The Waitaki River is a large river in the South Island of New Zealand, some 110 km long. It is the major river of the Mackenzie Basin.

It is a braided river which has Lake Benmore, Lake Aviemore and Lake Waitaki at its headwaters. These are ultimately fed by three large glacial lakes, Pukaki, Tekapo, and Ohau. Lake Benmore and Lake Aviemore are contained by hydroelectric dams.

The Waitaki has several tributaries, notably the Ahuriri River and the Hakataramea River. It passes Kurow and Glenavy before entering the Pacific Ocean between Timaru and Oamaru on the east coast of the South Island.

The middle of the river bed forms a political boundary between the Canterbury and Otago regions. A proposal for a series of canals and dams was made by the Meridian Energy for irrigation and electricity generation on the river. This was abandoned in 2004 citing lack of commercial viability as one of a number of reasons.

The river is popular for recreational fishing and jetboating.

See also

• List of rivers of New Zealand
• Reservoirs and dams in New Zealand