1. Introduction

NIWA report: Freshwater quality monitoring by Environment Southland, Taranaki Regional Council, Horizons Regional Council and Environment Waikato.

The Office of the Auditor General (OAG) requested assistance from NIWA with OAG's audit of freshwater quality management by regional councils. This report details results of a study performed by NIWA for OAG that responds to two specific questions posed by OAG:

  • Do regional councils have effective methods to gather information about and monitor the quality of freshwater?
  • Over the last 10 years, what is the state and trends in freshwater quality (within selected catchments and regions) as indicated by state of the environment monitoring data collected by regional councils as well as NIWA?

These questions have been addressed for four regional councils specified by OAG:

  • Environment Southland
  • Taranaki Regional Council
  • Horizons Regional Council
  • Environment Waikato

To answer question one we assessed the methods used to monitor the quality of freshwater in each of these regions. We first obtained information (metadata) from the regional councils that described their State of Environment (SoE) for physical, chemical and biological aspects of water quality monitoring programs for rivers, lakes and groundwater. Specifically, we obtained the locations and the details of monitoring sites, the frequency of monitoring, the variables analysed, the QA/QC and data storage procedures. From this information we assessed the network and monitoring programmes from technical perspectives.

To answer question two we analysed state and trends in water quality data for rivers and streams (hereafter referred to as "rivers") for the ten year period up to and including 2009. We included sites in the National Water Quality Monitoring Network (NRWQN) that is run by NIWA that are within the four regions.

The first section of this report describes the methods we used to address these questions. The subsequent two sections provide our response to the two questions for each of the four regions.