Great Salt Lake: America's Dead Sea

The Great Salt Lake is one of North America's most fascinating natural wonders, and it's hiding some jaw-dropping secrets. You're looking at a lake up to eight times saltier than the ocean, holding roughly 4.5 billion tons of salt with no way out — it's a completely closed basin. Yet it supports millions of migratory birds and unique wildlife. Stick around, because there's far more to this shrinking American treasure than meets the eye.

Key Takeaways

• The Great Salt Lake is the largest saltwater lake in the Western Hemisphere, with salinity reaching up to 27%—eight times saltier than the ocean.
• It formed roughly 11,000 years ago from the remnants of ancient Lake Bonneville, a massive Pleistocene-era freshwater lake.
• The lake holds approximately 4.5 billion tons of salt, with around 2 million additional tons entering annually from tributaries.
• Over 330 bird species visit yearly, including 90% of North America's Eared Grebes population, making it a critical migratory stopover.
• The lake has lost 73% of its water and 60% of its surface area, with some scientists predicting complete disappearance by 2028.

What Makes the Great Salt Lake So Salty?

The Great Salt Lake has no outlet, so when water flows in from the Jordan, Weber, and Bear rivers, it can only leave through evaporation. As water evaporates, it leaves salts and minerals behind — that's the evaporation concentration process working nonstop over thousands of years.

You're looking at roughly 2 million tons of salt entering the lake annually. Those minerals don't go anywhere, making mineral accumulation inevitable. Ancient salts from prehistoric Lake Bonneville add to the mix, compounding what's already there.

The result? Salinity levels ranging from 5% to 27%, depending on the section you're measuring. That's up to eight times saltier than the ocean. Semi-arid Utah summers accelerate evaporation, and the cycle continues — more inflow, more evaporation, more salt left behind. Because the lake sits in a closed basin with no outlet, any reduction in river inflow directly intensifies salinity levels throughout the lake. The lake's watershed spans roughly 22,000 square miles, stretching across northern Utah and into parts of Nevada, Idaho, and Wyoming, funneling an enormous volume of mineral-laden freshwater into the lake with nowhere to escape.

The railroad causeway dividing the lake into northern and southern halves creates distinctly different salinity levels between sections, with the northern half typically registering much higher concentrations than the southern half.

How Did the Great Salt Lake Form?

Understanding how the Great Salt Lake got so salty starts with understanding how it formed in the first place. Its lake origins trace back to the ancient Lake Bonneville, a massive freshwater lake that once covered nearly a quarter of present-day Utah during the Pleistocene ice ages. Around 14,500 years ago, a catastrophic flood drained much of it, and warming, drying conditions shrank what remained. By about 11,000 years ago, a smaller saline body rose to form the modern lake you see today.

Basin tectonics played a vital role. Extensional tectonic stress stretched and cracked Earth's crust, creating a natural depression called a graben. With no outlet, water from the Bear, Weber, and Jordan Rivers collects there, evaporates, and leaves minerals behind — explaining today's extreme salinity. At its greatest extent, Lake Bonneville covered approximately 20,000 square miles, dwarfing the modest body of water that exists in the basin today. Because the lake has no natural outlet, minerals and salt have accumulated over thousands of years, making evaporation the primary mechanism by which the lake loses water.

The lake's sediments hold a detailed archive of this transformation, with researchers analyzing isotope ratios in lakebed cores to reconstruct up to 8,000 years of environmental and watershed history since Lake Bonneville receded.

Can You Really Float in the Great Salt Lake?

One of the most common questions visitors ask is whether you can actually float in the Great Salt Lake — and the answer is a resounding yes.

The lake's salinity ranges between 5% and 27%, making it twice as salty as the ocean and creating effortless buoyancy. This buoyancy demonstration works even at deeper points, where the dense, mineral-rich water holds your body up without any effort.

The sensory experience, however, comes with warnings. Salt stings open cuts, eyes, and mouth, so keep your face clear of the water. Wear old swimwear since salt damages fabric, and use sandals to protect your feet from sharp shoreline crystals.

After drying, expect a visible salt layer coating your skin. The lake holds approximately 4.5 billion tons of salt, accumulated over centuries as water evaporates with no outlet to carry minerals away.

The lake is also home to live brine shrimp, tiny organisms that thrive in the hyper-saline conditions and form a critical part of the ecosystem supporting migratory birds. Much like the Dead Sea, the Great Salt Lake's mineral-rich mud has attracted growing interest for its potential therapeutic and cosmetic applications.

What Wildlife Actually Lives in the Great Salt Lake?

Despite its extreme salinity, the Great Salt Lake teems with life — and it supports one of the most remarkable wildlife ecosystems in North America. Brine shrimp and brine flies form the foundation of the food web, sustaining over 10 million birds annually.

Bird migrations here are staggering in scale. More than 330 species visit each year, including 500,000 Wilson's Phalaropes in a single fall count — 30% of the global population. Eared Grebes can reach 5 million individuals, representing up to 90% of North America's population.

Beyond birds, Antelope Island hosts American Bison, pronghorn, and mule deer. California Gulls maintain the world's largest breeding colony here, with 160,000 nesting birds. The bison roaming the island are descendants of fur trader animals introduced in the 1800s, connecting the lake's wildlife legacy to a rich historical past. The Great Salt Lake isn't barren — it's extraordinarily alive.

The lake's ecosystem also supports migratory routes spanning continents, with food produced here keeping birds alive and able to proliferate along pathways stretching from Alaska all the way to Argentina. The lake also hosts over 400 species of phytoplankton, alongside archaea and bacteria, forming the base of this highly productive biological system.

Why the Great Salt Lake Is Shrinking Fast

The Great Salt Lake is shrinking fast — and the causes are overwhelmingly human. Water diversions from three major tributaries account for roughly two-thirds of the lake's volume decline through 2022. Agriculture alone consumes about 75 percent of Utah's water supply, while a century of upstream diversion has cut inflows by 39 percent since 1850. The lake has lost 73 percent of its water and 60 percent of its surface area.

Climate impacts account for the remaining one-third of the decline. Warmer temperatures have accelerated evaporation, and a 4°F rise in northern Utah since 1900 has intensified the problem. Without this warming trend, 2022 wouldn't have hit record lows. A Portland State University study found that increased evaporation was the critical factor that pushed 2022 to a record low volume. To stabilize the lake, the Wasatch Front must cut water use by more than half.

At the current rate of shrinkage, scientists estimate the lake could disappear by 2028, leaving behind an exposed lakebed that generates roughly 15 large toxic dust storms per year.