The Bhāgīrathī (Pron: /ˌbʌgɪˈɹɑːθɪ/) is a turbulent Himalayan river in the Indian state of Uttarakhand, and one of the two headstreams of the Ganges, the major river of Northern India and the holy river of Hinduism. In the Hindu faith, history, and culture, the Bhagirathi is considered the source stream of the Ganges. However, in hydrology, the other headstream Alaknanda, is considered the source stream on account of its great length and discharge. The Bhagirathi and Alaknanda join at Devprayag in Garhwal and are thereafter known as the Ganges.

In Hindu texts, Bhagiratha was a descendant of King Sagara of the Suryavamsha, or Solar Dynasty. He played an important role in the descent of the Ganges.^[2] The story of Bhagiratha is narrated in the Ramayana, Mahabharata, and the Puranas.^[3][2]

Wanting to show his sovereignty, King Sagara performed a ritual known as ashvamedha, where a horse was left to wander for one year. However, Indra stole the horse to prevent the ritual from being successful. Learning that the horse had disappeared, King Sagara sent his sixty thousand sons to look for it. They eventually found the horse at the ashram of sage Kapila.^[2] Thinking that sage Kapila had stolen the horse, the sons interrupted him while he was in deep meditation. This infuriated sage Kapila and with his ascetic's gaze burned all sixty thousand sons to ashes.^[2] King Sagara sent his grandson, Amshuman, to ask sage Kapila what could be done to bring deliverance to their souls.^[4]

Sage Kapila advised that only the water of the Ganges, which flowed in the heavens, could liberate them. Bhagiratha, Amshuman's grandson, undertook ascetic practices and won the favour of Brahma and Shiva. Brahma allowed the goddess Ganga to descend upon the earth, while Shiva broke Ganga's fall in the coils of his hair so that her force would not shatter the earth.^[4]

When Ganga descended, Bhagiratha took her through the mountains, foothills, the plains of India, and to the sea where she liberated the sixty thousand sons of King Sagara.^[2] Due to Bhagiratha's role in the descent of the Ganges, the source stream came to be known as Bhagirathi.^[5][6]

The headwaters of the Bhagirathi River are formed at Gaumukh at the foot of the Gangotri glacier. From Gaumukh the river reaches the town of Gangotri. From Gangotri, it travels down a deep gorge and arrives at Bhaironghati. The river continues to travel to Harsil and crosses the Bhagirathi Granite. It then enters a wide valley and meets two tributaries near Jhala. The river continues to flow downwards to Uttarkashi and then through Dharasu, Chinyalisaur, and the old town of Tehri. From Tehri, the river reaches Devprayag via the Himalayas. At Devprayag, the Bhagirathi River converges with the Alaknanda River and travels onward as the Ganges River.^[7]

The Bhagirathi River is mythologically known to be the source stream for the Ganges River. In hydrology, the Alaknanda is the source stream for the Ganges River due to its length and discharge. The Alaknanda River, including its tributaries, is 664.5 km (412.9 mi) and the Bhagirathi River, including its tributaries, is 456.5 km (283.7 mi).^[7]

There are 18 dams along the Bhagirathi River , either in operation, under construction or planned. These are, in order from the source: