> The Ontario Line - Environment | Metrolinx Engage


The Ontario Line - Environment

By its nature, providing reliable, safe and accessible public transportation brings environmental and social benefits. Metrolinx is committed to the preservation and protection of the environment, while working to provide an integrated and sustainable transportation system. To maintain strong environmental oversight, Metrolinx is conducting a thorough environmental assessment – including studying existing environmental conditions and completing an environmental impact assessment. The below graphic shows the different environmental conditions that have been studied throughout the Ontario Line study area and the different reports that we will use to share those findings.


Metrolinx is completing an environmental assessment (EA) in accordance with Ontario Regulation 341/20: Ontario Line Project (O. Reg. 341/20) made under the Environmental Assessment Act. This regulation was available for public review from February 18, 2020 to March 19, 2020 on the Environmental Registry of Ontario and came into force on June 30, 2020.

The regulation outlines a Project-specific EA process that includes:

  • Public, regulatory agency and Indigenous community notification and consultation
  • An Environmental Conditions Report and an Environmental Impact Assessment Report
  • An opportunity for Early Works Reports for assessment of works that are ready to proceed in advance of Environmental Impact Assessment
  • Report completion
  • Metrolinx addressing concerns through an issues resolution process

In keeping with the process outlined in O. Reg. 341/20, Metrolinx is advancing Environmental Conditions, Early Works and Environmental Impact Assessment Reports.

The Environmental Conditions Report (ECR) characterizes environmental conditions within the Ontario Line study area through a combination of desktop review and field studies in accordance with industry standard techniques, protocols and guidelines.

In accordance with O. Reg. 341/20, the ECR provides the following on the Ontario Line Project:

  • A statement of the purpose and a summary of background information
  • A description of the Project
  • A map showing the area studied
  • A description of the local environmental conditions in the area studied
  • A description of all studies undertaken
  • A preliminary description of the potential impacts that the Project might have on the environment that have been identified to date and an indication of how those impacts will be studied and described in further detail in the Environmental Impact Assessment Report
  • A description of any potential measures for mitigating any negative impacts that the Project might have on the environment
  • A description of the future studies that will be carried out as part of the Environmental Impact Assessment Report to determine potential impacts to the environment caused by the Project and the potential measures for mitigating any negative impacts in respect of them
  • A preliminary list of the potential municipal, provincial, federal or other approvals or permits that may be required for the Project
  • A consultation record

Public feedback received on the Draft Environmental Conditions Report has been incorporated into the final version of the report. If you have questions about the report or about the environmental assessment process for the Ontario Line, please contact us.

As project planning and design advance, Metrolinx will complete and publish Early Works Report(s) and an Environmental Impact Assessment Report. Potential impacts and mitigation measures identified in the ECR will be confirmed and refined within Early Works Report(s) and the Environmental Impact Assessment Report.

Study Area

A broad study area was chosen to support flexibility in design. The Environmental Conditions Report summarizes potential impacts and potential mitigation measures for consideration during project planning and design.

map graphic showing the study area for the Ontario Line Environmental Reports

The Ontario Line study area has been divided into three segments:

  • Ontario Line West
    (OLW - from approximately Dufferin Street to University Avenue)
  • Ontario Line South
    (OLS - from University Avenue to Danforth Avenue)
  • Ontario Line North
    (OLN - from Danforth Avenue to approximately Eglinton Avenue East)

As detailed design advances, potential impacts and mitigation measures will be confirmed. These details as well as supporting studies will be included in the Early Works Reports and/or Environmental Impact Assessment Report.

View the Full Report

View the Environmental Conditions Report studies:

Early works are components of the Ontario Line Project that are anticipated to be ready to proceed before completion of the Environmental Impact Assessment Report, such as station construction, rail corridor expansion, utility relocation or bridge replacement or expansion, as defined in O. Reg. 341/20.

Early Works Reports will provide a description of the early works and alternatives considered, document local environmental conditions, and outline early works-specific environmental impacts, mitigation measures, monitoring activities, potentially required permits and approvals and other components.

Ontario Line early works are being advanced where the Project interfaces with other concurrently planned transit projects (i.e., GO Expansion) and where portions of the alignment run in parallel to the existing Lakeshore East and Lakeshore West GO rail corridors.

Advancing work in these areas will facilitate timely implementation of the Ontario Line Project and provides planning, design and implementation efficiencies for ongoing projects such as GO Expansion.

At this time, the following Ontario Line early works are being planned:

  • Exhibition Station – an extension to the existing passenger tunnel; a temporary pedestrian bridge; a new north platform and accompanying shift of the northern two GO tracks; and, utility relocation and protection. Learn more.
  • Corktown station – early works planned at the station serving Corktown (and future launch shaft site) are integral to the project’s construction schedule. These early works include removal of existing buildings, other structures and asphalt, decommissioning of utilities, and soil removal and/or remediation where required. These activities will enable the completion of environmental due diligence investigations, including archaeological assessments at the First Parliament site, that are required in advance of site preparation for future construction staging and laydown, future tunnel and below ground construction activities, and other work associated with the future Corktown Station. Learn more.
  • Lower Don Bridges – building a new bridge north of the existing rail bridge over the Lower Don River that will carry the Ontario Line tracks. Learn more.
  • Don Yard – shifting GO tracks in the Don Yard and nearby rail corridor west of the bridge to accommodate Ontario Line infrastructure; modifying the existing rail bridge to accommodate future GO track shifts and Ontario Line infrastructure; and relocating and protecting utilities and signal infrastructure in the area. Learn more.
  • Lakeshore East Joint Corridor – includes rearranging tracks in the corridor between Eastern Avenue and Pape Avenue to accommodate four GO rail tracks and two Ontario Line tracks, including: grading; installation or upgrading of vegetated slopes or retaining walls and noise barriers next to the corridor, where appropriate; relocation or protection of utilities; new bridges at Dundas and Logan to support future Ontario Line tracks; and replacement of the existing Lakeshore East rail corridor bridges at Queen, Dundas and Logan. Learn more.
  • East Harbour Station – includes the construction of the East Harbour Transit Hub and replacement and expansion of the Eastern Avenue rail bridge. This will be an important transfer point, serving GO and Ontario Line, and providing protection for a planned extension of the Broadview streetcar. The East Harbour Transit Hub will be located in a corner of the city that is poised for growth and will be a vital connection for customers transferring between the Ontario Line and GO train services, connecting with local transit via Broadview, and ultimately helping to reduce crowding at Union Station. With a proposed shared concourse providing easy access to all the rail and local transit that will serve East Harbour, more customers will be able to transfer from the GO train to the subway and local network and travel to more places. The expanded Eastern Avenue bridge will accommodate both GO and Ontario Line tracks. Learn more.

Exhibition Station, Lower Don Bridges, Don Yard and Lakeshore East Joint Corridor early works are being advanced where Ontario Line work will take place alongside other important transit expansion projects and where portions of the alignment run in parallel to the existing Lakeshore East and Lakeshore West GO rail corridors.

Learn more about the early works environmental assessment timeline under the process section, above.

map of Ontario Line early works


Following finalization of the Environmental Conditions and Early Works Reports, an Environmental Impact Assessment Report was completed and is now available online. This report includes a final description of the Ontario Line Project, environmental impact evaluation results, mitigation measures, monitoring activities, potentially required permits and approvals and other components as outlined in O. Reg. 341/20.

The Minister of the Environment, Conservation and Parks provided a decision for the final Environmental Impact Assessment Report in April 2022. The final Environmental Impact Assessment Report and the Statement of Completion are available online here.