The Claerwen reservoir and dam in Powys, Wales, were the last additions to the Elan Valley Reservoirs system built to provide water for the increasing water demand of the city of Birmingham and the West Midlands. The dam is built mainly of concrete, with the exterior dam face in dressed stone. The dam is a gravity dam built upon solid rock 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. Statistics Height: Length: Building material: primarily concrete Capacity: Some idea of what was involved in the building of the dam is given by the quantities of materials used. Approximately 1 ¼ million bricks, half a million tons of crushed stone, 200,000 tons of sand, 70,000 tons of cement and 18,500 tons of masonry had to be transported to the site, and an electricity generating station with a capacity of 1,500 h.p. was installed to provide power to operate the plant. Stone for concrete was obtained from a quarry about three miles away. Most of the sand was obtained from the Severn Valley, a distance of over 70 miles by road, and the low heat Portland cement used was made at Aberthaw in South Wales, taken to Rhayader Station by train in specially made containers, and carried to the site by a fleet of lorries. About 370 men were employed in building the dam. The contractors, Edmund Nuttall, Sons and Co. (London) Ltd., provided a temporary camp for 200 of them, with bungalows for members of the staff. This was about seven miles away and outside the catchment area. Others were accommodated in Rhayader. Local men were among those who took part in the work,