Mono Lake - the lake is rising, expected to reach its 1941 level around 2015 to 2022- The reserve was established to preserve the spectacular "tufa towers," calcium-carbonate spires and knobs formed by interaction of freshwater springs and alkaline lake water. Mono Lake is a majestic body of water covering about 65 square miles. It is an ancient lake, over 1 million years old -- one of the oldest lakes in North America. It has no outlet. Throughout its long existence, salts and minerals have washed into the lake from Eastern Sierra streams. Freshwater evaporating from the lake each year has left the salts and minerals behind so that the lake is now about 2 1/2 times as salty and 80 times as alkaline as the ocean.