The Castlereagh River is located in the State of 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...

. The river rises in the heart of the Warrumbungle mountains

Warrumbungles

The Warrumbungles is the name of a mountain range and National Park located in northern New South Wales, Australia. The nearest town to the Warrumbungles is Coonabarabran...

 and initially flows east through the town of Coonabarabran

Coonabarabran, New South Wales

Coonabarabran is a town in Warrumbungle Shire in northern New South Wales, Australia. At the 2006 census, the town had a population of 2,609.-History and description:...

. It then follows a looping course to the south, west, and finally northwest, passing the towns of Binnaway

Binnaway, New South Wales

Binnaway is a small town located on the Castlereagh River in central New South Wales near the larger centre of Coonabarabran, which is about 35 kilometres to the north. In 2006, the town had a population of 495 people. The road linking these two towns closely follows the meandering Castlereagh River...

, Mendooran, Gilgandra

Gilgandra, New South Wales

Gilgandra, is a town and Local Government Area in the Central West region of New South Wales, Australia. It is located on the junction of the Newell Highway, Oxley Highway and Castlereagh Highway. It can be reached in about six hours by car from Sydney. Like Coonabarabran, Gilgandra can be...

 and Coonamble

Coonamble, New South Wales

Coonamble is a town on the central-western plains of New South Wales, Australia. It lies on the Castlereagh Highway north-west of Gilgandra. At the 2006 census, Coonamble had a population of 2,549...

, before flowing into the Macquarie River before it flows into the Barwon River

Barwon River (New South Wales)

The Barwon River flows through New South Wales, virtually as a continuation of the Macintyre River / Border Rivers system, before joining with the Culgoa River to form the Darling River...

 which then joins Culgoa River

Culgoa River

The Culgoa River is a continuation of one branch of the Balonne River in southern Queensland and flows south-west to join the Darling River near Bourke, New South Wales. It is named for the Aboriginal word meaning "Running Through". Tributaries of the Culgoa include Nebine, Mungallala and Wallam...

 to form the Darling River

Darling River

The Darling River is the third longest river in Australia, measuring from its source in northern New South Wales to its confluence with the Murray River at Wentworth, New South Wales. Including its longest contiguous tributaries it is long, making it the longest river system in Australia.The...

.

Among the longer rivers of central and western New South Wales, the Castlereagh is unique in that it does not have its headwaters in the Great Dividing Range

Great Dividing Range

The Great Dividing Range, or the Eastern Highlands, is Australia's most substantial mountain range and the third longest in the world. The range stretches more than 3,500 km from Dauan Island off the northeastern tip of Queensland, running the entire length of the eastern coastline through...

. In consequence of this, the average flow of the Castlereagh is quite low and variable.

The Darling River is the longest river in Australia and itself flows into the Murray River

Murray River

The Murray River is Australia's longest river. At in length, the Murray rises in the Australian Alps, draining the western side of Australia's highest mountains and, for most of its length, meanders across Australia's inland plains, forming the border between New South Wales and Victoria as it...

 forming a part of the largest river system in the continent

Continent

A continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is...

. The catchment of the Murray-Darling Basin

Murray-Darling Basin

The Murray-Darling basin is a large geographical area in the interior of southeastern Australia, whose name is derived from its two major rivers, the Murray River and the Darling River. It drains one-seventh of the Australian land mass, and is currently by far the most significant agricultural...

 including the tributary of the Castlereagh River drains about twenty percent of the continental surface area of Australia.

The Castlereagh River was explored by John Oxley

John Oxley

John Joseph William Molesworth Oxley was an explorer and surveyor of Australia in the early period of English colonisation.October 1802 he was engaged in coastal survey work including an expedition to Western Port in 1804-05...

 in 1818

1818 in Australia

See also:1817 in Australia,other events of 1818,1819 in Australia and theTimeline of Australian history.- Governors:Governors of the Australian colonies:*Governor of New South Wales – Lachlan Macquarie...

.

In January 2010, major flooding along the river inundated more than 400 rural properties. Fodder

Fodder

Fodder or animal feed is any agricultural foodstuff used specifically to feed domesticated livestock such as cattle, goats, sheep, horses, chickens and pigs. Most animal feed is from plants but some is of animal origin...

drops were needed and some livestock had to be moved.