The Santa Susana Field Laboratory (SSFL) occupies about 2,850 acres and is located in Ventura County, California. The site is jointly owned by the Boeing Company and the federal government (the National Aeronautics and Space Administration administers the federal portion of the property). Much of the site was historically used as a rocket engine testing and energy research facility from 1949 to 1998. The site stormwater discharges are permitted by the Los Angeles Regional Water Quality Control Board through an individual industrial NPDES permit that includes numeric effluent limits for a wide range of constituents, including dioxins and metals. A large portion of the site uses distributed source stormwater controls with natural treatment systems utilizing chemically active media. As part of this approach, extensive research was conducted to develop a robust media for use in these controls to meet the discharge objectives. This paper describes the development of the media and its characteristics.