Cardrona River

The Cardrona River is in Otago in the South Island of New Zealand.^[1] It is one of the first tributaries of the Clutha River / Mata-Au, which it meets only 5 kilometres (3 mi) from the latter's origin at the outflow of Lake Wānaka.

Cardrona River Ōrau
View of Cardrona Valley of the Cardrona River
Native name	Ōrau (Māori)
Location
Country	New Zealand
Region	Otago
Settlements	Wānaka, Cardrona
Physical characteristics
Source	Crown Range
Mouth	Clutha / Mata-au River
• coordinates	44°41′S 169°12′E
Length	40 km (25 mi)
Basin features
Progression	→ Clutha River → Pacific Ocean

The Cardrona flows north for 40 kilometres (25 mi) down the steep narrow Cardrona Valley. Its headwaters are near New Zealand's highest main road, the Crown Range route.^[2] The river runs past the settlement of Cardona and the Cardrona skifield, then south of Wānaka township.

The original name of the river is the Ōrau. It was a traditional Māori route linking Whakatipu Waimāori (Lake Wakatipu) with lakes Wānaka and Hāwea. Ngāi Tahu recorded Ōrau as a kāinga mahinga kai (food-gathering place) where tuna (eels), pora ('Māori turnip') and weka were gathered.^[3]

In 2017, a toxic cyanobacteria phormidium was found in the river after a period of warm temperatures. The public were warned that people and dogs should avoid contact with the water while the algae was present.^[4] The Cardrona River is one of several rivers in the Otago region that are known as vulnerable to outbreaks of cyanobacteria.^[5]

An environmental DNA analysis in 2023 revealed a previously unknown population of galaxid fish are present in the Cardrona River. The species identified is the Clutha flathead galaxid, which is critically threatened and close to extinction.^[6]

In 2024, a group of 50 volunteers removed around 1,000 kg (2,200 lb) of rubbish from a section of the river. Further cleanups were planned for other sections of the river.^[7]