As well as having carbon sequestering superpowers, wetlands support fisheries, agriculture and flood control. Healthy wetlands store large amounts of carbon in their soils and plant material, making them critical for climate change mitigation.

However, wetlands remain among New Zealand’s most depleted ecosystems, with an estimated 90% lost nationally despite being recognised as a priority for protection since the Resource Management Act was introduced in 1991.

Degraded peat wetlands in New Zealand are estimated to emit the equivalent of about 8% to 10% of the country’s annual net greenhouse gas emissions.

The Root Causes of Wetland Loss in New Zealand: Statistics Update 2026 report identifies at least 416 hectares of natural wetland converted to modified land between 2018 and 2023. Most of this was to pasture, followed by loss to plantation forestry and mining. 

The findings build on earlier ELI-commissioned research showing more than 5400 hectares of freshwater wetlands were destroyed between 1996 and 2018, mostly through conversion to pasture, pointing to a long-running pattern of decline.

While the latest analysis covers a period that includes the introduction of stronger national freshwater protections in 2020, the report suggests wetland conversion has continued in the years since the rules came into force.

"What this update shows is that wetland conversion has continued. The rules have become stronger, but there still appears to be a monitoring and enforcement gap," ELI said.

"Wetlands are one of Aotearoa’s defining traits, but they are also one of our most depleted ecosystems. The expectation was that stronger national direction would change the trajectory. This evidence shows that new regulations must be properly monitored and enforced to have any real-world effect."

The report follows a 2024 High Court case taken by ELI against Environment Southland over failures to monitor and enforce wetland protections, with the court ruling councils must take active steps and dedicate adequate resources to safeguarding wetlands.

ELI said it was particularly concerned about the Government’s recent changes to wetland regulations, which mean beef cattle and deer that are not being intensively grazed no longer have to be excluded from natural wetlands.

“This is a new loophole, which risks further degradation and destruction of wetlands. Such loopholes in the rules protecting wetlands are a key barrier to the effective protection of wetlands.”

The report showed that between 1996 and 2016, nearly 5400 hectares of freshwater wetlands and more than 60 hectares of saline wetlands were lost through human activity. 

And between 2018 and 2023, Land Cover Database records showed a further net loss of almost 5000 hectares of wetland land cover types, including freshwater and saline wetlands and mangroves, to other land uses.

“Some of the loss was to another habitat type, in most cases to sand and gravel, and may reflect the dynamic nature of wetlands. However, the summary change tables indicate a net loss of 416 hectares to modified land cover types, presumably permanent loss through human agency," the report said.  

The identified wetland losses were predominantly linked to conversion into pasture, with a net loss of 338 hectares, followed by exotic  forestry at 56 hectares and mining-related land uses at 12 hectares. Herbaceous wetlands were reclassified in almost equal proportions as high-producing grassland, generally associated with dairy farming, and low-producing grassland linked to sheep and beef farming.

The largest apparent losses of freshwater and saline wetlands and mangroves to modified land uses occurred in Southland, Hawke’s Bay, the West Coast, Waikato, Otago, Auckland and Northland.

The report said wetland restoration remained minimal, with only 21 hectares gained compared with the scale of losses to development, suggesting New Zealand is failing to meet “no net loss” policies for wetlands.

"It is clear from this preliminary investigation that despite strong national rules implemented in 2020, wetland loss appears to have continued in some regions, particularly in Southland and the West Coast. 

“It appears that there needs to be continued vigilance from civil society to ensure that landowners, industry groups, developers and their contractors fully understand wetland drainage and clearance rules; consent conditions, monitoring and compliance processes, including of Environment Court orders, are robust, consistent and appropriate; breaches of wetland rules are enforced including remedial actions as required; and changes in national policy do not undermine long-fought battles to improve wetland protection.

"It is recommended that further investigation be undertaken to determine which instances of wetland loss occurred in breach of national and regional regulatory frameworks, whether those losses were subject to compliance or enforcement action, and what outcomes, if any, resulted from such actions."