Distribution coefficients were determined for sorption-desorption of radioactive tracers between Nevada Test Site alluvium and alluvial ground water. The order of increasing distribution coefficient by element is: Sb, Sr, U(VI), I, Ru, Nb, Ba, Cs, Co, Y, Ce, and Eu. Some distribution data were also obtained for bentonite. Volatile and refractory debris samples from nuclear tests in tuff, alluvium, and rhyolite were leached with ground water. Most leachable are the volatile species I, Mo, and Sb, which have condensed on chimney rubble. Comparison of the laboratory data with field measurements indicates that leaching is the main process responsible for the presence of radionuclides in water from the site of the underground nuclear test Cambric.