Due to the proposed development of the Green River Oil Shale Formation encompassing the areas of southwestern Wyoming, northeastern Utah, and northwestern Colorado, the EPA Region VIII Headquarters in Denver has a specific need for the development of site-specific ambient dispersion models. To meet this requirement, the Green River Ambient Model Assessment (GRAMA) project was initiated to develop improved air quality models for analyzing the impacts of the oil shale industry with respect to PSD increments over pristine wilderness areas, and ambient air quality standards for criteria pollutants. Two air quality simulation models are currently under development for this complex region. One model, VALMET, is a local-scale model for predicting concentrations of nonreactive pollutants within a well-defined mountain valley configuration. The second model, MELSAR, is a mesoscale Lagrangian puff model for predicting pollutant concentrations within a 500 km by 450 km region. This paper gives a description of the current VALMET model followed by brief explanations of the MELSAR model and the GRAMA field experiments. The paper concludes with a summary of the GRAMA project.