The Waitaki River is only some 68 miles in length but with its major tributary rivers – Tekapo (64 miles), Pukaki (42 miles), Ohau (48 miles), Ahuriri (64 miles), Hakataramea (36 miles), and Otematata (20 miles) – the catchment of 4,565 square miles is in size second only to that of the Clutha River, the largest in New Zealand. The alpine watershed is over 50 miles in length and over 100 miles westward from the river mouth. The first three tributary rivers named above are glacier fed and drain the most northerly of the southern lakes, Tekapo, Pukaki, and Ohau. The minimum recorded flow since 1930 at the Waitaki Power Station is 2,150 cusecs: the maximum during the 1931 flood was 85,000 cusecs. The Waitaki catchment is one of the most valuable hydro-electric areas in New Zealand. The second largest earth dam in the Southern Hemisphere and largest power station in New Zealand are located on the Waitaki at Benmore. An attractive 30-square-mile lake has been formed on the river as a result of this development. Waitaki Power Station and a small plant at the outlet of Lake Tekapo are the only other stations operating in the area but a fourth is under construction at Aviemore. Several other sites are under investigation. There is a control dam at Lake Pukaki.
The generally accepted meaning of the name is weeping waters. “Waitaki” is a southern Maori variant of the northern Maori “Waitangi”.
by Alexander Russell Mutch, B.SC., A.O.S.M., New Zealand Geological Survey, Dunedin.