The Giri Ganga rises from near Kupar peak just above Jubbal town in Shimla district, Tons from Yamunotri and Pabbar from Chandra Nahan Lake near the Chansal peak in Rohru tehsil of Shimla district. Its total catchment area in Himachal Pradesh is 2,320 km. It leaves the state near Tajewala and enters into the Haryana state.
The area drained by the Yamuna system includes Giri-Satluj water divide in Himachal Pradesh to the Yamuna Bhilagana water divide in Gharwal.