This project mainly focuses on monitoring the water quality and quantity of major reservoirs, the other reservoirs, and major Rivers on Taiwan’s main and outlying islands, and collects the survey data to hold water-quality trends and provide environmental protection department of pollution control reference. A total of 23 monitoring sites on major rivers flowing into 21 reservoirs were investigated, some of the measured values at each site did not meet Surface Water Classification and Water Quality Standards during the monitoring period. Among them, the Coliform group accounted for the highest proportion (56%), followed by BOD5 (44%). Most of the levels of The River Pollution Index (RPI) were non/mildly-polluted, indicating good water qualities. In addition, Songlin Bridge was lightly- to moderately-polluted and Baishuixi Bridge was non/mildly- to lightly-polluted due to the high SS caused by geological factors and rainfall, respectively. The water quality of Mirror No. 2 Bridge and Xinjian Bridge was occasionally slightly poor resulted in non/mildly-polluted levels. The Gangxi pumping station had low dissolved oxygen and high organic pollutants, which is moderately-polluted. Regarding 30 major reservoirs, each reservoir had monitoring sites that do not meet Category A and Category B of Surface Water Classification and Water Quality Standards during the monitoring period. The dissolved oxygen had the highest proportion exceeding the standard (20%), followed by pH (19%) and total phosphorus (16%). During the monitoring period, the Sun Moon Lake Reservoir had better water quality, with the level of eutrophication ranging from oligotrophic to mesotrophic (47%, 53%). The Xinshan Reservoir, Deji Reservoir, Wushe Reservoir, and Hushan Reservoir ranged from oligotrophic to eutrophic, with a high proportion of mesotrophic (67% ~ 87%). The eutrophication level of Shimen Reservoir, Baoshan Reservoir, Yongheshan Reservoir, Liyutan Reservoir, Lantan Reservoir, Renyitan Reservoir, Zengwen Reservoir, Wushantou Reservoir, Nanhua Reservoir, Chengqing Lake Reservoir, Agongdian Reservoir,and Mudan Reservoir is between mesotrophic to eutrophic, with a higher proportion of mesotrophic (50% ~ 97%). The Baihe Reservoir had the highest rate of eutrophic at 97%. Mingde Reservoir, Jingmian Reservoir, and Fengshan Reservoir were all eutrophic (100%), indicating poor water quality. Compared with previous data, the water quality of Hushan Reservoir has slightly improved. The water quality of Mingde Reservoir, Yongheshan Reservoir, Liyutan Reservoir, Deji Reservoir, Sun Moon Lake Reservoir, Wushe Reservoir, Lantan Reservoir, Riyuetan Reservoir, Zengwen Reservoir, Baihe Reservoir, Jingmian Reservoir had deteriorated slightly. In 21 general reservoirs, each reservoir had some monitoring sites that do not meet Category A and Category B of Surface Water Classification and Water Quality Standards. The proportion of pH exceeding the standard is the highest (41%), followed by total phosphorus (28%). Among the general reservoirs on the main island of Taiwan, the eutrophication levels of Xishi Reservoir, Baoer, and Toushe Reservoir ranged from mesotrophic to eutrophic. The Xishi and Baoer reservoirs had relatively high proportions (60%, 56%) of mesotrophic. Toushe Reservoir had a higher proportion (60%) of eutrophic. The Dapu Reservoir all belong to eutrophic (100%). Reservoirs on outlying islands such as Kinmen County, Lianjiang County, and Penghu County had generally poor water quality due to the low reservoir capacity. The eutrophication levels of Lake Lanhu in Jinmen County ranged from mesotrophic to eutrophic (10%, 90%), and the other 10 reservoirs were all eutrophic (100%). The eutrophication levels of Houwo Reservoir in Lianjiang County ranged from oligotrophic to eutrophic, with eutrophic accounting for a higher proportion (90%). Jinsha and Tung Chung all belong to eutrophic (100%), and the remaining reservoirs ranged from mesotrophic to eutrophic, with eutrophic accounting for a higher proportion (60%~100%). The water quality of Xi'an Reservoir in Penghu County was better, the eutrophication levels ranged from mesotrophic to eutrophic (80%, 20%), and the remaining reservoirs were all eutrophic (100%). Compared with previous data, the water quality of Dapu Reservoir, Toushe Reservoir and Jinmen County Water Storage Woxia dam had deteriorated slightly.The water quality of Kinmen County Qingtian, Lan Lake, Lianjiang County Dongyong, and Penghu County Hsi-An Reservoir has slightly improved.

Water quality, Reservoir, Carlson trophic state index , Major reservoir,Major River