The Keelung River Yuanshantze Flood Diversion Plan can be traced back to 1963 and 1970. It was not carried out since the goal at those times was to mitigate floods of Danshuei River. The torrential rains brought upon by Lynn typhoon in October, 1987, caused the flooding of expansive areas in Taipei City.

The planning unit of the former Taiwan Provincial Water Resources Agency re-examined the possibility of Yuansantze weir construction for flood diversion. Later, the central government actively advanced the Keelung River flood mitigation project; through the instruction of the Executive Yuan, the Ministry of Economic Affairs integrated various responsible units to carry out the “Keelung River Overall Improvement Project Planning,?and the former Water Resources Bureau, MOEA completed ?Overall Report (draft) of the Keelung River Overall Improvement Project Planning?and “Keelung River Overall Flood Mitigation Plan?and proposed to the Executive Yuan.

The Executive Yuan pointed out: “consider the feasibility of giving priority to advance the Yuansantze Flood Diversion Project;?and after the briefing meeting of “Keelong River Overall Improvement Project?in November, 2000, it pointed out the Yuansantze flood diversion plan; and in 2001, it sanctioned the Yuansantze flood diversion project.The Yuansantze Flood Diversion Project is located in the Rueifang township of Taipei County.

The start point of the project is located by the Rueigansin Village of Rueifang township by the upstream of the Keelung River main stream. The floodway goes northeast direction, diverting the flood of Keelung River’s upstream depression areas into the East China Sea by way of tunnels. Diagram on the right shows the location of the Yuansantze flood diversion construction.