He declined to discuss a cause of death and declined to describe the items found, saying the investigation is ongoing.
Police plan to reach out to experts at the University of Nevada, Las Vegas to analyse when the barrel started eroding. The Clark County coroner's office will try to determine the person's identity.
Boaters spotted the barrel Sunday afternoon. National Park Service rangers searched an area near the lake's Hemenway Harbor and found the barrel containing skeletal remains.
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.