The lake is situated in the valley of the Chagres River. It was formed, and the river widened and deepened, by the construction of the Gatun Dam about from the river's mouth in the Caribbean Sea 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 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 at its normal level of 26 m above sea level; it stores 5.2 cubic kilometres 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, home of the Smithsonian Tropical Research Institute. The lake has given its name to the Gatun structure, which may be an eroded impact crater.
Gatun Lake forms a major component of the Panama Canal; the lake, including the flooded arm extending up the Chagres River, makes up of the raised part of the waterway, the other part being the Culebra Cut. 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. Each time a ship transits the canal, 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, 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 to absorb rainfall, releasing it gradually into the lake. However, significant deforestation 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.
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 endured practically unscathed by human interference and is one of the few accessible areas on Earth where various native Central American animal and plant species can be observed undisturbed in their natural habitat. 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 important scientific and biological discoveries of the tropical animal and plant kingdom originated here. Lake Gatun encompasses a tropical ecological zone and ecotourism on Gatun Lake has become an industry for Panamanians. Angling is one of the primary recreational pursuits on Gatun Lake. Non-native Peacock Bass were introduced deliberately to Gatun Lake around 1967 by a local businessman, and have since flourished to become the dominant angling game fish in Gatun Lake. Locally called Sargento, and believed to be the species Cichla pleiozona, 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.
