Lake Ōhau, Alpine lake in Mackenzie District, New Zealand

Lake Ōhau is the smallest of three parallel lakes along the northern edge of the Mackenzie Basin, covering 60 km². The Hopkins and Dobson rivers enter at the northern end, and the Ōhau River leaves from the southeast corner. The Barrier Range, including Mount Sutton (2007 m), rises to the west, while the Ben Ohau Range lies to the east.

Benmore Station was established in 1857, launching commercial sheep operations around this water body, while hydroelectric development occurred downstream during the twentieth century throughout the wider Mackenzie region.

Ngāi Tahu oral history identifies Rākaihautū as the creator of this body of water, formed with his ko (digging stick) as part of a wider journey that shaped multiple waterways across Te Waipounamu.

Access is via Lake Ōhau Road, a 17 km turn-off from State Highway 8 between Twizel and Omarama. A gravel road runs around almost all of the eastern and western shorelines, giving good access to the lakeshore. The Hopkins and Dobson rivers are known spots for trout. Snow is common in June, July and August.

A wildfire swept through Lake Ōhau Alpine Village during October 2020, burning approximately 5000 hectares (12,000 acres) and destroying 48 homes before firefighters contained the blaze after several days.