St. Marys 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. Marys River Area of Concern (AOC).

Why it was listed as an Area of Concern

The St. Marys River was designated as an AOC because a review of available data indicated that water quality and environmental health were severely degraded. Pollution from local industries, insufficiently treated municipal wastewater, and other pollutant sources historically contributed to the environmental issues within the St. Marys River. The river has also been physically modified to accommodate ship navigation, vehicle and rail transportation, and hydroelectric power generation. Cumulatively, these issues have led to reduced water quality, contaminated sediments on the river bottom, and have impacted fish and wildlife habitat and resulted in 10 of the Great Lakes Water Quality Agreement's 14 beneficial use indicators of quality being deemed as impaired.

What has been accomplished

Through the combined efforts of Environment and Climate Change Canada, the Province of Ontario, local industry, concerned citizens and other partners, major strides have been made on improving water quality and ecosystem health in the St. Marys River AOC:

  • All actions have been completed for municipal and industrial wastewater treatment. Major improvements in water quality have been achieved as a result of the implementation of federal pulp and paper regulations, the Fisheries Act and the Province of Ontario’s Municipal Industrial Strategy for Abatement regulations in the mid-1990s
  • In anticipation of these regulatory requirements, and in an effort to reduce adverse impacts, process changes and upgrades to the treatment processes were implemented at the local steel mill that reduced the amount of oil and grease entering the river by 96%, suspended solids by 94%, odour-causing phenols by 99%, and ammonia by 95%. Before it ceased operations in 2012, the local paper mill reduced wastewater contaminants in its effluent significantly, reducing suspended solids by 91%, biological oxygen demand (BOD) by 97%, and phenols by 95%
  • As a result of a $77 Million infrastructure investment in the mid-2000s supported by $47 Million in federal and provincial grants and $30 Million in local funds, the City of Sault Ste. Marie in Ontario upgraded its wastewater treatment plant in the east end of town, reducing BOD by 96%, suspended solids by almost 90%, and phosphorus levels by 91%. In 2015, the City of Sault Ste. Marie began implementing a stormwater management master plan to better manage urban runoff and reduce pollution entering the river
  • Due to improved environmental quality in the AOC, there is no evidence of impairment in colonial waterbirds within the AOC: no physical deformities have been detected in chicks or adults; there are low contaminant levels in bird eggs; and the reproductive success for birds studied within the AOC is similar to the Lake Huron region. As a result, the bird and animal deformities and reproduction problems beneficial use was designated “not impaired’ in 2016
  • With federal and provincial financial support, Algoma University conducted multi-year water quality studies to evaluate the state of aesthetics, eutrophication and undesirable algae, and beaches along the river. The conclusion is these 3 beneficial uses are not impaired, and  the designation for each was changed to “not impaired’ in 2018

What’s left to do

Efforts are  focused on addressing contaminated sediment and fish and wildlife habitat in the St. Marys River.

A multi-agency technical team has been working toward developing a sediment management plan appropriate for the river. Co-led by Environment and Climate Change Canada and the Ontario Ministry of the Environment, Conservation and Parks  with representation from local stakeholders, this technical team has directed field studies to gather information needed to make an informed decision on how to manage contaminated sediment in the AOC. Community engagement is also underway.  

There has been some habitat restoration work undertaken, including a naturalization project within the Bar River (a tributary to the St. Marys River) that involved youth groups planting trees on a number of properties to reduce sedimentation, expand habitat, allow for better fish-spawning. Planning is underway to restore more aquatic habitat, as Environment and Climate Change Canada and community partners are discussing project designs around Whitefish Island to benefit fish and wildlife populations.


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. Marys River AOC. It is anticipated that actions will be completed beyond 2020.


Efforts in the St. Marys 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 contribute to efforts in the St. Marys River AOC, specifically for the Canadian section:

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