South Dandalup Dam is a dam in Western Australia. It is located at , where South Dandalup River flows out of Lake Banksiadale. The dam was built in 1971 in response to rapid population growth in Perth, Western Australia's capital city, and a resources boom in the Pilbara.
With a reservoir capacity of 208.2 GL, it is the largest dam providing water to Perth. It has a catchment area of 311 km², a surface area of 21 km² at full storage, and a reservoir length of 22 km. The dam itself is an earthfilled embankment dam, 43 m high and 268 m wide.
Located only 6 km (4 mi) north-east of the historic town of Dwellingup, and around 90 km (50 mi) from Perth, it is a popular recreation area. Western Australia's Water Corporation manages the area, and has provided facilities including picnic areas with gas barbecues, and a number of walk trails.