Before the Great Salt Lake, there was Lake Bonneville. Lake Bonneville was a large lake covering about 20,000 square miles of western Utah and smaller portions of eastern Nevade and southern Idaho. It occupied the lowest, closed depression in the eastern Great Basin. Lake Bonneville was a large, ancient lake that existed from about 32 to 14 thousand years ago. It occupied the lowest, closed depression in the eastern Great Basin and at its largest extent covered about 20,000 square miles of western Utah and smaller portions of eastern Nevada and southern Idaho. At its largest, Lake Bonneville was about 325 miles long, 135 miles wide, and had a maximum depth of over 1,000 feet. Approximately16,800 years ago, the lake rose and caused a catastrophic flood. Researchers believe that the flood probably lasted less than a year. After the Lake Bonneville flood, the Great Basin gradually became warmer and drier. Therefore, Lake Bonneville began to shrink due of increased evaporation. What remained of Lake Bonneville is now the Great Salt Lake and it occupies the lowest depression in the Great Basin.
The first discovery of the Great Salt Lake was by the Spanish missionary explorers Dominguez and Escalante, who first learned of the Great Salt Lake from the Native Americans in 1776; however, they never actually saw it. The first white person known to have visited the lake was Jim Bridger in 1825. It is said that Etienne Provost may have beaten Jim Bridger, but there is no proof of this. The first scientific examination of the lake was in 1843 by John C. Fremont and Kit Carson. Kit Carson even carved a cross into a rock near the summit of Fremont Island, which is one of the islands located in the Great Salt Lake, which can still be seen today.
The Great Salt Lake averages approximately 75 miles long by 35 miles wide and 33 feet deep. However, its size and depth vary both seasonally and over long term. The amount to which it changes depends primarily on the balance of the amount of water that enters the lake and the amount of water that exits. On average, the lake level changes only about one to two feet annually. The lake rises to its highest level usually during May through July, after the melting of the mountain snowpack, and drops to its lowest level usually during October through November after the hot summer months. From 1847 to today, the level of the lake has varied over a range of 20 feet, reaching its ultimate low of 4,191.35 feet in 1963 and its high of 4,211.85 feet in 1986-1987. The average level of the lake is about 4,200 feet. Since the Great Salt Lake is a extremely shallow, small changes in the water level can greatly affect the shoreline.
The lake contains eleven islands. Seven of these islands are in the southern portion of the lake and four are in the northwestern portion. The large islands in the southern portion are named Antelope, Stansbury, Fremont, and Carrington. The smaller islands are named Badger, Hat (Bird), and Egg. The four small islands in the northwestern portion are Dolphin, Gunnison, Cub, and Strongs Knob. Antelope Island is 36 square miles and has been inhabited since pioneer times. There is a small ranch house owned by the Utah Division of Parks and Recreation that is said to be the state's oldest Anglo-built structure on its original foundation and the longest continually inhabited building in Utah and is opened during the summer for tours. Fremont Island was inhabited by a Salt Lake County probate judge, Judge Werner, and his family from 1884 to 1891. Both Gunnison and Carrington Islands were inhabited for short periods...