Urban catchments contribute large amounts of nutrient pollution to receiving waters. These catchments are a complex matrix of land uses and surfaces, making it challenging to identify and manage specific nutrient sources. Over the past seven years, research in the Lake Tuggeranong catchment has focused on understanding the contribution of external nutrient loads delivered to the lake and identifying their sources. Three inflows were monitored using autosamplers, while 29 sub-catchment units were manually sampled during both baseflows and event flows over a 17-month period. Nutrient sources, including leaf litter, grass clippings, development sites and sports fields were evaluated. Total monthly loads entering the lake were correlated with monthly rainfall, with substantially higher loads observed during wet months (defined as those with above-average long-term rainfall) and even during dry months following prolonged dry periods. Event flow concentrations showed no clear relationship with weather variables such as rainfall intensity or antecedent dry periods. However, high nutrient concentrations were noted in low-intensity rain events following prolonged dry periods, suggesting an interaction between these variables. Leaf litter and grass clippings were identified as important nutrient sources, while sports fields contributed mostly during large rain events, and development sites were found to be less important. The position of leaf litter in the catchment affected nutrient release, with substantially higher releases occurring under continuous inundation than repeated inundation. These findings provide valuable insights for improving water management strategies in the Tuggeranong catchment.