{{Short description|River in New Zealand}} {{Use New Zealand English|date=April 2024}} {{Use dmy dates|date=October 2021}} {{Infobox river | name = Selwyn River | native_name ={{native name|mi|Waikirikiri}} | name_other = Selwyn River / Waikirikiri | name_etymology = Translates as "gravelly water", and named after Bishop Selwyn. | nickname = | image = | image_size = | image_caption = Selwyn River near Dunsandel, November 2017 | source1_location = Southern Alps | mouth_location = Lake Ellesmere / Te Waihora | subdivision_type1 = Country | subdivision_name1 = New Zealand | length = {{convert|80|km|mi|abbr=on}} | source1_elevation = | mouth_elevation = | discharge1_avg = | basin_size = | river_system = | tributaries_left = | tributaries_right = | pushpin_map = New Zealand | pushpin_map_caption= Location of the mouth within New Zealand }}
The '''Selwyn River''' ({{Langx|mi|'''Waikirikiri'''}}, officially gazetted as '''Selwyn River / Waikirikiri''') flows through the Selwyn District of Canterbury in the South Island of New Zealand.<ref>{{LINZ|125774|Selwyn River/Waikirikiri|5 April 2008}}</ref>
==Description== thumb|The River Walk, where the Wairiri Stream meets the Selwyn River (November 2019)|left left|thumb|The Selwyn River looking downstream, Harper Hills to the right and the camping ground to the left (January 2024) The river has its source in the Southern Alps and flows east for {{convert|80|km|mi}} before emptying into Lake Ellesmere / Te Waihora, south of Banks Peninsula. Terrace cliffs above the river's upper reaches gave the town of Whitecliffs its name.
For much of its course the river flows through wide shingle channels. In drought years, the river can disappear beneath this bed and seem to dry up completely. This frequently occurs where State Highway 1 crosses the river at the settlement of Selwyn, about {{convert|20|km}} upstream from its outflow into Lake Ellesmere.
In the foothills, the Selwyn flows year-round. On the plains, the riverbed is highly permeable, and the river overlays a deep and porous aquifer. As soon as the river reaches the plains, water begins leaking down through the bed and into the aquifer. In most months, all river-water disappears within {{convert|5|km|mi|0}} of leaving the foothills. The next {{convert|35|km}} of the river remains dry for most of the year, apart from a small section around the confluence with the permanently flowing Hororata River. About {{convert|15|km|mi|0}} upstream from Lake Ellesmere shallow groundwater rises back to the surface, and the Selwyn becomes permanent again.
== Bridges == There are six bridges that cross the Selwyn River. These are at: Whitecliffs (Whitecliffs Road), Glentunnel (SH 77), Coalgate (Hororata Road), Hororata (Bealey Road), Selwyn (SH 1) and Irwell (Leeston Road). It is also possible to cross at Coes Ford when the river is not in flood. Chamberlains Ford is no longer a ford. The nearby Irwell bridge provides access to the other side of the river.<ref>{{Cite web|title=Selwyn District Council|url=https://www.selwyn.govt.nz/|access-date=16 May 2021|website=Selwyn District Council|language=en}}</ref>
== Ecology == Disappearing river flows have significant ecological effects: when the river’s surface water disappears, so does the habitat for many aquatic plants and animals. In response to loss of surface water, aquatic invertebrates and fish must disperse, seek refuge in remnant aquatic habitats, or die. Aquatic plants, algae, and bacteria must form resting stages or die. The dry central reaches of the Selwyn River also constitute a significant barrier for dispersal of invertebrates and for fish migrating between Lake Ellesmere and the headwaters.<ref>{{cite web |author=Mike Scarsbrook |author2=Scott Larned |author3=Graham Fenwick |author4=Dave Kelly |title=Biodiversity in a disappearing river |url=http://www.niwa.co.nz/aquatic-biodiversity-and-biosecurity/update/issue-07-2004/biodiversity-in-a-disappearing-river |url-status=dead |publisher=NIWA |accessdate=22 March 2013 |archiveurl=https://web.archive.org/web/20130223040601/http://www.niwa.co.nz/aquatic-biodiversity-and-biosecurity/update/issue-07-2004/biodiversity-in-a-disappearing-river |archivedate=23 February 2013}}</ref>
=== Fishing === The Selwyn river was viewed historically as one of New Zealand’s best trout fisheries. In the 1960s a trout trap at Coes Ford was reported to count up to 14,000 returning spawning trout. In 2017, the numbers have declined to the stage that only dozens of trout could be counted when returning to spawn.<ref>{{Cite web|title=Welcome To The Future – Popular Family Swimming Spot Dries Up {{!}} Fish & Game NZ|url=https://fishandgame.org.nz/news/welcome-to-the-future-popular-family-swimming-spot-dries-up/|access-date=16 May 2021|website=Fish & Game|language=en-NZ}}</ref> The fish in the river have been described as low in number and the majority of the fish are quite small.<ref>{{Cite web|title=Selwyn River|url=https://nzfishing.com/north-canterbury/where-to-fish/selwyn-river/|access-date=16 May 2021|website=nzfishing.com|language=en-US}}</ref>
== Pollution == The Canterbury Regional Council (ECan) has permitted intensive dairy farming around Selwyn and it has been suggested that this has led to a deterioration in the water quality of the Selwyn river.<ref>{{Cite web|title=Nitrates in Selwyn River up 50% in 22 months, Federation of Freshwater Anglers says|url=https://www.nzherald.co.nz/nz/nitrates-in-selwyn-river-up-50-in-22-months-federation-of-freshwater-anglers-says/GKWOR7BRCHDYTKGXOSPBOKRCUI/|access-date=16 May 2021|website=The New Zealand Herald |language=en-NZ}}</ref> In May 2021, it was reported that Nitrate levels in the Selwyn River has increased by 50%.
It is no longer recommended that people go swimming in the Selwyn River. Coes Ford was once a well known swimming spot in Canterbury.<ref>{{Cite web|date=5 January 2020|title=Where we used to swim: The turning point for Canterbury's Selwyn River|url=https://www.stuff.co.nz/environment/117963750/where-we-used-to-swim-the-turning-point-for-canterburys-selwyn-river|access-date=16 May 2021|website=Stuff |language=en}}</ref><ref>{{Cite web|title=Selwyn|url=https://rivers.greens.org.nz/selwyn|access-date=16 May 2021|website=Swimmable Rivers}}</ref> The water at Coes Ford was reported to be in the worst 25% in New Zealand for total nitrate levels in 2020.<ref>{{Cite web|date=28 September 2020|title=Water quality data reveals a 'very mixed bag' for Canterbury rivers|url=https://www.stuff.co.nz/environment/122915459/water-quality-data-reveals-a-very-mixed-bag-for-canterbury-rivers|access-date=16 May 2021|website=Stuff |language=en}}</ref> The pollution at Coes Ford is thought to come from Silverstream creek, which used surrounded by many of the dairy farms in the area.<ref>{{Cite web|date=2020-01-05|title=Where we used to swim: The turning point for Canterbury's Selwyn River|url=https://www.stuff.co.nz/environment/117963750/where-we-used-to-swim-the-turning-point-for-canterburys-selwyn-river|access-date=2021-11-12|website=Stuff |language=en}}</ref>
Chamberlain's Ford which crosses the Selwyn RIver had an algal bloom health warning issued in December 2020. There were benthic cyanobacteria found in the river.<ref>{{Cite web|date=February 2, 2021|title=Health Warning Removed For Algal Bloom In The Waikirikiri/ Selwyn River At Chamberlains Ford.|url=https://www.scoop.co.nz/stories/AK2102/S00035/health-warning-removed-for-algal-bloom-in-the-waikirikiri-selwyn-river-at-chamberlains-ford.htm|access-date=16 May 2021|website=www.scoop.co.nz}}</ref> Algal Blooms of benthic cyanobacteria have also been reported at in the Selwyn river at Whitecliffs Domain and Whitecliffs Road in March 2021.<ref>{{Cite web|date=March 5, 2021|title=Health Warning Removed For Algal Bloom In The Selwyn/Waikirikiri River At Whitecliffs Domain And Whitecliffs Road |url=https://www.scoop.co.nz/stories/AK2103/S00143/health-warning-removed-for-algal-bloom-in-the-selwynwaikirikiri-river-at-whitecliffs-domain-and-whitecliffs-road.htm|access-date=16 May 2021|website=www.scoop.co.nz}}</ref>
Greenpeace placed billboards in the Selwyn River to protest the degree of pollution in it in February 2020.<ref>{{Cite web|date=13 February 2020|title=Three billboards protest pollution in Canterbury's Selwyn River|url=https://www.stuff.co.nz/environment/119484496/three-billboards-protest-pollution-in-canterburys-selwyn-river|access-date=16 May 2021|website=Stuff |language=en}}</ref>
==Naming== The Selwyn River and its gorge were named in 1849 by the chief surveyor of the Canterbury Association, Joseph Thomas, for Bishop Selwyn. The name was later adopted for the township, the district, and an electorate.<ref name="Place Names">{{cite book |last=Reed |first=A. W. |title=Place Names of New Zealand |year=2010 |publisher=Raupo |location=Rosedale, North Shore |isbn=9780143204107 |page =362 |editor=Peter Dowling}}</ref>
The New Zealand Ministry for Culture and Heritage gives a translation of "gravelly stream" for {{lang|mi|Waikirikiri}}.<ref>{{Cite web|url=https://nzhistory.govt.nz/culture/maori-language-week/1000-maori-place-names|title=1000 Māori place names|publisher=New Zealand Ministry for Culture and Heritage|date=6 August 2019}}</ref>
==References== {{Reflist}} {{Selwyn}} {{Selwyn District, New Zealand}} {{coord|43|45|S|172|26|E|display=title|region:NZ_type:river_source:GNS-enwiki}}
{{DEFAULTSORT:Selwyn River Waikirikiri}} Category:Rivers of the Canterbury Region Category:Rivers of New Zealand Category:Braided rivers in New Zealand