Picture taken at 9 a.m. on June 10, 2008 from a military helicopter shows the drainage of the Tangjiashan quake lake in southewest China's Sichuan Province. Drainage of the quake lake through a manmade spillway speeded up to 1,760 cubic meters per second at 9:30 am on Tuesday, whereas water flow in the lower reaches of the lake, in Beichuan County, reached 2,240 cubic meters per second. (Xinhua/Li Gang)

 A senior official said here on Tuesday that a "decisive victory" has been achieved in the drainage of China's main quake lake Tangjiashan.

    Liu Qibao, Communist Party chief of the southwestern Sichuan Province, made the remarks after about half of the quake's water have been discharged and the number of people under threat has dropped from 1.3 million to less than 50,000.

    A man-made sluice channel on the lake's dam was scoured to between 720 and 721 meters above the sea level at 5 p.m., which means the influx and outflow of the lake reached a balance, according to the Tangjiashan Lake emergency rescue headquarters.

    The lake's dam was also more secure with the sluice channel being lowered, the headquarters said.

    The man-made spillway started to drain from the lake on Saturday morning and military engineers used recoilless guns, bazookas and dynamites on Sunday and Monday to blast boulders and other obstructions in the channel and speed up the outflow.

    As a result of two massive blasts on Monday evening which broke through the "bottleneck" in the spillway, the water outflow speeded up drastically on Tuesday compared with 80 cubic meters on Monday night.

    The Tangjiashan quake lake, formed after quake-triggered landslides from the Tangjiashan Mountain, blocked the Tongkou River running through Beichuan County, one of the worst-hit areas in the May 12 quake.

Picture taken at 9 a.m. of June 10, 2008 from a military helicopter shows the water gushed out of the Tangjiashan quake lake in southewest China's Sichuan Province. Drainage of the quake lake through a manmade spillway speeded up to 1,760 cubic meters per second at 9:30 am on Tuesday, whereas water flow in the lower reaches of the lake, in Beichuan County, reached 2,240 cubic meters per second. (Xinhua/Li Gang)

Picture taken on June 10, 2008 from a military helicopter shows flood water flowing past Beichuan County in southewest China's Sichuan Province. Drainage of the Tangjiashan quake lake through a manmade spillway speeded up to 1,760 cubic meters per second at 9:30 am on Tuesday, whereas water flow in the lower reaches of the lake, in Beichuan County, reached 2,240 cubic meters per second. (Xinhua/Li Gang)