The Tons is the largest tributary of the Yamuna and flows through Garhwal region in Uttarakhand, touching Himachal Pradesh. The Tons thrust is named after this river.Its source lies in the 20,720 ft (6,315 meters)) high Bandarpunch mountain, and is one of the most major perennial Indian Himalayan rivers. In fact, it carries more water than the Yamuna itself, which its meets below Kalsi near Dehradun, Uttarakhand.