The Waitaki river is the major river of the Mackenzie Basin, a large intermontane basin running between the Southern Alps and the Waimate foothills that forms the headwaters of the Waitaki River catchment. Fed by three large glacial lakes, Tekapo, Ohau as well as Lake Pukaki, the Waitaki River flows through Lake Waitaki, Lake Benmore and Lake Aviemore, the latter two contained by Benmore Dam and Aviemore Dam respectively. There several tributaries, notably the Ahuriri River and the Hakataramea River. It passes Kurow and Glenavy before completing its 110km journey and entering the Pacific Ocean between Timaru and Oamaru on the east coast.
The Waitaki River has New Zealand’s fourth largest flow with a mean flow (1927 -2000) at the Waitaki Dam of 359 cumecs. The river’s flow is normally low in winter, increasing in spring when the snow from the Southern Alps melts. Summer flows are dependent on rainfall, and generally decline during autumn as smaller streams in the catchment begin to freeze. The glacial lakes dampen flood peaks and modifies flood flows into the lower catchment. This natural storage, together with the control of lake levels by hydro-electricity development, regulates downstream flow. The median flow of the Waitaki River at Kurow is 356 cumecs.