Woronora Dam, Heritage-listed concrete gravity dam in New South Wales, Australia

Woronora Dam is a curved concrete gravity dam on the Woronora River, 24 km upstream of its junction with the Georges River. Its wall is 66 m high and 390 m long, with lower courses of cyclopean masonry cut from sandstone quarried on site and a main wall of blue metal and gravel concrete. Two inspection galleries run inside the wall, and a separate serpentine spillway carries floodwater through a concrete-lined cutting.

Construction started in 1927 as Sydney's fifth water supply project, but was paused during economic hardship and finally finished in 1941. This extended timeline shaped how water resources were developed for the region over following decades.

The dam's name comes from the Woronora River, and its reservoir is often wrongly called Lake Woronora. Six fibrolite workers' cottages from the 1927–1941 construction camp survive as on-site maintenance housing, while the rest of the township became picnic grounds. The 1941 comedy drama Dad Rudd MP filmed construction scenes here, using workers and their families as extras.

Woronora Dam Road leaves the Princes Highway and runs 7 km to the dam, where a carpark and picnic area sit beside the wall. A walking trail crosses the dam crest, so visitors can look down both the reservoir and the serpentine spillway cutting. Six former workers' cottages remain as on-site staff housing.

The spillway is a separate serpentine channel, not part of the main wall, and discharges floodwater at 1,470 cubic metres per second through a concrete-lined cutting into the river below the dam. The reservoir is often wrongly called Lake Woronora; its correct name is Woronora Dam, the same as the structure.