LAS VEGAS — A week after a decades-old body was found in Lake Mead, authorities are working to identify a second set of human remains.

Two sisters from Henderson, Navada, were paddleboarding in Callville Bay on Saturday when they spotted the remains.

Lindsey Melvin told Las Vegas’ KLAS-TV that they thought it was a bighorn sheep. But when they noticed a human jaw, the women immediately called park rangers.

The National Park Service confirmed in a press release they are human skeletal remains.

Las Vegas police say they are not treating it has a homicide case. The remains are currently with the Clark County Coroner’s Office.

The discovery comes after a body in a barrel was found in the lake that encompasses both Nevada and Arizona. In that case, police say the body was 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.

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

Police have speculated that decline in water level could lead to more bodies being discovered.