Berre-l ' Ã tang is a commune of 14,300 people ( 2005 ) . It is found in the region Provence-Alpes-C Ã te d'Azur in the Bouches-du-Rh Ã ne department in the south of France . Berre-l ' Ã tang is a commune in the Bouches-du-Rh Ã ne department in the Provence-Alpes-C Ã te d'Azur region in southern France .