The trees have turned, the wind has kicked up, and our gardens and grass are in survival mode. This can only mean that the year is coming to a close, and 2027 is upon us. For minor sources in Wyoming, 2027 is a triennial emissions inventory (EI) reporting year. The Wyoming Department of Environmental Quality (WDEQ) requires minor sources to report actual emissions for calendar year 2026, with 2026 triennial emissions data due to WDEQ’s Air Quality Division by April 30, 2027. Wyoming’s triennial minor-source inventory supports the statewide emissions reporting conducted under 40 CFR Part 51, Subpart A. WDEQ collects actual emissions information from minor sources as part of this effort and reviews the reported information before emissions data are incorporated into the appropriate database. While we are still several months away from that deadline, it is important to begin getting organized and preparing data to support the RY2026 EI submittal. This article provides a breakdown of the triennial EI process, from beginning the data collection process to submitting via IMPACT, and shares tips and tricks we have identified through our long history of supporting clients with these tasks.
The Emissions Inventory Process
WDEQ strongly prefers that triennial EIs be submitted via IMPACT. Submission of excel files to the agency is allowed, but working directly with the Division is recommended if this option is pursued. EIs are intended to capture the actual emissions from a source that operated during the applicable reporting period (RY2026), so operational data is needed to quantify emissions. Examples of this type of data include throughputs at an oil and gas pad, operating hours of an engine, or total clinker production at a cement plant. Once adequate data is acquired, actual emissions for the sources are calculated utilizing the appropriate emission factors for the source, and data is uploaded to IMPACT. WDEQ also provides a batch-reporting approach for certain oil and gas production-site operators with multiple facilities, allowing data for multiple facilities to be processed for upload into IMPACT. Further guidance and information from WDEQ can be found on its website.
Tips and Tricks for a Successful EI
An emissions inventory is only as good as the data that supports it.
Assemble and Document Your Data
Since WDEQ is interested in actual emissions for the reporting period, operators should assemble the operating and production data needed to develop representative actual emissions calculations and document the basis for those calculations. Good recordkeeping practices and proper maintenance of monitoring equipment both support a thorough and accurate EI.
Start Early
Starting the EI process early leads to a more complete final product. For minor sources, the triennial nature of the program can result in deadlines slipping from industry radars, and it is not uncommon to see last-minute submittals with missing data due to an inadequate amount of time for preparation. Timely commencement of the process allows for data collection and organization well before deadlines loom.
Confirm Your IMPACT Inventory Is Current
Finally, ensuring your facility’s IMPACT inventory is updated is necessary to capture all operating sources to be reported. Because the EI is completed and submitted in IMPACT, the task will rely directly on the latest version of the facility inventory. It is easy to miss updates to the inventory in the three years between EIs, so the accuracy of the inventory must be confirmed prior to completing RY2026’s EI.
How Trinity Can Help
Trinity has a long history of supporting clients in Wyoming with the triennial EI program. Our consultants have close relationships with regional compliance managers and WDEQ staff and understand what the agency is looking for in an EI. Trinity can help ensure your reporting deadlines are met for all affected sites while solving any unforeseen problems along the way.
If your company operates sources in Wyoming, we recommend joining Trinity for a complimentary webinar that will dive into further details of the EI program while also touching on environmental hot topics to consider in the new year. The webinar will be held Thursday, November 12, at 11:00 a.m. Mountain Time.
If you have any questions on how Trinity can assist your company with the triennial EI process or any other environmental needs, please reach out to our Wyoming Operations Manager, Austin Buley, or our local emissions inventory resource, Tyler Ward.
