This report presents the development of a preliminary priority ranking of potential pollution sources with respect to groundwater quality and the associated pollutants for oil shale operations such as proposed for Federal Prototype Leases U-a and U-b in Eastern Utah. The methodology used includes description of background information and the proposed oil shale operations as potential pollution sources, characteristics of potential pollutants, area water use, the hydrogeologic framework of the project area, and existing water quality. This information base is then used to evaluate the potential mobility of pollutants in the subsurface through consideration of infiltration, and mobility and attenuation processes in unsaturated and saturated zones. These facts lead to the preliminary priority ranking based on the magnitude of the sources; the toxicity, persistence, etc., of the potential pollutants; the mobility of pollutants in the subsurface; and the potential for harm to water users.