Craig Coch Dam & Valve Tower

Craig Coch Dam and Valve Tower is a significant structure designed to supply water to the outskirts of Birmingham by gravity, eliminating the need for pumping. The dam was enhanced by the Claerwen dam in 1952, allowing for future expansion in the Claerwen Valley.

A bronze plaque removed to the visitor centre provides key details about the reservoir: it has a total capacity of 2,000,000,000 gallons, a top water area of 217 acres, and a top water level of 1,040 feet above Ordnance Datum. The dam rises 120 feet above the river bed, with foundations extending 10 feet below it. The length of the weir is 390 feet, and the thickness of the dam at its base is 104 feet, comprising an estimated 80,000 cubic yards of masonry.

The dam features a curved design made of massive, heavily rock-faced blocks. At both ends, there are spillways with parapet walls that widen as they descend, finished with hard grey stone. The walls of the spillways turn to run parallel with the river. On the east side, there is an outlet that was partly submerged at the time of inspection.

Supporting the dam is a viaduct with 13 arches that carries a roadway over it. The viaduct showcases a contrast between rock-faced and smoother stone. Its piers support segmental arches with keystones, and there is a bandcourse at road level along with a parapet featuring coping and heavy rock-faced capstones. Each end of the viaduct has three arches, and there is a polygonal refuge that is corbelled out. The abutments of the viaduct include doorways leading into the interior of the dam. Attached to the eastern refuge is a polygonal valve tower topped with a copper dome, lantern, and fish weathervane. The tower has waterspouts to the parapet and paired windows on each face that are set back from the buttresses. This upper stage of the tower is corbelled out over a narrower stage, which features barred intakes that extend below the water level.

The interior of the dam is reported to contain the original operating machinery.