The Murray River is a river in the southwest of Western Australia. It played a significant part in the expansion of settlement in the area south of Perth after the arrival of British settlers at the Swan River Colony in 1829. It should not be confused with the Murray River in southeastern Australia, which is the longest river in the country.
The river is one of the few major rivers close to Perth which is devoid of dams for public water supply. It includes a catchment area including a large part of the wheatbelt and southwest of the state, draining from 450 mm (18 in) per annum average rainfall country in the east near Pingelly, westward through the high rainfall parts of the Darling Range around Dwellingup with an average rainfall of 1,300 mm (51 in) per annum.
The first of the two major tributaries, the Hotham River, starts its journey near Narrogin. The other major tributary is the Williams River, which starts between Williams and Narrogin. These two tributaries are the main rivers which drain the eastern wheat-belt.
The Murray River then flows through forested high-rainfall parts of the Darling Range to emerge near Pinjarra.
Another tributary, the Dandalup River, joins the Murray a short distance downstream of Pinjarra. This section is known as the lower Murray and is navigable in small boats. The river then flows across the sand plain between the Darling Scarp and the coast to empty into the Peel Estuary near Mandurah.
The canal development of North and South Yunderup is situated several kilometres upstream from the estuary.