Lake Huro
Lake on Chatham Island, New Zealand
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Lake Huro is a coastal dune lake on Chatham Island, New Zealand, southwest of Te Whanga Lagoon and close to the settlement of Waitangi. Hosting many waterfowl and a population of New Zealand smelt, the lake has very poor water quality, with green and cloudy water, and poses a potential toxic hazard due to its outflow through Mangapē Creek to the Nairn River and Waitangi.
| Lake Huro | |
|---|---|
View of Lake Huro, showing a Myriophyllum growth | |
| Location | Chatham Island, New Zealand |
| Coordinates | 43°56′S 176°31′W |
| Primary outflows | Mangapē Creek |
| Surface area | 598 ha (1,480 acres) |
| Max. depth | 0.3 m (0.98 ft) |
 Interactive map of Lake Huro | |
Description
Lake Huro is a coastal dune lake on Chatham Island, New Zealand, located on a strip of land between the Te Whanga Lagoon and the settlement of Waitangi. It covers an area of around 598 hectares (1,480 acres), but with a maximum depth of only 0.3 m (1 ft).[1][2]
The lake's sediment mostly consists of sand, with a crust of peat along its shores. The water is green and turbid, stained by the peat. The water visibility was measured in 2004 as just 0.1 metres (0.33 ft),[3][2] although the growth of Myriophyllum (water milfoil) plants in the lake may have led to some increases.[4] Mangapē Creek drains the lake, running through an area of farmland into the Nairn River (also known as Mangatukurewa Creek) south of Waitangi.[5][6] The surrounding land is mainly used for livestock grazing, with animals given direct access to the lake.[3] It has similar water characteristics to other coastal dune lakes on Chatham, especially the nearby Tennants Lake and Lake Rangitai.[7]
The lake's water degraded during the early 2020s to hypertrophic, the lowest possible water quality level according to the New Zealand trophic level index.[1][8] It has moderate levels of phosphorus and ammoniacal nitrogen, but severely high amounts of nitrogen and algae.[9][4] In a 2022 survey, Huro was the only one of the island's lakes where Chlorophyll a levels were not found to have increased.[4] The lake's poor water quality poses a risk to nearby settlements, as Mangapē Creek and Mangatukurewa Creek drain into a well populated waterfront area in Waitangi. Potential blooms of toxic cyanobacteria could endanger nearby livestock, wildlife, shellfish, and local residents.[10]
Flora and fauna
Lake Huro hosts a significant population of waterfowl, such as the introduced black swans.[3][11] It hosts a large population of New Zealand smelt, alongside small numbers of redfin bullies (a species of goby).[12] In 1949, smelt from the lake (alongside samples from nearby Tennants Lake and Lake Marakapia) were described as a separate species from New Zealand smelt, R. chathamensis; this was later synonymised with Retropinna retropinna, New Zealand smelt. Lake Huro seems to have a genetically distinct population of smelt compared to Lake Marakpia and Tennants Lake.[13] A species of the algae Lamprothamnium grows in the lake.[14]