Documented is a computer model that should see extensive use in total-jurisdiction preliminary master planning for abatement of pollution from storm sewer discharges and combined sewer overflows. It is presently the outstanding tool available for that purpose. Water Resources Engineers (WRE) employed the initial version of the model in part of the development of the Department of Public Works, City and County of San Francisco, Master Plan for combined sewer overflow abatement, using 62-years of hourly rainfall data. Examples of planning applications are included, together with samples of computer output for a San Francisco drainage area including summary and event statistics for rainfall, storage, overflow, treatment and quality. Data processing for planning applications is a much more practical consideration than the level of sophistication of hydrological process modeling, just the opposite of the emphasis required for design applications. Related management issues are presented in a companion report.