China has to spend 10 million yuan (1.3 million U.S. dollars) annually to prevent upstream garbage runoffs from piling up at the mammoth Three Gorges Dam, so as to ensure safe operation of the world's largest water control project.

According to officials with the China Yangtze Three Gorges Project Development Corporation, the inflowing garbage runoffs for the Three Gorges reservoir amount to 100,000-200,000 cubic meters annually, most of which accumulate in flooding seasons.

The corporation has spent more than 20 million yuan (2.5 million U.S.dollars) on building a runoff-clearing vessel, so far the largest of its kind in China, the officials said.

Launched in 1993,the 180-billion-yuan (22.5 billion U.S.dollars) Three Gorges project, including a 185-meter-high dam and 26 generators on both banks of the Yangtze River, is being built in three phases on the middle reach of the Yangtze.

It is scheduled for completion in 2009 and by then, it will be able to generate 84. 7 billion kwh of electricity a year. The project will also function to harness flooding and benefit shipping.