This picture taken on February 14, 2020 shows a food vendor waiting for customers as tourists walk along a beach in Sihanoukville. Tan Chhin Sothy | AFP | Getty Images

China's upstream activities along the Mekong River have long been contentious — but a recent study has sparked fresh scrutiny over its dam-building exercises, reigniting warnings that millions of livelihoods could be destroyed. A U.S.-government funded study by research and consulting firm, Eyes on Earth, found that Chinese dams are holding back large amounts of water upstream on the Mekong, which exacerbated a severe drought in the Southeast Asian countries downstream last year. China dismissed the scientific report as "groundless." The 4,350 kilometer (2,700 mile) Mekong River runs through six countries. Starting from China — where it is called the Lancang River — it flows past countries like Cambodia, Laos, Thailand and Myanmar, before emptying into the South China Sea via Vietnam. It is the lifeblood of these Southeast Asian countries and supports the livelihood of nearly 200 million people there who depend largely on farming and fishing. China built its first dam on the upper Mekong in the 1990s and currently runs 11 dams along the river. The country has plans to build more dams, which are used to generate hydropower. Some of those dams have compounded the alteration of the river's natural flow, resulting in the Lower Mekong recording "some of its lowest river levels ever throughout most of the year," said the Eyes on Earth study. The report was published by the UN-backed Sustainable Infrastructure Partnership, and the Lower Mekong Initiative — a multinational partnership of the U.S. with Cambodia, Laos, Myanmar, Thailand and Vietnam. According to the study, which used data from 1992 to 2019, satellite measurements of "surface wetness" in China's Yunnan province suggest the region actually had slightly above-average combined rainfall and snowmelt from May to October 2019.

But water levels measured downstream along the Thai-Lao border were at times lower than they should have been, according to Alan Basist and Claude Williams, who authored the report. This points to China holding back dam waters while lower Mekong countries experienced drought that impacted rice production and fisheries, threatening food security for the region.

'Irreversible damage' to ecosystem

"China's dam management is causing erratic and devastating changes in water levels down stream," according to Washington-based security think tank, Stimson Center. "Unexpected dam releases caused rapid rises in river level that have devastated communities downstream, causing millions in damage shocking the river's ecological processes," according to a report dated April 13. While China was the subject of the Eyes on the Earth Study, stakeholders acknowledge that all the dams — more than a hundred operational ones along the Mekong — impact the river, with each facility putting incremental pressure on the environment. Not all of them belong to China.

We believe that the resultant threat to food security from this damage will put upside pressure on inflation for countries downstream in the Mekong River. Fitch Solutions

But as the most upstream country, China's dams have been deemed to be of strategic political interest as countries downstream may become increasingly beholden to Beijing for water, analysts said. Communities living along the river have been registering unusual water fluctuations with the building of new dams, said Pianporn Deetes, Thailand representative at International Rivers, a non-governmental organization. Some have seen unseasonal droughts and sudden water level rises, she added. The unusual activities "destroy the natural system of the Mekong River," Pianporn said during an online discussion on Friday held by the Foreign Correspondents' Club of Thailand. It destroys the livelihoods of those who depend on the ecosystem, including aquatic plants and animals, she said. Research from Stimson Center pointed to the same conclusion. It said that fishing communities alongside Cambodia's Tonle Sap Lake – where Cambodians catch up to 70% of their protein intake – reported fish catches that were 80-90% lower than usual. "Today some highly populated portions of Vietnam's Mekong Delta have completely lost access to fresh water," said authors of the report, Brian Eyler and Courtney Weatherby. Pianporn called for data and information transparency from both China and other downstream countries, and urged authorities to view the Mekong River as a entire system and a shared resource.

A fisherman checks his net along the Mekong River at Sangkhom district, in the northeastern Thai province of Nong Khai, on October 31, 2019. The once mighty Mekong River has been reduced to a thin, grubby neck of water across Northern Thailand, blamed on drought and a recently opened dam hundreds of kilometers upstream. Lilian Suwanrumpha | AFP | Getty Images

Others have highlighted the environmental threats of the numerous dams along the Mekong River. Fitch Solutions in a February report: "We believe that the resultant threat to food security from this damage will put upside pressure on inflation for countries downstream in the Mekong River." "The destruction of the natural ecosystem would also spur a shift in economic activity along the riverbanks away from agriculture and towards manufacturing and hospitality services such as tourism," Fitch said, citing "irreversible damage" to the ecosystem. The result would be that countries downstream would then have to rely more on the world's second largest economy, said Fitch.

China denies report findings

The Chinese government dismissed the report which blamed China for exacerbating one of Southeast Asia's worst droughts. In a reply to CNBC, the foreign ministry said that reduced precipitation, an abnormal monsoon, combined with an extreme El Nino events were the main causes of the drought. The ministry pointed to scientific findings from the Mekong River Commission that showed there was widespread drought across most of regions surrounding the entire river. The statement also said that foreign minister Wang Yi had pledged in February to cooperate with the Lower Mekong countries to ensure the rational and sustainable use of water resources. That shows China's "responsible attitude" as a country in the upper stream, the ministry said, according to a CNBC translation of the remarks in Chinese.

To Beijing, water is considered a sovereign commodity for consumptive use rather than a shared resource to be made available in an equitable manner to downstream stakeholders. Brian Eyler and Courtney Weatherby Stimson Center

At a regular press briefing last week, foreign ministry spokesperson Geng Shuang called the report "groundless" and said it "runs counter to facts," according to an official transcript. "The outflow from Lancang has a very limited impact on the overall volume of the Mekong as runoff in the lower reaches mainly depends on precipitation and contributions from branch rivers," he said. "Therefore there is no reason justifying the claim that China is responsible for the drought in downstream countries." The Mekong River Commission — an inter-governmental body comprising Cambodia, Laos, Thailand and Vietnam — said earlier this month that "more scientific evidence was necessary to conclude that the 2019 drought was in large part caused by water storage in Upper Mekong dams." It also urged for more information sharing among stakeholder countries, including China.

Grand plans for the river

Economic transformation of the river will change power relations around the Mekong. Though increasingly absent in the Asia Pacific region, the U.S. has long challenged China's influence in Southeast Asia. Last week, Secretary of State Mike Pompeo said he was concerned about expressed concerns over the report by Eyes on Earth. Last year, he blamed the blaming drought in the lower Mekong countries on "China's decision to shut off water upstream." At the center of the changing face of the Mekong is China's master plan to open a passage for massive cargo, said Fitch Solutions. That passage — from the Yunnan province through the Mekong countries and into the South China Sea — may potentially include military ships in the future, the research house added.

This screengrab from an aerial video taken on October 28, 2019 shows the Mekong river in Sungkom district in Nong Khai province, more than 300km from the Xayaburi dam. Suchiwa Panya | AFP | Getty Images