Mayo Relicensing Project

Our current water use licence and Fisheries Act Authorization for the Mayo hydro facility expires on December 31, 2025. To continue to generate electricity, and to continue to provide Yukoners with renewable electricity, we need to renew our water use licence. As part of this, we are looking to put processes in place that will allow us to continuously monitor and adapt to changing climate conditions, respond to community input, and minimize our impact on the environment.

What's in our current water use licence?

Sets out requirements for:

Storage range 

  • The full supply and low supply level of Mayo Lake.

Operating restrictions

  • Minimum and maximum flows downstream of the Mayo Lake Control Structure, Wareham Dam and Mayo A and B plants.
  • Minimum and maximum water levels of Mayo Lake and Wareham Lake.
  • Limits to changing water flows (ramping rates) according to discharge rate.

Dam safety

  • Annual dam safety inspections.
  • Facility and infrastructure maintenance.

Adaptive monitoring and management

  • Our day-to-day work which includes environmental monitoring and responding to our changing climate.
  • Reporting requirements to the Yukon Water Board.

What does a Fisheries Act Authorization do?

Sets out requirements for:

Instream flows and ramping rates

  • Minimum instream flow requirements for Mayo River to optimize fish habitat quality and quantity in all seasons.
  • Rules for the rate of stream flow change to prevent fish stranding.

In-water works

  • Requirements to protect fish and fish habitat when conducting construction and maintenance activities in or near the Mayo River.

Habitat compensation/offsetting

  • Construction, maintenance, and monitoring of compensatory Chinook salmon habitat.

Adaptive management and monitoring

  • Fish and fish habitat monitoring and response activities in the Mayo River.
  • Reporting requirements to DFO.

Project schedule

We recognize the importance of working collaboratively with First Nations governments and are applying lessons learned from other relicensing processes to this project. In 2022, we started discussions with the First Nation of Na-cho Nyäk Dun so as to understand their interests and values in the facility and the relicensing process. We will continue to have these discussions as the project continues.


Studies and Engagement

  • Engagement with the community and key interest groups
  • Studies, including fish passage discussions


Project Proposal & Assessment

  • Engagement
  • Submit Project Proposal to YESAB



  • Water Board and Fisheries Act Authorization processes
  • Water use licence issued
  • Fisheries Act Authorization issued

2025 & onwards

Monitoring and adaptive management

  • Ongoing community engagement
  • Ongoing monitoring and adaptive management plans

Share your feedback

So far, we’ve heard that fish, wildlife, wetlands, flood control, private and commercial land use, heritage resources, the local economy, energy planning, community well-being, trust and relationships are important to Mayo residents in the context of this project. Let us know what you’d like us to consider as we develop our Project Proposal for the Yukon Environmental and Socio-economic Board (YESAB). There are a few ways you can get involved.

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