Omecillo River. The two branches that form this river come from the mountains of Valdegobia, Bóveda, Arzena, Salvada and Arkamo. The western branch, which flows down from the mountains of Bóveda, increases its flow with the streams that descend from Quitanilla and Valluerca. It is joined within Alava's territory by those that flow down from Basabe and Pinedo, near San Millán (B). In Gurendes it is joined by the river Quejo, another stream in Villanueva de Valdegobía and before the two branches of the Omezillo join - near Villanañe - the waters that flow down from Nograro. This other branch of the Omezillo, the Húmedo, rises in Sierra Salvada (B), enters Alava via Osma de Valdegobía, continues via Caranca and downstream from Villanañe joins the Omezillo proper. It continues its course through Espejo and before Bergüenda is joined by the Muera, which comes from Salinas de Añana. A few kilometres further on, in the plain of Bergüenda, it flows into the Ebro.