This project carries on water quality monitoring to four kinds of water bodies of ten counties and cities in the northern Taiwan. The changes of water quality to the time and pollution assessment for those water bodies could be provided to the relevant environmental agencies for making a pollution control decision. During the monitoring period, two types of water bodies in the plan, including sea areas and beaches, have been coordinated and managed by the OCA (Ocean Conservation Administration) since 2019, and the monitoring has ceased. For river quality, the 134 sampling sites covering 36 rivers (including main streams and tributaries) were monitored monthly. The monitored results in water quality of rivers and creeks from 2018 to 2021 showed that the water quality in Yilan and Hualien cities was good; a critical difference between upstream and downstream water quality was shown in Danshuei-river; the downstream water quality got a high pollution concentration of organic matter; in Taoyuan and Hsinchu cities, Touchien-stream got the best water quality, the water quality in Nankan-stream, Laochieh-stream, Xinfeng-stream and Keya-stream was worse. As a whole, the highest percentage of the water quality was 51%, it belonged to unpolluted rivers. The secondary percentage of the water quality was 33%, it belonged to intermediately polluted rivers. Overall, water quality in 3 years was nondifference between the recent years. For ocean monitoring, the 40 sampling sites covering 8 coastal areas were monitored quarterly. Since the estuary areas were affected by the river during high tide, the salinity were low, and the concentrations of the inorganic salts were high. The monitored results appeared that Copper was ever found exceeding their relative marine water quality standards in the marine regions. The water quality in eastern sea area was better than in western, Taiwan coastal waters was better than off-shore island waters and estuary. The 9 sampling sites covering 3 beaches were monitored monthly from June to September. 3 beaches except the Fulong beach, others were not ever found exceeding the water quality standard because of the influence of river and rainfall, the water quality of 3 beaches was good. The 140 ground water sampling sites for 8 cities and counties were monitored quarterly. Ground water monitoring results showed that as usual, Ammonia-Nitrogen, Manganese and Iron were the major items against the Ground Water Monitoring Standard in second category. To analyze graphically each monitoring item by Stiff-plotting and Piper-plotting showed a trend as same as last sevesal years, there was no significant difference compared to the past. The highest percentage of Stiff-plotting and Piper-plotting was about 67% and 70%, it belonged to HCO3－- Ca2＋ type and area of I.

Water Quality Monitoring, Water Quality Standards, Method Detection Limit