Cordeaux Dam is the second of four dams constructed as part of the Upper Nepean Scheme to collect water from the Illawarra Plateau.
Located about 94 kilometres south of Sydney, construction on Cordeaux Dam began in 1918 and completed in 1926. The wall was built using cyclopean masonry – sandstone blocks, quarried from the site, fitted into an irregular pattern and packed with sandstone concrete. The dam was upgraded in 1988 with extra drainage in the wall and foundations.
Together with Cataract Dam, Cordeaux’s main role today is to supply water to Camden, Campbelltown and Wollondilly council areas via the Macarthur water filtration plant, but it also forms part of Sydney’s water supply network, connecting to Prospect Reservoir via a series of weirs and canals.
Cordeaux is a curved dam with an unlined spillway to the left of the dam wall. The design is Egyptian inspired. Massive Egyptian style stone gateways guard the entrance to the dam wall, inspired by the popularity of all things Egyptian following the discovery of King Tutankhamun’s tomb in 1922. The dam wall is the longest amongst the Upper Nepean dams, just over 400m but also the lowest (57m). The capacity is similar to Cataract Dam, around 100 gigalitres.
When we visited in late afternoon on 7 April 2021, water was flowing over the spillway, creating a dramatic sight that was enhanced by the late afternoon sunlight. Equally the view of the gorge from the dam wall was also impressive, with terraced stairs and water operation facilities. The dam outlet was also in operation.