Jouanne

The Jouanne is a 58.5 km long river in western France located in the department of Mayenne, region of Pays de la Loire. It is a tributary of the river Mayenne on the left side, and so is a sub-tributary of the Loire by Mayenne and Maine.

History
The name of Jouanne probably goes back to the Gaulish form div-onna (divine-water). The evolution of Divonne is exactly the same as that of divrnus which engendered day in modern French.