More human remains were found at Lake Mead,Grant Preston according to officials Saturday.

Park rangers responded to reports of human skeletal remains uncovered at the lake's Swim Beach — the fourth set found at the lake since May.

Park rangers and the Las Vegas Metropolitan Police Department's dive team set a perimeter to recover the remains, officials said. The investigation is ongoing and the county's medical examiner is determining the cause of death.

Located roughly 20 miles east of Las Vegas, Lake Mead was formed by the Hoover Dam, and can hold more water than any other reservoir in the United States. It supplies water to millions of people.

Here's a brief timeline of human remains found in Lake Mead in recent months:

May 1, 2022: Hemenway Harbor

Boaters found a body inside of a barrel after extremely low water levels exposed the bottom of the lake.

Authorities said the person's belongings indicated they had died between the 1970s and 1980s. They believe the person's death was a homicide that resulted from a gunshot wound.

The barrel containing the skeletal remains was found in an area close to the lake's Hemenway Harbor, according to earlier reports from the Associated Press. That's also close to Swim Beach.

May 7, 2022: Callville Bay

Two sisters found skeletal remains at Callville Bay. Clark County Coroner Melanie Rouse believes the remains were from a person between the approximate ages of 23 and 37, according to CNN.

Rouse said this set was more skeletal than the previous remains found, which had organ tissue, CNN also reported.

The cause of death in this case remains unknown.

July 25, 2022: Swim Beach

Reports emerged about another set of remains found at Swim Beach, according to authorities. The investigation is still ongoing and the cause of death has not been identified.

A worsening drought

The newest discovery of human remains found in the lake comes as the reservoir suffers from an ongoing 22-year-long drought.

Lake Mead has hit its lowest water levels since 1937 and is filled to 27% of capacity, according to NASA.

Las Vegas began pumping for its water supply from deeper in the lake because of how depleted the reservoir became, the Associated Press reported in May.

These droughts — exacerbated by climate change — continue to disrupt the West. The area is dealing with its driest period in at least 1,200 years.

Nevada, Arizona and California, along with the federal government, reached a $200 million deal to try to keep more water in Lake Mead this year and next, according to Alex Hager from Colorado's KUNC member station.