Geophysical prospecting is commonly used in solving environmental problems because of time saving, low cost, and nondestructive. The main objective of this study was to investigate the environmental impact assessment of groundwater contamination near El-Dair waste disposal site, west of Sohag city, Egypt to delineate a contaminant plume. The resistivity and self-potential (SP) methods can be helpful complement to geochemical measurements. The correlation between results of 2D electric resistivity tomography and SP method was applied and confirmed by hydro-chemical analysis of groundwater. The probable leachate plume is prolonged to out of disposal sites boundaries, and in general, those plumes have the same directions of the groundwater flow. Three profiles (3 km long) of two-dimensional resistivity tomography and 725 SP data points scattered within the area near and far the disposal site were implemented. Groundwater samples were collected from 13 tubewells at various locations for hydro-chemical analysis. Interpretations of resistivity tomography show a low resistivity zone (\7 X m), which appears to be a fully saturated zone with leachate from an open dumpsite. The results of SP show a large negative SP anomaly (-120 mV) with respect to a reference station taken outside the contaminant plume. SP method supported the results of resistivity method relating contaminated zones in the survey area. There is a good correlation between the geophysical investigations and the results of hydro-chemical analysis. The results of hydro-chemical analysis proved that there are concentrations of heavy metals within the groundwater which were percolated from wastewater disposal.