The Waikōau River is a river in southern Fiordland, New Zealand. Since 21 June 2019 the official name has been Waikōau River.[1] Waikōau River North Branch has been the official name of a tributary, which joins the river about a kilometre from the sea, since 19 December 2019.[2] Rising north of the Hump Ridge, it flows south-eastward into Te Waewae Bay.