Environmental Study of the Sewage Outfall Area at San Clemente Island. An Open-Ocean Sewage Disposal Model

An environmental-impact study of the San Clemente Island sewage discharge site was used as a model to predict the effects of dumping raw sewage into the open ocean. Coliform bacterial counts, used to assess water sanitary quality, showed that the water at distances greater than several hundred feet from the outfall was within standards for swimming beaches. Biological surveys revealed that plant and animal life was noticeably altered only within about 50 ft from the discharge. Dye-diffusion studies and dissolved-oxygen measurements demonstrated that normal ocean mixing is adequate to prevent oxygen depletion under open-ocean conditions. From an esthetic standpoint, odors and floatable solids were insignificant. The San Clemente Island findings were extrapolated to gauge the effect of ship sewage discharges in the open ocean, with completely harmless results predicted.