The fertilization of surface waters with excess nutrients may cause massive growths of algae and other aquatic plants and thus serious associated water quality problems. Eutrophication has become a major concern. It is important to determine the factors which affect algal growth and decomposition and how this information can be used to minimize the associated water quality problems. In the research reported, a continuous flow system was used to evaluate algal growth under different growth conditions (light, pH, CO2,...) and to determine the effects of these conditions on the level of mass supported by the particular environment. In the second phase the algal cultures were then decomposed aerobically to determine the rate and extent of decomposition of the algae grown under different environmental conditions. The results from the growth and decomposition studies can be applied to similar natural situations to determine the effect of the algae on the natural water quality. (Author)