AOC ABCs – An Introduction to Lake Superior “Areas of Concern”
Posted on: May 6, 2019
Environmental Areas of Concern, or “AOCs” are dotted around the entire Great Lakes system.


Environment and Climate Change Canada defines an Area of Concern, or “AOC,” as a location on the Great Lakes which has “experienced high levels of environmental harm.” Cleanup or “Remedial Action Plans” were developed to deal with issues identified at each of these locations. 


AOCs are found at specific locations around the entire Great Lakes. Forty-three such locations were identified in 1987, 12 of which are in Canada, 26 of which are in USA and 5 of which straddle the border in “binational” interconnecting waterways like the St. Marys River draining Lake Superior.

On Lake Superior, AOCs are found at the following locations:



  • St. Louis River (Duluth-Superior Harbour including the lower St. Louis River)
  • Torch Lake (on Michigan’s Keweenaw Peninsula)
  • Deer Lake (Marquette County, Michigan and removed from the list of AOCs in 2014 after cleanup completion)



Former fine papers mill on the Current River section of the Thunder Bay waterfront. Many environmental problems in Great Lakes Areas of Concern deal with legacy issues from extensive waterfront industrialization. (Photo: Ontario Ministry of the Environment, Conservation and Parks)

A clean environment allows us to drink the water, swim in the water and eat the fish. Remedial Action Plans have the primary goal of restoring such beneficial uses of the environment. Each Area of Concern has unique problems, some of which have already been addressed through remedial actions. The overall list of impairments for Great Lakes Areas of Concern includes the following:

  • Restrictions on Fish and Wildlife Consumption 
  • Tainting of Fish and Wildlife Flavour
  • Degraded Fish and Wildlife Populations
  • Fish Tumours or other Deformities
  • Bird (or other Animal) Deformities or Reproduction Problems
  • Degradation of Benthos (bottom dwelling organisms)
  • Restrictions on Dredging Activities
  • Eutrophication or Undesirable Algae
  • Restrictions on Drinking Water Consumption or Taste and Odour Problems
  • Beach Closings
  • Degradation of Aesthetics
  • Added Costs to Agriculture or Industry
  • Degradation of Phytoplankton and Zooplankton Populations
  • Loss of Fish and Wildlife Habitat


The following is a brief overview of key accomplishments:

Thunder Bay

A $20 million creosote cleanup project was completed in 2003. The project resulted in 32,000 cubic metres of highly contaminated sediment being contained or removed from the harbour. Five hectares of fish habitat were also created.

Nipigon Bay

The Nipigon Wastewatwater Treatment Plant was completed in 2011 leading to improved water quality in the Nipigon Bay Area of Concern. (Photo:

The Town of Nipigon constructed a new water pollution control plant thereby improving water quality in the lower Nipigon River. The Town of Red Rock will also be constructing a new water pollution control plant. Red Rock Town Council Minutes of March 4th indicate that Aegus Construction will build the new plant starting on May 1st. The minutes say the price tag is $21.5 million. (scroll to page 7927, Resolution #8).

Red Rock Town Council Minutes of April 1st indicate that start date for construction of the new plant will be May 1, 2019 (scroll to page 7938, items “K” and “L” under the Chief Administrative Officer’s Report).

Jackfish Bay

In May 2011, Jackfish Bay was officially re-designated as an Area of Concern (AOC) in Recovery, signifying that a long-term monitoring plan has been implemented to track and confirm environmental recovery. 

Federal and provincial pulp and paper regulations are fundamental to maintain progress. The Governments of Canada and Ontario continue to assess fish health and water and sediment quality, and will continue to enforce regulations to ensure the pulp and paper mill complies with the federal and provincial regulatory requirements.

Peninsula Harbour

A 7 million dollar remediation project at Peninsula Harbour was completed in 2012. The project was carried out to address contamination from mercury and other substances used in the pulp and paper industry. (Photo:

In 2012, a $7 million project placed 15 to 20 centimetres of clean sand on top of the most contaminated sediment in Peninsula Harbour. This process is known as thin-layer capping. The project was completed to address sediment contaminated with mercury and other substances used in the pulp and paper industry. Thin-layer capping creates clean fish habitat, stops the spread of contaminated sediment, and reduces risk to fish, fish-eating birds, mammals and people. 

Thunder Bay Harbour is contaminated with mercury and other substances associated with the pulp and paper industry at this site adjacent to a former mill in Current River. Concerted effort is being put forward by the Thunder Bay Remedial Action Plan to develop a cleanup plan for this site. (Photo: Ontario Ministry of the Environment, Conservation and Parks)


In Thunder Bay, an area of mercury contamination in the northern portion of the harbour remains a major challenge. Options have been identified for dealing with this material and a 13 member working group hopes to select a preferred cleanup method by 2020. The working group includes representatives from government, Indigenous communities, surrounding harbour land owners and the public.

In Nipigon Bay, construction of the new Red Rock Water Pollution Control Plant is scheduled to begin on May 1st.

At Jackfish Bay, intensive environmental monitoring is being carried out to better quantify environmental conditions. Once this information is in hand it will be presented to community members in the Terrace Bay – Schreiber area. At Peninsula Harbour, effort is now focused on environmental monitoring to determine the effectiveness of the thin-layer cap in assisting environmental recovery. This includes such aspects as recolonization of the harbour floor by bottom dwelling organisms.

Future Infosuperior articles will provide more detailed information about key Remedial Action Plan efforts. Such efforts include cleanup of contaminated sites in Lake Superior and rehabiliation of degraded habitat. 


Remedial Action Plans for Canadian Areas of Concern on Lake Superior are supported by Environment and Climate Change Canada, the Ontario Ministry of the Environment, Conservation and Parks, the Ontario Ministry of Natural Resources and Forestry and Lakehead University.

Remedial Action Plans for U.S. Areas of Concern on Lake Superior are supported federally by the U.S. Environmental Protection Agency and by state environmental agencies in each state bordering Lake Superior, namely Minnesota, Wisconsin and Michigan.

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