It springs on the southern slopes of the Cantabrian mountain range (province of Palencia, autonomous region of Castile-Leon) and flows south into the Douro river shortly after passing through the city of Valladolid. Its length is approximately 270 km.
Since the 1950s the water level of the river has been very regular throughout the year due to the huge Aguilar de Campoo dam which collects all the water from the river's rainy upper valleys. This regulation has allowed the creation of vast extensions of irrigated farmland along the Pisuerga's course across the northern Castilian plain.