Updating environmental assessment requirements for transmission lines

ERO number
Notice type
Environmental Assessment Act, R.S.O. 1990
Posted by
Ministry of the Environment, Conservation and Parks
Notice stage
Proposal Updated
Proposal posted
Comment period
July 5, 2021 - September 3, 2021 (60 days) Closed
Last updated

Update Announcement

We updated the notice to include a link to separate proposal from the Ministry of Energy, Northern Development and Mines referenced in the notice. No other changes have been made to the notice or commenting period.

July 16, 2021

This consultation was open from:

July 5, 2021
to September 3, 2021

Proposal summary

We are proposing to update the thresholds that determine the type of environmental assessment process required for establishing a transmission line.

Proposal details

Ontario is updating the almost 50-year-old Environmental Assessment (EA) program to support building safer and stronger communities, while maintaining environmental protection. As part of our modernization efforts, we are proposing changes to the environmental assessment requirements for certain transmission line projects, under the Environmental Assessment Act.

These proposed changes, if approved, will update the EA requirements for critical transmission infrastructure, while ensuring strong environmental protections are in place. These changes will support expanded access to lower carbon energy sources from Ontario’s electricity grid, promote regional economic development and shorten-times for building critical infrastructure projects across the province. The proposal will also benefit First Nations Communities by streamlining the process for off-grid communities in the Far North to connect to the transmission network.


On July 21, 2020, the COVID-19 Economic Recovery Act, 2020 was passed and included amendments to the Environmental Assessment Act (EAA) and related consequential amendments. The notice can be found at: https://ero.ontario.ca/notice/019-2051

These amendments enabled the next steps in modernizing Ontario’s environmental assessment program, helping to:

  • ensure strong environmental oversight
  • facilitate Ontario’s economic recovery

On September 11, 2020, the ministry posted a proposed list of projects which would be subject to the comprehensive environmental assessment requirements in Part II.3 of the EAA. The notice can be found at: https://ero.ontario.ca/notice/019-2377

Through this consultation we:

  • proposed maintaining existing thresholds for electricity projects that require a comprehensive environmental assessment
  • requested input on whether changes should be made

Proposed changes to thresholds

We are proposing to change the provincial voltage and distance thresholds for transmission lines that require an individual environmental assessment. The proposed changes would align with the thresholds in the federal regulation under the federal Impact Assessment Act that designates international electrical transmission lines, namely 75 kilometres (km) or longer and a voltage of 345 kilovolts (kV) or greater.

We are proposing that establishing transmission lines:

  • 75 km or more in length and 345 kV or greater in voltage would be required to complete an individual environmental assessment.
  • more than 2 km in length and with a nominal voltage of 115 kV or more, but which do not meet the criteria for an individual environmental assessment, would follow the Class Environmental Assessment for Minor Transmission Facilities (Class EA), as amended from time to time.

This proposal relates only to establishing transmission lines that are not associated with generation facilities that are subject to the Environmental Screening Process under O. Reg. 116/01 (Electricity Projects).

Currently, as outlined in the table below, an individual environmental assessment is required to establish a transmission line that is:

  • greater than 115 kV and less than 500 kV and greater than or equal to 50 km in length
  • greater than or equal to 500 kV and greater than 2 km in length

and not associated with a generation facility that the Environmental Screening Process applies to under O. Reg. 116/01.

The Class EA applies to the establishing of a transmission line that is below these thresholds and not associated with a generation facility that the Environmental Screening Process applies to under O. Reg 116/01. Note that establishing a transmission line that is 2 km or less in length or that is designed to operate at a nominal voltage of less than 115 kV is not subject to the EA Act.

These requirements are explained in the:

If these proposed changes to the thresholds are approved, the Class EA for Minor Transmission Facilities would apply to establishing transmission line projects that:

  • have a voltage greater than or equal to 115 kilovolts but less than 345 kilovolts, greater than 2 kilometres in length;
  • have a voltage greater than or equal to 345 kilovolts and less than 75 kilometres in length.

The current and proposed changes to environmental assessment requirements for establishing transmission lines are shown in the following table.

Table: Proposed changes to Environmental Assessment Requirements for Transmission Lines1
Voltage in kilovolts (kV) / Length in kilometres (km) 2 < km < 50 50 km < 75 75 km
=115 kV Class EA Class EA Class EA
115 < kV < 345 Class EA Class EA (change from Individual EA) Class EA (change from Individual EA)
345 kV < 500 Class EA Class EA (change from Individual EA) Individual EA
500 kV Class EA (change from Individual EA) Class EA (change from Individual EA) Individual EA

1. Transmission lines 2 km or less in length or less than 115 kV are not subject to the Act

We are not proposing changes to requirements for projects associated with a generation facility that the Environmental Screening Process applies to under O. Reg. 116/01 (Category B generation projects). For more information on these types of projects please see the Guide to Environmental Assessment Requirements for Electricity Projects..

The changes to these thresholds in the Class EA are proposed to be made by regulation under the Environmental Assessment Act. The regulation making authority in 15.1.4 would be proclaimed if the decision is to proceed with the regulation. No changes to the designations and exemptions in O. Reg. 116/01 will be necessary to implement this change.

The Class EA for Minor Transmission Facilities

The Class EA for Minor Transmission Facilities is a type of streamlined environmental assessment process that is used for projects with predictable and manageable environmental effects, that can be planned and constructed in accordance with a common process that:

  • includes requirements for consultation, including consultation with Indigenous communities
  • requires the consideration of potential environmental impacts and mitigation of any such impacts, before a project proceeds

We are proposing that the additional projects, identified in the table above, would be subject to the process outlined in the Class EA for Minor Transmission Facilities, which requires an electricity transmission proponent to:

  • establish the need for the project
  • consider alternatives to the project and alternative methods for the project
  • conduct an environmental inventory/analysis
  • document the studies and process in an environmental study report
  • consult with Indigenous communities, the public, and government agencies
  • develop a monitoring strategy for the project

Section 3.3 of the Class EA describes a screening process that can be used by transmission project proponents to screen out proposed projects that are determined to have very low potential for environmental effects. Upon successful completion of this process, the project would be exempt from the Act. This screening process is generally used for minor projects, such as constructing short transmission lines (i.e. between 2 and 4 kilometres in length). As such, the ministry is proposing that these additional project types (outlined in the table above) would not be eligible to use the screening process in the Class EA.

2020 proposed amendments to the Class EA for Minor Transmission Facilities

In July 2020, the ministry began consulting on amendments to the Class EA for Minor Transmission Facilities. More information on the proposed amendments can be found on our website at: https://www.ontario.ca/page/class-ea-minor-transmission-facilities

The ministry continues to consult with Indigenous communities on those proposed amendments and is proposing to proceed with this proposal separately from the July 2020 amendments. If the amendments proposed in July 2020 are approved, and may impact this proposal, the ministry will provide further information, including potential updates to this posting or direct notification.

Please note that there is a separate posting by the Ministry of Energy related to Ontario Energy Board leave to construct approval for certain transmission projects. Refer to https://ero.ontario.ca/notice/019-4009 for additional information.

Transition provisions

If the proposed changes are made, there may be projects that could be affected by the updated thresholds and so transition provisions will be included.

We are proposing that the Waasigan Transmission Line project by Hydro One, which has commenced an individual environmental assessment approval (terms of reference for this project has already been submitted to the ministry) be required to continue. The ministry is not aware of any other projects that have submitted a Terms of Reference for which transition provisions would be required. However, any other project for which a Terms of Reference has been submitted as of the date the regulation takes effect is also proposed to be required to continue with the individual environmental assessment process.

Comprehensive EA project list proposal

As noted above, the ministry consulted in fall 2020 on the list of projects proposed to be subject to a comprehensive environmental assessment. While the ministry is proposing to proceed with this change to the Class EA in respect of the specific thresholds for transmission lines, we will consult in the future on the draft regulation setting out the proposed projects that would be subject to a comprehensive environmental assessment and a summary of related Class EA amendments. This current proposal is intended to advance the regulatory work and decision making as it relates to transmission lines.

Regulatory impact statement

There are no direct compliance costs or new administrative burdens associated with the proposed regulation. Cost savings to proponents are anticipated as a result of following the Class EA process to address the requirements of the Environmental Assessment Act compared to completing an individual EA.


Commenting is now closed.

The comment period was from July 5, 2021
to September 3, 2021

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