Rivière le Charlieu

10.8 km long, it rises in the commune of Rochefort Samson and joins the Isère (at the foot of the Château de Favor) in Bourg de Péage, after crossing the Bois des Naix.

The water of this stream seems to have a special significance in the history of the Bois des Naix.
In Occitan, "Naix" refers to a damp place where hemp is "retted": the plant is macerated in water for several days to extract the fibers, which are then beaten, softened, combed and spun. The water from the stream and the ponds in the wood must have been used for this hemp textile process.

On an environmental level, the stream and ponds in the park enhance the biodiversity of the Bois des Naix, allowing wetland flora and fauna to flourish.