The West Coast Regional Council monitors surface water quality through its Surface Water Quality Monitoring Programme. This programme assesses surface water quality states and trends at selected sites where human impacts/pressures occur.
Key trends from the most recent State of the Environment report indicate that:
- Water quality in larger waterways tend to fare better in the face of human induced environmental pressure when compared with smaller ones due to the West Coast’s topography and climate.
- Smaller streams in lowland areas are 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 catchments. This included lower faecal indicator bacteria, nitrogen and phosphorus concentrations, and better invertebrate community structure (MCI and %EPT). This is consistent with the monitoring obtained around New Zealand.
There was broad range of results among sites. The natural characteristics of a water body are important to consider, as these can either exacerbate, or sometimes mitigate, human induced effects.
Stream fauna at the top three quarters of sites suggested slight to un-impacted water quality, with the bottom quarter consistently rating moderate to poor water quality.
Monitoring at Council contact recreation (swim) sites showed that lake sites had consistently good water quality, as did to a lesser extent those situated in open coastal locations.
