Toronto's Don River Rises From the Ashes: Once Ablaze With Pollution, Now Teeming With Life
There was a time when Toronto’s Don River was so choked with industrial waste that it actually caught fire. Declared biologically dead in 1969, the waterway had become a cautionary symbol of urban environmental neglect, its waters as lifeless as the concrete channels that contained them. Today, that same river pulses with renewed vitality, home to more than 20 species of fish and serving as proof that even the most damaged ecosystems can heal when given the chance.
The transformation didn’t happen overnight. It took decades of planning, community effort, and roughly one billion Canadian dollars in restoration initiatives to bring the Don back from the brink. But the results speak for themselves: ecologists with the Toronto and Region Conservation Authority have now confirmed the presence of Atlantic salmon, largemouth bass at every life stage, and the emerald bowfin—a warm-water fish native to Ontario—all thriving in waters that were once too toxic to support any life at all.
Undoing a Century of Damage
The Don River’s troubles began in the 1800s as Toronto’s port industrialized. Engineers straightened the river’s naturally meandering path into rigid channels, including an unnatural 90-degree angle that diverted water away from the inner harbor. The straightened course accelerated water flow while the destruction of adjacent wetlands eliminated crucial water-holding capacity. The result was a river that flooded frequently and could no longer sustain the delicate balance of life it once harbored.
Reversing this damage required reimagining the river itself. Restoration teams worked to recreate wetlands from land that had been filled in generations ago. The river’s course was gradually reshaped to approximate something closer to its original, winding form. New gravel beds were installed to provide spawning grounds, while underwater and above-water vegetation was reintroduced to give fish shelter and habitat.
The project also incorporated forward-thinking climate resiliency measures, including new levees and the creation of a delta island called Ookwemin Minising—“the place of the black cherry trees” in Ojibwa. The island represents both ecological restoration and urban development, with plans for approximately 5,000 homes to be built on reclaimed land that works with nature rather than against it.
Signs of Recovery Everywhere
Within just the first year of the river flowing through its newly naturalized valley, researchers documented a dramatic increase in fish diversity. Brynn Coey, supervisor of aquatic monitoring and management at the Toronto and Region Conservation Authority, has witnessed the transformation firsthand.
The variety of fish communities has expanded significantly throughout the restored area. Researchers are now observing multiple life stages of various species, from newly hatched pumpkin seed sunfish to massive largemouth bass prowling the newly created wetlands. The presence of these different age groups suggests that fish populations aren’t just visiting—they’re reproducing and establishing permanent homes in the revitalized ecosystem.
Predatory fish have also returned in force. Northern pike and walleye, species that require healthy prey populations and clean water to thrive, are now regularly documented in waters where they haven’t been seen for generations. Their presence indicates a functioning food web, with smaller fish, insects, and aquatic plants all playing their essential roles in supporting larger species.
A Template for Urban Rivers Everywhere
The Don River’s recovery offers lessons that extend far beyond Toronto’s borders. Cities throughout the Great Lakes region and around the world face similar challenges with waterways that were sacrificed to industrial development. The Don demonstrates that biological death need not be permanent.
The restoration required patience, significant financial investment, and a willingness to think in terms of decades rather than election cycles. It demanded collaboration between conservation authorities, government agencies, and community stakeholders. Most importantly, it required a fundamental shift in how cities view their relationship with natural waterways—not as obstacles to be controlled, but as living systems worthy of restoration.
Researchers caution that the work is far from complete. Ongoing monitoring will be essential to understand how the restored habitats evolve and whether fish populations continue to strengthen. Climate change presents new challenges that weren’t factors when the restoration began. Yet the early results provide genuine cause for optimism.
For a river that was written off as dead more than half a century ago, the Don’s resurgence represents something increasingly rare in environmental news: a story of genuine, measurable progress. The fish swimming through its waters today don’t know about the decades of pollution, the fires, or the years of neglect. They know only that the river, at last, has become a place where life can flourish once again.