Northeast Ontario Bulk Planning

Electricity demand in Northeast Ontario is growing, particularly in the City of Sault Ste. Marie and City of Timmins areas. This growth is primarily driven by strong economic development in mining and other industry, electrification and decarbonization initiatives and government policies such as Ontario’s Critical Minerals Strategy.

This electricity planning initiative examines forecasted constraints under various electricity supply and demand conditions – including specific large load connection scenarios, investigates reinforcement options, and identifies the nature, magnitude and timing for when the implementation of solutions would be required. A major focus of this work is to identify the needs to ensure the reliable supply to the substantial expected load growth forecast, while maintaining the required power transfers to supply the forecasted demand in the Northwest and the rest of the Northeast.

In response to this growing need, the IESO developed a new plan, Need for Northeast Bulk System Reinforcements, that recommends solutions to address the needs.

Informed by technical studies and engagement with local municipalities, businesses, Indigenous communities and rights-holders, and stakeholders, this plan recommends key recommendations to reinforce the transmission system including:

  • A new ~260 km single circuit 230 kV transmission line (built to 500 kV standards) between Wawa Transformer Station (TS) and Porcupine TS to be in-service in 2030;
  • A new ~205 km single circuit 500 kV transmission line between Mississagi TS and Hanmer TS 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 and Third Line TS 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.


The IESO engages with local and regional communities, stakeholders and the general public to seek input to help inform planning activities. Learn more about engagement on this electricity planning initiative.

Area Overview

Northeast Ontario lies north of Lake Huron and east of Lake Superior, stretching from the French River and Manitoulin Island in the south, to Timmins, Temiskaming Shores and Cochrane in the North. The northernmost communities include Attawapiskat, Fort Albany and Moosonee, and to the east it lies along the Quebec border, and to the west, it includes the communities of Chapleau, Foloyet and Kapuskasing. From an electricity planning perspective, Northeast Ontario is comprised of four planning regions (North & East of Sudbury, East Lake Superior, North of Moosonee and Sudbury/Algoma) and consists of two radial 115 kV interconnection points with Quebec.

Northeast Ontario Bulk Planning Map


Three public webinars have been to keep all interested parties informed of this work and provide opportunities for input. Visit the engagement webpage to view past meeting materials, feedback received and IESO responses.