Emergency workers are aiming to evacuate another 80,000 people from the area downstream of a swelling earthquake-induced lake by midnight on Tuesday.

Altogether 158,000 people will have to move from their homes if Tangjiashan Lake under an emergency plan drawn up for the contingency of a third of the lake volume bursting its banks.

The lake was formed by landslides that blocked a river known as the Jianjiang after the May 12 quake, bursts its banks, according to Mianyang City Quake Control and Relief Headquarters.

The people being affected are from 169 communities in 33 townships of Mianyang, one of the areas worst hit by the May 12 quake, under one of three emergency plans .

So far, more than 70,000 people in Mianyang City have been relocated.

Two other plans require the relocation of 1.2 million people if the half of the lake volume is released or 1.3 million if the barrier of the quake lake fully opens.

The evacuation is necessary because the water level in the quake lake has kept rising and the water diversion channel won't be ready in place until June 5, experts with Mianyang City Quake Control and Relief Headquarters said on Tuesday.

Tangjiashan, one of 35 such lakes, is inaccessible by road and can only be reached by foot or air.

It was holding 130 million cubic meters of water, said Liu Ning, Ministry of Water Resources chief engineer, who is at Tangjiashan to oversee the diversion work. Its water level was 725.3 meters on Monday, only 26 meters below the lowest part of the barrier.

The water level in the lake rose by 1.79 meters on Tuesday, comparing 1.6 meters on Monday, according to the headquarters.

Li Huzhang, an engineer with the armed police, said three emergency plans had been drawn up to dig the sluice. At least 50,000 cubic meters of debris would have to be removed. Rescuers, however, were aiming to remove 100,000 cubic meters of debris if the weather allowed.

As of 9 p.m. on Monday, around 600 engineers and soldiers had gathered at the site, some 3.2 km away from the seat of Beichuan County, the area worst hit in the devastating May 12 quake, and were working in shifts through the night, with the aid of 20 building equipment.

The earthquake measuring eight on the Richter scale and center in Wenchuan county, struck Sichuan Province on May 12. It was felt across the country.

It has claimed at least 67,183 lives and left 361,822 people injured, and 20,790 missing as of midday Tuesday, according to the Information Office of the State Council.

(Xinhua News Agency May 27, 2008)