In the past, this stretch of river functioned as a mouth, although nowadays it is covered by a sandbar most of the time. Today, the area is practicable in extreme conditions of the river. L'Alfacada, with 194.57 Ha, stands out for the ornithological variety that can be observed there.
At the limit of the continental towers, between the line of Amposta and Sant Carles de la Ràpita, and we find the Ullals de Baltassar...
