Diffusive Gradient in Thin film (DGT) is a speciation technique now commonly used in the scientific literature to assess metallic contamination in water. However, applications usually take place in a same watercourse or in neighbouring sites. The study presented here shows the first results of a large scale deployment in the Seine basin, around Paris in France. The data set acquired allows us to draw several lessons from it about the level of contamination of the basin and the behaviour of the labile fraction defined by DGT.