The Muskeg River and its tributaries have been sampled by Alberta Environment between 1972 and 2001. The purpose of this report is to summarize this data, interpret water quality conditions and controlling factors, check for any trends in water quality over the long term, and assess whether any effects of oil sands development are apparent. The intent is to make a scientific contribution to the knowledge and understanding of the Muskeg River system, and of potential oil sands development effects, in view of the level of development proposed for this basin.