Mayo Hydro Infrastructure Upgrades

Over the next five years, we are planning to complete a number of upgrades to the Mayo Hydro Facility. This work is critical to maintaining reliable, renewable generation and supporting public safety.

A note that the timelines below can change based on varying factors.

Mayo A Slope and Surge Tank

In 2022, a rockslide occurred behind the Mayo A Hydro Plant, followed by another slide in 2023. Contractors are working to stabilize the slope and replace the surge tank. The surge tank is an important part of the hydro system, as it absorbs sudden pressure changes in the penstock to protect the generating station equipment. 

Planned completion: 2026

Wareham Dam Spillway

The Wareham Dam Spillway is a critical component of the Mayo Hydro Facility. When there is more water than can be used to generate electricity, the excess water flows down the spillway and into the Mayo River. More information about the spillway replacement project is available here.

Planned completion: 2028

Mayo A Hydro Plant Renewal

The Mayo A Hydro Plant is one of two plants that house the turbines and related equipment at the Mayo Hydro Facility. The Mayo A Hydro Plant has been in service since the early 1950s and is nearing its end of life. To continue operating safely into the future, it requires an upgrade. Options for the plant, including the building and its equipment, will be considered.

Planned completion: TBD

Mayo Lake Control Structure

The Mayo Lake Control Structure is located 35 km upstream from Wareham Lake. Currently, the structure is in poor-to-fair condition and needs to be replaced. As part of the replacement, we will include fish passage. 

Design to begin: 2029