Lake Ōhau is a lake in the Mackenzie Basin in the South Island of New Zealand. The Hopkins and Dobson rivers fed into the northern end of Lake Ōhau. These rivers have their headwaters in the Southern Alps / Kā Tiritiri o te Moana. The lake's outflow is the Ōhau River, which travels from the southeast corner of Lake Ōhau and feeds into the Waitaki River hydroelectric project.
The Barrier range (and Mount Sutton 2007m in particular) dominate the western side of Lake Ōhau, while the Ben Ohau range dominates the eastern side of Lake Ōhau. At the northern end of the lake, in between the Hopkins and Dobson rivers, lies the Naumann Range of mountains (with Mt Glenmary 2590m being the tallest).
The New Zealand Ministry for Culture and Heritage gives a translation of "place of Hau" for Ōhau, but an alternative meaning could be "windy place".