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Crater LakeIntroduction |
Introduction to Crater Lake National Park (NP) in Oregon. Published by the National Park Service (NPS).
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Crater Lake
National Park Service
U.S. Department of the Interior
Crater Lake National Park
Introduction to Crater Lake
Crater Lake Is Like No
Place Else On Earth
Crater Lake has inspired its visitors for hundreds of years. No place else on earth
combines such a deep, pure lake with sheer surrounding cliffs and a violent volcanic
past. Few places on earth are so beautiful, so pristine, or—for these very reasons—so
interesting to scientists.
An Introduction to
Crater Lake
Crater Lake is located in Southern Oregon on the
crest of the Cascade Mountain range, 100 miles
(160 km) east of the Pacific Ocean. It lies inside a
caldera, or volcanic basin, created when the 12,000
foot (3,660 meter) high Mount Mazama collapsed
7,700 years ago following a large eruption.
Generous amounts of winter snow, averaging 528
inches (1,341 cm) per year, supply the lake with
water. There are no inlets or outlets to the lake.
Crater Lake, at 1,943 feet (592 meters) deep, is the
seventh deepest lake in the world and the deepest
in the United States. Evaporation and seepage
prevent the lake from becoming any deeper.
The lake averages more than five miles (8 km) in
diameter, and is surrounded by steep rock walls
that rise up to 2000 feet (600 meters) above the
lake's surface.
Physical Characteristics
Color:
The color of Crater Lake is the product of its great
depth, the purity and clarity of its water, and the
way solar radiation interacts with water. Water
molecules absorb the longer wavelengths of light
better (reds, oranges, yellows, and greens). This
energy slowly heats the lake throughout the summer. Shorter wavelengths (blues) are more easily
Following the collapse of Mount Mazama, lava
poured into the caldera even as the lake began to
rise. Today, a small volcanic island, Wizard Island,
appears on the west side of the lake. This cinder
cone rises 767 feet (234 meters) above the lake and
is surrounded by black volcanic lava blocks. A
small crater, 300 feet (90 meters) across and 90 feet
(27 meters) deep, rests on the summit. The crater is
filled by snow during the winter months, but remains dry during the summer.
The lake level fluctuates slightly from year to year.
The highest level was reached in 1975 when the
water level rose to 6,179.34 feet (1,883.47 meters)
above sea level. The lowest level was recorded in
1942 when it dropped to 6,163.20 feet (1,878.55
meters). For such a deep lake, the maximum observed variation of 16 feet (5 meters) is minor (less
than 1 percent).
scattered than absorbed. In the deep lake, some of
the scattered blue light is redirected back up to the
surface where we can see it. Around the edges
where the water is less deep, some of the unabsorbed green sunlight is reflected back up. The
color of the lake can vary from day to day depending on wind, cloud cover, and the angle of the sun.
Physical Characteristics
(continued)
Why Is the Lake So Blue?
Light Penetration:
Sunlight is able to penetrate the waters of Crater
Lake to great depths. Researchers often use a
reflector called a Secchi disk to determine lake
clarity. Readings deeper than 100 feet (30 meters) in
most lakes are rare, but they can typically reach 120
feet (37 meters) at Crater Lake. A reading of 142
feet (43.3 meters) was recorded in 1997.
beneath the surface remains near 38°F (3°C) all
year long. During the hottest time of the summer,
the top water layers warm and become less dense
than colder water below. This condition of thermal
stratification usually continues into September.
Temperature:
Surface temperatures of the lake water vary between 32°F (0°C) and 66°F (19°C). Summer temperatures typically range between 50°F (10°C) and
60°F (16°C). Water more than 260 feet (80 meters)
The lake rarely freezes in winter because of the
large amount of heat stored in the lake during the
summer, windy surface conditions, and relatively
mild air temperatures. The most significant complete freezing event in recent history occurred
between January and April in 1949. The lake was
mostly covered with ice twice in 1985, in January
and again in December.
1)
3)
2)
Most of the annual input comes directly from
precipitation.
No stream or creek flows into the lake carrying
dissolved minerals or dust.
4)
Seepage removes minerals already dissolved in
the lake.
Volcanic rocks below the water line are relatively insoluble in cold lake water.
Water Circulation
The upper 600 feet (180 meters) of lake water
appears to be well mixed based upon the degree of
oxygen saturation. Studies indicate that some
surface water mixes annually to the lake bottom
but a total turnover of lake water is incomplete. As
many as six years may be necessary to totally
exchange lake water at the bottom with oxygenrich surface water.
Hydrothermal Springs
Lake researchers have discovered two areas on the
lake bottom affected by hydrothermal spring water.
Mineral-rich water, at a slightly elevated tempera-
ture, pools in some locations and leaves iron deposits in others. Communities of bacteria mark the
venting sites.
Aquatic Life
Between 1888 and 1942, more than 1.8 million fish
were introduced into Crater Lake. Today, rainbow
trout and kokanee salmon can be seen swimming in
the lake.
forms is greatly restricted by the low concentrations of nitrogen in the lake.
Scientist have identified 157 different species of
phytoplankton and 12 species of zooplankton in the
lake. The density and diversity of these minute life
Statistics
Average lake surface elevation
Greatest depth
Average depth
Shallowest depth
Surface area
Widest point
Narrowest point
Wizard Island
Phantom Ship
Hillman Peak
Palisade Point
Sinnott Memorial
Average height of rim
Rim Village to Wizard Island
EXPERIENCE YOUR AMERICA
Large colonies of moss circle the lake at a depth
between 100 feet (30 meters) and 400 feet (120
meters). The unusual clarity of the lake water
permits the moss to thrive at depths found nowhere else.
6,173 feet (1,881 meters) above sea level
1,943 feet (592 meters)
1,148 feet (350 meters)
15-25 feet (6 meters) at Phantom Ship
30-60 feet (14 meters) at Skell Channel
21 square miles (5400 ha)
6.02 miles (9.69 km) from Discovery Point to Grotto Cove
4.54 miles (7.31 km) from Dutton Cliff to Llao Rock
767 feet (234 meters) above the lake surface
170 feet (52 meters) above the lake surface
1,978 feet (603 meters) above the water, highest point on the rim
507 feet (155 meters) above the water, lowest point on the rim
900 feet (270 meters) above the lake
1,000 feet (300 meters) above the lake
2 miles (3 km)
R e v. 7/2002 klb