Despite global studies, our understanding of PFAS mass transport pathways and related risks to marine environments remains limited. To address this, we investigated major rivers and creeks feeding into Port Phillip Bay, Melbourne, Australia, for 54 PFAS. We collected 90 grab samples and deployed 28 Polar Organic Chemical Integrative Samplers (POCIS) from 7 locations over 2 months to identify PFAS profiles across catchments and the influence of land uses and rainfall. We detected 28 PFAS in grab samples and 26 in POCIS. Mean Ʃ54PFAS for grab samples was 100.47 ng/L, with ~90% made up of ten PFAS (PFOS > PFHxS > PFOPA> PFHxA > PFHxPA > PFOA > PFPeS > PFPeA> PFBS > PFHpA). PFOS was the most common, but other PFAS, including perfluoroalkyl phosphonic acids (PFPAs) like PFDPA and pre-cursors 5:3 FTCA and N-EtFOSAA, were also present. Our surface water flow model showed diverse land uses influenced PFAS profiles across catchments. We estimated urban surface water flows exported over twice the Ʃ19PFAS compared to wastewater discharges, highlighting these as a significant PFAS source. Our findings underscore the value of monitoring multiple PFAS, while integrating surface water flow models, enhance our understanding of sources and transport mechanisms to marine environments.