AbstractStabilization ponds have been widely accepted in recent years, following studies that established deeper understanding of the phenomena associated with the stabilization process. A compilation of information on the use of both sewage and industrial ponds is presented showing types and geographical location in the United States. A total of 1,304 stabilization ponds currently are used as the principal method of sewage treatment serving a population of 2,138,085. Ponds are used for tertiary treatment serving a population of 2,146,951, in 343 instances. Use of 827 industrial ponds by 31 industries in 44 States is also indicated. Indiana ranks first in usage with 159 ponds and Callfornia second with 140. Ponds were classed as effective by 66 percent of the 455 users who reported on this item. Of 149 reports on odors, 73% indicated nuisances. Insect problems were reported in only a small number of instances. Data are presented on design considerations and the mechanism of waste stabilization ponds. Aerobic ponds are given greatest emphasis. Photosynthesis and its dependence upon the algal mass, suitable temperature, incident light penetration, nutrient supply, and induced vertical mixing by wind are of prime importance in the stabilization mechanism. Odors are associated with prolonged anaerobic conditions, and these may persist up to 4 weeks following extended ice cover in cold climates, if BOD loadings are 25 lbs. per acre per day or greater. Nitrogen and carbon may be limiting factors in the development of an algal mass. Coliform, BOD, and nutrient removals are presented for various physical, chemical, and climatic conditions. Although fecal streptococci removal averaged 97% in a study pond, they were still discharged in the effluent at a rate of 700,000 per second in winter and 70,000 per second in summer. A striking similarity exists generally among the algal speciation in stabilization ponds, regardless of geographic location. The algal mass is, however, dependent upon unique pond conditions and location, and may vary upwards to nearly 5 million algal cells per milliliter, 34,000 p.p.m. by volume, or 30–35 tons per acre per year. The problem of blue‐green algal mats and resultant pigpen odors in extremely localized areas is duscussed. Midges and midge larvae may have an impact on the nutrient cycle in a stabilization pond, and may pose a potential localized nuisance in some areas. Mosquito problems have usually been associated with growth of aquatic vegetation. Suggestions for minimizing the potential problem are discussed.