Its source is on the upper slopes of Mount Corno, at an approximate altitude of 1700 m (5575 ft), and it flows for about 60 kilometers , almost always due north, past the towns of Leonessa, Ocre, Ruscio, Monteleone di Spoleto, Roccaporena, Cascia to Serravalle where it receives the waters of the Sordo; from there the last 11 km in a northwesterly direction to Triponzo, where it flows into the Nera River at 420 m (1378 ft) altitude.