The lakebed is a remnant of prehistoric Lake Lahontan that covered much of northwestern Nevada during the ice age. Although the ancient history of Walker Lake has been extensively studied by researchers seeking to establish a climatic timeline for the region as part of the Yucca Mountain Nuclear Waste Repository study, this research has raised many puzzling questions. Unlike Pyramid Lake, the lake itself has dried up several times since the end of the Pleistocene, probably due to natural diversions of the Walker River into the Carson Sink approximately 2,100 years ago. Also, this research found no evidence that the Walker Lake basin contained water during the Lake Lahontan highstand, although based on the surface elevation of the highstand evidenced elsewhere in the region it must have.