DEQ Enhances Efforts, Outreach for 2021 Winter Ozone Season

DEQ Enhances Efforts, Outreach for 2021 Winter Ozone Season

By Mike Morris

Understanding and addressing the formation of winter ozone in the Upper Green River Basin (UGRB) is a unique challenge that requires an abundance of planning, strategy implementation, and collaboration each year.

Ground-level ozone is a harmful air pollutant that forms when precursor pollution emissions react chemically in the sunlight. Winter ozone formation in the UGRB is uniquely influenced by adequate amounts of precursor emissions, snow cover, temperature inversions, low winds, and sunlight.

Together, the Wyoming Department of Environmental Quality’s (WDEQ) Air Quality Division (AQD), the Wyoming Department of Health, industrial operators, environmental groups, and the general public have dedicated years of hard work and focused efforts to addressing elevated ozone formation and improving air quality in the area.

Those efforts continue this winter ozone season.

For 2021, the AQD has furthered its planning and resource commitment for forecasting and monitoring winter ozone, collaborating with operators to enact emission reduction strategies, and notifying the citizens of the UGRB in advance of potential elevated ozone formation. 

The AQD’s expanded strategy includes:

  • The addition of seasonal monitoring
  • Updates to its WyVisNet website
  • Implementation of the Wyoming Pond Emissions Calculator (WYPEC) to estimate emissions from Commercial Oilfield Waste Disposal (COWD) ponds
  • New educational public outreach videos

The AQD led a virtual public meeting December 17 to discuss these updates. The AQD gave a presentation detailing the preparations and public outreach it is undertaking this year, and the meeting also provided an opportunity for members of the public to ask questions of AQD staff. Industrial operators also provided overviews of their preparations and measures they have undertaken to limit emissions.

“We were pleased to have a number of folks from the general public, environmental groups, and industry who attended the meeting,” AQD Administrator Nancy Vehr said.

“We hope it was an informative session for everyone who attended and that we were able to introduce some of the new planning elements for 2021, in addition to covering the ongoing work the AQD has been undertaking in previous years.”

Additional Seasonal Monitoring

The mobile monitoring station located on Paradise Road is intended to help characterize ozone precursor emissions in an area of oil and gas development upwind of the Boulder monitoring station.

Although the station is not located in ambient air – and, as such, its data will not be used for comparison to the national ambient air quality standards (NAAQS) – the monitor will assist the ADQ in its research efforts. Ambient air is defined by the Environmental Protection Agency (EPA) as the portion of the atmosphere to which the general public has access.

The Paradise Road station complements five other long-term monitoring stations in addition to seasonal monitoring in the UGRB. The AQD began monitoring operations in the UGRB in 2005.

WyVisNet Updates

The general public can observe near-real-time air quality conditions and live images from these stations – and stations across the state – at the AQD’s newly refurbished WyVisNet website ( The website’s updates include enhanced functionality with graph illustrations of recent data retrieved from monitoring stations, as well as browser-friendly reports of recently retrieved data.

Cara Keslar, the AQD’s monitoring section supervisor, said, “We are excited about the updates to the website and believe it will provide the people of Wyoming with enhanced accessibility to the air quality data they are seeking.”

She added, “It is a good resource for observing conditions in the UGRB during winter ozone season.”


Implementation of the WYPEC model is also on the horizon in 2021. The AQD held a public input meeting regarding the model on December 15.

The WYPEC model has been in development for several years and will assist the AQD in estimating emissions from COWD ponds and, ultimately, in New Source Review (NSR) permitting of emission sources.

A COWD pond study undertaken from 2015-2018 informed the model. It also helped shed light on how air emissions emanating from the ponds are related to the water composition of the ponds – ultimately assisting with the development of strategies to reduce precursor pollutants that may contribute to winter ozone formation.

Engine Maintenance Assurance Program

The Engine Maintenance Assurance program, which was started in 2020, also continues this season.  In 2020, lessons learned from this program led to the creation of the Upper Green River Basin Engine Maintenance Assurance Best Management Practices. For 2021, the program is focused on engine maintenance and operation challenges for reciprocating internal combustion engines (RICE) in the UGRB. 

Public Outreach

Also new to 2021, the AQD’s Compliance Program’s work in the UGRB is highlighted in an educational YouTube video series, including interviews with both of the AQD’s full-time inspectors in the UGRB.

Lars Lone, the AQD’s Compliance Program manager, said, “The new video series should provide an informative and visual overview of the compliance work we undertake in the UGRB and it’s an introduction to getting to know our compliance inspectors.”

The AQD also continues its longstanding ozone forecasting strategy in 2021. The AQD has two dedicated meteorologists who assess weather models and forecast if meteorological conditions favor potential elevated ozone formation.

These forecasts inform whether or not the AQD will issue an Ozone Outlook or an Ozone Action Day (OAD). Ozone Outlooks inform the general public and industrial operators 48 hours in advance of the possibility of persistent conditions that could favor elevated ozone formation.

Ozone Action Days are issued when forecast conditions appear favorable for elevated ozone formation the following day. This provides advanced notice for industrial operators and the general public to implement voluntary, short-term Ozone Contingency Plan (OCP) measures, which can help minimize ozone precursor emissions and are encouraged by the AQD.

OCPs are submitted in advance to the AQD by operators and the general public, ensuring a proactive approach to identifying specific activities that can be implemented on an OAD. OCPs became a component of winter ozone season strategy in 2013 and are a defining example of collaboration in the UGRB.

It is this prevailing partnership between stakeholders and the AQD that has both grown and endured in the years since winter ozone was discovered in the UGRB in 2005. And those efforts have helped make a difference.

Since 2008, volatile organic compound (VOC) emissions in the UGRB have been reduced by 7,199 tons and nitrogen oxide (NOx) emissions have been reduced by 1,654 tons through permitting measures, as of December 9.

Additionally, in the calendar year 2020, the AQD’s Compliance Program had conducted 745 site visits at 434 unique facilities in the UGRB, finding a 94.9 percent compliance rate. Statewide, 2,382 facilities, including facilities located in the UGRB, have participated in the AQD’s voluntary self-audit program, reducing 6,588 tons per year of NOx and VOC.  

Interested citizens are encouraged to stay up to date during winter ozone season by visiting, where they can sign up to receive email notifications.

Citizens can also visit on the Wyoming Department of Health’s website to learn more about the health effects of ozone.

Additionally, a detailed narrative and summary of the historical work undertaken in the UGRB, entitled UGRB: The Power of Partnership, was published by DEQ in 2018 and is accessible from the download table at


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