|Basin countries||United Kingdom|
|Surface area||3.688 km2 (1.424 sq mi)|
The Claerwen reservoir and dam in Powys, Wales, were the last additions to the Elan Valley Reservoirs system built to provide water for the increasingly demanding city of Birmingham, in neighbouring England. Built mainly of concrete, the exterior of the dam face is dressed stone. The dam is a gravity dam. This type of dam needs to be built upon solid foundations as the pressure of the reservoir behind should be in equilibrium with the total weight of the dam itself thus causing complete stability.
The Claerwen dam was finished in 1952 and was given a late Victorian effect so that it blended in with the earlier dams in the valley. It was necessary to employ the services of Italian stonemasons as British ones were still at work in London during the post-war rebuilding process of the late 1940s.
The dam took six years to complete and was almost twice the size of the other dams in the Elan valley. The Claerwen reservoir is almost the size of all the other reservoirs in the Elan Valley system combined. Officially commissioned by Queen Elizabeth II in 1952, it was one of her first royal engagements as monarch.
- Height: 56 m (184 ft)
- Length: 355 m (1,165 ft)
- Building material: primarily concrete
- Capacity: 48,300,300 m3 (1.06246×1010 imp gal)
Claerwen National Nature Reserve is a lonely expanse of mountain upland lying halfway between Rhayader and Pontrhydfendigaid in Powys. Although its landscape can seem bleak and inhospitable[weasel words], the mainly peaty and acidic soil provides a home for numerous species of plants and animals which thrive in these conditions. One of the three British species of carnivorous sundew plants or Drosera can be found here, and it is a known breeding site for the rare merlin and red kite birds.
In popular culture
In 2015 the dam was featured in the fourth episode of Series Twenty-two of the BBC motoring programme Top Gear. During the episode Richard Hammond winched a Land Rover Series up to the top of the dam, and down again, in mimicry of an advert once used for the vehicle, during a tribute segment for the Land Rover Defender.