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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Map of Project Area and Route Alternatives

View our interactive map

Through technical studies and feedback, we’ve gained a more in-depth understanding of the study area for each of the alternative routes and have made three refinements to our routes and have identified the need to expand Chatham Switching Station, Lambton Transformer Station and a potential for Wallaceburg Transformer Station.

Refined Route Alternatives

Detailed maps of refined route alternatives

Route alternatives

Detailed maps of route alternatives

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Planning Process

We are committed to listening and incorporating your feedback into the planning stages of the proposed new transmission line. 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 will evaluate proposed alternative routes for the new line that minimize social, economic and environmental effects.

Engagement with Indigenous communities, government officials and agencies, interests persons and organizations throughout the project, through opportunities like community open houses, is critical to help us select a preferred route that considers the needs and interests of the region.

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 this new transmission line?

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 possible 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 easements.

Can the route follow existing infrastructure instead of a greenfield option?

Prior to the start of the Class Environmental Assessment, our team conducted preliminary work to identify to identify 5 possible route alternatives for the new transmission line, including opportunities to parallel existing transmission lines. During the Environmental Assessment process, we evaluate each of the route alternatives in an effort to select a preferred route that minimizes environmental effects.

Co-locating with existing linear infrastructure has the potential to offer several advantages, many of which are greater if co-locating with an existing transmission line, such as minimizing disturbance to natural areas and sensitive habitats by using existing access, reducing the width of new right-of-way required, minimizing visual effects, and decreasing overall operating costs.

How will the preferred route be selected?

A preferred route has not been selected at this time. As part of the environmental assessment process, we will be evaluating the alternative routes through consultation, environmental field studies and technical assessments. It is our goal to select a preferred route that will minimize adverse effects to the environment. Input from Indigenous communities, agencies and the public is crucial, along with environmental, technical, and other considerations, in determining the preferred route for the new line.

We anticipated a preferred route will be selected in Spring 2023 and will continue to keep community members informed and to seek your feedback. Please contact Hydro One Community Relations at or 1-877-345-6799 to join our project contact list and stay involved. Your feedback is valued.

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

Your feedback is an important part of the planning process for this proposed new transmission line. Our team has been collecting input since March 2022 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.

Your local knowledge about the environment, including the natural and socio-economic environment, will help us better assess the alternative routes to select a preferred route that minimizes adverse effects to the environment. Your input can also help us develop and prioritize the type of criteria that will be used to evaluate and compare each route before selecting a preferred route, as well as identify potential ways to avoid, mitigate or restore potential Project impacts.

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

What if the new line crosses my property?

Once a preferred route is selected for the new line, Hydro One will be able to determine the property requirements for the Project and work with directly impacted property owners who have a proposed structure or section of corridor on their property. Hydro One’s goal is to secure voluntary property settlements with affected property owners in a timely manner.

How big are the towers going to be and how wide will the corridor be?

We will know more accurately the size, location and number of towers required, as well as the right-of-way width after a preferred route is identified and we can complete the engineering design.

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.

As well, the typical footprint of a tower ranges from 8 metres x 8 metres to 14 metres x 14 metres, depending on the design. The typical height of a tower is influenced by environmental conditions like topography and range between 30 metres and 50 metres, depending on the design.

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 including soil compaction and drainage, to every extent possible and, where applicable, complete restoration.

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.

Additionally, once a preferred route is selected, a dedicated Hydro One real estate representative will work closely with directly impacted property owners who have the preferred right-of-way on their property. During these one-on-one conversations, we will collect information specific to their property.

Public Consultation

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
Expected Leave to Construct (Section 92) Application Approval
Proposed Construction Start
Proposed Line in-service