Significant progress in accessing the long-abandoned Tulsequah Chief Mine in Canada, upriver from Juneau, has occurred during the past two years, with the hope that a draft cleanup plan with updated options will be ready by the end of next year, officials said at a webinar on Dec. 3.

“We’d be looking at remedial completion, if all goes well, probably within the next 10 years,” Deborah Read, the project’s site manager for Canada-based minerals company Teck Resources, said during a question-and-answer portion of the hour-long midday forum.

A smooth timeline would include a final cleanup plan approved by 2029, following assessments of the options presented in the draft, with the work during the next several years, she said.

Cleanup of the site in British Columbia about 45 air miles northeast of Juneau has been a decades-long concern and frustration of tribal, environmental and other groups in the region. The copper, lead, zinc and gold mine that operated from 1951 to 1957 has continued discharging acid mine drainage ever since into the Tulsequah River, a main tributary of the Taku River and a prime Alaska salmon habitat.

Efforts to both resume mining and clean up the site have stalled over a period of decades. Critics in recent years have accused the administration of Alaska Gov. Mike Dunleavy of falling short on pushing Canada to clean up the mine to prevent transboundary pollution, as well as pushing for agreements with Canada allowing Alaskans to have a say in the neighboring country’s future mining projects.

“The B.C. government could legally hold Teck, the mine’s historical owner, liable for the estimated $100 million cost of the cleanup right now,” a statement by the Alaska-based advocacy group Salmon Beyond Borders issued after the webinar asserted.

“Instead of doing that, they’re hoping Teck will continue to volunteer to be involved. This lack of enforcement speaks volumes as to the way the province tiptoes around the big players in the mining industry — and the risk that means the rest of us face.”

The webinar focused on collaborative efforts to advance the cleanup by Teck and Taku River Tlingit First Nation (TRTFN), a community of about 400 people in Atlin, British Columbia. Officials from both entities said their cooperative work includes field activities, data review and discussion of possible cleanup options.

“Doing this work is long overdue, but it is actively being done,” said Rodger Thorlakson, TRTFN’s land and resources manager.

Site visits during the past two years have revealed a multitude of hazards and problems including bridges too decayed to drive over, an inoperative water treatment plant that would require extensive effort to restore, and a dam holding back contaminated water inside a mine tunnel that’s far past its intended lifespan, Read said.

She said considerable work to resolve some of those access and safety issues has already occurred, but much more will be needed before a cleanup plan can be implemented.

“The site is currently only accessible by air,” she said. “We use a twin-engine helicopter and a fixed-wing aircraft, and we access the site via the gravel airstrip. This method of access is going to be continued in 2026. There may be options in the future to use barging if we need to, but there is no road access to the site.”

A key finding of recent water quality sampling of the Tulsequah River is that while toxins are still seeping into the water, elevated pollution levels are not detected beyond a couple miles downstream of the mine site, said Chris Sergeant, a University of Washington researcher and TRTFN consultant.

However, that still means there are significant concerns to address near the mine, especially since it is likely the river will become more populated with salmon as a nearby glacier retreats and the water warms, he said.

High levels of the toxins at the mine can be fatal to salmon — a particular concern expressed by residents and officials in the surrounding region — but more commonly is “sub-lethal harm.”

“If a salmon, for instance, is exposed to high copper concentrations, that can hurt its sense of smell and its ability to detect predators, or even hone back to its birthstream when it comes back from the ocean to spawn,” Sergeant said.

“There can also be harms to the ecosystem — pollution can decrease the abundance of aquatic insects in some of these areas and also just direct habitat loss. If the water is too acidic or outside the range that the fish can live in, then that is basically unavailable to fish.”

It appears unlikely the toxins would be harmful to adult salmon in the region “because 99% of their time is in the ocean,” but a study of whether they are contaminated may occur during future field camps, he said.

Read, in response to a question submitted during the webinar about water treatment, said “our focus is on developing sustainable, long-term solutions” to manage the water risk at the site.

“This approach aims to manage the source of the acid mine drainage and protect the water quality without relying on something like a treatment system that requires a full-time ongoing site presence and intensive maintenance,” she said. “In parallel, we are assessing the need for and the feasibility of a short-term treatment system, and the associated risks with having a system like that on site.”