Releases of radium and uranium into Ralston Creek and Reservoir, Colorado, from uranium mining

Dissolved U concentrations were determined in wastewater from a uranium mine, in water from Ralston Creek upstream from and downstream from the discharge point, and from Ralston Reservoir, located 2.5 mi downstream from the mine. Dissolved U concentrations, in micrograms per liter, were: 1,700 in discharge water; approximately 4 in creek water upstream from the mine; and 600-1,200 in creek water downstream from the mine; and 100 in reservoir water. Dissolved /sup 266/Ra concentrations were less than 2 pCi/L in both the creek and reservoir waters. The concentration of suspended solids in the mine effluent was 6 mg/L. The fact that most of the /sup 266/Ra and U were not displaced by K/sup +/ or Ba/sup +2/ ions indicates that these radionuclides are not absorbed on the particle surfaces but rather are associated with minerals of U ores or are partly trapped inside the colloidal hydroxides of Fe and Mn coated on the sediment