Baltimore Environmental Police said a man was pulled from Prettyboy Reservoir in Baltimore County Saturday.
At 1:45 p.m., Environmental Police responded to a report of a possible drowning at the Prettyboy Reservoir. At the scene, responders found a man who had been swimming at the base of the dam, where swimming is prohibited.
The man suffered a cardiac arrest and was airlifted to Maryland Shock Trauma, where he died later than night, police said.
The rescue was a joint effort from Environmental Police, Maryland State Police Aviation and Baltimore County Fire.