Bagmati is one of the tributaries of Kosi. Baagh means tiger - or here it would be tigress. Baghmati - the intelligence of a Tiger. And Bagmati is exactly like that. A tigress. People in Raxia, Seetamarhi, who live within her embankments, said she is the tigress. One can hear her roar, her garjana, when she is in flood. And at that time she becomes Vyagramati - the tigress.
Bagmati, is also said to be purer than Ganga, more potent. One attains swarg, heaven, when one bathes in her.
One story, narrated by the people in the village, goes like this ...
A Brahman had four sons. 3 of them were like him, competent and well able to lead a prosperous life. The fourth was a loser, a waster who whiled away his time in meaningless pursuits. During one such pursuit, he landed up with a prostitute. And in the night, he was thirsty and asked her for water. Sleepily she told him it was by his bedside and he had to only reach out for it. The Brahman-youth drank deeply and to his consternation found out that it was madira, alcohol !
Being a Brahman, it was great sin to drink madira. (Don't ask why it was not a sin to visit a prostitute !!) Anyways, deeply distressed, he runs to priest to ask for a means to atone his sin. The priest has no answer.
The youth then goes to many, many people asking for a way to atone his sin. And finally in a village comes across a priest, considered by many to be a prankster. This chap hands him a danda, a walking stick, and tells him, that he has to keep walking, be on pilgrimage, until the stick sprouts, and gets an ankur.
The poor, misguided, youth, walks many miles, many years. But nowhere is he able to find his answer. He reaches a riverbank, and tired, lays his stick down, and goes down to her to drink and bathe. When he returns, he finds, lo and behold, that his stick has sprouted and sports an ankur !
The river, it is said, was Bagmati. So potent, that she could sprout even a walking stick.
And the Brahman? Of course, his sins were washed away ... :)