The Environmental Science and Research Foundation conducts an offsite environmental surveillance program for the Department of Energy's Idaho National Engineering and Environmental Laboratory (INEEL). The Foundation's environmental surveillance program monitors the effects, if any, of US Department of Energy (DOE) activities on the offsite environment, collects data to confirm compliance with applicable environmental laws and regulations, and observes any trends in the environmental levels of radioactivity. This report for the third quarter of 1999 is based on 704 samples of air, fine particulates, atmospheric moisture, precipitation, milk, and food. All concentrations of radioactivity found in these samples were consistent with concentrations which have been found in sampling during recent quarters and which have been attributed in the past to natural background radiation, worldwide fallout from past nuclear weapons testing, and nuclear operations around the world. No measured concentrations could be directly attributed to operations at the INEEL. Concentrations in all samples were below the guidelines set by both the DOE and the US Environmental Protection Agency (EPA) for protection of the public.