Cabins dotting the river banks were severely damaged and mobile homes lay on their sides.
Two dozen people were hospitalised and 60 others were rescued but relatives reported more than 73 people missing.
Forecasters had warned of the approaching danger during the night, but campers could easily have missed those advisories because the area is isolated.
John Nichols, a forest service spokesman, said it would have been impossible to warn everyone that the flood was coming - the area has spotty mobile phone service and no sirens.
Mike Beebe, the governor, said damage at the campsite was comparable to that caused by a strong tornado; the force of the water carried one body 13km downstream.