The move comes after the man's inner tube was found Tuesday morning, but no sign of the man himself.
Pierce County sheriff's officials said the missing 25-year-old man had been with several buddies floating down the river. But when they reached their destination at about 7:30 p.m. Monday, they realized he was missing.
The group searched themselves for a while, but could not find him.
Finally, at about midnight, they notified authorities, who launched a more intense search. The missing man's friends told deputies they believed he was high on cough medicine.
Search crews worked until about 4 a.m. Tuesday then resumed later in the morning, beginning near 80th Street East and Highway 162. The man's inner tube was found soon after that.
"The problem with this river is it's flowing strong enough and hard enough that it could wash somebody clear out into Puget Sound, but we're going to give it our best shot and see if we can find him," said Pierce County sheriff's spokesman Ed Troyer.
He said the man could still be alive if he managed to get out of the river.
"Unfortunately, he was not wearing a life jacket. So he could be underwater, and we may never find him," Troyer said.