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Jonah Field

Jonah Energy inspector Cesar Diaz walks through a natural gas well site in 2014 in the Jonah Field south of Pinedale. Wyoming is considering statewide ozone protections similar to those in the Upper Green River Basin. 

The Upper Green River Basin made it through winter this year without a single action day to prevent ground level ozone from forming, compared to a surprising spike of precautions the previous winter, officials say.

Ozone is the principle component of smog, and is created when sunlight and temperature conditions interact with contaminants like car exhaust and emissions from oil and gas production. It’s a hazardous pollutant and became a common problem in the Upper Green as oil and gas activities in the region increased years ago. Poor air quality conditions more akin to areas like Los Angeles than Wyoming prompted stricter guidelines on industry that apply only to the Upper Green River Basin.

With proposals in the wings like a 5,000-well project in eastern Wyoming, environmental groups are pushing for some Upper Green standards to apply to the entire state. Regulators have not indicated any intention to do so, and industry groups say the cost exceeds the gain.


Snow cover is a key ingredient causing ground level ozone to form in winter, and the limited snow this year was likely the biggest reason for the lack of high ozone days, said Brian Hall, natural resources program manager at the Department of Environmental Quality.

Last year was an anomaly, he said. Ozone levels exceeded federal standards six days in the Upper Green last winter, and on at least 12 days state regulators identified conditions for potential ozone, instituting action days when oil and gas firms decreased activity. It was the first year the region had experienced ozone levels above safe standards since 2011.


The Upper Green carries particular risks for ozone spikes. The surrounding mountain ranges keep pollutants from oil and gas activity in the Jonah and Pinedale Anticline fields from escaping. A lack of wind and regular snow pack increases the risk of ozone formation.

Wyoming’s strongest air quality standards apply solely to the Upper Green area as a result. Oil and gas firms perform on-the-ground checks of infrastructure every quarter, use infrared equipment to identify leaks and participate in low activity days when regulators forecast potential ozone spikes.


Emissions regulations and air quality controls have taken center stage over the last year given the controversy surrounding new Bureau of Land Management regulations on oil and gas activity. The BLM’s methane waste and reduction rule has been before Congress and the courts numerous times in the last year and is currently being revised by federal regulators.

Many of its rules mirror Wyoming’s Upper Green River standards, such as quarterly checks on infrastructure.

With those rules likely to disappear, environmental groups in Wyoming want the state to increase its own standards, making the Upper Green approach a statewide minimum.

“The concern is not just ozone,” said Dan Heilig, senior conservation advocate at the Wyoming Outdoor Council, noting that the conditions in the Upper Green are unique. “Nonetheless, that doesn’t really negate the need to do a better job of reducing emissions.”

The Wyoming Oil and Gas Conservation Commission recently reported it had a record 10,000 applications for permits to drill on file, many for activity in the Powder River Basin on the eastern half of the state. Large projects like the Converse County Oil and Gas proposal have instigated pushback from environmental groups who say the 5,000-well project would degrade air quality in the Powder River Basin.

The Wyoming Outdoor Council recently published a report calling on the state to increase its standards before conditions degrade in places like the Powder River Basin, with a particular interest in the leak detection and repair that is required in the Upper Green.

“It seems from our perspective to make a lot of sense,” Heilig said.

Industry is not interested in seeing the Pinedale standards applied to areas like the Powder River Basin.

A better approach would be to align some of Wyoming’s standards with federal rules from the Environmental Protection Agency, like twice-a-year checks of infrastructure, said John Robitaille, vice president of the Petroleum Association of Wyoming.

Making the Pinedale approach statewide would be too expensive, he said.

“It just doesn’t make economic sense,” he said. With every additional on the ground check, a company spends more money but finds less to fix, he said.

Industry is also concerned by a number of assumptions about how much gas is being vented or flared and how much could be captured with stricter rules. Pipelines and infrastructure to catch additional gas does not exist in many areas of the state, he said.


The Department of Environmental Quality is not currently pursuing an update to its air quality regulations in response to environmental pushback, said Keith Guille, a spokesman for the department.

The Upper Green standards are in place because of the unique problems that the region has faced. Dangerous air quality levels are not present in other areas of the state, he said.

“We haven’t seen those types of levels that we saw in (Pinedale),” Guille said. “Not even close.”

The Department of Environmental Quality and Wyoming Department of Health will hold a post ozone season meeting for the public at 6 p.m. May 2, at the Hampton Inn in Pinedale.

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Follow energy reporter Heather Richards on Twitter @hroxaner


Energy Reporter

Heather Richards writes about energy and the environment. A native of the Blue Ridge Mountains in Virginia, she moved to Wyoming in 2015 to cover natural resources and government in Buffalo. Heather joined the Star Tribune later that year.

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