Prince George, B.C. – Sampling of the sediment plume moving through Quesnel Lake in the wake of the breach of the Mount Polley mine tailings pond last month is leading to concerns about the fish stocks that will be travelling through the lake to reach their spawning grounds.

Dr. Ellen Petticrew, Endowed Research Chair in Landscape Ecology in the Geology Program at UNBC, tells 250 News “we have got back some more recent materials from our lake profiles. We’ve been looking at about seven to ten sites on the lake for the structure of the water column from top to bottom, or as close to the bottom as we can get, to look at the characteristics of the conductivity, temperature, turbidity. So we’re not measuring the specific metals, we’re measuring the physical parameters of the water so we can track how it’s moving.”

Dr. Petticrew explains “this is how we’ve identified that the plume was coming away from the deposit initially, and we’ve got some data up to the 29^th of August and we’re seeing the plume is moving east away from the deposit. So it’s not just moving towards Likely, it’s also moving east toward the open part of the lake, the deeper part and the other arms of the lake.”

Dr. Petticrew says “what this implies is that we’re going to have some issues when the lake starts to cool and overturn. So this material will either be strong enough to modify the mixing of the water column or, alternately, could get mixed into the column and then result in it being held in the lake, in the bottom waters for a very, very long time.”

“What we’re concerned about right now is the depth at which it’s sitting, this veneer of turbidity is sitting because it doesn’t seem to be settling very quickly, and our concern is, will the salmon coming through the lake actually be exposed to this layer of turbidity which has the higher metal content in it, or will the fish be able to avoid this? So the dominant fish in the area, two main Sockeye runs that are going in are going into the Mitchell River and the Horsefly River and our concern is what depth are those salmon going to be sitting at to move through and will they be exposed to this. So we’re trying to collect information on the depth at which people are identifying the salmon in the lake.” Dr. Petticrew says the researchers are hoping the fish will either avoid the water column or that it will have dissipated by the time the bulk of the salmon come through.

Asked about the level at which the plume sits in the lake Dr. Petticrew says “what we have is right around the breach area the turbidity is very mixed throughout the water column, so the highest level is below 20 metres and as we move up through the lake we’re seeing turbidity between ten and thirty metres. And then further away down the lake as we move east we’re seeing turbidity again between ten and twenty-fine metres. So this is the concern, is this turbidity, this cloud that’s moving down the lake, going to be a problem for the fish?”

Dr. Petticrew says the Ministry of Environment has test results of samples taken up to the 22^nd of August right in the plume where they could see the visible grey material. “And they’re picking up high levels of some metals which are problematic for aquatic life but levels which, they say, are high in aluminum, iron and manganese which are excessive for human drinking, or for water quality, but that they’re predominantly not in areas where people are taking their water supply from.”

Dr. Petticrew says the MOE is “indicating from their results from the 22^nd of August that the material that’s in this cloud is predominantly particulate, such that it is unlikely to be bio-available. But I don’t know that that’s been tested.” She explains in that bio-available means “is it available to organisms, can organisms use it, take it up by mistake or take it up by using the water.”

So is the ministry saying that would not be occurring? “They’re suggesting that it wouldn’t be occurring, that if it’s predominantly particulate that it’s less likely to be bio-available. I’m not certain that if you’re taking your water in over your gills that you can separate the particles from the liquids.”

Dr. Petticrew says the folks at the university’s Quesnel River Research Centre continuing to do a range of things regarding the tailings pond spill. “We’re continuing to run the CTD, which is this instrument that allows us to characterize the water column and trace the movement of the water. And we’re taking bulk samples of sediment to look at the composition of the metals, contaminants.” They are also taking plankton samples from the depth which they are concerned about “to see whether or not the organisms are starting to pick up the metals.”

And, as stated previously by Dr. Philip Owens in UNBC’s Environmental Science Program, Dr. Petticrew says “we haven’t been concerned as much about getting our samples analyzed immediately because we’re not reporting back to the public the way the Ministry of Environment is required to do. So we’re trying to get as many samples as we can. We’ve stored a number of them and we’ve started to send the early ones off for processing.”

She says staff at the research centre at Likely have not been able to get much in the way of samples from the land mass covered by the tailings pond breach. “We haven’t got access to the land yet. We did grab some samples before they restricted us, we did manage to grab some material from the new surface of Hazeltine Creek, but we don’t have access to there anymore so they’re waiting for the safety regulations to be lifted.”

The Cariboo Regional District closed the spill area to everyone except those with government permission to enter while mine owner Imperial Metals works to prevent Polley Lake from overflowing. It is not known when that work might be completed.

In the meantime there would appear to be some discrepancy regarding the amount of water and tailings sediment that spilled during the August 4th breach.  Initially it was estimated that 10 million cubic metres of water and 4.5 million cubic metres of sediment spilled.  Now Imperial Metals is reported stating that it was 10 million cubic metres of water, 13.8 million subic metres of slurry and 600-thousand cubic metres of waste from dam construction.

Just to muddle the muddied waters further, the provincial government says the company “has since revised the report to about 17 million cubic metres of water and 8 million cubic metres of tailings/materials discharged into Polley Lake and Quesnel Lake.”