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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  • Link to source page

    SHMAK water quality – visual clarity

    There are two methods to determine visual clarity in SHMAK; the clarity tube (or SHMAK tube) and the black disc method.
    Freshwater quality

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    Impacts of hydro

    Impacts of hydro-electric activities on water quality and mahinga kai.

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    Landscape

    On-Site Household Sanitation Guidelines for Fiji

    Research Project
    A participatory project empowering communities with self-help tools to improve water, sanitation and hygiene.
    Freshwater
    Pacific freshwater
    Freshwater pollution

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    Smelt

    Smelt have a distinctly forked tail and a strong cucumber smell.
    Freshwater fish
    Freshwater quality

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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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    Impacts

    Diverting water changes a waterways natural flow

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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