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Home , Ancient lake, Antelope Island, Great Salt Lake, Gunnison Island, Salt lake, Willard Bay

Great , Introduction • When did the lake first appear? Great , the shrunken remnant of Although as early as 30,000 years ago there • Why is the north part of the lake purplish- prehistoric , has no outlet. Dis- were alternating periods of saline and pla- pink? solved accumulate in the lake by evapora- yas (salt flats) in the basin, is A railroad separates the lake into tion. south of the causeway has ranged believed to have first formed about 11,000 years a north and south part. Most freshwater enters from 6 percent to 27 percent over a period of 22 ago when the lake rose from a smaller saline the south part, and in the north part years (2 to 7 times saltier than the ocean). The body to about 4,250 to 4,275 feet at the Gilbert evaporates faster than it enters. The north part is high salinity supports a mineral industry that Level. At this time it was about three times as always much saltier than the south part. Several extracts about 2 million tons of salt from the large as present Great Salt Lake and was salty. species of purple salt-tolerant bacteria and an lake each year. The aquatic ecosystem consists The lake was less salty during the Stansbury alga with a red pigment live in the north part of more than 30 species of organisms. Harvest Level of Lake Bonneville. and cause the purplish-pink coloration, espe- of its best-known species, the shrimp, • Why is the lake salty? cially when the salinity is greater than about 25 annually supplies millions of pounds of food for percent. the aquaculture industry worldwide. The lake Because the lake does not have an outlet, is used extensively by millions of migratory water flows into the lake and then evaporates, • Are there any other large saline lakes? and nesting birds and is a place of solitude for leaving dissolved minerals behind as residue. Excluding in (3,100 people. All this occurs in On average, 2.9 million acre-feet of water square miles when flooded, but usually dry): a lake that is located at enters the lake each year from the Bear, Weber, and Jordan Rivers. The inflow carries about Water body Salinity Area the bottom of a 35,000- (parts per (square square-mile drainage 2.2 million tons of salt. About 4.3 billion tons thousand) miles) of salt are in the lake, and commercial removal basin that has a human Caspian (, ) 11 170,000 population of more than of the salt ranges from 1.6 to 2.5 million tons 1.5 million. annually. (Russia) 10 25,000 (Russia) 2.8 7,115 Frequently Asked Questions • What animals live in the lake? and Answers about Great Of the various animals, the most visible and Great Salt Lake (Utah) *140 1,700 famous is the (Artemia francis- (California) 44 380 Salt Lake cana). Two species of brine flies (genus Ephy- • How large is the lake? dra) also are very numerous but do not bite. (Israel) 220 390 At the average water-surface altitude of Numbers of these flies may reach 370 million * Measurement for Gilbert Bay, 1995. 4,200 feet, the lake is 75 miles long by 28 miles per mile of shoreline during summer. wide and covers about 1,700 square miles. At Two to five million shorebirds and hundreds this altitude, the maximum depth is about 33 of thousands of waterfowl use the lake season- feet. At its lowest altitude in 1963 (4,191 feet), ally. Wilson’s Phalarope and Eared Grebes often it was less than one-half the size it reached at its are present in summer. historic high peak during 1986–87 (4,211 feet). • How did brine shrimp get into the lake and • How was the lake formed? when did they first appear? The lake is a remnant of Lake Bonneville, a The shrimp likely arrived as cysts (eggs) on large -age lake that covered about the feet of migratory birds. Brine shrimp cysts 20,000 square miles (slightly smaller than West and fecal pellets in a deep sediment core have Virginia at 24,000 square miles) and was a been dated to be 15,000 years old. maximum of 325 miles long by 135 miles wide, with a maximum depth of 1,000 feet. Lake • How do brine shrimp live in the extremely Bonneville existed from about 30,000 years ago salty (hypersaline) environment of the lake? to 16,000 years ago. Four ancient shorelines The body cuticle prevents water loss and salt of Lake Bonneville are visible on the Wasatch entry. The shrimp drink large amounts of salt Mountains to the east. water and the gut takes up the water (and some salt). The branchia, or gills, then excrete the salt Adult actual size back into the water. Brine shrimp (Artemia franciscana) adults and cysts. Altitude Lake-level Years (feet) name before present • Have there ever been marine organisms or fish in the lake? History 4,500 Stansbury 23,000–20,000 Thirty thousand years ago, during the last ice In 1899, the U.S. Fisheries Service consid- 5,090 Bonneville 16,000–14,500 age, Lake Bonneville expanded from a small ered implanting oysters into the mouths of the saline lake to a freshwater lake that covered 4,740 Provo 14,500–13,500 larger rivers that enter the lake but decided that about 20,000 square miles and was about 1,000 oysters could not be raised commercially. 4,250 Gilbert 11,000–10,000 feet deep. About 16,000 years ago, the lake In 1986, killifish entered from Timpie (Curry and others, 1984) cut a massive outlet at its northern end and Springs on the south end when the lake was at a discharged a flood that reached the . salinity of about 5.5 percent. A dry period nearly eliminated any remnant of the lake about 500 years later, but increasing

Water-Resources Investigations Report 1999–4189 April 2007 precipitation raised the water surface to about cies has been estimated at 32. These organisms 50 feet above the present lake level, creating interact to form a complex and highly produc- Great Salt Lake. tive ecosystem. (25 species reported The Dominguez and Escalante expedition in 1979) provide the base for the food chain reached Utah Valley, 50 miles south of Great through photosynthesis. They serve as food for Salt Lake, in 1776. The indigenous Timpan- brine shrimp and brine flies, which in turn are gotzis Indians told them of a very salty lake consumed by birds or by the shrimp harvested in the valley to the north. The explorers were for the aquaculture industry. Bacteria, proto- anxious to return to Monterey and did not zoa, and brine flies recycle the organic material investigate this saline lake. In 1824, the French to release nutrients and keep energy flowing trapper Etienne Provost may have been among through the system. the first of the European trappers to see the Brine Shrimp lake, but other European trappers and explor- The invertebrate community ers also vie for the honors: , Peter of Great Salt Lake undergoes Skene Ogden, and John H. Weber. An early large annual variations in timing scout and explorer, John C. Fremont, is cred- and abundance of life stages ited with making the first scientific measure- and is dominated by brine shrimp, Artemia ment of lake altitude in 1843 (4,200 feet). franciscana. The variations are partly the result The Stansbury expedition entered Salt Lake of changes in salinity, water temperature, Valley to make maps and describe the area in nutrients, and algal populations. The young 1849 under the direction of the U.S. Govern- artemia, called nauplii, typically appear ment. The expedition succeeded in mapping from over-wintering eggs (hard-walled cysts the entire shoreline of the lake by 1850. All of causeway viewed from containing an embryo in dormancy) from late the larger in the lake except Fremont Lakeside, Utah. Gunnison Bay on left, Gilbert Bay on right, January 1998. February to early March when water tempera- were named for members of this explo- tures are between 32 and 41 degrees Fahr- ration party: (Howard Stans- ity of 25 percent or higher; water south of the enheit. Their appearance follows the winter bury), Carrington Island (), causeway (Gilbert Bay) has varied from about 6 bloom of that provides food for (J.W. Gunnison). to 27 percent salinity. The Bear, Weber, 30 Clarence King, a geologist with the U.S. and Jordan Rivers contribute about 27 Government survey of the Fortieth Parallel, 66 percent of the annual inflow of 2.9 million acre-feet (one acre-foot equals 24 Gunnison Bay surveyed the lake from 1869 to 1870. Addi- at Saline gage tional geologic and geographic surveys in the 325,851 gallons, or the amount of water 21 (north part) vicinity of Great Salt Lake were completed in that it would take to cover one acre to a 18 the next few years by F.V. Hayden, George M. depth of one foot) to the lake, precipita- 15 Measurements tion into the lake contributes about 31 made in non- Wheeler, and Grove C. Gilbert as part of the 12 consecutive great exploration of the percent, and ground-water inflow about years 9 West done by the U.S. 3 percent. Gilbert Bay at SALINITY, IN PERCENT SALINITY, 6 Railroad Boat Harbor gage Army Corps of Topo- Water-budget studies done by the causeway (south part) graphical Engineers U.S. Geological Survey indicate that 3 constructed and the U.S. Depart- rivers contribute about 82 percent of 0 ment of the Interior. 1999 1998 1850 1889 1895 1903 1958 1963 1969 1972 1975 1981 1984 1990 1993 1996 the annual dissolved-solids load of 2.1 1877 1913 1966 1978 1987 million tons and springs contribute 18 Average annual salinity of Great Salt Lake. Hydrology and Salinity percent. Water can leave the lake only Great Salt Lake is divided by a rock-fill rail- by evaporation, which amounts to about the developing nauplii by about 1 month. Peak road causeway constructed in 1959 to replace 2.9 million acre-feet annually. The lake is saline numbers of nauplii typically occur between the wooden trestle built in 1903. During the because evaporation concentrates the dissolved mid-April and mid-May. The first generation high water years of 1983–87, additional fill salts in the remaining water. About 4.5 billion of adults produced by the nauplii reproduces was added to raise the structure and a 300-foot tons of salt are in the lake, and commercial sexually and, if food availability and environ- breach was added. Most of the surface inflow removal of salt equals about 2.3 million tons mental conditions are suitable, will produce from the Bear, Weber, and Jordan Rivers enters annually. Sodium (table salt) is the the second generation ovoviviparously (by live the lake south of the causeway, and only a most common salt, although small amounts birth). If conditions are less favorable, ovipa- small amount of water flows north through of other salts and elements also are present, rous reproduction produces cysts. Two or three openings in the causeway. Water north of the including , , sulfate, and generations of artemia are produced each year. causeway (Gunnison Bay) often has a salin- carbonate. The artemia graze the phytoplankton to near Five commercial enterprises extract salt extinction by May. The lack of food causes Commercial Surface-dwelling Birds Adult Birds adult females to begin oviparous cyst produc- harvest insects brine flies and other minerals from the lake. Most use tion. The maximum number of adults occurs (Trichocorixa large solar evaporation ponds located near verticalis) about mid-May and then gradually declines Sunlight Stansbury Island and Bear River Bay to Brine flies until December, when water temperatures drop (Ephydra Larvae) retrieve the salts. Brine shrimp below about 37 degrees Fahrenheit and the ? (Artemia franciscana) Bottom-dwelling Life in Great Salt Lake adults die. cyanobacteria Fecal (Coccochloris Hypersaline lakes typically support fewer Brine shrimp from Great Salt Lake have pellets elebans, Oscillatoria sp.) Phytoplankton species of aquatic organisms than freshwater been commercially harvested as adults since Shrimp (Dunaliella viridis lakes because only a few specialized species 1950 and as cysts since 1952. The annual cysts Pennate and Centric diatoms) can withstand the stress of . The harvest is regulated by the Utah Division of total number of species in Great Salt Lake Resources and begins October 1. The depends on the salinity and is not accurately harvest lasts about 1 to 4 months, depending Nutrients known because microscopic species have not on the number of cysts available. The cysts are Decomposition and from the nutrient release watershed been well studied. When the salinity is high marketed worldwide and used extensively in (bacterial) (28 percent in Gunnison Bay), there may be aquaculture as a food source for larval stages Generalized ecosystem structure and energy flow as few as six species. At lower (6 to of giant prawns and fish. Reported cyst harvest within Gilbert Bay of Great Salt Lake. 9 percent in Gilbert Bay), the number of spe- from 1964 to 1978 ranged from 83 tons in 113°00' 112°00'

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Base from U.S. Geological Survey digital data, 1:100,000, 1978, 1979, 1980, 1984 0 10 20 MILES Universal Transverse Mercator projection, zone 12 EXPLANATION 0 10 20 KILOMETERS Great Salt Lake, altitude 4,200 feet USGS has measured lake altitude at or near Boat Harbor gage since 1875, and at Saline gage since 1966. Intermittent water body Great Salt Lake historic maximum altitude 4,211.60 feet, June 3, 1986, and April 1 and 15, 1987 Utah State Park or National Monument Great Salt Lake historic minimum altitude 4,191.35 feet, October 15 and November 1, 1963 Waterfowl Management Area (WMA) or other wildlife reserve ing the world’s largest recorded single Additional References colony. About 150,000 breeding adults have been counted in recent years. The Arnow, Ted, and Stephens, Doyle, 1990, Hydro- colony on logic characteristics of the Great Salt Lake, Gunnison Island ranks among the three Utah: 1847–1986: U.S. Geological Survey largest colonies in North America. Water-Supply Paper 2332, 32 p. The lake and its marshes provide a resting and staging area for the birds as Curry, D.R., Atwood, G., and Mabey, D.R. well as an abundance of brine shrimp 1984. Major levels of Great Salt Lake and and brine flies that serve as food. Lake Bonneville: Map 73, Utah Geological Important wetlands include Bear River and Mineral Survey. Migratory Bird Refuge operated by the U.S. Fish and Wildlife Service; Gwynn, J.W., ed., 1980, Great Salt Lake, A Locomotive Springs, Salt Creek, Public scientific, historical, and economic overview: Shooting Grounds, Harold Crane, Wil- Utah Geological and Mineral Survey Bulletin Commercial shrimp-harvesting craft with isolation boom lard Bay Upland Game, Ogden Bay, suspended by orange floats. 116, 400 p. Howard Slough, Farmington Bay, and 1966 to 265 pounds in 1968 to about 7,400 tons Timpie Springs Waterfowl Manage- Morgan, D.L., 1947, The Great Salt Lake: Salt ment Areas operated by the Utah Division of during 1995–96. (Reported amounts include Lake City, Press, 432 p. Wildlife Resources; Layton Wetlands Preserve total unprocessed biomass of which about managed by the Nature Conservancy; Gill- half is cysts.) Historically, salinity of the lake Stephens, D.W., 1998, Salinity-induced changes mor Bird Sanctuary managed by the Audubon has been the major factor associated with the in the aquatic ecosystem of Great Salt Lake, Society; and the Inland Sea Shorebird Reserve abundance and distribution of artemia and the Utah: 1–7, in J. Pitman and A. Carroll, eds., managed by Kennecott Utah Copper. Most of success of the cyst harvest. When salinity of Modern and Ancient Lake Systems, Utah these areas are accessible seasonally for bird Gilbert Bay varied from 6 to 10 percent from Geological Survey Guidebook 26. watching and some for duck . 1982 to 1989, cyst production was poor and most harvesters moved to Gunnison Bay, the Recreation north part of the lake, where the salinity was Motor boating is not popular on the lake 15 to 17 percent. Since about 1990, reproduc- because of corrosion problems; however, two ing populations of artemia have been limited marinas provide facilities for sailing: Great — By Doyle W. Stephens and Joe Gardner to Gilbert Bay, although during the 1998–99 Salt Lake Marina on the south end of the lake season limited harvest efforts resumed in Gun- and State Park on Antelope nison Bay. Island. The more popular of the marinas and Contact Information: Brine Flies headquarters for the Great Salt Lake Yacht Club Antelope Island State Park 801-721-9569 is located at the south end of the lake where Entrance station 801-773-2941 Two species of brine launching is free but facilities are limited to a Bear River Migratory Bird Refuge 435-723-5887 flies (or ephydra) live in the lake. Adult flies boat ramp, picnic area, and restrooms. Fresh- congregate along the shoreline for breeding and Friends of Great Salt Lake 801-583-5593 water boating is available at Willard Reservoir, Website www.fogsl.org occasionally reach densities of 370 million per east of Bear River Bay, and camping facili- mile of beach. Although they do not bite, they ties are available at Willard Bay State Park. A Great Salt Lake Marina, near Saltair 801-250-1898 often land on people and may be annoying. commercial business operates daily boat trips Golden Spike National Historic Site 435-471-2209 The larval form of the brine fly (shown above on the lake from Great Salt Lake Marina in the Great Salt Lake Yacht Club www.gslyc.org at twice lifesize) feeds on detritus and benthic summer. A per-vehicle fee for use of the Davis Inland Sea Shorebird Reserve Website algae and plays an important role in recycling County Causeway and Antelope Island State www.kennecott.com/SD_env_wetlands.html nutrients within the lake. Park provides access to a boat ramp, restrooms, The Nature Conservancy of Utah Migratory Birds showers, picnic areas, camping areas (by reser- Layton Wetlands Preserve 801-531-0999 vation only), an excellent visitor center, miles Website www.nature.org/utah/ Great Salt Lake sup- of horse and bike trails, a resident bison herd, Salt Island Adventures (boat cruises) 801-252-9336 ports from 2 to 5 million and a café. shorebirds, as many Utah Division of Wildlife Resources 801-538-4700 Website wildlife.utah.gov/index.php as 1.7 million Eared Golden Spike National Historic Site marks Grebes, and hundreds of the spot where the last spike in the transcon- Willard Bay State Park 435-734-9494 thousands of waterfowl tinental railroad was driven on May 10, 1869. during and fall migration. Because of Facilities include a visitor center, historic loco- This information is provided by the U.S. its importance to migratory birds, the lake was motives, and interpretive presentations. Geological Survey, which has been researching designated a part of the Western Hemisphere Antelope Island, with an area of about Great Salt Lake since the G.C. Gilbert explora- Shorebird Reserve Network in 1992. The lake 28,000 acres, is the largest of the islands in tion of the 1870s. For additional information is a major staging area for some shorebirds, Great Salt Lake and is publicly owned and about Great Salt Lake see our web site at: such as the Wilson’s Phalarope. In July 1986, accessible by vehicle. Carrington and Fremont http://ut.water.usgs.gov/ 387,000 Wilson’s Phalarope were estimated in a Islands, although relatively large, are accessible 1-day aerial survey, and 600,000 were estimated only by boat and are privately owned. Gunnison on a single day in July 1991. Studies indicate and Hat Islands are protected as bird rookeries Information on technical reports and hydro- that at least 5,000 to 10,000 Snowy Plovers nest and have no public access. Stansbury Island is logic data of Great Salt Lake can be obtained on the alkaline flats surrounding the lake. The accessible by vehicle but is mostly privately from: current estimate for breeding American Avocets owned. is 40,000 and for Black-necked Stilts 30,000. U.S. Geological Survey Hundreds of thousands of Eared Grebes stage Bird watching is seasonally popular at most 2329 Orton Circle of the wetlands along the east shore. There is no on the lake, fattening on the abundant brine , Utah 84119-2047 shrimp. One of the world’s largest populations charge for access to State Waterfowl Manage- ment Areas. Duck and goose hunting is allowed of White-faced Ibis nests in the marshes along Phone (801) 908-5000 the east side of the lake. The lake hosts the larg- (with purchased permits) in the fall at all of the est number of breeding California Gulls, includ- State Waterfowl Management Areas.