It is just 19 kms long, but this river’s fountainhead is one of the most beautiful places in Navarra.
This fountainhead is the «overflow» of an aquifer that sits under Urbasa, where it is estimated that an amount of water accumulated between 1600 and 2500 Hectometers Cubic, which would be about 4-6 times the Yesa reservoir.
And this water comes out of this nacedero to a normal flow of 4.5 cubic meters (= 4500 liters) per second!! At dry seasons it decreases to 0.3 cubic meters per second, but may increase in high rainfall periods up to 50 cubic meters per second, this is 50,000 liters per second!!
(And if you do the math … with that water would fill an Olympic swimming pool in less than a minute!!)