Challenges pile up for avalanche mitigation on mountain highways

About 10 miles west of Jackson, Wyo., the crest of Glory Bowl looms 1,600 feet above Teton Pass. Its steep, open slope provides some of the most popular backcountry skiing in the U.S., with an unbroken run all the way back to the trailhead. Skiers and snowboarders made an estimated 80,000 runs down the bowl and surrounding slopes last year, possibly the most of any trailhead in the West.

Glory Bowl also sits atop an avalanche path that can overrun Highway 22, which is traversed by roughly 5,000 vehicles a day, many driven by people commuting from eastern Idaho to jobs in Jackson. After a big storm blows through, Wyoming Department of Transportation avalanche technician Jamie Yount gathers data about snow depth, weight and cohesion to forecast where and when avalanches might occur. Then he and the highway crew close the road and fire cannons to trigger small, predictable, easy-to-clear slides, hoping to prevent large natural avalanches.

"People assume since there is control work, it's safe to ski," Yount says. But in three separate incidents this November, backcountry skiers triggered avalanches that smothered sections of the highway. The road was closed for hours at a time -- even overnight -- while WYDOT rushed to clear the frozen rubble. Over 500 commuters called to complain about skier-caused highway closures. A rumor spread that the agency would stop plowing the skier parking lot to discourage backcountry use.

The geography of Teton Pass makes Highway 22 especially vulnerable to skier-triggered slides. But it's not just a local problem; as development and recreation swell in far-flung mountain towns, challenges for avalanche managers are piling up. "There's a very large increase in backcountry use across the West," says Ethan Greene, director of the Colorado Avalanche Information Center. Exact numbers are lacking, but Greene says skiers are flocking to terrain accessible by road -- the same snow-caked slopes that give highway departments so much trouble.

"It's a pretty freaking difficult job," says Liam Fitzgerald, a Utah Department of Transportation avalanche forecaster, who does mitigation work east of Salt Lake City, especially in Big and Little Cottonwood canyons. A study of the Little Cottonwood Canyon highway described it as one of the riskiest for avalanches in North America. During ski season, up to 6,500 vehicles a day wind along the canyon wall below 3,000 vertical feet of snowy, slide-prone slopes. When avalanche danger peaks, buildings in Alta and Snowbird are sometimes evacuated. Even with extensive mitigation, natural slides can still come down.

Add backcountry skiers, and the job of trying to protect roads and buildings from avalanches becomes even harder. In mid-December, UDOT posted signs in Big Cottonwood Canyon warning backcountry skiers to stay off slopes threatening the highway where they planned to airdrop explosives to shed one storm's load before another rolled in. But when the helicopter spotted three backcountry skiers beyond the closure signs, the mission was called off and could not be rescheduled before the storm hit. That storm dumped less new snow than predicted, but could have caused avalanche hazard levels resulting in lengthy road closures, blocking access to the ski resorts up the canyon. "This is a case of a small number of people impacting a large number of people," Fitzgerald says. "They are not looking at the big picture."

Fitzgerald believes the situation will get worse as more people venture into the backcountry. "Twenty years ago, there was hardly a problem. Ten years ago, more of a problem," he says. Today, it's even harder "to make sure no one is in the area where you do control work."

Still, there's little support for cutting off backcountry access. Greene says the increase in outdoor recreation is "representative of the New West environment." Recreation has replaced industries like mining and ranching as the major economic force in many mountain towns, where new construction increasingly gets in the way of avalanche mitigation. The Colorado Department of Transportation stopped bombing one slide path near Ouray after a cabin was built downhill. "If there is a home in the runout zone, we can't do control work," says CDOT maintenance superintendent Kyle Lester. When hazard is high, "the road stays closed until it releases naturally or the snow pack stabilizes."

The rumors that skier access on Teton Pass would be blocked came to nothing. More than 600 people attended an avalanche awareness meeting held by an outdoor gear shop in Jackson in December, and WYDOT promised to keep plowing the lot. "WYDOT needed to flex their muscle a little bit," says Teton Pass Ambassador Jay Pistono, whose job title indicates the strained relationship between skiers and the transportation department. Pistono works as a liaison between the two on behalf of the Forest Service and a local access advocacy group. He warns that access could still be cut off if a skier-caused avalanche ever kills a commuter.

"All we can do is try and educate them," adds WYDOT forecaster Yount, a backcountry skier himself. "But it only takes one person to ruin it."

• Recreation