Levels of radioactivity in the surface waters of the Columbia River Basin are reported, with emphasis on the main stem below the AEC's Hanford Works near Pasco, Washington. Natural radioactivity in the Columbia Basin includes alpha activity which varies with suspended sediment concentrations and beta activity which varies with suspended sediment concentrations and beta activity from potassium-40. Man-made radioactivity is added to surface waters by nuclear detonations and operation of the Hanford Works in the lower Columbia River. From October 1957 to September 1964, gross beta activity transport at Pasco was between 1500 and 5000 curies per day. No significant changes in radioactive loads were revealed during this period.