Dave Newman, 48, disobeyed repeated orders by emergency personnel to leave the water, police said. He was charged with interfering with public duties.
"I was amazed," Newman said Monday after his release on $2,000 bail. "I had a very uncomfortable night after saving that guy's life. He thanked me for it in front of the police, and then they took me to jail."
Abed Duamni, 35, of Houston, said he had just finished eating at a restaurant Sunday when he decided to go for a swim in a nearby river. Duamni said he didn't see any signs warning swimmers of dangerous currents.
Newman said he pulled Duamni out of the water, swimming under a waterfall and over to the shore opposite from the restaurant. He could hear law enforcement personnel telling him to come back to the other side.
According to police, Newman smirked and seemed annoyed by officers' requests. He stood in the water for about 15 seconds before swimming downstream.
"When he came across the river, the officer stuck out his hand like he's going to help him out of the water, and he put cuffs on him," said John Parnell, pastor of St. Augustine Old Roman Catholic Church in Fort Worth.
The police report does not say anything about Newman having rescued Duamni.
In April, a 22-year-old college student drowned after he and three other restaurant workers jumped from the eatery into the river.