Claerwen Dam & Reservoir
Claerwen dam and reservoir is the largest in the Elan Valley Estate and the last to be constructed. It is part of Birmingham’s principal water supply. The dam and reservoir was the eventual solution for the second phase of expanding the water supply. They were opened in 1952 by Queen Elizabeth II as one of her first official appearances during her reign.
Key info
| Location | Elan Valley Estate |
| County | Powys |
| Completed | 1952 |
| Chief engineer | Charles Arthur Risbridger |
| Consulting engineers | Sir William Halcrow & Partners |
| Maintained by | Dŵr Cymru Welsh Water |
| Heritage category | Listed Building Grade II |
Visiting guide
Open 24 / 7
Free entry
Free car park
What can I expect when visiting Claerwen dam and reservoir?
Head towards the base of the dam through the left gate.
You will see the outlet channel to left containing a weir permitting the Afon (river) Claerwen to continue its course to the Dol-y-Mynach Reservoir.
Follow the path to the footbridge crossing the outlet channel for a view of the majestic dam. If you visit during the winter, the reservoir is likely to be full; therefore, excess water flows over the dam creating a series of cascading waterfalls. The dam has a face of rough rock to break the fall of water; however, the centre has a stepped face, which provides a delightful variant of flow.
Once you have finished exploring the base of the dam, it’s time to head up to the top. Return along the path you came, head through the gate and turn left. Follow the gravel path up the hill.
As you approach the summit, take time to enjoy the view of the dam and its thirteen elliptical arches. Note the centre arch supporting the viewing platform, our next destination.
At the top of the hill, follow the road across the dam to the viewing platform.
Notice the ceremonial plaque commemorating the date of opening by Queen Elizabeth II.
Head up to the viewing platform for your reward, a panoramic view of the cascading dam overflows and the pristine Claerwen Valley.
Turn around for a view of the Claerwen Reservoir, the largest in the Elan Valley Estate. It was constructed to meet the rising demand for water in Birmingham and concerns about the original supply, which were amplified during a drought in 1937.
Continue along the road till you reach a dead end. There is another viewing platform where you can take in the fresh air and stunning views.
Once you are ready, head back along the road and down the gravel path to the car park.
How long does it take to visit Claerwen dam and reservoir?
It will take you roughly 45 minutes to follow the visiting guide detailed above; therefore, you should extend your visit by exploring more of the Claerwen Valley or the Elan Valley Estate.
Is Claerwen dam and reservoir suitable for a picnic?
Claerwen dam and reservoir is located in the Elan Valley Estate, an area of pristine natural beauty with ample spots for picnics or a simple lunch.
How do I get to Claerwen dam and reservoir?
Claerwen dam and reservoir is accessible on foot. You can reach it from multiple walking routes from the Elan Valley Visitors Centre up the Claerwen Valley. If arriving by car, follow the road after crossing the Garreg-Ddu dam until you reach a car park at the base of the Claerwen Dam.
If you are arriving by public transport, head for Rhayader. The town no longer has a railway station; however, you can catch a train to Llandrindod Wells and then take a 30 min bus journey to Rhayader. There are bus services from Rhayader to the Elan Valley Visitors Centre. Check out Traveline Cymru for travel info. You can always catch a taxi from Rhayader or Llandrindod Wells as an alternative option.
Architecture & dimensions
A masonry-faced concrete dam serves as the foundation for a viaduct supported by 13 elliptical arches, adorned with stone parapets. The central arch of the viaduct is wider and hosts a scenic viewing platform, complete with a protective balustrade. The platform’s end piers seamlessly integrate with the dam, forming a striking visual composition with a stepped spillway.
At the base of the spillway, two buttresses flank doorways, interconnected by bridges set diagonally across a pool nestled at the dam’s foot. Stepped spillways extend from the ends of the dam, gradually broadening as they descend, with parapet walls framing their course. These walls transition to enclose a channel directly in front of the dam’s base, where a stone bridge boasting two segmental arches and iron railings spans the watercourse, providing both function and aesthetic charm.
The total weight of materials used was 700,000 tons including 438,000 tons of gritstone, 173,000 tons of pit sand, 65,000 tons of cement, and 18,000 tons of masonry. The dam forms a reservoir over four miles long.
| Dam height | 184 ft (56.9 m) |
| Dam length | 1,166 ft (355.4 m) |
| Total electricity capacity | 1,680 kW |
| Total reservoir capacity | 10,625 million gallons (48,302 megalitres) |
| Top water area | 650 acres (2.6 km2) |
Sources
- Brown, D. L. (2020) The Elan Valley Clearance. Eardisley: Logaston Press.
- Morton, R. (1997) The Building of the Elan Valley Dams. Walsall: Brian Lowndes Print.
- Coflein (2024) Claerwen Dam, including attached footbridges. Available at: https://cadwpublic-api.azurewebsites.net/reports/listedbuilding/FullReport?lang=&id=16222 (Accessed: 31 March 2024).
Dol-y-Mynach Dam & Reservoir