Chinese rescue workers line up to leave their work area for safer ground today in Sichuan province. Crews were preparing to use explosives and construction equipment to bring down unsafe buildings. Chinese authorities said that 67,183 people have been confirmed dead and 20,790 are sill missing following the May 12 earthquake.

MIANYANG, China — Chinese officials rushed today to evacuate another 80,000 people in the path of potential floodwaters building up behind a quake-spawned dam as soldiers carved a channel to try to drain away the threat.

The official Xinhua News Agency reported emergency workers would try to complete the evacuation by midnight today, taking the number of people moved out of the threatened valley to almost 160,000.

The Tangjiashan lake in northern Sichuan province, formed when a massive landslide blocked a river, is one of dozens of fragile dams created during the earthquake that pose a new destructive threat in the disaster zone.

Soldiers hauled explosives through the mountains to reach the area, and the official Chinese Daily said today on its Web site they were "preparing to dynamite the barrier."

State television showed live footage of heavy earthmoving equipment being used to carve out a 200-yard channel to drain the water.

"We are prepared to get rid of the trees by chopping and explosion. After that, the second batch of equipment will be moved in," Liu Ning, chief engineer at the Ministry of Water Resources, was quoted as saying on CCTV.

The lake is swelling behind a landslide near Beichuan, one of the towns hit hardest by the May 12 tremor that devastated Sichuan. The number of deaths has climbed further toward an expected toll of 80,000 or more. The Cabinet said today that 67,183 people were confirmed killed — up by about 2,000 from a day earlier — and 20,790 were sill missing.

Also today, health officials said higher-than-normal rates of stomach pains and fever had been reported among the millions of quake survivors, but that no major disease outbreaks had occurred.

Some 5 million people were left homeless by the quake, and many of them are living in tents or makeshift communities that are clustered throughout the disaster zone.

Qi Xiaoqiu, the director of disease prevention at the health ministry, said the quake had knocked out much of the region's health infrastructure, but 12 field hospitals had been erected and tens of thousands of health professionals were working in the zone.

"With the destruction by the quake, the living and sanitary conditions have worsened for the local population," Qi told reporters in Beijing. "Their physical conditions are weakened (and they are) more vulnerable to disease."

Diseases such as tuberculosis and hepatitis remained a threat, but so far no outbreaks had been reported, he said.

About 1,800 soldiers clambered up mountain paths to reach Tangjiashan with plans to dig and blast their way through the debris and drain the water, Xinhua reported.