Image: A screen grab image taken from a fly over of the Chilcotin River Friday Aug. 2 / @NathanCullen / X (Twitter)

By Fraser Valley Today Staff

Environment

Updated modelling provides encouraging risk assessment for Chilcotin River landslide

Aug 3, 2024 | 9:20 PM

VICTORIA — The B.C. Ministry of Water, Land and Resource Stewardship says new modelling of the landslide across the Chilcotin River has provided an improved understanding of the worst-case scenario risks to people and communities.

In a news release Saturday (Aug. 3) evening, the ministry says the updated assessment suggests that even if the natural dam were to fail suddenly, water levels in the Fraser River would remain below the levels seen during the spring snowmelt season. However, flows in the Chilcotin River could exceed normal freshet levels significantly, posing considerable risks to the local ecosystem and public safety.

Despite the new information, a Flood Watch remains in effect along the Fraser River upstream from Hope and a High Streamflow Advisory remains in effect along the Fraser River through the Fraser Valley.

The latest data indicates that a sudden breach of the natural dam is less likely than a slower release. A gradual release would result in less dramatic increases in water levels in both the Chilcotin and Fraser rivers, reducing the immediate risk to downstream communities.

Despite the encouraging findings, public safety risks remain. Further landslides could occur upstream of the natural dam, and downstream areas could face hazards once the water starts to flow through.

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Residents are urged to avoid the Chilcotin River valley between Hanceville and the Fraser River confluence. An evacuation order issued by the Cariboo Regional District remains in effect, and the public is advised to stay clear of the Fraser River banks.

The landslide incident also poses threats to local wildlife, particularly spawning salmon and other fish species. In response, the Province is collaborating with First Nations and Fisheries and Oceans Canada to establish an incident command structure, mobilize resources, and plan mitigation efforts.

The government says while the updated models are reassuring, they do not guarantee safety. It says authorities are preparing for all potential outcomes. Provincial personnel and partnering agencies are working around the clock to provide real-time information from the site, and prepare necessary mitigation measures.

The timing and manner in which the water pooling behind the natural dam will re-enter the Chilcotin River remains uncertain. It says the situation could change at any time.