Electricity demand in the Toronto region is projected to grow significantly over the next two decades. As part of the Toronto Integrated Regional Resource Plan (IRRP), the Independent Electricity System Operator (IESO) has identified the need for additional transmission capacity into Toronto to support long-term growth and system reliability.
The recommended solution is the Toronto Third Line (TTL), a proposed new underwater high-voltage direct current (HVDC) transmission connection between Clarington (Bowmanville Switching Station) and downtown Toronto via Lake Ontario.
On January 7, 2026, the Government of Ontario announced its intent to proceed with this first of its kind underwater transmission project and directed the IESO to launch a competitive procurement process, ensuring a transparent and cost effective approach to selecting the transmitter that will design, build, and operate the line. Designed to strengthen grid resilience, diversify supply pathways, and relieve emerging constraints on the existing transmission system in and around Toronto, the Toronto Third Line represents a critical investment in the city’s energy future.
This web page outlines the procurement approach and opportunities to participate in engagement activities.
The IESO will provide an overview of preliminary Request for Proposals (RFP) design concepts and high-level term sheet concepts and contract considerations. The session will also continue discussions on the proposed Indigenous Engagement and Participation Plan (IEPP) approach.
The IESO will provide an overview of project and procurement plans, including considerations for an Indigenous participation framework, and begin engagement on the design of a competitive procurement process for the Toronto Third Line.
