Southwest Ontario Bulk Planning Initiatives

A bulk transmission plan was completed for the Windsor-Essex region and development work is currently underway for two bulk transmission projects in the Kingsville-Leamington area:

While these projects will reinforce the existing West of Chatham interface (the 230 kV transmission path from Chatham to Lakeshore) and ensure that adequate electricity supply is available to meet the Windsor-Essex region’s growing electricity needs and support economic growth in the area, there are still transmission limitations in the areas east of Chatham. A West of London bulk transmission plan is being developed to address these transmission limitations impacting the connection of load growth focused in Kingsville, Leamington, Lakeshore and Dresden. The report will examine emerging electricity needs, evaluate options and recommend actions required to reinforce the bulk system in advance of regional electricity planning that is anticipated to commence for Chatham-Kent/Lambton/Sarnia in early 2021. A public webinar was held on November 26 to provide an overview of the West of London Bulk Study and seek input on the defined needs and potential solutions and written feedback was collected until December 17. View the recorded webinar and IESO responses to feedback received.

West of London Map

West of London

Windsor-Essex Bulk Report

This report documents the outcomes of a planning study that was initiated to assess the adequacy of the bulk transmission system in the Windsor-Essex Region and recommends two transmission reinforcements to meet the identified near- and mid-term needs (a switching station at the Leamington Junction and the West of Chatham transmission line). This study was triggered by recent unprecedented growth in forecast electricity usage for the greenhouse sector in the Kingsville-Leamington area. The level of growth is significant ΜΆ  forecasted to double the region’s electrical demand over the next five years. 

While the scope of this study is related to the bulk system supplying the Windsor-Essex Region, there is a companion integrated regional resource plan (“IRRP”) for the Windsor-Essex Region that has been completed, focused on providing customers in the region with adequate line connection and step-down transformation capacity, and maintaining a level of reliability consistent with accepted planning standards. Information from the IRRP, such as demand forecasts and plans for new connection facilities inform this bulk planning study. Recommended solutions in both studies have been integrated as they impact bulk and regional needs.

The IESO will continue to monitor the progress of load and generation developments in the area while studying future system needs east of Chatham through the on-going Windsor-Essex addendum study. Future stages of system reinforcement will be triggered as required.

Switching Station at Leamington Junction (Lakeshore TS)

On January 31, 2019 the IESO issued a hand-off letter to Hydro One requesting that they undertake work to establish a new switching station on the existing 230 kV transmission corridor between Chatham and Windsor at the Leamington Junction (Lakeshore TS). This station is expected to be completed as early as 2022. This will help meet the electricity needs in the area by supporting additional consumer connections, and is an integral part of the reliable long-term plan to improve supply the Windsor-Essex region.

Transmission Line from Chatham to Lakeshore (North of Leamington)

On June 13, 2019, the IESO issued a hand-off letter to Hydro One requesting that they initiate the work and activities, including seeking Environmental Assessment and Leave-to-Construct approvals, leading to the construction of a new 230 kV double-circuit line from Chatham to the site of the new switching station north of Leamington. This line is expected to be completed prior to the winter of 2025/2026.

The approximate locations of these proposed electricity transmission facilities are shown in the map below. The locations are shown for illustrative purposes only, as the specific sites and/or routes have not yet been determined.

Hydro One will be beginning development work in the coming months, where there will be opportunities for public involvement, including from municipalities, communities, and Indigenous communities.

Documents referenced on this page, but not posted, can be obtained by contacting with a link to the web page that lists the document and advise whether it needs to be provided in an accessible format. Please allow a minimum of one business day for a response.

Map showing transmission lines and switching station in Southwest Ontario

Key Resources

Windsor-Essex Bulk Report

Need for Bulk Transmission Reinforcement in the Windsor-Essex Region

Switching Station at Leamington Junction (Lakeshore TS)

IESO Letter to Hydro One re Leamington Switching Station

Hydro One Lakeshore Transformer Station Project

Transmission Line from Chatham to Lakeshore (North of Leamington)

IESO Letter to Hydro One re Transmission Line from Chatham to Lakeshore

Chatham to North Leamington Transmission Backgrounder