He was swept about four miles downstream, spending nearly 30 minutes in the water before being pulled out.
He was spotted by a Los Angeles Police Department officer working a nearby air operations tower.
"It was very difficult to keep an eye on the victim," said Jim Weigh, an LAPD rescue pilot. "A lot of debris swept through the channel."
A helicopter had to maneuver backwards beneath high-voltage power lines to reach him. A firefighter then grabbed the man and pulled him to safety.
Officials said the man was minutes from losing his life because of the frigid water.
It's unclear what the man was doing at the time that caused him to fall into the water.
Fire officials said he had to be treated for hypothermia, but he is expected to be OK.