2024-22681. Clean Air Plans; Contingency Measures for the Fine Particulate Matter Standards; San Joaquin Valley, California

Table 2—Revised Annual Average Emission Reductions From District and CARB Contingency Measures

[tpd]

Contingency measure	1997 Annual PM 2.5 NAAQS		2006 24-Hour PM 2.5 NAAQS		2012 Annual PM 2.5 NAAQS
	Direct PM 2.5	NO X	Direct PM 2.5	NO X	Direct PM 2.5	NO X
District: Residential Wood Burning (first triggering event)	0.5793	0.0817	0.5793	0.0817	0.5793	0.0817
District: Non-agricultural Rural Open Areas	0.008		0.008		0.008
CARB: Smog Check (first triggering event)		0.117		0.120		0.086
Total	0.5873	0.1987	0.5873	0.2017	0.5873	0.1677

Table 3—Revised EPA Evaluation of District and CARB Contingency Measures as Percentage of One Year's Worth of RFP and One Year's Worth of Progress

PM 2.5 NAAQS	Pollutant	One year's worth of RFP			One year's worth of progress
		Reductions target	% OYW (no trading)	% OYW (with trading) a	Reductions target	% OYW (no trading)	% OYW (with trading) a
1997 Annual	Direct PM 2.5 NO X	0.44 16.7	132 1.2	100 6.3	0.41 7.9	142 2.5	100 b  15.8
2006 24-hour	Direct PM 2.5 NO X	0.58 18.4	101 1.1	100 1.3	0.52 6.7	112 3.0	100 b  8.9
2012 Annual	Direct PM 2.5 NO X	0.46 15.3	129 1.1	100 6.3	0.43 8.7	138 1.9	100 13.1
a  The EPA has calculated % OYW (With Trading) for NO X based on the 6:1 ratio presented in the SJV PM 2.5 Contingency Measure SIP. ( print page 80753)
b  The percentage of OYW of Progress (With Trading) is 0.1% higher in this table for NO X for the 1997 annual and 2006 24-hour PM 2.5 NAAQS relative to Table 3 of our proposed rule.

II. Public Comments and EPA Responses

The EPA's proposed action provided a 30-day public comment period. During this period, we received comment letters from three organizations or groups. CARB submitted a letter supporting the EPA's proposed approval.^[26] A group of four environmental, public health, and community organizations (collectively referred to herein as “Valley EJ Organizations”) submitted adverse comments,^[27] and a separate group of five environmental, public health, and community organizations (collectively referred to herein as “CVAQ”) submitted adverse comments.^[28] To the extent that certain comments by the Valley EJ Organizations solely pertain to the Smog Check Contingency Measure and the State's commitments to submit attainment contingency measures for the 1997 ozone NAAQS, we have addressed those comments in a separate final rule on the Smog Check Contingency Measure.^[29]

Comment 1: The Valley EJ Organizations assert that the EPA's proposed approval of the PM_2.5 contingency measures departs from the EPA's long-standing interpretation requiring OYW of RFP. They further state that the proposed approvals based on the Draft Revised Contingency Measure Guidance violate CAA section 172(c)(9) by severing the amount of required emission reductions from the parallel and related RFP requirement when the EPA shifts from its OYW of RFP to its new OYW of progress interpretation. The Valley EJ Organizations further assert that the plain meaning does not allow, and the EPA cannot provide a reasoned justification for, an interpretation that requires less than that which the Act requires for RFP and that, here, the PM_2.5 contingency measures plainly provide reductions far less than OYW of RFP. The CVAQ Comment Letter echoes these points, stating that the emission reductions from the Residential Wood Burning Contingency Measure and the Rural Open Areas Contingency Measure would “fall well short of the emission reductions needed to comply with the weakened average annual reduction requirement in EPA's draft guidance even when allowing for the interpollutant substitution of excess direct PM_2.5 emissions for NO_X emissions.” ^[30]

Response to Comment 1: Regarding emission reduction metrics ( i.e., the recommended amount of emission reductions that contingency measures should achieve), we disagree with commenters as to what is required under the CAA and with the commenters' broader framing of contingency measures within the overall planning requirements for nonattainment areas. While there is a statutory link between RFP and the contingency measure requirements of CAA section 172(c)(9), it does not function as the commenter suggests ( i.e., to establish an amount of emission reductions that contingency measures should achieve). The statutory text of this provision is as follows:

CAA section 172(c)(9) (“Contingency measures”)—“Such plan shall provide for the implementation of specific measures to be undertaken if the area fails to make reasonable further progress, or to attain the national primary ambient air quality standard by the attainment date applicable under this part. Such measures shall be included in the plan revision as contingency measures to take effect in any such case without further action by the State or the Administrator.”

Thus, while section 172(c)(9) requires contingency measures where an area fails to make RFP, the language does not specify what amount of emission reductions such measures should achieve ( i.e., does not explicitly tie the amount of reductions to RFP). Moreover, the statutory text also has a link to attainment, but it too does not specify what amount of emission reductions contingency measures should achieve.

While Congress did not specify an amount that contingency measures must achieve to comply with CAA section 172(c)(9), Congress must have intended the amount to be material because, without a specified amount, a state would not know how to comply with the requirement. Thus Congress must have at least implicitly delegated to the EPA the authority to determine an amount of emissions reductions that contingency measures should achieve and thereby give meaning to the requirement and provide states with a basis to comply with CAA section 172(c)(9) for a given nonattainment area. The EPA has taken a policy approach to this question, and in the past, the EPA has indicated that the recommended amount is OYW of RFP but allowed states to provide a reasoned justification for adopting contingency measures that would provide less than the recommended amount. Under the Draft Revised Contingency Measure Guidance, the EPA is continuing to take a policy approach but is recommending OYW of progress and describing a specific analytical framework that states may use to develop a reasoned justification if the state is unable to identify and adopt contingency measures that can achieve the recommended amount of emissions reductions.^[31]

In support of our revised approach, we first note that, for both RFP and attainment purposes, contingency measures are intended to provide for continued progress in the event that an area fails to meet an RFP milestone or fails to attain the NAAQS by the applicable attainment date. They are not themselves expected to provide for either RFP or attainment. With respect to RFP, the CAA provides certain remedies if the contingency measures do not make up the shortfall for a given RFP milestone.^[32] With respect to a failure to attain by the applicable attainment date, the CAA too provides a remedy by requiring a new attainment plan.^[33]

( print page 80754)

In reviewing our long-standing approach to contingency measures, the EPA observed that basing the amount of emission reductions on the annual amount of reductions needed to meet the separate RFP requirement—OYW of RFP—may in some cases lead to an amount that is greater than what typically would be needed to make up for a shortfall in RFP or for attainment purposes.^[34] The OYW of RFP approach was unnecessarily conservative for estimating the amount of emission reductions needed for contingency measure purposes because a given percentage of the base year inventory tends to represent a much more significant portion of the attainment projected inventory.

In shifting to the OYW of progress approach, the EPA recognizes attainment of the NAAQS as the primary objective of the nonattainment plan requirements, and thus the appropriate metric should be attainment-focused. In the absence of a CAA-specified amount of emission reductions required for contingency measures, the EPA's new approach is a better reading of the contingency measure SIP requirement given our understanding of the statutory purpose of contingency measures following a failure to attain or to meet an RFP milestone, which is to ensure uninterrupted progress toward attainment while the next steps unfold in response to the failure. In addition, unlike the previous approach, the EPA's new approach takes into account the declining emissions inventories between the base year and attainment year for a given nonattainment area and aligns the metric for determining the amount of emission reductions that contingency measures should achieve for ozone and particulate matter (PM). The alignment between ozone and PM is a better reading of the statute considering that the relevant statutory provision, CAA section 172(c)(9), applies to all the NAAQS.

As to the specific SIP submission addressed in this document, we acknowledge that CARB and the District used the newly-recommended metric in preparing the SJV PM_2.5 Contingency Measure SIP for which the EPA is now finalizing approval but, in this instance, the SIP submission and the EPA's evaluation thereof would have been the same in substance if the previous metric ( i.e., OYW of RFP) had been used instead. This is because, using either metric, the SIP submissions include contingency measures that collectively provide for OYW of progress or RFP for direct PM_2.5 and a portion of OYW of progress or RFP for NO_X .^[35] The only difference is the extent to which the emission reductions from the contingency measures fall short of each metric for NO_X reductions. Using the OYW of progress metric (with trading), the contingency measures are estimated to achieve between 8.9% and 15.8% of OYW of progress for NO_X as compared to between 1.3% and 6.3% of OYW of RFP for NO_X using the previously-recommended metric (with trading).^[36] Using either metric, the EPA would have expected the State to provide a reasoned justification for not adopting contingency measures sufficient to achieve greater NO_X emission reductions; consistent with the EPA's recommendations in the Draft Revised Contingency Measure Guidance, CARB and the District provided such reasoned justification in their infeasibility demonstrations.

Comment 2: The Valley EJ Organizations assert that the EPA's proposed approval of the State's 2023 SIP Submissions circumvents three recent court decisions ^[37] and unlawfully and arbitrarily (a) lowers the amount of emission reductions required for contingency measures (“by severing the statutory link to [RFP],” i.e., by shifting from OYW of RFP under the EPA's prior interpretation to OYW of progress under the EPA's revised interpretation), (b) extends implementation of contingency measures from one year to two years, and (c) invents a new feasibility exemption that does not appear in CAA section 172(c)(9). The commenters state that the EPA's proposed approval relies on the Draft Revised Contingency Measures Guidance “to replicate the arbitrary and capricious interpretation the [ AIR] court invalidated.”

Response to Comment 2: In relevant part, the Bahr and Sierra Club decisions stand for the proposition that contingency measures under CAA section 172(c)(9) must be conditional and prospective, and thus, already-implemented control measures cannot serve as contingency measures. The AIR decision stands for the proposition that surplus emission reductions from already-implemented measures cannot be relied upon as a justification for adoption of contingency measures that provide for less than the recommended amount of emission reductions for such measures. However, none of the cited court decisions bear on the questions of the amount of emission reductions that contingency measures should achieve, the timeline for achieving the emission reductions from contingency measures, or the consideration of feasibility of additional measures as justification for not adopting contingency measures sufficient to achieve the recommended amount of such measures.

Moreover, our proposed approval of the SJV PM_2.5 Contingency Measure SIP is consistent with the three cited decisions in that the SIP relies on contingency measures (Residential Wood Burning Contingency Measure, the Rural Open Areas Contingency Measures, and the Smog Check Contingency Measure) that are designed to be conditional and prospective. In addition, as discussed further in the following paragraph, the State has not relied on emission reductions from already-implemented measures.

The rationale for our approval of the SJV PM_2.5 Contingency Measure SIP is not the same as the rationale for our approval, later withdrawn in response to the AIR decision, of the contingency measure element for San Joaquin Valley for the 2008 ozone NAAQS that was at issue in the AIR case. In the case of the contingency measure element for the 2008 ozone NAAQS, the EPA took into account the surplus emission reductions from already-implemented measures in the milestone years and the years following the attainment date, not as constituting contingency measures per se, but rather, as justification for approving a contingency measure element that included a single contingency measure that would provide for far less than the recommended amount.

The Court found that, by doing so, the EPA had “severed the relationship between the requirement of contingency measures and the benchmark of reasonable further progress, without an adequate explanation of why the new—and far more modest—contingency measure is reasonable.” ^[38] The Court did not indicate that the Agency could not depart from previous guidance but cautioned that the EPA “must give a reasoned explanation for departing from agency practice or policy.” ^[39] The Court concluded that “[I]f already-implemented measures cannot themselves be contingency measures—and Bahr makes clear that they cannot—then neither can they be a basis for declining to establish contingency measures that would otherwise be ( print page 80755) appropriate.” ^[40] The Court rejected the EPA's rationale for allowing consideration of surplus emission reductions from already-implemented measures, reasoning that the EPA could not approve a contingency measure element “lacking robust contingency measures by assuming that they will not be needed. Because the agency did not provide a reasoned explanation for approving the state plan, the rule is arbitrary and capricious.” ^[41]

In the wake of the AIR decision, and other case law interpreting the contingency measure SIP requirement, the EPA undertook an internal process to reconsider previous guidance provided by the Agency to states for preparation of SIP submissions to meet the contingency measure requirements—a process that led to the publication of the Draft Revised Contingency Measure Guidance. Among other things, in the Draft Revised Contingency Measure Guidance, the EPA explains why the Agency believes that it is appropriate to update its prior guidance with respect to the recommended amount of emission reductions that contingency measures should achieve and the considerations that states could use to justify adoption of contingency measures that do not provide for the recommended amount of emission reductions.^[42] We found that an update to our contingency measures guidance was justified in light of changed factual circumstances ^[43] and a current understanding of what remaining controls may be available for states to adopt as contingency measures. For a more detailed explanation of our rationale for updating the metric, see Response to Comment 1, and for a more detailed explanation for allowing for consideration of feasibility, see Response to Comment 4.

With respect to this action, CARB and the District have adopted a contingency measure element that includes three contingency measures that would collectively achieve the recommended amount of emission reductions for one of the two pollutants or precursors at issue, and they have provided a reasoned justification in the form of infeasibility demonstrations for adopting contingency measures that provide for less than the recommended amount for the other relevant pollutant or precursor. The EPA's approval of a contingency measure element that relies, in part, on CARB and the District's infeasibility demonstrations, rather than relying on surplus emission reductions from already-implemented measures, stands in contrast to the EPA action on the SIP submission at issue in AIR. The EPA does not assume that contingency measures would not be needed for San Joaquin Valley but rather that CARB and the District have adequately demonstrated that there are no feasible contingency measures for that particular pollutant or precursor that are left to adopt or that could be implemented within one to two years of the triggering event.

Comment 3: For areas with more severe air pollution, such as Serious PM_2.5 nonattainment areas, the commenters state that the EPA has not articulated a reasoned justification for why OYW of progress is consistent with the CAA remedial scheme that imposes more stringent requirements on such areas. They suggest that a voluntary reclassification of an area ( e.g., from “Moderate” to “Serious” for PM_2.5) would lower the average annual reductions needed for contingency measures ( e.g., if the same attainment year inventory applied for a Moderate or Serious areas, then the annual average reduction would be lower due to averaging over more years).

In addition, the commenters illustrate a purported fatal flaw in the EPA's interpretation of OYW of progress using a table that shows OYW of progress for NO_X in a hypothetical ozone reclassification from Serious to Extreme (in tons per day of NO_X) and state that a lesser amount of emission reductions for contingency measures for such hypothetical Extreme ozone nonattainment area runs contrary to the structure of the Act.

Response to Comment 3: As explained in more detail in our Response to Comment 1, with respect to this specific action, the use of the new OYW of progress metric here does not materially impact our approval where the SJV PM_2.5 Contingency Measure SIP falls short of the emissions reductions recommended under either metric. However, we note that, contrary to commenters' assertions, the EPA's interpretation of the contingency measure requirement under CAA section 172(c)(9) is consistent with the CAA's general scheme of subjecting areas with higher classifications to more stringent requirements. More specifically, the increased stringency relates to the types of measures that qualify as contingency measures rather than the amount of emission reductions that such measures must achieve.

Under the EPA's interpretation of the contingency measure requirement, contingency measures must be designed to provide emission reductions (if triggered) that are not otherwise required to meet other attainment plan requirements and not relied upon to demonstrate RFP nor attainment. Thus, for example, contingency measures in PM_2.5 nonattainment areas classified as Moderate, which are thereby subject to the reasonably available control measures (RACM) requirement, must be measures that go beyond the RACM requirement, whereas contingency measures in PM_2.5 nonattainment areas classified as Serious (and thus subject to the best available control measures (BACM) requirement) must be measures that go beyond the BACM requirement. In other words, reclassification of an area to a higher classification shrinks the pool of candidate contingency measures because some of the candidate contingency measures will be required to be adopted and implemented in the reclassified area to meet the specific control requirements for that classification and, thus, will be unavailable for adoption as contingency measures. The candidate contingency measures that remain eligible to meet the contingency measure SIP requirement under the higher classification are different, and potentially more stringent, than those that had been available to meet the requirement under the lower classification. While more stringent measures would achieve further emission reductions, if triggered, they may achieve a smaller scale of emission reductions than the prior iterations of increasingly stringent control measures on a given emission source; stringency (a relative measure) is not the same as tons per day of emission reductions (an absolute measure).

Regarding the commenters' assertion that areas with more severe air pollution should have contingency measures that achieve a larger amount of emission reductions ( i.e., OYW of RFP), we look once more to the broader framing of contingency measures within the overall planning requirements for nonattainment areas. The EPA finds that the statutory and regulatory ( print page 80756) requirements to demonstrate attainment as expeditiously as practicable, and the absence of a specific statutory metric for how much emission reductions contingency measures should achieve, give priority to adopting control measures to attain in the first place, even if that leaves fewer options for contingency measures in the event of a failure to attain or to make RFP.

In the SJV PM_2.5 Contingency Measure SIP, the State elaborates further on using an attainment-focused metric by highlighting the scarcity of potential control measures that would qualify as contingency measures given the facts and circumstances of the San Joaquin Valley,^[44] where the progressively stringent set of control measures adopted to meet prior attainment and RFP planning requirements are already implemented measures and therefore ineligible to serve as contingency measures.^[45] This scarcity concept echoes the tension between the CAA requirements for attainment and contingency measures, and the prioritization of adopting measures to attain in the first place. Notwithstanding, the EPA does not endorse the scarcity concept as a starting point, but rather recommends the detailed analytical approach to identifying and evaluating potential control measures that can serve as contingency measures, as described in the Draft Revised Contingency Measures Guidance, and that the State employed in developing the PM_2.5 Contingency Measure SIP.

Regarding the commenters' suggestion that a state could reduce the amount of emission reductions needed for contingency measures by requesting a voluntary reclassification that would extend the amount of time to attain while relying on the same level of emission reductions, we disagree that such an action runs contrary to the general remedial scheme of the CAA that imposes more stringent requirements on reclassified areas. Under the statutory and regulatory requirements for PM_2.5 , a State may request reclassification from Moderate to Serious, but only where it can show that it is impracticable to attain by the Moderate area attainment year.^[46] Thus, a combination of direct PM_2.5 and plan precursor emission reductions that would achieve attainment would constrain the ability of the State to seek such reclassification—it would instead be practicable to attain by the Moderate area attainment date. Similarly, if the Moderate area attainment year were approaching and air quality for two of three design value years indicated that the area would not achieve the standard, then the air quality basis resulting from prior attainment planning would be insufficient to attain. In either case, the State would need to develop a Serious area plan that achieves additional emission reductions and also addresses the additional control requirements for Serious areas ( e.g., tighter new source review requirements, BACM and best available control technology (BACT), and, if the State were to seek an attainment date extension under CAA section 188(e), most stringent measures (MSM)).

For these reasons, as well as those described in Response to Comment 1 of this document, we conclude that the EPA's revised metric for contingency measure emission reductions (OYW of progress) does not run contrary to the general remedial scheme of the CAA that imposes more stringent requirements on areas reclassified to a higher classification. Lastly, the EPA finds that the comment on a hypothetical scenario for an ozone nonattainment area is outside the scope of this rulemaking because we are not acting on ozone contingency measure SIP submissions in this action.

Comment 4: Regarding feasibility assessments, the Valley EJ Organizations state that the CAA does not subject the contingency measure requirements to a feasibility standard and reject the State's and the EPA's proposed reliance on infeasibility demonstrations. The commenters argue that Congress made no exceptions to the contingency measure requirements nor did it provide authority to relax those requirements based on technological or economic challenges. They state that the CAA requirements for RACM or reasonably available control technology (RACT) include a “reasonably available” qualifier and that those for MSM are expressly limited to “feasible” measures, while such terms do not appear in the CAA requirements for contingency measures. They contend that the EPA conflates the contingency measure requirements with the primary requirements to attain the NAAQS in the first place. They further state that Congress expressly provided limited authority to relax the CAA requirements for RFP but did not do so for contingency measures.

The commenters state that the RACM requirements (under CAA sections 172(c)(1), 181(a)(1), and 188(c)(1)) require that the primary attainment strategy include “all” RACM and other available control measures that would expedite attainment and that the MSM provision (for Serious PM_2.5 nonattainment areas that cannot attain the standards within 10 years, under CAA section 188(e)) requires additional control measure implementation. They argue that contingency measures should not comprise the same controls that the CAA already requires for attainment and that failed to attain the NAAQS in the first place and that the EPA unlawfully and arbitrarily excuses contingency measures needed when the feasible measures the State has already adopted result in a failure to attain the NAAQS (citing AIR, 10 F.4th at 946).

Given these alleged flaws in the EPA's interpretation, the commenters state that the EPA's proposed approval violates the plain meaning of the CAA contingency measure requirement, fails to reasonably explain the Agency's relaxation of the emission reductions that contingency measures must provide, and is therefore arbitrary and capricious.

Response to Comment 4: As discussed in Response to Comment 1, Congress must have at least implicitly delegated to the EPA the authority to determine an amount of emissions reductions that contingency measures should achieve and thereby give meaning to the requirement and provide states with a basis to comply with CAA section 172(c)(9) for a given nonattainment area. The EPA is continuing to take a policy approach to this question and is recommending OYW of progress and describing a specific analytical framework that states may use to develop a reasoned justification if the state is unable to identify and adopt contingency measures that can achieve the recommended amount of emissions reductions. More specifically, as stated in our proposed rule and the EPA's Draft Revised Contingency Measures Guidance, where a state is unable to identify contingency measures that would provide approximately OYW of emission reductions, the state should provide a reasoned justification (referred to herein as an “infeasibility demonstration”) that explains and documents how it has evaluated all existing and potential control measures relevant to the appropriate source categories and pollutants in the nonattainment area and has reached reasonable conclusions regarding whether such measures are feasible.^[47] Thus, while the EPA acknowledges that ( print page 80757) CAA section 172(c)(9) does not explicitly provide for consideration of whether specific measures are feasible, the EPA does not read the statute to require air agencies to adopt and impose infeasible measures.^[48]

As stated in the proposed rule, the statutory provisions applicable to other nonattainment area plan control measure requirements, including RACM/RACT, BACM/BACT, and MSM, allow air agencies to exclude certain control measures that are deemed unreasonable or infeasible (depending on the requirement).^[49] For example, the MSM provision in CAA section 188(e) requires plans to include “the most stringent measures that are included in the implementation plan of any state or are achieved in practice in any state, and can feasibly be implemented in the area.” While the contingency measures provisions do not include such caveats, the EPA does not conclude that the contingency measures provisions should be read to require plans to include infeasible measures. Thus, the EPA anticipates that a demonstrated lack of feasible measures would be a reasoned justification for adopting contingency measures that achieve less than the recommended amount of emission reductions.^[50]

The EPA does not, as the commenters suggest, simply conflate the contingency measure requirements with other control requirements ( e.g., RACM/RACT, BACM/BACT, and MSM) that are integral to demonstrating attainment of the ozone and/or PM_2.5 NAAQS. Rather, while the analytical approach to identifying and evaluating existing and potential control measures may be similar to those used for RACM/RACT, BACM/BACT, and MSM ( e.g., identifying the universe of control devices that can reduce NO_X emissions from combustion equipment and whether they are technologically and economically feasible as applied to a specific type of emission source in the area), the EPA expects that the state “should not simply repeat the control strategy's infeasibility showing.” ^[51] The contingency measure requirement is in addition to the other control measure requirements.

A conclusion that a measure is not reasonable or feasible, for example, for RACM does not automatically disqualify it as a potential contingency measure. If the state identifies control measures that it determines are not needed to attain nor to collectively advance attainment, those measures would not be required to satisfy the RACM requirement but would remain as candidates for contingency measures. To the extent that the adopted contingency measures achieve a small amount of emission reductions, the state should provide a more robust infeasibility showing that there are no additional feasible contingency measures that could achieve the recommended amount of reductions.^[52] Furthermore, to the extent that the state's analyses and development of contingency measures occur after the state's analyses and development of the SIP submissions to meet the attainment control strategy requirements of the CAA (including associated control requirements and RFP), the state should update their analyses to reflect the latest potential control measures.

In the case of the SJV PM_2.5 Contingency Measure SIP, submitted in 2023, CARB and the District documented their analyses to identify and evaluate potential control measures that might serve as contingency measures. These analyses are updated relative to their 2021 submission of the Serious area attainment plan for the 1997 annual PM_2.5 NAAQS and to their 2019 submissions of the Serious area attainment plan for the 1997 24-hour PM_2.5 NAAQS (including BACM demonstration), Serious area plan for the 2006 24-hour PM_2.5 NAAQS (including demonstrations for BACM and MSM), and Moderate area plan for the 2012 annual PM_2.5 NAAQS (including RACM demonstration). The EPA has approved these attainment plan control strategies in successive actions ^[53] and they represent an overall stringent set of control requirements. The State did not set aside measures for lack of their ability to collectively advance attainment (as might be possible in theory, e.g., for RACM for an ozone nonattainment area).

In their updated analyses, CARB and the District considered the wide range of emission sources under their primary jurisdiction, identified potential control measures, analyzed their technological and economic feasibility, and assessed whether they could achieve emission reductions within one to two years of a triggering event, consistent with the EPA's discussion of the timing objective inherent to the contingency measure requirement.^[54] For the potential control measures identified through this process, the District further analyzed possible contingency measures for wood burning fireplaces and wood burning heaters, rural open areas, commercial charbroiling, almond harvesting, and oil and gas production combustion equipment, and ultimately adopted the Residential Wood Burning Contingency Measure and the Rural Open Areas Contingency Measure.

CARB, in turn, made a reasonable case that new engine standards and new fleet requirements require more time to implement than would be appropriate for contingency measures ( i.e., would exceed one to two years after a triggering event) and that the State's technology-forcing and zero-emission-based nature of its mobile source regulations reduce or eliminate opportunities for yet-further emission reductions that could qualify as contingency measures.^[55] Nevertheless, through its process CARB ultimately adopted the Smog Check Contingency Measure.

The three contingency measures proposed for approval stand in contrast to the commenters' argument that the feasibility assessment process put forward in the EPA's Draft Revised Contingency Measure Guidance, in the State's 2023 SIP Submissions, and the EPA's proposed approval thereof would simply re-employ the control measures originally employed to attain the PM_2.5 NAAQS in the San Joaquin Valley. Furthermore, in many instances the ( print page 80758) reason for which the EPA agreed with the State for not adopting a potential control measure as a contingency measure was not based on any affirmation that a measure was economically infeasible, but rather was based on other reasons. In evaluating CARB and the District's infeasibility demonstrations in the SJV PM_2.5 Contingency Measure SIP, we relied heavily on the “EPA Source Category and Control Measure Assessment and Reasoned Justification Technical Support Document, Proposed Contingency Measures Federal Implementation Plan for the Fine Particulate Matter Standards for San Joaquin Valley, California,” July 2023 (“EPA's Reasoned Justification TSD”) given its breadth and depth, as well as the expertise of EPA Region IX staff, to review the State's demonstrations, understand where the State's analyses and the EPA's analyses draw largely similar conclusions, and identify those source categories where the control measure analyses differ.

For example, for the potential control measure of requiring electric water heaters and furnaces at point of sale, the EPA determined that such a measure would not be feasible because we expect that it would result in negligible emission reductions within two years after trigger, consistent with the District's suggestion that the attrition-based nature of implementation of this contingency measure option deem the measure infeasible.^[56] For the potential control measure of requiring low-dust almond harvesters, the EPA determined that such a measure would be infeasible based only on the timing of emission reductions.^[57]

For the potential control measure of requiring the installation of control devices on commercial under-fired charbroilers, the EPA determined that such measure would be infeasible based on fire safety certification concerns and lack of demonstrated implementation of controls.^[58] For the potential control measure of lower NO_X emission limits on oil and gas production equipment with a total rated heat input of greater than 5.0 million Btu per hour, the EPA determined that it would be technologically infeasible to meet the lower limits within the two-year timeframe for contingency measures due to the likely requirement that affected units would need to install selective catalytic reduction (SCR) devices to meet the lower limits ( i.e., the planning, engineering, and installation of SCR would take more than two years).^[59] Similarly, for the potential control measure of lower NO_X emission limits for boilers, steam generators, and process heaters with a total rated heat input of 5.0 million Btu per hour or less, the EPA expects that units required to meet lower limits than those already adopted in Rules 4307 and 4308 would require installation of SCR, which cannot be feasibly achieved within the two-year timeframe for contingency measures.^[60]

In sum, the EPA maintains that it does not read the statute to require air agencies to adopt and impose infeasible measures. Furthermore, as applied to the SIP submissions subject to this rulemaking, we continue to find that the State's three contingency measures for the San Joaquin Valley for the 1997 annual, 2006 24-hour, and 2012 annual PM_2.5 NAAQS, in conjunction with the State's infeasibility demonstrations that adequately justify the contingency measures selected by the State, meet the contingency measure requirement under CAA section 172(c)(9) and 40 CFR 51.1014.

Comment 5: The Valley EJ Organizations assert that the EPA unlawfully and arbitrarily proposes approval of the PM_2.5 contingency measures based on the Agency's new interpretation in the Draft Revised Contingency Measures Guidance by extending the implementation period from one year to two years.

Response to Comment 5: With respect to the issue of extending the period in which the emission reductions from contingency measures can be considered in meeting the contingency measure SIP requirement, we note that the commenters raise this particular objection to the EPA's proposed approval in a single sentence and fail to elaborate on how extending the time period for achieving the emission reductions from contingency measures from one to two years conflicts with the CAA or the EPA's implementing regulations.

In this instance, we proposed, and are now taking final action, to approve two specific contingency measures (the Residential Wood Burning Contingency Measures and the Rural Open Areas Contingency Measures), both of which, if triggered, will achieve emission reductions within a year of the triggering event. Our approval of the 2023 SIP Submissions as meeting the contingency measure SIP requirement for San Joaquin Valley for the relevant PM_2.5 NAAQS also relies on emission reductions from a third contingency measure (the Smog Check Contingency Measure) that we have approved in a separate action.

As explained in the EPA's final rule on CARB's Smog Check Contingency Measure, the emission reductions from the Smog Check Contingency Measure may not be fully achieved until the second year after the triggering event.^[61] However, as further explained in that final rule, and consistent with the Draft Revised Contingency Measure Guidance, in instances where there are insufficient contingency measures available to achieve the recommended amount of emission reductions within one year of the triggering event, contingency measures that provide reductions within two years of the triggering event could be appropriate to consider toward achieving the recommended amount of emission reductions.^[62] Contingency measures that result in additional emission reductions during the second year following the triggering event, as contemplated by the Draft Revised Contingency Measure Guidance, can still serve the important purpose of contingency measures to continue progress toward attainment, as the State develops and submits, and the EPA acts on, a SIP submission to address the underlying condition ( e.g., failure to make RFP or to attain by the applicable attainment date) that triggered the contingency measures in the first place.

Comment 6: The Valley EJ Organizations state that, after a first triggering event, the EPA unlawfully and arbitrarily allows California discretion in adopting further contingency measures, fails to evaluate whether the emission reductions to follow a second triggering event would meet either OYW of RFP or OYW of progress, and allows California to “ `double dip' for contingency measure purposes” without enforceable provisions that would require adoption and submission of additional contingency measures.

Response to Comment 6: Our approval relates to the SIP requirements for contingency measures under CAA section 172(c)(9) and 40 CFR 51.1014 for the 1997 annual, 2006 24-hour and 2012 annual PM_2.5 NAAQS. Under the applicable requirements, states with PM_2.5 nonattainment areas must provide contingency measures that can be ( print page 80759) triggered in the event of a failure to meet any RFP requirement in an attainment plan, to meet any quantitative milestone in an attainment plan, to submit a quantitative milestone report, or to attain the applicable PM_2.5 NAAQS by the applicable attainment date.

Neither the CAA nor the EPA's regulations specify a minimum number of contingency measures or prescribe separate contingency measures for different contingency measure triggers. The CAA and the EPA's regulations also do not preclude the reliance on the same contingency measures for separate NAAQS, and the commenter does not identify any specific statutory or regulatory requirement that does so. Moreover, it is not uncommon for a state or district to rely on a core set of control measures for multiple NAAQS. For example, the State and District rely on a core set of NO_X control measures as part of the control strategies for demonstrating RFP and attainment for both ozone and PM_2.5 in the San Joaquin Valley. Regardless, we acknowledge that neither the State nor District has submitted an enforceable commitment to submit additional contingency measures in response to the triggering of the contingency measures. The EPA does not believe that such commitment is required.

In this instance, the 2023 SIP Submissions rely on three contingency measures, all of which provide for an initial triggering event and two of which provide for a second triggering event. In other words, all three contingency measures provide for implementation of more stringent requirements upon a first triggering event, and two of the contingency measures also provide for implementation of yet more stringent requirements upon a second triggering event ( i.e., further tightening of the requirements beyond that triggered by the first event).

While the EPA is not requiring CARB or the District to provide separate contingency measures for each of the triggering events or separate contingency measures for different PM_2.5 NAAQS in San Joaquin Valley, we find that a SIP deficiency would arise upon the first triggering event notwithstanding the existence of the built-in provisions for further reductions upon a second triggering event. This is because the adequacy of the contingency measure SIP depended on measures that are now being implemented as a result of the first triggering event, meaning they can no longer be used to satisfy the contingency measure requirements for subsequent triggering events. In response, we expect that CARB and the District would adopt and submit a SIP revision within one year of the triggering event to demonstrate that the SIP continues to meet contingency measure requirements. We would also expect the SIP revision to take into account the emission reductions from the two remaining contingency measures and to include additional contingency measures as needed to ensure that the San Joaquin Valley continues to meet the contingency measure requirements of CAA section 172(c)(9) and 40 CFR 51.1014.

Comment 7: CVAQ asserts that the “hot spot” approach under District Rule 4901, “Wood Burning Fireplaces and Wood Burning Heaters,” “cannot meet the basic control measure requirements of the [CAA]” and that the emission reductions from expanding applicability to previously exempt areas would not be surplus to the controls that should be required in the San Joaquin Valley. If, however, residential wood burning is to be used as a contingency measure, CVAQ contends that the contingency measure in Rule 4901 should ban all non-essential wood burning. CVAQ further contends that the District must adopt contingency measures that would achieve OYW of RFP emission reductions in each county of the San Joaquin Valley to protect its most vulnerable communities. In addition, citing comments made by residents during 2023 District workshops that report incidents of poor enforcement of the rule, CVAQ asserts that Rule 4901 has no assurance of actual emission reductions and no concrete commitments for enforcement. CVAQ advocates for accountability measures to ensure actual emission reductions and enforcement of residential wood burning regulations.

Response to Comment 7: The EPA maintains that the Residential Wood Burning Contingency Measure in SJVUAPCD Rule 4901 meets the contingency measure requirements and provides reasonable assurance of emission reductions. As explained in our proposed rule,^[63] Rule 4901 includes a tiered mandatory curtailment program that establishes different curtailment thresholds based on the type of devices ( i.e., registered clean-burning devices vs. unregistered devices) and different counties ( i.e., “hot spot” vs. non-hot spot), notwithstanding narrow exemptions ( e.g., for households where a wood burning fireplace or heater is the sole source of heat, per section 5.7.4.2 of Rule 4901). During a “Level One Episodic Wood Burning Curtailment,” operation of wood-burning fireplaces and other unregistered wood-burning heaters or devices is prohibited, but properly operated, registered wood-burning heaters may be used. During a “Level Two Episodic Wood Burning Curtailment,” operation of any wood-burning device is prohibited.

In 2019, the District lowered the curtailment thresholds in Madera, Fresno, and Kern counties, which the District identified as hot spot counties, because they were “either new areas of gas utility or areas deemed to have persistently poor air quality.” ^[64] Table 4 presents the wood burning curtailment thresholds in Rule 4901, as revised in 2019.

Table 4—Residential Wood Burning Curtailment Thresholds in Rule 4901

[as amended in 2019]

Episodic wood burning curtailment levels	Hot spot counties (Madera, Fresno, and Kern)	Non-hot spot counties (San Joaquin, Stanislaus, Merced, Kings, and Tulare)
Level One (No Burning Unless Registered)	12 μg/m3	20 μg/m3 .
Level Two (No Burning for All)	35 μg/m3	65 μg/m3 .