Groundwater quality trends 2005–2014

This dataset measures groundwater quality in New Zealand’s aquifers based on measurements made at monitored sites. Many factors influence the quality of our groundwater. Nitrogen, which occurs naturally in groundwater, can increase in concentrations due to agricultural and urban land use, and infrastructure such as waste treatment plants. High concentrations of nitrate-nitrogen in groundwater can affect human health and the quality of surrounding rivers and lakes that receive inflows from groundwater. Ammoniacal nitrogen can cause an undesirable smell that may make groundwater unsuitable for drinking water. Natural processes in groundwater can convert nitrate-nitrogen into ammoniacal nitrogen or other forms under some chemical conditions. Surplus phosphorus drains (leaches) into groundwater as dissolved reactive phosphorus. Too much nitrate-nitrogen, ammoniacal nitrogen, and phosphorus can lead to excessive plant and algae growth where groundwater flows into surface water. E. coli in groundwater is measured in colony forming units (cfu) and can indicate the presence of pathogens (disease-causing organisms) from animal or human faeces. The pathogens can cause illness for anyone who ingests them.

More information on this dataset and how it relates to our environmental reporting indicators and topics can be found in the attached data quality pdf.