Yellowstone and Grand Teton national parks scrambled Wednesday to put in place temporary rules for snowmobile use this season to comply with the latest ruling from a federal judge.

U.S. District Judge Clarence Brimmer in Wyoming issued a temporary restraining order Tuesday against Clinton-era restrictions on the vehicles, which are popular with tourists but criticized by environmentalists. He ordered the Park Service (search) to develop temporary rules for the remainder of the season — which ends next month — including the use of cleaner, quieter snowmobiles.

The temporary rules, announced during a conference call with reporters Wednesday, will increase from 493 to 780 the number of snowmobiles (search) that can enter Yellowstone (search) each day this season. Only a portion of them would be required to be the cleaner, quieter machines, but all will have to be part of commercially guided trips, Yellowstone Superintendent Suzanne Lewis said.

For Grand Teton, 140 snowmobiles would be allowed each day in Grand Teton (search) and the parkway connecting the two parks, park spokeswoman Joan Anzelmo said.

Lewis refused to speculate on what rules would be in effect next season or what the next legal step would be. She said officials "have been focusing on the current order in front of us."

Brimmer's move was cheered Tuesday by Gov. Dave Freudenthal and the businesses that rely on renting snowmobiles to visitors, but jeered by environmentalists, who fear an increase in pollution, noise and damage.

In December, just before the snowmobile season in the parks, another federal judge, U.S. District Judge Emmet Sullivan in Washington, D.C., reinstated the Clinton administration plan to ban snowmobiles in favor of less-polluting, mass-transit "snow coaches."

Sullivan's ruling allowed a limited number of snowmobiles in the parks this winter, but all had to be part of commercially guided trips. The ruling called for a complete ban next winter and blocked the Bush administration's attempt to scrap the rules in favor of cleaner machines.

Snowmobile manufacturers and Wyoming officials had appealed Sullivan's ruling, saying the phase-out plan would devastate communities that rely on winter tourism.

Environmental groups support the ban, arguing that snowmobiles create air and noise pollution in the parks and endanger the health of park workers. They also contend that the snowmobiles hurt wildlife.

David McCray, a snowmobile-business operator in West Yellowstone, Mont., said his concern now is the potential confusion the latest ruling may cause, particularly approaching the President's Day holiday weekend.

"To once again change the rules for this year — if there's any advantage for West Yellowstone businessmen, it's going to be negligible," he said.

A message left Tuesday for the International Snowmobile Manufacturers Association (search) were not immediately returned.

In welcoming the ruling, Freudenthal said in a statement that, "The people that are suffering under the move toward banning snowmobiles are the small-business owners in and around the parks."

But Michael Scott, executive director of the Greater Yellowstone Coalition (search), a conservation group, called Brimmer's ruling "terribly unfortunate."

"Yellowstone was clearly on a path to a better future, to cleaner air, to healthier wildlife," he said. "I think this ruling potentially puts that in jeopardy."