Environment - Ammoniacal nitrogen concentrations in rivers by dominant land cover 2009–2013

Ministry for the Environment


Ammoniacal nitrogen can form ammonia in water under certain conditions can be toxic to aquatic life; elevated quantities in waterways are primarily from direct discharges of pollutants such as untreated effluent; like nitrate-nitrogen, ammoniacal nitrogen is also readily used by plants and algae to grow.

Data calculation/treatment

Figure.NZ calculated the median, upper quartile, lower quartile, min and max clarity measures by land cover class. These calculations were undertaken to mirror the analysis undertaken for the Environmental Reporting Series (see http://stats.govt.nz/browse_for_stats/environment/environmental-reporting-series/environmental-indicators/Home/Fresh%20water/river-water-quality-nitrogen.aspx Figure 3)

Data provided by

Ministry for the Environment

Dataset name

Environmental Reporting: Ammoniacal nitrogen 2009–2013



How to find the data

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Import & extraction details

File as imported: Environmental Reporting: Ammoniacal nitrogen 2009–2013

From the dataset Environmental Reporting: Ammoniacal nitrogen 2009–2013, this data was extracted:

  • Sheet: Sheet1
  • Range: B4:G7
  • Provided: 24 data points

Dataset originally released on:

January 11, 2016

Purpose of collection

Small amounts of nitrogen are a natural component of healthy rivers. Nitrogen in rivers can vary due to differences in land use, climate, elevation, and geology. Nitrogen is transferred from land to water and is cycled through different forms, which can have different effects. Moderate concentrations of nitrate can cause weeds and algae to grow too fast. High concentrations of ammoniacal and nitrate nitrogen can be toxic to fish and other aquatic animals.

Method of collection/Data provider

Regional councils monitor river water quality to manage environmental impacts. These sites tend to be in catchments dominated by agricultural land use. Rivers in low-lying and hilly areas in the North and South islands are well represented, while mountainous areas in the South Island and parts of the central North Island are not. For the analysis presented here, NIWA used nitrogen data from 385 sites monitored by them and regional councils with consistent time periods and comparable methods (Larned et al, 2015).

Sites are classified by dominant land cover in the upstream catchment. Lower values for nitrate-nitrogen concentration are better than higher values.