copper (Cu) is an essential trace element that can be toxic to aquatic biota at elevated concentrations. Copper enters aquatic systems through aerial deposition or surface runoff. Because of its affinity for particulate matter, mainly fractions of iron, manganese oxides, and organic matter, Cu tends to accumulate in sediments (Campbell and Tessier 1996). Because a variety of organisms live in, or are in contact with, bed sediments, sediments act as an important route of exposure to aquatic organisms. Canadian interim sediment quality guidelines (ISQGs) and probable effect levels (PELs) for Cu can be used to evaluate the degree to which adverse biological effects are likely to occur as a result of exposure to Cu in sediments. Canadian ISQGs and PELs for Cu were