The Mortlock River is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 in the Wheatbelt of Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

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The headwaters of the river rise near Belmunging then flow in a northerly direction crossing the Goldfields Road and continuing in a north westerly direction to finally flow parallel to the Northam York Road and crossing Great Eastern Highway

Great Eastern Highway

The Great Eastern Highway is a major road between the Western Australian cities of Perth and Kalgoorlie. It is a key route for vehicles accessing the eastern wheatbelt and the eastern goldfields...

. The river discharges into the Avon River

Avon River (Western Australia)

The Avon River is a river in Western Australia. It is a tributary of the Swan River totalling 280 kilometres in length, with a catchment area of 125,000 square kilometres.-Catchment area:...

, of which it 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...

, just west of Northam

Northam, Western Australia

Northam is a town in Western Australia, situated at the confluence of the Avon and Mortlock Rivers, about north-east of Perth in the Avon Valley. At the 2006 census, Northam had a population of 6,009. Northam is the largest town in the Avon region...

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The river was named after the surveyor

Surveying

See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

 Henry Mortlock Ommanney in the 1830s. Ommanney was the first Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an to discover the river during an expedition through the area in 1835.

There are three tributaries

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 Mortlock River; Mortlock River North, Mortlock River East and Meenaar South Creek.

The river is saline

Saline water

Saline water is a general term for water that contains a significant concentration of dissolved salts . The concentration is usually expressed in parts per million of salt....

and delivers the most salt (approximately 91 tonnes per year) into the Avon River.