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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    Chemical contamination and wastewater

    What are the potential sources of chemical contaminants in wastewaters?

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    Further reading

    References, further reading, and links to useful websites.
    Freshwater quality

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    Dissolved oxygen

    Dissolved oxygen (DO) is a relative measure of the amount of oxygen (O2) dissolved in water.
    Freshwater quality

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    Impacts of wood processing

    Impacts of timber processing activities on water quality and mahinga kai.

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    Riparian vegetation and agriculture

    How may agricultural activities impact riparian vegetation around a waterway?

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    Mahinga kai - what species interests you?

    In Kaitiaki Tools the term mahinga kai generally refers to indigenous freshwater species that have traditionally been used as food, tools, or other resources.
    Freshwater quality

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    Chemical contamination and aquaculture

    What are the potential sources of chemical contamination from aquaculture activities?
    Aquaculture

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    Chemical contamination and mining

    What are the potential sources of chemical contamination from mining activities?

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    Wastewater Treatment

    Wastewater treatment is the separation and extraction of solid waste from liquid waste, and the removal of nutrients and pathogens.

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    LakeSPI diver

    LakeSPI: Keeping tabs on lake health

    Software Tool/Resource
    The condition of many NZ lakes is under threat from land-use changes and the invasion of alien aquatic plants.
    Invasive species
    Ecological monitoring
    Lakes

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    Dairy farming activities

    Dairy farms operate to maximise milk production

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    Loss of riparian vegetation

    Plants and trees along the water margins and banks are called riparian vegetation.