Presents findings of a project conducted to determine whether streambed oxygen demand (SOD) rates in the Athabasca River are consistently higher downstream of effluent inputs during winter, how the trend varies throughout the winter, and whether SOD is influenced directly by nutrient loads from effluents. Investigators obtained SOD measurements at 13 locations from upstream of Hinton downstream to the Calling River. The substrates at these locations were mainly coarse, with pebble, cobble, and boulder predominating. Controlling factors affecting SOD are discussed