[en] Oil sand mining, processing and tailings pond leakage has raised concerns about pollution of the Athabasca River. This study investigated 13 elements that are considered to be priority pollutants (PPE) under the United States Environmental Protection Agency's Clean Water Act. In particular, it investigated the oil sand industry's release of those 13 elements via air and water to the Athabasca River and its watershed. The PPEs include Sb, As, Be, Cd, Cr, Cu, Pb, Hg, Ni, Se, Ag, Tl, and Zn. Concern also exists over Sb, As, Cd, Cr, Cu, Pb, Ni, and Se concentrations in water or sediment from the Athabasca River. Snowpack studies in 2008 revealed that all PPEs except selenium were greater near oil sands developments than at more remote sites. Bitumen upgraders and local oil sands development were sources of airborne emissions. Concentrations of Hg, Ni, and Tl in winter and all 13 PPEs in summer were greater in tributaries with watersheds disturbed by development than in less disturbed watersheds. During the summer, concentrations of all PPE in the Athabasca River were greater near developed areas than upstream of development. At sites downstream of development and within the Athabasca Delta, concentrations of all PPEs except Be and Se were greater than upstream of development. Canada's or Alberta's guidelines for the protection of aquatic life were exceeded for 7 PPEs in melted snow or water collected near or downstream of development. It was concluded that contrary to claims made by industry and government, the oil sands industry significantly increases loadings of toxic PPEs to the Athabasca River and its tributaries via air and water pathways. 40 refs., 3 figs.