Over the last 20 years, tree well immersion has claimed the lives of more than 70 skiers and snowboarders; sadly, each fatality was completely preventable.

A tree well forms when snow accumulates around the base of a tree, but not under the lower branches or around the trunk. This results in a hole forming around the base of the tree, which gets progressively deeper as the snowpack height increases. Often times, a skier will fall and wind up head first down a tree well.

Key points to remember

1. While skiing backcountry unstrap your poles so they don’t become tangled during a fall.
2. Grab tree branches during a fall.
3. Do all you can to not land head first into the well.
4. Always stay in visible distance of your skiing partner.

A tree well is the area of deep, unconsolidated snow around the base of a tree that can “swallow” a rider if they come too close to the tree trunk. Snow immersion suffocation can occur if someone falls into a tree well, especially when they fall in headfirst and become immobilized.

A tree well provides space around the trunk of a tree that is free of grass or weeds and is often covered with mulch. Tree wells, when done correctly, contribute to a tree’s overall health by providing the following benefits: Preventing trunk damage by lawn mowers and weed eaters. Regulating soil temperature.

When do Accidents Happen? Most Tree Well/ SIS accidents have happened during or just after big snow storms or storm cycles. In general terms, the more fresh snow the higher the risk. As of 2011 research, an average of four Tree Well/ SIS accidents happen each season in the United States.

People who get caught in tree wells can sometimes find air pockets and survive up to an hour, but for many their survival time is closer to 15 minutes.

A tree well/ snow immersion suffocation accident can happen when a skier or snowboarder falls – usually headfirst – into a tree well or deep loose snow and becomes immobilized and trapped under the snow and suffocates. Breathing becomes difficult as the loose snow packs in around you.

These voids can be hidden from view by the tree’s low hanging branches. There is no easy way to identify if a particular tree has a dangerous tree well by sight therefore, treat all tree wells as dangerous. In simple terms, a tree well is a hole or void in the deep snow, which is clearly marked by a tree.

Raising the soil level around a tree is the most serious grade change. However, if the grade is to be increased a total of more than 18 inches, a tree well will be needed. A good garden soil, rich in organic matter, should be used for the fill.

Another type of tree well involves adding a “breathing layer” to the soil above the tree’s roots before adding the new grading. This is accomplished by laying down coarse gravel in a layer on top of the existing grade and then placing heavy straw or landscaper’s matting down before adding the new soil on top.

The most common skiing injury of all times, knee sprains happen when a ligament around the knee joint is injured by tearing or stretching too far. The injury can be caused by too much strain on the knee or bending of the knee in the opposite direction from its normal bending.

Generally, a skier will tip head first into the hole created by the tree well. This means that your head and arms will be heading straight down into the hole and your skis will be the last thing above you. Loose snow will start to fall in around you as you tumble, packing you in against the tree or other snow in the hole.

The big issue of tree skiing in the deep snow country is tree wells. Tree wells are areas of very loose uncompressed snow that form a hole or depression around the base of a tree. Evergreen trees, especially, have large and low hanging branches that can hold a lot of snow.

Tree wells are most common in areas of the mountain where there is fresh powder snow. Valleys, troughs and shaded parts of the mountain tends to have colder snow with more layers. Tree wells occur all over the mountain and any area that’s backcountry and off-piste that has trees can have snow wells.

This claustrophobia inducing video shows the dangers of tree wells when you venture under the rope or into the back country. If you’re not familiar with them, tree wells occur when snow falls around a tree. The lower branches of the tree prevent the snow from compressing firmly.