In 2017, the Taiwan Environmantal Protection Administration (Taiwan EPA) carried out the sustainable reservoir management program under the Science and Technology Master Plan 2017-2020 regarding the water environmental investigation and survey for improving the water quality of reservoirs in Taiwan. In order to achieve the goal, the tasks of this project include: (1) analyzing the data of the water quality and flow collected from the Shimen reservoir watershed, (2) intigating climate change adaptation in the water quality management and disasters mitigation strategies, (3) establishing nutrients reduction technologies (e.g. Multi-Soil-Layering System, MSL; Biorentation Cell) and developing the action plans of nutrients reduction implementation, (4) applying decision-making model for water quality management and economic incentive for reducing nonpoint source (NPS) water pollution, and (5) holding several consultation meetings involved. Literature on NPS control practices (Best management practices, BMPS) from USA and Japan was reviewed. The water quality of the eutrophication potential reservoir, Shimen Reservoir, was investigated and evaluated based on the monitoring data in 2017, and the water quality improvement strategies of the reservoir were presented in this project. The Taiwan EPA, the local government of reservoirs, and the experts discussed the water quality improvement strategies and watershed management of the Shimen reservoir during the study. The total phosphorus TMDL and a loading reduction strategy were developed for the Shimen Reservoir. The simulated results indicated that the average annual TP loading into the Shimen Reservoir was 32,014 kg / year, which consists of nonpoint source loading of 27,044 kg / year estimated by SWMM / BASINS, and point source loading of 4,990 kg/ year. It is estimated that the Shimen Reservoir can become the mesotrophic state if its average annual TP loading is reduced by 30.7 % or more. It was proposed that TP reduction implementation in the hot-spot subwatersheds that are likely locations for the LID/BMPs should be developed. Moreover, the results provided the basis on which an integrated control action plan for both point and nonpoint sources of pollution in the watershed can be developed.

Reservoir, Nutrients, TMDL