Ontario Investing in Two New Transmission Lines and Upgrades to Existing Lines
June 11, 2025
The Ontario government is building two new transmission lines and two major transmission upgrades to ensure the province has the power it needs to meet growing energy demand to build new homes and support economic growth — which represents one of the largest transmission investments in the province’s history. The government’s plan to significantly expand energy infrastructure is an important part of its work to protect Ontario by securing reliable and affordable energy that can power economic growth and reduce Ontario’s reliance on energy providers from outside the province.
“Ontario is growing fast and so is our energy demand,” said Stephen Lecce, Minister of Energy and Mines. “That’s why we’re planning early and advancing approximately 160 km of new and upgraded transmission lines to connect people and businesses to the affordable, secure, reliable and clean energy they’ll need in the years ahead. After announcing the largest nuclear expansion in Ontario history, we are building for the future by advancing one of the largest transmission expansions in Ontario history. This is part of Ontario’s long-term integrated plan for economic self-reliance.”
In the next 25 years electricity demand is expected to increase by 75 per cent, with industrial demand alone set to increase approximately 40 per cent in the next five years. That’s why Ontario is acting now to build the infrastructure today that will deliver power from new electricity sources — including nuclear, hydroelectric, renewables and storage — to the communities and industries that rely on it.
To meet this growing demand, the government is launching consultations on proposals to prioritize three transmission projects. These projects will deliver more power to growing communities — including in the Greater Toronto Area, Windsor-Essex, Central Ontario and Eastern Ontario — helping to connect new small modular reactors (SMRs), boost local manufacturing, support greenhouse operations and improve grid reliability.
Declaring these as priority projects would streamline Ontario Energy Board (OEB) reviews and enable faster approvals and development for the following critical transmission lines:
- A new line from Bowmanville to the Greater Toronto Area (GTA), to connect new generation in Eastern Ontario — including Darlington SMRs 2, 3 and 4 — to Ontario’s grid.
- A new line from Windsor to Lakeshore, to meet fast-growing regional demand in Windsor-Essex and drive continued growth in manufacturing and greenhouse industries.
- An upgrade to existing lines between Orangeville and Barrie, to improve reliability and support economic development in Central Ontario while maintaining system capability for electricity transfer between Ontario’s northern and southern regions.
The province is also announcing its support for upgrades to existing lines between Manby and Riverside Junction in Toronto, to increase capacity and support continued electricity demand growth in Toronto’s west end and downtown core.
“For Ontario’s energy-intensive industries — from greenhouses to auto manufacturing — access to affordable, secure and reliable electricity isn’t optional – it’s essential,” said Sam Oosterhoff, Associate Minister of Energy Intensive Industries. “By advancing these lines, we’re leveraging Ontario’s energy advantage to unleash the full potential of our economy and ensure the energy system can power investment, support increased production and protect jobs.”
The government strongly supports Hydro One’s commitment to creating 50-50 partnerships for Indigenous participation when building new large-scale transmission lines, supporting meaningful economic reconciliation and long-term benefits for participating communities.
This expansion is one of several actions being advanced through Ontario’s first Integrated Energy Plan, which will be released later this month. It reflects the coordinated, long-term approach the province is taking to make Ontario energy secure and create opportunities to export Ontario energy abroad. The government’s record investments in energy infrastructure are also helping protect workers and the economy by supporting economic growth and keeping workers on the job at a time of economic uncertainty.
Quick Facts
- Ontario is home to over 30,000 km of high voltage electricity transmission lines that carry power from generating stations to the communities, industries and homes that rely on it.
- Electricity demand in the Windsor-Essex region is expected to grow at least 500 MW over the next 10 years, from 1100 MW to approximately 1600 MW by 2035.
- Electricity demand in Toronto is expected to roughly double by 2050, driven by population growth, major housing and commercial developments, expanded public transit, and increased electrification of vehicles and buildings.
- The proposals that would be consulted on would be to:
- Issue Orders-in-Council and Minister’s Directives to declare these lines as priority projects with the intent of speeding up their development given Ontario’s electricity demand growth.
- Designate Hydro One to develop the line from Bowmanville to Toronto to provide regulatory clarity necessary for them to kickstart development work and avoid project delays.
- Hydro One was designated by the government in 2022 to begin early development work on the Windsor to Lakeshore transmission line following public and Indigenous consultation. Hydro One will also carry out upgrades on the Orangeville to Barrie and Manby to Riverside corridors, as the transmitter that owns and operates the existing infrastructure in those areas.
- On June 3, 2025, Minister Lecce introduced Protect Ontario by Securing Affordable Energy for Generations Act, which includes a number of other key measures to enhance Ontario’s energy system.
