Resilient rivers

Helping protect the Mekong, and rivers around the world

Each year when the monsoon season in Cambodia nears its end in October or November, stretches of the mighty Mekong River teem with colorful dragon boats slicing the water’s surface. The riverbanks are packed with onlookers who’ve traveled from all over the country to Phnom Penh to watch the spectacle of boat racing and join in the revelry that marks the Bon Om Touk water festival—the most important holiday in this Southeast Asian country. For three consecutive days, the nation of 16 million celebrates the seasonal ebb of the Mekong and the abundant fish run that ensues.

Fish provide an estimated 76% of the animal protein in Cambodian diets, and much of the supply comes from the Mekong. Accounting for 25% of the global freshwater fish catch, the river is the most productive inland fishery on the planet, worth an estimated $1.7 billion annually.

Photographed in 2014, You Veasna, a boat driver, brings tourists to see Irrawaddy dolphins in Kampi’s protected area in Cambodia.

At around 3,000 miles, the Mekong is among the longest rivers in Asia. The lower Mekong mainstem is also one of the last long stretches of tropical river in the world that is largely unaffected by human-made obstructions such as dams and levees that alter a river’s flow, hem it in, or block fish migrations.

Starting on the Tibetan Plateau, the upper Mekong flows through the rugged, sparsely populated terrain of China’s mountains and deep canyons, where it is known as the Lancang River. In the lower Mekong basin of Myanmar, Laos, Thailand, Cambodia, and Viet Nam, the river meanders through a gentler, more populous landscape before emptying into the South China Sea.

For the tens of millions of people in the Greater Mekong region, the river is not only at the center of cultural practices and food security but also important for mitigating the impacts of climate change. It’s used for transport and as a source of drinking water, provides irrigation for agriculture, and generates income. Home to 1,200 species, it is also the second-most biodiverse river in the world, after the Amazon.

Dolphin illustration Irrawaddy river dolphin
Elephant illustration Asian elephant
Vulture illustration Red-headed vulture

Perhaps nowhere is its life-sustaining power more apparent than in the nearly 120-mile stretch running from the Laotian border south to the sleepy Cambodian river town of Kratie. This free-flowing reach experiences the largest annual fish migration on Earth, as fish move from the vast Tonlé Sap Lake in western Cambodia to spawning grounds in the north. Brimming with biodiversity, the river and its basin provide habitat to the endangered Irrawaddy dolphin and the critically endangered white-shouldered ibis, giant ibis, red-headed vulture, and white-rumped vulture. Some species harbored here have all but disappeared from other parts of Southeast Asia. WWF has been tackling threats to wildlife and people in this part of Cambodia—known as the Mekong Flooded Forest—since 2002.

But today the wild stretches of the lower Mekong—and the intricate ecosystem as a whole—are under pressure. The region is changing fast, and with unprecedented social and economic development have come hydropower dams, sand mining, overfishing, pollution, and more.

The threats to wildlife and people on the Mekong are many and interrelated, says Marc Goichot, WWF’s freshwater lead for Asia Pacific. But make no mistake, he says, “the biggest threat is posed by hydropower.”

A fishing boat cuts through the Mekong River in Kratie Province at dawn.

A woman collects aquatic plants and vegetables inside the Tram Chim National Park in Viet Nam.

The energy challenge

In recent decades, the Mekong has become increasingly fragmented as countries seek to harness its potential to generate electricity. Eleven dams already constrain the mainstem in China, and Laos and Cambodia have been tapping into the power of the Mekong and its tributaries to anticipate the energy demands of the growing economies of the lower basin. Today more than 200 large dams are planned, completed, or under construction in the lower Mekong.

Mekong Flooded Forest

Deer beside river

The iconic reach of the lower Mekong known as the Mekong Flooded Forest is a rich mosaic of waterways, unusually deep pools, and forested island archipelagos. During the dry season, animals such as endangered hog deer forage in the forest. During the wet season, the forest floods, and fish take their place, feeding, breeding, and seeking refuge from predators in submerged stands of trees and shrubs. The forest is at the center of food security and survival for some 140,000 people, including Indigenous groups.

But in recent decades, it has come under pressure from unbridled development, overfishing, poaching, and other threats to its rich aquatic and terrestrial biodiversity.

WWF has been working here for almost 20 years to document the vital significance of this landscape and reduce pressure on the forest’s natural resources by helping communities to develop sustainable livelihoods. Recent initiatives include providing technical support to community fisheries and forestry groups; raising awareness, both nationally and globally, of the high biodiversity value of the area; funding river patrols in an effort to stamp out illegal activity and protect endangered species; and helping villagers develop ecotourism ventures.

WWF has also hired local people to protect the nesting sites of native birds. The project has proven successful in changing the behaviors of community members, who are now engaged in safeguarding nests rather than hunting birds or collecting eggs. In 2018, 105 villagers participated.

Also successful have been efforts to protect endangered Irrawaddy dolphins, whose survival is threatened by illegal electroshock and gillnet fishing. Day and night, rangers patrol the river, confiscating illegal gear and talking with fishers about the bounds of the law in the two wildlife sanctuaries—the Sambo and the Prasob—established here in 2018 with WWF’s help.

Today, nature enthusiasts flock from all over the world to wait patiently under bamboo umbrellas for the shy dolphins to pop up for air.

The controversial Don Sahong plant, which began operating in southern Laos in 2020, is the last lower Mekong barrier before the river becomes free flowing again as it continues into Cambodia. The Lower Sesan 2, Cambodia’s largest hydropower dam, is located on one of the longest Mekong tributaries. Approved in 2012 and operational by 2018, it displaced hundreds of Indigenous families and has already affected fisheries. A study published in Proceedings of the National Academy of Sciences of the United States of America estimated the dam would lead to a 9% drop in fish stocks across the basin.

Like its neighbors, Cambodia in recent years has struggled to meet its energy demands. Propelled by robust garment, construction, and (until the COVID-19 pandemic) tourism industries, its economy grew by 8% each year between 1998 and 2018. But though Cambodians pay four times the regional average cost for energy, almost 70% of grid users in the country face power shortages, and the nation must import nearly a quarter of its energy. For the Cambodian government, hydropower came to be seen as a cost-effective source of reliable electricity.

In 2016 Cambodian authorities announced plans to build not one, but two, massive hydropower plants—the Sambor and the Stung Treng—on the Mekong mainstem, smack-dab in the middle of the Mekong Flooded Forest.

An unprecedented threat

Not all hydropower projects are outright unsustainable; with careful planning, it is possible to choose a dam site that will result in lower environmental and social impacts. A 2019 WWF report estimated that with strategic and systematic planning, the potential loss of river connectivity from global hydropower expansion could be reduced by 90% globally—and more than 62,000 miles of river could remain connected. But the plans for the Sambor and Stung Treng power plants promised to drastically alter large stretches of the river.

If built, Sambor would become the largest dam on the Mekong and the farthest downstream. It would inundate 153,000 acres, displace some 20,000 people, and threaten food security for millions in Cambodia and Viet Nam. According to a Natural Heritage Institute (NHI) impact assessment, the dam “would create a barrier that would be devastating for the migratory fish stocks that move from the Tonlé Sap Great Lake to the spawning grounds upstream.”

As reservoirs associated with dams fragment rivers, converting entire stretches to lake-like conditions, not just the total catch of fish but the number of species dwindles. “Damming a river affects the life cycle of the fish, and while it takes some time, eventually species disappear,” says WWF’s Goichot.

Some fish that travel long distances upstream to spawn, like the Mekong giant catfish—a fish that weighs as much as a grizzly bear—have already paid the price for hydropower development. Now critically endangered, the giant catfish has experienced a population drop to some 100 individuals.

And because dams trap nutrient-rich sediment that is needed to replenish downstream deltas, the Sambor “would also have a tremendous impact on the Mekong Delta in Viet Nam, which is the most productive delta in the world,” says Rafael Guavera Senga, WWF’s senior advisor for global energy policy. (See “Running Out of Sand,” below.)

The Sambor dam “would affect the whole economy of the river in a big way: fisheries, agriculture, and tourism,” says Senga.

Perhaps the most sobering prognosis for the proposed dams came from the NHI assessment. In its words, the dams would “literally kill the river.”

Turning toward the sun

Running Out of Sand

Fish swimming toward sand

The Mekong Delta has a sediment problem.

Sediment—the silt, clay, sand, gravel, and organic solid materials carried by rivers—is indispensable for a healthy river basin. It carries nutrients that nourish fish, it replenishes soil, and it nutrifies agricultural lands that are irrigated with river water.

Moreover, sediment maintains the stability of the riverbed and the shape of the deltas, says Marc Goichot, WWF’s freshwater lead for Asia Pacific. “Sediment,” he says, “is the skeleton of a river system.”

But starved of sediment, the Mekong Delta—home to more than 20 million people and responsible for half of Viet Nam’s rice production—is rapidly shrinking and sinking, as seawater claims agricultural land. To date, the mighty Mekong River has lost a whopping 77% of the sediment that it once carried to the delta each year. The situation grows more dire as the climate warms and sea levels rise.

Dams, which trap sediment, are a key culprit in sediment loss. But they aren’t the only one. Throughout the lower Mekong basin, sand and other aggregates are mined relentlessly for use in land reclamation and to feed the region’s booming construction industry.

In an effort to increase the Mekong Delta’s natural ability to adapt to climate change challenges and mitigate the adverse impacts of massive land-use change—notably the loss of the delta’s floodplain space—WWF launched a project to promote sustainable sand mining in 2019.

With financial support from the German government, WWF is working with stakeholders in Viet Nam—including the Ministry of Agriculture and Rural Development—to promote awareness of the negative impacts of unsustainable sand mining and to advocate for alternative sourcing, better regulation of demand, greater supply-chain transparency, and improved practices.

The project aims to better estimate the sediment carried by the Viet Nam stretch of the river and introduce annual sand excavation quotas. Ultimately, the goal is to create a sand and gravel “budget” that establishes sustainable extraction rates for the basin and promotes more sustainable sourcing.

Immediately after Cambodia’s 2016 announcement, environmental watchdogs like International Rivers and Earthrights International, as well as WWF, began working to draw attention to the immense environmental, social, and economic risks posed by the dams.

WWF and others worked with decision-makers and investors not only to highlight the catastrophic impact the dams would have on the fragile Mekong ecosystem, but also to strongly promote clean and renewable energy alternatives to both hydropower projects—alternatives that would contribute to the country’s energy goals and boost the economy in a shorter time frame.

Senga says that the flat expanses of land needed for industry-scale solar and wind farms are ubiquitous in Cambodia. The falling costs of renewable power present a unique opportunity for the country to become energy independent—without harming the Mekong ecosystem. Moreover, solar farms can be deployed in less than six months’ time—much faster and cheaper here than hydropower.

While there may be no official data on the cost of the Sambor and Stung Treng dams, a WWF study concluded that the costs associated with the dams’ construction—high capital and transmission costs and devastating impacts on fisheries, agriculture, and tourism—would vastly surpass those associated with solar power.

In August 2019, WWF, the Swiss Agency for Development and Cooperation, and the Cambodian Ministry of Mines and Energy—the driver of the country’s energy policy—organized a forum in Phnom Penh on solar energy investment. It was attended by both government officials and infrastructure investors, including key solar panel firms from China.

The forum was well timed. It came on the heels of a drought-stricken summer that resulted in record-low water levels in the Mekong, affecting the performance of already existing dams in Cambodia and raising questions about the reliability of hydropower.

At one point, the conference room plunged into darkness, recalls Senga—a power cut. “Everybody just looked at each other with that expression of, ‘OK, this is a great reminder that Cambodia needs to deploy more solar energy!’” he says.

Currently, solar accounts for barely 2% of the country’s energy mix, which is almost evenly split between hydropower and fossil fuels including coal. But, says Senga, “we were able to show that Cambodia has enough solar energy sources so that it can be the principal source of energy.” Not only that, but WWF showed that by switching to solar and wind, the country could become energy independent before 2050, further propelling its economy forward through reduced electricity rates and the reliable energy supply needed to power its key industries.

“And this,” stresses Senga, “is without further development of hydropower on the mainstem Mekong.”

A fisher cleans his boat in the water of the Anlung Cheauteal Pool—on the border between Laos and Cambodia.

A bird takes flight in a flooded forest in Stung Treng, Cambodia.

The big win

Good news came in March 2020 and sent jubilant shock waves across the basin: The Cambodian government paused the Sambor and Stung Treng projects and imposed a 10-year moratorium on new dam construction on the Mekong mainstem.

“Meaningful dialogue with key players, including relevant government agencies, and provision of solutions and alternative options were the keys to the success of this campaign,” says Teak Seng, WWF-Cambodia country director. “It’s a historic victory.”

“This was a huge win,” says Goichot, “especially for the Irrawaddy dolphin. The main threat has been removed.”

In addition to the dam rulings, the government announced that the Ministry of Mines and Energy plans to nearly quadruple solar energy capacity from 90 megawatts (MW) to 320 MW by 2022 and is developing an 80 MW wind power plant in southern Cambodia and a 100 MW plant in Mondulkiri Province. All that energy could provide power—at current usage levels—for close to 1.4 million Cambodians.

Even though additional sustainable energy will be needed to keep up with the country’s desire to grow their economy, the government’s change of course “put Cambodia on the world map,” says Seng. “We have set an example for other countries. Everything is possible, so we all should be optimistic and have hope.”

Stingray illustration Giant freshwater stingray
Tiger illustration Tiger
Catfish illustration Mekong giant catfish

Unfinished business

Despite the wins in Cambodia, Goichot says the Mekong remains “in a state of stress that is pretty alarming.”

WWF has been working on a plethora of solutions to address the threats facing the river. To stamp out illegal fishing in the Mekong Flooded Forest, for example, WWF has been supporting community fisheries and river patrols and helping villagers develop alternative revenue streams. We have also been working with authorities in Viet Nam to counter the impacts of sand mining—another major threat to the Mekong Delta.

Working with companies on water stewardship and building with nature— understanding key natural processes and building with them, not against them—are equally important, says Goichot.

But perhaps most important, he says, we need to keep reminding people of the river’s significance. “We need to keep up the awareness of the value of the river, climate-disaster prevention, the cultures, the communities, the natural wonders, and the economy,” Goichot notes.

Awareness, he says, is a vital first step in the multistream effort it will take to protect a thriving Mekong for the long haul.

Learn more about the Greater Mekong.  

Positive flow

WWF works with communities, governments, and businesses on the lower Mekong to promote water stewardship and ensure that humans and the river ecosystem prosper. Keeping rivers free flowing is one of the most cost-effective climate change adaptation strategies we have.

1 Myanmar

The Irrawaddy and the Salween, two of the last large free-flowing tropical rivers in Asia, flow through the spectacularly biodiverse landscapes of Myanmar. WWF recently completed a detailed analysis of updated country data to map the connectivity of these rivers and is supporting development of a national alternative-energy vision.

2 Laos

Laos contains some of the largest natural forests remaining in Asia, so WWF is promoting the sustainable use of forest resources in this landlocked country. Highlighting the significant value of a free-flowing Mekong, WWF promotes alternatives to dams, which can provide energy and other socioeconomic services while minimizing impacts on nature and people.

3 Thailand

Thailand’s vital rivers and wetlands are under pressure from infrastructure and agricultural growth in a booming economy. WWF is advocating for policies that improve the governance of freshwater resources here. As a result, water stewardship, sustainable infrastructure development, and green energy production have begun to move from concept to reality.


4 Cambodia

In the stretch of the Mekong mainstem between the town of Kratie and the Laotian border, WWF works with local communities and Cambodia’s Fisheries Administration to protect the Irrawaddy river dolphin. Here, numbers of the critically endangered mammal grew from just 80 in 2015 to 100 in 2019—the first recorded increase in the population in over 20 years—and have stabilized, according to a 2020 report.

5 Viet Nam

Viet Nam is among the top five garment exporters in the world, and textile manufacturing is a thirsty business. WWF is engaging with key players in the industry—from local factories to global apparel brands—to more actively manage water resources, address the sinking of the Mekong Delta, improve water quality, limit industrial pollution of the river, and avert climate disaster.

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