Waterborne pathogens: Sources, fate, and transport in a watershed used for drinking water supply

This thesis presents the results of the first watershed-scale transport model of several waterborne pathogens, including Campylobacter spp., E. coli O157:H7, and Cryptosporidium spp., from agricultural land-based sources and wastewater effluent. Although the research was approached from a drinking water perspective, its implications are broader ranging. The issues addressed also impact public health, agriculture, recreation, and overall water quality. In recent years, a number of zoonotic pathogens (pathogens causing diseases in humans from animal sources), such as E. coli O157:H7, have emerged with respect to water. With increasing urbanization and agricultural intensification occurring in many regions of the world, the potential for increasing levels of pathogenic contamination of water resources exists.; A connection may exist between watershed hydrology and waterborne disease outbreaks, as many outbreaks have occurred following periods of intense rainfall. The objectives of the research were to determine the primary sources of pathogenic contamination in a watershed used for drinking water supply, and to gain a greater understanding of the factors that most influence their survival and transport in natural aquatic environments. The objectives were met through the development of a model for quantifying potential environmental loadings of pathogens from livestock and wastewater effluent sources, through a monitoring program performed in conjunction with a Canadian Water Network project, and by developing a hydrologic microbial transport model. The pathogens selected for study were Cryptosporidium spp., Giardia spp., Campylobacter spp., and E. coli O157:H7. The microbial indicators examined were Escherichia coli, fecal coliforms, and total coliforms. Water samples were also analyzed for culturable human enteric viruses and spores of Clostridium perfringens .; The natural variability of potentially pathogenic microorganisms in the environment from anthropogenic, natural and livestock sources is large and has been difficult to quantify. A probabilistic model was developed for estimating the production of Cryptosporidium spp., Giardia spp., Campylobacter spp., and E. coli O157 from livestock sources within a watershed. Probability density functions representing daily pathogen production rates from livestock were simulated for the Grand River Watershed in Southwestern Ontario. (Abstract shortened by UMI.)...