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NPCA Officials Cite Snowmobile Emissions In Criticizing Winter-Use Plan For Yellowstone National Park


Pointing to the National Park Service's own testing as evidence, National Parks Conservation Association officials are criticizing a proposed winter-use plan for Yellowstone National Park, saying testing shows snowmobiles have gotten dirtier and noiser, not cleaner and quieter.

In pointing to the park's Yellowstone Over-snow Vehicle Emission Tests – 2012: Preliminary Report, NPCA officials say the trend to dirtier and noiser snowmobiles the past six years "contradicts the snowmobile industry’s repeated promises to make cleaner snowmobiles and keep unhealthy gasses such as carbon monoxide, benzene and formaldehyde from fouling the air of the country’s oldest national park."

The report explains that scientists tested 2011-model snowmobiles in Yellowstone and compared their emissions with 2006 models made by the same companies, NPCA noted in a release.

"One manufacturer’s newer snowmobile emitted over 20 times more carbon monoxide than its earlier model. Another company’s newer model had higher emissions of every exhaust gas sampled, including 5 times more hydrocarbons," the release said.

The report concludes: “The model change in snowmobiles has not been a positive influence on air quality based on the emission data.”

In releasing the park's Draft Supplement Winter-Use Environmental Impact Statement earlier this month, Superintendent Dan Wenk said his proposal to allow up to 480 snowmobiles a day in Yellowstone, more than twice the average entries of recent winters, would make the park “cleaner and quieter.”

However, the National Park Service’s own studies contradict that assertion, the NPCA release said. "That document shows the proposed plan would increase snowmobile noise and pollution in Yellowstone National Park with significantly greater emissions of carbon monoxide and cancer-causing gasses such as formaldehyde and benzene," the park advocacy group said.

“Rewarding a technology that is going backward and getting dirtier is the very opposite of stewardship that Americans expect and deserve in Yellowstone National Park,” said Tom Kiernan, NPCA president. “After 10 years of pledging to make major improvements to emissions and noise, the snowmobile industry has gone back on its promise to the National Park Service and the public."

The emissions study looked at “recent additions to the snowcoach fleet” and concluded: “emissions are generally lower for newer snowcoaches compared to mean values of the earlier fleet and especially compared to the older carbureted engine snowcoaches.”

Indeed, specific data provided in the report show that current snowcoaches are up to 50 times cleaner than current models of “Best Available Technology” snowmobiles when the vehicles’ carbon monoxide emissions are calculated on a per-visitor basis. In per-visitor emissions of hydrocarbons and nitrogen oxides, the report shows snowcoaches are 2-5 times cleaner than snowmobiles. The report reflects that these air-quality advantages of snowcoaches are expected to become even more significant when Yellowstone requires all snowcoaches to utilize newer engines.

“The National Park Service should make an immediate U-turn on this misguided policy. After all, the growing majority of Yellowstone Park’s visitors prefer multi-passenger snow coaches, which are demonstrably cleaner than snowmobiles, which are getting dirtier. Even park officials have acknowledged that,” said Chuck Clusen, director of the National Park Project at the Natural Resources Defense Council. “The only obvious and responsible path forward is to facilitate the use of snow coaches, not snowmobiles.”


An electric snowmobile would not be pollution free, the pollution would merely be displaced to the power plant that generated its electricity. Furthermore, transmission of electricity is a rather inefficient process.

I think most people understand that there's no free energy lunch. (But who knows?—people's ignorance about energy can be astonishing.) The difference, however, is that any air pollution emitted to power an electric snowmobile is going to be emitted at a power plant somewhere else. It isn't going to be emitted in the middle of Yellowstone National Park and it shouldn't have any effect there, unless Yellowstone suffers from air pollution emitted by neighboring power plants.

Well, that's instructive. Thank you. I'm glad I allowed for the possibility that Yellowstone is affected by externally generated air pollution.

Anon is correct to a point. The source of electrical generation is important. So, if that source is hydroelectrical, for example, electric vehicles are obviously going to be superior to combustion whicles with respect to air quality.

Now, with nuclear power plants, the air pollution is nil (unless of course you place said power plant in the direct path of a once in a millenium tsunami).

I still don't understand why 600,000-plus summer visitors this June alone is CELEBRATED as a success for the park, but allowing 300 snowmobiles in the park for the entire winter is somehow ruining the park. Did those 600,000 people get magically transported there in June? No, they got there in cars, trucks, RVs and other things that have emissions. Over 1 million people are expected there in July. There are more people in one July day in the park than there are during a four-month period in the winter. This isn't about common sense or emissions, it's about winning or losing. Their arguement makes no sense!

It is interesting when I look at the tests you have linked it shows the 2012 Ski Doo being better in some departments than the 2006 model but you choose to only see the Arctic Cat which also happens to be the most powerful production power plant made be it 2 stroke or 4 stroke. Why not mention any improvements in the newer models? The snowmobile manufacturers are developing these engines along the way and according to the study the snowcoaches are able to slap in an engine that can be out of a wrecked vehicle model year 2000 or newer with the modern engine equipment.

We should be able to agree that the 4 strokes are cleaner than the 2 strokes for the purpose of transportation in the park. I find it interesting that you would say that even with cleaner and fewer snowmobiles that it isn't making an improvement. Maybe that means there are other factors at play. I don't think you are really saying we may as well go back to the way it has been.

Onwards though as I haven't looked at the latest studies very closely but do they have a base level established say the week before snowmobiles are allowed in the park and say a week after they leave the park to see if there is a rise and fall of pollutants during the period when snowmobiles, snowcoaches, and automobiles aren't allowed in the park other than administrative duties? As others have pointed out there is a possibility that pollutants can be coming from other sources than the snowmobiles.

I looked at the BAT list at and they list the new models as meeting the BAT requirements.

Again I say if you want clean and quiet no matter how you want to nit pick the studies it is far better to visit Yellowstone in the winter than the summer and it doesn't take millions of dollars to realize that if that is your main criteria for visiting Yellowstone. Go Enjoy!!!

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