After oil and gas drilling ramped up on Wyoming’s Pinedale Anticline in 2000, Perry Walker, a retired Air Force physicist and amateur astronomer, noticed that the once crystal-clear night skies were becoming hazy. Even with a telescope, Walker could hardly see some of the stars and galaxies with which he’d become familiar during his 16 years in the area.

When Environmental Protection Agency officials came to Pinedale this January to look into complaints that drillers had violated environmental standards, Walker accompanied them on a van tour of the nearby gas fields. Walker discussed air quality issues with a staffer on the ride back to town. “I gave him a lengthy dissertation on why I objected to the (agency’s) heavy reliance on computer modeling for air quality,” he remembers. “Their code has some Achilles’ heels. And there needs to be empirical measurements to validate these models.”

At lunch, Walker says he stated his position directly to Robert “Robbie” Roberts, the now-former head of EPA’s Region 8 in Denver, Colo. “He listened and said, yes, I understand what you’re saying.”

Just a few weeks after that van tour, Roberts sent a letter of reckoning to the Wyoming BLM office. He took the agency to task for not adequately controlling the impacts of expanded drilling on Pinedale’s air and water quality.

By the time he retired in June, Roberts had won the respect of conservationists around the West for his stance on energy production. The industry-friendly Bush administration has imposed few restrictions on oil and gas drillers, allowing companies largely unfettered access to Western public lands. Roberts’ criticism of the BLM bucked the administration right in Vice President Dick Cheney’s home state. “Such an act is pretty rare overall and exceedingly rare in (this) administration,” says Peter Aengst of The Wilderness Society in Bozeman, Mont. “His letter created quite a stir.”

Despite numerous requests, Roberts declined an interview with High Country News this spring. In May, he took a month off for knee surgery. Then, on June 17, Roberts abruptly retired. An EPA spokesman says he plans to spend time with his family in Alabama.

His departure was preceded by the May resignation of another top EPA official. Mary Gade, formerly administrator for the Midwest’s Region 5, left the agency after she  pushed for Dow Chemical to be held accountable for dioxin pollution in Michigan. Allegedly, administration appointees forced her to quit after she spoke out in an interview with the Chicago Tribune. Agency critics fear that her resignation will dampen other EPA administrators’ willingness to take strong anti-industry positions. And Roberts’ sudden departure could cast a further chill.