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Lake Okataina

Okataina is a deep lake (maximum depth 78m) and is oligotrophic, meaning it has low productivity and good water quality. The lake has no surface outlet and its water level varies dramatically in response to changing rainfall patterns. There is thought to be a subterranean outflow from the bed of the lake to Lake Tarawera.

Lake Okataina has an area of 10.9sq km and a moderately sized catchment at about 60sq km, which is dominated by native forest and scrub (84 percent of the catchment). Because of the forested catchment, the options available to manage water quality are limited. Recent attention has focused on identifying and targeting other nutrient sources and paths. This is underpinned by a PhD study into the impacts natural geological changes, land-use activities and introduced pests have on the catchment and lake. Wallabies in particular have cleared much of the understory, leading to the potential for increased nutrient run-off. There has been a recent incursion of hornwort into the lake and this invasive aquatic plant has the potential to affect the condition of native plant communities. Monitoring of the water quality in Lake Ōkataina occurs in the shallower of its two basins.

Lake Summary
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  • Maximum depth
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  • Catchment size
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  • Mixing pattern
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  • Geomorphic type
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Scientific data for this lake

This dashboard shows information on the data collected by the regional councils and unitary authorities for two indicators of lake water quality and ecological condition: TLI (Trophic Level Index) and LakeSPI (Lake Submerged Plant Indicators).  Select an indicator to see the historical results.

  • Water Quality

    Trophic Level Index (TLI)

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    The TLI score is an indicator of lake health and is determined from a suite of water quality measurements.

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    Trophic Level Index (TLI) history for this lake

    The TLI score for a lake is calculated from four water quality measurements – chlorophyll a, total nitrogen, total phosphorus and water clarity. If water clarity is unavailable, TLI is calculated using the other three water quality measurements. A higher score indicates poorer water quality.

    View a factsheet on TLI

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    TLI history for Lake Okataina
    Year

    What do the icons mean?

    VERY GOOD
    Very good water quality. Trophic Level Index of 0-2. Microtrophic lake conditions.
    GOOD
    Good water quality. Trophic Level Index of 2-3. Oligotrophic lake conditions.
    FAIR
    Average water quality. Trophic Level Index of 3-4. Mesotrophic lake conditions.
    POOR
    Poor water quality. Trophic Level Index of 4-5. Eutrophic lake conditions.
    VERY POOR
    Very poor water quality. Trophic Level Index of greater than 5. Supertrophic lake conditions.
    NO DATA
    No data available.
    TLI history for Lake Okataina data table
    Year TLI Score
    Year TLI Score
     Download data
  • Ecological Conditions

    Lake Submerged Plant Indicators (LakeSPI)

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    The LakeSPI status describes the ecological condition of the lake and is based on plants present.

    LakeSPI data provided by NIWA

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    LakeSPI history for this lake

    LakeSPI (Lake Submerged Plant Indicators) is a method of characterising the ecological condition of lakes based on the composition of native and invasive plants growing in them. A higher LakeSPI percentage result is associated with better ecological health:

    LakeSPI N/A
    LakeSPI {{spiData.details.Value}}%

    The overall LakeSPI score is calculated using a Native Condition Index ('good' plants) and an Invasive Impact Index (introduced, non-native plants):

    Native Condition N/A
    Native Condition {{spiData.details.NativeIndex}}%
    Invasive Impact N/A
    Invasive Impact {{spiData.details.InvasiveIndex}}% NA

    A higher Native Condition value indicates better ecological condition, but a higher Invasive Impact value indicates invasive plants are negatively impacting native plant communities.
    View a factsheet on LakeSPI for more information on these indicators.

    • LakeSPI
    • Native Condition
    • Invasive Impact
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    LakeSPI history for Lake Okataina
    Year

    What is this graph showing me?

    This graph is displaying the overall LakeSPI score over time. The results denote the ecological condition of the lake.

    EXCELLENT
    Excellent ecological health. A LakeSPI score of 75-100%.
    HIGH
    High ecological health. A LakeSPI score of 50-75%.
    MODERATE
    Moderate ecological health. A LakeSPI score of 20-50%.
    POOR
    Poor ecological health. A LakeSPI score of 0-20%.
    NON-VEG
    Non-vegetated. A LakeSPI score of 0% (there are no plants present).
    NO DATA
    No data available.
    LakeSPI history for Lake Okataina data table
    Sample Date LakeSPI Status LakeSPI % Native Condition Index % Invasive Impact Index %
    LakeSPI information has been provided by NIWA.
Sites

Monitored sites on Lake Okataina

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