The West Coast Region (Te Kaunihera Whakakotahi o Te Tai Poutini) extends 600 km down the South Island with the Southern Alps to the east and the Tasman Sea to the west.
The West Coast is home to approximately 32,000 people and protected public land covers about 84% of the Region. Rivers and streams fall steeply from their source to sea, usually in less than 50 km. Other than in the far north of the region around Karamea, the West Coast’s waterways are in a cool and extremely wet climate zone. The catchments of the larger waterways are mainly covered by forest and have hard rock under the beds, providing ample cool water and regular freshes. However, in the lowland coastal areas some parts of rivers run through softer rocks that are easily eroded and cause sediment to affect water quality.
The West Coast Regional Council focuses its monitoring effort on waterways where there is human activity rather than keeping track of water quality across the entire region. Therefore results indicate the level of impact of human activities in the minority of catchments where people live. Monitoring sites are designed to cover a representative combination of the major land use activities, e.g. mining, agriculture and urban drainage. Sampling of bugs in streams (macroinvertebrates) shows water quality is good in the top three quarters of monitoring sites, with the bottom quarter consistently rating moderate to poor. There has been some recent improvement in results for ammoniacal nitrogen, clarity, turbidity, and faecal coliforms.
Nutrient monitoring in the Grey and Buller rivers indicates that while ammoniacal nitrogen has decreased, other forms of nitrogen - total nitrogen and nitrate - have increased. Nitrogen levels, although increasing, are still low. The region’s frequent rainfall means we seldom see any algal growth related to high nutrient levels.
Air quality on the West Coast is generally good however over the cold winter months solid fuel burning for domestic home heating can increase air borne particulate matter. PM10, airborne particles less than 10 microns, are the main concern for air quality as these can pose a risk to human health. The West Coast Regional Council currently monitors PM10 at one site in Reefton where, over winter, there can be a number of exceedances of the National Environmental Standard for air quality.