The Waiau River is the largest river system in the southwestern corner of the South Island. It has its sources in the
Eglinton and
Clinton Rivers, both of which are major inflows to
Lake Te Anau, one of the two large lakes formed from
glaciation which are part of the Waiau's system. Other rivers to flow into Te Anau include the
Glaisnock River,
Wapiti,
Doon, and
Upukerora Rivers, as well as numerous
burns, of which the largest are the
Junction,
Woodrow,
Ettrick,
Snag, and
Mackenzie Burns. 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. From here, the Waiau continues south across a relatively narrow plain, fed by numerous small creeks and burns, the largest of which are the
Excelsior,
Whare and
Redcliff Creeks and the
Borland Burn. At
Monowai it is met by the
Monowai River, the outflow of a further glacially formed lake, also named
Monowai. At the Waiau's junction with the small
Wairaki River the plain widens. From here the Waiau is fed by numerous other streams and burns, notably the
Lill Burn close to
Clifden and the
Alton Burn, as well as the
Orauea River, close to
Tuatapere. As the river nears the coast it widens, with several small low-lying islands contained within its channels At its mouth on
Te Waewae Bay, the river forms a long tidal lagoon separated from the sea by a narrow
sandbar which extends along the coast for several kilometres. ==Geology==