The dead fish found downstream of Victoria Gold's Eagle mine were likely killed following contaminated water discharge from the site's treatment plant, the Yukon government said in a briefing on Friday.

On August 2, Victoria Gold personnel found 68 dead fish in Haggart Creek, a creek near the mine.

According to the government, contaminated water was discharged between July 31 and August 2. The circumstances around the discharge are unclear, as Yukon said it was ‘outside the scope' of Friday's briefing when asked whether the discharge was intentional. However, Yukon officials noted that they believe the fish deaths resulted from a single event and not directly due to contaminants from the earlier heap leach failure. 

On June 24, a slide of the ore stacked in the heap leach facility caused ore to spill over the dam at the base of the heap facility at the Eagle gold mine in Yukon, Canada.

Following the discovery of the dead fish, Victoria Gold stopped the water discharge, and the government ordered the miner to construct fish barriers to prevent fish from entering the area most affected by the contaminated water.

Ground and surface contamination

In the briefing, government officials said there is "clear evidence" that groundwater has been impacted by the heap leach failure.

"Victoria Gold has been regularly sampling locations where groundwater daylights to surface in the vicinity of the Lower Dublin South Pond," groundwater scientist Brendan Mulligan said. "Concentrations of weak acid dissociable, or wad, cyanide at the locations are 10,000 times greater than the long-term water quality guidelines for the protection of aquatic life."

Mulligan emphasised that the groundwater at those locations is being collected and contained on-site.

"However, not all of the groundwater flowing down the Dublin Gulch and Eagle Creek Valleys is captured," he added. 

While there is no evidence that impacted groundwater is discharging directly into Haggart Creek, contaminants are moving from the heap leach to Dublin Gulch via groundwater and then to Haggart Creek via surface water.

Mining halt

Last week, the Yukon government denied a call from the First Nation of the Na-Cho Nyäk Dun (FNNND) to halt all mining activity on its traditional lands.

"Acting on the request from FNNND to stop all exploration and mining activities on FNNND Traditional Territory would require the Government of Yukon to take actions not contemplated in the statutes born of the Umbrella Final Agreement, such as the Yukon Environmental and Socio-economic Assessment Act (YESAA) or the Waters Act," Yukon premier Ranj Pillai said in a statement. "The consequences of such action would be significant, with serious and far-reaching consequences for all Yukoners." 

Instead, the government proposed a "prohibition of entry on staking claims in areas of cultural or environmental significance where mining would be an incompatible activity" and a pause on existing consultation processes and not start new ones within the traditional territory for two months.

The First Nation had asked to halt the staking of new mining claims entirely and pause consultation and issuance of mining licenses.

In Friday's briefing, Yukon said it would collaborate with the FNNND to monitor the long-term impacts of heavy metals on wildlife and the environment.