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Permitting Requirements for Nonattainment Areas in Wisconsin

Areas that currently are or have been designated as being in "nonattainment" of a national ambient air quality standard (NAAQS) have more restrictive permitting requirements and sources in those areas may be subject to more stringent regulations known as Reasonably Available Control Technology (RACT) standards. This page shows current Wisconsin nonattainment areas and summarizes the applicable permitting requirements for major sources of emissions within these areas. Information about nonattainment area history is provided to assist in determining RACT applicability for specified sources of nitrogen oxides (NOx). This information is intended to provide an overview of the applicable requirements. Contact the Air Management Program for more detailed information about RACT applicability, state permitting regulations or with questions related to a specific permit situation.

Interactive Map

Click on a county below for a summary of the applicable major source permitting requirements based on nonattainment area designations. The map also provides relevant information for determining NOx RACT applicability.

Please note: To see applicability information for an address, type a specific address into the search bar on the map and then click on the map. Graphical representations of attainment/nonattainment areas are approximate.

Explanation of Information Provided in the Map Legend

Major Emission Sources

Major emission sources for construction permitting purposes in areas that meet or attain the NAAQS are covered by the prevention of significant deterioration (PSD) program. In contrast, major emission sources in nonattainment areas are covered by the nonattainment new source review (NNSR) program.

In general, the NNSR program is more stringent than the PSD program because the goal of NNSR is to improve air quality to attain the NAAQS. The emissions threshold for determining whether a source is subject to major source permitting is usually lower for NNSR than PSD. Projects covered by PSD are required to control emissions to a level defined as best available control technology (BACT), which allows consideration of economic feasibility of the controls. However, projects covered by NNSR are required to control emissions to the level defined as lowest achievable emission rate (LAER), which cannot, by law, consider costs.

Major construction covered by NNSR also requires the permit applicant to offset the project's emissions according to a ratio that depends on the severity of nonattainment. Permit applicants can use internal offsets by establishing emission reductions from their own operations, or an applicant can use emission reduction credits. The offsets must represent surplus, permanent, quantifiable and federally enforceable emissions reductions.

Based on nonattainment status, the map above shows which permitting program currently applies in each area in Wisconsin, along with the associated major source threshold and offset ratio (as applicable).


Nitrogen oxides (NOx) RACT requirements apply to facilities located in certain areas that are or have been classified as Moderate, Serious, Severe, or Extreme, and emit NOx emissions above an applicability threshold. The level of nonattainment classification determines the applicability threshold. More information on emission regulations and applications is available on the NOx RACT page.

More information

Refer to air permit options for more information about construction permits.

Contact Information

For more information on major source permitting thresholds, contact:

Kristin Hart
Air Permits and Stationary Source Modeling Section Chief

For more information on state implementation plans (SIPs), control strategies and current air quality, contact:

Jason Treutel
Air Quality Planning and Standards Section Chief