St. Lawrence River: Area of Concern

As of 2012, all actions required in the current St. Lawrence River (Cornwall) Remedial Action Plan (RAP) to restore water quality and ecosystem health were completed in the Canadian section of this Area of Concern (AOC).

Why was it listed as an Area of Concern?

The St. Lawrence River (Canadian section) was designated as an AOC because a review of available data indicated that water quality and environmental health were severely degraded. Cornwall, the largest urban centre in the AOC, has been a hub of industrial activity for more than 100 years. This legacy led to contamination issues in local waters affecting the aquatic environment. Contaminants also enter these waters from upstream sources via Lake Ontario and from the air. Other issues leading to its designation included development along the shoreline, and water flow changes that altered the natural features of the St. Lawrence River. 

What have we accomplished?

The implementation of federal and provincial pulp and paper regulations, and the provincial Municipal Industrial Strategy for Abatement regulations in the mid-1990s, led to process changes and upgrades to local wastewater treatment at pulp and paper mills. These efforts significantly improved water quality in the area, including the elimination of dioxins and furans in pulp mill discharges. 

All industrial discharges containing mercury have also been eliminated along the Cornwall waterfront, and there are no longer any sources of other heavy metals in the Cornwall area.

The Government of Canada, the Province of Ontario and the City of Cornwall provided funding to upgrade Cornwall’s wastewater treatment plant, which reduced nutrient loading to the St. Lawrence River. As part of the Cornwall Pollution Prevention and Control Program, the retrofit of the City of Cornwall's Fly Creek stormwater pond reduced the number of combined sewers and combined sewer overflow events.

The Cornwall Sediment Strategy, jointly led by Environment and Climate Change and the Ontario Ministry of the Environment and Climate Change, was completed in 2005. This significant accomplishment, involving scientists from both Environment and Climate Change Canada and the Ontario Ministry of the Environment and Climate Change, established administrative controls to protect contaminated sediments in the river from disturbance by any future waterfront development. By allowing cleaner sediment to settle on top of the highly contaminated sediments, the benthos (or riverbed community of organisms, an important part of the aquatic food chain) has been restored.

Fish populations and habitats have been significantly enhanced through regulations on fishing and the implementation of the Lake St. Francis Fisheries Management Plan. The construction of nearshore spawning and nursery reefs along the Cornwall waterfront has also helped to increase both population and diversity of fish in the AOC.

The implementation of the Tributary Restoration Program resulted in the planting of more than 85,000 trees and the installation of almost 50 kilometres of fencing to protect shoreline habitat.

What is left to do?

The St. Lawrence River (Cornwall) RAP delisting criteria are currently under review. 


Subject to the outcome of the delisting criteria review, it is anticipated that the Canadian section of the St. Lawrence River may be considered for delisting or AOC in Recovery status by 2019. 


Efforts in the St. Lawrence River (Canadian section) 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 its own, without the help of others.

Listed below are participants that have contributed to efforts in the St. Lawrence River (Canadian section):

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