Regional Haze Plan

What is the Regional Haze Plan?

In 1977, Congress amended the Clean Air Act (CAA) to include provisions to protect the scenic vistas of the nation’s national parks, national monuments, and wilderness areas. In these amendments, Congress declared as a national visibility goal: “The prevention of any future, and the remedying of any existing impairment of visibility in mandatory Federal Class I areas which impairment results from manmade air pollution.”

When the CAA was amended in 1990, Congress added § 169B, authorizing further research and regular assessments of the progress to improve visibility in Federal Class I areas.

In 1999, EPA finalized the Regional Haze Rule,1 which aimed to reduce emissions that contribute to haze in Federal Class I areas, or designated wilderness areas, national parks, and monuments. In 2017, EPA published amendments to the Regional Haze Rule to update the program for the Second implementation Period (2018-2028).2

Arizona is required by federal regulation3 to revise and submit its regional haze implementation plan revision to EPA by July 31, 2021, July 31, 2028, and every 10 years thereafter. These revisions must include: calculations of baseline and natural visibility conditions, reasonable progress goals toward natural visibility conditions, a long-term strategy addressing visibility impairment from regional haze, a monitoring strategy, and other implementation plan requirements.

In addition, Arizona is required to periodically submit a report to the EPA Administrator evaluating progress towards the reasonable progress goal for each Federal Class I area located within the State and in each Federal Class I area located outside the State that may be affected by emissions from within the State. Progress reports are due by January 31, 2025, July 31, 2033, and every 10 years thereafter.