The Wanganui River drains an area of rugged, mountainous country west and south-west of Lake Taupo. Its catchment area is 2,850 sq. miles, extending from 18 miles further north than the northern end of Lake Taupo to within 25 miles of Stratford; it drains the western slopes of Mounts Ngauruhoe, Tongariro, and Ruapehu. Through the greater part of its length the river is deeply entrenched in a steep-walled gorge cut in soft, upper Tertiary sandstones and mudstones. Only in its lowest 10 miles, from Makirikiri, has any valley plain been developed, and even at Wanganui this is only 2½ miles wide.
The largest tributaries of the Wanganui are the Ongarue River, rising in a mountain ridge to the east of Ongarue town, and the Ohura River, which runs parallel and to the west of the Ongarue. The Wanganui itself flows through the important town of Taumarunui.
The river is not normally fast flowing, and although there are several well-defined rapids on it, it is navigable by small boats for a distance of 140 miles. Although handicapped by the development of a sandbar, the port of Castlecliff in the mouth of the river serves coastal ships. The river was, and still is, an important centre of Maori culture.
The road from Makirikiri to Pipiriki in the gorge of the Wanganui River is a well-known scenic drive, and tourist trips on river boats are increasingly popular.
Wanganui means, literally, “big harbour” and possibly refers to the lower reaches and mouth of the river. The actual meaning is obscure.
by Thomas Ludovic Grant-Taylor, M.SC., New Zealand Geological Survey, Lower Hutt.