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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Research

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Tools & Services

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    Water Allocation Impacts on River Attributes (WAIORA)

    WAIORA is a decision-support system designed to provide guidance on whether a water abstraction or discharge could have adverse impacts on a number of environmental parameters.

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    LakeSPI outputs

    LakeSPI (pronounced ‘Lake Spy’) provides a quick and cost-effective tool for monitoring lake condition.

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    Quick-guides to freshwater flora and fauna

    These guides are designed for rapid identification of freshwater flora and fauna, usually to the generic level, for use in biomonitoring.

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    Weed management

    Find out how to manage aquatic weeds.

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    Species guide

    Aquatic plants have different lifeforms and habitats.

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    Education

    Learn more about aquatic plants.
    Freshwater quality

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    Publications

    Publications related to this section.

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    Outreach

    Aquatic plant overview, weed management options & freshwater plant ID guides.
    Freshwater quality

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    Trophic table

    Trophic preferences and range for submerged plant species in NZ lakes.
    Freshwater quality

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    Definition of terms and phrases

    Definitions of terms used in this section.

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    Resource survey and information

    An ability to discover basic information about plants in waterways is the foundation to solving a spectrum of problems that face our freshwaters today.
    Freshwater quality

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    Biodiversity services

    Native freshwater plants in New Zealand include species and assemblages found nowhere else, but these are under threat from invasive introduced weeds and fish, from decreasing water quality, and destruction of habitat.