Two people then rush to help the shocked woman, who is barely moving.
Shyrleny Cuchallo Ribera, who was in the area with her family, witnessed the terrible accident.
She said: "It is not very common to see this kind of sport here. We saw the lady jumping and for unknown reasons she ended up crashing against the riverbed, as it was not deep enough."
Ribera told media that she and her family went to the nearest town to call an ambulance as the woman was not able to move on her own, and could only open and close her eyes.
"It was so sad to see a young woman in such pain. They should have taken more care with this kind of risky activity," she added.
La Negra bridge lies on the road between Santa Cruz and Cocabamba, in the municipality of Samaipata.
Andean Trek, the company that organised the bungy jump, transferred the woman to a private clinic.
She had a few minor injuries and was discharged a few days later.
Company director Oscar Sandoval said: "The lady jumped from a 15m bridge. The company is paying the medical bills. She does not have fractures, according to the initial diagnosis, but we are awaiting further tests."
He added: "[The accident] was a human mistake. Somebody did something wrong. We are checking the videos in order to know who or what released the brake of the rope.
"It is the first time something like this has happened to us; we have a lot of years of experience."
