Today’s Great Salt Lake is a shallow, salty remnant of ancient Lake Bonneville that formed about 11,000 years ago. Three rivers flow into the lake – the Bear River, Weber River and Jordan River – but no water flows out of it, making it a “terminal” lake. Because it is shallow and salty, it loses about 2 million acre-feet of water through evaporation each year. Evaporation rates are highest during the hot summer months and lowest during the winter.

The Great Salt Lake supports a unique environment, ecology and economy. The lake reached new historic lows in 2021 and 2022, prompting action to protect it.

Great Salt Lake Shoreline historical fluctuation