Monitoring and evaluation are best practice in Commonwealth environmental water management as they underpin effective program management and reporting, and are fundamental to adaptive management. There has been gradual improvement in our capacity to monitor the effectiveness of river and wetland restoration as strategies have been developed to deal with spatial and temporal variability and the effects of multiple interacting stressors. However, our capacity to evaluate has not kept pace, yet evaluation is as important to adaptive management as monitoring. The Commonwealth Environmental Water Office (CEWO) has established a five year program to monitor the outcomes of their management of Commonwealth environmental water and evaluate its contribution to Basin Plan environmental objectives. This presentation will describe some of the challenges associated with this task and the proposed strategies for overcoming them. Some of the major challenges include: 1) Scale - the Basin Plan environmental objectives are set at a Basin scale over a ten year time-frame, while environmental watering occur in river reaches or individual wetlands over periods of weeks to months; and 2) Ability to quantify the contribution of Commonwealth environmental water - although the CEWO has a large volume of environmental water to utilise, within the context of climate variability and the influence of other stressors, at a Basin scale the signal to noise ratio may be quite small. While these challenges are significant, the CEWO’s Long-Term Intervention Monitoring Project represents a significant opportunity to develop and implement effective evaluation, thereby contributing to the effectiveness of adaptive management.