There are approximately 7,250 permitted Municipal Separate Storm Sewer Systems (MS4s), including large and small MS4s that exist nationwide, operating under a National Pollutant Discharge Elimination System (NPDES) MS4 permit. The NPDES MS4 permit requires, permittees to develop and implement a comprehensive Storm Water Management Program (SWMP) that must include pollution prevention measures, treatment or removal techniques, monitoring, use of legal authority, and other appropriate measures to control the quality of storm water discharged to the storm drains and thence to waters of the United States. In 2003, EPA, Region 6, randomly selected MS4s, in cooperation with the States of Arkansas, Louisiana, Oklahoma, New Mexico and/or Texas to audit their SWMP for compliance with the permit. EPA, Region 6, has launched the MS4 Self-Assessment Modules to increase MS4 participation in storm water management and to collect more specific information [Clean Water Act, 33 U.S.C. § 1318(a)], on how the MS4 has implemented their SWMP to comply with the permit. Full copies of the Modules are viewable online and available for download to your computer. If you are a permitted MS4 that has recently received a letter from EPA to participate in the MS4 Self-Assessment, you should download all the Modules from this website, that apply to the programs you have implemented. Follow the instructions given in the letter and Introduction Module (MS4 Self-Assessment 0) for completing and returning each Module. For technical assistance, send an email to Carol Johnson or call (214)-665-8471.