Priority trace elements, such as arsenic, selenium, cadmium, chromium, copper, lead, and silver are often present in the aqueous discharges from coal-fired electric power plants. The objective of this 8-year research project was to determine the technical and economic feasibility of removing inorganic trace elements from power plant waste streams by adsorption/coprecipitation with iron oxyhydroxide. Removal of arsenic and selenium from ash pond waters has been emphasized. The project was funded by the Electric Power Research Institute (EPRI) and carried out by the Department of Civil Engineering at Stanford University and Brown and Caldwell Consulting Engineers.