Chinese engineers Tuesday blew up a temporary barrier used during construction of the Three Gorges Dam, unleashing the full force of the Yangtze River upon the world's largest hydroelectric project.

The 1.4-mile-long Three Gorges Dam now assumes its role in controlling the deadly floods that have regularly ravaged China's farming heartland.

The 12-second series of blasts sent the 90-foot top section of the temporary cofferdam tumbling into the river, the official Xinhua News Agency reported.

The blast created 6,709,040 cubic feet of concrete fragments, said Li Yong'an, general manager of the Three Gorges project, Xinhua reported.

Officials zapped the water with electric pulses to drive away fish ahead of the blast, it reported. Ultrasonic monitoring showed 90 percent of the fish fled, it said, citing professor Tan Xichang from the Water Biological Engineering Institute.

The Three Gorges Dam was completed last month but its power-generation facilities are not slated to be finished until 2008. It is designed to eventually produce 22.4 million kilowatts of electricity — enough to light up Shanghai on a peak day with power to spare.

Some 191 tons of dynamite blew up the temporary dam, which was 1,900 feet long and 460 feet high, it reported. It was a little more than 100 yards upstream from the Three Gorges Dam.

The water level of the Three Gorges Reservoir will rise from its current height of 440 feet to 510 feet after the summer flood season is over, it reported.

At its full height, the water will to rise to 574 feet, although experts claim that no one really knows how high it will go because of silting and the area's irregular geography.

More than 1.13 million people have been relocated to make way for the dam and its reservoir, and officials are keen to show they are sensitive to the dam's massive environmental impact.