Surge of water from B.C. landslide dam breach fills Fraser River

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. 

Preliminary modelling from the River Forecast Centre predicts water and woody debris from the flooding will reach Hope, B.C. at the head of the Fraser Valley, later Tuesday.

"For now, we're just monitoring and anticipating some damage," Chief Roger William of Xeni Gwet'in First Nations and the Tŝilhqot'in National Government told CBC News. "We just want to know how much we're looking at."

In an update Monday night, the province said the banks of the Chilcotin River downstream of the breach have seen a significant amount of instability.

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.

The province expects flows to reach spring melt levels along the Fraser River as far as Hope, around 300 kilometres downstream of the confluence. 

The province added more information about flooding will become clear as the water continues to surge past its monitors at Big Bar. 

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. According to William, a couple of small cabins along the Chilcotin River were damaged by flooding. 

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.