National standards for discrete water quality sampling released

The long awaited National Environmental Monitoring Standard (NEMS) for Discrete Water Quality was released in March, contributing to the wider suite of existing Standards that collectively seek to improve national consistency in environmental monitoring. 

This NEMS addresses requirements for sample collection, field measurements and laboratory testing for a wide suite of physico-chemical and microbiological water quality variables across groundwater, rivers, lakes and near-shore coastal waters. NIWA oversaw the writing of the four-part Standard with the support of a small technical working group comprising water quality practitioners and scientists from regional councils, GNS Science and Hill Laboratories. 

A draft Standard released in October 2017 attracted a large number of valuable submissions which, together with the results of a national inter-laboratory comparison of low-level nutrient measurements, led to some changes in the final Standard. Key changes included the inclusion of both an alternative calibration procedure for ‘high quality’ field meters and a low-flow purging and sampling procedure for groundwater wells, refinements to visual clarity measurements, and alterations to some laboratory test methods and detection limits.

To assist with implementation of the new Standard, NIWA has been working with several regional councils to prepare a series of videos to illustrate good sampling practices. This work complements joint State of the Environment (SoE) river water quality sampling campaigns NIWA has been conducting with monitoring staff from Greater Wellington Regional Council and, more recently, Otago Regional Council (ORC). The ultimate aim is to establish a national quality assurance programme for river water quality monitoring.

NIWA and ORC field staff collecting water samples side-by-side from the Waitati River, an ORC State of the Environment (SoE) monitoring site north of Dunedin. The sampling formed part of a larger assessment of field practices against requirements of the NEMS for Discrete Water Quality.


Photo: Juliet Milne

Further reading:

Davies-Colley R.J., Milne J.R. and Heath M. 2019.  Reproducibility of river water quality measurements. Inter-agency comparisons as part of quality assurance protocols.  Journal of Marine and Freshwater Research.

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Resource Management Scientist