The water level at the Three Gorges Dam, the world's largest water control and hydropower project, reached its designed highest mark Tuesday.

Photo taken on Oct. 26, 2010 shows the Three Gorges Dam and the reservoir (on the right side of the dam) after the water level reached 175 meters, its designed maximum, at 9 a.m. Tuesday in Yichang, central China's Hubei Province.  [Xinhua]

The water level hit 175 meters at 9 a.m. Tuesday, said Cao Guangjing, chairman of the China Three Gorges Project Corporation (CTGPC), the developer of the project.

Raising water for the first time to 175 meters is "a milestone in the construction of the gigantic reservoir," Cao said, adding it will enable the project to fulfill its functions of flood control, power generation, navigation and water diversion.

The new level does not mean complete success for the project. It does, however, allow for testing of various public concerns and doubts raised since the very beginning, such as the function of many key equipment, geological disasters, water quality, and sediment situation, Cao said.

The 185-meter-deep reservoir, built on the upper middle-reaches of the Yangtze, China's longest river, began to store water in 2003.

It was the third attempt to raise the water level in the dam to full capacity since 2008.

In 2008, on the first attempt, the level was raised to 172.8 meters before geological hazards prevented it being raised further.

On the second attempt, in 2009, because of droughts downstream, the level could only be raised to 171.43 meters.

In September, the dam started holding more water back and discharging less. It reached full capacity after 47 days.

The water level-raising process allows experts to observe, research and validate the dam's original design, according to Cao.

So far, monitoring shows the dam is operating smoothly.

The water level will be maintained at 175 meters for about two months for surveillance and then be allowed to drop. In the future, the water level will be kept at between 145 meters and 175 meters, depending on flood control needs.