The Fresno County Sheriff's Office's Search and Rescue Team says it happened around 3:30 pm.
Deputies were driving down Piedra Road when a bystander flagged them down, letting them know the woman was stuck in the middle of the river.
The woman was found about 20 yards off the shore in waist-deep water.
A rope was tossed to her and a swimmer helped pull her to shore as the woman couldn't move.
She was safely returned to shore and did not suffer any injuries.