http://www.worldlakes.net en-us Tue, 06 Jan 2009 04:55:42 -0600 http://www.worldlakes.net/crater-lake/ Crater Lake is one of the most famous and interesting lakes not only in the U.S, but in the whole world. It is located in Oregon. It is the main feature of Crater Lake National Park and famous for its deep blue color and water clarity. The lake partly fills a nearly 4,000 foot (1,220 m) deep caldera that was formed around 5,677 (± 150) BC by the collapse of the volcano Mount Mazama.

On June 12, 1853, John Wesley Hillman was reportedly the first European American to see what he named "Deep Blue Lake" in Oregon. The lake changed it name at least three times, as Blue Lake, Lake Majesty, and finally, the final one, Crater Lake.

Crater Lake is known for the "Old Man of the Lake," a full-sized tree that has been bobbing vertically in the lake for more than a century. Due to the cold water of the lake, the tree has been rather well preserved.

While having no indigenous fish population, the lake was stocked from 1888 to 1941 with a variety of fish. Several species have formed self sustaining populations.

The commemorative Oregon State Quarter, which was released by the United States Mint in 2005, features an image of Crater Lake on its reverse side.

The lake is 5 by 6 miles (8 by 9.6 km) across with an average depth of 1,148 feet (350 m). Its deepest point has been measured at 1,949 feet (594 m) deep, though as with any lake its depth fluctuates with the climate, particularly rainfall. This makes Crater Lake the deepest lake in the United States, the second deepest lake in North America (Great Slave Lake is the deepest) and the ninth deepest lake in the world (Lake Baikal is the deepest). Crater Lake is often cited as the 7th deepest lake in the world, but this result excludes the recent discovery of subglacial Lake Vostok, which is situated under nearly 13,000 feet (4000 m) of Antarctic ice, and the recent soundings of O'Higgins/San Martín Lake, which is located on the border of Chile and Argentina.

However, on the basis of comparing average depths among the world's deepest lakes, Crater Lake becomes the deepest lake in the Western Hemisphere and the third deepest in the world. Comparing average depths among the world's lakes whose basins are entirely above sea level, Crater Lake is the deepest.

The caldera rim of Crater Lake ranges in elevation from 7,000 to 8,000 feet (2,130 to 2,440 m).

Mount Mazama, part of the Cascade Range volcanic arc, was built up mostly of andesite, dacite, and rhyodacite over a period of at least 400,000 years. The caldera was created in a massive volcanic eruption that led to the subsidence of Mount Mazama around 5700 BC: about 50 cubic kilometers (12 cubic miles) of rhyodacite was erupted in this event. Since that time, all eruptions on Mazama have been confined to the caldera.

Lava eruptions later created a central platform, Wizard Island, Merriam Cone, and other, smaller volcanic features, including a rhyodacite dome that was eventually created atop the central platform. Sediments and landslide debris also covered the caldera floor.

In time, the caldera cooled, allowing rain and snow to accumulate and eventually form a lake. Landslides from the caldera rim thereafter formed debris fans and turbidite sediments on the lake bed. Fumaroles and hot springs remained common and active during this period. Also after some time, the slopes of the lake's caldera rim more or less stabilized, streams restored a radial drainage pattern on the mountain, and dense forests began to revegetate the barren landscape. It is estimated that about 720 years was required to fill the lake to its present depth of 594 m. Much of this occurred during a period when the prevailing climate was less moist than at present.

Some hydrothermal activity remains along the lake floor, suggesting that at some time in the future Mazama may erupt once again.

Due to several unique factors, most prominently that it has no inlets or tributaries, the waters of Crater Lake are some of the purest in terms of the absence of pollutants in North America.

Secchi disk clarity readings have consistently been in the high-20 meter to mid-30 meter (80-115 ft) range, which is very clear for any natural body of water. In 1997, scientists recorded a record clarity of 43.3 meters (142 ft).

The lake has relatively high levels of dissolved salts, total alkalinity, and conductivity. The average pH has generally ranged between 7 and 8.

The Klamath tribe of Native Americans, who may have witnessed the collapse of Mount Mazama and the formation of Crater Lake, have long regarded the lake as a sacred site. Their legends tell of a battle between the sky god Skell and Llao, the god of the underworld. Mount Mazama was destroyed in the battle, creating Crater Lake. The Klamath people used Crater Lake in vision quests, which often involved climbing the caldera walls and other dangerous tasks. Those who were successful in such quests were often regarded as having more spiritual powers. The tribe still holds Crater Lake in high regard as a spiritual site.

The Crater Lake is covered with mystery, but it is a wonderful place to visit and explore. ]]> Tue, 30 Sep 2008 01:43:19 -0500 http://www.worldlakes.net/crater-lake/ http://www.worldlakes.net/lake-atitlan/ Lake Atitlán, which is also known as Lago de Atitlán is a large historic lake in the Guatemalan Highlands. While Atitlan is thought to be the deepest lake in Central America, it's bottom has not been completely sounded. Estimates of its maximum depth range up to 340 meters. The lake is shaped by deep escarpments which surround it and by three volcanoes on its southern flank. Lake Atitlan is further characterized by towns and villages of the Maya people.

The lake is volcanic in origin, filling an enormous caldera formed in an eruption 84000 years ago. It is renowned as one of the most beautiful lakes in the world, and Aldous Huxley famously wrote of it: "Lake Como, it seems to me, touches on the limit of permissibly picturesque, but Atitlán is Como with additional embellishments of several immense volcanoes. It really is too much of a good thing."

The lake basin supports extensive coffee growth and a variety of farm crops, most notably corn. Other significant agricultural products include onions, beans, squash, tomatoes, cucumbers, garlic, chile verde, strawberries, avocados and pitahaya fruit. The lake itself is rich in animal life which provides a significant food source for the largely indigenous population.

The region first saw volcanic activity about 11 million years ago, and since then has seen four separate episodes of volcanic growth and caldera collapse, the most recent of which began about 1.8 million years ago and culminated in the formation of the present caldera. The lake now fills a large part of the caldera, with depts over 600m!

The caldera-forming eruption is known as Los Chocoyos eruption, and ejected up to 300 km³ of tephra. The enormous eruption dispersed ash over an area of some 6 million km²: it has been detected from Florida to Ecuador, and can be used as a stratigraphic marker in both the Pacific and Atlantic oceans. A chocoyo is a type of bird which is often found nesting in the relatively soft ash layer.

Since the end of Los Chocoyos, continuing volcanism has built three volcanoes in the caldera. Volcán Atitlán lies on the northern rim of the caldera, while Volcán San Pedro and Volcán Tolimán lie within the caldera. San Pedro is the oldest of the three and seems to have stopped erupting about 40,000 years ago. Tolimán began growing after San Pedro stopped erupting, and probably remains active, although it has not erupted in historic times. Atitlán has grown almost entirely in the last 10,000 years, and remains active, with its most recent eruption having occurred in 1853.

On February 4, 1976 a massive earthquake (magnitude 7.5) struck Guatemala killing more than 26,000 people. The earthquake fractured the lake bed causing subsurface drainage from the lake, allowing the water level to drop two meters within one month.

In 1955, the area around Lago de Atitlán became a national park. The lake was mostly unknown to the rest of the world and Guatemala was seeking ways to increase tourism and boost the local economy. It was suggested by Pan American World Airways that stocking the lake with a fish prized by anglers would be a way to do just that. So, a non-native species, the black bass, was introduced into the lake in 1958. The bass quickly took to its new home and began eating the native inhabitants of the lake. The predatory bass caused the elimination of more than two-thirds of the native fish species in the lake and contributed to the extinction of the giant grebe, a rare bird that lived only around the Lago de Atitlán region. ]]> Tue, 29 Apr 2008 06:12:06 -0500 http://www.worldlakes.net/lake-atitlan/ http://www.worldlakes.net/lake-victoria/ Lake Victoria or Victoria Nyanza (also known as Ukerewe and Nalubaale) is one of the Great Lakes of Africa.

Lake Victoria is 68,800 square kilometres (26,560 mi?) in size, making it the continent's largest lake, the largest tropical lake in the world, and the second largest fresh water lake in the world in terms of surface area (third largest if one considers Lake Michigan-Huron as a single lake). Being relatively shallow for its size, with a maximum depth of 84 m (276 ft) and a mean depth of 40 m (131 ft), Lake Victoria ranks as the seventh largest freshwater lake by volume, containing 2,750 cubic kilometres (2.2 million acre-feet) of water. It is the source of the longest branch of the Nile River, the White Nile, and has a water catchment area of 184,000 square kilometres (71,040 mi?). It is a biological hotspot with great biodiversity. The lake lies within an elevated plateau in the western part of Africa's Great Rift Valley and is subject to territorial administration by Tanzania, Uganda and Kenya. The lake has a shoreline of 3,440 km (2138 miles), and has more than 3,000 islands, many of which are inhabited. These include the Ssese Islands in Uganda, a large group of islands in the northwest of the Lake that are becoming a popular destination for tourists.

The first recorded information about Lake Victoria comes from Arab traders plying the inland routes in search of gold, ivory, other precious commodities and slaves. An excellent map known as the Al Adrisi map dated from the 1160s, clearly depicts an accurate representation of Lake Victoria, and attributes it as being the source of the Nile.

The lake was first sighted by Europeans in 1858 when the British explorer John Hanning Speke reached its southern shore whilst on his journey with Richard Francis Burton to explore central Africa and locate the great Lakes. Believing he had found the source of the Nile on seeing this vast expanse of open water for the first time, Speke named the lake after the then Queen of the United Kingdom. Burton, who had been recovering from illness at the time and resting further south on the shores of Lake Tanganyika, was outraged that Speke claimed to have proved his discovery to have been the true source of the Nile, which Burton regarded as still unsettled. A very public quarrel ensued, which not only sparked a great deal of intense debate within the scientific community of the day, but much interest by other explorers keen to either confirm or refute Speke's discovery.

The well known British explorer and missionary David Livingstone failed in his attempt to verify Speke's discovery, instead pushing too far west and entering the Congo River system instead. It was ultimately the American explorer Henry Morton Stanley who confirmed the truth of Speke's discovery, circumnavigating the Lake and reporting the great outflow at Ripon Falls on the Lake's northern shore.

Lake Victoria plays a vital role in supporting the millions of people living around its shores, in one of the most densely populated regions on earth.

The ecosystems of Lake Victoria and its surroundings have been badly affected by human influence. In 1954, the Nile perch (Lates niloticus) was first introduced into the lake's ecosystem in an attempt to improve fishery yields of the lake. Introduction efforts intensified during the very early 1960s. The species was present in small numbers until the early to mid 1980s, when it underwent a massive population expansion and came to dominate the fish community and ecology of the world's largest tropical lake. Also introduced was the Nile tilapia (Oreochromis niloticus), now an important food fish for local consumption. The Nile perch (Lates niloticus) proved ecologically and socioeconomically devastating. Together with pollution born of deforestation and overpopulation (of both people and domestic animals), the Nile perch has brought about a massive transformation in the lake ecosystem and to the disappearance of hundreds of endemic haplochromine cichlid species. Many of these are now presumed to be entirely extinct. A number of other species are extinct in the wild, with populations being maintained in zoos and aquaria, e.g. as part of the Association of Zoos and Aquarium's Species Survival Plan for these species. Some species which were extirpated from Lake Victoria itself, are known to survive in nearby smaller so-called satellite lakes, such as Lake Kyoga, Lake Edward, and Lake Albert.

Also vanished from Lake Victoria is one of two native species of tilapia (another kind of cichlid fish), the Singidia tilapia or ngege (Oreochromis esculentus). The ngege is superior in taste and texture to Nile tilapia, but it does not grow as fast or as large and produces fewer young. Ngege and some representatives of haplochromine diversity survive in minute swamp ponds and lakes that dot the Lake Victoria Basin. The initial good returns on Nile perch catches, at their peak delivering export revenues of several hundred million dollars a year, have diminished dramatically due to poor enforcement of fisheries regulations. The proceeds from Nile perch sales remain an important economic engine in the region, but the resulting wealth is very poorly distributed and the overall balance sheet on the Nile perch introduction to Lake Victoria is well into the red despite the enormous value of the perch landings as an export commodity.

The three countries bordering Lake Victoria - Uganda, Kenya and Tanzania - have agreed in principle to the idea of a tax on Nile perch exports, proceeds to be applied to various measures to benefit local communities and sustain the fishery. However, this tax has not been put into force, enforcement of fisheries and environmental laws generally are lax, and the Nile perch fishery remains in essence a mining operation.

Currently, the Nile perch is being overfished. Populations of a few endemic cichlid species have increased again, particularly one to three species of zooplankton-eating, herring-like cichlids (Yssichromis) that school with the abundant native Silver Cyprinid (Rastrineobola argentea), known locally as dagaa (Tanzania), omena (Kenya) or mukene (Uganda). In 1996 The World Bank funded a project to restore and sustain the ecology of Lake Victoria and its fisheries, called LVEMP (Lake Victoria Environmental Management Project).

Meanwhile, the EU invested another large sum in fisheries infrastructure and monitoring. Few of the excellent intentions of these projects have been actualized despite massive expenditures, but the potential for things to be set aright is still great and through it all the ecology of Lake Victoria, in its new incarnation, has proven amazingly resilient. One beneficial product of these foreign aid programs has been the training of a new generation of east African aquatic ecologists, conservation professionals, and fisheries scientists. There has also been a renaissance in the fishery research institutes of the lake. Unfortunately, few of the new professionals find jobs, and fewer still find jobs that allow them to apply what they have learned to solving, rather than perpetuating, the deep problems that still beset the relationship between people and the lake.

An eco-problem with a happier outcome was the fight against the huge increase of the water hyacinth Eichhornia crassipes, a native of the tropical Americas, which forms thick mats of plant causing difficulties to transportation, fishing, hydroelectric power generation and drinking water supply. By 1995, 90% of the Ugandan coastline was covered by the plant. With mechanical and chemical control of the problem seeming unlikely, the mottled water hyacinth weevil Neochetina eichhorniae was bred and released with very good results.

Since the 1900s Lake Victoria ferries have been an important means of transport between Uganda, Tanzania and Kenya. The main ports on the lake are Kisumu, Mwanza, Bukoba, Entebbe, Port Bell and Jinja. The steamer MV Bukoba sank in the lake on October 3, 1995, killing nearly 1,000 people in one of Africa's worst maritime disasters. ]]> Sun, 03 Feb 2008 11:01:13 -0600 http://www.worldlakes.net/lake-victoria/ http://www.worldlakes.net/baikal-lake/ Lake Baikal, which is located in Russia, is one of the biggest lakes in the world. At 1,637 meters, Lake Baikal is the deepest lake in the world and with a volume 23,000 km? it holds the largest body of fresh water on earth, approximately twenty percent of the world's total surface fresh water. Lake Baikal was formed in an ancient rift valley and therefore is long and crescent-shaped with a surface area (31,500 km?). Baikal is home to more than 1,700 species of plants and animals, two thirds of which can be found nowhere else in the world and was declared a UNESCO World Heritage Site in 1996. Also, it is the oldest lake and it is more that 25 million years old! Baikal is so big, that it has more water that all lake in the United States combined together. It even has it's own island - Olkhon.

Due to it's location - Northern Siberia, it was very hard to study it before the Trans-Siberian railway was built. The lake is completely surrounded by mountains. The Baikal Mountains on the north shore and the taiga are technically protected as a national park. It contains 22 islands; the largest, Olkhon, is 72 kilometers long. The lake is fed by as many as three hundred and thirty inflowing rivers. The six main ones are the Selenga River (the source of some of Lake Baikal's pollution), the Chikoy River, the Khilokh, the Uda River, the Barguzin River, and the Upper Angara River. It is drained through a single outlet, the Angara River.

Although there were muted protests, a wood pulp and cellulose processing plant was built at the south end of the lake (at Baykalsk). The plant still pours industrial effluent into Baikal's waters. The overall impacts of watershed pollution on Baikal and similar watersheds are studied annually by the Tahoe-Baikal Institute, an exchange program between U.S., Russian, and Mongolian scientists and university graduate students started in 1990.

Lake Baikal hosts 1,085 species of plants and 1,550 species and varieties of animals. Over 80% of animals are endemic. The Baikal Seal or nerpa, is found throughout Lake Baikal. It is one of the only entirely freshwater seal species in the world. Perhaps the most important local species is the omul, a smallish endemic salmonid. It is caught, smoked, and sold widely in markets around the lake. But it's very hard to find some of those things not only outside Russia, but even Baikal itself.

The lake called "the Pearl of Siberia" drew investors from the tourist industry since energy revenues sparked an economic boom. Viktor Grigorov's Grand Baikal in Irkutsk is one of the investors who planned to build three hotels creating 570 jobs. In 2007, the Russian government declared the Baikal region a special economic zone. The popular resort of Listvyanka has a seven-story Hotel Mayak. Baikal is a UNESCO World Heritage site. Rosatom plans to build a laboratory in Baikal, in conjunction with an international uranium plant and to invest $2.5bn in the region and create 2,000 jobs in the city of Angarsk.

Baikal is also a very mysterious place. The legends say that many strange things happen there. Monsters, like in Lohness, mermaids, like in the Black Sea, ghosts and spirits are seen there all the time. UFO's are a common thing there. Shamans say, that it is a sacred place and people, who are far from the spirit world should stay away from Baikal at night.

Still, people go there and it is a very popular resort. Untouched nature, clean water and a great atmosphere - all that can be found in the heart of Siberia - Baikal! ]]> Sat, 22 Dec 2007 10:10:38 -0600 http://www.worldlakes.net/baikal-lake/