The regulations of formal organization for this bureau were approved in Jan. 1948. Interior business system was divided into four units: Construction Section, General Affairs Section, Material Section, and Accounting Section. Until July, 1951, a new Personnel Manager was increased to be in charge of personnel business affairs.
Later on, the regulations of organization were amended several times continuously in 1956, 1959, 1971, 1976, 1981, 1983, 1990, 1993, and 1994. In Jan. 1998, the name of this unit was reorganized formally as River Basin Management Bureau, and there were four sections and four offices programmed. Our bureau was reorganized to belong to the control of Ministry of Economic Affairs in July 1999. However, on Mar. 28, 2002, in order to coordinate with the reorganization of Water Resources Section ,our bureau was reorganized and renamed to be The Fifth River Basin Management Bureau-Water Resources Agency-Ministry of Economic Affairs. In our bureau, there were four sections and four offices established: Planning Section, Construction Section, Management Section, Property Management Section, Secretariat, Accounting Office, Personnel Office, and Civil Service Ethics Office.
In the 17th year of the Showa era (1942), this agency was originally established as the "Beigang River Flood Control Works Office" to manage the rectification of the Beigang River.
After the recovery of Taiwan, on August 15, 1945, it was temporarily placed under the "Public Works Bureau, Eighth Engineering Office, Mining and Public Works Department, Taiwan Provincial Government," handling flood control, engineering, and water administration for the Beigang, Bajhang, and Zengwen Rivers.
In April 1947, with the establishment of the Taiwan Provincial Government, the Water Resources Division of the Public Works Bureau and the Agricultural Water Resources Bureau were merged to form the "Water Resources Bureau, Taiwan Provincial Construction Department," and this agency was restructured as the "Eighth Engineering Office, Water Resources Bureau, Taiwan Provincial Construction Department."
In June 1947, it was renamed the "Beigang Engineering Office, Water Resources Bureau, Taiwan Provincial Government Construction Department."
In September 1956, following a reorganization of agencies under the Taiwan Provincial Construction Department's Water Resources Bureau, this agency was restructured as the "Fifth Engineering Office, Water Resources Bureau, Taiwan Provincial Construction Department."
In January 1998, with the adjustment of functions and organizational structure of the Taiwan Provincial Government, this agency was restructured as the "Fifth River Bureau, Taiwan Provincial Government."
On July 1, 1999, in response to the streamlining of provincial organizations, it was transferred to the Ministry of Economic Affairs and renamed the "Fifth River Bureau, Water Resources Agency, Ministry of Economic Affairs."
On March 28, 2002, in line with the Water Resources Agency's reorganization into the Water Resources Agency, this agency was restructured as the "Fifth River Bureau, Water Resources Agency, Ministry of Economic Affairs."
On September 26, 2023, in coordination with the reorganization of the Executive Yuan, it was restructured as the "Fifth River Branch, Water Resources Agency, Ministry of Economic Affairs."