2024-22008. State Implementation Plan Submittal Deadlines and Implementation Requirements for Reclassified Nonattainment Areas Under the Ozone National Ambient Air Quality Standards

Table 1—Default SIP Submission and Control Measure Implementation Deadlines for Reclassified Ozone Nonattainment Areas When the Classification-related Deadlines for Initial Designations Provide Insufficient Time

SIP requirement	Proposed default deadline
Default Deadlines for Reclassified Nonattainment Areas
SIP submittal deadline for all elements, unless addressed differently elsewhere in this table	Within 18 months after the effective date of the relevant reclassification or January 1 of the applicable attainment year, whichever is sooner.
RACT implementation deadline	Within 18 months from the RACT SIP submittal deadline or the beginning of the applicable attainment year ozone season as defined by 40 CFR appendix D to part 58(i), whichever is sooner.
I/M implementation deadline (Basic and Enhanced)	No later than 4 years after the effective date of the relevant reclassification notice (unless needed for attainment by the attainment date or to demonstrate RFP).
Default Deadlines for Reclassified Severe Nonattainment Areas
SIP submittal deadline for section 185 fee program element	36 months after the effective date of the relevant reclassification notice or no later than January 1 of the applicable attainment year, whichever is sooner.

Establishing default deadlines for areas reclassified under CAA sections 181(b)(2) and 181(b)(3) is necessary and appropriate to ensure states are submitting SIP revisions and implementing control measures triggered by reclassification on a consistent timeline that retains the statute's framework of applying requirements in time to achieve attainment by the attainment date. Doing so also provides states maximum advance visibility into the time that will be provided for development of SIP revisions and new control measures designed to expeditiously attain the NAAQS. The EPA's expectation is that providing a consistent framework for SIP development for reclassified areas will establish certainty for states with areas that fail to timely attain, and that such states can begin focusing on identifying meaningful reductions and developing SIPs to obtain those reductions earlier than they would under the EPA's historical practice of issuing SIP revision submission and control measure implementation deadlines after or in parallel with the determinations that result in area reclassifications. However, we recognize the possibility that in some situations, the default deadlines may not be appropriate or serve the statutory goals of consistency amongst submissions or expeditious attainment of the NAAQS. Therefore, we propose that the EPA would retain authority under CAA sections 301(a) and 182(i) to establish a set of SIP submission and control measure implementation deadlines on a case-by-case basis, through notice-and-comment rulemaking, that deviate from the default deadlines proposed in this document, if finalized, where appropriate.

1. Default Deadlines for Nonattainment Areas Reclassified as Moderate or Serious

SIP requirements that apply to Moderate areas are generally cumulative of CAA requirements for the Marginal classification and include additional Moderate area requirements ( see CAA sections 172(c)(1) and 182(a) and (b)). The EPA has further interpreted and described these requirements in its implementation rules.^[14] Similarly, SIP requirements that apply to Serious areas are generally cumulative of CAA requirements for the Marginal and Moderate area classifications and include additional Serious area requirements ( see CAA sections 172(c)(1) and 182(a)-(c)). The EPA's implementation rules also provide further interpretation of the statutory Serious area requirements.^[15]

a. Default Submission Deadline for Required SIP Revisions

The time period between designation and the maximum attainment date for nonattainment areas initially classified as Moderate or Serious is 6 or 9 years, respectively. In the case of mandatory reclassification after initial area designations pursuant to CAA section 181(b)(2), reclassified Moderate and Serious areas would typically have less than 3 years between the date of reclassification and the area's new maximum attainment date. Given the compressed timeline that reclassified Moderate and Serious areas face, and consistent with past practice,^[16] we are proposing to set the SIP submission deadlines for all the various requirements for newly reclassified Moderate and Serious areas as within 18 months of the effective date of the relevant reclassification notice or January 1 of the applicable attainment year, whichever is sooner, unless otherwise specified in a separate notice-and-comment rulemaking establishing a different SIP submission deadline. While not all of the “schedules prescribed in connection with” the various subpart 2 requirements are the same, because the timeframe to attain by the newly applicable attainment date for Moderate and Serious areas is compressed from either 6 or 9 years to less than 3 years, we propose to apply one SIP revision deadline that is at most 18 months from the effective date of reclassification, but in any case no later than January 1 of the attainment year.

As previously stated, the EPA believes that, in most cases, 18 months should provide states sufficient time for assessing, adopting, and implementing emission reduction measures such that any reclassified nonattainment areas can expeditiously attain the ozone NAAQS, consistent with part D's purpose of achieving expeditious attainment by the attainment date. Similarly, a default SIP submission deadline of January 1 of the applicable attainment year would ( print page 80839) promote expeditious attainment of the ozone NAAQS by requiring states to submit SIPs including control measures needed for attainment prior to when those controls are required to be implemented. In addition, establishing January 1 of the attainment year as the outer boundary for states to submit SIP revisions would ensure that reclassified nonattainment areas are subject to consistent deadlines in accordance with CAA section 182(i) and would be in line with past practice. For example, the EPA adopted this approach for Marginal areas reclassified as Moderate for failure to timely attain the 2008 and 2015 ozone NAAQS, to ensure consistency among required SIP submissions.^[17 18] Thus, the proposed deadline is necessary and appropriate to assure that these submissions are consistent with the Act's overall scheme for expeditious attainment of the NAAQS by the attainment date, and that similarly situated states are treated consistently.

In some historical instances, we have also established SIP submission deadlines that align with the beginning of an area's ozone season,^[19] which we view as the outer boundary for establishing a SIP submission deadline for a reclassified area, because the beginning of the attainment year ozone season is the maximum deadline under the statutory ozone RACT provision and the EPA's existing regulations interpreting that provision to implement RACT. The EPA does not believe it is reasonable to establish a SIP submission date for controls subsequent to a date when those controls are required under the Act to already be implemented. For many ozone nonattainment areas in the country, January 1 is the beginning of the ozone season. But there are states that have a later start to the ozone season in March, April, or May. We therefore take comment on establishing the later alternative SIP submission deadline for reclassified Moderate and/or Serious areas as the beginning of the attainment year ozone season (rather than January 1 of the attainment year), recognizing that doing so would result in different SIP submission deadlines for different reclassified areas, depending on when the area's ozone season begins.

The EPA's proposed SIP submission deadline for areas reclassified as Moderate or Serious of no later than 18 months after the effective date of the relevant reclassification notice or January 1 of the applicable attainment year, whichever is earlier, would apply to all newly applicable requirements associated with the reclassification, including SIPs to address RACT and I/M. The EPA's implementing regulations for the 2015 ozone NAAQS established a default RACT SIP submission deadline for areas reclassified Moderate or higher of either 24 months from the reclassification effective date or a deadline established by the Administrator in the reclassification action using its discretion under CAA section 182(i) ( see40 CFR 51.1312(a)(2)(ii)). We have found that a RACT SIP submission deadline of 24 months after the effective date of the reclassification action has resulted in SIP submission deadlines that are later than the beginning of the attainment year ozone season, and in some cases, near or after an applicable Moderate or Serious area attainment date. In every case of reclassification under the 2008 and 2015 ozone NAAQS, it has not been possible to provide a RACT SIP submission deadline of 24 months from the effective date of the reclassification for an area that was reclassified as result of failure to attain by the attainment date. We are therefore proposing to remove the existing RACT SIP submission deadline in 40 CFR 51.1312(a)(2)(ii) and replace it with the general default deadlines discussed in this action.

Thus, if this action is finalized as proposed, the default SIP submission deadlines for newly required Basic or Enhanced I/M SIPs, would also become the sooner of 18 months from the effective date of the relevant reclassification notice or January 1 of the applicable attainment year. This is necessary to be consistent with the I/M regulations which provide that an I/M SIP shall be submitted no later than the deadline for submitting the area's attainment SIP.^[20]

b. Default Implementation Deadlines for RACT and I/M

With respect to implementation deadlines, the EPA's implementing regulations for the 2008 ozone NAAQS require that, for areas initially classified as Moderate or higher, a state shall provide for implementation of RACT as expeditiously as practicable, but no later than January 1 of the 5th year after the effective date of designation.^[21] Similarly, the EPA's implementing regulations for the 2015 ozone NAAQS require that, for areas initially classified as Moderate or higher, a state shall provide for implementation of RACT as expeditiously as practicable but no later than January 1 of the fifth year after the effective date of designation.^[22] The EPA's implementing regulations for the 2015 ozone NAAQS also require that, for RACT required pursuant to reclassification, the state shall provide for implementation of RACT as expeditiously as practicable, but no later than the beginning of the attainment year ozone season associated with the area's new attainment deadline, or January 1 of the third year after the associated SIP submission deadline, whichever is earlier; or the deadline established by the Administrator in the final action issuing the area reclassification.^[23] In addition, the modeling and attainment demonstration requirements for 2008 ozone nonattainment areas require that a state must provide for implementation of all control measures needed for attainment no later than the beginning of the attainment year ozone season.^[24] Similarly, the EPA's implementing regulations for the 2015 ozone NAAQS require that the modeling and attainment demonstrations for areas classified Moderate or higher must provide for implementation of all control measures needed for attainment no later than the beginning of the attainment year ozone season, notwithstanding any alternative deadline established per 40 CFR 51.1312.^[25] Underlying these implementation deadlines is the EPA's consideration that any RACT deadline should, where possible, provide at least one full ozone season in advance of an area's maximum attainment date for implemented controls to achieve emission reductions and positively influence an area's monitored design value.

The EPA recognizes that the beginning of the ozone season varies among states and nonattainment areas. For some nonattainment areas, the ozone season begins in January and for other areas it begins in March, April, or May. Consequently, the beginning of the attainment year ozone season ranges from January to May of the year before ( print page 80840) the area's maximum attainment deadline. The EPA's existing implementing regulations informed the default RACT implementation deadline that we are proposing in this document for any area reclassified as Moderate or Serious. Such proposed default deadline would require states to implement RACT as expeditiously as practicable, but no later than 18 months from the proposed RACT SIP submittal deadline or the beginning of the applicable attainment year ozone season, whichever is earlier. We are proposing that this default deadline would apply instead of the existing regulatory provision in 40 CFR 51.1312(a)(3)(ii), which applied only to the 2015 ozone NAAQS. As we proposed for establishment of SIP submission deadlines, the EPA is also proposing that the regulation would allow the EPA to establish a different deadline in a notice-and-comment rulemaking in order to accommodate fact-specific circumstances, where appropriate.

With respect to the default implementation deadlines for Basic and Enhanced I/M programs required as the result of a mandatory reclassification, states wishing to use emission reductions from their newly required I/M programs for the ozone NAAQS would need to have such programs fully established and start testing as expeditiously as practicable, but no later than the beginning of the applicable attainment year ozone season, consistent with the CAA principle (and logic) that measures that are needed to demonstrate attainment by the attainment date must be in place early enough to impact the air quality design value that will be used to determine whether the area attained by that date. The EPA's implementing regulations for the 2008 and 2015 ozone NAAQS therefore adopt this principle with respect to implementation of I/M when required as a result of a reclassification. However, given the unique nature of I/M programs, there are many challenges, tasks, and milestones that must be met in establishing and implementing an I/M program. The EPA realizes that implementing a new or revised I/M program on an accelerated timeline may be difficult to achieve in practice. Therefore, for states that do not intend to rely upon emission reductions from their newly required Basic or Enhanced I/M program in attainment or RFP SIPs, we are proposing to allow these Basic and Enhanced I/M programs to be fully implemented no later than 4 years after the effective date of reclassification, explained as follows.

Under CAA section 182(i), mandatorily reclassified areas are generally required to meet the requirements associated with their new classification “according to the schedules prescribed in connection with such requirements.” The I/M regulations provide such a prescribed schedule in stating that newly required I/M programs are to be implemented as expeditiously as practicable. The I/M regulations also allow areas newly required to implement I/M up to “4 years after the effective date of designation and classification” to fully implement the I/M program.^[26] With mandatory reclassifications, this 4-year implementation deadline for newly required I/M programs might extend beyond the corresponding attainment date. However, by proposing such a deadline for mandatorily reclassified areas newly required to implement a Basic or Enhanced I/M program (but not needing I/M emission reductions for attainment or RFP SIP purposes), the EPA maintains that these newly required I/M programs could reasonably be implemented after the area's relevant attainment date if reductions from an I/M program are not necessary for an area to achieve timely attainment of the applicable NAAQS. The EPA has long taken the position that the statutory requirement for states to implement I/M in ozone nonattainment areas classified Moderate and higher generally exists independently from the attainment planning requirements for such areas ( see also section III.B.2. of this document).^[27] This proposed implementation deadline of up to 4 years takes into consideration the numerous challenges and milestones necessary in implementing a Basic or an Enhanced I/M program. The EPA is proposing to establish that the same implementation deadline of up to 4 years for areas not relying on Basic or Enhanced I/M for attainment or RFP SIP purposes is appropriate to also apply to voluntarily reclassified areas, where the higher classification deadlines for those areas have either already passed or are less than 18 months from the effective date of reclassification. This proposed deadline is not only consistent with the proposed deadline for mandatorily reclassified areas, but it is also consistent with EPA's historical practice.^[28]

The EPA requests comment on a proposed default deadline for reclassified Moderate and Serious areas requiring that any newly required Basic or Enhanced I/M programs be fully implemented as expeditiously as practicable, but no later than 4 years after the effective date of reclassification. The EPA again notes that if a state intends to rely upon emission reductions from its newly required Basic or Enhanced I/M programs in its attainment or RFP SIP, the state will need to have such I/M programs fully implemented no later than the beginning of the applicable attainment year ozone season.

c. Transportation Control Demonstration

CAA section 182(c)(5) requires states with Serious ozone nonattainment areas to submit, 6 years after November 15, 1990, and every 3 years thereafter, a demonstration as to whether current aggregate vehicle mileage, aggregate vehicle emissions, congestion levels, and other relevant parameters are consistent with those used for the area's demonstration of attainment. Six years after November 15, 1990, was 2 years after the statutory deadline established to submit attainment demonstrations for such areas. Because the transportation control demonstration is not itself a control that must be implemented in order for areas to attain by the attainment date, and is ideally spaced from the deadline of the attainment demonstration to allow sufficient time for the state to see whether actual vehicle emissions and parameters square with the projected emissions and parameters in the attainment demonstration modeling, it is appropriate to retain the Act's prescribed schedule without adjustment with respect to this element for reclassified areas. The EPA is therefore proposing that for all reclassified Serious ozone areas, the first transportation control demonstration must be submitted within 2 years after the deadline for the attainment demonstrations for these areas and every 3 years thereafter. ( print page 80841)

2. Default Deadlines for Nonattainment Areas Reclassified as Severe

SIP requirements that apply to Severe areas are generally cumulative of CAA requirements for lower area classifications ( i.e., Marginal through Serious) and include additional Severe area requirements as interpreted and described in the final SIP Requirements Rules for the 2008 and 2015 ozone NAAQS ( see80 FR 12264, March 6, 2015; 83 FR 62998, December 6, 2018; CAA sections 172(c)(1) and 182(a)-(d); 40 CFR 51.1100 et seq.; and 40 CFR 51.1300 et seq. ). For areas reclassified as Severe, SIP submissions must address the more stringent major source threshold of 25 tpy ^[29] for RACT and NNSR, and the more stringent NNSR emissions offset ratio of 1.3:1.^[30] In order to fulfill their Severe area SIP submission requirements, states may, where appropriate, certify that existing SIP provisions for an area are adequate to address one or more Severe area requirements. Such certifications must be submitted as a SIP revision.^[31]

The EPA is proposing the same default SIP submittal and implementation deadlines for reclassified Severe areas as is proposed in section III.A.1. of this document for reclassified Moderate and Serious areas, with one exception for SIP submissions addressing CAA section 185 fee programs. More specifically, for all newly applicable SIP requirements associated with an area's reclassification to Severe (except SIP submissions addressing section CAA section 185 fee programs), the EPA is proposing a default SIP submittal deadline as the earlier of 18 months after the effective date of the relevant reclassification notice or January 1 of the applicable attainment year.^[32] This proposed SIP submission deadline is consistent with the EPA's historical adjustment of deadlines for ozone areas mandatorily reclassified from Serious to Severe under the 2008 ozone NAAQS as well as areas reclassified to Severe per a voluntary request from the state, for which we have previously established 18-month SIP submission deadlines.^[33]

It is appropriate to align the default SIP submission and implementation deadlines for reclassified Severe nonattainment areas with those proposed in section III.A.1. of this document for reclassified Moderate and Serious nonattainment areas. The same considerations articulated in section III.A.1. also apply here. Additionally, areas that have been reclassified to Severe are areas that have struggled over time to expeditiously attain the NAAQS, and may face more complex and difficult implementation obstacles than areas classified at lower levels. However, it is the Agency's view that an outer boundary of 18 months remains an appropriate timeframe for states to revise SIPs as needed, even for areas reclassified as Severe. We recognize that the statute's later maximum attainment date associated with higher classifications, and the more stringent requirements imposed upon such areas under subpart 2, reflect the “heavier lift” that Severe areas may face to attain the NAAQS. The longer interval between attainment dates between Serious and Severe would provide states more time than is available for reclassifications between the lower classifications ( i.e., Marginal to Moderate or Moderate to Serious) for SIP development and identification and implementation of control measures. However, that same interval also means that establishing an 18-month maximum SIP submission and control measure implementation deadline will result in earlier implementation of the control measures prompted by the Severe area requirements, such that those measures may be in place to impact air quality in multiple ozone seasons before the maximum attainment date, rather than just the last ozone season preceding the attainment date, as may often be the practical outcome of the EPA's proposed deadline for areas in the lower classifications. Increasing the likelihood that Severe area measures will be in place for multiple ozone seasons prior to the attainment date correspondingly increases the likelihood that these reclassified Severe areas will expeditiously attain the NAAQS by the attainment date. The EPA's proposed deadline for reclassified areas, by providing 18 months for SIP development but requiring at least that those revisions and measures be submitted by the last calendar year preceding the attainment date, accommodates the varying positions areas may be in vis-à-vis their attainment date, while also meeting the CAA's requirement under section 182(i) “to assure consistency among the required submissions.”

The EPA is therefore proposing a default deadline for states to submit Severe area SIP revisions of 18 months after the effective date of reclassification or January 1 of the applicable attainment year, whichever is earlier. Specifically, the EPA is proposing that SIP revisions required for all newly reclassified Severe areas must be submitted by the sooner of 18 months after the effective date of reclassification or January 1 of the applicable attainment year, except for SIP revisions required to address the section 185 fee program element, for which the EPA is proposing a submittal deadline of the earlier of 36 months after the effective date of reclassification or January 1 of the applicable attainment year. Consistent with past practice, the EPA is proposing a later submittal date for the CAA section 185 fee program element than what is proposed for the other requirements because implementation of a CAA section 185 fee program is a penalty for failing to attain the NAAQS by the applicable attainment date.^[34] Thus, an extended deadline of the earlier of 36 months after the effective date of reclassification or January 1 of the applicable attainment year, could allow states to focus more attention on other elements in the first 18 months following reclassification while also allowing enough time for states to submit, and for the EPA to approve, a CAA section 185 fee program ahead of the applicable Severe area attainment date. However, to the degree that states want to take advantage of the administrative efficiency of adopting the CAA section 185 fee program element along with other required Severe area SIP elements, they have the option to submit their CAA section 185 fee programs earlier, including with the other elements.

CAA section 182(d)(1)(A) requires a state with a Severe ozone nonattainment ( print page 80842) area to submit a SIP revision that identifies and adopts specific enforceable transportation controls strategies and transportation control measures (TCMs) to offset any growth in emissions from vehicle miles traveled (VMT) or number of vehicles trips in such area. The EPA has provided guidance to states on how to demonstrate whether there has been any growth in emissions from growth in VMT or growth in the number of vehicle trips.^[35] In addition, states with Severe ozone nonattainment areas are required to submit a SIP revision that identifies and adopts specific enforceable transportation control strategies and TCMs to obtain reductions in motor vehicle emissions as necessary, in combination with other emission reduction requirements. States are also required to consider measures specified in CAA section 108(f) and choose from among those measures and implement such measures as necessary to demonstrate attainment with the relevant ozone NAAQS. In considering these measures, states should ensure adequate access to downtown, other commercial, and residential areas and should avoid measures that increase or relocate emissions and congestion rather than reduce them. The EPA proposes that a SIP revision to address the VMT offset demonstration requirement will be due the earlier of 18 months after the effective date of reclassification or January 1 of the applicable attainment year, consistent with all other Severe area requirements. If a demonstration shows that a state must adopt transportation control strategies or TCMs to offset any identified increase in emissions due to growth in VMT or vehicle trips or if additional transportation control strategies or TCMs are needed to address RFP or attainment, we are proposing that the transportation control strategies and/or TCMs be submitted at the same time as the SIP revision to address the VMT offset demonstration.

In addition to these submission deadlines, for any controls that air agencies determine are needed for meeting CAA requirements, the EPA is proposing that these controls must be implemented as expeditiously as practicable, but no later than 18 months from the SIP submission deadline or the beginning of the applicable attainment year ozone season, whichever is earlier. This proposed deadline would generally provide a 36-month schedule for SIP submission and controls implementation for reclassified Severe areas. These proposed default deadlines are consistent with the deadlines established for all other Severe area plan elements that are established under CAA sections 172(c)(1) and 182(a)-(d), and 40 CFR 51.1100 et seq. As proposed in section III.A.1. of this document for reclassified Moderate and Serious areas, the EPA is also proposing to reserve the right to establish different SIP submittal and implementation deadlines for reclassified Severe areas in a notice-and-comment rulemaking in order to accommodate fact-specific circumstances, where appropriate.

In addition to the SIP submission deadlines identified in this section, the CAA prohibits the sale of conventional gasoline in any ozone nonattainment area that is reclassified as Severe and requires that federal reformulated gasoline (RFG) be sold instead. The prohibition on the sale of conventional gasoline takes effect 1 year after the effective date of the reclassification ( see CAA sections 211(k)(10)(D) and 211(k)(5)). The prohibition on the sale of conventional gasoline takes effect by operation of law; therefore, states with such reclassified areas are not required to make a SIP submission associated with the RFG requirement.

In summary, the EPA is proposing to establish default SIP submittal and implementation deadlines for reclassifications by operation of law under CAA section 181(a)(2) for areas that fail to attain by the attainment date and are thus reclassified as Moderate, Serious, or Severe for all current and future ozone NAAQS, and also for voluntary reclassifications to these classifications under CAA section 181(a)(3). Establishing default SIP submission deadlines that are triggered from the effective date of reclassification actions will provide consistency among the submissions in the sense that all states with jurisdiction over such areas will be treated uniformly by having the same amount of time to develop and submit SIPs. However, we acknowledge that our proposal could in some cases result in SIP deadlines for reclassified areas falling on different days (because such deadlines will be triggered by reclassification actions that are statutorily required to happen any time in a 6-month window following the attainment date, or are granted under voluntary reclassification requests that may occur at any time).

For areas reclassified as Moderate or Serious, where the initially established deadlines have passed or are less than 18 months from the effective date of reclassification, the EPA is requesting comment on: (1) establishing a default SIP submission deadline for all Moderate and Serious area plan elements of no later than 18 months from the effective date of the relevant reclassification notice or January 1 of the applicable attainment year, whichever is earlier; (2) requiring that RACT be implemented as expeditiously as practicable, but no later than 18 months from the RACT SIP submittal deadline or the beginning of the applicable attainment year ozone season, whichever is earlier; (3) requiring that any newly required Basic or Enhanced I/M programs be fully implemented as expeditiously as practicable, but no later than 4 years after the effective date of reclassification; and (4) requiring that the first transportation control demonstration be submitted 2 years after the due date for the attainment demonstrations for reclassified areas ( i.e., January 1 of the applicable attainment year) and every 3 years thereafter.

For areas reclassified as Severe, where the initially established deadlines have passed or are less than 18 months from the effective date of reclassification, the EPA is requesting comment on: (1) establishing a default SIP submission deadline for all Severe area plan elements of 18 months after the effective date of reclassification or January 1 of the applicable attainment year, whichever is earlier, with an exception for section 185 fee program SIPs; (2) establishing a default SIP submission deadline for section 185 fee program SIPs of 36 months from the effective date of reclassification or January 1 of the applicable attainment year, whichever is earlier; and (3) requiring that any controls needed for meeting RFP or timely attainment of the ozone NAAQS be implemented as expeditiously as practicable, but no later than 18 months after the proposed SIP submission deadline or the beginning of the applicable attainment year ozone season, whichever is earlier.

B. Status of Certain Requirements of Former Classification

1. Introduction

The EPA is also proposing to revise regulations to clarify whether, when an ozone nonattainment area is reclassified to a higher classification, certain ozone SIP requirements for that lower, former classification will still be required. The ( print page 80843) EPA has previously established its statutory interpretation and position on the status of certain SIP requirements for the previous classification in individual SIP actions, most recently in a reclassification action for three nonattainment areas in Texas.^[36] This proposal restates these interpretations and proposes regulatory language to codify these interpretations to provide further clarity. Specifically, the EPA is restating its interpretation that ozone nonattainment area planning requirements continue to apply following a change in an area's classification level, except where the EPA has specifically determined that the planning requirement is no longer applicable. Specifically, the EPA's existing interpretation is that only three requirements applicable to the lower, former classification ( i.e., Moderate or Serious) are no longer required following a change in the area's classification ( i.e., to Serious or Severe, respectively): (1) the attainment demonstration, (2) RACM, and, (3) for areas that are voluntarily reclassified, contingency measures as necessary to address failure to attain by the attainment date.

As described elsewhere in this document, CAA section 182(i) specifies that reclassified areas must meet the requirements “as may be applicable to the area as reclassified” and describes the EPA's authority to adjust applicable deadlines (except attainment dates) for the new classification. In contrast, the CAA does not specify what then happens to the requirements that were applicable to the area as it was formerly classified. Nevertheless, this question commonly arises in the ozone program in circumstances where an area is reclassified—whether mandatorily as a result of failure to attain pursuant to CAA section 181(b)(2) or voluntarily ( i.e., at the request of a state) pursuant to CAA section 181(b)(3)—before the EPA determines that the requirements for the former classification have been met by the state. This can occur when reclassification takes effect before a state has submitted a SIP revision addressing the requirements applicable to the former classification, before the EPA has acted on a SIP submission to address such requirements, or where the EPA has disapproved or conditionally approved a SIP submission addressing such requirements. For the purposes of this proposal, the EPA refers to the unresolved requirements applicable to the former classification under any of these scenarios as “leftover” SIP requirements.

As an initial matter, the Agency notes that when the states and EPA timely meet CAA-specified deadlines for submitting and acting on SIPs, and the submissions are approvable, it is possible for there to be no leftover SIP requirements, but this is not guaranteed for every situation. To illustrate a possible circumstance, consider that under the 2015 ozone NAAQS, the Marginal attainment date was August 3, 2021. Assuming the EPA had completed the Marginal determinations of attainment by the attainment date (DAADs) within the 6 months provided by CAA section 181(b)(2) ( i.e., within 6 months of the August 3, 2021, attainment date), the reclassifications to Moderate would have taken effect no later than February 2022. The EPA, consistent with the principles articulated in the deadline portion of this document, could have established a SIP due date of January 1, 2023 ( i.e., the beginning of the Moderate attainment year), less than 11 months after the reclassification took effect. Had the states in turn made timely and complete submissions by January 1, 2023, the EPA could theoretically have acted to approve or disapprove them within the statutory 12 months allotted, or by January 1, 2024. This would have allowed for the possibility of final action before the Moderate attainment date of August 3, 2024. Assuming, for the sake of illustration, that such SIPs were approvable, final approval before the attainment date would ensure that there would be no leftover Moderate SIP requirements by the time the EPA would be required to complete the Moderate area DAAD ( i.e., by February 2025) and reclassify areas to Serious if they fail to attain. However, implementation of the ozone standards does not always follow the most straightforward path. To take the previous example, consider the changed circumstances and timeframe that might occur if the Marginal area qualified for a 1-year extension of the attainment date (under CAA section 181(a)(5) and 40 CFR 51.1307), but ultimately failed to attain by the extended attainment date of August 3, 2022. Even if the EPA issued its DAAD action reclassifying the area immediately after the attainment date ( i.e., August 4, 2022), the state would have less than four months between the reclassification and its applicable SIP due date under this proposal ( i.e., January 1 of the attainment year, 2023) to develop the SIP revisions, put them out for public notice and comment, legislatively approve them, and submit them to the EPA ( see, CAA section 110(l)). This timeframe makes it nearly impossible for the state and the EPA to have approved Moderate area SIPs and controls in place to influence air quality to help the area attain by the Moderate area attainment date ( i.e., August 3, 2024). Thus, areas in circumstances like these may end up failing to attain by the Moderate area attainment date and being reclassified as Serious without having their Moderate area SIP revisions submitted and/or approved. Moreover, even where there is no attainment date extension, the CAA timelines under section 182 leave no margin for delay, particularly for areas that are reclassified by operation of law as Moderate or Serious. For such areas, the attainment year typically begins less than a year from when the SIP would be due, and the resulting timeframe for SIP development—which for ozone can involve complex analyses—is typically less than a year. Therefore, despite significant effort invested by the EPA and states to timely meet CAA-specified deadlines for ozone SIPs, these deadlines are sometimes not met, and leftover SIP requirements can result.

Accordingly, the EPA is restating in this national rulemaking its interpretations describing whether and how these types of SIP requirements leftover from lower classifications will still apply following the reclassification to a higher classification ( e.g., reclassification from Moderate to Serious). The EPA is also proposing regulatory text to codify these interpretations. If this proposed rule is finalized, it will codify the EPA's existing interpretation that certain requirements applicable to the lower, former classification ( i.e., Moderate or Serious) are no longer required following a change in the area's classification. Codifying this interpretation will improve the EPA's and states' abilities to identify and timely meet SIP deadlines.

2. Leftover SIP Requirements

The EPA has assessed the effect of reclassification on each of the SIP requirements—referred to in this document as SIP elements—that apply to Marginal, Moderate, and Serious areas.^[37] We have concluded that certain SIP elements, discussed in this section, are explicitly tied to the current attainment date, and would therefore be mooted by reclassification. However, ( print page 80844) most of the SIP elements required under the former classification are not explicitly tied to the attainment date for that former classification and are therefore unaffected by reclassification. The mere fact that an area is reclassified is not a sufficient basis to determine that a CAA requirement applicable to the prior classification no longer applies and there is no language in the statute which necessitates or even supports such a position. The SIP elements associated with each classification are generally cumulative from Marginal up to Extreme.^[38] The requirement to submit such elements remains applicable, and the submittal and implementation deadlines are unchanged. If a state misses the submission deadline for these required SIP elements and has been subsequently reclassified, the EPA is obligated under CAA section 110(k)(1)© to issue a finding that the state has failed to make a complete submission (FFS) and promulgate a FIP unless the state submits, and the EPA approves, a corrective SIP. Thus, the EPA is not proposing any changes to the current rules with respect to these requirements. For clarity, the requirements associated with a prior classification that the EPA has concluded still apply following a reclassification are listed in table 2. The EPA has been, and will continue, to conduct any CAA-directed oversight on adherence to these listed requirements following reclassification.

Table 2—SIP Requirements From a Prior Classification That Continue To Apply Following Reclassification

SIP requirement	CAA section	Regulatory cite from 40 CFR (if applicable)
Marginal Area Requirements
Emissions Inventory	182(a)(3)(A)	§ 51.1315.
Emissions Statement Rule	182(a)(3)(B)	§ 51.1300(p).
Moderate Area Requirements (also includes above Marginal Area Requirements)
15 percent rate-of-progress (ROP) plan	182(b)(1)(a)	§ 51.1310.
Contingency measures for failure to achieve ROP	172(c)(9)	N/A.
Moderate Area RACT	182(b)(2)	§ 51.1312.
NNSR Moderate Area rules	173	§ 51.165.
Basic I/M	182(b)(4)	40 CFR part 51, subpart S.
Serious Area Requirements (also includes above Moderate Area Requirements)
RFP	182(c)(2)(B) and (C)	§ 51.1310.
Serious Area RACT	182(b)(2)	§ 51.1312.
Contingency measures for failure to achieve RFP	182(c)(9)	N/A.
Enhanced I/M	182(c)(3)	40 CFR part 51, subpart S.
Clean-fuel Vehicle Programs	182(c)(4)	N/A.
NNSR Serious Area Rules	173	51.165.