Pipeline leak located more than a week after sheen first reported on Ontario river

Two women chat on the St. Clair River Trail across from petrochemical plants and refineries in Sarnia, Ont. (CP/ Craig Glover)

A pipeline leak in Sarnia, Ont., has been located more than a week after an oil sheen turned up on the St. Clair River.

Sun-Canadian Pipe Line says it pinpointed the leak on Saturday morning, nine days after the company said it was made aware of it on March 12.

An oil sheen was found on the river along the Canada-U.S. border on March 11 by Suncor, the major oil company with a refinery in Sarnia. The company later said it appeared the leak was from a Sun-Canadian pipeline.

Sun-Canadian says the impacted pipeline remains shut down and cleanup activities are ongoing to address the leak near Sun Avenue and St. Clair Parkway, in Sarnia's petrochemical hub.

Ontario's environment ministry says containment booms and absorbent materials are in place at the "discharge point and in the St. Clair River".

In a statement, the ministry said no discharges had occurred since Suncor identified the initial oil sheen on the river. The ministry said it continued to monitor the cleanup and remained in contact with local communities, including nearby First Nations.

Aamjiwnaang First Nation, whose reserve is located just adjacent to the spill, said it had been left in the dark about its size and extent.

It also requested help from police to manage an expected increase in truck traffic carrying fuel products that would have otherwise been moved along the shuttered pipeline.

The Walpole Island First Nation, downstream of the refineries along the St. Clair River, said earlier this month the spill had been contained, and its water system was unaffected.

Sun-Canadian's pipeline burst in 2013 and released around 60,000 litres of diesel. The pipe, built in 1953, was corroded and a six-inch rupture opened up in the wall when it became too thin to withstand the pressure, according to a review published by the Technical Standards and Safety Authority, Ontario's pipeline regulator.

Some of the spill ended up in a nearby sewer system and reached the St. Clair River. The Walpole Island First Nation closed its drinking water intake as a precaution. About 22,000 litres of spilled diesel was recovered in the cleanup.

This report by The Canadian Press was first published March 23, 2026.

Jordan Omstead, The Canadian Press