TENNESSEE PASS — The 25,000 skiers a year who climb snowpacked paths to backcountry huts tend to be environmentally conscious, "leave no trace" travelers who minimize their impact.
But as population growth and the recreation industry drive demand to install more of the super-popular huts in Colorado's mountains, U.S. Forest Service officials are blocking construction. A new theory holds that skiers may be disturbing high-country ecosystems by creating compacted snow "highways" that lure unwanted predators — coyotes, cougars and bobcats — into otherwise isolated areas to hunt snowshoe hares.
That could be a problem, foresters say, because secluded timberline snowfields are the home of lynx,

Just west of Tennessee Pass, a lynx moves around near one of the structures that are part of the 10th Mountain Division Hut System. (Photo by Jill Mattoon)
the protected tuft-eared wildcats that government biologists are nurturing back from the brink of extinction. Snowshoe hares are their winter food supply.
Three lynx recently circled the 10th Mountain Division hut while skiers marveled from inside the log building. Although the species' fat paws are swift enough to swat down low-flying birds, food other than snowshoe hares at 11,370 feet is scarce.
"In a natural setting, with no skiers or other human-caused compaction, those predators (coyotes, cougars, bobcats) sink in and can't forage very high," said Mike Kenealy, a natural-resources specialist who manages hut permits in the White River National Forest.
Now an opportunistic coyote can follow skier tracks right to the hares.
"When you've got other critters eating your food source, then there's not enough food for lynx to consume. That's the crux of the issue," Kenealy said. "If there's no food around, lynx aren't going to be there."
The Summit Hut Association recently proposed to build a new hut between Breckenridge and Keystone.
Forest Service officials say they are inclined to stay with the current number. They're considering snow compaction as part of a broader "carrying capacity" calculation. Simply rebuilding a hut that burned down a couple of years ago required a full environmental review.
"We're running out of space in the forests to put too many more in," Kenealy said, noting Colorado's population is projected to nearly double by 2050 to more than 10 million. "And we're not making any more land."
Backcountry ski groups embrace the concerns about too many people. Some skiers trek to the backcountry precisely to escape Colorado's commercialized crowds around ski resorts and noisy motorized recreationists — including 30,000 registered snowmobilers.
The use of ski trails by coyotes and cougars "definitely happens. The evidence supports that," said Ben Dodge, director of the 10th Mountain Division Hut System, which oversees 30 of about 50 backcountry huts statewide.
"But does it cause adverse effects? Are those significant effects?" he asked. "It certainly seems that the critters who survive on snowshoe hares are doing pretty well."
State wildlife officials were unable to provide data on the hare populations. Lynx were reintroduced to Colorado in 1997. Today, wildlife biologists estimate "there are at least 200 lynx, and if pressed, we would say there are quite a few more," state Parks and Wildlife spokesman Theo Stein said. "We are confident that they are sustaining their population."
Dodge said ski-hut trips often inspire users to get involved in protecting the mountains. Ski-hut users

Cross-country skier David Christie of Evergreen makes his way to a 10th Mountain Division hut outside Leadville. The sled he pulls — which is carrying three days' worth of food, clothing, water and other necessities — also contributes to snow compaction on the trail. The packed surface helps predators access areas teeming with snowshoe hare — a trend that concerns parks and wildlife officials. (Helen H. Richardson, The Denver Post)
also serve as eyes and ears for state biologists — reporting details on "Lynx Tracking Field Survey" forms available at huts.
Colorado's ski huts multiplied in the early 1980s, modeled after huts in the European Alps. Most were designed and paid for by World War II veterans of the 10th Mountain Division — the experimental military unit that pioneered skiing and survival techniques in Colorado's mountains and then conducted a surprise assault on a ridgetop Nazi stronghold in Italy, clearing the way for U.S. forces to invade.
Each hut holds 16 or so people, who had to climb 3 to 6 miles, hauling packs. The huts have emerged as refuges from the urban world of technology, with limited solar electricity and water available only by melting snow over wood stoves. Wood is hauled in during summer so that hut users needn't cut their own fuel. Also, there are outhouses amid the snowdrifts.
And despite risks of hypothermia, avalanches and altitude sickness en route, demand for space in all huts is increasing.
Online lottery systems are used to allocate space, with fees about $30 per night. The 10th Mountain Division Hut System coordinators say all bunks are booked up to a year in advance for most winter weekends. They recorded more than 53,000 "skier nights" last year, up about 12 percent over the past decade. The San Juan Hut system, in southwestern Colorado, and others have equally brisk business.
"Mining, off-highway vehicles and ski-resort development pose far greater threats to lynx than backcountry skiers," said Wendy Keefover, director of WildEarth Guardians' advocacy to protect mountain carnivores.
However, even energetic hut users such as Hugh Evans, 87, a 10th Mountain Division veteran, see a need to set limits in the face of population growth.
Evans is the last skiing member of the mountain division. He has skied to all the huts, recently completing his 44th ascent — to the 10th Mountain Division hut northwest of Leadville, near the Holy Cross Wilderness Area.
When hut system coordinators sent him an e-mail last week seeking guidance on whether more huts should be built, he said he preferred no more.
The current huts "seem to be well-spaced, well-maintained," Evans said, sitting on the deck beneath 13,209-foot Homestake Peak.
"We have to think about the environment, the wildlife. And one of the reasons we like the backcountry," he said, "is that people are few and far between."