Yellowstone National Park's steaming geyser basins and pristine snowscapes used to be practically deserted in winter. But in the last 35 years there has been a veritable explosion of cold-season tourism here. In 1993, winter visitors - most of them on snowmobiles - topped the 143,000 mark, a level park officials had not expected until the end of the century.


Crowding is especially bad during the winter holidays, when it's not unusual to find 1,000 snowmobiles at Old Faithful. According to John Sacklin, Yellowstone's chief planner, last year the park received 110 letters from winter visitors, almost all complaining about congestion and related air pollution and harassment of wildlife.


"We expect that the unlimited growth that we've experienced in the past years cannot continue," he says. "Some kind of limits are out there on the horizon."


Most of the over-snow traffic comes from the town of West Yellowstone, Mont., which, with 1,500 snow machines for rent, calls itself the "Snowmobile Capital of the World."


On a busy winter morning, 50 to 70 of the two-cycle vehicles may be waiting at the park entrance here with their engines running. That has led to gate employees complaining of nausea, headaches, and eye and throat irritation, says district ranger Bob Seibert.


"Snow machines are dirty critters as we know them today," says Seibert. Figures submitted to the California Air Resources Board by the snow machine industry show that one snowmobile emits the same volume of hydrocarbons and nitrous oxides as 1,000 cars, and as much carbon monoxide as 250 to 500 autos.


"If you do the multiplication," says Bob Ekey of the Greater Yellowstone Coalition, "then 1,000 snowmobiles equal a million cars." The coalition is calling on the Park Service to limit snowmobiles to last year's levels.


Ekey fears that the recent opening of the Continental Divide Snowmobile Trail, which links Yellowstone, Grand Teton National Park, and Lander, Wyo., will funnel hundreds more snowmobiles into the park on busy weekends. Once use has reached a certain level, it's difficult for park officials to turn it back.


"What the cap (on numbers) would do," he says, "is give us a chance to catch our breath while there's still some fresh air."


Yellowstone officials have just begun a two-year study to determine what effect over-snow traffic is having here. They will survey visitors, measuring noise and air quality, and study the effects of cold-season traffic on geothermal features and wildlife. While the park's bison and elk seem accustomed to snowmobiles, the routes cut through their winter ranges at a critical time of year.


Yellowstone's previous winter-use plan (completed in 1990) saw the impacts of over-snow travel on wildlife as mostly negative - stress, displacement, harassment, and so on. But now several park scientists, citing the bison studies of National Biological Survey biologist Mary Meagher, say that the groomed trails are providing bison with easy travel routes between grazing areas, and contributing to their current population explosion to some 4,200 animals.


Meagher conceded in her 1993 report that factors like fire, drought, wet summers, and mild winters confused the picture somewhat. "But," she concluded, "bison use of the winter road system appeared to be the predominant factor."


Snow routes also give buffalo what Yellowstone natural resources chief Stu Coleman has called "nice easy access to park exits."


According to Sacklin, there will be no cap on winter use until the study is done. Meanwhile, the park has put a moratorium on commercial-use licenses, whose numbers, Sacklin says, are growing by leaps.


Ekey is critical of this strategy, which, he says, in effect cuts back on mass transit. "It forces you to rent a (personal) snow machine."


Sacklin agrees that "snow coaches and snowmobile guided tours are great. We'd like to encourage these rather than individual snowmobilers." The problem, he says, is that "there's no way to limit the number of rental machines coming into the park."


At least not without a cap on visitor numbers, which would not sit well with gateway towns like West Yellowstone. The park's 1990 Winter Use Plan reveals that not only do winter visitors come at a slack time of year, when they have a greater impact on local economies, but they also tend to spend more than summer tourists. According to preliminary figures from a recent study by the University of Wyoming and the Wyoming Commerce Department's Snowmobile Program, residents of that state spend $60.2 million a year on snowmobile purchases and rentals, gas, clothing and accommodations. Add the $56.5 million nonresident snowmobilers spend, and the statewide grand total approaches $117 million.


Ken Davis, West Yellowstone's operations manager, says winter recreation is "the only thing, really, that drives our economy in the wintertime." And Viki Eggers, executive director of the West Yellowstone Chamber of Commerce, has publicly commented that "it would be a horrible mistake to limit the number of visitors who come to see the winter."


* Lynne Bama





Lynne Bama writes in Wapiti, Wyoming.





For more information about Yellowstone's winter-use study, write: Winter Use, P.O. Box 168, Yellowstone National Park, WY 82190.