Streets of Langao County in Shaanxi are flooded after torrential rains.

The flow on the river's upper reaches topped 70,000 cubic meters a second Tuesday -- 20,000 cubic meters more than the flow during the 1998 floods that killed 4,150 people and the highest level since the dam was completed last year.

"The sluice gates have kept the water levels of the dam at 154 meters, enabling the dam to block 4 billion cubic meters of water and preventing severe flooding in the lower reaches," Liu said.

The reservoir has a capacity of 22.15 billion cubic meters for flood control, as water levels could rise to as high as 175 meters, he said.

Flood waters had breached six small reservoirs this year, but timely evacuations prevented any casualties, he said.

Liu also warned authorities to maintain their high alert as the flood season was far from over, and the six to eight typhoons expected to land later this year would bring more rain and exacerbate the situation.

About 287,000 military personnel had been mobilized in anti-flood operations.