Agricultural and urban development increases demands on groundwater resources. The sustainable use of groundwater requires a thorough knowledge of hydrogeology. This project addresses the origins, age, and geochemical evolution of groundwater in the Murray Basin, in particular constraining groundwater flow patterns, aquifer-aquitard interaction, water-rock interaction, and groundwater-surface water interactions both under present day and previous climatic conditions. The results of this project will ensure that this groundwater resource can be more effectively used and managed sustainably over the long term. In particular, historical responses of the system will be used to predict the effects of landuse or climate changes.