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Dam at the Upper Neuadd Reservoir

A Grade II* Listed Building in Llanfrynach, Powys

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Latitude: 51.859 / 51°51'32"N

Longitude: -3.4112 / 3°24'40"W

OS Eastings: 302915

OS Northings: 218769

OS Grid: SO029187

Mapcode National: GBR YN.T2HP

Mapcode Global: VH6CB.TJJQ

Entry Name: Dam at the Upper Neuadd Reservoir

Listing Date: 28 July 2005

Last Amended: 28 July 2005

Grade: II*

Source: Cadw

Source ID: 84824

Building Class: Water Supply and Drainage

Location: Situated in the Taf Fechan valley some 9.6 km SW of Llanfrynach.

County: Powys

Town: Brecon

Community: Llanfrynach

Community: Llanfrynach

Locality: Neuadd

Traditional County: Brecknockshire

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Dam to Upper Neuadd reservoir opened 1902, designed by George F. Deacon engineer of London, assisted by T. F. Harvey, Borough Engineer Merthyr Tydfil. Holme & King contractors. Deacon was also engineer to the Liverpool Water Board and designed the tower at Lake Vyrnwy in the 1880s and that at Norton (Cheshire). The architecture at Vyrnwy is based on the Gothic of William Burges, here Deacon seems to have been influenced by the massive detail of the American architect H. H. Richardson.


Long dam of massive rock-faced squared blocks with tooled edges. Long straight dam with sloping face and quarter-round moulded stone coping, each side of centre spillway-dam flanked by two towers. Spillway is bridged by walkway on seven stone piers rising from the sloping face of the very high rock-faced stone main dam, the face curving out at base to a more gentle slope. This is flanked by raised sections to similar slope which carry the two towers. The W tower is much larger, square-plan, with banded rusticated angle piers, modillion cornice broken forward around piers, and tapered square finials at each corner, around stone spire. The S front has a large 3-light mullioned window with arched head, stone voussoirs, sandstone mullions and massive cast-iron glazing bars. W and E sides have low doors protected by stone balconies on the S.
W tower is much shorter, square neo-classical building with the same banded rusticated angle piers, modillion cornice, but heavy blocking course above gabled to S. Low S lunette window with stone voussoirs and cast-iron glazing bars. Door each side with stone balcony on S.
Extending from the base of the E side of the dam, below the main tower is a massively designed tunnel-outlet in Piranesi style, the arch framed in gargantuan rustication, the W side tapered, and the corbelled parapet with low centre gable over bronze plaque recording the completion of the dam in 1902. Brick tunnel lining. A platform in front of the tunnel covers an arched water outlet on the W side.

Reasons for Listing

Graded II* for its special interest as an architecturally-designed dam of spectacularly massive construction and definite character.

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