Wyoming’s Upper Green River Basin breached a key federal barrier for multi-year air pollution limits, forcing federal regulators to demand changes in the area, the Environmental Protection Agency informed state officials Monday.
The EPA said the basin – home to energy development in the Jonah and Pinedale Anticline natural gas fields -- didn't meet federal air quality standards over a three-year testing period from 2008 to 2011, said Steven Dietrich, the air quality administrator for the Wyoming Department of Environmental Quality. The area was designated as marginal, the lowest of five ratings for the severity of the air pollution, he said.
The federal decision didn’t shock state officials, who have been aware of the air pollution testing results from the area.
“We’re not surprised,” Dietrich said. “We’ve known about it for quite some time.”
Due to the decision, the EPA will release a rule that will outline the minimum steps needed to get the area back into compliance, Dietrich said. That rule release is expected in July, he said.
Ozone levels increase as a result of pollution from natural gas drilling and production in the Jonah and Pinedale Anticline fields. In the winter, weather inversions trap volatile organic compounds and nitrogen oxide in the valley along with other pollution.
When there is snow, the volatile organic compounds and nitrogen oxide are exposed to direct sunlight and light reflected from the snow, which causes a reaction that creates ozone.
According to the EPA, ozone can cause health issues such as difficulty breathing, shortness of breath, coughing, sore or scratchy throat, increased asthma attacks and make lungs more susceptible to infection.
The Upper Green River Basin, including Sublette County and parts of Lincoln and Sweetwater counties, averaged ozone ratings of 78 parts per billion for the past three years, Dietrich said.
The national standard for ozone is 75 parts per billion over an eight-hour period. To make sure areas comply with national benchmarks, the ozone reading is taken each year for three years. If the average exceeds 75 parts per billion, the area is designated as reaching what’s known as nonattainment status, Dietrich said.
Readings in recent years have spiked well past the federal limit for nonattainment status.
In 2011, 13 days in the Upper Green River Basin exceeded the eight-hour standard, including a high of 124 parts per billion. The fourth-highest day, which was used in deciding compliance with national standards, was 104 parts per billion.
In 2008, the highest level reached was 122 parts per billion and the fourth-highest was 101, said Keith Guille, spokesman for Wyoming DEQ. In 2009 and 2010, the standard wasn’t exceeded. Data for 2012 is not yet available. Early numbers from the start of this year are expected this summer.
More than 40 areas in the country received letters saying their air quality was not in compliance.