GNF - Tonle Sap Lake

Tonle Sap Lake (Great Lake) – Cambodia


2 February 2016:

Tonle Sap Lake is the Threatened Lake of the Year 2016.

Background Tonle Sap Lake

The fish biodiversity of the Tonle Sap Lake is depending on the annual flooting cycles, reaching the lake from the Mekong River via the Tonle Sap River. The Tonle Sap Lake is the largest freshwater lake in South East Asia and one of the most productive inland fisheries in the world. The lake is connected to the Mekong River through the 100 km long Tonle Sap River.


Seasons of the Tonle Sap Lake

During the rainy season from mid-May to beginning October, the water level of the Mekong River is four times higher than in the dry months. Large water quantities flow via the Tonle Sap River in the Tonle Sap Lake, the surface of which can reach up to 16,000 sq. km. Its maximum depth then is about 14 m.


In November, when the Mekong River carries less water, the flow direction of the Tonle Sap River changes. Then huge quantities of water flow back from Tonle Sap Lake to the Mekong River, and the surface of the lake shrinks to 2,500 sq. km, its maximum depth amounts to 2 - 3 m only.


Due to this unique natural phenomenum Tonle Sap Lake is very rich in freshwater fish. In the floodplains rice has been cultivated for centuries.



Lake Tonle Sap with the rivers Mekong, Tonle Sap and Bassac form a unique eco-system, home to a great variety of species: over 200 fish species live in the lake, 70 of it are of commercial relevance. 23 snake species, among them the endemic Longhead Water Snake (Enhydris longicauda) as well as 13 turtle species live in and around Tonle Sap Lake.


Negative Impacts

Overfishing, untreated industrial and domestic sewage, climate change effects, and dam building projects along the inflows threaten the natural balance of the region.

More information about Tonle Sap Lake

Detailed Data

 Fischer auf dem Tonle Sap See
 Fish proceeding at Tonle Sap Lake
 Floating village at Tonle Sap Lake
 Menschen am Tonle Sap See
 Local fishery is dependent on healthy mangrove forests.

Project measures Tonle Sap Lake

UNESCO protection status

Since 1997, the Tonle Sap Biosphere Reserve (TSBR) has been designated as a UNESCO Biosphere Reserve, completely surrounding the Tonle Sap Lake.

Mangrove restoration and sustainable fisheries

Since January 2012, the project "Mangrove Restoration in Asia" is implemented at Tonle Sap Lake. During three years, native mangrove seedlings will be grown in tree nurseries and degraded mangrove forests will be reforested with this seedlings.


In 2012, the second project targeted at the “Promotion of Sustainable Fishery and Eco-Tourism” at Tonle Sap Lake. This project reduced the pressure on the biodiversity and the natural resources.

 Mangrove nursery
 Mangrove plants in the project area


Partner Organisation Tonle Sap Lake


Fisheries Action Coalition Team (FACT)

#57z, Street 430, Sangkat Phsar Doem Thkov, Khan Chamkarmon 

Phnom Penh, CAMBODIA

Phone: (855) 023 - 992 - 044



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