Open this photo in gallery In August, 2014, Mount Polley’s massive tailings dam breached at the copper and gold mine in B.C.’s Cariboo Region near Quesnel Lake, sending about 24 million cubic metres of waste and mine water into nearby waterways. JONATHAN HAYWARD/THE CANADIAN PRESS

A years-long investigation by multiple agencies into the largest mine-waste disaster in Canadian history has led to a recommendation for charges under the federal Fisheries Act.

With the five-year deadline for charges just weeks away, The Globe and Mail has learned joint task force on the 2014 tailings-pond breach at the Mount Polley mine in central British Columbia sent its recommendations to the Public Prosecution Service of Canada in early April.

It is now up to the Crown to decide whether to approve the charges.

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“The investigation of the Mount Polley pollution incident has been lengthy and complex. As the matter is now under charge assessment, there will be no further comment at this time,” Veronica Petro, a spokesperson for Environment Canada, said in a statement.

In August, 2014, Mount Polley’s massive tailings dam breached at the copper and gold mine in B.C.’s Cariboo Region near Quesnel Lake, sending about 24 million cubic metres of waste and mine water into nearby waterways.

An expert panel concluded the failure of the dam was a preventable accident due to a flawed dam design. The regulatory body that oversees British Columbia’s engineers and geoscientists said last year three of its members would face a disciplinary hearing to respond to allegations of negligence and unprofessional conduct over the dam collapse. A hearing has not yet been scheduled.

But there have been no charges laid. The B.C. government had three years after the spill to lay charges, but missed the window.

The joint investigation by Environment and Climate Change Canada, Fisheries and Oceans Canada, and the B.C. Conservation Officer Service continued, however, looking into alleged offences pursuant to the federal Fisheries Act, which prohibits the deposit of deleterious substances into water inhabited by fish.

No deadline has been given for a decision regarding charge assessment.

So the First Nations and other residents of the communities around Quesnel Lake and the mine workers will continue to wait. It has been a long five years of uncertainty.

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Christine McLean and her husband bought a secluded cabin on the shores of Quesnel Lake seven years ago, the waterfront home where they planned to retire. They were, at first, unaware their neighbours included a large gold and copper mine.

“The first we knew about it, was August 4, 2014, when my friend called me and told me the lake was destroyed and there was no point ever going there again. That’s what people thought that day, when they watched the tailings pour into the lake.”

When Ms. McLean returned to the cabin, what she found was not what she expected. The fish were not belly up in the water. The deep lake was resilient. It could, it seemed, recover.

Almost five years later, residents have started to swim in the lake again. A smaller number of them are willing to fish, even as Imperial Metals, the mine’s owner, continues to discharge effluent into the waterway that leads into the Fraser River. “But I don’t know anyone who drinks water from the lake any more," Ms. McLean added. Suspicions about safety remain.

Robert Phillips, a board member of the First Nations Energy and Mining Council, was close to members of the local Indigenous communities when he lived in nearby Williams Lake, 56 kilometres away from the mine. He recalled watching the news on TV the day the dam broke.

“You shed a tear,” he said. “Mostly, I think of the elders who would go berry-picking and hunting – people have been fishing here for thousands of years. Now, the environment is devastated.”

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Mr. Phillips is angry the B.C. government has failed to hold Imperial Metals accountable.

“We want financial consequences and the company has to clean up the mess,” he said. “The Soda Creek and Williams Lake bands, they need true compensation for what has happened in their traditional territories. But the company got off scot-free.”

The provincial government hired an expert panel to find out what went wrong. That review concluded the tailings dam was built on a layer of glacial silt, weakening the foundation of the dam – a flaw that was compounded over the years as the dam was repeatedly raised and made steeper. The panel said the inadequate design of the dam didn’t account for drainage or erosion failures associated with glacial silt beneath the pond.

Since that report, the province has tightened up oversight of mining regulation, but geophysicist David Chambers, the founder of the Center for Science in Public Participation in Montana, said B.C. has not gone far enough to ensure another mining disaster won’t happen. Mr. Chambers studied the Mount Polley aftermath and concluded in a 2018 report there are still gaps to be closed.

He’d like to see mining companies provide sureties to guarantee cleanup costs would be paid in the event of another environmental catastrophe. And, he said, the province has yet to follow through on key recommendations for change from its own expert review panel.

“Almost every jurisdiction does it better than B.C.,” he said in an interview.

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Two years after the dam was breached, the Mount Polley mine reopened and the company was given a permit to discharge waste water into Quesnel Lake until 2022. The mine has suspended operations as of May 31, however, citing low copper prices.

For Ms. McLean, now an activist with Concerned Citizens of Quesnel Lake, what remains is uncertainty about the future. “When we came here, we thought we had found a beautiful piece of heaven,” she said. "The communities on the lake need to have justice.”​