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Otago's wetlands and estuaries are some of our region’s most valuable ecosystems, with strong ecological, cultural and socio-economic values. 

What is a wetland?

What’s so special about wetlands?

Bendigo Wetland at the head of Lake Dunstan

Wetlands are permanently or intermittently wet areas that support natural ecosystems of plants and animals (RMA 1991). They can include bogs, swamps, fens, shallow water and salt marshes, and are found from the coast to the high country. 

90% of New Zealand’s wetlands have been cleared and drained in the last 150 years. But more and more landowners are seeing the value in restoring these unique landscape features. 

If you have a wetland on your property, there are different rules depending on the type of wetland (Regionally Significant Wetland and/or a natural wetland) and what activity you are proposing to do in or near the wetland.

The National Policy Statement for Freshwater Management (2020) has further defined a natural inland wetland means a wetland that is not:

  1. (a) in the coastal marine area; or
  2. (b) a deliberately constructed wetland, other than a wetland constructed to offset impacts on, or to restore, an existing or former natural inland wetland; or
  3. (c) a wetland that has developed in or around a deliberately constructed water body, since the construction of the water body; or
  4. (d) a geothermal wetland; or
  5. (e) a wetland that:
    1. (i) is within an area of pasture used for grazing; and
      (ii) has vegetation cover comprising more than 50% exotic pasture species (as identified in the National List of Exotic Pasture Species using the Pasture Exclusion Assessment Methodology (see clause 1.8 of the National Policy Statement for Freshwater Management)); unless
      (iii) the wetland is a location of a habitat of a threatened species identified under clause 3.8 of the National Policy Statement for Freshwater Management, in which case the exclusion in (e) does not apply

Wetlands are important environmental filters, often described as the kidneys of the landscape. They are also important for biodiversity by supporting a variety of native birds, fish, invertebrates, and plants.

Wetlands can improve water quality by:

  • Filtering sediment and nutrients
  • Removing soluble nitrogen from runoff and resurfacing groundwater. In some soils, managed wetlands are the most effective solution to reducing the amount of nitrogen reaching waterways. Too much nitrogen in the water can cause nuisance plant/algae growth, which affects ecosystems and water quality.

Wetlands are valuable for Otago’s environment because they:

  • Improve local biodiversity by providing a habitat for fish, birds and insects
  • Reduce flood peaks by slowing the water flow
  • Retain summer water flows by releasing water slowly
  • Have both recreational and educational value

Wetlands perform important ecosystem functions:

  • storing water
  • filtering sediment, nutrients, bacteria, and toxic compounds
  • accumulating carbon
  • buffering major flooding events

Wetlands have important cultural significance as:

  • reservoirs for mātauranga (knowledge), wellbeing, and utilisation
  • mahika kai (food and other resource gathering sites) used by marae, hapū, and iwi,
  • provide significant habitats for plants, fish, birds, reptiles, insects, and micro-organisms
  • providers of medicinal plants for rongoā (Māori medicinal use)

One other important value of wetlands is their ability to tell us the climate and vegetation history of the area. Scientists are able to examine the pollen and subfossil records. This gives us information on how vegetation has changed and the trends in climate change over thousands of years. This also lets us predict future trends. 

Protecting our wetlands

Historically, wetlands were treated as a “Cinderella” ecosystem, and they were often drained to develop farmland. However, we are beginning to better understand how they influence the environment, improve the ecosystem, and benefit many human activities. This has led these habitats to more often become the focus of restoration and protection.

Although there are still around 250,000 ha of inland wetlands in Aotearoa New Zealand, this is only 10% of what was originally here. In only 150 years 90% of wetlands have been lost. While the surviving 10% are being threatened by human activities such as land modification. This continues even after the Resource Management Act (1991) came into effect, which provides laws and regulations designed to protect our wetlands. In Otago, we have seen significant distortion of freshwater wetlands particularly in our lowland areas. 

A huge part of the loss of wetlands happened between 2008 and 2012 when many wetlands were converted into pastor for farming. However, there is increasing interest in knowing the location and condition of all wetlands. This will provide better understanding for sustaining, managing, and restoring societal and ecological values.

The Regional Plan - Water for Otago (RPW), provides protection for 173 wetlands. These have been mapped and defined as Regionally Significant Wetlands (RSWs) under Schedule 9 of the RPW.

Regionally Significant Wetlands

Otago is home to several nationally significant wetlands, including scroll plain/meander wetlands (Upper Taieri River), string bog/patterned mire wetlands (Lammerlaw Range), saline wetlands (Sutton Salt Lake), and ephemeral wetlands (Von Valley), each supporting unique ecosystems

Read more

Wetlands in Otago

 

Hydrosystems diagram - Johnson & Gerbeaux

Otago contains many different types of wetlands, including types that are rare in the rest of New Zealand. Our wetlands have also retained a significant amount of forest or shrubland, that in other parts of the country have been destroyed by fires. The diversity of the Otago landscape ranges from lowland to alpine areas, central areas with continental climates, and more temperate coast areas. This diversity is not found in other regions of New Zealand and provides a varied climate to support thousands of wetlands.

 

One of the ways to define the different types of wetland is by their "hydrosystem", however many wetlands fit into more than one of these definitions. Of the 9 wetland hydrosytems, the only one not found in Otago is Geothermal wetlands. We do have examples of all remaining wetland hydrosystems:

  • Palustrine
  • Riverine
  • Lacustrine
  • Estuarine
  • Marine
  • Inland Saline
  • Plutonic
  • Nival
Wetland Types in New Zealand

2004

Johnson & Gerbeaux

0478226047

PNG | 845 KB

Download

Our towns and rural communities are supported by the different types of wetlands. Our wetlands are natural assets that help maintain abundant, high-quality water, help in carbon sequestration for mitigation of climate change, providing habitats for indigenous biodiversity and wildlife, and supporting recreational activities. Otago wetlands support a high biodiversity of native plants, fungi and animals, and includes endemic species, southern and northern distributional limits, and best examples nationally of some wetland types.

Regional Plan - Water for Otago updated to 4 June 2022

PDF | 5 MB

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Regionally Significant Wetlands

Regionally Significant Wetlands are identified in the current Regional Plan Water: for Otago (2004). Because they are significant to the region, regionally significant wetlands are mapped so they can be identified. 

A Regionally Significant Wetland is any wetland that has one or more of the following values:

  • Habitat for nationally or internationally rare or threatened species or communities
  • Critical habitat for the life cycles of indigenous fauna which are dependent on wetlands
  • High diversity of wetland habitat types
  • High degree of naturalness
  • Wetland scarce in Otago in terms of its ecological or physical character
  • Wetland which is highly valued by Kai Tahu for cultural and spiritual beliefs, values and uses, including waahi taoka and mahika kai
  • High diversity of indigenous flora and fauna
  • Regionally significant wetland habitat of waterfowl
  • Significant hydrological values including maintaining water quality or low flows, or reducing flood flows
  • Any wetland over 800 metres above sea level (alpine wetlands)


To protect the ecology, habitat and cultural values of Regionally Significant Wetlands, you must:

  • Not dig any new drains without resource consent. You can maintain existing drains, but there are conditions around this so give us a call before you start any work
  • Not dig any ponds without a resource consent
  • Not allow stock to damage the area - ORC recommends stock is excluded from wetlands
  • Not harm any native flora or fauna through over-spray or drift from weed spraying
  • Not introduce any exotic plant species without resource consent. A list of permitted plants can be found below
  • Not dam, divert or take water from a Regionally Significant Wetland, or alter the bed of a Regionally Significant Wetland, without resource consent
  • Make sure that any water discharged to a Regionally Significant Wetland is clear and colour-free, and does not change the water level range or flow of the wetland

Find out the rules for Regionally Significant Wetlands, including plants you can and cannot plant in a wetland.

Regional Plan - Water - Chapter 13: Land Use on Lake or River Beds or Regionally Significant Wetlands

May 2014

PDF | 471 KB

Download

Regionally Significant Wetlands in Otago

Regionally Significant Wetlands

Otago is home to several nationally significant wetlands, including scroll plain/meander wetlands (Upper Taieri River), string bog/patterned mire wetlands (Lammerlaw Range), saline wetlands (Sutton Salt Lake), and ephemeral wetlands (Von Valley), each supporting unique ecosystems

Read more

Estuaries

Estuaries in Otago are vital ecosystems where freshwater meets the sea, creating rich habitats that support diverse wildlife and protect against coastal erosion. Preserving these estuaries is crucial for maintaining ecological balance and biodiversity

Read more

Intermittently closed estuaries

Intermittently closed estuaries (ICEs) are an essential part of the Otago environment, but are one of the least understood ecosystems. Research of ICEs is vital to better protect our native biodiversity.

Read more

Natural wetlands

Natural wetlands in Otago, New Zealand, are vital ecosystems that support diverse wildlife, improve water quality, and mitigate flooding. Preserving these habitats is essential for maintaining biodiversity and ecological balance.

Read more

Wetlands are permanently or intermittently wet areas that support natural ecosystems of plants and animals. They can include bogs, swamps, fens, shallow water and salt marshes, and are found from the coast to the high country.

90% of New Zealand’s wetlands have been cleared and drained in the last 150 years. But more and more landowners are seeing the value in restoring these unique landscape features.

If you have a wetland on your property, there are different rules depending on the type of wetland (Regionally Significant Wetland and/or a natural wetland) and what activity you are proposing to do in or near the wetland.

If you have a wetland on your property, there are different rules depending on the type of wetland (Regionally Significant Wetland and/or a natural wetland) and what activity you are proposing to do in or near the wetland.

If you are planning to do works in or near wetlands, check to see if you will need resource consent:

Working in and around rivers, lakes, and wetlands

There are both regional and national rules which that may apply to doing works in and around rivers, lakes, and wetlands.

Read more

Doing works in or near wetlands

It is important to be aware of the national and regional rules when carrying out any activities in or near rivers, lakes or wetlands.

Read more

Information for this wetlands page has been predominantly derived from the report "Wetlands of the Otago region".

Wetlands of the Otago Region

June 2022

Johnson, Peter N;Lee, William G;Khan, Samiullah

Landcare Research & Otago Regional Council

PDF | 2 MB

The report places the Otago wetlands in a national context, describes the types and diversity of wetlands in the region, and provides an account of wetlands in each of the Freshwater Management Units and Rohe developed for the Otago Region.

Download

Glossary

Subfossil: 

“Cinderella” ecosystem: 

Carbon sequestration:

Hydrosystem: "Hydrosystems are the units of the uppermost level of wetland classification. They are based on general landform and broad hydrological settings, and distinctive features of water salinity, water chemistry, and temperature." (Johnson & Gerbeaux)

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