The Ganga reached 50.53 metres at Gandhi Ghat in Patna, crossing the highest flood level by 1 cm following a 10 cm rise in four hours.
Bihar's Water Resources Department forecast that water levels at Gandhi Ghat could climb further to 50.62 cm by Sunday morning.
Major rivers including the Ganga, Gandak, Kosi, Burhi Gandak, Bagmati, Punpun, and Ghaghra are flowing above danger marks across Bihar.