River water quality water is valued for many reasons including ecological function and habitat, recreational value, its role in supporting people and industry, and its cultural significance. Nutrients such as nitrogen and phosphorus are essential for plant growth, however too much in rivers can lead to ‘nuisance’ growths of river algae and aquatic plants, degrading habitat. High concentrations in the form of ammoniacal nitrogen and nitrate-nitrogen can be toxic to fish and other aquatic animals. Water clarity is a measure of underwater visibility, and affects habitat of aquatic life such as fish and birds, and can also impact on aesthetic values and recreational use of rivers and streams.

Trend statistics and calculation results for the periods 1989-2013, 1994-2013, and 2004-2013 are provided by monitored site. Units for parameters are mg/m3, except CLAR (m). Refer to Larned at al. 2015 for further details.

For more information please see: Larned, S, Snelder, T, Unwin, M, McBride, G, Verburg, P, McMillan, H (2015).Analysis of Water Quality in New Zealand lakes and Rivers: data sources, data sets, assumptions, limitations, methods and results. NIWA Client Report no. CHC2015-033. Available at https://data.mfe.govt.nz/x/DDui3u from the Ministry for the Environment dataservice.

This dataset relates to the "River water quality" measures on the Environmental Indicators, Te taiao Aotearoa website.