Yellowstone, N.P. – Conservation groups are criticizing the Yellowstone snowmobiling plan unveiled last week and question why there won't be impacts. The plan says allowing 720 snowmobiles a day into Yellowstone for the next three winters won't significantly impact the environment. Chris Mehl of the Wilderness Society can't understand that statement. Mehl says studies done under the Clinton and Bush Administrations said there were impacts. He says National Park Service officials must be ignoring the science. But Yellowstone spokesman Al Nash says they are not overturning the science of the last 12 years. Nash says officials utilitized that research in coming up with this temporary three year plan. Comments are being accepted until September 20th.