Urban Stormwater Quality: Linking Pesticide Variability To Our Sustainable Water Future

Abstract:

Climate change and global population growth demand creative, multidisciplinary, and multi-benefit approaches for sustaining adequate fresh water resources and protecting ecosystem health. Currently, a driving factor of aquatic ecosystem degradation (stormwater) is also one of the largest untapped urban freshwater resources. This suggests that ecosystem protection and potable water security might both be achieved via treating and capturing stormwater for human use (e.g., potable substitution). The viability of such a scheme, however, depends on 1) initial stormwater quality (e.g., the contaminants present and their associated human/environmental health risks), 2) the spatial and temporal variability of contaminants in stormwater, and 3) the capacity of existing technologies to treat those contaminants to fit for purpose standards. Here we present results from a four year study of urban stormwater conducted across ten catchments and four states in Australia that addresses these three issues relative to stormwater pesticides. In total, 19 pesticides were detected across all sites and times. In general, pesticide concentrations were lower than has been reported in other countries, including the United States, Canada and Europe. This is reflected in few exceedences of public health (< 1%) and aquatic ecosystem standards (0% for invertebrates and fish, < 1% for algae and plants). Interestingly, pesticide patterns were found to be stable across seasons, and years, but varied across catchments. These catchment-specific fingerprints may reflect preferential commercial product use, as they map closely to co-occurrence patterns in registered Australian products. Importantly, the presence of catchment-specific pesticide variability has clear management implications; namely, urban stormwater must be managed at the catchment level and target local contaminant suites in order to best achieve desired human use and environmental protection standards.