Since 2002, LEESU organizes within the Water and sustainable development University of Val-de-Marne County, the World Wide Workshop for Young Environmental Scientists (WWW-YES). The thematic guideline of the seminar is 'Urban waters, resource or risks', inviting the participants to rethink the need for participative and integrated water management in urban areas and the lessons which can be learned from North and South experiences. The five days of the workshop are dedicated both to the presentation, discussion and assessment of individual research and to the building-up of scientific North – South cooperation projects. Admission fees and accommodation are supported by the Val de Marne County, Arcueil municipality and the Communaute d'Agglomeration du Val-de-Bievre (CAVB) for the 20 selected participants who need to find support for their travel costs. All presentations and discussions are made in English.