Canmore, Alberta is moving to tame another dangerous mountain creek that poses a debris-flood risk to homes and infrastructure below, continuing a mitigation effort that began after the catastrophic 2013 floods.
The town has posted a request for proposals seeking contractors to stabilize Three Sisters Creek, a steep drainage that engineering hazard assessments have identified as capable of unleashing torrents of water, mud and boulders into the Three Sisters neighbourhood below.
In June 2013, a massive rainfall event sent debris floods roaring down Cougar Creek, Three Sisters Creek and other Bow Valley drainages, tearing through neighbourhoods, destroying homes and severing the Trans-Canada Highway. The southern Alberta floods that month killed five people and caused an estimated $6 billion in damage province-wide, with Canmore alone absorbing more than $250 million. It remains one of the costliest natural disasters in Canadian history.
Source: NationGraph.
Since then, the town of roughly 15,000 permanent residents has been working through a list of high-risk drainages, one by one. The largest completed project is the Cougar Creek debris retention structure, a dam-like barrier built in phases over the past decade at a cost of more than $50 million, drawing on federal Disaster Mitigation and Adaptation Fund dollars alongside provincial and municipal funding. Three Sisters Creek is next in line.
The urgency is growing. Climate change is loading the dice for more intense rainfall events in the Rockies, while retreating glaciers and permafrost are destabilizing slopes. Debris floods on Bow Valley creeks are expected to become more frequent, meaning the mitigation work Canmore began after 2013 is essentially a permanent condition of living in this valley.
The stakes are compounded by development pressure. Three Sisters Creek drains terrain connected to the Three Sisters Mountain Village lands, which have been at the centre of a years-long dispute between the town and developers over proposed expansion into the Bow Valley. Canmore sits between Banff National Park and some of the most geohazard-prone mountainsides in Canada, with much of its developable land sitting on alluvial fans built up over centuries by exactly the kind of debris floods the town is now working to prevent.
The contractor selected will carry out the creek stabilization work, with details of the project scope and timeline outlined in the solicitation. The bid process is now open.
