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Greater Toronto Area West Regional Planning

Regional electricity planning is underway in Greater Toronto Area West. There are two sub-regions within this region: Northwest GTA and GTA West Southern sub-region. Subscribe to receive updates on the status of the plan and to learn about opportunities for municipalities, community groups, stakeholders and the general public to provide input.

Current status: An Integrated Regional Resource Plan (IRRP) has been released for the Northwest sub-region. The scoping assessment completed for the Southern sub-region determined that no further regional coordination is required at this time.


The local distribution companies providing service to this area are: Burlington Hydro Inc., Enersource Hydro Mississauga Inc., Halton Hills Hydro Inc., Hydro One Brampton Networks Inc., Hydro One Networks Inc., Milton Hydro Distribution Inc., and Oakville Hydro Electricity Distribution Inc.


Regional Planning Initiative Underway in this Region

Northwest Greater Toronto Area

The objective of the Northwest GTA IRRP is to develop an integrated supply plan for the area to address needs over a 20-year timeframe by recommending actions for the near to medium term (0-10 years), and identifying options for the long term (10-20 years). Potential solutions will focus on conservation, demand response, generation, distribution, and transmission.

Current status: An Integrated Regional Resource Plan (IRRP) has been released for this sub-region.


IRRP Outcome

The plan identifies several pockets in the study area that are currently at risk for not meeting targeted restoration levels during a system event. Two new step-down transmission facilities are recommended in the near term to ensure new customer connections can be accommodated in the Halton Hills and Milton service territories. Over the medium term, a transmission line upgrade is recommended to address emerging capacity needs in the central Brampton area. In the long term, a need was identified to provide additional transformer and transmission line capacity in Northern Brampton/Southern Caledon and Halton Hills to meet forecast demand growth. An opportunity exists to cost effectively supply this long term growth by initiating approvals for the required transmission right of way in the vicinity of the planned GTA West Transportation Corridor.

Additionally, a bulk system study is underway for GTA West to address anticipated overloads on major bulk system assets resulting from changing provincial generation and electrical demand patterns. The coordination of bulk system planning with the Integrated Regional Resource Planning process presents opportunities for potential solutions to meet both the bulk system needs and the local regional needs.


How to get involved

A Local Advisory Committee (LAC) is being established for the NW GTA IRRP in 2016. The role of the LAC is to provide advice and recommendations on the further development of the plan's longer-term options, as well as how to best engage the broader community in this discussion. Read more about regional planning Local Advisory Committees.

Subscribe to receive updates on regional planning initiatives in the NW GTA Region.

See Northwest GTA engagement initiative.


Working Group

A Working Group consisting of the local distribution companies in the region, the local transmitter and the IESO will use the regional planning process to identify and meet local electricity needs. Subscribe to receive updates on the status of the plan and to learn about opportunities for municipalities, community groups, stakeholders and the general public to provide input.

The working group consists of staff from Halton Hills Hydro, Hydro One Brampton, Milton Hydro, Hydro One Networks Inc., and the IESO.


Area overview

The Northwest Greater Toronto Area is defined in geographic terms as roughly the municipalities of Brampton, Milton, Halton Hills, and southern Caledon. The population of this area is over 700,000 and currently has a peak demand of approximately 1,200 MW. At two per cent per year over the past 10 years, historical load growth within this area is amongst the highest in Ontario.

The northern sections of GTA West are the focus of this IRRP due to a combination of high load growth, expanding urban boundaries, limited existing electrical infrastructure, and the requirement for coordination with bulk system plans impacting the sub-region. 

Northwest GTA sub-region map Map of Northwest GTA Region


Historical context

As part of managing load growth over the past decade, several new system investments have been made, including new transmission lines and station and equipment enhancements, and the new Hurontario Switching Station. These measures have successfully enabled the area to meet the demands of the past decade, but continued robust growth is now driving the need for further investigation.


GTA West Southern sub-region

Current status: A scoping assessment has been completed for the GTA West Southern sub-region and determined that no further regional coordination is required at this time.

The Scoping Assessment Outcome Report completed for the GTA West Southern sub-region concludes that with the load restoration needs being addressed through other planning studies, regional coordination through either a Regional Infrastructure Plan (RIP) or an Integrated Regional Resource Plan (IRRP) is not needed at this time.

The Scoping Assessment identified that Erindale TS T1/T2 capacity needs do not require regional coordination. Enersource and Hydro One agree that available transformation capacity exists adjacent to the limiting asset, and options for providing the required relief should be investigated. Any necessary infrastructure investments will be planned directly between Enersource and Hydro One Transmission.

The Scoping Report recommends that load restoration needs along the Richview x Trafalgar corridor and West of Cooksville area be considered within the ongoing bulk system planning study being carried out in the Western portion of the GTA. This bulk system study is considering electricity needs in the municipalities of Oakville, Mississauga, Toronto, Brampton, Milton, Halton Hills and Caledon, and is being coordinated with other electricity planning studies in these areas. The IESO will ensure that relevant regional specific information is incorporated in the analysis.

 GTA West Southern sub-region mapMap of GTA West Southern Subregion