Cataract Dam is one of the oldest and most picturesque dams in Sydney. It is the first of four dams to be constructed as part of the Upper Nepean Scheme and at the time of its construction from 1902 to 1907, Cataract Dam was the biggest engineering project in Australia and the fourth biggest in the world.
Cataract Dam is designed to collect water from the Illawarra Plateau by damming Cataract River, a tributary of Nepean River.
It’s main role today is to supply water to Camden, Campbelltown and Wollondilly council areas via the Macarthur water filtration plant. It is also part of Sydney’s water supply network connected via weirs and canals all the way to Prospect Reservoir.
Cataract Dam is a straight dam with an unlined side spillway to the left of the dam wall. For the first time in Australia, pre-cast moulded concrete blocks were used to build the upstream face of the dam. This spillway was widened almost immediately to prevent risk of floodwater overtopping the dam wall. In 1987 post-tensioned anchors were installed for additional reinforcement.
The dam is around 250m in length and almost 60m in height. It has a capacity of nearly 100 gigalitres.
When I visited in 7 April 2021, the dam was releasing waters via the outlets which created a loud gushing noise. Two large and magnificent plumes of water arced into Cataract River.
We parked at the picnic grounds, and walked towards the dam via a path passing some historical cottages constructed when the dam was being built. The largest of these is dubbed “The Manor”, a Federation Queen Anne bungalow, with matching outbuildings and landscaped gardens surrounded by a castle-like sandstone fence. When built, the house contained a board room, offices, four bedrooms and a kitchen.
The Manor wasn’t open to the public but apparently can be booked as accommodation. We found remains of what seems to be a mini-zoo nearby, as well as a large rock, and a historic workshop. The walk to the dam wall is via an avenue of phoenix palms and jacarandas and then descending down a long flight of stairs.
The dam itself has a unique design which reminded me of a castle. The valve house has Tudor style features a slate hipped roof with ridgecap finials and with parapet gable ends on the north and south sides and arched parapets on the east and west sides. It looks like a castle turret.
The dam wall provides views of the lake and Keele Island upstream, and of the deep Cataract Gorge downstream. And the far end of the wall is the spillway.