This EPA model is a steady-state Guassian plume model which can be used to assess pollutant concentrations from a wide variety of sources associated with an industrial source complex. This model can account for settling and dry deposition of particulates, downwash, area, line, and volume sources, plume rise as a function of downwind distance, separation of point sources, and limited terrain adjustment. ISCLT is designed to calculate the average seasonal and/or annual ground level concentration or total deposition from multiple continuous point, volume, and/or areas sources. Provision is made for special discrete, X, Y receptor points that may correspond to a sampler sites, points of maxima, or special points or interest. Sources can be positioned anywhere relative to the grid system. For the long term model, input includes stability wind rose (STAR deck), average afternoon mixing height, average morning mixing height, and average air temperature.