A nationwide assessment has been made of the quantity and quality of urban storm flow emanating from combined sewers, storm sewers, and unsewered portions of all 248 urbanized areas and other urban areas in the United States. Available control alternatives and their associated costs were also determined. Continuous simulation runs using one year of hourly data were made to determine the attainable level of pollution control with a specified availability of storage volume and treatment rate in five cities: Atlanta, Denver, Minneapolis, San Francisco, and Washington, DC. This procedure was used to derive generalized equations relating pollution control to storage and treatment. These results were combined into a simple optimization model which determined the optimal mix of storage and treatment for any feasible level of control for any city. Then the nationwide assessment is presented. The results indicate annual costs ranging from $297 million for 25 percent pollution control to $5,029 million for 85 percent pollution control. The corresponding initial capital investment ranges from $2,476 million for 25 percent control to $41,968 million for 86 percent control. These costs can be reduced significantly if stormwater pollution control is integrated with dry-weather quality control and wet-weather quantity control. Also, the relative impact of wet-weather versus dry-weather flows is illustrated for a case study of Des Moines, Iowa.

"March 1977." The report number appearing on the document, EPA-600/2-77-064, is in error. It should be EPA 600/2-77-064b, per NSCEP's publication title list. "Department of Environmental Engineering Sciences, University of Florida." "Contract No. 68-03-0283." "Project Officer Richard Field." Includes bibliographical references (pages 357-359).