For years, territorial disputes in the South China Sea have dominated Southeast Asia’s security agenda. The ferocity of rows over vital sea lines carrying up to a third of global trade valued at US$5 trillion annually has embittered relations between China and some Southeast Asian claimant states. Meanwhile, external powers such as the United States have jumped into the fray, seeking to keep China’s maritime ambitions in check. While the prevailing narrative tends to be that the South China Sea increasingly has become the main theatre of hegemonic competition between superpowers, this view tends to miss Asia’s other brewing water conflict in the Mekong Delta. Decades down the road, this area could be an even more explosive flashpoint than the South China Sea. Up to 60 million people in the Mekong basin directly depend on the river for water consumption, fisheries resources and mineral-rich soil. But the broader issue is ensuring food and water security for Indochinese nations, some of which, namely Vietnam and Thailand, are among the world’s biggest producers of food staples such as rice. The dispute involves China and the Southeast Asian states of Thailand, Vietnam, Cambodia, Myanmar and Laos. It is a classic case of upstream versus downstream nations. The conflict is not too dissimilar from aquatic squabbles between Egypt and Ethiopia over the Nile River in Africa and between Turkey and Iraq over the Tigris and Euphrates rivers in West Asia. At the dispute’s heart is the dam-building bonanza among littoral states – China and Laos in particular – which has downstream nations on the verge of panic. For Laos, the dam-building spree, including the Don Sahong and the much larger Xayaburi projects, is aimed at transforming the country into the “battery of Southeast Asia”. The poverty-stricken nation, which has limited domestic energy consumption, hopes to generate surplus electricity for export. Is Mekong River set to become the new South China Sea for regional disputes? China’s strategic and development goals include developing poorer southern regions such as the Yunnan province to arrest the growing inequality between China’s prosperous coast and its interior. China also seeks to improve energy security as its manufacturing base matures and hyper-consumerism sets in. Hydroelectric power is seen as a more environmentally friendly alternative to coal power plants, a major source of concern in the country’s industrialised regions. Down the road, the Mekong River area could be an even more explosive flashpoint than the South China Sea To the world’s second-largest economy, the powerful upper Mekong, known as Lancang Jiang in China, is a tantalising source of clean energy. So far, China has completed six large-scale dams in the area, collectively producing about 15,000 megawatts per year. This output is more than sufficient to support cities with as many as 2 million residents. But many more are to come. Manwan, the first of as many as 28 Chinese dams under consideration, was built back in 1995. The Mekong already hosts up to 11 major dam projects, many of which already are operating, with 30 more spread across its tributaries. Moreover, China aims to transform the river into a major navigational channel flowing all the way into the South China Sea, much of which the country claims as part of its ancestral heritage. It plans to demolish around 15 small-sized land features spread across the river under the rubric of “navigation channel improvement” mainly for commercial vessels weighing up to 500 tonnes. These projects are raising alarm across the region. Excessive dam building has, according to some observers, negatively affected fisheries stocks. It also has transformed the predictability of water flow and its availability in places such as the Tonle Sap, the region’s largest freshwater lake, and the downstream movement of silt for fertilising agricultural lands. Chinese dams blamed for exacerbating Southeast Asian drought Ultimately, tens of millions of Indochinese could be at risk of regular droughts, declining agricultural productivity and diminishing fisheries resources. Absent effective diplomatic solutions, the region also could see heightened geopolitical tensions, even direct conflict. As climate change proves disruptive across agricultural Asia, resource competition and water wars could take an even more vicious turn. This is precisely why littoral states should support multilateral diplomatic efforts to peacefully manage the disputes. The 1996 agreement on cooperation for the sustainable development of the Mekong basin, signed among Southeast Asian littoral states, provides a framework for institutionalised cooperation. The agreement stipulates that parties should refrain from unilateral activities which imperil the rights and developmental interests of neighbours and undermine the area’s ecological sustainability. But much remains to be done. Five things to know about the Lancang-Mekong Cooperation summit The establishment of the Lancang-Mekong Cooperation mechanism, which involves China and Southeast Asian littoral states, is a step in the right direction. It provides a much-needed platform for all parties to arrest the brewing conflict and adopt necessary mitigation and adaptation measures for affected communities. Proactive diplomacy is the only way forward. Richard Heydarian is a Manila-based academic and author