{"abstract":"The Environmental Protection Agency (EPA) is finalizing approval of revisions to the Arizona state implementation plan (SIP) for attaining the 1971 and 2010 sulfur dioxide (SO<INF>2</INF>) national ambient air quality standards (NAAQS or \"standards\") in the Hayden SO<INF>2</INF> nonattainment area. These SIP revisions, collectively referred to as the \"Hayden SO<INF>2</INF> Plan\" or \"Plan,\" include Arizona's attainment demonstration and other elements required under Clean Air Act (CAA or \"Act\") sections 110, 172, 191, and 192. In addition to an attainment demonstration, the revisions address the requirements for meeting reasonable further progress (RFP) toward attainment of the NAAQS, reasonably available control measures and reasonably available control technology (RACM/RACT), base-year and projection-year emissions inventories, nonattainment new source review, emissions limitations necessary to provide for attainment, and contingency measures. The EPA is approving the SIP revisions as meeting the CAA requirements. This action is being taken under the CAA.","action":"Final rule.","agencies":[{"raw_name":"ENVIRONMENTAL PROTECTION AGENCY","name":"Environmental Protection Agency","id":145,"url":"https://www.federalregister.gov/agencies/environmental-protection-agency","json_url":"https://www.federalregister.gov/api/v1/agencies/145","parent_id":null,"slug":"environmental-protection-agency"}],"body_html_url":"https://www.federalregister.gov/documents/full_text/html/2026/08/20/2026-16989.html","cfr_references":[{"chapter":null,"citation_url":null,"part":"52","title":40}],"citation":"91 FR 53720","comment_url":null,"comments_close_on":null,"correction_of":null,"corrections":[],"dates":"This rule is effective September 21, 2026.","disposition_notes":null,"docket_ids":["EPA-R09-OAR-2025-3821","FRL-13144-02-R9"],"dockets":[{"supporting_documents":[{"title":"Hayden SO2_Docket Index - Final","document_id":"EPA-R09-OAR-2025-3821-0012"},{"title":"G. Notice of Final Rulemaking","document_id":"EPA-R09-OAR-2025-3821-0011"},{"title":"F. Additional Documents Considered for Final Rulemaking","document_id":"EPA-R09-OAR-2025-3821-0010"},{"title":"E. Public Comments and Related Documents","document_id":"EPA-R09-OAR-2025-3821-0009"},{"title":"D. Notice of Proposed Rulemaking and TSDs","document_id":"EPA-R09-OAR-2025-3821-0006"},{"title":"C. Additional Documents for Proposed Rulemaking","document_id":"EPA-R09-OAR-2025-3821-0005"},{"title":"B. State Plans, Rules, TSDs, and Correspondence","document_id":"EPA-R09-OAR-2025-3821-0004"},{"title":"A. EPA Rulemakings, Guidance, Correspondence, and TSDs","document_id":"EPA-R09-OAR-2025-3821-0003"},{"title":"Hayden SO2_Docket Index - Proposal","document_id":"EPA-R09-OAR-2025-3821-0002"}],"agency_name":"EPA","documents":[{"comment_count":0,"comment_start_date":"2026-08-20","updated_at":"2026-08-20T09:57:05.618-04:00","comment_url":"https://www.regulations.gov/commenton/EPA-R09-OAR-2025-3821-0008","allow_late_comments":false,"id":"EPA-R09-OAR-2025-3821-0008","comment_end_date":null,"regulations_dot_gov_open_for_comment":false}],"supporting_documents_count":9,"id":"EPA-R09-OAR-2025-3821","title":"Air Plan Approval; Arizona; Attainment Plan for the Hayden SO2 Nonattainment Area for the 1971 and 2010 Sulfur Dioxide National Ambient Air Quality Standards"}],"document_number":"2026-16989","effective_on":"2026-09-21","end_page":53726,"executive_order_notes":null,"executive_order_number":null,"full_text_xml_url":"https://www.federalregister.gov/documents/full_text/xml/2026/08/20/2026-16989.xml","html_url":"https://www.federalregister.gov/documents/2026/08/20/2026-16989/air-plan-approval-arizona-attainment-plan-for-the-hayden-so2-nonattainment-area-for-the-1971-and","images":{},"images_metadata":{},"json_url":"https://www.federalregister.gov/api/v1/documents/2026-16989?publication_date=2026-08-20","mods_url":"https://www.govinfo.gov/metadata/granule/FR-2026-08-20/2026-16989/mods.xml","not_received_for_publication":null,"page_length":7,"page_views":{"count":345,"last_updated":"2026-10-24 08:15:05 -0400"},"pdf_url":"https://www.govinfo.gov/content/pkg/FR-2026-08-20/pdf/2026-16989.pdf","presidential_document_number":null,"proclamation_number":null,"public_inspection_pdf_url":"https://public-inspection.federalregister.gov/2026-16989.pdf?1787143522","publication_date":"2026-08-20","raw_text_url":"https://www.federalregister.gov/documents/full_text/text/2026/08/20/2026-16989.txt","regulation_id_number_info":{},"regulation_id_numbers":[],"regulations_dot_gov_info":{"supporting_documents":[{"title":"Hayden SO2_Docket Index - Final","document_id":"EPA-R09-OAR-2025-3821-0012"},{"title":"G. Notice of Final Rulemaking","document_id":"EPA-R09-OAR-2025-3821-0011"},{"title":"F. Additional Documents Considered for Final Rulemaking","document_id":"EPA-R09-OAR-2025-3821-0010"},{"title":"E. Public Comments and Related Documents","document_id":"EPA-R09-OAR-2025-3821-0009"},{"title":"D. Notice of Proposed Rulemaking and TSDs","document_id":"EPA-R09-OAR-2025-3821-0006"},{"title":"C. Additional Documents for Proposed Rulemaking","document_id":"EPA-R09-OAR-2025-3821-0005"},{"title":"B. State Plans, Rules, TSDs, and Correspondence","document_id":"EPA-R09-OAR-2025-3821-0004"},{"title":"A. EPA Rulemakings, Guidance, Correspondence, and TSDs","document_id":"EPA-R09-OAR-2025-3821-0003"},{"title":"Hayden SO2_Docket Index - Proposal","document_id":"EPA-R09-OAR-2025-3821-0002"}],"comments_count":0,"agency_id":"EPA","comments_url":"https://www.regulations.gov/docketBrowser?rpp=50&so=DESC&sb=postedDate&po=0&dct=PS&D=EPA-R09-OAR-2025-3821","supporting_documents_count":9,"docket_id":"EPA-R09-OAR-2025-3821","document_id":"EPA-R09-OAR-2025-3821-0008","regulation_id_number":null,"title":"Air Plan Approval; Arizona; Attainment Plan for the Hayden SO2 Nonattainment Area for the 1971 and 2010 Sulfur Dioxide National Ambient Air Quality Standards","checked_regulationsdotgov_at":"2026-08-21T15:55:05Z"},"regulations_dot_gov_url":null,"significant":null,"signing_date":null,"start_page":53720,"subtype":null,"title":"Air Plan Approval; Arizona; Attainment Plan for the Hayden SO2 Nonattainment Area for the 1971 and 2010 Sulfur Dioxide National Ambient Air Quality Standards","toc_doc":"Arizona; Attainment Plan for the Hayden SO2 Nonattainment Area for the 1971 and 2010 Sulfur Dioxide National Ambient Air Quality Standards","toc_subject":"Air Quality State Implementation Plans; Approvals and Promulgations","topics":["Air pollution control","Environmental protection","Incorporation by reference","Intergovernmental relations","Reporting and recordkeeping requirements","Sulfur oxides"],"type":"Rule","volume":91}