There are well-founded concerns about water security for town water, irrigators, and the environment across much of the Australian mainland. At the same time there is increasing potential to develop tree ring-based hydroclimate reconstructions to integrate pre-instrumental climate information into Australian water management policies, and provide a more robust measure of water security. The aims of this study were to highlight the significant potential for application of Australian dendroclimatological research. To achieve this, we present a new ~1000-year summer inflow reconstruction for Lake Burbury in western Tasmania, which exhibits intermittent 4-8 year cycles, as well as a persistent ~128 year periodicity. We then developed a catchment model representing the Lake Burbury hydro-electric water supply system and simulated ~1000 years of storage levels, extraction, spills, seasonal recovery rates and flow volumes. The outcomes of the modelling demonstrate that a) the observed recent decline in flows and associated storage levels is unlikely to be unprecedented, b) periods of lower flows than observed in the instrumental record are possible, and c) periods of higher inflows, and therefore increased extractions/spills, are also possible.Importantly, our case study highlights the relevance of tree-ring based hydrological reconstructions in water management decision-making because they enable the reassessment of probabilities of high/low inflows and diversion practices. The method demonstrated here is transferable to other catchments where it is possible to develop hydrological reconstructions from tree-ring sites local to the catchment. By extending the instrumental record, recent trends in water availability can be placed in context and the likelihood of extreme events better assessed. This information can be applied to decrease vulnerability of Australian towns and cities to drought. There is, therefore, clear potential for further applied dendroclimatological research in this area.