Electricity Planning for GTA West

Electricity demand in the cities and towns that make up GTA West continue to outpace most others in the province. As a result of the IESO’s most recent plan for the area, transmission upgrades are underway to strengthen the delivery of supply to the region. Now, more planning is needed.

With economic growth, electrification and local energy plans, the IESO is taking steps to address future needs – and determine a pathway to that would enable reducing reliance on natural gas generation in the area.

In GTA West, electricity demand could double by 2044

Current Status

Scoping the needs: 2025

Developing Solutions: 2026

Making Recommendations: 2026

Comprising the communities of Peel and Halton regions, the population of GTA West is mostly served by transmission infrastructure bringing in supply from the rest of the province, with local supply produced by two natural gas generating stations. Both plants are crucial to meeting local and provincial reliability during peak demand or transmission outages.

Map showcases potential transmision corridor proposed for Highway 413

The pace of demand growth in GTA West could require major investments in large-scale transmission infrastructure. With input from stakeholders and Indigenous communities, the IESO has launched a planning process that will determine which options will best meet these growing needs and upgrade aging infrastructure.

This process will include an evaluation of a scenario for a future without the Goreway and Halton Hills generation stations, determining what would be needed to meet increasing demand without the support of these two power plants. It also coincides with a joint study by the IESO and the Ontario Ministry of Energy and Mines to identify land to be protected for a future transmission corridor that would be adjacent to Highway 413.

The IESO is working with the local distribution companies serving GTA West - Alectra, Burlington Hydro, Milton Hydro, Oakville Hydro, Halton Hills and Hydro One Networks - to understand the full needs of the area and what solutions are best suited to address them.

Phase 1 - Understand Future Needs (2025)

The IESO is currently assessing GTA West's electricity needs over the long term. Demand forecasts for the area have been developed, showing that electricity use could double by 2044. Once the demand forecast is finalized, the IESO will carry out technical studies to fully understand the area’s electricity needs.

Early indications show that in the near and medium term, a number of transformer stations – which deliver power from the high voltage grid to local distribution networks - will reach capacity. Similarly, economic development is driving the need to expand transmission lines to deliver power to support new industrial facilities. Resolving these needs will require the development of additional transmission capacity, as well as other integrated energy options.

And finally, this assessment, as well as a broader analysis of the grid throughout south and central Ontario, is looking at the impact of reducing reliance on the Goreway and Halton Hills generating stations given their important role in maintaining reliability throughout Southern Ontario.

Phase 2 - Develop Solutions (2025-2026)

Once GTA West’s electricity needs are understood, we can take the next step, developing potential solutions to address those needs. Solutions are evaluated based on factors such as cost-effectiveness and reliability. These solutions could be transmission line expansions and upgrades or alternatives to transmission lines – for example, local generation, storage and energy-efficiency programs.

The IESO is also participating in a study by the Ministry of Energy and Electrification into protecting a future transmission corridor to be co-located along the proposed Highway 413.

Phase 3 - Make Recommendations (2026)

The IESO will publish a final report identifying specific priorities and actions. From there, implementation planning would begin for infrastructure projects and program development.

You can stay informed about the progress of this planning effort and participate in discussions on the IESO website, which offers detailed planning documents, videos of webinar sessions, and other information, including:

Presentation (June 2) on electricity demand forecasts for GTA West and how it impacts future system needs.
GTA West Regional Planning: detailed information and updates about the IESO’s planning process GTA West. Here you can subscribe for updates and learn more about the IESO’s webinars and feedback process.

Learn more

If you live or work in the GTA, the IESO offers more information about the region’s electricity needs. Learn more about the IESO’s planning process.