The principal part of the Ertan Hydropower Project commenced on September 14th, 1991. Due to huge bill of quantities and sophisticated engineering technology, main civil works were procured through international competitive bidding. The project with its dam and underground powerhouse undertaken by over ten contractors is the first of its kind in China, which is developed under international joint efforts.
Total area flooded by the reservoir is 24,841mu(Chinese unit of area), most of which was occupied by the counties of Miyi and Yanbian under the administration of Panzhihua. Also Yanyan, Dechang and Xichang under Liangshan Prefecture are affected. Until 1995, more than 29,372 migrants had been resettled and houses of 960,000m2 had been demolished. Moreover, the Yanbian County town as a whole was relocated.
In September 1987, preparatory works totaling 46 engineering items started, which include 3 bridges, nine highways, 7 power supply facilities, 4 residential zones, 13 items of diversion tunnels, traffic tunnel as well as communication and seismic monitoring works.
At 10 AM, May 1st,1998 when the gate of the temporary diversion tunnel was hauled down, the Yalung River was intercepted and water began to accumulate. On August 18 and November 16, two sets of 550MW generator units were brought into operation successively. The moment came when the Yalung River, having been silently asleep for thousands of years, was awakened to speak out her aspiration for giving forth light to human.
In July-September, there were exceptionally strong storms in the reach of the Yalung River , which resulted in frequent and heavy floods. Five peaks at a rate of 8,000m3/s above occurred consecutively. The largest was the third one on August 10 at a rate of 10,200 m3/s, which is documented as the second largest peak in the history. For the first time the Ertan reservoir, with its dam and flood relief facilities uncompleted, was used to regulate flood. With flood reduction by 34%(maximum reduction was 57%), and total flood retention of 3.424 billion cubic meters during five floods, the project played an important role in relieving flood for the middle and lower reach of the Changjiang river. In December, the Ertan Hydropower Development Company was awarded the title of ’National Outstanding Collectives for Flood Control in 1998’ by state authorities.