The rio Oja is a short River in the North of Spain, which, according to some theories, gives its name to the community of La Rioja in Spain (See etymology of La Rioja ). Born in the mountains of the demand in the Mount of the Herguijuelas, near the port of demand, to about 2,000 meters above sea level. It passes through Inns, Ayabarrena, Antón, Zaldierna, Ezcaray, Ojacastro, Santurde, Santo Domingo de la Calzada, Villalobar, Baños de Rioja, Castañares, Casalarreina, and waters joins the river Tirón before reaching Anguciana, near the town of Cihuri, point from which is known as Río Oja-Tirón to its mouth in the Ebro.El section of the river also receives the name of the row or river Glera, this last term which means accumulation of gravel. This feature of the runway makes it practically disappears in Ojacastro and reappears in chestnut.