East Ontario

The Eastern Ontario Bulk Plan identified near-term actions and long-term options to ensure the transmission system can reliably support forecast growth driven by industrial development and increasing electrification. The plan examined constraints on the region's high-voltage transmission system, reliability needs in the Ottawa and Belleville areas, opportunities to connect future generation resources to serve eastern Ontario, including new nuclear in southern and central Ontario; and to strengthen interconnections, particularly for exports, with neighbouring jurisdictions.

The IESO has recommended transmission infrastructure reinforcements in two stages, making investments that are essential today while preserving options for additional investments that will only be made when needed.

Implementation-ready actions are infrastructure investments that should be initiated immediately, given typical development timeframes, to be in-service by the early-2030s. This will meet the needs of communities and businesses in the area based on plans shared with the IESO through its engagements. These include:

• station upgrades in Ottawa and Belleville
• new lines connecting Cornwall–Ottawa and Greater Napanee–Belleville
• competitive procurement of new supply resources in the Belleville/Greater Napanee regions to service local needs
• additional electricity demand-side management savings to reduce overall costs

Together, these recommendations improve transmission capability needed to connect new customers and supply resources and lay a foundation for increased exports.

Future-consideration actions are potential reinforcements associated with longer-term demand growth, future generation development, and evolving policy direction. These actions should only proceed should conditions evolve beyond what implementation-ready actions address — preserving flexibility and managing ratepayer risk. These include:

• a new transformer station in west Ottawa and Belleville
• a new Ottawa–Greater Napanee transmission line
• new lines in Ottawa connecting two existing stations to the new west Ottawa station

The IESO will continue to monitor system conditions and trigger the development of these reinforcements as needed.

Supporting Materials and Resources

Report: Eastern Ontario Bulk Plan

Backgrounder: Eastern Ontario Bulk Plan

Engagement Page

The Gatineau Corridor End-of-Life Study examined transmission equipment reaching end-of-life in the Gatineau transmission corridor, along with forecasted reliability concerns in the areas of Ottawa and Peterborough to Quinte West that are supplied by the circuits located within the corridor. To meet the needs, this plan recommended to:

• Refurbish all 800 km of 230 kV circuits on the Gatineau Corridor identified as nearing end of life
• Build a new transmission line into Dobbin TS (Peterborough) from either Cherrywood TS (Pickering) or Clarington TS (Clarington) with planned in-service of 2029
• Pursue up to 230 MW of additional system cost-effective energy efficiency in the Ottawa area through province-wide and Local Initiative Programs over the 20-year planning horizon, while monitoring demand growth and resource acquisition activities in the Ottawa area
• Update and expand the use of remedial action schemes in the Peterborough and Ottawa areas to meet planning standards and further improve both areas’ load-meeting capabilities

Supporting Materials and Resources

Report: Gatineau End-of-Life Study

Engagement Page

Hydro One – Durham Kawartha Power Line (Dobbin TS to Clarington TS)