The dam was officially opened by Queen Elizabeth II in 1952, marking one of her first public duties after her accession.
The structure was designed to be easily expanded in height if additional storage capacity was needed in the future, though this never occurred.
The reservoir submerged the original Afon Claerwen river valley, including several farmsteads.
Construction work was managed by a consortium of contractors known as the Claerwen Constructors.
The dam is gravity-based, meaning it relies on its own weight and concrete mass to resist the pressure of the water.
It is a central feature of the Elan Valley's water management system, which operates via gravity flow to the West Midlands.
Claerwen Dam is a massive concrete gravity dam located in the Elan Valley, completed in 1952 to provide water to Birmingham. At 56 meters high and 355 meters long, it is the largest of the dams in the Elan and Claerwen estate. Its construction required the use of 400,000 tons of concrete. The dam creates a reservoir covering 650 acres when at full capacity. Unlike the earlier masonry dams in the valley, its design reflects post-war utilitarian engineering standards. The surrounding landscape is characterized by rugged, remote moorland and exposed upland terrain.
The viewing point on the western side of the dam crest provides a direct view of the spillway and the reservoir.
Bring windproof and waterproof clothing as the area is highly exposed to changing mountain weather.
Carry a physical map, as mobile signal is unreliable or non-existent in the Claerwen Valley.
The road leading to the dam is narrow and single-track with passing places; drive with caution.
Attempting to drive beyond the designated parking area, as the road surface deteriorates into private track.
Keep dogs on a lead due to grazing livestock; take all litter away as there are no bins.
