The Wollondilly River is a perennial river

Perennial stream

A perennial stream or perennial river is a stream or river that has continuous flow in parts of its bed all year round during years of normal rainfall. "Perennial" streams are contrasted with "intermittent" streams which normally cease flowing for weeks or months each year, and with "ephemeral"...

 in New South Wales

New South Wales

New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. It was originally a tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Warragamba River

Warragamba River

The Warragamba River is a tributary of the Nepean River, and hence of the Hawkesbury River, in New South Wales, Australia. It is best known for being the location of the Warragamba Dam and Lake Burragorang, which form a major part of the water supply to the Sydney region.Prior to the creation of...

, and hence of the Nepean

Nepean River

The Nepean River is a river in the coastal region of New South Wales, Australia.The headwaters of the Nepean River rise near Robertson, about 100 kilometres south of Sydney and about 15 kilometres from the coast. The river flows north in an unpopulated water catchment area into Nepean Dam, which...

 and Hawkesbury

Hawkesbury River

The Hawkesbury River, also known as Deerubbun, is one of the major rivers of the coastal region of New South Wales, Australia. The Hawkesbury River and its tributaries virtually encircle the metropolitan region of Sydney.-Geography:-Course:...

 Rivers. Today it flows into Lake Burragorang

Lake Burragorang

Lake Burragorang is the water storage impounded by Warragamba Dam. It collects the waters of the Coxs, Kowmung, Nattai, Wingecarribee, and Wollondilly Rivers. It is the major water storage for Sydney, Australia...

, created by construction of the Warragamba Dam

Warragamba Dam

Warragamba Dam is the primary water source for the Australian city of Sydney. It is approximately to the west of Sydney on the Warragamba River, a tributary of the Hawkesbury River, and impounds Lake Burragorang.- Overview :...

 across the Warragamba River, which is the major water supply for the Sydney

Sydney

Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

 region.

The Wollondilly River river rises about 7 kilometres (4.3 mi) east of Crookwell

Crookwell, New South Wales

Crookwell is a small town located in the Southern Tablelands of New South Wales, Australia, in the Upper Lachlan Shire. At the 2006 census, Crookwell had a population of 1,993 people. The town is at a relatively high altitude in Australian terms , and there are occasional snowfalls during the...

 and initially flows south to a point near Pomeroy. It then flows south-east and then east through Goulburn

Goulburn, New South Wales

Goulburn is a provincial city in the Southern Tablelands of New South Wales, Australia in Goulburn Mulwaree Council Local Government Area. It is located south-west of Sydney on the Hume Highway and above sea-level. On Census night 2006, Goulburn had a population of 20,127 people...

, where it is joined by the Mulwaree River

Mulwaree River

The Mulwaree River, also known as Mulwaree Ponds, is a river of the state of New South Wales in Australia. It is a tributary of the Wollondilly River....

. At Towrang

Towrang, New South Wales

Towrang is a village in the Southern Tablelands of New South Wales, Australia, in Goulburn Mulwaree Council. It is approximately 13 km before Goulburn on the Hume Highway 180 km south from Sydney. At the 2006 census, Towrang and the surrounding area had a population of 406.The town was...

 the river turns north-east to a point near Bullio

Bullio, New South Wales

Bullio is a small village in the Southern Highlands of New South Wales, Australia, in Wingecarribee Shire. In 2006, Bullio had a population of 298 people.- References :...

, where it is joined by the Wingecarribee River

Wingecarribee River

The Wingecarribee River rises on the heights at Robertson, fictional home of Babe the pig. It flows westwards, away from the sea, across the Southern Highlands plateau, near Bowral and Moss Vale, to Berrima...

. From here the Wollondilly River takes a wide detour to the north-west to Barrallier

Barrallier, New South Wales

Barrallier is a historical locality near the Southern Highlands of New South Wales, Australia, in Upper Lachlan Shire. The area was named after engineer and explorer Francis Barrallier....

, where it turn east before eventually regaining its north-easterly course into Lake Burragorang. It has a total length of approximately 156 kilometres (96.9 mi).

Wollondilly Shire is a local government area that is named after the Wollondilly River.