St. Marys River: Area of Concern

The St. Marys River was designated as a binational Area of Concern (AOC) in 1987 under the Canada-U.S. Great Lakes Water Quality Agreement. Industrial and wastewater contamination along with changes to the watercourse led to its degraded water quality and environmental health. Nine out of 14 beneficial use impairments (BUIs) were identified, which measure the environmental, human health or economic impact of poor water quality. One additional beneficial use was deemed “requiring further assessment”, meaning more information was required to determine whether it was impaired.


Over the past 30 years, there has been significant progress in restoring the water and environmental quality of the AOC. On the Canadian side, this includes:

  • compliance with industrial regulations introduced in the mid-1990s, which drastically reduced the entry of contaminants from the local steel mill and contaminants from the local paper mill, the latter of which eventually closed in 2012
  • upgrades to the City of Sault Ste. Marie’s largest wastewater treatment plant in 2006, and the implementation of a Stormwater Management Master Plan in 2015 to better manage urban runoff and reduce pollution from entering the river
  • removal of over 31,000 cubic meters of contaminated sediment from the Algoma Steel boat slip, which prevents additional contaminants from entering the river
  • restored fish and wildlife habitat, including a naturalization project in the Bar River tributary to reduce sedimentation, expand habitat and allow for better fish-spawning

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”:

  • bird or animal deformities or reproduction problems (2016)
  • eutrophication or undesirable algae (2018)
  • beach closings (2018)
  • degradation of aesthetics (2018)

Work continues on restoring the remaining beneficial uses:

  • restrictions on fish and wildlife consumption – wildlife consumption is not impaired and an analysis of fish contaminants and consumption advisories will be conducted as well as a community survey on fish consumption habits
  • degradation of fish and wildlife populations – monitoring results show a relatively healthy fish and wildlife community and an assessment report proposing redesignation to “not impaired” is undergoing community review
  • restrictions on dredging activities – implementation of the In-water and Dredging Administrative Controls Document, which is a guidance document to meet the established restoration criteria and will become part of the Sediment Management Strategy currently under development
  • fish tumours or other deformities – a fish tumour survey will be conducted to determine current fish tumour rates, which have already dropped from 11% to 6% between 2009 and 2017
  • degradation of benthos – a Sediment Management Strategy is being developed to outline specific plans and actions needed for sites across the AOC
  • loss of fish and wildlife habitat – there is no impairment of wildlife habitat and efforts are underway to improve aquatic habitat for fish, specifically around Whitefish Island

Recent actions

The overall health of the St. Marys River has continued to improve through these recent actions:

  • in 2017 and 2019, over 17,000 cubic meters of contaminated sediment was dredged and removed from the Algoma Steel boat slip and a post-dredge assessment is underway to evaluate the extent of remaining contamination and next steps

Remaining actions

We 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. Priorities are to:

  • complete community engagement on the Sediment Management Strategy, which outlines specific plans for sites in the AOC, including actions needed and associated timelines
  • advance efforts to improve fish and wildlife habitat, specifically working with the Batchewana First Nation on the Whitefish Island Habitat Project, which proposes to naturalize a cold water stream and add fish nursery sites 


The St. Marys River has seen significant progress towards restoration since its designation as an AOC. Under the Canada-Ontario Agreement on Great Lakes Water Quality and Ecosystem Health, we will work with the province of Ontario to continue making progress towards remediation, environmental recovery and restoration of beneficial uses. 

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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