Mono Lake Mono Lake Tufa State Reserve A large, shallow saline soda lake in Mono County, next to the city of Lee Vining, California Mono Lake Tufa State Reserve This lake was formed at least 760,000 years ago as a terminal lake in an endorheic basin. This means minerals flowed in from underground rivers and then sprung up through the ground to create those amazing Tufas you see marking the shores.