By this time last year, notorious "Avalanche Alley" on Idaho 21 between the Grandjean turnoff and Banner Summit had to be closed to traffic for eight days for avalanche mitigation and snow removal. This year, due to less snow and better mitigation efforts, the 11.5-mile stretch of road was closed for only three days during December and January, the Idaho Transportation Department reported.
During that time period last year, the canyon received 143 inches of snow, while this year it received only 99 inches. For last year's winter season, which runs from Dec. 1 through May 1, the canyon received 330 inches of snow. Avalanche crews closed the corridor on 21 days—a record low. Prior to that, the average number of closures had been 60 days.
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Two years ago, the ITD expanded its avalanche-control measures by adding an experienced avalanche team trained in forecasting avalanches. The department also added high-tech weather stations and other forecasting equipment, and purchased an "avalauncher" to fire explosives into weak snowpacks, thereby bringing avalanches down in a controlled manner.
"Being vigilant and not over-reacting are the keys," ITD Avalanche Forecast Manager Bill Nicholson said. "We also count on other ITD area crews—particularly from ITD headquarters, other district offices and the plow crews—and the National Weather Service to do our jobs effectively."
The corridor along Canyon Creek has 54 avalanche chutes and is responsible for about 90 percent of the state's avalanches across highways.
