The Cidacos River is a tributary of the Spanish Ebro River. Its source is Los Campos, in Soria, and it flows for until it reaches the Ebro at Calahorra, La Rioja.
It flows through or past various towns like Villar del RÃÂo, Yanguas, Enciso, Peroblasco, Arnedillo, Santa Eulalia Somera, and Bajera, Herce, Arnedo, Quel, Autol, and Calahorra. The river is used for irrigation purposes and is often dried up near Calahorra.