St. Clair Transmission Line

Expected Completion Date 2028
Current Project Phase Planning

Energizing life for people and communities through a network built for the possibilities of tomorrow.

As the population grows in southwestern Ontario, safe and reliable power is needed to improve reliability for homes and businesses, secure and diversify supply, and create opportunities for industries to locate in the area. That’s why Hydro One is proposing to construct a new double-circuit 230 kilovolt transmission line between our Lambton Transmission Station, located in St. Clair Township and our Chatham Switching Station, located in the Municipality of Chatham-Kent.

This project is part of a network of electricity infrastructure projects that will support the regions’ economic growth. Once built, the St. Clair Transmission Line will support local food supply and security, economic development and job creation. We’re completing the planning stage now, so that we can be ready to bring additional power to the region when and where it’s needed.

We want to hear from you

To provide comments or to be added to the project contact list, please call or email: 1-877-345-6799
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Watch this Video to Learn More about the Preferred Route

Watch the St. Clair Transmission Line Project

Project Maps

Since the start of this project in February 2022, we have received feedback from Indigenous communities, property owners, residents, community members, stakeholders, businesses and technical advisors and have conducted detailed field studies. Based on our diligent review and evaluation, Route Alternative 2 has been selected as the preferred route for the new transmission line. This route was selected as it minimizes the impacts on the natural environment and leverages the opportunity to replace existing electrical infrastructure and repurpose existing transmission line corridors.

View our interactive map

Preferred Route

Project Area Map Enlarge (.PDF)

Refined Route Alternatives

Detailed refined route alternatives

Route alternatives

Detailed route alternatives

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Planning Process

An integral part of this project requires the completion of a Class Environmental Assessment (Class EA), in accordance with the Ontario Environmental Assessment Act. Rooted in community engagement and consultation, the Class EA evaluated proposed alternative routes for the new line that minimize social, economic and environmental effects.

As Hydro One continues its study of the preferred route, we are committed to listening and incorporating your feedback into the planning stages of this project. We want to ensure all directly affected property owners understand the work required on their property and continue have the opportunity to provide feedback.

Following completion of the Class EA, the project will also require Ontario Energy Board (OEB) approval under Section 92 (Leave to Construct) of the Ontario Energy Board Act.

Frequently Asked Questions

What is the need for the project?

In Ontario, the Independent Electricity System Operator (IESO) is responsible for ensuring that future energy needs are being met. According to the IESO, agricultural electricity demand in the Windsor-Essex and Chatham areas is expected to quadruple by 2035.

To support this growth in southwest Ontario, the IESO requested Hydro One begin development work in March 2021 to build a new transmission line between our Lambton Transformer Station in and Chatham Switching Station.

How did you identify the alternative routes?

As a part of the Class Environmental Assessment our team conducted preliminary work to identify 5 viable route alternatives for the new transmission line, which consider existing baseline information about the environment, such as waterbodies, residential areas, environmentally significant areas and we looked for opportunities to parallel linear infrastructure and utilize existing corridors where such opportunities were available.

Why was Route 2 selected as the preferred route?

Since February 2022, we’ve sought feedback and completed studies to identify and evaluate five route alternatives to select a preferred route. Input from Indigenous communities and residents, agencies and the public has been crucial, as well as environmental, technical, and other considerations, in determining the preferred route for the new line.

We used this data to evaluate the route alternatives and select a preferred route that balances the natural and socio-economic environments, technical and cost considerations, and Indigenous culture, values and land use. We continue to welcome any feedback on the preferred route to help ensure the final route is considerate of community interests.

How is feedback used as part of the Class Environmental Assessment process?

Your feedback is an important part of the planning process for the project. Our team has been collecting input through meetings, email, phone, workshops, community open houses and surveys/comment forms to help us build a line that is considerate of the interests and needs of the community.

To date, your local knowledge about the environment, including the natural and socio-economic environment, has helped us to better assess the route alternatives to select a preferred route that minimizes adverse effects to the environment. As the project progresses, your input about the preferred route can help us identify potential environmental effects and ways to avoid, mitigate or restore Project effects.

Please provide your feedback at any time by contacting Hydro One Community Relations at or 1-877-345-6799.

What happens now that a preferred route is selected?

With the selection of a preferred route, the next steps include completing an assessment to identify potential effects of the new transmission line and identifying measures to avoid or mitigate adverse effects, progressing with the detailed design of the transmission line (including tower designs and placements) and construction planning, working with directly impacted property owners, and compiling a draft Environmental Study Report for public review and comment.

We’ll continue seeking feedback as we work towards a final route that is considerate of community interests. In designing the line, flexibility may be considered on a property-by-property basis to best mitigate effects to properties traversed by the line where practicable and feasible. For example, this could include slight deviations within the right-of-way, bringing towers closer to road, considering larger spanning or spacing distances.

How big are the towers going to be?

With the selection of a preferred route, we can begin the detailed engineering design, which will influence the size, location and number of towers required, as well as the right-of-way width.

That said, Hydro One has been powering southwestern Ontario for over 100 years and we know the typical right-of-way required for a 230-kilovolt transmission line is approximately 46 metres in width. We also anticipate the typical tower footprint will range from 6 metres x 6 metres to 12 metres x 12 metres, depending on the tower design. The typical tower height is influenced by environmental conditions like topography, and we anticipate will range between 30 metres and 60 metres.

How are effects to agricultural operations being considered?

As we continue our environmental and construction planning for this project, we will look for opportunities to avoid, protect and prevent damage to environmental features and properties, such as soil compaction and interference with tile drainage, to the extent practical and, ensure that work areas are restored following the completion of construction.

It is our goal to build a line that is considerate of the interests and needs of the community. Feedback gathered through ongoing consultation with farmers and other community members will be considered in the selection of tower design, construction methodologies, operations and maintenance procedures.

Anticipated Project Schedule

Notice of Commencement
Virtual Community Open House #1; Introduction of Project
Community Open House #2; Update on Project
Community Open House #3; Selection of Preferred Route
Release of draft Environmental Study Report (ESR); Report for 30-day review period
Submit final ESR and complete the Class EA process
Completion of detailed design and other permits and approvals, including Section 92 approval from the Ontario Energy Board.
Construction to follow approvals
Proposed Line in-service