While deposition is a removal process of pollutants from the atmosphere, it is an intake process of such pollutants to the ground. It is suggested that surface waters in the greater Seoul area, used as a source of drinking water, have been affected by severe air pollution. Lake Paldang is a main resource of drinking water for 20 million people in the greater Seoul area. In this study, dry deposition amounts of nitrogen and sulfur were estimated for three typical days in each season over the watershed of Lake Paldang. Models-3/CMAQ (USEPA Models-3/Community Multi-scale Air Quality) and MM5 (PSU/NCAR Mesoscale Modeling System) were used to predict air quality and meteorology, respectively. Aerosol chemistry as well as gaseous chemistry was considered. The modeling domain was 480 km x 384 km including Greater Seoul Area and watershed of Lake Paldang. The grid size was 12 km x 12 km and the number of grids was 40 in the west-east direction and 29 in the south-north direction. The number of layers in the vertical direction was six to the height of 100 hPa. Emission data were taken from the Center for Global and Regional Environmental Research, University of Iowa for anthropogenic emissions and from GEIA (Global Emissions Inventory Activity) for biogenic emissions. High resolution emission data of 1 km x 1 km were prepared for the greater Seoul area which have significant emission of anthropogenic pollutants. Dry deposition of nitrogen mainly occurred in the form of HNO₃ and was the largest in fall because secondary pollutants transported toward the watershed of Lake Paldang. Contribution of particulate pollutants to nitrogen and sulfur deposition was the largest in winter. Annual dry deposition amount of nitrogen was 3,645 ton and that of sulfur was 1,553 ton over the watershed of Lake Paldang. That is approximately 41% of nitrogen emission and 29% of sulfur emission in the study area on an annual base.