Chengdu, China ? Water churned through a drainage channel and engulfed empty towns Tuesday after Chinese soldiers blasted away the debris that kept an earthquake-formed lake threatening more than a million people downstream.

Sichuan province’s Communist Party chief, Liu Qibao, declared “decisive victory” after more than half the

66 billion gallons of water drained off by early evening, easing pressure on a dam formed when the quake triggered a landslide of mud, rocks and other debris, the official Xinhua News Agency reported.

More than 250,000 people had already moved to high ground because of concerns that the barrier holding back Tangjiashan lake could break. About 1.3 million people live downstream.

Fearful that the possible deluge would endanger refugees and residents, China ordered soldiers and police to work nonstop for four days to dig a diversion channel and blast away the debris with dynamite, bazookas and recoilless guns.

In the narrow valley town of Beichuan, which was flattened in the quake and has been evacuated, a rush of murky brown grey water from the Tangjiashan lake washed away a metal pedestrian bridge spanning a river on Tuesday and scraped away at river banks. But today the water appeared to have subsided and was calm.

The swirl of muddy water roaring past towns and villages swept along trees, barrels, television sets, refrigerators “and the occasional dead bodies of quake victims,” Xinhua reported.

Towns downstream remained on alert for possible flooding in case the water breached unstable banks.

“The best situation is to completely clear out the water in the Tangjiashan lake before the flood season. The water level is likely to linger around 720 meters (2,300 feet) for a period of time,” said Water Resources Minister Chen Lei, according to Xinhua.

Earlier, China’s security czar stressed the need to maintain order amid a struggle to shelter millions left homeless by the quake and scattered protests over alleged corruption linked to shoddy school construction.

Zhou Yongkang demanded police and legal staff “solve disputes and help maintain social stability,” the Communist Party’s official newspaper, The People’s Daily, said in a front-page report Tuesday.

While there have been no reports of major unrest, refugees have rioted on at least one occasion over misused aid. Parents of children killed in schools have demanded officials answer for alleged corruption in the buildings’ construction.

At least 15 Sichuan officials have also been removed from their posts for mishandling relief work. Another 13 have been given other forms of administrative punishment.