Ōhau River (Canterbury)

Ōhau River
Ōhau River upstream of Lake Ruataniwha
Location
CountryNew Zealand
Physical characteristics
SourceLake Ōhau
  coordinates44°17′06″S 169°56′11″E / 44.2851°S 169.9365°E / -44.2851; 169.9365
  elevation540 metres (1,770 ft)
MouthLake Benmore
  coordinates
44°20′39″S 170°12′17″E / 44.3441°S 170.2048°E / -44.3441; 170.2048
  elevation
380 metres (1,250 ft)
Length27 km (17 mi)
Basin features
ProgressionLake BenmoreLake AviemoreLake WaitakiWaitaki RiverPacific Ocean
Tributaries 
  leftTwizel River
  rightWairepo Creek
WaterbodiesLake Ruataniwha

The Ōhau River is a river in the Mackenzie Basin of New Zealand's South Island. It is the primary outflow of Lake Ōhau, from which it flows in a roughly eastward direction until reaching the artificial Lake Benmore after a distance of roughly 27 kilometres (17 mi). In 1981, the artificial Lake Ruataniwha was created along the river's length to power a small hydroelectric power station as part of the Waitaki hydro scheme. Prior to the creation of the Waitaki hydro scheme, the river flowed directly into the Waitaki River rather than through a series of lakes. The river forms part of the traditional boundary between Otago and Canterbury regions.

Prior to European settlement of the region, the river was a traditional mahinga kai (food gathering site) for Māori travelling through the Mackenzie Basin, providing valuable food sources such as weka, tuna (eels), and pora (Brassica rapa subsp. sylvestris).