This report presents results of an investigation of water and streambed-sediment quality in selected tributaries of the South Umpqua River. Concentrations of inorganic constituents in water (major and minor ions, nutrients, and trace elements) and streambed sediment (primarily trace elements), along with standard field parameters, are tabulated for samples collected at 10 sites. Aqueous trace-element concentrations are compared with U.S. Environmental Protection Agency (USEPA) criterion continuous concentrations for the protection of aquatic life. Streambed-sediment trace-element concentrations are compared with Canadian sediment quality guidelines for the protection of aquatic life and, to provide a frame of reference, with previously collected streambed-sediment data from the Willamette Basin in western Oregon.