Repairs to the Wareham spillway

What is the Wareham spillway?

The Wareham dam and spillway make up part of the Mayo Generating Station and were commissioned in 1952. Just upstream of Wareham dam, water enters an underground pipe that goes to the Mayo A and Mayo B generators to make electricity. When there is too much water to use, it flows down the spillway and back into the Mayo River.

What's happening?

We conduct regular dam safety inspections. After one of these inspections, we noticed there was damage to the concrete on the base of the spillway. We made temporary repairs to the structure in 2021 and 2022, but recent inspections have found that additional, permanent repairs are urgently needed.

Why are the repairs urgent?

We need to make temporary repairs now to reduce the risks of additional damage to the spillway this spring (2024) when the flow of water down the spillway increases substantially. There is no risk of additional damage to the spillway this winter. 

What's the plan going forward?

We intend to complete the temporary repairs to the spillway before the end of April 2024. This will allow us to use the spillway while we work on a permanent solution. We are also developing a monitoring plan to detect any damage to the spillway before, during and after the temporary repairs are completed. We will begin permanent repairs to the spillway as soon as possible and will be considering fish-friendly options. We will continue to work with the First Nation of Na-Cho Nyäk Dun and the Village of Mayo throughout the process and as we seek additional authorizations from our regulators. We hope to have a permanent solution in place by 2026.