In Jyestha month, Shukla pksha, dashami tithi, Hasta Nakshatra, Tuesday, king Bhagirath, riding on chariot, blowing his Shankh was ready for Ganga's arrival on Earth, in Himalayas.
Before that angry Ganga in her great force, fell on Shivji's Jata. She was searching for a way to come out of his Jata. Bhagirath prayed to Shivji to release her. Ganga to prayed Shivji to let her go on earth for welfare of animals & humans on Earth. Hearing this Shivji opened his jata, allowing her to go.
Pritvi appeared before Bhagirath, wanting to meet Ganga. Hearing Shankh naad, Ganga with full force came to Meru parvat. Ganga had told Bhagirath she will follow his shankhnaad & follow him. Prithvi met Ganga, wished for her presence in all 4 directins, till the Ocean. Ganga said without Bhagirath's wish she will be unable to do so. Bhagirath requested her to fulfill Prithvi's wish. Ganga divided her flow in 3 directions, South, North & East. She then went to South following Bhagirath.
Indra with other Devatas appeared before Bhagirth, prayed Ganga to remain in Swarga too. She agreed to remain in Swarga as Mandakini river.
Then she follwed Bhagirath in South. He stopped seeing Sumeru parvat on the way, asked her how will he be able to take her further? Ganga told him, she will wait here, he should go to the other side of this parvat & blow his Shankh loudly again, she will come with full force from top of this parvat & follow him.
She reached Haridwar. Saptarishis worshipped her, blowing shankh in 7 directions. Hearing Shankh naad, Ganga went in 7 directions in 7streams, going to Prayag & merged with Yamuna & Saraswati. In East She went to Kashi, where Kaal-bhairav worshipped her.
She them moved to Kamakhya peeth. In East. Knowing her desire to go to Kamkhya peeth, Bhagirath stopped his Shankh for some time.
At that time rishi Jahnu blew his Shankh, hearing that Ganga with full force went to his aashram. Bhagirath blew his Shankh again seeing her going in other direction. Hearing the familiar voice Ganga realized she is following wrong sound. With anger she went to the aashram to blow it away with her. Jahnu rishi realized this. With his Brhmatej, he drank entire Ganga. Everyone was worried. Bhagirath was quiet unhappy, so was Prithvi. Seeing Bhagirath in such state, Ganga told him to blow his Shankh again loudly, no one will be able to stop me. Bhagirath did the same, hearing the Shankh naad, Ganga came out of Jhnu rishi's thigh. He worshipped her. Pleased Ganga told him since I have come out of you, I am your daughter, I'll be known as Jhanvi.
She then asked Bhagirath the direction they have to go now. He told her his ancesters are in the South. She followe hin to South. Bhagirath was tired by now, he stopped on the way.
During this time, Jahnu rishi's daughter Padma wanted to see Ganga, she blew Shankh. Hearing that Ganga went in that direction. Seeing her going Bhagirath, asked his charioteer to follow her. Even he blew his Shankh, Ganga once again flowed Bhagirath. Due to this Padma got angry, started flowing as a river, went to East & merged with the Ocean.
Ganga went with her great force to South, near the ocean. Ocean worshipped her, she merged in the Ocean, coming out from the Ocean she went to Kapil muni's aashram in Patala-loka, where Sagar's sons were in form of ash. She blew their ash with her on Earth, freeing all the ancesters of Bhagirtah. He prayed her saying Jay Gange. She stayed in Patal-loka as Bhogakti.
From Devi Puran.