A terrible scar on a beautiful landscape, the “Big Burn” on BC Highway 3 in Manning Provincial Park, was a striking reminder of the damaging impact of forest fire for many years. Many British Columbians are familiar with the story of the 1946 forest fire and the infamous ‘Manning Park Gallows’ sign that was erected afterwards. What is less well known is how the former Department of Highways undertook an aggressive tree planting program to reforest the burnt-out avalanche start zones in the late 1970’s.
Our Avalanche Program was created in the mid-70s to ensure that avalanche paths with the potential to impact BC highways were monitored and controlled. Following the avalanche tragedy that claimed seven lives at the North Route Café on Highway 16 west of Terrace in January 1974, an Avalanche Task Force submitted a report recommending the use reforestation as a permanent avalanche control measure.
How Reforestation in an Avalanche Zone Works
Forest cover in the starting zone of an avalanche path acts in the same way as retaining barriers in preventing snow from sliding (watch how that works in this video). It also prevents snow from drifting, a major factor in the formation of large avalanches. In many instances, the origin of the avalanche problem has been the loss of forest cover. In most cases, including Allison Pass, the cause of the loss was fire.
On the ground reconnaissance to find severe sites, similar to those of the avalanche starting zones, along roads took place during the fall of 1977. One year later, preliminary field trials of seedling test stock started at two sites in Manning Park, with 1,977 seedlings planted. Over the next three years, spring and fall plantings in the start zones of highways avalanche paths put over 40,000 seedlings in the ground, including 11,799 trees in the Burn North paths from April to May 1981.
Results of Reforestation = Success!
In the Avalanche Task Force report, Allison Pass was rated as a moderate avalanche hazard area (index rating between 10-100), noting “the highest avalanche hazard exists in the Burn.” Thanks to reforestation (including 164,000 seedlings planted on lower slopes between 1953 and 1960), the frequency in all categories has been zero for several years now, with the last notable avalanche in 2009, and the last avalanche to affect the road in 1996.
Did You Know?
There are over 1,400 avalanche paths that have the potential to affect the Provincial Highway Network. The mandate of the Avalanche and Weather Program is to ensure safety to highway users, while minimizing interruptions to traffic. This is primarily accomplished through ongoing evaluation and forecasting of avalanche conditions and the application of specific operational procedures that provide appropriate avalanche safety measures for highway users.
Find out more about our Avalanche and Weather Program in these related blogs:
Do you have any questions about this, or any other work we do at the BC Ministry of Transportation and Infrastructure? Let us know in the comments below.