Mortlock
Etymology	Henry Mortlock Ommanney, a surveyor
Location
Country	Australia
State	Western Australia
Region	Wheatbelt
Physical characteristics
Source
• location	near Belmunging
• coordinates	31°51′48″S 117°9′2″E / 31.86333°S 117.15056°E / -31.86333; 117.15056
• elevation	249 m (817 ft)
Mouth	Avon River
• location	west of Northam
• coordinates	31°38′41″S 116°40′20″E / 31.64472°S 116.67222°E / -31.64472; 116.67222
• elevation	146 m (479 ft)
Length	81 km (50 mi)
Basin size	16,800 km2 (6,500 sq mi)
Discharge
• location	mouth
• average	17,800,000 m3/s (630,000,000 cu ft/s)
Basin features
River system	Avon River
[1][2]

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

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 metres (338 ft) over its 81-kilometre (50 mi) course.^[1]

The river is saline and delivers the most salt (approximately 91 tonnes (90 long tons) per year) into the Avon River.

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.^[3]

• List of watercourses in Western Australia