Sewage-associated marker genes illustrate the impact of wet weather overflows and dry weather leakage in urban estuarine waters of Sydney, Australia.

•After rainfall, untreated sewage from WWOs was present in estuarine waters.•Avian marker gene was consistently present in stormwater samples.•Dog marker was occasionally detected in stormwater samples.•Animal fecal contamination does not appear to be an issue in the estuarine waters.