Skip to main content.

River water quality

National River Water Quality Monitoring Network National River Water Quality Network

More than 800 sites on New Zealand rivers and streams are regularly monitored for water quality by regional councils and the National Institute of Water and Atmospheric Research (NIWA). Of these sites, 77 are located on 35 rivers throughout New Zealand which collectively make up the National River Water Quality Network operated by NIWA. The remaining sites, located on both rivers and streams, are part of monitoring networks operated by regional councils.

To report on river water quality, the following are measured:

While the above measurements are reported on regularly at a national level, regional councils, NIWA and other agencies also carry out other monitoring such as measuring pH, suspended sediments and periphyton (algal) cover, checking for pesticides and herbicides or fish monitoring.

For more information please see report on Water quality trends at National River Water Quality Network sites for 1989–2007.

Recent state and trends

Recent studies have used data from the National River Water Quality Network and data from regional councils to look at recent state and trends in water quality.

Interpreting results for river water quality

In order to turn large amounts of data into some indicative national statistics, river water quality results are commonly presented as percentiles. See What are percentiles? for more on what these statistics are.

Did you know?

  • New Zealand is a narrow, mountainous country characterised by relatively small catchments and fast-flowing rivers and streams. Half of its 425,000 kilometres of rivers and streams are small headwater streams.
  • Of New Zealand’s total length of rivers and streams, 51 per cent lies in catchments with predominantly natural land cover, such as native bush or alpine rock and tussock.
  • The remaining 49 per cent of river length is in catchments that have been modified by agriculture (43 per cent), plantation forestry (5 per cent) or urban settlement (1 per cent).

Information on the limitations of the river water quality indicator

This information has come from:

Return to the main freshwater page

Last updated: 3 June 2011