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West Coast region

River Quality

Rivers and streams in the West Coast 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 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.

 

Catchments 14 Scientific Indicators
Scientific data for this region

This dashboard shows information on the data collected by the regional councils for water quality indicators, analysed as state and trend.

The state for the region is represented by the median concentration for the parameter across all sites within the region and then compares that value to the quartiles for all monitored sites in New Zealand.

Click on the parameters state icons to compare this region with others nationally.

  • State

    State shows how the median of samples from this site compares to other sites

  • Trend

    Trend shows how the quality of water is changing over time. Depending on the sampling history duration, five and ten year timescales are available:

Can I trust this data?

The Cawthron Institute has worked alongside regional councils to verify the processes and methods used for data collection, laboratory analysis of samples collected and the statistical analysis and interpretation of the results presented.

If all Cawthron ticks are green, then you can trust this data. However, if one or more ticks are orange, then conclusions should be treated with some caution.

For more details on each tick, see our 'Can I Trust This Data?' Factsheet.

Can I trust the data?
Data Collection

All samples were collected using approved field protocols and have been analysed in accredited laboratories. Therefore the data shown here has been collected and analysed following best practice.

State

This data is not sampled during high flows so the data shown only represents base flow conditions. Proposed national guidelines recommend sampling during both low and high flows to get a full picture of water quality.

Trend - Adjustment for flow

This data is not flow adjusted. National guidelines suggest that flow-sensitive variables are flow 'adjusted' before trend analysis. Therefore, any trends shown here may be affected by variations in flow across sampling occasions.

Bacteria

E. coli
State
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Trend
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Clarity

Clarity

Black disc
State
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Trend
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Clarity

Turbidity
State
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Trend
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Nitrogen

Nitrogen

Total Nitrogen
State
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Trend
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Nitrogen

Total Oxidised Nitrogen
State
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Trend
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Nitrogen

Ammoniacal Nitrogen
State
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Trend
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Phosphorus

Phosphorus

Dissolved Reactive Phosphorus
State
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Trend
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Phosphorus

Total Phosphorus
State
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Trend
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Download Data

.ZIP file of indicator readings for all sites in New Zealand
Download
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