Wetlands
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3 min read
Protecting, restoring and creating wetlands on-farm can help improve water quality, reduce the impact of floods, and create habitat for native plants and animals. They can also help trap sediment and nutrients before they reach waterways, supporting a healthier farm environment.
What is a wetland?
Wetlands are areas on farm that stay permanently or seasonally wet. They include bogs, swamps, seeps and riparian areas.
These areas naturally sit in parts of the landscape where water collects or flows through, often receiving runoff from surrounding paddocks. As a result, they tend to have higher concentrations of nutrients.
What does a wetland do?
Wetlands work like a natural filter and sponge on-farm. They slow and hold water during heavy rain, helping reduce flooding, erosion and sediment loss.
As water moves through a wetland, plants and soils help trap sediment and remove nutrients and contaminants such as nitrogen and phosphorus before they enter waterways.
Wetlands also provide valuable habitat for native birds, fish and insects, supporting biodiversity and a healthier farm system.
Managing and protecting wetlands
Even small wetlands can make a big difference on-farm. Protecting and managing them helps improve water quality, support biodiversity and reduce sediment and nutrient loss. Wetland management may also be an action included in your Freshwater Farm Plan.
The key steps to managing a wetland are:
- Keep stock out: Excluding stock protects wetland plants and prevents damage to soils and waterways. The Resource Management (Stock Exclusion) Regulations 2020 require stock to be excluded from natural wetlands. For more information, see our stock exclusion page.
- Keep it wet: Wetlands need water for most of the year to function well. Avoid draining water away from existing wet areas.
- Control weeds and pests: Managing weeds and pests gives native wetland plants the best change to establish and thrive.
- Plant where needed: In some cases, wetland plants will regenerate naturally once stock and weeds are managed. Additional native planting can further improve biodiversity, resilience and visual appeal. See our riparian planting page for guidance.
Wetland rules and regulations
Rules apply to work in and around natural wetlands. Depending on the activity, you may need a resource consent or there may be restrictions in place. Before starting any work near a wetland, get advice from your regional council and check the National Environmental Standards for Freshwater. For more information, see our river structures and wetlands regulations page.
A farmer's perspective on managing wetlands
In the video below, Waikato farmer John Hayward explains the benefits of managing wetlands and his passion for being both environmentally friendly and productive.
Video 5:38 min
Constructed wetlands
Constructed wetlands are designed to improve water quality by slowing and filtering water through shallow, vegetated areas.
They can help reduce sediment, nitrogen and phosphorus entering waterways, while also providing a valuable habitat for native species. They also slow water flow, helping to reduce flooding in high rainfall.
How constructed wetlands work
Constructed, surface-flow wetlands work by directing water slowly across a shallow planted basin before it flows through an outlet structure or weir.
This simple design can work across a range of farm types and landscapes and is generally more cost-effective to build than other wetland designs.
DairyNZ and NIWA, alongside other technical experts, have developed a guide covering wetland sizing and siting, construction planning, plant selection, nutrient and sediment removal performance, and ongoing maintenance. You can download the guide here or see the NIWA website for more information.
Some regional councils offer funding for the development of new wetlands, so it’s worth checking what funding may be available before starting work.
Using wetlands to help manage N loss
Farmers in Southland have built different types of wetlands to help manage N loss, see their videos below.
Additional resources
Constructed wetland practitioner guide
Resources
Environment
Design and performance information for surface-flow constructed wetlands to reduce contaminant loss.
Additional links
Waterbodies and wetlands
/environment/waterbodies-and-wetlands/
Riparian Planting
/environment/waterbodies-and-wetlands/riparian-planting/
Wetland development
/research/regional-projects/wetland-development/
Wetland restoration
/research/regional-projects/wetland-restoration/
Freshwater Farm Plans
/regulation/policy/freshwater-farm-plans/
River Structures and Wetlands
/regulation/policy/river-structures-and-wetlands/
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