The hiker has apparently misjudged the speed of the water as he tried to cross Angel Falls in California, police say, and was caught in the cold spring water flowing 50 to 80 feet per second.
Nearby California Highway Patrol Officer Brent Donley, who is trained in search and rescue, also walked in the area near Bass Lake in Madera County.
Donley used a strap from his backpack and tied it around a branch so the hiker could grab it, police say. He threw the man's branch and then talked him through the rescue, according to a video released by California Highway Patrol Fresno.
With the help of a group of other hikers, Donley pulled the man, who has not been named, to safety. He provided first aid to the search and rescue crews.