In 2003, Yellowstone will celebrate a centennial. It’s been 100 years since President Theodore Roosevelt dedicated the famous stone archway at the north entrance of the world’s first national park. The Park Service plans to commemorate the event. I wonder what Roosevelt would say if he could attend.

I picture him pounding his fist and demanding of the agency, "What in heaven’s name are you doing?" I think he’d be outraged at the Bush administration and its determination to allow snowmobiles free rein in the park.

"You are compromising Yellowstone," I hear Roosevelt bellowing, "and that was never supposed to happen!"

These are the facts of what is happening: The Park Service has determined that the administration’s plan to continue and even expand snowmobile use in Yellowstone would cause substantially more harm than an earlier decision to phase out the machines. The Park Service believes we can expect a veil of dirty air near Old Faithful, the world’s most famous geyser; noise throughout the corridors where visitors travel; frequent strain on Yellowstone’s wildlife; and risk to people with sensitive lungs from snowmobile exhaust.

But this is not what the superintendents of Yellowstone and Grand Teton parks have said publicly, which is an important story in itself.

Last October, as the Park Service prepared to announce an administration plan that it knew would be controversial, the agency decided it would keep more than 300 pages of analysis to itself. Those pages included computer modeling, paid for by taxpayers, which showed that the administration’s plan for more snowmobiling would cause harm to Yellowstone’s environment and increased risk to human health.

The Park Service decided not to release these findings. A transcript of an Oct. 31 conference call reveals the assistant superintendent of Grand Teton National Park explaining, "We want to stay away from some of the details (of the plan) and focus on the fact that this is a collaborative decision process."

Calling a decision collaborative does not make it so. What seems certain is that the Bush administration prefers to listen to the snowmobile industry. Two years ago, Yamaha, Arctic Cat, Polaris and Ski-Doo filed suit against the National Park Service and have since spent, according to Internet bragging by Polaris, millions of dollars lobbying to keep their machines in Yellowstone and other national parks.

The Park Service had determined in November 2000 that restoring clean air and quiet and making Yellowstone safer and healthier for people and wildlife required a new winter transportation system. The agency decided to phase out snowmobile use and increase opportunities for visitors to ride into the park on multi-passenger snowcoaches. The Park Service said to do anything less would violate various laws and national park policies. The Environmental Protection Agency agreed. So did four out of five Americans with opinions on the question.

You might think that the Bush administration would likely have defended the Park Service. Instead, it asked for another study and more analysis. This backfired: Two additional comment periods produced more than 360,000 cards, letters, and emails--more citizen mail than the Park Service has received on any issue in its 86-year history. The comments came in 4-to-1 in support of ending snowmobile use in Yellowstone.

As for enlisting more analysis, the Park Service did that, but it is sharing its 300-page study primarily with supporters of the snowmobile industry; not with the media or the public. The stonewalling has become clear, thanks to the Billings Gazette, which obtained a copy of the study by invoking the state’s open records law.

In this latest study, the Park Service confirms that newer snowmobiles, while indeed cleaner, remain so disproportionately polluting, noisy, and stressful to wildlife that allowing their continued use in Yellowstone would come with significantly greater impacts.

"Compared with the plan approved in 2000," said the Billings Gazette, in a summary of what the Park Service knows but is not saying publicly, "the latest draft would be more harmful to wildlife, air quality, visibility and park employees’ health."

Americans have insisted on vigorous protection of Yellowstone ever since Congress made it our first national park in 1872. Though management directives echo that commitment, the administration’s snowmobile plan ignores this goal. The Park Service knows politics have replaced right action, and the American people deserve to know, too.

After years of study and public comment, costing millions of dollars, Yellowstone’s future should not be decided behind a curtain of secrecy. The Park Service should make its important findings -- all of them -- public immediately.

Hope Sieck is a contributor to Writers on the Range, a service of High Country News in Paonia, Colorado (hcn.org). She is associate program director for the nonprofit Yellowstone Coalition in Bozeman, Montana.