The determination of optimal station location for the measurement of flow and water quality in streams is crucial in environmental, agricultural, and ecological studies. The objective of this study is to determine these optimal locations for the stream flow and water quality in the Southeastern Anatolia Project (GAP) region of Turkey using the Digital Elevation Model (DEM) and the Geographic Information System (GIS). The results indicated that for the entire area a total of 98 gauging stations are required for reliable measurements of flow and water quality in the streams. When the results were compared with the current stations, only 12 gauging stations out of 54 were in appropriate locations. These results suggest that increasing the number of stations is recommended for accurate determination of regional conditions and changes.