Long-range transport of air pollutants (or LRTAP) is the mechanism by which atmospheric contaminants are transported very long distances to be deposited and affect the environment thousands of kilometers away from the source of the emissions. From investigation of lake sediments, chemical species are known to be transported into the river basins of northern Alberta via atmospheric pathways. The Atmospheric Environment Service (AES) Lagrangian back trajectory model was used to identify the potential atmospheric routes for airborne contaminants to the basin. Back trajectory analysis indicates that the possible source areas are more wide-spread in the closed- water season than in the open-water season as may be expected from climatology. Although there are subtle differences between the seasons, generally, the greatest frequency of air passages are from the northern Pacific Ocean (30 to 40%)and western North America (50 to 65%). There is no direct transport from Mexico or South America, little transport from Europe (0 to 1%) and central Asia (0.5 to 0.7%) or eastern North America (2 to 3%), but more transport from eastern Asia (3 to 4%) including Japan, China and northern Russia.