Wollondilly Shire is a local government area adjacent to the south-western fringe of Sydney, parts of which fall into the Macarthur, Blue Mountains and Central Tablelands regions in the state of New South Wales, Australia.
Wollondilly Shire is named after the Wollondilly River. The area is traversed by the Hume Highway and the Southern Highlands railway line. Wollondilly Shire contains several small towns and villages broken up by farms and sandstone gorges. To its west is wilderness and includes the Nattai Wilderness and the Burragorang Valley. The majority of the Shire is either national park or forms part of the water catchment for Sydney’s water supply. The Shire provides 97% of Sydney’s water supply.