Craig Goch Dam is topmost of a series of dams in the Elan Valley, built by the City of Birmingham from 1893 to 1904 to supply Birmingham with drinking water. The scheme involved the construction of 4 dams, an aqueduct 126 km long, and a village for construction workers. The height of the reservoirs enabled water to reach the outskirts of Birmingham by gravity alone, without the expense of pumping. Construction on the Craig Goch dam began in July 1897, the engineer was James Mansergh. Built of curved masonry, it has massive heavily rock-faced blocks. There are spillways with parapet walls to the ends, surfaced with hard grey stone. The dam supports a viaduct on 13 segmental arches carrying a roadway over the dam. Abutments to the viaduct have doorways to the interior of the dam. There is an attached polygonal valve tower, a copper dome with a lantern and fish weathervane and waterspouts to the parapet. The interior is said to contain original operating machinery.
A bronze plaque from dam (removed to visitor centre) reads:
" Craig Coch Reservoir
Total Capacity 2,000,000,000 gallons
Top Water Area 217 Acres
Top Water Level 1,040 feet above Ordnance Datum
Height of Dam above River Bed 120 ft
Depth of Foundations below River Bed 10 ft
Length of Weir 390 ft
Thickness of Dam at Base 104 ft
Estimated quantity of masonry 80,000 cubic yards"
Reference: Cadw listed buildings database.
Elan Valley Water Scheme (nprn 96459)
Craig Goch Reservoir (nprn 309536).