Reservoirs as traditional structures in water resources management system in MAZANDARAN province play a major role in supplying irrigation water for paddy fields. Dredging and improvement of such structures can result in getting more benefits from the surface runoff. In current research, using satellite images and ArcGIS software, land use over the case study area of GATAB, BABOL, Iran, was determined. Then the potential of the surface runoff in the area was estimated by SCS method. Also, irrigation costs for paddies, irrigated by groundwater well (four groundwater wells) and reservoir water (four Reservoirs), were estimated. The effect of dredging and improvement of reservoirs on the reduction of groundwater withdrawal and irrigation costs were evaluated. The potential of runoff in the area was estimated to be 31 MCM (million cubic meters). Dredging of all Reservoirs by 1 to 2 meters would result in the exploitation of 1.68 to 3.37 MCM from the surface runoff. A fall in irrigation cost, estimated to be 991 to 1982 million Rials per Hectare, is a consequent of   more proper utilization of surface runoff. According to the results, the increase in the storage capacity of reservoirs will result in saving part of groundwater storage in the case study area.