Lake Mead near Las Vegas was once the largest man-made reservoir in the United States.
For several months, the drought in America has dropped the water level to historically low levels - human remains have now appeared for the fourth time in a few weeks, as the American broadcaster CNN reports.
Park rangers received a call last Saturday informing them that skeletal parts had been found on a stretch of beach.
Three more bodies or parts thereof have been discovered in the lake since May, including one dead in a barrel with a gunshot wound to the head.
Police believe the man was killed in the mid 1970s to early 1980s.
The exact time and the identity of the corpse could not be determined due to the state of decomposition.
Rumors that the lake, which lies on the Nevada-Arizona border, were used by mob members as a dumping ground for bodies, a Las Vegas Metropolitan Police homicide detective denied to CNN.
Only in the case of the corpse in the barrel does the homicide detective investigate.
A National Parks Service spokesman told CNN that one possible explanation for the bodies is that people drowned while swimming when water levels were higher.
The authorities had already announced in July that a boat dating back to the Second World War had reappeared in the lake itself.