A snowboarder’s death at Whitefish Mountain Resort on Saturday underscored the risks that trees can pose when shrouded in deep powder snow.

According to the Flathead County Sheriff’s Office, 28-year-old Scott Robert Hornstra of Alberta became separated from his friends while snowboarding in the resort’s Hellroaring Basin. A multi-agency search ensued, and Flathead Search and Rescue eventually found his body upside down beneath a tree.

Hornstra had fallen into a tree well, a void in the snowpack around the base of an evergreen tree. When skiers or snowboarders fall into this space, they can find it impossible to escape alone and suffocate when the snow collapses around them.

The winter sports world has awakened to this risk over the past decade. It’s now urging skiers to understand the danger and watch out for one another.

Paul Baugher, director of the Washington-based Northwest Avalanche Institute, has helped guide this shift.

“These have been happening over time, and people just haven’t figured it out,” he told the Daily Inter Lake. “I really became aware of it in about the early to mid-2000s.”

For three decades, Baugher served as ski patrol director at Washington’s Crystal Mountain. When a skier there died in a tree well in the 1990s, “I thought, this was our craziest thing.”

But a second death a few years later, along with a lawsuit involving an incident in Oregon, led Baugher to suspect that these weren’t freak accidents. Data subsequently collected by him and other researchers show that, out of 61 “snow immersion suffocations” on U.S. ski slopes since 2000, about 70 percent were in tree wells.

Whitefish alone has seen five tree-well deaths since 2010. In 2016, the resort settled a federal lawsuit by the family of a 16-year-old German skier who died in a tree well.

Northwest Montana’s premier ski resort is prime territory for these kinds of accidents, said Baugher.

“If you look at a place like Whitefish, it’s got the right combination” for tree-well deaths: steep slopes, powdery snow and “fantastic tree skiing.”

But resorts, in his view, have limited options for risk mitigation.

“I get asked a lot, ‘Can’t you mark the dangerous trees?’ Well, pretty much every one of those trees is capable of having a problem.” As for simply closing the tree-dense, powder-rich zones, “skiers wouldn’t tolerate it, it’s just not the sport,” he said.

First responders also can’t guarantee survival. “By the time typically that a patrol or a rescue group gets involved, the die is already cast,” Baugher says. Hornstra’s body wasn’t found until the morning after he went missing.

“It’s the skiers themselves that have to prevent these accidents,” he said. “Education is the key.”

“We try to educate our guests as much as possible on the risks,” said Whitefish public relations manager Riley Polumbus. The resort has posted tree-well warning signs at the top of several lifts – including the one that accesses Hellroaring Basin, where Hornstra died — and printed them on every paper map. It also warns about the feature on its website and snow report newsletter.

“They do a good job of having the information out and having the sign boards,” Baugher said of Whitefish’s efforts.

On its website, the institute shares a variety of strategies to make a tree-well fall survivable: grabbing the trunk and branches, flipping and rolling to avoid a fully inverted position, and putting an arm in front of the face to open an air pocket. But these tactics mean little without someone nearby to pull the victim out.

“You have to keep their partner in sight,” Baugher explained. “That’s the key.”

Whitefish’s trail maps and website urge riders to “Always ski or ride with a partner, and stay in visual contact.”

Annual tree-well deaths have gone up and down, ranging from zero to nine in the years since Baugher and his colleagues began keeping track.

But in that time, he’s also seen growing awareness of the risks the wells pose. He remembers one rider, who watched a companion fall in, telling him that “my first instinct was to laugh, my second instinct was to grab my camera, my third instinct was ‘Oh, [expletive], this was exactly what I read about.” The snowboarder was successfully pulled out.

“They have to be aware of the risk,” Baugher said of those seeking glades and powder, “and they have to be a good partner, and that’s a partner that keeps their partner in sight.”

For more information on tree-well safety, visit https://www.deepsnowsafety.org/.

Reporter Patrick Reilly can be reached at preilly@dailyinterlake.com, or at 758-4407.