The prime objectives of the survey were: To determine plankton population in various areas of the Missouri River Basin during the summer months; To learn something of the physical, chemical and biological conditions of importance to plankton production and distribution during this period; To define problem areas; To gain an over-all picture of ecological conditions affecting algal growth in the Basin; and To observe the effects of impoundment upon plankton production whereever reservoirs were already in operation in the Basin. Author Modified Abstract)