Colorado Air Permits

Air permits & authorizations

• APEN and permit exemptions

  Exemption

  APEN-exempt sources are listed in Regulation 3, Part A.II.D; permit-exempt sources in Part B.II.D (an APEN may still be required).

  Regulation 3, Part A.II.D and Part B.II.DOfficial page

• Air Pollutant Emission Notice (APEN)

  Registration / Notice

  Used to report emissions, apply for a permit, or modify a permit. Compare uncontrolled actual emissions per calendar year (not counting control equipment) to the APEN threshold. Renew every five years or sooner for significant increases or changes.

  Thresholds (summarized from source, not a quotation)

  Per APCD (uncontrolled actual emissions per year), attainment / nonattainment: VOC 2 tons / 1 ton; NOx 2 tons / 1 ton; PM10, PM2.5, TSP, CO, SOx 2 tons; lead 100 lb; HAPs 250 lb.

  Regulation 3, Part AOfficial page

• Construction Permit

  Minor NSR

  Required before constructing a new source or modifying an existing stationary source. Thresholds apply to the whole facility (sum of all APEN-required sources). Initial Approval permit, Notice of Startup within 15 days, and self-certification within 180 days.

  Thresholds (summarized from source, not a quotation)

  Per APCD (total facility uncontrolled actual emissions), attainment / nonattainment: VOC 5 / 2 tons; NOx 10 / 5 tons; PM10 5 tons; PM2.5 5 tons; TSP 10 tons; CO 10 tons; SOx 10 tons; lead 200 lb.

  Regulation 3, Part BOfficial page

• General Permits

  General Permit

  Streamlined permits for qualifying sources: GP01 condensate tank batteries, GP02 natural gas RICE, GP03 land development, GP05 produced water tanks, GP06 diesel engines, GP07 hydrocarbon liquid loadout, GP08 oil and gas storage tanks, GP11 routine gas venting, GP12 oil and gas well production facilities (replaces GP09/GP10).

  Regulation 3, Part BOfficial page

Major NSR (PSD & nonattainment)

• PSD / Nonattainment NSR

  PSD

  Major stationary source review under Regulation 3, Part D (major stationary source defined at Part D, Section II.A.25). The Denver Metro/North Front Range area has been reclassified to severe ozone nonattainment (see PS Memo 22-01).

  Regulation 3, Part DOfficial page

Title V operating permits

• Title V Operating Permit

  Title V

  Required for major sources as defined in Regulation 3, Part A, Section I.B.30, plus Acid Rain sources and certain NSPS sources (e.g., landfills under Subparts Cf and XXX). 30-day public comment and 45-day EPA review; renew every five years.

  10 tons per year or more of any single hazardous air pollutant; 25 tons per year or more of any combination of hazardous air pollutants; 100 tons per year or more of any pollutant subject to regulation. Denver Metro/North Front Range: 25 tons per year or more of nitrogen oxides (NOx); 25 tons per year or more of volatile organic compounds (VOCs).

  Regulation 3, Part C; major source at Part A, I.B.30Official page

Oil & Gas

Colorado has one of the most detailed state oil and gas air programs. Regulation 7 governs oil and gas operations to reduce ozone precursors and methane (storage tank emissions management, LDAR, pneumatic controllers, well liquids unloading, emissions reporting), revised alongside Regulation 22 (greenhouse gases). Oil and gas sources file APCD-200 series APENs, can use oil and gas general permits (GP01, GP02, GP05, GP07, GP08, GP11, GP12), and synthetic minor/major sources need O&M plans. Annual inventory reporting is via ONGAEIR.

• GP12: Oil and Gas Well Production Facilities

  General Permit

  The only facility-wide general permit for constructing and operating new well production facilities; replaces GP09 and GP10.

  Official page

• GP08: Oil and Gas Industry Storage Tanks

  General Permit

  Condensate, crude oil, and produced water storage tanks.

  Official page

• GP02: Natural Gas Fired RICE (oil and gas operators)

  General Permit

  General permit for natural gas engines.

  Official page

• GP07: Hydrocarbon Liquid Loadout

  General Permit

  General permit for oil and gas loadout.

  Official page

• GP11: Routine or Predictable Gas Venting

  General Permit

  General permit for oil and gas venting emissions.

  Official page

• Regulation 7: Oil and gas emission controls

  Other

  Storage Tank Emissions Management (STEM), LDAR including approved instrument monitoring methods, pneumatic controller reporting, well liquids unloading and maintenance, and emissions reporting.

  Regulation 7Official page

• Oil and gas APENs

  Registration / Notice

  APCD-200 series APENs for each reportable emission point.

  Official page

• Oil and Natural Gas Annual Emission Inventory Reporting (ONGAEIR)

  Other

  Annual emissions inventory reporting for oil and gas.

  Official page

State air regulations

• AQCC Regulation 3Stationary Source Permitting and Air Pollutant Emission Notice Requirements (Parts A-D)
• AQCC Regulation 6Standards of Performance for New Stationary Sources
• AQCC Regulation 7Control of Ozone via Ozone Precursors and Hydrocarbons via Oil and Gas Emissions
• AQCC Regulation 22Climate Change and Greenhouse Gas Reporting/Emission Reductions

Forms

• Form APCD-100: Permit Application/Registration Checklist
• Form APCD-101: Company Contact Information
• Form APCD-102: Facility-wide Emissions Inventory
• Index of forms and guidance: oil and gas
• Index of forms and guidance: non-oil and gas

Guidance

• Reporting Your Air Emissions and Applying for Air Permits
• Oil and Gas Emissions Calculation Manual (v3, July 2026)
• Air permitting guidance memos
• Environmental justice in air permitting
• Disproportionately impacted community permitting rule
• Modeling guidance for permits
• PS Memo 22-01: Severe ozone reclassification permitting issues

Compliance

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

Sources

• CDPHE APENs and air permits
• CDPHE General air permits
• CDPHE About Title V
• CDPHE Oil and gas compliance
• CDPHE Oil and gas air permits

Editorial note: CDPHE hosts documents on its official records system (oitco.hylandcloud.com). Regulation titles for 6, 7, and 22 are summarized; confirm exact titles on the AQCC regulations page.