State of Surface Water Quality

Due to the West Coast Region’s topography and climate water quality in larger waterways tended to fare better in the face of human induced environmental pressure compared with smaller ones. Smaller streams in lowland areas were more susceptible to being affected by human development. Spring fed streams that are located on agricultural plains form a stream type with their own characteristics.

Waterways in forested catchments had better water quality than those in pasture, including with lower faecal indicator bacteria, nitrogen and phosphorus concentrations, and better invertebrate community structure (MCI and %EPT). This is consistent with relationships observed around New Zealand.

Comparison of individual water quality parameters to guidelines and benchmarks indicated a broad range of results among sites. Some sites rated poorly for many parameters, while other sites only rated poorly for some. The particular natural characteristics of a water body are important when comparing results. These natural characteristics can exacerbate or sometimes mitigate anthropogenic effects. Invertebrate indices suggested that the top three quarters of sites had slight to un-impacted water quality, with the bottom quarter consistently rating moderate to poor water quality. Nuisance periphyton growths have been infrequent at most sites. A combination of higher nutrients and suitable climatic conditions are required for nuisance growths to occur.

Contact recreation monitoring at contact recreation monitored sites showed that lake sites had good water quality, as did to a lesser extent those situated in open coastal locations. Improvements for some river and lagoon sites were apparent, although levels of faecal indicator bacteria at some were consistently above their respective contact recreation guidelines.

Page reviewed: 18 Feb 2016 9:07am