Air Plan Approval; Montana; Missoula, Montana Oxygenated Fuels Program Removal, Carbon Monoxide, Limited Maintenance Plan

Supplementary Information

Throughout this document wherever "we," "us," or "our" is used, we mean the EPA.

I. Background

The EPA is proposing to approve a SIP revision submitted by Montana on January 30, 2024, requesting to change the status of the oxyfuels program in the Missoula CO LMP from an active control measure to a contingency measure. To support the request, Montana's January 30, 2024 SIP revision contains technical support materials to demonstrate that the removal of the rules as a control measure will not interfere with attainment or maintenance of the CO NAAQS or with any other applicable requirement of the CAA. In addition to the technical support materials provided by Montana, the EPA has provided supplemental technical support documentation to further demonstrate non-interference. ⁽¹⁾ Specifically, these SIP revisions address State regulations amended in the Missoula City-County Air Pollution Control (MCCAPC) program rules, Chapter 10: Fuels, Subchapter 1: Oxygenated Fuels Program, rules 10.102(1), 10.105(1), 10.109(1), 10.110, 10.111, 10.111(2).

The EPA's analysis of Montana's January 30, 2024 SIP revision that is the subject of this proposed rule is organized into two parts under section II. of this document. Part A provides the background, analysis, and discussion of the non-interference demonstration for the change in status of Montana's oxyfuels program from a control measure to a contingency measure in the federally approved Montana SIP; Part B contains information regarding rules submitted for revision in MCCAPC Chapter 10: Fuels, Subchapter 1: Oxygenated Fuels Program . The EPA is proposing to act on the revisions listed in this action and will act on the additional rule revisions listed in the January 30, 2024 SIP revision submission in a separate action.

II. The EPA's Evaluation

A. Removal of the Oxygenated Gasoline Program as a Control Measure

1. Missoula, Montana Oxygenated Gasoline Program and CO NAAQS Maintenance

The EPA designated Missoula, Montana, as nonattainment for CO under the provisions of the 1977 CAA Amendments on March 3, 1978 (43 FR 8962). Under the CAA Amendments of 1990, the Missoula area was designated as nonattainment and classified as a "Moderate" CO area, with a design value of less than or equal to 12.7 parts per million (ppm) and was required to attain the CO NAAQS by December 31, 1995 (56 FR 56694, November 6, 1991). ⁽²⁾ Under section 211(m) of the CAA, states with areas designated nonattainment for CO with certain design values were required to submit revisions to their SIPs and implement oxygenated gasoline programs by no later than November 1, 1992. As a result, the State submitted such a revision, and the EPA approved an oxygenated gasoline program for the Missoula area on November 8, 1994 (59 FR 55585). The oxygenated gasoline program applies during the high CO season, which is generally during the colder winter months when cars tend to have higher tailpipe CO emissions. The oxygenated gasoline program also requires that gasoline contain at least 2.7% oxygen by weight during the high CO season. This requirement is intended to ensure complete gasoline combustion and thus achieve a reduction in tailpipe CO emissions. The high CO season for the Missoula CO area was established as November 1 through the last day of February of each year.

The CAA established an attainment date of December 31, 1995, for all Moderate CO areas, including the Missoula, Montana, area, triggering CAA section 211(m) requirements. CAA section 107(d)(3)(E) sets out the requirements that an area must meet to be redesignated from nonattainment to attainment, including that the area must have a fully approved maintenance plan pursuant to section 175A of the CAA. A maintenance plan, as defined in section 175A(a) of the CAA, is a revision to the SIP to provide for the maintenance of the NAAQS for the air pollutant in question in the area concerned for at least 10 years after the redesignation. CAA section 175A(d) requires that such plans include contingency provisions, as necessary, to promptly correct any violation of the NAAQS that occurs after redesignation of an area; this includes implementation of all control measures that were contained in the SIP prior to redesignation. While CAA section 175A sets forth the criteria for adequate maintenance plans, ⁽³⁾ the EPA has also published longstanding guidance providing clarification for states on developing maintenance plans by performing air quality modeling to demonstrate that the future mix of sources and emission rates will not cause a violation of the NAAQS or by showing that projected future emission reductions of a pollutant and its precursors will not exceed the level of emissions during a year when the area was in attainment of the NAAQS. ⁽⁴⁾

On May 27, 2005, the Governor of Montana submitted to the EPA a request to redesignate the Missoula CO nonattainment area to attainment for the 8-hour CO NAAQS. Along with this request, the Governor submitted a CAA section 175A(a) maintenance plan which established an attainment year of 2000, and demonstrated that the area would maintain the 8-hour CO NAAQS through 2020. The EPA approved the State's redesignation request, CAA section 175A(a) maintenance plan, and base year emissions inventory on August 17, 2007 (72 FR 46158).

Eight years after an area is redesignated to attainment, CAA section 175A(b) requires the state to submit a subsequent maintenance plan to the EPA, covering a second 10-year period. This second 10-year maintenance plan must demonstrate continued maintenance of the applicable NAAQS during this second 10-year period. The EPA explained in the October 6, 1995 Limited Maintenance Plan Option for Nonclassifiable CO Nonattainment Areas guidance memo that nonattainment and maintenance areas could meet CAA section 175A requirements to demonstrate continued maintenance by showing that an area has a design value of less than 85 percent of the 8-hour CO standard (7.65 ppm) based on the two most recent years of data for all CO monitors in the maintenance area. ⁽⁵⁾ This streamlined demonstration of maintenance is known as a limited maintenance plan. To fulfill this CAA requirement, the Governor of Montana submitted the second 10-year CO maintenance plan to the EPA on September 19, 2016. In this submission, the State utilized the EPA's option of using an LMP to demonstrate continued attainment and maintenance of the NAAQS, which was available because the area could demonstrate design values at or below 7.65 ppm (85% of exceedance levels of the 8-hour CO NAAQS) for eight consecutive quarters. ⁽⁶⁾ The EPA approved the second 10-year Montana CO LMP on February 1, 2018 (83 FR 4597). ⁽⁷⁾ The second 10-year CO LMP included the continued use of the oxygenated gasoline program for the Missoula area as a control measure.

2. CAA Requirements for the Removal of the Oxygenated Gasoline Program as a Control Measure in Missoula, Montana

As noted above, the oxyfuels program is included as a control measure in the State's second 10-year CO LMP for the Missoula area pursuant to the requirements of CAA section 175A(d). Montana's January 30, 2024, SIP revision seeks to change the status of Missoula's oxygenated gasoline program from a control measure to a contingency measure in the Montana SIP.

Under CAA section 211(m)(6) once a nonattainment area subsequently attains the CO NAAQS, oxygenated gasoline requirements may be removed as a control measure, as long as it is: (1) demonstrated that it is not needed for maintaining the health-based CO NAAQS in that area and (2) it is retained as a contingency measure. As relevant here, CAA section 211(m)(6) provides: "Nothing in this subsection shall be interpreted as requiring an oxygenated gasoline program in an area which is in attainment for carbon monoxide." Thus, the Agency determines that a CO nonattainment area is attaining the CO NAAQS, the State would be allowed to submit a SIP revision to remove the oxygenated gasoline program as a control measure so long as the area continues to maintain the CO NAAQS. However, the control measure must be retained as a contingency measure because it is contained in the SIP for the area before redesignation of the area as an attainment area. ⁽⁸⁾

CAA section 110(l) requires that a revision to the SIP not interfere with any applicable requirement concerning attainment and Reasonable Further Progress (RFP) (as defined in CAA section 171), or any other applicable requirement of the Act. The EPA's criterion for determining the approvability of Montana's January 30, 2024, SIP revision is whether the non-interference demonstration associated with the removal of the oxyfuels program for the Missoula area satisfies CAA section 110(l).

The EPA evaluates each CAA section 110(l) non-interference demonstration on a case-by-case basis considering the circumstances of each SIP revision. The degree of analysis focused on any NAAQS in a non-interference demonstration varies depending on the nature of the emissions associated with the proposed SIP revision. Regarding the SIP revision at issue, the primary focus of the 110(l) demonstration is the potential increase in CO emissions that could result from the change in status of the oxyfuels program in the Missoula CO LMP area from control measure to contingency measure. The oxyfuels program only applied in the area during its high CO season, November 1 through the last day of February of each year. Effects on vehicle emissions of other criteria pollutants or their precursors caused by implementation of an oxyfuels program are considerably less significant and thus the EPA's approval of the SIP revision would not be expected to result in interference for the purposes of a 110(l) demonstration. The EPA's analysis of Montana's January 30, 2024 SIP revision pursuant to CAA section 110(l) is provided below.

3. EPA's Analysis of Missoula, Montana's, Noninterference Demonstration

The EPA analyzed emissions information to determine whether changing the oxyfuels program in the Missoula CO LMP area from a control measure to a contingency measure would interfere with the attainment of the NAAQS. An emissions-based analysis is appropriate in these circumstances because the proposed revision, the removal of the Missoula oxyfuels program, effects only carbon monoxide emissions and leaves other air quality variables unchanged. ⁽⁹⁾ As a result, the EPA is able to conduct a focused assessment of the specific relationship between the limited revision to the SIP and NAAQS attainment.

To determine whether removal of the Missoula oxyfuels program would interfere with Missoula's maintenance of the CO NAAQS, the EPA reviewed whether removal of the oxyfuels program would lead to significant increases in onroad vehicle CO emissions over the 2010 vehicle emissions associated with the lowest CO ambient air design value documented in the approved Missoula LMP. Missoula ceased ambient CO monitoring in the maintenance area on March 31, 2011, due to low concentrations of CO (82 FR 43180). The latest complete design value for CO in Missoula between 2003-2011 was 2.2 ppm, significantly below the NAAQS of 9 ppm. The 2.2 ppm design value is also significantly below the 7.65 ppm threshold for eligibility for a CO limited maintenance plan.

The EPA evaluated CO emissions estimates from onroad mobile sources, the primary source of CO in the Missoula area, using estimates drawn from two different models. The estimated 2010 winter weekday onroad mobile source CO emissions using the MOVES3 model is 23.55 tons per day and the estimated 2010 winter weekday onroad mobile source CO emissions using the older MOVES2014 model is 30.21 tons per day. The emission estimates provided by the State of Montana in its 2016 LMP request, as approved by the EPA, and as found in Missoula's supporting documentation for the 110(l) demonstration are included in the docket for this proposed action. Emission estimates created by the EPA with the newer MOVES3 model, using data provided by Missoula and the State of Montana, are also provided in the docket for this action.

The difference in modeled emissions between the MOVES2014 and MOVES3 analyses of the 2010 emissions inventory input data is notable for reasons described in our Technical Support Document (TSD) for this action. The lower MOVES3 estimate of 2010 mobile source CO emissions is believed to be attributable to improvements in the accuracy of the model's vehicle activity assumptions and emission rates with each subsequent model release version. Since SIP revisions are required to be based on the latest modeling assumptions available at the time of the revision, we will hereinafter only rely on the MOVES3 estimates of 2010 onroad mobile source CO emissions in our analysis of Missoula's non-interference demonstration. MOVES3 was the latest model version available at the time Missoula was drafting the final 110(l) demonstration associated with this proposed action.

Missoula also provided winter weekday onroad mobile source MOVES3 CO emissions estimates for the years 2019, 2030 and 2040. Emission estimates for these years, with and without the oxyfuels program in place, are provided in the TSD for this action, with the 2010 emissions estimate provided for reference and comparison.

The monitored ambient level of CO in the attainment area in 2010 (the last time period with ambient air monitoring data available) was well below the CO NAAQS and modeled CO emissions are projected to be trending downward during the 2019 to 2040 time period even without an active oxyfuels program. The EPA finds that the removal of the program will cause only a transitory, insignificant increase in CO emissions and that removal of the program will not impact the area's ability to maintain the NAAQS.

Additionally, it does not appear likely that the ambient air concentration of CO in the Missoula LMP could exceed the 85% of the NAAQS qualification threshold for an LMP area. The 2010 emissions inventory available in the second ten-year LMP identified on-road mobile source CO emissions as 71% of all designated area emissions of CO. The EPA's revision of estimated 2010 emissions using MOVES3 lowers the mobile source contribution to total CO emissions to around 65%. In both cases, onroad mobile sources can be considered the major driver of ambient air CO concentrations observed in 2010. However, even in a conservative, hypothetical case where onroad mobile sources generate 100% of the CO emissions and all contributions to the last observed CO concentration value, the small increase in CO emissions resulting from the removal of the oxyfuels program is not projected to endanger maintenance of the NAAQS. The EPA review of the most recently certified 2021-2022 CO design values throughout the 50 states shows a maximum valid design value of 4.2 ppm. ⁽¹⁰⁾ This is reflective of a significant downward trend in CO values throughout the country in recent decades as more stringent vehicle standards and new emission control technologies have greatly decreased the levels of CO. ⁽¹¹⁾ Highway vehicle emissions of CO have decreased by over 40% nationwide over the last decade while there has been a national increase in vehicle miles travelled of nearly 8% over the same period. ^(12 13)

Based on this information and analysis, the EPA concludes that removal of the oxygenated fuels program from a control measure to a contingency measure in the Missoula, MT, CO LMP will not interfere with the NAAQS. Thus, the EPA proposes to approve the conversion of the oxygenated gasoline program from a control measure to a contingency measure in the Missoula, MT, CO LMP.

B. Rules Submitted for Revision

Montana's January 30, 2024, SIP submission includes proposed rule revisions in the MCCAPC program, in Chapter 10: Fuels, Subchapter 1: Oxygenated Fuels Program, specifically:

Rule 10.102(1): Revised to correct a clerical error.

Rule 10.105(1): Revised to correct a spelling error.

Rule 10.109(1): Revised to remove the requirement to annually sample 20% of all regulated gasoline storage tanks and gasoline blending facilities for the oxyfuel program.

Rule 10.110: Added to specify that the oxygenated fuels program ceases when authorization to end the program is received by the county.

Rule 10.111: Revision to renumber the rule.

Rule 10.111(2): Added to update the federally required contingency measures.

The EPA is proposing to act on the revisions listed in this action and will act on the additional rule revisions listed in the January 30, 2024, SIP revision submission in a separate action.

III. Environmental Justice Considerations

This is a proposed action to change the status of the oxyfuels requirement in the Missoula CO LMP from an active control measure to a contingency measure. Information on CO and its relationship to negative health impacts can be found at 36 FR 8186, April 30, 1971. We expect that this action will have neutral environmental and health impacts on all populations in Missoula, Montana, including people of color and low-income populations. At a minimum, this action would not worsen existing air quality and is expected to ensure the area is meeting requirements to attain and/or maintain NAAQS. Further, there is no information in the record indicating that this action is expected to have disproportionately high or adverse human health or environmental effects on a particular group of people.

IV. Proposed Action

For the reasons explained above, the EPA is proposing to approve Montana's January 30, 2024 SIP revisions seeking to revise various air quality rules and to remove the oxygenated gasoline program from Montana's SIP. The EPA has the authority to approve removal of a state's oxygenated gasoline program as specified in CAA section 211(m)(6) and has determined that the criteria of CAA section 211(m)(6) have been satisfied. The EPA is proposing to agree with Montana's technical demonstration that removal of the program from the SIP will not interfere with continued attainment or maintenance of any applicable NAAQS or with any other applicable requirement of the CAA, and that the requirements of CAA section 110(l) have been satisfied. Specifically, the EPA is proposing to revise the MCCAPC oxyfuels program rules, Chapter 10: Fuels, Subchapter 1: Oxygenated Fuels Program, rules 10.102(1), 10.105(1), 10.109(1), 10.110, 10.111, 10.111(2) as submitted in the Montana January 30, 2024, submission.

V. Incorporation by Reference

In this document, the EPA is proposing to include regulatory text in an EPA final rule that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by reference the MCCAPC oxyfuels program rules, Chapter 10: Fuels, Subchapter 1: Oxygenated Fuels Program, rules 10.102(1), 10.105(1), 10.109(1), 10.110, 10.111, 10.111(2) described in sections II. and IV. of this preamble. The EPA has made, and will continue to make, these materials generally available through https://www.regulations.gov and at the EPA Region 8 Office (please contact the person identified in the FOR FURTHER INFORMATION CONTACT section of this preamble for more information).

VI. 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. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, this action merely proposes to approve state law as meeting Federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this action:

• Is not a "significant regulatory action" 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).

• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq. );

• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq. ).

• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• Does not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not an economically significant regulatory action based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);

• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001);

• Is not subject to requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA; and

In addition, 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 proposed rule does not have Tribal implications and will not impose substantial direct costs on Tribal governments or preempt Tribal law as specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

Executive Order 12898 (Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations, 59 FR 7629, Feb. 16, 1994) directs Federal agencies to identify and address "disproportionately high and adverse human health or environmental effects" of their actions on minority populations and low-income populations to the greatest extent practicable and permitted by law. EPA defines environmental justice (EJ) as "the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies." EPA further defines the term fair treatment to mean that "no group of people should bear a disproportionate burden of environmental harms and risks, including those resulting from the negative environmental consequences of industrial, governmental, and commercial operations or programs and policies." The Montana Department of Environmental Quality (MDEQ) did not evaluate EJ considerations as part of its SIP submittal; the CAA and applicable implementing regulations neither prohibit nor require such an evaluation. EPA did not perform an EJ analysis and did not consider EJ in this action. Due to the nature of the action being taken here, this action is expected to have neutral impacts on the air quality of the affected area. Consideration of EJ is not required as part of this action, and there is no information in the record inconsistent with the stated goal of E.O. 12898 of achieving EJ for people of color, low-income populations, and Indigenous peoples.

[FR Doc. 2024-23589 Filed 10-11-24; 8:45 am]

BILLING CODE 6560-50-P

⁽¹⁾ See MEMO_Missoula MOVES TSD_CO OxyFuels 110(l).docx in docket.

⁽²⁾  Further information regarding this classification and the accompanying requirements are described in the "General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990." See 57 FR 13498, April 16, 1992.

⁽³⁾ See 42 U.S.C. 7505A(a).

⁽⁴⁾ See Memorandum from John Calcagni, Director, Air Quality Management Division, EPA Office of Air Quality Planning and Standards, "Procedures for Processing requests to Redesignate Areas to Attainment," September 4, 1992 (Calcagni Memo).

⁽⁵⁾  Memorandum from Joseph Paisie, Group Leader, EPA Integrated Policy and Strategies Group, to Air Branch Chiefs, October 6, 1995.

⁽⁶⁾ Id.

⁽⁷⁾ See September 14, 2017 direct final rule (DFR) and proposal (82 FR 43180, 82 FR 43208) for additional detail on the second, 10-year CO LMP for Missoula, Montana, area.

⁽⁸⁾  See CAA section 175A(d).

⁽⁹⁾ See Ctr. for Biological Diversity v. United States EPA, 75 F.4th 174, 180-181 (3rd Cir. 2024).

⁽¹⁰⁾ See https://www.epa.gov/air-trends/air-quality-design-values.

⁽¹¹⁾  See https://www.epa.gov/air-trends/carbon-monoxide-trends.

⁽¹²⁾  U.S. Environmental Protection Agency, Air Emissions Inventories, Air Pollutant Emissions Trends Data, National Tier 1 CAPS Trends, available at https://www.epa.gov/air-emissions-inventories/air-pollutant-emissions-trends-data as of Sept. 20, 2023.

⁽¹³⁾  U.S. Department of Transportation, Federal Highway Administration, Highway Statistics (Washington, DC: Annual Issues), table VM-202, available at https://www.fhwa.dot.gov/policyinformation/statistics.cfm as of Aug. 4, 2023.