Prevention of Significant Deterioration (PSD) Class I Areas

The Prevention of Significant Deterioration (PSD) regulations were devised by USEPA to be more restrictive than the National Ambient Air Quality Standards (NAAQS) in order to permit "economic growth in a manner consistent with the preservation of existing clean air resources...in areas such as national parks, national wilderness areas, national monuments, national seashores, and other areas of special national or regional natural, recreational, scenic, or historic value" (Clean Air Act, 1977). There are two classes of PSD areas in Wisconsin for PM10, SO2 and NOx, designated Class I and Class II. Almost all of Wisconsin is Class II with the exception of the Class I areas denoted below.

Class I areas are areas of special national or regional value from a natural, scenic, recreational or historic perspective. There are three types of Class I areas: mandatory Federal Class I areas; Federal Class I areas; and non-Federal Class I areas. Mandatory Federal Class I areas include international parks, national memorial parks larger than 5,000 acres, and national parks larger than 6,000 acres that were specified in the Clean Air Act on August 7, 1977. Mandatory Federal Class I areas may not be reclassified. Non-Federal Class I areas include those designated by the state or a Tribe. All other areas to which the PSD provisions apply are classified as Class II.

Class I areas are the most stringently regulated, as these are generally locations that have remained untouched by development. The State of Wisconsin has one Mandatory Federal Class I area and one non-Federal Class I area. The Mandatory Federal Class I area is Rainbow Lake Wilderness Area. Rainbow Lake and Bradwell Bay Wildlife Area in Florida are unique among the PSD Class I areas. Both are specified in the USEPA New Source Review Workshop Manual as areas where visibility is not recommended as an important value. Consequently, air quality modeling that includes Rainbow Lake as a consideration does not have to conduct an air quality visibility analysis.

Any PSD source that locates within 50 kilometers of the Rainbow Lake Class I Area must perform a significance analysis for the increase in emissions. In this analysis, the first highest concentration for each time period is compared to the Class I significant impact level (SIL). If the impact of the increase in emissions is less than the SILs for all pollutants, then no further analysis on Rainbow Lake is required.

In addition, any PSD source that locates within 200 kilometers of a Mandatory Federal Class I area must notify the applicable Federal Land Manager. For information regarding a facility's proximity to Class I areas, please click on the following memo and map for more information.

Forest County Potawatomi Community Class I Area

Effective May 29, 2008, a portion of the Forest County Potawatomi Community (FCPC) Reservation was redesignated as a non-Federal Class I area by the US Environmental Protection Agency. Prior to this redesignation, the State of Wisconsin and FCPC signed a 1999 Class I Final Agreement that resolved the dispute between the state and the tribe and outlined provisions for implementation of Class I for the FCPC Reservation.

In 2010, Wisconsin DNR and FCPC signed a Memorandum of Understanding to establish the process for implementing the 1999 Final Agreement. According to the agreement:

• All proposed PSD permits from facilities located within a ten (10) mile radius of the Class I area are subject to an increment analysis and consumption requirements using Class I standards.
• All proposed PSD permits from facilities located outside the 10-mile radius are subject to an increment analysis and consumption requirements using Class II standards, as per standard practice.

FCPC has defined aquatic systems and water quality as existing AQRVs (Air Quality Related Values) for the FCPC Class I Area.  FCPC has identified that acidic deposition and metals deposition (including mercury) have the potential to adversely affect these AQRVs.  FCPC will identify threshold values for the existing AQRVs by July 31, 2012.  Until threshold effects have been established, a Scientific Review Panel (SRP) has the authority to determine if adverse impacts may occur. The SRP will be established jointly by the State and FCPC to review analyses and resolve disputes.

According to the 1999 Class I Final Agreement between FCPC and the State of Wisconsin, all proposed PSD permits from facilities located within a sixty-two (62) mile radius of the FCPC Class I area are subject to DNR notice to FCPC and an AQRV effects analysis.  FCPC is responsible for performing the analysis, but may request the State to 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.WDNR recommends that PSD applicants for facilities outside the 62-mile radius contact the FCPC Air Program Director regarding potential impacts on the FCPC Class I AQRVs.

The FCPC Class I area (as defined by USEPA on May 29, 2008) and the 10-mile and 62-mile boundaries are shown in the map.

Further information related to the FCPC Class I area, please contact:

Natalene Cummings                                                               Steven Dunn
Air Resources Program Director                                            Construction Permit Team Leader
Forest County Potawatomi Community                                  WDNR Bureau of Air Management
Office: 715-478-7211                                                            Office: 608-267-0566
Fax: 715-478-7225                                                                Fax: 608-267-0560
natalene.cummings@fcpotawatomi-nsn.gov                          steven.dunn@wisconsin.gov

Air Quality Modeling