Northwest Wyoming’s Upper Green River Basin has a number of things in abundance. Two of those are wind and sagebrush. Two more are natural gas and ozone pollution. And as Wyoming moves toward new air quality rules, we’re learning more about how those four things are related.
Wyoming regulators and the oil and gas industry have done a “pretty amazing” job of rolling back some major pollution problems, says Russell Schnell, a scientist for the National Oceanic and Atmospheric Administration. But ozone pollution is also driven by meteorology, he says, and that’s where the Upper Green holds a few natural aces.
The basin lies between the Wind River Mountains and the Wyoming Range and provides billions of dollars in natural gas each year. Most of that comes from the Jonah Field, which hosts thousands of wells and their attendant pipelines, evaporation ponds, compressor stations and other infrastructural bits and bobs. All of that plumbing can leak natural gas, a which includes methane and volatile organic compounds, or VOCs, which are pollutants that help cause ground-level ozone—better known as smog.
In the Upper Green, that smog is worst in winter, a problem that confused scientists at first because smog typically gets along well with hot, summer weather. What Schnell and other researchers have found, though, is an interesting high-country cocktail that leads to smog. In the basin, that meant ozone that surpassed federal health standards between 2008 and 2011 and smog that looked like it came from a big city. Since then, the air has gotten better, but now a state advisory board, environmental groups and industry are all trying to agree on plans to keep it that way, or even improve it.
Turns out, they’re getting an extra hand from the state’s oft-bemoaned wind and monotonous sage. Here’s how.
Ozone is created when sunlight heats up the atmosphere where VOCs are present. On the high plains in winter, the snow reflects sunlight “like a mirror,” Schnell says, which boosts its power, warming the air and leading to winter smog. That smog is helped along by an inversion layer of still air, only a few hundred feet high, where the VOCs help create ozone.
Much of Utah’s current smog problem can be linked to these same phenomena above the Uinta Basin’s gas fields. But the Upper Green is different in a few key ways. The basin is open to the south, which allows for that famous, lonesome wind. And the widespread sagebrush grows high enough so that it’s not snowed over. This breaks up the snow’s mirror, dampening the heat that makes winter smog. Meanwhile, the wind disperses the air, either carrying away the ozone or preventing the inversion layer where it thrives.
Schnell says Wyoming’s air quality division—which is currently holding public meetings as it moves toward air quality rules in the Upper Green—has done a good job of pushing for regulations, while industry has been amenable to changes. Meanwhile, he says, Wyoming is “meteorologically lucking out.”
Brian Calvert is the associate editor of High Country News. He tweets @brcalvert.
This article was originally published in High Country News (hcn.org). The author is solely responsible for the content.