Microplastics are an environmental concern present in ecosystems globally, posing risks to ecological and human health. Freshwater runoff is a pathway to microplastic contamination of marine environments and identifying rivers that act as local microplastic sources to the marine environment is imperative to mitigating risks. In North Queensland, industries and towns are connected to the inner Great Barrier Reef World Heritage Area (GBRWHA) through rivers. Here, we sampled surface waters at seven river mouths along the GBRWHA to understand microplastic input into the coastal area and potentially inner reefs. Sampling occurred in February, June, and October since 2017 to monitor for any seasonal differences in microplastic abundance. Samples were laboratory processed using established methods, visually inspected for putative plastics using stereomicroscopy, and chemically confirmed using Fourier-transform infrared spectroscopy (FT-IR). Preliminary data from the 2018 sample set shows an average of 6.57 ± 4.08, 15.71 ± 11.80, and 6.86 ± 3.08 plastics present across all sites from February, June, and October consecutively. The most common plastic types found in these samples are polyethylene (n=83) and polypropylene (n=32). On-going monitoring will provide a unique dataset to map spatial and temporal differences in microplastic input along the GBRWHA and assist GBRWHA management initiatives.