Northeast Ontario

The North of Sudbury Bulk Plan recommended transmission infrastructure reinforcements in the northeast to advance in two stages, making investments that are essential today while preserving options for additional investments that will proceed to construction only when necessary.

Implementation-Ready

Implementation-ready actions are the investments needed by the early- to mid-2030s to maintain reliability and support growing electricity demand in the North of Sudbury region. They include transmission line reinforcements, associated station expansions, and end-of-life reconductoring work to strengthen supply across the Kirkland Lake, Timmins–Iroquois Falls, Kapuskasing, and areas north and south of Timmins.

Future-Ready

Future-ready actions preserve the region's ability to respond to long-term growth and changing electricity needs. They involve advancing planning and development activities today—such as engineering, siting, environmental approvals, and land rights—while postponing construction until the need is confirmed.

To maintain future flexibility, the North of Sudbury Bulk Plan recommends early development work for two potential transmission lines: one between Sudbury and Timmins, and another between Fraserdale and Timmins. These projects could support future demand growth, strengthen reliability, expand transmission capacity, and enable new electricity supply opportunities, including renewable and hydroelectric resources.

Supporting Materials and Resources

Report: North of Sudbury Bulk Plan

Backgrounder: North of Sudbury Bulk Plan

Engagement Page

The Northern Ontario Bulk Study: North-South Transmission Reinforcement Plan was developed to support growing electricity demand in northern Ontario, driven by both economic development and organic demand growth. It also enables the siting of additional generation in the region by increasing transfer capability, helping Ontario meet its future energy and capacity needs, as identified in the 2024 and 2025 Annual Planning Outlook. This Plan provides recommendations to address electricity needs over the next 20 years. The identified needs are based on the demand growth anticipated in northern Ontario and the capability of the existing transmission system.

To address this need, the Plan recommends:

• Implementing a new single circuit 500 kV series-compensated transmission line between Hanmer TS (Sudbury) and Essa TS (Barrie) with an in-service date of 2032.
• Preserving future transmission options by beginning early development work on a possible second new 500 kV transmission line between Hanmer TS (Sudbury) and Essa TS (Barrie).
• Exploring strategic siting of cost-effective system generation in Northern Ontario, including baseload generation, where existing bulk transmission system capacity exists, to help defer the need for the second new 500 kV transmission line.

The Plan also provides further benefits beyond accommodating forecast load growth, which includes an increase of the power transfer capability between southern and northern Ontario that can accommodate higher growth scenarios; enable various types of supply resources, including variable/intermittent energy, peaking, baseload, and storage in northern Ontario; and provide a foundation and advance key development work to help reduce lead time for further transmission system expansions when required in the future.

Supporting Materials and Resources

Report: Northern Ontario Bulk Study: North-South Transmission Reinforcement Plan

Engagement Page

Hydro One: Sudbury Barrie Transmission Line (Hanmer TS to Essa TS)

The IESO conducted this study to provide a comprehensive and co-ordinated approach to assess the reactive power requirements of the northern Ontario bulk power system given expected system development.

Supporting Materials and Resources

Engagement Page

Report: Bulk System Reactive Requirement in Northern Ontario

Informed by technical studies and engagement with local municipalities, businesses, Indigenous communities and rights-holders, and stakeholders, the 2022 Need for Northeast Bulk System Reinforcements report recommended a series of investment to reinforce the transmission system:

• A new ~260 km single circuit 230 kV transmission line (built to 500 kV standards) between Wawa TS (Wawa) and Porcupine TS (Timmins) to be in-service in 2030;
• A new ~205 km single circuit 500 kV transmission line between Mississagi TS (near Wharncliffe) and Hanmer TS (Greater Sudbury) and addition of two new autotransformers at Mississagi TS to be in-service in 2029;
• A new ~75 km double circuit 230 kV transmission line between Mississagi TS (near Wharncliff) and Third Line TS (Sault Ste. Marie) to be in-service in 2029; and,
• Voltage Control devices identified in accordance with the detailed design of these new facilities.

The recommended plan provides further benefits beyond accommodating increased electricity demand such as:

• Increasing the power transfer capability from Sudbury to regions west of Sudbury by up to 900 MW to supply future loads located around the City of Sault Ste. Marie and within the Northwest region;
• Improving reliability for existing and future loads located around the City of Timmins;
• Strengthening the connection between the Northeast and the Northwest and improving the resiliency of the Northern Ontario transmission network; and,
• Providing a foundation and reserving the ability for further expansion in the future based on input from other relevant planning activities in the North.

Supporting Materials and Resources

Report: Need for Northeast Bulk System Reinforcements

Northeast Bulk Plan Data Tables

Engagement Page

Hydro One: Wawa Timmins Power Line (Wawa TS to Porcupine TS)

Hydro One: North Shore Link (Mississagi TS to Third Line TS)

Hydro One: Northeast Power Line (Mississagi TS to Hanmer TS)