A white band of mineral deposits stains the mountainsides like the ring on a bathtub, showing where the water was at its high point after a flood in 1983.
"We used to water ski race here," Jaxkxon Zacher told AFP.
"And the island -- only the tip... was out 25 years ago. So now we can't even race here anymore. It's dropping drastically."
The growing islands in the middle of the lake point to the uneven topography of the valley that was flooded -- and the hazards that await.
"Every day someone's ripping a drive off, because last week, where there was no rock, it's now a foot down or two feet down so things are exposed," boatseller Jason Davis said.
"You've got houseboats getting beached and stuck, and people are ripping their lower units off."
And with vessels that can retail at hundreds of thousands of dollars, a weekend outing can turn into a costly mistake.
A NEW JOB
For some people, the risk of an accident and the sheer hassle of having to wait so long to get a boat into the water and then out again at the end of the day means Lake Mead is no longer a viable recreation option.
Below the Hoover Dam, stretches of river remain relatively unscathed by the dropping water levels.
At Willow Beach, across the state line in Arizona, kayakers frolic in the shallows, unloading water pistols on each other as 104 Fahrenheit (40 Celsius) sunshine beats down.
A small marina there offers Steve McMasters a place to stage his pontoon, just a short distance from his home in Boulder City.
"It can be a four-to-five-hour wait on weekends to get your boat out of the water (at Lake Mead), so this is big to have," he said.
"I waited like four months on a waiting list to get it. I got lucky here."
Climatologists say two decades of drought is not unheard of in the western United States, but combined with human-caused global warming, it is transforming the region.
Higher temperatures mean less moisture falls as snow on the Rocky Mountains, and what snowpack does form melts more quickly.
This leaves the Colorado River without the slow and steady feed that supplied it year-round in the centuries and millennia before the region was settled.
In climatic terms, Lake Mead is a baby; in existence for less than 90 years.
But in human terms, it is vanishing at a startling pace.
Jason Davis, the boatseller, says more people need to witness the stark changes for themselves.
"If you haven't come to see these rings, you know, you don't quite comprehend," he said.
And if the water keeps dropping?
"I'll need a new job."
