Metrolinx contractor's chemical spill contaminates West Highland Creek in Scarborough
A polymer-based slurry spill from Scarborough subway extension work has been contained, with cleanup ongoing at the creek near Lawrence and McCowan.
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Metrolinx crews have been cleaning up a chemical spill at West Highland Creek in Toronto's east end that has been traced back to work on the Scarborough subway extension project. The City of Toronto was notified on July 8 about the spill from an outfall at Lawrence Avenue and McCowan Road.
The spilled liquid was a polymer-based slurry used in construction, particularly for foundations and drilling. Metrolinx said the slurry in this case was water-based, non-toxic and biodegradable, and has been contained and is being removed by a specialized team. Ryan Prosser, an associate professor of environmental toxicology at the University of Guelph, cautioned that even biodegradable slurries can take decades to break down and may thicken and sink, potentially coating organisms in the stream.
The city installed containment booms and hay bales at the outfall and other areas downstream to limit the spread. Metrolinx and its contractor are responsible for the ongoing containment, cleanup and monitoring along the creek, with Ontario's Ministry of the Environment, Conservation and Parks overseeing the response. The Scarborough subway extension project is expected to connect Kennedy Station to Sheppard Avenue and McCowan Road by 2030.
At a glance
What spilled into West Highland Creek in Scarborough?
A polymer-based slurry used in construction for foundations and drilling spilled from work on the Scarborough subway extension project. Metrolinx said the slurry was water-based, non-toxic, and biodegradable.
When was the City of Toronto notified about the spill?
The City of Toronto was notified on July 8, 2026 about the spill from an outfall at Lawrence Avenue and McCowan Road in West Highland Creek.
