A Colorado woman has apparently drowned on the Green River in Dinosaur National Monument after being thrown from her raft while going through a rapid.

The 54-year-old woman, from Craig, was on a private four-day trip down the Green through Lodore Canyon when the raft she was on flipped in the middle of the Triplet Falls rapid Wednesday afternoon, according to park officials.

Members of the rafting party found her unresponsive when they retrieved her from a pool just below the rapid, according to Dinosaur Superintendent Mary Risser. They conducted CPR for approximately an hour before a commercial river rafting group arrived on the scene and provided additional assistance, she added.

The commercial group notified the National Park Service by satellite phone and assisted with transporting the victim to Echo Park, where an ambulance was waiting to transport her.