This report presents the results of gamma radiation surveys conducted by the Office of Radiation Programs at twenty inactive uranium mill sites in the Western United States. The purpose of these surveys was to measure the extent to which radioactive material had been spread into the environment from the sites by the action of wind and/or water erosion, and by milling activities. The results indicate that hundreds of acres of land exclusive of the tailings piles have been contaminated to above-background levels. Some of the contaminated land is private, off-site property. Survey techniques were developed to locate the spread radioactive materials and to estimate the gamma exposure rates resulting from them. These measurements were complicated by the presence of direct gamma radiation from the tailings piles. Iso-exposure rate lines were located around each site and plotted on site maps to facilitate site decontamination decisions.