The downstream Tienlun and Kukuan dams were built in 1956 and 1961 respectively,[3] but with their small storage capacities, power output was highly erratic.

"[4] The proposed Tachien Dam site was located at the end of a long valley where the surrounding mountains abruptly closed in to form a narrow slot canyon through which flowed the Dajia River.

[4] Construction at Tachien Dam began in December 1969,[5] with work directed and overseen by French civil engineers André Coyne and Jean Bellier.

[4] Due to the remote site, economic conditions and technical issues, it was a very difficult project for Taiwan at the time, but public support made continued construction possible.

[9] Techi Dam is located at the head of a 514 km2 (198 sq mi) watershed in the upper reaches of the Dajia River.

The auxiliary spillway is located on the reservoir about 300 m (980 ft) southwest of the dam, and consists of a tunnel controlled by five gates with a capacity of 3,400 m3/s (120,070 cu ft/s).

From here, water released from Techi flows through four more hydroelectric plants at Qingshan, Kukuan, Tienlun, and Ma'an dams, which collectively generate about 2.4 billion kWh per year.