Groundwater quality, state, 2014-18

This indicator measures groundwater quality in New Zealand’s aquifers and how it is changing over time, based on measurements made at monitored sites. We report on nitrate-nitrogen, ammoniacal nitrogen, dissolved reactive phosphorus, chloride, conductivity and Escherichia coli (E. coli) including:

• median values for the period 2014–18
• nitrate-nitrogen median values compared to the expectation for natural conditions, using a guideline value of 3 grams per cubic metre (g/m3) based on Daughney and Reeves (2005) and Morgenstern and Daughney (2012)
• the proportion of samples from each site that have concentrations of nitrate-nitrogen or E. coli in excess of the Maximum Acceptable Values for protection of human health (Ministry of Health, 2018).

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.