St. Clair River: Area of Concern

The contributions of binational, federal, provincial and local agencies, local industries, and other community partners continue to have a positive impact upon the water quality and ecosystem health within the Canadian section of the St. Clair River Area of Concern (AOC).

Why was it listed as an Area of Concern?

The St. Clair River was designated as an AOC in 1985 because available data and field studies indicated that water quality and environmental health were severely degraded. A history of industrialization, urbanization and agricultural land use activities on the St. Clair River and in its tributary watersheds resulted in nine of the Great Lakes Water Quality Agreement's 14 beneficial use indicators (BUIs) of quality being deemed as impaired and three identified as requiring further assessment.

What has been accomplished?

There has been significant progress over the past twenty-five years in restoring the water and environmental quality of the St. Clair River largely through legislative measures that have significantly reduced contaminant loads to the river from industrial and municipal sources. For example, implementation of the Municipal Industrial Strategy for Abatement program, introduced in the early 1990’s, provided a framework to control toxic contaminants in the petroleum and inorganic chemical sectors, both of which are prevalent in Sarnia. The result was a 75% reduction in contaminant loads to the river. A clean up of 13 300 cubic metres of contaminated sediment by Dow Chemical in 2002 resulted in improved water and sediment quality. Municipal infrastructure upgrades also reduced bacteria and unsightly discharges that impacted local beaches and the aesthetics of the river.  

Today on the Canadian side of the St. Clair River AOC, three beneficial uses have been restored to a “not impaired” status: tainting of fish and wildlife flavour in 2011, added costs to industry and agriculture in 2012, and degradation of aesthetics in 2016. A further two BUIs have met their restoration criteria and consultations are underway towards their re-designation to “not impaired” status which is expected in 2017. Four years of fish and wildlife studies have concluded and status reports are being prepared for the three beneficial uses that had been identified as requiring further assessment.   

Significant progress has been made in restoring the “Loss of Fish and Wildlife Habitat” BUI where six of the seven restoration targets have been achieved. A discussion paper on the drinking water BUI has been written and input from consultations with the two First Nations, local communities and other stakeholders will help guide next steps to effectively address this impairment.

Other BUIs are “restrictions on fish and wildlife consumption”, and “degradation of benthos” (benthic organisms live in and on the bottom of the river). These impairments are showing some improvement however sediment remediation is needed in order to fully address the remaining issues.  

Recent actions that contributed to the overall improvement in the environmental health of the St. Clair River include:

  • In 2015, $30 Million was approved to upgrade City of Sarnia’s Wastewater System over five years. The upgrade includes improvements to pumping stations, waste water treatment plants and the sewer system.
  • Between 2006 and 2014, approximately 15 kilometres of combined sewers in Sarnia were separated resulting in a 40% (average) decrease in the volume of combined sewer overflows and wastewater plant bypasses into the St. Clair River. Sewer separation is a priority and work is ongoing.
  • Investment of $1.2 Million in an automated system to monitor wastewater flows into Sarnia’s 56 pumping stations will improve flow management and ultimately reduce the need for bypasses to the river.
  • In 2013, the Township of St. Clair located downstream from Sarnia, completed its $34.5 Million wastewater treatment plant at Courtright. The treatment plant at Corunna was decommissioned, thus eliminating a municipal wastewater discharge into the St. Clair River.
  • In 2013, a Sediment Management Options assessment was completed and extensive public consultation resulted in support for dredging at the sites where contaminated sediment remains.
  • In the past five years, support from Environment and Climate Change Canada’s Great Lakes Sustainability Fund, over 165 hectares of valuable wetland habitat has been restored in the priority areas of the AOC including Walpole Island and Mitchell’s Bay. Eight shoreline projects have restored two kilometres of nearshore fish habitat and controlled shoreline erosion.
  • Scientists have concluded four years of fish and wildlife related studies which will inform the status of four beneficial uses including: fish tumours or other deformities, loss of fish and wildlife habitat, degradation of fish and wildlife populations, restrictions on wildlife consumption, and bird or animal deformities or reproductive problems.

What’s left to do?

The short term priorities will be to:

  • Complete the re-designation process for 2 BUIs and draft assessment reports for the outstanding three beneficial uses that require further assessment;
  • Continue planning for the implementation of a sediment remediation project in order to improve the sediment and water quality in these areas and eliminate them as a source of contaminant exposure to the local benthos, fish and wildlife;  
  • Provide on-going scientific monitoring of water and sediment quality to track progress and guide remaining restoration efforts;
  • Support municipal infrastructure improvements and on-going maintenance of fish and wildlife habitat projects, particularly coastal wetland projects, to ensure they remain healthy and functional;
  • Encourage shoreline restoration to improve near-shore fish habitat.


The St. Clair River is a binational AOC, meaning that continued effort is required in both Canada and the United States to achieve delisting. Environment and Climate Change Canada will continue to work with local and provincial partners to support restoration actions and the environmental monitoring and assessment studies needed to confirm that environmental quality objectives are met. Under the Canada-Ontario Agreement on Great Lakes Water Quality and Ecosystem Health, Canada and Ontario will continue to make significant progress towards remedial action implementation, environmental recovery and restoration of beneficial uses in the St. Clair River AOC. It is anticipated that actions will be completed by 2020. 


Efforts on the Canadian side of the St. Clair River are undertaken in a partnership between the Government of Canada, other levels of government and non-government groups, including members of the public.

Undertaking environmental restoration requires a large amount of scientific and technical expertise, local knowledge and hard work. One agency or group cannot engage in such a large task on their own without the help of others.

Listed below are participants that have contributed to efforts on the Canadian side of the St. Clair River AOC:

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