The present work describes the in-progress activities devoted to the definition of a model of sustainable management of the water resources at local scale, with special reference to an Optimal Territorial Ambit (ATO). These activities partly take as a starting point the EPSILON international research project “Environmental Policy via Sustainability Indicators On a European-wide NUTS-III level”. The objective of such a model is to overcome the current DPSIR (Driving force-Pressure-State-Impact-Response) approach, allowing to create an ISST (Sustainability Synthetic Territorial Index), which is a composite indicator obtained from elementary indicators of environmental, economic, social and institutional nature, subsequently aggregated in sub-themes, themes and pillars. The 155 Municipalities constituting the ATO can then be clustered in 5 categories (very low, low, middle, high, very high), according to the value of the corresponding composite sustainability indicator. Thanks to this approach, several classes of users can simulate different sustainability scenarios relevant to different values of the elementary indicators. In particular, the identification of sustainability indicators for the management of water resources allows a quick assessment of the management actions to be activated for the water use and reuse, with reference to the different uses and the different aspects of the Integrated Water System.