Dam, valve tower, bridge and outflow on Pontsticill Reservoir

The structure consists of a dam, valve tower, bridge, and outflow located on Pontsticill Reservoir. The long dam features a clay core and earth bund construction, with a pitched stone revetment on the inner face of the embankment and a full-length stone wall above it. The inner face of the sloping earth bank is supported by a low stone wall that carries the roadway above.

The valve tower is constructed of rock-faced coursed stone and topped with a copper-sheet spire. This Gothic-style octagonal tower rises from the water on an octagonal base. The lower masonry is corbelled out on stepped corbels, with pointed arches between them. It has a moulded plinth, and the base steps forward on the west side to form piers for a porch that leads to a square-headed door, which has a renewed gabled timber hood. The other sides of the tower feature narrow lancets with stone voussoirs and hoodmoulds, and the eaves are stepped. The tall octagonal roof has two pitches and is clad in copper sheet, topped with an iron vane.

The bridge extends from the west side of the reservoir to an abutment in front of the door of the valve tower. It is supported by a single stone pier with blockwork above and is of a lattice steel type. The abutment at the land end has walls made of rock-faced stone. Below the bridge, the outflow consists of a convex-sided large funnel in the reservoir, featuring concrete ribs and a lining of brick or stone.