Subpart W is the part of the EPA’s Greenhouse Gas Reporting Program (GHGRP), 40 CFR Part 98, that covers petroleum and natural gas systems. For most operators, EPA Subpart W 2026 work means the report for reporting year 2025 (RY2025). The EPA proposed ending most of the GHGRP in September 2025 and has since moved the report’s due date.
Is Subpart W being repealed?
No. The EPA proposed on September 16, 2025 (90 FR 44591) to end most of the Greenhouse Gas Reporting Program, and it has not finalized that proposal.
The proposal, titled “Reconsideration of the Greenhouse Gas Reporting Program,” would drop 46 source categories after reporting year 2024. Under Subpart W, natural gas distribution would stop reporting after RY2024, and the other nine segments would pause until RY2034. Comments closed November 3, 2025.
So far the EPA has acted only on the RY2025 deadline. Until it finalizes the proposal, the current Part 98 rules apply, and facilities over the reporting threshold still file. Any final action will be listed on the EPA’s rulemaking notices page.
Companies join OGMP 2.0, the UNEP methane reporting program, by choice. That program sits outside Part 98, and the EPA proposal does not reach it.
What is due, and when?
RY2025 reports are due March 10, 2027, through e-GGRT, the EPA’s electronic Greenhouse Gas Reporting Tool.
The original deadline was March 31, 2026. A final rule published February 27, 2026 (91 FR 9712) moved it to October 30. An interim final rule published October 14, 2026 (91 FR 65112) moved it again, to March 10, 2027, to give the EPA time to review more than 50,000 comments on the proposal. Comments on the new date are open until November 30, 2026.
What changed for the RY2025 report?
Most of the Subpart W amendments published May 14, 2024 (89 FR 42062) took effect January 1, 2025. The RY2025 report is the first to carry them. The optional measured-data methods took effect earlier, on July 15, 2024, and reporters could elect them for RY2024.
Five changes matter most to operators:
- Well-level data. Onshore production and gathering and boosting reporters now report emissions and activity data at the site or well level instead of the basin, sub-basin or county level. 40 CFR 98.236 asks for a well ID in paragraphs such as (f), (h) and (l). Check that unloading, completion and well test records tie to a well.
- Large release events. Reporters account for events with an instantaneous methane rate of 100 kg/hr or more, or 100 kg/hr above what other Subpart W methods estimate. Paragraphs 98.233(y) and 98.236(y) require emissions for the whole event, the equipment involved and the method used to identify it. Check your event log against all three. In the 2024 rule, the EPA said continuous monitoring data may provide an event’s duration.
- New sources. Produced water storage tanks (98.233(j)), nitrogen removal units (98.233(d)), drilling mud degassing (98.233(dd)) and crankcase venting (98.233(ee)) now carry reporting requirements. Confirm each is in your source inventory and pick the method its paragraph allows.
- Measured data. For several sources, reporters may use empirical data in place of population emission factors. These include equipment leaks (98.233(q)), compressors (98.233(o) and (p)) and pneumatic devices (98.233(a)). Decide by source whether to use measured data or a factor, and record the choice.
- Leaker factors. Table W-2 lists leaker emission factors in three columns. Two are for Method 21, at leak definitions of 10,000 ppm and 500 ppm. The third is for OGI, infrared laser beam illuminated instruments and acoustic leak detection devices (98.234(a)(1), (3) and (5)). Match each survey to the column for the method used.
Because the screening method sets the factor, survey records carry more weight than before. Keeping LDAR records in one place makes it quicker to show which method found each leak.
Who has to report?
Facilities that contain petroleum and natural gas systems and emit 25,000 metric tons of CO2e or more per year report under Subpart W. For most segments the 25,000 total is facility-wide. It counts stationary fuel combustion, miscellaneous uses of carbonate and every other applicable source category at the facility, under 40 CFR 98.2(a)(2). Four segments count only their Subpart W sources listed in 40 CFR 98.232: onshore production, gathering and boosting, natural gas distribution and onshore transmission pipeline (40 CFR 98.231(a)). Processing facilities also count the residue gas compression they own or operate.
Subpart W covers ten industry segments under 40 CFR 98.230(a):
- Offshore petroleum and natural gas production
- Onshore petroleum and natural gas production
- Onshore natural gas processing
- Onshore natural gas transmission compression
- Underground natural gas storage
- Liquefied natural gas (LNG) storage
- LNG import and export equipment
- Natural gas distribution
- Onshore petroleum and natural gas gathering and boosting
- Onshore natural gas transmission pipeline
Where are the emission factors for RY2025?
The EPA publishes the Subpart W factors in the rule itself. Tables W-1 through W-6 in 40 CFR Part 98 Subpart W hold the default population and leaker factors, on a whole gas, total hydrocarbon and methane basis. Table W-7 covers internal combustion equipment.
The 2024 amendments replaced the old Tables W-1A through W-1E with a single Table W-1. They also updated the leaker factors in Table W-2 and added a column for OGI, infrared laser beam illuminated instruments and acoustic leak detection devices. An RY2025 report uses the tables as amended.
The EPA’s GHG Emission Factors Hub covers sources such as purchased electricity and mobile combustion. The oil and gas equipment factors are in Part 98.
How do you get the RY2025 report done from data you already have?
Use the months before March 10 to tie the data you already have to its equipment and calculation method once. That work carries into later Subpart W years if the proposal is not finalized as written.
Take equipment leaks as one source type. A survey record carries the component type, the date and the screening method. The method picks the Table W-2 column, and the column gives the leaker emission factor. That factor and the survey counts feed the calculation, and the result goes into the report under 40 CFR 98.236(q). Each step traces back to a record, and every Subpart W report repeats that chain for each source type.
The EPA Subpart W solution in SensorUp Studio brings together a team’s observations, calculations and the audit trail needed for the GHGRP report. The numbers update as the data comes in, and the data connections stay in place from one reporting year to the next, so a rule change means updating the method once, not rebuilding the workbook.
To see that chain on your own equipment, start with a two-day workshop. It runs on a representative sample of your data, such as a few survey or event records for one source type. We trace each sample record to its Table W-2 column and to the value reported under 98.236. We also map it to the RY2025 paragraphs in 40 CFR 98.233.