Description: Total nitrogen, nitrate-nitrogen and ammoniacal nitrogen levels were monitored at selected river sites. The median values from 2013 to 2017 were calculated to measure the state of river water quality. River water quality trends were calculated for 10 years (2008–2017), 20 years (1998–2017) and 28 years (1990–2017) and categorised as very likely improving, likely improving, indeterminate, likely worsening and very likely worsening. River water quality monitoring data was collected by NIWA and regional councils using consistent time periods and comparable methods.
Copyright Text: NIWA, managed by Stats NZ and Ministry for the Environment.