Great Salt Lake FAQJune 2013Natural History Museum of Utah What is the origin of the Great Salt Lake?o After the Lake Bonneville flood, the Great Basin gradually became warmer and drier.Lake Bonneville began to shrink due to increased evaporation. Today's Great Salt Lake isa large remnant of Lake Bonneville, and occupies the lowest depression in the GreatBasin. Who discovered Great Salt Lake?o The Spanish missionary explorers Dominguez and Escalante learned of Great Salt Lakefrom the Native Americans in 1776, but they never actually saw it. The first whiteperson known to have visited the lake was Jim Bridger in 1825. Other fur trappers, suchas Etienne Provost, may have beaten Bridger to its shores, but there is no proof of this.The first scientific examination of the lake was undertaken in 1843 by John C. Fremont;this expedition included the legendary Kit Carson. A cross, carved into a rock near thesummit of Fremont Island, reportedly by Carson, can still be seen today. Why is the Great Salt Lake salty?o Much of the salt now contained in the Great Salt Lake was originally in the water of LakeBonneville. Even though Lake Bonneville was fairly fresh, it contained salt thatconcentrated as its water evaporated. A small amount of dissolved salts, leached fromthe soil and rocks, is deposited in Great Salt Lake every year by rivers that flow into thelake. About two million tons of dissolved salts enter the lake each year by this means. Where does the Great Salt Lake get its water, and where does the water go?o Great Salt Lake receives water from four main rivers and numerous small streams (66percent), direct precipitation into the lake (31 percent), and from ground water (3percent). The total average annual inflow to the lake is about 2.9 million acre feet ofwater.o The Great Salt Lake is a terminal lake because it has no surface outlet (rivers flowingfrom it). Water is lost from the lake mostly through evaporation. Evaporation rates arehighest during the hot summer months and lowest during the winter. An average ofabout 2.9 million acre feet of water evaporates from the lake annually. How big and how deep is the lake, and why does it change in size?o Great Salt Lake averages approximately 75 miles long by 35 miles wide at a surfaceelevation of about 4,200 feet. At this elevation, the lake covers an area of 1,034,000acres, and has a maximum depth of about 33 feet.o It is reported to be the 33rd largest lake in the world and the largest fresh or saltwaterlake in the United States after the Great Lakes. Its size and depth, however, vary both

Great Salt Lake FAQJune 2013Natural History Museum of Utahoooseasonally and over the long term. The magnitude of these changes depends on thebalance between the total amount of water that enters the lake and that which leaves.On average, the lake level fluctuates one to two feet annually, rising to its highest levelduring May through July (following the melting of the mountain snowpack) anddropping to its lowest point during October through November (after the hot summermonths).In historical time (1847 to present), fluctuations of the lake level have varied over arange of 20 feet from a low of 4,191.35 feet in 1963 to a high of 4,211.85 feet in 19861987. The historical average elevation of the lake is about 4,200 feet.Because of the very shallow nature of the lake, even modest changes in its elevationresult in relatively large changes in the lake's area and volume. The accompanying mapshows the high, average, and low elevations of the lake and pertinent information foreach of these elevations. How many islands are in the Great Salt Lake, where are they, and are they inhabited?o The lake contains 11 recognized islands, although this number varies depending on thelevel of the lake. Seven islands are in the southern portion of the lake and four in thenorthwestern portion.o The large islands in the southern portion are named Antelope, Stansbury, Fremont, andCarrington. The smaller islands are named Badger, Hat (Bird), and Egg. The four smallislands in the northwestern portion are Dolphin, Gunnison, Cub, and Strongs Knob.o Antelope Island has been inhabited since pioneer times. A ranch house on AntelopeIsland is said to be the state's oldest Anglo-built structure on its original foundation andthe longest continually inhabited building in Utah. Presently, the Utah Division of Parksand Recreation retains ownership of the ranch house which is open periodically duringthe summer for tours.o Fremont Island has also been inhabited, most notably by Judge Wenner, a probate judgefor Salt Lake County, and his family, from 1884 to 1891.o Both Gunnison and Carrington Islands were unsuccessfully homesteaded for shortperiods of time.o Antelope Island has been owned by the State of Utah since 1980. It is home to a largeherd of buffalo which is managed by the Utah Division of Parks and Recreation.Antelope, deer, and many other animals also live on the island.o The northern 2,000 acres of the 23,175-acre island are designated as Antelope IslandState Park. The Antelope Island/Syracuse causeway is the only public-access roadconnecting the island to the mainland. When and why was a railroad built across the Great Salt Lake?

Great Salt Lake FAQJune 2013Natural History Museum of Utahoooooo Great Salt Lake is divided into two parts by the Southern Pacific Transportation Co.(SPTC) causeway. That part north of the causeway and west of Promontory Mountains iscalled the north arm, and that to the south of the causeway is called the south arm.Bear River Bay, although north of the railroad, is considered part of the south arm of thelake. The south arm and Bear River Bay are connected by an opening in the railroadcauseway about four miles east of Promontory Point.In about 1903, the railroad was constructed across the lake as a wooden-trestlestructure. The open structure of the trestle allowed for the mixing of water between thenorth and south arms of the lake. It was built to lessen the distance, degrees ofcurvature, and time required for trains to travel the previous route around the northend of the lake.By the early 1950s, maintenance costs had become high, and the structure had becomeunstable under normal operating speeds. Construction of a stable, permanent structureacross the lake was needed.By 1953, the SPTC had decided to replace the wooden trestle with a rock-fill causewayto be built parallel to, and about 1,500 feet to the north of, the old trestle. The structurewas completed in 1959 at a cost of roughly 50 million (in 1960 dollars).In 1993, the Trestlewood Division of Cannon Structures, Inc. began to dismantle andsalvage the timbers and planking of the old wooden trestle. Salvage operations are stillactive as of 1995.How has the railroad causeway affected the Great Salt Lake?o The rock-fill causeway has had two major effects on the Great Salt Lake, both related torestricted circulation of water between the north and south arms: (1) the south arm hasmaintained a higher water level than the north, and (2), the north arm has becomesaltier than the south.o The rock-fill causeway has had two major effects on the Great Salt Lake, both related torestricted circulation of water between the north and south arms: (1) the south arm hasmaintained a higher water level than the north, and (2), the north arm has becomesaltier than the south.o The level of the south arm is higher than the north arm because river water enters thesouth arm at a faster rate than lake water can move northward through the causewayand its openings.o Since the construction of the solid-fill causeway, the salt content (salinity) of the northarm has become greater than the south arm. This is due to the following: (1) the southarm receives nearly all of the freshwater tributary inflow to the lake, and (2) the northarm is fed mainly by south arm salty water seeping through the causeway and flowingthrough the culverts and the breach opening.

Great Salt Lake FAQJune 2013Natural History Museum of UtahoCurrently, the north arm of the lake is near its salt-saturation point (24-26 percent) andis about twice as salty as the south arm (12-14 percent). What was done about the flooding that occurred around Great Salt Lake during the 1980s?o In 1983, the level of Great Salt Lake began to rise, due to above-average annualprecipitation. By 1986, the lake rose nearly 12 feet to reach its historic high of 4,211.85feet. The high lake level caused serious flooding which resulted in millions of dollars inproperty damage, especially around the south arm of the lake.o Flooding disrupted major highway and railroad traffic; inundated mineral-industry solarponds, roads, beaches, farms, boating facilities and state/federal waterfowlmanagement areas; and threatened water-treatment plants.o In 1984, after studying numerous flood-control alternatives, the State of Utahimplemented its first flood-control project by breaching the SPTC causeway. The breachconsisted of a 300-foot-long bridge-covered opening in the causeway near Lakeside,which allowed the rapid flow of south-arm water into the north arm.o Prior to the breach, the elevation of the south arm was over 3.5 feet higher than thenorth arm. Completed at a cost of about 3.5 million dollars, the project lowered thesouth arm of the lake by nearly one foot and raised the north arm by about 1.5 feet,within about two months.o The lake continued to rise after the causeway breach was completed, forcing the Stateto implement its second flood-control alternative, pumping water from the lake into theWest Desert.o Three large pumps installed on the western shore of the lake pumped water via a 4.1mile-long canal to the West Pond. The pumping project filled the 320,000-acre WestPond with over 800,000 acre-feet of water and greatly increased the net evaporationfrom the lake. The West Desert Pumping Project was completed at a cost of more than 60 million.o For more than two years, starting in 1987, water was pumped from the north arm of thelake into the West Pond evaporation area in the west desert. During the 26-month lifeof the project, more than 2.7 million acre-feet of water were pumped, which containedabout 695 million tons of salt.o The pumps are currently not in use but are maintained in ready condition should thelake rise again. How much salt is in Great Salt Lake, and why does the salinity vary?o The total amount of salt dissolved in Great Salt Lake is about 4.5 to 4.9 billion tons. Asthe lake rises, its salinity drops because the same amount of salt is dissolved in morewater. The lower the lake level, the saltier the lake becomes. In historical time, the

Great Salt Lake FAQJune 2013Natural History Museum of Utahlake's salinity has ranged from a little less than 5 percent, (just above that of sea water),to nearly 27 percent (beyond which water cannot hold more salt). Can I float in Great Salt Lake?o You can easily float in Great Salt Lake if the water is salty enough. At the lake's averageelevation of 4,200 feet, the south arm of the lake contains about 13 percent salt, whichmakes it salty enough for most people to float with little effort. When the lake is higherthan 4,200 feet, it is less salty and therefore less buoyant. Swimmers float easily in thenorth arm because it is twice as salty as the south arm. What is the chemical composition of Great Salt Lake?o The chemical composition of Great Salt Lake is similar to that of typical ocean water.Sodium and chloride are the major ions in the water, followed by sulfate, magnesium,calcium, and potassium. For comparison, the table below shows the concentration ofthe six major ions in water of Great Salt Lake, a typical ocean, and the Dead Sea.Chemical compositions (dry weight percents)of Great Salt Lake, typical ocean, and the Dead Sea deSulfateGreat Salt Lake32. (typical) Sea12.32.312.85.367.20.1 What activates/industries exist in and near Great Salt Lake?o The Great Salt Lake and its environs have been used by swimmers, boaters, bikers,hikers, and hunters for recreational purposes from the mid-1800s to the present.o Long-term water-level fluctuations, both high and low, have adversely affected lakerecreation over the years, however. Nearly a dozen resorts have either been flooded orleft high and dry.o The most famous resort, Saltair, was built in 1893 and destroyed by fire in 1971. Thelake and its three state parks, Great Salt Lake Saltair Beach, Antelope Island, and WillardBay, attracted over a million tourists in 1994.o The extraction of common salt from the lake started in the mid-1800s and continues tobe an important part of the State's economy. Other products, including magnesiummetal, chlorine gas, sodium and potassium sulfate, and magnesium chloride, have beenextracted since the early 1960s.o Oil occurs in natural seeps on the north shore of the lake, and drilling in the late 1970sdisclosed additional oil beneath the bed of the lake.

Great Salt Lake FAQJune 2013Natural History Museum of UtahooThe brine-shrimp industry harvests brine-shrimp eggs, for use as fish food, and exportsthem worldwide.Eight state waterfowl management areas and one federal migratory bird refuge dot thesouthern, northern, and eastern shores of the lake. Established during the early 1900s,these areas serve as important resting, feeding, and nesting areas for millions of ducks,geese, grebes, shorebirds, and other water-dependent birds. Visitors are alwayswelcome, and hunting is generally allowed during the regular waterfowl hunting season. What minerals are produced from Great Salt Lake? How and by who are they recovered?o In 1995, five mineral-extraction companies operated near the lake. These companiesused solar evaporation to concentrate the lake waters to produce either salts or highlyconcentrated brine (water with high salt content) products. These companies paid aroyalty to the State of Utah (owner of the lake), on the salts and other materialsproduced and sold.o Sodium chloride (common salt) is produced by: (1) evaporating the water in shallowponds that cover many thousands of acres, (2) precipitating the salt, and (3) harvestingit from the bottom of the ponds. The collected salt is rinsed, washed, dried, andscreened to produce different product sizes and grades.o Food-grade, or table salt is not produced from the lake, because its purity cannot beguaranteed without additional, costly processing. The table salt used in Utah comesfrom salt-processing facilities in New York, Ohio, Kansas, Louisiana, Texas, or California. What lives in and around Great Salt Lake?o The tiny brine shrimp (Artemia salina) is one of the few animals that live within GreatSalt Lake. The brine-shrimp population plays an important part in the lake's ecosystem,especially in keeping the lake waters clean through algae consumption. They are also amajor food source for millions of migrating birds.o Other forms of life associated with the lake include brine flies, algae, and bacteria. Brineflies congregate by the millions along the lake's beaches, where they feed on bacteriaand algae that grow on rocks or wood. The wind commonly blows the remains of deadbrine flies into long, black, odoriferous windrows or piles along the beaches. Numerousspecies of algae and bacteria, which cause the varied colors of the lake waters, providefood for the brine shrimp.o Ducks, geese, gulls, pelicans, and hundreds of other types of birds live in the marshesand wetlands surrounding the lake. Great Salt Lake is an important part of the Pacificand Central Flyways for migratory waterfowl and part of the Northern HemisphericShorebird Reserve Network.

Great Salt Lake FAQJune 2013Natural History Museum of UtahoThe shores and nearby wetlands of the lake are also home to a variety of reptiles andmammals. Eight amphibian, two turtle, nine lizard, and eight snake species, as well astotal of 64 species or subspecies of mammals have been identified in the Great Salt Lakearea. How does the lake affect the weather?o Due to its large size, Great Salt Lake has a significant effect on the weather of nearbycities. During the winter, the lake is warmer than the air above it. This increases themoisture content of the air, creates thermal instability, and causes natural seeding ofsalt crystals. These factors are believed to cause the fall and winter "lake effect," inwhich areas adjacent to and usually downwind from the lake receive greater snowfallthan those more distant. What makes the lake stink?o The unpleasant odor (resembling rotten eggs) that comes from the lake is a commoncomplaint from those who live near the lake. The odor results from the decay of plantand animal remains in the shallow waters around its shores, especially in FarmingtonBay. This odor is especially noticeable when northwest winds blow across the lake, stirup the shallow waters, and carry the odor landward to populated regions. Is the Great Salt Lake polluted?o The quantities of harmful contaminants in the lake, such as industrial organic wastes,copper, arsenic, mercury, cadmium, and lead are very low. This is contrary to what onemight expect since rivers, waste-water treatment plants, and industrial facilitiesdischarge into the lake.o The lake ecosystem appears to cleanse itself of certain types of contaminants throughchemical and biological processes. More study is needed to understand these cleansingprocesses, however. Where are the Bonneville Salt Flats and how did they form?o The Bonneville Salt Flats are located west of Great Salt Lake near the town of Wendoveron the Utah-Nevada border, about 115 miles west of Salt Lake City. The flats are abroad, salt-covered lake bed, and one of the flattest areas on earth. They were formedduring the final evaporative stages of Lake Bonneville. What is the tall smoke stack at the south end of the Great Salt Lake?o The 1,200-foot-tall smoke stack at the southern end of the lake is part of the KennecottCopper Company's copper ore-smelting operation. Ore for this smelter comes from the

Great Salt Lake FAQJune 2013Natural History Museum of UtahBingham Canyon copper mine, which is the largest open-pit excavation on earth. TheBingham Canyon mine, started in 1906, is located approximately 15 miles to the southof the lake on the eastern side of the Oquirrh Mountains. What are the round, white sand grains that make up the beaches?o The round, brown-to-white grains that make up many of the beaches around the lakeare called oolites. Oolites are small spherical to elongated grains composed ofconcentric layers of calcium carbonate built up around a central core, much like a pearl.The core material is usually a small mineral grain, or a brine shrimp fecal pellet.o Some of the most beautiful beaches around the lake are composed of oolitic sand. Do fish live in the Great Salt Lake?o Yes, but the fish only live near stream inlets where the salinity is low enough for them tosurvive. Outside of the inlets, fish do not and cannot survive What are the most common birds seen on the Great Salt Lake?o Wilson's phalaropeo Red-Necked Phalaropeo American Avoceto Black-Necked Atilto Marbled Godwito Snowy Plovero Western Sandpipero Long-billed Dowitchero Tundra Swano American White Pelicano White-Faced Ibiso California Gullo Eared Grebeo Peregrine Falcono Bald Eagleo Plus large populations of various ducks and geese Over 7.5 million birds of 257 species visit the Great Salt Lake every year Over 2.5 million eared grebes, at times over half the North American population Up to 20,000 breeding adult pelicans on Gunnison Island About 500,000 phalaropes, largest staging concentration in the world,representing 1/3 of world population

Great Salt Lake FAQJune 2013Natural History Museum of Utah What is the foam that forms on the Great Salt Lake?o Deep piles of white, pillowed foam are a common sight along the shores of Great SaltLake, especially during and after windstorms that cause waves to crash against itsshores. The question is often asked, “What causes the foam, and does this mean thatthe lake is polluted?” The bubbles are formed as the lake moves, but the bubbles in other lakes pop asthey reach the surface. On the Great Salt Lake, the bubbles don’t pop due to thepresence of Surfactants, similar to what you would find in soap. The surfactantsare not pollution; rather they are excrement of phytoplankton in the lake.

the soil and rocks, is deposited in Great Salt Lake every year by rivers that flow into the lake. About two million tons of dissolved salts enter the lake each year by this means. Where does the Great Salt Lake get its water, and where does the water go? o Great Salt Lake receives water from four main rivers and numerous small streams (66