Geographic Location
The Shihmen Reservoir is located on the mid-stream reach of the Tahan River. It is administratively within the territories of Daxi, Lungtan and Fuxing Townships of Taoyuan County, and of Guanxi Township of Hsinchu County. Shihmen in Chinese is meant stone gate. The reservoir site has been so named because at the mouth of the river a pair of face-to-face huge rocks looked like a stone gate are situated respectively on either bank of the river.

Five Purposes for Reservoir Operation
This reservoir started impounding water at the time when its diversion tunnels were completed with the outlet structures and closed in May 1963. Up to date, the reservoir has been operated for over 40 years to serve the 5 functions as originally planned; i.e., irrigation, hydropower generation, public water supply, flood mitigation and tourism. Over the years the Reservoir therefore has significantly contributed to agricultural production, industrial development, enhancement of living standards, increase of employment opportunities, and alleviation of flood and drought disasters in the northern Taiwan region.

Basic Data of Reservoir
Type of dam: rolled rock-fills
Height of dam: 133 m
Crest length of dam: 360 m
Catchment’s area: 763.4 km2
Total storage: 309 million m3
Max flood discharge over spillways: 1,900 cms each unit x 6 units
Max flood discharge of diversion tunnels: 1,200 cms each unit x 2 units
Supply of water demands：
Agricultural water for the Shihmen and Taoyuan Irrigation Associations’ irrigation areas: about 37,000 ha in total.
Public water supply for the Taoyuan and Taipei Counties’ areas.