BEIJING, July 8 — The world’s largest hydroelectric power station, the Three Gorges Dam on China’s Yangtze River, continues to operate with a mix of staggering output and persistent environmental trade-offs that researchers and engineers are still working to understand. The dam’s scale is difficult to grasp. Stretching 2,335 meters across the river and standing 181 meters tall, it houses 32 main turbines that generate roughly 100 billion kilowatt-hours of electricity each year.
That power flows to central and eastern China, feeding industrial and residential demand across a vast region. The project, built by the state-owned China Yangtze Power Company, cost an estimated $28 billion.
Construction began in 1994 and wrapped up in 2012.
Flood control and human cost
One of the dam’s primary functions is flood management. The reservoir it created, which runs 660 kilometers upstream, helps regulate the Yangtze’s flow. Officials say the dam protects 15 million people and 1.5 million hectares of farmland from seasonal flooding.
That is a significant benefit in a basin prone to devastating inundation. But the scale of displacement was enormous.
The reservoir flooded 13 cities, 140 towns, and 1,350 villages. An estimated 1.3 million people were relocated to make way for the rising waters. The project was approved by the National People’s Congress in 1992, after years of debate.
Environmental consequences
The ecological costs are becoming clearer with time. Sedimentation behind the dam is a well-documented challenge. As the river slows in the reservoir, silt settles to the bottom, gradually reducing storage capacity and potentially affecting the dam’s long-term operations.
Engineers monitor this closely, but it remains an unresolved issue. Fish populations have suffered.
The Chinese sturgeon, a species that migrates up the Yangtze to spawn, has seen steep declines. The dam blocks migration routes and alters the river’s flow patterns that the fish rely on. Conservation efforts are underway, but the pressure on the species is intense.
Landslide risk along the reservoir’s banks has also increased. The constant fluctuation of water levels — rising and falling with power generation and flood control — destabilises slopes.
Local authorities monitor dozens of potential slide zones, but the risk is a permanent feature of the reservoir’s operation.
What to watch next
The Three Gorges Dam remains a case study in trade-offs. It supplies vast amounts of clean electricity without burning coal, and its flood control saves lives and farmland every year. Yet the environmental costs — displaced communities, altered ecosystems, sedimentation, landslide hazards — are real and ongoing.
Researchers continue to study how the dam reshapes the Yangtze’s ecology, and whether mitigation measures can keep pace with the changes. For now, the dam stands as a monument to human engineering, with all the complexity that implies.
