There is increasing interest in developing irrigated agriculture across northern Australia – a development that will modify natural water flow regimes that support estuarine and coastal fisheries. Trade-offs associated with proposed water resource allocation are currently unknown and their quantification entails evaluating how altered river flows might affect the fishery and ecological values. Such analyses are also complicated by the fact that each catchment is different, and hence models and associated recommendations need to be tailored to be catchment area-specific. As there is currently no suitable ecosystem model available, this project will develop a model of intermediate complexity for ecosystem assessment that integrates existing data and understanding. This will be used to produce quantitative estimates of the impact of alternative flow regimes on the relative abundance of key fishery and other marine species in the Gulf of Carpentaria, as well as impacts on total fishery catches and value. Results will be summarised in technical and non-technical reports to share findings and engage in other relevant broader management fora.