The objective of this study was to develop a wet deposition model for Maryland and the Chesapeake Bay watershed that has a greater spatial resolution than is currently possible using NADP wet deposition measurements and available two-dimensional spatial interpolation algorithms. The model incorporates daily precipitation measurements from NOAA/NWS sites located within a 100 km radius of the Chesapeake Bay watershed, topographic variables (e.g., elevation, slope, aspect) that effect the amount and distribution of precipitation across the region, and precipitation chemistry data from the NADP sites within and adjacent to the region to estimate wet deposition. Because of strong coastal influence on climate in some portions of Maryland and the Chesapeake Bay watersheds, a subroutine was added to the model to correct for marine (sea-salt) influence on sulfate concentrations.