* * * * * * * * * *
Lake Tahoe, at 1,644’ deep, is the second deepest lake in the U.S.
(Crater lake in Oregon, at 1,932’, is deeper). It is the 11th
deepest in the world.
*
* *
If Lake Tahoe was emptied, it would submerge California under 15”
of water.
*
* *
There is enough water in Lake Tahoe to supply everyone in the United States
with more than 75 gallons of water per day for 5 years.
*
* *
Lake Tahoe is as long as the English Channel is wide.
*
* *
Due to its depth, Lake Tahoe never freezes.
*
* *
The bottom of Lake Tahoe, at 4,580’ above sea level, is lower than
the Carson Valley floor in Nevada.
*
* *
About 2.7 million visitors come to Lake Tahoe annually.
How
The Lake Was Formed
About
3 to 5 million years ago, the valley that would become the Tahoe Basin
sank between parallel fractures in the Earth’s crust as the mountains
on either side continued to rise. A shallow lake began to form in the
resulting valley. Roughly 2 to 3 million years ago, erupting volcanoes
blocked the outlet, forcing the lake to rise hundreds of feet above its
current elevation, and eventually eroding down to near its current outlet.
Between 1 million and 20,000 years ago, large masses of glacial ice covered
the west side of the Tahoe Basin. Current geologic theory suggests an
earthen berm (moraine) left by a receding glacier near Olympic Valley
acted as a dam, causing the lake level to rise and then draw down rapidly
when the dam catastrophically failed. Between 7,000 and 15,000 years ago,
a 4-mile segment of the West Shore collapsed into the Lake causing a massive
submerged debris avalanche, widening the Lake by 3 miles and creating
McKinney Bay.1
The
Tahoe Basin is mostly granite, with little topsoil, and therefore few
nutrients have washed into the lake to promote the growth of algae and
other organisms that make water murky.
As
well, 40 percent of the precipitation falling into the Tahoe Basin, lands
directly on the lake. The remaining precipitation drains through the decomposed
granite soil found in marshes and meadows, creating a good filtering system
for water.
Lake
Tahoe’s large volume, relatively small watershed to the lake and
the surrounding geology are the primary reasons for its naturally clear
waters.
Urbanization
of the Tahoe Basin has eliminated 75 percent of its marshes, 50 percent
of its meadows and 35 percent of its steam zone habitats. About 85 percent
of all wildlife in the Tahoe Basin use these habitats.
About
The Lake
Lake
Tahoe is located in the states of California and Nevada, with two-thirds
in California. It is fed by 63 streams and two hot springs.
The
Truckee River is Tahoe’s only outlet and flows from the dam in Tahoe
City east through Reno and eventually drains into Pyramid Lake in the
Nevada desert. From there, it evaporates into the atmosphere.
Lake
Tahoe sits at an average surface elevation of between 6,223’, its
natural rim, and 6,299.1’ The top 6.1’ of water is controlled
by the dam in Tahoe City and holds up to 744,600 acre feet of water.
However,
water releases are not permitted when the lake surface level falls below
the natural rim at 6,223.’ The lowest lake level on record (measured
since 1900) was 6,220.26’ on Nov. 30, 1992.
Lake
Clarity
The
University of California, Davis, operates the Tahoe Environmental Research
Center, which monitors, among other things, the clarity of Lake Tahoe.
Clarity
has been measured since 1968 using a Secchi measurement, which is the
point below the lake surface at which a 10” white disk disappears
from view. The annual Secchi depth is comprised of about 25 readings throughout
the year.
The
waters of Lake Tahoe were clear to an average depth of 69.6’ in
2008. This keeps the clarity measurement in the range where it has been
for about the past eight years.
In
2008, UC Davis reported that data since 2001 suggested lake clarity was
not declining as fast as it had been. That encouraging finding is supported
by the 2008 average, which is nearly identical to the 2007 average of
70.1 feet.
Lake
Tahoe is losing clarity because of fine (microscopic) sediments entering
the lake and algae growth (fueled by nitrogen and phosphorus).
Lake
Tahoe’s Blue Color
The
lake water appears blue in color as other colors in the light spectrum
are absorbed and blue light is scattered back. In addition, under the
right conditions, the Lake surface can reflect the color of the sky.1
Tahoe’s
Native Peoples
Lake Tahoe and about
10,000 square miles of land surrounding the lake were once home to the
Washoe Indians, the native peoples to Lake Tahoe. They once wintered in
the Carson Valley and spent their summers on the shores of the lake hunting,
fishing and gathering foods for the winter.
About 1,500 members
of the Washoe Tribe of Nevada and California live on tribal lands known
as “colonies” scattered in the Reno, Carson Valley and Gardnerville
areas of Nevada and in Woodfords in California. An active tribal government
continues to lobby for a land base in the Lake Tahoe Basin. They also
work with federal and state agencies and private land owners to protect
locations important to Washoe Heritage.
Lake
Tahoe’s Discovery
The first recorded
discovery of Lake Tahoe by white explorers was on Feb. 14, 1844, when
John Charles Frémont and Charles Preuss spotted the lake from atop Red
Lake Peak. Frémont named the lake “Mountain Lake” and then
called it “L. Bonpland,” in honor of French botanist Aimé
Jacques Alexandre Bonpland. The name was changed to Lake Bigler in 1857
in honor of Calif. Gov. John Bigler. The lake was renamed Tahoe in 1945.
Tahoe is a mispronunciation
of the first two syllables of the Washoe’s word for the lake –
Da ow a ga, which means “edge of the lake.”
Sources:
Tahoe Environmental Research Center, U.S. Geological Survey, “Tahoe
Place Names” and David Antonucci (denoted by 1).
|
