Facts About Lake Tahoe |
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The Lake Tahoe Basin was formed by geologic block (normal) faulting about 2 to 3 million years ago. A geologic block fault is a fracture in the Earth's crust causing blocks of land to move up or down. Uplifted blocks created the Carson Range on the east and the Sierra Nevada on the west. Down-dropped blocks created the Lake Tahoe Basin in between. Some of the highest peaks of the Lake Tahoe Basin that formed during this process were Freel Peak at 10,891 ft (3,320 m), Monument Peak at 10,067 ft (3,068 m) (the present Heavenly Valley Ski Area), Pyramid Peak at 9,983 ft (3,043 m) (in the Desolation Wilderness), and Mt. Tallac at 9,735 ft (2,967 m). Snow, rain, and streams filled the southern and lowest part of the basin, forming the ancestral Lake Tahoe. Modern Lake Tahoe was shaped and landscaped by the scouring glaciers during the Ice Age (the Great Ice Age began a million or more years ago). Many streams flow into Lake Tahoe, but the lake is drained only by the Truckee River, which flows northeast through Reno and into Pyramid Lake in Nevada. Lake Tahoe is the second deepest lake in the United States and
the tenth deepest in the world, with a maximum depth measured at 1,645
ft (501 m), average depth of 1,000 ft (305 m). Lake Tahoe is about 22 mi (35 km) long and l2 mi (19 km) wide and has 72 mi (116 km) of shoreline and a surface area of 191 mi2 (495 km2). The floor of the Lake Tahoe Basin is at an elevation of about 4,580 ft (1,396 m), which is lower than the surface of the Carson Valley to the east! With an average surface elevation of 6,225 ft (1,897 m) above sea level, Lake Tahoe is the highest lake of its size in the United States. The water temperature near the surface generally cools to 40 to 50oF (4.5 to 10oC) during February and March and warms to 65 to 70oF (18 to 21oC) during August and September. Below a depth of 600 to 700 ft (183 to 213 m), the water temperature remains a constant 39oF (4.0oC). Lake Tahoe has a water clarity of about 70 ft (21 m) deep. The clarity has reduced from greater than 100 ft (30.5m) since readings began in the late 1960's. The last published annual average Secchi depth reading was 67.7 ft (20.6m) in 2006 (page 10.2, UC Davis Tahoe Environmental Research Center publication "Tahoe: The State of the Lake Report 2007".) Information on this page was gathered from the |
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U.S. Department of the Interior
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