Blue Lake (Tasman)
{{Short description|Lake in New Zealand}}
{{Use dmy dates|date=January 2024}}
{{Use New Zealand English|date=January 2024}}
{{Infobox body of water
| name = Rotomairewhenua
| other_name = Blue Lake
| image = Blue lake Nelson New Zealand.jpg
| alt = Blue lake
| caption = Blue lake
| image_bathymetry =
| caption_bathymetry =
| location = Tasman Region, South Island
| image_map ={{Infobox mapframe |zoom=12|point=none|shape-fill-opacity=0|stroke-width=1|stroke-color=#0000ff}}
| pushpin_map = New Zealand South Island
| pushpin_map_alt = Location of Blue Lake
| coords = {{coord|42|3|30.6|S|172|39|25.6|E|type:waterbody_region:NZ|display=inline,title}}
| type =
| inflow = springs{{cite journal |last1=Gall |first1=Mark P. |last2=Davies-Colley |first2=Rob J. |last3=Merrilees |first3=Rob A. |year=2013 |title=Exceptional visual clarity and optical purity in a sub-alpine lake |journal=Limnology and Oceanography |volume=58 |issue=2 |pages=443–451 |doi=10.4319/lo.2013.58.2.0443 |doi-access= }}
| outflow = West Branch of the Sabine River
| catchment =
| basin_countries = New Zealand
| length =
| width =
| area = {{convert|2.45|ha|acre|abbr=on}}
| depth = {{convert|7|m|ft|abbr=on}}
| max-depth = {{convert|8.5|m|ft|abbr=on}}
| volume = {{convert|180000|m3|abbr=on}}
| shore =
| elevation = {{convert|1180|m|ft|abbr=on}}
| islands =
| cities =
}}
Rotomairewhenua / Blue Lake is a small lake in Nelson Lakes National Park, in the northern reaches of New Zealand's Southern Alps. Sacred to local Māori, it has the clearest natural fresh water in the world.
Description
The Blue Lake is drained by the west branch of the Sabine River, which is part of the Buller River system. It is fed by a short upper segment of the Sabine, which in turn is fed by underground seepage through the landslide debris impounding the much larger Lake Constance. Blue Lake is roughly boomerang shaped, running north then northwest, with each arm of the lake stretching some {{convert|200|m|ft|-2}}.{{cite web|title=Blue Lake|url=http://maps.google.co.nz/maps/ms?ie=UTF8&t=m&vpsrc=6&source=embed&oe=UTF8&msa=0&msid=200785319996428123531.0004b477c51e07b783a44|work=Google Maps|accessdate=24 December 2011}} Its waters are cold, ranging from {{convert|5|to|8|C|F}}.
=Clarity=
The lake has extremely clear water, and is the clearest natural body of fresh water yet reported.{{cite news|title=Nelson's Blue Lake clearest|url=http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10774272|accessdate=20 December 2011|newspaper=New Zealand Herald|date=20 December 2011}} A 2011 study found its visibility ranged from {{convert|70|to|80|m|ft}}, clearer than the {{convert|63|m|ft}} measured for Te Waikoropupu Springs, a previous record holder. For comparison, laboratory measurements show distilled water has a visibility of approximately {{convert|80|m|ft}}. Scientists attribute the lake water's clarity to its passage underground from Lake Constance, which filters out nearly all the particles suspended in the water. Its clarity reveals water's natural blue-violet colour.{{cite web|title=Nelson's Blue Lake – The clearest freshwater ever reported|url=http://www.niwa.co.nz/news/nelson%E2%80%99s-blue-lake-%E2%80%93-the-clearest-freshwater-ever-reported|publisher=NIWA|accessdate=20 December 2011}}
Facilities and access
Blue Lake is most often reached as a side trip from the Travers-Sabine Circuit, although a marked route to the south, over the Waiau Pass and another to the West, via Moss Pass continues beyond the lake. The nearby Blue Lake Hut, with 16 bunks, provides accommodation for more than 700 trampers each year.{{cite web |title=Blue Lake Hut |url=https://www.doc.govt.nz/parks-and-recreation/places-to-go/nelson-tasman/places/nelson-lakes-national-park/things-to-do/huts/blue-lake-hut/ |publisher=Department of Conservation |accessdate=31 August 2021}}
Māori history
Blue Lake lies within the rohe (tribal area) of Ngāti Apa ki te Rā Tō. As part of the iwi's 2010 treaty settlement, the lake passed into tribal ownership and was then given back to the Crown. The lake was traditionally used in ceremonies to cleanse the bones and release the spirits of the dead, so they could begin their journey to Hawaiki, and the iwi regard its waters as tapu (sacred). (Blue Lake was used only for males; Lake Constance was used for females.) Its Māori name, Rotomairewhenua, means "the lake of peaceful lands".
In August 2014, the official name for Blue Lake was altered to Rotomairewhenua / Blue Lake, following the Ngāti Apa ki te Rā Tō treaty settlement with the Crown.{{cite web|url=http://www.linz.govt.nz/regulatory/place-names/recent-place-name-decisions-and-place-names-interest/nzgb-decisions-august |title=NZGB decisions – August 2014 |date=August 2014 |website= |publisher=Land Information New Zealand |accessdate=27 October 2015 |url-status=dead |archive-url=https://web.archive.org/web/20151121203027/http://www.linz.govt.nz/regulatory/place-names/recent-place-name-decisions-and-place-names-interest/nzgb-decisions-august |archive-date=21 November 2015 }}
References
{{Reflist}}
{{Nelson Lakes National Park}}
{{Tasman District}}