UNBC Paper Studies Effects of Mt. Polley Breach
Montreal, QC – A team of UNBC scientists has released a new research paper documenting the effects of last summer’s Mt. Polley Mine breach on Quesnel Lake.
The paper examined the physical and chemical characteristics of the spill, along with the extent of the sediment plume in Quesnel Lake, over a two month period starting with the breach August 4, 2014.
The research team discussed the results at a conference in Montreal this morning.
Lead author Ellen Petticrew said the breach, which discharged 25 million cubic metres of contaminated water and mining waste into the surrounding creeks and rivers, had the following effects on Quesnel Lake:
-Quesnel Lake rose about 7.7 cm due to the input of the material
-Researchers observed a 1-2.5 degree Celsius increase in temperature in the bottom waters of the lake
– The turbidity increased in the West Arm, which is where the material was deposited in the west basin, indicating the existence of a sediment plume at depths below 30 metres
-Copper concentrations in sediment samples collected from Quesnel Lake and Quesnel River are elevated, often above sediment quality guidelines for freshwater ecosystems
-Ultra-fine sediments remained suspended (394 cubic metres representing a surface area of about 1,000 square km)
Petticrew said it would take some time to determine what the long-term environmental impacts of the spill might be.
“We know that the salmon cycle, the four year salmon cycle of the sockeye in the system, are going to be critical to observe over this next little while,” she said. “The salmon were returning to the lake in August, they were on their way up the Fraser River into the Quesnel system when the breach occurred and the flush of material came into the lake.”
Petticrew said those salmon “seem to have spawned very successfully,” but notes they “are concerned about the juveniles from the year before who were in the lake and moving in and out of the (sediment) plume.”
She admitted the research team is concerned “how this affects the biology and our question really is, how resilient is Quesnel Lake to handle this kind of material?”