This study investigated the occurrence of nonylphenol (NP) and 17beta-estradiol equivalent quotient (EEQ) concentrations in Kaoping River and two of its tributaries in Taiwan. During this study 44 water samples were collected from four sampling campaigns. Concentrations of NP in these samples ranged from 0.19 to 183.4 mug/L; EEQ ranged from less than limit of detection (1.41) to 32.2 ng-E2/L. NP concentrations in the main watercourse ranged from 0.19 to 9.21 mug/L; EEQ ranged from less than limit of detection to 2.13 ng-E2/L. These values are comparable to most rivers worldwide. The Wulo Creek tributary was polluted by animal waste discharges and the NP concentrations ranged from 0.72 to 6.8 mug/L. The EEQ ranged from 3.86 to 32.2 ng-E2/L. The Niouchou Creek tributary was polluted with domestic wastewater. Concentrations of NP ranged from 8.79 to 183.4 mug/L and EEQ ranged from 2.94 to 27.8 ng-E2/L. These data suggest that both inadequately treated livestock and human wastewater can cause high NP and EEQ concentrations.