The phenomenal growth of oxidation lagoons as a form of municipal waste treatment is a reflection of their relatively low cost and ease of maintenance. The widespread acceptance of lagooning was originally predicated on their ability to produce effluent quality at least equivalent to accepted secondary treatment. In the semi-arid Great Plains states where lagoons were originally successful, such efficiencies were easily achieved for most of the year. Unfortunately, differences in climate (especially sunlight and rainfall), soil type, population density and a multitude of diverse problems have worked against such success for other portions of the country. Inventory and operative data from municipal lagoon facilities have been collected and evaluated. The adequacy of such facilities to produce effluent to meet state water quality criteria for receiving waters has been evaluated.