St. Clair Transmission Line

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 Transformer 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.

Read the draft ESR

Expected Completion Date


Current Project Phase


We're here to help you

To provide comments or to be added to the project contact list, please call or email:

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We want to hear from you!

The draft Environmental Study Report is available for public review and comment from November 6 to December 7.

Help us build a line that reflects the interests and needs of your community by sharing your feedback to Hydro One Community Relations at
or 1-877-345-6799.

View Draft ESR Highlights

Hard copies are available at the following locations:

  • Corunna Library 417 Lyndoch Street, Corunna
  • Chatham-Kent Public Library 120 Queen Street, Chatham
  • Wallaceburg Municipal Office 786 Dufferin Avenue, Wallaceburg
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Project Maps

Since the start of this project in February 2022, we have received feedback and completed environmental studies to select a route that minimizes the impacts to the natural environment and leverages the opportunity to replace existing electrical infrastructure and repurpose existing transmission line corridors.

Interactive Map View PDF
St.Clair preferred map Enlarge (.PDF)

Refined Route Alternatives

Detailed refined route alternatives

Route alternatives

Detailed route alternatives

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 design and 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.

EA Process Image

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, 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.

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 important to the successful development of this critical line in Southwest Ontario. Since February 2022, we have heard from residents through meetings, email, phone, workshops, community open houses and surveys/comment forms. The local knowledge we have received about the environment, including the natural and socio-economic environment, has helped us to select a route that minimizes adverse effects to the environment. On balance, the route scored favorably in the natural environment, Indigenous culture, values and land use and socio-economic areas.

Our goal is to continue hearing as much local input as possible about the preferred route so that we can work towards building a line that community members and property owners can see their feedback reflected in.

Please provide your feedback at any time by contacting Hydro One Community Relations at or 1-877-345-6799 to join our project contact list and stay involved.

What happens after the draft Environmental Study Report (ESR) review period?

Following the public review and comment period for the draft ESR, comments received will be addressed in the final ESR Report, which will be filed to the Ministry of the Environment, Conservation and Parks (MECP).

We remain committed to working closely with community members. The draft ESR includes the identification of potential effects of the new transmission line and measures to avoid or mitigate adverse effects.

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 will affects to agricultural operations be mitigated?

We know the important role farmers have in supporting Ontario’s economy and we are committed to minimize potential affects to agricultural operations during and after construction. These measures, as outlined in Chapter 7 of the draft Environmental Study Report include, using existing access as much as possible and building new roads to the minimum length and width, avoid and protect tile drains, proactively communicate work activities with farmers that may disturb livestock and consult on mitigation measures such as moving or containing the livestock, restore land following construction activities.

Public Consultation

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Anticipated Project Schedule

February 2022
Notice of Commencement
March 2022
Virtual Community Open House #1; Introduction of Project
Fall 2022
Community Open House #2; Update on Project
June 2023
Community Open House #3; Selection of Preferred Route
Fall 2023
Draft Environmental Study Report (ESR) 30-day comment period
Late 2023
Submit final ESR and complete the Class EA process
2025 - 2026
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

We’re here to help You

To provide comments or to be added to the project contact list, please call or email: