This river has its source at the junction of the Wairua and Mangakahia Rivers in the central part of the North Auckland Peninsula. The river is navigable as far as Tangiteroria and with its major tributaries represents a drowned valley. Its major tributaries from the north are the Kirikopuni, Tangowahine, Awakino, and the Kaihu and, from the south, the Manganui. For some distance from the Kaipara Heads the river is flanked to the east by extensive swamps, many of which are now reclaimed and provide highly productive dairy lands. Chief of these is the old Tokatoka Swamp, now the Ruawai Flats. To the west is a series of dunes, both fixed and moving. Among them is a series of lakes and along the shore are drained swamps fringed with mangroves. This coastal sand belt was called “The Desert Coast” by Captain James Cook, who arrived off there in January 1770. At Dargaville, which was named after an early settler, where the river swings west, the country is alternating sandstone and shale of Upper Cretaceous age. East of Tokatoka are several prominent peaks, representing old volcanic necks. The bar at the Kaipara Heads is dangerous to shipping and several vessels have been lost there. The Wesleyan Church established a mission among the Maori people at Tangiteroria in 1836; in 1853 it was moved to Mount Wesley, near Dargaville.

Early development of the Wairoa was associated with the kauri pine. Lumbermen followed in the wake of the missionaries and early adventurers and pitsawed the kauri for building material from about 1840. About 1850 there developed a trade in the provision of spars for sailing vessels. Sawmills grew up along the river, at Aratapu in 1865, Mititai in 1866, and Te Kopuru in 1871. The kauri-gum industry was a large and thriving one, the principal areas being Babylon (Scotty's Camp), Tokatoka, and Aranga (Maunganui Bluff Swamp). Export of flax began from the Wairoa as early as 1840. The first ship was built at the Oparau and, later, yards were constructed at Omara about 1840, Aratapu about 1880, and Te Kopuru in 1901. With the virtual extinction of the kauri these industries either ceased or greatly diminished. Communication with Auckland was, in the early days, by sea to Kaukapakapa, overland to Riverhead, and by sea down the Waitemata. Later, mail, passengers, and freight were landed at Helensville, which had been connected by rail to Riverhead. The Kaipara Steam Ship Co's ships called at the many jetties on each side of the long waterway. Last of its ships were the Wairua and the Ruawai. Today there is little sawmilling, but two companies crush lime for agricultural purposes. The real wealth of the district lies in its agriculture, and so important is dairy farming that the Wairoa can support two large dairy factories, one at Mangawhare and one at Ruawai. The name Wairoa means “Long water”.

by Robert Findlay Hay, M.A., B.E.(MINING), Scientific Officer, New Zealand Geological Survey, Otahuhu.