They said water levels reached unprecedented levels at four locations in northern India.
The highest record was in Patna, the state capital of Bihar where flood waters reached 50.52m (166ft) on August 26, up from 50.27m in 1994.
Floods across India this year have killed more than 150 people and displaced thousands.
“We have also recorded unprecedented flood levels at Hathidah and Bhagalpur of Bihar state and Balliya of Uttar Pradesh,” chief of India’s Central Water Commission GS Jha said.
“In all these four places, the floods crossed the previous highest flood level and they all were unprecedented.”
Bihar is one of the worst flood-hit states in India with at least 150 deaths and nearly half a million people evacuated.
Neighbouring Uttar Pradesh has also been severely affected by floods in the Ganges.
The third largest river in the world flows through these north Indian states meeting its tributaries before emptying into the Bay of Bengal.
The Indian Meteorological Department, however, has recorded deficient rainfall in these states past week and average rains since the monsoon started in June.
Some experts have blamed the silt the river carries for the floods. The Ganges is one of the highest sediment load carrying rivers.
The silt deposition is said to have raised the river’s bed-level causing it to break embankments and flood the adjoining human settlements and farmlands.
Officials in Bihar have demanded that an artificial barrier in neighbouring West Bengal state bordering Bangladesh be dismantled to solve the silt problem.
They argue that the deposition of silt has obstructed several passages through the Farakka barrage.
As a result, they say, the Ganges’ water flows back to Bihar and causes floods.