Map of Peninsula Harbour Area of Concern

The International Joint Commission (IJC) first identified peninsula Harbour as an Area of Concern (AOC), in 1987. Peninsula Harbour’s Area of Concern is located approximately 290 km from Thunder Bay on the north shore of Lake Superior. The AOC is comprised of two regions: Peninsula Harbour and a portion of open Lake Superior immediately south of the Peninsula; it is roughly bounded by the watershed of the harbour and Pebble Beach, includes the Town of Marathon and extends four kilometers into Lake Superior.

In 1991, Marathon community members came together to form a Public Advisory committee, which assisted federal and provincial agencies in developing the first stage of the RAP for Peninsula Harbour. This plan was developed to identify environmental problems and determine sources of pollution in the AOC.

The harbour was identified as an AOC as a result of problems associated with bacterial contamination, aesthetic impairment, degraded fish and benthic communities, and high levels of toxic contamination (i.e. mercury and PCBs) in the fish and bottom sediments

Peninsula Harbour Remedial Action Plan Timeline

1991: The Stage 1 Remedial Action Plan (RAP) Report for the Peninsula Harbour AOC identified 5 beneficial uses as “impaired”, 11 as “not impaired” and 1 as “requiring further assessment”.

2012: The Stage 2 Remedial Strategies for Ecosystem Restoration identified 2 beneficial uses that remained “impaired” (Restrictions on Fish Consumption and the Degradation of Benthos) and 2 requiring further assessment (Degradation of Fish and Wildlife Populations and the Loss of Fish and Wildlife Habitat).

Peninsula Harbour Area of Concern Sediment Capping Project

Overview of Peninsula Harbour Sediment Capping Project (Environment Canada)

Elevated levels of mercury and PCBs accumulated in the Jellicoe Cove portion of Peninsula Harbour adjacent to a former pulp mill. The source of harbour mercury was a chlor-alkali plant which at one time operated beside the pulp mill.  To create clean habitat for plants and animals and to accelerate natural recovery, Environment Canada and Ontario Ministry of the Environment put in place a project to cap this contaminated sediment with clean sand. The project was completed during the summer of 2012. The integrity of the cap and “re-colonization” of the area by bottom dwelling organisms, including plants, will be monitored for the next 20 years. The capping project is the last major action required to address environmental concerns in Peninsula Harbour.

The first post-cap long-term monitoring (LTM) survey was completed in 2017 and demonstrated that the thin-layer sediment cap is effective and met the goals and objectives of the remedial effort. View additional photos here.

KEY DOCUMENTS relating to Peninsula Harbour

Peninsula Harbour – Status Report (2020)
Summary of remedial and monitoring activities undertaken over the history of the Peninsula Harbour Remedial Action Plan (RAP), and an update on the status of beneficial use impairments (BUIs) within the Area of Concern (AOC) as of 2020. The report also proposes “Not Impaired” status for BUIs where evidence supports improved conditions and delisting criteria have been met.
Jellicoe Cove Thin-Layer Cap Long-Term Monitoring (MECP 2019)
The first post-cap LTM survey has demonstrated that the thin-layer sediment cap is effective and met the goals and objectives of the remedial effort. Natural sedimentation has, and continues to occur. Biological surveys also indicate that the cap has been colonized with benthic invertebrates and that the coverage of submerged aquatic vegetation continues over time.
Submerged Aquatic Vegetation and Cap Movement Study (Northern Bioscience 2018)
Northern Bioscience study of the submerged aquatic vegetation levels and mobilization of the cap material 5-years post-capping.
Update on Sediment Cap Monitoring (Environment Canada 2014)
An update on the monitoring results from the Peninsula Harbour Area of Concern sediment management plan.
Water Quality Monitoring During Capping (AECOM 2012)
Report by AECOM about the water quality monitoring during capping operations.
Environmental Assessment screening (AECOM 2012)
The proposed project to cover, or cap, the contaminated sediments in Jellicoe Cove, Peninsula Harbour was subject to an environmental assessment according to the Canadian Environmental Assessment Act (CEAA). This report was prepared by AECOM.
Stage 2 Report (2012)
The Stage 2 Report for the Peninsula Harbour Area of Concern laid out the remedial strategies for Ecosystem Restoration
Peninsula Harbour Fish Habitat Assessment (Northern Bioscience 2011)
Review of fish habitat to support an environmental assessment of proposed capping of mercury and PCB-contaminated sediments in Jellicoe Cove.
Environmental Risk Assessment (Environ 2008)
Environ evaluated risks posed by mercury and polychlorinated biphenyls (PCBs) in the Peninsula Harbour Area of Concern.
Stage 1 Report (1991)
This is the Stage 1 Report for the Peninsula Harbour Area of Concern which identified the environmental conditions and defined the problem for future remediation work.

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