Waimakariri River

Waimakariri River
The Waimakariri with Christchurch in the background
Country	New Zealand
Basin features
Main source	Southern Alps
River mouth	Pacific Ocean 0 m (0 ft)

The Waimakariri River, formerly briefly known as the Courtenay River, is one of the largest of the North Canterbury rivers, in the South Island of New Zealand. It flows for 151 kilometres (94 mi) in a generally southeastward direction from the Southern Alps across the Canterbury Plains to the Pacific Ocean. In Māori, Waimakariri has several meanings, one of which is "river of cold rushing water". The river is known colloquially in Canterbury as "The Waimak".

The river rises on the eastern flanks of the Southern Alps, eight kilometres southwest of Arthur's Pass. For much of its upper reaches, the river is braided, with wide shingle beds. As the river approaches the Canterbury Plains, it passes through a belt of mountains, and is forced into a narrow canyon (the Waimakariri Gorge), before reverting to its braided form for its passage across the plains. It finally enters the Pacific north of Christchurch, near the town of Kaiapoi.

In 1849, the chief surveyor of the Canterbury Association, Joseph Thomas, gave the river the name Courtenay River after Lord Courtenay, but it lapsed into disuse.

Geological evidence indicates that the river mouth has been very mobile, at times flowing through the current location of Christchurch and even flowing into Lake Ellesmere / Te Waihora south of Banks Peninsula for a time.

Instead of being unoccupied crown land as are most New Zealand river beds, the bed of the Waimakariri River is vested in the Canterbury Regional Council (Environment Canterbury).