Northwest Ontario

Greenstone Transmission Line

Once built, the Greenstone Transmission Line will provide additional capacity in the region and improve reliability in northern Ontario.

Current project phase: Class Environmental Assessment (EA) ongoing

Expected completion date: 2032

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Current open houses

Thunder Bay

Monday, June 15

2 to 7 p.m.

Oliver Road Community Centre, 563 Oliver Road

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Geraldton

Tuesday, June 16

2 to 7 p.m.

Thunderbird Friendship Centre, 301 Beamish Avenue West

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Beardmore

Wednesday, June 17

2 to 7 p.m.

Beardmore Community Centre, 100 Main Street

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Nakina

Wednesday, June 17

2 to 7 p.m.

Nakina Community Centre, 206 North Avenue

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Nipigon

Thursday, June 18

2 to 7 p.m.

Nipigon Community Centre, 138 Wadsworth Drive

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Building a stronger grid for Ontario's future

Project overview

Ontario's long-term demand for electricity is increasing. To meet this growing demand, the Independent Electricity System Operator (IESO) has identified the need for the Greenstone Transmission Line.

The Greenstone Transmission Line is the result of years of collaboration with Hydro One, First Nations and the provincial government. As the partner of choice to the First Nations who advocated for the line, we will continue to develop the project in partnership to drive local priorities forward. This includes collaborating with Waaskoneh Yaabik, a consortium of seven First Nations to initiate a Class Environmental Assessment (EA) for the construction of a single-circuit, 230-kilovolt (kV) transmission line that will connect to existing infrastructure near Nipigon Bay and extend north to Aroland First Nation.

The project will be designed to accommodate a second circuit in the future and also includes the establishment of two future switching stations, located near Nipigon Bay and Aroland First Nation, as well as a future transformer station near Geraldton. The Greenstone Transmission Line is expected to be in service by 2032.

The proposed project will provide additional capacity to the area and improve reliability for northern communities.

Partnership with purpose

Building as partners

Through Hydro One's industry-leading First Nation Equity Partnership Model, seven First Nation partners will have the opportunity to invest in a 50 per cent equity ownership stake in the transmission line component of this project.

Together, we will build a more self-reliant and secure electricity system to power growth in northern Ontario.

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See the project map

Project map

As part of the Class EA process, the proposed route and route alternatives have been identified through a review of Indigenous culture and values, technical, socioeconomic and natural environment impacts, and consider opportunities to parallel existing linear infrastructure. The proposed route and route alternatives will be studied and evaluated to eventually select a preferred route for the new line.

Your feedback is important. We encourage you to view our interactive map and share your input.

View interactive map Download map (PDF)
Project map

See what's coming

Anticipated project schedule

Winter 2026
Project announcement
June 2026
Notice of Commencement and community open house 1
Summer 2026
Environmental field surveys, research and consultation to support route evaluation and environmental assessment
Spring 2027
Preferred route announcement and community open house 2
Summer 2027
Draft Environmental Study Report (ESR) available for a 30-day public comment period
Fall 2027
Final ESR filed to complete the Class EA
2028
Complete detailed design and obtain permits and approvals including Leave to Construct (Section 92) from the Ontario Energy Board
2029
Proposed construction start
2032
Planned in-service date
*Dates are subject to change.

Guided by standards

Planning process

The project will follow the Class Environmental Assessment for Transmission Facilities, 2024 in accordance with the Ontario Environmental Assessment Act. This is an important part of the planning process to assess potential natural, economic, social and cultural effects, determine measures to avoid or minimize impacts and evaluate route options.

In addition to the Class EA, the project will require Ontario Energy Board approval under Section 92 (Leave to Construct) of the Ontario Energy Board Act, 1998.

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What we shared

Public consultation documents

Project notices

June 2026

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What these documents mean

These documents summarize the studies, project notices and resources shared during the consultation process. They explain how decisions were made and how we engaged with communities.

Answers at a glance

Frequently asked questions

What is the need for this new transmission line?

The Greenstone Transmission Line is the result of years of collaboration with Hydro One, First Nations and the provincial government. As the partner of choice to the First Nations who advocated for the line, we will continue to develop the project in partnership to drive local priorities forward

As part of plans to address future growth in northern Ontario, the IESO has identified the need for added capacity in the region. Once built, this line will reinforce the transmission system in the northwest while supporting the growing electricity demands of industries, businesses and residents.

In addition to meeting growing electricity needs, this new line will improve the overall resiliency of the northern Ontario transmission network.

How will the project benefit the community?

As an Ontario-based company, Hydro One is investing today to ensure northwest Ontario has the electricity it needs now and in the future. Once built, the proposed Greenstone Transmission Line will increase the amount of power that can be delivered to communities to improve reliability to support local priorities and industry. Every investment in Ontario's electricity system is an investment in local jobs and businesses.

How will my feedback be used?

Over the course of the Environmental Assessment, Hydro One will seek feedback from government agencies, municipalities and elected officials, residents, Indigenous communities and interest groups.

Your feedback is important to help us gather information that will help inform the route evaluation and identification, as well as identify any potential mitigation measures necessary. Continuous consultation and engagement also offer opportunities to identify and address potential concerns and issues throughout the planning process to help us ensure the final project is considerate of local interests.

To share your feedback, contact the Hydro One team at: Community.Relations@HydroOne.com or 1-877-345-6799.

The proposed route and alternative routes considered for the new transmission line were identified by mapping known technical and environmental features, as well as input from Indigenous communities. These represent the viable options that we are focused on studying to identify a preferred route.

What is Hydro One's industry-leading First Nation Equity Partnership Model?

Through Hydro One's First Nation Equity Partnership Model, proximate First Nations will have the opportunity to invest in a 50 per cent equity stake in the transmission line component of the project. Together, Hydro One and the proximate First Nations will continue to collaborate on the planning, development and construction of the line.

Contact us

We're here to help

To provide comments or to be added to the project contact list, please connect with us.

1-877-345-6799

Land acknowledgement

Hydro One acknowledges that the Greenstone Transmission Line traverses the traditional territories and treaty lands, Treaty of First Nations signatory to both Treaty 9 and the 1850 Robinson-Superior Treaty which is now home to many diverse First Nations and Métis people. Hydro One understands that Indigenous Nations have been here since time immemorial and are stewards of what many refer to as Turtle Island.

We are all Treaty People and with a commitment to friendship and our pursuit of reconciliation, we are thankful to be welcomed on these lands as partners so we can improve on our past and energize our combined futures.

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