicle coatings, which 
would apply to manufacturing for sale as well as to the sale, supply, 
offer for sale, or distribution for sale of such coatings. Under this 
measure, motor vehicle coating facilities must use products that meet 
VOC content limitations or apply emission controls with a control 
efficiency of 90% or greater. The revisions to Reg. 25, Part B, section 
I.P. also include recordkeeping and reporting requirements to ensure 
that upon triggering, affected sources maintain records that document 
the VOC content of products used, and periodically report those records 
to the Colorado Air Pollution Control Division: annually for facilities 
with VOC emissions greater than 2.7 tons per 12-month rolling period, 
or semiannually with the operating permit report for facilities with 
emissions greater than 25 tons per year.\55\
---------------------------------------------------------------------------

    \52\ June 2023 SIP Submittal, Document Set 5 of 7, ``Reg Lang & 
SBAP Adopted_R7'' at 25-31.
    \53\ Although the vehicle coatings measure was included as a 
contingency measure in the Moderate area SIP for the 2015 NAAQS, 
before the area's Moderate attainment date the area was reclassified 
to Serious for the 2015 NAAQS in response to a request from the 
State for voluntary reclassification. Final Rule, Clean Air Act 
Reclassification; Colorado; Reclassification of the Denver Metro/
North Front Range 2015 Ozone Nonattainment Area to Serious, 89 FR 
59832 (July 24, 2024). As a result, the 2015 Moderate contingency 
measure for failure to attain was never triggered.
    \54\ April 2025 SIP Submittal, Document Set 1 of 2, ``Reg 
Language Adopted R25 (redline)'' at 4-11.
    \55\ Id. at 10.
---------------------------------------------------------------------------

    Colorado's June 26, 2023 submittal explains that the motor vehicle 
coatings contingency measure is based on the California Air Resource 
Board (CARB) Suggested Control Measure for Automotive Coatings, which 
``achieves additional reductions of VOCs from automotive coatings 
beyond EPA's national automobile refinish rule.'' \56\ As shown in 
table 2, when fully implemented, the measure would achieve VOC emission 
reductions of 0.54 tpd. The EPA is proposing approval of the motor 
vehicle coatings contingency measure.
---------------------------------------------------------------------------

    \56\ June 2023 SIP Submittal, Document Set 5 of 7, ``Reg Lang & 
SBAP Adopted_R7'' at 123.
---------------------------------------------------------------------------

V. Procedural Requirements

    The CAA requires that states meet certain procedural requirements 
before submitting a SIP revision to the EPA, including the requirement 
that states adopt SIP revisions after reasonable notice and public 
hearing.\57\ Colorado adopted the June 26, 2023 submittal following a 
September 17, 2022 notice of rulemaking in the Denver Post and a 
December 13-16, 2022 rulemaking hearing.\58\ Colorado adopted the May 
23, 2024 submittal following a January 21, 2023 notice of rulemaking in 
the Denver Post and an April 20, 2023 rulemaking hearing.\59\ Colorado 
adopted the April 2, 2025 submittal following an August 17, 2024 notice 
of rulemaking in the Denver Post and a December 18-20, 2024 rulemaking 
hearing.\60\
---------------------------------------------------------------------------

    \57\ CAA section 110(a)(2), 42 U.S.C. 7410(a)(2).
    \58\ June 2023 SIP Submittal, Document Set 1 of 7, ``Denver Post 
Legal Ad''.
    \59\ May 2024 SIP Submittal, ``Denver Post Legal Ad''.
    \60\ April 2025 SIP Submittal, Document Set 1 of 2, ``Denver 
Post Legal Ad''.
---------------------------------------------------------------------------

VI. The EPA's Evaluation of Colorado's SIP Submittals

A. Revisions to Regulation 7, Parts A and C and Reorganization Into 
Regulation 25, Parts A and B

    As discussed in section IV.A. of this document, Colorado's June 26, 
2023 submittal added motor vehicle coating requirements in Reg. 7, Part 
C as a new section I.P., which included provisions that the State 
structured to serve as a contingency measure for the Moderate 
nonattainment area plan with respect to the 2015 ozone NAAQS. The June 
26, 2023 submittal also revised Reg. 7, Part A concerning applicability 
and general provisions that apply across Reg. 7, including the relevant 
motor vehicle coating requirements. The EPA is proposing to approve 
these revisions from the June 26, 2023 submittal. The EPA is not 
proposing action on revisions to other sections of Reg. 7, Part C from 
the June 26, 2023 submittal besides those described above and will take 
action on them in a future rulemaking.
    Furthermore, the EPA is proposing to approve the revisions from the 
May 23, 2024 submittal that duplicate portions of Reg. 7 Part A in Reg. 
25 Part A, and relocate Reg. 7 Part C requirements into Reg. 25 Part B. 
Reg. 7, Part A concerns ``Applicability and General Provisions'' that 
apply across Reg. 7, but only the pieces of Reg. 7, Part A relevant to 
the control of emissions from surface coating, solvents, asphalt, 
graphic arts and printing, and pharmaceuticals are included in the 
newly established Reg. 25, Part A. Reg. 7, Part A is not being removed 
from Reg. 7 given its applicability to the sections of Reg. 7 that are 
not being relocated to standalone regulations. Because the EPA is not 
yet taking action on all of the June 26, 2023 revisions to Reg. 7, Part 
C, we are not taking action to relocate these provisions to Reg. 25, 
Part B in this action and will propose action on the

[[Page 19455]]

relocation of these requirements in a future rulemaking.
    The EPA also is proposing to approve revisions from the April 2, 
2025 submittal including the clerical revision to Reg. 25, Part A, 
section II.C.2.; the corrected numbering of Reg. 25, Part B, section 
I.P.7.; and the addition of reporting provisions related to the VOC 
content of products used at motor vehicle coating facilities in Reg. 
25, Part C, section I.P.8. Lastly, because the motor vehicle coatings 
contingency measure was never triggered for the Moderate DMNFR 
nonattainment area for the 2015 ozone NAAQS (see discussion above at 
sections I. and IV.), the EPA proposes to approve the revisions to Reg. 
25, Part B, section I.P. in the April 2, 2025 submittal that serve to 
repurpose the motor vehicles coating measure as a contingency measure 
for the 2008 ozone NAAQS.
    In summary, the EPA is proposing to approve the revisions to Reg. 
7, Part A concerning applicability and general provisions; the addition 
of Reg. 7, Part C, section I.P. motor vehicle coating requirements; a 
revision to Reg. 7, Part C, section I.A.3.a. updating a reference date; 
the copying over, with minor revisions, of Reg. 7 Part A to Reg. 25, 
Part A; the relocation of Reg. 7, Part C, sections I.A and I.P to Reg. 
25, Part B, sections I.A. and I.P.; the revision to Reg. 25, Part A, 
section II.C.2.; and the revisions to Reg. 25, Part B, section I.P. 
Given that the revisions that the EPA is evaluating span multiple SIP 
submittals from Colorado, we have included table 3 detailing the 
revisions from each submittal that we are proposing to approve in this 
document. The remainder of the revisions included with each submittal 
that we are not proposing action on in this proposed rulemaking will be 
addressed by the EPA in separate rulemakings at a later date.

 Table 3--Summary of EPA's Proposed Approval of Revisions to Regulations
                                7 and 25
------------------------------------------------------------------------
                                         Revisions included in the EPA's
               Submittal                        proposed approval
------------------------------------------------------------------------
June 26, 2023..........................  Reg. 7, Part A, sections
                                          I.A.1.a, I.B.2.a.(i)-(iii),
                                          I.B.2.c, I.B.2.d,
                                          I.B.2.d.(iii)-(iv), I.B.2.e,
                                          II.A.13-18, II.C.1; Reg. 7,
                                          Part C, section I.A.3.a., I.P.
May 23, 2024...........................  Reg. 7, Part C, section I.P;
                                          Reg. 25, Part A; Reg. 25, Part
                                          B, sections I.A., I.P.;
                                          appendix D-E
April 2, 2025..........................  Reg. 25, Part A, section
                                          II.C.2.; Reg. 25, Part B,
                                          sections I.P.1.b., I.P.3.,
                                          I.P.4.b., I.P.7.a.,
                                          I.P.7.a.(vi), I.P.7.b., I.P.8.
------------------------------------------------------------------------
Note: At this time, the EPA is not proposing action on any of the
  revisions included in the June 26, 2023, May 23, 2024, and April 2,
  2025 submittals besides those identified in table 3. Additionally,
  those sections marked as ``state-only'' are not included for
  incorporation into the SIP. Therefore, the EPA is not proposing action
  on these sections, and any such sections which were relocated from
  Reg. 7 to separate a separate regulation will continue to be ``state-
  only.''

B. 2024 DMNFR Contingency Measures Plan

1. One Year's Worth of Progress
    The EPA has reviewed the calculations in the 2024 DMNFR Contingency 
Measures Plan, as summarized in section IV.B.1. of this document, and 
is proposing to find that the State calculated one year's worth of 
progress for NOX and VOC for the 2008 ozone NAAQS in a 
manner consistent with the EPA's recommendations.
2. Contingency Measures Infeasibility Justification
    The EPA has reviewed the State's infeasibility justification 
submitted to support its determination that there are no feasible 
control measures that could be adopted as contingency measures in 
addition to the motor vehicle coatings measure. The EPA has reviewed 
the processes used by Colorado to assess a range of potential measures 
across the stationary, area, mobile, and oil and gas source categories. 
For the reasons explained below, and considering the relevant emission 
sources and other facts specific to this nonattainment area, the EPA is 
proposing to find that the motor vehicle coatings contingency measure 
together with the State's infeasibility justification satisfies the 
Serious ozone nonattainment area contingency measures requirement under 
CAA sections 172(c)(9) and 182(c)(9) for the DMNFR area with respect to 
the 2008 ozone NAAQS.
    Colorado evaluated other potential contingency measures and 
justified its determination of infeasibility, where applicable, using 
EPA-recommended procedures.\61\ As described in section IV.B. of this 
proposed rule, Colorado evaluated several potential control measures 
across the source categories from the State's emission inventory for 
VOC and NOX source categories in the DMNFR area, including 
point, area, nonroad/on-road mobile, and oil and gas sources. After 
setting aside measures that it has already adopted and implemented as 
state-only provisions or to fulfill other SIP requirements, and 
measures for which there are constraints for adoption concerning 
federal preemption and are therefore not candidates for contingency 
measures, the State made feasibility determinations based on whether 
the remaining candidate measures could be implemented and achieve 
emission reductions within two years, and whether the measures were 
technologically and economically feasible.\62\
---------------------------------------------------------------------------

    \61\ 2024 DMNFR Contingency Measures Plan at 23-26.
    \62\ Id at 29-30.
---------------------------------------------------------------------------

    While air agencies do not need to evaluate measures that they do 
not have the legal authority to implement, the EPA recommends that an 
infeasibility justification include a description of any such measures 
that were recommended by the public or are being implemented elsewhere, 
and an explanation of why the air agency lacks the legal authority to 
implement them.\63\ The EPA is proposing to find that Colorado 
reasonably excluded certain mobile source control measures from 
consideration as candidate contingency measures due to difficulty in 
ensuring such measures are not federally preempted. This includes 
emission standards for new motorcycles, emission standards for new off-
road compression ignition engines, zero-emission off-road equipment 
requirements, zero-emission cargo handling equipment requirements, 
retirement of older diesel locomotives, evaporative emission standards, 
and a prohibition on adding Tier 2 engines to fleets.\64\ These control 
measures may be directly preempted; if not, the additional complexity 
involved in ensuring that a potential regulation is not preempted would 
prevent timely implementation of the measure to satisfy the Serious 
nonattainment area contingency measures requirement for the DMNFR area 
for the 2008 ozone NAAQS.
---------------------------------------------------------------------------

    \63\ See 2024 Contingency Measures Guidance at 39.
    \64\ Strategy Summary at 16, 18, and 20.
---------------------------------------------------------------------------

    The EPA is proposing to determine that the emission reductions that 
could be achieved for this nonattainment area from livestock waste 
emission reduction measures like diet manipulation and manure 
management practices would be

[[Page 19456]]

difficult to quantify over the two-year timeframe in which reductions 
from contingency measures should be achieved, and therefore would not 
be appropriate candidates as contingency measures. Regarding pesticide 
application, associated emissions represent a negligible amount of the 
emission inventory for the DMNFR area. Therefore, the EPA is proposing 
to find that the pesticide application category produces negligible 
emissions, and that control measures for the category need not be 
considered further for purposes of the contingency measures 
requirement.
    The EPA agrees with Colorado's assessment that emission reductions 
in the SIP must be permanent, enforceable and quantifiable. In 
particular, contingency measures must be surplus over and above what is 
required for other nonattainment plan requirements. Accordingly, the 
EPA is proposing to find that Colorado reasonably excluded certain 
potential measures from consideration as candidate contingency measures 
due to challenges concerning SIP creditability. This includes measures 
where there is limited ability to quantify associated emission 
reductions over the two-year timeframe in which reductions from 
contingency measures should be achieved, like zero-fare transit, anti-
idling programs, an incentive program for electric vehicles/charging 
stations, planting of lower-VOC tree species, an incentive program 
providing financial assistance following failed vehicle emission tests, 
a heavy-duty truck engine chip retrofit program, and an incentive 
program to replace older light-duty vehicles.\65\ While the EPA agrees 
that these measures or types of programs may result in emission 
reductions, we see no basis to conclude that such measures could be 
developed for this nonattainment area in a way that would support their 
use as contingency measures. In particular, it would be difficult to 
design these incentive-based measures in a way that would allow them to 
achieve quantifiable reductions within the timeframe in which 
reductions from contingency measures should be achieved. To the extent 
these measures require funding for their implementation, the necessity 
to authorize such funding could further delay the implementation of 
such measures, making them further inappropriate for consideration as 
contingency measures for this area.\66\
---------------------------------------------------------------------------

    \65\ Strategy Summary at 8-10 and 14-15.
    \66\ A potential measure may also be infeasible if it requires 
program funding to be available upon triggering the contingency 
measure, but the funding or irrevocable funding commitment cannot be 
secured prior to the time the state submits, and the EPA approves, 
the contingency measure. Securing program funding or irrevocable 
funding commitments in advance for a contingency measure that may 
never be triggered may be a challenge for states.
---------------------------------------------------------------------------

    If a triggering event occurs before an air agency adopts measures 
to satisfy the contingency measures plan requirement, the timeframe for 
achieving reductions (one year; if necessary, two years) should be 
evaluated based on the adoption date of the measure rather than the 
now-passed trigger date.\67\ Thus, in this situation, we do not 
consider the past triggering event date of November 7, 2022 (the date 
of EPA's finding that the DMNFR area failed to attain the 2008 ozone 
NAAQS) the relevant starting point for the two-year period for: (1) 
identifying the time window during which contingency measures should 
achieve emission reductions in order to be creditable toward one year's 
worth of progress, and (2) identifying the time window for a measure to 
be deemed infeasible if it cannot be implemented within such 
period.\68\
---------------------------------------------------------------------------

    \67\ See 2024 Contingency Measures Guidance at 46 n. 92.
    \68\ Colorado has included an evaluation of feasibility with 
respect to timing using both 2 years beginning with the original 
2022 triggering date, as well as the EPA's recommended evaluation of 
2 years from adoption.
---------------------------------------------------------------------------

    Technological feasibility includes consideration of factors such as 
operating procedures, raw materials requirements, physical plant 
layout, and adverse environmental impacts such as water pollution, 
waste disposal, and energy requirements that would negate the 
environmental benefit of the emissions control. Colorado determined 
that implementing standards for materials to reduce VOC emissions from 
the use of cutback/emulsified asphalt would not be technologically 
feasible given the impact of altitude on paving operations. The EPA is 
proposing to find that Colorado provided an appropriate justification 
for the exclusion of the measure based on technological infeasibility. 
As described previously and evaluated below, technological 
infeasibility also encompasses the inability to implement a measure and 
achieve emission reductions from the measure in a suitable timeframe 
for contingency measures. In this evaluation, we have separated the 
consideration of timing of emission reductions from the broader 
technological infeasibility categorization to better characterize 
Colorado's analysis.
    The EPA considers measures to be technologically infeasible if they 
could not be implemented and achieve emission reductions in two years. 
Colorado's 2024 DMNFR Contingency Measures Plan includes information on 
the lack of available underlying data for source categories, and other 
considerations for certain source types that the State determined would 
preclude a full consideration of how candidate measures for such 
categories could be developed and implemented, and whether such 
measures would be technologically and economically feasible. For 
example, Colorado determined that for the following potential control 
measures the pool of affected sources consists of a relatively large 
number of facilities, including small operations with minimal 
experience with regulatory requirements. These potential control 
measures would include measures for cannabis cultivation operations, 
diesel inspection/maintenance (I/M) programs for NOX, an 
indirect source rule for nonroad equipment, a minor source offset 
program, and heavy equipment usage restrictions. The EPA is proposing 
to concur with Colorado's determination that such characteristics 
preclude a full consideration of how the potential measures could be 
developed and implemented for this area, and whether such measures 
would be technologically and economically feasible, within the two-year 
timeframe that control measures would need to achieve emission 
reductions. While adequate information may not presently be available 
to move forward with the potential measures, these measures may become 
feasible as additional information becomes available to Colorado.
    As explained previously, in this circumstance where the triggering 
event for the required contingency measures is in the past, we consider 
the two-year timeframe applied from adoption of a candidate measure 
appropriate. It is still important for a state to have measures that 
will serve the purpose of achieving the additional emission reductions 
that the contingency measures were intended to achieve, had a state 
adopted contingency measures as part of the attainment plan SIP 
submittal or at least in advance of the triggering event.
    Accordingly, we are proposing to find that Colorado adequately 
assessed the feasibility of potential control measures as contingency 
measures. Colorado followed a process to address the contingency 
measures requirement that included (1) identifying candidate 
contingency measures, (2) assessing the feasibility of each candidate 
measure, and (3) providing a infeasibility justification for each 
candidate measure explaining why the State rejected it as infeasible as 
a contingency measure for

[[Page 19457]]

the Serious DMNFR nonattainment area under the 2008 ozone NAAQS.\69\ 
Concerning the control measures identified in Colorado's Strategy 
Summary, we are proposing to find that Colorado appropriately excluded 
certain control measures (i.e., determined that the measures are not 
candidate contingency measures) according to the criteria identified in 
table 4 and adequately demonstrated infeasibility for the remaining 
candidate measures according to the criteria identified in table 5.
---------------------------------------------------------------------------

    \69\ 2024 DMNFR Contingency Measures Plan at 23-26.

  Table 4--2024 DMNFR Contingency Measures Plan Identification of Non-
                           Candidate Measures
------------------------------------------------------------------------
                                  Identified control        The EPA's
    Rationale for exclusion            measures            evaluation
------------------------------------------------------------------------
Already Implemented Measures..  Lower VOC Content       These are
                                 Consumer Products/AIM   already
                                 Coatings; Enhanced      implemented
                                 Vehicle I/M Program;    measures;
                                 Diesel I/M Program;     whether
                                 Clean Fuel Fleet        approved into
                                 Equivalent; Advanced    the SIP,
                                 Clean Cars II           promulgated on
                                 Standards; Low Reid     a state-only
                                 Vapor Pressure (RVP)/   basis, or are
                                 Reformulated Gasoline   otherwise in
                                 Standards;              effect and
                                 Prohibitions for Lawn/  achieving
                                 Garden Equipment;       emission
                                 Stage I Vapor           reductions,
                                 Recovery at Gas         they are
                                 Stations; Widen CTG     ineligible for
                                 VOC RACT                purposes of
                                 Applicability;          contingency
                                 Regional Haze SIP       measures.\a\
                                 Provisions; Expand      Therefore, the
                                 Use of Alternative      EPA is
                                 Fuels in Government     proposing to
                                 and Private Fleets;     find Colorado's
                                 Road Use                exclusion of
                                 Restrictions; Clean     the identified
                                 Air Fleets Diesel       measures as
                                 Retrofits; Electric     candidate
                                 Vehicle Group           measures to
                                 Purchase Program;       address
                                 Alternative Fuel        emissions from
                                 Vehicle Tax Credit;     the relevant
                                 Electric Car Share      source
                                 Program; Commercial     categories is
                                 Lawn and Garden         appropriate.
                                 Program; Building and
                                 Appliance Efficiency
                                 Standards; Emission
                                 Controls for
                                 Municipal Solid Waste
                                 Landfills; Diesel
                                 Idling Rule; Emission
                                 Standards for Space
                                 and Water Heaters.
Federal Preemption /SIP         Low-Emissions Diesel    Colorado's
 Creditability.                  Fuel; Reduce Public     infeasibility
                                 Transit Fares;          justification
                                 Increase Public         includes
                                 Transit Service;        federally
                                 Employer-based          preempted
                                 Transportation          measures and
                                 Management Plans/       measures for
                                 Incentives; Expanded    which there is
                                 Commuter Trip           difficulty in
                                 Reduction Program;      the associated
                                 Increased/Permanent     emission
                                 Funding for Zero Fare   reductions
                                 Initiative and          meeting the
                                 Bicycle/Walking         permanent,
                                 Infrastructure; Limit   enforceable,
                                 Sections of Metro       and
                                 Area to Non-motorized   quantifiable
                                 Use; Limit/Restrict     requirements
                                 Vehicle Use in          for SIP
                                 Downtown Areas; High    creditability
                                 Occupancy/Shared Ride   as a
                                 Program; Secure         contingency
                                 Bicycle Storage; Anti-  measure in the
                                 idling Programs;        DMNFR area. The
                                 Charge Ahead Electric   EPA is
                                 Vehicle Charging        proposing to
                                 Station Program; Mow    find Colorado's
                                 Down Pollution Lawn     demonstration
                                 Mower Exchange;         reasonably
                                 Mandate Use-based       excludes these
                                 Vehicle Insurance;      measures as
                                 Increase State Tax on   candidate
                                 Fuel; Local             measures to
                                 Government Diesel       address
                                 Equipment               emissions from
                                 Specifications;         the relevant
                                 Commercial Diesel       source
                                 Best Practices;         categories.
                                 Mobile Source Credits
                                 in Nonattainment New
                                 Source Review;
                                 Voluntary/Mandatory
                                 Emission Reduction
                                 Action Days; Work
                                 Crew Carpooling; Oil
                                 and Gas Best
                                 Management Practices:
                                 Defer Haul Trips,
                                 Altered Vehicle Fleet
                                 Maintenance,
                                 Additional Leak
                                 Detection and Repair,
                                 Defer Liquid Hauling
                                 to/from Field,
                                 Postpone Well
                                 Unloading Activities,
                                 Reschedule Pipeline
                                 Maintenance, Vapor
                                 Return on Truck
                                 Loading, Setting Pump
                                 Units Ahead of Ozone
                                 Season, Grouping
                                 Maintenance
                                 Activities, Delay
                                 Compression Unit
                                 Start Up, Improve
                                 Chemical Storage; Eco-
                                 driving Best
                                 Practices; Boating
                                 Restrictions; Diesel
                                 Vehicle Best
                                 Management Practices;
                                 Out of Area
                                 Inspection and Driver
                                 Education; Low-VOC
                                 Tree Species; Diesel
                                 Engine Chip Reflash;
                                 Regional Diesel Fuel;
                                 Car Scrap Programs
                                 (Vehicle Exchange
                                 Colorado, Clean Cars
                                 4 all, Clean Vehicle
                                 Rebate); CARB Clean
                                 Off-Road Fleet
                                 Recognition Program;
                                 San Joaquin Valley
                                 (SJV) Hybrid and Zero-
                                 Emission Truck and
                                 Bus Voucher Incentive
                                 Project; Low RVP
                                 Gasoline/Low Emission
                                 Diesel in Nonroad
                                 Vehicles and
                                 Equipment;
                                 Evaporative Emission
                                 Standards for
                                 Recreational Boats;
                                 Urban Heat Island/
                                 Tree Canopy.
------------------------------------------------------------------------
\a\ Note that accelerating the implementation of a control requirement
  (e.g., control measures that would have been implemented at some point
  in the future to meet other attainment plan requirements but that
  could be implemented earlier upon a triggering event so that upon
  triggering, reductions would occur in the two-year window) may still
  be approvable as a contingency measure.


       Table 5--2024 DMNFR Contingency Measures Plan Infeasibility
                          Justification Summary
------------------------------------------------------------------------
                               Identified control
 Rationale for infeasibility        measures        The EPA's evaluation
------------------------------------------------------------------------
Technological/Economic......  Episodic/Seasonal     The EPA is proposing
                               Restrictions on       to find Colorado
                               Operation of          appropriately
                               Industrial,           determined that the
                               Commercial, Oil and   listed measures are
                               Gas Operations;       infeasible as
                               Prohibition of        contingency
                               Certain Oil and Gas   measures on the
                               Operations during     basis of
                               Ozone Season;         technological and/
                               Asphalt Formulation   or economic
                               Paving                infeasibility.
                               Restrictions;
                               Colorado Department
                               of Public Health
                               and Environment
                               (CDPHE) Extended
                               Air Quality
                               Forecasting.

[[Page 19458]]

 
Inability to Implement and    Cannabis Cultivation  For several
 Achieve Emission Reductions   Operations; Diesel    measures, Colorado
 within Two Years.             I/M NOX Testing       describes the
                               Program; Indirect     present lack of
                               Source Rule Nonroad   data available to
                               Equipment; Flaring    make determinations
                               Minimization          on technological or
                               Requirements; Oil     economic
                               and Gas RICE Rule;    feasibility, which
                               Minor Source          would, in several
                               Emission Offset       instances, require
                               Program Including     engaging with
                               for Well Production   businesses
                               Facilities;           consisting of small
                               Reassessment of Oil   operators with
                               and Gas NOX/VOC       relative
                               Emissions Fees;       unfamiliarity with
                               Trip Reduction        the regulatory
                               Ordinances; Heavy-    process. Where
                               Equipment Use         adequate technical
                               Restrictions;         data is
                               Control of            unavailable, and
                               Emissions from Hot    which would
                               Mix Asphalt Plants;   preclude a full
                               Sale and              consideration of
                               Installation of       how candidate
                               Aftermarket           measures for such
                               Catalytic Converter   categories could be
                               Model Rule            developed and
                               Expansion; CARB On-   implemented, and
                               Road Motorcycles      whether such
                               Emission Standards;   measures would be
                               CARB Clean Miles      technologically and
                               Standard; CARB        economically
                               Transport             feasible, such
                               Refrigeration Unit    measures may be
                               Regulation Part 2;    infeasible as
                               CARB In-Use Off-      contingency
                               Road Diesel Fueled    measures.
                               Fleets Regulation;    Therefore, the EPA
                               CARB Large Spark-     proposes to find
                               Ignition Engine       Colorado's
                               Fleet Requirements;   infeasibility
                               CARB Tier 5 Off-      justification
                               Road New              approvable in this
                               Compression-          regard.
                               Ignition Engine
                               Standards; CARB Off-
                               Road Zero-Emissions
                               Targeted
                               Manufacturer Rule;
                               CARB Cargo Handling
                               Equipment
                               Requirements;
                               Accelerated Intro
                               to Cleaner Line-
                               Haul Locomotives;
                               Additional
                               Evaporative Vehicle
                               Emission Standards;
                               Tier 3 or Newer
                               Nonroad Equipment
                               Including
                               Agricultural
                               Equipment/Rec
                               Vehicle Emission
                               Standards/Clean
                               Construction
                               Policies; Utah
                               Commercial Cooking
                               Rule; Model Rule
                               for Reducing VOC
                               Emissions from
                               Adhesives and
                               Sealants; CARB 1,3-
                               Dichloropropene
                               Health Risk
                               Mitigation, SJV In-
                               Use Locomotive
                               Regulation; Utah
                               Appliance Pilot
                               Light Rule.
------------------------------------------------------------------------

    Furthermore, although not directly addressed in Colorado's 
infeasibility justification, the EPA evaluated the stringency of the 
State's existing SIP-approved emission limitations for combustion 
equipment in Regulation 26, Part B, section II.A.4. (previously 
Regulation 7, Part E, section II.A.4.). This includes emission 
limitations for boilers, stationary combustion turbines, RICE, and 
process heaters. The EPA has previously determined that these emission 
limitations constitute RACT as required by the CAA for major stationary 
sources of NOX. While an emission limitation constituting 
RACT does not in itself preclude a state from strengthening the 
existing limitation as a contingency measure, as a practical matter, 
for these specific source categories a more stringent limitation with 
respect to NOX concentrations or on a per heat/power basis 
would likely require replacement of burners or add-on, pre/post-
combustion emission controls. The equipment retrofits on individual 
pieces of combustion units that would be needed to achieve additional 
emission reductions would require the Colorado Air Pollution Control 
Division within CDPHE, and the significant number of potentially 
impacted individual operators to plan, prepare for installation, and 
install the air pollution control equipment, which would take time 
likely causing the measure to exceed the two-year timeframe for 
contingency measures to achieve emission reductions. Furthermore, we 
note that Colorado's SIP already includes combustion process 
adjustments for combustion equipment, where owners/operators must 
conduct inspections of fuel burning equipment and combustion controls 
and perform maintenance as applicable. Therefore, the EPA is proposing 
to find that establishing more stringent emission limitations for 
combustion equipment than those required by Regulation 26, Part B, 
section II.A.4. for boilers, stationary combustion turbines, RICE, and 
process heaters, would be infeasible as a contingency measure because 
it would not achieve emissions reductions within two years.
3. Adopted Contingency Measures
    The emission reductions from the motor vehicle coatings measure 
will be considered as the contingency measures reductions that should 
have been triggered by EPA's prior finding that the DMNFR Serious 
nonattainment area failed to attain the 2008 ozone NAAQS by its 
applicable attainment date. The EPA is proposing to find that this 
measure is consistent with applicable CAA requirements for contingency 
measures, and accordingly to approve the motor vehicle coatings measure 
as a contingency measure with respect to the contingency measures 
requirement for the 2008 ozone NAAQS Serious nonattainment plan for the 
DMNFR area.
4. Conclusion
    Based on the VOC emission reductions achieved by the motor vehicle 
coatings contingency measure, and Colorado's infeasibility 
justification for having contingency measures that achieve less than 
one year's worth of progress, the EPA proposes to find that the 2024 
DMNFR Contingency Measures Plan fulfills the contingency measures 
requirements for the Serious nonattainment plan for the DMNFR area for 
the 2008 ozone NAAQS. Final approval of the 2024 DMNFR Contingency 
Measures plan would cure the EPA's prior disapproval of the State's 
March 22, 2021 SIP submittal intended to meet the contingency measures 
requirement for the 2008 ozone NAAQS for the DMNFR Serious 
nonattainment area.

VII. Proposed Action

    The EPA is proposing to approve SIP revisions submitted by the 
State of Colorado to address the contingency measures requirement for 
the Serious area nonattainment plan for the DMNFR area for purposes of 
the 2008 Ozone NAAQS. The EPA is proposing this action based on our 
determination that the 2024 DMNFR Contingency Measures Plan meets the 
requirements of CAA

[[Page 19459]]

section 172(c)(9) and 182(c)(9). The EPA is also proposing to approve 
revisions to Colorado Regulations 7 and 25 related to the contingency 
measures requirement and as summarized in section IV.A. of this 
proposed rulemaking.
    In this same issue of the Federal Register, we are also issuing an 
interim final determination, effective upon publication, to defer the 
imposition of sanctions. Specifically, the determination will defer 
application of the offset sanction for permitting of new or modified 
sources and highway sanctions for which clocks were triggered by the 
EPA's November 7, 2023 disapproval of SIP revisions submitted to 
address the contingency measures requirement for the 2008 ozone NAAQS 
for the DMNFR Serious classification nonattainment area.\70\ The 
determination to defer sanctions is based upon our proposed approval 
action detailed in this document, with respect to the SIP submittals 
addressing the contingency measures SIP requirement. Please see the 
interim final determination for further information concerning 
sanctions and the basis for issuing the interim final determination.
---------------------------------------------------------------------------

    \70\ See 40 CFR 52.31(d)(2)(ii).
---------------------------------------------------------------------------

    The EPA is soliciting public comments on the proposed action, our 
rationale for the proposed action, and any other pertinent matters 
related to the issues discussed in this document. We encourage comments 
regarding whether there are new or more stringent control measures not 
identified in Colorado's analysis and which may be feasible as 
contingency measures. We will accept comments from the public on this 
proposal for the next 30 days and will consider comments before taking 
final action.

VIII. Consideration of Section 110(l) of the CAA

    Under section 110(l) of the CAA, the EPA cannot approve a SIP 
revision if the revision would interfere with any applicable 
requirement concerning attainment and reasonable further progress 
toward attainment of the NAAQS, or any other applicable requirement of 
the Act. In addition, section 110(l) requires that each revision to an 
implementation plan submitted by a state be adopted by the state after 
reasonable notice and public hearing. The Colorado SIP provisions that 
the EPA is proposing to approve in this action do not interfere with 
any applicable requirements of the Act. Thus, the EPA is proposing to 
find that the approval of portions of the State's June 26, 2024, May 
23, 2023, and April 2, 2025 SIP submittals as described in this notice 
of proposed rulemaking is consistent with section 110(l). Therefore, 
the EPA proposes to determine the CAA section 110(l) requirements are 
satisfied.

IX. Incorporation by Reference

    In this document, the EPA is proposing to include regulatory text 
in an EPA final rule that includes incorporation by reference. In 
accordance with requirements of 1 CFR 51.5, the EPA is proposing to 
incorporate by reference Colorado Air Quality Control Commission 
Regulation 25 pertaining to the ``Control of Emissions from Surface 
Coating, Solvents, Asphalt, Graphic Arts and Printing, and 
Pharmaceuticals'' and Regulation 7 pertaining to the ``Control of Ozone 
via Ozone Precursors and Control of Hydrocarbons via Oil and Gas 
Emissions (Emissions of Volatile Organic Compounds (VOC) & Nitrogen 
Oxides (NOX))'' (as specified in sections IV.A. and VI.A. 
above). The EPA has made, and will continue to make, these materials 
generally available through https://www.regulations.gov and at the EPA 
Region 8 Office (please contact the person identified in the FOR 
FURTHER INFORMATION CONTACT section of this preamble for more 
information).

X. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the CAA and applicable 
Federal regulations.42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely approves state law as meeting Federal requirements and 
does not impose additional requirements beyond those imposed by state 
law. For that reason, this action:
     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);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not subject to Executive Order 13045 (62 FR 19885, 
April 23, 1997) because it approves a state program;
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001); and
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the 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. The proposed rule does 
not have Tribal implications and will not impose substantial direct 
costs on Tribal governments or preempt Tribal law as specified by 
Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects in 40 CFR Part 52

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


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

    Dated: April 21, 2025.
Cyrus M. Western,
Regional Administrator, Region 8.
[FR Doc. 2025-07937 Filed 5-7-25; 8:45 am]
BILLING CODE 6560-50-P