Travis County authorities are investigating a death at Lake Travis.

Sheriff's deputies say the man was on a party barge off Starnes Island near Emerald Point.

A witness at the scene said the man jumped from the barge onto a child's floatation device, but became separated from it and went under around 4:20 p.m. They say he didn't know how to swim.

Emergency personnel went in after him.

After 50 minutes, divers found him. Paramedics tried to revive him, but it was too late. He was pronounced dead at the scene.

Deputies say reports of drownings have been low over the past few years, but with the lakes filling up, they remind people to enjoy them with caution.

"The lake is full, and that means that more people are going to come out,” Capt. Art Cardenas with the Travis County Sheriff's Office said. “Please be very cognizant of the dangers of the water."

The name of the man who died won't be released until next of kin are notified and an autopsy is completed.

Multiple rescue crews, including STAR Flight, responded to the scene. Robert Weiss submitted photos of the search and rescue operation.