From February to April each year, Kam Thon spends most of her days knee-deep in the waters of the Mekong River by her village in northern Thailand, gathering river weed to sell and cook at home.
Kam Thon and other women who live by the Mekong have been collecting river weed, or khai, for decades, but their harvest has fallen since China built nearly a dozen dams upstream.
The dams have altered the flow of water and block much of the sediment that is vital for khai and rice cultivation, researchers say.
"Generally, the water is clear and the level is lower in the dry season, and we can easily wade in and harvest khai.
"But now, the water level is higher during dry season, which makes it more difficult," said Kam Thon, 48, who sells khai at a local market.
"We need to spend more time collecting khai, and there is also less khai, which has affected our income," Kam Thon said, as she rolled handfuls of the stringy green weed into balls and placed them in a nylon bag slung on her shoulder.
Kam Thon, who lives in Chiang Khong by the Thai-Laotian border, said she made only about a third of what she used to earn when the Mekong's waters ran low in the dry season and the khai was plentiful. Her husband's fish catch had also fallen, she said.
Stretching from the Tibetan Plateau to the South China Sea for 4,350km, the Mekong is a farming and fishing lifeline for tens of millions across China, Laos, Myanmar, Thailand, Cambodia and Vietnam.
But with China building more dams to generate hydropower, fears are growing over the unseasonal flooding and droughts they cause, and for the future of Southeast Asia's longest river, which is now being shaped by powerful state-backed corporations.
Local communities and campaigners say their concerns and complaints are being ignored in the push for clean energy.
"The upstream dams are affecting fish catch, rice cultivation and river weed, a major source of income for women and the elderly," said Pianporn Deetes, campaign director for Thailand and Myanmar at Rivers International, an advocacy group.
"When the river is turned into just being a source of hydropower, it affects the lives and livelihoods of millions of people. It's about their food, their tradition and custom, their way of life."
Eager to boost its renewable energy capacity and reduce its reliance on coal, China has built nearly a dozen dams, including five mega-dams each more than 100 metres tall, since 1995 on the Mekong, which it calls the Lancang.
China has also built at least 95 hydroelectric dams on tributaries flowing into the Mekong. Dozens more are planned in China, which is also financing others in the Lower Mekong Basin.
Energy from the hydropower dams in the Upper Mekong River Basin, comprising the Tibetan Plateau and the Lancang Basin in China and Myanmar, valued at about US$4 billion annually by the Mekong River Commission (MRC), an intergovernmental body of the Lower Basin nations of Thailand, Cambodia, Laos and Vietnam.
Various studies estimate that nearly all of the river's sediment load will be trapped upstream if all dams proposed in the Mekong Basin are developed, which could impact the cultivation of rice, a major food source for millions in the region.
In addition, the decline of the Mekong's fisheries — as the dams block fish migration and alter water flow — is predicted by MRC to cost nearly US$23 billion by 2040, with the loss of forests, wetlands, and mangroves valued at up to US$145 billion.
Communities living closest to the dams were the hardest hit, including in Chiang Khong, said Brian Eyler, who directs the energy, water and sustainability programme at the United States-based Stimson Center, which monitors the Mekong dams.
Releases from the reservoirs for hydropower production during the dry season can "double or even triple what natural flow would deliver", while wet season restrictions can reduce water flow by more than half, he said.
"This is causing fishing villages along the Thai-Laotian border to become ghost towns."
The writer is from the Reuters news agency
The views expressed in this article are the author's own and do not necessarily reflect those of the New Straits Times