Development of the Mekong River is still minimal but large amounts of water that flow into it are being siphoned off by large dams, small dams, canals and irrigation projects along it tributaries. The Mekong and its tributaries have the hydroelectric potential of all the oil in Indonesia. A large amounts of development has already by done. More than 50 dams built by the Asian Development Bank have built on the Mekong in recent decades. There are plans for many more.

There are 15 dams on the Mun River and other tributaries of the Mekong River in Thailand. In 2000, the World Commission on Dams reported a significant decline in fish caught after the Pak Mun dam was built in Thailand. As of 2005 there were seven dams on tributaries of the Mekong River in Laos and seven more planned.

Eleven dams are proposed for the Lower Mekong Mainstream. Environmentalists predict the dam “would irreversibly alter” the Mekong River’s ecology, affecting water levels and fish migration in the entire basin. An additional 77 dams are planned for the river by 2030.

Eleanor J. Sterling and Merry D. Camhi wrote in Natural History magazine, “Dams are a dramatic example of a human activity that degrades freshwater ecosystems. Built to control flooding, store water, and generate electricity, dams have numerous ecologically disastrous side effects. They impede the movement and migration of aquatic species; some kill animals in turbines; and they change the timing and amount of flow downriver, which interferes with the reproductive cycles of fishes, frogs, and water birds that depend on seasonal flooding. [Source: Eleanor J. Sterling and Merry D. Camhi, Natural History magazine, December 2007]

“About a dozen hydroelectric dams in the Mekong River Basin provide the bulk of the region’s energy—and another hundred or so are in the planning stages. To date, China has built two dams across the upper mainstream, but there are none across the lower mainstream—in fact, the Mekong is one of the world’s few major rivers with so few mainstream dams. That may soon change: local governments view the free-flowing Mekong as an underutilized economic resource. Worldwide, an average of two large dams have gone up each day for the past fifty years, and today there are more than 45,000 dams taller than forty-five feet. Fortunately, increased awareness of the environmental problems they cause has contributed to a slowdown of large-dam construction in the United States and Europe. In the Mekong River Basin and elsewhere, however, big dams continue to rise.

Overall there are relatively few dams in Southeast Asia. Proponents of dams point out that reservoirs help broaden the availability of water throughout the year, which is especially useful in providing water for crops during the dry season.

Chinese Dams on the Upper Mekong

There are plans to build 100 dams in Sichuan and Yunnan in the Three Parallel Rivers area, where three great rivers—the Yangtze, Mekong, and the Salween — flow parallel to one another within a 55 mile band, divided by high mountain ridges. The plan calls for more than a dozen dams larger than the Grand Coulee dam and one that will be the tallest in the world. Even though the dams are in remote mountainous areas they are set to displace 1 million people.

China is currently involved in building large dams on the upper Mekong to provide electricity, control floods and provide water for irrigation. Some have been built. Some are being built. More than a dozen are in the planning stages. The $4 billion Xiaowan Dam is currently being built. When it is finished it will be the world’s tallest dam, over 300 meters (100 stories) high and create a reservoir 169 kilometers long. Only the Three Gorges dam will be larger.

China is planning eight Mekong dams totaling over 16,000 MW, of which three have been across the upper reaches of the river. Four are under construction, potentially impacting riverside communities in Myanmar, Thailand, Laos, Cambodia and Vietnam.

Dams that have already been built include the $600 million, 30-story-high Dachaoshan Dam in Dachaoshan Gorge, which created a 88-kilometer-long reservoir that filled up in just five days; the 35-story-high Manwan Dam, 100 kilometers south of Dali in Yunnan, with 40 foot tunnels through the mountains and a 1500 megawatt electricity generating capacity; and the Jinghong Dam.

Chinese dams on the Mekong River from north to south (year completed or targeted for completion, people displaced: 1) Gonguaoqiao (2010, 4,600); 2) Xiaowan (2013, 32,700); 3) manwan (1996, 7,600); 4) Dachaoshan (2003, 6,000); 5) Nuozhadu (2017, 24,000); 6) Jinghong (2010, 2,300); 7) Ganlanba (unknown, 50); 8) Mengsong (unknown, 230). [Source: New York Times]

In the Three Parallel Rivers area there are plans for major four dams along the Jinshajiang River, which would generate twice the power of the Three Gorges dam. The muddy Jinshajiang fills the Yangtze with half its silt. There are plans to build 13 dams on the Nu River, which flows into Thailand and Burma. The project would produce the largest cascade dam and generate more electricity than the Three Gorges Dam. Another proposed dam on the Yangtze will submerge Leaping Tiger Gorge.

Environmentalist oppose these projects because of the ecological impact they will have. Thailand and Burma oppose them too because they have their own plans to build dams on the river. The Nu River project is slated to be built through an area that has been declared a World Heritage Site UNESCO and biodiversity hot spot and has been described as “maybe the most biologically diverse temperate ecosystem in the world” because of the variety of unique flora and fauna found there. The Nu is one of only two free flowing rivers left in China.

Plans for the dams were suspended in 2004 but revived in 2005. The projects are widely seen as ground zero for conflict between development-minded officials and environment-minded ones. Surprisingly much of the discussion revolves around following the law. A Chinese government environmental review released in 2006 recommended that dam projects be reviewed and an effort made to limit their damage and decrease the number of people relocated. See China

Mekong Dam in Thailand

Its not just China that is building dams. A World Bank report was very critical of the Pak Moon dam Thailand, which was build near the Noon River; confluence with the Mekong and blocked important fish migration routes. Of the 265 species found on the Noon River before the dam was built only 96 remain. And fish catches dropped 80 percent. The $260 million Theun-Hinboun dam in the mountains of the central highlands of Laos supplies two thirds of that country’s electricity but has turned a once vibrant river into a stagnant lake and dramatically cut fish catches.

Supporters of the dam say the dams will help not hurt the people and wild life that use the river. They say the dams will increase the flow of water in dry season and reduce it I the wet season, reducing the chance of flooding and make ore water available for irrigation. Experts have also pointed out that Lower Mekong gets more water from the highlands of Laos and Vietnam than it does from China, where the dams are located.

One study found that local dams used to divert water for irrigation pose a much greater threat than the large dams. There are 20,000 local dams on the river, most them in Thailand, and they have been linked to fluctuating river levels. Others who studied the river have also said that massive numbers of people who live on the river har, the river through land degradations and water pollution, logging, erosion. . There also worried about sedimentation and salinization in the reservoir. The slay cold contaminate rice fields. sedimentation could make the dams unusable after a few decades.

Dams in Laos on Mekong Tributaries

Laos has over 60,000 cubic meters or renewable water resources, and with its small population more hydroelectric potential per capita than any nation in Asia. Most Laotian dams are on tributaries of the Mekong River. Half the Mekong River’s hydroelectric potential lies within Laos. Much of the electricity produced by Laotian dams is exported to Thailand on power lines over the Mekong River and is a major source income for the Laos government. Three quarters of the $5 billion pledged between 1988 and 1996 by foreign investors to Laos went to hydroelectric projects to supply Thailand with energy.

Nam Ngum Dam is a large dam built outside Vientiane built with the help of Japan, West Germany, India, Switzerland, OPEC and the World Bank. It has five generators and produces 150 megawatts of electricity. When it began operation in the 1980s, Laos only needed 30 megawatts, or 20 percent of the power generated by the dam , to run its dozen or so factories. The remaining 80 percent of the power was exported to Thailand. At the time, Thais paid $30 million for the power which was half of Laos's hard currency income. [Source: Peter White, National Geographic, June 1987]

The $260 million Theun-Hiboun dam in the mountains of central Laos is the largest hydro-electric project completed thus far in Laos. Finished in 1998, it is located just upriver from where the Theun River joins the Kading River and accounts for two thirds of Laos’s power exports. The dam however has disputed fish migration patterns and fishermen complain they catch much fewer fish now than before the dam was built.

The Laotian government has made plans to build a couple dozen dams on tributaries of the Mekong River and export the electricity to Thailand and Vietnam as a way to make money. Laos hopes money from the dams will improve the economy, help lift the country out of poverty and reduce its reliance on foreign aid. One Laotian official told AP, “We need this to eradicate poverty, Thus is the only way out.” The Asian financial crisis lowered projections on the amount of electricity that Thailand and Vietnam would need in the future. When Thailand and Vietnam said they didn’t need the electricity for a while the projects were put on hold.

The Nam Mang 3 Hydroelectric Project is a $200 million dam project being built by Chinese firms with Chinese migrant labor and loans from the Chinese government. The Pa Mong dam is a $2.6 billion project that if built would produce a reservoir that would displace more than 75,000 people.

Consequences of Dams on the Mekong River

The dams have displaced thousands of people, many of them ethnic minorities, and disrupted normal water patterns and fishing migration routes and reduced the flow of soil-enriching sediment. The Cambodian government has expressed its concern that development projects on the Mekong River could caused the Tonle Sap lake to dry up. The Tonle Sap is Southeast Asia’s largest lake and an important source of fish for Cambodians.

The Mekong fell to record low in the dry season of 2004. River boats were stranded. In Cambodia the fish catch fell 50 percent after it declined 15 percent the previous year. Some blamed the problem on dam construction and the release of water to allow Chinese ships to navigate the river. Drought, dams and overfishing also played a role.

Eleanor J. Sterling and Merry D. Camhi wrote in Natural History magazine, “Radical fluctuations are natural to the Mekong, and whole communities—human and wild—are adapted to its periodic floods and droughts. The river swells when rainfall rushes down its tributaries and shrinks again in drier weather. But the rise and fall of the Mekong is increasingly dictated by energy use in China and Thailand. Upriver hydroelectric dams dampen the fluctuations and change the timing of floods and dry spells, affecting water-dependent wildlife hundreds of miles away. The extent of those changes is likely to grow as more dams, scheduled for construction, make their mark on the river. [Source: Eleanor J. Sterling and Merry D. Camhi, Natural History magazine, December 2007]

Flow patterns altered by dams and other projects could prevent those species from reproducing. In addition to building dams, countries along the Mekong are destroying or modifying rapids and other natural features to improve navigation—changes that will disturb critical fish habitats and alter downstream water flow.

A study in Global Environmental Change found that if the 11 currently planned hydroelectric projects are built on the Mekong River, fish populations could fall by 16 percent. According to the paper, the "results suggest that basic food security is potentially at a high risk of disruption." [Source: Jeremy Hance, mongabay.com, November 07, 2012]

Consequences of Dams on Mekong River Fishermen

Reporting from Chiang Khong, Thailand, Jane Perlez wrote in the New York Times, For countless generations, fishermen along the Mekong River have passed their lore and way of life from father to son: the rhythms of the water, the habits of the many kinds of fish, the best nets and traps to use to survive and prosper. But Sri Sumwantha, 70, one of the old men of Asia's majestic river, has left his delicate pirogue tied up at the riverbank for longer stretches than usual. Through green bamboo stands, he has watched the caramel-colored current slow and surge unpredictably and his catch diminish. Now, he worries how much longer his family can live off the river. [Source: Jane Perlez, New York Times, March 19, 2005]

The fish species found in this stretch of the Mekong in northern Thailand dwindled from 100 to only 88 last year, said Sayan Khamnueng, a researcher with the Southeast Asia River Network, an environmental group. Water levels and temperatures have fluctuated widely, threatening the river environment and disrupting the livelihoods of the fishermen and others who depend on the $2 billion annual catch of migratory fish.

For the fishermen, their revered river, once nearly untouched and steady in its moods, has turned into a fickle sea. "In the past the river was up and down like nature - every three or four days up and down," said Tan Inkew, 72, a fisherman who lives in Meung Kan village. "Now the river is like the sea - up and down, up and down very quickly."

Protests by Mr. Tan and other fishermen helped persuade the Thai government to stop China from blasting the rapids in Thai waters near his home, between the port of Chiang Saen and Chiang Khong. "We protested outside the Chinese Embassy in Bangkok," Mr. Tan recalled. "We told them to stop blasting - and if they don't stop, we'll fight them." Still, he worries about the impact of China's dams as well. His recalled how his son was recently out on the water for nine hours but "did not catch one thing." While Mr. Tan and his neighbors may have scored a small victory, clearly China cannot be kept at bay for long.

Mr. Sayan, of the Southeast Asian River Network, said fishermen had stopped selling their fish at the main market in Chiang Rai. "They don't have enough," he said. In extreme cases, the fishermen have given up and become laborers, unloading the trading vessels from China that dock at Chiang Saen, laden with fruits and vegetables, electronics and cheap garments. "As laborers they become impoverished and are miserable," said Chainarong Srettachau, the director of the river network. Some fishermen have begun supplementing their incomes with crops. But crops are being hurt, too. China's upstream dams are also holding back as much as 50 percent of the fertile silt that is essential to the soil and that normally flows down river, according to conservationists.

Erosion is also worsening. At Pak Ing, a small village near Chiang Khong, fishermen pointed to a 12-foot-high wall of exposed soil, a muddy mini-cliff where the water, flowing faster because of blasting of the rapids, has cut into once gently sloping riverbanks. The next step will be to erect concrete banks to hold back the land. Farther downstream, the effects may be even more severe. In Cambodia, an intricate ecology and age-old economy depend on the ebb and flow of the great lake fed by the Mekong, Tonle Sap, which can swell fourfold during the rainy season. The rhythm of life is built around the seasonal tides and the bounty that the waters provide.

The fish catch dropped by almost 50 percent last year, according to the Mekong River Commission. In many areas, the low catches were caused by the sudden fluctuations that occurred when dams in China released water to allow easier passage for trading vessels, said Milton Osborne, an Australian historian and an expert on the Mekong. The water from the dams is also much colder than the water downstream, affecting the fish, which are extremely sensitive to changes in temperature, Mr. Osborne wrote last year in a paper titled "River at Risk" for the Lowy Institute, a public policy group in Sydney. Large species in particular had fallen off, he said. The outlook for the river and its vast ecosystem was not promising, he added.

"Because of the enormous imbalance of power between China and the downstream countries," he said, "it is highly unlikely that there will be a halt to China's projected dam building program on the Mekong." But Mr. Chainarong of the river network was less pessimistic. "Two or three years ago, people said we would never be able to stop China blasting the Mekong inside Thailand," he said. "But we did." "One good thing," he noted, "is that China doesn't want to have conflict downstream. That's the challenge. The situation is up to China: does it want to go friendly or hostile?"

Mekong Dam Spree Could Create Regional Food Crisis

Jeremy Hance of mongabay.com wrote: “Fish are a hugely important protein source for many people around the world. This is no more evident than along the lower Mekong River delta where an estimated 48 million people depend directly on the river for food and livelihoods. But now a new study in Global Environmental Change cautions that 11 planned hydroelectric dams in the region could cut vital fish populations by 16 percent while putting more strain on water and land resources. [Source: Jeremy Hance, mongabay.com , August 27, 2012, Orr, S., et al. Dams on the Mekong River: Lost fish protein and the implications for land and water resources. Global Environmental Change. 2012 ^^^]

"The Mekong countries are striving for economic growth, and they see hydropower as a driver of that growth. But they must first fully understand and take into account the true economic and social value of a free-flowing Mekong," says co-author Stuart Orr, freshwater manager with the World Wide Fund for Nature (WWF). ^^^

Economically, the 11 planned dams could cost the Mekong countries—Thailand, Vietnam, Laos, and Cambodia—nearly half a billion US dollars annually in lost fish catch. Replacing the lost fish protein with protein from livestock—such as cattle, pigs and poultry—would also require an additional 4,863 square kilometers (3,021 square miles) of land, according to the study. Water requirements would also need to boosted to irrigate crops for the livestock. For example, the 11 dams would require Cambodia to consume 29-64 percent more water for its agriculture, and Laos would need 12-24 percent more. ^^^

Hydro energy plans for the Mekong don't stop with the Xayaburi or the other planned ten dams. An additional 77 dams are planned for the river by 2030. The full impacts of all 88 projects, according to the study, would cut fish by nearly 40 percent. It could increase land needed for livestock to 24,188 square kilometers (15,029 miles), or an area the size of Vermont, to make up the protein lost by the dwindling fish supply. The full hydroelectric plans would force Cambodia to increase water supply by 42-150 percent and Laos by 18-56 percent in order to feed new livestock. The researchers write that their "results suggest that basic food security is potentially at a high risk of disruption." ^^^

Impact of Dams on Mekong River Fish Species

Harmony Patricio told mongabay.com: “The strategic environmental assessment for mainstem dams that was commissioned by the Mekong River Commission suggests that mainstem dams like the Xayaburi could block the migrations of some rare or economically valuable species. It could alter the species composition to favor fish species better adapted to a reservoir environment. The fish that can withstand lower oxygen levels or higher temperatures and can survive in a reservoir will do better than fish that need the free-flowing river environment or that are highly migratory. [Source: Jeremy Hance, mongabay.com, April 23, 2013 |~|]

“Also, no one knows for sure where the giant catfish spawns, but based on local ecological knowledge, people believe they spawn upstream of the Xayaburi Dam location. It would be a problem if the giant catfish can't make it past the dam, but they've already stopped showing up to these traditional spawning grounds—they've already been affected by changes to the river. Maybe they will be able to spawn somewhere downstream of the dam. The dam could also trap sediment that is very important for maintaining downstream habitat in the Mekong Delta in Vietnam. Ultimately, the Xayaburi is likely to have some impacts on fish, but there are plans for many other dams as well. |~|

“The impact is really going to depend on the development scenario: whether all of those dams are built in the locations where they're planned now, and how they're built. There are many alternative scenarios that could reduce impacts on fish and still generate a substantial amount of electricity. Overall, the cumulative effect will probably be a reduction in the number of migratory species and a shift in the species composition to favor species that do well in reservoirs. Right now, we know more than a third (38 percent) of the total Mekong fish harvest consists of migratory species. If the biomass of the reservoir species doesn't scale up to replace the migratory species, we could see a decline in total harvest or productivity. |~|

“The sediment trapping could reduce the productivity of the marine fishery off the coast of the delta and the delta itself could suffer land loss from erosion, which might affect rice production. People also talk about how dams will change the river's flow regime. Right now the Mekong has a very dynamic regime, extremely high flows in the rainy season, and very low flows in the dry season. This difference in flows is one reason why people think the river so productive. It causes the flooding of the Tonle Sap, creates floodplain habitat, and the potential for riverside gardens. A lot reservoirs and dams will reduce the variability of the flow regime. The dry season flows will be higher and the wet season flows might be a bit lower. There are a lot of questions about how this will affect the system. |~|

Mitigating the Impact of the Mekong River Dams on Fish

Jeremy Hance of mongabay.com wrote: “There are ways to mitigate the damage of the dams, such as building massive bypass channels around the dam. In addition, officials could look at other power-generation technologies that wouldn't involve damming the river.[Source: Jeremy Hance, mongabay.com, April 23, 2013 |~|]

Patricio told Mongabay: “There are definitely ways to design dams to minimize their impacts on fish. You might have to sacrifice a bit of the power generation capacity, but maybe it will be worth the gain you get from maintaining fish populations. One strategy they're looking at now for dams on the Mekong mainstem is building big bypass channels, basically creating a new river channel that goes around the dam. It's obviously not as big and wide as the natural river, but it provides fish with a more natural riverine environment, rather than trying to build an elaborate fish ladder or elevator system over the dam itself. I think that approach is probably the most "fish-friendly." |~|

“It depends on what kind of fish you're talking about! Fish passage is a challenge because there are more than 100 highly migratory fish species in the Mekong, ranging in size from less than 10 centimeters up to 300 centimeters. Obviously, their swimming and jumping capabilities are going to be really different. In addition, huge volumes of fish move at the same time in the Mekong, and it's hard to engineer something that can accommodate such a huge quantity of fish to pass a dam. |~|

“There are also ways of generating hydropower without making big dams. Some cool research is looking into building small turbines that are bolted to the riverbed, like free-standing barrels. Screens protect the fish from the turbines, and there is lots of space for fish to pass around. People are also designing mesh grids with tiny turbines, maybe the size of a cube of ice. You put that on the substrate, and the little turbines combine to produce a fair amount of electricity, although they can't generate the amount of electricity that the large dams can. I would say the most fish-friendly approach would be to use these small-scale, alternative technologies that maybe can't produce as much power per facility, but you could spread lots of them out in places that aren't essential for spawning or feeding. |~|

Image Sources: Wikimedia Commons

Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, 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, NBC News, Fox News and various books and other publications.

Last updated April 2014

This site contains copyrighted material the use of which has not always been authorized by the copyright owner. Such material is made available in an effort to advance understanding of country or topic discussed in the article. This constitutes 'fair use' of any such copyrighted material as provided for in section 107 of the US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this site is distributed without profit. If you wish to use copyrighted material from this site for purposes of your own that go beyond 'fair use', you must obtain permission from the copyright owner. If you are the copyright owner and would like this content removed from factsanddetails.com, please contact me.