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Northland region

River Quality

Northland has an extensive network of rivers and streams. None of them are considered major on a national scale as Northland's narrow land mass means most rivers are relatively short with small catchments.

Most of the major rivers flow into harbours, rather than discharging directly to the open coast which means contaminants tend to take longer to disperse from these sheltered environments.

Rivers are channels for floodwaters, a function that is much needed because of Northland's relatively high rainfall, while prolonged dry spells also lead to very low flows in many smaller catchments. Northland's rivers are generally characterised as being slow flowing and muddy because the land is dominated by deeply weathered geology and fine clay soils. Northland's rivers and streams provide habitat for a range of indigenous flora and fauna, as well as being an important water supply for rural communities, horticulture and agricultural demands.

The Northern Wairoa River is the region's largest river, draining a catchment area of 3,650 square kilometres, or 29 per cent of Northland's land area.

Almost all monitored rivers in Northland, within all land cover types (including native forest reference sites) have turbidity and bacteria (E. coli) levels worse than the national median suggesting Northland has naturally higher background levels for these measures.

Catchments 20 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

All samples were collected using approved field protocols and have been analysed in accredited laboratories.

Trend - Adjustment for flow

This site 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 at the site.

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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