British Columbia’s Supreme Court has rejected Xatśūll First Nation’s bid to halt a four-meter raise of the Mount Polley mine’s tailings dam, ruling that provincial consultation met legal standards.
Amanda Follett Hosgood reports for The Tyee.
In short:
- The 2014 dam failure unleashed 25 million cubic metres of slurry into the Fraser watershed, contaminating salmon habitat and becoming one of Canada’s worst mining accidents.
- In March 2025, provincial mining and environment ministers approved the current four-meter lift after the Environmental Assessment Office concluded its duties under B.C.’s Indigenous rights legislation.
- Imperial Metals aims to extend operations with a further expansion to 987 meters, a separate proposal that has not yet been ruled on.
Key quote:
"Xatśūll is obviously and understandably extremely concerned about the potential for a further failure and thus has a corresponding interest in ensuring that the mine is being operated in an environmentally responsible and safe manner."
— Justice Michael Tammen, B.C. Supreme Court
Why this matters:
Mount Polley sits in the headwaters of the Fraser River system, where sockeye salmon runs feed a multibillion-dollar fishing economy and form part of Indigenous diets and cultures. Tailings dams hold finely ground rock mixed with heavy metals and chemicals; when they fail, the slurry can travel dozens of miles, clouding waterways and smothering benthic life. Even slow, permitted seepage can leach copper and arsenic at levels toxic to aquatic invertebrates. Globally, climate-driven storms are putting more hydraulic pressure on aging dams, and mining companies are seeking taller walls to keep pace with booming demand for critical minerals. Each incremental raise compounds the consequences of any breach, turning routine regulatory decisions into high-stakes tests of Canada’s reconciliation and watershed protection commitments.
Read more: B.C. First Nation seeks to block tailings expansion at mine that caused major 2014 breach
