Footbridge at hydro-electric station (partly in Llanwrthwl community)

Power stations are symmetrical pair. Brown stone, slate roof. Parallel to river Elan. Each has one 4-window block with attached lower 3-window block set towards river; lantern ventilator to each block. Larger block has, to river, central doorway with small window over; 2 windows to each side (cruciform glazing); rear elevation similar but lacks doorway; gable end towards dam has doorway with elliptical head, and round window above. Lower block set forward with doorway in angle; 3 windows, central 2-light window flanked by 3-light windows, rear similar but with central doorway, not window; gable end away from dam has large 3-light round-headed window with heavy transom. Interior retains operating machinery including turbines and generators to upstream blocks, downstream blocks have railed pits, wooden cases with gauges etc.

Footbridge connects the two stations. Stone; 3 broad elliptical arches; return walls to ends opposite entrances to power houses. Bridge connects with revetment walls below power houses; grey stone, splayed downstream ends with arched outlets.