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WI · EPA Region 5

Wisconsin Air Permits

Wisconsin DNR requires a construction permit before anyone builds, reconstructs, modifies, relocates or replaces an air pollution source. Minor sources are covered by NR 406, PSD by NR 405, and nonattainment NSR by NR 408. Facilities also need an operation permit (NR 407) unless they are exempt. The construction exemptions in NR 406.04 are judged project by project. The operation exemptions in NR 407.03 are judged for the whole facility. Streamlined options include registration operation permits Types A, B, C and G, and general permits for hot mix asphalt plants and rock crushing. Major sources need a Title V (Part 70) permit. Non-Title V operation permits issued after December 2015 generally do not expire. Fees are set in NR 410. Parts of southeastern Wisconsin are ozone nonattainment areas.
Verified against agency sourceLast reviewed 2026-10-25

Air permits & authorizations

  • General exemptions (MTE-based)

    Exemption

    These exemptions are based on maximum theoretical emissions (MTE) of each pollutant. For construction they are applied to the project; for operation they are applied to the entire facility. Air toxics must also fall below the NR 445 Table A, B or C values, based on stack height. Exempt sources may still need to notify DNR on Form 4530-100.

    Quoted verbatim from the agency source
    9.0 pounds (lb) per hour of sulfur dioxide or carbon monoxide; 5.7 lb/hr of particulate matter (PM), nitrogen oxides (NOx) or volatile organic compounds (VOC); 3.4 lb/hr of PM less than 10 microns in size (PM10); 2.2 lb/hr of PM2.5; 0.13 lb/hr of Lead (Pb)
    NR 406.04(2); NR 407.03(2)Official page

  • Specific source-category exemptions

    Exemption

    Size-limited exemptions for gaseous-fuel boilers, restricted-use reciprocating engines, painting/coating/graphic arts/refinishing, cold cleaning, dry cleaning, grain storage, grain processing, and gasoline dispensing. A facility may combine categories for an operation exemption only if NR 407.03(1)(t) lists them.

    Thresholds (summarized from source, not a quotation)

    Restated from DNR: boilers under 25 MMBtu/hr total; engines under 3,000 kW total electric output; coating no more than 1,666 lb VOC/month before controls; cold cleaning 1.0 m² or less air-to-vapor interface; dry cleaning 75 lb clothes/hr total; grain storage under 5,500 tons/month received; grain processing under 4,500 tons/month.

    NR 406.04(1); NR 407.03(1)Official page

  • Actual-emissions and natural minor exemptions

    Exemption

    Three exemptions are available. The controlled actual emissions construction exemption (NR 406.04(1q); fact sheet AM-387) and the actual emissions operation exemption (NR 407.03(1m); fact sheet AM-388) are each explained in a DNR fact sheet. The natural minor operation exemption (NR 407.03(1s)) is not available to a facility whose MTE exceeds Part 70 major source levels. NR 406.04(4) lists exclusions from the definition of modification.

    NR 406.04(1q); NR 407.03(1m); NR 407.03(1s)Official page

  • Registration Operation Permits (Types A, B, C, G)

    Registration / Notice

    These are streamlined operation permits for small emitters. Type A (ROP-A) is the simplest option. Type B (ROP-B) has higher eligibility thresholds. Type C (ROP-C) is for printers. Type G (ROP-G01/G02) is for Green Tier participants. DNR must review each application within 15 days, and the annual fee is $400.

    Quoted verbatim from the agency source
    Facilities must have emissions below 25% of the major source threshold for both criteria and hazardous air pollutants.

    Thresholds (summarized from source, not a quotation)

    Type A: below 25% of major source thresholds (criteria and HAP). Type B: below 50% (criteria and HAP). Type C: below 25% for criteria pollutants and 50% for HAP. Type G: below 80%, plus Green Tier Tier 2 status (verbatim percentages from DNR's Registration Permit Options page).

    Official page

  • General Construction and Operation Permits

    General Permit

    General permits cover hot mix asphalt plants and nonmetallic mineral (rock crushing) plants, and DNR's options page also lists printers. General operation permits do not expire, and DNR must decide within 15 days of submittal. Replacing a primary crusher, or an asphalt plant's drum and burner at the same time, requires a construction permit.

    Official page

  • Construction Permit (minor source)

    Minor NSR

    A construction permit is required before construction, modification, expansion or replacement of a source. DNR's preliminary decision is due within 90 days of a complete application for minor sources, or 120 days for major sources, followed by a 30-day public comment period. Authority to construct lasts 18 months, with one 18-month extension. Fees: a $7,500 application fee is credited against the review bill; minor source review costs $3,000 base plus $800 per emission source when two or more are reviewed, $1,000 for an air quality analysis, and $5,000 for optional expedited review. A construction waiver for undue hardship (NR 406.03(2)) costs $300. Construction permit revisions under NR 406.11(1) use a 21-day notice period.

    NR 406; NR 410 (fees)Official page

  • Operation Permit (non-Part 70 minor and synthetic minor)

    State Operating

    An operation permit covers the entire facility, and it is required unless the facility is exempt. A synthetic minor accepts limits that keep it under major source levels; limits below the SM80 band are classed as SM, with lower fees. Non-Title V permits issued after December 2015 generally do not expire.

    Quoted verbatim from the agency source
    Anything between 99 tons per year and 80 tons per year is called SM80
    NR 407Official page

Major NSR (PSD & nonattainment)

  • Prevention of Significant Deterioration (PSD)

    PSD

    This permit covers major sources and major modifications in areas that meet the NAAQS. The DNR pages reviewed do not state numeric PSD thresholds; see ch. NR 405.

    NR 405Official page

  • Nonattainment NSR

    Nonattainment NSR

    This permit applies to the 2015 ozone nonattainment areas: all of Milwaukee and Ozaukee counties, parts of Washington, Waukesha and Racine counties, and parts of Sheboygan and Kenosha counties. DNR says it is generally more stringent than PSD. A Serious reclassification was stayed by the Seventh Circuit on Sept. 5, 2025, so Moderate requirements currently apply.

    Quoted verbatim from the agency source
    the NNSR major source threshold of 100 tons per year

    Thresholds (summarized from source, not a quotation)

    Existing major sources: a project triggers NNSR if its increase exceeds 40 tpy. A Serious reclassification would lower the major source threshold to 50 tpy (restated from DNR).

    NR 408Official page

Title V operating permits

  • Title V (Part 70) Operation Permit

    Title V

    Required for major sources. The permit has a five-year term, and renewal applications are due at least 6 months and no more than 18 months before expiration. Annual fees follow the Title V fee schedule.

    Quoted verbatim from the agency source
    any single criteria pollutant (PM, SO2, NOX, CO) or volatile organic compounds (VOC) above 100 tons per year ... a single federally regulated hazardous air pollutant above 10 tons per year ... total of all federally regulated hazardous air pollutants above 25 tons per year
    NR 407Official page

Oil & Gas

Wisconsin has no oil and gas production air permit program in DNR's air permit pages. Industrial (frac) sand mines and processing plants use the standard construction and operation permits and the nonmetallic mineral general permit.

    Oil & Gas industry hub

    State air regulations

    Forms

    Guidance

    Compliance

    State compliance obligations (reporting, emissions inventory, testing) are being indexed. Use the Compliance dashboard preview to see how they will be tracked.

    Sources

    Editorial note: The exemption thresholds and Title V thresholds are quoted from DNR pages. The PSD numeric thresholds were not shown on the pages reviewed; see NR 405. Registration eligibility is stated only as percentages of major source thresholds. EPA's 'CAA Permitting in Wisconsin' page would not load during review, so the absence of local or tribal permitting authorities is unconfirmed. NR chapter titles are standard titles and should be checked against the Legislature's code site.

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