Semnon


The Semnon is a long river in the Mayenne, Maine-et-Loire, Ille-et-Vilaine and Loire-Atlantique départements, western France. Its source is at Congrier. It flows generally west-northwest. It is a left tributary of the Vilaine into which it flows between Pléchâtel and Bourg-des-Comptes.

''Départements'' and communes along its course

This list is ordered from source to mouth: