How big is the Great Salt Lake?

The Great Salt Lake, located in northern Utah, is the largest saltwater lake in the Western Hemisphere and one of the most iconic natural landmarks in the United States. Its size, however, is not fixed. The lake’s surface area fluctuates dramatically over time due to changes in climate, precipitation, and human water usage. These fluctuations make answering the question "How big is the Great Salt Lake?" both fascinating and complex.

Variable Surface Area

At its average size, the Great Salt Lake covers about 1,700 square miles (4,400 square kilometers), but this number can vary significantly. During periods of high inflow, the lake has reached up to 3,300 square miles (8,500 square kilometers)—about the size of Connecticut. In contrast, during droughts or periods of water diversion, the lake has shrunk to just 950 square miles (2,460 square kilometers) or even smaller, exposing vast stretches of salt flats and lakebed.

This variability makes the Great Salt Lake one of the most dynamic large lakes in the world, changing more in size from year to year than many entire lakes change in a century.

Shallow Depth

Unlike deep freshwater lakes such as Lake Tahoe or Crater Lake, the Great Salt Lake is exceptionally shallow. On average, the lake is only about 14 feet (4.3 meters) deep, with the deepest point—found in the northern part of the lake—reaching around 33 feet (10 meters) when the lake is full. This shallow depth contributes to the rapid fluctuations in surface area, as even slight changes in water volume can result in significant changes in shoreline.

Divided by Causeways

The Great Salt Lake is divided into several distinct arms by railroad and highway causeways, which alter the lake’s hydrology and salinity. The most prominent of these is the Southern Pacific Railroad causeway, which separates the north arm (known as Gunnison Bay) from the south arm (Gilbert Bay).

The north arm receives little to no freshwater inflow and is much saltier—approaching saturation levels of 25–30% salinity.

The south arm receives freshwater from the Bear, Weber, and Jordan rivers and is therefore less salty, though still much saltier than seawater.

Historical and Modern Extremes

Throughout recorded history, the lake has experienced a range of sizes:

Historic high: In 1986–87, the lake reached its modern historical peak of about 4,400 feet (1,341 meters) in elevation and more than 3,300 square miles in area. Flooding at this time threatened roads and infrastructure, leading to the construction of massive pumps to divert excess water to the Bonneville Salt Flats.

Recent low: In 2022, due to prolonged drought and upstream water diversions, the lake shrank to its smallest size on record, with water levels dipping below 4,190 feet (1,277 meters). Its surface area dropped to less than 1,000 square miles, exposing dry lakebeds that emitted hazardous dust and threatened local ecosystems.

Ecological and Economic Importance

Despite its salty waters, the Great Salt Lake is a vibrant ecosystem. It supports millions of migratory birds, including American avocets, phalaropes, pelicans, and seagulls, and sustains commercial brine shrimp and mineral extraction industries. The lake’s size directly influences these systems; a smaller lake concentrates salinity, affects food webs, and shrinks crucial wetlands.

A Lake in Peril

The shrinking of the Great Salt Lake in recent decades has raised serious environmental and public health concerns. A smaller lake means:

1. Increased salinity, potentially collapsing ecosystems.
2. Dust storms from exposed lakebed, which contain toxic elements like arsenic.
3. Threats to wildlife, especially millions of migratory birds that rely on the lake as a critical stopover.

Scientists, lawmakers, and environmentalists are now focused on finding sustainable solutions to preserve this invaluable natural resource.

Conclusion

The Great Salt Lake is both large and shrinking—a paradox that underscores its complexity. It is a lake of extremes, where size is measured not just in square miles, but in its significance to Utah’s ecology, economy, and identity. Understanding how big the Great Salt Lake is requires not only looking at numbers but also recognizing its vulnerability in a rapidly changing world.