The stampede at Haridwar in Uttrakhand state was triggered when some of the pilgrims tripped and fell while those behind continued to push forward, government spokesman Amit Chandola said.
Thousands of people had converged on the river banks for the prayer ceremony in the temple-filled town in the foothills of the Himalayas where the Ganges enters the sprawling plains of northern India. Haridwar is about 300 miles (500 kilometers) southwest of Lucknow, the capital of Uttar Pradesh state.
Chandola said police had recovered 16 bodies from the site, and that about 50 injured people were taken to a nearby hospital.
Hundreds of thousands of Hindu pilgrims visit Haridwar every year for bathing in the Ganges, which they believe will cleanse them of sins and free them from the cycle of life and rebirth.
Stampedes often occur at Hindu pilgrimage sites, where authorities are unable to cope with the rush of devotees.