The Rakaia River is in the Canterbury Plains in New Zealand's South Island. The Rakaia River is one of the largest braided rivers in New Zealand. The Rakaia River has a mean flow of 203 cubic metres per second (7,200 cu ft/s) and a mean annual seven-day low flow of 87 m3/s (3,100 cu ft/s). In the 1850s, European settlers named it the Cholmondeley River, but this name lapsed into disuse.
|Native name||Rakaia (Māori)|
|Length||150 kilometres (93 mi)|
|• average||203 cubic metres per second (7,200 cu ft/s)|
|• minimum||87 m3/s (3,100 cu ft/s)|
It rises in the Southern Alps, travelling 150 kilometres (93 mi) in a generally easterly or southeasterly direction before entering the Pacific Ocean 50 kilometres (31 mi) south of Christchurch. It forms a hapua as it reaches the ocean.
The Rakaia River is bridged in two places. The busiest crossing is at the small town of Rakaia, 20 kilometres (12 mi) from the river mouth, where State Highway 1 and the South Island Main Trunk Railway cross the river using separate bridges. These two bridges are New Zealand's longest road and rail bridges respectively, approximately 1.75 kilometres (1.09 mi) long. A second bridge, much shorter and less used, spans the Rakaia Gorge.
The Rakaia River is a celebrated Chinook salmon fishery. It has been identified as an Important Bird Area by BirdLife International because it supports breeding colonies of the endangered black-billed gull. The river is also known for its large wrybill population which represents 73 percent of the total population. Other important bird species using the riverbed are black-fronted tern and banded dotterel.
- "Place name detail: Rakaia River". New Zealand Gazetteer. New Zealand Geographic Board. Retrieved 2 April 2008.
- Morland, K. 1994: Water Resources of the Canterbury Region. Canterbury Regional Council Unpublished Technical Report U94/59.
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- "The Rakaia River", Selwyn District Council, "Archived copy". Archived from the original on 28 September 2007. Retrieved 7 September 2014.CS1 maint: archived copy as title (link), retrieved 31 August 2007
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- "Rakaia River". BirdLife data zone: Important Bird Areas. BirdLife International. 2012. Retrieved 15 November 2012.
- O’Donnell, C.F.J. (2000). The significance of river and open water habitats for indigenous birds in Canterbury, New Zealand, Environment Canterbury Unpublished Report U00/37.