Don River Streams 500 Billion Microplastics into Lake Ontario

A river of plastic?

STARTER STATS

• Over 500 billion microplastic particles (36,000 kg, the weight of 18 cars) flow from the Don River to Lake Ontario every year.

• 20,700 macroplastics (160 kg) are trapped in the system

• Grocery bags and wet wipes were the top macroplastic culprits at 42% combined

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Researchers at the University of Toronto have quantified microplastic flow in Toronto’s Don River, estimating that it flushes over 500 billion microplastic particles into Lake Ontario annually. That's the equivalent of 36,000 kilograms, or the mass of 18 cars, revealing how our garbage is poisoning urban ecosystems.

The team analyzed plastic flow at four Don River sites before, during, and after storms. Most of that comes in the form of microplastics — tiny plastic fragments from sewage, road dust, tires, and broken-down single-use items — which easily travel into the lake.

At the same time, macroplastics like bags and wipes also flow into the river. Compared to U.S. rivers like Chicago’s, the Don’s load was found to be shockingly higher, highlighting its role as Canada’s most urbanized watershed and a model for global pollution tracking. To slow the flow, the team urges banning single-use plastics (potentially slashing waterway litter by 42%), installing storm drain traps, tightening waste collection, and enforcing anti-dumping rules. Individuals can help by binning wet wipes and joining cleanups like U of T’s Trash Team.

“From past clean-ups and trash-tracking projects, we expected to find a lot of waste in the Don for this study — but we were shocked by the numbers... The amount of plastic pollution is significantly higher than what we’ve seen in similar rivers in the U.S., like the Chicago River in Illinois and the Ipswich River in Massachusetts.”

— Dr. Chelsea Rochman, U of T

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