5th set of human remains found in receding Lake Mead

Another set of human remains were found in Lake Mead near Las Vegas, the second time this month that remains have been found in the country's largest reservoir, officials said Wednesday.

The remains were discovered at Swim Beach in the Lake Mead National Recreation Area around 8:00 p.m. Monday, according to the National Park Service.

With the help of the Las Vegas Metropolitan Police Department's dive team, park rangers responded and set up a perimeter to retrieve the body, the NPS said.

The Clark County Medical Examiner was contacted and is working to identify the person and discover the cause of death, the park service said.

This is the fifth time since May and the second time this month that human remains have been found in Lake Mead, where water levels are receding at a historic rate.

A firearm was also recovered in "close proximity" to where one of the human remains was found, though it is unclear if it is connected, police said Thursday. A journalist discovered the weapon on Wednesday and alerted investigators, police said.

"Although it is not uncommon for firearms to be found at the lake, it is too early to determine whether it is connected to the current investigation," the Las Vegas Metropolitan Police Department said in a statement.

Lake Mead, formed by the Hoover Dam on the Colorado River, supplies drinking water to millions of people in California, Arizona, Nevada and part of Mexico.

Officials said the water levels are so depleted, they could soon reach "dead pool" status, in which the water is too low to flow downstream to the Hoover Dam. According to the U.S. Bureau of Reclamation, the minimum water surface level needed to generate power at the dam is 1,050 feet.

On May 7, human skeletal remains were found near the lake's Callville Bay, according to NPS. The discovery came a week after the decayed body of a man was found stuffed in a steel barrel near the reservoir's Hemenway Fishing Pier, over 20 miles from Callville Bay, according to Las Vegas police.

On July 25 and Aug. 6, human remains were also discovered at Swim Beach.

ABC News' Bill Hutchinson contributed to this report.