Twenty organic chemical substances(Table 2) were isolated from untreated wastewater, as well as treated wastewater, collected at 76 companys of 9 industry group located in the basin of Youngsan River. Those organic compounds were analyzed by Gas Chromatography/Mass Spectrometry(GC/MS) and confirmed through comparison with each standard reagents. Phenol, which was not detected in the raw wastewater, was identified in the effluent of treatment facility, indicating that phenol is generated from isopropylbenzene of plant wastewater.