The NRWQN (National River Water Quality Network) consists of 77 sites on 35 rivers that are fairly evenly distributed over the two main islands of New Zealand. Monitoring commenced in January 1989. Water samples are collected monthly and analysed for a range of physical and chemical parameters (i.e., dissolved oxygen, water temperature, pH, conductivity). Other parameters that are being sampled include visual clarity, turbidity, coloured dissolved organic matter, total and dissolved forms of nitrogen and phosphorus and E. coli. Periphyton is also assessed monthly and benthic invertebrate samples are collected on an annual basis. Some sites are monitored monthly by both, councils and by the National Institute of Water and Atmospheric Research (NIWA). For the majority of those sites, LAWA will show data collected by councils, except at two sites where the council sampling frequency was less than monthly - those two sites are Waimakariri River at Gorge and Motueka River at Woodstock.
More information about the NRWQN is available from NIWA.