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Lanao Lake

Lake Lanao
Lake Lanao zoom.jpg
Landsat photo
Lake Lanao is located in Philippines
Lake Lanao
Lake Lanao
Location within the Philippines
Lake Lanao-Agus watershed2.png
Lake Lanao-Agus River watershed map
Location Lanao del Sur
Coordinates 7°53′31″N 124°15′09″E / 7.89194°N 124.25250°E / 7.89194; 124.25250Coordinates: 7°53′31″N 124°15′09″E / 7.89194°N 124.25250°E / 7.89194; 124.25250
Lake type Rift lake
Primary inflows 4 tributaries
Primary outflows Agus River
Basin countries Philippines
Max. length 33 km (21 mi)
Max. width 20 km (12 mi)
Surface area 340 km2 (130 sq mi)
Average depth 60.3 m (198 ft)
Max. depth 112 m (367 ft)
Shore length1 115 km (71 mi)
Surface elevation 700 m (2,300 ft)
Settlements
1 Shore length is not a well-defined measure.

Lake Lanao (Maranao: Ranao or Ranaw) is a large lake in the Philippines, located in Lanao del Sur province in the country's southern island of Mindanao. With a surface area of 340 km2 (130 sq mi), it is the largest lake in Mindanao, and the second largest lake in the Philippines and counted as one of the 15 ancient lakes in the world.

The lake was formed by the tectonic-volcanic damming of a basin between two mountain ranges and the collapse of a large volcano. It has a maximum depth of 122 m (400 ft), and a mean depth of 60.3 m (198 ft). The basin is shallowest towards the north and gets progressively deeper towards the south.

The lake is fed by four rivers. Its only outlet is the Agus River, which flows northwest into Iligan Bay via two channels, one over the Maria Cristina Falls and the other over the Linamon Falls. A hydroelectric plant installed on the Lanao Lake and Agus River system generates 70% of the electricity used by the people of Mindanao.

The lake is a home of myths and legends of the Meranaw tribe. The name Meranaw was derived from the name of the lake and it means "the people living around the lake".

Lake Lanao was proclaimed as a watershed reservation in 1992 through Presidential Proclamation 971 to ensure protection of forest cover and water yield for hydropower, irrigation and domestic use.

The lake is (or was) home to 18 endemic species of cyprinid fish in the genus Barbodes (most were formerly in Puntius). It also supports a large number of waterfowl. An investigations in 1992 only managed to locate three of the endemic fish species, and only two (Barbodes lindog and B. tumba) were located in 2008. It is believed that overfishing, pollution and competition from introduced species caused the extinction of the remaining. In October 2006, a study from the Mindanao State University discovered massive algae contamination in Lake Lanao. Initially, poor sewage and agricultural waste management were seen as the culprit to the contamination. However, the Department of Agriculture and the Bureau of Fisheries and Aquatic Resources stated that soil erosion from indiscriminate logging and extensive land use and farming are the problems that caused the algae contamination. Around 42 endemic crab species can also be found in Lake Lanao.


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