Caulmert’s planning expertise played a key role in a landmark project at Llyn Celyn Reservoir.
The Dŵr Cymru Welsh Water led scheme provides a significant upgrade to the reservoir, ensuring reliance, sustainability, and protection for communities and the environment within Eryri National Park.
Caulmert was engaged following a statutory Section 10 inspection under the Reservoirs Act 1975, which confirmed that Llyn Celyn was in good condition but, as expected, some recommendations to meet the latest UK guidance were made.
Construction of an auxiliary spillway featuring 4.5-metre-high tipping gates – the first of their kind at this scale in the UK, catchwater channel, and below-ground flow measurement chamber were all part of the development.
The spillway’s design incorporates a culverted structure for two-thirds of its length, minimising visual impact and preserving the natural landscape.
Llyn Celyn’s historical landscape is recognised as a culturally important site that remembers the rural community of Capel Celyn that was displaced to the reservoir. With that in mind, Caulmert’s planning team sensitively led the pre-application consultation process.
Principal planner Jenny Coxon said: “There’s no doubting the importance of this scheme on the communities and the environment around the reservoir.
“From attending public exhibitions in Bala to finding cost-effective solutions for the project, our highly skilled team was able to have a positive impact in conjunction with Dŵr Cymru Welsh Water and lead designers Mott MacDonald Bentley.”
Caulmert’s input was rewarded as the scheme earned national recognition by winning Water Project of the Year at the British Construction & Infrastructure Awards 2025 in October.
Dŵr Cymru Welsh Water project manager Karen Morris said: “Our commitment to safety, innovation, and environmental conservation has delivered a resilient solution that will protect communities and the environment for decades to come.
“We are especially proud of the collaborative working shown by our teams and partners, and grateful for the support of local stakeholders throughout the process.
“The project has showcased partnership working between ourselves in Welsh Water and Natural Resources Wales along with our contractors and numerous stakeholders.
“This has been one of our largest projects that we’ve undertaken in Welsh Water over the past few years combines technical excellence with real social and environmental value.”
