Жаңа Зеландиядағы Бруннер көлі

Lake in the South Island of New Zealand

Lake Brunner ( or Kōtukuwhakaoka) is the largest lake in the West Coast Region of New Zealand, located southeast of Greymouth. 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.

Lake Brunner is the largest lake in the West Coast region, across with an area of 4061 ha, just over The outlet of the lake is the Arnold River, a tributary of the Grey River / Māwheranui, next to the largest settlement of Moana, on the north shore of the lake. The largest rivers feeding into Lake Brunner are the Crooked River from the east, the Orangipuku River and Bruce Creek from the south at Swan Bay, and the Eastern Hohonu River from the west at Hohonu Spit. Lake Brunner was created in the last ice age by a spur of the Taramakau Glacier, which split from the main glacier and flowed north either side of Mount Te Kinga, between it and the Hohonu Range. Both these prominent mountains are made of erosion resistant granite and granodiorite, cooled magma 100–145 million years old. When the glacier receded about 11,000 years ago, it left behind moraines which impeded the flow of rivers to the sea and filled the gouged out glacial valley; the large blocks of rock it dropped, known as glacial erratics, can still be found in the surrounding bush. At this point, the lake would have been larger and deeper than today, with several outflows, but the Arnold River eventually became the main one, cutting through the moraine ridges to drain the lake to its present level. The same process of moraine deposition and glacial retreat created nearby Kangaroo Lake, Lady Lake, and Lake Haupiri. The lake is large enough that it can be subject to severe weather, including a powerful easterly wind known as the "Brucer", which blows up the valley from Inchbonnie, once belonging to Thomas Bruce (1831–1908) who began farming there in 1872. The soils in its catchment are derived from greywacke, granite, and schist, and are low in nutrients, but unlike many other West Coast glacial lake, Lake Brunner has significant alluvial soils on its margin.

Although the Māori name for the lake is often given as just "Moana", two names for the lake are recorded. The first, Kōtuku moana, translates as "sea of herons", referencing the white heron (Ardea alba modesta), known to Māori as kōtuku. In New Zealand kōtuku have a population of roughly 200 at any one time, breeding only at Ōkārito on the West Coast, and are symbols of beauty and rarity in Māori culture. The second name, Kōtukuwhakaoka, is shared with the Arnold River, and is the name of a Māori chief from the North Island who came upon the lake after following the river upstream. According to legend, the chief was attacked and killed by a taniwha which lived in the lake, which later became one of the two islands in the lake after it was killed by the chief's son. The name was variously rendered as Kotukuwakaho and Kotuku kaoka; Brunner spelled it "Kotu urakaoka" in the proclamation that in 1853 defined the boundaries of the province. The English name "Lake Brunner" was chosen by John Rochfort to honour the 19th century explorer Thomas Brunner, who was the first European to visit the lake. numerous subsequent searches turned up only his tent and some eel lines at the lake shore. United Mills operated in Te Kinga, using timber felled in a logging camp across the lake at Bain Bay. Initially they were transported across the lake by the Tiki, a steam launch, and from 1938 to 1963 by the Tikinui, which towed a punt onto which logs that would not float were fastened. When a "Brucer" blew, waves were so high they would break over the Tikinui's wheelhouse (8 feet above lake level); the boat would cast loose its punt and logs and make for shelter, returning to retrieve any floating logs the next day. Logs that had sunk to the lake floor a century ago remained perfectly preserved, with axe marks still visible.

Lake Brunner is notable in being surrounded by intact native forest, although the flats have been extensively logged while kahikatea (Dacrycarpus dacrydioides) swamp forest is found at many points along the lake shore. Kahikatea is able to tolerate submergence of its roots, and when lake levels are high it is possible to travel by kayak through forests of 30 m trees, one of the few places on the West Coast where this is easily done. The lakeside kahikatea and flax (Phormium tenax) community includes small leaved divaricating shrubs like mingimingi and Coprosma rhamnoides, and the trees rimu and kamahi. There are also small numbers of rainbow trout (Oncorhynchus mykiss). Rainbow trout originate in North America, and brown trout are a European game fish introduced throughout New Zealand following the establishment of a hatchery in Tasmania in the 1860s. In 1891, 15,000 young trout were transported from Greymouth by rail to stock the lake. Smelt (Retropinna retropinna) were also liberated in Lake Brunner to serve as food for trout, but did not establish.

The lake was early on recognised for its natural beauty, and in 1887 a tourist account celebrated the impending railway, and the lake "soon will be dotted with handsome villas, the summer residence of the aristocracy of Greymouth and the surrounding districts." Sailing was a popular early activity, and in 1892 the first regatta attracted a trainload of 350 sightseers. The growth of tourism led to the opening in 1931 of the 22 room Grand Chateau Moana, which went bankrupt the following year. A motor camp was built in 1959 in Moana, and a jetty, slipway, and car park in 1961. In the 1960s building a holiday home or "bach" at Moana or Iveagh Bay became popular with Christchurch or Greymouth families. There are boat launching ramps at Moana, Te Kinga (with lake access at Cashmere Bay), and Mitchells. Iveagh Bay was once a backwater, but has rapidly increasing numbers of expensive holiday mansions. and the short Valenski Walk and Rakaitane Track from Moana.

Lake Brunner is recognised for its ecological value and importance to the tangata whenua, to tourism and to fisheries. The lake is classified as oligotrophic, meaning that it has naturally low levels of nutrients, low levels of algae and the water is of high quality. Regular monitoring of water quality in Lake Brunner began in the early 1990s. A report in 2006 identified declining water quality, and this was followed in 2010 by an update describing increasing nutrient levels in surface water, increasing chlorophyll (an indicator of biomass of algae), and a decrease in water clarity. The report suggested that intensification of agriculture in the catchment area could be the cause of the deterioration. There are 25 dairy farms in the catchment area of Lake Brunner. Dairy farmers responded to the concerns about deteriorating water quality by investing in riparian planting, improved fencing of waterways and bridging of streams on their properties. Many also invested in improved effluent treatment systems. By 2021, it was reported that of fencing had been constructed on farms in the catchment along with 21,000 plants in riparian strips. Water quality updates are published periodically by the West Coast Regional Council. The December 2021 update reports that the lake is safe for swimming and recreation, and has remained in an oligotrophic (low nutrient) state. The levels of phosphorus are graded A on the National Objectives Framework issued under the National Policy Statement for Freshwater Management, and are sufficiently low that growth of algae is inhibited. Levels of total nitrogen and lakebed dissolved oxygen are graded B on the same scale.