The Meng River originates from the "Red Wall" - gorge at 2,390 meters above sea level. It flows through the Gamperdonatal in a northern direction, where it unites in the municipality of Nenzing with the Ill. It reaches a length of 18 kilometers.
The Gampbach with 5 kilometers of length approaches from the right side out of the Gamptal. Gampbach merges in the middle part with the Meng River.