To enhance the reservoir watershed soil conservation and improve its water quality, the Executive Yuan approved “Forward-looking infrastructure development program: The enhancement of reservoir watershed conservation plan”. The purpose of this project is to provide an integrated control action plan for the eutrophication potential reservoirs, Shimen reservoir and Liyutan reservoir. In order to achieve the goal, the tasks of this project include: (1) analyzing the data of the water quality and flow collected from Shimen reservoir watershed and Liyutan reservoir watershed, (2) establishing green technology (e.g. Multi-Soil-Layering System (MSL), biorentation system) for pollutant reduction and developing a plan for implementing nutrients reduction, (3) applying decision-making model for water quality management for reducing point and nonpoint source (NPS) water pollution, and (4) holding several consultation meetings. The water quality of the eutrophication potential reservoirs, Shimen reservoir and Liyutan reservoir, was investigated and evaluated based on the monitoring data in 2018, and the water quality improvement strategies of the reservoir were presented in the project. The results showed that the major pollution load of Dahan creek and Nanzaigou creek is from recreational activities in Shimen reservoir watershed. The point source pollution from the domestic sewage, civilian lodging and leisure farms and agricultural NPS pollution seriously affect the water quality of Liyutan reservoir. The research team also provided guidance for local governments (Kaohsiung City Government, Taoyuan City Government and Miaoli Irrigation Association), and environmental consulting service industry on developing green technology. Nutrients reduction devices (e.g. purification tank, MSL, and biorentation system) were considered and installed in watershed of Agongdian reservoir, Shimen reservoir, Yuanshan weir, and Mingte reservoir. The loading reduction strategies of biochemical oxygen demand (BOD) and the total phosphorus (TP) were developed for Liyutan reservoir. The results indicated that the average annual BOD and TP loading into Liyutan reservoir are 1.34×105 kg / year and 9.29 ×103 kg / year estimated by SWMM/ BASINS. The results showed that an integrated control action plan for both point and nonpoint sources of pollution in the watershed can be developed.

Reservoir, Nutrients, TMDL