Gangotpatti (Ganga Avataran) is the day to celebrate the descending of Goddess Ganga from her heavenly abode to the Earth. Gangavataran is also known as Ganga Saptami or Jahnu Saptami or Baisakh Ganga Puja.
In 2020, Gangotpatti date is April 29|30.
While descending from celestial region to the Earth, Ganga Devi entered into Jahnu Maharshi’s Ashram and disturbed his penance. He cursed her and drank herand later released from his ear on the request of Lord Shiva and all other Gods. This is the main reason behind Jahnu Saptami or Ganga Saptami.
Due to Jahnu Maharshi’s role in Gangotpatti, this festival is referred to as Jahnu Saptami.