The Żuławy Elbląskie area is located in the eastern part of the Vistula River delta. The area is a partly depressed flat, alluvial plain. The monotonous relief of the delta is contrasted by elevations of the Iława Lake District and the Elbląg Upland. From the west the area is bordered by Nogat arm which, along with its Cieplicówka arm and with the Elbląg River constitute the principal part of hydrographic system of the Żuławy. The aquatic system is also strongly influenced by the Drużno Lake. The most part of the Żuławy Elbląskie area must be subjected to the land drainage. Two groundwater horizons are important for water supply: Pleistocene-Holocene (Quaternary sands) and multiage (oldest Pleistocene units, Tertiary sands and Upper Cretaceous carbonates and siliceous sediments). The Żuławy Elbląskie area is recharged laterally from the surronding uplands. The infiltration of meteoric waters is less important due to impermeable cover and intensive drainage through the system of collector trenches, canals and pump stations. Utilization of groundwaters is highly limited by their quality, which deteriorates with the distance from the uplands due to increasing concentration of chloride ion (up to 600 mg Cl/dm3. Another deteriorating factor is the excess of Fe and Mn as well as the increased concentrations of ammonia. The groundwater balance and the assessment of groundwater resources were based upon the modelling studies. Three model variants were considered: Variant 0 - reconstruction of natural position of groundwater table (unexploited groundwaters), Variant 1 - reconstruction of hydrodynamic conditions for 1999 (model revision) and Variant 2 - hydrodynamic prognosis at the optimum exploitation of groundwater intakes. Simulation allowed to determine the total amount of grounwaters involved in recharge and drainage of the Żuławy Elbląskie horizons. Total amount of groundwaters in the Pleistocene-Holocene horizon is 21,090 m3/24 h under natural conditions (Step 0) and 35,040 m3/24 h at maximum exploitation (Step 2). For the multiage horizon the amount of groundwaters under natural conditions (Step 0) is 8,440 m3/24 h and increases 5 times at maximum exploitation (up to 43,900 m3/24 h, Stage 2). The disposable resources obtained from modelling are: 24,000 m3/24 h for Pleistocene-Holocene horizon and 38,400 m3/24 h for multiage horizon.