There is a need to improve ability to assess ecological consequences of water management options and integrate ecological outcomes and efficiency optimization, particularly in light of climate change responses. Because of ecosystem complexity and a need to disentangle effects of multiple pressures, predictions of ecological outcomes are often reliant on statistical models and expert opinion. These predictions require validation with observed data and the availability of long-term ecological datasets may also prove valuable in this respect. The Australian Capital Territory has a variety of water supply options and water-use pathways, and ecological values defined for all waterways, providing a valuable opportunity for researching the ecological consequences of water management. The challenge is to identify the likely ecological responses to various water supply and use options and optimise for the most efficient option, while maximising ecological outcomes. This research will provide environmental water management solutions that also meet desired ecological targets. The project will provide ecological understanding to underpin decisions associated with water supply optimization by modeling and evaluating instream responses to management scenarios, while considering climate-change influences. Environmental flow rules will be developed and ecological responses defined for integration into a catchment-scale model to inform water management decisions.