The project was aimed to monitor the water quality of river, ocean, reservoir and underground waters in six counties located in the central part of Taiwan. The survey program was expected to provide useful data to evaluate current pollution condition of the water systems, to predict the changing trend of quality of the water systems, and furthermore to provide reference information for government to making pollution control policy. As to the river water quality is concerned, the monitoring results show that the rivers located in Chang-hua county and in Yun-lin county were found in relatively high extent of pollution. Among the rivers investigated in 2006, the most polluted rivers are the downstream section of Jhong-Gang river, Wu river, Lu-Gang river and Bei-Gang river. In abundant water seasons, suspended solid was found to be one of the most important factors impacting on the RPI(River Pollution Index) in some water systems, especially in the area of Da-An stream and Lao-Jhuang stream, where the quality of waters is in relatively good condition. For some water systems of relatively poor water quality, it was found that the both the concentration of ammonia nitrogen (NH3-N) and bio-oxygen-demand (BOD) were substantially diluted in abundant water seasons, these happened especially in the downstream of Jhong-Gang river and Hou-Long river, Han river, Lu-Gang stream, SinHuWei stream and Bei-Gang river. In the plum raining season from May to June, higher suspension solid and chemical-oxygen-demand (COD) were observed especially in Da-An river, Da-Jia river, Wu stream and Bei-Gang river. In summary, the quality of water systems in 2006 was found to be somewhat better than in 2005. The monitoring of ocean shows that the water quality of all the 19 stations investigated in 2006 can meet the criteria of category A or B. The salinity measured in 2nd quarter was found obviously lower than other seasons due to heavy raining. The concentration of nitrite nitrogen (NO2-N) in 1st and 4th quarters was found higher compared to that of the past years. We suggest that EPA may need to continue this ocean monitoring program in order to establish the relationship between the concentration change of nitrite nitrogen and high rainfall. The monitoring of three beaches was conducted from June to September in 2006. Among the measured items, colon bacillus and Enterococcus were two specific items frequently exceeding the control criteria. For total of nine consecutive measurements in this monitoring program, the frequency which did not meet the criteria of category A was recorded as in the following：Ci-Ding beach three times, Da-An beach two times and Tong-Siao beach six times, respectively. The monitoring of reservoir water covered eight dams and the frequency was once per quarter. The results obtained in 2006 show that all the eight reserveoirs did not meet the criteria occasionally for some monitoring. The eutrophic level of the Sun-Moon Lake reservoir was the best, but the Da-Pu reservoir was the worst. By summing up ,the monitoring results of reservoirs water,it shows that the percentage of oligotrophe is 25%, mesotrophe is 50%, and eutrophe is 25%,respectively. The water quality of reservoirs in 2006 is found better than in 2005. Finally, the monitoring of groundwater was conducted in six counties covering 85 wells. Among the monitoring items, ammonia nitrogen, iron and manganese were found not meeting the quality criteria of 2nd category. We analyze graphically each monitoring item by Stiff-plotting and Piper-plotting, and the results show that there is no significant difference compared to that of 2005 .

Water Quality Monitoring, Water Quality Standards, Method Detection Limit