Lake Tahoe was formed between 5 and 10 billion years ago by the rising and falling of the land due to the shifting of geologic faults. Modern Lake Tahoe was shaped and landscaped by the glaciers that existed during the Ice Age, which began a million or more years ago.
Submerged stumps of trees have been found at elevations 16 ft. below the natural rim, indicating that Tahoe was much lower thousands of years ago.
Lake Tahoe, the eighth largest lake in the world, is known for its remarkable clarity. At times, it can extend to 75 ft. of underwater visibility and divers claim 200 ft. of visibility at times. This extreme clarity exists because a high percentage of precipitation falls directly into the lake while the remaining precipitation is filtered through marshes and meadows before reaching the lake.
The lake is 99.1 percent pure, allowing objects at 100 ft. to be clearly visable from the surface.
Surrounded by peaks of granite, which are common in the Sierra Nevada, Tahoe has an average surface elevation of 6,225 ft. above sea level. Mountain peaks rise to more than 10,000 ft. with the highest peaks at Monument Peak 10,067 ft., Pyramid Peak 9,983 ft. and Mt. Tallac 9,735 ft.
Lake Tahoe is 2/3 in California and 1/3 in Nevada and the floor of the Lake Tahoe Basin is at an elevation of about 4,580 ft., which is 92 ft. below the surface of Carson Valley to the east.
The Lake Tahoe Basin is located along the border of California and Nevada bound by the Sierra Nevada to the west and the Carson Range to the east. Most of the terrain is mountainous, limiting development mainly to flat lying areas along streams.
The lake is fed by 63 streams and two hot springs. The Truckee River at Tahoe City is the only outlet for the lake, which eventually feeds northeast into Pyramid Lake, never reaching an ocean.
The only fish truly native to this area is the Lahontan cuthroat trout, though mackinaw, rainbow trout and kokanee salmon also inhabit Tahoe. Non-natives were introduced as early as the mid-1800s to provide food for miners as the Lahontan fishery was drastically depleted.
Lake Tahoe is as long as the English Channel is wide. The Panama Canal, 700 ft. wide and 50 ft. deep, could be filled with Tahoe’s water, even if it circled the globe at the equator, and there would still be water left over to fill a canal of the same size running from San Francisco to New York.
The deepest part of Lake Tahoe is near Crystal Bay, measuring a water depth of 1,645 feet. If drained, it would take 700 years to refill the lake. Tahoe could provide every person in the United States with 50 gallons of water per day for 5 years. If the lake was tipped over, its contents would cover California in 14.5 inches of water, while Texas would be under 8.5 inches.
Lake Tahoe never freezes due to the depth and constant movement of water from the bottom to the surface although some protected areas such as Emerald Bay have been covered with a layer of ice.