Human remains, including a jaw with teeth still attached, were recovered at Lake Mead on Aug 16 as declining water levels exposed skeletal material.
The US National Park Service received a report and National Park Service rangers together with the Las Vegas Metropolitan Police Department responded to the scene, and the incident remains under investigation.
Two women on a vacation trip found the bones while walking along the Nevada side of the reservoir, just on the border with Arizona.
Dianelis Molina Cruz told CBS affiliate KLAS that her friend noticed the jaw and saw the teeth.
Noel De Leon, the friend, added that the low water levels were likely responsible for bringing the remains to the surface.
Lake Mead water levels have been falling since 2000 and last week dropped to 1,040ft (316m) above sea level, a new record low after July 2022.
The drought in western states, driven by climate change, has exposed more bodies from rivers and lakes worldwide.
In Hungary the Danube exposed the remains of two World War II German soldiers, while a UK reservoir revealed the once flooded village of Nether Hambleton.
Officials are investigating the find; no information yet about its origin or date of death.
