Rescuers searched for two hours before finding the body of Pat Hudgins, 34.
Investigators said Hudgins was fishing with his wife, Tammy, and young cousin, Bronson Murphy.
Murphy said Hudgins groaned and fell into the water. He and the victim's wife jumped in to try and rescue him.
"I didn't think it was really happening when it first happened. All these things started going through my head about what I've been taught in school about what to do. I dialed 911 on the cell phone," Murphy said.
It has not been determined what caused Hudgins to die.
Wildlife officials said Hudgins apparently did not know how to swim and was not wearing a life jacket.
Authorities say they cannot stress enough the importance of wearing life jackets, especially as more and more people start heading out into the water.