With the end of the dry season in the Lower Mekong Basin (LMB) — a period roughly running from November to May — the magnitude of the problems affecting the Mekong River is starkly apparent. With estimates that the river has been at its lowest level in the last 100 years — a circumstance that has had effects throughout the LMB and is particularly marked in the Mekong Delta and the Tonle Sap (Cambodia's Great Lake) — the gravity of the current situation cannot be overstated.

Although it is clear that the fundamental causes of these problems stem from a prolonged drought linked to the El Nino effect that has dominated weather patterns both in the LMB and in China's Yunnan province over the past year, there can be no denying that China's dams have played their part in altering the previous pattern of water flow down the river.

There are six completed dams on China's section of the Mekong (known in China as the Lancang), a further dam still under construction that appears to be operating, and a further three under construction that are not yet operating. As has long been predicted by critics of China's Mekong policies, these dams hold back water that once flowed down the river in the dry season. For instance, as is widely known, 40% of the water that once flowed past the Lao capital of Vientiane during the dry season originated in China. This is a fact that contradicts Chinese claims that the amount of water in the Mekong that originates in China is only 16% and hence that its dams are of little consequence.

In an effort to allay the concerns of downstream countries, China released water from its Jinghong dam in March, opening the dam's floodgates for two weeks. At the same time, and in an action that underlines the failure of the Mekong River Commission to play a role in relations between China and the lower Mekong countries that are its members (Laos, Thailand, Cambodia and Vietnam), Beijing announced the first meeting of the Lancang-Mekong Cooperation Mechanism to 'provide political guidance and a sub-regional roadmap for cooperation.'

It is too early to evaluate the utility of this initiative.

Neither this initiative nor the hoped-for rains of the rainy season that are now due will do much to mitigate the immediate and serious situation which has seen the waters of the Tonle Sap in Cambodia fall to one of the lowest levels in generations, and a dramatic increase in saltwater incursions into Vietnam's Mekong Delta. Fish caches in the Tonle Sap will be affected and agricultural production in the Delta will suffer. The greatly diminished flow of water down the Mekong also means that the life-giving nutrients that usually accompany the River's flow have been largely absent since drought conditions began in the middle of 2015.

Yet as the critical situation just described has developed, there is no slowing in the dam building program in China and more disturbingly in the LMB. The Xayaburi dam in Laos appears likely to be completed before the end of the decade. A ceremony in January marking the establishment of a coffer dam at the controversial Don Sahong site in the far south of Laos suggests that construction on the main dam wall is now taking place, and in Cambodia construction of the Lower Se San 2 dam on a major Mekong tributary in Stung Treng province is reported to be 40% complete. There is broad scientific consensus that these three dams in Laos and Cambodia will lead to significant reductions in fish catches, the major component of the protein intake in the two countries as well as in the Mekong Delta region of Vietnam.

What I find striking, and disturbing, from a personal point of view and as someone who saw the river before any dams were built, is the speed with which change has come about. Until the 1980s the Mekong had flowed essentially unchanged for millennia. It has now been changed, irrevocably, in less than half my lifetime.

Photo courtesy of Flickr user Vadim.