‘Barrier lake’ in China threatens up to 1.2 million in earthquake zone

The Chinese government warned today that as many 1.2 million residents may have to be evacuated because they could be inundated by a swelling “barrier lake” formed by the May 12 earthquake.

The notice was issued hours after a Russian helicopter transported heavy machines over mountains in the northern part of Sichuan province, and hundreds of Chinese soldiers carried in 10 tons of dynamite, to contend with the barrier lake at Tangjiashan, about 2 miles upstream from the town of Beichuan.

The afternoon announcement, broadcast on local television, made for another jittery day in Mianyang, a municipality of 5 million people that includes some of the hardest-hit areas of the earthquake, including Beichuan. Hopes of normality returning to the region had already been set back by Sunday’s magnitude 6 aftershock, centered north of here, which killed eight people and destroyed 270,000 houses.

Monday’s flood warning prompted some people to haul their tents to higher ground and others to flee Mianyang altogether.

“Some of my friends are leaving town; they want to go as far away as possible,” said Liu Decai, 35, a taxi driver who drove home after the broadcast to pack up jewelry and other valuables.

China’s central government continued to stress the importance of resettling victims, restoring production and rebuilding devastated areas. Some 5 million people were left homeless by the quake, which has claimed more than 65,000 lives, with 23,150 people still missing.

In addition, more than 306,000 were injured by the quake. As of Sunday, 5,914 patients were moved from overloaded hospitals in Sichuan province to medical centers elsewhere in the country, with another 2,100 still to be transferred, said the Ministry of Health.

Even as officials shift the focus from rescue to caring for survivors and preventing epidemics, they are trying to avert a potential disaster from some of the 35 barrier lakes that formed when rivers were plugged by landslides triggered by the quake. Geologists worry that aftershocks or heavy rains could burst the barriers.

One of the largest and most threatening is the one at Tangjiashan, which now holds more than 4.5 billion cubic feet of water and, as of today, was only 85 feet below the lowest part of the barrier, according to the official New China News Agency.

Tonight, about 600 engineers and soldiers had gathered at the blockage of the lake and were planning to work through the night to remove debris from a sluice, the agency said. Soldiers also might set off small-scale blasts to help drain the water.

Tens of thousands of people already have been evacuated. The warning issued today said that in the worst-case scenario, in which the entire barrier collapsed, about 1.2 million people would be ordered to move to higher ground, including some in central Mianyang.

“Right now, there is not panic in the tent city,” said Mianyang spokesman Wang Xiaogang, referring to the thousands of people living in tents at Jiuzhou Stadium.

But many others in downtown Mianyang weren’t taking any chances.

The Fucheng District Christian Church in Mianyang, with more than 4,000 members, called off all activities, including serving lunch to those at the stadium, to prepare for the evacuation, said the Rev. Ma Jin.

“We are now transferring some important documents to high ground, so if a flood comes, they won’t be destroyed,” the pastor said. “And of course I will pray too.”

 don.lee@latimes.com

Cao Jun of the Times’ Shanghai bureau contributed to this report.