Northumbrian Water and its partner Esh-Stantec have carried out the work at Burnhope Reservoir, in Weardale.
The reservoir, in Wearhead, supplies water to the neighbouring Wear Valley Water Treatment Works. It also feeds the River Wear, helping to regulate its levels downstream.
The project started in the summer of 2022 and has been carried out in two stages.
Work included drainage refurbishment on the external dam face, maintenance to the overflow near the valve tower, and modifications to the outlet tunnel feeding the treatment works.
A break was factored into the project due to difficult wet ground conditions and to protect ground nesting birds on the working area. This also removed the need to artificially lower water levels, via controlled reservoir releases, in the early part of the year. This has allowed for the preservation of raw water resources.
Mike Ciaraldi, Northumbrian Water’s Project Manager said: “This has been an important investment in the resilience of Burnhope Reservoir, a key asset in our water supply network.
“As our most westerly reservoir in Weardale, it has a vital role to play in water supply right down through the dale, the wider Wear Valley and beyond. It’s also instrumental in protecting the river levels in the Wear, supporting people, wildlife, and industry.”