Mayo Generating Station Technical Consultant

The Mayo Generating Station (MGS) is a key piece of electricity generation infrastructure in the Yukon. MGS has an installed capacity of 15 MW and a dependable winter capacity of 6.5 MW, reflecting restricted water outflows. MGS facilities include water control structures at Daghro Män/Ts’agro Män/Mayo Lake and Wareham Lake, a concrete spillway, intake structure, tunnel/penstock, surge facilities and two generating stations. MGS infrastructure is located within the territories of the First Nation of Na-Cho Nyäk Dun. The infrastructure regulates water / tu flows of the Tadze Nyäk/Mayo River and water elevations on Daghro Män/Ts’agro Män/Mayo Lake and Wareham Lake. Water in the Tadze Nyäk/Mayo River, which is used to generate hydroelectricity at the MGS, flows from Daghro Män/Ts’agro Män/Mayo Lake, before flowing into the Na-Cho Nyäk gé/Stewart River just southwest of the Village of Mayo. Daghro Män/Ts’agro Män/Mayo Lake itself is fed by numerous creeks and tributaries, the largest of which are Roop and Nelson creeks, which flow into each respective arm (i.e., Roop and Nelson arms). Roop Creek has a large wetland area (Roop Lakes Wetland) just to the north of Roop Arm. Edwards Creek, another major tributary, flows into Roop Creek immediately upstream of Daghro Män/Ts’agro Män/Mayo Lake. Other smaller tributaries include Anderson, Granite (tributary to Roop Creek), Ledge, Cascade, Ping Pong, Steep and Owl creeks. These tributaries lie within the Territories of FNNND. Operation of the MGS has been ongoing since 1951. For additional details, the location, and overview of MGS, are provided in the RFP as Appendix 7. Water Use Licence HY25-027, issued to YEC by the Yukon Water Board (YWB) February 27, 2026 and expires December 31, 2030. The existing FAA expires December 31, 2026 (Appendix 12). An application for a Fisheries and Oceans Canada (DFO) Fisheries Act Authorization (FAA) for the MGS is under development and is expected to be submitted in 2026.