Body in barrel in Colorado River was man who had been shot - police

The top of Lake Mead drinking water Intake No. 1, that provides Las Vegas with 90 per cent of its drinking water supply. Photo / AP

The body found inside a barrel on the newly exposed bottom of Lake Mead after the lake's level was depleted amid drought is that of a man who had been shot.

The killing probably happened between the mid-1970s and the early 1980s because the victim was wearing shoes that were manufactured during that period, the Las Vegas Review-Journal reported.

The barrel was found in the Lake Mead National Recreational Area by boaties, who informed authorities.

Drought has dropped the water level of Lake Mead on the Colorado River in southern Nevada and northern Arizona so much that the uppermost water intake of Las Vegas became visible last week.

Maintenance mechanics install a spacer flange at Lake Mead National Recreation Area. Photo / AP

Lake Mead and Lake Powell upstream are the largest human-made reservoirs in the US, part of a system that provides water to more than 40 million people, tribes, agriculture and industry in Arizona, California, Colorado, Nevada, New Mexico, Utah, Wyoming and across the southern border in Mexico.

The Clark County coroner's office will try to determine the man's identity.