Local approach to target pest weeds at Waitaki lakes

Two pesky plant species – introduced by early European settlers – are the target of a co-ordinated pest control project to enhance biodiversity, water quality and mahinga kai resource gathering opportunities at Lake Ōhau and Lake Middleton.

The Ōhau Conservation Trust has been allocated $23,081 of funding as part of the Upper Waitaki Water Zone Committee's action plan, for further work to control pest plants cotoneaster and crack willows around the edges of the lakes, while improving the ecological, cultural, and recreational values of the lakes.

Ongoing control of cotoneaster

The control of cotoneaster around the shore of Lake Ōhau will continue thanks to funding from the zone committee.

The control of cotoneaster around the shore of Lake Ōhau will continue thanks to funding from the zone committee

Ōhau Conservation Trust chair Vivienne Smith-Campbell said that the trust, along with Environment Canterbury and the Department of Conservation (DOC) has been working on removing cotoneaster from Lake Ōhau for eight years and the funding will focus on areas where cotoneaster has re-grown since the last control operation.

“We will focus on the lake shore and the terraces on the western side of Lake Ōhau Road. Cotoneaster is a very persistent plant that takes years to control. This work will take place over the spring and summer months.”

“Cotoneaster used to be extremely popular as a garden plant and birds spread it via the berries. While it is an attractive plant, in rural areas once it gets established it will out-compete and grow over the top of native plants. It is vigorous, fast-growing, and quickly establishes a monoculture if we don’t get on top of it with ongoing control work.”

Vivienne said it is vital to establish a long-term plan for funding when controlling cotoneaster as one treatment application is not enough to remove the pest plant.

“The trust is extremely fortunate to be able to continue working with Environment Canterbury and DOC on cotoneaster control and to receive ongoing funding from the Upper Waitaki Water Zone Committee for this project. Working together over the last eight years has created strong partnerships between all of us.”

Willow control at Lake Middleton

Small willow regrowth found all around the lake

Small willow regrowth found all around the lake

Meanwhile, the trust has also received funding from the zone committee to protect biodiversity values at Lake Middleton which Vivienne describes as a “jewel” for the Waitaki region.

“We will use the funding to control willow saplings which have started popping up around the northern and western edges of the lake. The willows were originally introduced for firewood and flood protection, but If we leave them there, they will take over and impact the water quality of the lake.”

The trust will work with Environment Canterbury staff, rūnanga/rūnaka and ecologists to assess the willow spread and look at options for removing the willows, with the work to begin early next year.

Vivienne said the ongoing success of both projects can be attributed to local input with the trust acting as the “eyes and ears on the ground”.

“Local people are in the area every day and can quickly identify any changes so action can be taken. We have the knowledge and understanding of the area that goes back years and projects like this make a real difference to the people who live and visit here.”

Protecting native riparian ecosystems

Zone committee chair Simon Cameron said that both projects align well with the committee’s three-year action plan goals.

"Our focus is improved management and preservation of recreational values of the Waitaki Lakes as well as enhancing mahinga kai opportunities.

"These projects help to ensure the ecological, habitat, cultural, social and recreational values of the native riparian ecosystems of Lake Ōhau and Lake Middleton are not detrimentally effected by the pest plants." 

Funding for local projects

Each of Canterbury’s water zone committees has an action plan which outlines how they will work with the community to deliver their aspirations for freshwater, as outlined in the Canterbury Water Management Strategy (CWMS). Committees, including Upper Waitaki Water Zone Committee, were provided $50,000 to support projects in their zones.

The Upper Waitaki Water Zone Committee has supported the following projects as part of its action plan:

  • Ōhau Conservation Trust: Lake Ōhau cotoneaster follow-up control project - $13,081; Lake Middleton Willow Control - $11,000
  • Tekapo Trails Society Inc: Lake Tekapo Willow Bay and lagoon planting project - $4,919
  • Omarama soil moisture monitoring pilot project - $21,000

Lake Tekapo Willow Bay and lagoon planting project

Two projects to enhance the Lake Tekapo area will go ahead with support from the zone committee.

  1. Native plantings will enhance a walk/cycle trail (1.2 km) from Pines Beach in the Regional Park to Willow Bay on the shores of Lake Tekapo. The plantings include the tree species on the right side of the track which, when established provide a natural barrier to stock entering the lake. On the bottom side of the track, groups of tussock and flax will be planted to mitigate run-off from the track and to help hide the trail from lakeview.
  2. Native planting and rabbit proof fencing for plants to enhance a lagoon on Sawdon Station Lagoon walking and bike trail.

Omarama soil moisture monitoring pilot project

The water zone committee is supporting a key project of the Omarama Water User Group - which is beginning a “Soil Moisture Monitoring Pilot Project” that investigates and implements technology that can improve nutrient loss management.

They aim to make improvements to overall effectiveness and usefulness of moisture technology by collaborating to manage, understand and use this equipment and data in a catchment wide approach.

Findings from the project would then be assimilated openly to other catchments in the Upper Waitaki Zone, in the interests of overall improvements to nutrient losses and loads that contribute to TLI readings in the Ahuriri Arm.

About the zone committee

The Upper Waitaki Water Zone Committee is a joint committee made up of community members, rūnanga and local councils. Find out more on our water zone page

Header image: Willows saplings around the edge of Lake Middleton in the Waitaki region will be removed early next year.