Utah's Fabled Great Salt Lake Is Shrinking

"GSL is what's called a terminal lake. It means there's no outlet leading out of Great Salt Lake," explains Jaimi Butler, a field biologist at Westminster College in Salt Lake City.

Fresh water flows into the lake through the Bear, Webber and Jordan rivers, among other routes. However, unlike a body of water such as Lake Superior, for example, the Great Salt Lake isn't connected to any outgoing waterways.

"There are 22,000 miles (35,405 kilometers) of watershed and they're all draining into this basin that is Great Salt Lake," notes Butler. "The only thing that can leave is water through evaporation."

This incoming water naturally carries small amounts of salt and other minerals along for the ride. Yet in a terminal lake such as the GSL, those materials have no place to go. Unlike the water which ferried them over, they can't just evaporate away. So over time, they accumulate — making the lake saltier and saltier.

"The Great Salt Lake proper is this hypersaline lake that has two pieces; there's a north arm and a south arm," says University of Utah geologist William Johnson.

Separating the two is the Southern Pacific Transportation Co. (SPTC) causeway. Finished in 1959, this railroad cuts right through the Beehive State's signature lake.

Being a solid structure full of rocks, it doesn't allow much water to circulate between the northern and southern ends of the lake.

According to an article Johnson and his colleagues wrote for the book "Encyclopedia of Water: Science, Technology, and Society," over 90 percent of all the freshwater runoff that the Great Salt Lake receives enters the south arm.

With the SPTC causeway now impeding its water flow, the north arm is not only denser, but it also has an incredibly high salinity ("salt content") of 16 to 29 percent. Compared to the south arm — whose salinity can fall into the single digits — this is a pretty intense environment.

Apart from the north and south arms, the Great Salt Lake includes a handful of bays, like Farmington Bay and Bear River Bay. Most of these are attached to their own wetland systems.

"In some ways, it's really five lakes that are interconnected," Johnson tells us — although he points out that Farmington Bay is "no longer a bay, it's just a stream that's flowing in."

Between the bays, the arms and the incoming water sources, salinity levels vary widely across different parts of the Great Salt Lake. "The GSL is one of the most diverse places on the planet in terms of salt content," Butler says. "It goes everywhere from fresh water to saturated with salt and everything in between."

Which brings us to one of Google's most frequently asked questions about the Great Salt Lake: Are there any fish inside?

"No fish live in the lake," says Michael Vanden Berg of the Utah Geological Survey in an email. "Sometimes, fish will enter the lake via one of three rivers, but will die shortly after. When lake levels are high, fish might be able to survive in places like Farmington Bay (east side of Antelope Island), but can't survive in the lake proper."

None of this is to say that the Great Salt Lake is a desolate, lifeless place. On the contrary: It's a birdwatcher's paradise.

An estimated 17 trillion brine shrimp reside in the GSL, making them an abundant food source for birds. The tiny invertebrates grow up to half an inch, or 1.27 centimeters, long when mature. They periodically lay nutritious eggs called "cysts," which also get eaten. Local brine flies and their larvae make convenient bird snacks as well.

In turn, these little creatures eat algae. By the way, many of the native algae and bacteria species release colorful pigments into the lake.

"Microbes ... can live anywhere and the north arm has so many microbes in it that are colored pink and red and orange that the water looks like pink lemonade," says Butler. South of the SPTC causeway, you'll see green-tinted waters, courtesy of green algae.

The Utah state government's official website reports that, annually, "10 million birds from 338 different species come to rest, eat and breed" at the Great Salt Lake. For birds like the eared grebe, it's an essential pit stop on their long migration routes.

Butler tells us that 5 million of these grebes, or "95 percent of the world's population," visit the GSL each year. "There's plenty of brine shrimp and resources for them to eat, even after people harvest [the shrimp] and their eggs for use in aquaculture," she notes.

Then we have the American white pelican, a charismatic bird that treats the GSL's Gunnison Island like a giant nursery. "They nest in the saltiest part of Great Salt Lake on this island," says Butler. Until recently, high water levels kept most predators out. "They trade food for a safe place to raise their young, even if it means traveling 30 to 60 miles [48 to 96 kilometers] to catch fish."

Over the past few years, receding shorelines have turned Gunnison Island into a peninsula, where hungry coyotes are now free to wander.

White pelicans have taken notice; in 2019, a preliminary survey found 3,414 pelican nests on Gunnison. That's 66 percent fewer than the 10,000-plus nests documented there in 1992.

What accounts for this downward trend? And why are water levels in the Great Salt Lake hitting record lows this year?

The usual suspects of drought and climate change aren't helping. Another factor — and a major one, at that — is the deliberate removal of fresh water from the GSL's natural sources. "The diversion of water for culinary and other uses is depleting the lake. That's a fact," says Johnson.

"Right now," Butler adds, "the lake is essentially half the size that it would be if we hadn't been diverting water."

"This issue ... affects everybody," she tells us. "I have hope that if we start to take action, good things will follow and there won't be an environmental catastrophe in my backyard."