The coroner's office has identified the victim as 15-year-old Nixon Quinonez Guerra of San Jose.
He was reported missing after going into the water on Sunday.
The initial call came in around 4:30 pm in the area behind the Firebaugh Rodeo Grounds on 11th and Q Streets.
Investigators say the boy was visiting his family when he went into the water to retrieve a ball and never resurfaced.
Deputies say the teen did not know how to swim and was not wearing a life vest.