Operations and waste disposal activities at the Y-12 Plant, the Oak Ridge National Laboratory (ORNL), and the Oak Ridge Gaseous Diffusion Plant (ORGDP), located on the US Department of Energy (DOE) Oak Ridge Reservation (ORR) in eastern Tennessee, have introduced airborne, liquid, and solid wastes into the surrounding environment. Some of these wastes may affect off-site areas by entering local streams that ultimately drain into the Clinch River. Previously reported concentrations of radionuclides, metals, and organic compounds in water, sediment, and biota of the Clinch River and Watts Bar Reservoir suggest the presence of contaminants of possible concern to the protection of human health and the environment. A preliminary screening was conducted of contaminants in the off-site surface water environments downstream of the DOE ORR. This screening analysis represents part of a scoping phase of the Clinch River Resource Conservation and Recovery Facilities Investigation (CRRFI). The purpose of this preliminary screening analysis is to use existing data on off-site contaminant concentrations to identify and prioritize potential contaminants of concern for further evaluation and investigation. The primary objective of this screening analysis is to ensure that CRRFI sampling and analysis efforts focus on those contaminants that may possibly contribute to human health or environmental risk. 8 refs., 3 figs., 6 tabs