Gatun Lake
Encyclopedia
Gatun Lake is a large artificial lake situated in the Republic of Panama
Panama
Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...

; it forms a major part of the Panama Canal
Panama Canal
The Panama Canal is a ship canal in Panama that joins the Atlantic Ocean and the Pacific Ocean and is a key conduit for international maritime trade. Built from 1904 to 1914, the canal has seen annual traffic rise from about 1,000 ships early on to 14,702 vessels measuring a total of 309.6...

, carrying ships for 33 km (20.5 mi) of their transit across the Isthmus of Panama
Isthmus of Panama
The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal...

.

The lake was created between 1907 and 1913 by the building of the Gatun Dam
Gatun Dam
The Gatun Dam is a large earthen dam across the Chagres River in Panama, near the town of Gatun. The dam, constructed between 1907 and 1913, is a crucial element of the Panama Canal; it impounds the artificial Gatun Lake, which in turn carries ships for of their transit across the Isthmus of Panama...

 across the Chagres River
Chagres River
The Chagres River is a river in central Panama. The central part of the river is dammed by the Gatun Dam and forms Gatun Lake, an artificial lake that constitutes part of the Panama Canal. Upstream lies the Madden Dam, creating the Alajuala Lake that is also part of the Canal water system...

. At the time it was created, Gatun Lake was the largest man-made lake in the world, and the dam was the largest dam on earth.

Description

The lake is situated in the valley of the Chagres River
Chagres River
The Chagres River is a river in central Panama. The central part of the river is dammed by the Gatun Dam and forms Gatun Lake, an artificial lake that constitutes part of the Panama Canal. Upstream lies the Madden Dam, creating the Alajuala Lake that is also part of the Canal water system...

. It was formed, and the river widened and deepened, by the construction of the Gatun Dam
Gatun Dam
The Gatun Dam is a large earthen dam across the Chagres River in Panama, near the town of Gatun. The dam, constructed between 1907 and 1913, is a crucial element of the Panama Canal; it impounds the artificial Gatun Lake, which in turn carries ships for of their transit across the Isthmus of Panama...

 about 10 km (6.2 mi) from the river's mouth in the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....

 in 1907–1913. The geography of the area was ideal for the creation of a large lake here; the hills bordering the valley of the Chagres open up widely around the area of the lake, but come together to form a gap just over 2 km (1.2 mi) wide at the location of the dam. The damming of the river flooded the originally wooded valley; almost a century later, the stumps of old mahogany trees can still be seen rising from the water, and submerged snags form a hazard for any small vessels that wander off the marked channels.

Gatun Lake has an area of 425 km² (164.1 sq mi) at its normal level of 26 m (85 ft) above sea level; it stores 5.2 cubic kilometres (183,000,000,000 ft³) of water, which is about as much as the Chagres River brings down in an average year.

With the creation of the lake many hilltops became islands. The biggest and best known of them is Barro Colorado Island
Barro Colorado Island
Barro Colorado Island is located in the man-made Gatun Lake in the middle of the Panama Canal. The island was formed when the waters of the Chagres River were dammed to form the lake. When the waters rose, they covered a significant part of the existing rainforest, and the hilltops remained as...

, home of the world famous Smithsonian Tropical Research Institute
Smithsonian Tropical Research Institute
The Smithsonian Tropical Research Institute in Panama, the only bureau of the Smithsonian Institution based outside of the United States, is dedicated to understanding biological diversity. What began in 1923 as small field station on Barro Colorado Island in the Panama Canal Zone has developed...

 (STRI).

The lake has given its name to the Gatun structure
Gatun structure
The Gatun structure is a possible eroded impact crater. It is named after the nearby Gatun Lake in Panama. It was first discovered in 1972 by geologist Bob Stewart and later studied by Livio L. Tornabene from the University of South Florida Department of Geology.The structure is estimated to have...

, which may be an eroded impact crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

.

Role in the canal

Gatun Lake forms a major component of the Panama Canal
Panama Canal
The Panama Canal is a ship canal in Panama that joins the Atlantic Ocean and the Pacific Ocean and is a key conduit for international maritime trade. Built from 1904 to 1914, the canal has seen annual traffic rise from about 1,000 ships early on to 14,702 vessels measuring a total of 309.6...

; the lake, including the flooded arm extending up the Chagres River, makes up 32.7 km (20.3 mi) of the raised part of the waterway, the other part being the 12.6 km (7.8 mi) Gaillard Cut
Gaillard Cut
The Gaillard Cut, or Culebra Cut, is an artificial valley that cuts through the continental divide in Panama. The cut forms part of the Panama Canal, linking Lake Gatún, and thereby the Atlantic Ocean, to the Gulf of Panama and hence the Pacific Ocean...

.

The canal follows a clearly marked route around the lake's islands, following the deeper water south from Gatun Locks, and then east. A small "shortcut" channel, the "Banana Cut", runs between the islands, providing a slightly shorter route through the lake; this is used by canal launches and yachts to cut a little time off the crossing, and to avoid the heavy ship traffic.

The lake is also important as a reservoir of water for the operation of the canal locks
Panama Canal Locks
The Panama Canal Locks, which lift ships up 25.9 m to the main elevation of the Panama Canal, were one of the greatest engineering works ever to be undertaken at the time, eclipsed only by other parts of the canal project. No other concrete construction of comparable size was undertaken...

. Each time a ship transits the canal 202000 m³ (53,362,751.5 US gal) of water is passed from the lake into the sea; with over 14,000 vessel transits per year, this represents a very large demand for water. Since rainfall is seasonal in Panama
Panama
Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...

, the lake acts as a water store, allowing the canal to continue operation through the dry season.

A major factor in water regulation is the ability of the rainforest in the lake's watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 to absorb rainfall, releasing it gradually into the lake. However, significant deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

 of the watershed has cleared away much of the vegetation, and reduced the area's water capacity. This has resulted in falling water levels in the lake during the dry season. Coupled with the massive increase in canal traffic since its opening, and the resultant increase in water usage, this is an ongoing problem for the canal (see Panama Canal: Water issues).

Gatun Lake supplementary benefits

Created in 1913 by the damming of the Chagres River, Gatun Lake is an essential part of the Panama Canal which forms a water passage between the Atlantic Ocean and the Pacific Ocean, permitting ship transit in both directions. At the time it was formed, Gatun Lake was the largest man-made lake in the world. The impassable rain-forest around Gatun Lake has been the best defense of the Panama Canal. Today these areas have endured practically unscathed by human interference and are one of the few accessible areas on earth that various native Central American animal and plant species can be observed undisturbed in their natural habitat.

World famous Barro Colorado Island, which was established for scientific study when the lake was formed and is today operated by the Smithsonian Institution, is the largest island on Gatun Lake. Many of the most important ground breaking scientific and biological discoveries of the tropical animal and plant kingdom originated here. Lake Gatun encompasses approximately 180 square miles (466.2 km²), a vast tropical ecological zone part of the Atlantic Forest Corridor and Eco-tourism on Gatun Lake has become a worthwhile industry for Panamanians. Gatun Lake also serves to provide the millions of gallons of water necessary to operate the Panama Canal locks each time a ship passes through and provides drinking water for Panama City and Colon.

Angling is one of the primary recreational pursuits on Gatun Lake. It is suspected that the Cichla Pleiozona species of Peacock Bass was introduced by accident to Gatun Lake by a renowned Panamanian aquarist and doctor in 1958. Locally called Sargento these peacock bass are not a native game fish of Panama but originate from the Amazon, Rio Negro and Orinoco river basins of South America where they are called Tucanare or Pavon and are considered a premier game fish. Since 1958 the Cichla Pleiozona species of Peacock Bass have flourished to become the dominant angling game fish in Gatun Lake of the Panama Canal.
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