Yukon’s mining minister says elevated levels of cyanide have been detected in a waterway after an equipment failure and slide of ore at Victoria Gold’s Eagle Mine last week.
The announcement by John Streicker on Thursday came hours after the company issued a statement saying it had detected no cyanide in surface water after the slide.
The firm also announced it had received notices of default from its lenders related to a US$200-million credit agreement.
Streicker told a subsequent briefing that elevated cyanide levels of about 40 parts per billion were collected in a creek, a level higher than the allowable five parts per billion, and which “could potentially affect fish.”
“Whether this concentration of cyanide in the water will actually affect fish depends on other chemicals in the water. Water quality sampling is ongoing and fish toxicity testing is underway,” he said.
He said the government had retained experts in aquatic science and water quality to help understand the risk to the aquatic environment.
The press conference came after Victoria Gold issued a statement saying surface water quality sampling at multiple points downstream of the mine located about 500 kilometres north of Whitehorse had “not detected any cyanide” since the June 24 failure.
When asked about the apparent disparity between the results, Streicker said samples were collected from multiple locations and testing would have to continue over an extended period.
“If you see a sample that says, ‘no you don’t have cyanide,’ that doesn’t mean that the risk is gone. This is a serious and significant slide,” he said.
“Over time, we will need to do a lot of monitoring to understand how, where, and when those potential contaminants are moving through either the surface or the groundwater and what that looks like.”
Victoria Gold CEO John McConnell did not respond to a request for comment.
The failure occurred at a heap-leach facility, which uses a cyanide solution to percolate through crushed ore and extract gold.
Yukon government officials said at the briefing that ore spilled over an embankment at the base of the facility and the resulting landslide was about 1.5 kilometres long.
They said Victoria Gold had estimated the slide involved about four million tonnes of material and half of that escaped containment.
Yukon’s director of mineral resources, Kelly Constable, said the company moved quickly to build dams to hold back contaminated water that was released and pump it into storage ponds.
Mark Smith, a geotechnical engineer and heap-leach specialist with the government, said his preliminary estimate was that when the two million tonnes of material left containment, it included 300 million litres of cyanide solution.
Victoria Gold said in its earlier statement that it had received notices of default from its lenders under a 2020 credit agreement.
It said production remained suspended and its previous 2024 production and cost forecasts had been retracted.
A press release that announced the deal on Dec. 18, 2020, said the credit agreement was with a syndicate of banks.