Thunder Bay

We're rebuilding and restoring wildlife habitat around Thunder Bay!

Learn more about the two projects currently underway in the Thunder Bay AOC:

About the Thunder Bay AOC

The Thunder Bay AOC study area extends approximately 28 kilometres along the shoreline of Lake Superior and up to nine kilometres offshore from the City of Thunder Bay. It also includes the Thunder Bay watershed, which is the land area drained by the Kaministiquia River system and a number of smaller rivers and creeks.

For over 100 years, industrialization, navigational dredging and channelization, waste disposal, and the release of pollutants into Lake Superior. There has been a long history of discharges into the harbour, primarily from the forest products industry (e.g., pulp and paper mills). While this has led to economic development in the Thunder Bay area, it has also adversely impacted water quality and significantly degraded fish and wildlife habitat along the Thunder Bay waterfront.

For this reason, Thunder Bay was designated in 1987 as an Area of Concern (AOC). At that time, 11 of the Great Lakes Water Quality Agreement’s 14 Beneficial Use Indicators (BUIs) of ecological quality were deemed as impaired.

View a map of the Thunder Bay AOC project locations


Chemicals of concern included:

  • Dioxins/furans,
  • Polycyclic aromatic hydrocarbons (PAHs),
  • Creosote, polychlorinated biphenyls (PCBs),
  • Mercury

Concerns relating to the contamination:

  • Restrictions on fish consumption
  • Negative pressures on fish populations
  • Loss of species diversity
  • Contaminated benthos

Current Status & BUIs

The current state of the Thunder Bay AOC has been greatly improved since it was first listed as an AOC in 1987. Beneficial Use Impairments (BUIs) are changes in physical, chemical, and/or or biological properties that have impaired ecosystem benefits or uses. A status summary for the Thunder Bay Area of Concern follows:


BUIs are currently identified as impaired.

Degradation of Fish and Wildlife Populations, Loss fo Fish and Wildlife Habitat, and Degradation of Benthos.


BUI has been identified as requiring further assessment.

Restrictions on Fish and Wildlife Consumption.

Delisting Criteria

The following information sets out the criteria for removing, or “delisting,” the remaining impairments in the Thunder Bay Area of Concern.

Dynamics of Fish Populations

Delisting Criteria:
Fish populations will no longer be considered impaired when the fish community within the AOC has the following characteristics, as observed by the MNR Fish Community Index Netting (FCIN) program.

  • The fish community within the Thunder Bay AOC becomes similar to nearshore (0–80 m deep) fish communities adjacent to the AOC for a minimum of three consecutive years, as measured by the relative abundance (Catch Per Unit Effort) and species composition of the fish community.
  • The nearshore fish community should be dominated by self-sustaining populations of native species showing the following characteristics:

Lake Trout:

  • The mean age of lake trout is greater than eight years.
  • The length at the age of seven-year-old lake trout caught in the FCIN or harvested by the commercial fishery is stable and greater than 430 mm
  • *The FCIN and/or commercial catch becomes dominated by mature fish and many age classes

Lake Whitefish

  • Fish population is capable of supporting a commercial fishery with sustainable yields that do not exceed 0.51 kg/ha/yr (Busiahn 1990)
  • Maximum total annual mortality does not exceed 60-65%
  • Average age in the catch should be two years older than the age at which 50% of the population matures

Lake Sturgeon, Walleye and Brook Trout

The overall understanding of the population dynamics of these native species within Thunder Bay is limited, therefore it is difficult to establish population criteria. Efforts are currently underway to better understand these species and their habitat use within Thunder Bay and its tributaries. As a result, criteria that reflect lake sturgeon, walleye, and brook trout populations are covered under the loss of habitat delisting criteria.

Lead Agency: Ontario Ministry of Natural Resources and Forestry.
Status: Impaired

Loss of Fish Habitat

Delisting Criteria:
This beneficial use will no longer be impaired when the following habitat-related projects from the Thunder Bay Stage 2 RAP Report (2004) have been completed, evaluated for effectiveness, and areas support diverse self-sustaining biological communities:

  • Alleviation of water quality barriers to fish migration in the Kaministiquia River
  • Re-vegetation projects in McVicar Creek and McKellar River
  • Habitat improvements associated with the creation of Sanctuary Island at the mouth of McVicar Creek
  • Habitat remediation on McKellar River
  • Rehabilitation of walleye spawning habitat at Current River Estuary
  • Improving salmonid access to the upper reaches of the Current River
  • Implement the Slate River Watershed Management Plan
  • Monitoring to support lake sturgeon rehabilitation strategy
  • Implement plan for shoreline naturalization within the Thunder Bay AOC

In addition to the Stage 2 RAP projects, the following should also be completed:

  • Remaining and created wetlands are protected from further degradation through existing environmental legislation, with provincial standards used to inventory and classify wetlands within the Thunder Bay AOC
  • Provide unrestricted access to critical spawning habitat by providing adequate flow in the Kaministiquia River
  • Ensuring that native fish populations are not negatively affected by industrial water-use practices, including water intake and discharge

Lead Agency: Ontario Ministry of Natural Resources and Forestry
Status: Impaired

Fish Consumption Restrictions

Delisting Criteria:
This beneficial use will no longer be impaired when the fish consumption advisories in the AOC (inner and outer Harbour) are no more restrictive than the advisories for the same contaminants in an open water reference site (Schreiber Point to Sewell Point – Block 7), based on samples collected in the same time frame (<5 years) for a minimum of two consecutive studies.

Lead Agency: Ontario Ministry of the Environment and Climate Change
Status: Requires further assessment

Dynamics of Wildlife Populations

Delisting Criteria (proposed):
Monitoring data shows that the wildlife community (at a population level) does not differ significantly from the abundance that would be expected for the amount and quality of physical, chemical and biological habitat typical of the AOC.


The wildlife community (at a population level) does not differ significantly from suitable Lake Superior reference sites.

(Adopted from the International Joint Commission)
Status: Impaired.


Loss of Wildlife Habitat

Delisting Criteria:

The Wildlife beneficial use will no longer be impaired when riparian/coastal and wetland habitat within the Thunder Bay AOC is in compliance with the guidelines set out through Environment Canada’s How Much Habitat is Enough (2013):

  • Wetland Habitat: “At a minimum, the greater of (a) 10% of each major watershed and 6% of each subwatershed, or (b) 40% of the historic watershed wetland coverage, should be protected and restored.”
  • Riparian Habitat: “Both sides of streams should have a minimum 30-metre-wide naturally vegetated riparian area to provide and protect aquatic habitat…so that 75% of stream length should be naturally vegetated.”
  • Coastal Habitat: There is no guideline for this habitat type


This beneficial use will no longer be impaired when no fewer than 4-5 riparian or coastal habitat improvement projects (restoration, enhancement, or creation) have been implemented in the Thunder Bay AOC. An external Thunder Bay AOC Wildlife Habitat Strategy will guide the implementation of the habitat improvement projects.

In addition, remaining and created wetlands must be protected from further degradation through existing environmental legislation. Provincial standards should be used to inventory and classify wetlands within the Thunder Bay AOC.

Status: Impaired.

Degradation of Benthos

Delisting Criteria:
Benthic community impairments were originally identified in three locations within the Thunder Bay Area of Concern: the Kaministiquia River, the area adjacent to the Northern Wood Preservers (NWP) property, and the area adjacent to the former Cascades Fine Paper property (“North Harbour”). Each of the identified sites has its own unique characteristics, contaminants of concern, and prescribed management action, and therefore requires distinct delisting criteria.

Lower Kaministiquia River (including Mission & McKeller Rivers):
This BUI will no longer be impaired when monitoring data indicates that benthic invertebrate communities and contaminant concentrations in sediment from the lower Kaministiquia River, Mission River, and the McKellar River remain stable (similar to 2005 data), or are improving.

Northern Wood Preservers Site:
The Northern Wood Preservers Alternative Remediation Project for Contaminated Sediment (NOWPARC) was completed in 2003. Benthos will no longer be impaired when monitoring data indicates that the benthic community from the NOWPARC area is similar to the benthic community in other parts of the harbour.

North Harbour Industrial Site:
This BUI will no longer be impaired when:

  1. Monitoring data indicates that contaminant concentrations in sediment and/or benthos from the North Harbour are showing a declining trend in concentrations and benthic communities are improving; and
  2. Site-specific criteria have been met (or objectives accomplished) as per the sediment management plan (to be added when available).

Status: Impaired.

Work Completed to Date

Over the past 30 years, thanks to the incredible support from our community partners, the Thunder Bay Area of Concern has seen significant improvements to ecosystem health.

The remedial actions undertaken and identified within the Stage 2 Report are currently in the process of being reviewed by the Thunder Bay AOC Public Advisory Committee (PAC). The PAC is an organization comprised of members of the public, including organizations, private citizens, academia, industry, recreational groups and property owners. The involvement of the PAC in the Thunder Bay Remedial Action Plan has been extensive and integral to RAP success. The combination of local knowledge and community based goals with scientific data and expertise has resulted in a practical strategy to rehabilitate the Area of Concern. PAC cooperation, understanding and stewardship have assisted the RAP since inception of the program.

Public Advisory Committee Terms of Reference (as passed by PAC members, December 6, 2017)

The two project currently underway in the Thunder Bay AOC are the Thunder Bay Habitat Strategy and the North Harbour Sediment Remedition Project. Learn more about both below.

Habitat Strategy

The Thunder Bay Habitat Strategy was developed by the North Shore Remedial Action Plan office in partnership with various community partners. Engagement on the Strategy and its habitat projects took place throughout 2020 and 2021.

The strategy was developed to inform and guide the implementation of coastal and riparian habitat improvement projects in order to address the Wildlife Habitat Beneficial Use Impairment delisting criteria of completing 4-5 major habitat improvement projects in lieu of reaching Environment Canada’s How Much Habitat is Enough Guidelines. 

The strategy currently consists of 5 proposed remediation projects along the Thunder Bay Harbour waterfront and a selection of riparian improvement projects on Harbour tributaries.

Read about each project here:

Recently, the Thunder Bay Habitat Strategy has taken off, and projects are happening around the AOC with our many great partners. Over $600,000 was announced to fund habitat projects around Thunder Bay through Environment and Climate Change Canada’s Great Lakes Protection Initiative. These projects include the Pool 6 and Superior Fine Papers restoration areas. You can learn more about our habitat work around Thunder Bay here.

On November 16th, we held a Public Advisory Committee Meeting to share the findings from the Ontario Ministry of Environment, Conservation & Parks’ most recent study on water and sediment in the lower Kaministiqua River. The study found that toxicity and benthic community structures have shown similar trends of gradual improvement since 2005. Recovery has now slowed, as the system is reflective of an urbanized river.

The PAC also heard from Transport Canada and Environment Canada about the progress made in the efforts to remediate the Thunder Bay North Harbour Sediment Clean-Up Project. The project is in the engineering design phase for the preferred sediment management option of an onsite confined disposal facility.

Another PAC meeting is anticipated for the new year to hear an update on the Habitat Strategy and the Ministry of Natural Resources and Foretry’s assessment of fish populations in the Thunder Bay Harbour.

Learn more about the Thunder Bay Habitat Strategy

North Harbour

The photos speak for themselves: Thunder Bay’s North Harbour faces a serious issue. North Harbour is one of the main restoration projects within the Thunder Bay AOC. The site consists of about 400,000 cubic meters of contaminated organic sediment deposited by a pulp and paper mill over the course of 90 years. Mercury concentrations in the contaminated sediment range from 2 to 11 ppm at the surface of the sediment to 21 ppm at depth. The sediment layer itself ranges from 40 to 380 centimetres thick and covers an area of approximately 26 hectares. Composed of a relatively fibrous material, the sediment’s consistency makes it difficult to deal with, as options for capping aren’t considered feasible. 

Over the past 15 years, the Public Advisory Committee (PAC) for the Thunder Bay AOC has sought public input on the contamination and remediation efforts. The PAC has received a variety of information on the contaminated sediment and the different options available to remediate it (Sediment Management Options or SMOs). Over the years the PAC has received a variety of information on the contaminated sediment and the different options available to remediate it.  Over the years, the public reviewed and commented on these reports, and the PAC compiled a selection of these responses. Links to these reports, presentations, and public comments are presented below.

April 2010 – North Harbour Steering Committee (NHSC) Response to PAC Questions
October 2010 – Questions and Answers for the NHSC from September PAC Meeting
November 2011 – Answers to Questions generated at October PAC Meeting
December 2011 – Letter from the PAC to the NHSC
February 2012 – PAC Meeting Minutes
December 2012 – PAC Meeting Minutes
February 2013 – Answers to Questions generated at February PAC Meeting
April 2013 – Questions to Franz Environmental generated at April PAC Meeting
September 2013 – Updated North Harbour from Jamie Saunders for PAC Meeting
November 2013 – PAC Meeting Minutes
March 2014 – PAC Questions and Answers to Cole Engineering Presentation
March 2014 –Public’s Questions and Answers to Cole Engineering Presentation
March 2016 – Letter sent to federal and provincial MPPs, Chronicle Journal, Port Authority

Moving from Phase I to Phase II

In 2019 the PAC selected SMO A, which proposes to create an on-site disposal facility where the contaminated sediment will be partially dredged and stored in a confined disposal facility. There are three phases to the TBNH Sediment Remediation Project:

Phase 1

Selection of the preferred Sediment Management Option (SMO).


Phase 2

Complete engineering design.

In Progress

Phase 3

Implementation and monitoring

Up Next

Currently, the project is in the engineering phase. To read a full version of the memorandum that documents the work completed by the Committee for Phase 1 (selection of the preferred SMO), click here.

Read more about the North Harbour Sediment Remediation Project

In the coming years, the RAP will continue to implement the Thunder Bay Habitat Strategy with partners around the city. Most of these projects are expected to be complete by the end of 2025, though monitoring may continue well after.

The management of the North Harbour Sediment Remediation project continues to be a major focus for the RAP, with Transport Canada leading the project as the owners of the site. This project is expected to be completed by 2032. The RAP office, along with local communities, the MECP and ECCC, are also assessing the status of fish consumption within the Thunder Bay AOC. Surveys were conducted in the AOC over the past 2 years and will be summarized to understand whether contaminants in fish are restrictive to current consumption rates within the AOC.


1991 – Stage 1 Report was developed by the Thunder Bay RAP writing team comprised of Environment Canada, the Ontario Ministry of Natural Resources, the Department of Fisheries and Oceans and the Ontario Ministry of the Environment. This report identified beneficial use impairments in the Thunder Bay AOC.

2004 – Stage 2 Report was drafted by the former Lake Superior Programs Office with the assistance of the Thunder Bay RAP team and Public Advisory Committee. Water use goals and restoration actions to achieve these goals were outlined. A number of these projects have since been completed with several of them ongoing to date.

2012– Stage 2 Update Report. An update on the Thunder Bay Remedial Action Plan for the years between 2009-2012, prepared by Lakehead University. This update highlights work that has been done within the Area of Concern and outlines various actions being undertaken to address the remaining beneficial use impairments.

Looking for more information on the Thunder Bay Area of Concern?

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