States are responsible for developing a Regional Haze State Implementation Plan (SIP) that addresses regional haze in each Class I area located within the state and in each Class I area located outside the state which may be affected by emissions from sources within the state. The Regional Haze SIP is required to identify existing facilities that cause or contribute to visibility impairment; analyze, identify, and apply federally enforceable control strategies for those sources; and periodically demonstrate reasonable progress toward reaching visibility goals. States are also responsible for periodic comprehensive updates to their Regional Haze SIP that address these same topics. For certain older sources, the SIP must also determine the Best Available Retrofit Technology (BART). The determination of BART is based on an analysis of the best system of continuous emission control technology available and associated emission reductions achievable for each source subject to BART. This analysis considers:

  • technology available
  • costs of compliance
  • energy and non-air-quality environmental impacts of compliance
  • any pollution control equipment in use at the source
  • remaining useful life of the source
  • degree of improvement in visibility which may reasonably be anticipated to result from the use of such technology

The SIP must contain emission limitations representing BART and schedules for compliance with BART for each source subject to BART that emits any air pollutant which may reasonably be anticipated to cause or contribute to any impairment of visibility in any mandatory federal Class I area. The state also has an option to demonstrate that an emissions trading program or other alternative will achieve greater reasonable progress toward natural visibility conditions than would be achieved through the installation and operation of BART.

Draft State Implementation Plan

The draft Regional Haze State Implementation Plan for the second implementation period (2018 - 2028) was open for public comment from August 22, 2022, to October 7, 2022.


Progress report

The MPCA submitted the five-year progress report in December 2014. It outlined the status of required SIP elements and documented Minnesota’s determination that its Regional Haze SIP was adequate and required no further substantive revision to achieve 2018 visibility goals.

U.S. EPA's Regional Haze Federal Implementation Plan for taconite facilities

In the MPCA’s 2009 SIP and subsequent 2012 supplement, the MPCA identified site-specific BART determinations for nitrogen oxide (NOX), particulate matter (PM), and sulfur dioxide (SO2) emissions at taconite facilities. In general, the MPCA determined for all taconite pellet furnaces that:

  • BART for NOX emissions was an operating standard of good combustion practices in combination with other process changes to reduce NOX emissions and improve fuel efficiency.
  • BART for PM emissions was equivalent to the requirements of 40 CFR pt. 63, subp. RRRRR (known as Taconite MACT), which requires control of PM emissions to control hazardous air pollutants.
  • BART for SO2 emissions was optimizing the existing control equipment for removal of SO2.

However, EPA partially disapproved Minnesota’s SIP and these requirements have not yet been finalized. EPA agreed with Minnesota’s determination of which sources were subject to BART and that BART for PM emissions from these sources was satisfied by the requirements of the Taconite MACT. However, EPA disapproved the proposed NOX and SO2 limits contained in Minnesota’s SIP, stating that the proposed determinations did not go far enough in controlling NOX and SO2 emissions. As a result, EPA developed a federal implementation plan (FIP) to address the deficiencies in the Minnesota SIP.

On February 6, 2013, EPA promulgated a FIP that included BART limits for taconite furnaces subject to BART in Minnesota and Michigan with an effective date of March 8, 2013. EPA later proposed revisions to this FIP on October 22, 2015, which proposed to revise the BART emission limits and compliance schedules at four taconite facilities identified in the FIP.

On April 12, 2016, EPA finalized the revisions to the FIP and the final rule was effective on May 12, 2016. The rule and applicable requirements can be found in 40 CFR § 52.1235.

Minnesota's initial Regional Haze SIP

The initial SIP was submitted to U.S. EPA on December 30, 2009. Below are several documents that make up Minnesota's original Regional Haze SIP submittal. The documents are divided into smaller files for easier downloading.

In order to complete the SIP process, the MPCA prepared a Supplemental Regional Haze SIP. The supplemental SIP contained additional information and was submitted to EPA on May 8, 2012. Below are the documents that make up Minnesota’s Supplemental SIP submittal.


The SIP included a concept plan focusing on major sources in Northeast Minnesota as one part of its long-term strategy for improving visibility by reducing emissions of SO2 and NOx from major sources in six counties (Carlton, Cook, Itasca, Koochiching, Lake, and St. Louis). As part of the Northeast Minnesota plan, the MPCA has committed to annually tracking emissions from subject sources.