Lake water quality, state, 2016 - 2020

Adapted by Ministry for the Environment and Statistics New Zealand to provide for environmental reporting transparency. Dataset used to develop the "Lake water quality" indicator (available at www.stats.govt.nz/indicators/lake-water-quality).

We report on eight biological, chemical, and physical lake water quality attributes based on measurements made at monitored lake sites: trophic level index (TLI), chlorophyll-a, E. coli, total phosphorus, total nitrogen, ammoniacal nitrogen, nitrate-nitrogen, and clarity.

For all attributes we report on the median values for monitored sites during the period 2016–20. For selected attributes we also report:

• how these values compare to the National Objectives Framework (NOF) bands related to ecosystem health (trophic level), toxicity, and E. coli (MfE, 2020)
• a comparison of NOF and trophic level index (TLI) bands at monitored sites with the proportion of human modified landcover in the upstream catchment area

High concentrations of the measured biological and chemical attributes or low clarity indicates poor habitats for some species of animals and plants, risks for human recreation, potential toxic effects on aquatic life, and poor overall lake health.

More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf. Summary report available at environment.govt.nz/publications/environment-aotea....