Muddy lake water from a dangerously unstable "quake lake" rushed into the devastated Chinese town of Beichuan on Tuesday, covering about a third of the ruins, after soldiers used explosives to widen a sluice.
Brown water, clumps of trees and occasional vehicles were moving quickly into low-lying areas of the town, washing away remains of corpses, family mementoes and valuables left under the rubble.
Wang Guiru, 43, whose wife died in the quake alongside his father and mother-in-law, said he had hoped eventually to look for their remains.
"Now I guess we can never go back," he said stoically. "This is fate. We have to learn to face up to realities."
The water level at the Tangjiashan quake lake, formed by China's most devastating earthquake in decades, dropped by nearly eight metres (26 ft) in three hours on Tuesday, Xinhua news agency said.
The Tangjiashan lake, the largest of the more than 30 created when landslides triggered by the quake blocked the flow of rivers, has so far prompted the evacuation of more than 250,000 residents downstream in case the mud-and-rock dam bursts.
SOLDIERS EVACUATED
Helicopters were evacuating remaining soldiers and experts from the top of the dam, which was no longer safe with cracks appearing as the flow of water accelerated by more than tenfold, Xinhua said, adding some mountains near the lake had started crumbling.
It attributed the abrupt increase in water discharged from the lake to "two massive blasts on Monday evening which broke through the bottleneck" in a sluice opened by soldiers.
The torrents had further widened and lowered the sluice, Xinhua said.
"The flow downstream has increased dramatically, but the dam hasn't collapsed," Zhou Hua, spokesman for the lake relief operation, told Reuters. "The channel has widened but this isn't a collapse.
"... So far everything is happening within expectations. As things are, we don't expect to have to evacuate any more."
The waters would reach the densely populated city of Mianyang, which was ready to activate a "red alarm" to evacuate but had advised residents not to panic, Xinhua said.
Mianyang hosts tens of thousands of quake refugees from Beichuan, where more than 15,000 people died in the May 12 tremor. Road blocks kept traffic away from nearby Jiangyou, but it was not clear if the whole town was cut off.
The flow of water would only be "relatively safe" when the water level behind the Tangjiashan dam fell another 15 metres to about 720 metres above sea level, Xinhua quoted experts as saying.
Beichuan was so thoroughly ravaged that authorities sealed it off after the tremor and planned to rebuild it elsewhere.
The flooding brought more heartache to people displaced by the earthquake in which nearly 87,000 people either died or are missing. Many said valuables were now lost for good.
"It began flooding early this morning," said shop assistant Zhu Yunhui, 37, who lost loved ones in the quake and said she had kept many tens of thousands of yuan in her home. "Now we can never go back. This is heartbreaking."