title: Cattle-derived microbial input to source water catchments: An experimental assessment of stream crossing modification.
abstract: The provision of safe drinking water is a global issue, and animal production is recognized as a significant potential origin of human infectious pathogenic microorganisms within source water catchments. On-farm management can be used to mitigate livestock-derived microbial pollution in source water catchments to reduce the risk of contamination to potable water supplies. We applied a modified Before-After Control Impact (BACI) design to test if restricting the access of livestock to direct contact with streams prevented longitudinal increases in the concentrations of faecal indicator bacteria and suspended solids. Significant longitudinal increases in pollutant concentrations were detected between upstream and downstream reaches of the control crossing, whereas such increases were not detected at the treatment crossing. Therefore, while the crossing upgrade was effective in preventing cattle-derived point source pollution by between 112 and 158%, diffuse source pollution to water supplies from livestock is not ameliorated by this intervention alone. Our findings indicate that stream crossings that prevent direct contact between livestock and waterways provide a simple method for reducing pollutant loads in source water catchments, which ultimately minimises the likelihood of pathogenic microorganisms passing through source water catchments and the drinking water supply system. The efficacy of the catchment as a primary barrier to pathogenic risks to drinking water supplies would be improved with the integration of management interventions that minimise direct contact between livestock and waterways, combined with the mitigation of diffuse sources of livestock-derived faecal matter from farmland runoff to the aquatic environment.
authors.affiliation: Queensland Bulk Water Supply Authority (Trading as Seqwater), Ipswich, Queensland 4305, Australia; University of New England, Armidale, New South Wales 2351, Australia. Electronic address: andrew.smolders@seqwater.com.au.
authors.forename: Andrew
authors.initials: A
authors.lastname: Smolders
authors.affiliation: University of New England, Armidale, New South Wales 2351, Australia.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Rolls
authors.affiliation: University of New England, Armidale, New South Wales 2351, Australia.
authors.forename: Darren
authors.initials: D
authors.lastname: Ryder
authors.affiliation: Queensland Bulk Water Supply Authority (Trading as Seqwater), Ipswich, Queensland 4305, Australia; University of Queensland, St Lucia, Queensland 4067, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Watkinson
authors.affiliation: Queensland Bulk Water Supply Authority (Trading as Seqwater), Ipswich, Queensland 4305, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Mackenzie
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D065187:Controlled Before-After Studies; D003612:Dairying / Q000379:methods; D016983:Enterococcus / Q000302:isolation & purification; D004784:Environmental Monitoring / Q000379:methods; D004926:Escherichia coli / Q000302:isolation & purification; D005243:Feces; D006801:Humans; D045483:Rivers / Q000382:microbiology*; D014867:Water; D014871:Water Microbiology; D014873:Water Pollutants / Q000032:analysis*; D014876:Water Pollution / Q000032:analysis / Q000517:prevention & control*; D014881:Water Supply / Q000592:standards*
chemical_list: D014873:Water Pollutants; D014867:Water
keywords: Dairy; Livestock; Microbial pollution; Source water quality; Stream bridging