The management of water resources in Brazil occurs in a decentralized manner. Basin Agencies are deliberative entities that act as the executive office of the River Basin Committees. In the state of São Paulo there are three Basin Agencies: Fundação Agência da Bacia Hidrográfica do Alto Tietê (FABHAT), Fundação Agência da Bacia Hidrográfica do Rio Sorocaba e Médio Tietê (FABH-SMT) and Agência das Bacias dos Rios Piracicaba, Capivari e Jundiaí (AB-PCJ). Access to information is considered an important instrument of environmental governance and websites are an advantageous tool in the context of a network society. The general objective is to evaluate and compare the websites of the aforementioned River Basin Agencies, in order to verify the quality of information sharing. The methodology is based on the analysis of the structuring of pages and a protocol composed of seven variables (Identification, Ergonomics, Access to Information, Adequacy of Information, Content, Research and Relationship) and 41 analysis categories. The FABHAT and FABH-SMT website did not meet half of the indicators analyzed, presenting unsatisfactory performance. The AB-PCJ page met 33 requirements, being considered satisfactory. The website of an organization dedicated to water resources management needs to be constantly optimized to attract more users, to improve the community's understanding of the role of these institutions in society, to share information in a clear and accessible way with interested parties, and to strengthen the management of water resources.