Water is expected to overtop the Chilcotin River landslide, in B.C.’s Central Interior, either Sunday night or early Monday.
In an update provided by the provincial government on Sunday afternoon, based on current modelling, it is expected that the water will start to move overtop the blockage and enter the riverbed below.
“There has been minimal seepage of water through the natural dam created by the landside on Tuesday, July 30, 2024, so the water level behind the dam has continued to increase steadily in recent days,” the province said in a statement.
“It is rising at a rate of about 18 centimetres per hour.”
The best and most likely scenario is that it would still take 12 to 24 hours for the trapped water to move through and past the blockage.
This is expected to result in flows below spring flooding peaks on the Fraser River though far above peaks on the Chilcotin River.
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“In the 12-hour scenario, the peak flows in the Chilcotin River could be over 10 times greater than a typical freshet peak flow,” the province stated. “In the 24-hour scenario, the peak flow could be over seven times greater than a typical freshet peak flow.”
People are urged to keep out of the Chilcotin River valley between Hanceville and the confluence of Fraser River. An evacuation order issued by the Cariboo Regional District remains in place. People are also advised to stay away from the banks of the Fraser River.
The province said it is preparing for all possible outcomes since modelling does not provide guarantees.
Real-time water-level monitoring information is publicly available through the Water Survey of Canada.
The provincial government has also launched a new web portal to provide the latest information on the Chilcotin River landslide.