Rafter's paddle hit a rock and it jolted the paddler upward which unsecured the left foot and a wall of water knocked her out of the boat. This happened upon approaching the first hole on the upper limits rapid. She got caught in a whirlpool that pulled her under about 5 times then blacked out until waking up to a people screaming to grab a rescue rope. The rescue occurred underneath the 312 overpass/bridge about 3/4 a mile from the beginning of upper limits. The rafting company handled the rescue. Injuries excessive bruised, concussion, minor scrapes, excessive coughing, weakness