The US’s largest water reservoir, Lake Mead at the Hoover Dam, is in very, very bad shape. How bad is it? New satellite images from NASA show just how much the reservoir’s footprint has shrunk over the past two decades — and the difference between July 2000 and July 2022 is stark.

Water levels at Lake Mead are at a historic low — the reservoir hasn’t been this empty since 1937 when it was being filled for the first time. It’s currently at just 27 percent capacity. The last time it was close to full capacity was 1999, just one year before the image on the left of the slider below was taken.

Image: NASA Earth Observatory / Lauren Dauphin and Image: NASA Earth Observatory / Lauren Dauphin

The water elevation at the Hoover Dam stood at a meager 1,041 feet on July 18th, 2022, according to the Bureau of Reclamation, which manages Lake Mead. That’s a scary number because, once it drops below 1,000 feet, it will affect the dam’s ability to operate its hydropower turbines. The dam typically provides power to 1.3 million people in Nevada, Arizona, and California.

That’s not the only trouble at Lake Mead. Last year, officials declared a water shortage there — the first time such a declaration had ever been made along the Colorado River system. Forty million people depend on the system for water across the southwestern US and northwestern Mexico. At the time, water levels at Lake Mead had dropped to 1,071.57 feet. The water elevation is already even lower than that and is predicted to drop another 20 feet by next summer.

Long-term drought made worse by climate change has sucked the reservoir dry. In the chart below, NASA plots out what that’s looked like over the past 2022 years. More than 80 percent of the Western US is currently “abnormally dry,” according to the US Drought Monitor. Well over a third of the region is coping with “extreme” or “exceptional” drought.

Image: NASA Earth Observatory / Lauren Dauphin

Vanishing water at Lake Mead has left behind what’s euphemistically called a “bathtub ring.” You can see it pretty well in the images below that zoom in on one section of the reservoir. The pale fringes surrounding the water that remains are places where water left behind calcium carbonate and other minerals — showing where the high mark used to be.

Image: NASA Earth Observatory / Lauren Dauphin

The receding water is uncovering the reservoir’s secrets — sparking treasure hunts and even murder mysteries. A body found in a barrel this year is suspected to be the victim of a mob hit in the 1980s, The Washington Post reports. (Las Vegas is nearby.) Tourists have also started scouring the lake in search of jewelry and other valuables, the Post reports. That’s only if they can manage to get on the water — five of six boating ramps are closed and cars are reportedly getting stuck in the mud along the lake’s shrinking shores.