Shihmen Reservoir has been operated in nearly half of a century since 1964. In recently years, it caused severe situations for water supply regardless of high water turbidity, as well as the problem of eutrophication of water. The main purpose of this project is to improve the water quality, especially for the eutrophication problems of Shihmen Reservoir. The short-term viable strategies for diminishing pollutants are proposed in this project by researching into the sources of pollution; moreover, the feasibility of management founding by levying clean fee are assessed. According to the demand of EPA, this project also helped to organize a BMP conference.
The results of this study are: (1) the water quality of Shihmen Reservoir was at the mesophication to eutrophication levels in recent years, and the total phosphorus (TP) as the main factors involved. Moreover, the watersheds around Sanmin River and Nanzi Ditch closed to the reservoir and the massive agriculture fields on the hillsides are the hot spots to contribute pollution. (2) The loading ratio of point source pollution to non-point source pollution (NPS) is evaluated to be 15:85 for the pollution of the total phosphorus. The non-point source pollution, 32%, caused by human activities mostly comes from dry farmlands. It pointed out that the pollution caused by human activities must be managed properly. (3) Reducing the point source pollution emitted from the domestic sewage should be based on building the sound infrastructures as a priority programs, such as construction of wastewater sewer systems and establishment of on-site water purification facilities. Furthermore, to promote the low-impact travel can effectively reduce the pollution caused by tourists. (4) Excessive fertilization of crops and surface soil erosion caused by rainstorm are the major source of non-point source pollution. It is effective to practice the optimization of fertilizer management and soil-water conservation to reduce pollution. The structural best management practices (BMPs) can be carried out at hot spots when necessary and they are suggested to set up at the hot spots around the reservoir, as well as monitor the effectiveness of their reduction. (5) In the current lows, there are no laws can be followed directly and immediately to impose cleaning fee for Shihmen Reservoir. The more relevant laws are listed in this study according to different resources of pollution. However, it should first be established by the objects levied and amending the laws for the next stage. (6) Professor introduced the management directions of US EPA for non-point source pollution control in this BMP international conference. Moreover, the Total maximum daily load (TMDL) of pollution was proposed for the reservoirs and watersheds managements.