The Semnon (; ) is a long river in the

Mayenne Mayenne ( ) is a landlocked department in northwest France named after the river Mayenne. Mayenne is part of the administrative region of Pays de la Loire and is surrounded by the departments of Manche, Orne, Sarthe, Maine-et-Loire, and Il ...

Maine-et-Loire Maine-et-Loire () is a department in the Loire Valley in the Pays de la Loire region in Western France. It is named after the two rivers, Maine and the Loire. It borders Mayenne and Sarthe to the north, Loire-Atlantique to the west, Indr ...

Ille-et-Vilaine Ille-et-Vilaine (; Gallo language, Gallo: ''Ill-e-Vilaenn'', ) is a departments of France, department of France, located in the regions of France, region of Brittany (administrative region), Brittany in the northwest of the country. It is named a ...

and

Loire-Atlantique Loire-Atlantique (; Gallo language, Gallo: ''Louére-Atantique''; ; before 1957: ''Loire-Inférieure'', ) is a departments of France, department in Pays de la Loire on the west coast of France, named after the river Loire and the Atlantic Ocean. ...

'' départements'', northwestern France. Its source is in Congrier. It flows generally west-northwest. It is a left tributary of the

Vilaine The Vilaine (; ) is a river in Brittany, in the west of France. The river's source is in the Mayenne ''Département in France, département'' (53), and it flows out into the Atlantic Ocean at Pénestin in the Morbihan ''département'' (56). It is ...

into which it flows between Pléchâtel and Bourg-des-Comptes.

''Départements'' and communes along its course

This list is ordered from source to mouth: *Mayenne: Congrier, Saint-Erblon, Senonnes *Maine-et-Loire: Pouancé *Ille-et-Vilaine: Eancé, Martigné-Ferchaud *Loire-Atlantique: Fercé *Ille-et-Vilaine: Thourie *Loire-Atlantique: Soulvache *Ille-et-Vilaine: Teillay, Ercé-en-Lamée, Lalleu, Tresbœuf, La Bosse-de-Bretagne, Bain-de-Bretagne, Pancé, Pléchâtel,

Poligné Poligné (; Gallo: ''Polinyae'', ) is a commune in the Ille-et-Vilaine department of Brittany in northwestern France. Geography The river Semnon forms all of the commune's southwestern border. Population Inhabitants of Poligné are called ' ...

, Bourg-des-Comptes

References

Rivers of France Rivers of Loire-Atlantique Rivers of Ille-et-Vilaine Rivers of Mayenne Rivers of Maine-et-Loire Rivers of Pays de la Loire Rivers of Brittany {{France-river-stub