More landslides could occur in the Johnsons Landing area in the Kootenays, in the same area as a landslide in July 2012 in which four people died.
In a report released Thursday, the review found there is potential for future landslides in the Gar Creek drainage area, where the slide occurred last year.
The report found the likelihood of a landslide and debris flow that is contained within the Gar Creek channel flowing over the Gar Creek fan and into Kootenay Lake is estimated at 1:10 per year, the likelihood of a landslide of sufficient volume to travel onto and near the downslope end of the Johnsons Landing bench is estimated at 1:1,000 per year, and the likelihood of a landslide of sufficient volume to travel onto the Johnsons Landing bench and continue to Kootenay Lake is estimated at 1:10,000 per year (see below):
The study was commissioned by the Regional District of Central Kootenay to look at whether another slide could occur, and to look at the hazards to residents in the area. The study has found that another slide could happen at any time, meaning the land is still unstable.
The cause of the July 12 slide was found to be a very high groundwater table that reduced the effective strength of the soil. This occurred due to above average rainfall in June and a higher than normal snowpack, combined with a delayed snowmelt. Slope movement was happening at least two days before the slide occurred, and local residents had noticed the Gar Creek had been flowing at its highest level in more than 40 years in the week before the slide.
One of the recommendations of the report is the improvement of communication between residents and local authorities.
This includes notifying residents of the estimated hazard and risk in the area, and teaching them how to read the signs of increased landslide hazards, such as high creek turbidity. This includes visitors to the region.
Other recommendations include establishing a simple landslide monitoring program, and restricting further land/house development in the areas identified as having a moderate, high, or very high hazard unless investigation are done that support the development.
Sixty-year-old Valentine Webber and his daughters, 22-year-old Diana and 17-year-old Rachel, died along with 64-year-old German national Petra Frehse, when at least three homes were engulfed as the massive slide tore through the tiny hamlet.
– With a file from the Canadian Press