Investigating public health impacts of deer in a protected drinking water supply watershed.

The World Health Organisation's (WHO) Water Safety Plans highlight the need for preventative risk management when managing water contamination risks. As part of this approach, a management framework incorporating multiple barriers is necessary and there is a need to validate those barriers through scientific evidence. This paper reports on a study undertaken to validate the effectiveness, in terms of pathogen numbers, of having protected watersheds. The study aimed to determine if the deer population in a protected watershed carried Cryptosporidium and whether or not it was human infectious. Deer faecal samples were collected from the protected watersheds over a 12 month period and analysed using a new method, developed as part of this project, for genotyping Cryptosporidium. Early results showed the presence of Cryptosporidium, but following a refinement in the method no human infectious Cryptosporidium was detected. The results give some confidence that having protected watersheds is an effective barrier against pathogen contamination. They do not, however, imply that continued monitoring and management of the deer should cease. To maintain compliance with the Water Safety Plans, continual validation of barrier effectiveness is required.

Assessing the health implications of turbidity and suspended particles in protected catchments.

The supply of unfiltered disinfected drinking water from Melbourne's fully protected catchments means that the water-quality managers must ensure that the source water poses no public health risk. High turbidity is currently used as a surrogate of pathogens, and harvesting of water is based on its measurement. The work presented here summarises suspended particle and associated pathogen, microbial indicator and faecal biomarker concentrations collected to (a) quantify turbidity in an Australian water supply system and (b) assess the possibility of increasing water harvesting from selected tributaries. Pathogens and microbial indicators were present in low numbers in these source waters; increased turbidity during storm events was not associated with an increase in pathogen concentration. The results confirmed that protected catchments, along with good management, were effective barriers to pathogen contamination. Aesthetic issues still need to be addressed, but no measurable increase in microbiological risk was associated with storm-generated particles.