Two lakes in eastern South Dakota were sampled for plankton and water chemistry from April 1970 through June 1972. These sample results were used with meteorogical data to set up multiple regression analysis of the measured factors that would be expected to effect the abundance of major algae species and major inorganic nutrients. Primary production rates were also measured and the effects of selected inorganic nutrients on production rates were determined. Results of multiple regression analysis by season on algal populations in the deeper of the two lakes showed repeated evidence of nitrogen and phosphorus as important controlling factors. Measurements were made to determine whether the correlations between wind streets and nutrients were determined by increased wind-generated circulation of the water in the lakes or by direct stirring of the bottom sediments by wind-generated action. The conclusion was drawn that efforts to control algae blooms by limitation of incoming nutrient supply would be beneficial in deeper, nutrient-limited lakes but not effective in many of the shallower recreational lakes.