Tracking Changes to Basin-wide Pollutant Emissions

Project Updates

Updated March 2026

• Major Findings:
  • Measurements show that methane emissions from oil and gas activities in the Uinta Basin have decreased over time. This long-term monitoring helps track changes in emissions and provides important information for understanding trends in regional air quality.
    
    
  • The analysis is still ongoing, but early results suggest that emissions of organic compounds and nitrogen oxides (NOx) in the region have also decreased over time. Continued analysis will help confirm these trends and improve understanding of how emissions are changing.
    
    
  • The observed decreases in emissions appear to be the result of a combination of regulatory requirements and voluntary actions taken by industry to reduce pollution. These efforts have likely contributed to improved air quality in the region over time.
    
    
• Current and Upcoming Work:
  
  • Data expected to become available in April or May will allow us to complete a basin-wide estimate of emissions for the year 2025. This analysis will provide an updated picture of overall emissions across the Uinta Basin and help track how they are changing over time.
    
    
  • We are also exploring alternative approaches that use satellite observations available through Google Earth Engine. These methods could provide additional ways to estimate emissions across the region and help complement ground-based measurements.
  • This spring, we will complete a more comprehensive evaluation of long-term trends in organic compounds and nitrogen oxides (NOx). This analysis will help provide a clearer picture of how these important air pollutants have changed over time in the region.
    
    
  • A peer-reviewed scientific paper describing the long-term trends in methane emissions is currently in preparation and is approximately halfway complete.
• Problems:
  • None to report.

More Information

 

Changes to Basin-wide Pollutant Emissions

We believe that tracking changes in Uinta Basin air quality and emissions over time will be valuable for research and policy decisions. Tracking changes in emissions over time allows us to understand whether changes in industry practices and regulations are effective, and it allows us to investigate the root causes of the changes.  We have been reporting on changes in emissions over time in our annual reports (Lyman et al., 2024a).  We have also used two methods to assess methane emissions at the Basin scale.  The first method is detailed in a final technical report to the Utah Division of Air Quality (Lyman et al., 2024b), which builds upon a method pioneered by Lin et al. (2021).  The Lin et al. method calculates top-down, Basin-wide methane emissions estimates from observed enhancements of methane at Horsepool relative to Fruitland, an upwind baseline site with little influence from local emission sources. The residence time of air parcels measured at Horsepool, and the resulting sensitivity of Horsepool methane enhancements to Basin emissions, are calculated using the Stochastic Time-Inverted Lagrangian Transport (STILT) atmospheric model, which simulates air parcel transport 24 hours backward in time from the measurement site.  The STILT model is used to calculate emissions from oil and gas facilities that are needed to result in the methane enhancement at Horsepool.  Details of this method are available in the cited references.  In the final technical report, we also estimated emissions of NOx and non-methane organics based on their measured ratio to methane in ambient air.

The second method we used was the Integrated Methane Inversion, which uses methane concentration data from the TROPOMI satellite instrument with the GEOS-Chem photochemical transport model in inverse mode to estimate the emissions required to achieve the methane concentrations observed with TROPOMI.  Details of the Integrated Methane Inversion method are given in Varon et al. (2022) and Varon et al. (2023).  We carried out inversion estimates for Uintah and Duchesne Counties for each two-month period from January 2019 (the first full year that TROPOMI data are available) through December 2024.  We used two-month averaging periods to increase the statistical power of the method.  Each calendar year was run separately, with a 6-month spin-up period prior to the start of each year, and default emissions from the U.S. EPA greenhouse gas emissions inventory were used to initiate each spin-up period. 

Our 2025 annual report details the results of this work so far.  We have also created a web-based data explorer tool to allow stakeholders to access and analyze the collected data on their own (https://ubenergyexplorer.streamlit.app/).

In 2026, we will:

1. Complete methane emissions estimates through 2025
2. Publish this work in a peer-reviewed journal
3. Use the methods established in the previous work to create an emissions time series for NOx and speciated organic compounds from 2013 through 2025, and work towards publishing those results
4. Compare methane emissions trends against oil and gas activity, meteorological conditions, and other parameters to understand the drivers behind temporal changes

We will also connect with stakeholders to make sure they understand and can use the data we collected, and to get their input to ensure our interpretations of oil and gas-related activity are correct.