Lake Onslow
{{redirect|Onslow PHS||Pumped-storage hydroelectricity}}
{{Use New Zealand English|date=April 2024}}
{{Use dmy dates|date=July 2019}}
{{Infobox body of water
| name = Lake Onslow
| image = Lake Onslow, Central Otago.jpg
| alt = Lake Onslow In May 2014
| caption = Lake Onslow In May 2014
| image_bathymetry =
| caption_bathymetry =
| location = Otago, South Island
| coords = {{coord|45|33|S|169|37|E|region:NZ_type:waterbody_source:GNS-enwiki|display=inline,title}}
| type = reservoir
| inflow = Teviot River
|pushpin_map=New Zealand Otago peninsula
| pushpin_map_alt = Location of Lake Onslow
| outflow = Teviot River
| catchment =
| basin_countries = New Zealand
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| elevation = {{convert|700|m|ft|abbr=on}}
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Lake Onslow is a man-made lake east of Roxburgh and south of Alexandra in the Otago region of New Zealand. It lies {{cvt|700|m}} above sea level. It was formed in 1890 by the damming of the Teviot River and Dismal Swamp, with a new dam built in 1982 that raised the lake level by {{cvt|5|m}}. It has been considered as the site for a pumped-storage hydroelectricity project.
History
Lake Onslow first formed in 1890 when a dam was built that flooded the Dismal Swamp; the Teviot River flowed through the swamp. The water from this lake was used for mining, irrigation and hydroelectricity. In 1982, a new and higher dam was built that raised the lake level by {{cvt|5|m}}; the old dam is now drowned.{{cite web |title=Our history |url=https://pioneerenergy.co.nz/our-history/#section13 |publisher=Pioneer Energy |access-date=16 May 2022}} The water usage rights jointly sit with Pioneer Energy (formerly the Otago Central Electric Power Board) and the Teviot Irrigation Company.{{cite news |last1=Morgan |first1=Jared |title=Lake Onslow project: area has seesawing history |url=https://www.odt.co.nz/regions/central-otago/lake-onslow-project-area-has-seesawing-history |access-date=16 May 2022 |work=Otago Daily Times |date=1 August 2020}}
In 2019, the Interim Climate Change Committee proposed that the lake be used for a pumped hydro-storage system to provide backup electricity generation in dry years. The project had first been considered by hydrologist Earl Bardsley of the University of Waikato since 2002 and proposed in 2005.{{cite news |last1=O'Connor |first1=Rose |title=Pumped storage: A game-changer for New Zealand's electricity needs? |url= https://www.stuff.co.nz/otago/128651393/pumped-storage-a-gamechanger-for-new-zealands-electricity-needs |access-date=16 May 2022 |work=Stuff |date=16 May 2022}}{{cite web |url= https://www.iccc.mfe.govt.nz/assets/PDF_Library/daed426432/FINAL-ICCC-Electricity-report.pdf |title=Accelerated electrification: Evidence, analysis and recommendations |publisher=Interim Climate Change Committee |pages=67–68 |date=30 April 2019 |accessdate=16 July 2019}}{{cite news |last1=Jones |first1=Pam |title=Massive hydro storage plan to be reassessed |url=https://www.odt.co.nz/regions/central-otago/massive-hydro-storage-plan-be-reassessed |accessdate=18 September 2019 |work=Otago Daily Times |date=18 September 2019}} In July 2020, Minister of Energy Megan Woods announced that the New Zealand government would fund a detailed feasibility study of the plan.{{cite news |url= https://www.odt.co.nz/regions/central-otago/central-otago-hydro-project-could-be-game-changer |title=Central Otago hydro project could be 'game changer' |publisher=Otago Daily Times |date=26 July 2020 |accessdate=26 July 2020}} If progressed, the scheme would be the biggest infrastructure project in New Zealand since the 1980s, employ an estimated 3500 to 4500 people, and take four to five years to build and a further two years to fill.{{cite news |url= https://www.stuff.co.nz/national/300066128/government-wants-100-per-cent-green-electricity-by-adding-battery-power-to-hydro-power |title=Government wants 100 per cent green electricity by adding 'battery' power to hydro power |author=Thomas Coughlan |publisher=Stuff |date=26 July 2020 |accessdate=26 July 2020}} One option could be 5 TWh of storage and a 1.2 GW power station, equivalent to half a year of full production.{{cite web |title=Does New Zealand's plan for a nation-sized battery hold water? |url=https://reneweconomy.com.au/does-new-zealands-plan-for-a-nation-sized-battery-hold-water-11911/ |website=RenewEconomy |language=en-AU |date=15 October 2020}}
If the project goes ahead it will completely drown and submerge a small scroll plain with its swirling and migrating meanders (formerly known as Dismal Swamp). The scroll plain is a miniature example of the nearby Taieri Scroll Plains{{cite web |title=Upper Taieri Wetlands Complex |url=https://www.orc.govt.nz/managing-our-environment/water/wetlands-and-estuaries/central-otago-district/upper-taieri-wetlands-complex |publisher=Otago Regional Council |access-date=16 May 2022 |date=12 April 2022}} and has formed because of the low and decreasing gradient of the stream valley due to slow progressive tectonic back-tilting of the catchment.{{cite journal |last1=Hayward |first1=Bruce W |author1-link=Bruce Hayward |title=Lake Onslow's small scroll plain, Otago |journal=Geoscience Society of New Zealand Newsletter |date=March 2022 |issue=36 |pages=22–25 |url= https://www.researchgate.net/publication/359056158}}
In March 2023, the government estimated the cost of the storage project at $15.7 billion.{{cite web |url=https://www.newsroom.co.nz/lake-onslow-scheme-to-cost-157-billion |title=Lake Onslow scheme to cost $15.7 billion |publisher=Newsroom |author=Marc Daalder |date=16 March 2023 |access-date=16 March 2023}}
In December 2023, the Energy Minister in the new National-led government, Simeon Brown, announced the axing of the pumped hydro scheme, saying, "This hugely wasteful project was pouring money down the drain at a time when we need to be reining in spending and focussing on rebuilding the economy and improving the lives of New Zealanders".{{Cite web |date=3 December 2023 |title=Govt confirms it is dumping 'hugely wasteful' Lake Onslow battery project |url=https://www.rnz.co.nz/news/national/503816/govt-confirms-it-is-dumping-hugely-wasteful-lake-onslow-battery-project |access-date=4 December 2023 |website=RNZ }}
Climate
{{Weather box|width=auto
|metric first=y
|single line=y
|collapsed = Y
|location = Manorburn Dam{{efn|Manorburn Dam is located approximately {{convert|20|km|1|abbr=out}} north of Lake Onslow.}}, elevation {{convert|746|m|ft|abbr=on}}, (1951–1980 normals, extremes 1928–1977)
| Jan record high C = 29.7
| Feb record high C = 33.9
| Mar record high C = 26.7
| Apr record high C = 23.3
| May record high C = 16.9
| Jun record high C = 14.4
| Jul record high C = 12.3
| Aug record high C = 17.8
| Sep record high C = 20.0
| Oct record high C = 25.3
| Nov record high C = 25.8
| Dec record high C = 26.7
| year record high C = 33.9
|Jan high C = 18.9
|Feb high C = 18.9
|Mar high C = 16.6
|Apr high C = 12.9
|May high C = 8.3
|Jun high C = 5.3
|Jul high C = 4.1
|Aug high C = 6.6
|Sep high C = 10.1
|Oct high C = 12.7
|Nov high C = 15.0
|Dec high C = 17.2
| year high C =
|Jan mean C = 12.4
|Feb mean C = 12.5
|Mar mean C = 10.7
|Apr mean C = 7.5
|May mean C = 3.7
|Jun mean C = 0.9
|Jul mean C = -0.5
|Aug mean C = 1.7
|Sep mean C = 4.8
|Oct mean C = 7.1
|Nov mean C = 9.0
|Dec mean C = 11.1
| year mean C =
|Jan low C = 5.9
|Feb low C = 6.0
|Mar low C = 4.7
|Apr low C = 2.1
|May low C = -0.9
|Jun low C = -3.5
|Jul low C = -5.1
|Aug low C = -3.3
|Sep low C = -0.6
|Oct low C = 1.5
|Nov low C = 2.9
|Dec low C = 5.0
| year low C =
|Jan record low C = -2.8
|Feb record low C = -2.5
|Mar record low C = -4.7
|Apr record low C = -6.0
|May record low C = -10.6
|Jun record low C = -15.6
|Jul record low C = -16.9
|Aug record low C = -18.6
|Sep record low C = -9.4
|Oct record low C = -6.1
|Nov record low C = -5.7
|Dec record low C = -4.6
|year record low C = -18.6
|rain colour = green
|Jan rain mm = 56
|Feb rain mm = 39
|Mar rain mm = 53
|Apr rain mm = 45
|May rain mm = 46
|Jun rain mm = 34
|Jul rain mm = 25
|Aug rain mm = 23
|Sep rain mm = 31
|Oct rain mm = 42
|Nov rain mm = 46
|Dec rain mm = 52
|year rain mm =
{{cite web
|url = http://cliflo.niwa.co.nz
|title = CliFlo – National Climate Database : Manorburn Dam
|publisher = NIWA
|access-date = 19 May 2024}}{{cite web
|url = https://cliflo.niwa.co.nz/
|title = CliFlo -The National Climate Database (Agent number:5608)
|publisher = NIWA
|access-date = 15 May 2024}}
}}
Notes
{{notelist}}
References
{{reflist}}
External links
- [https://newzealand.water.blog/ Onslow Pumped Storage – Earl Bardsley] ({{webarchive |url=https://archive.today/20210811232153/https://newzealand.water.blog/ |date=12 August 2021}})
{{DEFAULTSORT:Onslow, Lake}}
Category:Proposed renewable energy power stations in New Zealand
Category:Proposed pumped-storage hydroelectric power stations