A former National Park Service director said her bosses in the top ranks of the Interior Department have called all the shots about snowmobiling in Yellowstone National Park, usurping normal channels of decision-making.

Further, Fran Mainella expressed doubt as to whether science, rather than politics, led to a recent decision to allow 540 snowmobiles per day in the park.

Mainella maintained absolute silence about the ongoing controversy for a year after she left the helm of the Park Service, in accord with federal civil service rules. That's why her signature was missing on a March 26 letter to Interior Secretary Kempthorne involving Yellowstone and the issue of snowmobile use within the park.

In that letter, seven past directors of the Park Service wrote to express their alarm and dismay that Yellowstone was considering allowing 720 snowmobiles per day in the park.

"The latest National Park Service study illuminates in detail that allowing Yellowstone's current average of 250 snowmobiles per day to increase - to as many as 720 snowmobiles - would undercut the park's resurgent natural conditions," the former directors wrote. "… It sidesteps a recent recommendation made by Park Service scientists: that in order to minimize disturbance of the park's wildlife, traffic should be kept at or below current levels, not expanded. The study also provides clear evidence that reducing snowmobile numbers still further - from 250 per day to zero - while expanding public access on modern snowcoaches, would further improve the park's health."

Mainella, in a Nov. 19 letter to former Park Service Director George Herzog Jr., wrote, "I now am able to let you know that I would have joined with you and the other former NPS Directors by signing your letter. In fact, through this letter, please consider me an official signatory effective immediately."

Mainella is now a visiting scholar at Clemson University. In a telephone interview from her office, Mainella explained that she would take information about the Yellowstone snowmobile issue to the Interior leadership, and that final decisions would be made there, rather than within the Park Service itself.

She said she had pulled the former directors together into a directors council, within the National Park Service Advisory Board, adding that it was "a great thing to have all that knowledge in one place."

Asked directly if decisions by Interior are driven by science or politics, Mainella said science has an important role, but there are other issues to consider as well, such as access.

Gone from the Park Service for the past year, Mainella said she hasn't been privy to Interior or Park Service discussions. Her purpose in joining with other former directors was to emphasize to the Interior leadership, "You can't ignore the science. There may be other factors that play in, but you cannot allow the science to be ignored," she said.

Mainella said she believes in Park Service leaders and Kempthorne, but doesn't know whether the final decision about Yellowstone snowmobiles "is reflective of the science or not."

She has also been interviewed by Kurt Repanshek, a former Associated Press reporter in Wyoming and co-founder of National Park Traveler, the nation's first blog dedicated specifically to covering the Park Service and the national park system.

Repanshek said in his interview with Mainella, she indicated that she had opposed an attempt by Paul Hoffman, Interior's assistant deputy secretary for fish, wildlife and parks, to rewrite the Park Service's management policies, as well as efforts to outsource Park Service jobs.