Upper Rangitata River

Image: DOC


Conservation efforts in Ō Tū Wharekai are focused on predator control, weed control, monitoring, and improving water quality.


Our vision: That the intrinsic values of one of the best remaining high-country freshwater wetland and braided river ecosystems are protected, enhanced and appreciated.

Ō Tū Wharekai is a nationally important inter-montane wetland, lake and braided river site that has outstanding biodiversity values and high cultural significance to Ngāi Tahu.

Conservation efforts in Ō Tū Wharekai are focused on protecting braided river birds through predator control, restoring ecosystems by large-scale weed control, improving water quality of the Ashburton lakes and streams, and monitoring the status of threatened plant and animal species that rely on the site. We also support community trapping initiatives to protect wetland birds from predators.

Key projects

Braided river bird recovery

AK objective: Enhance species diversity and protect threatened species
Site target: Increasing nesting success of wrybill and other threatened braided river birds

The rare and dynamic braided river environment provides habitat for a range of threatened bird species like wrybill, kakī/black stilt and black-fronted tern. Protecting these birds and enhancing their habitat through advocacy and weed and predator control is a key part of our conservation efforts.

We’re reducing nest predation rates through predator control - black-fronted tern nest predation drops to 38%, compared to 96% outside the control area.

Our monitoring programme has shown that nationally critical kakī are nesting in the Upper Rangitata River, and we have successfully banded kakī chicks

Ashburton Lakes ecosystem health

AK objective: Maintain or enhance water regime and water quality
Site target:
Tropic status (TLI) of Lake Heron is <2 TLI; and for (all other Ashburton lakes is <3 TLI

Water quality and ecosystem health vary between the lakes – some are close to pristine, while others are in poor condition. Our research has focused on monitoring water quality and native aquatic plant communities. Aquatic plants provide habitat for aquatic life, regulate water quality by absorbing nutrients and binding sediment, and are a useful indicator of lake health.

We are working with Environment Canterbury, iwi and landowners to improve management regimes and reduce sediment and nutrient loads entering the lakes.

Threatened plant recovery (Craspedia)

AK objective: Enhance species diversity and protect threatened species
Site target: Increasing population of Craspedia heron

The critically endangered Craspedia (heron) only grows near Lake Heron. To ensure the survival of this incredibly rare plant species we are monitoring the existing population on Cameron Fan, as well as collecting seed so the DOC nursery can store and grow plants which can then be translocated to Lake Heron. Trial plantings at different sites around the lake are underway.  

Weed control

AK objective: Enhance species diversity and protect threatened species.
Site target: Grey willow, crack willow, broom and lupin are managed at low levels.

Invasive plant species put pressure on threatened native plants and ecosystems. We are using aerial and ground control methods to manage woody and ground-cover weeds across 12,000 ha of wetlands, riparian habitats and the Upper Rangitata River. Removing weeds will enable recovery of native vegetation and enhance landscape values.

Kettlehole wetland protection

AK objective: Protect or restore ecosystem condition
Site target: All kettleholes on conservation land are protected and retain high plant diversity dominated by native vegetation

Seasonally wet kettleholes support rare ephemeral turf vegetation. To protect these native turf communities and other threatened plant species we are controlling rabbit populations to a low level and managing weeds around the kettleholes.

Skink monitoring

AK objective: Enhance species diversity and protect threatened species
Site target: A long-term conservation plan for threatened skinks is prepared by 2020

A 10-year study on the Nationally Vulnerable scree skink was completed in 2018 which identified population trends, habitat range and threats, and showed that the skinks are highly vulnerable to mammalian predators and flood events. Based on this knowledge we aim to develop and implement a plan for securing scree skink populations. 

Report cards

Science publications

See all our publications in the Arawai Kākāriki science bibliography.

Key partners

Working in partnership with organisations and communities to share knowledge is an intrinsic element of Arawai Kākāriki.

Key partners involved with Ō Tū Wharekai:

  • Te Rūnanga o Arowhenua
  • Environment Canterbury
  • Fish and Game New Zealand
  • Ashburton District Council
  • Forest and Bird
  • Rangitata Landcare Group
  • Land Information New Zealand
  • Cawthron Institute
  • Lake Clearwater bach owners
  • Landowners
  • Recreational groups

Get involved

Volunteer groups involved in Ō Tū Wharekai:

  • Forest and Bird – Ashburton Branch (weed control, annual winter bird counts)
  • Māori Lakes volunteer trapping group (predator control)
  • Lake Heron volunteer trapping group (predator control)
  • Lake Clearwater Hut Holders Association

Find other DOC volunteering activities


Raukapuka / Geraldine Office
Phone:   +64 3 693 1010
Email:   esienquiries@doc.govt.nz
Address:   13 – 15 North Terrace
Geraldine 7930
Postal Address:   PO Box 33
Geraldine 7956
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