Xallas River through Mazaricos Nature · Mazaricos, Xallas, A Coruña Image of Mazaricos, not of the place itself. The Xallas marks the whole northern boundary of the concello and is dammed at four points, Fervenza, Ponte Olveira, Castrelo and Santa Uxía, which turned its course into a succession of enclosed sheets of water. Photo: Vaneante (CC BY-SA 3.0) What to see and do in Mazaricos