FACT & FICTION

Visitors to Tahoe will hear much in the way of interesting statistics and information about the lake while here, some true and some just popular misconceptions. On this page we try to set the record straight.

Lake Tahoe is approximately 22 miles at its longest point and 12 miles at its widest. It has 72 miles of shoreline and approximately two-thirds of its 191 square mile surface area is in California, one-third in Nevada.

The bottom of Lake Tahoe has never been found.

On July 4, 1875, two men actually discovered the deepest point in the lake to be 1645 feet by lowering a leaded champagne bottle on fishing line from the side of their boat. Following the invention of sonar, soundings by the National Oceanic and Atmospheric Administration confirmed that depth.
The deepest point is in the north end of the lake, about 4 miles southwest of Stateline Point and about 1 mile west of the California-Nevada state line. The bottom at that point is 92 feet below the level of Carson City, Nevada, lying in the valley directly to the east. Tahoe is the tenth deepest lake in the world. A 1998 survey by the U.S. Geological Survey and the Ocean Mapping Group produced many stunning bathymetric images of the lake bottom and determined the deepest point at that time to be 1637 feet (499 m).

The average depth of Lake Tahoe is 989 feet (301 m), and with a surface area of 193 square miles (500 sq. km) the lake contains enough water to cover California to a depth of 14 inches, or Texas to a depth of 9 inches! Crater Lake in Oregon, with a depth of 1932 feet, is the only deeper lake in the United States. If Lake Tahoe was completely drained it would take over 700 years to refill!


Lake Tahoe lies in what was once a volcanic crater.

Although volcanic activity in the area helped shape the Tahoe Basin it was actually faulting that created a huge rift, or valley, where the lake now lies between the mountain ranges to the east and west. Volcanic flows sealed the south end of the valley and, much later, flows from Mount Pluto, which lies 3 miles northwest of Carnelian Bay, damned up the north end. Natural runoff of melting snow and ice then eventually filled the basin that had been formed.

Lake level in the early period following formation rose as much as 800 feet above the present average of 6225' (1897 m) above sea level, covering all of what is now South Lake Tahoe. The caves that gave Cave Rock its name, and that are located well above the tunnels cut through the rock for Highway 50, were actually formed by the wave action of the lake during that long era. Gradual erosion caused by the only outlet of the lake, now known as the Truckee River, eventually lowered the lake to its current level.

Water in Lake Tahoe is 99.4% pure.

Though still one of the cleanest, clearest lakes in the world, Lake Tahoe has been gradually losing cleanliness and clarity over the last 30 years, primarily due to the impact of man.

Enough water evaporates from the surface of the lake on an average day (1/10th of an inch, or over 330 million gallons!) to supply a city of 3.5 million people with its daily needs. Sixty-three different tributaries feed Lake Tahoe, but there is only one outlet, the Truckee River at Tahoe City. To better comprehend the astonishing amount of water that can flow into or out of the lake in a single day, see the graph on the Lake Level Data page.

The water temperature of Lake Tahoe below 600' remains at a constant 39° Fahrenheit (4° C) year-round and the water's continual motion prevents it from ever freezing over. The average surface temperature ranges from 41° Fahrenheit (5° C) in the winter to 68° F (20° C) in the summer. For average air temperatures in the Tahoe Basin visit the Weather page.