Three Gorges Dam under construction (March 13, 2006)

China is celebrating the completion of the construction of the Three Gorges Dam, the world's largest.  With the last load of cement poured, the dam is 2,300 meters long and, when filled, the reservoir will be 656 kilometers long.  The project that has been a dream of Chinese leaders since the early 20th century.

It is 185 meters high and able to generate enough electricity to power Belgium. Admirers have called it an engineering wonder of the world.

The Three Gorges Dam, which stretches across the Yangtze River in Central China's Hubei Province, has been completed nine months ahead of schedule, after 13 years of work, and an expenditure of $25 billion.

It was Chinese Nationalist leader Sun Yat-Sen who, in 1919, first conceived the idea of a giant dam to control the Yangtze's devastating annual floods.

In recent years, the push to build a dam has been driven by more modern economic considerations. China's rapidly growing economy is prone to blackouts, and desperately needs more power.

The government says the dam will go some way toward solving the country's energy shortage.

Environmentalists, however, have suggested that the reservoir that will be created could become a giant cesspool, as untreated waste from nearby cities or chemicals from factories build up.

Patricia Adams, an executive director of environmental group Probe International, calls the project a mistake.

"The Three Gorges Dam is bad because of the cost of building it. The financial, the environmental, and the social effects of the dam very much outweigh the benefits," she said.

More than one million people were forcibly relocated during the construction as rising water levels slowly engulfed low-lying towns, including some historic sites.

The structure has been built close to a geological fault line, and critics suggest that pressure from the reservoir could trigger landslides, or even an earthquake. 

The Chinese leadership was determined, however, and construction went ahead even as criticisms were voiced.  There are now only a handful of rivers left in China without a dam.