Lake Bonneville was a lake that existed between 30,000 and 13,000 years ago. At its largest, the lake stretched for nearly 20,000 square miles, covering parts of western Utah and eastern parts of Idaho and Nevada. The lake filled up a depression that was located in the Great Basin.
Lake Bonneville had a depth of over 1,000 feet and was approximately 325 miles long by 135 miles wide. During the Ice Age, the fresh water lake was fed by rain, streams, glacier meltwater and rivers.
About 16,000 years ago, the climate became warmer and dryer, and the lake levels began decreasing. Within 2,000 years, the lake decreased to about the size of the Great Salt Lake.
Only a few remnants remain of this great lake, including Salt Lake.
Historical Marker Inscription
20,000 years ago, this land was under water. Not far to the north, you can see the old shore of Lake Bonneville.
Formed in a basin from which no river reached the ocean, this became the largest lake in North America. Finally the lake rose high enough to overflow into the Snake River. Then after the climate got drier, and the great basin of Utah and Nevada became mostly a desert, the lake receded. Salt Lake and two other remnants are all that are left of this old 20,000 square mile lake.
Text prepared by The Idaho Historical Society
Marker Made & Installed by Idaho Transportation Department
Location
42° 4’ 22.820” N, 112° 54’ 18.792” W
Malta, ID 83342, United States
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