Boulogne (river)
The river Boulogne is located in western France in the départements Loire-Atlantique and Vendée.
It is 86.5 km in length and flows north from the source near Saint-Martin-des-Noyers, through Les Essarts and La Merlatière, then through Boulogne, Vendée and Les Lucs-sur-Boulogne into the Lac de Grand-Lieu. This lake is drained by the river Acheneau towards the Loire.
Coordinates: 47°05′N 1°40′W / 47.083°N 1.667°W
...
Wikipedia