20 May 2021

New wetlands are taking shape in the upper catchment of the Ōpāwaho/Heathcote River as work continues on reducing the flood risk in the area.

The wetlands will act as storage basins in heavy rainfall events.

“We’re creating a network of new wetland areas upstream of the Ōpāwaho/Heathcote catchment to capture stormwater and improve water quality,’’ says Christchurch City Council Head of Three Waters and Waste Helen Beaumont.

“Our contractors are currently working on a 100-hectare facility between Cashmere and Sutherlands Roads and another in Cashmere Valley, close to the Christchurch Adventure Park. These new facilities will help reduce the risk of flooding, as the large ponds capture and store excess stormwater in large rain events,’’ Ms Beaumont says.

The wetlands, will also act as a natural filter for the stormwater before it flows into the Ōpāwaho/Heathcote River, which is home to koura (freshwater cray fish), kākahi (freshwater mussels) and īnanga (whitebait). 

The Eastman’s and Sutherlands stormwater basins, which are currently under construction, are part of four new stormwater treatment facilities in the Cashmere/Hoon Hay/Halswell area. Basins at Curletts Wetland and Ngā Puna Wai in Wigram are already operational and providing flood storage.

All of these facilities will have an automatic control system to manage water levels during a flood event.

They will be planted with thousands of locally sourced native grasses, shrubs and trees to increase the city’s biodiversity and to create new habitats for native birds, fish and animals. They will also have walking paths and green spaces for people to enjoy.

The largest site at Eastmans/Sutherlands - will have around 12,500 native trees planted and up to 350,000 other plants and shrubs. It will be the largest single site planting project ever undertaken in Christchurch.

The full network of stormwater facilities is expected to be operational by 2023.