Lake Tahoe is the largest alpine lake in North America, 22 miles long and 12 miles wide with 72 miles of shoreline. Two-thirds of the lake is in the state of California and one-third is in the state of Nevada. It is the third deepest lake in North America, and the tenth deepest in the world. Its greatest measured depth is 1,645 feet and averages 1,000 feet. In North America, Crater Lake in Oregon at 1,930 feet, and the Great Slave Lake in Canada at 2,101 feet are deeper. The water temperature at the surface varies from about 40° F in winter to 70° F in summer, and below 700 feet it is a constant 39° F. The lake is so clear because 40% of the precipitation falling into the Lake Tahoe basin lands directly on the lake. The remaining precipitation drains through the decomposed granite soils found in marshes and meadows, creating a good filtering system.
The images below are from May 2008.