Managing to stem the rise of water levels in Tangjiashan lake has become a priority for the government as it tries to prevent further disaster.
Experts warn that the lake could burst at any time, flooding the homes of more than one million people. About 250,000 people have already been evacuated from the area since the quake.
According to state media, the soldiers have managed to make the run-off channel wider and deeper, helping to reduce the water level in the lake, and are now working on a second drainage channel.
But rainfall and further landslides caused by a 4.8 magnitude aftershock on Sunday afternoon have made the situation harder still.
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