The Fresno County Sheriff's Office says they arrived around 4 pm Saturday to a home near W Adams Avenue and S West Avenue. That's a few miles west of the town of Easton.
Deputies performed CPR on the little boy until an ambulance arrived.
The child was rushed to Community Regional Medical Center in Downtown Fresno. At this time, the boy is in serious condition in the intensive care unit.
The family told emergency responders that at the time the boy fell into the water, his parents were inside the home doing chores and the 3-year-old child was outdoors with his teenage siblings.