Sutluj river, also known as Sutlej or Satluj, has its source at an elevation of 4,600 m near the Mansarovar lake in Tibet. Sutluj was known to ancient Indians as Shatadru in the Vedic period. From the source the Sutluj flows 300 km to enter India near Shipki La in Kinnaur district. It then cuts through the Zanskar range, and at a place called Khab, is joined by the Spiti river from the west.

Sutluj passes through the Great Himalayan Range, cutting a deep gorge with the Kinner Kailash massif on its left. To the east of the Sutluj the valleys are narrow while in the west, they are wide and open. On the right bank of the Sutluj is the Shrikhand Mahadev range. Here small peaks and glaciers descend to high-altitude pastures.

In the Kinnaur district, the Sutluj valley extends in northeast to southwest alignment for a length of about 140 km. The northeastern part of this valley receives very little rainfall and conditions become humid towards the southwest. At Karcham Sutluj is joined by the Baspa river, which drains the Sangla valley.

From Karcham, for about 30 km the flow of Sutluj is most furious and the construction of various power projects makes this stretch ugly and dangerous. About 4 km down river from Wangtu is the "Pick-Up Dam” for the tunnel of the famous Nathpa Jhakhri Hydel Project.

From here the Sutluj flows for about 200 km to enter the Govind Sagar at Bilaspur where its water is used by the Bhakra Nangal Hydel project. From here Sutluj river enters Punjab and joins Beas river at a place called Harike. It flows from Punjab to Pakistan (where it joins the Indus river) and then to the final destination - The Arabian Sea. Prior to construction of the Bhakra Dam the Sutluj was infamous for its capability to cause frequent damage when in flood.

The fast flow with just the right amount of water makes the Sutluj and its tributaries ideal for being tapped to generate hydroelectric power. The total hydel power potential of Sutluj basin is assessed to be 10,000 mw. The National Highway NH-22 running along the banks of the river gives accessibility. The hydel potential of the river is being harnessed by construction of storage dams in its lower sections and through 'Run of the River' projects in its faster sections.

There is some evidence to suggest the Sutluj was once a tributary of the legendary Saraswati river. It is believed that tectonic activity changed the course of Sutluj from southeast to southwest. As a result, the mighty Saraswati river dried up and caused the abandonment of ancient human settlements along its banks.