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Water pollution flows across borders, 100% tariff-free

From coal mining runoff in British Columbia to bacterial blooms in the Great Lakes, there are things that just won’t be contained by lines drawn on maps

By Jacqueline Ronson

Aug. 8, 2025

Water pollution: 100% tariff-free

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A fly fisherman casts a line on a picturesque riverbend with shallow rapids

Headlines about the ongoing trade war between Canada and the U.S. continue to provide fodder for the daily news machine. Here’s the thing, though: as new reporting from The Narwhal makes clear, there are other types of cross-border flows that won’t be restrained, even by executive orders from the president of the United States.

Take the summer wildfire smoke that’s drifted up from Washington or down from the Prairies — or the toxins in our lakes and rivers. We share water and air and whatever pollutants they may carry, which means we still need to collaborate to solve thorny environmental problems.

In British Columbia, regulators are weighing a revised proposal for a mine expansion in the southern Rockies, which would involve removing the top of a mountain to unearth coal for steel-making overseas.

But across the border in Montana and Idaho, there are yet-unresolved tensions over water contamination, imported into the U.S. as a result of a century of coal mining in the mountains of B.C.’s Elk Valley. It took more than a decade of pressure from the transboundary Ktunaxa Nation before Canada and the U.S. agreed in 2024 to launch an international inquiry into cross-border pollution from the mines — an investigation that’s ongoing.

Considering new mining at this point is “just throwing gasoline on the fire,” Derf Johnson, who works for a Montana environmental group, told biodiversity reporter Ainslie Cruickshank. “It’s tough to say this right now because of the current state of political affairs in the United States, but it’s about being a good neighbour in terms of making sure that our water quality is protected.”

Scars from industrial mining in a river valley between snow-capped mountains

🔗 ‘Still knocking down an entire mountain’: new Elk Valley coal mine plan faces pushback

Over in the Great Lakes, governments on both sides of the border are collaborating to monitor toxic bacteria, known as blue-green algae, in Lake Superior and the surrounding watershed. Photojournalist Chris McEvoy followed Nathan Wilson, a doctoral candidate at Lakehead University, as he took samples from a lake near Thunder Bay, Ont., to study the bacteria and better understand its impacts.

The blooms have emerged because of warming water, due to climate change. But temperature isn’t the only factor — leaky septic systems, land development, forestry and agricultural runoff all help supply the nutrients the bacteria need to thrive.

A man throws a fine, sleeve-shaped net on a line off a dock on a tree-lined lakeshore

🔗 Blue-green algae is making a home in the warming waters of Lake Superior’s watershed

Here, as in B.C., the consequences of human activities on land and water fail to respect the arbitrary lines we like to draw across maps. We’d do well to keep that in mind, even as relationships sour on many fronts with our closest neighbours.

Take care and keep your side of the street clean,

Jacqueline Ronson
Assistant editor

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