Three Gorges Dam. Landsat satellite image of the Yangtze River in Sandouping, Yichang, China, in 2004, during construction of the Three Gorges Dam (right). At this stage the reservoir (left of the dam) was beginning to fill. The Dam is the largest hydroelectric power generator in the world. Construction started in December 1994 and was completed in 2006. The Dam is expected to be fully operational by 2011. At its fullest the reservoir covers over 600 square kilometres. Nearly two million people were displaced to make way for the rising water levels behind the dam.