Construction crews finished the main wall of the world's largest hydroelectic dam on Saturday, Xinhua News Agency reported.

Workers pour the last batch of concrete into a section of the Three Gorges Dam on May 19, 2006, as they try to complete construction of the dam structure 10 months ahead of schedule at 2 pm on Saturday. [Xinhua]

After 13 years of construction, the structure of the 185-meter-high (607 feet), 2,309-meter-long (1.4-mile-long) dam across the Yangtze River was completed at around 2 pm on Saturday.

However, the completion of the dam building of the Three Gorges Hydropower Project marks a phased victory, for there are still great deal of works ahead, a senior official from the State Council Three Gorges Project Construction Committee was quoted as saying by the Xinhua News Agency on Saturday.

"The completion of the dam also represents landmark progress in the construction. However, tasks such as building of power houses of the dam, the shiplock and shiplift are still formidable," said Pu Haiqing, deputy director of the committee, when attending a forum held to discuss the final concrete placement of the dam, which is expected to be done shortly.

Pu noted that difficult tasks of the project also include resettlement, prevention of geological disasters and biological construction.

The final 12 of the dam's 26 generators are to be installed over the next two years, with a scheduled completion date in 2008, a year ahead of schedule.

The dam which replaces Brazil's Itaipu Dam as the world's largest hydro-electric and flood-control installation, is often compared to the Great Wall in scale with 28 million cubic metres of concrete poured.

More than 1.13 million people have been relocated to make way for the project, and more than 100 workers reportedly lost their lives in various accidents during construction.

"This is the grandest project the Chinese people have undertaken in thousands of years," said Li Yong'an, general manager of the China Yangtze River Three Gorges Project Development Corporation.

Li said that the project will solve "one of the Chinese people's worst afflictions" the flooding that has ravaged the Yangtze basin for centuries.

A general view of the Three Gorges Dam on Yangtze River. [Newsphoto/file]

Moreover, the dam has been designed to withstand an earthquake measuring 7.0 on the Richter scale and is solid enough to withstand terrorist attacks, according to Cao Guangjing, deputy general manager of the corporation.

China will spend 10 million yuan (US$1.25 million) annually to prevent upstream floating rubbish from piling up at the dam, thereby ensuring that vessels travelling past the dam operate safely.

According to project development corporation officials, the volume of floating rubbish into the Three Gorges Reservoir amounts to 100,000-200,000 cubic metres each year, most of which accumulates in flood seasons.

The government has set aside US$5 billion to build sewage treatment plants around Chongqing and other upstream cities to prevent the river from turning into a cesspool, Cao said.

"Reservoirs worldwide are being more or less beset by rubbish, and the Three Gorges Reservoir is no exception," said Hu Xing'e, a corporate official in charge of reservoir business.

The corporation has spent more than 20 million yuan (US$2.5 million) on building a rubbish-clearing vessel, so far the largest of its kind in China. Floating rubbish that is collected will be sorted out and then be buried or burnt.

Apart from generating clean energy, the landscape-altering mega-project, with a designed water storage capacity of 39.3 billion cubic metres, will also harness flooding and benefit shipping.

Cao Guangjing said his company has taken comprehensive measures to deal with environmental problems.

There have been concerns that the project would affect lives, water quality, cause silt accumulation and maybe even modify local climate slightly in the dam's vicinity.

"The negative effects on the environment caused by industrial sewage and dust produced in the project's construction process are under control," Cao said.

The government has decided to shut down 1,000 polluting enterprises in the upper reaches of the project.

Launched in 1993, the Three Gorges Project, with an estimated investment of 203.9 billion yuan (US$25.2 billion), will have 26 generators with a combined generating capacity of 18.2 million kilowatts.

The generators will churn out 84.7 billion kilowatt-hours a year when the final touches are completed in 2008, officials said.