Abstarct: Mobarakabad is located in Haraz road which connects Tehran to the Northern provinces, between Abali and Mosha villages. In this area water for drinking and agricultural uses is supplied from wells in karstic and alluvial formations. Spatial study of the water resources in these formations showed that electrical conductivity of groundwater is increased in southern parts. This was assessed to be related to the increase of distance from recharge area and proximity to the Mosha-Fasham Thrust Fault. Water resources with pH values less than annual average are also located in this part. This is probably related to the increase of electrical conductivity which enhances calcite precipitation. Study of the groundwater chemistry of the wells drilled in alluvium and karstic formations indicates temporal enhancement of electrical conductivity due to the increase in discharge and recent droughts. Electrical conductivity is decreased at the first half of the year (dry season) probably due to the snow melting which adds more water and improves groundwater quality. The dominant type of groundwater in Mobarkabad aquifer (alluvial and karstic) is Ca2+-HCO3- in relation to the presence of limestone at the recharge zone. Positive correlation between calcium and bicarbonate also confirms the role of limestones in quality of the groundwater in this region.