Sarnia pipeline leak pinpointed as cleanup continues along St. Clair River

The source of a pipeline leak linked to an oil sheen on the St. Clair River has been identified in Sarnia, more than a week after the incident first came to light.

Sun-Canadian Pipe Line reported the leak was pinpointed Saturday morning, nine days after the company said it became aware of the issue on March 12. The initial sheen was detected the evening of March 11 by Suncor at its Sarnia refinery, prompting an immediate response and early containment efforts on the water.

The affected section of pipeline remains shut down as cleanup operations continue in the area near Sun Avenue and St. Clair Parkway, within the city’s petrochemical district. Crews have deployed containment booms and absorbent materials both at the discharge point and along the river to limit environmental impact.

Provincial officials say no additional discharge has been observed since the initial sheen was identified. The Ministry of the Environment, Conservation and Parks continues to monitor the situation and assess information from both Suncor and Sun-Canadian as cleanup and investigation work progresses. Authorities are also reviewing whether any compliance action may be required.

The Technical Standards and Safety Authority has launched an investigation to determine the cause of the leak. The regulator oversees pipeline safety across Ontario and has confirmed the impacted section of infrastructure remains offline.

Local First Nations have been closely watching developments. Aamjiwnaang First Nation, located adjacent to the industrial area, has raised concerns about a lack of clear information regarding the size and extent of the spill. The community has also requested assistance managing increased truck traffic, as fuel that would normally move through the pipeline is being redirected by road.

Further downstream, Walpole Island First Nation reported earlier that the spill had been contained and its water system was not affected.

Sun-Canadian, which was established in 1953 to transport refined petroleum products from Sarnia-area refineries to markets across southwestern Ontario, has stated that emergency procedures were activated once the issue was identified. The company continues to work with environmental response teams and local authorities as part of an ongoing integrity assessment and cleanup effort.

The incident has renewed attention on the age and condition of pipeline infrastructure in the region. A previous rupture involving the same company in 2013 released tens of thousands of litres of diesel after corrosion weakened the pipe wall. That spill reached the stormwater system and the St. Clair River, prompting precautionary measures including temporary closure of downstream drinking water intakes.

While officials now indicate the current situation is contained, monitoring and remediation efforts remain ongoing as investigators work to determine the cause and ensure the safety of surrounding communities and waterways.