Saint-Bruno-de-Montarville, February 22, 2024

Press Release

The modernization of the Beauharnois–Les Cèdres complex will get underway with rehabilitation work on Coteau-1 and Coteau-3 damsStart of the draft design ahead of the project to modernize the Beauharnois–Les Cèdres complex

Hydro-Québec is announcing the start of the draft design ahead of the project to overhaul Coteau-1 and Coteau-3 dams, which are nearly a century old, to ensure their long-term operability and increase their capacity in compliance with current standards.

Potential project scenarios will be assessed during the draft design, which will be completed in 2026. The following phases will encompass the preliminary work and then the rehabilitation itself, which is expected to start in 2029.

Better integration of the hydropower facilities into their environment
The draft design aims chiefly to establish the optimal course of action and includes:

  • Consulting local Indigenous and non-Indigenous communities to develop a project that integrates their goals
  • Coordinating all studies required to define the technical content, constraints, permitting requirements and impacts on the environment
  • Developing of the project execution strategy
  • Identifying and managing project risks
  • Developing schedules and project estimates

“This draft-design study is a first step towards the modernization of the Beauharnois–Les Cèdres complex. In the decades ahead, our infrastructure renovations will require investments, and we want to involve stakeholders from the outset to ensure the project’s social acceptability,” said Yannick Chevrier-Bédard, Manager – Construction Projects.

Built by the Beauharnois Light, Heat and Power Company, Coteau-1 (built in 1933) and Coteau-3 (built in 1940) are two of four dams designed to regulate water levels in Lac Saint-François and facilitate the flow to the Canal de Beauharnois and the headrace canal for Les Cèdres generating station.

Spanning 320 meters, Coteau-1 dam has 20 openings with 18 gates. Coteau-3 dam is 270 meters long and has 16 gates. The necessary rehabilitation work is part of a broad portfolio of major investments to modernize the Beauharnois–Les Cèdres complex and will be carried out in addition to the priority work that began in 2021 based on surveys of all the structures on the Fleuve Saint-Laurent (St. Lawrence River) and Canal de Beauharnois.

For more information, go to


Philippe Cyr
Tel.: 514 289-5005

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