BEIJING, China (CNN) -- On Tuesday, a huge volume of water surged from a lake created by China's massive earthquake, plunging downstream to where hundreds of thousands of people were bracing themselves for further disaster.
Engineers racing to drain Tangjiashan lake -- where floodwaters behind a landslide are threatening to burst through the wall of rubble to smash into low-lying towns -- reported water was draining quickly from man-made channels.
The official Xinhua news agency reported late Tuesday that a crest of flood water, carrying with it trees, TVs, refrigerators and the bodies of earthquake victims, had surged safely past the city of Mianyang, where up to 400,000 people remain despite the evacuation of another 250,000.
Officials in the badly hit Sichuan province said it they were hoping that limited flooding caused by the emergency draining of Tangjiashan lake would prevent potentially disastrous inundations that could occure if the waters were allowed to build up behind the dam.
Three spillways have been created by engineers to boost outflow from the lake to ensure it exceeds the amount of water coming in, according to Xinhua.
But, although the lake's level was dropping, there were still fears that the rapid movement of water could trigger the dam's collapse -- causing a much bigger tidal wave to swell downstream.
If the dam were to break, it could threaten areas downstream that are home to more than 1.3 million people.
State broadcaster CCTV said 40 percent of homes in the down rivertown of Qingyi were at risk while Mianyang, where residents have been practicing evacuation drills, was on alert, AP reported.
Meanwhile, officials found the crash site of a Chinese military helicopter that went down late last month in the mountains of southwestern China, killing 19 people, state-run media reported.
The transport was carrying a crew of five along with 14 injured residents from Sichuan province on May 31 when it crashed in "fog and turbulence" near Yingxiu in Wenchuan County, a military source told the Xinhua news agency.
The flight was a part of rescue efforts following the May 12 earthquake that devastated much of the region.
More than 69,000 people died in the May 12 quake, but more than 17,000 remain missing, according to the official government toll.