Photo Courtesy Cariboo Regional District
Tailings dam breach at Imperial Metals' Mount Polley mine in British Columbia in August spilled nearly 10 million cu yd of gold and copper mine tailings into the Fraser River system.


The massive western Canada mine spill is even bigger than initial estimates, generating government-mandated inspections of almost 100 other mine tailings ponds and calls for hiring more engineers to inspect mines.

Mount Polley Mine, near Likely, British Columbia, and owned by Imperial Metals Corp., Vancouver, dumped 4.5 billion gallons of water and 9.5 million cu yd of tailings after a 984-ft section of the tailings pond collapsed on Aug. 4.

The volume of spilled water is 73% more than initially believed, and tailings total 61% more. It all gushed into the nearby Polley Lake, Hazeltine Creek and Quesnel Lake, all part of the Fraser River system. The watershed, an important spawning ground, has experienced large variations in returning sockeye-salmon populations in recent years.

Water in Quesnel Lake has been declared safe to drink if it is not cloudy, but neither the amount of sediment lodged there nor the long-term effect on fish is known. Fish has been approved for human consumption.

Ministry of Environment and Ministry of Mines and Energy investigations continue, as well as a joint study by the province and the Soda Creek and Williams Lake Indian Bands. The reports are due in January.

The copper-and-gold mine is shut down, while crews repair the tailings pond. A Sept. 4 inspection found waste continuing to flow into Hazeltine Creek.

That brought a sharp reprimand from the Ministry of Environment, which ordered "prompt action to abate all discharges" by adding proper containment systems "and ensuring abatement capacity is designed and built to handle a 1-in-10-year 24-hour rainfall event."

The company has not responded to questions, but a website update said a main dike in the pond was completed on Sept. 22, and no tailings have gone out since Sept. 4. Completion of a second dike allows installation of pumps to move water from the pond into a nearby pit.

No one will venture an estimate of the cleanup cost, especially because legal fees are likely.