Toronto River That Caught Fire Now Teems With Salmon

Toronto's Don River was once so toxic it literally caught fire, but today ecologists are celebrating the return of Atlantic salmon and rare native fish to its waters.

After a billion-dollar restoration effort, the river that was declared biologically dead in 1969 now supports over 20 species of fish at every stage of life. Scientists from the Toronto and Region Conservation Authority recently spotted Atlantic salmon, largemouth bass, and the emerald bowfin swimming in the same waters that once resembled London's polluted Thames.

The transformation didn't happen overnight. In the 1800s, industrialization forced the meandering Don River into straight lines with an unnatural 90-degree angle that caused decades of flooding. The artificial channels sped up water flow while destroying wetlands that naturally held excess water.

Restoration teams spent years undoing that damage. They recreated wetlands from infilled land and gradually returned the river to a natural course. The project included new flood protection measures and Ookwemin Minising, "the place of the black cherry trees" in Ojibwa, a delta island that will support 5,000 homes.

The changes gave fish exactly what they needed. Gravel beds now provide spawning grounds while underwater and shoreline vegetation offers shelter. In just the first year after the river flowed through its restored valley, fish diversity exploded.

"The fish community in general has definitely increased in the area," says Brynn Coey, supervisor of aquatic monitoring at TRCA. "We're seeing different life stages, very juvenile, just born pumpkin seed, and then we're getting underwater video of these massive largemouth bass in these wetlands."

Predatory fish have made a particularly impressive comeback. Northern pike and walleye now hunt alongside those largemouth bass, signs of a healthy, balanced ecosystem.

The Ripple Effect

The Don River's revival shows what's possible when cities commit to undoing environmental damage. This major artery of Lake Ontario went from literally burning to supporting complex food chains in just a few decades. The restored wetlands now provide flood protection, wildlife habitat, and recreational opportunities for millions of Toronto residents. Other Great Lakes cities watching the Don's transformation have proof that even the most polluted urban waterways can return to life.

Coey and her team know there's still more data to collect on the new habitats, but for a river once considered beyond saving, the future looks remarkably bright.