Source: Environment Canterbury Regional Council
The trial draws on findings from a four-year NIWA study that show artificial wetlands to be effective for removing contaminants, like nitrogen, sediment and phosphorus, from freshwater.
The selection of a pilot site for this project involved several factors. The final choice was based on replicability, cost-effective construction and maintenance, and favourable soil conditions.
Wetland design and construction
The design and construction of the wetland features a snake like pattern of raised land that guides draining water through the system slowly, allowing for maximum filtration. In addition, the site is home to 4,800 native riparian plantings with more still to come.
Committee members at the Delany Wetland site
A 1.6-hectare section of retired pasture at Jerseyland Dairies in Culverden was ultimately chosen, in collaboration with landowners Tim and Jo Delany, who are strong advocates for biodiversity. The site’s peaty soil layer over a clay base provides optimal conditions, slowing drainage to ensure water remains in the wetland long enough for effective treatment.
According to historical survey maps dating back to the 1860s, it is likely that the site was also once part of a natural wetland drained for agriculture in the early 20th century.
To test how well the Delany Wetland is filtering out contaminants, the team is sampling and testing water from five sites across the wetland each month. August 2024 marked the first round of sampling, and thus far, the results are promising.
Community benefits
Outcomes of this constructed wetland trial will allow community-led groups, like water zone committees, landowners and industry to better understand if replicating and implementing constructed wetlands more widely could address water quality issues.
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Waiau Uwha riparian and mahinga kai restoration project
Local landowner and dairy farmer, John Faulkner, invited the committee to the site of his riparian restoration and weed eradication programme, which spans 2.5 hectares of boundary land on the edge of the Waiau Uwha river.
The Waiau Uwha is an important braided river system in Waitaha/Canterbury that provides habitat for a variety of native fish and bird species.
Goals of the project
Among the key native birds that Faulkner is keen to protect are the nationally threatened New Zealand dotterel/tūturiwhatu pukunui and ngutu pare/wrybill, both shorebird species vulnerable to habitat loss from human activity.
With support from Ministry of Primary Industries’ One Billion Trees Fund, Faulkner enlisted Native Plant Specialist, Sue McGaw, to plan the installation of 9,500 indigenous plants. There are 64 species of plants that have been placed in specific groupings called biodiversity nodes, collections of species that are often found in nature together.
John Faulkner talking about the biodiversity project
Indigenous planting initiative
In the same area, to honour the memory of a dear friend, Faulkner is working with guidance from Northern Pou Mātai Kō/Cultural Land Management Advisor Makarini Rupene to establish a site based on contemporary nohoanga values beside the Waiau Uwha river. The site’s purpose to enhance local access to traditional mahinga kai activities. Nohoanga refers to the seasonal occupation of sites that Ngāi Tahu whānui utilised as they travelled Te Waipounamu/The South Island to gather kai and other natural resources.
Faulkner’s ambitious vision, in partnership with a network of adjacent landowners, is to restore an 18 km stretch of river that leads to Waiau township. This project would create a biodiversity corridor of Indigenous fauna to keep pest plants and predators at bay and increase the biodiversity and mahinga kai values of the area.
About the Kaikōura Water Zone Committee
The Kaikōura Water Zone Committee is a joint committee of Environment Canterbury, Kaikōura District Council, Rūnanga and members of the local community.
“This field trip was a great opportunity for our committee to meet and network with others, and to draw inspiration from catchments that are working at the local level to tackle tricky issues when it comes to water management and biodiversity,” says Jodie Hoggard, facilitator of the Kaikōura Water Zone Committee.
“It’s inspiring to see the mahi that landowners are driving to achieve better outcomes for the environment. I know the committee really valued the day, appreciated the networking opportunity and are excited to discuss how we can support similar projects in our patch.”
We allocate funding annually for water zone committees to recommend support for community-led projects that aim to improve the environment and help meet Canterbury Water Management Strategy objectives.
Each committee outlines its steps for meeting these targets in an Action Plan for 2021-2024.
