[Microbial risk assessment of urban water bodies for aesthetical and recreational uses]

With the increasing public access to urban water bodies for aesthetical and recreational purposes, it is of critical importance for densely populated urban areas to conduct microbial risk assessment and accordingly implement effective risk management. Based on the methodology of quantitative microbial risk assessment, a case study was conducted on three typical urban water bodies for aesthetical and recreational uses in a southern city in China. Exposure assessment was carried out through water quality monitoring, field survey and literature review, and accordingly human health risk was assessed with different dose-response equations based on fecal coliforms (FC), Escherichia coli (EC) and Enterococci (ENT). Microbial risk estimated by different dose-response equations was found consistent with and comparable to each other. Stream B located in a residential area was not suitable for primary- or secondary-contact recreational uses, and its microbial risk to the public mainly came from water abstraction for household miscellaneous uses. Stream C and Lake E, located in a public open space and a scenic area respectively, could meet the current recreational requirements, and their microbial risk to the public was generally attributed to various recreational activities. It was necessary to address the public health risk associated with the unauthorized or inappropriate water uses (e.g. abstraction for household miscellaneous uses) of urban aesthetical and recreational water bodies.