East Ontario Bulk Planning

The new Gatineau Corridor End-of-Life Study (with Appendices) examines transmission equipment reaching end-of-life (EOL) in the Gatineau transmission corridor along with forecasted reliability concerns in the areas of Ottawa and Peterborough to Quinte West which are supplied by the circuits located within the corridor. Consideration of replacement options for EOL transmission facilities through an integrated planning process can ensure assets are renewed in a cost-effective manner that aligns with the evolution of the electricity system (e.g. decarbonization of the electricity sector and the economy) and new or emerging issues that have arisen in an area since the assets were originally constructed.

The study examines the scope of refurbishment for the EOL facilities in coordination with forecast reliability concerns in Ottawa and Peterborough to Quinte West. The reliability concerns addressed through the study include:

  • Approximately 800 km of the 230 kV circuits on the Gatineau Corridor (Oshawa to Ottawa) are expected to reach end-of-life over the next 5 to 10 years
  • The Load Meeting Capability (LMC) for the Ottawa area is forecast to be exceeded in the mid 2020’s
  • The LMC for the Peterborough to Quinte West area is insufficient today

Informed by technical studies and engagement with local municipalities, businesses, Indigenous communities and rights-holders, and stakeholders, this study recommends, an integrated solution package to address the transmission equipment end-of-life needs and accommodate the long-term demand forecast for the area including:

  • Refurbish all 800 km of 230 kV circuits on the Gatineau Corridor identified as nearing EOL
  • Build a new double circuit 230 kV transmission line into Dobbin TS (in Peterborough) from either Cherrywood TS (in Pickering) or Clarington TS (in Oshawa) with a 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 zone
  • Update and expand the use of remedial action schemes (RAS) in the Peterborough and Ottawa areas to meet planning standards and further improve both areas’ LMCs


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

Transmission system map delineating the Gatineau Bulk Study area

The Gatineau is a 300 km long transmission corridor that stretches between the Greater Toronto Area (GTA) East and Ottawa and passes through Peterborough. The corridor consists of five (5) 230 kV lines that were originally constructed in the late 1920’s and early 1930’s primarily to transfer power from the hydro electric facilities in eastern Ontario and Quebec to the province’s major load center in the GTA. The five lines have a combined length of 1300 line-kms, of which 800 line-kms have been identified by the facility owner as nearing EOL and requires a planning decision to be made. The Gatineau Corridor is highlighted in Figure 1 along with the key areas of interest (Peterborough to Quinte West and Ottawa).