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Class I areas in and near Wisconsin [PDF].
Wisconsin counties within 300 km of Class I areas [PDF].
Contact information
For information about tribal Class I areas, contact:
Marty Burkholder
Air Management Program
For information about federal Class I areas, contact:
John Roth
Air Management Program

Prevention of Significant Deterioration (PSD) Class I Areas

Class I areas receive extra protection from the impacts of air pollution. The classification was established under the Clean Air Act Prevention of Significant Deterioration (PSD) program to limit the amount of additional pollution to these areas resulting from construction or modification of major sources of air emissions.

The Class I areas in Wisconsin are Rainbow Lake Wilderness Area in Bayfield County and the Forest County Potawatomi Community (FCPC) Reservation located near Crandon. Class I areas in neighboring states include the Boundary Waters Canoe Area Wilderness and Voyageurs National Park in northern Minnesota, and Seney National Wildlife Refuge and Isle Royale National Park in northern Michigan. The Bad River Band of Lake Superior Chippewa (located near Ashland, Wisconsin) and the Fond du Lac Band of Lake Superior Chippewa (located in Minnesota approximately 20 miles west of Superior, Wisconsin) are pursuing redesignation of their reservations to Class I status.

Background: PSD classifications

The PSD regulations were devised by the U.S. Environmental Protection Agency (EPA) in order to permit economic growth in a manner consistent with the preservation of air quality in areas meeting the National Ambient Air Quality Standards (NAAQS). The level of air quality protection depends on the area's classification: Class I, Class II or Class III. Class I status allows the most protection of air quality. Most areas throughout the United States are Class II areas. There are no Class III areas.

There are three types of Class I areas: mandatory federal, federal and non-federal. The Clean Air Act designated 158 areas in the United States as mandatory federal Class I areas. These areas include international parks, national wilderness areas larger than 5,000 acres, national memorial parks larger than 5,000 acres and national parks larger than 6,000 acres. Mandatory federal Class I areas may not be reclassified to Class II or Class III areas. In addition, states and tribes can request that EPA redesignate additional areas to Class I status. The process for redesignation includes notifying and consulting with affected governments, preparing a technical support document and holding a public hearing. If approved by EPA, the redesignated area becomes a federal Class I area if it includes a national park or wilderness area or a non-federal Class I area if it includes state or tribal lands.

Map showing Class I areas in Wisconsin.

Requirements for major construction and modification near Class I areas

A PSD permit is required for the construction of a new major air emission source or modification of an existing major air emission source. Any PSD source located within 300 kilometers (km) of a Class I area that is undergoing a major construction or modification project should contact the area's land manager so that the source's potential impacts on the area can be assessed as part of the permitting process.

The PSD program prevents air quality deterioration by defining maximum allowable increases in ambient pollutant concentrations, referred to as increments. Increments have been established for four air pollutants - sulfur dioxide, nitrogen oxide, coarse particulate matter and fine particles. The increments vary by class. Class I increments are the smallest, and therefore the most protective of air quality. PSD sources must not contribute to violation of any increments.

Class I land managers can also establish Air Quality Related Values (AQRVs), which are the unique attributes of a Class I area – such as vegetation, water and visibility – that warrant protection from the impacts of air pollution. The land managers establish pollution thresholds (Threshold Effect Levels or TELs) to protect AQRVs. PSD sources may not exceed the applicable thresholds.

Rainbow Lake Wilderness Area Mandatory Federal Class I Area

Any PSD source located within 50 km of the Rainbow Lake Wilderness Area that is undergoing a major construction or modification project must perform a significance analysis for the increase in emissions. For each pollutant, the maximum impact for each time period is compared to the respective Class I significant impact level (SIL). If the impact of the increase in emissions is less than the SIL for all pollutants, the source is presumed to not contribute to violation of the PSD increments and no further increment analysis is required.

The Rainbow Lake AQRVs and associated thresholds are listed on the U.S. Forest Service website [exit DNR]. Rainbow Lake is one of only two mandatory federal Class I areas in the country where visibility is not an AQRV (Bradwell Bay Wildlife Area in Florida is the other). Consequently, air permit applications do not need to include an air quality visibility analysis for Rainbow Lake.

Forest County Potawatomi Community Class I Area

Effective May 29, 2008, the Forest County Potawatomi Community (FCPC) Reservation located near Crandon, Wisconsin, was redesignated by U.S. EPA as a non-federal Class I area. Prior to the re-designation, the state of Wisconsin and FCPC signed a 1999 Class I Final Agreement [PDF] that resolved the dispute between the state and the FCPC regarding the re-designation. The agreement also outlines implementation of Class I status for the FCPC Reservation.

According to the 1999 Class I Final Agreement, the DNR will notify the FCPC of all new proposed PSD permit applications for facilities located within a 62-mile radius of the FCPC Class I area and these facilities may be subject to an AQRV effects analysis. The FCPC is responsible for performing the analysis, although the state may require the permit applicant to perform the analysis as part of a complete application. In either event, the permit applicant is required to provide all information necessary to conduct or review an AQRV effects analysis. For facilities outside the 62-mile radius, DNR recommends that PSD applicants contact the FCPC air program manager to determine if FCPC may assert that the facility will have an impact on the community's Class I AQRVs.

In addition to notification requirements for PSD permit applications, the Final Agreement includes the following provisions:

  • Class I increment analysis and consumption is limited to sources located within a 10-mile radius (22.25 miles from the geographic center) of the Class I area; and
  • a Scientific Review Panel (SRP) is available to resolve scientific and technical disputes between the state and tribe related to AQRV effect analyses.

The FCPC Class I area, as defined by U.S. EPA, and the 10-mile and 62-mile boundaries are shown in this map [PDF].

In October 2010, the DNR and FCPC signed a Memorandum of Understanding [PDF] to further define the roles and responsibilities for the state and the tribe that were established in the 1999 Final Agreement. The DNR and FCPC have subsequently signed several addendums to the memorandum. The third and fifth addendums list the AQRVs and associated thresholds that have been recognized by the DNR.

The state PSD and construction permit rules include provisions for the FCPC Class I area. Section NR 405.19, Wis. Adm. Code [exit DNR], addresses the increment and AQRV effects analyses. Pursuant to s. NR 406.08(4), Wis. Adm. Code [exit DNR], FCPC may also review best available control technology (BACT) determinations made under ch. NR 445, Wis. Adm. Code, or case-by-case maximum achievable control technology (MACT) determinations for new or modified sources, including non-PSD sources, located within specified distances of the Class I area.

To learn more about the FCPC Class I Area, refer to the Air Permitting page of the Forest County Potawatomi Community [exit DNR] or contact the following FCPC and DNR staff:

Bad River Band of Lake Superior Tribe of Chippewa Indians proposed Class I Area

In May 2014, the Bad River Band notified the State of Wisconsin of its intent to request that U.S. EPA change the air quality status of its reservation in northern Wisconsin from Class II to Class I under the federal Clean Air Act.

Fond du Lac Band of Lake Superior Chippewa proposed Class I Area

In August 2014, the Fond du Lac Band of Lake Superior Chippewa notified the DNR of its intent to request that the U.S. EPA change the air quality status of its reservation from Class II to Class I under the federal Clean Air Act. The reservation is located in northeastern Minnesota approximately 20 miles west of Superior, Wisconsin.

Last revised: Friday December 18 2015