Victoria Gold mine CEO disputes Yukon gov't's assertion fish in Haggart Creek died from cyanide

The CEO of mining company Victoria Gold says he believes the deaths of dozens of fish in Haggart Creek, near the Eagle gold mine, may not have been caused by cyanide.

As of Monday, the mining company had reported finding at least 68 dead fish in the creek. Last week, Yukon government officials said the mine had discharged water into the creek from its water treatment plant and that was likely what killed the fish. 

Further details from the government, released Monday, outlined how most of that water was discharged on Aug. 1. On that day, concentrations of WAD cyanide "exceeded both chronic and acute guidelines for the protection of aquatic life and water quality objectives" at three locations along the creek, the government said.

In an interview Tuesday, Victoria Gold CEO John McConnell said chlorine or hard water might have killed the fish instead.

"We don't necessarily think it's related to cyanide," said McConnell. "The samples that have been taken don't indicate high levels of cyanide in Haggart Creek at the time of the fish mortality." 

McConnell called the fish die-off "very regrettable."

"As soon as we noticed the fish mortality, we stopped discharging and started recycling," he said.

When asked about the specific cyanide concentrations in the effluent discharged at the site, McConnell said he didn't have the number immediately available — but said a laboratory confirmed it was "higher than our discharge limit but below Canadian federal guidelines."

McConnell said his team has been reviewing a number of factors that may have created toxic conditions in the creek. 

"Our initial reaction was [to ask], 'Does this have something to do with temperature?'" he said.

"We kind of ruled that out, although we have built a diffuser so that when we do resume discharging, that hopefully moderates the temperature."

The company is making other modifications to its water treatment facility to address possible toxicity related to water hardness or dissolved chlorinated organics, McConnell said.

The fish die-off comes after the June 24 heap leach facility failure. The failure forced the mine to cease operations and eventually led to the Yukon government stepping in.

CBC spoke to Som Niyogi, a professor specializing in aquatic contamination, about the possibility of another explanation for the fish deaths. 

"For hardness to be acutely toxic to fish, meaning it could cause fatalities in a short time period, the hardness would have to be abnormally high," he said. "Effluents typically have higher hardness, but not high enough to be acutely toxic to fish. That's very unlikely, in my opinion."

As for chlorinated organics, Niyogi says they can be very toxic to fish, but typically have long-term impacts affecting the immune system or ability to reproduce. 

Cyanide levels dangerously high, says First Nation

Bill Slater, an environmental consultant who works with the First Nation of Na-Cho Nyäk Dun, said the cyanide levels in the water being discharged from the mine were highly toxic, and cyanide levels in Haggart Creek are dangerously high.

"Victoria Gold's own monitoring showed results that the treatment plant was discharging water more than six times the effluent standard for cyanide," he said on Wednesday as the First Nation gave its own briefing on the situation.

"In Haggart Creek, the cyanide concentrations are at or above the Canadian water quality guidelines for protection of aquatic life," Slater said.

Yukon chief veterinary officer Mary Vanderkop said it would be difficult to definitively confirm cyanide as the cause of death, as the chemical breaks down quickly in tissues — but there are other indicators. 

"The death of a large group of fish like that, of multiple species, in a really short period of time is completely consistent with what we would expect from cyanide toxicity," she told reporters at the briefing. 

Plans to resume water discharge

The company is aiming to resolve the issues with treatment and resume water discharge within five to 10 days. 

McConnell also said concerns about instability at the site appear to have passed. 

"There were concerns that there could be another sloughing, but we drained down the heap leach a few weeks ago," said McConnell. "We completed a seismic survey and geotechnical drill program and we're confident that those two measures will confirm that the leach pad is stable." 

However, on Wednesday, Slater said Na-Cho Nyäk Dun doesn't agree.

"The heap [leach] remains unstable and the critical dam that was built to retain the heap is suffering erosion on its crest and downstream slope," he said, adding that the current lack of an effective water treatment system means that water storage space on-site is almost full.

"If not addressed, this lack of storage could lead to discharge of contaminated solution directly [into waterways]," he said.

McConnell confirmed a review is underway to try and understand the cause of the June 24 heap leach facility failure. 

Meanwhile, Na-Cho Nyäk Dun has called for a public inquiry of the event.

When asked about comments by Yukon Premier Ranj Pillai and Na-Cho Nyäk Dun suggesting a possible takeover of the site, McConnell said he would have a "difficult time handing over the site." 

"Our team has done an excellent job in terms of ensuring that there is not a major environmental impact," he said. "I don't think anybody can do a better job than the Victoria team on site now and the consultants and contractors we have assisting us."