This study is to survey water quality for effluent of industrial zones' wastewater treatment plants, downstream of main streams, and effluent of different industries in Taoyuan agricultural zone, and to investigate the influence of industrial effluent on irrigation water. The results showed that pH values and dissolved oxygen (DO) concentrations for the most sampling points were corresponding to the requirements of irrigation quality standards (pH = 6.0-9.0 and DO > 2.0 mg/L). However, conductivity and total nitrogen (T-N) all would not meet the standards (750 μS/cm and 1.0 mg/L in order). For heavy metals, besides copper (Cu), lead (Pb), and chromium (Cr) of Linkou fourth industrial zone's effluent (not treated), Pb of Kueishan and Linkou third industrial zone's effluent, Cu of Nankan stream would not meet the needs of irrigation quality standards, the other sampling points all reached the current standards. On the other hand, although the maximum of organic carbon isn't specified in the irrigation quality standards, but the study of different industrial effluent indicated that chemical oxygen demand (COD) concentrations of all industries (except transport tools maker) were more than 200 mg/L, which already exceeded the limits of discharge standards for various industrial wastewater. Furthermore, 2509.2 mg/L of COD measured from chemistry/chemical engineering maker should not be neglected. Finally, the investigation of main streams exhibited that Nankan, Puhsin, and Huangchien stream contaminated were more serious than the others.
