Areas of Concern

What are Areas of Concern?


These are locations within the Great Lakes watersheds that have been identified as having experienced high levels of environmental harm due to human activity. The St. Lawrence River at Cornwall was designated an Area of Concern (AOC) in 1987 by the International Joint Commission (a bi-national agency supervising transboundary water quality and water levels in Canada and U.S.), under the Great Lakes Water Quality Agreement between Canada and the United States.

Currently, 12 such designated areas are on the Canadian side of the Great Lakes, 26 in the United States, and 5 are shared by both countries. The St. Lawrence River Area of Concern at Cornwall / Akwesasne / Massena is one of these bi-national areas. In each Area of Concern, government, Indigenous, community, and industry partners are undertaking a coordinated effort to address identified environmental challenges through a Remedial Action Plan (RAP).

Why are We an Area of Concern?


The St. Lawrence River (Cornwall) 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.

The status of an AOC is determined by assessing the state of local environmental conditions against fourteen different Beneficial Use Impairments (BUIs), as identified in the Great Lakes Water Quality Agreement. Each BUI describes a human or ecological use of the ecosystem that has been lost or impaired as the result of environmental degradation. The clean-up, or remediation, of an AOC occurs through a mandated process called a Remedial Action Plan (RAP). A site-specific RAP is required for each AOC.

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 Cornwall Sediment Strategy, jointly led by Environment and Climate Change and the Ontario Ministry of the Environment, Conservation and Parks was completed in 2005. This significant accomplishment established administrative controls to protect sediments in the river from disturbance by any future waterfront development. Because the original sources of mercury to the river have been eliminated, it was determined that the best way to deal with these pockets of contaminated sediment was to leave them in place and allow cleaner sediment to settle on top of them.

The Government of Canada, the Province of Ontario and the City of Cornwall provided funding to upgrade Cornwall’s wastewater treatment plant, which has 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 storm water pond reduced the number of combined sewers and combined sewer overflow events.

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.

Implementation of a 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. The Remedial Action Plan team continues to work on environmental challenges identified within the Canadian portion of the St. Lawrence River AOC that include the following issues:


  • Restrictions on Fish and Wildlife Consumption
  • Degradation of Fish and Wildlife Populations
  • Fish Tumours / Other Deformities
  • Eutrophication or Undesirable Algae
  • Degradation of Phytoplankton and Zooplankton Populations
  • Loss of Fish and Wildlife Habitat