The origin of the Great Salt Lake can be traced back to ancient Lake Bonneville which covered most of Western Utah and small parts of Idaho and Nevada during the Ice Age (between 23,000 and 12,000 years old). In the warmer, dry period after the ice age, Lake Bonneville receded and the Great Salt Lake is the remnant of that ancient lake.
The total amount of salt dissolved in the Great Salt Lake is about 4.5 to 4.9 billion tons. As the lake rises, its salinity drops because the same amount of salt is dissolved in more water. The lower the lake level, the saltier it becomes. In the past, the lake's salinity has ranged from a little less than 5 percent (which is just above sea water) to nearly 28 percent (beyond which water cannot hold more salt). As water flows over or moves beneath the Earth's surface, it dissolves minerals from the soils and rocks. The streams that originate in the Wasatch Range and other nearby mountains all flow into the Great Salt Lake, bringing in water with varying percentages of dissolved minerals. Since the lake has no outlet, all of these minerals remain in the lake.
The total amount of salt dissolved in the Great Salt Lake is about 4.5 to 4.9 billion tons. As the lake rises, its salinity drops because the same amount of salt is dissolved in more water. The lower the lake level, the saltier it becomes. In the past, the lake's salinity has ranged from a little less than 5 percent (which is just above sea water) to nearly 28 percent (beyond which water cannot hold more salt). As water flows over or moves beneath the Earth's surface, it dissolves minerals from the soils and rocks. The streams that originate in the Wasatch Range and other nearby mountains all flow into the Great Salt Lake, bringing in water with varying percentages of dissolved minerals. Since the lake has no outlet, all of these minerals remain in the lake.