Construction of Brome substation and its supply line

The need for a new substation and supply line

The power grid has served the region for more than 100 years. The region’s high-voltage lines and substations are aging and have reached their full capacity.

The construction of Brome substation and its supply line is therefore essential to ensuring the region’s energy security. It will also reduce the number of electrical facilities needed in the region, in addition to making the grid more reliable and reducing the risk of major outages.

This project will also meet the growing needs of the local population. It will not be used to export electricity to the United States.

The substation and supply line are scheduled to be commissioned by 2030.

A rigorous consultation process

In January 2024, Hydro-Québec held preliminary consultations with municipalities, regional environmental groups, the Union des producteurs agricoles (UPA) and the regional county municipality (MRC) of Brome-Missisquoi to present the project and the study area.

Preserving landscapes and conserving the agricultural and built environments were priority concerns raised during the consultations. Hydro-Québec took them into account right from the draft-design stage.

In April 2025, we began public consultations on the substation’s location and the route variants for its supply line. Hydro-Québec received several proposals aimed at improving the project from the community during the consultations. Because it is committed to building the best possible project for the region, Hydro-Québec took the time to analyze each proposal.

Through this process, the company identified factors that are considered sensitive or important to the community, such as landscapes, agricultural land, proximity to residential neighborhoods, presence of an oil pipeline, tourist activities, wildlife habitats, the colline des Chênes and residential, commercial and industrial development projects.

Hydro-Québec assessed, among others, the following proposals:

Relocating the substation to the Pearson sandpit
Making the substation’s host area larger than initially proposed
Powering the sector at 69 kV
Using a 120-kV single-circuit supply line
Running the line along Route 104 and 139 in the area of Cowansville

Of these proposals, the company chose the one to make the substation’s host area larger than initially proposed. In addition to being technically feasible, this scenario made it possible to locate the new substation in a white zone and reduce the length of the supply line while maintaining forest cover to mitigate the substation’s visual impact.

The reports of these consultations are available in the Public consultation section.

Hydro-Québec analyzed the Route 104/139 option

At the request of local stakeholders, Hydro-Québec studied the possibility of running a line route along Route 104/139 in Cowansville.

In this scenario, the route follows Route 104/139 through southern Cowansville, crosses part of Dunham, then connects to the existing line in Lac-Brome before reaching the new Brome substation, which is also located in Lac-Brome.

We assessed this scenario from several perspectives:

Our transmission line specialists conducted a technical feasibility study.
We worked with the Ministère des Transports et de la Mobilité durable and the city of Cowansville.
We identified the main impacts on the natural and human environments.
We also assessed the estimated construction costs and schedule.

Advantages

The 104/139 scenario offers several environmental advantages:

Approximately 3 km of the route would run through an urban area.
At approximately 11 km, this route is slightly shorter than the other route variants: 18 km for Variant A; 12 km for Variant B; and 14 km for Variant C.
It avoids the habitats on colline des Chênes.
It follows the existing line and already developed areas, minimizing changes to the landscape.

Technical considerations and impacts

Part of the 120-kV line would be built along Route 104/139, in the area of Cowansville. This option would create impacts on built and human environments and carries significant constraints, both in terms of construction and compatibility with existing uses:

The presence of a sharp curve, as well as several buildings and other infrastructure, would require the installation of a greater number of towers, would probably require the relocation of some buildings and would limit development in part of Cowansville.
The area contains many underground utilities, including gas pipelines, water mains and sewers, as well as overhead telecommunications and power systems.
These constraints would require a specialized line design that would leave little flexibility for optimization to reduce the project’s impacts.

Overcoming these challenges would make the project more complex and riskier, and therefore more costly. The anticipated average construction cost would stand between $10 and $14 million per kilometre. By comparison, the costs authorized by the Régie de l’énergie for similar projects in the Estrie region range from $5 to $7 million per kilometre.

Impacts on energy security, residential areas and tourism

This option would delay construction of the line by an additional one to two years; however, the line is essential to ensuring the local population’s energy security. In addition, the towers and lines would be located close to homes, businesses and tourist attractions.

Implementing this scenario would result in an additional delay of one to two years for the construction of the line, even though it is crucial to the energy security of the local population.

In addition, the towers and conductors would be located near residences, businesses and tourist attractions.

Some landowners would face restrictions on the use of their property, and a business would need to be acquired.

The subdivision of lots would be required in certain areas.

The route would limit Cowansville's residential, commercial and industrial development potential. The line would pass near the Centre de la nature in Cowansville.

The towers would be visible from the Auberge West Brome, Lake Davignon, the equestrian centre and two maple syrup operations.

The line would run parallel to the Route des vins for just over one kilometre, pass near the charming villages tourist route and cross a scenic tourism route featuring picturesque landscapes.

Conclusion of the scenario analysis

Although it offers certain advantages, the Route 104/139 scenario would not significantly reduce environmental impacts and would substantially increase the risks associated with the project’s costs and construction schedule. Following its analysis, Hydro-Québec concluded that this option did not meet the feasibility criteria.

Hydro-Québec consults the public when its analysis of a route is conclusive. In this case, because the option did not meet the feasibility criteria, it was not submitted for public consultation.

Why route variant C was selected

The objective of every Hydro-Québec project is to identify the route that offers the best balance across the following criteria:

Technical requirements for constructing both the substation and the line
Environmental considerations
Factors that are important to the local population, such as protecting landscapes, agricultural land and the built environment
Project cost

Following extensive consultations and analyses, Hydro-Québec concluded that route variant C offered the best balance among these various criteria.

How we intend to improve the selected route

Now that the line route has been selected, Hydro-Québec wishes to continue working with affected property owners, residents, elected officials and organizations to improve the project and reduce its impacts on the factors that the local population deems important. Where possible, some adjustments can be made to the line route or line infrastructure, such as the line’s towers.

Hydro-Québec is therefore continuing to gather the public’s questions, comments and concerns. Collaborating with the public in this way helps us to improve the project and better meet the needs of the local population.

Documentation

Visual simulations

Work schedule

Preliminary consultation Summer–Fall 2024
Project consultation 2025–2026
Announcement of the optimized project Fall 2026
Permitting 2027–2028
Construction 2029–2030
Commissioning of the substation and the new line 2030

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