Animal Waste, Water Quality and Human Health

Transport of microbial pollution in catchment systems 179reported in Kay et al. (2005d), and Crowther et al. (2002, 2001, 2003) have reportedsimilar investigations on other smaller catchments in the United Kingdom drainingto recreational waters. The objective of this approach has been to predict high-flowgeometric mean FIO concentrations at sub-catchment outlets. This information hasbeen used by the British regulators to target remediation efforts to “hot spot”sub-catchments which exhibit high positive residuals identified through modelcomparison with empirical data acquisition. These catchment scale studiesfollowed early process-based modelling studies (Jenkins 1984, Jenkins et al.1983, Kay & McDonald 1980). Neural network black-box models have beenapplied to identify non-point pollution sources by Brion and Lingireddy (1999)and Collins (2004) reported that a simple statistical model using flow and solarirradiance was able to explain 87% of the variance in E. coli during five rainfallevents monitored in a pastoral wetland in New Zealand.In an excellent review paper Jamieson et al. (2004a) state:Liquid and solid wastes generated from both animal and domestic sources cansignificantly impair drinking, irrigation and recreational water sources inrural areas. The assessment and management of non-point sources ofmicrobial pollution, in particular, is an issue of great interest. Arepresentative watershed scale water quality model would be an invaluabletool in addressing microbial pollution issues. [………….] A completewatershed scale microbial water quality model includes subroutines which(i) characterize the production and distribution of waste and associatedmicroorganisms, (ii) simulate the transport of microorganisms from theland surface to receiving streams, and (iii) route microorganisms throughstream networks. Current watershed scale models only account formicrobial transport to surface waters through overland flow and ignoresubsurface transport. The movement of microorganisms on the soil surfaceis predicted using simple empirical equations or by assuming thatmicroorganism transport is only associated with sediment erosion.However, several studies have indicated that the assumption thatmicroorganism transport is directly linked with sediment transport may notbe valid. The simulation of microorganism survival and transport inreceiving streams is complicated by sediment/microorganism interactions.More research is needed to be able to quantitatively assess and modelmicrobial processes in alluvial streams.The same team have conducted a series of studies in Ontario to clarify these areascovering the fate and transport of FIOs in catchment systems (Jamieson et al. 2004a,b,Jamieson et al. 2005a,b).Diffuse source transport of FIOs from farming activities were presented in Kayet al. (2008b) (see Table 5.8). This report was based on 205 stream monitoring sites