Third Depot Lake Dam Environmental Assessment

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Current Status

Quinte Conservation is contacting any interested persons, Indigenous communities, and provincial and federal ministries and agencies, with specific expertise relevant to the problem being addressed, for their input into the preparation of a baseline inventory.

Project Background

In 2021, Quinte Conservation undertook a Seepage Study at Third Depot Lake Dam. The report identified a seepage path through the steel water barrier in the middle of the main dam. It also suggested that through the 50+ year lifespan of the dam the internal sheet pile system may have become significantly deteriorated. The study recommended that Quinte Conservation investigate the system by exposing sections of the sheet pile to determine if the theoretical deterioration matched the actual conditions. 

In 2022, Quinte Conservation exposed the sheet pile in three locations and had a professional engineer inspect the conditions. It was found that the thickness of the sheet pile had been reduced by as much as 85%, the sheet pile seams are significantly deteriorated, and the remaining metal is now prone to rock puncture. The consultant recommended that Quinte Conservation begin the process to repair or replace the sheet pile as soon as possible.

In 2023, Quinte Conservation began an options analysis to determine the best path forward. Five options were presented: 

  • Option 1: Do Nothing
  • Option 2: Dam Decommissioning
  • Option 3: Cement Bentonite Wall
  • Option 4: Secant Pile Wall
  • Option 5: New Structure Downstream of Existing Dam

Quinte Conservation is now completing an environmental assessment which is being completed in accordance with the Conservation Ontario’s Class Environmental Assessment for Remedial Flood and Erosion Control Projects. The Class EA process includes consultations with interested persons, Indigenous communities, and provincial and federal ministries and agencies, characterization of the study area and the identification, and evaluation of alternatives using sound criteria to select the technically preferred alternative. This study will investigate the potential environmental, social and economic impacts of the alternatives, and identify measures to mitigate any adverse impacts.

This project is being carried out in accordance with the process for Conservation Ontario’s Class EA for Remedial Flood and Erosion Control Projects under the Environmental Assessment Act.

A Class EA characterizes the study area, identifies alternative solutions, evaluates each alternative’s potential impacts on the natural, cultural, social and economic environments, and identifies measures to mitigate potential adverse effects. The EA process ensures that interested persons, Indigenous communities, and provincial and federal ministries and agencies are engaged at key points during the study to identify and consider options for resolving the issue.

The project officially launched in May 2025 with a Notice of Intent for the Third Depot Lake Dam Class EA being issued to interested persons, Indigenous communities, and provincial and federal ministries and agencies.

Quinte Conservation is currently contacting any interested persons, Indigenous communities, and provincial and federal ministries and agencies with specific expertise relevant to the problem being addressed for their input into the preparation of a baseline inventory. 

A Community Liaison Committee (CLC) was established to hear various perspectives, and obtain input at key points in the study process in advance of engaging the broader public through more traditional consultation means. 

While public comments are encouraged throughout the process, Quinte Conservation will reach out at the following milestones as defined in the Conservation Ontario Class Environmental Assessment for Remedial Flood and Erosion Control Projects. 

Project Initiation
Notifications sent to interested persons, Indigenous communities, and provincial and federal ministries and agencies.

Preparation of a Baseline Environmental Inventory
Interested persons, Indigenous communities, and provincial and federal ministries or agencies, with specific expertise relevant to the problem being addressed, will be contacted for their input into the inventory process. 

Project Plan (PP)
This PP shall be filed and made available on Quinte Conservation's website and at the Conservation Authority office for a 30-day comment period, following the posting of the Notice of Completion. 

Environmental Study Report (ESR)/Notice of Completion
In this regard, a second notice, referred to as the Notice of Completion, will be given, stating that an ESR has been prepared for the project and is available to view on the Quinte Conservation's website and at the Conservation Authority office.

Following this filing of the ESR and issuance of the Notice of Completion, a comment period of 30 days will be provided to interested persons, Indigenous communities, and provincial and federal ministries and agencies to review and provide comments.

2025-04-30 Notice of Intent

Contact

Mike Smith
Capital Projects Coordinator
Phone: 613-968-3434 ext. 125
Email: msmith@quinteconservation.ca

Christine Philibert
Water Resources Manager
Phone: 613-968-3434 ext. 130
Email: cphilibert@quinteconservation.ca

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