Welsh Water has recently completed a project to return Llyn Bran back to a natural lake.
Llyn Brân near Bylchau in Denbighshire was created to supply the old Denbighshire Hospital, but since the hospital’s closure in 1995 it is no longer needed as a water resource. Welsh Water, in conjunction with Natural Resources Wales, decided to remove the artificially raised part of the reservoir to return it to a natural lake. The lake is home to water vole, common lizards and numerous bird and plant species as well as important habitats and deep deposits of peat.
The work took place following numerous ecology surveys and site investigations which have been undertaken since 2018 to ensure the least amount of impact to the site. The reservoir drawdown and decommissioning work was carried out between May and October 2022 and the dam structure was removed. The remaining natural lake now flows as it would have done before the dam was built. It also brings a number of habitat enhancements to the area including uncovering a large area of previously submerged peatland as well as the relocation of rare aquatic plants from Llyn Anafon on the Carneddau Mountains. The work also helps to improve fish migration and preserve the habitat for water vole as well as significant shoreline restoration works.
Welsh Water’s Head of Dam Safety Andrew Bowen said: “Llyn Brân had supplied fresh clean water to the North Wales Hospital in Denbigh for many years until it closed therefore it is no longer needed as part of our water resource plan. As a company committed to protecting the environment, the best solution is to restore it to its natural state before the dam was built in 1896.
“This restoration of Llyn Brân presented us with a significant opportunity to improve biodiversity in the area by reinstating the natural river corridor and relocating rare aquatic plants from Llyn Anafon.”
The natural lake is smaller in size than the previous reservoir and as part of the project the banks have been partially revegetated to support re-growth. Now that the water levels have been lowered, the site may initially look quite muddy. However, after a growing season, the coir seeded matting will start to grow and re-cover this area. Llyn Brân will eventually become a Special Area of Conservation. Welsh water will continue to monitor and manage the ecology of the site for several years to ensure that the site recovers to its natural state and supports the unique ecology of the site.
Andrew Bowen added: “We have worked hard during this project to safeguard the environment. The water voles in Llyn Brân were removed whilst the work was carried out and they will be returned to their natural habitat next spring in time for the breeding season. Welsh Water will also continue to monitor water quality levels at the lake monthly.”