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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    Staying ahead of water weed invasions

    Research Project
    Aquatic systems are under threat due to the introduction of invasive exotic species such as water weeds. Modelling work by NIWA has provided new information on which water bodies may be at greatest risk.

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    Formal identification keys

    Formal identification keys are the scientifically accepted way to identify species. These will allow the identification of species which are unclear when using quick guides.

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    An Overview of New Zealand's Freshwater Fish Fauna

    Compared to other countries, New Zealand has a sparse freshwater fish fauna of just over fifty species. But it is unique and comprises at least thirty-five native species of which thirty-one are found only in New Zealand.

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    Publications - mitigation systems (formerly rehabilitation and protection)

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    Freshwater biosecurity - publications

      

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    Catchments to estuaries - publications

    Publications related to the Catchments to Estuaries programme

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    Causes and effects of water quality degradation - publications

    These are some recent publications related to the causes and effects of water quality degradation programme.
    Freshwater quality

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    Environmental flows - publications

    These are some publications related to the Environmental flows programme.
    Hydrology and flow
    Rivers

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    Hydrological observations and predictions - publications

    Publications related to the Hydrological observations and predictions programme.
    Hydrology and flow
    Rivers

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    Fish risk assessment

    Research Project
    NIWA has developed a rapid, desktop model which assesses the potential impact of introducing new fish species to New Zealand. The model is customised to New Zealand's unique environment and endemic fish.

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    Mitigation systems

    Developing techniques for protecting, enhancing and rehabilitating the biodiversity of freshwater ecosystems and the cultural value they provide.
    Freshwater restoration

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    Catchments to estuaries

    Understanding and predicting the connections between catchments and estuaries to improve the management of diffuse-source contamination.