Currently, a systematic monitoring of pesticides in small rivers is not stipulated by authorities in Germany although it is assumed that pesticide concentrations can reach acute toxic levels after runoff from agricultural fields and input from urban activities1. In order to extend the data base on pesticide pollution in small rivers, a national two-year monitoring program at about 180 sites has been initiated. The analytical determination of 111 pesticides and pesticide metabolites in water samples is part of our project contribution. (H)UPLC-tandem mass spectrometry is the method of choice for trace detection of the mostly polar pesticides and metabolites. Additionally, analyses of passive samplers (Chemcatcher) are included to develop and evaluate this method together with the Department of Ecological Chemistry at UFZ.