One day after water spilled over and breached the landslide blocking the Chilcotin River, officials, First Nations and residents in the B.C. Interior are assessing the damage as the backed-up flow surges down the Fraser River.
In an update Tuesday morning, the province said significant woody debris is flowing downstream along both rivers.
At about 6:45 p.m. PT Monday, the leading edge of the flood had reached Big Bar on the Fraser River, about 70 kilometres downstream of the Chilcotin-Fraser confluence. There, the flood reached peak flow Tuesday morning.
The province expects flows to reach spring melt levels along the Fraser River as far as Hope by noon Tuesday, around 300 kilometres downstream of the confluence.
The landslide last Wednesday dammed the Chilcotin River at Farwell Canyon — which sockeye salmon must pass through on their way to spawn.
“We have some relief that the slide area has been released,” Chief Joe Alphonse, chair of the Tŝilhqot’in National Government, said at a news conference Monday.
Evacuation orders remain in place for the banks of the Chilcotin River from near Hanceville, B.C., to where the Fraser and Chilcotin rivers meet, plus the banks of the Fraser immediately upstream and downstream of that confluence.
An evacuation order is also in place for 1.5 square kilometres near the Churn Creek Bridge.
Several districts in the area have also issued evacuation alerts along the river banks. In an evacuation alert Monday, the Thompson-Nicola Regional District recommended that anyone within 300 metres of the Fraser River banks prepare to evacuate.
Photos from social media show the flood damaged a cabin on the Pothole Ranch in Farwell Canyon, near where the slide was first reported.
Alphonse said a “handful” of structures, including small cabins along the Chilcotin River, were also swept into the water.
Alphonse said the province should have involved the Tŝilhqot’in nations in its emergency response and flood management, adding that local knowledge of landslides could have improved flood modelling.
“This is our land, we are the ones who know how to deal with this,” he said.
The Ministry of Emergency Management and Climate Readiness and Ministry of Water, Land and Resource Stewardship did not immediately respond to request for comment.
The landslide was first reported last Wednesday on the Chilcotin River near Farwell Canyon, about 285 kilometres north of Vancouver. The area is also known as Nagwentled, which in the Tŝilhqot’in language roughly translates to “landslides across the river.”
The slide created an approximately 30-metre-high dam that blocked the Chilcotin River for days. Water, debris and fallen trees built up behind the dam, creating a rising lake where the river used to flow.
On Monday morning, water and debris spilled over the dam and began to flow down the Chilcotin River. It surged over the Chilcotin River banks at rates higher than the typical levels at spring melt.
In the 24 hours before 10 a.m. PT Tuesday morning, according to the province, the lake that had formed behind the dam had drained by 15 metres.
Sockeye salmon run
First Nations have raised concerns about how the flooding will affect how salmon swim up the river, on their yearly migration to spawn.
Nathan Cullen, B.C.’s Water, Land and Resource Stewardship minister, told reporters Friday the sockeye salmon run was only days away from passing through the area.
Alphonse confirmed Tuesday that salmon head through Farwell Canyon to spawn in Chilko Lake in early August. But he said debris and silt from the flooding could greatly reduce the salmon run.
“We don’t know how many are going to get through. There may be some but it’s going to be very, very challenging,” he said.