Brazil has a new water law and is now implementing an innovative system to manage its waters. The Brazilian Federal Water Resources System Law was signed by the President of Brazil on 8 January 1997. To implement such a system, all institutional framework is now in the process of important changes, seeking achievements which it will be quite hard to meet. It is an arduous task to overcome obstacles such as effectively directing the decision-making process towards its lowest appropriate level. This paper will briefly present the new management system and the respective institutional framework. It will also discuss the implementation of River Basin Committees as the participatory approach adopted to decentralize management. As a case study, it will show the experience of the Piracicaba River Basin Committee, the first to be established under this new and modern vision in 1993.