This text presents the results of a one-day workshop on retention ponds in the "Villes nouvelles" in the Ile-de-France" region. 25 experts participated to this seminar which took place in March 2001. All the relevant technical and scientific disciplines involved in the design and the maintenance of retention ponds were represented. It appears that these ponds designed in the seventies are the signature of a typical urbanism. They contributed to organise the appropriation of the new urban areas by their inhabitants. Today the main related stakes deal with the development and the evolution of the multiple uses of these retention ponds.