Nineteenth-century Mekong explorers marvelled at the wetlands of Siphandone in southern Laos, a district of spectacular waterfalls, swirling rapids, steep narrow gorges and myriad islets. Beyond the rapids, a colony of rare Irrawaddy Dolphins still frolic near the Cambodia border. The dam would cause serious nutritional problems in the Mekong region DR IAN BAIRD But experts say this ecotourism paradise, known as the "Four Thousand Islands" region, could soon be irreversibly damaged by the construction of a hydro-electric dam recently announced by Laos, only a few kilometres from the renowned Khone Waterfall, a major tourist attraction. The communist government notified the Mekong River Commission [MRC] on September 30 of its plans to launch construction of the Don Sahong Dam next year. The 260 megawatt dam would be Laos' second Mekong hydropower project. The commission is the multi-nation body that supposedly oversees development on the vital waterway. Concerns about the new dam were raised this week in Bangkok at a forum of 103 Thai NGOs campaigning against it. Photo-journalist Suthep Kritsanavarin, who has documented the communities of the region for National Geographic magazine told the forum: "If the water level in the Hou Sahong [channel] increases [to support the dam], we will see a decrease in other areas, including the Pha Pheng [Khone] Waterfall. "If there's only half of the water in the dry season, would anyone want to go there?" The NGOs claim to represent the people of eight Thai provinces bordering the Mekong, who experts say will suffer major losses of fisheries and agricultural fertility if the dam is built. Dr Ian Baird a Mekong specialist at the University of Wisconsin-Madison told the Post: "The dam would cause serious nutritional problems throughout the Mekong region. Decreasing availability of fish in the marketplace would lead to higher prices, reducing fish consumption, especially by poorer consumers." The Hou Sahong channel, which would feed the dam's reservoir, is the key route used by 80 to 90 per cent of migratory fish coming from Cambodia. UK fisheries expert Terry Warren, a consultant on the dam's first environmental assessment said "if these fish can complete this migration, Cambodian fisheries will continue to flourish". "[But] stop a migration and within a few years everything will start to collapse and eventually cease to exist. I see disaster looming for the fisheries of Cambodia and southern Laos, if this project goes ahead," he said. Dam-builder Megafirst has dismissed these concerns. Megafirst Senior Environmental Manager Dr Peter Hawkins told the Vientiane Times "environmental impacts can be mitigated by using other natural channels adjacent to the Hou Sahong". The Laotian government has long been embroiled in controversy over its first dam on the Lower Mekong at Xayaburi. It is determined to press ahead with Don Sahong, despite objections from downstream nations. Sin Niny, the Cambodian deputy chairman of their National Mekong Committee, has demanded that Laos stop all construction plans until its neighbours have reviewed the environmental impact. Vietnam has called for a 10-year moratorium on all mainstream dam building. MRC members have been bitterly divided over unilateral damming of the Lower Mekong. Cambodia and Vietnam want independent scientific studies before any dam goes ahead. Don Sahong will be another major test-case for the MRC and its mandate to ensure the Mekong's health. Its fisheries support 60 million people. Laos surprised many with its unilateral assessment that Don Sahong "is not a mainstream dam", a move that would allow it to avoid public forums. Cambodia and Vietnam insist Don Sahong is a mainstream site. Hans Guttman, CEO of the MRC, said: "Don Sahong is a mainstream dam [according to the MRC Secretariat] … since its inflow comes not from a tributary, but rather through the mainstream." Increasingly the Mekong's future looks bleak. The MRC has no right of veto over what many NGOs view as a destructive dam-building spree.