The Waiau, so named, flows from the southern tip of Te Anau and meanders for some 12 kilometres along the western edge of a small plain before entering the northeastern corner of Lake Manapouri, the second of the two large lakes in the Waiau system. Manapouri is also fed by the Spey and Grebe Rivers, as well as the Freeman, Awe, and Iris Burns. The Waiau flows out of the lake in the southeast, close to the small town of Manapouri, and shortly thereafter is joined by the waters of the Mararoa River.