This sixth data release report contains available radium-226 and uranium results supplementing the data contained in the previous releases of October 1962, January 1963, July 1963, January 1964, and July 1964. The data indicate evidence of uranium mining and milling from analysis of composite water samples at stations of the Radium Monitoring Network established by the Colorado River Basin Water Quality Control Project. The network is a surveillance system consisting of continuous surface water sampling at 26 locations throughout the basin. It assays the radiological content of river water over the entire basin. Tabular data are presented.