SUPPLEMENTARY INFORMATION:

I. Background for This Supplemental Proposal

On December 30, 2019, EPA proposed to approve SIP submissions from six Southeast States ( i.e., Alabama, Florida, Georgia, North Carolina, South Carolina, and Tennessee) ^[1] as meeting the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I), or the Good Neighbor provision, for the 2015 8-hour ozone NAAQS. See84 FR 71854. Refer to the December 30, 2019, notice of proposed rulemaking (NPRM) for an explanation of the CAA requirements, the four-step framework that EPA applies under the Good Neighbor provision for ozone NAAQS, a detailed summary of the state submissions, and EPA's proposed rationale for approval. See84 FR 71854. The public comment period for the December 30, 2019, NPRM closed on January 29, 2020.^[2]

Subsequent to the December 30, 2019, proposal, two events occurred which have caused EPA to adjust its analysis of the aforementioned SIP submissions, and consequently, to issue this supplemental proposal. First, on May 19, 2020, the United States Court of Appeals for the District of Columbia Circuit (D.C. Circuit) issued its ruling in Maryland v. EPA, 958 F.3d 1185 (D.C. Cir. 2020) ( Maryland). That case involved EPA's denial of administrative petitions filed by the states of Maryland and Delaware under CAA section 126(b), seeking to have EPA impose emissions limits on sources in upwind states alleged to be emitting in violation of the Good Neighbor Provision. The court held that EPA must address Good Neighbor obligations consistent with the 2021 attainment date for downwind areas classified as being in Marginal nonattainment under the 2015 8-hour ozone NAAQS, “not at some later date.” 958 F.3d at 1203-04 (citing Wisconsin v. EPA, 938 F.3d 303, 314 (D.C. Cir. 2019) ( Wisconsin)). The court disagreed with EPA that use of a 2023 analytic year, consistent with the 2024 attainment date for areas classified as being in Moderate nonattainment, was a proper reading of the court's earlier decision in Wisconsin. Id. at 1204. In light of the Maryland decision, EPA is evaluating these states' Good Neighbor obligations using a 2021 analytic year, corresponding to the 2021 Marginal area attainment date under the 2015 8-hour ozone NAAQS.

Second, on October 30, 2020, EPA released and accepted public comment on updated 2023 modeling that used the 2016 emissions platform developed under the EPA/Multi-Jurisdictional Organization (MJO)/state collaborative project as the primary source for the base year and future year emissions data.^[3] On April 30, 2021, EPA published the final Revised Cross-State Air Pollution Rule (CSAPR) Update using the same modeling that was made publicly available in the proposed rulemaking for the Revised CSAPR Update.^[4] Although that modeling focused on the year 2023, EPA conducted an “interpolation” analysis of these modeling results to generate air quality and contribution values for the 2021 analytic year, consistent with the Maryland holding, as the relevant analytic year for the 2015 8-hour ozone NAAQS.

This new modeling and analysis now provides the primary basis for EPA's proposed approval of the Good Neighbor SIP submissions for Florida, Georgia, North Carolina, and South Carolina. By relying on the updated modeling results, EPA is using the most current and technically appropriate information as the primary basis for this proposed rulemaking. As explained in greater detail in this supplemental proposal, this new analysis indicates that in 2021, these four states are not projected to impact any downwind states at or above a contribution threshold of one percent of the 20158-hour ozone NAAQS, which is equivalent to 0.70 parts per billion (ppb). Thus, EPA is proposing to approve these four states' submissions.

Additionally, EPA previously proposed to approve infrastructure SIP elements submitted to fulfill the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I) by the states of Alabama and Tennessee for the 2015 8-hour ozone NAAQS in the December 30, 2019, NPRM referenced above. This supplemental proposal does not address these submissions, and EPA is deferring action on the referenced SIP submissions from Alabama and Tennessee at this time.

II. EPA's Analysis

On May 19, 2020, the D.C. Circuit issued the Maryland decision that cited the Wisconsin decision in holding that EPA must assess the impact of interstate transport on air quality at the next downwind attainment date, including Marginal area attainment dates, in evaluating the basis for EPA's denial of a petition under CAA section 126(b). See 958 F.3d 1185, 1203-04. The court noted that “section 126(b) incorporates the Good Neighbor Provision,” and therefore “the EPA must find a violation [of section 126] if an upwind source will significantly contribute to downwind nonattainment at the next downwind attainment deadline. Therefore, EPA must evaluate downwind air quality at that deadline, not at some later date.” Id. at 1204 (emphasis added). EPA interprets the court's holding in Maryland as requiring the Agency, under the Good Neighbor provision, to address Good Neighbor obligations by the next applicable attainment date for downwind areas, including a Marginal ( printed page 37944) area attainment date under CAA section 181 for ozone nonattainment.^[5]

The Marginal area attainment date for the 2015 8-hour ozone NAAQS is August 3, 2021.^[6] See CAA section 181(a); 40 CFR 51.1303; 83 FR 25776 (June 4, 2018, effective August 3, 2018). Historically, EPA has considered the last full ozone season prior to the attainment date as supplying an appropriate analytic year for assessing Good Neighbor obligations. See, e.g.,81 FR 74540. While this would be 2020 for an August 2021 attainment date (which falls within the 2021 ozone season running from May 1 to September 30), in this circumstance, when the 2020 ozone season is wholly in the past, it is appropriate to focus on 2021 to address Good Neighbor obligations to the extent possible by the 2021 attainment date. EPA does not believe it would be appropriate to select an analytic year that is wholly in the past because EPA interprets the Good Neighbor provision as forward looking. See85 FR 68964, 68981; see also Wisconsin, 938 F.3d at 322. Consequently, as discussed further below, EPA is using the analytic year of 2021 in this supplemental proposal to evaluate Good Neighbor obligations for Florida, Georgia, North Carolina, and South Carolina with respect to the 2015 8-hour ozone NAAQS.

The December 30, 2019, NPRM proposing approval of the 2015 8-hour ozone Good Neighbor SIPs for Florida, Georgia, North Carolina, and South Carolina predates the D.C. Circuit's decision in Maryland. This decision also came after the close of the public comment period on the December 30, 2019, NPRM. However, this decision bears directly on EPA's action and its consideration of the comments received on the December 30, 2019, NPRM. As discussed above and in accordance with the Wisconsin and Maryland decisions, the Agency considers 2021 to be the relevant analytic year for the purpose of determining whether sources in Florida, Georgia, North Carolina, and South Carolina will significantly contribute to nonattainment or interfere with maintenance of the 2015 8-hour ozone NAAQS in any other states.

EPA is proposing to determine that the Florida, Georgia, North Carolina, and South Carolina Good Neighbor SIP submissions for the 2015 8-hour ozone NAAQS are approvable using a 2021 analytic year. The SIP submissions from Florida, Georgia, North Carolina, and South Carolina rely on analysis of the year 2023 to show that they do not significantly contribute to nonattainment or interfere with maintenance of the 2015 8-hour ozone NAAQS in any other state. However, given the holdings in Wisconsin and Maryland, analysis of that year is no longer sufficient where the next attainment date for the 2015 8-hour ozone NAAQS is in 2021.^[7] Nonetheless, the analysis EPA has conducted for the 2021 analytic year corroborates the conclusion reached in each state's submission and in the December 30, 2019, NPRM. In accordance with the holdings in Wisconsin and Maryland, EPA's supplemental analysis relies on 2021 as the relevant attainment year for evaluating Good Neighbor obligations for Florida, Georgia, North Carolina, and South Carolina with respect to the 2015 8-hour ozone NAAQS using the same four-step interstate transport framework described in the proposal of this action. See84 FR 71855.

In step 1, EPA identifies locations where the Agency expects there to be nonattainment or maintenance receptors for the 2015 8-hour ozone NAAQS based on analysis of ozone concentrations at individual monitoring sites in the appropriate analytic year. Where EPA's analysis shows that a monitoring site does not fall under the definition of a nonattainment or maintenance receptor in the analytic year, that site is excluded from further analysis under EPA's four-step interstate transport framework.^[8] For monitoring sites that are identified as nonattainment or maintenance receptors in the appropriate analytic year, EPA proceeds to step 2 of the four-step interstate transport framework by identifying whether emissions in upwind states contribute to those receptors in amounts that exceed a contribution threshold.

EPA's approach to identifying ozone nonattainment and maintenance receptors in this supplemental proposal is consistent with the approach described in the December 30, 2019, NPRM, and is the same approach used in previous transport rulemakings. EPA's approach gives independent consideration to both the “contribute significantly to nonattainment” and the “interfere with maintenance” prongs of CAA section 110(a)(2)(D)(i)(I), consistent with the D.C. Circuit's direction in North Carolina v. EPA, 531 F.3d 896, 910-911 (2008) (holding that EPA must give “independent significance” to each prong of CAA section 110(a)(2)(D)(i)(I)).

For the purpose of this supplemental proposal, EPA identifies nonattainment receptors as those monitoring sites that are projected to have average design values that exceed the NAAQS and that are also measuring nonattainment based on the most recent monitored design values. This approach is consistent with prior transport rulemakings, such as CSAPR Update, where EPA defined nonattainment receptors as those areas that both currently monitor nonattainment and that EPA projects will be in nonattainment in the future compliance year.^[9]

In addition, in this supplemental proposal, EPA identifies a receptor to be a “maintenance” receptor for purposes of defining interference with maintenance, consistent with the method used in CSAPR and upheld by the D.C. Circuit in EME Homer City ( printed page 37945) Generation, L.P. v. EPA, 795 F.3d 118, 136 (DC Cir. 2015).^[10] Specifically, monitoring sites with a maximum projected design value in 2021 that exceeds the NAAQS are identified as maintenance receptors in 2021. EPA's method of defining these receptors takes into account both measured data and reasonable projections based on modeling analysis.^[11]

Recognizing that nonattainment receptors are also, by definition, maintenance receptors, EPA often uses the term “maintenance-only” to refer to receptors that are not also nonattainment receptors. Consistent with the methodology described above, monitoring sites with a projected maximum design value that exceeds the NAAQS, but with a projected average design value that is below the NAAQS, are identified as maintenance-only receptors. In addition, those sites that are currently measuring ozone concentrations below the level of the applicable NAAQS, but are projected to be nonattainment based on the average design value and that, by definition, are projected to have a maximum design value above the standard are also identified as maintenance-only receptors.

Florida, Georgia, North Carolina, and South Carolina relied on the modeling included in an EPA memorandum dated March 2018 (“March 2018 memorandum”),^[12] as well as state specific ozone precursor emission trends, design values, and regulations, to develop their SIPs as EPA had suggested. In the December 30, 2019, NPRM, EPA also relied on the modeling results included in the March 2018 memorandum. See84 FR 71855-71856, 71859-71861. However, EPA is now supplementing the December 30, 2019, NPRM with newly available, updated modeling that was developed using a 2016-based modeling platform prepared under the EPA/Multi-Jurisdictional Organization/state collaborative) project.^[13] The results of this updated modeling were released with the NPRM for the Revised CSAPR Update on October 30, 2020, and finalized in the final Revised CSAPR Update without changes. See86 FR 23054 (April 30, 2021). The updated modeling includes 2016 base year and 2023 projection year model simulations that were analyzed to identify receptors and determine interstate ozone contributions to these receptors in 2021. Specifically, EPA developed an interpolation technique based on modeling for 2023 and measured ozone data to determine ozone design values for 2021. To estimate average and maximum design values for 2021, EPA first performed air quality modeling for 2016 and 2023 to project measured 2016 design values to 2023. The 2023 design values were then coupled with the corresponding 2016 measured design values to estimate design values in 2021. The Air Quality Modeling technical support document (TSD) developed in connection with the Revised CSAPR Update, which is included in the docket for this supplemental proposal, describes the modeling and interpolation for estimating design values in 2021.^[14]

EPA's analysis for this supplemental proposal, supported by the modeling analysis completed in the Revised CSAPR Update, further substantiates EPA's proposed approval in the December 30, 2019, NPRM. To quantify the contribution of emissions from specific upwind states on 2021 8-hour design values for the identified downwind nonattainment and maintenance receptors, EPA first performed nationwide, state-level ozone source apportionment modeling for 2023. The source apportionment modeling provided contributions to ozone from precursor emissions of anthropogenic nitrogen oxides (NO_X) and volatile organic compounds (VOCs) in each state, individually. The modeled 2023 contributions were then applied in a relative sense to the 2021 average design value to estimate the contributions in 2021 from each state to each receptor. Details on the source apportionment modeling and the methods for determining contributions in 2021 are in the Air Quality Modeling TSD in the docket.

The 2021 design values and contributions were examined to determine if Florida, Georgia, North Carolina, and South Carolina contribute at or above the threshold of one percent of the 2015 8-hour ozone NAAQS (0.70 ppb) to any downwind nonattainment or maintenance receptor.^[15] Table 1 presents the highest contribution in 2021 from Florida, Georgia, North Carolina, and South Carolina to a downwind nonattainment or maintenance receptor.

Based on the analysis of the updated modeling as described above, EPA proposes to find that it is reasonable to conclude that Florida, Georgia, North Carolina, and South Carolina, individually, will not contribute greater than one percent of the 2015 8-hour ozone NAAQS to any potential nonattainment or maintenance receptors in 2021.

EPA also analyzed ozone precursor emissions trends in Florida, Georgia, North Carolina, and South Carolina to support the findings from the air quality analysis. In evaluating emissions trends, EPA first reviewed the information submitted by Florida, Georgia, North Carolina, and South Carolina and then reviewed additional information derived from EPA's National Emissions Inventory. EPA focused on state-wide emissions of NO_X and VOCs in Florida, Georgia, North Carolina, and South Carolina.^[17] Combined, emissions from mobile sources, electric generating units (EGUs), industrial facilities, gasoline vapors, and chemical solvents are a large percentage of anthropogenic emissions of ozone precursors. This evaluation looks at both past emissions trends, as well as projected trends.

As shown in Table 2, from 2011 to 2023 annual total NO_X and VOC emissions are projected to decline in the following amounts, respectively: By 56 percent and 35 percent in Florida; by 57 percent and 27 percent in Georgia; by 53 percent and 18 percent in North Carolina; and by 47 percent and 24 percent in South Carolina. The projected reductions are a result of the implementation of existing control programs that will continue to decrease NO_X and VOC emissions in Florida, Georgia, North Carolina, and South Carolina, as indicated by EPA's most recent 2021 and 2023 projected emissions used in the updated 2023 modeling.

As presented below in Table 3, onroad and nonroad mobile source emissions collectively ( i.e., mobile source emissions) comprise a large portion of these states' total anthropogenic NO_X and VOC ( i.e., 67 percent of the state total NO_X and 36 percent to state total VOC for Florida; 61 percent of the state total NO_X and 30 percent to state total VOC for Georgia; 57 percent of the state total NO_X and 31 percent to state total VOC for North Carolina; and 57 percent of the state total NO_X and 31 percent to state total VOC for South Carolina).

The large decrease in NO_X emissions between 2016 emissions and projected 2023 emissions in Florida, Georgia, North Carolina, and South Carolina are primarily driven by reductions in emissions from onroad and nonroad mobile sources. As shown by the mobile source emissions trends in Table 3, EPA projects that both VOC and NO_X emissions will continue declining out to 2023 as newer vehicles and engines that are subject to the most recent, stringent mobile source standards replace older vehicles and engines.²¹

In summary, based on the projected downward trend in projected future emissions trends, in combination with the historical decline in actual emissions, there is no evidence to suggest that the overall emissions trend demonstrated in Table 2 would suddenly reverse or spike in 2021 compared to historical emissions levels or those projected for 2023. Further, there is no evidence that the projected ozone precursor emissions trends beyond 2021would not continue to show a decline in emissions.^[22]

This downward trend in emissions in Florida, Georgia, North Carolina, and South Carolina adds support to the air quality analysis presented above and indicates that the contributions from emissions from sources in Florida, Georgia, North Carolina, and South Carolina to ozone receptors in downwind states will continue to decline and remain below one percent of the 2015 8-hour ozone NAAQS. Thus, based on this supplemental analysis, EPA continues to propose to conclude that the air quality and emissions analyses indicate that emissions from Florida, Georgia, North Carolina, and South Carolina will not significantly contribute to nonattainment or interfere with maintenance of the 2015 8-hour ozone NAAQS in any other state.

III. Supplemental Proposed Actions

In its December 30, 2019, NPRM, EPA originally proposed to find that emissions from sources in Florida, Georgia, North Carolina, and South Carolina will not significantly contribute to nonattainment or interfere with maintenance of the 2015 8-hour ozone NAAQS in any other state based on information for the analytic year 2023, consistent with the 2024 Moderate area attainment date. Thus, EPA proposed to approve the interstate transport portions of the infrastructure SIP submissions from Florida, Georgia, North Carolina, and South Carolina as meeting CAA section 110(a)(2)(D)(i)(I) requirements for the 2015 8-hour ozone NAAQS.^[23] See84 FR 71854.

The analysis presented in this notice provides a new primary basis for approval to supplement EPA's proposed finding in the December 30, 2019, NPRM. EPA continues to propose to find that emissions from sources in Florida, Georgia, North Carolina, and South Carolina will not significantly contribute to nonattainment or interfere with maintenance of the 2015 8-hour ozone NAAQS in any other state. Thus, EPA continues to propose to approve the interstate transport portions of the infrastructure SIP submissions from Florida, Georgia, North Carolina, and South Carolina as meeting CAA section 110(a)(2)(D)(i)(I) requirements for the 2015 8-hour ozone NAAQS.

IV. Statutory and Executive Order Reviews

Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the Act and applicable Federal regulations. See42 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. These actions merely propose to approve state law as meeting Federal requirements and do not impose additional requirements beyond those imposed by state law. For that reason, these proposed actions:

• Are not significant regulatory actions subject to review by the Office of Management and Budget under Executive Orders 12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
• Do not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
• Are 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.);
• Do 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);
• Do not have Federalism implications as specified inExecutive Order 13132 (64 FR 43255, August 10, 1999);
• Are not economically significant regulatory actions based on health or safety risks subject toExecutive Order 13045 (62 FR 19885, April 23, 1997);
• Are not significant regulatory actions subject toExecutive Order 13211 (66 FR 28355, May 22, 2001);
• Are not subject to requirements of Section 12(d) of the National ( printed page 37948) Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA; and
• Do not provide EPA with the discretionary authority to address, as appropriate, disproportionate human health or environmental effects, using practicable and legally permissible methods, underExecutive Order 12898 (59 FR 7629, February 16, 1994).

The SIP is not approved to apply on any Indian reservation land or in any other area where EPA or an Indian tribe has demonstrated that a tribe has jurisdiction. In those areas of Indian country, the rule does not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), nor will it impose substantial direct costs on tribal governments or preempt tribal law.

For South Carolina, because this proposed action merely proposes to approve state law as meeting Federal requirements and does not impose additional requirements beyond those imposed by state law, this action for the state of South Carolina does not have Tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000). Therefore, this proposed action will not impose substantial direct costs on Tribal governments or preempt Tribal law. The Catawba Indian Nation Reservation is located within the boundary of York County, South Carolina. Pursuant to the Catawba Indian Claims Settlement Act, S.C. Code Ann. 27-16-120 (Settlement Act), “all state and local environmental laws and regulations apply to the Catawba Indian Nation and Reservation and are fully enforceable by all relevant state and local agencies and authorities.” The Catawba Indian Nation also retains authority to impose regulations applying higher environmental standards to the Reservation than those imposed by state law or local governing bodies, in accordance with the Settlement Act.

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

86 FR 37942