The Mortlock River is a perennial river in the Wheatbelt region of Western Australia.

Course and features

The headwaters of the river rise near Belmunging then flow in a northerly direction, crossed by the Goldfields Road and continuing in a north-westerly direction to finally flow parallel to the Northam York Road and crossed by the Great Eastern Highway. The river is joined by three minor tributaries: Mortlock River North, Mortlock River East and Meenaar South Creek. The river discharges into the Avon River, just west of Northam. The Mortlock descends 103 m over its 81 km course. The river is saline and delivers the most salt (approximately 91 t per year) into the Avon River.

Name

The river was named after the surveyor Henry Mortlock Ommanney in the 1830s. Ommanney visited the river during an expedition through the area in 1835.