Advancing Critical Transmission Expansion in the Toronto Area

On October 31, 2025, the Independent Electricity System Operator (IESO), released its Toronto Integrated Regional Resource Plan which recommended a new underwater transmission line (the “Toronto Third Line” project) connecting downtown Toronto to Bowmanville via Lake Ontario. This line is required to accommodate growth in Toronto and the Greater Toronto Area, improve grid resilience, diversify supply sources, and alleviate capacity strain in the province.

The Toronto Third Line project would be Ontario’s first underwater high voltage transmission network line and its first major domestic High Voltage Direct Current (HVDC) project. The proposed project provides a net new transmission system connection between Toronto and eastern Ontario via Bowmanville and offers unique system benefits and value in terms of strategic resilience and longer-term benefits for the City of Toronto, including:

• Enhancing system resilience by introducing a net new supply point for Toronto. This mitigates risks experienced by existing supply points which are vulnerable to extreme weather events such as flooding experienced in 2024;
• Alleviating strain on the bulk power system and avoiding additional system reinforcements elsewhere in the GTA. It is anticipated that the line would address anticipated needs in the region beyond 2044;
• Facilitating the connection of new generation supply, alleviating capacity needs on the grid;
• The potential to support the integration of Distributed Energy Resources (DERs) in the City of Toronto, which could enable the generation of energy from clean and renewable sources;
• The potential to facilitate “black start” capability (e.g., the ability to restore power following a local blackout), enabling more rapid return to supply in the event that there is an outage on the system; and,
• Avoiding more disruptive routing options through Toronto, which would require the expropriation of land and construction through heavily built-up urban areas.

Our proposed action for public feedback:

Consistent with the IESO’s recommendation, the Ministry of Energy and Mines (the ministry) is proposing to bring forward an order in council and Minister’s directive (Directive) pursuant to s. 25.32 of the Electricity Act, 1998 that would, subject to fulfillment of all applicable consultation obligations and receiving all required approvals, direct the IESO to undertake a competitive procurement process and enter into a procurement contract with a transmitter to develop and construct the Toronto Third Line project with an in service date of 2037 or sooner..

The IESO is best positioned to lead this process due to its expertise in conducting competitive procurements. This experience can be leveraged to facilitate an expedient selection process and provide clarity that is needed for the transmitter to begin development as soon as possible.

A competitive process is anticipated to drive cost effectiveness by soliciting proposals from a pool of transmitters with the expertise necessary to build this complex project, while a procurement contract has the potential to include necessary provisions to incent schedule adherence.

Furthermore, the ministry is proposing that the Directive include certain requirements to be implemented in the IESO’s procurement process (including requirements related to the Request for Proposals and transmission contract). The requirements would be intended to strengthen ratepayer protection, ensure meaningful engagement with Indigenous communities, incent Indigenous participation and partnerships, and encourage timely development of the project to the maximum benefit of Ontarians.

The ministry is seeking public feedback on whether and how the following proposed requirements should be included in the Directive. The ministry also welcomes input on any additional proposed criteria.

Proposed restrictions on transmitter eligibility

• The ministry is proposing that IESO’s RFP be limited to applicants that demonstrate the following: 
  Experience developing, building, and operating and mitigating environmental impacts associated with underwater transmission lines. This requirement may be demonstrated through partnerships or other arrangements with transmitters that possess this experience.
• Experience in engaging and working with Indigenous communities in Canada, including undertaking rights-based consultation within Treaty and traditional territories. This may be demonstrated through partnerships or other arrangements with organizations that possess this experience (e.g., other transmitters; consulting firms).

Proposed requirements on the evaluation criteria for transmitter selection

The ministry is proposing that evaluation criteria established by the IESO for transmitter selection consider the following:

• A plan for how the applicant would engage with Indigenous communities and support their capacity to be consulted and participate in the project.
• Offers for Indigenous economic participation in the project, which could include but is not limited to equity participation, supply chain opportunities, training, and employment opportunities.
• Incentives intended to maximize the participation of and support of Ontario and Canadian businesses in the procurement.

Proposed requirements on the procurement contract

The ministry is proposing to direct the IESO to, after completing its transmitter selection process, enter into a contract with the selected transmitter that includes contract terms that:

• Provide accountability mechanisms with respect to the transmitter’s economic participation commitments to Indigenous communities, as well as commitments to supporting Ontario and Canadian businesses.
• Incentivize schedule adherence to an in-service date.
• Incorporate cost containment mechanisms in a manner that will be incorporated into the Ontario Energy Board’s rate regulation process, as required.
• Ensure contract fulfillment is conditional on obtaining all applicable environmental approvals and other permits, including fulfilling any delegated procedural aspects of the Duty to Consult in respect of the approval or permit.

Consultation with Indigenous Communities on this Proposal:

The provincial Crown is committed to fulfilling its Duty to Consult with Indigenous communities in respect of its conduct that may have the potential to adversely impact Aboriginal and treaty rights protected under Section 35 of Canada’s Constitution Act, 1982 (s. 35 rights). The ministry will provide information about the proposed transmission project and the above policy actions to potentially impacted Indigenous communities, including information about how they can participate in the consultation process at this early stage of project development.

This includes an opportunity to review and provide comments about this proposal through the Environmental Registry of Ontario (ERO), as well as early rights-based consultation opportunities for potentially impacted Indigenous communities, including opportunities to share their input about the proposed Directive to the IESO and any potential for impacts to s. 35 rights directly with ministry staff.

In addition, should the proposal move forward, the province expects to delegate the procedural aspects of the Crown’s Duty to Consult to the selected transmitter, as appropriate, in respect of the proposed Toronto Third Line project, which may be fulfilled through the Class Environmental Assessment for Transmission Facilities and other provincial regulatory approvals and permits, as appropriate.

Timing:

Depending on the outcomes of consultation, including early rights-based with Indigenous communities, the ministry anticipates bringing this proposal forward for a possible decision in 2026. The IESO would endeavour to have a transmitter selected within 18 months of receiving the proposed Directive, if government decides to proceed with this proposal.

Environmental Impact:

Like all infrastructure projects, transmission projects have the potential to impact land, local environments and ecosystems, and waters. This proposal does not impact the existing requirement for the selected transmitter to obtain all required government permits and approvals and comply with any applicable requirements under the Environmental Assessment Act, 1990, prior to proceeding with the project. These approvals include requirements for the transmitter to consult with Indigenous communities, the public, and stakeholders on the proposed project, including in the determination of the exact path of the line, its impacts to the environment, and any appropriate mitigation measures.

Building transmission infrastructure is essential for maintaining Ontario’s affordable, secure, reliable and clean energy advantage. Success in achieving these objectives could have significant positive impacts on the environment. The Toronto Third Line project, if completed, will enable a more resilient provincial grid that can facilitate new local energy sources, energy storage, and the implementation of energy efficiency strategies.