The Water Environment Federation Stormwater Institute (SWI) needs your help to identify the information and resources municipal separate storm sewer system (MS4) permittees need to run an effective and efficient MS4 stormwater program. This bi-annual survey seeks to understand and quantify the challenges the regulated municipal stormwater community faces, so resource solutions can be directed to fill these gaps. SWI will use the survey results to prioritize future research that will benefit your stormwater program. The MS4 survey is conducted once every two years. The inaugural survey was conducted in May 2018.