The Warragamba River is 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 Nepean River

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 hence of the Hawkesbury River

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:...

, 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 is best known for being the location 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 :...

 and 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...

, which form a major part of the water supply to 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.

Prior to the creation of Lake Burragorang, the Warragamba River would have been formed by the confluences of the Coxs, Nattai

Nattai River

-References:...

, and Wollondilly

Wollondilly River

The Wollondilly River is a perennial river in New South Wales, Australia. It was originally a tributary of the Warragamba River, and hence of the Nepean and Hawkesbury Rivers...

 Rivers in the Burragorang Valley. Downstream, the river flowed through a gorge that varied in width from 300 metres (984.3 ft) to 600 metres (1,968.5 ft), and was 100 metres (328.1 ft) in depth. It was this configuration which allowed a relatively short but high dam

Dam

A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

wall in the gorge to impound a large quantity of water. Today, the Burragorang Valley and most of the Warragamba River is submerged beneath the lake, and the remaining section of the river flows only the 3.5 kilometres (2.2 mi) north-east from the Warragamba Dam to its confluence with the Nepean River.