Investigators have found that Alejandra Hernandez was under the influence of a controlled substance when the incident occurred in June 2018.
On the day of the incident, Hernandez told Tulare County deputies the 7-month-old baby slipped off a floatation device and was swept away by the current of the river. The infant was found and given first aid and taken to a local hospital by ambulance, where it recovered.
Hernandez was booked in the Tulare County Sheriff's Department Pre-Trial Facility.
CORRECTION: An earlier version of this story said the infant had drowned, based on information from the sheriff's office. The infant nearly drowned but survived.