According to conservationists, Cambodia's 400-megawatt Sesan 2 dam will prevent sediment travel down to the Mekong's delta, depriving it of nutrients needed for aquatic life and rice production
In Thai and Lao languages, Mekong roughly translates as ‘mother of rivers.' As one of the world's largest waterways it stretches more than 4,000 kilometers thrusting through China, Thailand, Laos, Cambodia and Vietnam before emptying into the South China Sea.
For wildlife enthusiasts in the region, these are exciting times. A horned lizard and rainbow-headed snake were among 163 delightful new species documented last year by scientists alongside 10 endangered Irrawaddy dolphin calves. Fewer than 90 Irrawaddy dolphins exist on the planet.
But all is not well.
In January 2016, build on the 260-megawatt hydroelectric Don Sahong dam began less than a mile from Laos' border with Cambodia. The area is home to a trans-boundary dolphin pool where numbers are critical. Just three remain. A figure the World Wildlife Fund (WWF) warns is ‘no longer viable. (Functionally Extinct)
In recent months the dolphins have moved out of their two-kilometer preservation into areas where illegal fishing methods are rife. Villagers blame the daily boom of dynamite used to blast rocks in dam construction.
"Even when you are inside the water, it's very loud," says Mekong river ranger, Sok Laing, responsible for patrolling the dolphins' protected area. "The noise is too loud and dolphins need to live in a place that is quiet," he adds.
It's a worry for villagers who rely on the thousands of tourists the dolphins bring yearly.
"Only local (protected) fishing is allowed in this part of the river but where the dolphins are now, no one is responsible for controlling," says Bu Maen, a 27-year-old boat driver.
His village, Anlong Svay Thom, in Cambodia's Stung Treng province, lies just south of the dam. It's a smattering of wooden frame houses built on stilts in the Khmer fashion that overlook the river.
A new road was constructed to provide greater access to the secluded village. This boosted business for those driving tourists across the waters.
"Customers increased because of the road but now the dolphins have gone I don't know what will happen," Maen says.
Dolphin habitats threatened by human activity
Irrawaddy dolphins in Cambodia can be found in Stung Treng and Kratie, forming pools they generally live in for life.
These freshwater marine mammals are one of the oldest creatures in the world, long symbolizing the health of a river but forced now into near extinction by human activity.
Illegal fishermen are wise to the times when dynamite is used on the construction site say villagers. Some employ homemade bombs to blast fish; particularly in the new area the dolphins seek refuge.
"Poachers are very intelligent and very smart," says Rin Narouen, conservation area manager at WWF Cambodia. "They use it on the same day so nobody can catch them."
He believes if no action is taken, "they [dolphins] will become extinct."
If such dire prognosis were to happen, "it means the income of people here will be affected," says Laing. "Right now people come here because they want to see dolphins, if the dolphins are gone then no tourists will come again."
Why governments are damming the Mekong
Around 120 million in Southeast Asia have no access to electricity. South East Asia Energy Outlook
In Cambodia this equates to 44 percent of its population according to Word Bank figures. Access To Energy
For governments that border the river, the cheaper and greener solution is to dam. In China for example, 88 percent of energy consumption uses fossil fuels. Fossil Fuel Energy Consumption
Large hydropower dams already exist on the Mekong in China, but more than 100 are planned by Mekong bordering countries. Of these, 11 will dam the river's mainstream in Laos and Cambodia built by Thai, Malaysian, Chinese, and Vietnamese developers.
Laos, the poorest of its neighbors with a GDP of just $12.37 billion has declared its ambition to be ‘the battery of Southeast Asia.' It will host nine of the dams for much needed revenue generation despite not benefitting from the electricity produced. For example, Don Sahong's energy will be exported mainly to Thailand and Cambodia.
Life in Preah Rumkel remains as it has for centuries
Fish is a staple sought from a river containing over 1,000 species of fish. The Mekong accounts for an astonishing one quarter of the world's freshwater catch.
Every morning, 29-year-old fisherman Horn Phoeun heads onto the Mekong.
"Before there was a lot of fish but now there are not many," says Phoeun. He has frequently changed the pools he fishes from in order to accommodate for the loss of catch. He blames illegal fishing and dams.
"It takes longer to catch the same amount of fish," he says. Like many other villagers, he is considering switching to farming seeds and nuts. But it's an expensive occupation costing $750 more to run and one riddled with risks of flooding.
"My father was a fisherman, my whole generation were fisherman," he adds.
Upstream the Lower Sesan 2 dam is almost complete.
Some 34 miles east of the Don Sahong, fishermen and women gather on the muddy banks of the river's Sesan channel with reams of mesh nets cascading around them.
Almost lost in the fabric of the net, they must decide whether any further attempts at fishing today will bring in a catch.
Here most come from Pluk Village in northern Cambodia, close to the $800m Lower Sesan 2 dam nearing completion on a Mekong tributary. It's a venture between China's Lancang Hydropower International Energy, Cambodia's Royal Group, and Vietnam's EVN International.
Utha Camy, a fisherman in his late 50s, stoops beside the nets. "Before the dams I would have caught more than 5 kilos by now," says Camy. "And if I kept fishing from now until 6.30pm I would have caught a further 10 kilos."
Today, after an unsettling 6am rise he has caught just one fish in five hours. The number of dams already built mean irregular variations in water levels that interfere with fish migration and spawning. There is no longer enough fish to go around.
"We all know this but right now there is no job for us to do, so we continue to just fish," shrugs Camy.
A 2012 study by researchers from the U.S. and Cambodia estimated that the Sesan 2 dam once complete would reduce fish catch by 9 percent. Fish Biodiversity, Food Security & Hydropower in the Mekong River
The Mekong River Commission (MRC) oversees dam constructions on the lower Mekong through a 1995 agreement. It's a committee of four member nations-Vietnam, Cambodia, Thailand, and Laos. China is not part of the voluntary commission and it's yet to resolve disagreements on projects.
And as the Ecologist has reported previously, many of the dams have gone ahead without backing from all member states. Death By Strangulation
So many dams are catastrophic for fisheries activists warn
According to conservationists, Cambodia's 400-megawatt Sesan 2 dam will prevent sediment travel down to the Mekong's delta, depriving it of nutrients needed for aquatic life and rice production.
A two and a half year study submitted by Vietnam to the MRC in 2016 concluded that there were "high to very high adverse effects on some of the key sectors and environmental resources in Cambodia and Vietnam," as a result of planned dams.
Around 40 percent of Vietnam's rice stock is grown in the delta. The country is still recovering from last year's scathing El Nino induced drought - its worst in a century. [http://www.channelnewsasia.com/news/asiapacific/vietnam-hit-by-worst/2562802.html].
"The further downstream a hydropower is sited, the more impact it will have on fisheries, notably on fish migration," Marc Goichot, water lead at WWF's Greater Mekong Programme said via email.
In the case of Don Sahong, for example the dam would block the only channel known as a year round route for migrating fish, vital to around 60 million people who rely on the protein the Mekong's fish provide.
Mega First Corporation, the dam's developers have in the past dismissed concerns, saying a new fish passage would be built.
"What the developers have done is widen some of the other surrounding channels and blast clear them out so that they are passable for fish migration as alternative routes," says Maureen Harris, Southeast Asia program director at advocacy group International Rivers. "The problem is they've been doing this as they build the dam."
Scientists believe there is lack of sufficient evidence that fish would migrate through new channels. The Myth of Sustainable Hydropower
"There are no example of success in large tropical rivers," says Goichot.
In northern Cambodia villagers battle developers
Bai Pumsen, a 30-year-old rice farmer and his family of five were relocated six months ago to make way for the Sesan 2. His old home in Kbal Romeas will be flooded along with 5,000 others when the dam opens later this year.
Pumsen's resettlement village currently called Kbal Romeas II is a regimented mix of yellow and blue concrete houses alongside traditional wooden builds.
Each family is entitled to either a house or $6,000 to build a new home as compensation and a 12-acre land to farm. New villages boast schools, health centers, and crucially electricity. However villagers complain the land isn't ideal for farming, and is far from freshwater sources.
"Staying here is more difficult," says Pumsen. "More than 50 families are waiting with no job to do."
Land is yet to be cleared for agriculture.
Like Pumsen, many frequently make the two hour round trip back to their old rice fields for work and food and are demanding to move back.
"Here I have to spend a lot of money," says 31-year-old mother of two, Sarun Nan. "Before there was no need to buy food, we just go down to the river and catch fish ... now also for drinking and cooking I need to buy water."
Nan and her husband commute by motorbike to their old village to fish and hunt in the forest. "I don't know what I will do if I cannot continue to go," she says.
There are some in Kbal Romeas who refuse to move to the resettlement site having seen how their former neighbours are struggling.
Dams are not the problem say experts but they need to be better planned
"It is easy to assess which ones will have the greatest negative impacts and the most positive. Common sense would be to prioritise the ones with least negative impacts, and postpone the ones with the greatest," says Goichot. "Don Sahong, Lower Sesan, are in the 20 percent group with the highest negative impacts. They should not have been prioritised."
Others point to more ecological means of energy generation through solar power. But these are difficult to attract financial investment and slow to generate immediate revenue.
"Typically what's usually done in these projects is an economic impact assessment, where they weigh up the benefit but not the costs," believes Mark Zeitoun, professor of water policy and security, at the University of East Anglia in England.
Zeitoun has been researching similar environmental issues on the $2.4 billion Merowe dam built on the River Nile in Northern Sudan. It's displaced more than 50,000 people, blocking fish migration and degrading water quality. Impacts of Merowe Dam
In the US, older dams are being decommissioned. After its largest dam removal - the 210-foot-high Glines Canyon dam - salmon have returned to the Elwha river in Washington after almost a century of absence say scientists. River Restoration
But, "decommissioning is very expensive, much more expensive than building a dam," adds Zeitoun. "Once you build a dam you are locked into it for a very long time."
"The dams are affecting everyone who live along the river," reflects Laing as he sits, legs crossed in front of his house looking ahead towards the calm waters. "We have to try to find a way to keep the fish and the dolphins within the Mekong. But how I don't know."
Nosmot Gbadamosi is a freelance journalist based in London. She can be followed on Twitter @nosmotg
Nicolas Axelrod and Thomas Cristofoletti are co-founders of Ruom, a collective of journalists based in Asia. Read stories here [http://www.ruom.net/feature-stories/]
More information: Save the Mekong [https://savethemekong.org] campaign.
Also on The Ecologist: How the largest inland fisheries in the world are being destroyed. Destuction of the world's largest inland fisheries