Steung Treng Province

Steung Treng Province demonstrates how upstream infrastructure decisions cascade downstream to reshape entire regional ecosystems. Located where four major rivers—the Mekong, Se Kong, Se San, and Srea Pok—intersect, the province functioned as one of Southeast Asia's most productive freshwater confluences. That productivity is now collapsing under hydropower pressure from neighboring Laos.

The Don Sahong Dam, operational since 2020 less than two kilometers from the Cambodian border, represents the proximate cause of Steung Treng's ecological crisis. The 260-megawatt Lao facility disrupts fish migration patterns and alters water flow regimes affecting communities throughout the province. By March 2024, the downstream impacts had become undeniable: unpredictable water levels, declining fish stocks, and—most symbolically—the disappearance of Irrawaddy dolphins from Anlong Chheu Teal since 2022.

The dolphins functioned as keystone indicator species. Their absence signals broader ecosystem dysfunction that threatens livelihoods across the province. Fish catch has declined 13.71% from 2019-2020 with further 7.3% decline in 2021, forcing families who fished for generations to seek work elsewhere. The tourism economy built around dolphin watching has collapsed alongside the ecological base it depended upon.

Cambodia's 2020 moratorium on Mekong mainstream hydropower development until 2030 acknowledges downstream vulnerability but cannot reverse upstream Lao decisions. The province imports electricity from Don Sahong while absorbing its environmental costs—a structural asymmetry in transboundary resource governance.

By 2026, Steung Treng's trajectory depends on factors largely beyond provincial control: Chinese hydropower investment decisions in Laos, Mekong River Commission effectiveness, and whether economic alternatives can absorb displaced fishers. The province exemplifies how border position creates vulnerability to neighbor-state infrastructure decisions.