Includes bibliographical references. "September 1966." "Presented at the ASCE National Symposium on Quality Standards for Natural Waters, Ann Arbor, Michigan, July 19-22, 1966. Submitted for publication in the Proceedings of the Symposium and in the Journal Sanitary Engineering Division of the American Society of Civil Engineers"--Page 1 "This work was performed while the authors were members of the Division of Water Supply and Pollution Control, Public Health Service, Department of Health, Education, and Welfare"--Page 1