The Eskisehir province is well-known due to its industrial and agricultural activities, which are a threat for the aquatic environment. Hence, monitoring of water quality in the area is of vital importance because of an excess heavy metal contents, especially As. The Porsuk River is heavily polluted by industrial activities from Kutahya city. It discharges into the Porsuk Dam and from there it flows relatively clean to Eskisehir city center, but beyond this point it increasingly deteriorates due to the negative impact of industrial and agricultural activities up to the junction point of Porsuk and Sakarya rivers. Heavy metal concentrations and As contents in surface and ground waters were selected as pollution indicators to examine pollution level and compare an interaction between river and groundwater. For this purpose, water samples taken between 2008 and 2010 from the Porsuk River along the section from the west of Kutahya to the discharge point into the Sakarya River, as well as groundwater samples from the wells located close to or far of the Porsuk River, were evaluated. Based on the obtained results, we found that the Porsuk River, especially at the locations close to the Sakarya River, and groundwater are polluted in terms of heavy metals and As compounds. In conclusion, the heavy metal and As pollution is also observed in the wells close to the locations in which groundwater is fed by the Porsuk River since it acts as an influent river. Thus, surface water is considered as a polluting source of groundwater.