Study area is Cheshme-Ali Damghan, one of the main watersheds of Haj-Ali-Gholi subcatchment located in central drainage basin of Iran. Research was carried out via generating needed informative themes, detecting location of water samples and overlaying and interpreting themes. The effect of geological formations on water quality was analyzed after geometric overlaying of themes and assessing water resources distribution. Informative themes included maps of: geology, geological formation sensivity, drainage net, deposits and its bedrock, and water samples. Results showed that the main destructive agent of surface water quality is Neogene marly formations (Ngm) which are mostly expanded over west part of watershed. Also marly formation extension as bedrock of pediment and playa deposits is the main cause of groundwater quality degradation.