Why is Lake Tahoe so deep? Lake Tahoe’s depth is 501m, was actually formed by geologic block faulting 25 million years ago.
Lake Tahoe, located in the mountains of Northern California, is 22 miles long and 12 miles wide. Its surface area of 121 square miles creates 72 miles of coastline around the lake — and room for countless travel opportunities among the natural beauty that almost led it to become a National Park.
The lake was formed through faulting of the Earth’s crust, volcanism and glaciation.
About 25 million years ago the Sierra Nevada block was formed by tremendous uplifting. The valley that later became the Tahoe Basin sank between two parallel faults as the mountains on either side rose. Water filled this Basin where Lake Tahoe lies today.
Lava flowing from Mt. Pluto on the north shore formed a barrier or dam across the basin’s outlet. Water from rivers and streams flowed into the Basin gradually filling it several hundred feet above its present level.
During the last Ice Age, less than a million years ago, huge ice blocks or glaciers formed in the surrounding mountains. These glaciers scoured the landscape, carving broad U-shaped valleys now occupied by Cascade Lake, Fallen Leaf Lake, and Emerald Bay. The material left after the glaciers melted, called moraines, blocked the original outlet of Lake Tahoe, changing it to the present Truckee River outlet at Tahoe City.
There are 63 streams that flow into Lake Tahoe and only one, the Truckee River, that flows out into Pyramid Lake. Unlike most bodies of water in North America, Tahoe’s water never reaches the ocean.
The water in Lake Tahoe could cover a flat area the size of California to a depth of 14 inches. This is enough to supply everyone in the United States with 50 gallons of water per day for five years. And believe it or not, the amount of water that evaporates from the surface of Lake Tahoe every year could supply a city the size of Los Angeles for five years.
Tahoe is so clear that in some places objects can be seen to depths of over 70 feet. One reason is that 40 percent of the precipitation falling into the Lake Tahoe Basin falls directly upon the Lake. The remaining precipitation drains through the marshes and meadows, which are a good filtering system for water. Unfortunately, many of the Lake’s natural filtering systems have been disturbed by development and Tahoe’s clarity is diminishing.
Tahoe’s clean air and water are the keys to the Lake’s dazzling blue color. The surface of Lake Tahoe is blue in part because it’s reflecting the sky, but there is more to this phenomenon. Water as crystal clear as Tahoe’s absorbs red light, leaving the rich blue color that we all see.
