Regional Haze

Regional Haze Program and RH SIP Submittals

The Regional Haze Program is a long-term national program designed to protect current visibility conditions at treasured areas that have been designated as Federal Class I Areas, and to restore visibility to natural conditions at those impacted by man-made sources. The Wichita Mountains Wilderness Area (WMWA) in Comanche County is Oklahoma’s only Class I Area.

Oklahoma implements the Regional Haze Program through State Implementation Plans (SIPs) in accordance with the federal Regional Haze Rule (40 CFR Part 51, Subpart P, Protection of Visibility). A comprehensive SIP revision is required every ten years to update the state’s plan to meet reasonable progress goals in the following ten-year period, also called the Planning Period. Each RH SIP must address visibility conditions at the Wichita Mountains Wilderness Area, and any other Class I area at which Oklahoma may contribute to impairment.

Wichita Mountains

The Regional Haze Program is helping to improve the view at the Wichita Mountains Wilderness Area, Oklahoma’s only federally-designated Class I area, located within the Wichita Mountains National Wildlife Refuge in Comanche County, near Fort Sill & Lawton, OK. It is managed by the U.S. Fish and Wildlife Service.

The Air Quality Division continually works with the Federal Land Managers (FLMs), EPA, and our regional-state partnerships, especially through the Central States Air Resource Agencies (CenSARA), to develop a long-term strategy for meeting natural visibility conditions by 2064.

Planning Period 1

2010 Oklahoma Regional Haze Plan

Oklahoma’s Regional Haze State Implementation Plan (RH SIP) for the initial Planning Period was submitted to EPA Region 6 on February 18, 2010. This plan addresses the requirements of the federal regional haze regulations in 40 CFR Part 51, Subpart P, Protection of Visibility, including determination and implementation of Best Available Retrofit Technology (BART) requirements of OAC 252:100-8-70 through 78. It also addresses regional planning, documents the extensive processes for State/Tribe & federal land manager (FLM) consultation, and public comment & hearing.

Regional Haze State Implementation Plan (February 2010), including the Secretary of Environment’s RH SIP Submittal Letter & the Rulemaking Procedures Certification


November 2009 Draft SIP and 2007 Initial Planning Document

EPA Action on 2010 RH SIP: Effective January 27, 2012 (76 FR 81727), EPA approved core elements of Oklahoma’s Regional Haze SIP, including BART determinations for the majority of emissions units subject to BART. However, EPA disapproved the sulfur dioxide (SO2) BART determinations for several emissions units, and issued a Federal Implementation Plan (FIP) covering SO2 control requirements for those units.

2013 Oklahoma Regional Haze Plan Revision

On June 18, 2013, Oklahoma submitted a revision to the 2010 RH SIP to replace a portion of the Federal Implementation Plan (FIP) covering SO2 control requirements for two coal-fired units located at a facility in Rogers County, Oklahoma. This SIP revision submittal process included consultation with Federal Land Managers and potentially affected states, public review and comment including a public hearing held at DEQ’s OKC offices on May 20, 2013, and EPA’s proposed action on August 21, 2013 (78 FR 51686). On March 7, 2014, EPA published a notice (79 FR 12944) in the Federal Register approving the SIP revision. A separate notice published simultaneously (79 FR 12954) withdrew the EPA-issued FIP as it relates to the subject facility.

Regional Haze & Transport State Implementation Plan Revision (2013), including the Secretary of Environment’s RH SIP Submittal Letter

Appendices – note: proposed versions are either included in the final appendix or provided separately

Five Year Progress Report

On September 28, 2016, Oklahoma submitted the Five-Year Progress Report on Oklahoma’s Regional Haze State Implementation Plan (RH SIP) to EPA for their review. The report gives an update on implementation of BART requirements and other control measures that maintain and improve visibility. The report evaluates progress towards achieving natural visibility conditions, including changes in visibility at the Wichita Mountains. The FLM & interstate coordination and public comment processes and results are also summarized in the report. EPA published proposed and final approval notices for Oklahoma’s 5-year RH SIP Progress Report in the Federal Register on March 28, 2019 (84 FR 11711) and June 28, 2019 (84 FR 30918), respectively.

Five-Year Progress Report on 2010 Oklahoma’s Regional Haze State Implementation Plan, including the Secretary of Energy and Environment’s Submittal Letter

Planning Period 2

RH SIP Development

The second planning period for the Regional Haze Program covers the period 2018 to 2028. The first planning period RH SIP primarily focused on making progress towards natural visibility conditions by obtaining reductions of visibility-impairing emissions from a specific, defined group of emission sources as candidates to install and implement Best Available Retrofit Technology (BART). See OAC 252:100-8, Part 11. Subsequent RH planning periods must continue the progress by considering if further reductions are needed and obtainable using a selection process from a broader pool of emission sources followed by a “four-factor analysis” to measure cost-effectiveness of potential added controls for selected emission sources. Through lessons learned during the first planning period, EPA made a number of changes to the RH rule, including to: more clearly focus the goal of natural visibility conditions on controlling sources over which the States have jurisdiction (i.e., domestic man-made emissions); better define the FLM consultation process; and delay the deadline for submittal of the Planning Period 2 RH SIP to July 31, 2021.

As stated in the Public Notice, the proposed Planning Period 2 RH SIP is available for a 30-day public comment period from June 1, 2022 through July 1, 2022, and DEQ will hold a public hearing on Friday, July 1, 2022 from 9:00 am to 11:00 am. Please note the location has been changed from the 2nd Floor Training Room to the 1st Floor Multipurpose Room at the DEQ Headquarters. For those who cannot attend the public hearing in person, a link to view a non-participatory stream of the hearing online will be posted to this web page at least 24-hours prior to the public hearing. A brief PowerPoint presentation will be given by DEQ at the start of the hearing.

Oklahoma Regional Haze State Implementation Plan Revision: Planning Period 2 (June 2022 Draft SIP)


As part of the process for developing the Planning Period 2 RH SIP, DEQ identified 12 facilities in Oklahoma that are reasonably anticipated to impact visibility conditions at the WMWA. A Powerpoint presentation delivered at the June 2020 AQAC meeting gave more detail of DEQ’s planning and development process. Appendix E contains the letters DEQ sent requesting an analysis and the responses received to date, which are also individually linked below:

Additionally, DEQ identified 21 sources in neighboring states that are reasonably anticipated to impact visibility conditions at the WMWA. As documented in Appendix A, each of the states was asked to consider the potential impact of the sources identified within their state for possible further analysis as part of the process for developing their Planning Period 2 RH SIP. A copy of each request is linked below: