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Lake Rotomanu

Lake Rotomanu is a popular recreational spot for boating, water and jet-skiing, kayaking, and picnicking activities. The lake, which is close to the coast, is replenished from time to time by inflow from the nearby Waiwhakaiho River. 

Ducks and gulls are common on and around the lake. The construction of the Peringa Park wetland has improved the quality of storm water runoff entering the lake.

Summer recreational surveys showed that 85% (2015-2016) and 80% (2016-2017) of samples met the freshwater microbiological water quality guidelines prepared by the Ministry of Environment in conjunction with the Ministry of Health (MfE, 2003)  and did not exceed the ‘Action’ level (>550 E.coli/100mls).

 The State of the Environment technical report showing the freshwater recreational monitoring results for 2016-2017 is available at www.trc.govt.nz/environmental-monitoring-technical-reports/

Lake Summary
  • Lake size
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  • Maximum depth
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  • Catchment size
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Scientific data for this lake

This dashboard shows information on the data collected by the regional councils for two lake water quality and ecological condition measurements. Lake SPI (Lake Submerged Plant Indicators) and TLI (Trophic Level):

  • Water Quality

    Trophic Level Index (TLI)

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    This measure is the Trophic Level Index (TLI). The TLI indicates the lifesupporting capacity of a lake and is based on four water quality indicators.

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    Trophic Level Index (TLI) history for this lake

    Trophic Level Indicator (TLI) which measures four parameters: water clarity, chlorophyll content, total phosphorus and total nitrogen. From these parameters a TLI value is calculated. In cases where water clarity data is missing a three parameter TLI is calculated. The higher the value, the greater the nutrients and fertility of the water which encourages growth, including algal blooms. As a rule, higher TLI scores mean poorer water quality. View a factsheet on TLI

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    TLI history for Lake Rotomanu
    Year
    TLI history for Lake Rotomanu data table
    Year TLI Score
    Year TLI Score

    What do the icons mean?

    VERY GOOD
    Very good water quality. Trophic Level Index of less than 2. Microtrophic lake conditions.
    GOOD
    Good water quality. Trophic Level Index of 2-3. Oligotrophic lake conditions.
    AVERAGE
    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.
  • Ecological Conditions

    Submerged Plant Indicators (SPI)

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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.grades[0].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.grades[0].NativeIndex}}%
    Invasive Impact N/A
    Invasive Impact {{spiData.grades[0].InvasiveIndex}}%

    A higher Native Condition percentage is also good, but a higher Invasive Impact percentage is bad. View a factsheet on SPI

    • SPI %
    • Native Condition %
    • Invasive Impact %
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    LakeSPI history for Lake Rotomanu
    Year
    LakeSPI history for Lake Rotomanu data table
    Sample Date Status LakeSPI % Native Condition Index % Invasive Impact Index %
    LakeSPI information has been provided by NIWA.

    What do the icons mean?

    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.
Sites

Monitored sites on Lake Rotomanu

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No sites found.