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EPA Proposes Oregon PM2.5 Redesignation to Attainment

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Published March 4th, 2026
Detected March 4th, 2026
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Summary

The Environmental Protection Agency (EPA) has proposed the redesignation of Klamath Falls, Oregon, from nonattainment to attainment for particulate matter (PM2.5). This proposed rule includes a maintenance plan for the area. The public comment period for this proposal closes on April 3, 2026.

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What changed

The Environmental Protection Agency (EPA) has published a proposed rule to redesignate the Klamath Falls, Oregon, area to attainment for the 24-hour national ambient air quality standard for fine particulate matter (PM2.5). This action is based on air quality monitoring data demonstrating that the area has attained the standard and will continue to do so. The proposal also includes an associated maintenance plan.

Regulated entities and interested parties have a comment period that ends on April 3, 2026. Following the comment period, the EPA will review submissions before finalizing the redesignation. While this is a proposed rule and not yet binding, it signals a shift in the regulatory status of PM2.5 attainment in Klamath Falls, which may impact future air quality management strategies and permitting requirements.

What to do next

  1. Review the proposed rule for potential impacts on air quality management and permitting.
  2. Submit public comments by April 3, 2026, if applicable.

Source document (simplified)

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Proposed Rule

You may be interested in this older document that published on 08/21/2025 with action 'Determination of adequacy.' View Document

Air Plan Approval; OR; Klamath Falls PM2.5 Redesignation to Attainment and Maintenance Plan

A Proposed Rule by the Environmental Protection Agency on 03/04/2026

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  3. Document Details Published Content - Document Details Agency Environmental Protection Agency Agency/Docket Numbers EPA-R10-OAR-2025-0052 FRL-12592-01-R10 CFR 40 CFR 52 40 CFR 81 Document Citation 91 FR 10545 Document Number 2026-04333 Document Type Proposed Rule Pages 10545-10556 (12 pages) Publication Date 03/04/2026 Published Content - Document Details

| EPA-R10-OAR-2025-0052
(2 Documents) | | | |
| --- | | | |
| Date | | Action | Title |
| | 2026-03-04 | Proposed rule. | Air Plan Approval; OR; Klamath Falls PM2.5 Redesignation to Attainment and Maintenance Plan |
| | 2025-08-21 | Determination of adequacy. | Adequacy Status of the Klamath Falls, Oregon Submitted 2006 24-Hour PM2.5 NAAQS Redesignation Request and Maintenance Plan Budgets for Transportation Conformity Purposes |

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  1. 40 CFR Parts 52 and 81
  2. EPA-R10-OAR-2025-0052; FRL-12592-01-R10 # AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) proposes to approve an August 20, 2024 request by the Oregon Department of Environmental Quality (Oregon) to revise the attainment plan for the Klamath Falls, Oregon, nonattainment area; redesignate the Klamath Falls nonattainment area to attainment for the 2006 24-hour fine particulate matter (PM 2.5) National Ambient Air Quality Standard (NAAQS); and approve into the Oregon state implementation plan (SIP) a maintenance plan for the area that demonstrates continued attainment through 2037. This proposed rulemaking includes approving the motor vehicle emission budget for the area and approving updated state rules and the Klamath County Clean Air Ordinance, to be incorporated by reference. EPA proposes these actions pursuant to the Clean Air Act (CAA or the Act).

DATES:

Comments must be received on or before April 3, 2026.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R10-OAR-2025-0052, at https://www.regulations.gov. Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. EPA may publish any comment received to its public docket. Do not electronically submit any information you consider to be Confidential Business Information (CBI) or other information the disclosure of which is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. EPA will generally not consider comments or comment contents located outside of the primary submission (i.e. on the web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit https://www.epa.gov/​dockets/​commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT:

Claudia Vaupel, EPA Region 10, 1200 Sixth Avenue, Suite 155, M/S 15-H13, Seattle WA, 98101; by telephone at (206) 553-6121, or by email at vaupel.claudia@epa.gov.

SUPPLEMENTARY INFORMATION:

Throughout this document whenever “we,” or “our” is used, it refers to EPA.

Table of Contents

I. Background

II. Revisions to the Klamath Falls Attainment Plan

III. Clean Air Act Requirements for Redesignation to Attainment

IV. EPA's Analysis of Oregon's Redesignation Submittal

A. Determination That the Area Has Attained the 2006 24-Hour PM 2.5 NAAQS

B. Applicable Requirements Under CAA Section 110 and Part D

  1. CAA Section 110 General SIP Requirements

  2. CAA Title I, Part D Requirements

  3. Fully Approved SIP Under CAA Section 110(k)

C. Improvement in Air Quality Due to Permanent and Enforceable Measures

D. Fully Approved Maintenance Plan

  1. Attainment Inventory

  2. Maintenance Demonstration

  3. Monitoring Network and Verification of Continued Attainment

  4. Contingency Plan

E. Transportation Conformity and Motor Vehicle Emissions Budgets

F. State Rule Changes To Reflect the Redesignation

V. Proposed Action

VI. Incorporation by Reference

VII. Statutory and Executive Order Reviews

I. Background

EPA sets the NAAQS for certain ambient air pollutants at levels required to protect human health and the environment. Particulate matter with an aerodynamic diameter less than or equal to 2.5 micrometers, or PM 2.5, is one of the air pollutants for which EPA has established health-based standards. On October 17, 2006 (71 FR 61144), EPA set the level of the primary 24-hour PM 2.5 NAAQS to 35 µg/m 3. On November 13, 2009 (74 FR 58688), EPA designated a portion of Klamath County, Oregon, as nonattainment for the 2006 24-hour PM 2.5 NAAQS, triggering Clean Air Act attainment planning requirements for the area. On June 2, 2014 (79 FR 31566), EPA classified the Klamath Falls area as a Moderate nonattainment area.

On December 12, 2012, Oregon submitted an attainment plan (Klamath Falls Attainment Plan) to EPA that focused primarily on reducing emissions from residential wood combustion during the winter heating season, which is when violations of the 2006 24-hour PM 2.5 typically NAAQS occurred. The Klamath Falls Attainment Plan demonstrated how the Klamath Falls 2006 24-hour PM 2.5 nonattainment area (Klamath Falls area) would attain the 2006 24-hour PM 2.5 NAAQS by the December 2014 attainment date. EPA approved the Klamath Falls Attainment Plan in two actions, on August 25, 2015, and June 6, 2016. [1 ] The June 6, 2016, action included EPA's finding that the Klamath Falls area had attained the 2006 24-hour PM 2.5 NAAQS by December 31, 2014, and finalized a Clean Data Determination (CDD) pursuant to 40 CFR 51.1015. The CDD suspended the requirements for the state to submit an attainment demonstration, associated Reasonably Available Control Measures, Reasonable Further Progress, contingency measures, and any other SIP planning requirements related to the attainment of the 2006 PM 2.5 NAAQS, so long as the area continues to meet the standard. [2 ]

On August 20, 2024, Oregon submitted revisions to the Klamath Falls Attainment Plan as well as a request to EPA to redesignate the Klamath Falls area to attainment for the 2006 24-hour PM 2.5 NAAQS and to approve into the Oregon SIP a maintenance plan for the area that demonstrates continued attainment through 2037. Oregon clarified its submissions in two letters dated April 4, 2025, and December 9, 2025.

II. Revisions to the Klamath Falls Attainment Plan

Oregon's submission includes revisions to the Klamath Falls Attainment Plan to incorporate updates to the Klamath County Clean Air Ordinance (Ordinance No. 63-06).

EPA approved Ordinance No. 63-06 (adopted on December 31, 2012) into Oregon's SIP August 25, 2015. [3 ] The ordinance includes several control measures that EPA determined meet CAA moderate area control strategy requirements, particularly for the solid fuel burning area source category. On June 25, 2024, Klamath County adopted updates to the SIP-approved Klamath County Clean Air ordinance in the form of Ordinance No. 63-07. Oregon submitted Klamath County Ordinance No. 63-07 to EPA for approval into Oregon's SIP. The following is EPA's discussion and analysis of revisions to ( printed page 10546) the Klamath County Clean Air Ordinance.

406.001 Policy and Purpose and 406.450 Severability

Summary of SIP Revision

Klamath County made minor changes to the policy and purpose provision, 406.001, and the severability provision, 406.450. These include wording changes such as replacing “problems” with “issues,” “address” with “assess,” “clean” with “cleaner,” “jurisdiction” with “jurisdictions.”

EPA's Evaluation

EPA is proposing to approve these minor revisions.

406.005 Definitions

Summary of SIP Submission

Klamath County made several non-substantive changes to the definitions in the Clean Air Ordinance. For example, the County capitalized certain words that were originally lower case. In other instances, the County made minor word choice changes (e.g., replacing “die down” with “completely extinguish,” and “violator” with “individual or entity in violation”). Klamath County removed unused definitions, e.g., “urban growth boundary.” The County consolidated the definition of “pellet stove” into the definition of “wood burning device.”

Likewise, Klamath County consolidated certain definitions associated with outdoor burning into a central definition of “open/outdoor burning.” This central definition includes agricultural waste, commercial waste, construction waste, demolition waste, domestic waste, forest slash waste, and industrial waste, and waste from agricultural operations. This new term applies to all open or outdoor fires intended for the combustion of yard debris and cites the definition of “open burning” in OAR 340-264-0030(25)(c), a SIP-approved rule. In line with the removal of waste categories, Klamath County revised the definition of yard debris by removing criteria that distinguish between domestic and commercial waste and changing “waste” in the definition of “open/outdoor burning” to “yard debris.” The County also revised the definition of “open/outdoor burning” to remove “open or outdoor fires intended for heating.”

The County removed the definition of “person” and changed the definition of “responsible person” to “responsible party,” which is consistent with the updated outdoor burning requirements in section 406.100(3)(K). The County also replaced the term “Air Quality Inspector” with “Air Quality Specialist” and added language clarifying the Air Quality Specialist's role to develop forecasts and respond to violations, and to educate the public about the ordinance and violations.

The County also revised the definition of the Klamath County Advisory Committee from being appointed by the Klamath County Board of Commissioners to being selected by the Klamath County Public Health department. The revised ordinance clarifies that a role of the committee is to provide community input on program implementation and removes the duty of the committee to identify significant emissions sources. Klamath County also removed the legal description of air quality zone (AQZ); however, the ordinance already contains a map of the AQZ.

The County added new definitions for “Air quality outlook” and “Air Quality Index (AQI)” which are used to provide air quality information to the public based on the Oregon AQI. The purpose of the air quality outlooks is to inform the public of air quality when conditions are at or above levels that are unhealthy for sensitive groups (AQI of 101).

In addition, Klamath County replaced outdated specifications in the definition of “woodstove/woodheater” and “American Society for Testing and Materials (ASTM) Standards” with references to “current EPA emissions standards,” which are incorporated into the definition of “certified woodburning device.”

The County replaced the definitions of “solid fuel fired appliance” and “woodstove/woodheater” with “wood burning device.” Accordingly, the County replaced the definition of “exempt solid-fuel fired appliance” with “exempt wood burning device” and removed the definition of “woodstove/woodheater.” In the definition of “certificate of exemption,” the County removed language that provided for exempting open or outdoor burning from burning curtailments. The County also removed the definition of “particulate matter ten microns and less (PM 10)” and removed PM 10 wood burning curtailment advisories.

Klamath County also made several changes to certain definitions associated with the issuance of burn bans. The County issues burn notifications under section 406.150 of the Ordinance. Klamath formerly used a color-code to issue burn notifications (red, yellow, green). In section 406.005, the County defined each color based on the projected PM 2.5 level. Klamath County replaced the former definition of each color with burn notifications phrases (“burning allowed,” “exempt wood burning devices only,” and “no burning allowed”).

The County defined the “burning allowed” notice as when the air quality forecast projects that PM 2.5 levels will be below 22 micrograms per cubic meter (µg/m 3) for a 24-hour average. Under this notice there is no burn ban. “Exempt wood burning devices only” is defined as when the forecast projects that PM 2.5 levels have the potential to exceed 22 µg/m 3 for a 24-hour average. Under this notice, the County will allow burning in only devices for which the County has issued a certificate of exemption under section 406.200. “No burning allowed” is defined as when the forecast indicates that PM 2.5 levels have the potential to exceed 35 µg/m 3 for a 24-hour average. Under this notice, no burning is allowed in any devices.

Klamath County revised the definition of “low income” from the Housing and Urban Development definition of “very low income” to using 250 percent of the Federal poverty level. Under 406.200, the County issues certificates of exemption to only “low income” individuals for the purposes of the “exempt wood burning devices only” notification.

Section 406.005 includes a definition of “certificate of variance,” which is a term used throughout the ordinance. However, Oregon did not include 406.250 Certificate of Variance in its submittal. Therefore, the variance authority referenced in the definitions and other portions of the ordinance is not proposed for approval into the Klamath Falls Attainment Plan.

EPA's Evaluation

EPA has evaluated the changes to section 406.005 and proposes to approve them for the following reasons. Many of the revisions are minor editorial corrections that do not change the substance of the associated definitions or regulatory provisions. The revisions including the replacement of person with responsible party, revision to the definition of air quality zone, and the change to “open/outdoor burning”, clarify the rules and make the rules easier to implement.

The revisions to air advisory committee and air quality outlook do not change the substance or stringency of the control measures in the Ordinance. The replacement of outdated woodstove/woodheater specifications improves the stringency of the Ordinance. Similarly, the consolidation of multiple definitions into “wood burning device” simplifies the ( printed page 10547) Ordinance and will improve implementation. The County's removal of the exemption for open and outdoor burning from burning curtailments in the definition of “certificate of exemption” improves the stringency of the Ordinance.

In addition, the County's removal of definitions of PM 10 is appropriate for the Klamath Falls area because EPA previously approved removing the PM 10 monitor from the area and approved an approach using the Klamath Falls PM 2.5 monitoring data as a surrogate for measuring PM 10. Moreover, the revised PM 2.5 curtailment trigger (when the 24-hour average PM 2.5 concentrations have the potential to exceed or are exceeding an estimate of 35 µg/m 3) is more protective than the former PM 10 curtailment trigger (when PM 10 concentrations have the potential to exceed or are exceeding an estimate of 150 ug/m 3).

With respect to the revisions to the burn curtailment advisory definitions, the replacement of the color code with natural language advisories will provide for equivalent emissions reductions. Notably, the new natural language advisories do not exactly parallel the former color code but will simplify implementation. We note that the new “Exempt Wood Burning Device” category significantly limits the categories of exempt devices than the former red and yellow advisories. This will lead to significant emissions reductions well before the area is forecasted to experience PM 2.5 levels at the NAAQS. Likewise, the “No Burn Period” advisory limits burning to only individuals with a wood stove as a sole source of heat. Although the “No Burn Period” is called when levels are projected to exceed 35 µg/m 3 as opposed to 30 µg/m 3 in the former regulation, the broader applicability will compensate in terms of greater emission reductions.

Likewise, the revision to the definition of “low income” is appropriate. We acknowledge that this revision may allow more people to qualify for exemptions during a burning curtailment. As of 2025, the very low-income limit for a four-person household in Klamath County was $40,700. [4 ] According to the U.S. Department of Health and Human Services, 250 percent of the Federal poverty level for a four-person household is $80,375. [5 ] Thus, this revision broadens the scope of individuals eligible to obtain a certificate of exemption. However, other changes to the definitions strengthen the Ordinance. Notably, pellet stoves, fireplaces, cook stoves, masonry heaters, and open burning are no longer exempt from burn bans. We also acknowledge that adjusting the income limits is necessary to ensure the measure is feasible to implement. [6 ] Individuals making 250 percent of the Federal poverty level likely cannot afford alternative sources of heat. Between 40 and 49 percent of Klamath County residents earning 200 percent or below the Federal poverty level experience high or severe energy burden. [7 ] The U.S. Department of Energy classifies a household spending 6 percent or more of its income on home energy costs as experiencing high energy burden. [8 ] The per capita energy expenditures in Oregon in 2022 was $4,594, which is a 61percent increase since 2020. [9 ] At this expenditure level, households making 250 percent of the Federal poverty level would experience high energy burden.

406.100 County Wide Air Quality Pollution Control Requirements

Summary of SIP Submission

Klamath County revised section 406.100 to incorporate the updated definitions discussed previously. The County clarified the open burning hours in two primary ways. First, the county replaced “sunrise” and “sunset” with times of day, “8 a.m.” and “5 p.m.,” respectively. Second, under the current rule, burning conducted for “forest slash fires” or “ecosystem management” are not required to be extinguished by sunset. The County revised the rule to exempt Federal, State, and local agency managed open burning (e.g., forest fuel reduction, fire training, and ecosystem management) from the requirement to extinguish the fire by sunset. In addition, the revised Ordinance expands and clarifies the burn notification period from “during the winter heating season” to “from October 15 through March 15.” The County added a requirement that newly retrofitted fireplaces must comply with fireplace ASTM standards. The County also added a provision allowing certain types of fires: “outdoor fires used for cooking, personal warmth, lighting, ceremonial, or aesthetic purposes, and are not associated with waste disposal” but provided that such fires must be contained within a fireproof container designed for outdoor burning, be capable of containing the fire and coals above the ground surface, and may not exceed two feet in diameter and two feet in height.

EPA Evaluation

EPA reviewed the revisions to section 406.100 and proposes to approve them for the following reasons. Several revisions improve the clarity and enforceability of the section. Notably, the changes to the burn ban season and time periods make the section easier to follow and enforce. The addition of the requirement that newly installed fireplaces meet ASTM standards strengthens the Ordinance. Also, the former open burn hours exemption for slash fires and ecosystem management was ambiguous. Klamath County's revisions clarify and narrow the exemption's scope. Finally, we acknowledge that the addition of the exemption for certain small fires makes the rule less stringent. However, we do not anticipate that this narrow exemption will interfere with attainment of the NAAQS because the exemption is limited to very small fires for certain limited purposes.

406.150 Air Quality Pollution Requirements Applying Within the AQZ

Summary of SIP Submission

Klamath County revised section 406.150 to incorporate the updated definitions discussed previously and to remove the 3-minute per hour exemption from the 20 percent opacity limit and the exemption for pellet stoves, antique stoves, masonry fireplaces, and cookstoves, during wood burning curtailments. Other revisions to the Ordinance include removing the requirement that three weekends be included in the open/outdoor burning window and removing the option to extend the open burn window by the number of days that burning was prohibited. The requirement to consult with the City of Klamath Falls Code ( printed page 10548) Compliance Officer before an open burn window is declared was also removed. The County added a provision to prohibit structures that can impede the view of material being burned outdoors. [10 ]

EPA's Evaluation

We discussed the reasons for proposing to approve the updated burn ban requirements under section 406.005. In addition, we are proposing to approve revisions to section 406.150 because these revisions strengthen the Ordinance. The County removed exemptions on certain devices and removed the opacity limit exemption for 3 minutes each hour. These changes increase the stringency of the Ordinance.

406.200 Certificate of Exemption

Summary of SIP Submission

Klamath County revised section 406.200 to incorporate the updated definitions discussed previously. Klamath County also revised the section to clarify that the certificate of exemption is for low-income households or those with wood heating as a sole source of heat.

EPA Evaluation

For the reasons discussed under section 406.005, EPA is proposing to approve these revisions.

406.500 Air Quality Advisory Committee

Summary of SIP Submission

Klamath County's revisions to section 406.500 changed the board composition from persons “representing industry” and the “general public” to “community members.” Outdated contingency measures that might have been triggered in 2014 and 2015 and are no longer relevant.

EPA Evaluation

EPA is proposing to approve these revisions.

III. Clean Air Act Requirements for Redesignation to Attainment

The CAA provides the requirements for redesignating a nonattainment area to attainment. Specifically, CAA section 107(d)(3)(E), allows for redesignation provided that: (1) EPA determines that the area has attained the applicable NAAQS; (2) EPA has fully approved the applicable implementation plan for the area under CAA section 110(k); (3) EPA determines that the improvement in air quality is due to permanent and enforceable reductions in emissions resulting from implementation of the applicable SIP and applicable Federal air pollutant control regulations and other permanent and enforceable reductions; (4) EPA has fully approved a maintenance plan for the area as meeting the requirements of CAA section 175A; and (5) the State has met all requirements applicable to the area under CAA section 110 and part D. In this proposed rulemaking, EPA will review CAA section 107(d)(3)(E) requirements (2) and (5) together as part of our evaluation of Oregon's redesignation request.

EPA has provided guidance on redesignations in the “General Preamble,” [11 ] and has provided further guidance on processing redesignation requests in the following documents: (1) “Procedures for Processing Requests to Redesignate Areas to Attainment,” Memorandum from John Calcagni, Director, Air Quality Management Division, September 4, 1992 (Calcagni Memo); (2) “State Implementation Plan (SIP) Actions Submitted in Response to Clean Air Act (CAA) Deadlines,” Memorandum from John Calcagni, Director, Air Quality Management Division, October 28, 1992; and (3) “Part D New Source Review (part D NSR) Requirements for Areas Requesting Redesignation to Attainment,” Memorandum from Mary D. Nichols, Assistant Administrator for Air and Radiation, October 14, 1994. These documents are included in the docket for this proposed rulemaking.

IV. EPA's Analysis of Oregon's Redesignation Submittal

EPA is proposing to redesignate the Klamath Falls area to attainment for the 2006 24-hour PM 2.5 NAAQS and to approve a maintenance plan for the area (the Klamath Falls Maintenance Plan) that demonstrates the area will remain in attainment of the 2006 24-hour PM 2.5 NAAQS for 10 years after redesignation. EPA's proposed approval of the redesignation request and maintenance plan is based upon EPA's determination that the area continues to attain the 2006 24-hour PM 2.5 NAAQS and that all other redesignation criteria have been met for the area. The following is a description of how Oregon's August 20, 2024, submission and the April 4, 2025, and December 9, 2025, clarification letters, available in the docket for this rulemaking, satisfy the requirements of CAA section 107(d)(3)(E) for the 2006 24-hour PM 2.5 standard.

A. Determination That the Area Has Attained the 2006 24-Hour PM 2.5 NAAQS

To redesignate an area from nonattainment to attainment, the CAA requires EPA to determine that the area has attained the applicable NAAQS (CAA section 107(d)(3)(E)(i)). An area is attaining the 2006 24-hour PM 2.5 NAAQS, when the 3-year average 98th percentile mass concentrations produce a valid design value that is less than or equal to 35 µg/m [3 ], based on 3 complete, consecutive calendar years of quality-assured air quality monitoring data, as determined in accordance with 40 CFR 50.13 and 40 CFR part 50, appendix N. [12 ]

As previously noted, on June 6, 2016 (81 FR 36176), EPA determined that the Klamath Falls area had attained the 2006 24-hour PM 2.5 NAAQS of 34 µg/m 3 based on the 2012-2014 design value period. For this proposed rulemaking, EPA reviewed the recent PM 2.5 ambient air monitoring data in the Klamath Falls area for the 2022 through 2024 design value period. The Klamath Falls area continues to attain the 2006 24-hour PM 2.5 NAAQS with a 2022 through 2024 design value of 34 µg/m 3.

EPA's review of the monitoring data supports the previous determination and therefore EPA finds it is appropriate to conclude the area has continued to attain the 2006 24-hour PM 2.5 NAAQS, based on attaining design values at the Peterson School regulatory monitor (AQS ID 41-035-0004).

B. Applicable Requirements Under CAA Section 110 and Part D

CAA section 107(d)(3)(E)(ii) and (v) states that for an area to be redesignated to attainment, it must be determined that the Administrator has fully approved the applicable implementation plan for the area under CAA section 110(k) and all the requirements applicable to the area under CAA section 110 (general SIP requirements) and part D of title I (SIP requirements for nonattainment areas) must be met. We interpret this to mean that, for a redesignation request to be approved, the state must have met all requirements that applied to the subject area prior to, or at the time of, submitting a complete redesignation ( printed page 10549) request. EPA may rely on prior SIP approvals in approving a redesignation request as well as any additional measure it may approve in conjunction with a redesignation action. [13 ]

1. CAA Section 110 General SIP Requirements

CAA section 110(a)(2) of title I delineates the general requirements for a SIP, which include enforceable emissions limitations and other control measures, means or techniques, provisions for the establishment and operation of appropriate devices necessary to collect data on ambient air quality, and programs to enforce the limitations. The general SIP elements and requirements set forth in CAA section 110(a)(2) include, but are not limited to the following:

  • Submittal of a SIP that has been adopted by the state after reasonable public notice and hearing;
  • Provisions for establishment and operation of appropriate procedures needed to monitor ambient air quality;
  • Implementation of a minor source permit program;
  • Provisions for the implementation of part C requirements (referred to as prevention of significant deterioration or PSD);
  • Provisions for the implementation of CAA part D requirements for nonattainment new source review (referred to as part D NNSR, NNSR, nonattainment NSR, or NSR) permit programs;
  • Provisions for air pollution modeling; and
  • Provisions for public and local agency participation in planning and emission control rule development. [14 ] We note that SIPs must be fully approved only with respect to applicable requirements for purposes of redesignation in accordance with CAA section 107(d)(3)(E)(ii). Similarly, EPA believes that the other CAA section 110(a)(2) (and part D) requirements that are not connected with nonattainment plan submittals and not linked with an area's attainment status are not applicable requirements for purposes of redesignation. EPA considers the CAA section 110(a)(2) (and part D) requirements that relate to a particular nonattainment area's designation and classification as the relevant measures to evaluate in reviewing a redesignation request. This approach is consistent with EPA's existing policy on applicability of the conformity SIP requirement for redesignations. [15 ]

EPA has reviewed the relevant measures in the Oregon SIP and concludes that they meet the general SIP requirements under CAA section 110(a)(2). EPA has previously approved provisions of Oregon's SIP as demonstrating compliance with the CAA section 110(a)(2) requirements for the 2006 PM 2.5 NAAQS. [16 ] These requirements are, however, statewide requirements that are not linked to the PM 2.5 nonattainment status of the Klamath Falls area. In addition, there are no outstanding or disapproved applicable SIP submittals with respect to the Klamath Falls area that would prevent redesignation of the Klamath Falls area for the 2006 PM 2.5 NAAQS. Therefore, EPA concludes that Oregon has met all general SIP requirements for the Klamath Falls area for purposes of redesignating the area to attainment for the 2006 PM 2.5 NAAQS.

2. CAA Title I, Part D Requirements

As set forth in CAA part D of title I, the basic nonattainment plan requirements applicable to all nonattainment areas at subpart 1 (CAA sections 172 through 176) and requirements specific to PM 10 and PM 2.5 areas at subpart 4 (CAA section 189). On August 24, 2016 (81 FR 58010), EPA promulgated the Fine Particulate Matter National Ambient Air Quality Standards; State Implementation Plan Requirements rule which implements the CAA part D requirements for areas designated nonattainment for any PM 2.5 NAAQS. [17 ]

States containing Moderate PM 2.5 nonattainment areas were required to submit SIPs, by December 31, 2014, that demonstrated how the areas would attain the PM 2.5 NAAQS by December 31, 2015. [18 ] As discussed in section I of this document, EPA approved the Klamath Falls Attainment Plan, determined that the Klamath Falls area had attained the 2006 24-hour PM 2.5 NAAQS by the attainment date, and finalized a CDD pursuant to 40 CFR 51.1015. [19 ] In accordance with 40 CFR 51.1015, upon a CDD, the requirements for the state to meet certain nonattainment plan requirements under CAA section 172(c) shall be suspended until such time as: (1) the area is redesignated to attainment, after which such requirements are permanently discharged; or, (2) EPA determines that the area has re-violated the PM 2.5 NAAQS. This includes the requirements to submit an attainment demonstration, provisions demonstrating that reasonably available control measures (RACM), including reasonably available control technologies (RACT) for stationary sources, shall be implemented no later than 4 years following the date of designation of the area, reasonable further progress (RFP) plan, quantitative milestones (QM) and reports, and contingency measures for the area. However, determinations of attainment do not relieve states from submitting and EPA from approving certain other CAA part D planning requirements for the 2006 PM 2.5 NAAQS. CAA section 172(c)(3) requires submittal and approval of a comprehensive, accurate and current inventory of actual emissions. For purposes of the PM 2.5 NAAQS, this emissions inventory should address not only direct emissions of PM 2.5, but also emissions of all precursors to PM 2.5 formation, i.e., SO 2, NO X, VOC, and ammonia. EPA determined that Oregon met the CAA section 172(c)(3) comprehensive emissions inventory requirement for the Klamath Falls area on June 6, 2016. [20 ]

CAA section 172(c)(4) requires the identification and quantification of allowable emissions for major new or modified stationary sources in an area, and CAA section 172(c)(5) requires source permits for the construction and operation of new or modified major stationary sources anywhere in the nonattainment area. EPA most recently approved Oregon's NSR permit program as meeting these requirements on July 23, 2024 (89 FR 59610).

Once the Klamath Falls area is redesignated to attainment, sources located in the Klamath Falls area will be subject to Oregon's NSR regulations applicable to maintenance areas. Oregon's NSR and PSD regulations are codified in the Oregon Administrative Rules (OAR), chapter 340, divisions 200, 202, 209, 212, 216, 222, 224 (except 0510(3) inter-pollutant offset ratios), 225, and 268. EPA finds that Oregon's NSR and PSD provisions meet all ( printed page 10550) applicable Federal requirements for any area designated unclassifiable or attainment, and these provisions will become fully effective in the Klamath Falls area upon redesignation to attainment. EPA most recently approved revisions to division 224, Oregon's NSR program, on July 23, 2024 (89 FR 59610).

CAA section 172(c)(7) requires the SIP to meet the applicable provisions of CAA section 110(a)(2). As explained previously in section IV.B.1 of this document, we have proposed to find that the Oregon SIP meets the CAA section 110(a)(2) applicable requirements. For purposes of redesignation to attainment for the 2006 24-hour PM 2.5 NAAQS, EPA also proposes to find that Oregon has met all the applicable SIP requirements under CAA part D of title I in accordance with CAA section 107(d)(3)(E)(v).

3. Fully Approved SIP Under CAA Section 110(k)

CAA section 110(k) sets out provisions governing EPA's review of SIP submittals. For an area to qualify for redesignation, the SIP for the area must be fully approved under CAA section 110(k). As discussed in sections IV.B.1 and IV.B.2 of this document, for purposes of redesignation to attainment for the 2006 24-hour PM 2.5 NAAQS, EPA has fully approved all applicable requirements in the Klamath Falls Attainment Plan into the Oregon SIP in accordance with CAA section 110(k). Therefore, the criterion for redesignation, set forth at CAA section 107(d)(3)(E)(ii), is satisfied.

C. Improvement in Air Quality Due to Permanent and Enforceable Measures

CAA section 107(d)(3)(E)(iii) provides that for an area to be redesignated to attainment, the Administrator must determine that the improvement in air quality is due to permanent and enforceable reductions in emissions resulting from implementation of the applicable implementation plan, implementation of applicable Federal air pollutant control regulations, and other permanent and enforceable reductions. In making this demonstration for the Klamath Falls area, Oregon explained that residential wood heating was the major source of emissions contributing to violations of the 24-hour PM 2.5 NAAQS, which occur primarily during the winter season. The permanent and enforceable control measures included in the Klamath Falls Attainment Plan focused on reducing emissions from residential wood combustion, as well as other contributing sources including open burning, permitted industrial facilities, and mobile sources. The following paragraphs describe the permanent and enforceable local and state control measures that were adopted in the Klamath Falls Attainment Plan.

Oregon identified emissions from residential wood heating in the winter months as the major contributor to nonattainment in the Klamath Falls area. The Klamath Falls Attainment Plan implemented enforceable state and local strategies to reduce emissions from residential wood heating and EPA approved them into the Oregon SIP on June 6, 2016 (81 FR 36176), making them federally enforceable. In this rulemaking, EPA is proposing to approve revisions to the Klamath Falls Attainment Plan, as discussed in section II of this document. The strategies in the Klamath Falls Attainment Plan include curtailing wood heating on days when exceedances of the 2006 24-hour PM 2.5 NAAQS are most likely to occur, a woodstove change out program, prohibitions on resale and installation of non-certified [21 ] solid fuel heating devices, requirements to remove non-certified solid fuel heating devices at the time of home sale, and certain operational requirements for solid-fuel heating.

The mandatory curtailment program, under the Klamath Clean Air Ordinance, restricts combustion in residential wood burning devices when elevated PM 2.5 concentrations are forecast in the air quality zone. [22 ] Key elements of the curtailment program include daily burn notifications during the heating season, from October 15 through March 15. A “no burning allowed” notification is issued when 24-hour average PM 2.5 concentrations have the potential to exceed or are exceeding 35μg/m 3. During this time, operating any wood burning device is prohibited. An “exempt wood burning devices only” notification is issued when PM 2.5 24-hour average concentrations have the potential to exceed 22μg/m 3 but are not projected to exceed 35μg/m 3. During this time, only devices with an approved certificate of exemption may burn. A certificate of exemption may be issued by the Klamath County Public Health Administrator or designee to applicants who qualify as low income or whose sole source of heat is a wood burning device. A “burning allowed” notification is issued when 24-hour average PM 2.5 concentrations are forecast to not exceed 22μg/m 3. All wood burning devices may be used during this time.

To reduce the number of high-emitting wood burning devices that operate in the Klamath Falls area, Oregon implemented a woodstove changeout program, prohibited the sale and installation of non-certified devices, required the removal and destruction of all non-certified wood burning devices at the time of home sale (including residences, shops, garages, and outbuildings), and established new fireplace standards. The woodstove changeout program provided financial incentives for homeowners to replace non-certified woodstoves with newer, cleaner heating devices. Oregon stated that 180 woodstoves had been replaced in the changeout program, and 7 uncertified woodstoves had been removed upon home sale as of the date of its redesignation request and maintenance plan submission. Oregon projects that by 2028, 411 woodstoves will have been replaced. The removal of non-certified woodstoves and the prohibition on their sale and installation ensures the emissions reductions from changeouts and removal at time of home sale are permanent and enforceable.

The Klamath Falls Attainment Plan includes operational requirements for residential wood heating, specifically limits on opacity and restrictions on materials that can be burned. The Klamath Clean Air Ordinance prohibits operating a wood burning device in a manner that produces smoke with opacity greater than 20 percent, except during the first 10 minutes of operation. [23 ] The Ordinance also lists the types of fuel that can be used in a wood burning device as: only dry, seasoned cordwood, pressed sawdust logs, organic charcoal or pellets specifically manufactured for the appliance. Both the Klamath Clean Air Ordinance and the Oregon Heat Smart Program (OAR Division 262) list materials that are prohibited from being burned in a solid-fuel heating device. The combined list of prohibited materials include: garbage, treated wood, plastic or plastic products, rubber or rubber products, animal carcasses, products that contain asphalt, petroleum products, paint, chemicals, products containing lead, mercury or other heavy or toxic metals, materials containing asbestos, wire insulation, automobile parts, ( printed page 10551) particleboard, and animal or vegetable matter resulting from the handling, preparation, cooking or service of food that normally results in dense or noxious smoke when burned.

While emissions from residential wood heating in the winter months was identified as the major contributor to nonattainment in the Klamath Falls area, and therefore the Attainment Plan largely relies on implemented enforceable state and local strategies to reduce emissions from residential wood heating, other permanent and enforceable measures contained in the Klamath Falls Attainment plan include those for open burning, permitted industrial facilities, and industrial sources. The Klamath Clean Air Ordinance allows for open and outdoor burning during specific time periods, and within the Klamath Falls air quality zone during open burn periods declared by Klamath County Public Health. To address emissions from industrial facilities, the Klamath Falls Attainment Plan implemented rules requiring all permitted facilities emitting 10 or more tons per year of PM 2.5 to implement RACT. Specifically, the rules (OAR 340-240-0510 through OAR 340-240-0530) include opacity limits, fugitive emissions plans, and operations and maintenance best practices. Emissions reductions are expected to increase in future years as the motor vehicle fleet in Klamath Falls turns over. Further, the Klamath Falls Attainment Plan stated that efforts to reduce road dust emissions generated by motor vehicle traffic had been achieved through road paving, minimizing the use of sanding material, and controlling mud and dirt track out from industrial, construction and agricultural operations. The Interagency Agreement to Reduce Particulate Emissions from Winter Road Sanding between the Oregon Department of Transportation, the Klamath County Public Works Department, and the City of Klamath Falls Public Works Department was approved into the Oregon SIP.

Based on EPA's evaluation of the control measures, we propose to determine that the improvement in air quality is reasonably attributable to permanent and enforceable reductions in emissions resulting from implementation of the applicable state, local, and Federal air pollutant control regulations, and other permanent and enforceable emissions reductions.

D. Fully Approved Maintenance Plan

In conjunction with Oregon's request to redesignate the Klamath Falls area to attainment, Oregon submitted a plan to provide for maintenance of the 2006 24-hour PM 2.5 NAAQS through 2037 (Klamath Falls Maintenance Plan). EPA is proposing to approve the Klamath Falls Maintenance Plan, and if this proposed rulemaking is finalized, the Klamath Falls area will have an approved PM 2.5 maintenance plan.

CAA section 107(d)(3)(E)(iv) requires that, for a nonattainment area to be redesignated to attainment, EPA must fully approve a maintenance plan for the area as meeting the requirements of CAA section 175A. The maintenance plan must demonstrate continued attainment of the relevant NAAQS in the area for at least 10 years after redesignation. Eight years after redesignation, the state must submit a revised maintenance plan demonstrating attainment for an additional 10-year period. The maintenance plan must also contain a contingency plan to ensure prompt correction of any violation of the NAAQS that occurs after redesignation of the area. See CAA sections 175A(a), (b) and (d). The Calcagni Memo provides additional guidance on the content of a maintenance plan, stating that a maintenance plan should include the following elements: (1) an attainment emissions inventory; (2) a maintenance demonstration showing attainment for 10 years following redesignation; (3) a commitment to maintain and operate an appropriate air quality monitoring network; (4) verification of continued attainment; and (5) a contingency plan to prevent or correct future violations of the NAAQS. The following describes how each of the maintenance plan elements are addressed in the maintenance plan.

1. Attainment Inventory

As discussed in the CAA General Preamble (See 57 FR 13498, April 16, 1992) and the Calcagni Memo, PM 2.5 maintenance plans should include an attainment emission inventory to identify the level of emissions in the area which are sufficient to maintain the NAAQS. The attainment inventory should be consistent with EPA's emissions inventory requirements and most recent guidance on emission inventories for nonattainment areas available at the time and should represent emissions during the time period associated with the monitoring data showing attainment. [24 ] The inventory must be comprehensive, including emissions from stationary point sources, area sources, and mobile sources, and must be based on actual emissions during the appropriate season, if applicable.

The Klamath Falls Maintenance Plan includes an attainment inventory for the year 2017, which is associated with monitoring data showing attainment of the 2006 24-hour PM 2.5 NAAQS with a 2015-2017 design value of 32 µg/m [3 ]. [25 ] Therefore, the 2017 emissions inventory identifies the level of emissions in the Klamath Falls area that is sufficient to attain the 2006 24-hour PM 2.5 NAAQS. The 2017 emissions inventory includes annual emissions and typical season day emissions. Typical season day emissions represent emissions from November 1 through the end of February, which is when the 2006 24-hour PM 2.5 NAAQS has historically been exceeded in the Klamath Falls area. The attainment inventories shown in table 1 of this document, include emissions of PM 2.5, nitrogen oxides (NO X), sulfur dioxide (SO 2), ammonia (NH 3) and volatile organic compounds (VOC) for the four major source categories: events and natural sources, mobile sources, [26 ] nonpoint sources, and point sources.

| Pollutant emissions by emission category | Annual emissions
(tons per year) | Typical season day
(pounds per day) |
| --- | --- | --- |
| Direct PM 2.5: | | |
| Events and Natural Sources | 163.5 | 2,347 |
| Mobile Sources | 56.5 | 328 |
| ( printed page 10552) | | |
| Nonpoint Sources | 232.5 | 1,191 |
| Point Sources | 158.5 | 1,002 |
| Direct PM 2.5 Total | 611 | 4,868 |
| NH 3: | | |
| Events and Natural Sources | 32.2 | 462 |
| Mobile Sources | 13 | 69 |
| Nonpoint Sources | 97.6 | 337 |
| Point Sources | 111.7 | 537 |
| NH 3 Total | 254.5 | 1,406 |
| NO X: | | |
| Events and Natural Sources | 72.8 | 559 |
| Mobile Sources | 650.4 | 3,490 |
| Nonpoint Sources | 77.l | 656 |
| Point Sources | 257.6 | 1,551 |
| NO X Total | 1,057.9 | 6,256 |
| SO 2: | | |
| Events and Natural Sources | 12.1 | 174 |
| Mobile Sources | 13.9 | 70 |
| Nonpoint Sources | 6.7 | 40 |
| Point Sources | 14.8 | 84 |
| SO 2 Total | 47.6 | 368 |
| VOC: | | |
| Events and Natural Sources | 5,613.1 | 47,209 |
| Mobile Sources | 406.6 | 2,256 |
| Nonpoint Sources | 724.2 | 4,308 |
| Point Sources | 555.5 | 3,124 |
| VOC Total | 7,299.4 | 56,897 |
EPA has reviewed the results, procedures, and methodologies for the Klamath Falls 2017 attainment inventories and proposes to find that they are based on the most current and accurate information available to Oregon at the time they were developed. Based on our review of the emissions inventories that Oregon provided in its submission, we propose to find that Oregon prepared an adequate attainment inventory for the Klamath Falls area. [27 ]

2. Maintenance Demonstration

CAA section 175A requires a state seeking redesignation to attainment to submit a SIP revision to provide for maintenance of the NAAQS in the area “for at least 10 years after the redesignation.” A state can make this demonstration by either showing that future emissions of a pollutant or its precursors will not exceed the level of the attainment inventory or by modeling to show that the future mix of sources and emissions rates will not cause a violation of the NAAQS. [28 ]

In the Klamath Falls Maintenance Plan, Oregon elected the attainment inventory method to show that the Klamath Falls area will remain in attainment. Oregon developed projected emissions inventories for the year 2037, shown in table 2 of this document, which satisfies the 10-year interval required in CAA section 175A. Like the attainment inventories, the 2037 inventories include the four major source categories: events and natural sources, mobile sources, nonpoint sources, and point sources. Oregon projected future year emission inventories using the latest socioeconomic growth indictors and applying emissions reduction benefits from adopted control strategies when appropriate. [29 ] Oregon estimated “no growth” in emissions from 2017 to 2037 for point sources, events (wildfires/prescribed and structural fires) and some agriculture sources.

| Pollutant emissions by emission category | Annual emissions
(tons per year) | Typical season day
(pounds per day) |
| --- | --- | --- |
| Direct PM 2.5: | | |
| Events and Natural Sources | 163.5 | 2,347 |
| Mobile Sources | 59.6 | 348 |
| ( printed page 10553) | | |
| Nonpoint Sources | 223.7 | 994 |
| Point Sources | 158.5 | 1,002 |
| Direct PM 2.5 Total | 605.3 | 4,691 |
| NH 3: | | |
| Events and Natural Sources | 32.2 | 462 |
| Mobile Sources | 10.11 | 56 |
| Nonpoint Sources | 103.6 | 347 |
| Point Sources | 111.7 | 537 |
| NH 3 Total | 257.61 | 1,403 |
| NO X: | | |
| Events and Natural Sources | 72.8 | 559 |
| Mobile Sources | 451 | 2,469 |
| Nonpoint Sources | 79.8 | 670 |
| Point Sources | 208.5 | 1,281 |
| NO X Total | 812.1 | 4,980 |
| SO 2: | | |
| Events and Natural Sources | 12.11 | 174 |
| Mobile Sources | 14.1 | 71 |
| Nonpoint Sources | 6.9 | 38 |
| Point Sources | 14.8 | 84 |
| SO 2 Total | 47.91 | 367 |
| VOC: | | |
| Events and Natural Sources | 5,613.1 | 47,209 |
| Mobile Sources | 224.1 | 1,231 |
| Nonpoint Sources | 756.5 | 4,334 |
| Point Sources | 555.5 | 3,124 |
| VOC Total | 7,149.2 | 55,897 |
Table 3 of this document shows the change in projected annual and typical season day emissions between the 2017 attainment year and 2037 future year inventories. Future emissions of direct PM 2.5, NO X, and VOC are expected to be lower than in the 2017 attainment year, while future NH 3 and SO 2 emissions are expected to increase slightly, by approximately one percent by 2037. Oregon attributes the reductions in directly emitted PM 2.5 primarily to the removal of residential wood heating devices and their replacement with heat pumps or gas furnaces and to wood burning curtailment during stagnant conditions. [30 ]

| Pollutant emissions by emission category | Change in annual emissions
(tons per year) | Change in typical season day
emissions
(pounds per day) |
| --- | --- | --- |
| Direct PM 2.5: | | |
| Events and Natural Sources | 0 | 0 |
| Mobile Sources | 3.1 | 20 |
| Nonpoint Sources | −8.8 | −197 |
| Point Sources | 0 | 0 |
| Direct PM 2.5 Total | −5.7 | −177 |
| NH 3: | | |
| Events and Natural Sources | 0 | 0 |
| Mobile Sources | −2.89 | −13 |
| Nonpoint Sources | 6 | 10 |
| Point Sources | 0 | 0 |
| NH 3 Total | 3.11 | −3 |
| NO X: | | |
| Events and Natural Sources | 0 | 0 |
| Mobile Sources | −199.4 | −1,021 |
| ( printed page 10554) | | |
| Nonpoint Sources | 2.7 | 14 |
| Point Sources | −49.1 | −270 |
| NO X Total | −245.8 | −1,276 |
| SO 2: | | |
| Events and Natural Sources | 0.01 | 0 |
| Mobile Sources | 0.2 | 1 |
| Nonpoint Sources | 0.2 | −2 |
| Point Sources | 0 | 0 |
| SO 2 Total | 0.31 | −1 |
| VOC: | | |
| Events and Natural Sources | 0 | 0 |
| Mobile Sources | −182.5 | −1,025 |
| Nonpoint Sources | 32.3 | 26 |
| Point Sources | 0 | 0 |
| VOC Total | −150.2 | −1,000 |
EPA has reviewed the documentation provided by Oregon for developing the projected 2037 emissions inventories for the Klamath Falls area. Based on our review, EPA finds that the projected inventories were developed using appropriate assumptions and procedures, comprehensively address all source categories in the Klamath Falls area, and sufficiently account for PM 2.5 and NH 3, NO X, and VOC precursor emissions. These inventories indicate a decrease in directly emitted PM 2.5. The inventories indicate that NO X and VOC emissions will decrease throughout the maintenance period and that NH 3 and SO 2 will remain relatively stable or increase slightly throughout the maintenance period. Therefore, EPA proposes to determine that the projected emissions inventories in the Klamath Falls Maintenance Plan sufficiently demonstrate that the Klamath Falls area will continue to attain the 2006 24-hour PM 2.5 standard for the 10-year maintenance period.

3. Monitoring Network and Verification of Continued Attainment

Once a nonattainment area has been redesignated to attainment, the state must continue to operate an appropriate air quality monitoring network, in accordance with 40 CFR part 58, to verify the attainment status of the area. The maintenance plan should contain provisions for continued operation of air quality monitors that will provide such verification.

Oregon committed to continue to operate the air monitoring network in accordance with 40 CFR part 58. Oregon will use air monitoring results to verify continued attainment of the 2006 24-hour PM 2.5 NAAQS and to track progress of the Klamath Falls Maintenance Plan. Oregon stated that it will work with EPA through the air monitoring network review process to determine the adequacy of the monitoring network and consult with EPA on any modifications to the network. [31 ] EPA proposes to determine that the Klamath Falls Maintenance Plan contains adequate provisions for continued operation of an air quality monitoring network to verify maintenance of the 2006 24-hour PM 2.5 NAAQS. Additionally, Oregon is required to periodically update the emissions inventory for Klamath County in accordance with the Annual Air Emissions Reporting Requirements Rule. [32 ] This includes developing annual inventories for major point sources and a comprehensive periodic inventory covering all source categories every 3 years.

4. Contingency Plan

CAA section 175A(d) requires that a maintenance plan also include contingency provisions, as necessary, to promptly correct any violation of the NAAQS that occurs after redesignation of the area to attainment. For the purposes of CAA section 175A, a state is not required to have fully adopted contingency provisions that will take effect without further action by the state in order for the maintenance plan to be approved. However, the contingency plan is an enforceable part of the SIP and should ensure that contingency provisions are adopted expeditiously once they are triggered. The contingency plan should discuss the measures to be adopted and a schedule and procedure for adoption and implementation. The contingency plan must require that the state will implement all measures contained in the CAA part D nonattainment plan for the area (i.e., Klamath Falls Attainment Plan) prior to redesignation. The state should also identify the specific indicators, or triggers, that will be used to determine when the contingency plan will be implemented. [33 ]

The Klamath Falls Maintenance Plan outlines the procedures for the adoption and implementation of contingency provisions to further reduce emissions should a violation of the 2006 24-hour PM 2.5 NAAQS occur. If monitored PM 2.5 levels exceed 35 μg/m 3 , Oregon will work to determine the cause of the exceedance within 6 months of annual data certification. [34 ] Oregon will assess probable emissions sources and meteorological events contributing to elevated PM 2.5 levels, including information on wildfires or winter power outages.

Oregon has identified additional potential contingency measures for the Klamath Falls Maintenance Plan that ( printed page 10555) may be implemented as appropriate. These include:

  • Developing Red Day Plans for industrial sources of PM 2.5 with title V permits to be implemented on non-wildfire related predicted red days;
  • Developing updated RACT measures for industrial sources with the capacity to emit more than 50 pounds per day of PM 2.5;
  • Using the application process for debris burning or agricultural burning to spread out incidents of burning and limit exceedances;
  • Developing a street sweeping plan with local highway districts and the Oregon Department of Transportation to prioritize the reduction of fugitive road dust; and
  • Additional street paving projects. Oregon commits to adopting and implementing the necessary contingency measures as expeditiously as possible, but not later than one year after a violation, based on confirmed quality-assured data. Any contingency measures adopted and implemented will become part of the control measures in the next revised maintenance plan submitted to EPA for approval.

Based on EPA's review of Oregon's submittal, we propose to find that the contingency measure provisions provided in the Klamath Falls Maintenance Plan are sufficient and meet the requirements of CAA section 175A(d).

E. Transportation Conformity and Motor Vehicle Emissions Budgets

Transportation conformity is required by CAA section 176(c). EPA's transportation conformity rule at 40 CFR part 93, subpart A, requires that transportation plans, programs, and projects conform to SIPs and establishes the criteria and procedures for determining whether they conform to the SIP. Conforming to a SIP means that onroad transportation activities will not produce new air quality violations, worsen existing violations, or delay timely attainment of the NAAQS. Thus, EPA's transportation conformity rule requires a demonstration that emissions from a metropolitan planning organization's regional transportation plan and transportation improvement program, involving Federal Highway Administration (FHWA) or Federal Transit Administration (FTA) funding or approval, are consistent with the motor vehicle emissions budgets contained in a control strategy SIP revision or maintenance plan (40 CFR 93.101, 93.118, and 93.124). Generally, the budgets are the level of mobile source emissions of a pollutant relied upon in the attainment or maintenance demonstration to attain or maintain compliance with the NAAQS in the nonattainment or maintenance area. A PM 2.5 maintenance plan should identify budgets for direct PM 2.5, NO X and all other PM 2.5 precursors from onroad mobile source emissions that are determined to significantly contribute to PM 2.5 levels in the area. [35 ]

Oregon indicated that the Klamath Falls nonattainment area meets the definition of an “isolated rural nonattainment area” at 40 CFR 93.109(g) because the area does not contain, and is not part of, a metropolitan planning organization. Neither a transportation improvement plan nor a regional transportation plan was developed for the Klamath Falls area. Instead, transportation projects for Klamath Falls are included in a statewide transportation improvement plan. The Oregon Department of Transportation is responsible for transportation conformity determinations in this isolated rural nonattainment area.

The Klamath Falls Maintenance Plan identifies budgets for PM 2.5 and NO X, which are displayed in table 4 of this document. Oregon used EPA's Motor Vehicle Emission Simulator model (MOVES3.1) in emissions inventory mode to estimate 2037 future year emissions from onroad mobile sources for a typical season day. The budgets for the 2037 future year will be 77 and 1,448 lbs/day for PM 2.5 and NO X respectively. The Klamath Falls Maintenance Plan also established a safety margin for the 2037 future year budgets along with additional margin allocated from emissions reductions from woodstoves. The safety margin was applied to the 2037 future year motor vehicle emissions budgets to account for emissions from future transportation projects. Oregon projects that 411 woodstoves will be removed from the Klamath Falls nonattainment area by 2028, which Oregon projects will lead to decreases in PM 2.5 and NO X emissions. To provide an extra safety margin for mobile vehicle emissions, a portion of the projected emissions reductions from the 411 woodstove removals was allocated to the 2037 future year motor vehicle emissions budgets. Oregon did not include emissions from paved road dust because those emissions were found to be insignificant. Oregon also found that motor vehicle emissions of VOC, SO 2 and NH 3 contributed minimally to PM 2.5 in the area and did not include budgets for these precursors in accordance with 40 CFR 93.102(b)(2)(v).

| Year | PM 2.5 emissions | NO X emissions |
| --- | --- | --- |
| 2017 Attainment Year | 64 | 2,149 |
| 2037 Future Year | 77 | 1,448 |
EPA is proposing to find that Oregon has evaluated the appropriate pollutants and precursors and established appropriate budgets for PM 2.5 and NO X. Oregon used the most up-to-date model (MOVES3.1) available at the time of submission to appropriately calculate these budgets. [36 ] The budgets are based on the control measures in the Klamath Falls Maintenance Plan and consistent with maintaining the 2006 24-hour PM 2.5 NAAQS.

EPA completed the adequacy review for the motor vehicle emissions budgets in a separate, tangential process which is detailed in 40 CFR 93.118(f). The adequacy review process consists of three basic steps: (1) public notification of a SIP submission; (2) a public comment period; and (3) EPA's adequacy determination. EPA completed steps (1) and (2) by posting a notice on the Office of Transportation and Air Quality website inviting the public to comment on the adequacy of the NO X and PM 2.5 motor vehicle emissions budgets in the Klamath Falls Maintenance Plan. [37 ] The comment period was open from September 5, 2024, through October 7, 2024. EPA did not receive adverse comments and found the budgets adequate on April 23, 2025. EPA published a notice of adequacy on August 21, 2025 (90 FR 40737). Because EPA found the motor vehicle emissions budgets adequate, we are not soliciting comments on budget adequacy as part of this notice of proposed rulemaking. The motor vehicle emissions budgets adequacy review process is separate from any action on the submitted SIP and allows for motor vehicle emissions budgets to be used for transportation conformity purposes, provided they meet the criteria in 40 CFR 93.118(e).

Based on the information presented in the Klamath Falls Maintenance Plan for ( printed page 10556) the 2006 24-hour PM 2.5 NAAQS, and the adequacy review of the motor vehicle emissions budgets that we have completed, we propose to approve the motor vehicle emissions budgets in the Klamath Falls Maintenance Plan as meeting the requirements of the CAA and EPA regulations.

F. State Rule Changes To Reflect the Redesignation

Oregon also submitted rule revisions to reflect the anticipated redesignation of the Klamath Falls PM 2.5 nonattainment area to attainment (OAR 340-204-0010, -0030, -0040, and OAR 340-240-0010, -0500, -0550, -0560). Additionally, Oregon submitted rule revisions that reflect the attainment status of the Oakridge PM 2.5 and PM 10 former nonattainment areas which EPA redesignated to attainment in 2022 (OAR 340-204-0030, -0040). [38 ] These revisions remove Klamath Falls and Oakridge from Oregon's list of PM 2.5 nonattainment areas, and they remove Oakridge from Oregon's list of PM 10 nonattainment areas. Accordingly, the revisions also add these areas to Oregon's list of PM 2.5 and PM 10 maintenance areas.

V. Proposed Action

EPA proposes to redesignate the Klamath Falls, Oregon PM 2.5 nonattainment area to attainment and approve the Klamath Falls Maintenance Plan. If this proposal is finalized, the designation status of the Klamath Falls, Oregon PM 2.5 nonattainment area under 40 CFR part 81 will be revised to attainment upon the effective date of that final action.

EPA proposes to approve and incorporate by reference into the Oregon SIP, the submitted revisions to OAR 340-204-0010, -0030, -0040, and OAR 340-240-0010, -0500, -0550, -0560, state effective May 25, 2024; and Klamath County Code Chapter 406, Ordinance No. 63.07, state effective June 25, 2024, except the following provisions that were not submitted for approval into the Oregon SIP: 406.150(1)(D)(e) regarding emergency conditions, section 406.250 regarding certificate of variance, section 406.300 regarding enforcement, and section 406.400 regarding penalties.

Finally, we propose that the motor vehicle emissions budgets in the Klamath Falls Maintenance Plan meet applicable CAA requirements for maintenance plans and transportation conformity requirements.

VI. Incorporation by Reference

In this document, EPA proposes to include, in a final rule, regulatory text that includes incorporation by reference. In accordance with the requirements of 1 CFR 51.5, EPA proposes to incorporate by reference the provisions described in section IV of this document.

EPA has made, and will continue to make, these documents generally available through https://www.regulations.gov and at the EPA Region 10 Office (please contact the person identified in the FOR FURTHER INFORMATION CONTACT section of this preamble for more information).

VII. Statutory and Executive Order Reviews

Under the Clean Air Act, the Administrator is required to approve a SIP submission that complies with the provisions of the Clean Air Act and applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve State choices, provided that they meet the criteria of the Clean Air Act. Accordingly, this action merely approves State law as meeting Federal requirements and does not impose additional requirements beyond those imposed by State law. For that reason, this action:

  • Is not a significant regulatory action subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);
  • Is not subject to Executive Order 14192 (90 FR 9065, February 6, 2025) because SIP actions are exempt from review under Executive Order 12866;
  • Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
  • Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);
  • Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
  • Does not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
  • Is not subject to Executive Order 13045 (62 FR 19885, April 23, 1997) because it approves a State program;
  • Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001); and
  • Is not subject to requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the Clean Air Act. 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 rule does not have Tribal implications and will not impose substantial direct costs on Tribal governments or preempt Tribal law as specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects

40 CFR Part 52

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

40 CFR Part 81

  • Environmental protection
  • Air pollution control
  • Carbon monoxide
  • Intergovernmental relations
  • Lead
  • Nitrogen dioxide
  • Ozone
  • Particulate matter
  • Reporting and recordkeeping requirements
  • Sulfur oxides
  • Volatile organic compounds Authority: 42 U.S.C. 7401 et seq.

Dated: February 20, 2026.

Emma Pokon,

Regional Administrator, Region 10.

Footnotes

1.

                     
                    See [80 FR 51470](https://www.federalregister.gov/citation/80-FR-51470) (August 25, 2015) and [81 FR 36176](https://www.federalregister.gov/citation/81-FR-36176) (June 6, 2016).

Back to Citation 2. Id.

Back to Citation 3.

                     
                    See [80 FR 51470](https://www.federalregister.gov/citation/80-FR-51470) (August 25, 2015).

Back to Citation 4.

                     See FY 2025 Income Limits Documentation System, Klamath County, available at *<a href="https://www.huduser.gov/portal/datasets/il/il2025/2025summary.odn?STATES=41.0&INPUTNAME=NCNTY41035N41035*4103599999%252BKlamath+County&statelist=&stname=Oregon&wherefrom=&statefp=41&year=2025&ne_flag=&selection_type=county&incpath=&data=2025&SubmitButton=View+County+Calculations/">https://www.huduser.gov/​portal/​datasets/​il/​il2025/​2025summary.odn?​STATES=​41.0&​INPUTNAME=​NCNTY41035N41035*4103599999%2BKlamath+​County&​statelist=​&​stname=​Oregon&​wherefrom=​&​statefp=​41&​year=​2025&​ne_​flag=​&​selection_​type=​county&​incpath=​&​data=​2025&​SubmitButton=​View+​County+​Calculations/</a>.*

Back to Citation 5.

                     2025 Poverty Guidelines: 48 Contiguous States (all states except Alaska and Hawaii), available at *<a href="https://aspe.hhs.gov/sites/default/files/documents/dd73d4f00d8a819d10b2fdb70d254f7b/detailed-guidelines-2025.pdf/">https://aspe.hhs.gov/​sites/​default/​files/​documents/​dd73d4f00d8a819d10b2fdb70d254f7b/​detailed-guidelines-2025.pdf/</a>.*

Back to Citation 6. 40 CFR 51.1009(a)(3).

Back to Citation 7.

                     2024 Biennial Energy Report, Oregon Department of Energy, November 2024, p. 45, available at *<a href="https://www.oregon.gov/energy/Data-and-Reports/Documents/2024-Biennial-Energy-Report.pdf/">https://www.oregon.gov/​energy/​Data-and-Reports/​Documents/​2024-Biennial-Energy-Report.pdf/</a>.*

Back to Citation 8.

                     U.S. Department of Energy, Low-Income Energy Affordability Data (LEAD) Tool, available at *<a href="https://www.energy.gov/scep/low-income-energy-affordability-data-lead-tool/">https://www.energy.gov/​scep/​low-income-energy-affordability-data-lead-tool/</a>.*

Back to Citation 9.

                     2024 Biennial Energy Report, Oregon Department of Energy, November 2024, p. 61, available at *<a href="https://www.oregon.gov/energy/Data-and-Reports/Documents/2024-Biennial-Energy-Report.pdf/">https://www.oregon.gov/​energy/​Data-and-Reports/​Documents/​2024-Biennial-Energy-Report.pdf/</a>.*

Back to Citation 10.

                     We note that Oregon did not submit section 406.150.1.D.e, “other emergencies as determined by Klamath County Public Health,” for EPA's approval into the Oregon SIP.

Back to Citation 11.

                     
                    See 
                     “State Implementation Plans; General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990,” [57 FR 13498](https://www.federalregister.gov/citation/57-FR-13498) (April 16, 1992).

Back to Citation 12.

                     The design value is the metric calculated in accordance with [40 CFR part 50, appendix N](https://www.ecfr.gov/current/title-40/part-50/appendix-Appendix%2520N%2520to%2520Part%252050), for determining compliance with the NAAQS. Section 4.5 of appendix N provides the procedures and equations for calculating the 24-hour PM 2.5 NAAQS design values and section 4.3 provides the rounding conventions.

Back to Citation 13.

                     Calcagni Memo, 3; *Wall* v. *EPA,* 265 F.3d 426, 438 (6th Cir. 2001); and *Southwestern Pennsylvania Growth Alliance* v. *Browner,* 144 F.3d 984, 989-990 (6th Cir. 1998).

Back to Citation 14.

                     
                    See 
                     the General Preamble for further explanation of these requirements. [57 FR 13498](https://www.federalregister.gov/citation/57-FR-13498) (April 16, 1992).

Back to Citation 15.

                     
                    See [75 FR 36023](https://www.federalregister.gov/citation/75-FR-36023) through [36026](https://www.federalregister.gov/citation/75-FR-36026) (June 24, 2010) and citations within.

Back to Citation 16. See e.g., 78 FR 46514 (August 1, 2013), and 80 FR 2313 (January 16, 2015).

Back to Citation 17.

                     
                    See [81 FR 58010](https://www.federalregister.gov/citation/81-FR-58010) (August 24, 2016). Codified at [40 CFR part 51, subpart Z](https://www.ecfr.gov/current/title-40/part-51/subpart-Z).

Back to Citation 18.

                     
                    See 
                     CAA section 188(c)(1), [42 U.S.C. 7513(c)(1)](https://www.govinfo.gov/link/uscode/42/7513), and [40 CFR 51.1004(a)(1)](https://www.ecfr.gov/current/title-40/section-51.1004#p-51.1004(a)(1)). *See also* Identification of Nonattainment Classification and Deadlines for Submission of State Implementation Plan (SIP) Provisions for the 1997 Fine Particle (PM 2.5) National Ambient Air Quality Standard (NAAQS) and 2006 PM 2.5 NAAQS (June 2, 2014), [79 FR 31566](https://www.federalregister.gov/citation/79-FR-31566), [31567-68](https://www.federalregister.gov/citation/79-FR-31567).

Back to Citation 19.

                     
                    See [80 FR 51470](https://www.federalregister.gov/citation/80-FR-51470) (August 25, 2015) and [81 FR 36176](https://www.federalregister.gov/citation/81-FR-36176) (June 6, 2016).

Back to Citation 20.

                     
                    See [80 FR 51470](https://www.federalregister.gov/citation/80-FR-51470) (August 25, 2015).

Back to Citation 21.

                     Information on EPA certified woodstoves is available at: *<a href="https://www.epa.gov/burnwise/epa-certified-wood-stoves/">https://www.epa.gov/​burnwise/​epa-certified-wood-stoves/</a>.*

Back to Citation 22.

                     The air quality zone is slightly smaller than the Klamath Falls nonattainment area. (
                    See 
                     Klamath Clean Air Ordinance, Exhibit A).

Back to Citation 23.

                     We note that other control measures apply during the opacity start-up exemption, which target emissions reductions from the same sources, including a requirement that only dry, seasoned cordwood, pressed sawdust logs, organic charcoal or pellets specifically manufactured for the appliance can be burned.

Back to Citation 24.

                     
                    See 
                     Calcagni Memo at 8.

Back to Citation 25.

                     Air Quality Design Values are available at *<a href="https://www.epa.gov/air-trends/air-quality-design-values/">https://www.epa.gov/​air-trends/​air-quality-design-values/</a>.* The 2015-2017 design value excludes data from wildfire exceptional events. EPA's concurrence letter, technical support document, and monitoring data report are included in the docket for this rulemaking.

Back to Citation 26.

                     For more information on how the mobile source emissions were developed, *see* section IV.E of this document.

Back to Citation 27.

                     “Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations,” May 2017.

Back to Citation 28.

                     
                    See 
                     Calcagni Memo, pages 9-10.

Back to Citation 29.

                     For more detailed information on the inventories, *see* appendix 2 of the Klamath Falls Redesignation Request and Maintenance Plan for PM 2.5, in the docket for this rulemaking.

Back to Citation 30.

                     The control strategies are discussed in section IV.C of this document.

Back to Citation 31.

                     See EPA's May 16, 2025, approval of Oregon's 2024 Annual Monitoring Network Plan, included in the docket for this rulemaking.

Back to Citation 32.

                     Information about the Air Emissions Reporting Rule is available at *<a href="https://www.epa.gov/air-emissions-inventories/air-emissions-reporting-requirements-aerr/">https://www.epa.gov/​air-emissions-inventories/​air-emissions-reporting-requirements-aerr/</a>.*

Back to Citation 33.

                     
                    See 
                     Calcagni Memo at 12.

Back to Citation 34. 40 CFR 58.15(a) requires air agencies to certify air quality data by May 1 of each year.

Back to Citation 35.

                     See [40 CFR 93.102(b)(2)(iv)](https://www.ecfr.gov/current/title-40/section-93.102#p-93.102(b)(2)(iv)) and [(v)](https://www.ecfr.gov/current/title-40/section-93.102#p-93.102(b)(2)(v)), and [(b)(3)](https://www.ecfr.gov/current/title-40/section-93.102#p-93.102(b)(3)).

Back to Citation 36.

                     We have previously explained that state agencies may continue to use MOVES3 in SIP development where the State has already completed significant work on a SIP at the time EPA releases a new model, as is the case here. [89 FR 99862](https://www.federalregister.gov/citation/89-FR-99862) through [99864](https://www.federalregister.gov/citation/89-FR-99864) (December 11, 2024).

Back to Citation 37.

                     Motor vehicle emissions budgets that have been found adequate and that are under EPA's review are available at *<a href="https://www.epa.gov/state-and-local-transportation/adequacy-review-state-implementation-plan-sip-submissions-conformity/">https://www.epa.gov/​state-and-local-transportation/​adequacy-review-state-implementation-plan-sip-submissions-conformity/</a>.*

Back to Citation 38.

                     
                    See [87 FR 51265](https://www.federalregister.gov/citation/87-FR-51265) (August 22, 2022).

Back to Citation [FR Doc. 2026-04333 Filed 3-3-26; 8:45 am]

BILLING CODE 6560-50-P

Published Document: 2026-04333 (91 FR 10545)

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March 4th, 2026
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