Since decades, the volume of information produced, stored and exchanged does not cease growing in all the fields and in particular in the field of the environment where studies, diagnoses, measurements, and models multiply in particular with the installation of national or regional data repository. The administration and the exchange of these data in the midst of workshops zones become arduous. Since, a few years, the creation of information, is accompanied by a more ‘rational' management of available information: development of validation techniques, data criticism, systems of description of information. This article presents the work undertaken within the Zone Atelier du Bassin du Rhône in order to build a tool of documentation about data related to the Rhone river knowledge. This metadata base must allow to the data producer a better management, and publication of information and to the user to find more easily the best information required towards his needs.