The explorer George Grey found the river on 11 April 1839, on his second expedition along the west coast. He named it after the distinguished English cartographerJohn Arrowsmith.[5]
The river commences just south of Arrino and north-west of Three Springs near the Midlands Road and flows in a westerly direction for a length of 85 kilometres (53 mi) to the coast and terminates in Arrowsmith Lake, 9 kilometres (6 mi) inland from Cliff Head.
The river drops a total of 219 metres (719 ft) in elevation over the course of its length.
Flooding in surrounding areas occurred in 1932 following a torrential downpour that caused the river and surrounding creeks to rise and flood a few hours later.[6]
The salinity levels in the river are often higher than 1000 mg/L due to brackish run-off water, but the potential bore yields of the catchment are quite high.[7]