Environment Court upholds pasture exclusions in classification of natural wetlands

23 Aug 22

A recent decision of the Environment Court provides guidance on the classification of natural wetlands and the assessment of pasture exclusions. This decision will interest landowners, particularly farmers, considering whether their land is subject to wetland controls.  

In the case of Greater Wellington Regional Council (GWRC) v S L Adams ([2022] NZEnvC 25), GWRC sought enforcement orders against the owners of recently subdivided land, to restrict activities in an area that GWRC contended was a natural wetland. The position of the subdividing parties, new landowners, and Upper Hutt City Council which granted the subdivision consent (together, the Respondents) was that the land in question met pasture exclusions in the relevant wetland definitions.


The subdividing parties undertook a 12-lot rural-residential subdivision totaling an area of 37.3 ha, located at Whitemans Valley, Upper Hutt. The subdivision was completed with titles issued and all lots on the subdivision sold. GWRC contended that the subdivision consent was wrongly granted and that an ecologist’s report (Report) provided with the application inaccurately applied the pasture exclusion provisions to natural wetlands in the area.

GWRC sought orders to restrict the activities permitted on Lots 1-7 and sought to impose controls on other areas also. Additionally, it sought the restoration of what they believed to be natural wetlands on the site.

The question before the Court was whether or not the areas identified by GWRC constituted natural wetlands as defined in the Natural Resources Plan for the Wellington Region (pNRP) or the National Policy Statement for Freshwater Management 2020 (NPS-FM), such that the restrictions on activities in wetlands would apply.

Definitions of wetlands and exclusions

Section 2 of the Resource Management Act 1991 provides that a wetland includes permanently or intermittently wet areas, shallow water, and land water margins that support a natural ecosystem of plants and animals that are adapted to wet conditions. This definition and its application may be further refined by specific planning instruments such as the NPS-FM and pNRP.

The pNRP provides that the definition of wetland has the same meaning as under the RMA, but does not include damp gully heads, or “wetted pasture”, or “pasture with patches of rushes”. This is referred to by the Court in the judgment as the ‘pasture exclusion provision’. Other Regional Councils may have definitions (and exclusions) different to the pNRP definition.

The NPS-FM also adopts the definition of a wetland from the RMA and offers three exclusions from this definition as being artificial wetlands, geothermal wetlands or any area of improved pasture that, at the commencement date, is dominated by (more than 50%) exotic pasture species and is subject to temporary rain-derived water pooling. Improved pasture is also defined as an area of land where exotic pasture species have been deliberately sown or maintained for the purpose of pasture production, and species composition and growth has been modified and is being managed for livestock grazing. This is referred to by the Court in the judgment as the ‘improved pasture exclusion provision’.

The Court confirmed that there is an evidential burden on the Respondents (as the parties seeking to rely on the exclusions) to place sufficient evidence before the Court to raise the reasonable possibility that the pasture/improved pasture exclusions apply. The onus then lies with the GWRC to negate that proposition on the balance of probabilities. In this instance, the long history of use of the site for pastoral farming put the issue as to whether the wetlands constituted wetted pasture or improved pasture “front and center from the outset.”

The pasture exclusion clause of the pNRP

The pasture exclusion provision of the pNRP was analysed first by the Court. It was acknowledged that the pNRP did not contain any definitions as to what constituted “wetted pasture” or “pasture with patches of rushes”. It was accepted on the evidence that a pasture is a place, usually a field sown or maintained for growing plants on which to graze animals. GWRC imported their own definition of how to distinguish wetted pasture with rushes from wetlands. That is, where 50% of the relative cover is defined pasture species. The Court noted that there was an obvious legal issue in GWRC purporting to import a binding pasture test into pNRP without undertaking the correct due process.

An ecologist employed by the subdividing parties undertook a vegetation assessment, and reported that the wetland areas met the improved pasture exclusion provisions so were not classified as natural wetlands as defined in the pNRP. GWRC contended that this Report was inaccurate because the subdividing parties had created atypical conditions by influencing vegetation growth.

GWRC contended that the subdividing parties had undertaken mechanical vegetation clearance, clearance and deepening of drains and installation of new drains, and the ripping of soil which created an atypical situation resulting in the Report being inaccurate. However, the Court was quick to criticise GWRC for using the definition of ‘mechanical vegetation clearance’ in reference to the common farming practice of mowing; and found that GWRC was unable to produce evidence that the subdividing owners had undertaken work to deepen drains beyond their original depth; and attributed the “ripping” to standard farming practices of the breaking up of soil pans to improve soil structure, drainage and aeration.

Concluding on GWRC’s contentions, the Court observed “that it may come as a surprise to people having any familiarity with farming practices for it to be suggested that the mowing, drain clearance and ripping activities… were in some way out of the ordinary in a farming situation.”

Accordingly, the Court found that the pasture exclusion applied. It considered that the Respondents had considerably exceeded the reasonable possibility standard of proof, and that GWRC failed to upset the evidence provided by the Respondents in “any material aspect.”

The improved pasture exclusion provision of the NPS-FM

In order for the NPS-FM improved pasture exclusion to apply, the area in question must be dominated by exotic pasture and subject to temporary rain-derived water pooling.

The Upper Hutt City Council engaged a second ecologist who surveyed 50 plots across the land to see if a pasture exclusion applied. He found that the improved pasture exclusion applied as, by his analysis, the average cover of pasture species was 95.3%. He also observed temporary rain-derived water pooling.

With regard to the water pooling requirement, GWRC submitted that the ‘wetland hydrology test’ had to be applied in determining the rain derived pooling as part of the definition contained in the NPS-FM. The ‘wetland hydrology test’ is found in the Ministry for Environment Guidance Document and requires a minimum number of consecutive days of inundation or saturation in most years, assessed as a 50% probability recurrence.

The Court identified two issues with the use of the hydrology test. Firstly, that it was contained in a guidance document, and the definition in a statutory instrument should not be influenced by non-statutory instruments. Secondly, the ability to actually apply the test due to data constraints. In order to determine whether an area was inundated for at least seven days during the growing season in most years, would require at least 10 years of data. The Court was of the view that this was not the appropriate legal test, and even if it was, GWRC had no data to establish that the hydrology of the site met the test. Therefore, the Court favoured the evidence of the second ecologist, that there was temporary rain derived pooling. In conjunction with the vegetative cover, the evidence was that the site met the improved pasture exclusion contained in the NPS-FM.

A Natural Wetland?

Having concluded that the area in question met the pasture exclusion under both the pNRP and the NPS-FM, the Court went on to consider whether the area was in fact a natural wetland in any case. The Court considered that determination of whether an area was a natural wetland required evidence on the vegetation, soil and hydrology of the area.

The Court determined that GWRC had failed to provide sufficient evidence to establish that the area was a natural wetland, noting in particular the lack of soil and hydrology evidence. The Court was particularly critical of GWRC for seeking such extensive relief without providing sufficient evidence to meet the burden of proof. The Court concluded that “the Regional Council has failed to satisfy us by a massive margin that the delineated natural wetland area in fact constituted natural wetlands… the evidence which we heard pointed to a contrary conclusion.

GWRC’s failure to undertake the work required to meet the burden of proof has resulted in a cost award against it in the sum of more than $482,000. The substantive decision on the wetlands issue is littered with criticism of GWRC, including the following question, which speaks volumes regarding GWRC’s stance in Court: ‘The Court asks the question that if the Regional Council’s own expert independent expert witness was unable to conclude on the evidence … whether or not the Site met the natural wetland definition, how could the Court possibly conclude that was the case?’

What this means going forward

This decision may provide some guidance to those grappling with application of the wetland definitions. It clarifies that:

  • The first step is to consider exclusion provisions, and where an exclusion applies further determination of an areas’ status as a wetland will not be required.
  • It is for the landowner to raise the reasonable possibility that the exclusion applies, and for the Regional Council to prove on the balance of probabilities that the exclusion does not apply.
  • Where the exclusions do not apply, establishment of a natural wetland requires a combined consideration of expert evidence on vegetation, hydrology and soil.

Classifying land as ‘natural wetlands’ can have significant impacts on the property rights of land owners – the relief sought by GWRC was described as “draconian” by the Court. As such, “every reasonable investigable step should be taken” when assessing whether land meets the definitions provided in the NPS-FM or relevant Regional Policy Statement/Plan.

Amendments to NPS-FM wetland definitions proposed

Subsequent to the release of the Court’s decision, the Ministry for the Environment has released for consultation an exposure draft of amendments to the NPS-FM and National Environmental Standards for Freshwater 2020 (NES-F), which propose to amend some aspects of the wetlands provisions considered by the Environment Court. For more information, see Environmental Policy Update article.

Want to know more?

If you have any questions about natural wetlands, please contact our specialist Agri or Resource Management team.

PDF version: here

This article was included in Edition 6 of our rural newsletter – Rural. which you can read here.

For more information contact:

Sarah Eveleigh