This post is for informational purposes only and does not constitute legal or compliance advice. Consult qualified legal counsel or a compliance professional for guidance specific to your operations and jurisdiction.

Colorado’s ONGAEIR program requires covered operators to file facility-level emissions inventories with CDPHE [1]. The filing deadline is June 30 each year [2]. The 2026 filing covers all calendar year 2025 operations across every covered facility in Colorado [2]. Sixty-eight days remain as of April 23. Regulation 7 requires documented emissions for every regulated source category, including pneumatic devices, storage tanks, fugitive components, and combustion equipment [3]. The verified totals from that inventory feed Colorado’s intensity program; see how the Colorado Reg 7 verification factor works. Late submissions or inventories with material data errors risk enforcement action from CDPHE, including penalty notices. Operators preparing for the deadline should confirm facility applicability, verify source categories, and assemble supporting documentation now.

Quick Answer: Covered Colorado operators must file facility-level ONGAEIR inventories with CDPHE by June 30, 2026, for CY2025. Confirm applicability, verify all source categories, reconcile equipment inventories, and assemble control device documentation before submitting.

Which Facilities Must File ONGAEIR by June 30, 2026?

ONGAEIR applies to oil and gas operators in Colorado whose facilities exceed CDPHE’s applicable reporting thresholds under Regulation 7 [3]. Covered facility types include production wellpads, compressor stations, gas processing plants, and midstream gathering facilities [4]. Operators who filed in prior years already have an applicability determination on record with CDPHE [5].

New filers, or operators who added facilities during CY2025, should confirm applicability with CDPHE before assembling data. Getting applicability wrong wastes weeks. Missing a reportable facility creates a filing gap that is harder to correct after June 30.

ONGAEIR is a Colorado state program, administered independently of the federal EPA Greenhouse Gas Reporting Program (GHGRP) [6]. EPA is reconsidering whether to suspend mandatory Subpart W reporting for reporting years 2025 through 2034. EPA also moved the RY2025 GHGRP deadline from March 31 to October 30, 2026, through an interim final rule (91 FR 2026-03995, February 27, 2026). None of this affects Colorado’s ONGAEIR deadline or reporting requirements.

For operators tracking both programs, the divergence is stark. The federal program’s future is uncertain. Colorado’s June 30 deadline is fixed. A detailed analysis of the federal timeline is available in GHGRP Subpart W Deadline Moved to October 2026.

What Must the ONGAEIR Submission Include?

Each ONGAEIR submission must provide facility-level emissions data across every regulated source category, using emission factors from Regulation 7 or source-specific measurement data. The two main areas where compliance teams encounter filing errors are source category completeness and calculation method inputs.

Which Source Categories Must Operators Report?

CDPHE requires emissions reporting across multiple source categories at each covered facility. Required categories include pneumatic controllers, pneumatic pumps, storage tanks, dehydrators, compressors, fugitive components, and combustion equipment. Several categories require subtype-level detail: controller bleed rates (high-bleed, low-bleed, instrument-air), tank loss types (flash, working, breathing), and compressor vent types (rod packing, seal). Each category has distinct calculation inputs and emission factor tables under Regulation 7.

Equipment counts and emission estimates must be reported at the individual facility level, not aggregated at the lease or unit level. Production volumes must also be allocated to each facility individually. A lease-level production total split evenly across facilities distorts every downstream emission calculation.

Which Calculation Methods Does ONGAEIR Accept?

Operators may apply Regulation 7 default emission factors or source-specific measurement data for each source category. Gas composition data must reflect conditions at each separation stage within the facility, not a single wellhead analysis applied across all stages. Composition changes as gas moves through separation. Flash emissions from storage tanks and dehydrator emissions both shift with composition at the relevant process point.

Control device efficiency claims require supporting documentation. Manufacturer specifications, maintenance logs, and field test results (where applicable) must be on file for each control device applied to a reported source. A claimed 98% destruction efficiency on an enclosed combustor without supporting records is a documentation gap that CDPHE reviewers can flag. Operators can explore Colorado and Texas facility and emissions data through a 7-day free trial of the TetraSoft Atlas Dashboard, a subscription platform.

What Operators Should Complete Before June 30

Operators who start this process now have enough time to file a clean submission. Operators who wait until June do not.

Step 1: Confirm facility applicability. Verify which facilities meet CDPHE’s CY2025 reporting thresholds [5]. New facilities brought online during the year need their own applicability determination [5].

Step 2: Reconcile equipment inventories. Pull the CY2024 submitted inventory as a baseline and reconcile it against field records, work orders, and SCADA configurations for every mid-year equipment change during CY2025. Document the effective date of each change. The date determines how many months of emissions are attributed to each piece of equipment.

Step 3: Allocate production volumes by facility. Confirm that oil, gas, condensate, and water volumes are assigned to each reporting facility individually for the full CY2025 period. Lease-level aggregates are not acceptable.

Step 4: Verify gas composition at each separation stage. Confirm that composition analyses reflect conditions at each process point during CY2025. If any analysis is older than 12 months, schedule an updated sample before running emission calculations.

Step 5: Collect emission calculation inputs. Gather operating hours, fuel gas consumption, pneumatic controller bleed rates, and tank parameters for each source category at each facility. Use CY2025-specific values, not carried-forward defaults.

Step 6: Assemble control device documentation. Compile manufacturer specs, CY2025 maintenance records, and field test results for every control device applied to a reported source. Claimed efficiencies must trace to records on file.

Step 7: Run internal QA before submission. Review the completed inventory for arithmetic errors and missing source categories. Check equipment counts against field records before submitting through CDPHE’s system. Submit by June 27 to allow time for system confirmation. Retain all supporting documentation alongside the submission receipt.

A detailed month-by-month breakdown of this preparation sequence is available in Colorado ONGAEIR 2025 Annual Inventory: Your Q2 Deadline Timeline.

Frequently Asked Questions

Does ONGAEIR apply to midstream operators in Colorado?

ONGAEIR applies to midstream operators whose Colorado facilities exceed CDPHE’s reporting thresholds under Regulation 7 [3]. Covered midstream facility types include compressor stations and gathering facilities [5]. The June 30 filing deadline is the same for midstream and upstream operators [2]. Operators uncertain about midstream applicability should contact CDPHE’s Air Pollution Control Division for a determination.

Can operators file an amended ONGAEIR submission after June 30?

CDPHE’s ONGAEIR program includes provisions for amended submissions after the initial filing [5]. Self-identified corrections filed proactively carry a different risk profile than errors CDPHE discovers during its own review. Operators who find data errors after filing should submit corrections promptly rather than waiting for an agency inquiry. Consult qualified compliance counsel before filing amendments that change reported emission totals.

How does ONGAEIR differ from GHGRP Subpart W?

ONGAEIR is a Colorado state program administered by CDPHE under AQCC Regulation 7. GHGRP Subpart W is a federal program under 40 CFR Part 98 with a 25,000 metric ton CO2e applicability threshold. EPA is reconsidering Subpart W reporting requirements through 2034. Colorado’s ONGAEIR operates independently and is unaffected by changes to the federal program. Operators filing under both programs should track the two timelines separately.

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References

  1. Colorado Department of Public Health and Environment (CDPHE), “Oil and Natural Gas Sector Emission Inventory and Reporting (ONGAEIR) Program,” Air Pollution Control Division. URL: https://cdphe.colorado.gov/oil-gas-sector-emission-inventory-and-reporting-ongaeir
  2. Colorado Air Quality Control Commission, Regulation 7, Part B (5 CCR 1001-9), “Emissions from Oil and Natural Gas Operations.” Colorado Secretary of State.
  3. CDPHE, “ONGAEIR Reporting Instructions,” Air Pollution Control Division, revised 2025.
  4. CDPHE, “ONGAEIR Program Guidance,” Air Pollution Control Division, revised 2025.
  5. U.S. Environmental Protection Agency, 40 CFR Part 98, Subpart W, “Petroleum and Natural Gas Systems.”
  6. EPA, “Extending the Reporting Deadline Under the Greenhouse Gas Reporting Rule for 2025,” Federal Register, 91 FR 2026-03995, February 27, 2026. URL: https://www.federalregister.gov/documents/2026/02/27/2026-03995/extending-the-reporting-deadline-under-the-greenhouse-gas-reporting-rule-for-2025