The Zadorra region. The great hydrographic network of the Zadorra originates in the foothills of Urbasa, Enzia and Iturrieta, on the south side, and the Gipuzkoa-Alava dividing chain, on the north side. The separation of the Alava plain and the Burunda valley (N) is barely a wrinkle in the terrain. It can be said that the basins of the Arga, in Navarre, and the Zadorra, in Alava, go hand in hand without a hitch. These two natural regions, from the Loiti pass (N) to the Arrato mountain range (A), enclose the geographical basin par excellence of the Basque Country. It is here that Vitoria and Pamplona are located and where almost all the history and art of the country has developed. To contemplate the plains of Alava, we can choose the area of Arlaban, Opakua or the mountains of Vitoria. From any eminence we can glimpse this series of grids that mark the cereals, fodder, potatoes and vegetables. From time to time there are some wooded hills and to the north of Vitoria the Zadorra reservoirs. From Araya and Agurain (Salvatierra) to Vitoria with its dozens of surrounding villages, many of them already trapped by the renovating tentacles of industry. And all around the horizontelas mountains, blue in summer, white in winter. A string of names: Alzania, Aratz, Urkilla, Aitzgorri, Arlaban, Altube, Gorbea, Arrato, Badaya, Tuyo, Vitoria mountains, Iturrieta, Enzia and Urbasa mark the milestones of the great oval of the Zadorra. The beautiful river of Alava, after collecting the waters of Barrundia, plunges into the great Ullibarri Gamboa reservoir. But then it rises, resumes its course and leaves the plain at Trespuentes, where it picks up the Zalla with the waters of the Foronda valley from the foothills of Gorbea. It passes the Conchas de Arganzón and receives the waters of Treviño, an ethnically and geographically Alavese land that is naturally included in the Zadorra basin. It flows into the Ebro near Miranda. The river Zadorra is the river of Alava par excellence, the river of its physical conformation and its history.