According to Kashi Khand, Chapter 30, Kashi is a Mukti Kshetra. Long back Yama, Indra and Agni witnessed the devotees in Kashi engaged in religious activities and they drew boundaries for Kashi. All the above Lords, with a view to destroy Asatya (falsehood) and bad thoughts in the Holy City, created Assi River. Then they created Varuna River and made it run through the other end of Kashi.
As per the directions of Lord Shiva, Lord Vishnu proceeded towards Kashi (kindly refer to Padodak Teerth). On reaching Kashi, Lord Vishnu saw the entire kshetra with bird’s eye view. He then went to a place where the Holy Rivers Varuna and Ganga conjoined and washed his hands and feet.
The place where Lord Vishnu’s Charan (feet referred to with respect) were washed came to be known as PADODAK TEERTH. According to Kashi Khand, Chapter 58, devotees who bathe in Padodak Teerth will cleanse all their sins accumulated over 7 births, including the present life.
At the time when the events mentioned in Kashi Khand must have occurred (in Sat Yug), Varuna must have extended upto the present day Trilochan, because the place where Lord Vishnu washed his feet near Varuna Ganga Sangam is Padodak, which is now existing in the form of a well in Trilochaneshwar temple.
Kashi Khand at several places has mentioned the importance of Varuna river. It is believed that devotees who bathe in Varuna-Ganga sangam and worship Varuna Sangameshwar will be blessed with all sorts of prosperity.
South Indian pilgrims who undertake Kashi yatra perform Pancha Ghatta Pindam and one of the places identified for the purpose is Varuna. However, the fifth place where they do the ritual is Trilochan Ghat. This must be because, the area of religious influence of Varuna must be extending upto Trilochan.
However, the devotees are advised to take a boat ride upto Varuna Ganga Sangam and in the process they can also have darshan of Adi Keshav temple alongwith other deities therein.