Dissolved oxygen modelling for the Athabasca River began in 1987 with very limited historic oxygen and biochemical oxygen demand information. A river monitoring program was designed and implemented in winter 1988, consisting of 2 complete surveys along the Athabasca River and from major tributaries between the Town of Hinton and the Town of Athabasca. This report describes in detail the updated Athabasca River oxygen model calibration, procedures for evaluating future Biochemical Oxygen Demand effluent loading scenarios, and results of a few select scenario evaluations. The complete model input files and graphical model output are also included.