The completion of the drainage canal today meant the lake was no longer a time bomb for downstream residents, said Liang Dongchun, a senior officer with the Chengdu Area Command of the Chinese People's Liberation Army (PLA).
Excavation of the channel, which is 8 meter deeps and 5 meters wide, involved more than 1,100 soldiers from the PLA and the Armed Police over the last seven days, he said.
The barrier lake is near the border of Ludian and Qiaojia counties in Yunnan Province, where most of the 600 plus quake deaths were reported.
Nearly 13,000 residents were evacuated. The quake on August 3 was the strongest to hit Yunnan Province in 14 years.
It killed more than 600 people and destroyed 80,000 homes in Ludian County and surrounding areas.