Nitrate, ammonia and dissolved reactive phosphorus concentrations, NGMP sites, 2004–13

"At high concentrations, nitrate–nitrogen may have health impacts where it is for untreated drinking water, and it is also plant nutrient which can contribute to excessive plant and algae growth, potentially damaging the ecological health of rivers and lakes.
Ammoniacal nitrogen can be toxic to fish, animals and people at moderate concentrations.
Nitrate can be an indicator of general groundwater degradation as often it is accompanied by other pollutants from human activities, such as faecal pathogens and pesticides.

Dissolved reactive phosphorus is a plant nutrient which can contribute to excessive plant and algae growth, damaging the ecological health of rivers and lakes if it enters surface water.
Surplus phosphorus can originate on land from fertilizer or animal manure, where it can be drained or leached into groundwater as dissolved reactive phosphorus. It can also occur naturally in aquifers as a result of water–rock interaction.

This dataset relates to the "Groundwater quality: phosphorus" and "Groundwater quality: nitrogen" measures on the Environmental Indicators, Te taiao Aotearoa website. "