Refining a protected corridor of land for future electricity transmission infrastructure in the Northwest Greater Toronto Area

What is Being Proposed 
MEM and the Independent Electricity System Operator (IESO) are proposing to refine the protected corridor of land, called the Narrowed Area of Interest (NAI), that is expected to be required to host critical electricity transmission infrastructure in the northwest Greater Toronto Area (GTA) region. This revision is the result of a milestone in the Northwest Greater Toronto Area GTA Transmission Corridor Identification Study (the “Study”). Updated design work on Highway 413 and updated electricity demand forecasts have provided greater clarity in respect of the land expected to be required to support future transmission infrastructure.

The revision would reduce the size of the protected NAI by approximately 70% and would protect only the land that is necessary to support updated electricity system needs in the region and to co-locate transmission infrastructure efficiently with Highway 413 and auxiliary highway land uses, while minimizing impacts to adjacent communities. The revised NAI will remain protected from development under the Provincial Planning Statement until the construction of transmission infrastructure. At this time, further portions of land may be released if not needed.  

Some of the lands that will be released from the NAI will be used for Highway 413.Concurrently with this consultation, the Ministry of Transportation (MTO) is preparing to finalize the route alignment for Highway 413 and designate the properties needed for the highway under the Public Transportation Highway and Improvement Act. MEM and MTO plan to coordinate the release of their respective land-use plans and protections, likely in December.

Why this Corridor is Needed
Halton, Peel and York are among the fastest growing regions in Ontario. Their demand for electricity exceeds the provincial average, and communities in these regions are expanding further away from existing transmission infrastructure. New transmission infrastructure will be vital to support new housing and economic development in these regions. Furthermore, the IESO has identified a need for transmission infrastructure that can transfer electricity from other regions in Ontario into and through northwestern GTA.

Energy for Generations, Ontario's first integrated energy plan dated June 12, 2025, indicated that corridor studies designed to identify and protect land that may be needed for future transmission infrastructure are critical to ensuring our electricity system can meet growing demands, especially in urban and rapidly developing regions where available land is scarce and electricity demand is growing rapidly. Preserving this land corridor now will:

• Avoid delays to project in-service dates to meet the pace of growth;
• Maximize co-location with Highway 413 to minimize land impacts, consistent with provincial policy under the Provincial Policy Statement;
• Avoid the need to build transmission infrastructure underground, which costs significantly more;
• Minimizes environmental impacts; and
• Provide certainty to municipal planners, landowners and developers.

How the Corridor was Identified
The proposed corridor is the result of a study that began in 2019, with the goal of identifying a corridor to host future transmission infrastructure to be co-located with Highway 413. Extensive technical analysis was undertaken to identify the narrowest possible corridor of land that can support both 230kV and 500kV transmission infrastructure, while retaining sufficient optionality for a future transmitter to design and build the most cost-effective transmission solution. Consistent with provincial policy, a key objective of the Study is to co-locate the transmission corridor with Highway 413, while minimizing impacts on natural areas and on already built-up areas. Informed by these guiding principles, and in close collaboration with MTO’s Highway 413 design team, MEM and IESO revised the Study’s NAI in 2020 and 2025, reflecting ongoing technical analysis of potential land corridors. MEM and IESO now have further clarity from the updated design of Highway 413 and the IESO’s updated electricity demand forecasts, which allow us to significantly narrow the NAI and are key inputs to the proposed revisions.

Throughout the process, MEM engaged with stakeholders to gather feedback on the corridor’s design and its guiding principles. Input from these engagements has helped shape this proposal.

Seeking Feedback
We are seeking feedback on the proposed final corridor.

A map illustrating the revised NAI is included in the supporting material below. It is also available as a data layer, which can be downloaded from Ontario’s Open Data Catalogue.

Next Steps
The revised NAI is defined as a planned corridor under the Provincial Planning Statement and thus remains subject to protections against development that could preclude or negatively affect the use of the corridor for the purpose for which it is identified. Retaining protections on these corridor lands will allow a future transmitter to evaluate and compare different infrastructure options to find the most cost-effective transmission routing and design solution.

Following this engagement, MEM will post a decision notice confirming the specific corridor lands that will be protected going forward within the revised NAI and confirm the lands MEM no longer has an interest in. While we do not anticipate any substantial revisions to the NAI in the future, additional lands may be released in as a transmitter makes specific infrastructure siting and routing decisions and determines certain lands are not needed.

Development of transmission infrastructure on the corridor lands will occur in stages, as the IESO identifies the scope and timing of specific transmission projects that are needed. In other words, multiple projects are expected to be constructed within the corridor at different times.  The IESO continues to study electricity transmission needs in this area through its regional planning processes for the GTA North and GTA West planning regions. Initial transmission investments are expected to occur in the corridor in the next 5-7 years, followed by further transmission projects that may be identified through future IESO electricity planning processes over time.

Once an infrastructure project has been recommended and a transmitter is selected to develop the project, the transmitter will undertake a Class Environmental Assessment, secure other appropriate permits (e.g., a Leave to Construct approval from the Ontario Energy Board) and acquire lands and/or land rights (e.g., easements) as necessary. The transmitter would then initiate construction and may end up releasing small portions of land that are not needed in the final corridor design.

Environmental Impact
Revisions to the Study’s NAI will have no direct environmental impacts in respect of the lands within the NAI. The Study will continue to preserve lands within the corridor for future transmission infrastructure but will not immediately result in the construction of any infrastructure.

Future electricity transmission infrastructure development within the corridor will be subject to Environmental Assessment Act requirements and other applicable regulatory approvals, including through the Ontario Energy Board’s Leave to Construct approvals process. The future transmitter would be responsible for conducting the necessary assessments and obtaining the necessary permits and approvals.

Engagement with Indigenous communities on this proposal:
The provincial Crown is committed to fulfilling its duty to consult with Indigenous communities in respect of contemplated 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 has directly contacted potentially affected Indigenous communities at major project milestones, including the launch of the Study and the identification of the Narrowed Area of Interest. The ministry will provide information about the above policy actions and project to potentially impacted Indigenous communities, including information about how they can participate in the consultation process. This would include an opportunity to review and provide comments about this proposal through the Environmental Registry of Ontario (ERO) as well as an opportunity to meet with MEM staff about the proposal.

In addition, the province expects to delegate the procedural aspects of Crown consultation to the transmitter in respect of future transmission lines, which may be fulfilled through environmental approvals and/or other provincial regulatory approvals and/or permits as appropriate.