WASHINGTON - A plan to maintain current snowmobile regulations in Yellowstone and Grand Teton national parks drew criticism from both conservationists and snowmobile enthusiasts Monday.

Jon Catton, a Montana-based conservationist, said the new proposal is ignoring National Park Service policies that require the agency to act in the best interest of the environment. A new management policy implemented this year emphasizes conservation as the parks' first responsibility.

"This proposal represents an unfortunate U-turn by the administration only months after it pledged to emphasize conservation in our national parks," Catton said.

The Park Service plan would allow 720 snowmobiles per day to enter Yellowstone National Park and 140 snowmobiles a day to enter Grand Teton National Park and the John D. Rockefeller Jr. Parkway - the same numbers as in the temporary policy now in place. Requirements for "best available" pollution control technology and for all visitors to have commercial guides in Yellowstone would also remain.

Catton said noise pollution has continued to be a problem in recent years. That remains so even though far fewer than 720 snowmobiles have entered the park each year, he said.

Jack Welch, president of the Blue Ribbon Coalition that advocates for snowmobiles, said 720 vehicles a day is appropriate.

"I don't think there is a problem with the numbers," he said.

But he added that he is frustrated the draft would maintain the requirement for snowmobilers to be accompanied by commercial guides. Visitors who receive some training should be able to guide themselves, he said.

Welch also expressed concern that the park's east entrance at Sylvan Pass would be closed to snowmobile use.

Wyoming Sen. Craig Thomas, the Republican who is currently chairman of the Senate subcommittee on national parks, said in a statement he is sure there will be a lot of questions about the east entrance closure and the plan in general.

"As with any plan that considers competing points of view, it's not perfect, but I'm pleased that our public land managers recognize the importance of maintaining visitor access to our national parks in Wyoming," Thomas said.

For years, snowmobile access to the park was largely unrestricted. But that ended before the 2003-04 winter, when the Park Service moved from a Clinton-era plan that called for phasing out snowmobiles in favor of snowcoaches and decided instead to limit the numbers and types of snowmobiles allowed in Yellowstone and Grand Teton national parks. Court challenges have also delayed a final decision.

For related articles click on the headlines below:

Parks: Keep winter limits

Plan calls for closing pass in winter