This paper aims to present the information-based technologies used for water management in a test basin within the scope of the EU-sponsored SMART and OPTIMA projects. The study uses a dynamic simulation model with its associated databases and a water resources planning and optimization system, established through a web-based client–server implementation to support distributed use and easy access for multi-criteria optimization and decision support. The results clearly illustrate how a consistent and well-integrated set of advanced but practical Decision Support System (DSS) tools can be used for efficient “optimal” water management strategies and policies of use, designed for a participatory public decision-making process.