Land drainage, Water  |  7 Jun 2022

More than 100,000 native trees will be planted in the city’s south-west as part of a network of new wetland areas in the upper catchment of the Ōpāwaho/Heathcote River.

It will be the largest native planting project ever undertaken by the Christchurch City Council.

The Eastman Wetland landscape plan was approved by the Waipuna Halswell-Hornby-Riccarton Community Board last week with planting to take place over the next three years.

“This project will return a vast area of native plants to the city, reduce the amount of sediment going into waterways and protect natural springs,” Council Head of Three Waters Helen Beaumont says.

“The wetlands act as a storage basin in heavy rainfall, reducing downstream flooding and improving waterway health. They'll also provide a wonderful area for people to connect with nature and will create new habitat for native birds, fish and insects.”

The new wetlands are being developed in the upper catchment of the Ōpāwaho/Heathcote River

Council contractors have been developing the 100-hectare facility on former farmland between Cashmere and Sutherlands Roads and towards Hoon Hay Valley.

The large ponds will capture and store excess stormwater and act as a natural filter before the water flows into the Cashmere Stream and on to the Ōpāwaho/Heathcote River.

Both of these waterways have freshwater crayfish/koura, freshwater mussels/kākahi, whitebait/īnanga and other native fish.

“Now we have the landscape plan approval we can start to look at the planting programme. The Council’s Harewood Nursery has been working with suppliers for the past two years as a programme of this scale requires a lot of preparation,” Ms Beaumont says.

The plan provides for 30,000 to 35,000 tall trees that will grow up to 12m high, 70,000 to 75,000 small trees and shrubs growing up to 5m high and between 600,000 and 650,000 plants.

Large areas of Rongoā garden will be developed to provide a sustainable place to collect plants for use in traditional Māori medicine. Walking and cycling tracks are included as part of the landscape plan, along with a car park. 

Provision has also been made for a cycling pump track to be included. Council staff will be working with Cashmere High School students to help them design and build the track.

“We hope this project will positively benefit people of all ages and from right across the city," says Ms Beaumont.