The experimental dam of the TGP——Gezhou Dam Project is located at the lower end of the Three Gorges in the suburb of Yichang City, 38 km downstream of the TGP.

The construction of the Gezhou Dam Project started on December 30, 1970 and ended on December 10,1988. The Dam is 2,606.5 meters high, with a total storage capacity of 1.58 billion m3 and a maximum flood discharging capability of 110,000 m3/s. The two hydro-electric plants have 21 generating units with a total installed capacity of 2.715 million kw and annual output of 15.7 billion kwh, which is transmitted to Shanghai, He'nan, Hu'nan, Wuhan, etc. The annual one-way shipping capacity of the navigation facilities is 50 million tons and its total investment was 4.848 billion yuan ($0.557 billion). The Gezhou Dam Hydropower Plant generated a total of 140 billion kwh of electricity between 1981, when the first generating unit went into operation, and May, 1991, creating a total output value of 12 billion yuan ($1.38 billion).

The Gezhou Dam Project is a cascade which regulates the tailwater flow from the TGP and improves the navigation conditions between the two dams. After completion of the TGP, the annual guaranteed output of electricity from the Gezhou Dam Hydro-power Plant will increase by about 430,000 kw. Therefore the two projects are considered as twins through thick and thin.