Rescue team member Mariana Escobar says the six-day effort to free the dolphins finished on Thursday.
The animals had swum from their normal home in the Rio Grande into the more tranquil Rio Paila to breed. Flooding blocked the river and prevented them from returning to their habitat. They were at risk of dying as the dry season lowers the smaller river.
Rescuers caught the dolphin in nets and carried them in padded containers in an all-terrain vehicle to the larger river, where they were released. The dolphins weight about 65 to 90 pounds (30 to 40 kilograms).