The Mount Polley mine disaster occurred on August 4th, 2014 near Likely in the Cariboo region of Central British Columbia.

Below you will find an overview section describing the Mount Polley mine disaster, followed by our latest news and analysis on the subject.

Overview of the Mount Polley Mine Disaster

On August 4th, 2014 a four square kilometre sized tailings pond full of toxic copper and gold mining waste breached, spilling an estimated 25 billion litres of contaminated materials into Polley Lake, Hazeltine Creek and Quesnel Lake, a source of drinking water and major spawning grounds for sockeye salmon. According to Mount Polley mine records filed with Environment Canada in 2013, there were “326 tonnes of nickel, over 400 tonnes of arsenic, 177 tonnes of lead and 18,400 tonnes of copper and its compounds placed in the tailings pond,” in 2012.

Following the Mount Polley mine disaster, a local state of emergency was declared for the Cariboo Regional District over drinking water contamination concerns.

Clean up efforts have led to a reconstructed Hazeltine Creek, although the contaminated slurry that made its way into Polley Lake and Quesnel Lake remains in the waterways. A drinking water ban was lifted within weeks of the spill and regular water testing is being conducted by the B.C. government, the Mount Polley mine, the University of Northern British Columbia and local residents.

An investigation into the cause of the spill revealed mine engineers failed to account for glacial silt underneath the tailings containment pond, leading to structural insufficiencies that caused the dam’s collapse. No charges or fines have been laid in response to the disaster. Several local landowners and business operators affected by the spill have launched legal challenges to seek compensation for damages.

The Mount Polley mine is an open pit gold and copper mine in operation since 1997 and is owned by Imperial Metals.

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Another year of keeping a close watch
Here at The Narwhal, we don’t use profit, awards or pageviews to measure success. The thing that matters most is real-world impact — evidence that our reporting influenced citizens to hold power to account and pushed policymakers to do better.

Our stories have been raised in legislatures across the country and cited by citizens in their petitions and letters to politicians.

In Alberta, our reporting revealed Premier Danielle Smith made false statements about the controversial renewables pause. In Manitoba, we proved that officials failed to formally inspect a leaky pipeline for years. And our investigations on a leaked recording of TC Energy executives were called “the most important Canadian political story of the year.”

We’d like to thank you for paying attention. And if you’re able to donate anything at all to help us keep doing this work in 2026 — which will bring a whole lot we can’t predict — thank you so very much.

Will you help us hold the powerful accountable in the year to come by giving what you can today?

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We’re fighting for our right to report — and your right to know. Stay in the loop about our trial against the RCMP and get a weekly dose of The Narwhal’s independent journalism
Red text in bold, capital letters: JOIN OUR FIGHT FOR PRESS FREEDOM