On 1 July 2025, NIWA merged with GNS Science to become Earth Sciences New Zealand.

Freshwater

We provide public information on river, lake, and groundwater conditions across New Zealand including freshwater quantity and quality.

Rachel Crawford and Paul Franklin inspecting a fish passage on the Waikato River.

Freshwater and Estuaries Update

A seasonal review and outlook for New Zealand's water resources, and an update on NIWA's freshwater research

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    Mitigation and best practice options

    Some simple steps to minimise the effects of wastewater on water quality and mahinga kai.
    Freshwater

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    Sediment and urbanisation

    How does urbanisation increase sediments in waterways?
    Environmental Information
    Freshwater quality

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    Biological limitations

    Identifying biological factors that may be limiting fish numbers requires sampling to ensure that key invertebrate prey species are not scarce and that pest fish, especially predators, are not abundant.
    Fisheries

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    Proud of your plants? 1 June 2017

    News article
    01 June 2017
    NIWA is doing a nationwide study to discover what makes the best riparian projects. Help us give you the knowledge to make the best riparian management decisions possible by taking our 5 minute survey.
    Rivers
    Freshwater quality

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    Mangroves: to clear or not to clear?

    Media release
    19 May 2017
    NIWA scientists have written a guide for managing mangroves, prompted by a desire for people to learn more about mangrove ecosystems, and what happens when they are removed.
    Estuaries
    Mangroves

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    NIWA Technical Background report for MfE “Clean Water” Swimmability Proposals for Rivers

    News article
    11 May 2017
    NIWA provides technical background information on "Clean Water" swimmability proposals.
    Freshwater quality

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    Paradise for eels? Getting to know the secrets of NZ's new icon

    Feature story
    09 May 2017
    As New Zealand's "Mr Eel", Niwa's Dr Don Jellyman has heard every tall tale. And some of them may be true.
    Estuaries
    Fisheries

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    Wetlands

    Wetland species and wetland management in New Zealand.
    Wetlands

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    Ten years of willow control at Whangamarino Wetland 1999 - 2008

    NIWA review of the ten year Whangamarino willow control programme and evaluation of willow distribution and other wetland vegetation types.
    Wetlands

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    Modelling vegetation-impacted morphodynamics in braided rivers

    NIWA is developing numerical models for predicting how the morphology of braided rivers responds to flow regulation and invasive exotic woody vegetation.
    Rivers

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    Modelling vegetation-impacted morphodynamics in braided rivers

    Research Project
    NIWA is developing numerical models for predicting how the morphology of braided rivers responds to flow regulation and invasive exotic woody vegetation.
    Rivers

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    Managing mangrove expansion

    This manual aims to provide the guidance needed to manage mangrove expansion, while maintaining the ecological integrity of estuaries and harbours.
    Estuaries