OpenNSPECT is a raster-based GIS model that estimates runoff, pollution and erosion in a GIS setting. NOAA’s National Centers for Coastal Ocean Science (NCCOS) has conducted a series of regional ecological assessments throughout many estuarine and coastal shelf areas of the southeastern U.S. aimed at evaluating condition of living resources and ecosystem stressors in these coastal areas, including NERRS. This project aims to evaluate relationships between modeled levels of water runoff, suspended or dissolved pollutants, and observed pollutant levels in receiving water sediments. The basic assumptions required in this modeling approach are that 1) pollutants are related to land cover type; 2) the concentration of pollutants from a given land cover can be represented by a single value, the event mean coefficient, which can be thought of as the average concentration over the course of all rainfall events that produce runoff; 3) pollutants are carried conservatively downstream, where they are precipitated out and found in the sediments; 4) there are no significant sources of sediment pollutants other than those coming down from upstream lands.