The Ōhau River is 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.[1] Prior to the creation of the Waitaki hydro scheme, the river flowed directly into the Waitaki River rather than through a series of lakes.[2] The river forms part of the traditional boundary between Otago and Canterbury regions.[3]
| Ōhau River | |
|---|---|
 Ōhau River upstream of Lake Ruataniwha | |
.png)  | |
| Location | |
| Country | New Zealand |
| Physical characteristics | |
| Source | Lake Ōhau |
| • coordinates | 44°17′06″S 169°56′11″E / 44.2851°S 169.9365°E |
| • elevation | 540 metres (1,770 ft) |
| Mouth | Lake Benmore |
• coordinates | 44°20′39″S 170°12′17″E / 44.3441°S 170.2048°E |
• elevation | 380 metres (1,250 ft) |
| Length | 27 km (17 mi) |
| Basin features | |
| Progression | Lake Benmore→ Lake Aviemore→ Lake Waitaki→ Waitaki River→ Pacific Ocean |
| Tributaries | |
| • left | Twizel River |
| • right | Wairepo Creek |
| Waterbodies | Lake Ruataniwha |
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)[4][5]