The objectives of this project were addressed by first identifying common sentinel species immediately upstream and downstream of pulp mill effluents at Hinton and Whitecourt. Spoonhead sculpin and lake chub were identified as sentinel species because of their abundance in the Hinton and Whitecourt reaches of the river, respectively. These species are assumed to have limited mobility and a small home range. This project attempted to document the geographic extent of biochemical responses in fish subjected to prolonged exposures during low flow periods (i.e., fall and early spring). This was accomplished by conducting laboratory analyses on the fish tissues collected from the field to determine the potential for the pulp mill effluents to disrupt sex steroid levels and induce liver MFO activity.