|Native name||Kōtukuwhakaoka (Māori)|
|• location||Lake Brunner|
The Arnold River (Māori : Kōtukuwhakaoka)  is a river on the West Coast of New Zealand's South Island. It is the outflow of Lake Brunner, which it links with the Grey River at Stillwater. The Arnold River flows northwest for 20 kilometres (12 mi), joining the Grey immediately above the town of Brunner, some 15 kilometres (9 mi) from the Tasman Sea. It is a popular spot for whitewater kayaking and trout fishing.
The river was known to Māori as Kōtukuwhakaoka, the name of a Māori chief from the North Island who had followed it upstream to the lake. According to legend, the chief was attacked and killed by a lake taniwha, which later became one of the two islands in the lake after it was in turn killed by his son.  Explorer Thomas Brunner, who was the first European to travel up the river to its source, spelled it "Kotu-urakaoka" in the proclamation that in 1853 defined the provincial boundaries. 
In 1859 surveyor John Rochfort and his men arrived at the opposite shore of the lake, which he proceeded to name after Brunner. They made a canoe from a hollowed-out kahikatea log and paddled across the lake to where flowed into the Kōtukuwhakaoka, which Rochfort named the "Arnould River". The name "Arnould" appears on maps in the 1860s, but from 1865 onwards the river was usually spelled "Arnold".  Rochfort attempted to survey the "Arnould River" by canoe, but it was choked up with logs and snags, and the party eventually abandoned their vessel for "dreary marches in the midst of drenching rain." 
The Arnold Power Station is on the river close to its confluence with the Grey. TrustPower, which operates the current hydroelectric station, has a proposal for another hydro-electricity scheme on the river. 
In the early days of the settlement of Moana, Noel Peat owned land in the township and across the mouth of the Arnold River, and since 1929 had petitioned the government to build a bridge at Moana connecting the two. No bridge was built, until in 1990 as part of New Zealand sesquicentennial celebrations Fletcher Challenge and the Department of Conservation collaborated on the construction of a 83-metre footbridge, which took 15 weeks to build, opening on 15 September 1990. It provided public access to the Tasman Forest Accord Scenic Reserve, 2050 ha of native forest protected from logging in 1989. The Lake Brunner Centennial Committee later developed a walking trial along the western shore of the Arnold River, now known as the Rakaitane Walk.  : 54
Greymouth is the largest town in the West Coast region in the South Island of New Zealand, and the seat of the Grey District Council. The population of the whole Grey District is 14,100, which accounts for 43% of the West Coast's inhabitants. The Greymouth urban area had an estimated population of 8,310. A large proportion of the District, 65%, is part of the Conservation Estate owned and managed by the Department of Conservation making Greymouth a natural centre for walkers and trampers.
The Grey River / Māwheranui is located in the northwest of the South Island of New Zealand. It rises 12 kilometres southwest of the Lewis Pass in Lake Christabel, one of numerous small lakes on the western side of the Southern Alps, and runs westward for 120 kilometres before draining into the Tasman Sea at Greymouth. Thomas Brunner, who explored the area in the late 1840s, named the river in honour of Sir George Grey, who first served as Governor of New Zealand from 1845 to 1854. The Ngāi Tahu Claims Settlement Act 1998 changed the official name of the river to Grey River / Māwheranui in 1998. The Māori name for the river system and surrounding area is Māwhera, with Māwheranui being distinguished from the northern branch Little Grey River / Māwheraiti.
Lake Brunner, 31 km (19 mi) southeast of Greymouth, is the largest lake in the West Coast region of New Zealand. The main settlement, Moana, is on its northern shore. It is an important settlement and waystation for local Māori. The first Europeans in the area were loggers, and sawmills were an important early industry. Being several kilometres inland from the coast road, it is less frequently visited by tourists than many of the West Coast's scenic highlights, but it is becoming increasingly popular, in part due to its reputation for fishing.
The Taramakau River is a river of the West Coast Region of the South Island of New Zealand. It rises in the Southern Alps / Kā Tiritiri o te Moana near Harper Pass, 80 kilometres (50 mi) due east of Hokitika, and runs westward for 75 kilometres (47 mi) into the Tasman Sea 15 kilometres (9.3 mi) south of Greymouth.
Lake Kaniere is a glacial lake located on the West Coast of New Zealand's South Island, nearly 200 m deep and surrounded on three sides by mountains and mature rimu forest. It is regarded by many as the most beautiful of the West Coast lakes, and is a popular tourist and leisure destination.
Waka are Māori watercraft, usually canoes ranging in size from small, unornamented canoes used for fishing and river travel to large, decorated war canoes up to 40 metres (130 ft) long.
Grey District in the West Coast Region of New Zealand is a municipality that covers Greymouth, Runanga, Blackball, Cobden and settlements along the Grey River. It has a land area of 3,474.44 square kilometres (1,341.49 sq mi). The seat of the Grey District Council, the local government authority that administers the district, is at Greymouth, where 58.9% of the district's population live.
Thomas Brunner was an English-born surveyor and explorer remembered for his exploration of the West Coast of New Zealand's South Island.
Lake Poerua is a shallow lake located in the West Coast region of New Zealand's South Island roughly 13 km southeast from Lake Brunner. It is located between the Alexander Range and the slopes of Mount Te Kinga, to the north of the lake. The area around Lake Poerua is sparsely populated. A number of small streams flow into the lake, and the Poerua River flows from the lake into the Crooked River, which leads to Lake Brunner.
Lake Mahinapua is a shallow lake on the West Coast of New Zealand's South Island. Once a lagoon at the mouth of the Hokitika River, it became a lake when the river shifted its course. Lake Māhinapua was the site of a significant battle between Ngāi Tahu and Ngāti Wairangi Māori, and is regarded by them as a sacred site where swimming and fishing are prohibited. In European times it was part of an inland waterway that carried timber and settlers between Hokitika and Ross until the building of the railway. Today it is protected as a scenic reserve for boating, camping, and hiking.
Stillwater is a town in the South Island of New Zealand east of Greymouth on the banks of the Grey River, at the confluence with the Arnold River, in the Grey District of the West Coast, next to Brunner. There is also Stillwater, Auckland in the North Island.
Moana is a small town in the West Coast Region of the South Island of New Zealand. It is situated on the northern shore of Lake Brunner, and is beside the outflow of the lake into the Arnold River. There is a pedestrian suspension bridge crossing the Arnold from the town to access the lake shore across the river, with some short easy bush walks on each side.
Ngāti Ranginui is a Māori iwi (tribe) in Bay of Plenty, New Zealand. Its rohe extends from Waihi in the north, to the Kaimai Range in the west, to south of Te Puke in the south, and to Tauranga in the east. The rohe does not extend offshore to Matakana Island or Mayor Island / Tuhua.
Lake Rotoiti, previously also known as Lake Arthur, is a lake in the Tasman Region of New Zealand. It is a substantial mountain lake within the borders of Nelson Lakes National Park. The lake is fed by the Travers River, water from the lake flows into the Buller River. The lake is surrounded by beech forest and is 82 metres (269 ft) deep. Saint Arnaud is a small community at the northern end of the lake.
The Arahura River, for a time called the Brunner River after the explorer Thomas Brunner, is a river located on the West Coast of the South Island of New Zealand.
The Arnold Power Station is a hydroelectric facility fed from Lake Brunner on the Arnold River in West Coast, New Zealand, owned and operated by TrustPower. Commissioned in 1932, the plant is rated at 3 megawatts (4,000 hp) and has an average annual output of 25 gigawatt-hours (90 TJ).
The Ōrangipuku River is a river of the West Coast Region of New Zealand's South Island. It flows north into the southern end of Lake Brunner.
Bell Hill mill tramway was a bush tramway at Bell Hill in the Moana Region of the Grey District on the West Coast of New Zealand. The tramway with a track gauge of 3 ft 6 in was used in the 1910s.
Ngāti Tūmatakōkiri is a Māori iwi (tribe) of New Zealand, who arrived on the Kurahaupō waka. In the 1600s the iwi settled northwestern South Island, becoming a major power in the region until the 1800s. In 1642, members of Ngāti Tūmatakōkiri made the first known contact between Europeans and Māori, when Dutch explorer Abel Tasman visited Golden Bay / Mohua.
Coordinates: 42°26′S171°22′E / 42.433°S 171.367°E