This project investigated nutrient silicon cycling in Hamilton Harbour, Lake Ontario. A field sampling program was undertaken to collect water, suspended sediment, and bottom sediment samples from Hamilton Harbour, which were then analysed for dissolved and particulate reactive silicon. Sediment cores were also used in sediment core incubation experiments to determine the flux of silicon from sediments to the water column. This data was collated into a reactive silicon mass balance model to determine silicon inputs, outputs and internal cycling processes within Hamilton Harbour.