Materials deposited into Quesnel Lake from the Mount Polley Mine breach are slowly getting flushed out with time, said Dr. Bernard Laval during a recent presentation at the University of Northern B.C. on the impact spill.
A civil engineer with the University of British Columbia, Laval has been researching the physics of Quesnel Lake for more than a decade — long before the 2014 Mount Polley Mine breach.
In 2008 and 2012 he initiated publishing two papers on the unique lake.
“I look at the physical transport of dissolved and suspended materials,” Laval said. “I’m interested that the fluid is moving and there is mixing and turbulence going on.”
Barnard said the first four months after the spill had the most dramatic influence on the lake.
“The lake mixed full depth, flushed material out down the Quesnel River, and then subsided until the turbidity kicked up,” he said, noting the hypothesis is that the materials still on the bottom of the lake are slowly getting flushed out.
When someone asked about the quality of the water down stream, UNBC professor Ellen Pettigrew from the Quesnel River Research Centre responded that suspended sediment collected the first year after the spill saw an increase of high copper concentrations.
In 2014 copper concentration was well above the acceptable standard for aquatic life, but it has been decreasing with time, Pettigrew said.
Sediments that came into the lake with the spill have higher vanadium, arsenic and copper and the natural sediments have higher chromium and nickel so researchers are able to separate the elements.
There has been an effort to collect samples from the Niagara, Mitchell and Horsefly Rivers to determine natural inputs and this year will focus on some of the streams to see how much copper is there naturally in the lake.
This coming summer, she added, there will be an emphasis to collect fish tissue analysis because 2014 was also the largest return of the salmon for the Quesnel Lake system.
“The fish had some elevated levels of things like mercury before just because of natural processes,” Pettigrew said. “This is the year that 2014 cohort of eggs that were laid will be coming back.”
The fish that swam through the river and spawning in the streams had quite an effective spawn, she added.
“They will be looking to see what happened when there was all the turbidity around.”
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