Air Plan Approval; AK; Regional Haze Plan for the Second Implementation Period

ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R10-OAR-2023-0348; FRL-11133-01-R10]</DEPDOC> <SUBJECT>Air Plan Approval; AK; Regional Haze Plan for the Second Implementation Period</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Proposed rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The Environmental Protection Agency (EPA) is proposing to approve the Alaska regional haze plan for the second implementation period. Alaska submitted the plan to address applicable requirements under the Clean Air Act and the EPA's Regional Haze Rule. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Written comments must be received on or before December 1, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Submit your comments, identified by Docket ID No. EPA-R10-OAR-2023-0348 at <E T="03">https://www.regulations.gov</E> . For comments submitted at <E T="03">regulations.gov,</E> follow the online instructions for submitting comments. Once submitted, comments may not be edited or removed from <E T="03">regulations.gov</E> . For either manner of submission, the EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be confidential business information or other information the disclosure of which is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission ( <E T="03">i.e.,</E> on the web, cloud, or other file sharing system). For additional submission methods, please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section. For the full EPA public comment policy, information about confidential business information or multimedia submissions, and general guidance on making effective comments, please visit <E T="03">https://www.epa.gov/dockets/commenting-epa-dockets</E> . <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Kristin Hall, EPA Region 10, 1200 Sixth Avenue, Suite 155, Seattle, WA 98101, at (206) 553-6357 or <E T="03">hall.kristin@epa.gov</E> . </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document, the use of “we” and “our” means “the EPA.” <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. What action is the EPA proposing?</FP> <FP SOURCE="FP-2">II. Background and Requirements for Regional Haze Plans</FP> <FP SOURCE="FP1-2">A. Regional Haze</FP> <FP SOURCE="FP1-2">B. The Western Regional Air Partnership</FP> <FP SOURCE="FP-2">III. Requirements for Regional Haze Plans for the Second Implementation Period</FP> <FP SOURCE="FP1-2">A. Identification of Class I Areas</FP> <FP SOURCE="FP1-2">B. Calculations of Baseline, Current, and Natural Visibility Conditions; Progress to Date; and the Uniform Rate of Progress</FP> <FP SOURCE="FP1-2">C. Long-Term Strategy for Regional Haze</FP> <FP SOURCE="FP1-2">D. Reasonable Progress Goals</FP> <FP SOURCE="FP1-2">E. Monitoring Strategy and Other State Implementation Plan Requirements</FP> <FP SOURCE="FP1-2">F. Requirements for Periodic Reports Describing Progress Towards the Reasonable Progress Goals</FP> <FP SOURCE="FP1-2">G. Requirements for State and Federal Land Manager Coordination</FP> <FP SOURCE="FP-2">IV. The EPA's Evaluation of the Alaska Regional Haze Plan for the Second Implementation Period</FP> <FP SOURCE="FP1-2">A. Background on the Alaska First Implementation Period Plan</FP> <FP SOURCE="FP1-2">B. The Alaska Second Implementation Period Plan and the EPA's Evaluation</FP> <FP SOURCE="FP1-2">C. Identification of Class I Areas</FP> <FP SOURCE="FP1-2">D. Calculations of Baseline, Current, and Natural Visibility Conditions; Progress to Date; and the Uniform Rate of Progress</FP> <FP SOURCE="FP1-2">E. Long-Term Strategy for Regional Haze</FP> <FP SOURCE="FP1-2">F. Reasonable Progress Goals</FP> <FP SOURCE="FP1-2">G. Monitoring Strategy and Other Implementation Plan Requirements</FP> <FP SOURCE="FP1-2">H. Requirements for Periodic Reports Describing Progress Towards the Reasonable Progress Goals</FP> <FP SOURCE="FP1-2">I. Requirements for State and Federal Land Manager Coordination</FP> <FP SOURCE="FP-2">V. Proposed Action</FP> <FP SOURCE="FP-2">VI. Incorporation by Reference</FP> <FP SOURCE="FP-2">VII. Statutory and Executive Order Reviews</FP> </EXTRACT> <HD SOURCE="HD1">I. What action is the EPA proposing?</HD> The EPA is proposing to approve the Alaska regional haze plan for the second implementation period as meeting the Regional Haze Rule (RHR) requirements of 40 CFR 51.308(f)(1) through (6), (g)(1) through (5), and (i). The Alaska Department of Environmental Conservation (DEC) submitted the regional haze plan on July 25, 2022, as a State Implementation Plan (SIP) revision, and clarified aspects of the submission on October 6, 2025. In addition, as requested by the Alaska DEC in the submission, we are proposing to approve and incorporate by reference into the Alaska SIP at 40 CFR 52.70(c), two new regulatory provisions of Alaska Administrative Code Title 18 Environmental Conservation, Chapter 50 Air Quality Control (18 AAC 50), specifically, 18 AAC 50.025 and 18 AAC 50.265, State effective August 21, 2022. The EPA is proposing this action pursuant to Clean Air Act (CAA) sections 110 and 169A. <HD SOURCE="HD1">II. Background and Requirements for Regional Haze Plans</HD> A detailed history and background of the regional haze program is provided in multiple prior EPA proposal actions. <SU>1</SU> <FTREF/> For additional background on the 2017 RHR revisions, please refer to section III of this document. Overview of Visibility Protection Statutory Authority, Regulation, and Implementation of “Protection of Visibility: Amendments to Requirements for State Plans” of the 2017 RHR. <SU>2</SU> <FTREF/> The following is an abbreviated history and background of the regional haze program and 2017 RHR as it applies to the current action. <FTNT> <SU>1</SU>  See 90 FR 13516 (March 24, 2025). </FTNT> <FTNT> <SU>2</SU>  See 82 FR 3078 (January 10, 2017) at page 3081. </FTNT> <HD SOURCE="HD2">A. Regional Haze</HD> In the 1977 CAA Amendments, Congress created a program for protecting visibility in the nation's mandatory Class I Federal areas, which include certain national parks and wilderness areas. See CAA section 169A. The CAA establishes as a national goal the “prevention of any future, and the remedying of any existing, impairment of visibility in mandatory class I Federal areas which impairment results from manmade air pollution.” See CAA section 169A(a)(1). In CAA section 169A(a)(1), Congress established the national goal of preventing any future and remedying any existing impairment of visibility in mandatory Class I Federal areas that results from manmade (anthropogenic) air pollution. The core component of a regional haze SIP submission for the second implementation period is a strategy that addresses regional haze in each Class I area within the State's borders and each Class I area outside the State that may be affected by emissions originating from within the State, CAA section 169A(b)(2)(B), 40 CFR 51.308(f)(2), and makes “reasonable progress” toward the national goal based on consideration of the four statutory factors in CAA section 169A(g)(1)—the costs of compliance, the time necessary for compliance, the energy and non-air quality environmental impacts of compliance, and the remaining useful life of any potentially affected sources. <SU>3</SU> <FTREF/> <FTNT> <SU>3</SU>  CAA section 169A(g)(1); 40 CFR 51.308(f)(2)(i). </FTNT> Regional haze is visibility impairment that is produced by a multitude of anthropogenic sources and activities which are located across a broad geographic area and that emit pollutants that impair visibility. Visibility impairing pollutants include fine and coarse particulate matter (PM) ( <E T="03">e.g.,</E> sulfates, nitrates, organic carbon, elemental carbon, and soil dust) and their precursors ( <E T="03">e.g.,</E> sulfur dioxide (SO <E T="52">2</E> ), nitrogen oxides (NO <E T="52">X</E> ), and, in some cases, volatile organic compounds (VOC) and ammonia (NH <E T="52">3</E> )). Fine particle precursors react in the atmosphere to form fine particulate matter (PM <E T="52">2.5</E> ), which impairs visibility by scattering and absorbing light. Visibility impairment reduces the perception of clarity and color, as well as visible distance. <SU>4</SU> <FTREF/> <FTNT> <SU>4</SU>  There are several ways to measure the amount of visibility impairment, <E T="03">i.e.,</E> haze. One such measurement is the deciview, which is the principal metric used by the RHR. Under many circumstances, a change in one deciview will be perceived by the human eye to be the same on both clear and hazy days. The deciview is unitless. It is proportional to the logarithm of the atmospheric extinction of light, which is the perceived dimming of light due to its being scattered and absorbed as it passes through the atmosphere. Atmospheric light extinction (b <SU>ext</SU> ) is a metric used for expressing visibility and is measured in inverse megameters (Mm <E T="51">−1</E> ). The formula for the deciview is 10 ln (b <SU>ext</SU> )/10 Mm−1). See 40 CFR 51.301. </FTNT> To address regional haze visibility impairment, the 1999 RHR established an iterative planning process that requires both States in which Class I areas are located and States “the emissions from which may reasonably be anticipated to cause or contribute to any impairment of visibility” in a Class I area to periodically su ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 201k characters. 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