The Nevada city's former mayor, Oscar Goodman, told The Associated Press on Monday that the reservoir is "not a bad place to dump a body."
"There’s no telling what we’ll find in Lake Mead," he said.
A few days later, a second, empty barrel was found by a KLAS-TV news crew.
On Saturday, National Park Service (NPS) rangers received a witness report of human skeletal remains discovered at Callville Bay. Las Vegas police said Monday that there was no immediate evidence of foul play and that they are not investigating.
Lake Mead has dropped more than 170 feet since 1983, and the uppermost water intake became visible last week.
Persistent drought is predicted to expand this year, amid warmer temperatures.
Goodman – who was previously a lawyer, representing mob figures including the ill-fated Anthony "Tony the Ant" Spilotro – declined to name names about who might turn up next.
"I’m relatively sure it was not Jimmy Hoffa," he joked, but noted that a lot of his former clients seemed interested in "climate control."
Geoff Schumacher, vice president of The Mob Museum, said that the barrel was a "signature of a mob hit."
David Kohlmeier, a former police officer who now co-hosts a Las Vegas podcast and TV show called "The Problem Solver Show," said Monday that, after offering a $5,000 reward last week for qualified divers to find barrels in the lake, people contacted him who were willing to do so.
The NPS said that's not allowed and that there are hundreds of barrels in Lake Mead's depths.
Fox News' Louis Casiano, Bradford Betz and The Associated Press contributed to this report.