The Zadorra is a river tributary of the Ebro in the Basque Country at the north of the Iberian Peninsula. The river flows across province Álava all along (with the exception of Burgos' exclave La Puebla de Arganzon) till it pours into the Ebro near Miranda de Ebro in Burgos' lands. The river's water volume is the largest in Álava, with its basin being the most extensive in the province.