The body Russell Shawver, 51, was found floating in North Fork Buffalo Creek Reservoir around 10 a.m. Tuesday morning.
The reservoir, commonly known as Buffalo Lake, is a popular area for small boat fishing. It's located north of U.S. 287 between Iowa Park and Electra.
"First responders responded and we got on the scene, and there was a white male lying face down in the lake with a boat next to him upside down," said Wichita County Sheriff David Duke.
Another person boating found Shawver's body in a shallow area of the lake about 10 to 12 inches deep.
The Wichita County Sheriff's Office is investigating the case, but at this time the agency does not suspect foul play or drowning as his cause of death.
"The individual was dressed. He had a life jacket on and a heavy coat. He was heavily clothed with the small boat that he had. It appears to us that the boat probably flipped over while he was checking some lines," said Sheriff Duke.
Authorities believe after Shawver's boat flipped over, he tried to walk out of the lake. But due to the cold temperatures, he may have gotten hypothermia and then a possible heart attack.
The Texas Parks and Wildlife game wardens and Iowa Park Volunteer Fire Department assisted in the investigation.
Shawver's body has been sent to the Tarrant County Medical Examiner's office for an autopsy.