Yukon gov't reports potential leak at Eagle mine; chief says concerns about groundwater remain

While the possibility of a new leak at the Eagle Gold mine is upsetting, what could be in the groundwater remains the First Nation of Na-Cho Nyäk Dun's top concern, Chief Dawna Hope said.

"We knew that this was going to come to this," she said. "There was no treatment plant up and running. There was no emergency planning established in case of a disaster.

"It's been leaking since June 24. There's just so much unknown about groundwater."

That's the date when part of the mine failed, with an enormous rock slide severely damaging the system. Walls containing chemical compounds breached, spilling some 300 million litres of cyanide solution.

The territory notified Yukoners Friday of a new potential leak, which, it says, could be located in a new storage pond, built by a contractor hired by receiver PricewaterhouseCoopers. The scale of the possible leak remains unknown.

The receiver informed the territory of "irregularities" in volumes of water contaminated with toxins like cyanide, which, among heavy metals like mercury, continue to leach into, and spike, in nearby Haggart Creek. The latest government data shows cyanide downstream of Dublin Gulch in late November and early December were nearing levels high enough to kill fish.

With contaminated water decreasing in the pond, it's a question of where it's escaping from. 

A spokesperson with the Yukon Department of Mines said in an email to CBC News more tests are needed to figure out whether there is, in fact, a leak. That's what the receiver is doing now, said John Thompson.

"The pond holds snow, ice and water that can obscure precise volume readings," he stated.

"Recent surface water quality results from Haggart Creek, near Lynx Creek, received this past week have shown elevated levels of cyanide. Monitoring will continue in this area to determine if the results were anomalies or represent an increasing trend."

Thompson said the receiver has been pumping treated water into the storage pond, in an effort to dilute and curb impacts to the land and water.

PricewaterhouseCoopers didn't reply to a request for comment.

'Far more complicated down below'

Much of the surface water in the creek has been frozen solid. The same can't be said for groundwater, regardless of recent frigid temperatures or gradient of land.

This is where Na-Cho Nyäk Dun's concern continues to lie, like it has since the outset of the disastrous slide. During the summer, the First Nation's technical team warned of a toxic plume of cyanide inching toward Haggart Creek.

"Groundwater can actually go uphill because of the pressurized abilities behind it," Hope said.

"If you look at the history of how the Yukon geological surface was developed, the Yukon River at one point actually ran in the opposite direction. As much as the environment is different on the surface, it is far, even far more complicated down below."

Hope wants to see more tests completed in areas where the groundwater upwells.

"They're wet areas in the snow that we should be testing to see if it is actually getting farther than we expect."