The salt lake in Utah that is the largest in the Western Hemisphere and hosts millions of brine shrimp is the Great Salt Lake.
The lake is a remnant of prehistoric Lake Bonneville, which covered much of western Utah during the Ice Age. Because the Great Salt Lake has no outlet, water leaves mainly through evaporation, leaving dissolved minerals behind and making the lake much saltier than seawater.
That extreme salinity prevents most fish from surviving in the main basin, but brine shrimp, brine flies, algae, and microscopic organisms thrive there. Brine shrimp produce durable eggs called cysts, which are harvested commercially for fish, shrimp, and aquarium food. The lake also supports millions of migratory birds that feed on its invertebrates and use its surrounding wetlands.
A common mix-up is the Dead Sea, another famous hypersaline lake. The Dead Sea is saltier and lies in the Middle East, but it is not in the Western Hemisphere. The Great Salt Lake’s area and salinity fluctuate dramatically with drought, water diversions, and precipitation.