Lake Lanao
Lake Lanao is a large lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 in the Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

, located in Lanao del Sur
Lanao del Sur
Lanao del Sur is a province of the Philippines located in the Autonomous Region in Muslim Mindanao . Its capital is Marawi City and borders Lanao del Norte to the north, Bukidnon to the east, and Maguindanao and Cotabato to the south. To the southwest lies Illana Bay, an arm of the Moro Gulf...

 province in the country's southern island of Mindanao
Mindanao is the second largest and easternmost island in the Philippines. It is also the name of one of the three island groups in the country, which consists of the island of Mindanao and smaller surrounding islands. The other two are Luzon and the Visayas. The island of Mindanao is called The...

. With a surface area
Surface area
Surface area is the measure of how much exposed area a solid object has, expressed in square units. Mathematical description of the surface area is considerably more involved than the definition of arc length of a curve. For polyhedra the surface area is the sum of the areas of its faces...

 of 340 km². (131 square miles), it is the largest lake in Mindanao, and the second largest lake in the Philippines
Lakes in the Philippines
The origin of most of the lakes in the Philippines is closely related to volcanic and seismic activity. A number of smaller lakes occupy the craters of extinct volcanoes. Some lake basins are developed by subsidence resultant upon plate tectonics or volcanic activity...

 and counted as one of the 15 ancient lake
Ancient Lake
An ancient lake is a lake that carried water uninterruptedly for more than one million years. The vast majority of lakes, including very large ones such as the Great Lakes, are of much more recent origin...

s in the world.

Physical Characteristics

The lake was formed by the tectonic-volcanic damming of a basin between two mountain range
Mountain range
A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...

s and the collapse of a large volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

. It has a maximum depth of 112 meters, and a mean depth of 60.3 meters. The basin
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...

 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
Agus River
Agus River is a river that flows for 36.5 km from Lanao Lake to Iligan Bay, Philippines. It cuts through the provinces of Lanao del Sur and Lanao del Norte. Settlements along the banks of the river include the City of Marawi, the Municipality of Linamon and the City of Iligan...

, which flows southwest into Iligan Bay
Iligan Bay
Iligan Bay is a bay in Mindanao in the Philippines. It is part of Bohol Sea and cuts into the northern portion of the island of Mindanao. The provinces along its coast are Misamis Occidental, Misamis Oriental, Zamboanga del Sur, and Lanao del Norte. Iligan City is the most important port on Iligan...

 via two channels, one over the Maria Cristina Falls
María Cristina Falls
Maria Cristina Falls is a waterfall of the Agus River on the island of Mindanao. It is sometimes called the "twin falls" as the flow is separated by a rock at the brink of the waterfall. It is a landmark of Iligan City, nicknamed the City of Majestic Waterfalls, because of the presence of more...

 and the other over the Linamon Falls. A hydroelectric plant installed on the Lanao Lake and Agus River system generates 70% of the electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

 used by the people of Mindanao.

The lake is a home of myths and legends of the Maranao tribe. The name Maranao 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 watershed occupies an area of 153,008 hectares and is home to a rich variety of flora and fauna, including 18 cyprinid species that are endemic to the lake.

As early as the 1980s the scientific community has warned that these endemic cyprinid
The family Cyprinidae, from the Ancient Greek kyprînos , consists of the carps, the true minnows, and their relatives . Commonly called the carp family or the minnow family, its members are also known as cyprinids...

 species may be in danger of extinction due to the long term effects of the hydroelectric plants on lake levels and introduction of invasive alien species. Today, water inflow and outflow have declined, lake water level has decreased, and lakebed exposure has been observed. The accidental introduction of white goby (Glossogobius
Glossogobius is a ray-finned fish genus in the subfamily Gobiinae of the goby family . The Tank Goby is the largest member of the subfamily, growing to about 50 cm long.Species include:* Glossogobius ankaranensis...

) in Lake Lanao has also caused the decline of endemic cyprinids (Guerrero, 2002), with only about 5 of 18 species still remaining in the lake

A recent study by the Mindanao State University (MSU) in 2006 discovered massive algal contamination due mainly to soil erosion from indiscriminate logging in the watershed and extensive land use and farming in the surrounding areas (Gallardo, 2006). Other factors that contribute to the deterioration of the lake are the environmental impacts of the dams, hydrological alterations, diminishing waterflow and pollution. If this continues, food security and the livelihood of communities who are dependent on the lake may be seriously affected.

A Lake Lanao Watershed Protection and Development Council (LLWPDC) was created in 1992 responsible for the development of the Lake Lanao Integrated Development Plan (IDP) in 2003. However, the perennial changes in leadership in the Council have made it difficult to implement its mandate. The IDP aimed to manage the Lake Lanao - Agus River Watershed using the landscape approach by harmonizing the various frameworks and activities that have been at work for many years (LLWPDC, 2003). However, current institutional arrangements have not really arrested the degradation of the lake.

Some current initiatives are those provided by the USAID EcoGov2 Project for ridge to reef planning and capacity building of stakeholder groups in the area. The DENR-River Basin Control Office (RBCO) is also supporting the preparation and completion of the Lake Lanao Integrated River Basin Action Plan and the creation of the Agus River Basin Project Management Office. Agroforestry projects, watershed rehabilitation and institutional strengthening are ongoing but harmonization of efforts, sustained management interventions and stakeholder support are keys to saving Lake Lanao.

In culture

A Maranao
Maranao is the term used for the people of Lanao, a predominantly Muslim region in the Philippines island of Mindanao. They are famous for their artwork, sophisticated weaving, wood and metal craft, and their epic literature...

 myth describes the formation of the lake. It is said that a group of angels under the command of Gabriel
In Abrahamic religions, Gabriel is an Archangel who typically serves as a messenger to humans from God.He first appears in the Book of Daniel, delivering explanations of Daniel's visions. In the Gospel of Luke Gabriel foretells the births of both John the Baptist and of Jesus...

removed the vast population of Mantapoli to prevent the world from tipping over. The hole that was left was filled with water and threatened to drown the rest of the world. In response, the angels enlisted the help of the Four Winds to gouge out an outlet. The hole became Lake Lanao and the outlet became the Agus river.

External links

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