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 over its
course. The river is
saline and delivers the most salt (approximately per year) into the Avon River. ==Name==