A map of the Minto mine site. (Submitted/Department of Mines, Energy and Resources)

A map of the Minto mine site. (Submitted/Department of Mines, Energy and Resources)

Minto mine’s lack of storage capacity for contaminated water potentially poses danger to environment: inspector

Minto Metals Corporation directed to take what Yukon government officials call “preventative” measures

A mine inspector has directed Minto mine to take “proactive” action to avoid releasing contaminated water to the environment during the spring melt, according to Yukon government officials in the department of Energy, Mines and Resources.

The mine inspector issued inspector’s directions to Minto Metals Corporation, which runs the mine, on April 18. The mine is legally compelled to follow the directions which were issued under the Waters Act.

In the direction, the inspector had “reasonable grounds to believe” that the mine has been and is using water in violation of the conditions of its water licence and that a “danger to the environment may reasonably be expected to result from the adverse effects of that use.”

In a technical briefing on April 19, officials said the direction is a “preventative” measure to counteract the potential release of contaminated water due to a lack of storage capacity on site.

The mine must follow the direction once the storage capacity in the tailings management facilities falls below a certain threshold.

Water is used in mining to process the tailings — the crushed rock and ore waste — which must be properly stored. Discharged water must meet the standards set out in the water licence.

This spring’s forecast puts pressure on the remaining storage capacity, which could be depleted, officials said. The region has seen significantly above average snow four years in a row.

Without taking action, during the upcoming spring melt, the mine will exceed its storage capacity and will release contaminated water, according to the inspector.

The inspector wrote that the release of untreated water into Minto Creek, which flows into the Yukon River, is “reasonably expected to cause a danger to the environment by depositing contaminants of concern which can bio-accumulate in aquatic organisms and have toxic effects.”

If the threshold is met, then the mine will have to stop milling, officials said.

Officials noted the mine is working with compliance and monitoring inspections. It is working to treat water as quickly as it can and get a new water treatment plant in place that would allow it to treat water faster, according to officials.

If the company fails to follow the directions, the next step is increased enforcement action, likely through the courts, officials said.

The mine is confident it can safely navigate the freshet season, according to an April 20 press release.

In an April 20 interview, Chris Stewart, president and CEO of Minto Metals Corporation, said the mine is following the inspector’s direction.

Stewart said the mine has been working on the water problem for more than two years. It has spent $8 million in 2022 and $12 million in 2023 on upgrading and operating the water treatment plant on site and bringing in another one.

“We’re in a much better position with respect to treatment capacity. It’ll be double what it was last year,” he said, noting the snowpack levels are “nowhere near” as high as spring 2022.

Per the release, over 1.4 million cubic metres of water was discharged in a “safe and compliant manner” in 2022, which constitutes more than double what was cumulatively discharged over the prior seven years.

Stewart said the mine is currently running at about 50 per cent milling capacity, which means a much lower quantity of tailings are being deposited.

The mine is located on Selkirk First Nation settlement land.

“It’s important for people to understand that we’ve been working closely with the Yukon government, as well as Selkirk First Nation, in regard to this water, which is actually a legacy issue,” Stewart said.

“We’ll continue to work diligently to safeguard the environment. If we need to stop milling in order to ensure that we don’t go over the limit, you know, we’ll go ahead and do that.”

Energy, Mines and Resources Minister, John Streicker provided an update on the mine’s situation in the Yukon legislature on April 19.

“An inspector’s direction was issued to Minto Metals Corporation to take action once storage capacity in the tailings management facilities falls below 300,000 cubic metres in order to protect the environment in advance of the coming spring snow melt,” Streicker said.

“Our government is committed to protecting human health and safety and the environment at all mine sites in the territory. This is why a proactive direction was issued to the company to take steps to protect the integrity of the environment at the mine site and downstream.”

Streicker explained that once the available storage falls below the threshold, the mine must divert some of the untreated water from the current water storage facility to another on-site pit known as the Minto North Pit to ensure safe storage prior to treatment.

“At that time, they have also been directed to temporarily cease milling during the spring snow melt to allow water storage levels to recover. The direction was issued after closely monitoring the situation and will ensure that there is enough water storage at the mine to accommodate increased water levels expected from the spring melt,” he said.

“The direction also lays out increased reporting requirements to continue monitoring the situation and take additional action as needed. While the Minto North Pit is not part of the current water license, it is a geologically stable pit with no known surface or ground water seepage concerns.”

Streicker said temporarily storing additional water in this pit will be safe and will prevent an uncontrolled release of contaminated water to the environment.

“Any water stored in the Minto North Pit will be treated prior to discharge to the environment,” he said.

Streicker noted the mine has been operating open pits since 2007 and underground mining since 2014. It employs an average of 180 workers throughout the year. It provides revenues and royalties to the Selkirk First Nation.

“In the face of growing evidence that additional precipitation and spring melt waters could put the environmental integrity of the mine site at risk, the decision was made to issue the direction,” Streicker said.

“Since we took over care and control of the Wolverine mine site, we have improved how we assess and respond to risk to make sure we do everything we can to avoid a similar situation here in the Yukon.”

Streicker suggested the directions will protect the environment and improve the mine’s long-term viability.

“We are committed to continuing to work with Selkirk First Nation and Minto Metals Corporation to resolve the situation as quickly as possible,” he said.


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Contact Dana Hatherly at dana.hatherly@yukon-news.com