The Māori name ‘Rangitata’ (Rakitata) has been variously translated as ‘day of lowering clouds’, ‘close sky’, and ‘the side of the sky’. With a catchment area (click for interactive map) of 1,773 km2, the Rangitata River begins its journey from the Southern Alps at the confluence of the Clyde and Havelock Rivers, a region made famous because of its location of Edoras and Helm’s Deep in Lord of the Rings.
Before the Rangitata River enters the Canterbury Plains, part of it is diverted to the Rangitata Diversion Race (RDR) for irrigation and hydroelectric generation. Built between 1937 and 1944, the RDR supplies water to the Montalto and Highbank schemes before joining the Rakaia River. The Rangitata River passes through the Rangitata Gorge in the Alpine foothills, and flows southeast for 121km before entering Canterbury Bight 64km northeast of Timaru.
Towards its mouth, the river splits into two streams, forming the large (17km x 5km) lens-shaped delta island, Rangitata Island.
Biodiversity & cultural significance
The Rangitata River is the border between two zone committees with two different Zone Implementation Programmes (ZIPs): Ashburton and Orari-Opihi.
Download the October 2019 report for DOC: Rangitata Catchment Values
Extract from the Ashburton Zone Implementation Program: ‘Water is precious and limited. It must be managed in ways that recognise and balance its importance for cultural, economic and recreational use, aesthetic and landscape values and biodiversity values – and delivers both individual and community good. We affirm and recognise tangata whenua and the value they place on mahinga kai, and the priority of available high quality sources of drinking water in rivers, waterways and aquifers. We also recognise the intrinsic value of aquatic ecosystems and river health (quality and flow), and the need to both prevent further decline and then restore wetlands and waterways. We know that to achieve all the targets of the CWMS within our zone it is necessary to strategically manage the water within our zone and provide opportunities to bring more water into the zone.’
Extract from the Orari-Opihi Zone Implementation Programme (ZIP): ‘The upper reaches of the Rakaia and Rangitata represent relatively weed free glacier fed catchments in almost pristine condition. Throughout their catchments, these rivers have outstanding fishery and habitat values… The Rangitata…provides outstanding habitat for many rare birds, fish, plants and other species, as well as a wide range of recreational values.’
Important Bird Areas on the Rangitata River: links to 6-page PDF file that includes maps, habitat types, and threats relevant to this river. This document was extracted from Forest & Bird’s 177-page 20Mb file on all rivers, lakes, and coastal areas.
Hakatere Conservation Park straddles sections of the upper Rakaia and Rangitata Rivers, is part of one of the best wetlands in the country. A national wetland restoration project was started in 1997 and involves three premier sites: Whangamarino in Waikato, Awarua/Waituna in Southland and Ō Tū Wharekai here in Canterbury. The rivers, lakes, tarns and swamps of Ō Tū Wharekai have their own special range of species; some of which are rare, for example our kettle holes are home to 23 threatened plants. Although each wetland habitat is unique, all waterways are interconnected, breathing life into the Hakatere basin.
The Rangitata River is one of ECan’s flagship biodiversity programmes.
The Implementation Strategy for the Braided River Flagship Programme – Upper Rakaia and Rangitata Rivers (2011), outlines the initiatives for both rivers.
- 2020: Upper Rangitata Trapping Report (DOC)
- 2019: Major study of Rangitata River (Timaru Herald article)
- 2019: Presentation at the Braided Rivers Seminar on details and current outcomes of the project
- 2018: Rakaia /Rangitata River Weed Control Strategy 5-Year Review (30Mb PDF)
- 2017: DOC Newsletter including updates of work and outcomes
- 2016/17: DOC report on wrybill and black-fronted tern nesting success
- 2016: DOC Upper Rangitata predator control programme and results
- 2016: Site assessment for the possible reintroduction of kaki/black stilt (BRaid workshop)
- 2013: Upper Rakaia Riverbed Weed Control Strategy
Water flow & floods
The December 2019 flood peaked at 2270 cumecs, with a catchment rainfall of 875mm extending over seven days. This flood had an extreme total volume, estimated to be a 1 in 40 year event. As the flood was well beyond the design capacity of infrastructure, the outcome was, unexpectedly, considerable and very costly.
This highlights a key problem that river manager are now facing. NIWA has forescast more frequent and larger floods as the climate change. All the research points to rivers being given more ‘room to move’ to accommodate these future floods. And yet the High Court has ruled that the legal width of a braided river is significantly less than previously defined.
References & research material
- 2019: DOC; Rangitata River Catchment Values
- ECan document library: enter ‘Rangitata River’ in the ‘keywords‘ search field
- DOC catalogue of scientific publications: enter the relevant search terms in the ‘search’ dialogue box. You may need to vary your search, for example ‘black stilt’ gives far more results than ‘kaki’ or ‘kakī’
- See Rivers for a more comprehesive list of braided rivers research and reference material