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Cattle grazing on rangeland in community drinking water catchments is recognized as a potential source of pathogens to drinking water surface sources. In the province of British Columbia, Canada (BC), Cryptosporidiosis outbreak incidents in the communities of Cranbrook and Kelowna in 1996 have generated public concern about the presence of grazing cattle in community watersheds. An audit of forest practices in 2010 subsequently led to the development of a pilot project in four community watersheds to develop Best Management Practices (BMPs) to mitigate the potential for this hazard. Subsequently there is pressure to expand the use of these BMPs to other watersheds. Effective and efficient deployment of these BMPs dictates that decision makers have an understanding of 1) the expected behaviour of cattle in a watershed including their routes of migration, and where, when, and how long they might access resources (feed, water, shade, and shelter) in the watershed, and 2) the presence of Cryptosporidium parvum (C.parvum) in their faeces and its persistence as a viable pathogen. With increased understanding of cattle movement from the use of GPS collar recorders, modern Agent Based Modeling is one possible approach to quantifying and gaining insight to efficacy and efficiency of BMPS to mitigate C.parvum contamination as a potential drinking water source hazard in other watersheds. This paper will explore the development, implementation and validation of an Agent Based Model (ABM) as a tool to support the selection and optimization of BMPs to mitigate risks to drinking water sources from cattle. It will also explore the underlying data requirements for this model, and the assumptions with respect to C.parvum persistence in BC's community watersheds as derived from both field and laboratory environment research, and the integration of the ABM results in Quantitative Microbial Risk Analysis (QMRA).