Ahead of crucial discussions about the future of Cambodia’s wetlands this month, residents of a globally significant area of the Mekong River fear an environmental catastrophe if hydropower plans go ahead

Just south of the Laos border – about a kilometre from where the Don Sahong hydroelectricity dam will be built – the “flooded forest” is quiet.

Between rocky islands and sandbanks, hundreds of gnarled trees rise out of the Mekong River, most bent downstream by the current. In their branches perch rare ibises, eagles and other birds, while under the water uncountable species of fish spawn among their interwoven root systems which, depending on the season, can be seen partially exposed above the surface.

A pod of six critically endangered Irrawaddy dolphins spend most of their time in a deep pool on the border at Onlong Chheuteal Village. Tourists often kayak down from the 4,000 Islands in Laos to watch them splash and frolic, their stubby noses and fins breaking the surface.

But environmentalists fear the playful river mammals won’t last long after the dam’s construction begins.

The 14,600-hectare wetlands, that stretch down to the town of Stung Treng, are one of only three in Cambodia to have been designated a Ramsar site – the wetlands equivalent of a national park.

Keo Chuon, 54, is a chief river guard with the Fisheries Administration. His job is to go on patrol five or six times a month on the lookout for people fishing where they shouldn’t be or using illegal methods like gill nets – one of the major causes of dolphin death – or electricity.

He said he had seen endangered white shouldered ibis, giant catfish and Siamese crocodiles – including babies.

“There are many kinds of animals in the wetlands,” he said.

The residents of the area are rightly proud of its natural heritage and, ahead of a potentially crucial Ramsar Convention meeting in Siem Reap this coming week, they expressed concerns about the dam’s possible impact.

Thith San, a 53-year-old from Onlong Chheuteal Village, also helps patrol the area as a community fisheries volunteer, along with members from 30 families in his village.

He used to be a fisherman himself but turned to farming rice when the government introduced restrictions to help protect the area’s fish stocks. “I just want to protect the dolphins and fish for future generations,” San said.

Other nearby villagers said they were happy to turn to other “livelihood activities” such as farming chickens in order to protect the wetlands.

San said he was worried that their efforts would be rendered pointless by the dam, the construction of which is expected to traumatise the dolphins and block migrating fish.

“I don’t want it to go ahead,” he said.

Despite the wishes of nearby residents, preparatory work - including the construction of roads and a bridge – has already begun for the 32 metre-high dam, a “run off river” hydroelectric power scheme to be built across the Sahong channel in the Siphandone (4,000 Islands) area to generate 256MW of electricity.

Environmentalists’ primary worry is that the dam will interrupt migratory fish because it will block the only tributary that allows for migration all year round, affecting fish stocks not only around Stung Treng but far up and down the Mekong River.

As for the dolphins, they say the explosives used for excavation have the potential to kill them outright or at least damage their ability to use the sonar on which they depend to navigate through the murky water and communicate.

Then there’s the possibility of toxic spillage during construction, reduced prey and physiological stress. 

WWF-Cambodia country director Chhith Sam Ath said the dam could also affect the main population of about 80 dolphins further downstream.

“The Mekong River dolphin population is already under stress, but over the past two years the calf mortality has very significantly reduced and the population is slowly recovering,” he said. “Adding a very significant impact at this stage of the conservation efforts from Cambodia to save the dolphin can be a killer blow that will cause the extinction of the Mekong River dolphin.”

The Malaysian company contracted to build the project, Mega First Corporation, claims that impacts on the dolphins – from explosives, sediment, noise, flow, boat traffic and loss of prey – will be mitigated. Measures include using cofferdams (temporary watertight enclosures) to contain sediment and shockwaves and restricting the areas where explosives will be used.

Other channels around the 4,000 Islands are also being expanded to facilitate fish migration.

However, Ian Baird, an expert in Southeast Asian geography and ecology who in 2011 published a detailed analysis of the probable impacts of the dam, is sceptical that these measures will be effective.

“I believe that the conditions of the Hou Sahong Channel, with its continuous flow of water and great width, could never be duplicated through implementing the proposed mitigation measures,” he wrote.

This coming week in Siem Reap, at the Asian Wetlands Symposium, about 100 delegates including government representatives of Asian Ramsar signatories will meet to discuss “wise use” of wetlands in Asia and prepare the agenda for next June’s Ramsar Convention meeting in Uruguay.

The WWF is set to use the meeting as an opportunity to lobby Ramsar signatory countries including Laos.

“If Ramsar 2015 adopts resolutions on energy and infrastructure development, including taking steps to ensure hydropower dam development is sustainable, then signatories must respect and fulfil their commitment to the Ramsar treaty and take concrete steps in their national planning of energy and infrastructure development to ensure it does not go against the Ramsar principle of ‘wise use’ of wetlands through conservation and livelihood benefits,” Chhith Sam Ath said.

Meanwhile, the dam is going through a six-month Mekong River Commission “prior consultation” process that began in July but was not made public until last month.

A regional consultation meeting is to be held on November 14 with up to 100 representatives of stakeholder groups, the MRC and member countries to discuss the dam, the MRC’s technical review initial findings and to seek feedback from interested groups.

The WWF and other environmental groups want the Lao government to consider the Thako Water Diversion, an alternative hydropower project using the same water flow that would produce less power but not block fish migration.

However, it seems none of this is likely to stop the Don Sahong project going ahead.

In a stinging opinion piece published in Bangkok’s the Nation newspaper last Friday in response to NGO complaints about the process, Lao vice minister of Energy and Mines, Viraphonh Viravong, said the consultation procedures in the 1995 Mekong River agreement were “not a mechanism for approving or rejecting any particular project”.

“MRC [Mekong River Commission] is not a building permits office.”

The vice minister said that environmental activists were “grousing” about the consultation process because they wanted the project cancelled rather than see the technical aspects improved and environmental effects mitigated.

“By now, they should realise that the Lao government will not be deterred from its commitment to develop clean, renewable hydropower, a source of national pride for the Lao people and a sustainable, reliable source of electricity for the region,” he said.

Back at the Ramsar wetlands, at the riverside village of Vun Sean, a few kilometres downstream from the border, the bones of a dolphin are displayed in a glass case alongside a Buddhist shrine.

Taking a break from tending to her rice wine still, Chav Saveth, 39, explained it was a form of respect and recognition of the animal’s rarity.

“There used to be many dolphins that swam past our village,” she said. “But now there are only a few.

“We know that they are important to the whole world – not just us.”