St. Clair River: Area of Concern

The St. Clair River was designated a binational Area of Concern (AOC) in 1987 under the Canada-U.S. Great Lakes Water Quality Agreement. Years of industrialization, urbanization and agricultural land use activities led to severely degraded water quality and ecosystem health in the river and its tributary watersheds. Nine out of 14 beneficial use impairments (BUIs) were identified, which measure the environmental, human health or economic impact of poor water quality. A further three beneficial uses were deemed as “requiring further assessment”, meaning more information was required to determine whether they were impaired.


Over the past 30 years, there has been significant progress in restoring the water and environmental quality of the river. These include:

Restoration of beneficial uses 

Over the last decade, significant progress has been made to improve environmental conditions on the Canadian side. These beneficial uses are no longer considered “impaired”:

Work continues on restoring the remaining beneficial uses:

Recent actions

The overall health of the St. Clair River has improved through these recent actions:

Wastewater management:

Habitat restoration:


A sediment management project is underway to improve sediment and water quality in the three remaining priority areas within the AOC. In 2013, following an assessment study and public consultation, dredging was chosen as the preferred option to clean up mercury-contaminated sediment at the site. Between 2014 and 2018, a committee comprised of Environment and Climate Change Canada, the Ontario Ministry of Environment, Conservation and Parks and Dow Chemical Canada worked to establish a framework for working together and secure funding for a detailed engineering and design plan by spring 2021. The plan will outline actions required and estimated costs to implement the dredging option. The St. Clair Region Conservation Authority will be the project manager for this phase.

Remaining actions

The Government of Canada will continue to work with local and provincial partners to support restoration actions and the environmental monitoring and assessment studies needed to confirm environmental quality objectives are met. Short-term priorities are to:


The St. Clair River AOC has made significant progress, and it is anticipated that five of the six remaining BUIs will be restored by 2023. Restoration actions are nearly complete and plans are underway to remediate the three priority areas of contaminated sediment. Under the Canada-Ontario Agreement on Great Lakes Water Quality and Ecosystem Health, the Government of Canada works with the province of Ontario to continue making progress towards remediation, environmental recovery and restoration of beneficial uses. As a binational AOC, Canada and the United States continue to work closely together to achieve delisting. 

Our partners

On the Canadian side, we partner with other levels of government, non-government groups, Indigenous communities and members of the public. This restoration work requires a large amount of scientific and technical expertise, local knowledge, hard work and the help of:

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