One of the main rivers of Southland, it rises in the Thomson mountains west of Lake Wakatipu and flows 105 miles southward to enter Foveaux Strait by the New River estuary near Invercargill. The catchment area is some 448 sq. miles, and major floods occurred in March 1913 of 84,000 cusecs at Winton and in June 1955 of 19,686 cusecs at Lochiel Bridge. A representative rate of flow at Mossburn Bridge on 12 October 1954 was 7,047 cusecs. The upper reaches of the river flow in mountainous sheep-farming country, but the main reaches lie across the plains of the Waimea district and Southland. The river, which is generally clear, flows over a gravel bed and is used at several places as a source of domestic and municipal water supply. The major intake near Branxholme, north of Invercargill, supplies that city and Bluff with much of its water. The estuary near Invercargill affords facilities for boating.

Like many Maori place names, the meaning of Oreti is obscure. Perhaps the name was originally Koreti which means “a snare at yonder place” or “the snare”. If Koreto, the meaning is “trickling down”.

by Bryce Leslie Wood, M.SC., New Zealand Geological Survey, Dunedin.