TONLE SAP (north of Phnom Penh) is the largest freshwater lake in Southeast Asia at the end of the wet season but is only a large lake in the dry season when it shrinks to a fraction of its wet season size Stretching almost all the way from Phnom Penh to Angkor Wat, it provides water for half of Cambodia's crops, and yields fish that supplies Cambodia’s population with half its protein It is also one of the country’s most important transportation links.

Tonle Sap lake—which is connected to the Mekong by a short river also called Tonle Sap—alternately feeds, and feeds from, the Mekong River. During raining season from June to October, the lake is fills with water flowing from the northward-flowing Mekong River and becomes 14 meters deep in some places and expands it surface area to around 10,000 square kilometers. In dry season from November to May its shrinks in size to 3,000 square kilometers, with an average depth of only two meters as water flows out from the lake when the Mekong changes course and flows south.

In the Angkor era, Tonle Sap was to the Khmers what the Nile was to the Egyptians: a source of abundance that freed labor to produce grand monuments and create a high level of culture. In the dry season, the Khmers captured the lake’s retreating waters and used them to irrigate crops, and thus were able to grow two or three crops a year. In the wet season, they used the waterway’s advancing waters to carry quarried stones to build Angkor’s great temples. In the Khmer language "Sap" means “lake.”

Flooding Cycle of Tonle Sap

During the rainy season, from June to November the Mekong River reverses its flow into the lake causing it to expand to more than six or seven times its normal size of approximately 2,600 square kilometers. It becomes a vast inland sea. In June, with monsoon rains swelling the Mekong, excess water is pushed into the Tonle Sap that then drains back upstream into the lake, flooding the surrounding low plains. By monsoon's end, in November, the pressure is relieved and the Tonle Sap reverses course and returns to the direction of flow expected of it. However, the waters take several more months before they begin to recede, and it is not until February that Tonle Sap Lake begins its return to normal size.

Tonle Sap is like a big bowl that fills with water when the Tonle River flows into it and empties when the Tonle River changes direction, as it does every year, and flows out of it. The Tonle River is part of the Mekong River system, which swells with monsoon rains and snow melt from the Himalayas in the wet season. By September the of flow of the Mekong River is ten times what it is in the dry season, with much of the excess water flowing into the Tonle River, which in turn fills up Tonle Sap.

After that the monsoon rains stop the amount of water flowing down the Mekong is greatly reduced. At a critical point the water pressure from Tonle Sap exceeds the pressure from the Mekong River and the Tonle River changes direction and begins flowing towards the Mekong River, draining much of the water out of Tonle Sap. By the end of dry season, Tonle Sap has lost most of its water and resembles a swamp crisscrossed by channels.

The depth of Tonle Sap peaks at around 45 feet in September, when area of the lake covers as much a 4,500 square miles (11,700 square kilometers). In the dry season the depth of the lake can drop to as low as three feet. Depending on the rainfall and snow melt amounts Tonle Sap can be as much as 15 times bigger in the wet season than it is in the dry season. In the wet season vast amounts of farmland and entire forests are submerged and stilted houses and floating villages lie in the middle of the lake. When the water retreats it leaves behind layers of fertile silt and maroons the stilted houses and floating villages on land.

Fishing and Agriculture and Tonle Sap

There are 300 species of fish living in Tonle Sap. These include black fish that breed and spawn when the lake is full and stick round when the lake empties, living in ponds, and sometimes in hollows of unique underwater plants. Migratory whitefish, mostly catfish, enter the lake during the wet season and migrate to the sea or the upper reaches of the Mekong River to spawn. They are caught in great numbers as they enter and leave the lake.

The months of flooding encourages the growth of huge fish stocks and other aquatic life, that become extremely easy to catch once the waters begin to reside. Fishing families string nets and bamboo traps across the lake's mouth and the numerous fish can almost be plucked from the water. The Tonle Sap Lake's level drops so fast that it catches out many of its inhabitants, and its not unlikely to see fisherman picking their catch from the trees.

When the Tonle Sap fills with water it also fills with quick-spawning and -growing fish. During the height of the dry season Tonle Sap becomes one of the easiest lakes in the world to catch fish in, as all the fish that grew and spawned in the wet season get squeezed into shallow pools from the drained lake. The fish are then trapped in bamboo weirs and nets that are strung across channels.

By some estimates fish caught from Tonle Sap provide Cambodians with 60 percent of their protein. Most of the fish caught are small five- to eight-millimeter-long moonlight gourmai which are capable of leaping as high as six feet into the air and are chopped and mashed into fermented fish paste. During the fishing season, Tonle Sap is filled with nets and small boats. One a good day a fisherman may can catch 500 pounds of small fish. Prawns are also drawn from the lake and water is used in crocodile farms.

The mud banks created by the flooding of the Tonle Sap are extremely fertile, and local rice farmers have developed a deepwater rice that is unique to this area. Water from the Tonle Sap also provides rice farmers with water for irrigation. The fresh layers of silt deposited after each flood serves as an ideal fertilizer. The abundance provided by Tonle Sap, some historians have theorized, is one reason why the Angkor civilization was so great and was able to sustain itself for so long.

Tonle Sap Environmental Concerns

The flooded forest surrounding the edge of Tonle Sap is an important spawning and breeding area for fish. The lake is a vital ecosystem for over 300 species of freshwater fish as well as snakes, turtles and amphibians and perhaps some crocodiles and otters. More than 100 varieties of water birds, including storks and pelicans, thrive in the lake. Each year, millions of fish come to spawn in the seasonally flooded forest surrounding the lake, attracting myriad waterbirds. Villages along the shores live with the rhythm of the season and the floods.

There are problems with fertilizer run off contaminating water supplies. Deforestation produces erosion that silts up the lake. Already there have been notable declines in some species of fish that has probably been caused by overfishing and conversion of traditional spawning grounds to agricultural areas. . There are also concerns that new dams on the Mekong River—notably in China and Laos—that could disrupt the entire Tonle Sap cycle, with catastrophic consequences.

Thus far the Cambodian government has done little to protect the Tonle Sap. Environmentalist say regulations need to be put into effect to prevent overfishing and illegal logging but realize that if more laws and regulation are put in place enforcement is spotty and corruption widespread. Often times politicians and military officers and police have a hand in the illegal fishing operations that sometimes involve connecting metal poles to car batteries to electrocute fish.

Village Life on the Tonle Sap

Five provinces encircle Tonle Sap and more than three million people live in around the lake. Of these about 90 percent of them earn a living from fishing or agriculture. Many people live in distinctive floating villages in stilted houses, and use fish traps to catch fish in a life deeply intertwined with the lake, the fish, the wildlife and the cycles of rising and falling waters.

Reporting from Chong Kneas, Ker Munthit of Associated Press wrote: “Every year, Tonle Sap lake expands into a small sea with the onset of the monsoon season, then shrinks when the rains end. It makes nomads of the people of Chong Kneas, a sprawling community of houseboats and thatched huts at the lake's northern end. When the rains begin, drivers struggle to steady their trucks on muddy trails leading to the villages as they haul away residents and their ramshackle shelters and meager belongings on an unwanted but necessary seasonal journey. [Source: Ker Munthit, Associated Press , July 23, 2006]

Although two of its villages sit on dry land, the other five are floating communities of houseboats on which people live and run businesses. Classrooms sit on floating platforms, and children row themselves to school on small sampans, the same means by which vendors go “door-to-door" to sell vegetables or noodle soup.

But it is the villagers' lives that are really adrift at Chong Kneas. Its 5,800 people, like most of those in rural Cambodia, live at subsistence level, and it is a heavy burden to pay to move every year when the lake's edge pushes north as much as 4.5 miles, then moves back as the waters recede. About 70 percent of the villagers earn only the equivalent of 70 cents to $1.90 a day, said Em Mann, the Chong Kneas community leader. Each move costs a family up to $14.40 to transport their shelter and belongings, leaving many in debt year-round to moneylenders. “Every year, they have to move and buy clothes and kitchenware to replace that blown away by the storms of the monsoon," he said. “We are fed up with this way of life but have no alternative."

“He said life would have changed for the better had Cambodia's government not scrapped a plan conceived by the Asian Development Bank to move Chong Kneas to a permanent settlement on high ground, with a clean water supply, sanitation, roads, schools, and medical clinics. Neou Bonheur, the Environment Ministry's coordinator of the Tonle Sap environmental management project, said the government couldn't afford the move — which would cost millions of dollars — or the land acquisition and employment issues it would entail. “All these issues are quite complicated" for the government to pursue, he said.Em Mann, the community leader, complained that some tour companies also argued against moving Chong Kneas because tourists like to visit the floating community. “They must be really thinking we are animals in a zoo here," he said.

The lake long provided enough bounty to sustain those living along its shores. But many villagers say life has become harder because of dwindling fish stocks, tighter government regulation of fishing, and environmental degradation. Pollution is threatening the villagers' health and lifestyle. With no public sewage system, they use the lake — their traditional water supply — as a toilet and garbage dump as well.

For safe drinking water, villagers must pay nearly 30 cents for 8 gallons of well water brought in by vendors from other villages miles away on high ground, said Ly Saloeurn, a 51-year-old fisherman who earns roughly $1.20 a day from fishing to support his family of eight. Now that the government has spurned the plan to give them a permanent home, most villagers are resigned to living adrift. Sia Yem Son, 70, said he didn't have the words to adequately describe the hardships. But one thing is certain, he said. “It will never end before I die."

Traveling Between Siem Reap and Phnom Penh on the Tonle Sap

Traveling through the Tonle Sap is an interesting way to travel between Siam Reap and Pnomh Penh. While the slow boats take a couple of days to make the journey, it is easy to find fast boats which take only half a day.

Tonle Sap lake is located about 15 kilometers south of Siem Reap town; you can make your journey from Siem Reap to Phnom Penh by express boat crossing the lake and dock at the village of Chong Khneas. Its takes only six hours, but this trip we may recommend you during Monsoon season. In dry season the boat sometimes stuck in mud because the water is low. There are several ways to see the culture and wildlife of the lake area depending on the amount of time you have and your interest. It is preferable to arm oneself with sunscreen and sit on the top of the boat (which will be overcrowded), to get a better view, more fresh air, and improve your chances of survival should the boat capsize.

Boats from Siem Reap (about 15 kilometers south of main part of town) depart daily at 7:00am. The journey take about 5 or 6 hours, longer depending on the water level. The usual cost is $25.00 per ticket. You may find cheaper prices if buy at a travel agent. [Source: Tourism of Cambodia]

There are eight boat companies currently providing services between Phnom Penh and Siem Reap and one boat company operating between Phnom Penh to Chau Doc. Since there is limited numbers of passenger travel, boat companies take turn doing the trips, one company a day. You should arrive a half before the 7:00 departure time. Ticket should be bought at least one-day in advance to be assured of a seat. All boats are equipped with air-conditioners, toilets and video TV. Enjoy your ride and the scenery from the rooftop of the cabin.

Boat Companies: 1) Khemara Express Boat: High Way No 5A In Front of Soksan Club: Tel: 023 430 777; 2) Soon Ly Boat: Tel: 023 725 797/ 012 728 055; 3) Channa Boat: Tel: 023 725 788; 4) Royal Express Boat: Sangkat Sras Chork Khan Daun Penh, Road No 5. Tel: 023 725 538; 5) Angkor Express Boat: Sisowath Squay International Phnom Penh Port. Tel: 023 426 892; 6) Rambo Express Boat: Tel: 012 846 818/ 011 876 678; 7) Mittapheap Boat (Friendship): Tel: 023 880 857/011 876 555; 8) Hang Chau Boat: Sisowath Squay International Phnom Penh Port. Tel: 012 883 542.

Towns and Villages on the Tonle Sap

Kampong Chhnang (on the Tonlé Sap) is home to about 50,000 people and a large fishing industry. The city is central Cambodia's transportation hub and is linked by rail, road, and river ferry with Phnom Penh. The residents of Kampong Chhnang and the surrounding region are noted for the creation of beautiful Cambodian pottery.

Chong Khneas (15 kilometers from Siem Reap) is the name the village at the edge of Tonle Sap that is the jumping off point for boat travel between the Angkor Wat area and Phnom Penh. The village is located in the southern part of Siem Reap town. It takes about 30 minutes by vehicles to reach the boat docks from Siem Reap proper. There are always boats waiting to take visitors on local trips arpund the lake and floating villages. The boat trip through the floating village takes approximately two hours. You will explore the different of Khmer, Muslim and Vietnamese floating households and the floating markets, fisheries, clinics, schools, basketball courts and pigstys. You will also likely see boatloads of other tourists.

Chong Khneas used be more charming and interesting. Now that village is controlled by a private firm that has jacked up prices and made the area more commercial. The boat trip usually includes two stops: one at a touristy floating 'fish and bird exhibition' with a souvenir and snack shop, and the other at the very highly recommended Gecko Environment Centre, which offers displays and information introducing the ecology and biodiversity of the lake area.

Kompong Khleang (55 kilometers east of Siem Reap town) is located on the northern lake-edge. It is more remote and less touristy than Kampong Pluk. Visitors to Kampong Khleang during the dry season are amazed by the forest of stilted houses rising up to 10 meters in the air. In the wet season the waters rise up to one or two meters from the floors of the buildings. Like Kompong Pluk, Kompong Khleang is a permanent community within the flood plain of the lake, with an economy based in fishing and surrounded by flooded forest. But Kompong Khleang is significantly larger with nearly 10 times the population of Kompong Pluk, making it the largest community on the Lake.

Sights on the Tonle Sap

Prek Toal (two hours by boat from Chong Kneas) is one of the most attractive floating fishing villages on the Tonle Sap lake, with a school, hospital, restaurants, shop and even a pagoda. Just behind the Prek Toal village are flooded forests with bird sanctuaries. Every year, between December and March, thousands of birds come to fish and to breed here.

Kompong Khleang can be reached in 2½ hours by charter boat from the Chong Khneas dock. Or it can reached by a combination of road-boat trips: first by 1½ hours by road to the dock in Domdek via Route 6, and then a one hour boat trip to the village. The best method depends on the time of year. During the dry season, boats cannot get all of the way to the main village. Consult with a tour operator about current conditions. Many travel agencies have very little experience in this area.

Tonle Sap View (in front of Phsar Krom, about one kilometer from Siem Reap) includes many floating houses and fishing lots, where locals raise and catch fish. The site is popular among foreign visitors who want to learn about Cambodian fishermen and those people who live on the river.

Tonle Sap from Pursat: Pursat Province offers a magnificent opportunity to see one of the larger and markedly less touristy floating villages without a significant investment in time or money. In fact, there are a number of floating villages in the province only accessible from the lake, Peach Kantil, Kbal Taol, and Prek Kr, but you can only see Kompong Luong for the cost of the day-rate for a moto ($6-8) and the cost for a boat ride once you get there. See Tonle Sap

Bird and Wildlife Spots on the Tonle Sap

Bird Sanctuary at Prek Toal (two hours by boat from Chong Kneas boat dock) is the core area of the Tonle Sap Biosphere Reserve, which has been called "the single most important breeding ground in Southeast Asia for globally threatened large water birds. Visitors arrive at the the Prek Toal Environmental Research Station for a guided tour of the birds sanctuary. The Research Station has information on the area's flora and fauna. There are also basic overnight accommodations at the Research Station if you want to stay the night to take full advantage of the sunset and early morning viewing hours. The entrance fee for birds watching for two persons is 25$ each, for three persons and the cost is $20 per person. The fee includes a guided boat tour of the bird sanctuary. The entrance fee helps promote responsible tourism in Cambodia, and contributes to the conservation of the area, especially educating children and villagers about the importance of the birds and the unique flooded forest environment. Theoretically anyway, all the money goes through to local communities.

Tonle Sap Biosphere Reserve (the northwest tip of the Tonle Sap Lake) covers 31,282 hectares and plays host to species including greater and lesser adjuncts, black-headed ibis, painted stork, milky stork, spot-billed pelican, grey-headed fish eagle and many more species. Of the three Biosphere core areas on the Tonle Sap Lake, Prek Toal is the most popular with birdwatchers. The best time to explore is the dry season between December to May when flocks of migratory birds congregate at Prek Toal. While the dry season progresses and the water recedes, the number of birds increase, but unfortunately travel to some of the more important viewing areas becomes more difficult. It takes about an to reach the bird tower.

Kampong Luong Floating Village of Lake Tonle Sap

Kampong Luong Floating Village (35 kilometers east of Pursat provincial town) is a a complete village on the water populated mostly by Vietnamese fishermen. To reach it head east from Pursat town. About one-third of the way to Kampong Chhnang town is the town of Krakor. Just a few kilometers to the north are Lake Tonle Sap and the floating village of Kampong Luong. You can arrange for a small non-motorized boat to show you around.

Kampong Luong is located on the Tonle Sap in Kampong Luong commune, Krakor district. The site is a sand cape suitable for swimming during the dry season. During the rainy season, especially during the Pchumben festival, many Cambodians gather her to play Chaol Teuk Leak (a traditional Khmer game, played by throwing water on one another) on the river. The game can be dangerous, however, because it is often played while in small boats.

Situated just past the mouth of the Tonle Sap, the floating village of Kompong Luong is found 30 kilometers into the lake on its southwest shore. It' is truly a floating village, with a large population of Vietnamese fishermen. Almost totally overlooked by tourists because of its remoteness and difficult-to-reach location, the village is completely self-sufficient. A floating school, factories to make ice for fish preservation, church, pagoda, service stations, pigsty, stores, boat and television repair shops, video clubs, karaoke bar, police station... everything is on the water. Many trades are represented and everybody from children to grandparents gets around by boat through the network of canals that cross this little town.

There are four other sites that people visit: 1) Kampeng: located in Pro Ngil village, Por Ngil commune, Kravanh district, about 20 kilometers from the provincial town. 2) Phnom Dak Preah: located in Roleap village, Roleap commune, Pursat district, about 10 kilometers from the provincial town. 3) Koh Sampeou Meas: located in front of the provincial hall in the middle of Pursat Island. It covers 2 hectares. And 4) Preah Theat: located in Sre Sdok village, Sre Sdok commune, Kan Deang district, about 20 kilometers from the provincial town. These sites in Pursat province cater mostly to local people who visit them, especially on holidays or during the traditional festivals.

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Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, Lonely Planet Guides, Library of Congress, CIA World Factbook, Compton’s Encyclopedia, The Guardian, National Geographic, Smithsonian magazine, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Wall Street Journal, The Atlantic Monthly, The Economist, Global Viewpoint (Christian Science Monitor), Foreign Policy, Wikipedia, BBC, CNN, Fox News and various websites, books and other publications identified in the text.

Last updated August 2020

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