Mapping the Otago Wetlands: An Investment in Our Future
Overview
Currently in New Zealand, there are several important wetlands’ management and restoration activities being carried out by local councils, iwi, community groups, Fish & Game and the Department of Conservation. Most importantly, an increasing number of landowners are now seeing the value and importance in restoring these unique landscape features.
In 2020, the New Zealand Government introduced the National Policy Statement on Freshwater Management (NPS-FM) regulatory package with the aim of embedding long-term change through regional plans, including policies to protect and restore wetlands. These policies mandate that each council - including the Otago Regional Council - must map all New Zealand’s natural inland wetlands of a minimum 0.05 hectares and lesser if contain threatened species or ephemeral, by 2030.
A unique example of nationally and internationally significant wetlands are right here in Otago, and contained within the Upper Taieri Scroll Plain, a series of wetlands in the upper reaches of the Taieri River, the only wetlands of its kind in New Zealand.
The Upper Taieri Wetland Complex consists of three sub-areas, the Styx (Paerau) Basin Wetlands, the Maniototo Basin Wetlands and Taieri Lake Wetlands. These areas are predominantly in private ownership and much of this area comprises pastureland used for grazing. However, most of these pasture areas retain significant wetland values, including being home to many threatened and critically endangered species of plants, fish, and birds.
Mapping the Upper Taieri wetlands
Under the Government’s directive, in 2021-2022, the Otago Regional Council commenced Phase One of a three phase project, mapping and delineation of the wetlands in the Upper Taieri Scroll Plain wetland complex. Working alongside the landowners and community groups, this task is expected to be completed by the end of 2022.
The mapping involves reporting on wetland hydrology, river water level, ground wetness, land curvature and the likelihood of land to be wet in an event of annual and seasonal high-water levels. Alongside wetlands hydrology and the scroll plains topography, the wetlands’ current state will also be assessed on its plant diversity (regardless of whether indigenous or non-indigenous species) and the proportion of the area that is dominated by plants that prefer wet soils/conditions. Vegetation cover will be ranked on the basis of the plants’ preference for wet, dry or intermittent conditions. If more than 50% of the vegetation cover consists of species that prefer or tolerate wet conditions, then the area is considered to be a wetland.
Phase Two consists of mapping and delineating regionally significant wetlands, which will also be completed in 2022. Phase Three, involving the mapping of all natural wetlands in the region, will be completed by 2030 prioritising those at risk followed by those identified in areas under development.
During these phases we will be actively engaging with local communities. If you are an owner of the areas being mapped, and you would like to know more, please check out our FAQs, or contact Dr Sami Khan (Sami.Khan@orc.govt.nz). You can also keep up to date on general water related work the ORC is doing by subscribing to On-Stream.
What are wetlands delineation and the protocols involved?
The NPS-FM 2020 guidelines suggest that in case of uncertainty or dispute about the existence or extent of a natural wetland (as identified in the maps), a regional council must have regard to the Wetland Delineation Protocols (WDPs).
New Zealand’s Ministry for Environment (MfE) has adopted a US based wetland delineation system, which uses three main criteria, i.e., vegetation, soils, and hydrology. These criteria have been adapted for New Zealand conditions and are available on the MfE website.
Why are we focusing on the Upper Taieri wetlands?
New Zealand’s wetlands are one of the world's most productive environments that support the greatest concentration of wildlife out of any other habitat.
They act like the kidneys of the earth, cleaning the water that flows into them. They trap sediment and soils, filter out nutrients and remove contaminants; can reduce flooding and protect coastal land from storm surge; are important for maintaining water tables; they also return nitrogen to the atmosphere. Wetlands also sequester carbon from the atmosphere through plant photosynthesis and by acting as sediment traps for runoff. Carbon is held in wetlands vegetation as well as in litter, peats, organic soils, and sediments that have built up, in some instances, over thousands of years.
The Taieri Scroll Plain Wetlands are situated around the Taieri River, which is the fourth longest river in New Zealand and follows an s-shaped course from the Central Otago block mountains to the sea near Dunedin. The upper catchment is a mosaic of tussock grasslands, farmland, wetlands and bogs which help store water and release it slowly into the river, protecting fish, wildlife and cultural values, and water sources.
The river is habitat for several of New Zealand's 27 native fish species including inanga, short-finned eels, kokopu and bullies. Four threatened species are found in this area: the Central Otago roundhead galaxias, dusky galaxias, Teviot flathead galaxias and the Taieri Flathead galaxias.
The Taieri scroll plain wetlands are also one of the top waterfowl sites in New Zealand. Among the 28 bird species recorded, the wetlands are home to the endangered black-billed gull, grey duck, white heron, black-fronted tern, and the nationally threatened Australasian Bittern and the Banded Dotterel.
Migrating birds visiting Otago’s wetlands are also an important reminder of our global connections and responsibilities, with some birds travelling thousands of kilometres non-stop to reach our wetlands.
Find out more about the Upper Taieri Wetlands Complex.
Upper Taieri Mapping Q&As
Wetlands are permanently or intermittently wet areas that support natural ecosystems of plants and animals, including many endangered species. They can include bogs, swamps, fens, shallow water and salt marshes, and are found from the coast to the high country.
With the introduction of the National Policy Statement for Freshwater Management (NPS-FM) in 2020, the Government intends to provide the best possible protection of our ‘natural wetlands’ while ensuring that restoration activities, and activities that help people understand and enjoy natural wetlands can continue.
By mapping New Zealand’s wetlands, we will gain a clearer picture of what needs to be done to meet these targets.
The National Policy Statement for Freshwater Management current definition of a ‘natural wetland (as defined in the Resource Management Act) is a wetland that is not:
- a wetland constructed by artificial means (unless it was constructed to offset impacts on, or restore, an existing or former ‘natural wetland’); or
- a geothermal wetland; or
- any area of improved pasture that has more than 50% of exotic pasture species or exotic species associated with pasture
Some wetlands (eg, ponds and stormwater treatment wetlands) have been constructed for purposes other than conservation. It is unreasonable to make it more difficult for them to be used for their intended purpose, so they are excluded under part (a) of the definition.
Areas also exist that may once have been wetlands or streams but are now heavily modified land (eg, pasture that is grazed that gets wet after heavy rainfall). These wetlands are excluded by part (c) of the definition.
This definition acknowledges the original intent that wet pasture areas, even if they were once ‘natural wetlands’, are now highly modified environments and should be able to continue their current use or be able to shift in land use. All other natural wetlands will remain subject to strong regulatory protection.
The Government’s mandate includes all wetlands, whether they be publicly or privately owned.
The National Policy Statement for Freshwater Management mandates Otago Regional Council to;
(a) identify and map every natural inland wetland in the region that is:
(i) 0.05 hectares or greater in extent; or
(ii) of a type that is naturally less than 0.05 hectares in extent (such as an ephemeral wetland) and known to contain threatened species.
(b) in case of uncertainty or dispute about the existence or extent of a natural inland wetland, ORC must have regard to the wetland delineation protocols (i.e., hydrology, vegetation and soil).
(c) the mapping of natural inland wetlands must be completed within 10 years of the commencement date (i.e., September 2020).
(d) Wetland mapping must be prioritised as follows:
(i) first, mapping any wetland at risk of loss of extent or values; then
(ii) mapping any wetland identified in a farm environment plan, or that may be affected by an application for, or review of, a resource consent; then
(iii) mapping all other natural inland wetlands.
Following Government guidelines, ORC has prioritised wetland mapping in the region as below;
(i) re-map and delineate wetlands in the Upper Taieri Scroll Plain wetland complex (Phase I),
(ii) re-map and delineate regionally significant wetlands, wetland management areas and complexes in the region (Phase II), and
(iii) map and delineate all natural and inland wetlands in the region (Phase III).
ORC’s wetland mapping will be prioritised as follows:
(i) mapping any wetland at risk of loss of extent or values; then
(ii) mapping any wetland identified in a farm environment plan, or that may be affected by an application for, or review of, a resource consent; then
(iii) mapping all other natural inland wetlands.
Following guidelines ORC has prioritised wetland mapping in the region as below.
Phase One: re-map and delineate wetlands in the Upper Taieri Scroll Plain wetland complex
Phase Two: re-map and delineate regionally significant wetlands, wetland management areas and complexes in the region
Phase Three: map and delineate all natural and inland wetlands in the region.
Yes, the consultation process will proceed as follows:
- A letter will be sent* to all affected landholders advising them that wetland(s) on their property have been assessed and mapped. A map showing the wetland(s) area will be enclosed with the letter and landholders will be invited to comment on the map
- If landowners disagree with the mapping precision and accuracy, then either an ORC staff or ORC commissioned wetland/GIS expert will ‘ground truth’ the recorded wetland values and / or proposed wetland boundaries using the NZ Ministry for Environment’s recommended wetlands delineation protocols.
- In all three phases, a combination of wetlands mapping techniques will be employed such as LiDAR (areal imagery) and Sentinal-2 (spaceborne timeseries imageries), and deep learning algorithm to capture the wetlands values
* This will be done when we know final maps of the wetlands (end of March for Taieri complex) and by the end of May all regionally significant wetlands and wetlands management areas.
Otago Regional Council is aware of landowner and community concerns about the regulatory changes and the uncertainty it presents. While this is understandable, it is hoped that by working with landowners we can improve these important environmental values for future generations.
The Otago Regional Council welcomes any assistance and feedback from landowners in the area. Please contact Dr Sami Khan (Sami.khan@orc.govt.nz).
