Explanation:

Ardh Ganga which is also known as Ardh Gaya or Gupt Ganga. It is a pool full of crystal clear water. It is said that mother Parvati wanted to have bath in the Falgu river at Gaya but that was not possible for the time being. So Lord Ganesha Shot an arrow into earth and water from seven holy rivers including Ganga and Falgu began to ooze out.  Devi Parvati then had a bath in this pool .Today it is believed that having a bath in this pool absolves all the sins of humans.