While the indicators for fresh water provide an overview of the quality and level of allocation in New Zealand, they do not provide a complete picture of the health of the freshwater resource. The indicators do not include several pollutants that can affect water quality, such as herbicide and pesticide residues, dissolved metals, pharmaceuticals and hydrocarbons.
The indicators also do not cover many aspects of freshwater ecosystem health, such as the type and abundance of fish. While many regional councils undertake such monitoring as part of their freshwater management programmes, data is not yet readily available for this to be reported at the national level.
Monitored lakes make up only a small proportion (4 per cent) of all lakes in New Zealand, and many of the lake monitoring programmes focus on lakes that have poor water quality or are at risk of water quality being affected by land use in their catchment. This means care should be taken when interpreting the results of the monitoring of water quality of New Zealand lakes.
A more balanced picture of lake water quality across the country can be obtained by estimating the condition of all unmonitored lakes according to the environmental factors that drive water quality (such as climate, lake depth and the size and types of land cover in the lake catchment).
Last updated: December 2007