Cambodia’s Tonle Sap Lake Under Threat

In July the Mekong River, the precious lifeline for four Southeast Asian countries and China’s Yunnan Province, fell to its lowest levels in 100 years, the victim of increasing climate change, agricultural runoff and a plethora of upstream dams that threaten its existence.

The rains have finally come, but the worst casualties of a tamed Mekong are due for Cambodia’s 125-km-long Tonle Sap Lake, where life above and below the water relies on the flood pulse of the river. Now more than ever, experts are wondering how much pulse is left.

“Traditionally the annual reversal of the Tonle Sap Lake happens in late July or early August, but with this year’s drought, the reversal will come late or perhaps not at all,” said Brian Eyler, the Energy, Water, Sustainability Program Director for the Washington, DC-based Stimson Center. When the Mekong floods, it reverses the flow of the river and puts 11,000 to 16,000 sq km underwater, producing one of the most intense seasonal changes in the world. The reversal transforms the map from Phnom Penh to Siem Reap and supports globally important colonies of endangered waterbirds and giant snakehead fish alike — as well as the millions who rely on its bounty.

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