Water Quality Data

We monitor water quality at 14 stream sites and eight lake/lagoon sites on the main Island.

Samples are collected on a quarterly basis and sent away for laboratory analysis. The data is collated and reported on every year, with more comprehensive analysis undertaken approximately every ten years to look at trends in the data.

Key findings from 2022

• Flow regimes of the major river systems are now well understood and characterised for both low flow and flood conditions.
• Poor and degrading water quality of waters across the island are likely caused primarily by climate patterns although changing farming emphasis to heavier livestock appear to strongly interact with climate. 
• Reduction in state or degrading trends had reduced at some sites but were particularly notable at key sites.
• The degrading water quality of Lake Rangitai is highly likely to be a result of its reducing area. Water is taken for stock water and domestic water use. With water resources largely used under sustained drought conditions, the lake becomes relatively small and shallow the water quality degrades.

View reports published in the past 10 years.