Environmental sanitation workers from southwest China's Chongqing Municipality have collected 78,000 tonnes of garbage from the Yangtze River near the Three Gorges Dam, ensuring the dam's safe and effective operation after its water level was raised.

More than 68,000 workers in nearly 21,000 boats retrieved the garbage.

In late October, the water level in the dam was lifted to its designed maximum of 175 meters, allowing the dam to play its full flood control, power generation, navigation and water supply roles, said Wang Yuankai, a Chongqing municipal work administrator.

Raising the dam's water level increased the surface area of water in the dam. It also increased garbage collectors' workload, with about 60 percent more garbage appearing.

The cleanup operation helped ensure the water quality of the dam and its navigability.

The Three Gorges Dam is the world's largest water-control and hydropower project.