The great Salt Lake. This picture was take away by an astronaut plank the International room Station in the summer of 2001. (Image credit: NASA earth Observatory)
Great Salt Lake, in northern Utah, is the biggest lake west that the Mississippi River and also the largest salt lake in the western Hemisphere. Occasionally referred to as America’s Dead Sea, it is nonetheless a critically essential habitat for numerous native and also migratory birds and also is a federally regulated bird refuge. It is likewise home to several varieties of algae, brine shrimp and brine flies.

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Great Salt Lake includes several islands, causeways, a railroad, 3 state parks and an earthwork sculpture called the Spiral Jetty. The lake is a popular recreation area, through hiking, sailing and also swimming available.


Great Salt Lake is typically bigger than the states of Delaware and also Rhode Island, according to the U.S. Geological inspection (USGS). The dimension changes, however, together water level rise and fall. The lake is just 14 feet (4 meters) deep on median so a foot that water loss deserve to make a large difference in its full size.

These are the median dimensions of good Salt Lake, according to USGS, friend of an excellent Salt Lake, and also the college of Utah.

Surface area: 1,700 square miles (4,402 square kilometers) top top an mean yearLength: 75 mile (120 km)Width: 28 mile (45 km)Average altitude the the water surface: 4,200 feet (1,280 meters)Maximum depth: 33 feet (10 m)Average depth: 14 feet (4 m)Total watershed area: 21,000 square miles (54389.75 square km), encompassing many of northern Utah and also parts of Nevada, Idaho and also Wyoming.Record high water level: In 1986, the altitude in ~ the water surface ar was 4,212 feet (1,283 m) and also the lake’s full surface area was 2,300 square mile (5,956 square km).Record short water level: In 1963, the altitude at the water surface ar was 4,191 feet (1,277 m) and the lake’s total surface area to be 937 square mile (2,426 square km).


Great Salt Lake lies in a an ar of the Western united States referred to as the good Basin. The Wasatch range rises come the east of the lake, with number of 11,000-foot mountains. The great Salt Lake Desert is west the the lake. It attributes a level expanse the salt crust called the Bonneville Salt Flats, which has ideal problems for attempts to rest land-speed records.

The lake is a remnant the Lake Bonneville, an ancient, freshwater lake indigenous the last ice Age, said Bonnie Baxter, manager of the an excellent Salt Lake Institute and also a professor that biology in ~ Westminster college in Salt Lake City. Lake Bonneville to be 325 miles (523 km) long and 135 mile (217 km) vast and 1,000 feet (308 m) deep.

Lake Bonneville formed around 30,000 years ago from a small saline lake. Virtually 17,000 years ago, Lake Bonneville overflowed at Red Rock pass in Idaho and also a yearlong overwhelming ensued. The lake lost about 375 feet (114 m) the water, according to the USGS. Lake Bonneville underwent several durations of shrinking and stabilizing. These changes were as result of increased evaporation and also a warming climate. There room four various shorelines visible together ridges on Utah’s Wasatch Mountains. The Bonneville Salt Flats in west Utah space a remnant of Lake Bonneville.

The modern great Salt Lake emerged about 10,000 year ago. Local aboriginal American people knew about good Salt Lake, of course. The an initial non-native human to view the lake is claimed to be explorer Jim Bridger in 1824, according to the Utah geological Survey. The first thorough expedition of the lake was by a party led by man C. Fremont in 1843. On the expedition, Kit Carson visited one of the lake"s islands and also carved a cross near the summit of an island that is now dubbed Fremont Island. Members that the Church the Jesus Christ the Latter-day Saints (or Mormons) come in the area in 1847 and used the islands because that grazing cattle and likewise enjoyed swimming in the lake and holding picnics on its shores.

On may 10, 1869, the Transcontinental Railroad was completed on the Promontory Peninsula ~ above the north end of an excellent Salt Lake. Though momentous, this wedding of the rails was no efficient; great Salt Lake had caused the designers to build a detour onto the rugged hills of the peninsula. In 1902, the southerly Pacific built an east-west wooden railroad trestle across good Salt Lake dubbed the Lucien Cutoff, i m sorry bypassed Promontory Peninsula completely, follow to American Rails. In 1959 the wooden trestle was changed with a rock-fill causeway that is still in use today.


As Lake Bonneville shrank, every one of the mineral in that — including salt — concentrated into steadily much less water. Every year, 2.2 million tons (1,814, 369 metric tons) the salt operation into great Salt Lake indigenous tributary rivers, follow to USGS. “This build-up of minerals and no outlet to the ocean results in a salt lake,” claimed Baxter.

“Terminal lakes are regularly salty,” she called Live Science. “Water evaporates, however salt continues to be behind and also accumulates. A terminal lake holds whatever that has ever gotten in the lake other than water, which deserve to leave through evaporation.”

Great Salt Lake is a sodium chloride lake, stated Baxter. The hypersaline north arm (also dubbed Gunnison Bay) is around 30 percent salt. The southern portion of the lake (also referred to as Gilbert Bay) fluctuates in between 6 and 27 percent salinity. About 4.3 billion tons (3,628,738,960 metric tons) of salt are in good Salt Lake.

As with plenty of other saline lakes, including the Dead Sea, that is possible to rise in an excellent Salt Lake.


An aerial shot reflects the causeway the divides the northern and also southern parts of the an excellent Salt Lake. The rosy shade of the northern waters is the result of the pigmented, salt-loving microbes. (Image credit: Courtesy of an excellent Salt Lake Institute)


Great Salt Lake has three feeders: the Bear, Weber and also Jordan rivers, follow to an excellent Salt Lake info System at Utah State University. These rivers lug fresh water indigenous melted snow in the Wasatch Mountains into the east area that the lake. Sixty-six percent of fresh water beginning the lake comes from these rivers. Added fresh water originates from rainfall, groundwater and also springs, according to an excellent Salt Lake Ecosystem Program. No feeders reach Gunnison bay in the northwestern part of the lake. The western component of the good Salt Lake watershed is desert and also does not bring water into the lake except in very wet years.

There room 11 islands in great Salt Lake, including the 28,800-acre (116 square km) Antelope Island, i beg your pardon is house to a state park and also one the America’s largest free-roaming herds that bison, follow to the Utah State Parks. Gunnison Island is house to a huge population the pelicans. Number of of the bigger islands in the southern part of good Salt Lake, consisting of Antelope Island, come to be peninsulas as soon as the water level is low. The Promontory Peninsula, residence to the golden Spike National historic Site, divides Gunnison just from the rest of the north area of the lake (also called Bear flow Bay).

Willard only is a human-made freshwater reservoir top top the northeastern flood plains of great Salt Lake, according to Utah State Parks. The area to be separated from good Salt Lake in 1964 and is currently a state park.

The Spiral Jetty is a substantial earthwork sculpture ~ above the north shore of an excellent Salt Lake. Earthwork artist Robert Smithson developed it in 1970. Smithson used much more than 6,000 lots (5,443 metric tons) of black basalt rocks and also earth dug up from the site to develop a 1,500-foot-long (457 m) spiral that extends into the water, follow to Dia Art. The is visible once the water level is listed below 4,197 feet (1,279 m) altitude.

The Union Pacific Railroad north Causeway is 21 miles (33 km) long and also was constructed as a railroad shortcut. The divides Gunnison Bay, the north arm that the lake, native Gilbert just in the south, according to girlfriend of great Salt Lake. Human-built features like causeways and also dykes impede water flow, which creates microenvironments, said Jaimi Butler, coordinator that the good Salt Lake Institute. The clearest instance of this is in the far north of the lake, whereby the Union Pacific Railroad northern Causeway blocks freshwater flow and has produced a super-saturation of salt and severe environment.

“Not plenty of things live increase there, and also the microbes that execute are pink or red,” said Butler. “Their red pigments assist them deal with the harsh environment.” together a result, the water is often pink colored.

Mineral extractionis a significant economic attribute of an excellent Salt Lake, stated Butler. According to USGS, 5 businesses extract salt and also other minerals from the lake v solar evaporation ponds. No food-grade salt comes from the lake; good Salt Lake salt is offered for deicers, roadway salt, water softeners and salt licks for livestock. Additionally, said Butler, a substantial brine shrimp harvest occurs every fall. The brine shrimp are primarily sent come Asia and South America where they are offered as feeders because that commercially grown prawn and also fish.

Among Utah residents, great Salt Lake is renowned for sometimes emitting a stench prefer rotten eggs. It is caused by hydrogen sulfide, which certain types of bacteria in the lakebed breath out into the air. Though the odor annoys humans, butler emphasized the it is simply “microbes doing your job. They space transforming energy into some other form that is helpful to the birds and also the bugs.”

Oolitic sand is pill-shaped sand widespread on the bottom of an excellent Salt Lake and also several beaches. It is soft, smooth and also round unlike constant sand the is jagged-edged, according to great Salt Lake Ecosystem Program. A serial of oolitic sand begins as a brine shrimp fecal pellet or other little bit of debris. Calcium and also magnesium lead carbonate particles build up around it, creating oolitic sand and also separating brine shrimp waste from the rest of the water. In this way, oolitic sand attributes as a filter for great Salt Lake.


Great Salt Lake has actually a vibrant and unique ecosystem. It is most famous as an essential refuge for moving birds. “Great Salt Lake is the largest inland human body of water on the Pacific flyway,” described Baxter. “This is a crucial habitat for migrating birds to feed and grow in prior to they move on. There are just two invertebrates in the lake, brine shrimp and brine flies, but the numbers of these types provide an exceptional amount of food because that these birds.”

The size of that wetlands and also the diversity of that aquatic environments also make good Salt Lake appeal to countless different bird species. Some room the American avocet, phalarope, bald eagle, barn owl, earn grebe, gold eagle, north harrier and also snowy plover, follow to an excellent Salt Lake Marina.

“We have one that America’s biggest pelican populations,” included Butler. “Pelicans eat fish but they nest in Gunnison Island, in the northern arm of the lake that has 10 time the amount of salt together the ocean. They swarm there due to the fact that it’s remote and there space no predators on the island.”

According to great Salt Lake Ecosystem Program, an ext than 7.5 million birds in 257 varieties either stop at an excellent Salt Lake top top their migrations of live in ~ it, consisting of one-third the the world’s populace of phalaropes (500,000 birds).

Brine shrimp room the many populous pet in good Salt Lake. These small crustaceans live in salt water around the world, yet only one species, Artemia franciscana, resides in good Salt Lake. They measure up to 0.5 inch (1.37 centimeters) long and also can live in water v up to 33 percent salinity, according to good Salt Lake Ecosystem Program. Lock can regulate how much salt gets into their human body tissues far better than any type of other biology on Earth due to skin lining your stomachs and also gills. Scientists suspect the they initially came to great Salt Lake as embryos in protective shells on the feet of migrating birds.

There space at least three species of brine paris that flourish at good Salt Lake. Scientists estimate that there might be billions that brine paris swarming about the lake throughout the summer, follow to good Salt Lake Ecosystem Program. They room visible as swarms of tiny brown insects, however they do not bite. In their larval state, theyeat birds blooms in the water.


There are plenty of threats to an excellent Salt Lake, claimed Butler, but by far the most pressing is water loss. Due to the fact that 2011, an excellent Salt Lake has shrunk by virtually 40 percent. In November 2016, NASA exit satellite photos demonstrating the decline. Around 50 percent the the lake bed is currently exposed.

The West is in a drought cycle that, compounded through warming temperature in Utah and surrounding states, outcomes in much less snowpack and precipitation, and, subsequently less water entering great Salt Lake with rivers, snowfall and also rainfall, claimed Butler.

But neighborhood human activity plays a much bigger function in an excellent Salt Lake water loss. A 2016 white paper co-authored through Wayne Wurtsbaugh and also published by the Utah State University describes how water flowing right into the lake native rivers has actually been lessened by 39 percent in the last 150 years. Currently, about 40 percent that the river water is diverted and also used for farming, industry and other forms of human consumption. Follow to Wurtsbaugh, human water use has lowered the lake level 11 feet (3.3 meters) in the last 10 years.

Water ns affects the whole ecosystem of an excellent Salt Lake. It rises salinity, i m sorry could affect brine shrimp and birds. Migrating fowl have fewer areas to stay, together wetlands are desiccated. Butler provided the pelican population: “Pelicans swarm on Gunnison Island since it has actually no predators, but when the water levels space too low, predators have the right to walk the end to the island.”

Additionally, claimed Butler, water loss impacts the salt and brine shrimp harvest economy. The devices aren’t built for short water levels. Lower lake levels likewise increase wind-blown dust, do the lake less available via boat and could have unforeseen results on the Utah climate.

Humans also affect the lake through pollution. Great Salt Lake is unique amongst saline lakes in that it is alongside a significant metropolitan area, claimed Butler, and also the Salt Lake City area is meant to twin to 4 million people over the next 30 years. The proximity can cause problems, which are exacerbated by good Salt Lake’s lack of outlet. “Everything that happens in the watershed and airshed can be checked out in the lake,” claimed Butler. Rivers bring not only trash however toxins and other chemicals into great Salt Lake. Polluted air bring in additional toxins.

But toxin difficulties don’t just come from neighborhood sources. According to the university of Utah hereditary Learning science Center, great Salt Lake has actually the highest possible levels that mercury of everywhere in the joined States. Industry approximately the civilization emits mercury toxins, however they space benign in the atmosphere. Bacteria in good Salt Lake turn it into toxic mercury.

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Butler emphasized that the mercury exists primarily in a deep brine class (about 19 feet or 6 meter down), i m sorry the constant water and also brine does no penetrate. Therefore, that is for sure for humans to swim in good Salt Lake. Advisories have been authorize for people to stop eating typical goldeneye, cinnamon teal and northern shoveler duck caught around an excellent Salt Lake due to the fact that of your mercury levels.