Anthropogenic materials can enter natural waters through domestic and industrial effluents, agricultural run-off, seepages from surface and sub-surface chemical repositories, atmospheric deposition, and accidental spills. An assessment of the biological effects of chemicals in aquatic environments requires an understanding of the fate of such xenobiotic compounds. Biodegradation may be a principal mechanism which dictates the longevity of chemical pollutants in terrestrial and aquatic environments (Bollag 1974). However, it is the environment that actually controls the biodegradation process and has a greater influence on the process than the microorganisms per se (Kaplan 1979). The present study was conducted to measure and compare the degradation of ten organic chemicals in ground, Lester river and Superior harbor waters by autochthonous microorganisms.