The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2025-1112; Project Identifier MCAI-2025-00027-T” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend this proposal because of those comments.

Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to regulations.gov , including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.

CBI is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this NPRM contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as “PROPIN.” The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI should be sent to Kin Suen Chan, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 312-203-5670; email: Kin.Suen.Chan@faa.gov. Any commentary that the FAA receives that is not specifically designated as CBI will be placed in the public docket for this rulemaking.

The FAA issued AD 2024-08-05, Amendment 39-22738 (89 FR 50505, June 14, 2024) (AD 2024-08-05), for Airbus SAS Model A330-200 series, A330-200 Freighter series, A330-300 series, A330-841, and A330-941 airplanes with an original airworthiness certificate or original export certificate of airworthiness issued on or before October 2, 2023. AD 2024-08-05 was prompted by an MCAI originated by EASA, which is the Technical Agent for the Member States of the European Union. EASA issued AD 2023-0199, dated November 17, 2023 (EASA AD 2023-0199) to correct an unsafe condition identified as a safety-significant latent failure (that is not annunciated) that, in combination with one or more other specific failures or events, could result in hazardous or catastrophic failure condition. AD 2024-08-05 requires revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations.

Since the FAA issued AD 2024-08-05, EASA superseded AD 2023-0199 and issued EASA AD 2025-0012, dated January 13, 2025 (EASA AD 2025-0012) (referred to after this as “the MCAI”), for all Airbus SAS Model A330-200 series, A330-200 Freighter series, A330-300 series, A330-841, and A330-941 airplanes. The MCAI states that new and/or more restrictive airworthiness limitations for certification maintenance requirements (CMRs) related to the air cooling temperature control and pneumatic system have been developed.

Airplanes with an original airworthiness certificate or original export certificate of airworthiness issued after October 1, 2024, must comply with the new and more restrictive airworthiness limitations, as those airworthiness limitations are part of the approved type design and referenced on the type certificate data sheet; this proposed AD therefore does not include those airplanes in the applicability.

The FAA is proposing this AD to address a safety-significant latent failure (that is not annunciated) that, in combination with one or more other specific failures or events, could result in a hazardous or catastrophic failure condition. You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2025-1112.

The FAA reviewed EASA AD 2025-0012. This material specifies new and more restrictive airworthiness limitations for airplane structures.

This proposed AD would also require EASA AD 2023-0199, which the Director of the Federal Register approved for incorporation by reference as of July 19, 2024 (89 FR 50505, June 14, 2024).

This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

This product has been approved by the aviation authority of another country and is approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, it has notified the FAA of the unsafe condition described in the MCAI referenced above. The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop in other products of the same type design.

This proposed AD would retain certain requirements of AD 2024-08-05 until the existing maintenance or inspection program, as applicable, is revised to incorporate the additional new and more restrictive airworthiness limitations, which are specified in EASA AD 2025-0012 already described, as proposed for incorporation by reference. Any differences with EASA AD 2025-0012 are identified as exceptions in the regulatory text of this proposed AD.

This proposed AD would require revisions to certain operator maintenance documents to include new actions ( e.g., inspections). Compliance with these actions is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by this proposed AD, the operator may not be able to accomplish the actions described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance (AMOC) according to paragraph (n)(1) of this proposed AD.

AD 2022-17-08, Amendment 39-22146 (87 FR 54865, September 8, 2022) (AD 2022-17-08) applies to Model A330-201, -202, -203, -223, 223F, -243, -243F, -301, -302, -303, -321, -322, -323, -341, -342, and -343 airplanes and requires, among other actions, repetitive maintenance tasks and corrective actions for failures related to over-temperature conditions. Accomplishing the actions in paragraph (j) of this proposed AD would terminate those repetitive maintenance tasks and corrective actions, which are specified in paragraphs (4) through (7) of EASA AD 2021-0281, dated December 17, 2021, and required by paragraph (g) of AD 2022-17-08.

In the FAA's ongoing efforts to improve the efficiency of the AD process, the FAA developed a process to use some civil aviation authority (CAA) ADs as the primary source of information for compliance with requirements for corresponding FAA ADs. The FAA has been coordinating this process with manufacturers and CAAs. As a result, the FAA proposes to retain the incorporation by reference (IBR) of EASA AD 2023-0199 and incorporate EASA AD 2025-0012 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with EASA AD 2023-0199 and EASA AD 2025-0012 through that incorporation, except for any differences identified as exceptions in the regulatory text of this proposed AD. Using common terms that are the same as the heading of a particular section in EASA AD 2023-0199 or EASA AD 2025-0012 does not mean that operators need comply only with that section. For example, where the AD requirement refers to “all required actions and compliance times,” compliance with this proposed AD requirement is not limited to the section titled “Required Action(s) and Compliance Time(s)” in EASA AD 2023-0199 or EASA AD 2025-0012. Material required by EASA AD 2023-0199 and EASA AD 2025-0012 for compliance will be available at regulations.gov by searching for and locating Docket No. FAA-2025-1112 after the FAA final rule is published.

The FAA's process of incorporating by reference MCAI ADs as the primary source of information for compliance with corresponding FAA ADs has been limited to certain MCAI ADs (primarily those with service bulletins as the primary source of information for accomplishing the actions required by the FAA AD). However, the FAA is now expanding the process to include MCAI ADs that require a change to airworthiness limitation documents, such as airworthiness limitation sections.

For these ADs that incorporate by reference an MCAI AD that changes airworthiness limitations, the FAA requirements are unchanged. Operators must revise the existing maintenance or inspection program, as applicable, to incorporate the information specified in the new airworthiness limitation document. The airworthiness limitations must be followed according to 14 CFR 91.403(c) and 91.409(e).

The previous format of the airworthiness limitation ADs included a paragraph that specified that no alternative actions ( e.g., inspections) or intervals may be used unless the actions and intervals are approved as an AMOC in accordance with the procedures specified in the AMOCs paragraph under “Additional AD Provisions.” This new format includes a “New Provisions for Alternative Actions and Intervals” paragraph that does not specifically refer to AMOCs, but operators may still request an AMOC to use an alternative action or interval. Operators may not use alternative actions or intervals under 14 CFR 91.403(c).

The FAA estimates that this AD, if adopted as proposed, would affect 158 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD:

The FAA estimates the cost per operator for the retained action from AD 2024-08-05 to be $7,650 (90 work-hours × $85 per work-hour).

The FAA has determined that revising the existing maintenance or inspection program takes an average of 90 work-hours per operator, although the agency recognizes that this number may vary from operator to operator. Since operators incorporate maintenance or inspection program changes for their affected fleet(s), the FAA has determined that a per-operator estimate is more accurate than a per-airplane estimate.

The FAA estimates the total cost per operator for the new proposed actions to be $7,650 (90 work-hours × $85 per work-hour).

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.

The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Would not affect intrastate aviation in Alaska, and

(3) Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under ADDRESSES . Include “Docket No. FAA-2025-1113; Project Identifier MCAI-2024-00552-A” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend this proposal because of those comments.

Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to regulations.gov , including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.

CBI is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this NPRM contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as “PROPIN.” The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI should be sent to Doug Rudolph, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.

The European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2024-0183, dated September 20, 2024 (EASA AD 2024-0183) (also referred to as “the MCAI”), to correct an unsafe condition on Polskie Zaklady Lotnicze Sp. z o.o. Models PZL M28 02-W and PZL M28 05 airplanes, all manufacturer serial numbers. The MCAI states that occurrences have been reported by pilot instructors where, during type rating training with Model PZL M28 airplanes, students applied an incorrect flap setting and airspeed while practicing the emergency procedure for an approach and landing with OEI after a simulated engine failure. The investigation concluded that the root cause for these occurrences was typographical errors in the AFM. The MCAI requires incorporating an AFM update containing the correct flap setting and airspeed to be applied during approach with OEI. Applying an incorrect flap setting and airspeed during an approach for landing under (simulated) OEI conditions could result in loss of control of the airplane.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2025-1113.

The FAA reviewed pages 3-4 ENGINE FAILURE AT DESCENT and ENGINE FAILURE DURING BALKED LANDING; 3-9 BALKED LANDING WITH ONE ENGINE INOPERATIVE; 3-17 ENGINE FAILURE AT DESCENT (LANDING APPROACH); 3-18 ENGINE FAILURE DURING BALKED LANDING; and 3-25 and 3-26 BALKED LANDING WITH ONE ENGINE INOPERATIVE from Section 3, Emergency Procedures in Polskie Zakłady Lotnicze Sp. z o.o. Airplane Flight Manual, Model PZL M28 05, Revision 55, dated July 9, 2024. This material provides the correct emergency procedures for the flightcrew when adjusting the flap settings and airspeed during approach for landing under simulated OEI conditions.

The FAA also reviewed Polskie Zaklady Lołnicze Sp. z o.o. Check List, PZL M28 05 with PT6A-65B engines, Emergency Procedures, Revision 1, dated July 9, 2024. This material provides the flightcrew with the correct emergency procedures checklist that corresponds with the changes to Section 3, Emergency Procedures, of the AFM.

In addition, the FAA reviewed Polskie Zakłady Lotnicze Sp. z o.o. Check List, PZL M28 05 with PT6A-65B engines, Emergency Procedures, effective on airplanes without the installed ice protection system certified for flights in known and forecast icing conditions, Revision 1, dated July 9, 2024. This material provides the flightcrew with the correct emergency procedures checklist that corresponds with the changes to Section 3, Emergency Procedures, of the AFM.

This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

These products have been approved by the aviation authority of another country and are approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, it has notified the FAA of the unsafe condition described in the MCAI and material referenced above. The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.

This proposed AD would require revising the existing AFM for your airplane to provide the correct emergency procedures and checklist for the flightcrew when adjusting the flap settings and airspeed during approach for landing under OEI conditions. See “Differences Between this Proposed AD and the MCAI” for a discussion of the general differences included in this AD.

The owner/operator (pilot) holding at least a private pilot certificate may revise the existing AFM and checklist for your airplane and must enter compliance with the applicable paragraph of this proposed AD into the airplane maintenance records in accordance with 14 CFR 43.9(a) and 91.417(a)(2)(v). The pilot may perform this action because it only involves revising the AFM. This action could be performed equally well by a pilot or a mechanic. This is an exception to the FAA's standard maintenance regulations.

The MCAI applies to Polskie Zaklady Lotnicze Sp. z o.o. Model PZL M28 02-W airplanes, but this proposed AD would not because this model does not have an FAA type certificate.

The MCAI requires informing all pilots about the AFM update and thereafter operating the airplane accordingly, and this proposed AD would not because those actions are already required by FAA regulations.

The FAA estimates that this AD, if adopted as proposed, would affect nine airplanes of U.S. registry.

The FAA estimates the following costs to comply with this proposed AD:

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.

The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Would not affect intrastate aviation in Alaska, and

(3) Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

Comments Invited

The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2025-0482; Project Identifier MCAI-2024-00152-T” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend this proposal because of those comments.

Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to regulations.gov , including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.

CBI is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this NPRM contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as “PROPIN.” The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI should be sent to Yaser Osman, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7300; email 9-avs-nyaco-cos@faa.gov. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.

The FAA issued AD 2019-16-09, Amendment 39-19712 (84 FR 46434, September 4, 2019) (AD 2019-16-09), for certain De Havilland Aircraft of Canada Limited Model DHC-8-400, -401, and -402 airplanes. AD 2019-16-09 was prompted by an MCAI originated by Transport Canada, which is the aviation authority for Canada. Transport Canada issued AD CF-2018-34, dated December 17, 2018 (Transport Canada AD CF-2018-34), to correct an unsafe condition.

AD 2019-16-09 requires one-time inspections for cracks and damage of the elevator PCU fittings (brackets) and surrounding area, horizontal stabilizer rear spar, and elevator front spar, and related investigative and corrective actions if necessary. The FAA issued AD 2019-16-09 to address failure of an elevator PCU fitting (bracket) or fracture of the front spar into two segments; either structural failure may cause a jam in one elevator or a loss of airplane pitch control if both elevators are affected.

Since the FAA issued AD 2019-16-09, Transport Canada superseded AD CF-2018-34 and issued Transport Canada AD CF-2024-10, dated March 1, 2024 (Transport Canada AD CF-2024-10), to correct an unsafe condition for certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes. Transport Canada AD CF-2024-10 states that new findings have been reported as a result of maintenance activities and/or inspections performed in accordance with De Havilland Aircraft of Canada Limited Service Bulletin 84-55-09, dated June 7, 2018 (the service information required by FAA AD 2019-16-09). Transport Canada AD CF-2024-10 requires repeating the inspections one time and performing applicable on-condition actions, while maintaining the requirements of AD 2019-16-09. Transport Canada AD CF-2024-10 also removes the requirement to report findings to the manufacturer.

Transport Canada also issued AD CF-2025-19, dated March 24, 2025 (Transport Canada AD CF-2025-19), which provides a new design solution to address the unsafe condition identified in this NPRM and terminates the actions specified in Transport Canada AD CF-2024-10.

The FAA is proposing this AD to address the unsafe condition on these products. You may examine Transport Canada ADs CF-2024-10 and CF-2025-19 in the AD docket at regulations.gov under Docket No. FAA-2025-0482.

Although this proposed AD does not explicitly restate the requirements of AD 2019-16-09, this proposed AD would retain certain requirements of AD 2019-16-09. Those requirements are referenced in Transport Canada AD CF-2024-10, which, in turn, is referenced in paragraph (g) of this proposed AD.

Transport Canada AD CF-2024-10 specifies procedures for performing detailed visual and fluorescent penetrant inspections for cracks and damage of the elevator PCU fittings (brackets), horizontal stabilizer rear spar, and elevator front spar; repeating the inspections one time; rectifying any cracked or damaged elevator PCU fitting (bracket) (which includes replacing the elevator PCU fitting (bracket) and performing related investigative and corrective actions including performing an eddy current inspection for cracking of certain mating holes of the horizontal stabilizer rear spar); and repairing any cracked or damaged horizontal stabilizer rear spar assembly.

Transport Canada AD CF-2025-19 specifies procedures for, among other actions, replacement of existing PCU fittings with redesigned PCU fittings. The replacement includes detailed inspections for damage and eddy current inspections for cracking, repair, installation of new bushings, and installation of doublers.

This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

This product has been approved by the aviation authority of another country and is approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, it has notified the FAA of the unsafe condition described in Transport Canada AD CF-2024-10 referenced above. The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop in other products of the same type design.

This proposed AD would retain certain requirements of AD 2019-16-09. This proposed AD would remove an airplane from the applicability and require accomplishing the actions specified in Transport Canada AD CF-2024-10 described previously, except for any differences identified as exceptions in the regulatory text of this proposed AD. This proposed AD would also provide optional terminating action for the repetitive inspections, as specified in Transport Canada AD CF-2025-19.

In the FAA's ongoing efforts to improve the efficiency of the AD process, the FAA developed a process to use some civil aviation authority (CAA) ADs as the primary source of information for compliance with requirements for corresponding FAA ADs. The FAA has been coordinating this process with manufacturers and CAAs. As a result, the FAA proposes to incorporate Transport Canada ADs CF-2024-10 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with Transport Canada AD CF-2024-10 in its entirety through that incorporation, except for any differences identified as exceptions in the regulatory text of this proposed AD. Material required by Transport Canada ADs CF-2024-10 for compliance will be available at regulations.gov under Docket No. FAA-2025-0482 after the FAA final rule is published.

The FAA considers that this proposed AD would be an interim action. The FAA is considering mandating the optional terminating action specified in Transport Canada AD CF-2025-19.

The FAA estimates that this AD, if adopted as proposed, would affect 54 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD:

The FAA estimates the following costs to do any necessary on-condition actions that would be required based on the results of any required actions. The FAA has no way of determining the number of aircraft that might need this on-condition action:

The FAA has received no definitive data on which to base the cost estimates for the on-condition repairs specified in this proposed AD.

According to the manufacturer, some or all of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected individuals. The FAA does not control warranty coverage for affected individuals. As a result, the FAA has included all known costs in the cost estimate.

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.

The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Would not affect intrastate aviation in Alaska, and

(3) Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

Throughout this document, “we,” “us,” and “our” refer to the EPA.

The EPA sets the NAAQS for certain ambient air pollutants at levels required to protect human health and the environment. Ground-level ozone pollution is formed from the reaction of volatile organic compounds (VOCs) and oxides of nitrogen (NO X ) in the presence of sunlight. 1 These two pollutants, referred to as ozone precursors, are emitted by many types of sources, including on- and off-road motor vehicles and engines, power plants and industrial facilities, and smaller area sources such as lawn and garden equipment and paints.

Scientific evidence indicates that adverse public health effects occur following exposure to ozone, particularly in children and adults with lung disease. Breathing air containing ozone can reduce lung function and inflame airways, which can increase respiratory symptoms and aggravate asthma or other lung diseases. 2

Under section 109 of the CAA, the EPA promulgates NAAQS for pervasive air pollutants, such as ozone. Following promulgation of a new or revised NAAQS, the CAA requires the EPA to designate areas throughout the nation as either attaining or not attaining the standards.

On February 8, 1979, the EPA established primary and secondary NAAQS for ozone at 0.12 parts per million (ppm) averaged over a 1-hour period. 3 On July 18, 1997, the EPA revised the primary and secondary standards for ozone to 0.08 ppm averaged over an 8-hour period (“1997 ozone NAAQS”). 4 In 2004, the EPA published the 1997 ozone NAAQS designations and classifications  5 and a rule governing certain facets of implementation of the 1997 ozone NAAQS (“Phase 1 Rule”). 6 The Phase 1 Rule established the revocation of the 1979 ozone NAAQS one year following the effective date of the designations for the 1997 ozone NAAQS and set anti-backsliding provisions for the transition from the 1-hour to the 1997 8-hour standard. Anti- backsliding provisions provide for controls that are not less stringent than the controls applicable to areas that were listed as nonattainment for the revoked ozone standards when the standards and designations were revoked.

The Phase 1 Rule and its subsequent revision did not include contingency measures, new source review (NSR) requirements, conformity determinations, or the section 185 fee program among the measures retained as 1-hour ozone standard anti-backsliding requirements. 7 However, on December 23, 2006, the U.S. Court of Appeals for the District of Columbia Circuit determined that the EPA should not have excluded these requirements from its anti-backsliding requirements. 8

In 2015, the EPA revoked the 1997 ozone NAAQS, established anti-backsliding requirements for the revoked 1997 ozone NAAQS, and revised the anti-backsliding requirements for the revoked 1-hour ozone standard as a part of the final rule for implementing the 2008 ozone 8-hour NAAQS (“2008 NAAQS SIP Requirements Rule”). 9 The EPA considered the South Coast I decision on the Phase 1 Rule in developing the 2008 NAAQS SIP Requirements Rule for the 2008 8-hour ozone standard (“2008 ozone NAAQS”). 10

The 2008 NAAQS SIP Requirements Rule provided that an area will be subject to the anti-backsliding obligations for a revoked NAAQS until the EPA approves either (1) a redesignation to attainment for the area for the 2008 ozone NAAQS or (2) a “redesignation substitute” for a revoked NAAQS, which required an area to demonstrate that it had attained the revoked NAAQS due to permanent and enforceable measures and would maintain that standard for ten years. 11 In the 2008 NAAQS SIP Requirements Rule, the EPA created the redesignation substitute procedure because it believed it did not have the authority under the CAA to change the designations of areas under a revoked NAAQS but wanted to establish a means to terminate anti-backsliding requirements for an area that would otherwise be eligible for a redesignation had the standard not been revoked. 12 Though the EPA created the redesignation substitute based on the CAA section 107(d)(3)(E) redesignation criteria, the procedure did not require states to demonstrate satisfaction of all five criteria.

On February 16, 2018, the U.S. Court of Appeals for the District of Columbia Circuit vacated certain parts of the 2008 NAAQS SIP Requirements Rule, including the redesignation substitute provision, based on the court's conclusion that those provisions were not consistent with CAA requirements. 13 In South Coast II, the Court held that the redesignation substitute tool was not consistent with CAA requirements because it failed to satisfy all five of the statutory requirements set forth in CAA section 107(d)(3)(E), which governs redesignations from nonattainment to attainment. 14

The San Joaquin Valley 1979 ozone area encompasses over 23,000 square miles and includes eight counties: San Joaquin, Stanislaus, Merced, Madera, Fresno, Tulare, Kings, and Kern. 15 The area is home to four million people and is one of the nation's leading agricultural regions. Stretching over 250 miles from north to south and averaging 80 miles wide, it is partially enclosed by the Coast Mountain range to the west, the Tehachapi Mountains to the south, and the Sierra Nevada range to the east. Under state law, the San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD or the “District”) has primary responsibility for developing plans to provide for attainment of the NAAQS in this area. The District works cooperatively with the California Air Resources Board (CARB) in preparing attainment plans. Authority for regulating sources under state jurisdiction in the San Joaquin Valley is split under state law between the District, which generally has responsibility for regulating stationary and area sources, and CARB, which generally has responsibility for regulating mobile sources.

The CAA, as amended in 1977, required states to submit SIP revisions for nonattainment areas that, among other requirements, provided for attainment of the 1979 ozone NAAQS no later than 1987; however, like many areas of the country, the San Joaquin Valley failed to attain the 1979 ozone NAAQS by 1987. In the 1990 CAA Amendments, Congress established a classification system for ozone nonattainment areas under which areas with more severe ozone problems were given a higher classification and more time to attain the standard but were subject to a greater number of, and more stringent, SIP requirements. The classifications include “Marginal,” “Moderate,” “Serious,” “Severe,” and “Extreme.”  16 Effective January 22, 1992, the EPA established the initial air quality designations for most areas in the United States for the 1979 ozone NAAQS. 17 The EPA designated the San Joaquin Valley area as Serious nonattainment based on monitoring data from 1987 to 1989. 18 Areas classified as Serious were required to attain the NAAQS by November 15, 1999. 19 In response, in 1994, CARB submitted The California Ozone State Implementation Plan (“1994 California Ozone Plan”), a comprehensive ozone plan for the State of California that included a state strategy as well as certain regional ozone plans, such as the regional plan for the San Joaquin Valley. On January 8, 1997, the EPA approved the 1994 California Ozone Plan, which projected attainment by November 15, 1999. 20

On November 8, 2001, the EPA found that the San Joaquin Valley area did not attain the 1979 ozone NAAQS by the November 15, 1999 deadline, and the San Joaquin Valley area was reclassified by operation of law as “Severe-15”  21 nonattainment based on monitoring data from 1997 to 1999. 22 As a result, the State of California was required to submit a Severe area ozone nonattainment plan by May 31, 2002, that provided for attainment as expeditiously as practicable, but no later than November 15, 2005.

On April 16, 2004, the EPA granted a request by the State of California to voluntarily change the San Joaquin Valley nonattainment area's classification for the 1979 ozone NAAQS from Severe to Extreme and required the State to submit an Extreme area plan by November 15, 2004, that provided for attainment as expeditiously as practicable, but no later than November 15, 2010. 23 CARB submitted an Extreme area plan on November 15, 2004 (“2004 Ozone Plan”). CARB subsequently amended it and resubmitted it on March 6, 2006. On March 8, 2010, the EPA approved California's 2004 Ozone Plan as amended and clarified. 24 Our approval of the 2004 Ozone Plan was challenged, and the U.S. Court of Appeals for the Ninth Circuit remanded the approval of the plan to the EPA based on its conclusion that the EPA had not adequately considered and addressed the implications of recent emissions data (“ Sierra Club ”). 25 In response to the Sierra Club decision, the EPA withdrew its approval of the 2004 Ozone Plan. 26 Because of approvability concerns raised in the Sierra Club decision, CARB withdrew the plan effective at the time the EPA finalized its withdrawal of approval. Consequently, the EPA also issued a finding of failure to submit required SIP revisions to provide for attainment of the 1-hour ozone NAAQS in the San Joaquin Valley.

Meanwhile, as noted in section I.A. of this document, in 1997, the EPA established an 8-hour ozone standard to replace the 1-hour ozone standard, and in 2004, the EPA designated the San Joaquin Valley as a Serious nonattainment area for the 1997 8-hour ozone standard. 27 In 2010, the EPA approved a request by CARB to reclassify the San Joaquin Valley as Extreme for the 1997 8-hour ozone standard. 28

On December 30, 2011, the EPA determined that the San Joaquin Valley did not attain the 1-hour ozone standard by the November 15, 2010 attainment date based on monitoring data from 2008 to 2010. 29 In November 2012, the EPA established November 26, 2017, as the new attainment deadline for the San Joaquin Valley for the 1979 ozone NAAQS. 30

On December 20, 2013, California submitted the 2013 Plan for the Revoked 1-Hour Standard (“2013 Ozone Plan”). On April 5, 2016, the EPA approved the following elements of the 2013 Ozone Plan: the base year and projected future year emissions inventories, reasonably available control measures (RACM) demonstration, rate of progress (ROP) demonstration, attainment demonstration, Clean Fuel for Boilers (CFB) rule adoption, vehicle miles traveled (VMT) offset requirement, and contingency measures for failure to meet ROP milestones for the area. 31

On July 18, 2016, the EPA determined that the San Joaquin Valley area attained the 1979 ozone NAAQS based on three years of complete, quality-assured, and certified data for the 2012-2014 time period, and we issued a “clean data determination.”  32 Citing 40 CFR 51.1118, the EPA also stated that, to the extent such requirements were not already fulfilled, the clean data determination would suspend requirements to submit attainment demonstrations and associated RACM, reasonable further progress plans, contingency measures for failure to attain or make reasonable progress, and other requirements related to attainment of the 1-hour ozone standard for so long as the area continues to attain the standard, or until such time as the area is redesignated as attainment for the current ozone NAAQS, or a redesignation substitute for the 1-hour ozone standard is approved, at which time the requirements no longer apply. 33

The CAA establishes the criteria that must be met for the EPA to redesignate a nonattainment area to attainment for a given NAAQS. Specifically, section 107(d)(3)(E) sets forth the following criteria: (1) the EPA must determine that the area has attained the applicable NAAQS; (2) the EPA must have fully approved the applicable SIP for the area under CAA section 100(k); (3) the EPA must determine that the improvement in air quality is due to permanent and enforceable reductions in emissions; (4) the EPA must have fully approved a maintenance plan for the area as meeting the requirements of CAA section 175A; and, (5) the state must have met all requirements applicable to the area under section 110 and title I, part D, (“part D”) of the CAA. Section 110 identifies a comprehensive list of elements that must be included in SIPs, and part D establishes the SIP requirements for nonattainment areas. Part D is divided into six subparts. The generally applicable SIP requirements for nonattainment areas are found in subpart 1 of part D, and the ozone-specific SIP requirements are found in subpart 2 of part D. The EPA provided guidance on redesignations in a document titled “State Implementation Plans; General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990,” published in the Federal Register on April 16, 1992, 34 and supplemented on April 28, 1992 (collectively referred to herein as the “General Preamble”). 35 The EPA issued additional guidance in two memoranda: a September 4, 1992 memorandum from John Calcagni, Director of the EPA's Air Quality Management Division in the Office of Air Quality Planning and Standards, titled “Procedures for Processing Requests to Redesignate Areas to Attainment” (referred to herein as the “Calcagni memo”) and a 1995 memorandum from Mary D. Nichols, titled “Part D New Source Review (part D NSR) Requirements for Areas Requesting Redesignation to Attainment” (“Nichols memo”).

The EPA's approval of a state's maintenance plan is one of the CAA prerequisites for redesignation of a nonattainment area to attainment under CAA section 107(d)(3)(E). Section 175A of the CAA provides the general framework for a state's maintenance plans. A state's initial 10-year maintenance plan must provide for maintenance of the NAAQS for at least 10 years after redesignation and include any additional control measures necessary to ensure such maintenance. In addition, maintenance plans must contain contingency provisions necessary to assure the prompt correction of a violation of the NAAQS during the maintenance period. At a minimum, these contingency provisions must include a requirement that a state will implement all control measures contained in the nonattainment SIP prior to redesignation. Because a state's maintenance plan submittals are SIP revisions, the EPA is obligated under CAA section 110(k) to approve them or disapprove them depending on whether they meet the applicable CAA requirements for such plans outlined above.

For the reasons described in section III of this proposal, the EPA is proposing to find that California's submittal meets all five criteria in CAA section 107(d)(3)(E) for the 1-hour ozone NAAQS. The EPA is also proposing to approve the San Joaquin Valley Maintenance Plan for the 1979 ozone NAAQS as consistent with CAA section 175A. Although CAA section 107(d)(3) applies explicitly only to revisions of area designations and the designations for this area have been revoked along with the NAAQS, the EPA's view is that, consistent with the U.S. Court of Appeals for the District of Columbia Circuit's findings in South Coast II, satisfaction of the statutory redesignation criteria permits the termination of any remaining anti-backsliding obligations for the San Joaquin Valley area as to the revoked 1979 ozone NAAQS. The EPA is therefore proposing to terminate the anti-backsliding obligations for the San Joaquin Valley area associated with the 1-hour ozone NAAQS and to revise the table in 40 CFR part 81 to reflect that the San Joaquin Valley area has attained the revoked 1979 ozone NAAQS and that all anti-backsliding obligations for that NAAQS are terminated.

On July 21, 2023, CARB submitted to the EPA its redesignation request and maintenance plan for the San Joaquin Valley area for the 1979 ozone NAAQS as a revision to the California SIP. 36 This document addresses all of the CAA section 107(d)(3)(E) redesignation criteria and includes the required maintenance plan elements. The San Joaquin Valley Maintenance Plan is organized into seven chapters and two appendices. The first appendix (Appendix A) provides the emissions inventory, and the second appendix (Appendix B) provides support for meteorological conditions affecting ozone levels in the San Joaquin Valley. On February 27, 2024, SJVUAPCD submitted information clarifying the contingency plan in section F.5 of the San Joaquin Valley Maintenance Plan;  37 on July 1, 2024, CARB submitted information supplementing the emissions inventory in Appendix A;  38 and on August 22, 2024, CARB submitted information amending the maintenance demonstration in section F.2 of the San Joaquin Valley Maintenance Plan. 39 Collectively, we refer to this as the “San Joaquin Valley Maintenance Plan” or “Plan.”

CAA sections 110(a) and 110(l) require states to provide reasonable public notice and opportunity for public hearing prior to adoption and submission of a SIP or SIP revision. To meet these procedural requirements, every SIP submission should include evidence that the state provided adequate public notice and an opportunity for a public hearing, consistent with the EPA's implementing regulations in 40 CFR 51.102.

CARB's July 21, 2023 SIP submittal package includes documentation of the public process used by the District to adopt the San Joaquin Valley Maintenance Plan. 40 On May 16, 2023, SJVUAPCD released a draft version of the Plan for public review and published a notice of public meeting to be held on June 15, 2023, to consider adoption of the San Joaquin Valley Maintenance Plan. As documented in SJVUAPCD Resolution No. 2023-6-9, included in the SIP submittal package, the Governing Board of the SJVUAPCD adopted the San Joaquin Valley Maintenance Plan on June 15, 2023, following a public hearing. 41 As evidenced by CARB Executive Order S-23-013, CARB adopted the San Joaquin Valley Maintenance Plan on July 19, 2023. 42 Based on the documentation in the July 21, 2023 SIP submittal package, SJVUAPCD has satisfied the applicable statutory and regulatory requirements for reasonable public notice and hearing prior to adoption and submission of the Plan. Therefore, the submission of the San Joaquin Valley Maintenance Plan meets the procedural requirements for public notice and hearing in CAA sections 110(a) and 110(l) and in 40 CFR 51.102.

On January 21, 2024, the San Joaquin Valley Maintenance Plan submittal became complete by operation of law pursuant to CAA section 110(k)(1)(B).

Pursuant to section 107(d)(3)(E)(i) of the CAA, for a nonattainment area to be redesignated to attainment, the EPA must determine that the area has attained the relevant NAAQS. The EPA interprets this requirement to mean that the area must have an attaining design value based on the most recently available and quality-assured air quality monitoring data, collected in accordance with the requirements of 40 CFR part 58. 44 These requirements include quality assurance procedures for monitor operation and data handling, siting parameters for instruments or instrument probes, and minimum ambient air quality monitoring network requirements. 45 State, local, or tribal agencies that operate air monitoring sites in accordance with 40 CFR part 58 must enter the ambient air quality data from these sites in the EPA Air Quality System (AQS) database. 46 These monitoring agencies certify annually that these data are accurate to the best of their knowledge, taking into consideration the quality assurance findings. 47 Accordingly, the EPA relies primarily on AQS data when determining the attainment status of an area.

In accordance with 40 CFR part 58 and 40 CFR part 50, appendix H, generally, the EPA's finding of attainment for the 1979 ozone NAAQS must be based upon complete, quality-assured, certified data gathered at eligible monitoring sites in the nonattainment area in accordance with 40 CFR part 58 and entered into AQS. 48 Under 40 CFR 50.9 and in accordance with part 50, appendix H, an area meets the 1979 ozone NAAQS when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is equal to or less than 1, averaged over a three year period. 49 A daily maximum ozone value is considered valid if 75 percent of the hours from 9:01 a.m. to 9:00 p.m. were measured or if the highest hour is greater than the level of the standard. 50 A missing daily maximum ozone value may be assumed to be less than the level of the standard if the valid daily maxima on both the preceding day and the following day do not exceed 75 percent of the NAAQS.

SJVUAPCD is the governmental agency with the authority and responsibilities under state law for collecting ambient air quality data in the San Joaquin Valley area. The ambient air monitoring network in the San Joaquin Valley area also includes air monitoring stations that are managed and operated by CARB and the National Park Service (NPS). As a result, SJVUAPCD submits annual monitoring network plans to the EPA. 51 These plans document the status of SJVUAPCD's air monitoring network including the CARB and NPS air monitoring stations, as required under 40 CFR 58.10. The EPA reviews these annual network plans for compliance with the specific requirements in 40 CFR part 58. With respect to ozone, we have found that the annual network plans submitted by SJVUAPCD meet these requirements under 40 CFR part 58, including the minimum monitoring requirements. 52 See Table 1 for a summary of air quality ozone monitors in the San Joaquin Valley area. 53

In accordance with 40 CFR 58.15, SJVUAPCD, CARB, and the NPS certify annually that the previous calendar year's ambient concentration and quality assurance data are completely submitted to AQS and that the ambient concentration data are accurate, taking into consideration the quality assurance findings. 54 Along with the certification letters, SJVUAPCD, CARB, and the NPS submit a summary of the precision and accuracy data for all ambient air quality data. 55 The EPA's evaluations of the relevant quality assurance data are reflected in the associated AQS certification evaluation and concurrence reports. 56 For the purposes of this proposal, we reviewed the data for the 2021-2023 period for completeness and determined that the ozone ambient concentration data collected in the San Joaquin Valley area met the completeness criterion at all ozone monitoring sites except for those specified in Table 2. 57

Finally, the EPA conducts regular technical systems audits (TSAs) where we review and inspect state and local ambient air monitoring programs to assess compliance with applicable regulations concerning the collection, analysis, validation, and reporting of ambient air quality data. For the purposes of this proposal, we reviewed the findings from EPA's 2022 TSAs of CARB and SJVUAPCD's ambient air monitoring programs. 58 The results of these TSAs do not preclude the EPA from determining that the area has attained the 1979 1-hour ozone NAAQS.

To summarize, based on the EPA's review of the 2021-2023 certified data available in AQS, relevant monitoring network plans, certifications, quality assurance data, and the 2022 TSAs, we propose to find that the ozone data collected in the San Joaquin Valley area are suitable for determining whether the area has attained the 1979 1-hour ozone NAAQS.

In 2016, the EPA determined that the San Joaquin Valley area attained the 1979 ozone NAAQS based on monitoring data from 2012-2014. 59 The San Joaquin Valley continues to attain the NAAQS. Table 2 shows the calculated 1979 1-hour ozone design values at all monitoring sites in the San Joaquin Valley area for the 2020-2022 and 2021-2023 periods. 60 The data show that all of the monitoring sites in the San Joaquin Valley area met the 1-hour ozone NAAQS in the 2020-2022 and 2021-2023 periods, based on the average expected exceedances at all monitoring sites being less than or equal to 1 exceedance per year. Preliminary data available in AQS for 2024 indicate that the San Joaquin Valley area continues to show concentrations below the level of the 1979 1-hour ozone NAAQS. 61

As indicated in Table 2, the 2022 design values for Maricopa and Arvin-DiGiorgio are invalid and the 2023 design value for Hanford is invalid. For the 2022 design value period, the Maricopa site did not meet the 3-year completeness criterion of 90%. Also, for the 2022 design value period, the Arvin-DiGiorgio site did not meet the 3-year completeness criterion of 90% and calendar year 2020 did not meet the annual completeness criterion of 75%. For the 2023 design value period, the Hanford site did not meet the 3-year completeness criterion of 90% and calendar year 2023 did not meet the annual completeness criterion of 75%. While these design values were invalid, these sites were not historically the highest design value sites in the San Joaquin Valley area. 62 Thus, we find that invalid design values from the Maricopa, Arvin-DiGiorgio, and Hanford sites do not preclude an attainment determination for the San Joaquin Valley.

Consequently, based upon three years of complete, quality-assured, and certified data from 2021-2023, the EPA proposes to determine that the San Joaquin Valley area has attained and continues to attain the 1979 ozone NAAQS.

Sections 107(d)(3)(E)(ii) and (v) of the CAA require the state to have met all applicable requirements under section 110 and part D and the EPA to have fully approved that applicable SIP under CAA section 110(k).

Section 110(a)(2) of the CAA contains the general requirements for a SIP. Section 110(a)(2) provides that the SIP must have been adopted by the state after reasonable public notice and hearing, and that, among other things, it must: (1) include enforceable emission limitations and other control measures, means or techniques necessary to meet the requirements of the CAA; (2) provide for establishment and operation of appropriate devices, methods, systems and procedures necessary to monitor ambient air quality; (3) provide for implementation of a source permit program to regulate the modification and construction of stationary sources within the areas covered by the plan; (4) include provisions for the implementation of part C prevention of significant deterioration (PSD) and part D new source review (NSR) permit programs; (5) include provisions for stationary source emission control measures, monitoring, and reporting; (6) include provisions for air quality modeling; and, (7) provide for public planning and emission control rule development.

Part D of the Clean Air Act establishes the plan requirements for nonattainment areas. Section 172(c) sets forth the basic requirements of air quality plans for states with nonattainment areas that are required to submit plans on a schedule pursuant to section 172(b). Subpart 2 of part D, which includes section 182 of the CAA, establishes specific requirements for ozone nonattainment areas depending on the areas' nonattainment classifications. The San Joaquin Valley area was classified as Extreme under the 1979 ozone NAAQS. Therefore, the area is subject to the subpart 1 requirements contained in section 172(c) and section 176. The area is also subject to the subpart 2 requirements contained in section 182(e) (Extreme nonattainment area requirements). A thorough discussion of the requirements contained in section 172(c) and 182 can be found in the General Preamble for Implementation of Title I. 63

Since Congress passed the CAA amendments in 1990, the EPA has consistently held the position that not every requirement that an area is subject to is applicable for purposes of redesignation. 64 For example, some of the part D requirements, such as demonstrations of reasonable further progress, are designed to ensure that nonattainment areas continue to make progress toward attainment. The EPA has interpreted these requirements as not “applicable” for purposes of redesignation under CAA section 107(d)(3)(E)(ii) and (v) because areas that are applying for redesignation to attainment are by definition already attaining the standard. Similarly, the EPA has long held that CAA provisions that are not relevant to an area's designation and classification as a nonattainment area are not “applicable” for purposes of redesignation under CAA section 107(d)(3)(E)(ii) and (v). For this reason, SIP revisions that apply regardless of whether an area is designated nonattainment or attainment, such as good neighbor plans required under CAA section 110(a)(2)(D)(i)(I), have not been considered “applicable” for purposes of redesignation. Finally, some requirements may not be applicable in this action given that both of the NAAQS at issue in this notice were revoked for all purposes, and, post-revocation, the San Joaquin Valley area remained subject only to the anti-backsliding requirements identified by the EPA in regulation. 65

However, for the revoked ozone standard at issue here, over the past three decades the State has submitted numerous SIPs for the San Joaquin Valley area to implement the standard, improve air quality with respect to the standard, and to address anti-backsliding requirements for the standard. Therefore, even though some of the San Joaquin Valley area's SIP-approved elements address criteria that are not requirements “applicable” for purposes of redesignation under CAA section 107(d)(3)(E)(ii) and (v), such as CAA section 182(b) reasonable further progress, or address requirements that were not retained for anti-backsliding, such as section 182(a) emissions inventories, we provide a list of elements the State has adopted and the EPA has fully approved for the San Joaquin Valley area with respect to the revoked 1-hour ozone standard. These include: (1) emissions inventories, (2) a RACM demonstration, (3) an attainment demonstration, (4) a rate of progress demonstration, (5) contingency measures for failure to meet rate of progress milestones, (6) advanced technology or clean fuels for boilers, (7) VMT offset demonstration and transportation control measures, 66 (8) reasonably available control technology (RACT), 67 (9) both basic and enhanced vehicle inspection and maintenance programs, 68 (10) nonattainment new source review (NSR) programs with NSR offset requirements, 69 and (11) a CAA section 185 fee program. 70 Because the requirements for infrastructure SIPs in section 110(a)(2) were not part of the CAA until the 1990 amendments, SJVUAPCD has not submitted SIPs addressing section 110(a)(2) elements for the 1979 ozone NAAQS. 71

Therefore, we are proposing to find That the San Joaquin Valley area has met all requirements under CAA section 110 and part D and that the Plan satisfies CAA sections 107(d)(3)(E)(ii) and (v).

To approve a request for redesignation to attainment, CAA section 107(d)(3)(E)(iii) requires the EPA to determine that the improvement in air quality is due to emission reductions that are permanent and enforceable and that the improvement results from the implementation of the applicable SIP, applicable Federal air pollution control regulations, and other permanent and enforceable regulations. Under this criterion, a state must be able to reasonably attribute the improvement in air quality to permanent and enforceable emission reductions. Attainment resulting from temporary reductions in emission rates ( e.g., reduced production or shutdown due to temporary adverse economic conditions) or unusually favorable meteorology would not qualify as an air quality improvement due to permanent and enforceable emission reductions. 72

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

The EPA is updating the delegation of the implementation and enforcement of certain NSPS to LDEQ. EPA is also proposing to approve the delegation of the implementation and enforcement of certain NESHAP to LDEQ. If finalized, the delegation will provide LDEQ with the primary responsibility to implement and enforce the delegated standards.

Section 111(c)(1) of the Clean Air Act (CAA) authorizes EPA to delegate authority to any State agency which submits adequate regulatory procedures for implementation and enforcement of the NSPS program. The NSPS standards are codified at 40 CFR part 60.

Section 112(l) of the Clean Air Act (CAA), and 40 CFR part 63, subpart E, authorize the EPA to delegate authority to any State or local agency which submits adequate regulatory procedures for implementation and enforcement of emission standards for hazardous air pollutants. The hazardous air pollutant standards are codified at 40 CFR parts 61 and 63.

In order to receive delegation of NSPS, a State must develop and submit to the EPA a procedure for implementing and enforcing the NSPS in the State, and their regulations and resources must be adequate for the implementation and enforcement of the NSPS. EPA initially approved Louisiana's program for the delegation of NSPS on February 22, 1982 (47 FR 7665). EPA reviewed the laws of the State and the rules and regulations of the Louisiana Department of Natural Resources (now the LDEQ) and determined the State's procedures, regulations and resources adequate for the implementation and enforcement of the NSPS program. This action notifies the public that EPA is updating LDEQ's delegation to implement and enforce certain additional NSPS.

As to the NESHAP standards in 40 CFR parts 61 and 63, Section 112(l)(5) of the CAA requires the EPA to disapprove any program submitted by a State for the delegation of NESHAP standards if the EPA determines that:

(A) the authorities contained in the program are not adequate to assure compliance by the sources within the State with respect to each applicable standard, regulation, or requirement established under section 112;

(B) adequate authority does not exist, or adequate resources are not available, to implement the program;

(C) the schedule for implementing the program and assuring compliance by affected sources is not sufficiently expeditious; or

(D) the program is otherwise not in compliance with the guidance issued by the EPA under section 112(l)(2) or is not likely to satisfy, in whole or in part, the objectives of the CAA.

In carrying out its responsibilities under section 112(l), the EPA promulgated regulations at 40 CFR part 63, subpart E, setting forth criteria for the approval of submitted programs. For example, in order to obtain approval of a program to implement and enforce Federal section 112 rules as promulgated without changes (straight delegation) for part 70 sources, a State must demonstrate that it meets the criteria of 40 CFR 63.91(d). 40 CFR 63.91(d)(3) provides that interim or final Title V program approval will satisfy the criteria of 40 CFR 63.91(d). 1 The NESHAP delegation for Louisiana, as it applies to both part 70 and non-part 70 sources, was most recently approved on February 24, 2015 (80 FR 9613).

Executive Summary

In accordance with the Marine Mammal Protection Act of 1972 (16 U.S.C. 1371(a)(5)(A)) and its implementing regulations, we, the U.S. Fish and Wildlife Service (hereafter FWS or we), propose incidental take regulations that, if finalized, would allow through Letters of Authorization (LOAs) the nonlethal, incidental, unintentional take of small numbers of northern sea otters ( Enhydra lutris kenyoni ) during pile driving and marine construction in Seward, Sitka, and Kodiak, Alaska. If finalized, the rule would be effective for 5 years from the date of issuance.

This proposed rule is based on our preliminary findings that the total takings of sea otters during specified activities will impact small numbers of animals, will have a negligible impact on this species or stocks, and will not have an unmitigable adverse impact on the availability of northern sea otters for subsistence use by Alaska Natives. We base our preliminary findings on the best available scientific evidence, including but not limited to, data from monitoring the encounters and interactions between sea otters and pile driving and marine construction activities; research on northern sea otters; potential and documented effects on this species from similar activities; information regarding the natural history and conservation status of sea otters; and data reported from Alaska Native subsistence hunters. In conjunction with this proposed rulemaking, we have prepared a draft environmental assessment, which is also available for public review and comment.

The proposed regulations include permissible methods of nonlethal taking; mitigation measures to ensure that the activities of the U.S. Coast Guard (USCG) will have the least practicable adverse impact on the northern sea otters, their habitat, and the availability of this species for subsistence uses; and requirements for monitoring and reporting. Compliance with this rule, if finalized, is not expected to result in significant additional costs to the applicant, and any costs are minimal in comparison to those related to actual pile driving and marine construction activities.

Section 101(a)(5)(A) of the Marine Mammal Protection Act (MMPA) (16 U.S.C. 1371(a)(5)(A)) gives the Secretary of the Interior (Secretary) the authority to allow the incidental, but not intentional, taking of small numbers of certain marine mammals, in response to requests by U.S. citizens (as defined in title 50 of the Code of Federal Regulations (CFR) in part 18 (at 50 CFR 18.27(c)) engaged in a specified activity (other than commercial fishing) within a specified geographic region. The Secretary has delegated authority for implementation of the MMPA to the FWS. According to the MMPA, the FWS shall allow this incidental taking for a period of up to 5 consecutive years if we find that the total of such taking:

(1) will affect only small numbers of individuals of the species or stock;

(2) will have no more than a negligible impact on the species or stock; and

(3) will not have an unmitigable adverse impact on the availability of the species or stock for taking for subsistence use by Alaska Natives.

If the requisite findings are made, we issue regulations that set forth the following, where applicable:

(a) permissible methods of taking;

(b) means of effecting the least practicable adverse impact on the species or stock and its habitat and the availability of the species or stock for subsistence uses; and

(c) requirements for monitoring and reporting of such taking.

If final regulations allowing such incidental take are issued, we may then subsequently issue letters of authorization (LOA), upon request, to authorize incidental take during the specified activities.

The term “take” means to “harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill any marine mammal” (16 U.S.C. 1362(13)). Harassment for activities other than military readiness activities or scientific research conducted by or on behalf of the Federal Government means any act of pursuit, torment, or annoyance that has the potential to injure a marine mammal or marine mammal stock in the wild (the MMPA defines this as Level A harassment), or has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (the MMPA defines this as Level B harassment) (16 U.S.C. 1362(18)).

The terms “negligible impact” and “unmitigable adverse impact” are defined in 50 CFR 18.27(c) ( i.e., regulations governing small takes of marine mammals incidental to specified activities) as follows: “Negligible impact” is an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival. “Unmitigable adverse impact” means an impact resulting from the specified activity: (1) that is likely to reduce the availability of the species to a level insufficient for a harvest to meet subsistence needs by (i) causing the marine mammals to abandon or avoid hunting areas, (ii) directly displacing subsistence users, or (iii) placing physical barriers between the marine mammals and the subsistence hunters; and (2) that cannot be sufficiently mitigated by other measures to increase the availability of marine mammals to allow subsistence needs to be met.

The term “small numbers” is also defined in 50 CFR 18.27(c). However, we do not rely on that definition here as it conflates “small numbers” with “negligible impact.” We recognize “small numbers” and “negligible impacts as two separate and distinct requirements for promulgating incidental take regulations (ITR) under the MMPA (see Natural Res. Def. Council, Inc. v. Evans, 232 F. Supp. 2d 1003, 1025 (N.D. Cal. 2003)). Instead, for our small numbers determination, we estimate the likely number of marine mammals to be taken and evaluate if that take is small relative to the size of the species or stock.

The term “least practicable adverse impact” is not defined in the MMPA or its enacting regulations. In promulgating ITRs, we ensure the least practicable adverse impact by requiring mitigation measures that are effective in reducing the impact of specified activities, but they are not so restrictive as to make specified activities unduly burdensome or impossible to undertake and complete.

The USCG's activities may result in the incidental taking of sea otters. The MMPA does not require that the USCG must obtain incidental take authorization prior to conducting these activities; however, any incidental taking that occurs without authorization is a violation of the MMPA. An ITR was issued to the USCG for pile driving and marine construction activities at multiple locations in Alaska including Seward, Sitka, and Kodiak from May 19, 2023, through May 19, 2028 (88 FR 24115, April 19, 2023). The specified activities described in this proposed ITR are outside the scope of the 2023-2028 USCG ITR, and, therefore, the USCG submitted requests for the incidental take of sea otters during their planned activities.

On March 5, 2024, the FWS received a request prepared by Weston Solutions on behalf of the U.S. Coast Guard (hereafter, USCG or the applicant) for the nonlethal, incidental harassment of small numbers of northern sea otters ( Enhydra lutris kenyoni ) (hereafter, sea otters unless another sea otter subspecies is specified) from the Southwest Alaska stock that may occur during pile driving and marine construction activities in Womens Bay, Kodiak, Alaska. During discussion with the applicant, a request prepared by WSP Environment and Infrastructure on behalf of the USCG (received January 19, 2024) for the nonlethal, incidental harassment of small numbers of sea otters from the Southcentral Alaska stock that may occur during pile driving and marine construction activities in Seward was combined with the USCG's request prepared by Weston Solutions. Additionally, a request prepared by WSP Environment and Infrastructure on behalf of the USCG (received January 19, 2024) for the nonlethal, incidental harassment of small numbers of sea otters from the Southeast Alaska stock that may occur during pile driving and marine construction activities in Sitka was then merged with the USCG's combined request. The USCG provided additional information regarding project activities, timelines, and mitigation measures for their planned activities in Kodiak, Seward, and Sitka requested by the FWS during correspondence. On October 2, 2024, the FWS received a revised application for activities in Kodiak (hereafter referred to as “Weston Solutions 2024 Request”). On October 3, 2024, the FWS received a revised application for activities in Seward and Sitka (hereafter referred to as “WSP Environment and Infrastructure 2024 Request”). The FWS determined USCG's combined request for activities in Kodiak, Seward, and Sitka to be adequate and complete on October 3, 2024.

The applicant expects take by harassment may occur during pile driving and marine construction activities at three facilities in Alaska: the USCG Moorings Seward in Seward; the USCG Moorings Sitka in Sitka; and the USCG Base Kodiak near Kodiak. These improvements are needed to support the commission, temporary and permanent homeporting, and berthing of Fast Response Cutters (FRCs) at all three facilities and Offshore Patrol Cutters (OPC) at Kodiak. Hereafter (unless otherwise specified), the terms “pile driving” and “pile-driving activities” are used to refer to both pile installation and pile removal.

The proposed regulations, if finalized, would allow through LOAs the authorization of nonlethal, incidental, unintentional take of small numbers of sea otters that may result from the specified activities based on standards set forth in the MMPA. They would not authorize or “permit” the activities being conducted by the USCG, only the incidental take of sea otters that may result from those activities. The proposed regulations include:

(1) Permissible methods of nonlethal taking;

(2) Measures designed to ensure the least practicable adverse impact on sea otters and their habitat, and on the availability of this species or stock for subsistence uses; and

(3) Requirements for monitoring and reporting.

An LOA is required to conduct activities pursuant to an ITR. Under this proposed ITR, if finalized, the applicant may request an LOA for the authorized nonlethal, incidental Level B and Level A harassment of sea otters incidental to the specific activities described in these proposed regulations. Per the applicant's request, such entities would be limited to the USCG and their subcontractors. Requests for LOAs must be consistent with the activity descriptions and mitigation and monitoring requirements of the ITR and be received in writing at least 30 days before the activity is to begin. Requests must include (1) an operational plan for the activity, including the number of days of work and the nature of work to be conducted; (2) a digital geospatial file of the project footprint; (3) a site-specific marine mammal monitoring and mitigation plan that specifies the procedures to monitor and mitigate the effects of the activities on sea otters; and (4) Plans of Cooperation (if required as described below). Once this information has been received, we will evaluate each request and issue the LOA for up to a 1-year period if we find that the level of taking will be consistent with the findings made for the total taking allowable under the ITR. Requests for LOAs may be submitted on an annual basis for additional years of activities within the ITR period. We must receive an after-action report on the monitoring and mitigation activities within 90 days after the LOA expires. For more information on requesting and receiving an LOA, refer to 50 CFR 18.27(f).

A POC is a documented plan describing measures to mitigate potential conflicts between specified activities and Alaska Native subsistence hunting. The circumstances under which a POC must be developed and submitted with a request for an LOA are described below.

To help ensure that specified activities do not have an unmitigable adverse impact on the availability of the species for Alaska Native subsistence hunting opportunities, all applicants requesting an LOA under this ITR must provide the FWS documentation of communication and coordination with Alaska Native communities potentially affected by the specified activity and, as appropriate, with representative subsistence hunting and co-management organizations. If Alaska Native communities or representative subsistence hunting organizations express concerns about the potential impacts of specified activities on subsistence activities, and such concerns are not resolved during this initial communication and coordination process, then a POC must be developed and submitted with the applicant's request for an LOA. In developing the POC, the USCG will further engage with Alaska Native communities and/or representative subsistence hunting organizations to provide information and respond to questions and concerns. The POC must provide adequate measures to ensure that specified activities will not have an unmitigable adverse impact on the availability of sea otters for Alaska Native subsistence uses.

The specified geographic region includes Gulf of Alaska coastal waters of three USCG facilities. The specified activities would occur in the waters and intertidal areas of the eastern shore of Resurrection Bay, Alaska, surrounding the USCG Moorings Seward, the waters and intertidal areas of Sitka Channel, Alaska, surrounding the USCG Moorings Sitka, and the waters and intertidal areas of Womens Bay, Kodiak, Alaska, which surround the USCG Base Kodiak located on the Nyman Peninsula (figure 1).

Three pile driving and marine construction projects would occur within the specified geographic region: Moorings Seward, Moorings Sitka, and Base Kodiak. Brief summaries of each project are provided below, and additional project details for each project may be reviewed in the application materials available as described under ADDRESSES or may also be requested as described under FOR FURTHER INFORMATION CONTACT .

The specified activity (hereafter project) in Seward will include installation and removal of piles for the construction of shoreside facilities and associated infrastructure at the USCG Moorings Seward in the Seward Marine Industrial Center (SMIC) to homeport 1 FRC. The project entails construction of a new floating dock parallel to the existing SMIC dock and reconfiguration of the SMIC floating dock to allow for construction of the FRC moorings. For the reconfiguration of the SMIC floating dock, project activities include the removal of up to 10 existing steel guide piles that are no greater than 40.6 centimeters (cm; 16 inches (in)) in diameter and the installation of up to 10 new concrete or steel pipe guide piles that are 76.2 cm (30 in) in diameter. Construction of the new dock includes installation of up to 20 concrete or steel pipe guide piles that are no greater than 76.2 cm (30 in) in diameter. In-water project activities are summarized in table 1. After the dock is installed, ancillary infrastructure ( i.e., electricity, water, sewage) to service the docked FRC will be installed. Pile-driving activities will occur over 22 non-consecutive days for approximately 105 hours. Pile removal will be done with vibratory extraction or cutting at the mud line with a pile clipper or diamond saw. Pile installation will be done with a combination of rock socket down-the-hole (DTH) drilling, impact proofing, and vibratory settling.

The USCG plans to remove a mooring dolphin supported by four concrete piles, each of which is 61.0 cm (24 in) in diameter, and a float supported by six timber piles, each of which is 35.6 cm (14 in) in diameter. To support the pier, floating dock, and mooring dolphins, the USCG plans to install 118 concrete piles, each of which will be 76.2 cm (30 in) in diameter; 54 plastic piles, each of which will be 33.0 cm (13 in) in diameter; and 6 timber piles, each of which will be 35.6 cm (14 in) in diameter. Pile-driving activities will occur over 117 non-consecutive days. Pile installation will be done with a combination of impact pile driving, vibratory pile driving, and DTH drilling. Temporary and existing piles will be removed by the dead-pull method (a direct lift of the pile using a crane with no vibration), a pile clipper, a diamond saw, or a vibratory hammer. In-water activities are summarized in table 2.

The USCG will implement in-water and waterfront improvements at the USCG Base Kodiak to support the commission, temporary and permanent homeporting, and berthing of FRCs and OPCs. In-water improvements will consist of replacing and extending existing wharfs, installing floating docks and camel logs, installing a solid-fill approach bulkhead, and refurbishing small craft floats. In-water activities will include impact pile driving of steel piles and concrete fender piles, vibratory installation and extraction of timber piles, steel piles, steel/concrete piles, concrete piles, and vibroflot columns, and DTH drilling of steel piles. These activities are anticipated to occur over 339 non-consecutive days from 2 to 5 years. A total of 501 piles of various sizes and types will be removed throughout the project. A total of 918 piles of various sizes and types will be installed throughout the project. In-water activities are summarized in table 3.

There are three sea otter stocks in Alaska: the Southeast Alaska stock, the Southcentral Alaska stock, and the Southwest Alaska stock. All three Alaskan sea otter stocks are present in the project area. Sea otters at the USCG Moorings Seward belong to the Southcentral Alaska stock. Sea otters at Moorings Sitka belong to the Southeast Alaska stock. Sea otters at the USCG Base Kodiak belong to the Southwest Alaska stock. Detailed information about the biology of these stocks can be found in the most recent stock assessment reports (88 FR 53510, August 8, 2023), which can be found at https://fws.gov/project/marine-mammal-stock-assessment-reports. Additionally, the Southwest Alaska stock of sea otters is listed as threatened under the Endangered Species Act (ESA; 16 U.S.C. 1531 et seq. ) at 50 CFR 17.11(h) (70 FR 46366; August 9, 2005). Further information on the Southwest Alaska stock is available in the FWS's species status assessment available at: https://ecos.fws.gov/ecp/species/2884.

Northern sea otters occur in nearshore coastal waters from Alaska's Aleutian Islands to Washington (88 FR 53510, August 8, 2023). Sea otters may be distributed anywhere within the specified geographic region other than upland areas; however, they generally occur in shallow water near the shoreline. They are most commonly observed within the 40-meter (m) (131-foot [ft]) depth contour (88 FR 53510, August 8, 2023), although they can be found in areas with deeper water. Ocean depth is generally correlated with distance to shore, and sea otters typically remain within 1 to 2 kilometers (km) (0.6 to 1.2 miles [mi]) of shore (Riedman and Estes 1990). They tend to be found closer to shore during storms but move farther out during good weather and calm seas (Lensink 1962; Kenyon 1969).

Sea otters are nonmigratory and generally do not disperse over long distances (Garshelis and Garshelis 1984), usually remaining within a few kilometers of their established feeding grounds (Kenyon 1981; Barocas and Ben-David 2021). Breeding males may stay for all or part of the year in a breeding territory ranging from 4 to 11 square kilometers (km 2 ) (1.5 to 4.2 square miles [mi 2 ]) (Garshelis and Garshelis 1984; Riedman and Estes 1990; 88 FR 53510, August 8, 2023), while adult females maintain home ranges of approximately 1 to 16 km (0.6 to 10 mi), which may include one or more male breeding territories (Kenyon 1969; Garshelis and Garshelis 1984; Riedman and Estes 1990). Juveniles disperse greater distances after weaning (Garshelis and Garshelis 1984; Garshelis et al. 1984; Monnett and Rotterman 1988; Riedman and Estes 1990). Although sea otters generally remain local to an area, they are capable of long-distance travel. Sea otters in Alaska have shown daily movement distances greater than 3 km (1.9 mi) at speeds up to 5.5 km per hour (3.4 mi per hour) (Garshelis and Garshelis 1984).

The Southcentral Alaska sea otter stock occurs in the center of the sea otter range in Alaska and extends from Cape Yakataga in the east to Cook Inlet in the west, including Prince William Sound (PWS), the eastern Kenai Peninsula coast, and Kachemak Bay (88 FR 53510, August 8, 2023). Between 2014 and 2019, aerial surveys were conducted in three regions of the Southcentral Alaska sea otter stock: (1) Eastern Cook Inlet, (2) Outer Kenai Peninsula, and (3) PWS by aerial transects flown at 91 m (~299 ft) of altitude. The combined estimates of the 3 regions resulted in approximately 21,617 sea otters (with a 95 percent confidence interval of 17,324 to 25,910 sea otters) and an average density of 1.96 sea otters/km 2 for the Southcentral Alaska stock (Esslinger et al. 2021; 88 FR 53510, August 8, 2023). The trend for the Southcentral Alaska sea otter stock has either increased or remained stable across surveyed areas since the FWS's previous stock assessment report in 2014 (88 FR 53510, August 8, 2023). The maximum rate of productivity, which is the maximum net annual increment in population numbers, for the Southcentral stock is estimated at 29 percent (Eisaguirre et al. 2021; 88 FR 53510, August 8, 2023). The Southcentral Alaska sea otter stock is classified as non-strategic under the MMPA (88 FR 53510, August 8, 2023).

The Southeast Alaska sea otter stock boundaries include Dixon Entrance Strait at the U.S.-Canada border to the south and Cape Yakataga to the north (88 FR 53510, August 8, 2023). However, the largest abundances of sea otters in Southeast Alaska are found in the northern part of this range and expanding south to east (Tinker et al. 2019). Sea otters from this stock prefer shallow waters (<40 m in depth), areas close to shore, areas with bathymetric variation ( i.e., steep slopes), and areas with straight shorelines (Eisaguirre et al. 2021).

The most recent abundance survey of the Southeast Alaska sea otter stock was conducted in 2022. The stock is estimated at 22,359 sea otters (with a 95 percent Bayesian credible interval of 19,595 to 25,290 sea otters) based on recent photo-based survey data, historic aerial survey data, and an applied ecological diffusion model to calculate stock-wide abundance (Eisaguirre et al. 2021, 2023; Schuette et al. 2023; 88 FR 53510, August 8, 2023). The trend for the Southeast Alaska sea otter stock has increased steadily over time (Schuette et al. 2023; 88 FR 53510, August 8, 2023). The maximum productivity rate is estimated at 29 percent (Eisaguirre et al. 2021; 88 FR 53510, August 8, 2023). This stock is classified as non-strategic under the MMPA (88 FR 53510, August 8, 2023). Abundance values within the Moorings Sitka project area ranged from 0.065 to 0.65 sea otters/km 2 .

The Southwest Alaska sea otter stock occurs from western Cook Inlet to Attu Island in the Aleutian chain (88 FR 53510, August 8, 2023). Between 2014 and 2021, surveys to estimate sea otter population size were conducted in the following locations: Aleutian Islands, Bristol Bay, South Alaska Peninsula, Kodiak Archipelago, Katmai National Park, western Cook Inlet, and Kamishak Bay (USFWS 2020; 88 FR 53510, August 8, 2023). The combined population estimates from these surveys resulted in a total estimate of 51,935 sea otters for the Southwest Alaska sea otter stock (a global coefficient of variation is unavailable for the Southwest Alaska stock due to the different survey methods and analytical approaches used for population assessments in each of the five management units). The overall trend for the Southwest Alaska sea otter stock is generally stable to increasing (88 FR 53510, August 8, 2023). The maximum rate of productivity is estimated at 29 percent (Eisaguirre et al. 2021; 88 FR 53510, August 8, 2023).

The Southwest Alaska sea otter stock was listed as threatened under the ESA in 2005 as a distinct population segment (DPS) due to sea otter population declines throughout the stock's range (70 FR 46366, August 9, 2005). A rule for this stock under section 4(d) of the ESA was promulgated in 2006 (71 FR 46864, August 15, 2006), and critical habitat was designated for the stock in 2009 (74 FR 51988, October 8, 2009). Sea otter critical habitat consists of areas within the 20-m (66-ft) depth contour, areas within the 100-m (328-ft) nearshore waters, and areas where the 20-m (66-ft) depth contour and 100-m (328-ft) nearshore waters overlap (74 FR 51988, October 8, 2009). The specified activities that would occur at Kodiak overlap with 1.61 km 2 (0.62 mi 2 ) of critical habitat for the Southwest Alaska sea otter stock. Sea otters' preference for shallow water may be related to diving depth limits and avoidance of large predators, such as killer whales ( Orcinus orca ) (Wilson et al. 2021; Monson 2021; Tinker et al. 2023), which have purportedly contributed to recent declines in the Southwest Alaska sea otter stock (78 FR 54905, September 6, 2013; Tinker et al. 2021). Sea otters' frequent use of shallow waters to avoid predation has allowed sea otter populations in the Southwest Alaska stock to persist, but this preference for shallow waters restricts habitat use and reduces population connectivity, which can impact population recovery (Tinker et al. 2023).

Under the ESA, the Southwest Alaska sea otter stock is divided into five management units (MU): Western Aleutians; Eastern Aleutians; South Alaska Peninsula; Bristol Bay; and Kodiak, Kamishak, and Alaska Peninsula (88 FR 53510, August 8, 2023). The specified geographic region occurs within the range of the Kodiak, Kamishak, and Alaska Peninsula MU.

The range of the Kodiak, Kamishak, and Alaska Peninsula MU extends from Chignik Bay to Western Cook Inlet on the southern side of the Alaska Peninsula, and it also encompasses Kodiak Island (USFWS 2020). The specified geographic region is within the range of the sea otter population at Kodiak Archipelago. The most recent aerial surveys to estimate sea otter population size in the Kodiak Archipelago were conducted in 2014. The overall sea otter density estimate within this area was 1.56 sea otters/km 2 (Cobb 2018; USFWS 2020). The population trend for sea otters in the Kodiak Archipelago appears to be increasing between the 2004 and 2014 surveys after exhibiting a decline between the 1994 and 2001 surveys (88 FR 53510, August 8, 2023). Sea otters were not uniformly distributed throughout the Kodiak Archipelago. Sea otter density was estimated to be 2.54 sea otters/km 2 in high sea otter density area, which is the area between shore and 400 m (1,312 ft) seaward, or the 40-m (131-ft) depth contour, whichever was greater. Sea otter density was estimated to be 0.30 sea otters/km 2 in low sea otter density area, which is the area between the high sea otter density area boundary and 2 km (1.2 mi) offshore, or the 100-m (328-ft) depth contour, whichever was greater (Cobb 2018). Sea otter density was highest in the straits between Kodiak, Raspberry, and Shuyak Islands. Few sea otters were observed on the eastern side of Kodiak Island (Cobb 2018).

The effects of climate change in the northern latitudes include increases in water and air temperatures, reductions in seasonal sea ice, increases in acidity of seawater, increases in coastal erosion, and changes in timing and intensity of storm events (Intergovernmental Panel on Climate Change 2014). Increasing ocean temperatures and changes in sea ice could allow species to expand or change their traditional ranges, allowing species that were previously geographically isolated from one another to share the same area. This interaction between species could introduce novel pathogens into populations. For example, phocine distemper virus was introduced to marine mammals in the Pacific Ocean, likely by seals traveling from the Atlantic Ocean (Goldstein et al. 2009). The loss of sea ice may facilitate additional introductions of novel pathogens to marine mammals in the Arctic and Pacific Oceans. Sea otters are susceptible to mortality from infections by a number of viruses, bacteria, and parasites (Burek-Huntington et al. 2021; Barratclough et al. 2023). For example, Strep syndrome has been recorded as one of the leading causes of death in northern sea otters in Alaska, especially in subadults who have not yet reproduced (Burek-Huntington et al. 2021; Barratclough et al. 2023). It is unknown what the long-term impacts of diseases are for sea otter populations and how climate change may affect disease rates in sea otter populations.

Climate change may also indirectly affect sea otters by altering the abundance, distribution, composition, and the quality of benthic invertebrates (Wassmann et al. 2011; Renaud et al. 2015), including the clams, urchins, and mussels eaten by sea otters. Increases in ocean temperatures and changes in sea ice may allow southern invertebrate species to move northward and create more resource competition for Arctic species. It is possible that Arctic species and overall species richness may decline as a result of increasing ocean temperatures (Renaud et al. 2015). However, there is a great deal of uncertainty and variability in the predicted effects of increased ocean temperatures and sea ice changes on benthic productivity (Post et al. 2013), and these potential impacts are likely to vary throughout the sea otter's range. Another potential concern with increased ocean temperatures is elevated levels of biotoxins in bivalve mollusks associated with harmful algal blooms (HABs) (Burek et al. 2008; Gulland et al. 2022; 88 FR 53510, August 8, 2023). Biotoxins bioaccumulate through trophic levels to sea otters and other top-level predators when they consume contaminated prey (Miller et al. 2010). Biotoxin exposure causes lesions in the central nervous system and cardiovascular system of sea otters (Miller et al. 2021), which can cause or contribute to mortality. For example, biotoxin concentrations were detected in 29 percent of sea otters examined for causes of mortality, and HAB toxicosis was considered the main cause of death for 2 of the 144 sea otters examined (Burek-Huntington et al. 2021). It is not well understood what impact HABs may have on the health of sea otter populations that are exposed to and uptake biotoxins through prey sources (88 FR 53510, August 8, 2023).

Climate change may also impact sea otter prey species through ocean acidification. Ocean acidification increases as the atmospheric concentrations of greenhouse gases rise. Clams, snails, and crabs, which are prevalent in sea otter diets, contain calcium-based shells, which may be corroded from ocean acidification. The early life stages of some bivalves and gastropods are likely to be negatively affected (Kroeker et al. 2013; 88 FR 53510, August 8, 2023), particularly the broadcast spawners that have an extended pelagic larval phase. Some sea otter prey species may be more tolerant, especially those that are periodically exposed to acidified seawater under natural conditions. Sea otters eat a variety of different benthic organisms (LaRoche et al. 2021), and this variability in their diet may provide some resiliency against the changes in prey availability due to ocean acidification.

Climate change has the potential to impact sea otters by altering species ranges and interactions, introducing novel pathogens, and changing the availability, distribution, and quality of prey species. However, there is a great deal of uncertainty and variability in the predicted effects of climate change on sea otters and their prey species. Sea otters also exhibit behavioral flexibility and diversity in their prey consumption (LaRoche et al. 2021), which may allow them to adapt to climate change effects. For example, sea otters show a high degree of individuality and diversity in their diet and foraging behavior that allow them to compete in an environment with limited food resources (Tinker et al. 2008; LaRoche et al. 2021). Evidence shows that sea otters may also be able to attenuate the effects of climate change through top-down effects within their ecosystem. For example, the rising ocean temperatures and ocean acidification parallel a decline in skeletal density of Clathromorphum nereostratum, a red alga found in kelp forests. This reduction in skeletal density makes the algae more susceptible to lethal grazing by sea urchins. Sea otters regulate sea urchin populations through prey consumption, which helps maintain equilibrium within kelp forests and potentially mitigate the effects of climate change within kelp forests (Rasher et al. 2020). More information is needed to better understand how climate change impacts sea otters and how sea otter populations respond to climate change impacts.

We characterize “noise” as sound released into the environment from human activities that exceeds ambient levels or interferes with normal sound production or reception by sea otters. The terms “acoustic disturbance” and “acoustic harassment” are disturbances or harassment events resulting from noise exposure. Potential effects of noise exposure are likely to depend on the distance of the sea otter from the sound source, the level and intensity of sound the sea otter receives, background noise levels, noise frequency, noise duration, and whether the noise is pulsed or continuous. The actual noise level perceived by individual sea otters will also depend on whether the sea otter is above or below water and atmospheric and environmental conditions. Temporary disturbance of sea otters or localized displacement reactions are the most likely effects to occur from noise exposure.

Pile driving and marine construction activities produce sound within the hearing range of sea otters. Controlled sound exposure trials on southern sea otters ( Enhydra lutris nereis ) indicate that sea otters can hear frequencies between 125 hertz (Hz) and 38 kilohertz (kHz), with best sensitivity between 1.2 and 27 kHz (Ghoul and Reichmuth 2014). Sea otters are more adept at aerial hearing and their sensitivity is similar to that of terrestrial carnivores (Reichmuth and Ghoul 2012; Ghoul and Reichmuth 2016; Zellmer et al. 2021). Aerial and underwater audiograms for a captive adult male southern sea otter in the presence of ambient noise suggest the sea otter's hearing was less sensitive to high-frequency (greater than 22 kHz) and low-frequency (less than 2 kHz) sound than that of terrestrial mustelids but was similar to that of a California sea lion ( Zalophus californianus ). However, the sea otter was still able to hear low-frequency sounds, and the detection thresholds for sounds between 0.125 and 1 kHz were between 116 and 101 decibels (dB), respectively. Dominant frequencies of southern sea otter vocalizations are between 3 and 8 kHz, with some energy extending above 60 kHz (McShane et al. 1995; Ghoul and Reichmuth 2012).

Exposure to high levels of sound may cause changes in behavior, masking of communications, temporary or permanent changes in hearing sensitivity, discomfort, and injury to marine mammals. Sea otters do not rely on sound to orient themselves, locate prey, or communicate under water; therefore, masking of communications by anthropogenic noise is less of a concern than for other marine mammals. However, sea otters, especially mothers and pups, do use sound for communication in air (McShane et al. 1995), and sea otters may monitor underwater sound to avoid predators (Davis et al. 1987).

Noise exposure criteria for identifying underwater noise levels capable of causing Level A harassment (injury) to marine mammal species, including sea otters, have been established using the same methods as those used by the National Marine Fisheries Service (NMFS) (Southall et al. 2019). These criteria are based on estimated levels of sound exposure capable of causing a permanent shift in hearing sensitivity ( i.e., a permanent threshold shift (PTS) (NMFS 2018)). A PTS occurs when noise exposure causes damage to hair cells within the inner ear system (Ketten 2012). Although the effects of PTS are, by definition, permanent, PTS does not equate to total hearing loss.

Sound exposure thresholds incorporate two metrics of exposure: the peak level of instantaneous exposure likely to cause PTS, and the cumulative sound exposure level (SEL CUM ) during a 24-hour period. They also include weighting adjustments for the sensitivity of different species to varying frequencies. PTS-based injury criteria were developed from theoretical extrapolation of observations of temporary threshold shifts (TTS) detected in lab settings during sound exposure trials (Finneran 2015). A TTS is a noise-induced threshold shift in hearing sensitivity that fully recovers over time (Finneran 2015). Southall et al. (2019) developed TTS thresholds for sea otters, which are included in the “other marine carnivores” category, of 188 dB SEL for impulsive sounds and 199 dB SEL for nonimpulsive sounds. Based on these analyses, Southall et al. (2019) predict that PTS for sea otters will occur at 232 dB peak or 203 dB SEL CUM for impulsive underwater sound and 219 dB SEL for nonimpulsive (continuous) underwater sound.

The NMFS (2018) criteria do not identify thresholds for avoidance of Level B harassment. For pinnipeds (seals and sea lions), NMFS has adopted a 160-dB threshold for Level B harassment from exposure to impulsive noise and a 120-dB threshold for continuous noise (High Energy Seismic Survey Team 1999; NMFS 2018). These thresholds were developed from observations of mysticete (baleen) whales responding to airgun operations ( e.g., Malme et al. 1983; Malme and Miles 1983; Richardson et al. 1986, 1995) and from equating Level B harassment with noise levels capable of causing TTS in lab settings. Southall et al. (2007, 2019) assessed behavioral response studies and found considerable variability among pinnipeds. The authors determined that exposures between approximately 90 to 140 dB generally do not appear to induce strong behavioral responses from pinnipeds in water. However, they found behavioral effects, including avoidance, become more likely in the range between 120 and 160 dB, and most marine mammals showed some, albeit variable, responses to sound between 140 and 180 dB. Wood et al. (2012) adapted the approach identified in Southall et al. (2007) to develop a probabilistic scale for marine mammal taxa at which 10 percent, 50 percent, and 90 percent of individuals exposed are assumed to produce a behavioral response. For many marine mammals, including pinnipeds, these response rates were set at sound pressure levels (SPLs) of 140, 160, and 180 dB, respectively.

We have evaluated these thresholds and determined that the Level B harassment threshold of 120 dB for nonimpulsive noise is not applicable to sea otters. The 120-dB threshold is based on studies in which gray whales ( Eschrichtius robustus ) were exposed to experimental playbacks of industrial noise (Malme et al. 1983; Malme and Miles 1983). During these playback studies, southern sea otter responses to industrial noise were also monitored (Riedman 1983, 1984). While gray whales exhibited avoidance to industrial noise at the 120-dB threshold, there was no evidence of disturbance reactions or avoidance in southern sea otters. Thus, given the different range of frequencies to which sea otters and gray whales are sensitive, the NMFS 120-dB threshold based on gray whale behavior is not appropriate for predicting sea otter behavioral responses, particularly for low-frequency sound.

Based on the lack of sea otter disturbance response or any other reaction to the playback studies from the 1980s, as well as the absence of a clear pattern of disturbance or avoidance behaviors attributable to underwater sound levels up to about 160 dB resulting from low-frequency broadband noise, we assume 120 dB is not an appropriate behavioral response threshold for sea otters exposed to continuous underwater noise.

Based on the best available scientific information about sea otters and closely related marine mammals when sea otter data are limited, the FWS has set 160 dB of received underwater sound as a threshold for take by Level B harassment of sea otters in this proposed ITR. Exposure to in-water noise levels between 125 Hz and 38 kHz that are greater than 160 dB—for both impulsive and nonimpulsive sound sources—will be considered by the FWS as Level B harassment. Thresholds for Level A harassment (which entails the potential for injury) for in-water noise levels between 125 Hz and 38 kHz are 232 dB peak or 203 dB SEL for impulsive sounds and 219 dB SEL for continuous sounds (table 4).

The NMFS (2018) guidance neither addresses thresholds for preventing injury or disturbance from airborne noise, nor provides thresholds for avoidance of Level B harassment. Conveyance of underwater noise into the air is of little concern since the effects of pressure release and interference at the water's surface reduce underwater noise transmission into the air. For activities that create both in-air and underwater noise, we will estimate take based on parameters for underwater noise transmission. Considering sound energy travels more efficiently through water than through air, this estimation will also account for exposures to sea otters at the surface.