Animal Waste, Water Quality and Human Health

328Animal Waste, Water Quality and Human Healthmethod which systematically evaluates conditions to identify restorationopportunities within the stream corridor of a small watershed (Kitchell &Schueler 2005). The unified stream assessment provides a comprehensiveoverview of the condition of a river corridor and is based on nine components(storm water outfalls/discharge pipes, erosion, lack of vegetated buffer, leakysewer/exposed pipes, trash/debris, channel modifications/dams, access and anyunusual conditions).9.4 SOURCE ATTRIBUTION TECHNIQUESWhile E. coli can be useful for predicting the possible presence of faecalcontamination in water via spatial/temporal distribution studies (Geldreich 1966),it does not provide any indication as to the source of pollution. In order to applyeffective remediation practices for water bodies impaired by faecalcontamination, the sources must be identified (USEPA 2005). This has led tomuch research and investment in recent years into the field of source attribution, asuite of discriminatory methods which have the potential to distinguish hostsources (Scott 2002, Scott et al. 2002, Simpson et al. 2002, USEPA 2005, Field& Samadpour 2007). Other commonly used terms to describe these efforts aremicrobial source tracking (MST) and faecal source tracking. It is important tonote that MST is a limiting term in that it is not technically inclusive of chemicalmethods used for source attribution. Used as part of an expanded monitoringprogramme along with primary and secondary FIO assessments, modelling, andsanitary surveys, source attribution techniques can provide the level ofdiscrimination necessary to effectively identify water quality impairments due tofaecal contamination.While health risk from human sewage has been well established (Wade et al.2006), the risk associated with domestic, agricultural or wild animal faeces isless clearly defined (USEPA 2007). Outside of additional epidemiologicalstudies at water bodies solely impacted by animal sources, a direct approach formonitoring and identifying pathogens in water would be of benefit insafeguarding public health (Bertrand and Schwartzbrod 2007, Ruecker et al.2007). Pathogen distribution in the aquatic environment is, however, uneven,the assembly size necessarily large, and pathogens are difficult and costly toanalyze. Furthermore, the great variety of potential pathogens at any givenlocation effectively precludes testing for even a representative subset withcurrently available methods. For those reasons, the combined use of FIOs andhost-specific markers is important as part of a toolbox of assessment techniquesallowing pathogen exposure to be predicted and reduced.