On April 25, 2016, EPA proposed revisions to its requirements for state plans submitted under the CAA for protection of visibility in mandatory Class I federal areas in order to assure continued steady progress in reducing regional haze in national parks. States are required to submit periodic plans that demonstrate how they will continue to make progress towards achieving their visibility improvement goals. The first state plans covered the 2008 to 2018 planning period. The proposed rule will address the requirements for ensuring reasonable further progress during the second planning period from July 31, 2018 to 2028. The first phase focused on applying best available retrofit technology (BART) to large sources of NO_x, fine PM and SO₂. The proposed rule appeared in the May 4, 2016 Federal Register, and the public comment period ended on August 10, 2016. 

With respect to SIP requirements, EPA is proposing to extend the deadline for submittal of the SIPs for the second implementation period from July 31, 2018 to July 31, 2021. EPA explains the extension will allow states to consider emission reductions achieved under other federal programs in conducting their regional haze planning, such as the 1-Hour SO₂ NAAQS, the 2012 Annual PM_2.5 NAAQS, and the Clean Power Plan. EPA is also proposing to adjust interim progress report submission deadlines and is removing the requirement for progress reports to take the form of SIP revisions. The proposed rule would require states to consult with Federal Land Managers (FLMs) and obtain public comment on their progress reports before they are submitted to EPA. The proposed rule would also enhance the role of FLMs in the state planning process and clarify that FLMs alone have the power to certify that a source or group of sources is causing impairment at a Class I Area under the reasonably attributable visibility impairment provisions.

EPA is also proposing clarifications to the regulations to reflect its long standing interpretations applied under the 1999 Regional Haze Rule. The proposed rule clarifies that all states, not just states with Class I Areas, are responsible for developing reasonable progress plans for emissions that contribute to impairment in Class I Areas. States would be responsible for assessing reduction and control requirements to respond to a FLM reasonable attributable visibility impairment certification. The proposed rule would also clarify that states must conduct additional analysis to demonstrate that no additional emission reduction measures are reasonable for making further progress where a state is not on track within the 10-year regional haze planning period to attain natural conditions in Class I areas by 2064.