In the process of pursuing economic growth as the national target for a long time, Taiwan has created an economic miracle but sacrificed ecological environmental sources. With increasing higher living standards, more living space is demanded such that providing clean and green spaces along riverbanks in addition to offering security becomes another important mission. In recent years, the global thinking of sustainable development has demanded more ecological and environmental protection such that efficient management of waters along river, drainage and seacoast will be emphasized tasks of watershed management. The main objective of pollution investigation and quantity estimation in Chiang-Chun River watershed is to effectively comprehend the sources of pollution to assist in establishing the water quality model to be used in simulation. The QUAL2E model developed by the US EPA is used to carried out estimating the carrying capacity of Chiang-Chun River, and drafting pollution control measures and waste reduction strategies so that the objective of improving Chiang-Chun River¡¦s water quality can be achieved. Chiang-Chun River has long been subjected to pollutions from industrial and domestic waste discharges resulting in serious water quality deterioration. Additionally the waste discharge from manufacturing plants along the creek has made the pollution even worse. Hence, various environmental protection authorities have actively promoted the checking and controlling industrial and pig-farming wastewater discharges and established a mechanism encouraging local residents to participate in the watershed pollution prevention and control. These measures will not only alleviate the water pollution in Chiang-Chun River with limited resources but also achieve the purpose of communing local residents and the river. V The livestock wastewater is currently treated in three-stage system including solid-liquid separation, anaerobic treatment and aerobic treatment. With good management, the effluent is expected to meet discharge standards. However, since most pig farmers, who may try to save costs, have not efficiently managed the treatment facility so that the treated effluent does not meet the standards. If directly discharged into surface bodies, the improperly treated effluent will cause serious pollution problems. A natural treatment and water purification system is currently being promoted. If implemented in the three-stage treatment system, the natural system (aquatic treatment system) will achieve energy savings, lower the difficulty to operate the treatment system and reduce the operation and maintenance costs. Additionally, effluent quality can be improved such that the possibility of water reuse is also expected. Providing adequate treatment for domestic wastewater requires the construction of sewage system, which is costly and may take a long time to complete. Additionally, since most residents are scattered in the watershed, the construction of conventional sewage system to collect domestic wastewater is not cost-effective. Hence, the natural system, e.g. constructed wetland, is proposed as the major method for treating the wastewater discharged from communities and for achieving water reuse such that multiple-functional benefits can be reached. Additionally, the concept and tasks of water pollution prevention and control can be deeply rooted in the community development so that a community possessing the capability of water self-purification and sustainable application is developed.