After major floods occurred in 2003 on the Rhône River (France), the State and local authorities created a new institution at river level, in order to tackle flood issues at a supposedly more functional scale. Called Plan Rhône, this new partnership combined several policy sectors and several administrative levels, with the aim of developing the river territory and preserving floodplain retention capacity. The plan included a floodplain restoration project. However, after five years of negotiation, the project was finally abandoned. In this article, we analyze the drivers behind the failure to preserve floodplain retention capacity by focusing on scale issues, using two theoretical frameworks: the concept of "functional fit" between the scale of ecological issues and that of the institutions in charge of those issues, and the concept of "politics of scale" in which scale results from historical processes. We conclude that the scaling of an issue results from history. It legitimates a specific point of view and hampers alternative ways of seeing reality at other scales.