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.
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.
Last updated: 3 June 2011