National Overview of the Municipal Separate Storm Sewer System (MS4) Program: Status and Progress

In fall 2010, the Environmental Protection Agency (EPA) sent information collection request (ICR) questionnaires to more than 600 regulated municipal separate storm sewer systems (MS4s) to help EPA collect information on MS4 program implementation. This ICR represents a comprehensive national data collection on implementation of the MS4 program. A total of 471 regulated MS4s responded to the questionnaires. This paper summarizes the MS4 ICR data, and discusses the results with key differences between Phase I (medium and large) MS4s and Phase II (small) MS4s. The ICR questionnaires primarily focused on post-construction standards and programs in order to collect data to support a potential EPA rulemaking that would address stormwater discharges from newly developed and redeveloped sites. The ICR also asked for information about other aspects of the MS4 program, including public education and involvement, illicit discharges, good housekeeping, retrofits, industrial sources and monitoring. The questionnaires results generally found a high level of implementation in many of the MS4 program areas.