Evaluation of three source tracking indicator organisms for watershed management

The use of indicator organisms to ensure the microbial safety of drinking water is a standard practice throughout the developed world. Traditional coliform indicators, however, are not always the most suitable indicator for all waterborne pathogens, especially viruses and protozoans. Drinking water contaminated with human waste is typically associated with a higher risk of infection by human pathogens. For that reason, source-specific or source tracking indicators would be beneficial in identifying the source of water contamination. The focus of this research was to determine the potential of three source-specific indicators (sorbitol-fermenting Bifidobacteria, Rhodococcus coprophilus and serogroups of F-specific coliphages) for differentiating human, grazing animal and other wildlife microbial inputs into a drinking water watershed. Three locations within a surface water source watershed management area were sampled over a 13-month period. The results indicated that the three indicators tested might be a good means of discriminating between microbial input sources into drinking water supplies.