The 511ft-high Zipingpu dam holds 315 million tonnes of water and lies just 550 yards from the fault line, and three miles from the epicentre, of the Sichuan earthquake.
Now scientists in China and the United States believe the weight of water, and the effect of it penetrating into the rock, could have affected the pressure on the fault line underneath, possibly unleashing a chain of ruptures that led to the quake.
Fan Xiao, the chief engineer of the Sichuan Geology and Mineral Bureau in Chengdu, said it was "very likely" that the construction and filling of the reservoir in 2004 had led to the disaster.
"There have been many cases in which a water reservoir has triggered an earthquake," said Mr Fan. "This earthquake was very unusual for this area.
There have been no seismic activities greater than a magnitude seven quake along this particular seismic belt before."
The 7.9 magnitude quake struck last May and left more than five million people homeless. It remains a raw and emotional topic for most Chinese, and the government has been quick to quash any suggestion that Zipingpu may have been responsible for the catastrophe. Researchers have been denied access to seismological and geological data to examine the earthquake further.
Zipingpu is only one of nearly 400 hydroelectric dams in the earthquake zone. Mr Fan said the government had been warned of the danger of building so many large-scale projec