Overview of the power, limitations and interpretation of microbial source tracking in recreational freshwater quality management
Please note: As of 1 July 2025, the New Zealand Institute for Public Health and Forensic Science (PHF Science) is the new name for the Institute of Environmental Science and Research (ESR). Research and reports published prior to this date may reference the organisation’s former name.
Summary
Freshwater recreational use is highly valued by New Zealanders. Contamination from point and non-point discharges of sewage and animal faeces presents a risk to human health. Water quality managers need to understand the risks to human health from faecal contamination to manage and improve recreational freshwater water quality and protect public health. Human faecal contamination may have human specific pathogens, such as viruses, but zoonotic pathogens from animal sources may also cause disease in humans. Monitoring recreational waters against the microbial criteria is routinely undertaken in the bathing season using the faecal indicator bacteria (FIB), Escherichia coli (E. coli). Where E. coli criteria are exceeded water quality managers need to identify the source of contamination to better understand the risk and target interventions that will improve water quality. Data from surveys of pathogens and faecal indicators in freshwater in New Zealand in 1998-2000, 2020 and 2021 showed that pathogen contamination comes from rural and urban activities.